JP2011174639A - Air conditioner - Google Patents

Abstract

An object of the present invention is to enable continuous heating operation even after completion of frost prevention operation.
In order to achieve the above object, the present invention provides a bypass circuit that connects a discharge side of a compressor and an inlet side during heating operation of an outdoor heat exchanger, and a bypass solenoid valve that connects and disconnects the bypass circuit. And a control device for controlling the bypass solenoid valve and controlling the number of rotations of the compressor. In the control device, the outdoor heat exchanger may be frosted during heating operation. In the case of determining whether or not there is a risk of frost formation from a state where there is a risk of frost formation, the rotation speed of the compressor is decreased, and after the rotation speed reaches a predetermined value, the bypass Shut off the circuit.
[Selection] Figure 1

Description

  The present invention relates to an air conditioner, and is particularly suitable for an air conditioner having a refrigeration cycle capable of heating operation.

  In a conventional air conditioner equipped with a refrigeration cycle capable of heating operation, during the heating operation, the temperature of the outdoor heat exchanger becomes 0 ° C. or less as the outside air temperature decreases, and the moisture in the outside air becomes frost and the outdoor heat exchanger. Adhere to. When the heating operation is continued in this state, frost grows gradually, hindering the heat exchange performance of the outdoor heat exchanger, resulting in a problem that the heating capacity is lowered.

  In order to prevent this, an operation for detecting frost formation on the outdoor heat exchanger and melting the frost (hereinafter referred to as defrosting operation) is performed. For the defrosting operation, a reverse cycle method and a bypass method are known.

  In the reverse cycle method, the refrigeration cycle is switched to the cooling cycle by switching the switching valve, the operation of the blower of the indoor unit and the outdoor unit is stopped, and the high-temperature and high-pressure gas refrigerant discharged from the compressor is transferred to the outdoor heat exchanger. The frost attached to the outdoor heat exchanger is melted by flowing it. Therefore, during this defrosting operation, the heating capacity becomes zero and the temperature of the indoor heat exchanger operates as an evaporator to lower its temperature. It was one of the complaints about the machine.

  In one bypass system, defrosting can be performed while heating is continued. Therefore, this defrosting operation is referred to as a frost prevention operation. Since a part of the amount of heat released into the room is used for defrosting, it takes time for defrosting, heating capacity is lowered, and room temperature is lowered.

  In either method, during the defrosting operation, the heating capacity is lowered or the heating operation is stopped and the room temperature is lowered. Therefore, it is desirable to finish the defrosting operation in a short time as much as possible.

  In order to shorten such a defrost period, the technique like patent document 1 which heats a refrigerant | coolant and a compressor by generating loss heat to a compressor drive motor during a defrost operation is known.

JP 2010-8003 A

  However, in the air conditioner of patent document 1, it moves to the heating operation preparation period after completion | finish of a defrost operation, and will stop a compressor in the said period. Therefore, heating operation cannot be performed during this period.

  Further, if the bypass circuit is immediately shut off after the defrosting operation, the discharge pressure of the compressor increases, the compressor operating current increases, and the pressure protection control or current protection control is activated to stop the air conditioner. In some cases, heating operation cannot be performed during this period.

  An object of the present invention is to enable continuous heating operation even after completion of the frost prevention operation.

In order to achieve the above object, the present invention
A bypass circuit connecting the discharge side of the compressor and the inlet side of the outdoor heat exchanger during heating operation;
A bypass solenoid valve for communicating / blocking the bypass circuit;
A control device for controlling the number of revolutions of the compressor and controlling the bypass solenoid valve;
With
In the control device,
When determining whether there is a risk of frost formation on the outdoor heat exchanger during heating operation, when the state where there is no risk of frost formation from a state where there is a risk of frost formation,
Decreasing the rotation speed of the compressor,
After the rotational speed reaches a predetermined value, the bypass circuit is shut off.

  According to the present invention, a continuous heating operation can be performed even after the frosting prevention operation is completed.

