JP7512639B2 - Air Conditioning Equipment - Google Patents

Description

The present invention relates to an air conditioner having an outdoor unit equipped with a compressor and an outdoor heat exchanger, and multiple indoor units equipped with indoor heat exchangers.

In a multi-room air conditioner having an outdoor unit with a compressor and an outdoor heat exchanger, and multiple indoor units with indoor heat exchangers and indoor fans, if the air temperature in the room where the indoor units are installed becomes close to the set temperature (for example, the set temperature ±1°C) during air conditioning operation, the indoor unit expansion valve is fully closed (during cooling operation) or slightly opened (during heating operation) to prevent refrigerant from flowing into the indoor heat exchanger, and the indoor fan is stopped to stop blowing air from the indoor unit, entering a so-called thermo-off state. If the air temperature in the room drops or rises and moves away from the set temperature, the expansion valve is opened to an opening degree corresponding to the required air conditioning capacity, the indoor fan is started, and the so-called thermo-on state is entered, in which blowing air into the room is resumed. When the thermo-off state is in effect, the indoor fan is stopped, but the indoor fan is periodically driven (for example, once every five minutes) to take in indoor air into the indoor unit, and a monitoring operation is performed to detect the temperature of the taken-in indoor air using an indoor temperature sensor installed in the indoor unit to determine whether to switch to the thermo-on state.

In the multi-room air conditioning system described above, as long as there is at least one indoor unit in the thermo-on state, the compressor must be operated in order to supply refrigerant to that indoor unit, but if all indoor units are in the thermo-off state, there is no need to supply refrigerant and the compressor can be stopped.

As a result of the above, during heating operation, a small amount of refrigerant continues to flow through the indoor unit in the thermo-off state, heating the indoor heat exchanger, and the air inside the indoor unit is also heated by the indoor heat exchanger. For this reason, when detecting the indoor air temperature by monitoring operation during the thermo-off state of heating operation, it is necessary to drive the indoor fan to exhaust the air inside the indoor unit that is heated by the indoor heat exchanger from inside the indoor unit. For this reason, in the case of a monitoring operation to detect the indoor air temperature while the thermo-off state is in effect, for example, as in the multi-room air conditioner described in Patent Document 1, the indoor fan is driven for a predetermined time (e.g., one minute) to exhaust the air inside the indoor unit that is heated by the indoor heat exchanger, and then the temperature of the indoor air taken into the indoor unit is detected. At this time, air that has been warmed by the indoor heat exchanger is blown out into the room.

JP 2003-287258 A

When a multi-room air conditioner performs heating operation during intermediate seasons such as spring and autumn, indoor units installed in spaces with low air conditioning loads (for example, spaces facing south-facing windows) may be in the thermo-off state for almost the entire day. For this reason, in an indoor unit that is in the thermo-off state all day during heating operation, if a monitoring operation is performed to periodically drive the indoor fan to detect the indoor air temperature, as in the multi-room air conditioner shown in the above-mentioned Patent Document 1, there is a problem that the room that is being air-conditioned by the indoor unit may become too warm, causing discomfort to the user, because the air blown out from the indoor unit is heated by the indoor heat exchanger.

In view of the above problems, the present invention provides an air conditioner that includes multiple indoor units, each of which has an indoor heat exchanger, an indoor fan, an indoor temperature sensor, and an indoor unit control device that controls the operation of the indoor fan, and an outdoor unit that has the same number of expansion valves as the indoor units, a compressor, and an outdoor heat exchanger, and performs cooling or heating air conditioning operation in the room in which the indoor units are installed, and that can prevent air blown out from the indoor units from causing discomfort to users by monitoring the indoor units when the thermostat is off during heating operation.

