Refrigeration cycle device

Abstract

The purpose of the present invention is to suppress noise accompanying the operation of a flow path switching mechanism when switching functions of a first heat source heat exchanger and a second heat source heat exchanger while continuing the operation of a compressor. An air conditioning device includes a compressor, a first heat source heat exchanger, a second heat source heat exchanger, a first switching valve, a second switching valve, and a control unit. The first switching valve switches the state of the first heat source heat exchanger between the radiator and the evaporator. The second switching valve switches the state of the second heat source heat exchanger between the radiator and the evaporator. When the rotation speed of the compressor is a predetermined rotation speed (Rc) that is less than the maximum rotation speed (Rmax) of the compressor, the control unit changes the rotation speed of the compressor to a predetermined rotation speed (Rc) that is less than the maximum rotation speed (Rmax) of the compressor while continuing the operation of the compressor. A state in which the second heat source heat exchanger functions as an evaporator and the first heat source heat exchanger functions as a radiator is changed to a state in which the second heat source heat exchanger functions as a radiator and the first heat source heat exchanger functions as an evaporator.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle device. Background Art

[0002] Conventionally, as disclosed in Patent Document 1 (Japanese Patent Publication No. 9-318206), there is known a refrigeration cycle apparatus that includes a plurality of heat source heat exchangers and can use some of the plurality of heat source heat exchangers as evaporators while the remaining heat source heat exchangers as radiators.

[0003] In the refrigeration cycle device of Patent Document 1 (Japanese Gazette No. 9-318206), it is possible to defrost the remaining heat source heat exchangers while using a portion of the heat source heat exchangers for heating operation. Therefore, there is no need to interrupt the heating operation for defrosting, and defrosting can be performed while ensuring the comfort of the user. Summary of the Invention

[0004] In the refrigeration cycle device of Patent Document 1 (Japanese Gazette No. 9-318206), while continuing the heating operation, the heat source heat exchanger used as an evaporator and the heat source heat exchanger used as a radiator are switched, and while continuing the operation of the compressor, the flow switching mechanism for switching the flow direction of the refrigerant in the heat source heat exchanger is operated.

[0005] Therefore, in this refrigeration cycle apparatus, a plurality of flow switching mechanisms may be operated when a high pressure difference exists in the refrigerant circuit, and noise generated during the operation of the flow switching mechanisms is likely to become a problem.

[0006] A refrigeration cycle device according to a first aspect includes a compressor, a first heat source heat exchanger, a second heat source heat exchanger, a first switching mechanism, a second switching mechanism, and a control unit. The first switching mechanism switches between a state in which refrigerant discharged from the compressor's discharge port flows into the first heat source heat exchanger, functioning as a radiator, and a state in which refrigerant, having passed through the first heat source heat exchanger, functioning as an evaporator, flows into the compressor's intake port. The second switching mechanism switches between a state in which refrigerant discharged from the compressor's discharge port flows into the second heat source heat exchanger, functioning as a radiator, and a state in which refrigerant, having passed through the second heat source heat exchanger, functioning as an evaporator, flows into the compressor's intake port. The control unit controls the operation of the compressor, the first switching mechanism, and the second switching mechanism. When the compressor's rotational speed is changed to a predetermined speed less than the compressor's maximum rotational speed, the control unit, while continuing the operation of the compressor, changes the state from the state in which the second heat source heat exchanger functions as an evaporator and the first heat source heat exchanger functions as a radiator to the state in which the second heat source heat exchanger functions as a radiator and the first heat source heat exchanger functions as an evaporator.

[0007] In the refrigeration cycle device of the first aspect, when switching the functions of the first heat source heat exchanger and the second heat source heat exchanger while continuing the operation of the compressor, the rotation speed of the compressor is suppressed to be lower than the maximum rotation speed, thereby suppressing the noise associated with the operation of the flow path switching mechanism.

[0008] The refrigeration cycle apparatus according to the second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the rotation speed is set to be less than 1 / 2 of the maximum rotation speed.

[0009] In the refrigeration cycle device of the second viewpoint, when switching the functions of the first heat source heat exchanger and the second heat source heat exchanger while continuing the operation of the compressor, the speed of the compressor is suppressed to be lower than 1 / 2 of the maximum speed, thereby suppressing the noise accompanying the action of the flow switching mechanism.

[0010] The refrigeration cycle device of the third viewpoint is based on the refrigeration cycle device of the first viewpoint or the second viewpoint, and when the following change is made, the speed of the compressor is a speed less than the maximum speed of the compressor. The change means that the control unit changes the state from a state in which both the first heat source heat exchanger and the second heat source heat exchanger act as evaporators to a state in which one of the first heat source heat exchanger and the second heat source heat exchanger acts as a radiator while continuing the operation of the compressor.

[0011] In the refrigeration cycle device of the third viewpoint, when the function of one of the first heat source heat exchanger acting as an evaporator and the second heat source heat exchanger is switched to the radiator while the operation of the compressor continues, the speed of the compressor is also suppressed to be lower than the maximum speed, thereby suppressing the noise accompanying the action of the flow switching mechanism.

[0012] A refrigeration cycle device according to a fourth aspect is the refrigeration cycle device according to any one of the first to third aspects, further comprising a heat exchanger, piping, and a muffler. The piping connects the first switching mechanism and the second switching mechanism to the heat exchanger. The muffler is provided on the piping.