It is a whole block diagram of the air conditioner of 1st Embodiment of this invention. It is a flowchart which shows the control method of the air conditioner of FIG. It is a timing chart which shows the conventional control method. It is a timing chart which shows the control method of the air conditioner of this invention.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or equivalent.

(First embodiment)
The air conditioner of 1st Embodiment of this invention is demonstrated using FIG.1 and FIG.2, FIG.3, FIG.4.

  First, the overall configuration, functions, and the like of the air conditioner 50 of the first embodiment will be described with reference to FIG. FIG. 1 is an overall configuration diagram of an air conditioner 50 according to a first embodiment of the present invention.

  The air conditioner 50 includes an outdoor unit 51, a plurality of (in the first embodiment, two) indoor units 52, a gas connection pipe 53 and a liquid connection pipe 54 that connect the outdoor unit 51 and the indoor unit 52. It is composed of The gas connection pipe 53 is provided so as to communicate between the gas blocking valve 11 of the outdoor unit 51 and the indoor heat exchanger 7 of the indoor unit 52. The liquid connection pipe 54 is provided so as to communicate between the liquid blocking valve 12 of the outdoor unit 51 and the indoor expansion valve 8 of the indoor unit 52. The indoor units 52 are connected in parallel via a gas connection pipe 53 and a liquid connection pipe 54.

  The gas blocking valve 11 and the liquid blocking valve 12 are for sealing the refrigerant charged in the refrigeration cycle of the outdoor unit 51 before the air conditioner 50 is installed. After the connection pipe 53 and the liquid connection pipe 54 are connected, they are always open.

  The outdoor unit 51 includes a compressor 1, a switching valve 2, an outdoor heat exchanger 3, an outdoor expansion valve 4, a bypass circuit 17 (including a bypass pressure reducing mechanism 5 and a bypass electromagnetic valve 6), an outdoor fan (not shown), and an outdoor heat exchanger. A temperature detector 13, an outside air temperature detector 14, an outdoor control device 16a and the like are provided.

  The compressor 1 is composed of a variable capacity compressor that is controlled by changing its operating frequency with an inverter. The switching valve 2 is a valve that switches the flow direction of the refrigerant discharged from the compressor 1 and the flow direction of the refrigerant sucked into the compressor 1, and is configured by a switching valve in the first embodiment. The switching valve 2 is controlled by the control device 16 so as to form a flow path indicated by a solid line during heating operation and to form a flow path indicated by a dotted line during cooling operation.

  The outdoor heat exchanger 3 is composed of a plate fin type heat exchanger composed of a large number of plate-like fins juxtaposed at narrow intervals and a meandering refrigerant pipe passing through these fins. Heat is exchanged between the refrigerant flowing through the refrigerant pipe and the outside air (outdoor air) ventilated by the outdoor fan.

  The outdoor expansion valve 4 is an electronic expansion valve for reducing the pressure of the refrigerant flowing through the main circuit of the refrigeration cycle, and is installed between the outdoor heat exchanger 3 and the liquid blocking valve 12 (liquid connection pipe 54). Yes.

  The bypass circuit 17 bypasses the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 during the heating operation and supplies the refrigerant to the outdoor heat exchanger 3. The bypass circuit 17 exchanges outdoor heat with the discharge-side refrigerant pipe of the compressor 1. The heater 3 is connected to the inlet side refrigerant pipe during heating operation. The bypass circuit 17 includes a bypass pressure reducing device 18 including a bypass pressure reducing mechanism 5 and a bypass electromagnetic valve 6. The bypass solenoid valve 6 is for opening and closing the bypass circuit 17, and the bypass solenoid valve 6 is for decompressing the refrigerant flowing through the bypass circuit 17.

  The outdoor heat exchanger temperature detector 13 is for detecting the temperature of the outdoor heat exchanger 3 that is one of the outdoor temperatures. In the first embodiment, the inlet of the outdoor heat exchanger 3 during the heating operation is used. It is installed on the side part. The outdoor temperature detector 14 is for detecting an outdoor temperature that is one of outdoor temperatures. In the first embodiment, the outdoor heat detector 14 detects the temperature of the outdoor air sucked into the outdoor heat exchanger 3. It is installed on the outside air suction side of the exchanger 3.

