Refrigeration cycle device

Abstract

A refrigeration cycle device according to an embodiment includes an outdoor unit, a plurality of indoor units, a first pipe, a second pipe, a third pipe, a switching unit, and a control unit. The outdoor unit includes a compressor and an outdoor heat exchanger. The plurality of indoor units includes an indoor expansion valve and an indoor heat exchanger. The first pipe causes a refrigerant to flow between the outdoor heat exchanger and the indoor heat exchanger. The second pipe causes the refrigerant discharged from the compressor to flow into the indoor heat exchanger. The third pipe causes the refrigerant flowing out of the indoor heat exchanger to flow into the compressor. The switching means switches the connection of the second pipe and the third pipe to the indoor heat exchanger. The control unit sets the upper limit opening degree of the indoor expansion valve when a predetermined condition is satisfied in a state in which the indoor heat exchanger is connected to the third pipe in the switching unit.

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. 2023-026487 filed in Japan on February 22, 2023, the contents of which are incorporated herein by reference. Background Art

[0003] A refrigeration cycle device capable of performing simultaneous cooling and heating operations is used in a plurality of indoor units. In the refrigeration cycle device, it is required to suppress the generation of abnormal noise.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-57826 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] An object of the present invention is to provide a refrigeration cycle device capable of suppressing the generation of abnormal noise.

[0009] Means for solving problems

[0010] The refrigeration cycle device of Option 1 includes an outdoor unit, multiple indoor units, a first pipe, a second pipe, a third pipe, a switching unit, and a control unit. The outdoor unit includes a compressor and an outdoor heat exchanger. The multiple indoor units include indoor expansion valves and indoor heat exchangers. The first pipe allows refrigerant to circulate between the outdoor heat exchanger and the indoor heat exchanger. The second pipe allows refrigerant discharged from the compressor to flow into the indoor heat exchanger. The third pipe allows refrigerant flowing out of the indoor heat exchanger to flow into the compressor. The switching unit switches the connection between the second pipe and the third pipe relative to the indoor heat exchanger. When the indoor heat exchanger and the third pipe are connected in the switching unit, the control unit sets the upper limit opening of the indoor expansion valve if specified conditions are met.

[0011] In the refrigeration cycle apparatus of claim 2, in the refrigeration cycle apparatus of claim 1, the upper limit opening degree is a value corresponding to at least one of the capacity information and the form information of the indoor unit.

[0012] In the refrigeration cycle apparatus according to claim 3, in the refrigeration cycle apparatus according to claim 1 or 2, the predetermined condition is a condition for inputting a setting instruction of the upper limit opening degree to the control unit.

[0013] In the refrigeration cycle device of claim 4, in the refrigeration cycle device of any one of claims 1 to 3, the predetermined condition is a condition that a predetermined time has not elapsed since the indoor unit started the cooling operation.

[0014] The refrigeration cycle device of claim 5 is the refrigeration cycle device of any one of claims 1 to 4, further comprising a main pipe. The main pipes corresponding to the plurality of indoor units and the third pipe are connected to the main pipe. The indoor unit corresponding to the main pipe that is the longest distance from the third pipe along the axial direction of the main pipe is the first indoor unit. When the indoor heat exchanger of the first indoor unit is connected to the third pipe in the switching unit, and when predetermined conditions are satisfied, the control unit sets an upper limit opening of the indoor expansion valve of the first indoor unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a circuit diagram showing a refrigeration cycle device according to an embodiment.

[0016] Figure 2 It is a cross-sectional view showing the third main pipe and the third branch pipe. DETAILED DESCRIPTION

[0017] Hereinafter, a refrigeration cycle device 1 according to an embodiment will be described with reference to the drawings.

[0018] Figure 1 : is a circuit diagram showing a refrigeration cycle device 1 in an embodiment. The refrigeration cycle device 1 includes an outdoor unit 11, a plurality of indoor units 10, and piping 30. The piping 30 allows the refrigerant to flow through the outdoor unit 11 and the plurality of indoor units 10. The refrigeration cycle device 1 is a heat recovery type air conditioning system capable of operating simultaneously in cooling and heating in the plurality of indoor units 10. Figure 1 In the illustrated example, the refrigeration cycle device 1 includes four indoor units 10 , namely, a first indoor unit 10 a , a second indoor unit 10 b , a third indoor unit 10 c , and a fourth indoor unit 10 d .

