Heat source unit and refrigeration cycle device

Abstract

A heat source unit (10) is provided with a compressor (11), a first heat source heat exchanger (13a), a second heat source heat exchanger (13b), a first fan, a second fan, and a control unit. The first fan primarily passes air through the first heat source heat exchanger. The second fan primarily passes air through the second heat source heat exchanger. The control unit continues the operation of the compressor and controls the first fan and the second fan during the defrosting operation such that the rotational speed of the first fan and the rotational speed of the second fan are different. In the defrosting operation, a first defrosting mode for removing frost from the first heat source heat exchanger and a second defrosting mode for removing frost from the second heat source heat exchanger are switched.

Description

Technical Field

[0001] The present disclosure relates to a heat source unit and a refrigeration cycle device. Background Art

[0002] Patent Document 1 (Japanese Patent Application Laid-Open No. 5-346270) discloses that a subcooling coil is provided at the bottommost stage of each outdoor heat exchanger in a stack of outdoor heat exchangers. Summary of the Invention

[0003] However, the present inventors have focused on the following technical problem: in Patent Document 1, the performance of the defrosting operation may be reduced due to the operation of two outdoor fans that blow air to the respective outdoor heat exchangers.

[0004] A heat source unit according to a first aspect includes a compressor, a first heat source heat exchanger, a second heat source heat exchanger, a first fan, a second fan, and a control unit. The first fan primarily passes air through the first heat source heat exchanger. The second fan primarily passes air through the second heat source heat exchanger. The control unit continues operation of the compressor and controls the first and second fans during a defrost operation, switching between a first defrost mode for removing frost from the first heat source heat exchanger and a second defrost mode for removing frost from the second heat source heat exchanger, such that the rotational speeds of the first fan and the second fan differ.

[0005] According to the heat source unit of the first aspect, in the first defrost mode, it is possible to simultaneously perform defrosting by using the first heat source heat exchanger as the condenser of the refrigerant and perform heating operation by using the second heat source heat exchanger as the evaporator of the refrigerant. Furthermore, in the second defrost mode, it is possible to simultaneously perform defrosting by using the second heat source heat exchanger as the condenser of the refrigerant and perform heating operation by using the first heat source heat exchanger as the evaporator of the refrigerant. Furthermore, by controlling the rotational speeds of the first fan and the second fan to be different, it is possible to vary the amount of air passing through the heat exchanger serving as the condenser for the defrost operation and the amount of air passing through the heat exchanger serving as the evaporator for the heating operation. Therefore, it is possible to reduce the effect of air passing through the heat exchanger serving as the evaporator on the heat exchanger serving as the condenser. Therefore, it is possible to suppress a decrease in the ability to perform defrost operation while performing heating operation.

[0006] The heat source unit of the second aspect is based on the heat source unit of the first aspect. In the first defrost mode, the control unit condenses the refrigerant in the first heat source heat exchanger, evaporates the refrigerant in the second heat source heat exchanger, and makes the rotation speed of the first fan lower than the rotation speed of the second fan.

[0007] In the heat source unit of the second aspect, the rotational speed of the first fan that delivers air to the first heat source heat exchanger, which functions as a condenser during defrosting operation, is set to be lower than the rotational speed of the second fan that delivers air through the second heat source heat exchanger, which functions as an evaporator during heating operation. Therefore, during the defrosting operation of the first heat source heat exchanger, the influence of ventilation by the second fan can be reduced, thereby further suppressing a decrease in the defrosting performance.

[0008] A heat source unit according to a third aspect is the heat source unit according to the second aspect, wherein the control unit stops the first fan in the first defrosting mode.

[0009] In the heat source unit of the third aspect, the first fan that sends air to the first heat source heat exchanger used as a condenser for the defrosting operation is stopped. Therefore, it is possible to more effectively suppress a decrease in the defrosting performance of the first heat source heat exchanger.

[0010] The heat source unit of the fourth viewpoint is based on the heat source unit of any one of the first viewpoints to the third viewpoints, and the control unit condenses the refrigerant in the first heat source heat exchanger and evaporates the refrigerant in the second heat source heat exchanger in the first defrost mode, and makes the upper limit speed of the second fan lower than the upper limit speed during normal operation.

[0011] In the heat source unit according to the fourth aspect, the rotational speed of the second fan supplying air through the second heat source heat exchanger, which serves as an evaporator during heating operation, is lower than the upper limit rotational speed during normal operation. Therefore, during the defrost operation of the first heat source heat exchanger, the air volume passed through the second heat source heat exchanger by the second fan is lower than the maximum air volume during normal operation. Therefore, during the defrost operation of the first heat source heat exchanger, the influence of ventilation caused by the second fan can be reduced, thereby further suppressing a decrease in the performance of the defrost operation.

[0012] A refrigeration cycle apparatus according to a fifth aspect includes the heat source unit according to any one of the first to fourth aspects and a utilization unit. The utilization unit is connected to the heat source unit.

[0013] According to the refrigeration cycle apparatus of the fifth aspect, since it includes the heat source unit according to any one of the first to fourth aspects, it is possible to realize a refrigeration cycle apparatus that can suppress a decrease in the performance of the defrosting operation while performing the heating operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic configuration diagram of a refrigeration cycle device according to one embodiment of the present disclosure.

[0015] Figure 2 This is a control block diagram of a refrigeration cycle device.

[0016] Figure 3It is a schematic diagram of a heat source heat exchanger and a heat source fan.

[0017] Figure 4 It is a diagram showing the operation (flow of refrigerant) of the refrigeration cycle apparatus during cooling operation.

[0018] Figure 5 It is a diagram showing the operation (flow of refrigerant) of the refrigeration cycle device during heating operation.

[0019] Figure 6 This is a diagram showing a control flow during the defrosting operation of the refrigeration cycle apparatus.

[0020] Figure 7 It is a diagram showing the operation (flow of refrigerant) in the first defrosting mode of the refrigeration cycle device.

[0021] Figure 8 It is a diagram showing the operation (flow of refrigerant) in the second defrosting mode of the refrigeration cycle apparatus.

[0022] Figure 9 It is a schematic structural diagram of a refrigeration cycle apparatus according to a modified example.

[0023] Figure 10 This is a schematic structural diagram of a refrigeration cycle device according to another modified example.

[0024] Explanation of symbols

[0025] 1. Refrigeration cycle device;

[0026] 4. Heat source control unit (control unit);

[0027] 10 heat source units;

[0028] 13a first heat source heat exchanger;

[0029] 13b second heat source heat exchanger;

[0030] 14a first heat source fan (first fan);

[0031] 14b second heat source fan (second fan);

[0032] 20 utilization units. DETAILED DESCRIPTION

[0033] (1) Overall structure

[0034] Figure 1The refrigeration cycle device 1 of one embodiment of the present disclosure is an air conditioning device that uses a vapor compression refrigeration cycle to perform indoor air conditioning in buildings such as residences and buildings. The refrigeration cycle device 1 mainly includes a heat source unit 10, a utilization unit 20, a first communication pipe 31, a second communication pipe 32, a third communication pipe 33, and a control unit 6. The first communication pipe 31, the second communication pipe 32, and the third communication pipe 33 connect the heat source unit 10 and the utilization unit 20. Figure 2 As shown, the control unit 6 includes a heat source control unit 4 and a utilization control unit 5 , and controls components of the heat source unit 10 and the utilization unit 20 .

[0035] The refrigeration cycle device 1 includes a refrigerant circuit 2 and a subcooling circuit 3. The refrigerant circuit 2 is formed by connecting a heat source unit 10, a utilization unit 20, and communication pipes 31, 32, and 33. The subcooling circuit 3 is formed by connecting a subcooling heat exchanger 16 and a third heat source expansion mechanism 15c. The refrigerant circuit 2 and the subcooling circuit 3 are filled with a refrigerant such as R410.

[0036] (2) Detailed structure

[0037] (2-1) Heat source unit

[0038] The heat source unit 10 is installed outdoors (on the roof of a building, near the outer wall of a building, etc.). The heat source unit 10 mainly includes a compressor 11, a first switching mechanism 12a, a second switching valve mechanism 12b, a third switching mechanism 12c, a fourth switching mechanism 12d, a first heat source heat exchanger 13a, a second heat source heat exchanger 13b, a first heat source fan 14a, a second heat source fan 14b, a first heat source expansion valve mechanism 15a, a second heat source expansion mechanism 15b, a third heat source expansion mechanism 15c, a subcooling heat exchanger 16, an accumulator 17, a first stop valve 18a, a second stop valve 18b, and a third stop valve 18c. The compressor 11, the switching mechanisms 12a to 12d, the heat source heat exchangers 13a and 13b, the heat source expansion valve mechanisms 15a to 15c, the subcooling heat exchanger 16, the accumulator 17, and the first to third stop valves 18a to 18c are connected by refrigerant piping.