One aspect of the present invention includes a plurality of indoor units each including an indoor heat exchanger, an indoor unit fan, an indoor temperature sensor, and an indoor unit control device that controls the operation of the indoor unit fan, and an outdoor unit including the same number of indoor unit expansion valves as the indoor units, a compressor, and an outdoor heat exchanger , and the indoor unit control device switches the indoor unit to thermo-off operation when the indoor air temperature detected by the indoor temperature sensor of the indoor unit during heating operation becomes higher than a temperature obtained by adding a first predetermined temperature to a set temperature, and after a predetermined interval has elapsed from the start of the thermo-off operation, drives the indoor unit fan for a predetermined time to detect the indoor air temperature with the indoor temperature sensor, and continues the thermo-off operation. This air conditioning apparatus is characterized in that it performs a monitoring operation to determine whether the temperature of the indoor air is higher than the set temperature minus a second predetermined temperature, and if, during the monitoring operation, the detected indoor air temperature is higher than the set temperature minus a second predetermined temperature, it continues the thermo-off operation, and if the detected indoor air temperature is lower than the set temperature minus a second predetermined temperature, it terminates the thermo-off operation and switches the indoor unit to thermo-on operation, and the indoor unit control device counts the number of times the thermo-off operation has been continued due to the monitoring operation, and changes the specified interval according to the number of times the thermo-off operation has been counted before starting the next monitoring operation.

According to the present invention, it is possible to prevent the room from becoming too warm when the indoor unit is in thermo-off operation during heating operation, thereby reducing discomfort to the user.

FIG. 2 is a refrigeration circuit diagram of the indoor air conditioning device. FIG. 2 is a control block diagram of the indoor conditioning device. FIG. 11 is a control flow diagram of the monitoring operation of the indoor conditioning device.

The following describes in detail an embodiment of the present invention with reference to the attached drawings. As an example of the embodiment, an air conditioner in which 10 indoor units are connected in parallel to an outdoor unit and all indoor units can simultaneously perform cooling or heating operation will be described. Note that the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention.

As shown in FIG. 1, the air conditioner 1 in this embodiment includes one outdoor unit 2 and ten indoor units 5-1 to 5-10 (only two of these, indoor units 5-1 and 5-10, are shown in FIG. 1) connected in parallel to the outdoor unit 2 by liquid pipes 8 and gas pipes 9. More specifically, the shutoff valve 25 of the outdoor unit 2 is connected to the liquid pipe connection 53 of each indoor unit 5 by the liquid pipe 8. Also, the shutoff valve 26 of the outdoor unit 2 is connected to the gas pipe connection 54 of each indoor unit 5 by the gas pipe 9. In this way, the outdoor unit 2 and the ten indoor units 5 are connected by the liquid pipes 8 and gas pipes 9 to form the refrigerant circuit 10 of the air conditioner 1.

<Outdoor unit configuration>
First, the outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 20, a four-way valve 22 which is a flow path switching valve, an outdoor heat exchanger 23, an outdoor unit expansion valve 24, a stop valve 25 to which a liquid pipe 8 is connected, a stop valve 26 to which a gas pipe 9 is connected, an accumulator 27, and an outdoor unit fan 28. The air conditioning device 1 also includes an outdoor unit control device 100 which controls the compressor 20, the outdoor unit expansion valve 24, and the outdoor unit fan 28, which will be described later. Each of these devices, except for the outdoor unit fan 28, is connected to each other by each refrigerant pipe, which will be described in detail below, to form an outdoor unit refrigerant circuit 20 which is part of the refrigerant circuit 10.

The compressor 20 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The refrigerant discharge side of the compressor 20 is connected by a discharge pipe 40. The refrigerant suction side of the compressor 20 is also connected to the refrigerant outflow side of the accumulator 27 by a suction pipe 42.

The four-way valve 22 is a valve for switching the direction of refrigerant flow in the refrigerant circuit 10, and has four ports a, b, c, and d. Port a is connected by a discharge pipe 40. Port b is connected to one of the refrigerant inlets and outlets of the outdoor heat exchanger 23 by a refrigerant pipe 43. Port c is connected to the refrigerant inlet side of the accumulator 27 by a refrigerant pipe 46. And port d is connected to the stop valve 26 by an outdoor unit gas pipe 45.

The outdoor heat exchanger 23 exchanges heat between the refrigerant and the outside air taken into the outdoor unit 2 by the rotation of the outdoor unit fan 28 described below. As described above, one refrigerant inlet/outlet of the outdoor heat exchanger 23 is connected to port b of the four-way valve 22 by a refrigerant piping 43. The other refrigerant inlet/outlet of the outdoor heat exchanger 23 is connected to the shutoff valve 25 by an outdoor unit liquid pipe 44. The outdoor heat exchanger 23 functions as a condenser when the air conditioning device 1 is performing cooling operation, and functions as an evaporator when the air conditioning device 1 is performing heating operation.

