Refrigeration cycle device

Abstract

A refrigeration cycle device according to an embodiment includes a main circuit, a check valve, and a control unit. The main circuit annularly connects the compressor, the first heat exchanger, the expansion device, and the second heat exchanger, and circulates a refrigerant. The downstream side in the flow direction of the refrigerant is set as a first side, and the upstream side in the flow direction of the refrigerant is set as a second side. The check valve is provided in the main circuit on the first side of the compressor. When a predetermined condition is satisfied and the operation of the compressor is stopped, the control unit controls the implementation of the pressure reduction operation. The pressure reduction operation is an operation for reducing a first pressure of the main circuit on a first side of the check valve.

Description

Technical Field

[0001] An embodiment of the present invention relates to a refrigeration cycle device.

[0002] This application claims priority based on Japanese Patent Application No. 2023-021787 filed in Japan on February 15, 2023, and the contents are incorporated herein by reference. Background Art

[0003] A refrigeration cycle device has a main circuit. In the main circuit, a compressor, a first heat exchanger, an expansion device, and a second heat exchanger are connected in a ring shape. The main circuit allows refrigerant to flow through the compressor, the first heat exchanger, the expansion device, and the second heat exchanger. Sometimes a check valve is provided in the main circuit of the refrigeration cycle device. The check valve is provided on the downstream side of the compressor in the flow direction of the refrigerant. When the main circuit located on the downstream side of the compressor is in a high-pressure state, the compressor sometimes stops. A refrigeration cycle device capable of stably restarting the compressor is required.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2022 / 059054 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The technical problem to be solved by the present invention is to provide a refrigeration cycle device capable of stably restarting a compressor.

[0009] Solutions for solving the above technical problems

[0010] The refrigeration cycle device of the embodiment has a main circuit, a check valve and a control unit. The main circuit connects the compressor, the first heat exchanger, the expansion device and the second heat exchanger in a ring shape to circulate the refrigerant. The downstream side of the circulation direction of the refrigerant is set as the first side, and the upstream side of the circulation direction of the refrigerant is set as the second side. The check valve is provided in the main circuit on the first side of the compressor. When the prescribed conditions are met and the operation of the compressor is stopped, the control unit controls the implementation of the pressure reduction action. The pressure reduction action is an action to reduce the first pressure of the main circuit on the first side of the check valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a circuit diagram showing the refrigeration cycle device in the embodiment.

[0012] Figure 2 It is a circuit diagram showing a refrigeration cycle device in a first modified example of the embodiment.

[0013] Figure 3 It is a circuit diagram showing a refrigeration cycle device in a second modified example of the embodiment. DETAILED DESCRIPTION

[0014] Hereinafter, a refrigeration cycle apparatus according to an embodiment will be described with reference to the drawings.

[0015] Figure 1 1 is a circuit diagram showing a refrigeration cycle device 1 in an embodiment. The refrigeration cycle device 1 has an outdoor unit 11, an indoor unit 10, and a main circuit 5. The main circuit 5 allows the refrigerant to circulate in the outdoor unit 11 and the indoor unit 10. In the present embodiment, the downstream side (first side) of the circulation direction of the refrigerant is sometimes referred to as simply the "downstream side", and the upstream side (second side) of the circulation direction of the refrigerant is sometimes referred to as simply the "upstream side". In the present embodiment, the pipe through which the refrigerant circulates is sometimes referred to as a "circuit".

[0016] The refrigeration cycle device 1 contains a refrigerant such as R410A, R32, R1123, R454B, R466A or carbon dioxide (CO2). The refrigerant circulates in the refrigeration cycle device 1 while undergoing a phase change.

[0017] The outdoor unit 11 includes a compressor 2, a check valve 3, a four-way valve 18, an outdoor heat exchanger 8, and an outdoor expansion valve 6b.

[0018] The indoor unit 10 includes an indoor heat exchanger 4 and an indoor expansion valve 6 a .

[0019] A case where the refrigeration cycle apparatus 1 performs cooling operation will be described.

