CN118401787A - Ventilation device, air conditioning system, ventilation method, and ventilation system - Google Patents

Abstract

The ventilation device includes: a compressor; a1 st heat exchanger; a1 st air flow path for supplying air introduced from the outside to the indoor space after passing through the 1 st heat exchanger; a2 nd heat exchanger; a2 nd air flow path for exhausting air introduced from the indoor space to the outside after passing through the 2 nd heat exchanger; a refrigerant circuit connected to the compressor, the 1 st heat exchanger and the 2 nd heat exchanger through refrigerant pipes, and having a refrigerant flowing therein; and a control unit. The control unit detects whether or not a predetermined criterion indicating the possibility of frosting of the 2 nd heat exchanger is satisfied while the 2 nd heat exchanger functions as an evaporator, and controls the temperature of the refrigerant flowing through the 2 nd heat exchanger to be a temperature at which frosting of the 2 nd heat exchanger is not performed when the predetermined criterion is detected to be satisfied.

Description

Ventilation device, air conditioning system, ventilation method and ventilation system

Technical Field

The invention relates to a ventilation device, an air conditioning system, a ventilation method and a ventilation system.

Background technique

Conventionally, there is known a ventilation and air conditioning device that ventilates the room by means of an exhaust fan and an air supply fan, blows outdoor air into the room after heat exchange with a refrigerant through a first heat exchanger, and discharges indoor air to the outside after heat exchange with a refrigerant through a second heat exchanger (see Patent Document 1 and Patent Document 2).

＜Prior Art Documents＞

＜Patent Documents＞

Patent Document 1: (Japan) Patent No. 5076745

Patent Document 2: (Japanese) Patent Publication No. 3-20573

Summary of the invention

<Problems to be Solved by the Invention>

The ventilation and air conditioning device described in Patent Document 1 proposes a technique for suppressing frost formation on the second heat exchanger by preheating air before supplying the air to the second heat exchanger using a preheating heater. However, various methods are conceivable as a method of suppressing frost formation.

An object of the present invention is to suppress frost formation and to continue ventilation operation.

<Methods for problem solving>

The present invention provides a ventilation device, comprising:

compressor;

The first heat exchanger functions as a condenser or an evaporator;

The first air flow path supplies air introduced from the outside to the indoor space after passing through the first heat exchanger;

The second heat exchanger functions as a condenser or an evaporator;

a second air flow path for exhausting the air introduced from the indoor space to the outside through the second heat exchanger;

a refrigerant circuit, formed by connecting the compressor, the first heat exchanger, and the second heat exchanger via a refrigerant pipe, and having refrigerant flowing therein; and

The control unit detects whether a prescribed criterion indicating the possibility of frost on the second heat exchanger is satisfied while the second heat exchanger functions as an evaporator, and controls the temperature of the refrigerant flowing in the second heat exchanger to a temperature at which frost is not formed on the second heat exchanger if the prescribed criterion is detected to be satisfied.

According to this ventilator, by controlling the temperature of the refrigerant when a predetermined criterion is satisfied, frost formation is suppressed, and the ventilation operation of supplying air to the indoor space and exhausting air to the outdoors can be continued.

Regarding the ventilation device, it may also be that:

The control unit detects whether a prescribed criterion indicating the possibility of frost on the second heat exchanger is satisfied while the second heat exchanger functions as an evaporator, and outputs a signal for controlling the air conditioner installed in the indoor space in order to control the temperature of the refrigerant flowing in the second heat exchanger when the prescribed criterion is detected to be satisfied.

According to this ventilation device, the air conditioner is operated according to the signal to adjust the temperature of the indoor space, and frost formation is suppressed by controlling the temperature of the refrigerant, thereby realizing efficient frost suppression.

Regarding the ventilation device, it may also be that:

The control unit outputs a signal indicating that a temperature currently set in the air conditioner is to be increased to the air conditioner installed in the indoor space when the predetermined criterion is satisfied.

According to this ventilation device, the air conditioner raises the temperature of the indoor space in response to the signal to raise the temperature of the refrigerant to suppress frost formation, thereby achieving effective frost suppression.

Regarding the ventilation device, it may also be that:

The refrigerant circuit has a bypass pipe, and while the second heat exchanger functions as an evaporator, the refrigerant flows into the second heat exchanger through the bypass pipe without passing through the first heat exchanger.

The control unit controls the refrigerant compressed by the compressor to flow into the second heat exchanger via the bypass pipe when the predetermined criterion is satisfied.

According to this ventilator, by allowing the refrigerant to flow into the second heat exchanger via the bypass pipe, frost formation is suppressed by raising the temperature of the refrigerant, thereby achieving efficient frost suppression.

The ventilation device may further include:

a third air flow path for passing air introduced from a room in the indoor space different from the second air flow path through the second heat exchanger; and

The first guide mechanism switches whether to guide the air to the second heat exchanger via the third air flow path.

The control unit controls the first guide mechanism to guide the air to the second heat exchanger via the third air flow path when the predetermined criterion is satisfied.

According to this ventilator, since the air is guided to the second heat exchanger via the third air flow path, frost formation is suppressed by increasing the temperature of the refrigerant flowing through the second heat exchanger, and thus frost formation can be suppressed efficiently.

Regarding the ventilation device, it may also be that:

The ventilation device further includes a second ventilation unit that adjusts the amount of air flowing into the second heat exchanger via the second air flow path.

The control unit controls the second ventilation unit to increase the amount of air flowing into the second heat exchanger when the predetermined criterion is satisfied, compared with a time before the predetermined criterion is satisfied.

According to this ventilator, the amount of air flowing through the second heat exchanger is increased to raise the temperature of the refrigerant flowing through the second heat exchanger to suppress frost formation, thereby achieving efficient frost formation suppression.

The ventilation device may further include:

a plurality of said second heat exchangers; and

The second ventilation unit corresponding to each of the second heat exchangers,

The control unit, during the period when the plurality of second heat exchangers function as evaporators and when the prescribed benchmark is satisfied, controls the second ventilation unit corresponding to any one of the plurality of second heat exchangers to increase the amount of air flowing in the second heat exchanger compared to before the prescribed benchmark is satisfied.

According to this ventilation device, the second ventilation unit increases the amount of air flowing through the second heat exchanger, thereby raising the temperature of the refrigerant flowing through the second heat exchanger to suppress frost formation, thereby achieving efficient frost suppression.

Regarding the ventilation device, it may also be that:

The control unit, while controlling the second ventilation unit corresponding to any one of the plurality of second heat exchangers to increase the amount of air, controls the second ventilation units corresponding to other second heat exchangers among the plurality of second heat exchangers to reduce the amount of air flowing in the second heat exchanger compared to before the prescribed benchmark is met.

According to this ventilator, the comfort of the living space can be maintained by adjusting the total amount of exhausted air.

Regarding the ventilation device, it may also be that:

The ventilation device further includes a first ventilation unit that adjusts the amount of air flowing into the first heat exchanger through the first air flow path.

The control unit, when controlling the second ventilation unit corresponding to any one of the plurality of second heat exchangers to increase the air volume, controls the first ventilation unit to increase the air volume flowing in the first heat exchanger compared to before the prescribed benchmark is met, based on the increased air volume in the second ventilation unit.

According to this ventilator, when the air volume of the second air supply unit increases, the air volume of the first ventilator is also increased to adjust the air volume of supply and exhaust, thereby maintaining the comfort of the living space.

The ventilation device may further include:

a first ventilation unit that adjusts the amount of air flowing into the first heat exchanger through the first air flow path; and

The second ventilation unit adjusts the amount of air flowing into the second heat exchanger through the second air flow path.

When the control unit receives a signal indicating a defrost operation from an air conditioner installed in the indoor space during the period when the second heat exchanger functions as an evaporator, the control unit deems that the prescribed criterion is satisfied, and controls the first ventilation unit to increase the amount of air flowing into the first heat exchanger, and at the same time controls the second ventilation unit to increase the amount of air flowing into the second heat exchanger, compared to before the prescribed criterion is satisfied.

According to this ventilating device, when the air conditioner performs the defrosting operation, the air volumes of the first ventilating unit and the second ventilating unit are increased, thereby suppressing a decrease in heating performance and maintaining the comfort of the living space.

The ventilation device may further include:

a bypass flow path for guiding the air after heat exchange in the first heat exchanger to the second heat exchanger; and

The second guide mechanism switches whether to guide the air to the second heat exchanger via the bypass flow path.

The control unit controls the second guide mechanism to guide the air to the second heat exchanger via the bypass flow path when the predetermined criterion is satisfied.

According to this ventilator, air is introduced to the second heat exchanger via the bypass flow path, so that the temperature of the refrigerant flowing through the second heat exchanger is increased to suppress frost formation, thereby achieving efficient frost formation suppression.

Regarding the ventilation device, it may also be that:

The ventilation device further includes a second ventilation unit that adjusts the amount of air flowing into the second heat exchanger via the second air flow path.

The control unit stops the compressor and controls the second ventilation unit to flow the air passing through the second air flow path toward the second heat exchanger when the predetermined criterion is satisfied.

According to this ventilator, after stopping the compressor, air is caused to flow to the second heat exchanger, thereby raising the temperature of the refrigerant flowing through the second heat exchanger to suppress frost formation, thereby achieving highly efficient frost suppression.

The ventilation device may further include:

a plurality of said second heat exchangers; and

a second ventilation unit corresponding to each of the second heat exchangers,

The refrigerant circuit further includes a first valve portion for adjusting the opening degree of a flow path flowing into the second heat exchanger for each of the second heat exchangers.

The control unit, when the temperature-related information detected from the plurality of second heat exchangers satisfies the prescribed criterion, controls the plurality of first valve units corresponding to the second heat exchangers that satisfy the prescribed criterion to close in a prescribed order, and controls the second ventilation unit corresponding to the second heat exchanger that satisfies the prescribed criterion to allow air passing through the second air flow path to flow into the second heat exchanger.

According to this ventilator, by closing the valve portions in a predetermined order, it is possible to suppress the refrigerants in the plurality of second heat exchangers from being stopped at the same time, thereby maintaining the comfort of the living space.

The ventilation device may further include:

a first ventilation unit that adjusts the amount of air flowing into the first heat exchanger through the first air flow path; and

The second ventilation unit adjusts the amount of air flowing into the second heat exchanger through the second air flow path.

The control unit controls the first ventilation unit and the second ventilation unit so that the amount of air exhausted to the outside through the second air flow path becomes larger than the amount of air supplied to the indoor space through the first air flow path when the predetermined reference is satisfied.

According to this ventilator, since the amount of air flowing into the second heat exchanger increases, the temperature of the refrigerant flowing through the second heat exchanger rises, and frost formation is suppressed, thereby achieving efficient frost suppression.

Regarding the ventilation device, it may also be that:

The control unit controls the first heat exchanger so that the temperature of the air after passing through the first heat exchanger becomes lower than a temperature set in the air conditioner installed in the indoor space when the predetermined criterion is satisfied.

According to this ventilator, since the temperature of the refrigerant flowing into the second heat exchanger rises, efficient frost suppression can be achieved.

Regarding the ventilation device, it may also be that:

A plurality of combinations of the compressor, the first heat exchanger, the second heat exchanger, the refrigerant circuit, and a second ventilation unit corresponding to the second heat exchanger,

The control unit, when the temperature-related information detected from the plurality of second heat exchangers satisfies the prescribed criterion, controls the compressors corresponding to the second heat exchangers that satisfy the prescribed criterion to stop in a prescribed order, and controls the second ventilation unit corresponding to the second heat exchanger that satisfies the prescribed criterion to allow air passing through the second air flow path to flow into the second heat exchanger.

According to this ventilator, the comfort of the living space can be maintained by suppressing the simultaneous stop of the refrigerants in the plurality of second heat exchangers.

The ventilation device may further include:

a first housing accommodating the first heat exchanger and at least a portion of the first air flow path; and

a second housing accommodating the second heat exchanger and at least a portion of the second air flow path;

The first housing and the second housing are separable.

According to this ventilation device, since the first housing and the second housing are separable, the arrangement layout becomes easy and the burden at the time of installation can be reduced.

Regarding the ventilation device, it may also be that:

The control unit performs control to reduce the rotation speed of the compressor compared to before the predetermined criterion is satisfied, when the predetermined criterion is satisfied.

According to this ventilator, since the temperature of the refrigerant flowing through the second heat exchanger increases by reducing the rotation speed of the compressor, efficient frost suppression can be achieved.

Regarding the ventilation device, it may also be that:

The refrigerant circuit further comprises a second valve portion, which is disposed between the first heat exchanger and the second heat exchanger and is used to adjust the opening of the flow path.

The control unit performs control to increase the opening degree of the second valve unit compared to before the predetermined criterion is satisfied, when the predetermined criterion is satisfied.

Regarding the ventilation device, it may also be that:

The ventilator further includes a third valve portion, wherein when the second heat exchanger functions as an evaporator, the third valve portion is located downstream of the second heat exchanger in the refrigerant flow in the refrigerant circuit.

Furthermore, when the second heat exchanger functions as an evaporator and the predetermined criterion is satisfied, the control unit performs control to tighten the third valve unit compared to before the predetermined criterion is satisfied.

The ventilation device may further include:

The third heat exchanger functions as a condenser or an evaporator;

a third air flow path for exhausting the air after heat exchange between the outdoor air and the refrigerant flowing in the third heat exchanger to the outside of the room;

In addition to the compressor, the first heat exchanger, and the second heat exchanger, the refrigerant circuit further includes the third heat exchanger connected via the refrigerant pipe.

The present invention provides an air conditioning system, comprising:

A ventilator having a first heat exchanger functioning as a compressor and a condenser or an evaporator during heat recovery ventilation operation, a first air flow path for supplying air introduced from the outside to an indoor space after passing through the first heat exchanger, a second heat exchanger functioning as a condenser or an evaporator, a second air flow path for exhausting air introduced from the indoor space to the outside after passing through the second heat exchanger, and a refrigerant circuit in which the compressor, the first heat exchanger, and the second heat exchanger are connected by a refrigerant pipe and a refrigerant flows therein;

an air conditioner having a third heat exchanger functioning as a condenser or an evaporator, and an air conditioner indoor unit for discharging air in the indoor space after heat exchange between the air in the indoor space and the refrigerant flowing in the third heat exchanger to the indoor space; and

A control unit detects whether a prescribed criterion indicating the possibility of frost on the second heat exchanger is satisfied, and when detecting that the prescribed criterion is satisfied, controls the temperature of the refrigerant flowing in the second heat exchanger to a temperature at which the second heat exchanger is not frosted, or controls the operation for removing frost on the second heat exchanger after the second heat exchanger is frosted, based on the power consumption of the ventilation device and the air conditioner required for controlling the temperature of the refrigerant flowing in the second heat exchanger to a temperature at which the second heat exchanger is not frosted, and the power consumption required for operating the ventilation device and the air conditioner for removing frost on the second heat exchanger after the second heat exchanger is frosted.

According to this air conditioning system, by controlling the temperature of the refrigerant while satisfying a predetermined standard, effective suppression of frost formation can be achieved.

The present invention provides a ventilation method, wherein:

When controlling a ventilation device having a first heat exchanger functioning as a compressor, a condenser or an evaporator, a first air flow path for supplying air introduced from the outside to an indoor space after passing through the first heat exchanger, a second heat exchanger functioning as a condenser or an evaporator, a second air flow path for exhausting air introduced from the indoor space to the outside after passing through the second heat exchanger, and a refrigerant circuit formed by connecting the compressor, the first heat exchanger and the second heat exchanger through a refrigerant pipe and having a refrigerant flowing therein, it is detected whether a prescribed criterion indicating the possibility of frost on the second heat exchanger is satisfied while the second heat exchanger functions as an evaporator, and when it is detected that the prescribed criterion is satisfied, the temperature of the refrigerant flowing in the second heat exchanger is controlled to be a temperature at which frost is not formed on the second heat exchanger.

According to this ventilation method, by controlling the temperature of the refrigerant while satisfying a predetermined standard, efficient frost suppression can be achieved.

The present invention provides a ventilation system, comprising:

A refrigerant circuit comprising a compressor, a first heat exchanger and a second heat exchanger connected by a refrigerant pipe and having a refrigerant flowing therein; an air supply fan for supplying outdoor air to indoor air via the first heat exchanger; an exhaust fan for exhausting the indoor air to the outdoor air via the second heat exchanger; and a control unit, wherein the control unit starts the compressor while the second heat exchanger functions as an evaporator, and performs a first control for increasing the low pressure of the refrigerant circuit when it is determined that the low pressure of the refrigerant circuit, the evaporating temperature of the second heat exchanger, the indoor temperature, or the outdoor temperature is lower than a first threshold value related to the low pressure of the refrigerant circuit, the evaporating temperature of the second heat exchanger, the indoor temperature, or the outdoor temperature.

According to this ventilation system, in the ventilation system including the refrigerant circuit capable of recovering heat energy from exhaust gas, when the second heat exchanger is made to function as an evaporator, it is possible to ensure that the compressor is continuously operated.

Regarding the ventilation system, preferably,

The refrigerant circuit includes a discharge pipe of the compressor, a bypass pipe connected to the second heat exchanger or a liquid pipe connected to the second heat exchanger, and a valve provided in the bypass pipe, and the control unit opens the valve in the first control state.

In this case, the high-temperature and high-pressure gas refrigerant can be supplied to the second heat exchanger in the first control state. Therefore, frost formation on the second heat exchanger can be suppressed.

Regarding the ventilation system, preferably,

The control unit, when the valve is opened, closes the valve upon determining that the low pressure of the refrigerant circuit, the saturation temperature of the second heat exchanger, or the intake air temperature of the second heat exchanger exceeds a second threshold value related to the low pressure of the refrigerant circuit, the saturation temperature of the second heat exchanger, or the intake air temperature of the second heat exchanger.

In this case, when the condition for causing the second heat exchanger to function as an evaporator is satisfied during execution of the first control, the first control can be terminated.

Regarding the ventilation system, preferably,

The control unit causes the second heat exchanger to take in air having a temperature higher than a second threshold value related to the intake air temperature in the first control state.

In this case, during the execution of the first control, air having a temperature higher than the second threshold value can be caused to flow into the second heat exchanger. This can suppress frost formation on the second heat exchanger.

Regarding the ventilation system, preferably,

The control unit adjusts the blowing direction of the air supply fan in the first control state so as to guide the air blown out from the air supply fan to the suction side of the exhaust fan.

In this case, during execution of the first control, air having a temperature higher than the second threshold value can be caused to flow into the second heat exchanger.

Regarding the ventilation system, preferably,

The ventilation system further includes an air conditioner that performs air conditioning in the room, and the control unit drives the exhaust fan when the air temperature in the room becomes higher than the second threshold value due to conditioning by the air conditioner in the first control state.

In this case, during execution of the first control, air having a temperature higher than the second threshold value can be caused to flow into the second heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration example of a ventilator and an air conditioner according to Embodiment 1. FIG.

FIG. 2 is a flowchart showing frost suppression control performed by the exhaust unit of the ventilation device according to Embodiment 1. FIG.

FIG. 3 is a diagram showing a configuration example of a ventilator and an air conditioner according to a third modification of the first embodiment.

FIG. 4 is a diagram showing a configuration example of a ventilator and an air conditioner according to Embodiment 2. FIG.

FIG. 5 is a diagram showing a refrigerant circuit according to Modification 1 of Embodiment 2. FIG.

FIG. 6 is a diagram showing a configuration example of a ventilation device, an air conditioner, and a host control device according to a third embodiment.

7 is a sequence diagram showing a flow of processing performed among the host control device, the ventilation device, and the air conditioner when the defrosting operation of the air conditioner according to Embodiment 3 is started.

8 is a timing chart showing a flow of processing performed among the host control device, the compressor unit, and the exhaust unit group when there is a possibility of frost formation on each exhaust unit group in Embodiment 4. FIG.

FIG. 9 is a diagram illustrating an arrangement of a device group including a host control device according to the seventh embodiment.

FIG. 10 is a diagram illustrating an arrangement of a device group including a host control device according to the eighth embodiment.

FIG. 11 is a diagram illustrating a refrigerant circuit according to Embodiment 11. FIG.

FIG. 12 is a diagram illustrating a refrigerant circuit according to a modified example of Embodiment 11. FIG.

FIG. 13 is a flowchart showing the processing procedure of the upper control device of the twelfth embodiment.

FIG. 14 is a schematic structural diagram of a ventilation system according to an embodiment.

FIG. 15 is a control block diagram of a ventilation system according to an embodiment.

FIG. 16 is a flowchart showing the operation of the ventilation system according to one embodiment.

FIG. 17 is a schematic configuration diagram of a ventilation system according to Embodiment 13. FIG.

FIG. 18 is a schematic configuration diagram of a ventilation system according to a fourteenth embodiment.

FIG. 19 is a schematic configuration diagram showing the installation state of the ventilation system of Embodiments 14 and 15 in a building.

FIG. 20 is a schematic configuration diagram of a ventilation system according to a fifteenth embodiment.

FIG. 21 is a schematic configuration diagram of a ventilation system according to a sixteenth embodiment.

FIG. 22 is a schematic configuration diagram of a ventilation system according to a seventeenth embodiment.

FIG. 23 is a schematic configuration diagram of a ventilation system according to Embodiment 18. FIG.