[0039] The compressor 11, the switching mechanism 12a~12d, the heat source heat exchanger 13a, 13b, the heat source expansion valve mechanism 15a, 15b, 15c, the first flow path 16a of the subcooling heat exchanger 16, the storage tank 17, the first to third stop valves 18a~18c are connected to the utilization unit 20 via the first connecting pipe 31, the second connecting pipe 32 and the third connecting pipe 33, and constitute a part of the refrigerant circuit 2.

[0040] In addition, the second flow path 16b of the subcooling heat exchanger 16 and the third heat source expansion mechanism 15c constitute a part of the subcooling circuit 3. The subcooling circuit 3 is a circuit for diverting a part of the refrigerant of the refrigerant circuit 2 and delivering it to the suction side of the compressor 11. The subcooling circuit 3 connects the first heat source heat exchanger 13a and the second heat source heat exchanger 13b and the subcooling heat exchanger 16 with the suction side of the compressor 11. Here, the subcooling circuit 3 connects the refrigerant piping between the first heat source expansion mechanism 15a and the second heat source expansion mechanism 15b and the subcooling heat exchanger 16 with the inlet side of the storage tank 17.

[0041] Compressor 11 compresses the low-pressure refrigerant in the refrigeration cycle to a high-pressure state. Here, a closed-type compressor, in which a positive displacement compression element (not shown), such as a rotary or scroll type, is driven by a compressor motor, is used as compressor 11. Furthermore, the speed (frequency) of the compressor motor can be controlled by an inverter, etc., thereby controlling the capacity of compressor 11.

[0042] The switching mechanisms 12a, 12b, 12c, and 12d are valves that switch the flow direction of the refrigerant in the refrigerant circuit. In this embodiment, the switching mechanisms 12a, 12b, 12c, and 12d use four-way reversing valves, and one port is closed.

[0043] The first switching mechanism 12a is a device capable of switching the flow of refrigerant in the refrigerant circuit 2, so as to connect the discharge side of the compressor 11 with the gas side of the first heat source heat exchanger 13a when the first heat source heat exchanger 13a acts as a condenser of the refrigerant, and to connect the suction side of the compressor 11 with the gas side of the first heat source heat exchanger 13a when the first heat source heat exchanger 13a acts as an evaporator of the refrigerant.

[0044] The second switching mechanism 12b is a device capable of switching the flow of refrigerant in the refrigerant circuit 2, so as to connect the discharge side of the compressor 11 with the gas side of the second heat source heat exchanger 13b when the second heat source heat exchanger 13b acts as a condenser of the refrigerant, and to connect the suction side of the compressor 11 with the gas side of the second heat source heat exchanger 13b when the second heat source heat exchanger 13b acts as an evaporator of the refrigerant.

[0045] The third switching mechanism 12c is a device capable of switching the flow of refrigerant in the refrigerant circuit 2, so as to connect the discharge side of the compressor 11 to the second connecting pipe 32 when the refrigerant discharged from the compressor 11 is delivered to the second connecting pipe 32, and to connect the suction side of the compressor 11 to the second connecting pipe 32 when the refrigerant flowing in the second connecting pipe 32 is delivered to the suction side of the compressor 11.

[0046] The fourth switching mechanism 12d is a device capable of switching the flow of refrigerant in the refrigerant circuit 2, so as to connect the discharge side of the compressor 11 to the third connecting pipe 33 when the refrigerant discharged from the compressor 11 is delivered to the third connecting pipe 33, and to connect the suction side of the compressor 11 to the third connecting pipe 33 when the refrigerant flowing in the third connecting pipe 33 is delivered to the suction side of the compressor 11.

[0047] In addition, the switching mechanisms 12a, 12b, 12c, and 12d are not limited to mechanisms composed of four-way reversing valves. For example, they can also be mechanisms that switch the flow direction of the refrigerant as above by combining multiple solenoid valves and refrigerant pipes, or by using multiple solenoid valves and a four-way reversing valve.

[0048] The first heat source heat exchanger 13a and the second heat source heat exchanger 13b perform heat exchange between the refrigerant and the outdoor air. The first heat source heat exchanger 13a and the second heat source heat exchanger 13b are heat exchangers that function as refrigerant condensers or as refrigerant evaporators.

[0049] The first heat source heat exchanger 13a and the second heat source heat exchanger 13b are connected in parallel to each other. The first heat source heat exchanger 13a and the second heat source heat exchanger 13b are arranged close to each other. Preferably, at least a portion of the first heat source heat exchanger 13a and the second heat source heat exchanger 13b are in contact with each other. In this embodiment, Figure 3 As shown, the second heat source heat exchanger 13b is arranged below the first heat source heat exchanger 13a. Here, the second heat source heat exchanger 13b is arranged vertically below the first heat source heat exchanger 13a, and the bottom surface of the first heat source heat exchanger 13a contacts the top surface of the second heat source heat exchanger 13b.

[0050] The first heat source fan 14a primarily passes air through the first heat source heat exchanger 13a. Specifically, the first heat source fan 14a draws outdoor air into the heat source unit 10, supplies the outdoor air primarily to the first heat source heat exchanger 13a, and then exhausts the air outside the heat source unit 10. Therefore, the first heat source heat exchanger 13a acts as a cooling source or a heating source for the outdoor air, condensing or evaporating the refrigerant.

[0051] In addition, the first heat source fan 14a supplies more air to the first heat source heat exchanger 13a than to the second heat source heat exchanger 13b. Therefore, the first heat source fan 14a includes a case where air is supplied only to the first heat source heat exchanger 13a and a case where air is supplied to both the first heat source heat exchanger 13a and the second heat source heat exchanger 13b.

[0052] The second heat source fan 14b primarily passes air through the second heat source heat exchanger 13b. Specifically, the second heat source fan 14b draws outdoor air into the heat source unit 10, supplies the outdoor air primarily to the second heat source heat exchanger 13b, and then exhausts the air outside the heat source unit 10. Therefore, the second heat source heat exchanger 13b acts as a cooling source or a heating source for the outdoor air, condensing or evaporating the refrigerant.

[0053] In addition, the second heat source fan 14b supplies more air to the second heat source heat exchanger 13b than to the first heat source heat exchanger 13a. Therefore, the second heat source fan 14b includes a case where air is supplied only to the second heat source heat exchanger 13b and a case where air is supplied to both the first heat source heat exchanger 13a and the second heat source heat exchanger 13b.

[0054] The first heat source fan 14a and the second heat source fan 14b of the present embodiment are driven by motors controlled by inverters, and are configured to be able to change the air blowing volumes.

[0055] The second heat source fan 14b is arranged below the first heat source fan 14a. Here, the second heat source fan 14b is arranged in parallel on the vertically lower side of the first heat source fan 14a.

[0056] The opening degrees of the first, second, and third heat source expansion mechanisms 15a, 15b, and 15c are variable. By adjusting the opening degrees of the first, second, and third heat source expansion mechanisms 15a, 15b, and 15c, the degree of pressure reduction can be adjusted.

[0057] Specifically, the first heat source expansion mechanism 15a is an electric expansion valve with adjustable opening, and adjusts the flow rate of the refrigerant flowing through the first heat source heat exchanger 13a. The first heat source expansion mechanism 15a is provided corresponding to the liquid side of the first heat source heat exchanger 13a.

[0058] The second heat source expansion mechanism 15b is an electric expansion valve with adjustable opening, and adjusts the flow rate of the refrigerant flowing through the second heat source heat exchanger 13b, etc. The second heat source expansion mechanism 15b is provided corresponding to the liquid side of the second heat source heat exchanger 13b.

[0059] The third heat source expansion mechanism 15c is an electrically operated expansion valve with adjustable opening, and performs functions such as adjusting the flow rate of the refrigerant flowing through the second flow path 16b of the subcooling heat exchanger 16. The third heat source expansion mechanism 15c is disposed between the refrigerant piping and the accumulator 17. The refrigerant piping is located between the first and second heat source expansion mechanisms 15a, 15b, and the subcooling heat exchanger 16.

[0060] The subcooling heat exchanger 16 is arranged between the first heat source heat exchanger 13a and the second heat source heat exchanger 13b and the first stop valve 18a. The subcooling heat exchanger 16 has a first flow path 16a and a second flow path 16b. The first flow path 16a is connected to the utilization unit 20. Here, the first flow path 16a constitutes a part of the refrigerant piping that connects the first heat source expansion mechanism 15a, the second heat source expansion mechanism 15b and the first stop valve 18a. The second flow path 16b is for the refrigerant that exchanges heat with the refrigerant in the first flow path 16a to flow through. Here, the second flow path 16b constitutes a part of the subcooling circuit 3. The subcooling heat exchanger 16 is a heat exchanger that cools the refrigerant flowing in the first flow path 16a by the refrigerant flowing in the second flow path 16b.