  The outdoor control device 16a is mounted on the outdoor control board together with an outdoor operation switch (not shown) and the like, and constitutes the control device 16 together with the indoor control device 16b. The outdoor operation switch constitutes an operation switch together with an indoor operation switch (not shown). The outdoor control board constitutes a control board together with the indoor control board.

  The control device 16 uses the air conditioner 50 based on signals detected by sensors such as the outdoor heat exchanger temperature detector 13, the outdoor air temperature detector 14, and the indoor temperature detector 15, signals set by operation switches, and the like. It controls the equipment that constitutes.

  Each indoor unit 52 includes an indoor heat exchanger 7, an indoor expansion valve 8, an indoor fan, an indoor temperature detector 15, and the like. The indoor heat exchanger 7 and the indoor expansion valve 8 are connected in series between the gas connection pipe 53 and the liquid connection pipe 54.

  The indoor heat exchanger 7 is composed of a plate fin type heat exchanger composed of a large number of plate-like fins juxtaposed at narrow intervals and a meandering refrigerant pipe passing through them. Heat is exchanged between the refrigerant flowing through the refrigerant pipe and the indoor air ventilated by the indoor fan.

  The indoor expansion valve 8 is an electronic expansion valve for reducing the pressure of the refrigerant flowing through the main circuit of the refrigeration cycle, and is installed between the indoor heat exchanger 7 and the liquid connection pipe 54.

  The indoor temperature detector 15 is for detecting the indoor temperature. In the first embodiment, the indoor air intake of the indoor heat exchanger 7 is detected so as to detect the temperature of the indoor air sucked into the indoor heat exchanger 7. It is installed on the side.

  The indoor control device 16b is mounted on the indoor control board together with the indoor operation switch and the like.

  Next, the basic operation of the refrigeration cycle of the air conditioner 50 will be described with reference to FIG.

  The heating operation will be described. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 passes through the switching valve 2, passes through the gas blocking valve 11 and the gas connection pipe 53, as indicated by the solid line arrow, and passes through the indoor heat exchanger of each indoor unit 52. 7 is condensed in the indoor heat exchanger 7 to become a liquid refrigerant. This liquid refrigerant reaches the outdoor expansion valve 4 through the fully opened indoor expansion valve 8, the liquid connection pipe 54 and the liquid blocking valve 12, and is decompressed by the outdoor expansion valve 4 to become a low-temperature low-pressure gas-liquid mixed refrigerant. The decompressed refrigerant is evaporated by the outdoor heat exchanger 3, becomes a gas refrigerant, passes through the switching valve 2, and is returned to the compressor 1.

  During the heating operation, by opening the bypass electromagnetic valve 6, the gas refrigerant discharged from the compressor 1 branches from the flow through the switching valve 2 described above and is depressurized by the bypass depressurization mechanism 5. After passing through the bypass electromagnetic valve 6, the refrigerant is combined with the refrigerant flowing into the outdoor heat exchanger 3 through the outdoor expansion valve 4 and flows into the outdoor heat exchanger 3. Thereby, the temperature of the outdoor heat exchanger 3 can be raised compared with the case where the refrigerant is not bypassed. Since the flow rate is constant by the bypass pressure reducing mechanism 5, the circulation amount to the outdoor heat exchanger 3 is proportional to the discharge circulation amount of the compressor 1 in the first embodiment.