[0020] The compressor 2 compresses the low-pressure gas refrigerant taken into the compressor 2 into a high-temperature, high-pressure gas refrigerant. The refrigerant discharged from the compressor 2 is supplied to the four-way valve 18 via the oil separator 2b and the check valve 3. When the refrigeration cycle device 1 performs a cooling operation, the refrigerant is supplied from the four-way valve 18 to the outdoor heat exchanger 8 of the outdoor unit 11.

[0021] The outdoor heat exchanger 8 functions as a condenser (radiator, first heat exchanger). The condenser dissipates heat from the high-temperature, high-pressure gas refrigerant discharged from the compressor 2, and converts the high-temperature, high-pressure gas refrigerant into a high-pressure liquid refrigerant. The outdoor heat exchanger 8 is provided with an outdoor fan (fan) 8f. The outdoor fan 8f circulates outdoor air to the outdoor heat exchanger 8.

[0022] The refrigeration cycle device 1 has an outdoor expansion valve 6b and an indoor expansion valve 6a as an expansion device 6. When the refrigeration cycle device 1 performs a refrigeration operation, the refrigerant discharged from the outdoor heat exchanger 8 flows sequentially through the outdoor expansion valve (first expansion device) 6b and the indoor expansion valve (second expansion device) 6a. The outdoor expansion valve 6b and the indoor expansion valve 6a reduce the pressure of the high-pressure liquid refrigerant supplied from the outdoor heat exchanger 8, so that the high-pressure liquid refrigerant becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant. The refrigerant discharged from the indoor expansion valve 6a is supplied to the indoor heat exchanger 4.

[0023] The indoor heat exchanger 4 functions as an evaporator (heat absorber, second heat exchanger). The evaporator converts the gas-liquid two-phase refrigerant discharged from the indoor expansion valve 6a into a low-pressure gas refrigerant. The refrigerant discharged from the indoor heat exchanger 4 is supplied to the four-way valve 18. The refrigerant discharged from the four-way valve 18 is supplied to the compressor 2 via the accumulator (gas-liquid separator) 2a.

[0024] The refrigeration cycle device 1 performs a refrigeration operation as described above. In the main circuit 5, the compressor 2, the outdoor heat exchanger 8 (the first heat exchanger), the expansion device 6, and the indoor heat exchanger 4 (the second heat exchanger) are connected in sequence in a ring shape. The main circuit 5 allows the refrigerant to circulate through the compressor 2, the outdoor heat exchanger 8, the expansion device 6, and the indoor heat exchanger 4. In the main circuit 5, the path from the downstream side of the compressor 2 to the indoor expansion valve 6a of the expansion device 6 along the flow direction of the refrigerant is the high-pressure circuit 5a. The pressure of the refrigerant in the high-pressure circuit 5a is relatively high. In the main circuit 5, the path from the indoor expansion valve 6a of the expansion device 6 to the upstream side of the compressor 2 along the flow direction of the refrigerant is the low-pressure circuit 5b. The pressure of the refrigerant in the low-pressure circuit 5b is relatively low.

[0025] When the refrigeration cycle device 1 performs heating operation, Figure 1 The state shown is the switching state of the four-way valve 18. By the switching action of the four-way valve 18, the refrigerant discharged from the compressor 2 flows in the order of the four-way valve 18, the indoor heat exchanger 4, the expansion device 6, the outdoor heat exchanger 8, the four-way valve 18, and the compressor 2. In this case, the indoor heat exchanger 4 functions as an evaporator (radiator, first heat exchanger), and the outdoor heat exchanger 8 functions as a condenser (absorber, second heat exchanger).