Detailed ways

Hereinafter, the ventilation device, air conditioning system, ventilation method and ventilation system of the present embodiment will be described with reference to the drawings. In addition, the following embodiments are essentially preferred examples and do not limit the present invention, its application objects or the scope of its application.

(Implementation Method 1)

Fig. 1 is a diagram showing a configuration example of a ventilator and an air conditioner according to Embodiment 1. The example shown in Fig. 1 is an air conditioning system including a ventilator 1 and an air conditioner 2 for performing air conditioning of an indoor space.

In this embodiment, as an example of an indoor space, a living space R11 and a ceiling back space R12 are used for explanation, but the indoor space is not limited to the living space R11 and the ceiling back space R12, as long as it is an internal space of a building, for example, it may also have an underfloor space.

The living space R11 is, for example, an office or a living room in a house. The ceiling back space R12 is a space adjacent to the upper part of the living space R11. Since the ceiling back space R12 is located above the living space R11, warm air tends to gather therein.

The air conditioner 2 includes an outdoor unit 70 and two air conditioner indoor units 81 and 82. The number of air conditioner indoor units in the present embodiment is not limited to two, and may be one or three or more.

The air conditioner 2 is a device that performs a vapor compression refrigeration cycle and cools or heats the living space R11. The air conditioner 2 of this embodiment is a device that can perform both cooling and heating operations on the living space R11. However, this embodiment is not limited to an air conditioner that can perform both cooling and heating, and for example, it can also be a device that can only cool.

The outdoor unit 70 and the two air conditioner indoor units 81 and 82 are connected by a communication pipe F5. The communication pipe F5 includes a liquid refrigerant communication pipe and a gas refrigerant communication pipe (not shown). Thus, a refrigerant circuit in which the refrigerant circulates between the outdoor unit 70 and the two air conditioner indoor units 81 and 82 is realized. When the refrigerant circulates in the refrigerant circuit, a vapor compression refrigeration cycle is performed in the air conditioner 2.

The outdoor unit 70 is disposed outdoors and includes a heat exchanger, and discharges air to the outdoors after exchanging heat with a refrigerant flowing through the heat exchanger.

The air conditioner indoor units 81 and 82 have a heat exchanger, and blow the air after heat exchange with the refrigerant flowing in the heat exchanger to the living space R11. In the present embodiment, the air conditioner indoor units 81 and 82 are ceiling-mounted indoor units arranged on the ceiling of the living space R11. In particular, the air conditioner indoor units 81 and 82 of the present embodiment are ceiling-embedded air conditioner indoor units, and the air after heat exchange is blown out from the ventilation ports 93A and 93B. In the present embodiment, an example in which the ventilation ports 93A and 93B are arranged on the ceiling is described, but there is no particular limitation on the setting position of the ventilation ports 93A and 93B. In addition, the air conditioner indoor units 81 and 82 are not limited to the ceiling-embedded type, but may also be ceiling-suspended type. In addition, the air conditioner indoor units 81 and 82 may also be wall-mounted or floor-standing air conditioner indoor units other than ceiling-mounted types.

The ventilator 1 includes an exhaust unit 10 , an air supply unit 20 , a compressor unit 50 , refrigerant circuits F1 , F2 , F3 , and F4 , a supply air passage P1 , and a return air passage P2 .

The ventilator 1 is a device that supplies introduced outdoor air to the living space R11 and exhausts air introduced from the indoor space (including the living space R11) to the outside. Thus, the ventilator 1 realizes air exchange in the living space R11.

Furthermore, the ventilator 1 of the present embodiment performs heat exchange between the exhaust unit 10 and the supply unit 20 , thereby suppressing the temperature difference between the temperature of the air introduced from the outside and the temperature of the living space R11 .

The air supply passage P1 (an example of the first air flow passage) is a passage for supplying air introduced from the outside to the living space R11 from the ventilation port 92 after passing through the air supply unit 20 having the first heat exchanger 22. In this embodiment, an example in which the ventilation port 92 is provided on the ceiling is described, but the installation position of the ventilation port 92 is not particularly limited.

The return air flow path P2 (an example of the second air flow path) is a flow path for discharging the air (return air) introduced from the ventilation port 91 of the living space R11 to the outside through the exhaust unit 10 having the second heat exchanger 12. This embodiment describes an example in which the ventilation port 91 is provided on the ceiling, but the installation position of the ventilation port 91 is not particularly limited.

In the return air flow path P2 of this embodiment, in order to be able to introduce air from a plurality of rooms, the air introduction destination is divided into two branches, which are respectively called the first return air branch path P2A (an example of the second air flow path) and the second return air branch path P2B (an example of the third air flow path).

The first return air branch (an example of the second air flow path) P2A is an air flow path provided for exhausting the air introduced from the living space R11 to the outside through the exhaust unit 10 having the second heat exchanger 12. The first return air branch P2A introduces air from the ventilation port 91 provided on the ceiling of the living space R11. In addition, the present embodiment describes an example in which the ventilation port 91 is provided on the ceiling, but it may also be provided at other locations such as under the floor or on the wall.

The second air return branch (an example of the third air flow path) P2B is an air flow path provided to exhaust the air introduced from the ceiling back space R12 to the outside after passing through the exhaust unit 10 having the second heat exchanger 12. The second air return branch P2B of this embodiment is described as an example of the ceiling back space R12 as a room of the air introduction target different from the first air return branch P2A. However, the air introduction target is not limited to the ceiling back space R12, but may also be the underfloor space. In this way, the air introduction target of the second air return branch P2B can be any room in the indoor space that is different from the living space R11.

In addition, an opening and closing damper 40 is provided at the front end portion of the second return air branch. The opening and closing damper 40 is usually in a closed state. Moreover, the opening and closing damper 40 (an example of the first guide mechanism) can adjust the amount of air introduced from the ceiling back space R12 through control performed by the control unit 13 provided in the exhaust unit 10 via the signal line S2.

The refrigerant circuits F1, F2, F3, and F4 are circuits in which refrigerant flows by connecting the compressor unit 50, the first heat exchanger 22 of the air supply unit 20, and the second heat exchanger 12 of the air exhaust unit 10 via refrigerant pipes.

The control unit 52 of the compressor unit 50, the control unit 23 of the air supply unit 20, and the control unit 13 of the exhaust unit 10 are connected by the signal line S1 shown by the dotted line in FIG. 1. Thus, information can be sent and received between the control unit 52 of the compressor unit 50, the control unit 23 of the air supply unit 20, and the control unit 13 of the exhaust unit 10. The processing shown in the control units 13, 23, and 52 shown below can be implemented by the CPU reading the program (not shown), or can be implemented by hardware wiring. The same is true in the control unit and the upper control device shown in the following embodiments.

The compressor unit 50 includes a driving motor 51 and a control unit 52, and controls the circulation of the refrigerant in any of the refrigerant circuits F1, F2, F3, and F4 by compressing the refrigerant in the refrigerant circuits F1, F2, F3, and F4. For example, when the second heat exchanger 12 in the exhaust unit 10 functions as an evaporator, the compressor unit 50 compresses the refrigerant in the refrigerant circuit F2 to circulate the refrigerant in the refrigerant circuits F1, F2, F3, and F4.

The driving motor 51 is a motor for rotating (driving) a compressor that compresses refrigerant.

The control unit 52 controls the internal structure of the compressor unit 50. For example, the control unit 52 outputs a command to the driving motor 51 to rotate (drive) the compressor.

The air supply unit 20 includes a fan 21, a first heat exchanger 22, a control unit 23, and a temperature detection unit 24, and introduces outside air (OA) to supply air (SA) to the living space R11.

The fan 21 has a function of supplying (SA) the introduced outside air (OA) to the living space R11.

The first heat exchanger 22 functions as a condenser or an evaporator.

The temperature detection unit 24 detects the outdoor air temperature, the surface temperature of the first heat exchanger 22 , and the temperature of the refrigerant flowing through the first heat exchanger 22 .

The control unit 23 controls the internal structure of the air supply unit 20. The control unit 23 performs various controls based on the detection result of the temperature detection unit 14. For example, the control unit 23 adjusts the function of the first heat exchanger 22 as a condenser or an evaporator based on the detection result of the temperature detection unit 24.

The exhaust unit 10 includes a fan 11, a second heat exchanger 12, a control unit 13, and a temperature detection unit 14, and introduces return air (RA) from the living space R11 and exhausts it to the outside (EA).

The fan 11 has a function of exhausting return air (RA) introduced from the living space R11 to the outside (EA).

The second heat exchanger 12 functions as a condenser or an evaporator.

The temperature detection unit 14 detects the indoor temperature, the surface temperature of the second heat exchanger 12, and the temperature of the refrigerant flowing in the second heat exchanger 12. Furthermore, the indoor temperature to be detected includes, for example, the temperature of the air in the living space R11 and the temperature of the air in the ceiling back space R12 via the sensor unit (not shown).

The control unit 13 controls the internal structure of the exhaust unit 10. The control unit 13 performs various controls based on the detection result of the temperature detection unit 14. For example, the control unit 13 adjusts the function of the second heat exchanger 12 as a condenser or an evaporator based on the detection result of the temperature detection unit 14.

Furthermore, the control unit 13 of the present embodiment controls the opening and closing damper 40 based on the detection result of the temperature detection unit 14, thereby being able to adjust the amount of air introduced from the ceiling rear space R12.

The processing performed by the ventilator 1 when the temperature is low will be described. When the temperature is low, the ventilator 1 heats the outside air (OA) introduced from the outside in the air supply unit 20 and then supplies air to the living space R11 (SA), and cools the return air (RA) introduced from the living space R11 in the exhaust unit 10 and then exhausts air to the outside (EA). That is, the first heat exchanger 22 in the air supply unit 20 functions as a condenser, and the second heat exchanger 12 in the exhaust unit 10 functions as an evaporator. The second heat exchanger 12 functions as an evaporator, which lowers the temperature of the refrigerant flowing in the second heat exchanger 12, so there is a possibility that the second heat exchanger 12 freezes (frosts). In this regard, in this embodiment, control is performed to avoid freezing (frost) of the second heat exchanger 12 or to prevent frost from growing when frost is assumed. In the embodiments described below, at least one of the control to avoid frost and the control to suppress frost growth when frost is assumed is referred to as control to suppress frost.

Specifically, the control unit 13 of the exhaust unit 10 determines whether the predetermined reference indicating the possibility of frost (freeze) of the second heat exchanger 12 is satisfied based on the detection result of the temperature detection unit 14 during the period when the second heat exchanger 12 functions as an evaporator. As the predetermined reference indicating the possibility of frost (freeze) of the second heat exchanger 12, for example, it may be a reference for determining whether the outdoor temperature detected by the temperature detection unit 14 is below 0 degrees. In addition, in the present embodiment, the predetermined reference is not limited to whether the outdoor temperature is below 0 degrees, and it may also be a reference for determining whether the outdoor temperature is the minimum operating temperature of the second heat exchanger 12.

In addition, the prescribed reference may not be a reference based on the temperature of the outside air. For example, whether the surface temperature of the second heat exchanger 12 is below a prescribed temperature (e.g., 0 degrees) may be used as a judgment reference. As another example, whether the temperature of the refrigerant flowing in the second heat exchanger 12 is below a prescribed temperature (e.g., 0 degrees) may be used as a judgment reference. In the description shown below, examples of prescribed references are shown, but any reference may be used as long as it is a reference that indicates the possibility of frost (freezing) of the second heat exchanger 12. For example, as shown in the embodiment described below, it may also be used as a reference for determining whether the low pressure of the refrigerant circuits F1, F2, F3, and F4 is lower than a prescribed pressure threshold.

In this embodiment, an example of obtaining the temperature of the outside air or the surface temperature of the second heat exchanger, etc., and determining whether the obtained temperature meets the prescribed benchmark is described. However, this embodiment represents an example of information to be obtained, and the information to be obtained only needs to be information that can determine whether the prescribed benchmark is met. For example, in addition to the temperature of the outside air, the surface temperature of the second heat exchanger 12, the temperature of the refrigerant, or the pressure of the refrigerant, etc. can also be obtained. In addition, this information can also be combined to determine whether the prescribed benchmark is met. In addition, the embodiments and modified examples shown below also represent an example of information obtained, and any information can be used as long as it can determine whether the prescribed benchmark is met.

The control unit 13 of the exhaust unit 10 of the present embodiment, when it is determined that the prescribed criterion is satisfied, controls the opening and closing damper 40 as a control to suppress the frosting of the second heat exchanger 12, so that the air existing in the ceiling back space R12 is guided to the second heat exchanger 12 via the second return air branch P2B as a control to suppress the frosting of the second heat exchanger 12. That is, since the ceiling back space R12 exists above the living space R11, warm air is concentrated there. Therefore, when there is a possibility of frosting of the second heat exchanger 12, the control of opening and closing damper 40 is performed. Through this control, the air after the warm air existing in the ceiling back space R12 and the air existing in the living space R11 are mixed is guided to the second heat exchanger 12.

The controller 13 of this embodiment controls warm air in the ceiling back space R12 to flow to the second heat exchanger 12 as an example of control to increase the temperature of the refrigerant flowing through the second heat exchanger 12. This can suppress frost formation on the second heat exchanger 12.

FIG. 2 is a flowchart showing frost suppression control performed by exhaust unit 10 of ventilation device 1 according to the present embodiment.

The control unit 13 of the exhaust unit 10 acquires the temperature of the outside air from the temperature detection unit 14 ( S1201 ).

The control unit 13 of the exhaust unit 10 determines whether a predetermined criterion indicating the possibility of freezing of the second heat exchanger 12 is satisfied based on the acquired temperature of the outside air (S1202).

When the control unit 13 of the exhaust unit 10 determines that the predetermined criterion is not satisfied (S1202: No), the control unit 13 of the exhaust unit 10 ends the processing without performing any special processing.

On the other hand, when the control unit 13 of the exhaust unit 10 determines that the predetermined criterion is satisfied (S1202: YES), it obtains the temperature of the air in the ceiling back space R12 and the temperature of the air introduced from the living space R11 from the temperature detection unit 14 (S1203).

The control unit 13 of the exhaust unit 10 determines whether the temperature of the air in the ceiling back space R12 is higher than the temperature of the air in the living space R11 (S1204). When the control unit 13 determines that the temperature of the air in the ceiling back space R12 is lower than the temperature of the air in the living space R11 (S1204: No), the control unit 13 does not perform the control related to the opening and closing of the damper 40 and ends the process. In addition, when the control related to the opening and closing of the damper 40 is not performed, the control for suppressing frost described in the following embodiment and modified example may be performed.

On the other hand, when the control unit 13 determines that the air temperature of the ceiling rear space R12 is higher than the air temperature of the living space R11 (S1204: Yes), it performs control to open the damper 40 (S1205).

In the present embodiment, by the above-described processing sequence, when the second heat exchanger 12 is likely to be frosted, the air in the ceiling rear space R12 where air warmer than the living space R11 exists is guided to the second heat exchanger 12 .

That is, the temperature of the air flowing through the second heat exchanger 12 increases, and thus it is possible to increase the temperature of the refrigerant flowing through the second heat exchanger 12. Thus, the possibility of frost formation on the second heat exchanger 12 can be reduced.

(Variation 1 of Implementation Example 1)

In the first embodiment described above, as an example of controlling the temperature rise of the air flowing through the second heat exchanger 12, a method of reducing the possibility of frosting of the second heat exchanger 12 by guiding the air of the ceiling back space R12 to the second heat exchanger 12 is described. However, the method of controlling the temperature rise of the air flowing through the second heat exchanger 12 is not limited to the method of guiding the air of the ceiling back space R12 to the second heat exchanger 12, and other methods may also be used. In this regard, in a modified example 1 of the first embodiment, an example of raising the temperature (room temperature) of the air in the living space R11 by controlling the air conditioner 2 is described.

In this modification, the control unit 13 of the exhaust unit 10 and the control unit 71 of the outdoor unit 70 are connected via a signal line. Thus, the control unit 71 of the outdoor unit 70 can output a control signal to the control unit 13 of the exhaust unit 10 .

In addition, in this modification, as a method of transmitting and receiving information between the control unit 13 of the exhaust unit 10 and the control unit 71 of the outdoor unit 70, an example of connection through a signal line is described. However, the method of transmitting and receiving information is not limited to the example of connection through a signal line, and control signals may be transmitted and received through a higher-level control device (not shown), or through a cloud service or server connected via a public network.

Furthermore, the control unit 13 of the exhaust unit 10 of the present modification detects whether or not a predetermined criterion indicating the possibility of freezing of the second heat exchanger 12 is satisfied while the second heat exchanger 12 functions as an evaporator.

When it is determined that the predetermined reference is satisfied, the control unit 13 outputs a control signal to the control unit 71 of the outdoor unit 70 of the air conditioner 2 to increase the temperature currently set in the living space R11 in order to increase the temperature of the refrigerant flowing in the second heat exchanger 12. In this modified example, the temperature of the air flowing in the second heat exchanger 12 can be increased by increasing the air temperature in the living space R11, and thus the temperature of the refrigerant flowing in the second heat exchanger 12 can be increased.

In this way, the control unit 13 in this modified example outputs a control signal to the control unit 71 to increase the currently set temperature of the living space R11 as an example of control to increase the temperature of the refrigerant flowing in the second heat exchanger 12. As a result, the room temperature of the living space R11 increases, and warm air flows into the second heat exchanger 12, so that the temperature of the refrigerant flowing in the second heat exchanger 12 can be increased, and frost formation in the second heat exchanger 12 can be suppressed.

In addition, this modification example describes an example in which a control signal for increasing the currently set temperature of the living space R11 is output to the control unit 71 of the outdoor unit 70 of the air conditioner 2. However, the control signal output to the control unit 71 of the outdoor unit 70 of the air conditioner 2 in this modification example is not limited to a control signal for increasing the currently set temperature of the living space R11, and any control signal may be used as long as it is a control signal for increasing the temperature of the refrigerant flowing in the second heat exchanger 12. For example, the control unit 13 may also output a control signal for increasing the air volume in order to circulate the air in the living space R11.

(Variation 2 of Implementation Example 1)

The first embodiment and the modified example are not limited to the above method. Therefore, in the modified example 2 of the first embodiment, a method of controlling the fan 11 to suppress frost formation will be described.

The control unit 13 of the exhaust unit 10 of the present modification determines whether or not a predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied while the second heat exchanger 12 functions as an evaporator.

When the control unit 13 determines that the prescribed criterion is satisfied, in order to increase the temperature of the refrigerant flowing in the second heat exchanger 12, the control unit 13 controls the fan 11 (an example of the second ventilation unit) to increase the amount of air flowing in the second heat exchanger 12 compared to before the prescribed criterion is satisfied.

Thus, the control unit 13 of this modification outputs a control signal to the fan 11 (an example of the second ventilation unit) to increase the amount of air flowing in the second heat exchanger 12 compared to before the predetermined reference is satisfied, as an example of control to increase the temperature of the refrigerant flowing in the second heat exchanger 12. As a result, the amount of warm air flowing in the second heat exchanger 12 increases, so that the temperature of the refrigerant can be increased, and frost formation in the second heat exchanger 12 can be suppressed.

Furthermore, if the fan 11 is controlled to increase the amount of air flowing through the second heat exchanger 12 , the pressure in the living space R11 may become negative. Therefore, the control unit 13 may output a control signal for increasing the air volume of the fan 21 to the control unit 23 of the air supply unit 20 .

(Variation 3 of Implementation Example 1)

The first embodiment and the modified examples are not limited to the above-described method. Therefore, in the modified example 3 of the first embodiment, a method of providing a bypass flow path for directly flowing air between the air supply unit and the exhaust unit will be described.

Fig. 3 is a diagram showing a configuration example of a ventilator and an air conditioner according to a modification example 3 of the first embodiment. In the example shown in Fig. 3, a ventilator 1A and an air conditioner 2 are provided to perform air conditioning of an indoor space. In this modification example, the same reference numerals are given to the same configurations as those in the first embodiment, and their descriptions are omitted here.

As shown in Fig. 3, a bypass flow path P102 is provided between the air supply unit 20 and the exhaust unit 110. The bypass flow path P102 is composed of a first bypass partial flow path P102A closer to the air supply unit 20 than the supply flow path P101, a third bypass partial flow path P102C closer to the exhaust unit 110 than the return flow path P103, and a second bypass partial flow path P102B connecting the first bypass partial flow path P102A and the third bypass partial flow path P102C.

In addition, an opening and closing damper 140 is provided on the second bypass partial flow path P102B. The opening and closing damper 140 is usually in a closed state. In addition, the opening and closing damper 140 (an example of a second guide mechanism) can guide the air heated by the air supply unit 20 directly to the exhaust unit 110 according to the control of the control unit 113 provided in the exhaust unit 110 via the signal line S3.

After the air supply unit 20 introduces the outside air (OA), it usually supplies air (SA) to the living space R11 through the first bypass partial flow path P102A and the supply air flow path P101.

The exhaust unit 110 includes a fan 11, a second heat exchanger 12, a control unit 113, and a temperature detector 14. Return air (RA) of the living space R11 is introduced through the return air flow path P103 and the third bypass partial flow path P102C and exhausted to the outside (EA).

The control unit 113 of the exhaust unit 110 of the present modification detects whether or not a predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied while the second heat exchanger 12 functions as an evaporator.

When it is determined that the predetermined criterion is satisfied, the control unit 13 performs control to open the damper 140 in order to increase the temperature of the refrigerant flowing through the second heat exchanger 12 .