The outdoor unit expansion valve 24 is provided in the outdoor unit liquid pipe 44. The outdoor unit expansion valve 24 is an electronic expansion valve driven by a pulse motor (not shown), and the amount of refrigerant flowing into the outdoor heat exchanger 23 or the amount of refrigerant flowing out from the outdoor heat exchanger 23 is adjusted by adjusting the opening degree according to the number of pulses given to the pulse motor. When the air conditioner 1 is performing heating operation, the opening degree of the outdoor unit expansion valve 24 is adjusted so that the discharge temperature, which is the temperature of the refrigerant discharged from the compressor 21, becomes a target temperature determined based on the heating capacity required by each of the indoor units 5-1 to 5-1. When the air conditioner 1 is performing cooling operation, the opening degree of the outdoor unit expansion valve 24 is fully open.

As described above, the refrigerant inlet side of the accumulator 27 is connected to port c of the four-way valve 22 via the refrigerant piping 46, and the refrigerant outlet side is connected to the refrigerant suction side of the compressor 20 via the suction pipe 42. The accumulator 27 separates the refrigerant that flows into the inside of the accumulator 28 from the refrigerant piping 46 into gas refrigerant and liquid refrigerant, and allows only the gas refrigerant to be sucked into the compressor 20.

The outdoor unit fan 28 is made of a resin material and is disposed near the outdoor heat exchanger 23. The outdoor unit fan 28 is rotated by a fan motor (not shown) to take in outside air from an intake port (not shown) into the outdoor unit 2, and releases the outside air that has exchanged heat with the refrigerant in the outdoor heat exchanger 23 to the outside of the outdoor unit 2 from an outlet port (not shown).

In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1, the discharge pipe 40 is provided with a discharge pressure sensor 31 that detects the discharge pressure, which is the pressure of the refrigerant discharged from the compressor 20, and a discharge temperature sensor 33 that detects the temperature of the refrigerant discharged from the compressor 20. Near the refrigerant inlet of the accumulator 28 in the refrigerant piping 46, a suction pressure sensor 32 that detects the suction pressure, which is the pressure of the refrigerant sucked into the compressor 20, and a suction temperature sensor 34 that detects the temperature of the refrigerant sucked into the compressor 20 are provided.

A heat exchanger temperature sensor 35 is provided between the outdoor heat exchanger 23 and the outdoor unit expansion valve 24 in the outdoor unit liquid pipe 44 to detect the temperature of the refrigerant flowing into the outdoor heat exchanger 23 or the temperature of the refrigerant flowing out of the outdoor heat exchanger 23. An outdoor air temperature sensor 36 is provided near an intake port (not shown) of the outdoor unit 2 to detect the temperature of the outdoor air flowing into the outdoor unit 2, i.e., the outdoor air temperature.

The outdoor unit control device 100 is connected to the compressor 20, four-way valve 22, outdoor unit expansion valve 24, shut-off valve 25, shut-off valve 26, outdoor unit fan 28, discharge pressure sensor 31, discharge temperature sensor 33, suction pressure sensor 32, suction temperature sensor 34, and outdoor air temperature sensor 36, and is also connected to the indoor unit control device 200, which will be described later. The outdoor unit control device 100 controls the compressor 20, four-way valve 22, outdoor unit expansion valve 24, shut-off valve 25, and outdoor unit fan 28 based on signals from various sensors and the indoor unit control device 200.

<Configuration of each indoor unit>
Next, the ten indoor units 5-1 to 5-10 will be described. All ten indoor units 5-1 to 5-10 have the same configuration, and are equipped with an indoor heat exchanger 51, an indoor unit expansion valve 52, a liquid pipe connection section 53, a gas pipe connection section 54, and an indoor unit fan 55. They also have an indoor unit control device 200 that controls the drive of the indoor unit fan 55 and the opening degree of the indoor unit expansion valve 52. These component devices, except for the indoor unit fan 55, are connected to each other by refrigerant pipes described in detail below to constitute an indoor unit refrigerant circuit 50 that forms part of the refrigerant circuit 10.