[0026] The refrigeration cycle device 1 performs heating operation as described above. In the main circuit 5, the compressor 2, the indoor heat exchanger 4 (the first heat exchanger), the expansion device 6, and the outdoor heat exchanger 8 (the second heat exchanger) are connected in sequence in a ring shape. The main circuit 5 allows the refrigerant to flow through the compressor 2, the indoor heat exchanger 4, the expansion device 6, and the outdoor heat exchanger 8. The refrigerant discharged from the indoor heat exchanger 4 flows in sequence through the indoor expansion valve (the first expansion device) 6a and the outdoor expansion valve (the second expansion device) 6b. In the main circuit 5, the path from the downstream side of the compressor 2 to the outdoor expansion valve 6b of the expansion device 6 along the flow direction of the refrigerant is the high-pressure circuit 5a. In the main circuit 5, the path from the outdoor expansion valve 6b of the expansion device 6 to the upstream side of the compressor 2 along the flow direction of the refrigerant is the low-pressure circuit 5b.

[0027] In the present embodiment, the heat exchanger that functions as a condenser (radiator) among the outdoor heat exchanger 8 and the indoor heat exchanger 4 is sometimes referred to as a first heat exchanger, and the heat exchanger that functions as an evaporator (heat absorber) is sometimes referred to as a second heat exchanger. In the present embodiment, the expansion valve located on the upstream side of the refrigerant flow direction among the outdoor expansion valve 6b and the indoor expansion valve 6a is sometimes referred to as a first expansion device, and the expansion valve located on the downstream side is sometimes referred to as a second expansion device.

[0028] The outdoor unit 11 has a discharge pressure sensor 14, a suction pressure sensor 15, and an external air temperature sensor 17. The discharge pressure sensor 14 is provided in the high-pressure circuit 5a. The discharge pressure sensor 14 outputs a discharge pressure signal corresponding to the discharge pressure of the refrigerant of the compressor 2. The suction pressure sensor 15 is provided in the low-pressure circuit 5b. The suction pressure sensor 15 outputs a suction pressure signal corresponding to the suction pressure of the refrigerant of the compressor 2. The external air temperature sensor 17 is provided in a place of the outdoor unit 11 in contact with the external air. The external air temperature sensor 17 is provided near the outdoor heat exchanger 8. The external air temperature sensor 17 outputs an external air temperature signal corresponding to the external air temperature.

[0029] The outdoor unit 11 has a pressure equalizing circuit 26 and a pressure equalizing circuit valve 27. The pressure equalizing circuit 26 connects the high-pressure circuit 5a and the low-pressure circuit 5b on the upstream side of the check valve 3. The pressure equalizing circuit valve 27 is provided in the pressure equalizing circuit 26 to open and close the pressure equalizing circuit 26. The pressure equalizing circuit valve 27 opens when the compressor 2 is stopped. The pressure equalizing circuit 26 equalizes the pressure of the high-pressure circuit 5a and the pressure of the low-pressure circuit 5b on the upstream side of the check valve 3. The pressure equalizing circuit 26 reduces the pressure of the high-pressure circuit 5a on the upstream side of the check valve 3.

[0030] The outdoor unit 11 includes a subcooling heat exchanger 20 , a subcooling circuit (bypass circuit) 21 , and a subcooling circuit expansion valve (bypass circuit opening and closing device) 22 .

[0031] The subcooling heat exchanger 20 is provided in the main circuit 5 between the outdoor expansion valve 6b and the indoor expansion valve 6a.

[0032] The subcooling circuit 21 connects the first position 21a of the high-pressure circuit 5a on the downstream side of the check valve 3 to the second position 21b of the low-pressure circuit 5b on the upstream side of the compressor 2. When the refrigeration cycle device 1 performs cooling operation, the first position 21a is the downstream side of the outdoor heat exchanger 8 and the downstream side of the subcooling heat exchanger 20. The second position 21b is the downstream side of the indoor heat exchanger 4. When the refrigeration cycle device 1 performs heating operation, the first position 21a is the downstream side of the indoor heat exchanger 4 and the upstream side of the subcooling heat exchanger 20. The second position 21b is the downstream side of the outdoor heat exchanger 8.