[0061] The accumulator 17 is provided on the suction side of the compressor 11. The accumulator 17 temporarily stores the refrigerant to be sucked into the compressor 11. In other words, the accumulator 17 stores excess refrigerant.

[0062] The first stop valve 18a is provided at the connection between the heat source unit 10 and the first communication pipe 31. The second stop valve 18b is provided at the connection between the heat source unit 10 and the second communication pipe 32. The third stop valve 18c is provided at the connection between the heat source unit 10 and the third communication pipe 33. The first stop valve 18a, the second stop valve 18b, and the third stop valve 18c are valves that are manually opened and closed.

[0063] In addition, various sensors are provided in the heat source unit 10. Specifically, Figure 2 As shown, the heat source unit 10 is provided with an outdoor temperature sensor 41 for detecting the outside air temperature, a suction pressure sensor 42 for detecting the suction pressure of the compressor 11 , a discharge pressure sensor 43 for detecting the discharge pressure of the compressor 11 , and the like.

[0064] (2-2) Connecting pipes

[0065] The connecting pipes 31, 32, and 33 are refrigerant pipes installed on-site when the refrigeration cycle apparatus 1 is installed in a building or other installation location. The first connecting pipe 31 connects the first stop valve 18a to the utilization unit 20. The first connecting pipe 31 is a pipe for liquid refrigerant to pass through. The second connecting pipe 32 connects the utilization unit 20 to the second stop valve 18b. The second connecting pipe 32 is a pipe for gaseous refrigerant to pass through. The third connecting pipe 33 connects the utilization unit 20 to the third stop valve 18c. The third connecting pipe 33 is a pipe for gaseous refrigerant to pass through.

[0066] (2-3) Utilization Unit

[0067] The usage unit 20 is installed indoors (inside a building) and is connected to the heat source unit 10 via the first communication pipe 31 , the second communication pipe 32 , and the third communication pipe 33 as described above, and constitutes a part of the refrigerant circuit 2 .

[0068] The utilization unit 20 mainly includes a first utilization expansion mechanism 21a, a second utilization expansion valve mechanism 21b, a first utilization heat exchanger 22a, a second utilization heat exchanger 22b, a first utilization fan 23a, and a second utilization fan 23b. The utilization expansion mechanisms 21 and 21b are connected to the utilization heat exchangers 22a and 22b via refrigerant piping.

[0069] The first utilization expansion mechanism 21a is connected in series with the first utilization heat exchanger 22a. The second utilization expansion mechanism 21b is directly connected with the second utilization heat exchanger 22b. The first utilization heat exchanger 22a and the second utilization heat exchanger 22b are connected in parallel with each other.

[0070] The opening degrees of the first expansion mechanism 21a and the second expansion mechanism 21b can be changed. By adjusting the opening degrees of the first expansion mechanism 21a and the second expansion mechanism 21b, the degree of pressure reduction can be adjusted.

[0071] Specifically, the first utilization expansion mechanism 21a is an electric expansion valve with adjustable opening, and adjusts the flow rate of the refrigerant flowing through the first utilization heat exchanger 22a, etc. The first utilization expansion mechanism 21a is provided corresponding to the liquid side of the first utilization heat exchanger 22a.

[0072] The second utilization expansion mechanism 21b is an electric expansion valve with adjustable opening, and adjusts the flow rate of the refrigerant flowing through the second utilization heat exchanger 22b, etc. The second utilization expansion mechanism 21b is provided corresponding to the liquid side of the second utilization heat exchanger 22b.

[0073] The first heat exchanger 22a and the second heat exchanger 22b perform heat exchange between the refrigerant and the indoor air. The first heat exchanger 22a and the second heat exchanger 22b are heat exchangers that function as condensers of the refrigerant or as evaporators of the refrigerant.

[0074] The first utilization fan 23a primarily passes air through the first utilization heat exchanger 22a. Specifically, the first utilization fan 23a draws indoor air into the utilization unit 20, supplies the indoor air primarily to the first utilization heat exchanger 22a, and then exhausts the indoor air outside the utilization unit 20. Thus, the first utilization heat exchanger 22a serves as a cooling or heating source for the indoor air, condensing or evaporating the refrigerant.

[0075] The second utilization fan 23b primarily passes air through the second utilization heat exchanger 22b. Specifically, the second utilization fan 23b draws indoor air into the utilization unit 20, supplies the indoor air primarily to the second utilization heat exchanger 22b, and then exhausts the indoor air outside the utilization unit 20. Therefore, the second utilization heat exchanger 22b serves as a cooling or heating source for the indoor air, condensing or evaporating the refrigerant.

[0076] Alternatively, a single fan may be used to pass air through the first utilization heat exchanger 22a and the second utilization heat exchanger 22b.

[0077] In addition, various sensors are provided in the utilization unit 20. Specifically, Figure 2 As shown, the usage unit 20 is provided with an indoor temperature sensor 44 and the like for detecting the temperature of the indoor air sucked into the usage unit 20 .

[0078] (2-4) Control Unit

[0079] (2-4-1) Overview

[0080] like Figure 1 As shown, the refrigeration cycle apparatus 1 includes a heat source control unit 4 and a utilization control unit 5 connected via a transmission line and a communication line, and a control unit 6 is provided to control the operation of the components. The heat source control unit 4 is provided in the heat source unit 10. The utilization control unit 5 is provided in the utilization unit 20. The heat source control unit 4 and the utilization control unit 5 can be connected by wire or wirelessly via a transmission line and a communication line.

[0081] The heat source control unit 4 and the utilization control unit 5, which constitute the control unit 6 of the refrigeration cycle device 1, are implemented by a computer. The controller 6 includes a control operation device and a storage device. The control operation device can use a processor such as a CPU or a GPU. The control operation device reads a program stored in the storage device and performs predetermined image processing or operation processing in accordance with the program. In addition, the control operation device can write operation results to the storage device according to the program and can read information stored in the storage device according to the program.

[0082] like Figure 2 As shown, the heat source control unit 4 is configured to receive detection signals from an outdoor temperature sensor 41, a suction pressure sensor 42, a discharge pressure sensor 43, and the like. Furthermore, the heat source control unit 4 controls the operation of components of the heat source unit 10, such as the compressor 11, the first switching mechanism 12a, the second switching mechanism 12b, the third switching mechanism 12c, the fourth switching mechanism 12d, the first heat source fan 14a, the second heat source fan 14b, the first heat source expansion valve mechanism 15a, the second heat source expansion mechanism 15b, and the third heat source expansion mechanism 15c.

[0083] The utilization control unit 5 is configured to receive detection signals from an indoor temperature sensor, etc. Furthermore, the utilization control unit 5 controls the operation of the first utilization expansion mechanism 21 a , the second utilization expansion mechanism 21 b , the first utilization fan 23 a , the second utilization fan 23 b , etc., which are components provided in the utilization unit 20 .

[0084] As described above, the refrigeration cycle apparatus 1 includes a control unit 6 that performs operational control of the component devices. Furthermore, the control unit 6 is configured to control the component devices, such as the compressor 11, the first switching mechanism 12a, the second switching mechanism 12b, the third switching mechanism 12c, the fourth switching mechanism 12d, the first heat source fan 14a, the second heat source fan 14b, the first heat source expansion valve mechanism 15a, the second heat source expansion mechanism 15b, the third heat source expansion mechanism 15c, the first utilization expansion mechanism 21a, the second utilization expansion mechanism 21b, the first utilization fan 23a, and the second utilization fan 23b, based on detection signals from the outdoor temperature sensor 41, the suction pressure sensor 42, the discharge pressure sensor 43, and the indoor temperature sensor 44, thereby performing air conditioning operations such as cooling operation, heating operation, and defrosting operation, as well as various other controls.

[0085] (2-4-2) Control during defrosting operation

[0086] Hereinafter, control during the defrosting operation performed by the heat source control unit 4 of the control unit 6 of the refrigeration cycle apparatus 1 will be described.