The indoor heat exchanger 51 exchanges heat between the refrigerant and indoor air taken into the indoor unit 5 from an intake port (not shown) by the rotation of the indoor unit fan 55 (described later). One refrigerant inlet and outlet of the indoor heat exchanger 51 is connected to the liquid pipe connection part 53 by the indoor unit liquid pipe 71, and the other refrigerant inlet and outlet and gas pipe connection part 54a are connected by the indoor unit gas pipe 72. The indoor heat exchanger 51 functions as an evaporator when the air conditioner 1 is performing cooling operation, and functions as a condenser when the air conditioner 1 is performing heating operation. The liquid pipe connection part 53 and the gas pipe connection part 54 are connected to each refrigerant pipe by welding, flare nuts, etc.

The indoor unit expansion valve 52 is provided in the indoor unit liquid pipe 71. The indoor unit expansion valve 52 is an electronic expansion valve, and when the indoor heat exchanger 51 functions as an evaporator, that is, when the indoor unit 5 performs cooling operation, its opening is adjusted so that the refrigerant superheat degree at the refrigerant outlet (gas pipe connection part 54 side) of the indoor heat exchanger 51 becomes the target refrigerant superheat degree. Also, when the indoor heat exchanger 51 functions as a condenser, that is, when the indoor unit 5 performs heating operation, the indoor unit expansion valve 52 is adjusted so that the refrigerant supercooling degree at the refrigerant outlet (liquid pipe connection part 53 side) of the indoor heat exchanger 51 becomes the target refrigerant supercooling degree. Here, the target refrigerant superheat degree and the target refrigerant supercooling degree are the refrigerant superheat degree and the refrigerant supercooling degree required for each of the indoor units 5-1 to 5-10 to exhibit sufficient cooling capacity or heating capacity.

The indoor unit fan 55 is made of a resin material and is located near the indoor heat exchanger 51. The indoor unit fan 55 is rotated by a fan motor (not shown) to take in indoor air from an intake port (not shown) into the indoor unit 5, and releases the indoor air that has exchanged heat with the refrigerant in the indoor heat exchanger 51 into the room from an outlet port (not shown).

In addition to the configuration described above, the indoor unit 5 is provided with various sensors. A liquid-side temperature sensor 61 is provided in the indoor unit liquid pipe 71 between the indoor heat exchanger 51 and the indoor unit expansion valve 52 to detect the temperature of the refrigerant flowing into or out of the indoor heat exchanger 51. A gas-side temperature sensor 62 is provided in the indoor unit gas pipe 72 to detect the temperature of the refrigerant flowing out or into the indoor heat exchanger 51. An indoor temperature sensor 63 is provided near the suction port (not shown) of the indoor unit 5 to detect the temperature of the indoor air flowing into the indoor unit 5.

The indoor unit control device 200 is connected to the indoor unit expansion valve 52, the indoor unit fan 55, the liquid side temperature sensor 61, the gas side temperature sensor 62, the indoor temperature sensor 63, and the counter 76, and is also connected to the outdoor unit control device 100. The indoor unit control device 200 controls the drive of the indoor unit fan 55 and adjusts the opening of the indoor unit expansion valve 52 based on signals from the outdoor unit control device 100 and signals from the liquid side temperature sensor 61, the gas side temperature sensor 62, and the indoor temperature sensor 63. Furthermore, the indoor unit control device 200 controls the drive of the indoor unit fan 55 in the monitoring operation performed during thermo-off operation, which will be described later. The counter 76 also counts the number of thermo-off operations when thermo-off operation is continued.

<Operation of the refrigerant circuit>
Next, the flow of refrigerant in the refrigerant circuit 10 and the operation of each part during air conditioning operation of the air conditioner 1 in this embodiment will be described with reference to Fig. 1. Note that in the following description, first, a case where the air conditioner 1 performs heating operation will be described, and then a case where the air conditioner 1 performs cooling operation will be described. Note that the solid arrows in Fig. 1 indicate the flow of refrigerant during heating operation. Also, the dashed arrows in Fig. 1 indicate the flow of refrigerant during cooling operation.

<Heating operation>
1, when the air conditioner 1 performs heating operation, the four-way valve 22 is switched to the state shown by the solid lines, that is, so that ports a and d of the four-way valve 22 communicate with each other, and so that ports b and c of the four-way valve 22 communicate with each other. As a result, the refrigerant circuit 10 becomes a heating cycle in which the indoor heat exchangers 51 function as condensers and the outdoor heat exchanger 23 functions as an evaporator.