[0033] The subcooling circuit 21 passes through the subcooling heat exchanger 20. The subcooling heat exchanger 20 performs heat exchange between the refrigerant flowing in the main circuit 5 and the refrigerant flowing in the subcooling circuit 21. The refrigerant flowing in the subcooling circuit 21 absorbs heat from the refrigerant flowing in the main circuit 5. The subcooling heat exchanger 20 liquefies the refrigerant flowing in the main circuit 5.

[0034] The subcooling circuit expansion valve 22 reduces the pressure of the refrigerant flowing through the subcooling circuit 21. The subcooling circuit expansion valve 22 adjusts the opening degree of the subcooling circuit 21.

[0035] The refrigeration cycle device 1 has a CPU (Central Processing Unit), a memory, an auxiliary storage device, etc. The CPU functions as a control unit 13 by executing programs stored in the memory and the auxiliary storage device. The control unit 13 controls the operation of each unit of the refrigeration cycle device 1. The control unit 13 controls the current of the motor driving the compressor 2 (sometimes referred to as the driving current of the compressor). The control unit 13 receives a discharge pressure signal output from the discharge pressure sensor 14 and an external air temperature signal output from the external air temperature sensor 17. The control unit 13 controls the opening and closing of the equalizing pressure circuit valve 27 and the subcooling circuit expansion valve 22.

[0036] Hereinafter, a case where the refrigeration cycle apparatus 1 performs cooling operation will be described as an example.

[0037] During the cooling operation of the refrigeration cycle device 1, the outside air temperature may become high. In order to make the refrigerant supplied to the outdoor heat exchanger (radiator) 8 high in temperature, the compressor 2 is operated in an overloaded state. A large current flows through the motor of the compressor 2. The refrigerant in the high-pressure circuit 5a becomes high pressure.

[0038] When the refrigerant in the high-pressure circuit 5a is at a high pressure, the operation of the refrigeration cycle device 1 is sometimes stopped. As the operation of the refrigeration cycle device 1 is stopped, the operation of the compressor 2 is stopped, and the outdoor expansion valve 6b and the indoor expansion valve 6a are closed. At this time, the pressure of the high-pressure circuit 5a on the upstream side of the check valve 3 is reduced by opening the pressure equalization circuit valve 27. The pressure of the high-pressure circuit 5a on the downstream side of the check valve 3 (sometimes referred to as the first pressure) is maintained at a high pressure state.

[0039] When the operation of the refrigeration cycle device 1 is restarted, the compressor 2 is restarted. In order to circulate the refrigerant, the compressor 2 increases the pressure of the refrigerant to a higher level than the first pressure. The compressor 2 suddenly becomes overloaded, and the motor may lose step, etc. It is difficult to restart the compressor 2 stably.

[0040] When the predetermined condition is satisfied and the operation of the compressor 2 is stopped, the control unit 13 controls the execution of the pressure reducing operation. The pressure reducing operation is an operation for reducing the first pressure of the high pressure circuit 5a on the downstream side of the check valve 3.

[0041] The pressure reduction action is an action of opening the subcooling circuit expansion valve 22. By opening the subcooling circuit expansion valve 22, the refrigerant of the high-pressure circuit 5a flows to the low-pressure circuit 5b through the subcooling circuit 21. The first pressure of the high-pressure circuit 5a is reduced. As a result, the compressor 2 can be restarted stably. The subcooling circuit 21 and the subcooling circuit expansion valve 22 are used as a bypass circuit and a bypass circuit opening and closing device between the high-pressure circuit 5a and the low-pressure circuit 5b. Since there is no need to set up a new bypass circuit and a bypass circuit opening and closing device, the cost increase of the refrigeration cycle device 1 can be suppressed.

[0042] When the compressor 2 is stopped, the outdoor expansion valve 6b and the indoor expansion valve 6a are closed. If the subcooling circuit expansion valve 22 is opened in this state, the first pressure on the downstream side of the outdoor expansion valve (first expansion device) 6b decreases, but the first pressure on the upstream side does not decrease. When the compressor 2 is restarted, if the outdoor expansion valve 6b is opened, the first pressure on the upstream side of the outdoor expansion valve 6b decreases. In this way, the compressor 2 can be restarted stably. The control unit 13 can also open the subcooling circuit expansion valve 22 and open the outdoor expansion valve 6b when the compressor 2 is stopped.