[0013] In the refrigeration cycle device of the fourth aspect, by providing the silencer member in the piping, it is possible to suppress the propagation of noise to the space where the heat exchanger is installed (for example, the air-conditioned space when the heat exchanger is used for air conditioning) or the space nearby.

[0014] A refrigeration cycle device according to a fifth aspect is the refrigeration cycle device according to the fourth aspect, further comprising a housing for housing the first heat source heat exchanger, the second heat source heat exchanger, the first switching mechanism, and the second switching mechanism, wherein a single silencer is provided in the housing.

[0015] In the refrigeration cycle apparatus according to the fifth aspect, a single silencer member can suppress the propagation of noise to a space where a heat exchanger is installed, while suppressing an increase in the number of components.

[0016] A refrigeration cycle device according to a sixth aspect is the refrigeration cycle device according to any one of the first to fifth aspects, further comprising a first valve for regulating the flow rate of refrigerant flowing through the first heat source heat exchanger and a second valve for regulating the flow rate of refrigerant flowing through the second heat source heat exchanger. The control unit further controls the operation of the first valve and the second valve. When the first heat source heat exchanger is used as an evaporator and the second heat source heat exchanger is used as a radiator, and defrosting the second heat source heat exchanger is performed, the control unit causes the opening of the second valve to be larger than the opening of the second valve when the second heat source heat exchanger is used as an evaporator.

[0017] During defrosting, if liquid refrigerant accumulates in the second heat source heat exchanger, the time required to defrost the second heat source heat exchanger may be prolonged, and there is a risk of residual melted frost. In response to this, in the refrigeration cycle device of the sixth aspect, the opening of the second valve corresponding to the first heat source heat exchanger undergoing defrosting is larger than the opening of the second valve when the second heat source heat exchanger is used as an evaporator. This makes it less likely that liquid refrigerant will accumulate in the second heat source heat exchanger during defrosting. Therefore, in the refrigeration cycle device of the sixth aspect, the time required for defrosting can be shortened, and residual melted frost can be suppressed.

[0018] The refrigeration cycle device of the seventh viewpoint is based on the refrigeration cycle device of any one of the first viewpoints to the sixth viewpoint. When the first heat source heat exchanger is used as an evaporator and the second heat source heat exchanger is used as a radiator and the second heat source heat exchanger is defrosted, the control unit increases the opening of the first valve if the specified conditions are met.

[0019] When the second heat source heat exchanger is used as a radiator and the first heat source heat exchanger is used as an evaporator, a portion of the refrigerant that has passed through the second heat source heat exchanger is transferred to the first heat source heat exchanger. In the refrigeration cycle device of the seventh aspect, the opening of the second valve is increased when a specified condition is met, thereby facilitating the flow of refrigerant through the first heat source heat exchanger. Thus, even if liquid refrigerant accumulates in the second heat source heat exchanger undergoing defrosting, it is easier to discharge the liquid refrigerant out of the second heat source heat exchanger. As a result, in the refrigeration cycle device of the seventh aspect, the time required to defrost the second heat source heat exchanger can be shortened, thereby suppressing the amount of melted frost remaining in the second heat source heat exchanger.

[0020] The refrigeration cycle device of the eighth aspect is based on the refrigeration cycle device of any one of the first to seventh aspects, and the refrigeration cycle device also includes a first refrigerant pipe, a suction pipe, a bypass pipe and a bypass valve. One end of the first refrigerant pipe is connected in parallel to the first heat source heat exchanger and the second heat source heat exchanger, and the other end of the first refrigerant pipe is connected to the heat exchanger. The suction pipe is connected to the suction port of the compressor. The bypass pipe connects the first refrigerant pipe and the suction pipe. The bypass valve is provided in the bypass pipe. The control unit also controls the operation of the bypass valve. When the first heat source heat exchanger is used as an evaporator and the second heat source heat exchanger is used as a radiator, and the second heat source heat exchanger is defrosted, if the specified conditions are met, the control unit opens the closed bypass valve or increases the opening degree of the opened bypass valve.

[0021] In the refrigeration cycle device of the eighth aspect, by opening a closed bypass valve or increasing the opening of an open bypass valve, a portion of the refrigerant flowing to the first heat source heat exchanger flows through the bypass pipe. Therefore, even if liquid refrigerant accumulates in the second heat source heat exchanger undergoing defrosting, this liquid refrigerant can be easily discharged out of the second heat source heat exchanger. As a result, the refrigeration cycle device of the eighth aspect can shorten the time required to defrost the second heat source heat exchanger and suppress the amount of melted frost remaining in the second heat source heat exchanger.

[0022] A refrigeration cycle apparatus according to a ninth aspect is the refrigeration cycle apparatus according to the seventh aspect or the eighth aspect, wherein the predetermined condition is that defrosting of the second heat source heat exchanger is not completed within a predetermined time.

[0023] From the perspective of defrosting efficiency, it is preferred that the openings of the first valve and the bypass valve are not too large. However, when liquid refrigerant accumulates in the second heat source heat exchanger, as described above, the time required for defrosting may be prolonged, and frost may remain after melting.

[0024] In the refrigeration cycle apparatus of the ninth aspect, when defrosting is not completed within the prescribed time, the openings of the first valve and the bypass valve are increased, thereby suppressing a decrease in defrosting efficiency, and preventing the defrosting time from being prolonged and melted frost from remaining. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a diagram schematically showing a refrigerant circuit of an air-conditioning apparatus as one embodiment of the refrigeration cycle apparatus of the present disclosure.