[0019] Refrigeration cycle device 1 contains a refrigerant such as R410A, R32, R1123, R454B, R466A, or carbon dioxide (CO2). The refrigerant circulates through refrigeration cycle device 1 while undergoing phase change. In this embodiment, the downstream side of the refrigerant flow direction may be simply referred to as the "downstream side," and the upstream side of the refrigerant flow direction may be simply referred to as the "upstream side."

[0020] 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 four-way valve 18 includes a first four-way valve 18a and a second four-way valve 18b. The first four-way valve 18a switches the connection of the compressor 2 to the upstream and downstream sides of the outdoor heat exchanger 8. The second four-way valve 18b switches the connection of the second pipe 32 and the third pipe 33 to the compressor 2.

[0021] Each of the plurality of indoor units 10 includes an indoor expansion valve 6a and an indoor heat exchanger 4. The indoor expansion valve 6a is, for example, an electronically controlled valve (Pulse Motor Valve: PMV). The outdoor expansion valve 6b and the indoor expansion valve 6a function as an expansion device 6.

[0022] The pipe 30 includes a first pipe 31 , a second pipe 32 , and a third pipe 33 .

[0023] The first pipe (liquid pipe) 31 allows the refrigerant to flow between the outdoor heat exchanger 8 and the indoor heat exchanger 4. The outdoor expansion valve 6b is provided in the first pipe 31.

[0024] The second pipe (discharge gas pipe) 32 allows the refrigerant discharged from the compressor 2 to flow into the indoor heat exchanger 4 .

[0025] The third pipe (intake gas pipe) 33 allows the refrigerant flowing out of the indoor heat exchanger 4 to flow into the compressor 2 .

[0026] The refrigeration cycle device 1 includes a switching unit 40. The switching unit 40 switches the connection between the second pipe 32 and the third pipe 33 and the indoor heat exchangers 4 of the plurality of indoor units 10. The switching unit 40 includes main pipes 61, 62, and 63, trunk pipes 51, 52, and 53, and on-off valves 42 and 43.

[0027] The switching unit 40 includes a first supply pipe 61, a second supply pipe 62, and a third supply pipe 63 as the supply pipes 61, 62, and 63. The switching unit 40 includes a plurality of first supply pipes 61, a plurality of second supply pipes 62, and a plurality of third supply pipes 63 corresponding to the plurality of indoor units 10. The first supply pipe 61 is connected to one of the inlet and outlet of the indoor heat exchanger 4 via the indoor expansion valve 6a. The second supply pipe 62 and the third supply pipe 63 merge with a connecting pipe 67. The connecting pipe 67 is connected to the other of the inlet and outlet of the indoor heat exchanger 4.

[0028] Switching unit 40 includes a first main pipe 51, a second main pipe 52, and a third main pipe 53 as the main pipes 51, 52, and 53. The first pipe 31 and a plurality of first branch pipes 61 are connected to the first main pipe 51. The second pipe 32 and a plurality of second branch pipes 62 are connected to the second main pipe 52. The third pipe 33 and a plurality of third branch pipes 63 are connected to the third main pipe 53. Multiple branch pipes are connected to the first through third main pipes (headers), forming the first through third headers.

[0029] Figure 2This is a cross-sectional view showing the third main pipe 53 and the third distribution pipe 63. The third distribution pipe 33 is connected to one end of the third main pipe 53. The other end of the third main pipe 53 is sealed. Multiple third distribution pipes 63 are arranged axially along the third main pipe 53 and connected to the middle portion of the third main pipe 53 in the axial direction. The third distribution pipe 63 corresponding to the first indoor unit 10a has the largest axial distance from the third distribution pipe 33. The distal ends of the multiple third distribution pipes 63 protrude into the interior of the third main pipe 53. Figure 1 The first header of the illustrated first trunk pipe 51 and the second header of the second trunk pipe 52 are also configured similarly to the third header of the third trunk pipe 53 .