[0043] The pressure reduction operation may also be an operation of operating the outdoor fan 8f. The outdoor fan 8f circulates outdoor air to the outdoor heat exchanger 8. The temperature of the refrigerant passing through the high-pressure circuit 5a of the outdoor heat exchanger 8 decreases, and the first pressure of the high-pressure circuit 5a decreases. As a result, the compressor 2 can be restarted stably.

[0044] As described above, when the predetermined condition is satisfied and the operation of the compressor 2 is stopped, the control unit 13 controls the execution of the pressure reducing operation.

[0045] The prescribed condition is a condition that the drive current of the compressor 2 exceeds the first prescribed value. As described above, the control unit 13 controls the drive current of the compressor 2. The greater the drive current of the compressor 2, the higher the first pressure of the high-pressure circuit 5a. If the compressor 2 is restarted in a state where the first pressure of the high-pressure circuit 5a is high, the compressor 2 is driven with a current greater than the drive current when the operation is stopped. If the compressor 2 is restarted suddenly with a large drive current, motor imbalance and the like may occur. The first prescribed value is a current value that makes the restart of the compressor 2 unstable. When the drive current of the compressor 2 is in a state exceeding the first prescribed value and the operation of the compressor 2 is stopped, the control unit 13 controls the implementation of the pressure reduction action. Thereby, the compressor 2 can be restarted stably.

[0046] The predetermined condition may also be a condition that the first pressure of the high-pressure circuit 5a exceeds the second predetermined value. The control unit 13 receives the discharge pressure signal output from the discharge pressure sensor 14 and detects the first pressure of the high-pressure circuit 5a. When the first pressure of the high-pressure circuit 5a exceeds the second predetermined value and the operation of the compressor 2 is stopped, the control unit 13 controls the implementation of the pressure reduction operation. In this way, the compressor 2 can be restarted stably.

[0047] The prescribed condition may also be a condition that the external air temperature exceeds the third prescribed value during the refrigeration operation of the refrigeration cycle device 1. The control unit 13 receives the external air temperature signal output from the external air temperature sensor 17 and detects the external air temperature. The higher the external air temperature, the greater the drive current of the compressor 2, and the higher the first pressure of the high-pressure circuit 5a. When the external air temperature exceeds the third prescribed value during the refrigeration operation of the refrigeration cycle device 1 and the operation of the compressor 2 is stopped, the control unit 13 controls the implementation of the pressure reduction action. Thereby, the compressor 2 can be restarted stably.

[0048] As described above in detail, the refrigeration cycle device 1 of the embodiment includes a main circuit 5, a check valve 3, and a control unit 13. The check valve 3 is provided in the main circuit 5 on the downstream side of the compressor 2. When the predetermined conditions are satisfied and the operation of the compressor 2 is stopped, the control unit 13 controls the implementation of the pressure reduction operation. The pressure reduction operation is an operation to reduce the first pressure of the main circuit 5 on the downstream side of the check valve 3.

[0049] By reducing the first pressure of the main circuit 5 on the downstream side of the check valve 3, a sudden overload at the time of restarting the compressor 2 is suppressed. Thus, the compressor 2 can be restarted stably.

[0050] Figure 21 is a circuit diagram showing a refrigeration cycle device 1B in a first variant of the embodiment. The refrigeration cycle device 1B of the first variant is different from the refrigeration cycle device 1 of the embodiment in that it has a plurality of outdoor units 11 and 12 connected in parallel with the indoor unit 10. The description of the first variant of the same points as the embodiment is sometimes omitted.

[0051] The plurality of outdoor units 11 and 12 include a first outdoor unit 11 and a second outdoor unit 12. The plurality of outdoor units may include three or more outdoor units. The first outdoor unit 11 includes a compressor 2, a check valve 3, a four-way valve 18, an outdoor heat exchanger 8, and an outdoor expansion valve 6b. The second outdoor unit 12 is configured similarly to the first outdoor unit 11. The indoor unit 10 includes an indoor heat exchanger 4 and an indoor expansion valve 6a.