[0087] The defrost operation is an operation for removing frost from at least a portion of the first heat source heat exchanger 13a and the second heat source heat exchanger 13b. In the defrost operation of this embodiment, while the operation of the compressor 11 continues, a first defrost mode for removing frost from the first heat source heat exchanger 13a and a second defrost mode for removing frost from the second heat source heat exchanger 13b are switched. Therefore, the heat source control unit 4 alternates between the first defrost mode and the second defrost mode as the defrost operation. In addition, during this defrost operation, the heat source control unit 4 controls the first heat source fan 14a and the second heat source fan 14b so that the rotation speed of the first heat source fan 14a is different from the rotation speed of the second heat source fan 14b. In addition, during this defrost operation, the heat source control unit 4 controls the first heat source fan 14a and the second heat source fan 14b so that the maximum rotation speed of the first heat source fan 14 is different from the maximum rotation speed of the second heat source fan 14b.

[0088] Specifically, in the first defrost mode, the heat source control unit 4 condenses the refrigerant in the first heat source heat exchanger 13a and evaporates the refrigerant in the second heat source heat exchanger 13b, while also setting the rotational speed of the first heat source fan 14a to be lower than the rotational speed of the second heat source fan 14b. Specifically, in the first defrost mode, the first heat source heat exchanger 13a functions as a condenser for the defrost operation, and the second heat source heat exchanger 13b functions as an evaporator for the heating operation. Furthermore, the heat source control unit 4 sets the rotational speed of the first heat source fan 14a, which delivers outdoor air to the first heat source heat exchanger 13a, which functions as a condenser for the defrost operation, to be lower than the rotational speed of the second heat source fan 14b, which delivers outdoor air to the second heat source heat exchanger 13b, which functions as an evaporator for the heating operation. This prevents outdoor air from the second heat source fan 14b from passing through the first heat source fan 14a.

[0089] Here, in the first defrost mode, the heat source control unit 4 stops the operation of the first heat source fan 14a. Furthermore, in the first defrost mode, the heat source control unit 4 sets the upper limit speed of the second heat source fan 14b to a value lower than the upper limit speed during normal operation. Normal operation is heating operation without defrosting. During normal operation, the heat source control unit 4 controls the speeds of the first and second heat source fans 14a, 14b based on the heating capacity and the temperatures of the first and second heat source heat exchangers 13a, 13b. In the first defrost mode, the heat source control unit 4 controls the speed of the second heat source fan 14b to, for example, less than 60% of the speed during normal operation. Thus, in this embodiment, in the first defrost mode, the heat source control unit 4 stops the first heat source fan 14a and reduces the speed of the second heat source fan 14b.

[0090] Furthermore, in the second defrost mode, the heat source control unit 4 condenses the refrigerant in the second heat source heat exchanger 13b and evaporates the refrigerant in the first heat source heat exchanger 13a, while also setting the rotation speed of the second heat source fan 14b to be lower than the rotation speed of the first heat source fan 14a. Specifically, in the second defrost mode, the second heat source heat exchanger 13b functions as a condenser for the defrost operation, while the first heat source heat exchanger 13a functions as an evaporator for the heating operation. Furthermore, the heat source control unit 4 sets the rotation speed of the second heat source fan 14b, which delivers outdoor air to the second heat source heat exchanger 13b, which functions as a condenser for the defrost operation, to be lower than the rotation speed of the first heat source fan 14a, which delivers outdoor air to the first heat source heat exchanger 13a, which functions as an evaporator for the heating operation. This prevents outdoor air from the first heat source fan 14a from passing through the second heat source fan 14b.

[0091] Here, the heat source control unit 4 stops the second heat source fan 14b in the second defrost mode. Furthermore, the heat source control unit 4 sets the upper limit speed of the first heat source fan 14a to a value lower than the upper limit speed during normal operation during the second defrost mode. For example, the heat source control unit 4 controls the speed of the first heat source fan 14a to less than 60% of the speed during normal operation during the second defrost mode. Thus, in this embodiment, the heat source control unit 4 stops the second heat source fan 14b and reduces the speed of the first heat source fan 14a during the second defrost mode. In other words, the heat source control unit 4 stops the fan that supplies outdoor air through the heat exchanger serving as the evaporator and reduces the speed of the fan that supplies outdoor air through the heat exchanger serving as the condenser.

[0092] Furthermore, the heat source control unit 4 performs at least one of the first and second defrost modes as a defrost operation. For example, the heat source control unit 4 may start in the first defrost mode, then switch to the second defrost mode, and then terminate the defrost operation. In this case, the defrost operation consists of only one first defrost mode and one second defrost mode. Furthermore, for example, the heat source control unit 4 may start in the second defrost mode, then switch to the first defrost mode, then switch to the second defrost mode, and then terminate the defrost operation. In this case, the defrost operation consists of only two second defrost modes and one first defrost mode.

[0093] Furthermore, the heat source control unit 4 reduces the rotational speed of the compression molding machine 11 when switching from heating operation to defrost operation. Specifically, the heat source control unit 4 reduces the rotational speed of the compressor 11 before switching from heating operation to the first defrost mode or the second defrost mode. Furthermore, the heat source control unit 4 reduces the rotational speed of the compressor 11 before switching from the first defrost mode to the second defrost mode. Furthermore, the heat source control unit 4 reduces the rotational speed of the compressor 11 before switching from the second defrost mode to the first defrost mode.

[0094] (3) Action

[0095] Reference Figures 1 to 8 The operation of the refrigeration cycle device 1 will be described. The refrigeration cycle device 1 performs cooling operation, heating operation, and defrosting operation. The operation of the refrigeration cycle device 1 including the above-mentioned operations is performed by the control unit 6.

[0096] (3-1) Refrigeration Operation

[0097] Below, refer to Figure 4 Next, the operation during cooling operation of the refrigeration cycle apparatus 1 will be described. Here, the case where all of the plurality of utilization heat exchangers of the utilization unit 20 cool the indoor air will be described.

[0098] The control unit 6 which receives the cooling operation instruction controls the operation of the compressor 11, the first switching mechanism 12a, the second switching valve mechanism 12b, the third switching mechanism 12c, the fourth switching mechanism 12d, the first heat source fan 14a, the second heat source fan 14b, the first heat source expansion valve mechanism 15a, the second heat source expansion mechanism 15b, the third heat source expansion mechanism 15c, the first utilization expansion valve mechanism 21a, the second utilization expansion valve mechanism 21b, the first utilization fan 23a, the second utilization fan 23b, etc. Figure 4 Cooling operation shown.

[0099] The first switching mechanism 12a, the second switching mechanism 12b, the third switching mechanism 12c and the fourth switching mechanism 12d are switched to a state in which the first heat source heat exchanger 13a and the second heat source heat exchanger 13b act as condensers of the refrigerant, and the first utilization heat exchanger 22a and the second utilization heat exchanger 22b act as evaporators of the refrigerant.

[0100] like Figure 4 As shown, in this state of the refrigerant circuit 2, low-pressure refrigerant in the refrigeration cycle is drawn into the compressor 11, compressed to the high pressure within the refrigeration cycle, and then discharged. The high-pressure refrigerant discharged from the compressor 11 is branched and delivered to the first heat source heat exchanger 13a via the first switching mechanism 12a, and then to the second heat source heat exchanger 13b via the second switching mechanism 12b. The refrigerant delivered to the first heat source heat exchanger 13a condenses by exchanging heat with outdoor air supplied by the first heat source fan 14a in the first heat source heat exchanger 13a. This refrigerant is delivered to the first flow path 16a of the subcooling heat exchanger 16 via the first heat source expansion mechanism 15a. Furthermore, the refrigerant delivered to the second heat source heat exchanger 13b condenses by exchanging heat with outdoor air supplied by the second heat source fan 14b in the second heat source heat exchanger 13b. This refrigerant is delivered to the first flow path 16a of the subcooling heat exchanger 16 via the second heat source expansion mechanism 15b. The refrigerants that have merged and are further cooled in the subcooling heat exchanger 16 pass through the first stop valve 18 a and flow out of the heat source unit 10 .

[0101] The refrigerant flowing out of the heat source unit 10 is transported to the utilization unit 20 through the first connecting pipe 31. The refrigerant transported to the utilization unit 20 is branched and reduced in pressure to the low pressure within the refrigeration cycle by the first and second expansion mechanisms 21a and 21b. The refrigerant transported to the first and second heat exchangers 22a and 22b is heated and evaporated by heat exchange with indoor air supplied from the room by the first and second fans 23a and 23b in the first and second heat exchangers 22a and 22b, which function as evaporators. This refrigerant then flows out of the utilization unit 20. Meanwhile, the indoor air cooled by the first and second heat exchangers 22a and 22b is transported back into the room, thereby cooling the room.