  The cooling operation will be described. The gas refrigerant discharged from the compressor 1 reaches the outdoor heat exchanger 3 via the switching valve 2 and is condensed by the outdoor heat exchanger 3 to become a liquid refrigerant as indicated by the dotted arrow. This liquid refrigerant reaches the indoor expansion valve 8 through the fully open outdoor expansion valve 4, the liquid blocking valve 12 and the liquid connection pipe 54, and is decompressed by the indoor expansion valve 8 to become a low-pressure gas-liquid mixed refrigerant. The decompressed refrigerant is evaporated in the indoor heat exchanger 7, becomes a gas refrigerant, returns to the compressor 1 through the gas connection pipe 53, the gas blocking valve 11, and the switching valve 2. During the cooling operation, the bypass solenoid valve 6 is always closed and the bypass circuit 17 is not used.

  Next, a specific control method in the heating operation will be described with reference to FIGS. 2, 3, and 4. FIG. 2 is a flowchart showing a control method of the air conditioner 50 of FIG. 3 is a conventional control timing chart, and FIG. 4 is a control timing chart of the air conditioner 50 of FIG. This control is performed by the control device 16.

  When the heating operation is started, the outdoor heat exchanger temperature detector 13 detects the outdoor heat exchanger temperature while the bypass solenoid valve 6 is closed, and the outdoor air temperature detector 14 detects the outdoor air temperature (step). S1). Next, based on the detected outdoor heat exchanger temperature and outside air temperature, it is determined whether or not the outdoor heat exchanger 3 may be frosted (step S2).

  If it is determined in step S2 that there is a risk of frost formation, the bypass solenoid valve 6 is opened (step S3). By opening the bypass electromagnetic valve 6, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 is diverted to the bypass circuit 17, decompressed by the bypass decompression mechanism 5, and circulated to the outdoor heat exchanger 3.

  According to these controls, the temperature of the outdoor expansion valve 4 can be increased as compared with the case where high-temperature and high-pressure gas refrigerant is not divided through the bypass circuit 17, so that the outdoor heat exchanger 3 can be prevented from frosting. Thus, the heating operation that does not require the defrosting operation is possible, and the comfort of the indoor space can be ensured.

  As described above, when the bypass solenoid valve 6 is opened and the refrigerant is diverted through the bypass circuit 17, the refrigerant circulation amount to the indoor unit 52 is reduced, the heating capacity is lowered, and the comfort of the indoor space may be impaired. Therefore, the rotational speed of the compressor 1 is increased to increase the total refrigerant circulation amount (step S4). As a result, a decrease in the amount of refrigerant circulating to the indoor unit 52 can be compensated, and the comfort of the indoor space can be more reliably ensured.

  And assuming the case where the reduction | decrease of the refrigerant | coolant circulation amount to the indoor unit 52 cannot fully be compensated, following step S4, the refrigerant | coolant circulation amount to the indoor heat exchanger 7 is before opening the bypass solenoid valve 6. It is determined whether or not the circulation amount to the indoor heat exchanger 7 is the same (step S5). In this determination, when the refrigerant circulation amount becomes the same, the process returns to step S1 and the heating operation with the bypass electromagnetic valve 6 opened is continued.

  If it is determined in step S5 that the refrigerant circulation amount to the indoor heat exchanger 7 is not the same, the indoor temperature is detected by the indoor temperature detector 15, and the detected indoor temperature and the operation switch are set. The difference between the set indoor temperature and the indoor expansion valve 8 of each indoor unit 52 is calculated based on the difference (step S6).

  Based on the calculation result, the throttle opening degree of the indoor expansion valve 8 is adjusted in the closing direction to reduce the refrigerant circulation amount flowing through the indoor unit 52, and the sum of the reduction amounts is the same as the refrigerant circulation amount flowing through the bypass circuit. (Step S7), the process returns to Step S1 to continue the process.

  By these, the temperature rise of the outdoor heat exchanger 3 by the refrigerant from the bypass circuit 17 and the securing of the heating capacity of the indoor heat exchanger 7 of each indoor unit 52 can be harmonized.

  If it is determined in step S2 that there is no possibility of frost formation, and if frost prevention control is not being performed in step S8, the process returns to step S1 and the heating operation with the bypass solenoid valve 6 closed is continued.