[0052] The control unit 13 adjusts the number of operating outdoor units 11 and 12 based on the indoor temperature and the outdoor temperature. Sometimes, only a part of the outdoor units 11 and 12 are in operation, and the remaining outdoor units are stopped. Figure 2 In the heating operation state shown, only the first outdoor unit 11 is in operation, and the second outdoor unit 12 is stopped. The high-pressure refrigerant discharged from the compressor 2 of the first outdoor unit 11 enters the stopped second outdoor unit 12 in addition to the indoor unit 10. The check valve 3 of the second outdoor unit 12 prevents the high-pressure refrigerant from entering the stopped second outdoor unit 12 from the operating first outdoor unit 11.

[0053] When the refrigeration cycle device 1B performs cooling operation, Figure 2 The state shown is the switching state of the four-way valve 18. As in the embodiment, the operation of the compressor 2 may be stopped when the refrigerant in the high-pressure circuit 5a is at a high pressure. It is difficult to restart the compressor 2 stably.

[0054] When the predetermined condition is satisfied and the operation of the compressor 2 is stopped, the control unit 13 controls the implementation of the pressure reduction action. As in the embodiment, the pressure reduction action is an action of opening the subcooling circuit expansion valve 22, etc. The predetermined condition is a condition that the drive current of the compressor 2 exceeds the first predetermined value, etc. Thus, the compressor 2 can be restarted stably.

[0055] Figure 3 1 is a circuit diagram showing a refrigeration cycle device 1C in a second variant of the embodiment. The refrigeration cycle device 1C of the second variant is different from the refrigeration cycle device 1 of the embodiment in that it has a plurality of indoor units 10 connected in parallel to the outdoor unit 11 via a switching unit 40. The description of the second variant of the same points as the embodiment is sometimes omitted.

[0056] The refrigeration cycle device 1C is a heat recovery type air conditioning system capable of operating simultaneously in cooling and heating in a plurality of indoor units 10. The refrigeration cycle device 1C includes an outdoor unit 11, a plurality of indoor units 10, a first circuit 31, a second circuit 32, a third circuit 33, and a switching unit 40.

[0057] The outdoor unit 11 includes a compressor 2, a check valve 3, a four-way valve 18, an outdoor heat exchanger 8, and an outdoor expansion valve 6b. The plurality of indoor units 10 include an indoor expansion valve 6a and an indoor heat exchanger 4, respectively.

[0058] The first circuit 31 allows the refrigerant to flow between the outdoor heat exchanger 8 and the indoor heat exchanger 4 .

[0059] The second circuit 32 allows the refrigerant discharged from the compressor 2 to flow into the indoor heat exchanger 4 .

[0060] The third circuit 33 allows the refrigerant flowing out of the indoor heat exchanger 4 to flow into the compressor 2 .

[0061] The switching unit 40 switches the connection between the second circuit 32 and the third circuit 33 and the indoor heat exchanger 4 for each of the plurality of indoor units 10. The switching unit 40 includes a second circuit valve 42 and a third circuit valve 43. The second circuit valve 42 opens and closes the second circuit 32. The third circuit valve 43 opens and closes the third circuit 33.

[0062] The control unit 13 controls the switching of the four-way valve 18 based on the command input of the user, and controls the opening and closing of the second circuit valve 42 and the third circuit valve 43. Thus, in the plurality of indoor units 10, simultaneous cooling and heating operations can be performed.

[0063] As in the embodiment, the operation of the compressor 2 may be stopped when the refrigerant in the high-pressure circuit 5a is at a high pressure. It is difficult to restart the compressor 2 stably.

[0064] When the predetermined condition is satisfied and the operation of the compressor 2 is stopped, the control unit 13 controls the implementation of the pressure reduction action. As in the embodiment, the pressure reduction action is an action of opening the subcooling circuit expansion valve 22, etc. The predetermined condition is a condition that the drive current of the compressor 2 exceeds the first predetermined value, etc. Thus, the compressor 2 can be restarted stably.