[0026] Figure 2 Yes Figure 1 A block diagram of the control unit of an air conditioning device and the electrical connections of various structures.

[0027] Figure 3 Yes Figure 1A diagram illustrating an example of arrangement of a first heat source heat exchanger and a second heat source heat exchanger of an air-conditioning apparatus.

[0028] Figure 4 It means in Figure 1 FIG. 1 is a diagram showing a state of a refrigerant circuit during cooling operation in which a cooling operation is performed using both a first heat source heat exchanger and a second heat source heat exchanger as radiators in an air-conditioning apparatus.

[0029] Figure 5 It means in Figure 1 FIG. 1 is a diagram showing a state of a refrigerant circuit during a first heating operation in which a heating operation is performed using both a first heat source heat exchanger and a second heat source heat exchanger as evaporators in an air-conditioning apparatus.

[0030] Figure 6 It means in Figure 1 FIG. 1 is a diagram showing a state of the refrigerant circuit during a second heating operation (state of the refrigerant circuit during a first defrosting operation) in an air-conditioning apparatus in which a first heat source heat exchanger is defrosted and a second heat source heat exchanger is used as an evaporator for heating.

[0031] Figure 7 It means in Figure 1 FIG. 1 is a diagram showing a state of the refrigerant circuit during a third heating operation (state of the refrigerant circuit during a second defrost operation) in an air-conditioning apparatus in which the second heat source heat exchanger is defrosted and a heating operation is performed using the first heat source heat exchanger as an evaporator.

[0032] Figure 8 It is used for Figure 1 A diagram illustrating the operating states of various devices in an air-conditioning device when the operation of the air-conditioning device is switched in the order of first heating operation, first defrost operation (second heating operation), second defrost operation (third heating operation), and first heating operation.

[0033] Figure 9 This is a diagram schematically showing a refrigerant circuit of an air-conditioning apparatus as one embodiment of a refrigeration cycle apparatus according to Modification D.

[0034] Figure 10 This is a diagram schematically showing a refrigerant circuit of an air-conditioning apparatus as one embodiment of a refrigeration cycle apparatus according to Modification E.

[0035] Figure 11 This is a diagram schematically showing a refrigerant circuit of an air-conditioning apparatus as one embodiment of a refrigeration cycle apparatus according to Modification F.

[0036] Figure 12 This is a diagram schematically showing a refrigerant circuit of an air-conditioning apparatus as one embodiment of a refrigeration cycle apparatus according to Modification G.

[0037] Explanation of symbols

[0038] 10a housing;

[0039] 12 compressors;

[0040] 12a suction port;

[0041] 12b discharge outlet;

[0042] 16a first switching valve (first switching mechanism, second switching mechanism);

[0043] 16b second switching valve (second switching mechanism, first switching mechanism);

[0044] 18a: first heat source heat exchanger (first heat source heat exchanger, second heat source heat exchanger);

[0045] 18b second heat source heat exchanger (second heat source heat exchanger, first heat source heat exchanger);

[0046] 20a first heat source expansion valve (first valve, second valve);

[0047] 20b second heat source expansion valve (second valve, first valve);

[0048] 21a regulating valve (first valve, second valve);

[0049] 21b regulating valve (second valve, first valve);

[0050] 24 subcooling valve (bypass valve);

[0051] 29a, 29b solenoid valves (second switching mechanism, first switching mechanism);

[0052] 25 sound-absorbing components;

[0053] 52a and 52b utilize heat exchangers;

[0054] 152a first heat exchanger (using heat exchanger);

[0055] 152b second heat exchanger (utilizing heat exchanger);

[0056] 90 Control Department;

[0057] 100 air conditioning units (refrigeration cycle units);

[0058] 100A air conditioning unit (refrigeration cycle unit);

[0059] 100B air conditioning unit (refrigeration cycle unit);

[0060] 100C air conditioning unit (refrigeration cycle unit);

[0061] P1 suction pipe;

[0062] P2 discharge pipe;

[0063] P6 bypass pipe;

[0064] Rmax maximum speed. DETAILED DESCRIPTION

[0065] (1) Structure of air conditioning unit

[0066] An overview of an air-conditioning apparatus 100 according to an embodiment of the refrigeration cycle apparatus of the present disclosure will be described with reference to the drawings. Figure 1 1 is a diagram schematically showing a refrigerant circuit of the air-conditioning apparatus 100 . Figure 2 1 is a block diagram showing the electrical connections between the control unit 90 of the air-conditioning apparatus 100 and various components of the air-conditioning apparatus 100 .

[0067] The air conditioning device 100 is a device that cools or heats the interior of a building, etc., by operating a vapor compression refrigeration cycle. The refrigeration cycle operation disclosed herein is not limited to air conditioning devices. For example, the refrigeration cycle device may also be a device that regulates the temperature of a liquid such as water, such as a water heater or floor heating system.

[0068] The air conditioning apparatus 100 mainly includes a heat source unit 10, a plurality of utilization units 50a, 50b, and refrigerant communication pipes 32, 34, 36 connecting the heat source unit 10 and the utilization units 50a, 50b. Figure 1 Although two utilization units 50a and 50b are depicted, Figure 1 There is no limit to the number of utilization units 50a and 50b, and the number of utilization units may be three or more, or may be one.