  If it is determined in step S2 that there is no possibility of frost formation and if it is determined in step S8 that frost prevention control is being performed, the rotational speed of the compressor is reduced to the rotational speed before the bypass circuit is opened. After that, the bypass circuit is shut off, and the process returns to step 1 to continue the processing.

  With these controls, as shown in FIGS. 3 and 4, when the bypass circuit is shut off after the compressor speed is lowered to the speed before the bypass circuit is opened, the discharge pressure of the compressor is prevented from increasing. An increase in compressor operating current can be suppressed, abnormal stop due to pressure protection control or current protection control can be prevented, and comfort in the indoor space can be ensured by continuing heating operation.

  In other words, when there is no risk of frost formation, the compressor rotation speed is decreased, and when the predetermined value is reached, the bypass solenoid valve 6 is closed and the bypass circuit is shut off, so that the continuous heating operation is performed even after the frost prevention operation is completed. It can be performed.

  As described above, according to the first embodiment, it is possible to achieve a heating operation in which the defrosting operation is unnecessary while ensuring the minimum comfort while reducing the heating capacity.

  That is, the first embodiment is configured by branching from a gas connection pipe 53 and a liquid connection pipe 54 from one outdoor unit 51 and connecting a plurality of indoor units 52 in parallel. 1 is provided with a pressure reducing device 18 in a bypass circuit 17 connected between the outdoor heat exchanger 3 and the outdoor expansion valve 4 from the discharge side, and the temperature of each element from the temperature sensors 13 and 14 of the outdoor unit 51 during heating operation. The control device 16 takes in and opens and closes the decompression device 18 based on these temperatures. Then, when the temperature of the outdoor heat exchanger 3 of the outdoor unit 51 decreases and the outdoor heat exchanger 3 may be frosted, the decompression device 18 is opened and the high-temperature and high-pressure refrigerant from the compressor 1 is decompressed. By reducing the pressure in the apparatus 18 and allowing it to flow through the outdoor heat exchanger 3, a decrease in the temperature of the outdoor heat exchanger 3 is prevented.

  When the decompression device 18 is opened here, the circulation amount to the indoor unit 52 is lowered, and there is a possibility that the heating capacity is lowered and the comfort of the indoor space is impaired. Therefore, in the combination of the indoor unit 52 and the outdoor unit 51, the rotational speed of the compressor 1 is increased by driving the inverter and the discharge circulation amount per time is increased so as to compensate for the decrease in the circulation amount to the indoor unit 52. I have to.

  If this cannot be sufficiently compensated, the indoor expansion valve 8 provided in the indoor unit 52 is determined from the difference between the indoor set temperature set in each indoor unit 52 and the actual indoor temperature detected by the indoor temperature detector 15. Calculate the minimum necessary amount of the aperture for ensuring comfort and adjust it in the closing direction. Accordingly, the necessary refrigerant circulation amount to the indoor unit 52 can be adjusted, and the amount of bypass circulation that cannot be compensated by adjusting the rotation speed of the compressor 1 can be compensated.

  In order to prevent frost formation of the outdoor heat exchanger 3 in the heating operation, when the refrigerant is circulated to the outdoor heat exchanger 3 from between the discharge side of the compressor 1 and the switching valve 2, Although the refrigerant circulation rate is reduced and the heating capacity is reduced, it is possible to carry out continuous heating operation while maintaining the comfort of the indoor space by controlling the indoor set temperature and the indoor temperature. is there.

  Further, when it is determined that there is no possibility of frost formation during the frost prevention control, the rotation speed of the compressor 1 is lowered to the rotation speed before the bypass circuit 17 is opened, and then the bypass circuit 17 is shut off. By preventing the compressor 1 from increasing discharge pressure and suppressing the increase in compressor operating current, it is possible to prevent abnormal stoppage due to pressure protection control or current protection control, and comfort in the indoor space by continuing heating operation. Can be secured.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Switching valve 3 Outdoor heat exchanger 4 Outdoor expansion valve 5 Bypass pressure reduction mechanism 6 Bypass solenoid valve 7 Indoor heat exchanger 8 Indoor expansion valve 11 Gas check valve,
12 liquid blocking valve 13 outdoor heat exchanger temperature detector 14 outdoor air temperature detector 15 indoor temperature detector 16 control device 16a outdoor control device 16b indoor control device 17 bypass circuit 18 bypass decompression device 50 air conditioner 51 outdoor unit 52 indoor unit 53 Gas connection piping 54 Liquid connection piping