[0030] The switching unit 40 includes a second on-off valve 42 and a third on-off valve 43 as the on-off valves 42 and 43. The second on-off valve 42 opens and closes the second main pipe 62. The third on-off valve 43 opens and closes the third main pipe 63. Only one of the second main pipe 62 and the third on-off valve 43 is open. When only the second main pipe 62 is open, the second pipe 32 is connected to the indoor heat exchanger 4 via the second main pipe 52. When only the third on-off valve 43 is open, the third pipe 33 is connected to the indoor heat exchanger 4 via the third main pipe 53.

[0031] An external filter 35 and an internal filter 65 are installed inside the switching unit 40. The external filter 35 is installed in the pipes 31, 32, and 33 on the outdoor unit 11 side of the main pipes 51, 52, and 53. The internal filter 65 is installed in the first main pipe 61 and the connecting pipe 67 on the indoor unit 10 side of the main pipes 51, 52, and 53. The external filter 35 and the internal filter 65 capture foreign matter in the refrigerant flowing through the pipes.

[0032] The refrigeration cycle device 1 includes a CPU (Central Processing Unit), memory, and auxiliary storage devices. The CPU functions as a control unit 19 by executing programs stored in the memory and auxiliary storage devices. The control unit 19 controls the operation of each component of the refrigeration cycle device 1. The control unit 19 controls the operation of the four-way valve 18. The control unit 19 controls the operation of the outdoor expansion valve 6b and the indoor expansion valve 6a. The control unit 19 controls the operation of the on-off valves 42 and 43.

[0033] A case where all the indoor units 10 perform cooling operation (individual cooling) will be described.

[0034] The control unit 19 makes all four-way valves 18 Figure 1The downstream side of the compressor 2 is connected to the outdoor heat exchanger 8. The controller 19 opens the third on-off valves 43 corresponding to all indoor units 10 and closes the second on-off valves 42. The indoor heat exchangers 4 of all indoor units 10 are connected to the third pipe 33.

[0035] Compressor 2 compresses the low-pressure gas refrigerant sucked into it into a high-temperature, high-pressure gas refrigerant. Refrigerant discharged from compressor 2 flows through oil separator 2b and check valve 3 into first four-way valve 18a. From first four-way valve 18a, the refrigerant flows into outdoor heat exchanger 8 of outdoor unit 11.

[0036] The outdoor heat exchanger 8 functions as a condenser (radiator) that radiates heat from the high-temperature, high-pressure gas refrigerant flowing from the compressor 2, converting the high-temperature, high-pressure gas refrigerant into a high-pressure liquid refrigerant.

[0037] The refrigerant flowing out of the outdoor heat exchanger 8 passes through the first pipe 31 and flows into the outdoor expansion valve 6b and the indoor expansion valves 6a of all indoor units 10. 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, converting the high-pressure liquid refrigerant into a low-temperature, low-pressure gas-liquid two-phase refrigerant. The refrigerant flowing out of the indoor expansion valve 6a flows into the indoor heat exchanger 4.

[0038] The indoor heat exchanger 4 functions as an evaporator (heat absorber). The evaporator converts the gas-liquid two-phase refrigerant flowing in from the indoor expansion valve 6a into a low-pressure gas refrigerant. The refrigerant flowing out of the indoor heat exchanger 4 in all indoor units 10 flows through the third pipe 33, the accumulator (gas-liquid separator) 2a, and into the compressor 2.

[0039] A case where all the indoor units 10 perform the heating operation (individual heating) will be described.

[0040] The control unit 19 Figure 1 In the illustrated state, all four-way valves 18 are switched. Consequently, the upstream side of compressor 2 is connected to outdoor heat exchanger 8. Second piping 32 is connected to the downstream side of compressor 2. Control unit 19 opens second on-off valves 42 corresponding to all indoor units 10 and closes third on-off valve 43. The indoor heat exchangers 4 of all indoor units 10 are connected to second piping 32.

[0041] The refrigerant discharged from the compressor 2 passes through the second four-way valve 18b and the second pipe 32 and flows into the indoor heat exchangers 4 of all indoor units 10. The indoor heat exchangers 4 function as condensers (radiators). The refrigerant flowing out of the indoor heat exchangers 4 of all indoor units 10 passes through the indoor expansion valve 6a, the first pipe 31, and the outdoor expansion valve 6b and flows into the outdoor heat exchanger 8. The outdoor heat exchanger 8 functions as an evaporator (heat absorber). The refrigerant flowing out of the outdoor heat exchanger 8 passes through the first four-way valve 18a and flows into the compressor 2.