As described above, the control unit 113 in this modification performs control to open the damper 140 as an example of control to increase the temperature of the refrigerant flowing in the second heat exchanger 12, so as to guide the air to the second heat exchanger 12 through the bypass flow path P102. As a result, the air heated by the exhaust unit 110 can flow directly to the second heat exchanger 12, so that the second heat exchanger 12 can be prevented from frosting.

(Implementation Method 2)

In the above-described embodiment and modification, an example is described in which the temperature of the refrigerant flowing in the second heat exchanger 12 is increased by adjusting the air flowing in the second heat exchanger 12. However, other methods may be used as a method of increasing the temperature of the refrigerant flowing in the second heat exchanger 12. Therefore, in this embodiment, a method of increasing the temperature of the refrigerant by controlling the refrigerant flowing in the second heat exchanger 12 is described.

Fig. 4 is a diagram showing a configuration example of a ventilator and an air conditioner according to Embodiment 2. In the example shown in Fig. 4, a ventilator 1B and an air conditioner 2 are provided to perform air conditioning of an indoor space. In the configuration of this embodiment, the same reference numerals are given to the same configurations as those in Embodiment 1, and their description is omitted here.

The control unit 52 of the compressor unit 50, the control unit 23 of the first air supply unit 220A, the control unit 23 of the second air supply unit 220B, and the control unit 213 of the exhaust unit 210 are connected by a signal line S201 indicated by a dotted line. Thus, information can be sent and received between the control unit 52 of the compressor unit 50, the control unit 23 of the first air supply unit 220A, the control unit 23 of the second air supply unit 220B, and the control unit 213 of the exhaust unit 210.

The ventilator 1B includes an exhaust unit 210 , a first air supply unit 220A, a second air supply unit 220B, a compressor unit 50 , refrigerant circuits F1 , F2 , F3 , and F4 , a first air supply passage P201 , a second air supply passage P202 , and a return passage P203 .

The first air supply passage P201 (an example of a first air flow passage) supplies air introduced from the outside to the living space R11 from the ventilation port 92A after passing through the first air supply unit 220A having the first heat exchanger 22 .

The second air supply passage P202 (an example of the first air flow passage) supplies air introduced from the outside to the living space R11 from the ventilation port 92B after passing through the second air supply unit 220B having the first heat exchanger 22 .

The return air flow path P203 (an example of a second air flow path) exhausts the air introduced from the indoor space to the outside of the room after passing through the exhaust unit 210 including the second heat exchanger 12 .

The first air supply unit 220A and the second air supply unit 220B include a fan 21, a first heat exchanger 22, a control unit 23, and a temperature detection unit 24, and take in outside air (OA) and supply air (SA) to the living space R11.

The exhaust unit 210 includes a fan 11, a second heat exchanger 12, a control unit 213, and a temperature detection unit 14, and introduces return air (RA) from the living space R11 and exhausts it to the outside (EA).

The control unit 213 of the exhaust unit 210 controls the internal structure of the exhaust unit 210. For example, the control unit 213 outputs a control signal to the control unit 52 of the compressor unit 50 based on the detection result of the temperature detection unit 14.

The processing performed by the ventilation device 1B when the air temperature is low is described. As in the above embodiment, the first heat exchanger 22 of the first air supply unit 220A and the second air supply unit 220B functions as a condenser, and the second heat exchanger 12 in the exhaust unit 210 functions as an evaporator. By making the second heat exchanger 12 function as an evaporator, the temperature of the refrigerant flowing in the second heat exchanger 12 is reduced, so that the second heat exchanger 12 may be frosted. Here, in this embodiment, control is performed to suppress the frosting of the second heat exchanger 12.

Specifically, the control unit 213 of the exhaust unit 210 determines whether a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the detection result of the temperature detection unit 14 during the period when the second heat exchanger 12 functions as an evaporator. As a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12, for example, a reference for determining whether the temperature of the refrigerant detected by the temperature detection unit 14 is below 0 degrees may be used. In addition, the predetermined reference in the present embodiment is not limited to a reference based on the temperature of the refrigerant, and may also be used as a reference for determining whether the pressure of the refrigerant is below a predetermined pressure.

In addition, the predetermined reference may not be based on the temperature or pressure of the refrigerant, but may be based on the temperature of the outside air or the surface temperature of the second heat exchanger 12, for example.

The control unit 213 of the exhaust unit 210 of this embodiment, when it is determined that the prescribed standard is met, outputs a control signal to the control unit 52 of the compressor unit 50 to reduce the number of revolutions of the compressor compared to before the prescribed standard is met as a control to suppress frost on the second heat exchanger 12.

Furthermore, the control unit 52 of the compressor unit 50, upon receiving the control signal, outputs a control signal to the drive motor 51 for driving the compressor, which reduces the number of revolutions of the compressor compared to before the predetermined reference is satisfied. As described above, the rotation speed of the compressor is reduced. As a result, the pressure of the refrigerant flowing through the refrigerant circuits F1, F2, F3, and F4 is reduced, and thus the temperature (evaporation temperature) of the refrigerant flowing through the second heat exchanger 12 can be increased.

The control unit 213 of this embodiment outputs a control signal to the control unit 52 of the compressor unit 50 to reduce the number of revolutions of the compressor compared to before the predetermined reference is satisfied as an example of control to increase the temperature of the refrigerant flowing through the second heat exchanger 12. This can suppress frost formation on the second heat exchanger 12.

(Variation 1 of Implementation Example 2)

In Embodiment 2, an example of increasing the temperature (evaporation temperature) of the refrigerant flowing in the second heat exchanger 12 by reducing the number of revolutions of the compressor is described. However, the method of increasing the temperature (evaporation temperature) of the refrigerant flowing in the second heat exchanger 12 is not limited to the method of reducing the number of revolutions of the compressor. Therefore, in Modification 1, an example of providing a bypass flow path (an example of a bypass pipe) in the refrigerant circuit is described. This Modification 1 is also provided with two air supply units and one exhaust unit, as in Embodiment 2.

Fig. 5 is a diagram showing a refrigerant circuit of a modification 1 of embodiment 2. In the example shown in Fig. 5, the flow of the refrigerant when the second heat exchanger 12 of the exhaust unit 310 functions as an evaporator is shown. In addition, the same reference numerals are given to the same structures as those in the above embodiments, and their description is omitted here.

In the example shown in FIG. 5 , air supply units 320A and 320B, an exhaust unit 310 , and a compressor unit 350 are provided.

The air supply units 320A and 320B include a fan 21 , a first heat exchanger 22 , a control unit 23 , a temperature detection unit 24 , a drive motor 25 , and an electric valve 26 .

The driving motor 25 is controlled by the control unit 23 to control the air volume of the fan 21 .

The electric valve 26 functions as an expansion valve for decompressing the refrigerant, and switches whether to decompress the refrigerant according to the control of the control unit 23. The electric valve 26 functions so as to decompress the refrigerant when the first heat exchanger 22 functions as an evaporator, and does not decompress the refrigerant when the first heat exchanger 22 functions as a condenser.

The exhaust unit 310 includes a fan 11 , a second heat exchanger 12 , a control unit 313 , a temperature detection unit 14 , a drive motor 15 , and an electric valve 16 .

While the second heat exchanger 12 functions as an evaporator, the control unit 313 determines whether a predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the detection result of the temperature detection unit 14. The predetermined criterion is the same as that in the second embodiment, and its description is omitted.

When determining that a predetermined criterion is satisfied, the control unit 313 of the exhaust unit 310 of this modification outputs a control signal for causing the refrigerant to flow to the bypass flow path F6 to the control unit 352 of the compressor unit 350 as a control to suppress frost formation on the second heat exchanger 12 .

The driving motor 15 is controlled by the control unit 313 to control the air volume of the fan 11 .

The electric valve 16 functions as an expansion valve for decompressing the refrigerant, and switches whether to decompress the refrigerant according to the control of the control unit 313. The electric valve 16 functions in a manner that decompresses the refrigerant when the second heat exchanger 12 functions as an evaporator and does not decompress the refrigerant when the second heat exchanger 12 functions as a condenser.

The compressor unit 350 is provided with a driving motor 51 , a control unit 352 , a compressor 53 , a four-way valve 54 , an electric valve 55 , and a bypass electric valve 56 .

The compressor 53 compresses the refrigerant flowing in the refrigerant circuit.

The driving motor 51 is an actuator for driving the compressor 53. The driving motor 51 of the present embodiment drives the compressor 53 at a rotation speed controlled by the control unit 352.

The control unit 352 controls the internal structure of the compressor unit 350. For example, the control unit 352 controls the drive motor 51 and the four-way valve 54 as described below.

The four-way valve 54 functions as a valve for switching the outflow destination of the refrigerant compressed by the compressor 53 from the refrigerant circuit F1 and the refrigerant circuit F4. For example, when the second heat exchanger 12 functions as an evaporator under the control of the control unit 352, the four-way valve 54 switches the refrigerant compressed by the compressor 53 to flow to the refrigerant circuit F1.

The electric valve 55 functions as a valve for performing opening and closing control of the refrigerant circuit under the control of the control unit 352. When the second heat exchanger 12 functions as an evaporator, the electric valve 55 is in a closed state in which no refrigerant flows.

In this modification, when the second heat exchanger 12 functions as an evaporator, in order to increase the temperature of the refrigerant flowing in the second heat exchanger 12 , a bypass flow path F6 is provided for allowing the refrigerant compressed by the compressor 53 to flow directly into the second heat exchanger 12 .

The bypass flow path F6 is provided as a flow path for bypassing the refrigerant between the compressor 53 and the four-way valve 54 and between the refrigerant circuit F3. That is, the bypass flow path F6 functions as a pipe for allowing the refrigerant to flow to the second heat exchanger 12 without passing through the first heat exchanger 22 while the second heat exchanger 12 functions as an evaporator.

The bypass electric valve 56 functions as a valve that switches whether or not the refrigerant flows into the bypass flow path F6 according to control from the control unit 352 .

Specifically, first, when determining that a predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied, the control unit 313 of the exhaust unit 310 outputs a control signal for causing the refrigerant to flow to the bypass flow path F6 to the control unit 352 of the compressor unit 350 .

Furthermore, when receiving a control signal for causing the refrigerant to flow into the bypass flow path F6 from the control unit 313 of the exhaust unit 310, the control unit 352 of the compressor unit 350 controls the bypass electric valve 56 to be in an open state.

When the bypass electric valve 56 is in an open state, the refrigerant compressed by the compressor 53 to become a high-temperature, high-pressure gas flows into the refrigerant circuit F3 via the bypass flow path F6. As a result, the temperature of the refrigerant flowing in the refrigerant circuit F3 rises. Then, the refrigerant with a raised temperature flows into the second heat exchanger 12.

That is, in this modification, when a predetermined criterion is satisfied, control is performed to allow the refrigerant compressed by the compressor 53 to flow into the second heat exchanger 12 via the bypass flow path F6. Thus, frosting of the second heat exchanger 12 can be suppressed.

(Variation 2 of Implementation Example 2)

In addition, other methods may be used as a method of increasing the temperature of the refrigerant flowing in the second heat exchanger 12. Therefore, in the second modification of the second embodiment, an example of controlling the electric valve 16 inside the exhaust unit 310 is described. In addition, the structure of the second modification of the second embodiment is equivalent to the structure in which the bypass flow path F6 is removed from the refrigerant circuit shown in FIG.

When the second heat exchanger 12 functions as an evaporator, the electric valve 16 functions as a valve unit for reducing the pressure of the high-pressure liquid refrigerant flowing out of the first heat exchanger 22 so that it can be easily evaporated, according to the control of the control unit 313. The smaller the opening of the electric valve 16, the more the pressure is reduced, thereby reducing the temperature of the refrigerant. In other words, the larger the opening of the electric valve 16, the higher the temperature of the refrigerant.

In this regard, the control unit 313 of the exhaust unit 310 determines whether a predetermined standard indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the detection result of the temperature detection unit 14 while the second heat exchanger 12 functions as an evaporator. The predetermined standard is the same as that in the second embodiment, and its description is omitted.

When determining that the predetermined criterion is satisfied, the control unit 313 performs control to increase the opening degree of the electric valve 16 (an example of the second valve unit) compared to before the predetermined criterion is satisfied as control to suppress frost formation on the second heat exchanger 12 .

That is, in this modification, when a predetermined criterion is satisfied, control is performed to increase the opening of the electric valve 16 to increase the temperature of the refrigerant flowing through the second heat exchanger 12. This can suppress frost formation on the second heat exchanger 12.

(Implementation method 3)

In the above-mentioned embodiments and modified examples, an example is described in which a control unit in the exhaust unit is judged whether it meets a predetermined standard, and an example is described in which control is performed according to the judgment result. However, in the above-mentioned embodiments and modified examples, the method of controlling by the control unit in the exhaust unit is not limited. For example, control may also be performed by a higher-level control device provided at a higher level than the air conditioner and the ventilation device.

Fig. 6 is a diagram showing a configuration example of a ventilation device, an air conditioner, and a host control device according to Embodiment 3. In addition, the same reference numerals are attached to the same configurations as those in the above-mentioned embodiment, and the description thereof is omitted here.

In the example shown in FIG. 6 , a host control device 400 is provided for performing cooperative operations between the ventilator 1C and the air conditioner 2C.

The air conditioner 2C includes an outdoor unit 470 and two air conditioner indoor units 81 and 82. In addition, the number of air conditioner indoor units in the present embodiment is not limited to two, and may be one or three or more.

The outdoor unit 470 includes a control unit 471 together with a heat exchanger (not shown).

The control unit 471 controls the entire air conditioner 2C. The control unit 471 also transmits and receives information to and from the host control device 400. The control unit 471 performs various controls based on control signals from the host control device 400.

The ventilation device 1C has a first exhaust unit 410A, a second exhaust unit 410B, a first air supply unit 420A, a second air supply unit 420B, a compressor unit 450, a refrigerant circuit F401, F402, F403, F404, a first supply air passage P401, a second supply air passage P402, a first return air passage P403 and a second return air passage P404.

The first air supply passage P401 supplies air introduced from the outside to the living space R11 from the ventilation port 92A after passing through the first air supply unit 420A having the first heat exchanger 22 .

The second air supply path P402 supplies air introduced from the outside to the living space R11 from the ventilation port 92B after passing through the second air supply unit 420B having the first heat exchanger 22 .

The first return air flow path P403 exhausts the air (return air) introduced from the ventilation port 91A of the indoor space to the outside through the first exhaust unit 410A including the second heat exchanger 12 .

The second return air flow path P404 exhausts the air (return air) introduced from the ventilation port 91B of the indoor space to the outside through the second exhaust unit 410B having the second heat exchanger 12 .

The refrigerant circuits F401, F402, F403, and F404 are formed by connecting the compressor unit 450, the first heat exchanger 22 of the first air supply unit 420A and the second air supply unit 420B, and the second heat exchanger 12 of the first exhaust unit 410 and the second exhaust unit 410B through refrigerant pipes, and have a circuit in which the refrigerant flows.

The control unit 452 of the compressor unit 450, the control unit 423A of the first air supply unit 420A, the control unit 423B of the second air supply unit 420B, the control unit 413A of the first exhaust unit 410A, and the control unit 413B of the second exhaust unit 410B are connected by a signal line S401 indicated by a dotted line. Thus, information can be sent and received between the control unit 452, the control unit 423A, the control unit 423B, the control unit 413A, and the control unit 413B.

Control unit 452 of compressor unit 450 transmits the status of ventilation device 1C received from control units 423A, 423B, 413A, and 413B to host control device 400. Thus, host control device 400 can implement control according to the status of ventilation device 1C.

The first air supply unit 420A includes a fan 21, a first heat exchanger 22, a control unit 423A, and a temperature detection unit 24, introduces outside air (OA), and supplies air (SA) to the living space R11 from the ventilation port 92A.

The second air supply unit 420B includes a fan 21, a first heat exchanger 22, a control unit 423B, and a temperature detection unit 24, introduces outside air (OA), and supplies air (SA) to the living space R11 from the ventilation port 92B.

The control unit 423A and the control unit 423B control the structure in each air supply unit. In addition, the control unit 423A and the control unit 423B send the detection results of the temperature detection unit 24 and the like in each air supply unit to the control unit 452 of the compressor unit 450. The control unit 452 of the compressor unit 450 identifies the current status based on the detection results and sends the identification results to the upper control device 400. Thus, the upper control device 400 can identify the status of the first air supply unit 420A and the second air supply unit 420B.

The first exhaust unit 410A includes a fan 11 (an example of a second ventilation unit), a second heat exchanger 12, a control unit 413A, and a temperature detection unit 14, introduces return air (RA) from the ventilation port 91A of the living space R11, and exhausts air to the outside (EA).

The second exhaust unit 410B includes a fan 11 (an example of a second ventilation unit), a second heat exchanger 12, a control unit 413B, and a temperature detection unit 14, introduces return air (RA) from the ventilation port 91B of the living space R11, and exhausts air to the outside (EA).

The control unit 413A and the control unit 413B control the structure in each exhaust unit. Furthermore, the control unit 413A and the control unit 413B send the detection results of the temperature detection unit 14 and the like in each exhaust unit to the control unit 452 of the compressor unit 450. The control unit 452 of the compressor unit 450 identifies the current status based on the detection results and sends the identification results to the upper control device 400. Thus, the upper control device 400 can identify the status of the first exhaust unit 410A and the second exhaust unit 410B.

The host control device 400 performs various controls to coordinate the operation of the ventilation device 1C and the operation of the air conditioner 2C with each other.

The host control device 400 receives the status of the air conditioner 2C from the control unit 471 of the outdoor unit 470 and receives the status of the ventilator 1C from the control unit 452 of the compressor unit 450. The host control device 400 performs various controls based on the status of the air conditioner 2C and the status of the ventilator 1C.

For example, when the upper control device 400 recognizes that the air conditioner 2C is performing a defrosting operation based on information received from the control unit 471 of the outdoor unit 470, it performs control to increase the heating capacity of the ventilation device 1C.

That is, when the air conditioner 2C performs the defrosting operation, the air conditioner 2C does not perform the heating function, so there is a possibility that the temperature in the living space R11 decreases. On the other hand, in order to compensate for the low function of the air conditioner 2C when the air conditioner 2C performs the defrosting operation, when the supply air temperature of the first air supply unit 420A and the second air supply unit 420B is increased, the temperature of the refrigerant in the second heat exchanger 12 of the first exhaust unit 410A and the second exhaust unit 410B connected through the refrigerant circuit F401, F402, F403, and F404 is reduced. In this case, the possibility of frost formation in the second heat exchanger 12 of the first exhaust unit 410A and the second exhaust unit 410B is increased.

Therefore, when recognizing that the air conditioner 2C is performing the defrosting operation, the host control device 400 increases the air volume of the air supply and exhaust of the ventilator 1C to improve the heating capacity and suppress the temperature drop in the living space R11.

FIG. 7 is a sequence diagram showing a flow of processing performed among the host control device 400 , the ventilation device 1C, and the air conditioner 2C when the air conditioner 2C of the present embodiment starts the defrosting operation.

First, when the defrosting operation is started, the control unit 471 in the outdoor unit 470 of the air conditioner 2C transmits a signal indicating that the defrosting operation is to be performed to the host control device 400 (S1701).

Then, when the upper control device 400 recognizes from the received signal that the defrosting operation has started in the air conditioner 2C, it determines to perform the air volume increase control of the ventilation device 1C in order to compensate for the function reduction caused by the defrosting operation (S1702).

Then, the host control device 400 transmits a control signal to the control unit 452 of the compressor unit 450, instructing the exhaust unit group (the first exhaust unit 410A and the second exhaust unit 410B) to increase the air volume (S1703).

Similarly, the control unit 452 of the compressor unit 450 transmits a control signal instructing an increase in air volume to each of the control units 413A and 413B of the exhaust unit group (the first exhaust unit 410A and the second exhaust unit 410B) (S1704).

Based on the received control signal, the control units 413A and 413B of the exhaust unit group control the fan 11 (an example of the second ventilation unit) to increase the amount of air flowing into the second heat exchanger 12 (increase the air volume) compared to before the air conditioner 2C performed the defrosting operation (S1705).

Then, the host control device 400 transmits a control signal to the control unit 452 of the compressor unit 450, instructing the air supply unit group (the first air supply unit 420A and the second air supply unit 420B) to increase the air volume (S1706).

Then, the control unit 452 of the compressor unit 450 transmits a control signal instructing an increase in air volume to the control units 423A and 423B of the air supply unit group (the first air supply unit 420A and the second air supply unit 420B) respectively (S1707).

The control units 423A and 423B of the air supply unit group respectively control the fan 21 (an example of the first ventilation unit) to increase the amount of air flowing into the first heat exchanger 22 (increase the air volume) compared to before the air conditioner 2C performs the defrost operation based on the received control signal (S1708).

In this embodiment, the supply air temperature of the ventilator 1C is not increased, but the supply and exhaust air volume is increased, thereby improving the heating capacity of the ventilator 1C and suppressing the decrease in the room temperature of the living space R11. In addition, in this embodiment, by suppressing the increase in the supply air temperature of the ventilator 1C, the possibility of frost on the second heat exchanger 12 caused by the decrease in the evaporation temperature can be reduced.