[0102] The refrigerant flowing out of the utilization unit 20 and passing through the first utilization heat exchanger 22a is transported to the heat source unit 10 via the second connecting pipe 32. The refrigerant transported to the heat source unit 10 passes through the second shutoff valve 18b and the third switching mechanism 12c, and is then transported to the accumulator 17. The refrigerant flowing out of the utilization unit 20 and passing through the second utilization heat exchanger 22b is transported to the heat source unit 10 via the third connecting pipe 33. The refrigerant transported to the heat source unit 10 passes through the third shutoff valve 18c and the fourth switching mechanism 12d, and is then transported to the accumulator 17. The refrigerant that has been combined in the accumulator 17 is then drawn into the compressor 11.

[0103] During the cooling operation described above, the control unit 6 uses the refrigerant flowing in the second flow path 16b of the refrigerant circuit 2 to cool the refrigerant flowing in the first flow path 16a of the refrigerant circuit 2 through the subcooling heat exchanger 16 and the subcooling circuit 3, and then delivers the refrigerant to the first connecting pipe 31. Specifically, a portion of the refrigerant that has passed through the first heat source expansion mechanism 15a and the second heat source expansion mechanism 15b and converged is branched, passed through the subcooling circuit 3, and delivered to the compressor 11. At this time, the flow rate of the refrigerant flowing in the second flow path 16b is adjusted by controlling the opening degree of the third heat source expansion mechanism 15c.

[0104] During refrigeration operation, the operating frequency of the compressor 11 is controlled so that the low pressure value of the refrigeration cycle (the detection value of the suction pressure sensor 42) becomes a constant value, and the opening of the first expansion mechanism 21a and the second expansion mechanism 21b is adjusted so that the superheat of the refrigerant at the outlet of the first heat exchanger 22a and the second heat exchanger 22b becomes a specified target value.

[0105] In the cooling operation, one of the utilization heat exchangers in the utilization unit 20 and one of the heat source heat exchangers in the heat source unit 10 may not be used depending on the load.

[0106] (3-2) Heating operation

[0107] Below, refer to Figure 5 Next, the operation during the heating operation of the refrigeration cycle apparatus 1 will be described. Here, the case where all of the plurality of utilization heat exchangers of the utilization unit 20 heat the indoor air will be described.

[0108] The control unit 6 which receives the instruction of the heating operation controls the operation of the compressor 11, the first switching mechanism 12a, the second switching valve mechanism 12b, the third switching mechanism 12c, the fourth switching mechanism 12d, the first heat source fan 14a, the second heat source fan 14b, the first heat source expansion valve mechanism 15a, the second heat source expansion mechanism 15b, the third heat source expansion mechanism 15c, the first utilization expansion valve mechanism 21a, the second utilization expansion valve mechanism 21b, the first utilization fan 23a, the second utilization fan 23b, etc. Figure 5 Heating operation shown.

[0109] The first switching mechanism 12a, the second switching mechanism 12b, the third switching mechanism 12c and the fourth switching mechanism 12d are switched to change the state in which the first heat source heat exchanger 13a and the second heat source heat exchanger 13b act as evaporators of the refrigerant, and the first utilization heat exchanger 22a and the second utilization heat exchanger 22b act as condensers of the refrigerant.

[0110] like Figure 5 As shown, in this state of the refrigerant circuit 2, low-pressure refrigerant in the refrigeration cycle is drawn into the compressor 11, compressed to high pressure in the refrigeration cycle, and then discharged. The high-pressure refrigerant discharged from the compressor 11 branches, flows out of the heat source unit 10 through the third switching mechanism 12c and the second stop valve 18b, and then flows out of the heat source unit 10 through the fourth switching mechanism 12d and the third stop valve 18c.

[0111] The refrigerant flowing out of the heat source unit 10 through the second stop valve 18b is transported via the second connecting pipe 32 to the first utilization heat exchanger 22a of the utilization unit 20. The refrigerant flowing out of the heat source unit 10 through the third stop valve 18c is transported via the third connecting pipe 33 to the second utilization heat exchanger 22b of the utilization unit 20. The high-pressure refrigerant transported to the first and second utilization heat exchangers 22a and 22b is cooled and condensed by heat exchange with indoor air supplied from the room by the first and second utilization fans 23a and 23b in the first and second utilization heat exchangers 22a and 22b, which function as refrigerant condensers. This refrigerant is decompressed by the first and second utilization expansion mechanisms 21a and 21b before flowing out of the utilization unit 20. Meanwhile, the indoor air heated in the first and second utilization heat exchangers 22a and 22b is transported indoors, thereby heating the room.

[0112] The refrigerant that has converged and flowed out of the utilization unit 20 is delivered to the heat source unit 10 through the first communication pipe 31. The refrigerant delivered to the heat source unit 10 passes through the first shutoff valve 18a and is delivered to the first flow path 16a of the subcooling heat exchanger 16. The refrigerant cooled in the subcooling heat exchanger 16 branches and is delivered to the first heat source expansion valve mechanism 15a and the second heat source expansion mechanism 15b.

[0113] The refrigerant supplied to the first heat source expansion mechanism 15a is decompressed to the low pressure in the refrigeration cycle by the first heat source expansion mechanism 15a and then supplied to the first heat source heat exchanger 13a. The refrigerant supplied to the first heat source heat exchanger 13a is heated by heat exchange with the outdoor air supplied by the first heat source fan 14a, thereby evaporating. This refrigerant is supplied to the accumulator 17 through the first switching mechanism 12a. The refrigerant supplied to the second heat source expansion mechanism 15b is decompressed to the low pressure in the refrigeration cycle by the second heat source expansion mechanism 15b and then supplied to the second heat source heat exchanger 13b. The refrigerant supplied to the second heat source heat exchanger 13b is heated by heat exchange with the outdoor air supplied by the second heat source fan 14b, thereby evaporating. This refrigerant is supplied to the accumulator 17 through the second switching mechanism 12b. The refrigerant that has merged in the accumulator 17 is sucked into the compressor 11.

[0114] During the heating operation described above, the controller 6 uses the refrigerant flowing in the second flow path 16b of the refrigerant circuit 2 to cool the refrigerant flowing in the first flow path 16a of the refrigerant circuit 2 through the subcooling heat exchanger 16 and the subcooling circuit 3, and then delivers the refrigerant to the first heat source expansion mechanism 15a and the second heat source expansion mechanism 15b. Specifically, a portion of the refrigerant that has passed through the first flow path 16a of the subcooling heat exchanger 16 is branched, passed through the subcooling circuit 3, and delivered to the compressor 11. At this time, the flow rate of the refrigerant flowing in the second flow path 16b is adjusted by controlling the opening degree of the third heat source expansion mechanism 15c.

[0115] During heating operation, the operating frequency of the compressor 11 is controlled so that the high pressure value of the refrigeration cycle (the detection value of the discharge pressure sensor 43) becomes a constant value, and the opening degree of the first expansion mechanism 21a and the second expansion mechanism 21b is adjusted so that the subcooling degree of the refrigerant at the outlet of the first heat exchanger 22a and the second heat exchanger 22b becomes a specified target value.

[0116] In addition, in the heating operation described above, depending on the load, one of the utilization heat exchangers in the utilization unit 20 and one of the heat source heat exchangers in the heat source unit 10 may not be used.

[0117] (3-3) Defrost operation

[0118] In the refrigeration cycle device 1, during the heating operation, the defrost operation is performed when the prescribed conditions are met. The defrost operation of this embodiment is to switch between the first defrost mode for removing frost from the first heat source heat exchanger 13a and the second defrost mode for removing frost from the second heat source heat exchanger 13b while continuing the operation of the compressor 11. Therefore, by performing the heating operation in the first defrost mode by using the second heat source heat exchanger 13b as the evaporator of the refrigerant, and performing the heating operation in the second defrost mode by using the first heat source heat exchanger 13a as the evaporator of the refrigerant, the uninterrupted state of the heating operation is maintained during the defrost operation. As follows, Figure 6 As shown, from Figure 7 The first defrost mode shown starts and then switches to Figure 8 The defrosting operation that ends with the second defrosting mode shown will be described.

[0119] like Figure 6As shown, the heat source control unit 4 of the control unit 6 determines whether the predetermined conditions related to frost formation are met during the heating operation (step S1) (step S2). The predetermined conditions are not particularly limited, and for example, the determination can be made based on at least one of the following conditions: the outside air temperature measured by the outdoor temperature sensor 41 is below a predetermined value; a predetermined time has passed since the defrosting operation was completed; the temperature of at least one of the first heat source heat exchanger 13a and the second heat source heat exchanger 13b is below a predetermined value; and the evaporation pressure or evaporation temperature of the refrigerant in the refrigerant circuit 2 is below a predetermined value.