When the compressor 20 is driven while the refrigerant circuit 10 functions as a heating cycle, the refrigerant discharged from the compressor 20 flows through the discharge pipe 40 and into the four-way valve 22. The refrigerant that flows out of the four-way valve 22 then flows through the outdoor unit gas pipe 45 and into the gas pipe 9 via the shutoff valve 26.

The refrigerant flowing through the gas pipe 9 is diverted to the indoor units 5-1 to 5-10 via each gas pipe connection 54. The refrigerant that flows into the indoor units 5-1 to 5-10 flows through each indoor unit gas pipe 72 and flows into each indoor heat exchanger 51. The refrigerant that flows into each indoor heat exchanger 51 exchanges heat with the indoor air drawn into each indoor unit 5 by the rotation of each indoor unit fan 55, and condenses.

In this way, each indoor heat exchanger 51 functions as a condenser, and the indoor air heated by heat exchange with the refrigerant in each indoor heat exchanger 51 is blown out into the room from an air outlet (not shown), thereby heating the room in which the indoor units 5-1 to 5-10 are installed.

The refrigerant that flows from each indoor heat exchanger 51 into each indoor unit liquid pipe 71 is decompressed as it passes through each indoor unit expansion valve 52, the opening of which is adjusted so that the refrigerant subcooling degree at the refrigerant outlet side of each indoor heat exchanger 51 becomes the target refrigerant subcooling degree. Here, the target refrigerant subcooling degree is determined based on the heating capacity required for each indoor unit 5-1 to 5-10. In addition, the heating capacity is determined based on the temperature difference between the set temperature and the detected indoor temperature in each indoor unit 5-1 to 5-10.

The refrigerant depressurized by each indoor unit expansion valve 52 flows out from each indoor unit liquid pipe 71 through each liquid pipe connection 53 into the liquid pipe 8. The refrigerant that joins in the liquid pipe 8 and flows into the outdoor unit 2 through the closing valve 25 flows through the outdoor unit liquid pipe 44 and is further depressurized as it passes through the outdoor unit expansion valve 24, the opening of which is adjusted so that the discharge temperature of the compressor 20 becomes the target temperature.

The refrigerant decompressed by the outdoor unit expansion valve 24 flows through the outdoor unit liquid pipe 44 and into the outdoor heat exchanger 23, where it evaporates through heat exchange with the outside air drawn into the outdoor unit 5 by the outdoor unit fan 28 rotating at its maximum speed. The refrigerant that flows from the outdoor heat exchanger 23 into the refrigerant pipe 43 flows through the four-way valve 22, the refrigerant pipe 46, the accumulator 27, and the suction pipe 42, in that order, before being sucked into the compressor 20 and compressed again.

<Cooling operation>
1, when the air conditioner 1 performs cooling operation, the four-way valve 22 is switched to the state shown by the dashed lines, that is, so that ports a and b of the four-way valve 22 communicate with each other, and so that ports c and d of the four-way valve 22 communicate with each other. As a result, the refrigerant circuit 10 becomes a heating cycle in which the indoor heat exchangers 51 function as evaporators and the outdoor heat exchanger 23 functions as a condenser.

When the compressor 20 is driven while the refrigerant circuit 10 functions as a cooling cycle, the refrigerant discharged from the compressor 20 flows through the discharge pipe 40 and into the four-way valve 22. The refrigerant flowing out of the four-way valve 22 flows through the refrigerant piping 43 and into the outdoor heat exchanger 23. The refrigerant that has flowed into the outdoor heat exchanger 23 exchanges heat with the outside air that has been drawn into the outdoor unit 2 by the rotation of the outdoor unit fan 28, and condenses. The refrigerant that has flowed out from the outdoor heat exchanger 23 into the outdoor unit liquid pipe 44 passes through the outdoor unit expansion valve 24, which is fully open, and flows out into the liquid pipe 8 via the closing valve 25.