In order to compensate for the reduced capacity caused by the frosting operation of the air conditioner 2C, the upper control device 400 of this embodiment reduces the possibility of frosting of the second heat exchanger 12 by increasing the air supply and exhaust volume of the ventilator 1C, thereby improving the heating capacity and suppressing the drop in room temperature.

The host control device 400 of the present embodiment can perform various controls in addition to the cooperative control described above.

For example, the upper control device 400 may determine whether or not a predetermined standard indicating the possibility of frost formation on the second heat exchanger 12 is satisfied when receiving the temperature of the outside air from the control unit 413A or the control unit 413B of the exhaust unit group via the control unit 452 of the compressor unit 450. Furthermore, when the upper control device 400 determines that the predetermined standard is satisfied, control may be performed to suppress frost formation on the second heat exchanger 12. As control to suppress frost formation on the second heat exchanger 12, for example, the upper control device 400 may send a control signal to the control unit 471 of the outdoor unit 470 to increase the current set temperature of the heating device.

In addition, the configuration of the ventilation device may include the configuration of the host control device 400 shown in this embodiment. In other words, the processing performed by the host control device 400 may also be a function of the ventilation device. The same applies to the following embodiments.

(Implementation 4)

In Embodiment 3, cooperative control is described when the host control device 400 performs defrosting operation by the air conditioner 2C. However, the host control device 400 performs various cooperative controls. Therefore, in Embodiment 4, control is described when there is a possibility that the second heat exchanger 12 of the plurality of exhaust units 410 may be frosted.

When there is a possibility of frost forming on the second heat exchangers 12 of the plurality of exhaust units 410, it is difficult to simultaneously perform control to suppress frost formation on the second heat exchangers 12 of the plurality of exhaust units 410. Therefore, the upper control device 400 performs adjustment so as not to simultaneously perform control to suppress frost formation on the second heat exchangers 12 of the plurality of exhaust units 410.

In this embodiment, as control to suppress frost formation in the ventilator 1C, control is performed to increase the amount of air flowing into the second heat exchanger 12. When the plurality of exhaust units 410A and 410B simultaneously control to increase the amount of air flowing into the second heat exchanger 12, the living space R11 may have a negative pressure.

Therefore, in the present embodiment, the defrosting suppression control is performed by increasing the air volume for one of the plurality of exhaust units 410A and 410B, and the air volume is reduced for the other. That is, in the present embodiment, the defrosting suppression operation is performed preferentially for one of the plurality of exhaust units 410A and 410B. Furthermore, the upper control device 400 suppresses the negative pressure of the living space R11 by adjusting the total amount of exhausted air.

FIG8 is a timing chart showing the flow of processing performed among the host control device 400, the compressor unit 450, and the exhaust unit groups when there is a possibility of frost formation in each exhaust unit group in the present embodiment.

First, the control unit 413A of the first exhaust unit 410A acquires the temperature of the outside air from the temperature detection unit 14 ( S1801 ).

Then, the control unit 413A notifies the control unit 452 of the compressor unit 450 of the detected temperature of the outside air ( 1802 ).

Then, the control unit 413B of the second exhaust unit 410B acquires the temperature of the outside air from the temperature detection unit 14 ( S1811 ).

Then, the control unit 413B notifies the control unit 452 of the compressor unit 450 of the detected temperature of the outside air (1812).

The control unit 452 of the compressor unit 450 determines whether the prescribed criterion indicating that the second heat exchanger 12 of the first exhaust unit 410A and the second exhaust unit 410B may be frosted is satisfied (S1821) based on the temperature of the outside air received and detected from the control unit 413A of the first exhaust unit 410A and the control unit 413B of the second exhaust unit 410B. In the example shown in FIG. 8 , the second heat exchanger 12 of the first exhaust unit 410A and the second exhaust unit 410B is determined to satisfy the prescribed criterion. In addition, the prescribed criterion is the same as in the above embodiment, and its description is omitted.

The control unit 452 of the compressor unit 450 notifies the host control device 400 of the determination result indicating that there is a possibility of frost formation (S1822).

The upper control device 400 determines the order of frost suppression control for the first exhaust unit 410A and the second exhaust unit 410B based on the received judgment result (S1831). The method for determining the order can be any method. For example, it can be controlled so that the frost suppression is first performed on the side with a higher possibility of frost, or it can be determined according to the priority order pre-assigned to the first exhaust unit 410A and the second exhaust unit 410B. The example shown in FIG. 8 is an example in which frost suppression is determined in the order of the first exhaust unit 410A and the second exhaust unit 410B.

The host control device 400 transmits a signal indicating an instruction to increase the air volume of the first exhaust unit 410A to the control unit 452 of the compressor unit 450 (S1832).

Then, the control unit 452 of the compressor unit 450 transmits a signal indicating an instruction to increase the air volume to the control unit 413A of the first exhaust unit 410A (S1823).

Thus, the control unit 413A of the first exhaust unit 410A controls the fan 11 to increase the amount of air flowing into the second heat exchanger 12 (increase the air volume) compared to before the temperature detection in S1801 (S1803).

After increasing the amount of air flowing into the second heat exchanger 12 through the above control and after a specified time (a time predetermined to suppress frost formation) has passed, the upper control device 400 sends a signal (S1833) indicating a reduction in the air volume of the second exhaust unit 410B to the control unit 452 of the compressor unit 450.

Then, the control unit 452 of the compressor unit 450 transmits a signal indicating an instruction to reduce the air volume to the control unit 413B of the second exhaust unit 410B (S1824).

Thus, the control unit 413B of the second exhaust unit 410B controls the fan 11 to reduce the amount of air flowing into the second heat exchanger 12 (reducing the air volume) compared to before the temperature detection in S1811 (S1813).

In the present embodiment, the total exhaust volume of air is maintained by increasing the air volume of the first exhaust unit 410A and reducing the air volume of the second exhaust unit 410B. Then, the host control device 400 replaces the exhaust unit that performs frost suppression.

The host control device 400 transmits a signal indicating a command to reduce the air volume of the first exhaust unit 410A to the control unit 452 of the compressor unit 450 (S1834).

Then, the control unit 452 of the compressor unit 450 transmits a signal indicating an instruction to reduce the air volume to the control unit 413A of the first exhaust unit 410A (S1825).

Thus, the control unit 413A of the first exhaust unit 410A controls the fan 11 to reduce the amount of air flowing into the second heat exchanger 12 (reduce the air volume) compared to before the temperature detection in S1801 (S1804).

The host control device 400 transmits a signal indicating an instruction to increase the air volume of the second exhaust unit 410B to the control unit 452 of the compressor unit 450 (S1835).

Then, the control unit 452 of the compressor unit 450 transmits a signal indicating an instruction to increase the air volume to the control unit 413B of the second exhaust unit 410B (S1826).

Thus, the control unit 413B of the second exhaust unit 410B controls the fan 11 to increase the amount of air flowing into the second heat exchanger 12 (increase the air volume) compared to before the temperature detection in S1811 (S1814).

As described above, the controller 452 of the compressor unit 450 and the upper control device 400 of the present embodiment, when it is determined that the predetermined reference is satisfied, controls the fan 11 corresponding to any one of the plurality of second heat exchangers 12 to increase the amount of air flowing into the second heat exchanger 12 compared to before the predetermined reference is satisfied during the period when the plurality of second heat exchangers 12 function as evaporators. As a result, the amount of (warm) air flowing into any one of the second heat exchangers 12 increases, thereby suppressing frost.

Furthermore, the upper control device 400 controls the fans 11 corresponding to any one of the plurality of second heat exchangers 12 to increase the amount of air, and controls the fans 11 corresponding to other second heat exchangers 12 to reduce the amount of air flowing into the second heat exchanger compared to before the predetermined reference is satisfied. Thus, the amount of air exhausted from the plurality of exhaust unit groups can be maintained, thereby preventing the living space R11 from becoming negative pressure.

Furthermore, in the present embodiment, by performing frost suppression control for each of the plurality of exhaust units in a predetermined order, it is possible to suppress frost formation on the second heat exchanger 12 of the plurality of exhaust units.

(Implementation 5)

In Embodiment 4, an example of adjusting the amount of air discharged from a plurality of exhaust unit groups when performing frost suppression control is described. However, as a method for avoiding negative pressure, it is not limited to the method of adjusting the amount of air discharged from a plurality of exhaust unit groups. Therefore, in Embodiment 5, a case is described in which the amount of air introduced from the outside of the air supply unit group is increased when the amount of air discharged from the exhaust unit group is increased. In addition, it is assumed that the structure of this embodiment has the same structure as that of Embodiment 4.

The control unit 452 of the compressor unit 450 of this embodiment determines whether the predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 of the first exhaust unit 410A and the second exhaust unit 410B is satisfied based on the temperature of the received outside air, similarly to the fourth embodiment.

When the control unit 452 of the compressor unit 450 determines that either the first exhaust unit 410A or the second exhaust unit 410B satisfies the predetermined standard, the host control device 400 instructs the exhaust unit to increase the air volume. The instruction method is the same as that in Embodiment 4, and its description is omitted.

When it is determined that the first exhaust unit 410A and the second exhaust unit 410B satisfy the predetermined criteria, the upper control device 400 determines the order in which the frost is suppressed in the first exhaust unit 410A and the second exhaust unit 410B. The upper control device 400 instructs the first exhaust unit 410A and the second exhaust unit 410B to increase the air volume in the order.

The upper control device 400 of this embodiment, instead of giving an instruction to decrease the air volume as shown in Embodiment 4, gives an instruction to increase the air volume to at least one of the first air supply unit 420A and the second air supply unit 420B. The instruction to increase the air volume is given from the upper control device 400 via the control unit 452 of the compressor unit 450 to at least one of the control unit 423A of the first air supply unit 420A and the control unit 423B of the second air supply unit 420B.

The object for which the air volume increase is instructed may be any one of the first air supply unit 420A and the second air supply unit 420B, or each of the first air supply unit 420A and the second air supply unit 420B. However, the upper control device 400 makes adjustments so that the air volume exhausted from the first exhaust unit 410A and the second exhaust unit 410B is the same as the air volume introduced into the first air supply unit 420A and the second air supply unit 420B.

As described above, the upper control device 400 of this embodiment controls the fan 21 included in the air supply unit group to increase the amount of air flowing into the first heat exchanger 22 compared to before the predetermined reference is satisfied, when the fan 11 corresponding to any one of the plurality of second heat exchangers 12 included in the exhaust unit group is controlled to increase the amount of air flowing into the second heat exchanger 12. Thus, in this embodiment, since the amount of air introduced is substantially the same as the amount of air discharged, it is possible to suppress the situation where the living space R11 becomes negative pressure.

(Implementation 6)

The method of suppressing frost is not limited to the above embodiment, and other methods may be used. Therefore, in Embodiment 6, an example of suppressing frost by causing air to flow into the second heat exchanger 12 after stopping the operation of the compressor of the compressor unit will be described.

The structure of this embodiment may be any structure, and may be a structure provided with a host control device 400 as shown in FIG6 of Embodiment 3. In addition, in the example shown in FIG6, an example is shown in which two exhaust units and two air supply units are provided, but one exhaust unit and one air supply unit may be provided. As described above, the number of exhaust units and air supply units may be any number.

While the second heat exchanger 12 functions as an evaporator, the control unit 413A of the first exhaust unit 410A and the control unit 413B of the second exhaust unit 410B acquire the surface temperature of the second heat exchanger 12 from the temperature detection unit 14. Then, the control unit 413A and the control unit 413B of the second exhaust unit 410B transmit the detected surface temperature of the second heat exchanger 12 to the control unit 452 of the compressor unit 450.

Furthermore, the control unit 452 of the compressor unit 450 determines whether a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12. As a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12, for example, a reference for determining whether the surface temperature of the second heat exchanger 12 is below 0 degrees may be used. In addition, the predetermined reference may be any reference as long as it is a reference indicating the possibility of frost formation on the second heat exchanger 12. For example, the predetermined reference may be the reference described in the above embodiment, or may be a reference based on the temperature or pressure of the refrigerant.

When determining that the predetermined criterion is satisfied, the control unit 452 of the compressor unit 450 of the present embodiment notifies the host control device 400 of the determination result indicating that there is a possibility of frost on the second heat exchanger 12 .

Based on the determination result, the host control device 400 transmits a control signal for instructing the controller 452 of the compressor unit 450 to stop the compressor. As a result, the controller 452 of the compressor unit 450 performs control to stop the compressor.

In addition, the upper control device 400 outputs control signals to the control unit 413A of the first exhaust unit 410A and the control unit 413B of the second exhaust unit 410B respectively via the control unit 452 of the compressor unit 450 according to the determination result, so as to continue to control the second heat exchanger 12 for causing air to flow into the fan 11. Furthermore, as shown in Embodiment 4, the upper control device 400 may also control the fan 11 to increase the air volume.

In the present embodiment, the compressor in the compressor unit 450 is stopped and the air in the living space R11 is directed to the second heat exchanger 12 to increase the surface temperature of the second heat exchanger 12 , thereby suppressing frost on the second heat exchanger 12 .

(Implementation 7)

In Embodiment 6, an example is described in which the host control device 400 controls one compressor unit 450. However, the number of compressor units controlled by the host control device 400 is not limited to one. Therefore, in Embodiment 7, an example is described in which the host control device 400 controls three compressor units.

Fig. 9 is a diagram illustrating an arrangement of a group of devices including the host control device 500 according to Embodiment 7. In the example shown in Fig. 9 , at least living room spaces R501, R502, and R503, dressing rooms R511 and R512, and a pipe axis R521 are included.

Ventilation ports 595A and 595B are provided in dressing rooms R511 and R512, respectively.

In addition, the air conditioner 2D includes three outdoor units 571, 572, and 573 and eight indoor air conditioner units 581, 582, 583, 584, 585, 586, 587, and 588. The three outdoor units 571 to 573 and the eight indoor air conditioner units 581 to 588 are connected by connecting pipes (not shown).

In addition, the three outdoor units 571 to 573 are connected to the host control device 500 via signal lines. Thus, the three outdoor units 571 to 573 can perform air conditioning control according to the control of the host control device 500.

The first ventilator 1D_1 is a ventilator provided in the living space R501, and includes a first compressor unit 550A, a first air supply unit 520A, and a first exhaust unit 510A.

The first air supply unit 520A supplies air (SA) from the ventilation port 592A. The first exhaust unit 510A returns air (RA) from the ventilation port 591A. The first compressor unit 550A, the first air supply unit 520A and the first exhaust unit 510A are connected by a connecting pipe F501. The connecting pipe F501 includes a plurality of refrigerant connecting pipes. Thus, the refrigerant can be circulated between the first compressor unit 550A, the first air supply unit 520A and the first exhaust unit 510A.

In addition, the first compressor unit 550A, the first air supply unit 520A and the first exhaust unit 510A are connected by a signal line (not shown). This enables information to be sent and received between the units. In addition, the structures in the first compressor unit 550A, the first air supply unit 520A and the first exhaust unit 510A are the same as the compressor unit 450A, the first air supply unit 420A and the first exhaust unit 410A shown in Figure 6, and their description is omitted.

The second ventilator 1D_2 is a ventilator provided in the living space R502, and includes a second compressor unit 550B, a second air supply unit 520B, and a second exhaust unit 510B.

The second air supply unit 520B supplies air (SA) from the ventilation port 592B. The second exhaust unit 510B returns air (RA) from the ventilation port 591B. The second compressor unit 550B, the second air supply unit 520B and the second exhaust unit 510B are connected by a connecting pipe F502. The connecting pipe F502 includes a plurality of refrigerant connecting pipes. Thus, the refrigerant can be circulated between the second compressor unit 550B, the second air supply unit 520B and the second exhaust unit 510B.

In addition, the second compressor unit 550B, the second air supply unit 520B and the second exhaust unit 510B are connected by a signal line (not shown). Thus, information can be sent and received between the units. In addition, the structure in the second compressor unit 550B, the second air supply unit 520B and the second exhaust unit 510B is the same structure as the compressor unit 450A, the first air supply unit 420A and the first exhaust unit 410A shown in Figure 6, and its description is omitted here.

The third ventilator 1D_3 is a ventilator provided in the living space R503, and includes a third compressor unit 550C, a third air supply unit 520C, and a third exhaust unit 510C.

The third air supply unit 520C supplies air (SA) from the ventilation port 592C. The third exhaust unit 510C returns air (RA) from the ventilation port 591C. The third compressor unit 550C, the third air supply unit 520C and the third exhaust unit 510C are connected by a connecting pipe F503. The connecting pipe F503 includes a plurality of refrigerant connecting pipes. Thus, the refrigerant can be circulated between the third compressor unit 550C, the third air supply unit 520C and the third exhaust unit 510C.

In addition, the third compressor unit 550C, the third air supply unit 520C and the third exhaust unit 510C are connected by a signal line (not shown). Thus, information can be sent and received between the units. In addition, the structure in the third compressor unit 550C, the third air supply unit 520C and the third exhaust unit 510C is the same structure as the compressor unit 450A, the first air supply unit 420A and the first exhaust unit 410A shown in Figure 6, and its description is omitted here.

As described above, in this embodiment, there are a plurality of combinations of the compressor unit, the air supply unit, the exhaust unit, and the communication duct. In addition, the first compressor unit 550A, the second compressor unit 550B, and the third compressor unit 550C are arranged on the pipe axis R521.

The host control device 500 is connected to the first compressor unit 550A, the second compressor unit 550B, and the third compressor unit 550C via signal lines, so that the host control device 500 can recognize the state of each of the first to third ventilation devices 1D_1 to 1D_3 and can control each device.

Through the above structure, while the second heat exchanger 12 of each of the first exhaust unit 510A to the third exhaust unit 510C functions as an evaporator, the control unit (not shown) of the first compressor unit 550A to the third compressor unit 550C receives the surface temperature of the second heat exchanger 12 from the first exhaust unit 510A to the third exhaust unit 510C, respectively.

Furthermore, the control unit of the first compressor unit 550A to the third compressor unit 550C of the present embodiment determines whether a predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 during the period when the second heat exchanger 12 functions as an evaporator. In addition, the predetermined criterion is the same as that of the above-mentioned embodiment, and its description is omitted here.

The control units of the first to third compressor units 550A to 550C notify the host control device 400 of the determination results indicating whether or not the predetermined criteria are satisfied.

When the upper control device 500 determines from the judgment result that there are multiple compressor units (for example, the first compressor unit 550A to the third compressor unit 550C) connected to the second heat exchanger 12 that meets the specified criteria through the connecting pipe, as a control to suppress frost on the second heat exchanger 12, the upper control device 500 outputs a control signal to stop the compressor in a specified order to the multiple compressor units (for example, the first compressor unit 550A to the third compressor unit 550C). Thereby, it is possible to suppress the situation where multiple compressor units stop the compressor at the same time. In addition, the specified order can be an arbitrary order, or it can be an order from low to high surface temperature, or it can be based on the priority order of the compressor units set in advance.

In addition, the host control device 500 maintains control of the fan 11 corresponding to the second heat exchanger 12 satisfying the predetermined criterion so that air from the living spaces R501 to R503 flows into the second heat exchanger 12. Thus, the temperature of the refrigerant flowing through the second heat exchanger 12 can be increased.

In the present embodiment, by performing the above control, the flow of the refrigerant into the second heat exchanger 12 is stopped, and the flow of air into the second heat exchanger 12 is maintained, thereby suppressing the frosting of the second heat exchanger 12 .

(Eighth Implementation Method)

In Embodiment 7, an example is described in which the host control device 500 stops a plurality of compressor units in a predetermined order. In contrast, in Embodiment 8, an example is described in which a plurality of air supply units and a plurality of exhaust units are connected to one compressor.

FIG10 is a diagram illustrating an arrangement of a device group including a host control device 600 according to Embodiment 8. Among the configurations shown in FIG10 , configurations identical to those of the above-described embodiment are denoted by identical reference numerals and description thereof is omitted.

As shown in Fig. 10, the compressor unit 650 is connected to the first air supply unit 520A and the first exhaust unit 510A through a communication pipe F601, connected to the second air supply unit 520B and the second exhaust unit 510B through a communication pipe F602, and connected to the third air supply unit 520C and the third exhaust unit 510C through a communication pipe F603. Thus, the refrigerant can be circulated through each unit connected by the communication pipes F601, F602, and F603.

The compressor unit 650, the first air supply unit 520A to the third air supply unit 520C, and the first exhaust unit 510A to the third exhaust unit 510C are connected by a signal line (not shown), thereby enabling information to be sent and received between the units. In addition, the upper control device 500 and the compressor unit 650 are also connected by a signal line, thereby enabling information to be sent and received.

Furthermore, the first air supply unit 520A, the second air supply unit 520B, and the third air supply unit 520C are provided with the electric valve 26 (an example of the first valve unit) as shown in FIG5 . Similarly, the first exhaust unit 510A, the second exhaust unit 510B, and the third exhaust unit 510C are provided with the electric valve 16 (an example of the first valve unit) as shown in FIG5 .

When the second heat exchanger 12 of the first exhaust unit 510A, the second exhaust unit 510B, and the third exhaust unit 510C functions as an evaporator, the electric valve 16 functions as a valve that adjusts the opening of the flow path flowing into the second heat exchanger 12 (adjusts the pressure of the refrigerant).

(An example of a valve part)

Thus, the host control device 600 controls the first exhaust unit 510A, the second exhaust unit 510B, and the third exhaust unit 510C to close the electric valve 16 , and can individually control to stop the inflow of the refrigerant.