Claims (9)

A bypass circuit connecting the discharge side of the compressor and the inlet side of the outdoor heat exchanger during heating operation;
A bypass solenoid valve for communicating / blocking the bypass circuit;
A control device for controlling the number of revolutions of the compressor and controlling the bypass solenoid valve;
With
In the control device,
When determining whether or not there is a risk of frost formation on the outdoor heat exchanger during heating operation, when a state where there is no risk of frost formation from a state where there is a risk of frost formation,
Decreasing the rotation speed of the compressor,
An air conditioner characterized in that the bypass circuit is shut off after the rotational speed reaches a predetermined value. In claim 1,
The air conditioner, the outdoor heat exchanger includes an outdoor heat exchanger temperature detector,
The air conditioner characterized in that the control device determines whether or not the outdoor heat exchanger may be frosted at a temperature detected by the outdoor heat exchanger temperature detector. Machine. In claim 1,
In the air conditioner, the outdoor heat exchanger includes an outdoor temperature detector,
The air conditioner characterized in that the controller controls whether or not the outdoor heat exchanger has a possibility of frost formation based on a temperature detected by the outside air temperature detector. In claim 1,
An air conditioner comprising an operation switch for setting a determination condition of the control device. An outdoor unit having a compressor, a switching valve, an outdoor expansion valve, an outdoor heat exchanger, an outdoor temperature detector for detecting an outdoor air temperature, or an outdoor heat exchanger temperature detector for detecting the temperature of the outdoor heat exchanger, and an indoor heat An indoor unit having an exchanger and an indoor expansion valve, and a control device,
The compressor, the switching valve, the indoor heat exchanger, the indoor expansion valve, the outdoor expansion valve, the outdoor heat exchanger, the switching valve, and the compressor are connected in order to form a refrigeration cycle and perform heating operation In an air conditioner capable of
The refrigeration cycle has a bypass circuit that connects a discharge side of the compressor and an inlet side during heating operation of the outdoor heat exchanger,
The bypass circuit includes a bypass solenoid valve and a bypass pressure reducing mechanism,
In the control device, during heating operation, it is determined whether or not there is a risk of frost formation on the outdoor heat exchanger, and when there is a risk of frost formation, the bypass electromagnetic valve is opened, and the compressor In addition to frost prevention control for supplying refrigerant from the discharge side to the outdoor heat exchanger through the bypass pressure reducing device, control is performed to increase the rotation speed of the compressor, and there is no risk of frost formation during frost prevention control. If it is determined, the air conditioner is controlled to cut off the bypass circuit after the rotation speed of the compressor is lowered. In claim 5,
When it is determined by the control device that there is no possibility of frost formation during frost prevention control, the rotation speed of the compressor is shifted to the rotation speed before the bypass circuit is opened, and then the bypass circuit is shut off. An air conditioner characterized by performing control. In claim 5,
The control device determines whether or not the outdoor heat exchanger is likely to be frosted by controlling the temperature detected by the outdoor air temperature detector or the outdoor heat exchanger temperature detector. Air conditioner characterized by. In claim 5,
In the control device, when there is a risk of frost formation, the bypass solenoid valve is opened, and refrigerant is diverted from the discharge side of the compressor through the bypass pressure reducing mechanism and supplied to the outdoor heat exchanger. An air conditioner that performs control to increase the rotational speed of the compressor, and performs control to shut off the bypass circuit after decreasing the rotational speed of the compressor after a predetermined time has elapsed. In claim 5,
An air conditioner comprising an operation switch for setting a determination condition of the control device.

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