[0120] In step S2, when the heat source control unit 4 determines that the prescribed conditions are not met, it continues the heating operation (step S1). On the other hand, in step S2, when the heat source control unit 4 determines that the prescribed conditions are met, it switches to perform the defrosting operation (step S3). In step S3, the heat source control unit 4 switches the first switching mechanism 12a to condense the refrigerant in the first heat source heat exchanger 13a and evaporate the refrigerant in the second heat source heat exchanger 13b, thereby changing to the first defrosting mode. In detail, as Figure 7 As shown in FIG. 1 , the heat source control unit 4 switches the first switching mechanism 12a to the same state as the cooling operation and reduces the rotation speed of the compressor 11.

[0121] Then, the heat source control unit 4 starts the first defrosting mode (step S4 ). The heat source control unit 4 controls the first heat source fan 14 a and the second heat source fan 14 b so that the rotation speed of the first heat source fan 14 a is different from the rotation speed of the second heat source fan 14 b.

[0122] In the first defrost mode, if Figure 7 As shown, in the refrigerant circuit 2 , low-pressure gas refrigerant in the refrigeration cycle is compressed to high pressure in the refrigeration cycle by the compressor 11 and then branches to the first switching mechanism 12 a , the third switching mechanism 12 c , and the fourth switching mechanism 12 d .

[0123] The refrigerant flowing into the third switching mechanism 12c flows through the third switching mechanism 12c, the second stop valve 18b, the second connecting pipe 32, the first utilization heat exchanger 22a, the first utilization expansion mechanism 21a, the first connecting pipe 31, the first stop valve 18a, and the subcooling heat exchanger 16, similarly to the operation in the heating operation, and then flows into the second heat source expansion mechanism 15b. The refrigerant flowing into the fourth switching mechanism 12d flows through the fourth switching mechanism 12d, the third stop valve 18c, the third connecting pipe 33, the second utilization heat exchanger 22b, the second utilization expansion mechanism 21b, the first connecting pipe 31, the first stop valve 18a, and the subcooling heat exchanger 16, similarly to the operation in the heating operation, and then flows into the second heat source expansion mechanism 15b.

[0124] Alternatively, a portion of the refrigerant that has passed through the first flow path 16 a of the subcooling heat exchanger 16 may be branched to the subcooling circuit 3 .

[0125] Meanwhile, the refrigerant flowing toward the first switching mechanism 12a passes through the first switching mechanism 12a and flows into the first heat source heat exchanger 13a. The high-pressure refrigerant flowing into the first heat source heat exchanger 13a supplies heat to the first heat source heat exchanger 13a. This melts the frost adhering to the first heat source heat exchanger 13a, defrosting the first heat source heat exchanger 13a.

[0126] The high-pressure refrigerant flowing out of the first heat source heat exchanger 13a merges with the refrigerant flowing out of the first utilization heat exchanger 22a and the second utilization heat exchanger 22b, which serve as condensers for heating operation, before the second heat source expansion mechanism 15b. The merged refrigerant passes through the second heat source expansion mechanism 15b, becoming a low-pressure gas-liquid two-phase refrigerant and flowing into the second heat source heat exchanger 13b. The low-pressure refrigerant flowing into the second heat source heat exchanger 13b exchanges heat with the outdoor air delivered by the second heat source fan 14b, becoming a low-pressure gas refrigerant, and then flows out of the second heat source heat exchanger 13b. The low-pressure gas refrigerant flowing out of the second heat source heat exchanger 13b passes through the accumulator 17 and is again drawn into the compressor 11.

[0127] In this embodiment, in the first defrost mode, the heat source control unit 4 sets the rotational speed of the first heat source fan 14a to be lower than the rotational speed of the second heat source fan 14b. Here, the heat source control unit 4 stops the first heat source fan 14a and sets the upper limit rotational speed of the second heat source fan 14b to be lower than the upper limit rotational speed during heating operation. Furthermore, the heat source control unit 4 increases the rotational speed of the compressor 11.

[0128] The heat source control unit 4 determines whether the completion conditions for the first defrost operation are met (step S5). The completion conditions for the first defrost mode are not particularly limited, and can be determined by, for example, at least one of the following conditions: a predetermined time has passed since the start of the first defrost mode; the temperature of the first heat source heat exchanger 13a is above a predetermined value; or the condensing pressure or condensing temperature of the refrigerant is above a predetermined value.

[0129] When the heat source control unit 4 determines in step S5 that the completion condition of the first defrost mode is satisfied, it switches to the second defrost mode (step S6). In step S6, the heat source control unit 4 switches to evaporate the refrigerant in the first heat source heat exchanger 13a and condense the refrigerant in the second heat source heat exchanger 13b, thereby changing to the second defrost mode. Figure 8As shown, the heat source control unit 4 switches the first switching mechanism 12a to the same state as the heating operation and switches the second switching mechanism 12b to the same state as the cooling operation.

[0130] Then, the heat source control unit 4 starts the second defrosting mode (step S7 ). The heat source control unit 4 controls the first heat source fan 14 a and the second heat source fan 14 b so that the rotation speed of the first heat source fan 14 a is different from the rotation speed of the second heat source fan 14 b.

[0131] In the second defrost mode, if Figure 8 As shown, in the refrigerant circuit 2 , low-pressure gas refrigerant in the refrigeration cycle is compressed to high pressure in the refrigeration cycle by the compressor 11 and branches to the second switching mechanism 12 b , the third switching mechanism 12 c , and the fourth switching mechanism 12 d .

[0132] The refrigerant flowing into the third switching mechanism 12c flows through the third switching mechanism 12c, the second stop valve 18b, the second connecting pipe 32, the first utilization heat exchanger 22a, the first utilization expansion mechanism 21a, the first connecting pipe 31, the first stop valve 18a, and the subcooling heat exchanger 16, similarly to the heating operation, and then flows into the first heat source expansion mechanism 15a. The refrigerant flowing into the fourth switching mechanism 12d flows through the fourth switching mechanism 12d, the third stop valve 18c, the third connecting pipe 33, the second utilization heat exchanger 22b, the second utilization expansion mechanism 21b, the first connecting pipe 31, the first stop valve 18a, and the subcooling heat exchanger 16, similarly to the heating operation, and then flows into the first heat source expansion mechanism 15a.

[0133] Alternatively, a portion of the refrigerant that has passed through the first flow path 16 a of the subcooling heat exchanger 16 may be branched to the subcooling circuit 3 .

[0134] Meanwhile, the refrigerant flowing toward the second switching mechanism 12b passes through the second switching mechanism 12b and flows into the second heat source heat exchanger 13b. The high-pressure refrigerant flowing into the second heat source heat exchanger 13b supplies heat to the second heat source heat exchanger 13b. This melts the frost adhering to the second heat source heat exchanger 13b, defrosting the second heat source heat exchanger 13b.

[0135] The high-pressure refrigerant flowing out of the second heat source heat exchanger 13b merges with the refrigerant flowing out of the first utilization heat exchanger 22a and the second utilization heat exchanger 22b, which serve as condensers for heating operation, before the first heat source expansion mechanism 15a. The merged refrigerant passes through the second heat source expansion mechanism 15a, becoming a low-pressure gas-liquid two-phase refrigerant and then flowing into the first heat source heat exchanger 13a. The low-pressure refrigerant flowing into the first heat source heat exchanger 13a exchanges heat with the outdoor air delivered by the first heat source fan 14a, becoming a low-pressure gas refrigerant and flowing out of the first heat source heat exchanger 13a. The low-pressure gas refrigerant flowing out of the first heat source heat exchanger 13a passes through the accumulator 17 and is again drawn into the compressor 11.

[0136] In this embodiment, in the second defrost mode, the heat source control unit 4 sets the rotation speed of the second heat source fan 14b to be lower than the rotation speed of the first heat source fan 14a. Here, the heat source control unit 4 stops the second heat source fan 14b and sets the upper limit rotation speed of the first heat source fan 14a to be lower than the upper limit rotation speed during heating operation.

[0137] Furthermore, the heat source control unit 4 increases the rotation speed of the compressor 11. The heat source control unit 4 makes the rotation speed of the compressor 11 in the second defrosting mode higher than the rotation speed of the compressor 11 in the first defrosting mode.

[0138] The heat source control unit 4 determines whether the completion conditions for the second defrost operation have been met (step S8). The completion conditions for the second defrost mode are not particularly limited and can be determined by, for example, at least one of the following conditions: a predetermined time has passed since the start of the second defrost mode; the temperature of the second heat source heat exchanger 13b is above a predetermined value; or the condensing pressure or condensing temperature of the refrigerant is above a predetermined value. In this embodiment, the second heat source heat exchanger 13b is positioned below the first heat source heat exchanger 13a. Therefore, the completion conditions for the second defrost mode differ from those for the first defrost mode, taking into account that water generated by the defrost operation of the first heat source heat exchanger 13a during the first defrost mode flows to the second heat source heat exchanger 13b below. Here, for example, the completion condition is that the time elapsed since the start of the second defrost mode is longer than the time elapsed since the start of the first defrost mode. Alternatively, for example, the completion condition is that the predetermined value for the temperature of the second heat source heat exchanger 13b is higher than the predetermined value for the temperature of the first heat source heat exchanger 13a.