[0069] The refrigerant circuit 40 of the air conditioner 100 is composed of a heat source unit 10 and usage units 50a and 50b connected via refrigerant communication pipes 32, 34, and 36. In the air conditioner 100 of this embodiment, each usage unit 50a and 50b can independently perform cooling operation or heating operation.

[0070] An appropriate refrigerant is used in the refrigerant circuit 40. For example, the refrigerant may be an HFC refrigerant such as R32, an HFO refrigerant, or a natural refrigerant such as CO2. In this embodiment, the following description will be made using R32 as an example.

[0071] (1-1) Utilization Unit

[0072] The utilization units 50 a and 50 b are connected to the heat source unit 10 via the refrigerant communication pipes 32 , 34 , and 36 , and constitute a part of the refrigerant circuit 40 .

[0073] The units 50 a and 50 b cool / heat the air of the air-conditioned space, which is the temperature adjustment target, using the refrigerant, thereby cooling / heating the air-conditioned space.

[0074] The usage units 50a and 50b are installed in, for example, a room (air-conditioned space) of a building, etc. The types of the usage units 50a and 50b are not particularly limited, and various types such as ceiling-embedded, ceiling-suspended, wall-mounted, and floor-standing types can be used.

[0075] Utilization unit 50a includes a utilization heat exchanger 52a, an expansion valve 54a, a utilization fan 56a, and a utilization control unit 94a. Utilization unit 50b includes a utilization heat exchanger 52b, an expansion valve 54b, a utilization fan 56b, and a utilization control unit 94b. Utilization unit 50a and utilization unit 50b are identical devices.

[0076] (1-1-1) Using a heat exchanger

[0077] The heat exchangers 52a and 52b are, for example, fin-tube heat exchangers composed of a plurality of heat transfer tubes and fins.

[0078] One end (liquid end) of the heat exchanger 52a is connected to the liquid refrigerant communication tube 32 via a pipe, and the other end (gas end) of the heat exchanger 52a is connected to the gas refrigerant communication tube 34 via a pipe. One end (liquid end) of the heat exchanger 52b is connected to the liquid refrigerant communication tube 32 via a pipe, and the other end (gas end) of the heat exchanger 52b is connected to the gas refrigerant communication tube 36 via a pipe.

[0079] In the utilization heat exchangers 52a and 52b, heat exchange is performed between the refrigerant flowing in the utilization heat exchangers 52a and 52b and the air in the air-conditioned space.

[0080] The heat exchanger 52a functions as a radiator (condenser) or evaporator (heat absorber) for the refrigerant, depending on the connection state of the piping achieved by the third switching valve 16c (described later). The heat exchanger 52b functions as a radiator (condenser) or evaporator (heat absorber) for the refrigerant, depending on the connection state of the piping achieved by the fourth switching valve 16d (described later).

[0081] (1-1-2) Using an expansion valve

[0082] The utilization expansion valve 54a is disposed in the pipe connecting the utilization heat exchanger 52a and the liquid refrigerant communicating pipe 32 (the pipe on the utilization heat exchanger 52a side of the branching portion where the pipe connected to the liquid refrigerant communicating pipe 32 branches off). The utilization expansion valve 54b is disposed in the pipe connecting the utilization heat exchanger 52b and the liquid refrigerant communicating pipe 32 (the pipe on the utilization heat exchanger 52b side of the branching portion where the pipe connected to the liquid refrigerant communicating pipe 32 branches off).

[0083] The expansion valves 54a and 54b are electrically operated valves whose openings can be adjusted. The expansion valves 54a and 54b adjust the flow rate of the refrigerant. Furthermore, the expansion valves 54a and 54b reduce the pressure (expand) of the refrigerant passing through the expansion valves according to their openings.

[0084] (1-1-3) Using a fan

[0085] Utilization fans 56a and 56b are fans that supply air to the corresponding utilization heat exchangers 52a and 52b to promote heat exchange between the air and the refrigerant in the corresponding utilization heat exchangers 52a and 52b. Utilization fans 56a and 56b are variable speed fans. The type of fan used as utilization fans 56a and 56b can be appropriately selected.

[0086] The utilization fan 56a is provided corresponding to the utilization heat exchanger 52a (supplies air to the utilization heat exchanger 52a), and the utilization fan 56b is provided corresponding to the utilization heat exchanger 52b (supplies air to the utilization heat exchanger 52b).

[0087] The fan 56a draws air from the air-conditioned space of the usage unit 50a and supplies the drawn air to the usage heat exchanger 52a. The air that has exchanged heat with the refrigerant in the usage heat exchanger 52a is blown out from the usage unit 50a to the air-conditioned space of the usage unit 50a.

[0088] The fan 56b draws air from the air-conditioned space of the usage unit 50b and supplies the drawn air to the usage heat exchanger 52b. The air that has exchanged heat with the refrigerant in the usage heat exchanger 52b is blown out from the usage unit 50b to the air-conditioned space of the usage unit 50b.

[0089] (1-1-4) Utilization Control Unit

[0090] The use control unit 94a is a control device that controls the use unit 50a, and the use control unit 94b is a control device that controls the use unit 50b. The use control units 94a and 94b mainly include a CPU (processor) and a memory.