[0042] The following describes a case where the first indoor unit 10a performs heating operation and the other indoor units 10b to 10d perform cooling operation simultaneously. The refrigeration cycle device 1 performs simultaneous cooling and heating operation (simultaneous cooling) with cooling as the main operation.

[0043] The control unit 19 sets the state of the first four-way valve 18a to Figure 1 The downstream side of the compressor 2 is connected to the outdoor heat exchanger 8. The control unit 19 turns the second four-way valve 18b from Figure 1 The second pipe 32 is connected to the downstream side of the compressor 2.

[0044] The controller 19 opens the second on-off valve 42 corresponding to the first indoor unit 10a and closes the third on-off valve 43. The indoor heat exchanger 4 of the first indoor unit 10a is connected to the second pipe 32. The controller 19 opens the third on-off valve 43 corresponding to the other indoor units 10b, 10c, and 10d and closes the second on-off valve 42. The indoor heat exchangers 4 of the other indoor units 10b, 10c, and 10d are connected to the third pipe 33.

[0045] The refrigerant discharged from the compressor 2 flows into the first indoor unit 10a through the second four-way valve 18b and the second pipe 32. The indoor heat exchanger 4 of the first indoor unit 10a functions as a condenser (radiator). The refrigerant flowing out of the indoor heat exchanger 4 flows into the first main pipe 51.

[0046] The refrigerant discharged from the compressor 2 flows through the first four-way valve 18a, the outdoor heat exchanger 8, and the first pipe 31 into the first main pipe 51. The refrigerant in the first main pipe 51 flows into the other indoor units 10b, 10c, and 10d. The indoor heat exchangers 4 in the other indoor units 10b, 10c, and 10d function as evaporators (heat absorbers). The refrigerant flowing out of these indoor heat exchangers 4 flows into the compressor 2 through the third pipe 33.

[0047] The following describes a case where cooling operation of the first indoor unit 10a and heating operation of the other indoor units 10b-10d are performed simultaneously among the plurality of indoor units 10. The refrigeration cycle device 1 performs simultaneous cooling and heating operation (simultaneous heating) with heating as the main mode.

[0048] The control unit 19 Figure 1 The state shown in FIG. 1 makes the first four-way valve 18a switch state. The upstream side of the compressor 2 is connected to the outdoor heat exchanger 8. The control unit 19 makes the second four-way valve 18b Figure 1 The status shown.

[0049] The controller 19 opens the third on-off valve 43 corresponding to the first indoor unit 10a and closes the second on-off valve 42. The indoor heat exchanger 4 of the first indoor unit 10a is connected to the third pipe 33. The controller 19 opens the second on-off valve 42 corresponding to the other indoor units 10b, 10c, and 10d and closes the third on-off valve 43. The indoor heat exchangers 4 of the other indoor units 10b, 10c, and 10d are connected to the second pipe 32.

[0050] The refrigerant discharged from the compressor 2 passes through the second four-way valve 18b and the second pipe 32 and flows into the other indoor units 10b, 10c, and 10d. The indoor heat exchangers 4 in the other indoor units 10b, 10c, and 10d function as condensers (radiators). The refrigerant flowing out of these indoor heat exchangers 4 flows into the first dry pipe 51. A portion of the refrigerant in the first dry pipe 51 flows through the first pipe 31 and the outdoor heat exchanger 8 and flows into the compressor 2.

[0051] The remaining portion of the refrigerant in the first main pipe 51 flows into the first indoor unit 10a. The indoor heat exchanger 4 of the first indoor unit 10a functions as an evaporator (heat absorber). The refrigerant flowing out of the indoor heat exchanger 4 flows into the compressor 2 through the third pipe 33.

[0052] Abnormal noise generated during the cooling operation of the indoor unit 10 will be described.

[0053] When the indoor unit 10 is in cooling operation, the indoor heat exchanger 4 functions as an evaporator (heat absorber). The indoor heat exchanger 4 converts the gas-liquid two-phase refrigerant into a low-pressure gas refrigerant. When the indoor unit 10 is in cooling operation, the third on-off valve 43 is open and the second on-off valve 42 is closed. The indoor heat exchanger 4 is connected to the third pipe 33. The refrigerant flowing out of the indoor heat exchanger 4 flows into the compressor 2 through the connecting pipe 67, the third branch pipe 63, the third main pipe 53, and the third pipe 33.