[0065] In the embodiment, the subcooling circuit 21 and the subcooling circuit expansion valve 22 are used as a bypass circuit and a bypass circuit opening and closing device between the high-pressure circuit 5a and the low-pressure circuit 5b. In contrast, a new bypass circuit and a bypass circuit opening and closing device different from the subcooling circuit 21 and the subcooling circuit expansion valve 22 may also be provided.

[0066] According to at least one embodiment described above, there is a control unit 13, which controls the implementation of the pressure reduction action when the predetermined conditions are met and the operation of the compressor 2 is stopped. The pressure reduction action is an action to reduce the first pressure of the main circuit 5 on the downstream side of the check valve 3. Thereby, the compressor 2 can be restarted stably.

[0067] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope and subject matter of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

[0068] Description of Reference Numerals

[0069] 1. 1B, 1C Refrigeration cycle device

[0070] 2 compressor

[0071] 3 Check valve

[0072] 4 Indoor heat exchanger (2nd heat exchanger, 1st heat exchanger)

[0073] 5 Main circuit

[0074] 6 Expansion device

[0075] 6a Indoor expansion valve (second expansion device, first expansion device)

[0076] 6b Outdoor expansion valve (1st expansion device, 2nd expansion device)

[0077] 8Outdoor heat exchanger (1st heat exchanger, 2nd heat exchanger)

[0078] 8f outdoor fan (fan)

[0079] 21 Subcooling circuit (bypass circuit)

[0080] 21a1st position

[0081] 21b 2nd position

[0082] 22 Subcooling circuit expansion valve (bypass circuit opening and closing device).

Claims

1. A refrigeration cycle device, characterized in that: have: A main circuit connects the compressor, the first heat exchanger, the expansion device, and the second heat exchanger in a ring shape to allow the refrigerant to flow; a check valve, wherein the check valve is provided in the main circuit on the first side of the compressor when the downstream side in the flow direction of the refrigerant is set as the first side and the upstream side in the flow direction of the refrigerant is set as the second side; The control unit controls execution of a pressure reducing operation for reducing a first pressure of the main circuit on the first side of the check valve when a predetermined condition is satisfied and the operation of the compressor is stopped.

2. The refrigeration cycle device according to claim 1, characterized in that: The predetermined condition is a condition that a drive current of the compressor exceeds a first predetermined value.

3. The refrigeration cycle device according to claim 1, characterized in that: The predetermined condition is a condition that the first pressure exceeds a second predetermined value.

4. The refrigeration cycle device according to claim 1, wherein: The predetermined condition is a condition that the outside air temperature exceeds a third predetermined value during cooling operation of the refrigeration cycle device.

5. The refrigeration cycle device according to claim 1, wherein: Further having: a bypass circuit connecting a first position of the main circuit in the first side of the check valve with a second position of the main circuit in the second side of the compressor; A bypass circuit opening and closing device is arranged in the bypass circuit, The pressure reducing operation is an operation of opening the bypass circuit opening and closing device.

6. The refrigeration cycle device according to claim 5, characterized in that: The expansion device comprises a first expansion device and a second expansion device located on the first side of the first expansion device. The first position is a position between the first heat exchanger and the second expansion device. The second position is a position between the second heat exchanger and the compressor.

7. The refrigeration cycle device according to claim 5, characterized in that: The bypass circuit is a subcooling circuit.

8. The refrigeration cycle device according to claim 1, wherein: further comprising a fan for circulating outdoor air to the first heat exchanger, The pressure reducing operation is an operation of operating the fan.

9. The refrigeration cycle device according to claim 1, wherein: A plurality of outdoor units including the compressor, the check valve, and one of the first heat exchanger and the second heat exchanger are connected in parallel to an indoor unit, and the indoor unit includes the other of the first heat exchanger and the second heat exchanger.

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