[0091] The utilization control unit 94a is electrically connected to the utilization expansion valve 54a and the utilization fan 56a. Furthermore, the utilization control unit 94a is electrically connected to various sensors, such as a temperature sensor (not shown), provided in the utilization unit 50a, and obtains measurement values ​​from the sensors. The utilization control unit 94b is electrically connected to the utilization expansion valve 54b and the utilization fan 56b. Furthermore, the utilization control unit 94b is electrically connected to various sensors, such as a temperature sensor (not shown), provided in the utilization unit 50b, and obtains measurement values ​​from the sensors.

[0092] The control units 94 a and 94 b are communicably connected to a heat source control unit 92 described later, and function together with the heat source control unit 92 as a control unit 90 that controls the operation of the air-conditioning apparatus 100 .

[0093] The control of various devices of the air-conditioning apparatus 100 by the control unit 90 will be described in the description of the operation of the air-conditioning apparatus 100 .

[0094] (1-2) Heat source unit

[0095] The refrigeration cycle apparatus disclosed herein includes multiple heat source heat exchangers capable of independently switching between a state in which the heat sink (condenser) of the refrigerant is used and a state in which the heat sink (evaporator) of the refrigerant is used. In particular, the heat source unit 10 of the air conditioning apparatus 100 includes two heat source heat exchangers (a first heat source heat exchanger 18a and a second heat source heat exchanger 18b) capable of independently switching between a state in which the heat sink of the refrigerant is used and a state in which the heat sink of the refrigerant is used.

[0096] The heat source unit 10 mainly includes a compressor 12, a first switching valve 16a, a second switching valve 16b, a third switching valve 16c, a fourth switching valve 16d, a first heat source heat exchanger 18a, a second heat source heat exchanger 18b, a first heat source expansion valve 20a, a second heat source expansion valve 20b, a subcooling heat exchanger 22, a subcooling valve 24, a liquid shutoff valve 26, gas shutoff valves 28a and 28b, a storage tank 14, a first heat source fan 17a, a second heat source fan 17b, and a heat source control unit 92. The above-mentioned structure of the heat source unit 10 is housed in a housing 10a of the heat source unit 10.

[0097] The compressor 12, the first switching valve 16a, the second switching valve 16b, the third switching valve 16c, the fourth switching valve 16d, the first heat source heat exchanger 18a, the second heat source heat exchanger 18b, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the subcooling heat exchanger 22, the subcooling valve 24, the liquid shutoff valve 26, the gas shutoff valves 28a and 28b, and the accumulator 14 constitute the refrigerant circuit 40. The above-mentioned components constituting the refrigerant circuit 40 are connected within the heat source unit 10 via pipes P1 to P6 as follows.

[0098] A discharge port 12 b of the compressor 12 , from which the refrigerant compressed by the compressor 12 is discharged, is connected to the first to fourth switching valves 16 a to 16 d via a plurality of branched discharge pipes P2 .

[0099] In addition, it is preferred that a silencer component 25 is provided in the discharge pipe P2 so that the noise accompanying the operation of the first switching valve 16a and the second switching valve 16b is not transmitted to the utilization units 50a and 50b. The discharge pipe P2 constitutes a part of the piping (the discharge pipe P2 and the refrigerant connecting pipes 34 and 36) that connects the first switching valve 16a and the second switching valve 16b to the utilization heat exchangers 52a and 52b. In other words, the discharge pipe P2 is an example of a piping that connects the first switching valve 16a and the second switching valve 16b to the utilization heat exchangers 52a and 52b. The silencer component 25 is, for example, a silencer having an expansion portion. Only one silencer as the silencer component 25 is provided at the following position (refer to Figure 1 ): A position downstream (on the side of the utilization units 50a and 50b) of the position where the discharge pipe P2 extending from the discharge port 12b of the compressor 12 to the first to fourth switching valves 16a and 16d branches into the pipe extending to the first switching valve 16a and the pipe extending to the second switching valve 16b, and a position upstream (on the side of the compressor 12) of the position where the discharge pipe P2 extending from the discharge port 12b of the compressor 12 to the first to fourth switching valves 16a and 16d branches into the pipe extending to the third switching valve 16c and the pipe extending to the fourth switching valve 16d. In another example, a silencer serving as the silencer member 25 may be provided in each of the pipe extending to the third switching valve 16c and the pipe extending to the fourth switching valve 16d (not shown). Alternatively, silencers serving as the silencer members 25 may be provided in the gas refrigerant communication pipes 34 and 36 , which are examples of pipes connecting the first switching valve 16 a and the second switching valve 16 b to the heat exchangers 52 a and 52 b .

[0100] Furthermore, the silencer member 25 may be a weight attached to the discharge pipe P2 and the gas refrigerant communication pipes 34 and 36 instead of a muffler. By attaching the weight to the discharge pipe P2 and the gas refrigerant communication pipes 34 and 36, the noise generated by the operation of the first switching valve 16a and the second switching valve 16b is less likely to propagate to the utilization units 50a and 50b.

[0101] The suction port 12a of the compressor 12, into which the refrigerant to be compressed by the compressor 12 flows, is connected to the first switching valve 16a to the fourth switching valve 16d via a suction pipe P1 that branches into a plurality of branches. The suction pipe P1 is connected to one end of the bypass pipe P6 described later. The suction pipe P1 is provided with a storage tank 14. The storage tank 14 is also arranged in the suction pipe P1 at a portion where a total of four pipes extending from the first switching valve 16a to the fourth switching valve 16d converge into one pipe and are connected to the suction port 12a of the compressor 12. In addition, the storage tank 14 is also arranged in the suction pipe P1 at a position closer to the suction port 12a of the compressor 12 than the confluence position of the bypass pipe P6 to the suction pipe P1.