[0054] Gas-liquid two-phase refrigerant sometimes flows out of the indoor heat exchanger 4. If liquid refrigerant contained in the gas-liquid two-phase refrigerant flows into the compressor 2, the compressor 2 may malfunction. The control unit 19 sets a target value for the superheat of the refrigerant flowing out of the indoor heat exchanger 4. The control unit 19 controls the opening of the indoor expansion valve 6a so that the superheat exceeds the target value. When the superheat exceeds the target value, the outflow of liquid refrigerant from the indoor heat exchanger 4 is suppressed.

[0055] When the operation of the indoor unit 10 starts or stops, or when the speed of the compressor 2 changes, there is a situation where the superheat is lower than the target value. In this case, the gas-liquid two-phase refrigerant containing liquid refrigerant flows out of the indoor heat exchanger 4. In the process of the liquid refrigerant circulating in the connecting pipe 67, the third branch pipe 63, the third dry pipe 53 and the third pipe 33, an abnormal sound is generated. The abnormal sound is an irritating sound of about 4 to 7 Hz. The abnormal sound is generated in the inner filter 65 provided in the connecting pipe 67, the third on-off valve 43 provided in the third branch pipe 63, the inside of the third dry pipe 53, or the outer filter 35 provided in the third pipe 33. As Figure 2 As shown, the tip of the third branch pipe 63 protrudes into the third dry pipe 53. When the liquid refrigerant flows through the third dry pipe 53, if a vortex is generated at the tip of the third branch pipe 63, the risk of abnormal noise generation increases.

[0056] When specified conditions are met, the control unit 19 performs a refrigerant flow control operation for the indoor unit 10 performing cooling operation. As a refrigerant flow control operation, the control unit 19 sets the upper limit opening (upper limit value of the opening) of the indoor expansion valve 6a of the indoor unit 10 performing cooling operation. The upper limit opening is a constant value predetermined by the refrigeration cycle device 1. The upper limit opening is the opening of the indoor expansion valve 6a when the superheat is greater than the target value when the indoor unit 10 is operating under cooling rated conditions. For example, if the indoor expansion valve 6a has an opening control range of 0 to 500 pls, the upper limit opening is set to 150 pls.

[0057] The control unit 19 controls the opening of the indoor expansion valve 6a to below the upper limit. The flow rate of the refrigerant flowing through the indoor heat exchanger 4 is restricted. Since heat exchange in the indoor heat exchanger 4 is performed on a small amount of refrigerant, the refrigerant temperature tends to rise. The superheat of the refrigerant flowing out of the indoor heat exchanger 4 exceeds the target value. The outflow of liquid refrigerant from the indoor heat exchanger 4 is suppressed. The generation of abnormal noise associated with the circulation of liquid refrigerant is suppressed.

[0058] The upper limit opening degree is a value corresponding to at least one of the capacity information and the configuration information of the indoor unit 10. Generally, the refrigerant circulation rate varies depending on the capacity and configuration of the indoor unit 10. The upper limit opening degree is set to achieve a balance between achieving the performance of the indoor unit 10 and suppressing abnormal noise.

[0059] The greater the capacity of the indoor unit 10, the larger the upper limit opening is set. The smaller the capacity of the indoor unit 10, the smaller the upper limit opening is set. The capacity of the indoor unit 10 is expressed in horsepower (HP). For example, if the capacity of the indoor unit 10 is 6HP, the upper limit opening is set to 200pls. If the capacity of the indoor unit 10 is 1HP, the upper limit opening is set to 100pls.

[0060] The heat exchange capacity of the indoor heat exchanger 4 varies depending on the type of indoor unit 10. The greater the heat exchange capacity of the indoor heat exchanger 4, the larger the upper limit opening is set. The smaller the heat exchange capacity of the indoor heat exchanger 4, the smaller the upper limit opening is set. For example, if the indoor unit 10 is a ceiling box-type, four-way airflow type, the heat exchange capacity of the indoor heat exchanger 4 is large, so the upper limit opening is set to 170 pls. If the indoor unit 10 is a duct-type type, the heat exchange capacity of the indoor heat exchanger 4 is small, so the upper limit opening is set to 130 pls.