The control unit (not shown) of the compressor unit 650 of this embodiment determines whether a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 during the period when the second heat exchanger 12 functions as an evaporator. The predetermined reference is the same as that in the above embodiment, and its description is omitted. Furthermore, the control unit (not shown) 652 of the compressor unit 650 notifies the upper control device 600 of the determination result.

In this embodiment, when the upper control device 600 recognizes that there are multiple second heat exchangers 12 that meet the specified criteria based on the judgment result, as a control to suppress frost formation on the second heat exchanger 12, a control signal for closing the electric valve 16 is output in a specified order for multiple exhaust units (for example, the first exhaust unit 510A to the third exhaust unit 510C) including the second heat exchanger 12 that meets the specified criteria. As a result, the actions of the refrigerant flowing into the multiple second heat exchangers 12 can be suppressed from being stopped at the same time. In addition, the specified order can be an arbitrary order, an order from low to high surface temperature, or a priority order based on a preset compressor unit.

In addition, the host control device 500 maintains control of causing the air from the living spaces R501 to R503 to flow into the second heat exchanger 12 for the fan 11 corresponding to the second heat exchanger 12 that satisfies the predetermined criterion.

In the present embodiment, by performing the control as described above, the flow of the refrigerant into the second heat exchanger 12 is stopped, and the flow of air into the second heat exchanger 12 is maintained, so that frost formation can be suppressed.

(Implementation method 9)

It is also possible to use methods other than those in the above embodiment to suppress the frosting of the second heat exchanger 12. Therefore, in the ninth embodiment, an example of adjusting the supply air volume and the exhaust air volume will be described.

The structure of the ninth embodiment may be any structure of the above embodiments, and may be, for example, the structure shown in Fig. 6. Therefore, in this embodiment, the case of having the structure shown in Fig. 6 will be described.

Furthermore, the control unit 452 of the compressor unit 450 of the present embodiment determines whether or not a prescribed criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 during the period when the second heat exchanger 12 functions as an evaporator. The prescribed criterion is the same as that in the above embodiment, and its description is omitted here.

In the present embodiment, the control unit 452 of the compressor unit 450 notifies the upper control device 400 of the determination result. Furthermore, when the upper control device 400 recognizes that there are a plurality of second heat exchangers 12 that satisfy the prescribed criteria, as a control to suppress frost formation on the second heat exchanger 12, a control signal for controlling the fan 11 and the fan 12 is output so that the total air supply volume of the fan 11 (an example of the second ventilation unit) of the exhaust unit group (for example, the first exhaust unit 410A and the second exhaust unit 410B) is greater than the total exhaust volume of the fan 21 (an example of the first ventilation unit) of the air supply unit group (for example, the first air supply unit 420A and the second air supply unit 420B).

In this embodiment, the exhaust air volume is set larger than the supply air volume, thereby suppressing the condensing capacity of the supply air unit group and increasing the evaporation temperature of the second heat exchanger 12 of the exhaust air unit group, thereby suppressing frost.

(Implementation 10)

It is also possible to use methods other than those of the above embodiment to suppress frost formation on the second heat exchanger 12. Therefore, in the tenth embodiment, an example in which the temperature of air after passing through the first heat exchanger 22 is adjusted will be described.

The structure of the tenth embodiment may be any structure of the above embodiments, and may be, for example, the structure shown in Fig. 6. Therefore, in this embodiment, the case of having the structure shown in Fig. 6 will be described.

Furthermore, the control unit 452 of the compressor unit 450 of the present embodiment determines whether a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 during the period when the second heat exchanger 12 functions as an evaporator. The predetermined reference is the same as that in the above embodiment, and its description is omitted. Furthermore, the control unit 452 of the compressor unit 450 notifies the upper control device 400 of the determination result.

In this embodiment, when the upper control device 400 recognizes that there are a plurality of second heat exchangers 12 that meet the prescribed criteria, it outputs a control signal to the first heat exchanger of the air supply unit group (for example, the first air supply unit 420A and the second air supply unit 420B) as a control to suppress frost formation on the second heat exchanger 12. The control signal makes the temperature of the air after passing through the first heat exchanger 22 lower than the temperature of the air conditioner 2C provided in the living space R11. In addition, the temperature set in the air conditioner 2C is obtained from the control unit 471 of the outdoor unit 470.

In this embodiment, the temperature of the air after passing through the first heat exchanger 22 of the air supply unit group (supply air temperature) is lower than the set indoor temperature. Therefore, the compressor of the compressor unit 450 is operated at a low rotation speed, and the evaporation temperature of the second heat exchanger 12 can be suppressed from decreasing.

(Implementation 11)

It is also possible to use methods other than the above embodiment to suppress frost formation on the second heat exchanger 12. Therefore, in Example 11, an example of adjusting the refrigerant pressure by an electric valve (an example of a third valve portion) provided downstream of the exhaust unit will be described.

The structure of the eleventh embodiment may be any structure of the above embodiments, and may be, for example, the structure shown in Fig. 6. Therefore, in this embodiment, the case of having the structure shown in Fig. 6 will be described.

Fig. 11 is a diagram showing a refrigerant circuit of Embodiment 11. The example shown in Fig. 11 shows the flow of the refrigerant when the second heat exchanger 12 of the exhaust units 410A and 410B functions as an evaporator. In addition, the same reference numerals are given to the same structures as those in the above embodiments, and their description is omitted here.

In the example shown in FIG. 11 , when the second heat exchanger 12 of the exhaust units 410A and 410B functions as an evaporator, electric valves 601 and 602 are provided on the downstream side of the second heat exchanger 12 of the exhaust units 410A and 410B, respectively.

Furthermore, the control unit 452 of the compressor unit 450 of the present embodiment determines whether a predetermined reference indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 during the period when the second heat exchanger 12 functions as an evaporator. The predetermined reference is the same as that in the above embodiment, and its description is omitted here. The control unit 452 of the compressor unit 450 notifies the upper control device 400 of the determination result.

In this embodiment, when the upper control device 400 recognizes the existence of the second heat exchanger 12 that meets the specified criteria, it outputs a control signal to the control unit (control unit 413A or control unit 413B) of the exhaust unit (for example, the first exhaust unit 410A or the second exhaust unit 410B) including the second heat exchanger 12, thereby tightening the electric valve (electric valve 601 or electric valve 602) compared to before the specified criteria were met.

By reducing the opening of the expansion valve (expansion valve 161 or expansion valve 162), the pressure of the refrigerant flowing in the second heat exchanger 12 located on the upstream side of the expansion valve (expansion valve 161 or expansion valve 162) can be increased. As a result, the evaporation temperature of the refrigerant flowing in the second heat exchanger 12 can be increased. Thus, frost formation in the second heat exchanger 12 can be suppressed.

11 shows a bypass flow path F6, but in the present embodiment, the bypass flow path F6 may be used in combination with the control in the above embodiment, or may not be used in combination.

(Variation of Implementation Example 11)

In Embodiment 11, an example of suppressing frost formation by tightening the electric valves 601 and 602 downstream of the second heat exchanger 12 is described. In Embodiment 11, not only the method of adjusting the electric valves 601 and 602 on the downstream side of the second heat exchanger 12 is described, but also the case of providing an exhaust unit 730 of an outdoor unit in the refrigerant circuit and controlling the exhaust unit 730 is described.

Fig. 12 is a diagram showing a refrigerant circuit of a modified example of Embodiment 11. In the example shown in Fig. 12, an example is shown in which an exhaust unit 730 is further provided in the refrigerant circuit shown in Fig. 11. In addition, except for the exhaust unit 730, other structures are the same as those of Embodiment 11, and the description thereof is omitted.

The exhaust unit 730 includes a fan 11 , a third heat exchanger 732 , a control unit 733 , a temperature detection unit 14 , a drive motor 15 , and an electric valve 16 .

The exhaust unit 730 functions as an outdoor unit. That is, the exhaust unit 730 is provided on a flow path (an example of a fourth air flow path) for exhausting the air after heat exchange between the outdoor air and the refrigerant flowing through the third heat exchanger 732 to the outside.

Furthermore, the control unit 452 of the compressor unit 450 of the present embodiment determines whether a predetermined criterion indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 during the period when the second heat exchanger 12 functions as an evaporator. The predetermined criterion is the same as that in the above embodiment, and its description is omitted. The control unit 452 of the compressor unit 450 notifies the upper control device 400 of the determination result.

In this embodiment, when the upper control device 400 recognizes the existence of the second heat exchanger 12 that meets the specified criteria, it performs the same control as embodiment 11 and causes the third heat exchanger 732 of the exhaust unit 730 to perform heat exchange at a lower evaporation temperature than the second heat exchanger 12 during heat exchange.

As shown in Fig. 12, the refrigerant flow through the third heat exchanger 732 of the exhaust unit 730 and the refrigerant flow through the second heat exchanger 12 of the exhaust units 410A and 410B are connected to each other. Therefore, the evaporation temperature of the third heat exchanger 732 can be lowered, and the evaporation temperature of the second heat exchanger 12 can be increased. As a result, frost formation on the second heat exchanger 12 can be suppressed.

In addition, in the above embodiments and modified examples, a method in which the control unit 452 of the compressor unit 450 and the upper control device 500 share the processing is described, but it is not limited to the method in which the control unit 452 of the compressor unit 450 and the upper control device 500 share the processing, and the determination and control of other devices may be performed by either the control unit 452 of the compressor unit 450 or the upper control device 500. Furthermore, it is not limited to the method in which the control unit 452 of the compressor unit 450 and the upper control device 500 perform the processing, and the processing of the above embodiments may be performed by a server or cloud service that performs centralized management.

(Implementation 12)

It is also possible to use methods other than the above-described embodiment to suppress frost formation on the second heat exchanger 12. Therefore, in Example 12, an example of switching control in consideration of power consumption will be described.

The structure of the twelfth embodiment may be any structure of the above embodiments, for example, it may be the structure shown in Fig. 6. Therefore, in this embodiment, the case of having the structure shown in Fig. 6 is described. The upper control device 400 performs the following control during the heat recovery ventilation operation.

Furthermore, the control unit 452 of the compressor unit 450 of the present embodiment determines whether a predetermined standard indicating the possibility of frost formation on the second heat exchanger 12 is satisfied based on the surface temperature of the second heat exchanger 12 while the second heat exchanger 12 functions as an evaporator. The control unit 452 of the compressor unit 450 notifies the host control device 400 of the determination result.

As the predetermined criterion, determination may be made based on the temperature of the refrigerant flowing through the second heat exchanger 12 or the pressure of the refrigerant, and the same method as in the above embodiment may be adopted.

In this embodiment, when the host control device 400 recognizes that there are multiple second heat exchangers 12 that meet the specified criteria, it determines whether to perform frost suppression control or allow frost and then perform defrost operation after frost. According to the determination result of the host control device 400, the exhaust unit group (for example, the first exhaust unit 410A and the second exhaust unit 410B) performs frost suppression control or allows frost and then performs defrost operation after frost.

FIG. 13 is a flowchart showing the processing procedure of the host control device 400 according to the present embodiment.

First, the control unit 452 of the compressor unit 450 of the present embodiment receives detection results related to the second heat exchanger 12 from each exhaust unit group (S2101). The detection result is the temperature of the refrigerant flowing through the second heat exchanger 12 or the pressure of the refrigerant.

The control unit 452 of the compressor unit 450 determines whether the prescribed criterion is met based on the detection result (S2102). For example, as a prescribed criterion indicating the possibility of frost on the second heat exchanger 12, whether the detected (evaporation) temperature of the refrigerant is less than the prescribed temperature t can be used as a criterion, or whether the detected (evaporation) pressure of the refrigerant is less than the prescribed pressure p can be used as a criterion. In the case where it is determined that the prescribed criterion is not met (S2102: No), the process starts again from S2101. In addition, the prescribed temperature t and pressure p as a criterion for whether there is a possibility of frost are values determined according to the implementation method, and their description is omitted. In addition, the judgment can be made at each prescribed time (for example, × minutes).

When determining that the predetermined criterion is satisfied ( S2102 : YES), the control unit 452 of the compressor unit 450 notifies the host control device 400 of the determination result.

Then, the host control device 400 controls the temperature of the refrigerant flowing through the second heat exchanger 12 to perform frost suppression, and calculates the power consumption E1 for maintaining the current temperature of the living space R11 (S2103).

Furthermore, the host control device 400 calculates the power consumption E2 for maintaining the current temperature of the living space R11 while performing the defrosting operation (S2104).

For example, in this embodiment, a power consumption calculation model preset for calculating power consumption E1 and power consumption E2 is pre-stored in the upper control device 500. Then, the upper control device 500 calculates power consumption by inputting input information (e.g., room temperature/outside temperature, air volume of fans 11 and 21, pressure of refrigerant, number of revolutions of compressor, etc.: an example of the condition of the living space) into the power consumption calculation model. In addition, the method for calculating power consumption is not limited to the method using the calculation model, and other methods may also be used.

Then, the upper control device 400 determines whether the power consumption E1 is less than the power consumption E2 (S2105). When the upper control device 400 determines that the power consumption E1 is less than the power consumption E2 (S2105: Yes), it outputs a control signal for suppressing frost to the exhaust unit group (S2106). In addition, the method for suppressing frost can be any of the processes shown in the above embodiment, and its description is omitted. After that, the upper control device 500 starts the process again from S2101.

Then, when it is determined that the power consumption E1 is greater than (not less than) the power consumption E2 (S2105: No), the upper control device 400 allows the exhaust unit group to be frosted, and after it is determined that frosting has occurred based on the detection result, it outputs a control signal for executing the defrosting operation (S2107). In addition, regarding the method of performing the defrosting operation, there is no limitation to the known method, and any method can be used, and its description is omitted here.

Then, the host control device 400 of this embodiment receives the detection result related to the second heat exchanger 12 from each exhaust unit group via the control unit 452 of the compressor unit 450 (S2108). The detection result is the temperature of the refrigerant flowing in the second heat exchanger 12 or the pressure of the refrigerant.

The upper control device 400 determines whether the defrost end criterion (S2109) is met based on the detection result. For example, as the defrost end criterion for the second heat exchanger 12, whether the detected (evaporation) temperature of the refrigerant is greater than the specified temperature t+α can be used as a criterion, or whether the detected (evaporation) pressure of the refrigerant is less than the specified pressure p+β can be used as a criterion. In addition, the defrost end criterion can be any criterion as long as it can be used to determine whether the defrost is completed. In addition, the variables α and β are positive numbers determined according to the implementation method, and their description is omitted here. Determine whether the defrost end criterion (S2109) is met. When it is determined that the defrost end criterion is not met (S2109: No), the process starts again from S2108. In addition, this determination can be made at each specified time (for example, y minutes).

On the other hand, when the host control device 400 determines that the defrosting end criterion is satisfied based on the detection result (S2109: Yes), it outputs a control signal for ending the defrosting operation to the exhaust unit group (S2110) and ends the process. Then, the host control device 500 starts the process again from S2101.

The upper control device 500 of the present embodiment, by performing the above-mentioned control, when it is determined that the prescribed benchmark is met, can control the temperature of the refrigerant flowing in the second heat exchanger 12 to a temperature at which the second heat exchanger 12 is not frosted, or control the operation of eliminating frost on the second heat exchanger 12 after the second heat exchanger 12 is frosted, based on the power consumption required for controlling the temperature of the refrigerant flowing in the second heat exchanger 12 and the power consumption required for the operation of eliminating frost on the second heat exchanger 12 after the second heat exchanger 12 is frosted.

Therefore, in the present embodiment, it is possible to suppress frost formation on the exhaust unit group or to suppress power consumption during defrosting.

In the above embodiments and modifications, an example is described in which the air supply unit is a shell (an example of a first shell) that accommodates the first heat exchanger 22 and at least a portion of the air flow path (an example of the first air flow path), and the exhaust unit is a shell (an example of a second shell) that accommodates the second heat exchanger 12 and at least a portion of the air flow path (an example of the second air flow path), and the shells are separated.

Thus, the exhaust unit and the air supply unit can be arranged at separate positions. Thus, the degree of freedom in arrangement of the ventilation device capable of heat recovery can be increased compared to the related art.

However, the above embodiments and modified examples are not limited to the example in which the shells of the air supply unit and the exhaust unit are separated, and the air supply unit and the exhaust unit may also be an integrated structure. That is, the first heat exchanger 22 is connected to the second heat exchanger 12 through a refrigerant circuit, and in the case where a fan 21 corresponding to the first heat exchanger 22 and a fan corresponding to the second heat exchanger 12 are provided, the air volume adjustment or the refrigerant temperature adjustment as shown in the above embodiments and modified examples can be applied. Therefore, the method shown in the above embodiments and modified examples can also be applied to the case in which the air supply unit and the exhaust unit are an integrated structure.

(Overview of the ventilation system)

The air conditioning system starts the compressor, uses the first heat exchanger of the air supply unit as a condenser, and uses the second heat exchanger of the exhaust unit as an evaporator, so that the heat of the exhaust gas (indoor air) can be recovered to the refrigerant in the refrigerant circuit while ventilating the room. In the air conditioning system, when the second heat exchanger into which the exhaust gas flows is used as an evaporator, if the temperature of the exhaust gas (indoor air) is lower than a specified value, frost will form on the second heat exchanger, and the low pressure of the refrigerant circuit will decrease. In this case, it is difficult to keep the started compressor running.

In the embodiments described below, regarding a ventilation system including a refrigerant circuit, when a heat exchanger is used as an evaporator, continuous operation of the compressor can be surely achieved.

FIG. 14 is a schematic diagram of the ventilation system of the present invention. FIG. 15 is a control block diagram of the ventilation system of the present invention. In the following description, the ventilation system 1E of the 13th embodiment (see FIG. 17) is referred to as the 13th ventilation system 1F, the ventilation system 1E of the 14th embodiment (see FIG. 18 and FIG. 19) is referred to as the 14th ventilation system 1G, the ventilation system 1E of the 15th embodiment (see FIG. 20) is referred to as the 15th ventilation system 1H, the ventilation system 1E of the 16th embodiment (see FIG. 21) is referred to as the 16th ventilation system 1I, the ventilation system 1E of the 17th embodiment (see FIG. 22) is referred to as the 17th ventilation system 1J, and the ventilation system 1E of the 18th embodiment (see FIG. 23) is referred to as the 18th ventilation system 1K. In the following description, only the case of recording "the ventilation system 1E" indicates that the structure common to each of the ventilation systems 1F to 1K of the 13th to 18th embodiments is described.

The ventilation system 1E shown in FIG14 is an embodiment of the ventilation device of the present invention, which is installed in a building such as a building or a factory to ventilate the target space in the building. The ventilation system 1E includes an air supply unit 1020, an exhaust unit 1030, a compressor unit 1040 and a refrigerant circuit 1050.

As shown in FIG. 14 , the air supply unit 1020 includes a first housing 1021, an air supply fan 1022, and a first heat exchanger 1023. The first housing 1021 of the present embodiment is a cubic box body composed of a heat-insulating plate member, and a suction port 1024 and a blow-out port 1025 are formed on the side. The air supply fan 1022 and the first heat exchanger 1023 are arranged in the first housing 1021. When the air supply unit 1020 drives the air supply fan 1022, air (external air OA) from the outside (hereinafter referred to as the outdoor 1000S2, refer to FIG. 17 and FIG. 19) is introduced into the inside of the first housing 1021, and after the introduced air is heat-exchanged with the refrigerant in the first heat exchanger 1023, the air (supply air SA) is supplied from the blow-out port 1025 to the room (hereinafter referred to as the indoor 1000S1, refer to FIG. 17 and FIG. 19). The ventilation system 1E has an air supply path P1001 (an example of a first air flow path) for supplying introduced external air OA to the room 1000S1 from the blow-off port 1025 via the first housing 1021 .

The first heat exchanger 1023 constitutes a refrigerant circuit 1050 described below. The first heat exchanger 1023 is a cross-fin-tube type or microchannel type heat exchanger for performing heat exchange between the refrigerant flowing in the first heat exchanger 1023 and the air (outside air OA) of the outdoor 1000S2.

The air supply unit 1020 includes an air supply temperature sensor 1026 and an external air temperature sensor 1027. The air supply temperature sensor 1026 is disposed in the air flow after passing through the first heat exchanger 1023 in the first housing 1021, and is used to detect the temperature T1 of the supply air SA (hereinafter referred to as the blown air temperature T1). The external air temperature sensor 1027 is disposed in the air flow before passing through the first heat exchanger 1023 in the first housing 1021, and is used to detect the temperature T2 of the external air OA (hereinafter referred to as the external air temperature T2).

The air supply unit 1020 includes a first heat exchange temperature sensor 1055 and a first refrigerant temperature sensor 1056. The first heat exchange temperature sensor 1055 detects a temperature Tb1 of the first heat exchanger 1023 (in other words, a temperature of the refrigerant in the first heat exchanger 1023). The first refrigerant temperature sensor 1056 detects a temperature Ta2 of the refrigerant after passing through the first heat exchanger 1023 (at the outlet). In addition, the first heat exchange temperature sensor 1055 may be a pressure sensor for detecting the pressure in the first heat exchanger 1023. In this case, the refrigerant temperature in the first heat exchanger 1023 is calculated based on the detected value of the pressure.