[0102] The first switching valve 16a is connected to one end (gas side) of the first heat source heat exchanger 18a via a first gas pipe P3a. The second switching valve 16b is connected to one end (gas side) of the second heat source heat exchanger 18b via a first gas pipe P3b.

[0103] The other end (liquid side) of the first heat source heat exchanger 18a and the other end (liquid side) of the second heat source heat exchanger 18b are connected to the liquid shutoff valve 26 via the liquid pipe P4. Furthermore, one end of the liquid pipe P4 is connected to the liquid shutoff valve 26, and at its other end, it branches into two liquid pipes P4a and P4b. One end of the liquid pipe P4a (the end on the opposite side of the branching portion of the liquid pipe P4) is connected to the first heat source heat exchanger 18a, and one end of the liquid pipe P4b (the end on the opposite side of the branching portion of the liquid pipe P4) is connected to the second heat source heat exchanger 18b. The liquid pipe P4a is provided with a first heat source expansion valve 20a. The liquid pipe P4b is provided with a second heat source expansion valve 20b.

[0104] Liquid pipe P4 is connected to the other end of bypass pipe P6, one end of which is connected to suction pipe P1 as described above. Bypass pipe P6 is connected to liquid pipe P4 between the first heat source heat exchanger 18a and the second heat source heat exchanger 18b, which will be described later, and the subcooling heat exchanger 16. Subcooling heat exchanger 16 is arranged so as to straddle liquid pipe P4 and bypass pipe P6. In other words, subcooling heat exchanger 16 is arranged between liquid pipe P4 and bypass pipe P6 so that refrigerant flowing through liquid pipe P4 and refrigerant flowing through bypass pipe P6 flow into subcooling heat exchanger 16, and heat exchange is performed between the refrigerant flowing through liquid pipe P4 and the refrigerant flowing through bypass pipe P6.

[0105] The third switching valve 16c and the gas shutoff valve 28a are connected via the second gas pipe P5a, and the fourth switching valve 16d and the gas shutoff valve 28b are connected via the second gas pipe P5b.

[0106] Hereinafter, various structures of the heat source unit 20 will be described.

[0107] (1-2-1) Compressor

[0108] The compressor 12 compresses the refrigerant using a compression mechanism (not shown). The compressor 12 is a variable capacity inverter compressor (with a variable motor speed). The compressor 12 is, for example, a positive displacement compressor such as a scroll type, but the type of compressor can be determined as appropriate.

[0109] The compressor 12 has a suction port 12a and a discharge port 12b. The compressor 12 compresses the low-pressure gas refrigerant drawn from the suction pipe P1 through the suction port 12a by a compression mechanism, and discharges the compressed high-pressure gas refrigerant to the discharge pipe P2 through the discharge port 12b.

[0110] (1-2-2) First Switching Valve and Second Switching Valve

[0111] The first switching valve 16a is a flow switching mechanism that switches the direction of the refrigerant flowing through the first heat source heat exchanger 18a. The first switching valve 16a is an example of the first switching mechanism or the second switching mechanism in the claims.

[0112] The second switching valve 16b is a flow path switching mechanism that switches the direction of the refrigerant flowing through the second heat source heat exchanger 18b. The second switching valve 16b is an example of the first switching mechanism or the second switching mechanism in the claims.

[0113] In addition, in this embodiment, the case where the first heat source heat exchanger 18a corresponds to the first heat source heat exchanger in the claims, the second heat source heat exchanger 18b corresponds to the second heat source heat exchanger in the claims, the first switching valve 16a corresponds to the first switching mechanism in the claims, and the second switching valve 16b corresponds to the second switching mechanism in the claims is explained as an example.

[0114] However, this is not limited to this, and the first heat source heat exchanger 18a may correspond to the second heat source heat exchanger in the claims, the second heat source heat exchanger 18b may correspond to the first heat source heat exchanger in the claims, the first switching valve 16a may correspond to the second switching mechanism in the claims, and the second switching valve 16b may correspond to the first switching mechanism in the claims.

[0115] The first switching valve 16a switches between a state in which the refrigerant discharged from the discharge port 12b of the compressor 12 flows into the first heat source heat exchanger 18a to function as a radiator and a state in which the refrigerant passing through the first heat source heat exchanger 18a functioning as an evaporator flows into the suction port 12a of the compressor 12.

[0116] In this embodiment, the first switching valve 16a is a four-way switching valve with one of its four ports blocked (see Figure 1).exist Figure 1 In FIG. 1 , a black circle marked on one port of the first switching valve 16a indicates a blocked port. When the first heat source heat exchanger 18a functions as a radiator of the refrigerant, the first switching valve 16a connects the first gas pipe P3a with the discharge pipe P2 (see FIG. 1 ). Figure 1 The first switching valve 16a connects the first gas pipe P3a with the suction pipe P1 when the first heat source heat exchanger 18a functions as an evaporator for the refrigerant (see the solid line in the first switching valve 16a). Figure 1 The first switching valve 16a is shown in dashed line.