[0061] As described above, the control unit 19 sets the upper limit opening degree of the indoor expansion valve 6a when predetermined conditions are satisfied.

[0062] One of the prescribed conditions is inputting an instruction to set the upper limit opening degree to the control unit 19. Upon hearing an abnormal noise, the operator of the refrigeration cycle apparatus 1 (maintenance operator, user, etc.) inputs an instruction to set the upper limit opening degree. The operator inputs the instruction to set the upper limit opening degree from the control board of the outdoor unit 11 or the remote control device (remote control) of the indoor unit 10. Upon receiving the instruction to set the upper limit opening degree, the control unit 19 sets the upper limit opening degree of the indoor expansion valve 6a. This suppresses the occurrence of abnormal noise during cooling operation of the indoor unit 10.

[0063] One of the prescribed conditions is that a prescribed time has not elapsed since the indoor unit 10 started cooling operation. While the indoor unit 10 is stopped, the refrigerant temperature drops, causing liquid refrigerant to remain in the indoor unit 10. When the indoor unit 10 starts operating, this retained liquid refrigerant circulates, potentially causing abnormal noise. The control unit 19 sets the upper limit of the opening of the indoor expansion valve 6a until the prescribed time has elapsed from the start of cooling operation in the indoor unit 10. This suppresses the occurrence of abnormal noise when the indoor unit 10 starts cooling operation.

[0064] The first upper limit opening degree set at the start of cooling operation of the indoor unit is the same as the second upper limit opening degree set based on the operator's instruction. The first upper limit opening degree may be smaller than the second upper limit opening degree. The generation of abnormal noise is effectively suppressed.

[0065] The predetermined time for setting the first upper limit opening degree is predetermined according to the magnitude of the first upper limit opening degree. The predetermined time is a time sufficient for the retained liquid refrigerant to vaporize.

[0066] The timing at which the control unit 19 starts setting the first upper limit opening degree may be the time at which the compressor 2 starts operating, instead of the time at which the indoor unit 10 starts the cooling operation.

[0067] like Figure 2 As shown, the switching unit 40 includes a third main pipe 53. The third pipe 33 and third branch pipes 63 corresponding to the plurality of indoor units 10 are connected to the third main pipe 53. The first indoor unit 10a is the indoor unit 10 corresponding to the third branch pipe 63 that is the greatest distance from the third pipe 33 along the axial direction of the third main pipe 53. When predetermined conditions are met, the control unit 19 sets the upper limit opening of the indoor expansion valve 6a of the first indoor unit 10a, which is performing cooling operation.

[0068] The third control pipe 63 corresponding to the first indoor unit 10a is referred to as the "end third control pipe 63," and the third control pipes 63 corresponding to the other indoor units 10b, 10c, and 10d are referred to as "other third control pipes 63." When the first indoor unit 10a is in cooling operation, refrigerant flows from the end third control pipe 63 into the third main pipe 53. Within the third main pipe 53, the tips of the other third control pipes 63 protrude between the end third control pipe 63 and the third pipe 33. Liquid refrigerant flowing from the end third control pipe 63 into the third main pipe 53 passes through the tips of all other third control pipes 63. If vortexes are generated at the tips of the other third control pipes 63, the risk of abnormal noise increases. Liquid refrigerant flowing from the end third control pipe 63 into the third main pipe 53 is more likely to pass through the tips of the third control pipes 63 than refrigerant flowing from the other third control pipes 63. When the first indoor unit 10a performs cooling operation, the risk of abnormal noise generation is higher than when the other indoor units 10b, 10c, and 10d perform cooling operation.

[0069] The controller 19 sets the upper limit opening of the indoor expansion valve 6a at least when the first indoor unit 10a is performing cooling operation. This suppresses the flow of liquid refrigerant from the third branch pipe 63 at the end into the third main pipe 53. This effectively suppresses the generation of abnormal noise. Preferably, the controller 19 also sets the upper limit opening of the indoor expansion valve 6a when the other indoor units 10b, 10c, and 10d are performing cooling operation. This effectively suppresses the generation of abnormal noise.