[0139] When the heat source control unit 4 determines in step S8 that the completion condition of the second defrosting mode is satisfied, it switches to the heating operation (step S9). In step S9, the heat source control unit 4 switches to evaporate the refrigerant in the first heat source heat exchanger 13a and the second heat source heat exchanger 13b, thereby switching to the heating operation. Figure 5As shown, the heat source control unit 4 switches the second switching mechanism 12b to the same state as the heating operation and reduces the rotation speed of the compressor 11. Then, the heating operation is resumed (step S1).

[0140] (4) Characteristics

[0141] (4-1)

[0142] The heat source unit 10 of this embodiment includes a compressor 11, a first heat source heat exchanger 13a, a second heat source heat exchanger 13b, a first fan (first heat source fan 14a), a second fan (second heat source fan 14b), and a control unit (heat source control unit 4). The first heat source fan 14a mainly passes air through the first heat source heat exchanger 13a. The second heat source fan 14b mainly passes air through the second heat source heat exchanger 13b. While continuing the operation of the compressor 11, the heat source control unit 4 controls the first heat source fan 14a and the second heat source fan 14b during the defrost operation, so that the rotation speeds of the first heat source fan 14a and the second heat source fan 14b are different. The defrost operation switches between a first defrost mode for removing frost from the first heat source heat exchanger 13a and a second defrost mode for removing frost from the second heat source heat exchanger 13b.

[0143] According to the heat source unit 10 of this embodiment, in the first defrost mode, the first heat source heat exchanger 13a can be used as a refrigerant condenser for defrosting while the second heat source heat exchanger 13b can be used as a refrigerant evaporator for heating. Furthermore, in the second defrost mode, the second heat source heat exchanger 13b can be used as a refrigerant condenser for defrosting while the first heat source heat exchanger 13a can be used as a refrigerant evaporator for heating. Therefore, heating operation can be continued during the defrost operation, which removes frost from the first and second heat source heat exchangers 13a, 13b. Furthermore, by controlling the rotational speeds of the first and second heat source fans 14a, 14b to be different, the amount of air passing through the first or second heat source heat exchanger 13a, 13b, as the condenser for defrosting, and the amount of air passing through the second or first heat source heat exchanger 13b, 13a, as the evaporator for heating can be varied. Therefore, the influence of air passing through the second heat source heat exchanger 13b or the first heat source heat exchanger 13a serving as the evaporator on the first heat source heat exchanger 13a or the second heat source heat exchanger 13b serving as the condenser can be reduced. Therefore, heating capacity can be maintained during defrost operation while heating operation is performed, and a decrease in defrost operation capacity can be suppressed.

[0144] In particular, in this embodiment, the heat source control unit 4 controls the first heat source fan 14a and the second heat source fan 14b during the defrost operation while continuing the operation of the compressor 11, so that the rotational speed of the first heat source fan 14a and the rotational speed of the second heat source fan 14b are different. During the defrost operation, a first defrost mode in which the first heat source heat exchanger 13a is operated as a condenser and the second heat source heat exchanger 13b is operated as an evaporator and a second defrost mode in which the second heat source heat exchanger 13b is operated as a condenser and the first heat source heat exchanger 13a is operated as an evaporator are switched.

[0145] (4-2)

[0146] In the heat source unit 10 of this embodiment, it is preferred that the heat source control unit 4 condenses the refrigerant in the first heat source heat exchanger 13a, evaporates the refrigerant in the second heat source heat exchanger 13b, and makes the rotation speed of the first heat source fan 14a lower than the rotation speed of the second heat source fan 14b in the first defrost mode.

[0147] Here, the rotation speed of the first heat source fan 14a, which delivers air to the first heat source heat exchanger 13a, which functions as a condenser during the defrost operation, is set lower than the rotation speed of the second heat source fan 14b, which delivers air through the second heat source heat exchanger 13b, which functions as an evaporator during the heating operation. Therefore, during the defrost operation of the first heat source heat exchanger 13a, the influence of the ventilation caused by the second heat source fan 14b can be reduced, thereby further suppressing the reduction in the performance of the defrost operation.

[0148] In addition, in the heat source unit 10 of this embodiment, it is preferred that the heat source control unit 4 condenses the refrigerant in the second heat source heat exchanger 13b and evaporates the refrigerant in the first heat source heat exchanger 13a in the second defrost mode, and makes the rotation speed of the second heat source fan 14b lower than the rotation speed of the first heat source fan 14a.

[0149] Here, the rotation speed of the second heat source fan 14b, which delivers air to the second heat source heat exchanger 13b, which serves as the condenser for the defrost operation, is set lower than the rotation speed of the first heat source fan 14a, which passes air through the first heat source heat exchanger 13a, which serves as the evaporator for the heating operation. Therefore, during the defrost operation of the second heat source heat exchanger 13b, the influence of the ventilation caused by the first heat source fan 14a can be reduced, thereby further suppressing the decline in the defrost operation performance.

[0150] (4-3)

[0151] In the heat source unit 10 of the present embodiment, it is preferable that the heat source control section 4 stops the first heat source fan 14a in the first defrosting mode.

[0152] Here, the first heat source fan 14a that sends air to the first heat source heat exchanger 13a used as a condenser for the defrosting operation is stopped. Therefore, it is possible to more effectively suppress a decrease in the defrosting operation performance of the first heat source heat exchanger 13a.

[0153] Furthermore, in the heat source unit 10 of the present embodiment, it is preferable that the heat source control section 4 stops the second heat source fan 14b in the second defrosting mode.

[0154] Here, the second heat source fan 14b that sends air to the second heat source heat exchanger 13b used as a condenser for the defrosting operation is stopped. Therefore, it is possible to more effectively suppress a decrease in the defrosting operation performance of the second heat source heat exchanger 13b.

[0155] (4-4)

[0156] In the heat source unit 10 of this embodiment, it is preferred that the heat source control unit 4 condenses the refrigerant in the first heat source heat exchanger 13a and evaporates the refrigerant in the second heat source heat exchanger 13b in the first defrost mode, and makes the upper limit speed of the second heat source fan 14b lower than the upper limit speed during normal operation.

[0157] Here, the rotational speed of the second heat source fan 14b, which passes the supply air through the second heat source heat exchanger 13b, which serves as the evaporator for heating operation, is lower than the upper limit rotational speed during normal operation. Therefore, during the defrost operation of the first heat source heat exchanger 13a, the air volume passed through the second heat source heat exchanger 13b by the second heat source fan 14b is lower than the maximum air volume during normal operation. Therefore, during the defrost operation of the first heat source heat exchanger 13a, the impact of the ventilation caused by the second heat source fan 14b can be reduced, thereby further suppressing the decline in the defrost performance.

[0158] In addition, in the heat source unit 10 of this embodiment, it is preferred that the heat source control unit 4 condenses the refrigerant in the second heat source heat exchanger 13b and evaporates the refrigerant in the first heat source heat exchanger 13a in the second defrost mode, and makes the upper limit speed of the first heat source fan 14a lower than the upper limit speed during normal operation.

[0159] Here, the rotational speed of the first heat source fan 14a, which passes the supply air through the first heat source heat exchanger 13a, which serves as the evaporator for heating operation, is lower than the upper limit rotational speed during normal operation. Therefore, during the defrost operation of the second heat source heat exchanger 13b, the air volume passing through the first heat source heat exchanger 13a achieved by the first heat source fan 14a is lower than the maximum air volume during normal operation. Therefore, during the defrost operation of the second heat source heat exchanger 13b, the influence of the ventilation caused by the first heat source fan 14a can be reduced, thereby further suppressing the decline in the defrost performance.

[0160] (4-5)

[0161] In the heat source unit 10 of this embodiment, the second heat source heat exchanger 13b is preferably arranged below the first heat source heat exchanger 13a. In the heat source unit 10 of this embodiment, at least a portion of the first heat source heat exchanger 13a and the second heat source heat exchanger 13b are more preferably in contact with each other.