[0117] The second switching valve 16b switches between a state in which the refrigerant discharged from the discharge port 12b of the compressor 12 flows into the second heat source heat exchanger 18b to function as a radiator and a state in which the refrigerant passing through the second heat source heat exchanger 18b functioning as an evaporator flows into the suction port 12a of the compressor 12.

[0118] The second switching valve 16b is a four-way switching valve with one of its four ports blocked (see Figure 1 ).exist Figure 1 In FIG. 1 , a black circle marked on one port of the second switching valve 16b indicates a blocked port. When the second heat source heat exchanger 18b functions as a radiator of the refrigerant, the second switching valve 16b connects the first gas pipe P3b with the discharge pipe P2 (see FIG. 1 ). Figure 1 The second switching valve 16b connects the first gas pipe P3b with the suction pipe P1 when the second heat source heat exchanger 18b functions as an evaporator for the refrigerant (see the solid line in the second switching valve 16b). Figure 1 The second switching valve 16b is shown in dashed line.

[0119] Furthermore, the first or second switching mechanism described in the claims need not be a four-way reversing valve with one of its four ports blocked, as in the first switching valve 16a and the second switching valve 16b described above. As long as the refrigerant flow path can be switched as described above, the first switching valve 16a and the second switching valve 16b may be a flow path switching mechanism constructed by connecting multiple valves and piping. Furthermore, the first switching valve 16a and the second switching valve 16b may be a three-way valve.

[0120] (1-2-3) Third switching valve and fourth switching valve

[0121] The third switching valve 16c is a flow path switching mechanism that switches between a state in which the refrigerant discharged from the discharge port 12b of the compressor 12 flows into the heat exchanger 52a and functions as a radiator, and a state in which the refrigerant passes through the heat exchanger 52a and functions as an evaporator and flows into the suction port 12a of the compressor 12.

[0122] In this embodiment, the third switching valve 16c is a four-way switching valve with one of its four ports blocked (see Figure 1 ).exist Figure 1 The black circle marked on one port of the third switching valve 16c indicates a blocked port. When the third switching valve 16c is used to function as a radiator of the refrigerant using the heat exchanger 52a, the second gas pipe P5a is connected to the discharge pipe P2 (see FIG. Figure 1 The third switching valve 16c connects the second gas pipe P5a and the suction pipe P1 when the heat exchanger 52a is used as the evaporator of the refrigerant (see the dotted line in the third switching valve 16c). Figure 1 solid line in the third switching valve 16c).

[0123] The fourth switching valve 16d is a flow path switching mechanism that switches between a state in which the refrigerant discharged from the discharge port 12b of the compressor 12 flows into the heat exchanger 52b and functions as a radiator, and a state in which the refrigerant passes through the heat exchanger 52b and functions as an evaporator and flows into the suction port 12a of the compressor 12.

[0124] In this embodiment, the fourth switching valve 16d is a four-way switching valve with one of its four ports blocked (see Figure 1 ).exist Figure 1 In FIG. 1 , the black circle on one port of the fourth switching valve 16d indicates a blocked port. When the heat exchanger 52b is used as a radiator for the refrigerant, the fourth switching valve 16d connects the second gas pipe P5b with the discharge pipe P2 (see FIG. 1 ). Figure 1 The fourth switching valve 16d allows the second gas pipe P5b to communicate with the suction pipe P1 when the heat exchanger 52b is used as the evaporator for the refrigerant (see the dashed line in the fourth switching valve 16d). Figure 1 4 switching valve 16d in the solid line).

[0125] In addition, the third switching valve 16c and the fourth switching valve 16d are four-way reversing valves in which one of the four ports is blocked, but as long as the flow path of the refrigerant can be switched as described above, a flow path switching mechanism formed by connecting multiple valves and pipes can also be used as an alternative to such a four-way reversing valve.

[0126] (1-2-4) First heat source heat exchanger and second heat source heat exchanger

[0127] The first heat source heat exchanger 18a and the second heat source heat exchanger 18b are, for example, fin-tube heat exchangers composed of a plurality of heat transfer tubes and fins.

[0128] Although not limited, in this embodiment, Figure 3 As shown, a single heat exchanger is divided into two, an upper side and a lower side (the heat exchanger is divided into two so that the refrigerant flowing in the heat transfer tube on the upper side is not directly connected to the refrigerant flowing in the heat transfer tube on the lower side), the upper side is used as the first heat source heat exchanger 18a, and the lower side is used as the second heat source heat exchanger 18b. For example, one end of the heat transfer tube on the upper side that functions as the first heat source heat exchanger 18a is connected to a header connected to the first gas pipe P3a, and the other end of the heat transfer tube on the upper side that functions as the first heat source heat exchanger 18a is connected to a header connected to the liquid pipe P4a. In addition, one end of the heat transfer tube on the lower side that functions as the second heat source heat exchanger 18b is connected to a header connected to the first gas pipe P3b, and the other end of the heat transfer tube on the lower side that functions as the second heat source heat exchanger 18b is connected to a header connected to the liquid pipe P4b. In addition, Figure 3 An example of the shape and structure of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b (heat exchangers used as the first heat source heat exchanger 18a and the second heat source heat exchanger 18b) is conceptually shown, and the shape and structure of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b (heat exchangers used as the first heat source heat exchanger 18a and the second heat source heat exchanger 18b) can be appropriately selected.