[0070] As described above in detail, the refrigeration cycle device 1 of the embodiment includes an outdoor unit 11, multiple indoor units 10, a first pipe 31, a second pipe 32, a third pipe 33, a switching unit 40, and a controller 19. The outdoor unit 11 includes a compressor 2 and an outdoor heat exchanger 8. The multiple indoor units 10 include indoor expansion valves 6a and indoor heat exchangers 4. The first pipe 31 circulates refrigerant between the outdoor heat exchanger 8 and the indoor heat exchanger 4. The second pipe 32 allows refrigerant discharged from the compressor 2 to flow into the indoor heat exchanger 4. The third pipe 33 allows refrigerant flowing out of the indoor heat exchanger 4 to flow into the compressor 2. The switching unit 40 switches the connection between the second pipe 32 and the third pipe 33 with respect to the indoor heat exchanger 4. When the switching unit 40 connects the indoor heat exchanger 4 to the third pipe 33, the controller 19 sets the upper limit opening of the indoor expansion valve 6a if predetermined conditions are satisfied.

[0071] By setting the upper limit of the opening of the indoor expansion valve 6a, the flow rate of the refrigerant flowing through the indoor heat exchanger 4 is limited. Since a small amount of refrigerant undergoes heat exchange in the indoor heat exchanger 4, the refrigerant temperature tends to rise. The superheat of the refrigerant flowing out of the indoor heat exchanger 4 exceeds the target value. This prevents the outflow of liquid refrigerant from the indoor heat exchanger 4. This also suppresses the generation of abnormal noise associated with the circulation of liquid refrigerant.

[0072] According to at least one embodiment described above, the control unit 19 is provided to set the upper limit opening of the indoor expansion valve 6a of the indoor unit 10 performing cooling operation. This can suppress the generation of abnormal noise.

[0073] While several embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments may be implemented in various other ways, and various omissions, substitutions, and modifications may be made without departing from the gist of the invention. These embodiments and their variations are included within the scope and gist of the invention, and are also included within the invention described in the claims and their equivalents.

[0074] Description of Reference Numerals

[0075] 1…Refrigeration cycle device, 2…Compressor, 4…Indoor heat exchanger, 6a…Indoor expansion valve, 8…Outdoor heat exchanger, 10…Indoor unit, 10a…First indoor unit, 11…Outdoor unit, 19…Control unit, 31…First pipe, 32…Second pipe, 33…Third pipe, 40…Switching unit, 53…Third main pipe (main pipe), 63…Third branch pipe (branch pipe).

Claims

1. A refrigeration cycle device comprising: an outdoor unit including a compressor and an outdoor heat exchanger; a plurality of indoor units including indoor expansion valves and indoor heat exchangers; a first pipe for circulating refrigerant between the outdoor heat exchanger and the indoor heat exchanger; a second pipe for allowing the refrigerant discharged from the compressor to flow into the indoor heat exchanger; a third pipe for allowing the refrigerant flowing out of the indoor heat exchanger to flow into the compressor; a switching unit for switching connections of the second pipe and the third pipe to the indoor heat exchanger; as well as The control unit sets an upper limit opening degree of the indoor expansion valve when a predetermined condition is satisfied in a state in which the indoor heat exchanger is connected to the third pipe in the switching unit.

2. The refrigeration cycle device according to claim 1, wherein The upper limit opening degree is a value corresponding to at least one of capability information and form information of the indoor unit.

3. The refrigeration cycle device according to claim 1 or 2, wherein: The predetermined condition is a condition for inputting a setting instruction of the upper limit opening degree into the control unit.

4. The refrigeration cycle device according to claim 1 or 2, wherein: The predetermined condition is a condition that a predetermined time has not elapsed since the indoor unit started cooling operation.

5. The refrigeration cycle device according to claim 1 or 2, wherein: The refrigeration cycle device further includes main pipes corresponding to the plurality of indoor units and a trunk pipe connected to the third pipe. When the indoor unit corresponding to the main pipe that is the longest in the axial direction of the main pipe from the third pipe is set as the first indoor unit, In a state in which the indoor heat exchanger of the first indoor unit is connected to the third pipe in the switching unit, when the predetermined condition is satisfied, the control unit sets the upper limit opening degree of the indoor expansion valve of the first indoor unit.

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