[0162] In the structure where the second heat source heat exchanger 13b is arranged below the first heat source heat exchanger 13a, there is a significant amount of contact between the first and second heat source heat exchangers. Therefore, in the first defrost mode, when the second heat source heat exchanger 13b is used for heating operation and the first heat source heat exchanger 13a is being defrosted, the technical problem of a decrease in the defrost performance of the first heat source heat exchanger 13a is significant. Furthermore, in the second defrost mode, when the first heat source heat exchanger 13a is used for heating operation and the second heat source heat exchanger 13b is being defrosted, the technical problem of a decrease in the defrost performance of the second heat source heat exchanger 13b is significant. In particular, the greater the contact area between the first and second heat source heat exchangers 13a, the greater the technical problem. To address this technical problem, in this embodiment, the first heat source fan 14a and the second heat source fan 14b are controlled so that the rotational speed of the first heat source fan 14a and the rotational speed of the second heat source fan 14b are different. Therefore, it has the significant effect of being able to perform heating operation during defrost operation and being able to suppress the decline in the ability of defrost operation.

[0163] (4-6)

[0164] The refrigeration cycle apparatus 1 of this embodiment includes the above-mentioned heat source unit 10 and a utilization unit 20. The utilization unit 20 is connected to the heat source unit 10.

[0165] According to the refrigeration cycle apparatus 1 of the present embodiment, since it includes the heat source unit 10 described above, it is possible to realize the refrigeration cycle apparatus 1 that performs the heating operation during the defrosting operation and suppresses a decrease in the performance of the defrosting operation.

[0166] (5) Modification

[0167] (5-1) Modification 1

[0168] In the above embodiment, the heat source control unit 4 stops the first heat source fan 14a in the first defrosting mode and stops the second heat source fan 14b in the second defrosting mode, but the present invention is not limited thereto.

[0169] In this modified example, the heat source control unit 4 does not stop the first heat source fan 14a in the first defrost mode, nor does it stop the second heat source fan 14b in the second defrost mode. Specifically, in the first defrost mode, the heat source control unit 4 reduces the rotation speed of the second heat source fan 14b and sets the rotation speed of the first heat source fan 14a to a very low level. In this case, frost formation on the first heat source fan 14a can be suppressed in the first defrost mode, and frost formation on the second heat source fan 14b can be suppressed in the second defrost mode.

[0170] (5-2) Modification 2

[0171] In the above embodiment, the heat source control unit 4 makes the upper limit speed of the second heat source fan 14b lower than the upper limit speed during normal operation in the first defrost mode, and makes the upper limit speed of the first heat source fan 14a lower than the upper limit speed during normal operation in the second defrost mode, but is not limited to this.

[0172] In this modified example, the heat source control unit 4 stops the first heat source fan 14a and increases the rotation speed of the second heat source fan 14b in the first defrost mode. Furthermore, the heat source control unit 4 stops the second heat source fan 14b and increases the rotation speed of the first heat source fan 14a in the second defrost mode. In this case, the capacity of the second heat source heat exchanger 13b, which functions as an evaporator for heating operation, can be increased in the first defrost mode. Furthermore, the capacity of the first heat source heat exchanger 13a, which functions as an evaporator for heating operation, can be increased in the second defrost mode.

[0173] (5-3) Modification 3

[0174] The first and second variations can also be combined. Specifically, in the first defrost mode, the heat source control unit 4 reduces the rotational speed of the first heat source fan 14a and increases the rotational speed of the second heat source fan 14b. Furthermore, in the second defrost mode, the heat source control unit 4 reduces the rotational speed of the second heat source fan and increases the rotational speed of the first heat source fan.

[0175] Thus, in the above embodiment and modified examples 1 to 3, the rotation speeds of the first heat source fan 14a and the second heat source fan 14b are different based on the air volume balance of the heat source heat exchangers 13a and 13b and the emphasis on the performance of the heating operation performed together with the defrosting operation.

[0176] (5-4) Modification 4

[0177] In the above embodiment, the first defrost mode is used as the condenser, and the second heat source heat exchanger 13b is used as the evaporator for heating operation. In the second defrost mode, the second heat source heat exchanger 13b is used as the condenser, and the first heat source heat exchanger 13a is used as the evaporator for heating operation. However, the present invention is not limited to this. In the first defrost mode, frost can be removed from the first heat source heat exchanger 13a without using the second heat source heat exchanger 13b. In the second defrost mode, frost can be removed from the second heat source heat exchanger 13b without using the first heat source heat exchanger 13a.

[0178] (5-5) Modification 5

[0179] In the above embodiment, the defrost operation of switching between the first defrost mode for removing frost from the first heat source heat exchanger 13a and the second defrost mode for removing frost from the second heat source heat exchanger 13b is described, but in addition to this defrost operation, the heat source control unit 4 can also perform a different defrost operation in which the refrigerant flows in parallel in the first heat source heat exchanger 13a and the second heat source heat exchanger 13b to remove frost from the first heat source heat exchanger 13a and the second heat source heat exchanger 13b.

[0180] (5-6) Modification 6

[0181] In the above embodiment, the refrigerant passes through the subcooling circuit 3 during the heating operation and the defrosting operation, but it is also possible not to pass through the subcooling circuit 3. In addition, the subcooling circuit 3 can be omitted from the refrigeration cycle device of the present disclosure.

[0182] (5-7) Modification 7

[0183] In the above embodiment, the heat source unit 10 and the refrigeration cycle apparatus 1 including two heat source heat exchangers 13a and 13b are described as examples, but the present invention is not limited thereto. The heat source unit and the refrigeration cycle apparatus of the present disclosure may include three or more heat source heat exchangers, as long as there are multiple heat source heat exchangers.

[0184] (5-8) Modification 8

[0185] In the above embodiment, the first utilization fan 23a for supplying air through the first utilization heat exchanger 22a and the second utilization fan 23b for supplying air through the second utilization heat exchanger 22b are respectively provided, but the present invention is not limited thereto. Figure 9 As shown, in the utilization unit constituting the refrigeration cycle device of the present disclosure, the fan for supplying air through the two utilization heat exchangers 22a and 22b may also be shared. In this case, a reheating and dehumidification function can be achieved.

[0186] (5-9) Modification 9

[0187] In the above embodiment, the refrigeration cycle device 1 including one utilization unit 20 having two utilization heat exchangers 22a and 22b is described as an example, but the present invention is not limited thereto. The utilization unit constituting the refrigeration cycle device of the present disclosure may also be as follows. Figure 10 As shown, the refrigeration cycle device may include one utilization unit or multiple utilization units. In this case, the refrigeration cycle device can also be used as a refrigeration cycle device that can enable multiple utilization units to independently perform cooling operation or heating operation.

[0188] (5-10) Modification 10

[0189] In the above embodiment, the refrigeration cycle device 1 that performs cooling operation, heating operation, and defrosting operation is described as an example, but the present invention is not limited thereto. The refrigeration cycle device of the present disclosure may also perform dehumidification operation, etc., and may omit the cooling operation.

[0190] (5-11) Modification Example 11

[0191] In the above embodiment, an air conditioner is described as an example of the refrigeration cycle device 1, but the present invention is not limited thereto. The refrigeration cycle device of the present disclosure may also be a water heater, a floor heating device, a refrigeration device, or the like.

[0192] While the embodiments of the present disclosure have been described above, it should be understood that various modifications in form and detail can be made without departing from the spirit and scope of the present disclosure as described in the claims.

[0193] Prior art literature

[0194] Patent Literature

[0195] Patent Document 1: Japanese Patent Application Laid-Open No. 5-346270.

Claims

1. A heat source unit (10), comprising: compressor (11); a first heat source heat exchanger (13a); a second heat source heat exchanger (13b); a first fan (14a), the first fan being mainly used to pass air through the first heat source heat exchanger; a second fan (14b), the second fan being primarily used to pass air through the second heat source heat exchanger; and Control unit (4), The heat source unit is characterized in that While continuing the operation of the compressor, the control unit controls the first fan and the second fan in a defrost operation so that the rotational speed of the first fan is different from the rotational speed of the second fan. The defrost operation switches between a first defrost mode for removing frost from the first heat source heat exchanger and a second defrost mode for removing frost from the second heat source heat exchanger.

2. The heat source unit according to claim 1, wherein In the first defrosting mode, the control unit condenses the refrigerant in the first heat source heat exchanger, evaporates the refrigerant in the second heat source heat exchanger, and makes the rotation speed of the first fan lower than the rotation speed of the second fan.

3. The heat source unit according to claim 2, wherein: The control unit stops the first fan in the first defrosting mode.

4. The heat source unit according to any one of claims 1 to 3, characterized in that In the first defrosting mode, the controller condenses the refrigerant in the first heat source heat exchanger, evaporates the refrigerant in the second heat source heat exchanger, and sets the upper limit rotation speed of the second fan to be lower than the upper limit rotation speed during normal operation.

5. A refrigeration cycle device (1), characterized in that: include: The heat source unit according to any one of claims 1 to 3; as well as A utilization unit (20) connected to the heat source unit.

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