The refrigerant flowing through the liquid pipe 8 flows into the indoor units 5-1 to 5-10 through each liquid pipe connection 53. The refrigerant that flows into the indoor units 5-1 to 5-10 flows through each indoor unit liquid pipe 71 and is reduced in pressure when passing through each indoor unit expansion valve 52, the opening of which is adjusted so that the refrigerant superheat degree at the refrigerant outlet of each indoor heat exchanger 51 becomes the target refrigerant superheat degree. Here, the target refrigerant superheat degree is determined based on the cooling capacity required for each indoor unit 5-1 to 5-10. The cooling capacity is also determined based on the temperature difference between the set temperature and the detected indoor temperature in each indoor unit 5-1 to 5-10.

The refrigerant that flows from each indoor unit liquid pipe 71 into each indoor heat exchanger 51 evaporates by exchanging heat with the indoor air drawn into the indoor units 5-1 to 5-10 by the rotation of each indoor unit fan 55. In this way, each indoor heat exchanger 51 functions as an evaporator, and the indoor air that has been cooled by exchanging heat with the refrigerant in each indoor heat exchanger 51 is blown out into the room from an air outlet (not shown), thereby cooling the room in which the indoor units 5-1 to 5-10 are installed.

The refrigerant that flows out from each indoor heat exchanger 51 to each indoor unit gas pipe 72 flows out into the gas pipe 9 through each gas pipe connection 54. The refrigerant that joins in the gas pipe 9 and flows into the outdoor unit 2 through the shutoff valve 26 flows in the order of the outdoor unit gas pipe 45, the four-way valve 22, the refrigerant piping 46, the accumulator 27, and the suction pipe 42, and is sucked into the compressor 20 and compressed again.

In the air conditioner 1, multiple indoor units can simultaneously perform air conditioning operations such as heating operation. During heating operation, the indoor unit control device 200 of the indoor units 5-1 to 5-10 detects the temperature of the indoor air based on the indoor temperature sensor 63, and if the temperature of the indoor air becomes higher than the temperature obtained by adding a first predetermined temperature (e.g., 1°C) to the set temperature (set temperature + first predetermined temperature), the indoor unit expansion valve 52 is slightly opened to significantly reduce the amount of refrigerant flowing into the indoor heat exchanger 51, and the indoor unit fan 55 is stopped to switch to thermo-off operation, which stops the air conditioning operation. Also, if the temperature of the indoor air becomes lower than the temperature obtained by subtracting a second predetermined temperature (e.g., 1°C) from the set temperature during thermo-off, the expansion valve opening is set to an opening corresponding to the required air conditioning capacity, and the indoor fan is started to resume blowing air into the room.

The monitoring operation performed during thermo-off operation when the air conditioner 1 of this embodiment is performing heating operation will be described below with reference to the flow diagram of FIG.
<Monitoring operation>
The monitoring operation is an operation during heating operation in which, after a predetermined interval has elapsed since the start of thermo-off operation, the indoor unit fan 55 is driven for a predetermined time to detect the indoor air temperature with the indoor temperature sensor 63 and determine whether to continue thermo-off operation or to terminate thermo-off operation and switch to thermo-on operation. If the detected indoor air temperature is higher than the set temperature minus a second predetermined temperature (for example, 1°C) (set temperature - second predetermined temperature), thermo-off operation is continued, and if the detected indoor air temperature is lower than the set temperature minus the second predetermined temperature (for example, 1°C) (set temperature - second predetermined temperature), thermo-off operation is terminated and switched to thermo-on operation.

In this embodiment, in the monitoring operation, after a predetermined interval has elapsed since the start of thermo-off operation, the indoor unit fan 55 is driven for a predetermined time, and the predetermined interval is controlled to change according to the number of thermo-off operations that continue. By performing such control, for example, when performing heating operation in intermediate seasons such as spring and autumn, in an indoor unit installed in a space with a small air conditioning load (for example, a space facing a south-facing window), thermo-off operation is repeated almost all day, but at this time, it is possible to prevent the room from becoming too warm due to the heated air blown out from the indoor unit each time thermo-off operation is performed.

The indoor unit control device 200 determines whether the indoor air temperature during heating operation (salmon on operation) is higher than the temperature obtained by adding the set temperature to a first predetermined temperature (set temperature + first predetermined temperature) (S1). If the indoor air temperature is higher than the temperature obtained by adding the set temperature to the first predetermined temperature (set temperature + first predetermined temperature) (S1-YES), the indoor unit control device 200 sets the counter 75 to an initial value, COUNT = 0 (S2). Next, the indoor unit control device 200 sets the predetermined interval T during which the indoor unit fan is stopped to a predetermined initial setting value (default), for example, 4 minutes (S3), and starts thermo-off operation (S4).