The exhaust unit 1030 includes a second housing 1031, an exhaust fan 1032, and a second heat exchanger 1033. The second housing 1031 of the present embodiment is a cubic box body composed of a heat-insulating plate member, and has a suction port 1034 and a blow-out port 1035 formed on the side. The exhaust fan 1032 and the second heat exchanger 1033 are arranged in the second housing 1031. When the exhaust unit 1030 drives the exhaust fan 1032, the air (return air RA) of the room 1000S1 is introduced into the interior of the second housing 1031, and after the introduced air is heat-exchanged with the refrigerant in the second heat exchanger 1033, the air (exhaust air EA) is discharged from the blow-out port 1035 to the outside 1000S2. The ventilation system 1E includes a return air flow path P1002 (an example of a second air flow path) for discharging the air (return air RA) in the room 1000S1 to the outside 1000S2 from the air outlet 1035 via the second casing 1031 .

The second heat exchanger 1033 constitutes a refrigerant circuit 1050 described below. The second heat exchanger 1033 is a cross-fin-tube type or microchannel type heat exchanger for performing heat exchange between the refrigerant flowing in the second heat exchanger 1033 and the air (return air RA) in the room 1000S1.

The exhaust unit 1030 has a return air temperature sensor 1036. The return air temperature sensor 1036 is arranged in the air flow before passing through the second heat exchanger 1033 in the second shell 1031, and is used to detect the temperature T3 of the air flowing into the second heat exchanger 1033. In the following description, this temperature T3 is referred to as the intake air temperature T3. In the present invention, the intake air temperature T3 when only the air introduced from the indoor 1000S1 passes through the second heat exchanger 1033 is set as the temperature of the air in the indoor 1000S1. In addition, the temperature of the indoor 1000S1 can also be detected by a sensor (not shown) provided in the indoor 1000S1.

The exhaust unit 1030 is provided with a second heat exchange temperature sensor 1057 and a second refrigerant temperature sensor 1058. The second heat exchange temperature sensor 1057 is used to detect the temperature Tb2 of the second heat exchanger 1033 (in other words, the refrigerant in the second heat exchanger 1033). The second refrigerant temperature sensor 1058 is used to detect the temperature Tb3 of the refrigerant after passing through the second heat exchanger 1033 (at the outlet). In addition, the second heat exchange temperature sensor 1057 may be a pressure sensor for detecting the pressure in the second heat exchanger 1033. In this case, the refrigerant temperature in the first heat exchanger 1023 is calculated based on the detected value of the pressure.

The compressor unit 1040 includes a third housing 1041, a compressor 1042, a four-way switching valve 1043, and an expansion valve 1044. In addition, the compressor unit 1040 of the present embodiment includes the third housing 1041, but the third housing 1041 may be omitted. In this case, it is preferred that the compressor 1042 and the four-way switching valve 1043 are accommodated in the first housing 1021 of the air supply unit 1020 or the second housing 1031 of the exhaust unit 1030. In addition, although the ventilation system 1E of the present embodiment accommodates the expansion valve 1044 in the compressor unit 1040, the expansion valve 1044 may also be accommodated in the first housing 1021 of the air supply unit 1020 or the second housing 1031 of the exhaust unit 1030.

The compressor unit 1040 includes a low pressure sensor 1052, a discharge pressure sensor 1053, and a discharge temperature sensor 1054. The low pressure sensor 1052 is used to detect the pressure PL of the refrigerant sucked into the compressor 1042. In the following description, this pressure PL is also referred to as the low pressure PL. The discharge pressure sensor 1053 detects the pressure PH of the refrigerant discharged from the compressor 1042. In the following description, this pressure PH is also referred to as the high pressure PH. The discharge temperature sensor 1054 detects the temperature Ta1 of the refrigerant discharged from the compressor 1042.

The compressor 1042 inhales low-pressure gaseous refrigerant and discharges high-pressure gaseous refrigerant. The compressor 1042 has an electric motor whose operating speed can be adjusted by inverter control. The compressor 1042 is a variable capacity type (capacity variable type), and the capacity (capacity) can be changed by inverter control of the motor. However, the compressor 1042 can also be a fixed capacity type. In addition, the compressor 1042 used in the ventilation system 1E of the present invention can also be composed of two or more compressors connected in parallel.

The four-way switching valve 1043 reverses the refrigerant flow in the refrigerant pipe, and switches the refrigerant discharged from the compressor 1042 to one of the first heat exchanger 1023 and the second heat exchanger 1033. As a result, the ventilation system 1E can switch between a cooling operation mode (hereinafter, also referred to as the first operation mode M1) for cooling the outside air OA and a heating operation mode (hereinafter, also referred to as the second operation mode M2) for heating the outside air OA. The expansion valve 1044 is composed of an electric valve that can adjust the refrigerant flow rate and pressure. In the ventilation system 1E, the pressure of the refrigerant provided to the first heat exchanger 1023 or the second heat exchanger 1033 is adjusted by controlling the opening of the expansion valve 1044.

The refrigerant circuit 1050 includes a compressor 1042, a four-way switching valve 1043, an expansion valve 1044, a first heat exchanger 1023, a second heat exchanger 1033, and a refrigerant pipe 1051 (a liquid pipe 1051L and a gas pipe 1051G) connecting these. The refrigerant circuit 1050 circulates the refrigerant between the first heat exchanger 1023 and the second heat exchanger 1033.

In the ventilation system 1E having the above structure, when the air supply unit 1020 cools the outside air OA and supplies air (the first operation mode M1), the four-way switching valve 1043 maintains the state shown by the solid line in FIG. 14. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1042 flows into the second heat exchanger 1033 of the exhaust unit 1030 through the four-way switching valve 1043. At this time, the second heat exchanger 1033 functions as a condenser, and the refrigerant flowing in the second heat exchanger 1033 exchanges heat with the return air RA by the operation of the exhaust fan 1032, condenses, and liquefies. The liquefied refrigerant is decompressed at the expansion valve 1044 and flows into the first heat exchanger 1023. At this time, the first heat exchanger 1023 functions as an evaporator, and the refrigerant exchanges heat with the outside air OA in the first heat exchanger 1023 and evaporates. The outside air OA cooled by the evaporation of the refrigerant is supplied to the indoor 1000S1 as the supply air SA through the supply air fan 1022. The refrigerant evaporated in the first heat exchanger 1023 returns to the compressor unit 1040 via the refrigerant pipe 1051 (gas pipe 1051G), and is sucked into the compressor 1042 via the four-way switching valve 1043.

In the ventilation system 1E having the above structure, when the air supply unit 1020 heats the outside air OA and supplies air (second operation mode M2), the four-way switching valve 1043 maintains the state indicated by the dotted line in FIG. 14. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1042 flows into the first heat exchanger 1023 of the air supply unit 1020 through the four-way switching valve 1043. At this time, the first heat exchanger 1023 functions as a condenser, and the refrigerant exchanges heat with the outside air OA in the first heat exchanger 1023 to condense and liquefy. The outside air OA heated by the condensation of the refrigerant is supplied to the indoor 1000S1 through the air supply fan 1022. The refrigerant liquefied in the first heat exchanger 1023 reaches the compressor unit 1040 through the refrigerant pipe 1051 (liquid pipe 1051L), is reduced to a predetermined low pressure at the expansion valve 1044, and then flows into the second heat exchanger 1033. At this time, the second heat exchanger 1033 functions as an evaporator, and the refrigerant evaporates by exchanging heat with the return air RA in the second heat exchanger 1033. The refrigerant evaporated and gasified in the second heat exchanger 1033 is sucked into the compressor 1042 via the four-way switching valve 1043.

(About the Control Department)

FIG15 is a control block diagram of the ventilation system 1E. As shown in FIG15, the ventilation system 1E has a control unit 1018. The control unit 1018 is a device for controlling the operation of the ventilation system 1E, and is composed of, for example, a processor such as a CPU, a microcomputer having a memory such as a RAM, a ROM, etc. The control unit 1018 can also be implemented as hardware using an LSI, an ASIC, an FPGA, etc. The control unit 1018 performs a predetermined function by executing a program installed in the memory by the processor.

The control unit 1018 is connected to the air supply fan 1022, the exhaust fan 1032, the compressor 1042, the four-way switching valve 1043, and the expansion valve 1044. The control unit 1018 is connected to the air supply temperature sensor 1026, the outside air temperature sensor 1027, the return air temperature sensor 1036, the low pressure sensor 1052, the discharge pressure sensor 1053, the discharge temperature sensor 1054, the first heat exchange temperature sensor 1055, the first refrigerant temperature sensor 1056, the second heat exchange temperature sensor 1057, and the second refrigerant temperature sensor 1058. The control unit 1018 controls the operation of the air supply fan 1022, the exhaust fan 1032, the compressor 1042, the four-way switching valve 1043, the expansion valve 1044, and the low pressure increasing mechanism 1080 based on the detection values of the sensors.

The control unit 1018 calculates the saturation temperature TS of the second heat exchanger 1033 functioning as an evaporator based on the detection value (high pressure PH) of the discharge pressure sensor 1053 during operation in the second operation mode M2. The control unit 1018 obtains the low pressure PL of the refrigerant circuit 1050 based on the detection value of the low pressure sensor 1052. The control unit 1018 obtains the evaporation temperature TE of the second heat exchanger 1033 based on the detection value (temperature Tb2) of the second heat exchange temperature sensor 1057. Alternatively, the control unit 1018 obtains the evaporation temperature TE of the second heat exchanger 1033 based on the obtained low pressure PL.

As described above, the ventilation system 1E of the present invention has the first operation mode M1 and the second operation mode M2 as the operation modes selectable by the user. When the user selects the first operation mode M1 and the operation of the ventilation system 1E is started, the control unit 1018 can use the first heat exchanger 1023 as an evaporator and the second heat exchanger 1033 as a condenser by switching the four-way switching valve 1043. When the user selects the second operation mode M2 and the operation of the ventilation system 1E is started, the control unit 1018 can use the first heat exchanger 1023 as a condenser and the second heat exchanger 1033 as an evaporator by switching the four-way switching valve 1043. In addition, "when the user selects the second operation mode M2 and the operation of the ventilation system 1E is started" mentioned in this description includes the case where the switching of the four-way switching valve 1043 has been completed and the case where the switching of the four-way switching valve 1043 has not been completed.

In the ventilation system 1E of the present invention, when the second operation mode M2 is selected and started, the control unit 1018 sometimes performs low pressure pressure increase control (first control). In addition, in the following description, the operation mode of the ventilation system 1E when the control unit 1018 performs the low pressure pressure increase control is referred to as the low pressure pressure increase mode M3. When the user selects the second operation mode M2 and the operation of the ventilation system 1E is started, the control unit 1018 starts the compressor 1042 and detects the low pressure PL of the refrigerant circuit 1050 or the evaporation temperature TE of the second heat exchanger 1033. When it is determined that the low pressure PL or the evaporation temperature TE is lower than each set threshold value (referred to as the first threshold value in this description), the control unit 1018 switches the operation mode of the ventilation system 1E to the low pressure pressure increase mode M3 to perform the low pressure pressure increase control. Furthermore, when the control unit 1018 does not determine that the low pressure PL or the evaporation temperature TE is lower than the first threshold, it is not necessary to switch the operation mode of the ventilation system 1E to the low pressure increase mode M3 (not executing the low pressure increase control).

The ventilation system 1E having the refrigerant circuit 1050 can recover the heat of the exhaust gas EA into the refrigerant in the refrigerant circuit 1050 by using the first heat exchanger 1023 as a condenser and the second heat exchanger 1033 as an evaporator when operating in the second operation mode M2. In the ventilation system 1E in this case, when the temperature of the exhaust gas EA drops, frost may sometimes form on the second heat exchanger 1033. In this case, the low pressure PL of the refrigerant circuit 1050 drops, and it will be difficult to keep the compressor 1042 running continuously. The control unit 1018 can keep the compressor 1042 running continuously by selecting the low pressure increase mode M3 in this case. In addition, the "continuous operation of the compressor" mentioned here means that after the compressor is started, there will be no state where the compressor cannot be continuously operated (has to be stopped) due to the drop of the low pressure of the refrigerant circuit, and the operation can be continued.

The control unit 1018 stores a first threshold value X for determining whether the conditions for operating in the second operation mode M2 are met when the second operation mode M2 is selected and the ventilation system 1E is started. In the ventilation system 1E of the present invention, as the first threshold value X, a pressure threshold value X1 as the first threshold value X related to the low pressure PL of the refrigerant circuit 1050, a refrigerant temperature threshold value X2 as the first threshold value X related to the evaporation temperature TE of the second heat exchanger 1033, an indoor temperature threshold value X3 as the first threshold value X related to the air temperature of the room 1000S1, i.e., the suction air temperature T3, and an outside air temperature threshold value X4 as the first threshold value related to the air temperature of the outdoor 1000S2, i.e., the outside air temperature T2 are stored. In addition, the control unit 1018 of this embodiment stores the pressure threshold X1, the refrigerant temperature threshold X2, the indoor temperature threshold X3 and the outdoor air temperature threshold X4 as the first threshold X, but the ventilation system 1E of the present invention can also store one of the thresholds X1~X4 in the control unit 1018.

The control unit 1018 stores a second threshold value Y, which is used to determine whether the condition for operating in the second operation mode M2 is met when the control unit 1018 performs the low pressure pressure increase control (in other words, when the ventilation system 1E operates in the low pressure boost mode M3). In the ventilation system 1E of the present invention, as the second threshold value Y, a pressure threshold value Y1 as the second threshold value Y related to the low pressure PL of the refrigerant circuit 1050, a saturation temperature threshold value Y2 as the second threshold value Y related to the saturation temperature TS of the second heat exchanger 1033, and an air temperature threshold value Y3 as the second threshold value Y related to the intake air temperature T3 of the second heat exchanger 1033 are stored. In addition, the control unit 1018 of the present embodiment stores the pressure threshold value Y1, the saturation temperature threshold value Y2, and the air temperature threshold value Y3 as the second threshold value Y, but the ventilation system 1E of the present invention may store at least one of the pressure threshold value Y1, the saturation temperature threshold value Y2, or the air temperature threshold value Y3 in the control unit 1018.

(Regarding control at the start of ventilation system operation)

The operation of the ventilation system 1E at the start of operation is controlled by the control unit 1018 according to the flow shown in FIG. 16 .

As shown in FIG. 16 , when the operation of the ventilation system 1E starts, first, the control unit 1018 determines whether the second operation mode M2 is selected and started (S2501). In step (S2501), if the control unit 1018 determines that the second operation mode M2 is selected and started (yes), the next step (S2502) is executed. In addition, in step (S2501), if the control unit 1018 determines that the second operation mode M2 is not selected and started (no), the control unit 1018 ends the control at the start of the operation. In step (S2502), the control unit 1018 starts the compressor 1042 and enters the next step (S2503).

In step (S2503), the control unit 1018 determines the low pressure PL of the refrigerant circuit 1050. In step (S2503), when the control unit 1018 determines that the low pressure PL is not lower than the first threshold value X (pressure threshold value X1) related to the low pressure PL (No), the next step (S2504) is executed. In step (S2503), when the control unit 1018 determines that the low pressure PL is lower than the first threshold value X (pressure threshold value X1) (Yes), the next step (S2507) is executed.

In step (S2504), the control unit 1018 determines the evaporation temperature TE of the second heat exchanger 1033. In step (S2504), if the control unit 1018 determines that the evaporation temperature TE is not lower than the first threshold value X (refrigerant temperature threshold value X2) related to the evaporation temperature TE (No), the next step (S2505) is executed. In step (S2504), if the control unit 1018 determines that the evaporation temperature TE is lower than the first threshold value X (refrigerant temperature threshold value X2) (Yes), the next step (S2507) is executed.

In step (S2505), the control unit 1018 determines the air temperature of the room 1000S1, that is, the intake air temperature T3. In step (S2505), if the control unit 1018 determines that the intake air temperature T3 is not lower than the first threshold value X (indoor temperature threshold value X3) associated with the intake air temperature T3 (no), the next step (S2506) is executed. In step (S2505), if the control unit 1018 determines that the intake air temperature T3 is lower than the first threshold value X (indoor temperature threshold value X3) (yes), the next step (S2507) is executed.

In step (S2506), the control unit 1018 determines the air temperature of the outdoor 1000S2, that is, the outdoor air temperature T2. In step (S2506), if the control unit 1018 determines that the external air temperature T2 is not lower than the first threshold value X (external air temperature threshold value X4) related to the external air temperature T2 (no), the next step (S2512) is executed. In step (S2506), if the control unit 1018 determines that the external air temperature T2 is lower than the first threshold value X (external air temperature threshold value X4) (yes), the next step (S2507) is executed.

In step (S2507), the control unit 1018 performs low pressure pressure increase control. Specifically, in step (S2507), the control unit 1018 switches the operation mode of the ventilation system 1E to the low pressure pressure increase mode M3, and operates the ventilation system 1E. When the control unit 1018 performs the low pressure pressure increase control, the ventilation system 1E uses the low pressure pressure increase mechanism 1080 described later. After the execution of the low pressure pressure increase control is started, the control unit 1018 further performs step (S2508).

In step (S2508), the control unit 1018 determines the low pressure PL of the refrigerant circuit 1050 during the execution of the low pressure rise control. In step (S2508), if the control unit 1018 determines that the low pressure PL does not exceed the second threshold value Y (pressure threshold value Y1) related to the low pressure PL (no), step (S2509) is executed. In step (S2508), if the control unit 1018 determines that the low pressure PL exceeds the pressure threshold value Y1 (yes), step (S2511) is executed.

In step (S2509), the control unit 1018 determines the saturation temperature TS of the second heat exchanger 1033. In step (S2509), if it is determined that the saturation temperature TS does not exceed the second threshold value Y (saturation temperature threshold value Y2) related to the saturation temperature TS (No), step (S2510) is executed. In step (S2509), if it is determined that the saturation temperature TS exceeds the saturation temperature threshold value Y2 (Yes), step (S2511) is executed.

In step (S2510), the control unit 1018 makes a judgment about the intake air temperature T3 of the second heat exchanger 1033. In step (S2510), if it is judged that the intake air temperature T3 does not exceed the second threshold value Y (air temperature threshold value Y3) related to the intake air temperature T3 (no), the control unit 1018 returns to step (S2508). In step (S2510), if the control unit 1018 judges that the intake air temperature T3 exceeds the air temperature threshold value Y3 (yes), the control unit 1018 executes step (S2511).

In step (S2511), the control unit 1018 ends the low pressure pressure increase control. After the control unit 1018 ends the low pressure pressure increase control, step (S2512) is executed. In step (S2512), the control unit 1018 switches the operation mode of the ventilation system 1E to the second operation mode M2, and operates the ventilation system 1E. Through the above processing, the control of the operation at the start of operation performed by the control unit 1018 (the flow shown in Figure 16) is ended.

The judgment conditions of each step (S2508) to (S2510) are conditions for judging whether the compressor 1042 can be reliably and continuously operated in the second operation mode M2. In other words, in steps (S2508) to (S2510), when any one of the conditions is satisfied, the condition for the compressor 1042 to be reliably and continuously operated in the second operation mode M2 is met. The ventilation system 1E can achieve the condition for the compressor 1042 to be reliably and continuously operated by executing the low pressure pressure increase control (first control). The ventilation system 1E can achieve the condition for the compressor 1042 to be reliably and continuously operated by starting the operation in the second operation mode M2 after the condition for the compressor 1042 to be reliably and continuously operated is met. Furthermore, in the present invention, the judgment of whether to proceed to step (S2507) is performed by judging the low pressure PL in step (S2503), judging the evaporation temperature TE in step (S2504), judging the intake air temperature T3 in step (S2505), and judging the outside air temperature T2 in step (S2506), but the judgment may be performed only by any one of steps (S2503) to (S2506). In the present invention, the judgment of whether to proceed to step (S2511) is performed by judging the low pressure PL in step (S2508), judging the saturation temperature TS in step (S2509), and judging the intake air temperature T3 in step (S2510), but the judgment may be performed only by any one of steps (S2508) to (S2510).

(Detailed implementation of the ventilation system)

As shown in FIG15 , the ventilation system 1E of the present invention includes a low pressure pressure increasing mechanism 1080. In the first to sixth ventilation systems 1F to 1K described below, the structure of the low pressure pressure increasing mechanism 1080 is different. When the ventilation system 1E selects the second operation mode M2 and is started, the low pressure pressure increasing mechanism 1080 is used when executing the low pressure pressure increasing control (refer to FIG16 ). In the following description, the same parts of the first to sixth ventilation systems 1F to 1K are marked with the same symbols, and repeated description of the parts marked with the same symbols is omitted.

(About the 13th Ventilation System 1F)

FIG. 17 shows a thirteenth ventilation system 1F of the thirteenth embodiment of the ventilation system 1E of the present invention. The thirteenth ventilation system 1F shown in FIG. 17 includes an air supply unit 1020, an exhaust unit 1030, and a compressor unit 1040. In the thirteenth ventilation system 1F, the air supply unit 1020, the exhaust unit 1030, and the compressor unit 1040 are an integrated structure. In addition, although the air supply unit 1020, the exhaust unit 1030, and the compressor unit 1040 are configured as an integrated structure in the thirteenth ventilation system 1F shown in this embodiment, the air supply unit 1020 (the first heat exchanger 1023 and the air supply fan 1022), the exhaust unit 1030 (the second heat exchanger 1033 and the exhaust fan 1032), and the compressor unit 1040 (the compressor 1042) may be separately configured in the ventilation system 1E of the present invention.