Next, the indoor unit control device 200 adds the number of thermo-off operations during heating operation to the current count (S5), and if the count is not less than a predetermined number (for example, 10 times) (S6-No), that is, if the number of thermo-off operations is not less than the predetermined number, the indoor unit control device 200 changes the predetermined interval T to 5 minutes, which is the initial setting value of 4 minutes plus 1 minute (S11). Next, the indoor unit control device 200 determines whether the predetermined interval T is less than 14 minutes (S12-Yes), and if the predetermined interval T is less than 14 minutes (S12-No), the predetermined interval T is set to 14 minutes (S13) and the process proceeds to S7. In other words, in the processes of S11 to S13, the predetermined interval T is controlled to be changed from the initial setting value depending on the number of thermo-off operations to be continued. Also, the maximum value of the predetermined interval T is set to 14 minutes in this embodiment.

Next, the process moves to a monitoring operation to determine whether to continue thermo-off operation or to end thermo-off operation and switch to thermo-on operation (S8 to S10 are processes related to the monitoring operation). In ST6, if the count is less than the predetermined number (S6-Yes), in other words, the number of thermo-off operations is less than 10, the indoor unit control device 200 determines whether a predetermined interval T has elapsed since thermo-off operation was started (S7), and if the predetermined interval T has not elapsed since thermo-off operation was started (S7-No), the process returns to S7 and waits for the predetermined interval T to elapse.

If a predetermined interval T has elapsed since the start of thermo-off operation (S7-Yes), the indoor unit control device 200 drives the indoor unit fan 55 for a predetermined time (e.g., 1 minute) (S8), detects the indoor air temperature with the indoor temperature sensor 63 (S9), and determines whether the detected indoor air temperature is lower than the set temperature minus the second predetermined temperature (set temperature-second predetermined temperature) (S10). Note that if the number of thermo-off operations is less than 10 (as described above, S6-No), the predetermined interval T is the initial setting value of 4 minutes, and if the number of thermo-off operations is 10 or more (as described above, S6-Yes), the predetermined interval T is anywhere from 5 minutes to 14 minutes.

If the detected indoor air temperature is not lower than the set temperature minus the second predetermined temperature (set temperature - second predetermined temperature) (S10-No), that is, if the detected indoor air temperature is higher than (set temperature - second predetermined temperature), the indoor unit control device 200 returns to S4 and continues thermo-off operation. If the detected indoor air temperature is lower than the set temperature minus the second predetermined temperature (set temperature - second predetermined temperature) (S10-Yes), the indoor unit control device 200 stops thermo-off operation (S14), switches to thermo-on operation to resume heating operation (S15), and returns to S1.

In the processing of S11 to S13 described above, once the number of thermo-off operations reaches 10 or more, the predetermined interval T increases by one minute each time thermo-off operation continues, but the maximum value of the predetermined interval T is set to 14 minutes. Also, the first time thermo-off operation is performed, the number of thermo-off operations is 1 (as described above, in the case of S6-Yes), so the predetermined interval T is set to the initial setting value of 4 minutes. If the number of consecutive thermo-off operations reaches 9 (as described above, in the case of S6-Yes), the predetermined interval T remains at the initial setting value of 4 minutes.

If the number of consecutive thermo-off operations is 10 or more (as in the case of S6-No, as described above), the predetermined interval T is set to the initial setting of 4 minutes, with 1 minute added for each additional consecutive thermo-off operation. When the predetermined interval T reaches 14 minutes, it is fixed at 14 minutes thereafter.

When performing heating operation in intermediate seasons such as spring and autumn, an indoor unit installed in a space with a small air conditioning load (for example, a space facing a south-facing window) may be in the thermo-off state for almost the entire day. In this embodiment, if the thermo-off state continues, the more times the thermo-off operation continues, the longer the specified interval at which the indoor unit fan 55 is driven by the monitoring operation becomes. This lengthens the interval at which air heated by the indoor heat exchanger 51 is blown out of the indoor unit, reducing the risk of the room becoming too warm and causing discomfort to users.

In this embodiment, the initial predetermined interval of 4 minutes is changed to 5 minutes, one minute longer than the initial predetermined interval, from the monitoring operation at the 10th thermo-off operation, but the predetermined interval may be longer from the monitoring operation at the second thermo-off operation. Also, in the case of the 19th or subsequent thermo-off operation, the predetermined interval until the monitoring operation is performed is fixed at the maximum value of 14 minutes, but it is also possible to lengthen the predetermined interval as the number of thermo-off operations increases without setting a maximum value.

In addition, if the number of continued thermo-off operations reaches or exceeds a predetermined number, the predetermined interval may be set to a value obtained by subtracting a predetermined value (e.g., 5) from the number of continued thermo-off operations. For example, if the number of thermo-off operations reaches the predetermined number of 10, the predetermined interval may be set to 5, which is 10 minus 5, and if the number of thermo-off operations reaches the predetermined number of 11, the predetermined interval may be set to 6, which is 11 minus 5.

In this embodiment, the indoor unit control device 200 controls to lengthen the predetermined interval during which the indoor unit fan 55 is stopped as the number of thermo-off operations continued by the monitoring operation increases. However, for example, in the case of an indoor unit installed in a space with a large air conditioning load, if the monitoring operation switches to thermo-on operation before the number of thermo-off operations continued by the monitoring operation reaches the set predetermined number, the control may be performed to shorten the predetermined interval during which the indoor unit fan 55 is stopped during the monitoring operation. In other words, the control may be performed to shorten the predetermined interval during which the indoor unit fan 55 is stopped as the number of thermo-off operations continued by the monitoring operation decreases. By performing such control, in the case of an indoor unit installed in a space with a large air conditioning load, it is possible to switch to thermo-on operation earlier during thermo-off operation, thereby shortening the time during which the indoor air temperature is outside the set temperature range.

The above description refers to a limited number of embodiments, but the scope of the rights is not limited to these, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art.

1...Air conditioner, 2...Outdoor unit, 5-1 to 5-10...Indoor unit, 10...Refrigerant circuit, 20...Compressor, 23...Outdoor heat exchanger, 51...Indoor heat exchanger, 52...Indoor unit expansion valve, 55...Indoor unit fan, 63...Indoor temperature sensor, 100...Outdoor unit control device, 200...Indoor unit control device

Claims (4)

A plurality of indoor units each including an indoor heat exchanger, an indoor unit fan, an indoor temperature sensor, and an indoor unit control device that controls the driving of the indoor unit fan;
The same number of indoor unit expansion valves as the indoor units;
An outdoor unit including a compressor and an outdoor heat exchanger ,
When the indoor air temperature detected by the indoor temperature sensor of the indoor unit during heating operation becomes higher than a temperature obtained by adding a first predetermined temperature to the set temperature, the indoor unit control device switches the indoor unit to thermo-off operation, and after a predetermined interval has elapsed since the start of the thermo-off operation, drives the indoor unit fan for a predetermined time to detect the indoor air temperature with the indoor temperature sensor and perform a monitoring operation to determine whether to continue the thermo-off operation,
In the monitoring operation, if the detected indoor air temperature is higher than the set temperature minus the second predetermined temperature, the thermo-off operation is continued, and if the detected indoor air temperature is lower than the set temperature minus the second predetermined temperature, the thermo-off operation is terminated and the indoor unit is switched to thermo-on operation;
The air conditioning apparatus is characterized in that the indoor unit control device counts the number of times the thermo-off operation has continued when the monitoring operation has occurred, and changes the specified interval according to the number of times the thermo-off operation has been counted before starting the next monitoring operation . The air conditioner according to claim 1, characterized in that the indoor unit control device lengthens the predetermined interval as the number of times the thermo-off operation is counted increases. The air conditioner according to claim 2, characterized in that when the number of times the thermo-off operation is counted reaches or exceeds a predetermined number, the indoor unit control device lengthens the predetermined interval as the number of times the thermo-off operation is counted increases. The air conditioner according to claim 2 or 3, characterized in that the indoor unit control device determines a maximum value of the predetermined interval, and the predetermined interval remains at the maximum value after it reaches the maximum value.

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