The 13th ventilation system 1F can be set, for example, outdoors 1000S2. In the 13th ventilation system 1F shown in FIG17, the outlet 1025 of the air supply unit 1020 and the inlet 1034 of the exhaust unit 1030 are directly set on the outer wall surface of the building 1000B. In addition, in this embodiment, the case where the 13th ventilation system 1F is arranged outdoors 1000S2 is illustrated, but the whole or part of the 13th ventilation system 1F can also be arranged indoors 1000S1.

As shown in Fig. 17, the thirteenth ventilation system 1F includes an air conditioner 1081 as a first low pressure increasing mechanism 1080. The air conditioner 1081 includes a refrigerant circuit 1081d including an indoor unit 1081a, an outdoor unit 1081b, and a refrigerant pipe 1081c.

(About air conditioners)

The air conditioner 1081 is installed in the building 1000B to realize air conditioning of the air-conditioned space (indoor 1000S1). The air conditioner 1081 cools and heats the air-conditioned space by performing a vapor compression refrigeration cycle operation. In addition, in this embodiment, the air conditioner 1081 that performs a vapor compression refrigeration cycle operation is illustrated, but as the low-pressure pressure increasing mechanism 1080, the air conditioner is not limited to this, for example, it can also be an air conditioner that uses cold water or hot water provided by a heat source device to realize air conditioning of the target space.

The indoor unit 1081a of the air conditioner 1081 is arranged in the indoor 1000S1, and the outdoor unit 1081b is arranged in the outdoor 1000S2. The indoor unit 1081a and the outdoor unit 1081b are connected by a refrigerant pipe 1081c. The air conditioner 1081 has a refrigerant circuit 1081d for air conditioning. The refrigerant circuit 1081d for air conditioning includes a compressor, a four-way switching valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, etc. (none of which are shown in the figure). The refrigerant circuit 1081d for air conditioning circulates the refrigerant between the indoor unit 1081a and the outdoor unit 1081b through the refrigerant pipe 1081c. The refrigerant circuit 1081d for air conditioning is separated from the refrigerant circuit 1050 of the 13th ventilation system 1F to form an independent circuit. The air conditioner 1081 detects the temperature of the indoor 1000S1.

In the 13th ventilation system 1F, the temperature of the indoor 1000S1 is increased by operating the air conditioner 1081 when the low pressure pressure increase control is performed. In the 13th ventilation system 1F, when the control unit 1018 determines that the temperature of the air in the indoor 1000S1 detected by the air conditioner 1081 exceeds the second threshold value Y (the air temperature threshold value Y3 related to the intake air temperature T3) (refer to FIG. 15), the exhaust fan 1032 is started to operate. In the 13th ventilation system 1F, air having a temperature higher than the air temperature threshold value Y3 related to the intake air temperature T3 is sucked into the second heat exchanger 1033 through the above. In the 13th ventilation system 1F, the frost of the second heat exchanger 1033 is suppressed by operating the air conditioner 1081. In the 13th ventilation system 1F, the air conditioner 1081 can increase the intake air temperature T3 of the second heat exchanger 1033 functioning as an evaporator, thereby suppressing frost on the second heat exchanger 1033 and suppressing a decrease in the low pressure PL of the refrigerant circuit 1050.

In the 13th ventilation system 1F, when the second operation mode M2 is selected and started, the control unit 1018 can forcibly start the air conditioner 1081. In the 13th ventilation system 1F, when the second operation mode M2 is selected and started, the control unit 1018 can also provide information to urge the user to start the air conditioner 1081, so that the user starts the air conditioner 1081. In addition, when the 13th ventilation system 1F and the air conditioner 1081 are not linked, the control unit 1018 can operate the exhaust fan 1032 and measure the intake air temperature T3 after providing the user with information urging the user to start the air conditioner 1081 and after a predetermined time has passed, and the control unit 1018 starts the air conditioner 1081 based on the measured value. In the 13th ventilation system 1F, the control unit 1018 is configured to detect the operating status of the air conditioner 1081. When the second operating mode M2 is selected and started, when the control unit 1018 detects that the air conditioner 1081 is operating, the control unit 1018 can perform low pressure increase control.

In the thirteenth ventilation system 1F, when the low pressure pressure increase control is completed, the control unit 1018 may stop the air conditioner 1081, or the control unit 1018 may continue to operate the air conditioner 1081.

(About the 14th ventilation system 1G)

FIG. 18 is a schematic structural diagram of a ventilation system according to Embodiment 14 of the present invention. FIG. 19 is a schematic structural diagram showing a state in which the ventilation systems according to Embodiments 14 and 15 of the present invention are installed in a building. The 14th ventilation system 1G shown in FIGS. 18 and 19 is Embodiment 14 of the ventilation system 1E of the present invention. The 14th ventilation system 1G is different from the 13th ventilation system 1F in that it includes a second low pressure pressure increasing mechanism 1082 as the second low pressure pressure increasing mechanism 1080.

As shown in FIG. 18 , the 14th ventilation system 1G is provided with a second low pressure pressure increasing mechanism 1082. The second low pressure pressure increasing mechanism 1082 is composed of a bypass pipe 1082a and a valve 1082b. The valve 1082b is, for example, an electric valve, an electromagnetic valve, etc. The bypass pipe 1082a is a pipe for bypassing the discharge pipe 45 and the liquid pipe 1051L connecting the compressor 1042. The bypass pipe 1082a can provide the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1042 to the second heat exchanger 1033 via the liquid pipe 1051L. The valve 1082b can switch the refrigerant flow in the bypass pipe 1082a. When the valve 1082b is opened, the gaseous refrigerant can flow in the bypass pipe 1082a, and when the valve 1082b is closed, the gaseous refrigerant can be prevented from flowing in the bypass pipe 1082a.

The 14th ventilation system 1G opens the valve 1082b and supplies the gaseous refrigerant to the second heat exchanger 1033 through the bypass pipe 1082a, thereby increasing the temperature of the refrigerant flowing in the second heat exchanger 1033, thereby suppressing frost on the second heat exchanger 1033. In the 14th ventilation system 1G, the saturation temperature TS at the outlet of the second heat exchanger 1033 functioning as an evaporator can be increased by the second low-pressure pressure increasing mechanism 1082, thereby suppressing frost on the second heat exchanger 1033 and suppressing a decrease in the low-pressure PL of the refrigerant circuit 1050.

In the fourteenth ventilation system 1G, the control unit 1018 ends the low pressure increase control by closing the valve 1082b.

(About the 15th ventilation system 1H)

FIG20 is a schematic structural diagram of a ventilation system according to Embodiment 15 of the present invention. The fifteenth ventilation system 1H shown in FIGS. 19 and 20 is Embodiment 15 of the ventilation system 1E of the present invention. As shown in FIG20 , the fifteenth ventilation system 1H is different from the thirteenth and fourteenth ventilation systems 1F and 1G in that it includes a third low pressure pressure increasing mechanism 1083 as the third low pressure pressure increasing mechanism 1080.

The 15th ventilation system 1H is provided with a third low pressure pressure increasing mechanism 1083. The third low pressure pressure increasing mechanism 1083 is composed of a bypass duct 1083a and a damper 1083b. The bypass duct 1083a is formed in the third housing 1041, and connects the discharge side of the first housing 1021 and the suction side of the second housing. The bypass duct 1083a can supply a part of the air flow (supply air SA) generated by the air supply unit 1020 to the suction side of the exhaust fan 1032 in the exhaust unit 1030. The damper 1083b includes a valve body and an opening and closing mechanism that can open and close the flow of the supply air SA in the bypass duct 1083a. When the damper 1083b is opened, the supply air SA can flow in the bypass duct 1083a, and when the damper 1083b is closed, the flow of the supply air SA in the bypass duct 1083a can be blocked.

In the 15th ventilation system 1H, when the control unit 1018 determines that the blown air temperature T1 detected by the supply air temperature sensor 1026 exceeds the second threshold value Y (the air temperature threshold value Y3 related to the intake air temperature T3) (refer to FIG. 15), the damper 1083b is opened. The 15th ventilation system 1H can increase the intake air temperature T3 of the second heat exchanger 1033 by opening the damper 1083b and supplying the supply air SA to the intake side of the second heat exchanger 1033 via the bypass duct 1083a. In the 15th ventilation system 1H, the intake air temperature T3 of the second heat exchanger 1033 functioning as an evaporator can be increased by the third low pressure increasing mechanism 1083, thereby suppressing the frost formation of the second heat exchanger 1033 and suppressing the decrease of the low pressure PL of the refrigerant circuit 1050.

In the fifteenth ventilation system 1H, the control unit 1018 ends the low pressure increase control by closing the damper 1083b.

(About the 16th ventilation system 1I)

FIG. 21 is a schematic structural diagram of a ventilation system according to Embodiment 16 of the present invention. The 16th ventilation system 1I shown in FIG. 21 is Embodiment 16 of the ventilation system 1E of the present invention. As shown in FIG. 21 , the structure of the low pressure increasing mechanism 1080 in the 16th ventilation system 1I is different from that in the 13th to 15th ventilation systems 1F to 1H. The 16th ventilation system 1I is different from the 13th to 15th ventilation systems 1F to 1H in that the air supply unit 1020, the exhaust unit 1030, and the compressor unit 1040 are separately arranged in the room 1000S1. In the 16th ventilation system 1I, the air supply unit 1020, the exhaust unit 1030, and the compressor unit 1040 are arranged in the space behind the ceiling of the room R1 which is the ventilation target space of the room 1000S1 (hereinafter referred to as the ceiling back R2). In addition, in the present embodiment, the case where the sixteenth ventilation system 1I is arranged in the room 1000S1 is exemplified, but the whole or a part of the sixteenth ventilation system 1I may be arranged in the outdoor 1000S2.

In the 16th ventilation system 1I, the air supply unit 1020 constitutes a part of the air supply air path 1028. The air supply air path 1028 is an air path connecting the indoor 1000S1 and the outdoor 1000S2. The air supply air path 1028 is composed of a first air supply duct 1028a, a second air supply duct 1028b and the air supply unit 1020. The first air supply duct 1028a connects the outdoor 1000S2 and the air supply unit 1020. Specifically, the first air supply duct 1028a has an air inlet 1028c as one end thereof, and the air inlet 1028c is connected to an opening of the outer wall of the building 1000B, thereby connecting to the outdoor 1000S2. The other end of the first air supply duct 1028a is connected to the air supply unit 1020. The second air supply duct 1028b connects the air supply unit 1020 and the indoor 1000S1. Specifically, the second air supply duct 1028b has an outlet 1028d as one end thereof, and the outlet 1028d is connected to an opening of the ceiling surface of the room 1000S1, thereby communicating with the room 1000S1. The other end of the second air supply duct 1028b is connected to the air supply unit 1020.

In the 16th ventilation system 1I, the exhaust unit 1030 constitutes a part of the exhaust air passage 1038. The exhaust air passage 1038 is an air passage connecting the indoor 1000S1 and the outdoor 1000S2. The exhaust air passage 1038 is composed of a first exhaust duct 1038a, a second exhaust duct 1038b, and the exhaust unit 1030. The first exhaust duct 1038a connects the outdoor 1000S2 and the exhaust unit 1030. Specifically, the first exhaust duct 1038a has an exhaust port 1038c as one end thereof, and the exhaust port 1038c is connected to an opening of the outer wall of the building 1000B, thereby connecting to the outdoor 1000S2. The other end of the first exhaust duct 1038a is connected to the exhaust unit 1030. The second exhaust duct 1038b connects the exhaust unit 1030 and the indoor 1000S1. Specifically, the second exhaust duct 1038b has a suction port 1038d as one end thereof, and the suction port 1038d is connected to an opening of the ceiling surface of the room 1000S1, thereby communicating with the room 1000S1. The other end of the second exhaust duct 1038b is connected to the exhaust unit 1030.

The 16th ventilation system 1I is provided with a 4th low pressure pressure increasing mechanism 1084. The 4th low pressure pressure increasing mechanism 1084 is composed of a bypass duct 1084a and a damper 1084b. The bypass duct 1084a connects the 2nd air supply duct 1028b connected to the blow-out side of the air supply unit 1020 and the 2nd exhaust duct 1038b connected to the suction side of the exhaust unit 1030. The bypass duct 1084a can supply a part of the air flow (supply air SA) generated by the air supply unit 1020 to the suction side of the exhaust fan 1032 in the exhaust unit 1030. The damper 1084b includes a valve body and an opening and closing mechanism that can open and close the flow of the supply air SA in the bypass duct 1084a. When the damper 1084b is opened, the supply air SA can flow in the bypass duct 1084a, and when the damper 1084b is closed, the flow of the supply air SA in the bypass duct 1084a can be blocked.

In the sixteenth ventilation system 1I, when the control unit 1018 determines that the blown air temperature T1 detected by the supply air temperature sensor 1026 exceeds the second threshold value Y (the air temperature threshold value Y3 related to the intake air temperature T3), the damper 1084b is opened. The sixteenth ventilation system 1I supplies the supply air SA to the intake side of the second heat exchanger 1033 via the bypass duct 1084a by opening the damper 1084b, thereby increasing the intake air temperature T3 of the second heat exchanger 1033. In the sixteenth ventilation system 1I, the intake air temperature T3 of the second heat exchanger 1033 functioning as an evaporator can be increased by the fourth low pressure increasing mechanism 1084, thereby suppressing the frosting of the second heat exchanger 1033 and suppressing the decrease in the low pressure PL of the refrigerant circuit 1050.

In the sixteenth ventilation system 1I, the control unit 1018 ends the low pressure increase control by closing the damper 1084b.

(About the 17th ventilation system 1J)

FIG22 is a schematic diagram of the structure of a ventilation system according to Embodiment 17 of the present invention. The seventeenth ventilation system 1J shown in FIG22 is the seventeenth embodiment of the ventilation system 1E of the present invention. As shown in FIG22, the structure of the low pressure pressure increasing mechanism 1080 of the seventeenth ventilation system 1J is different from that of the sixteenth ventilation system 1I. The seventeenth ventilation system 1J includes a fifth low pressure pressure increasing mechanism 1085 as the fifth low pressure pressure increasing mechanism 1080.

The fifth low pressure increasing mechanism 1085 is composed of an air intake duct 1085a, a damper 1085b and a ceiling back temperature sensor 1085c. The air intake duct 1085a is connected to the second exhaust duct 1038b and is open at the ceiling back R2. By driving the exhaust fan 1032, the air at the ceiling back R2 can be introduced into the exhaust unit 1030. In the seventeenth ventilation system 1J, the air introduced into the ceiling back R2 of the exhaust unit 1030 can flow in the second heat exchanger 1033. The damper 1085b is a valve that can open and close the flow of air in the air intake duct 1085a. When the damper 1085b is opened, the air at the ceiling back R2 can be sucked into the air intake duct 1085a, and when the damper 1085b is closed, the air flow in the air intake duct 1085a can be blocked.

In the seventeenth ventilation system 1J, the ceiling back temperature sensor 1085c is connected to the control unit 1018. The ceiling back temperature sensor 1085c can detect the temperature of the air on the ceiling back R2. In the seventeenth ventilation system 1J, when the control unit 1018 determines that the temperature T4 of the air on the ceiling back R2 exceeds the second threshold value Y (the air temperature threshold value Y3 related to the intake air temperature T3), the air door 1085b is opened to allow the air on the ceiling back R2 to flow through the second heat exchanger 1033 via the intake duct 1085a.

The seventeenth ventilation system 1J, by opening the air door 1085b, supplies the air from the ceiling back R2 to the suction side of the second heat exchanger 1033 through the suction duct 1085a, thereby increasing the suction air temperature T3 of the second heat exchanger 1033. In the seventeenth ventilation system 1J, the fifth low-pressure pressure increasing mechanism 1085 can increase the suction air temperature T3 of the second heat exchanger 1033 functioning as an evaporator, thereby suppressing frost on the second heat exchanger 1033 and suppressing a decrease in the low-pressure PL of the refrigerant circuit 1050.

In the seventeenth ventilation system 1J, the control unit 1018 ends the low pressure increase control by closing the damper 1085b.

(About the 18th ventilation system 1K)

Fig. 23 is a schematic structural diagram of a ventilation system according to Embodiment 18 of the present invention. The eighteenth ventilation system 1K shown in Fig. 23 is Embodiment 18 of the ventilation system 1E of the present invention. As shown in Fig. 23, the structure of the low pressure pressure increasing mechanism 1080 of the eighteenth ventilation system 1K is different from that of the sixteenth and seventeenth ventilation systems 1I and 1J.

The 18th ventilation system 1K is provided with a 6th low pressure pressure increasing mechanism 1086 as the 6th low pressure pressure increasing mechanism 1080. The 6th low pressure pressure increasing mechanism 1086 includes a louver 1086a configured to be rotatable around a rotation axis and a mechanism (not shown) for rotating the louver 1086a. The louver 1086a is arranged near the blow-out port 1028d in the room 1000S1. The louver 1086a is configured to be rotatable between a storage position 1000P1 in which the blow-out direction of the supply air SA blown out from the blow-out port 1028d is not changed and an operating position 1000P2 in which the blow-out direction of the supply air SA blown out from the blow-out port 1028d is changed.

In the 18th ventilation system 1K, when the control unit 1018 determines that the blown air temperature T1 detected by the supply air temperature sensor 1026 exceeds the second threshold value Y (the air temperature threshold value Y3 related to the intake air temperature T3), the louver 1086a is rotated from the storage position 1000P1 to the operation position 1000P2. In the 18th ventilation system 1K, the supply air SA blown out from the blow-out port 1028d is blocked by the louver 1086a and its blowing direction is changed, and it flows to the suction port 1038d. In the 18th ventilation system 1K, the supply air SA having a higher temperature than the air in the room 1000S1 is actively sucked from the suction port 1038d, so that the intake air temperature T3 of the second heat exchanger 1033 is increased. In the 18th ventilation system 1K, the intake air temperature T3 of the second heat exchanger 1033 functioning as an evaporator can be increased by the sixth low-pressure pressure increasing mechanism 1086, thereby suppressing frost on the second heat exchanger 1033 and suppressing a decrease in the low-pressure PL of the refrigerant circuit 1050.

In the eighteenth ventilation system 1K, the control unit 1018 ends the low pressure increase control by changing the rotation position of the louver 1086a from the operating position 1000P2 to the storage position 1000P1.

[Effects of the Embodiments]

(1) The ventilation system 1E shown in the above embodiment is connected to the compressor 1042, the first heat exchanger 1023 and the second heat exchanger 1033 by the refrigerant pipe 1051, and includes a refrigerant circuit 1050 with refrigerant flowing inside, an air supply fan 1022 for supplying air from the outdoor 1000S2 to the indoor 1000S1 via the first heat exchanger 1023, an exhaust fan 1032 for exhausting air from the indoor 1000S1 to the outdoor 1000S2 via the second heat exchanger 1033, and a control unit 1018. The control unit 1018 starts the compressor 1042 while making the second heat exchanger 1033 function as an evaporator, and when it is determined that the low pressure PL of the refrigerant circuit 1050, or the evaporation temperature TE of the second heat exchanger 1033, or the temperature of the indoor 1000S1 (intake air temperature T3), or the temperature of the outdoor 1000S2 (external air temperature T2) is lower than the first threshold value X related to the low pressure PL of the refrigerant circuit 1050, or the evaporation temperature TE of the second heat exchanger 1033, or the intake air temperature T3, or the external air temperature T2, the low pressure increasing control is performed to increase the low pressure PL of the refrigerant circuit 1050.

According to the ventilation system 1E having the above-described structure, the compressor 1042 can be reliably and continuously operated while the second heat exchanger 1033 is made to function as an evaporator, in the ventilation system having the refrigerant circuit 1050 capable of recovering heat from the exhaust gas EA.

(2) In the 14th ventilation system 1G shown in the above embodiment, the refrigerant circuit 1050 includes a bypass pipe 1082a for connecting the discharge pipe 45 of the compressor 1042 and the second heat exchanger 1033 or the liquid pipe 1051L connected to the second heat exchanger 1033, and a valve 1082b provided in the bypass pipe 1082a. In the 14th ventilation system 1G, the control unit 1018 opens the valve 1082b under the low pressure pressure increase control (first control).

In this case, the high-temperature and high-pressure gas refrigerant can be supplied to the second heat exchanger 1033 under the low-pressure pressure increase control. Thus, frost formation on the second heat exchanger 1033 can be suppressed.

(3) In the 14th ventilation system 1G shown in the embodiment, the control unit 1018, when the valve 1082b is open, determines that the low pressure PL of the refrigerant circuit 1050, the saturation temperature TS of the second heat exchanger 1033, or the intake air temperature T3 of the exhaust fan 1032 exceeds the second threshold value Y related to the low pressure PL of the refrigerant circuit 1050, the saturation temperature TS of the second heat exchanger 1033, or the intake air temperature T3 of the second heat exchanger 1033, the valve 1082b is closed.

In this case, when the conditions for causing the second heat exchanger 1033 to function as an evaporator are met during execution of the low pressure pressure increase control, the low pressure pressure increase control can be ended.

(4) In each ventilation system 1F, 1H to 1K shown in the embodiment, the control unit 1018 causes the second heat exchanger 1033 to inhale air having a temperature higher than the second threshold value Y (air temperature threshold value Y3) related to the inhaled air temperature T3 in the low pressure pressure increase mode M3 for performing low pressure pressure increase control.

In this case, during execution of the low pressure increase control, air having a temperature higher than the second threshold value Y (air temperature threshold value Y3) can be caused to flow into the second heat exchanger 1033. Thus, frost formation on the second heat exchanger 1033 can be suppressed.

(5) In the eighteenth ventilation system 1K shown in the above embodiment, the control unit 1018 adjusts the blowing direction of the air supply fan 1022 in the low pressure pressure increase mode M3 for performing low pressure pressure increase control so as to guide the air blown out from the air supply fan 1022 to the suction side of the exhaust fan 1032.

In this case, during execution of the low pressure increase control, air having a temperature higher than the second threshold value Y (air temperature threshold value Y3 ) associated with the intake air temperature T3 can be caused to flow into the second heat exchanger 1033 .

(6) In the 13th ventilation system 1F shown in the embodiment, there is also an air conditioner 1081 for performing air conditioning in the indoor room 1000S1. The control unit 1018 drives the exhaust fan 1032 when the air temperature of the indoor room 1000S1 becomes higher than the second threshold value Y (air temperature threshold value Y3) through the adjustment of the air conditioner 1081 in the low pressure pressure increase mode M3 for performing low pressure pressure increase control.

In this case, during execution of the low pressure increase control, air having a temperature higher than the second threshold value Y (air temperature threshold value Y3 ) associated with the intake air temperature T3 can be caused to flow into the second heat exchanger 1033 .

The above embodiments and modified examples show examples of methods for suppressing frost. The methods shown in the above embodiments and modified examples are not limited to the use of this method, and can be used in combination with one or more methods shown in other embodiments and modified examples.

According to the above embodiments and variations, by performing the control as described above, frost formation (for example, on the second heat exchanger) can be suppressed, and the ventilation operation that relies on supplying air to the indoor space and exhausting air to the outdoors can be continued without stopping. The so-called suppression of frost formation is not limited to avoiding frost formation, but means that even in the case of frost formation, control is performed to prevent frost growth. In the ventilation device or ventilation system of the embodiment and variation, by suppressing frost formation and continuing the ventilation operation, the comfort of the living space can be maintained.

The number of air supply units and exhaust units shown in the above embodiments and modified examples is an example. The number of air supply units and the number of exhaust units can be determined according to the living space. For example, the number of air supply units can be one or more, and the number of exhaust units can also be one or more. In addition, the control unit shown in the above embodiments and modified examples represents one method and can be included in any device.

The above describes the embodiments, but it should be understood that various changes can be made in form or detail without departing from the spirit and scope of the claims. Various modifications and improvements can also be achieved by combining or replacing part or all of other embodiments.

This application claims priority based on Japanese patent applications No. 2021-204798 and No. 2021-205609 filed on December 17, 2021, and all contents of the above Japanese patent applications are cited in this application.

Symbol Description

1.1A, 1B, 1C, 1D_1, 1D_2, 1D_3 ventilation device

2.2C air conditioner

10, 110, 210, 310, 410A, 410B, 510A, 510B, 510C, 730 exhaust units

11 Fan

12 2nd heat exchanger

13, 113, 213, 313, 413A, 413B control unit

14 Temperature detection unit

15 Driving motor

16 Electric valve

20, 220A, 220B, 320A, 320B, 420A, 420B, 520A, 520B, 520C air supply unit

21 Fan

221st heat exchanger

23, 423A, 423B control unit

24 Temperature detection unit

25 Drive motor

26 Electric valve

40 Open and close damper

50, 350, 450, 550A, 550B, 550C, 650 compressor units

51 Drive motor

52, 452 control unit

53 compressor

54 four-way valve

55 Electric valve

56 Bypass Electric Valve

70, 470, 571, 572, 573 outdoor units

71, 471 control unit

81, 82, 581, 582, 583, 584, 585, 586, 587, 588 air conditioner indoor units

400, 500, 600 upper control device

601, 602 electric valve

732 3rd heat exchanger

733 Control Department

F1, F2, F3, F4, F401, F402, F403, F404 refrigerant circuit

F5, F501, F502, F503, F601, F602, F603 connecting pipes

F6 bypass flow path

P1, P101 air supply path

P2, P103 return air flow

P2A No. 1 return air branch

P2B Second return air branch

P102 bypass flow path

P201, P401 1st air supply path

P202, P402 Second air supply path

P203 Return air flow

P403 1st return air flow path

P404 Second return air flow path

1E Ventilation System

1F No. 13 Ventilation System

1G No. 14 ventilation system

1H No. 15 ventilation system

1I No. 16 Ventilation System

1J No. 17 ventilation system

1K No. 18 ventilation system

1018 Control Department

1022 air supply fan

1023 No.1 Heat Exchanger

1032 Exhaust Fan

1033 2nd heat exchanger

1042 compressor

1045 spit out pipe

1050 Refrigerant circuit

1051 Refrigerant Pipe

1051L Liquid Tube

1080 Low pressure rise mechanism

1081 Air Conditioner

1082a bypass pipe

1082b valve

1000S1 Indoor

1000S2 Outdoor

PL low pressure

TE Evaporation Temperature

TS saturation temperature

T2 Outdoor temperature

T3 Intake air temperature

X1st threshold

Y 2nd Threshold

Y3 air temperature threshold (second threshold related to intake air temperature)

SA air supply (air blown from the air supply fan)

Claims (33)

1. A ventilation device, comprising:

A compressor;

A1 st heat exchanger functioning as a condenser or an evaporator;

a 1 st air flow path for supplying air introduced from the outside to the indoor space after passing through the 1 st heat exchanger;

A2 nd heat exchanger functioning as a condenser or an evaporator;

A 2 nd air flow path for exhausting the air introduced from the indoor space to the outside after passing through the 2 nd heat exchanger;

A refrigerant circuit in which the compressor, the 1 st heat exchanger, and the 2 nd heat exchanger are connected by refrigerant pipes, and in which a refrigerant flows; and

And a control unit that detects whether or not a predetermined criterion indicating a possibility of frosting of the 2 nd heat exchanger is satisfied while the 2 nd heat exchanger is functioning as an evaporator, and when it is detected that the predetermined criterion is satisfied, controls the temperature of the refrigerant flowing through the 2 nd heat exchanger so as to be a temperature at which frosting of the 2 nd heat exchanger is not performed.

2. The ventilation device according to claim 1, wherein,

The control unit detects whether or not the predetermined criterion is satisfied while the 2 nd heat exchanger is functioning as an evaporator, and outputs a signal for controlling an air conditioner provided in the indoor space to control the temperature of the refrigerant flowing through the 2 nd heat exchanger when the predetermined criterion is detected to be satisfied.

3. A ventilation device according to claim 2, wherein,

When the predetermined criterion is satisfied, the control unit outputs a signal indicating that the temperature currently set in the air conditioner is to be raised to the air conditioner provided in the indoor space.

4. A ventilation device according to claim 2, wherein,

The ventilator further includes a 2 nd ventilation unit that adjusts an amount of air flowing into the 2 nd heat exchanger via the 2 nd air flow path,

The control unit drives the 2 nd ventilation unit when the air temperature of the indoor space becomes higher than a 2 nd threshold value after outputting a signal for controlling the air conditioner.

5. The ventilation device according to claim 1, wherein,

The refrigerant circuit has a bypass line that flows the refrigerant into the 2 nd heat exchanger without passing through the 1 st heat exchanger while the 2 nd heat exchanger functions as an evaporator,

The control unit controls the refrigerant compressed by the compressor to flow into the 2 nd heat exchanger through the bypass pipe when the predetermined criterion is satisfied.

6. The ventilation device according to claim 5, wherein,

The control unit performs control to close a valve for allowing the refrigerant compressed by the compressor to flow into the 2 nd heat exchanger through the bypass line when it is determined that the low pressure of the refrigerant circuit, the saturation temperature of the 2 nd heat exchanger, or the suction air temperature of the 2 nd heat exchanger exceeds a 2 nd threshold value related to the low pressure of the refrigerant circuit, the saturation temperature of the 2 nd heat exchanger, or the suction air temperature of the 2 nd heat exchanger after the control to flow into the 2 nd heat exchanger through the bypass line.

7. The ventilation device of claim 1, further comprising:

A 3 rd air flow path for passing air introduced from a room different from the 2 nd air flow path in the indoor space through the 2 nd heat exchanger; and

A 1 st guide mechanism for switching whether or not to guide the air to the 2 nd heat exchanger via the 3 rd air flow path,

The control unit controls the 1 st guide mechanism to guide the air to the 2 nd heat exchanger via the 3 rd air flow path when the predetermined criterion is satisfied.

8. The ventilation device according to claim 1, wherein,

The ventilator further has a 2 nd ventilation unit that adjusts the amount of air flowing into the 2 nd heat exchanger through the 2 nd air flow path,

The control unit performs control to increase the amount of air flowing into the 2 nd heat exchanger in the 2 nd ventilation unit when the predetermined criterion is satisfied, as compared with before the predetermined criterion is satisfied.

9. The ventilation device of claim 8, further comprising:

a plurality of said 2 nd heat exchangers; and

The 2 nd ventilation units corresponding to each of the 2 nd heat exchangers,

The control unit performs control to increase the amount of air flowing into the 2 nd heat exchanger, when the predetermined criterion is satisfied, with respect to the 2 nd ventilation unit corresponding to any one of the plurality of 2 nd heat exchangers, as compared with before the predetermined criterion is satisfied, while the plurality of 2 nd heat exchangers function as evaporators.

10. A ventilation device according to claim 9, wherein,

The control unit is configured to control, when the 2 nd ventilation unit corresponding to any one of the plurality of 2 nd heat exchangers is controlled to increase the air amount, the 2 nd ventilation unit corresponding to the other 2 nd heat exchanger of the plurality of 2 nd heat exchangers to reduce the air amount flowing into the 2 nd heat exchanger as compared with before the predetermined standard is satisfied.

11. A ventilation device according to claim 9, wherein,

The ventilator further includes a1 st ventilation unit that adjusts an amount of air flowing into the 1 st heat exchanger through the 1 st air flow path,

The control unit controls the 1 st ventilation unit to increase the air amount flowing into the 1 st heat exchanger in comparison with the air amount before the predetermined criterion is satisfied, based on the air amount increased for the 2 nd ventilation unit, when the control unit controls the 2 nd ventilation unit corresponding to any one of the plurality of 2 nd heat exchangers to increase the air amount.

12. The ventilation device of claim 1, further comprising:

A 1 st ventilation unit that adjusts an amount of air flowing into the 1 st heat exchanger via the 1 st air flow path; and

A2 nd ventilation unit configured to adjust an amount of air flowing into the 2 nd heat exchanger via the 2 nd air flow path,

The control unit is configured to, when a signal indicating that defrosting operation is to be performed is received from an air conditioner provided in the indoor space while the 2 nd heat exchanger is functioning as an evaporator, consider that the predetermined criterion is satisfied, perform control to increase the amount of air flowing into the 1 st heat exchanger for the 1 st ventilation unit and to increase the amount of air flowing into the 2 nd heat exchanger for the 2 nd ventilation unit, as compared with before the predetermined criterion is satisfied.

13. The ventilation device of claim 1, further comprising:

a bypass flow path for guiding the air heat-exchanged by the 1 st heat exchanger to the 2 nd heat exchanger; and

A2 nd guide mechanism for switching whether or not to guide the air to the 2 nd heat exchanger via the bypass flow path,

The control unit controls the 2 nd guide mechanism to guide air to the 2 nd heat exchanger via the bypass flow path when the predetermined criterion is satisfied.

14. The ventilation device of claim 1, wherein,

The control unit adjusts the air flow by a flow adjustment mechanism so as to guide the air blown into the indoor space from the 1 st air flow path to the suction side of the 2 nd air flow path when the predetermined criterion is satisfied.

15. The ventilation device according to claim 1, wherein,

The ventilation device further includes a 2 nd ventilation unit that adjusts an amount of air flowing into the 2 nd heat exchanger via the 2 nd air flow path,

The control unit stops the compressor and controls the 2 nd ventilation unit to allow air passing through the 2 nd air flow path to flow into the 2 nd heat exchanger when the predetermined criterion is satisfied.

16. The ventilation device of claim 1, further comprising:

a plurality of said 2 nd heat exchangers; and

A2 nd ventilation unit corresponding to each of the 2 nd heat exchangers,

The refrigerant circuit further includes a1 st valve portion for adjusting an opening of a flow path flowing into the 2 nd heat exchanger for each of the 2 nd heat exchangers,

The control unit performs control of closing the 1 st valve units corresponding to the 2 nd heat exchangers satisfying the predetermined reference in a predetermined order and performing control of flowing air passing through the 2 nd air flow path into the 2 nd heat exchanger for the 2 nd ventilation unit corresponding to the 2 nd heat exchanger satisfying the predetermined reference when the temperature-related information detected from the 2 nd heat exchangers satisfies the predetermined reference.

17. The ventilation device of claim 1, further comprising:

A 1 st ventilation unit that adjusts an amount of air flowing into the 1 st heat exchanger via the 1 st air flow path; and

A2 nd ventilation unit configured to adjust an amount of air flowing into the 2 nd heat exchanger via the 2 nd air flow path,

The control unit controls the 1 st ventilation unit and the 2 nd ventilation unit so that an amount of air discharged to the outside through the 2 nd air flow path becomes larger than an amount of air supplied to the indoor space through the 1 st air flow path when the predetermined criterion is satisfied.

18. The ventilation device according to claim 1, wherein,

The control unit controls the 1 st heat exchanger so that the temperature of the air passing through the 1 st heat exchanger becomes lower than the temperature set by the air conditioner provided in the indoor space when the predetermined criterion is satisfied.

19. The ventilation device according to claim 1, wherein,

The ventilator includes a plurality of combinations of the compressor, the 1 st heat exchanger, the 2 nd heat exchanger, the refrigerant circuit, and the 2 nd ventilation unit corresponding to the 2 nd heat exchanger,

The control unit controls the 2 nd ventilation unit corresponding to the 2 nd heat exchanger satisfying the predetermined reference and controls the air flowing into the 2 nd heat exchanger through the 2 nd air flow path while controlling the compressors corresponding to the 2 nd heat exchanger satisfying the predetermined reference to stop in a predetermined order when the temperature-related information detected from the plurality of 2 nd heat exchangers satisfies the predetermined reference.

20. The ventilation device according to any one of claims 1 to 19, wherein,

The control unit determines, as a predetermined criterion indicating a possibility of frosting of the 2 nd heat exchanger, whether or not the low pressure of the refrigerant circuit, the evaporation temperature of the 2 nd heat exchanger, or the temperature of the indoor space, or the outdoor temperature is lower than a1 st threshold value related to the low pressure of the refrigerant circuit, the evaporation temperature of the 2 nd heat exchanger, or the temperature of the indoor space, or the outdoor temperature.

21. The ventilation device of any one of claims 1 to 20, further comprising:

a1 st casing that accommodates the 1 st heat exchanger and at least a part of the 1 st air flow path; and

A 2 nd casing accommodating the 2 nd heat exchanger and at least a part of the 2 nd air flow path,

The 1 st housing is separable from the 2 nd housing.

22. A ventilation device according to claim 21, wherein,

The control unit performs control to reduce the rotation number of the compressor in comparison with the rotation number before the predetermined criterion is satisfied when the predetermined criterion is satisfied.

23. A ventilation device according to claim 21, wherein,

The refrigerant circuit has a 2 nd valve portion provided between the 1 st heat exchanger and the 2 nd heat exchanger for adjusting an opening degree of a flow path,

The control unit performs control to increase the opening degree of the 2 nd valve unit in comparison with that before the predetermined criterion is satisfied when the predetermined criterion is satisfied.

24. The ventilation device according to claim 1, wherein,

The ventilation device further includes a3 rd valve portion, the 3 rd valve portion being located downstream of the 2 nd heat exchanger in the refrigerant flow in the refrigerant circuit with respect to the 2 nd heat exchanger when the 2 nd heat exchanger functions as an evaporator,

The control unit further performs control to tighten the 3 rd valve portion when the predetermined criterion is satisfied when the 2 nd heat exchanger functions as an evaporator, as compared with before the predetermined criterion is satisfied.

25. The ventilation device of claim 24, further comprising:

a 3 rd heat exchanger functioning as a condenser or an evaporator; and

A4 th air flow path for discharging the air after heat exchange between the outdoor air and the refrigerant flowing through the 3 rd heat exchanger to the outside,

In the refrigerant circuit, the 3 rd heat exchanger is connected to the compressor, the 1 st heat exchanger, and the 2 nd heat exchanger through the refrigerant pipe.

26. An air conditioning system, wherein,

The air conditioning system comprises a ventilation device, an air conditioner and a control part,

The ventilation device includes:

a 1 st heat exchanger functioning as a compressor, a condenser, or an evaporator during a heat recovery ventilation operation;

a 1 st air flow path for supplying air introduced from the outside to the indoor space after passing through the 1 st heat exchanger;

A2 nd heat exchanger functioning as a condenser or an evaporator;

A2 nd air flow path for exhausting air introduced from the indoor space to the outside after passing through the 2 nd heat exchanger; and

A refrigerant circuit formed by connecting the compressor, the 1 st heat exchanger and the 2 nd heat exchanger through refrigerant pipes, and having a refrigerant flowing therein,

The air conditioner includes:

a 3 rd heat exchanger functioning as a condenser or an evaporator; and

An air conditioning indoor unit configured to exchange heat between air in the indoor space and refrigerant flowing through the 3 rd heat exchanger, to discharge air into the indoor space,

The control unit detects whether or not a predetermined criterion indicating a possibility of frosting of the 2 nd heat exchanger is satisfied, and when the predetermined criterion is satisfied, controls the temperature of the refrigerant flowing through the 2 nd heat exchanger to be a temperature at which the 2 nd heat exchanger does not frost, or controls operation for frosting of the 2 nd heat exchanger after frosting of the 2 nd heat exchanger, based on power consumption of the ventilation device and the air conditioner required for controlling the temperature of the refrigerant flowing through the 2 nd heat exchanger to be a temperature at which the 2 nd heat exchanger does not frost, and power consumption required for operating the ventilation device and the air conditioner for removing frosting of the 2 nd heat exchanger after frosting of the 2 nd heat exchanger.

27. A ventilation method, wherein,

When a ventilation device including a1 st heat exchanger functioning as a compressor, a condenser, or an evaporator, a1 st air passage for supplying air introduced from the outside to an indoor space after passing through the 1 st heat exchanger, a2 nd heat exchanger functioning as a condenser or an evaporator, a2 nd air passage for discharging air introduced from the indoor space to the outside after passing through the 2 nd heat exchanger, and a refrigerant circuit connecting the compressor and the 1 st heat exchanger and the 2 nd heat exchanger through a refrigerant pipe and having a refrigerant flowing therein is controlled, while the 2 nd heat exchanger functions as an evaporator, it is detected whether a predetermined criterion indicating a possibility of frosting of the 2 nd heat exchanger is satisfied, and when it is detected that the predetermined criterion is satisfied, a temperature of the refrigerant flowing in the 2 nd heat exchanger is controlled so as to be a temperature at which frosting of the 2 nd heat exchanger is not caused.

28. A ventilation system, comprising:

A refrigerant circuit formed by connecting a compressor, a1 st heat exchanger and a 2 nd heat exchanger through refrigerant pipelines, wherein the refrigerant flows in the refrigerant circuit;

A supply fan for supplying outdoor air to the indoor via the 1 st heat exchanger;

an exhaust fan for exhausting the indoor air to the outside via the 2 nd heat exchanger; and

The control part is used for controlling the control part to control the control part,

The control unit starts the compressor when the 2 nd heat exchanger is caused to function as an evaporator, and when it is determined that the low pressure of the refrigerant circuit, the evaporation temperature of the 2 nd heat exchanger, the indoor temperature, or the outdoor temperature is lower than a1 st threshold value related to the low pressure of the refrigerant circuit, the evaporation temperature of the 2 nd heat exchanger, the indoor temperature, or the outdoor temperature, performs 1 st control to raise the low pressure of the refrigerant circuit.

29. The ventilation system of claim 28, wherein,

The refrigerant circuit has a discharge pipe of the compressor, a bypass pipe connected to the 2 nd heat exchanger or a liquid pipe connected to the 2 nd heat exchanger, and a valve provided in the bypass pipe,

The control part opens the valve in the 1 st control state.

30. The ventilation system of claim 29, wherein,

The control unit closes the valve when it is determined that the low pressure of the refrigerant circuit, or the saturation temperature of the 2 nd heat exchanger, or the suction air temperature of the 2 nd heat exchanger exceeds a2 nd threshold value related to the low pressure of the refrigerant circuit, or the saturation temperature of the 2 nd heat exchanger, or the suction air temperature of the 2 nd heat exchanger, when the valve is opened.

31. The ventilation system of claim 28, wherein,

The control unit causes the 2 nd heat exchanger to suck air having a higher temperature than a2 nd threshold value related to a sucked air temperature in the 1 st control state.

32. The ventilation system of claim 31, wherein,

The control unit adjusts the blowing direction of the air supply fan so as to guide the air blown from the air supply fan to the suction side of the exhaust fan in the 1 st control state.

33. The ventilation system of claim 31, wherein,

The ventilation system further includes an air conditioner that adjusts the indoor air,

The control unit drives the exhaust fan when the indoor air temperature becomes higher than the 2 nd threshold value by the air conditioner in the 1 st control state.