[0129] Furthermore, the first heat source heat exchanger 18a and the second heat source heat exchanger 18b may be independent heat exchangers, or the first heat source heat exchanger 18a may be placed on the second heat source heat exchanger 18b.

[0130] Furthermore, the first heat source heat exchanger 18a and the second heat source heat exchanger 18b may be independent heat exchangers, and the first heat source heat exchanger 18a and the second heat source heat exchanger 18b may be arranged horizontally or in a front-to-back arrangement.

[0131] In addition, in this embodiment, the volume of the first heat source heat exchanger 18a (the internal volume of the heat transfer tube constituting the first heat source heat exchanger 18a) and the volume of the second heat source heat exchanger 18b (the internal volume of the heat transfer tube constituting the second heat source heat exchanger 18b) are equal.

[0132] However, the volumes of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b may be different. However, by making the volumes of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b equal, or by making the volumes of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b have similar values, as described later, when one of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b is used as an evaporator for heating, while the other of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b is used as a radiator for defrosting, it is possible to suppress the increase in size of the heat source heat exchangers 18a and 18b and prevent the occurrence of capacity shortages.

[0133] (1-2-5) First Heat Source Fan and Second Heat Source Fan

[0134] The first heat source fan 17a is a fan that primarily supplies air to the first heat source heat exchanger 18a in order to facilitate heat exchange between the air and the refrigerant in the corresponding first heat source heat exchanger 18a. The second heat source fan 17b is a fan that primarily supplies air to the second heat source heat exchanger 18b in order to facilitate heat exchange between the air and the refrigerant in the corresponding second heat source heat exchanger 18b. The first heat source fan 17a and the second heat source fan 17b are variable speed fans that can change their rotational speed according to the desired air volume. The types of fans used as the first heat source fan 17a and the second heat source fan 17b can be appropriately selected.

[0135] The first heat source fan 17a draws air from the air-conditioned space outside the casing 10a and supplies the drawn air mainly to the first heat source heat exchanger 18a. The air that has exchanged heat with the refrigerant in the first heat source heat exchanger 18a is blown out of the casing 10a.

[0136] The second heat source fan 17b draws air from the air-conditioned space outside the casing 10a and supplies the drawn air mainly to the second heat source heat exchanger 18b. The air that has exchanged heat with the refrigerant in the second heat source heat exchanger 18b is blown out of the casing 10a.

[0137] In addition, in this embodiment, the first heat source fan 17a is provided corresponding to the first heat source heat exchanger 18a, and the second heat source fan 17b is provided corresponding to the second heat source heat exchanger 18b, but the present invention is not limited to this configuration. For example, in the air conditioning device 100, instead of providing two heat source fans, a single heat source fan may be provided in common with the first heat source heat exchanger 18a and the second heat source heat exchanger 18b.

[0138] (1-2-6) First Heat Source Expansion Valve and Second Heat Source Expansion Valve

[0139] The first heat source expansion valve 20 a is an example of the first valve or the second valve in the claims, and the second heat source expansion valve 20 b is an example of the second valve or the first valve in the claims.

[0140] In this embodiment, the first heat source heat exchanger 18a corresponds to the first heat source heat exchanger in the claims, the second heat source heat exchanger 18b corresponds to the second heat source heat exchanger in the claims, the first heat source expansion valve 20a corresponds to the first valve in the claims, and the second heat source expansion valve 20b corresponds to the second valve in the claims. However, this is not limiting, and the first heat source heat exchanger 18a may alternatively correspond to the second heat source heat exchanger in the claims, the second heat source heat exchanger 18b may correspond to the first heat source heat exchanger in the claims, the first heat source expansion valve 20a may correspond to the second valve in the claims, and the second heat source expansion valve 20b may correspond to the first valve in the claims.

[0141] The first heat source expansion valve 20a is disposed in the liquid pipe P4a, and the second heat source expansion valve 20b is disposed in the liquid pipe P4b.

[0142] The first and second heat source expansion valves 20a and 20b are electrically operated valves with adjustable openings. They directly regulate the refrigerant flow rate. Furthermore, the first and second heat source expansion valves 20a and 20b reduce the pressure (expand) of the refrigerant passing through them according to their openings.

[0143] (1-2-7) Subcooling heat exchanger and subcooling valve

[0144] The subcooling heat exchanger 22 is arranged in the liquid pipe P4 and the bypass pipe P6 as described above, so that the refrigerant flowing in the bypass pipe P6 and the refrigerant flowing in the liquid pipe P4 exchange heat, thereby cooling (subcooling) the refrigerant flowing in the liquid pipe P4 by the refrigerant flowing in the bypass pipe P6.

[0145] Subcooling valve 24 is located in bypass pipe P6. Specifically, subcooling valve 24 is located between the connection between bypass pipe P6 and liquid pipe P4, and the connection between bypass pipe P6 and subcooling heat exchanger 22. Subcooling valve 24 regulates the flow rate of refrigerant flowing from bypass pipe P6 into subcooling heat exchanger 22 and decompresses (expands) the refrigerant passing through subcooling valve 24.

[0146] (1-2-8) Storage tank

[0147] The accumulator 14 is disposed in the suction pipe P1. The accumulator 14 captures liquid refrigerant mixed with the refrigerant flowing in from the suction pipe P1 and stores it therein, thereby preventing the liquid refrigerant from flowing into the suction port 12a of the compressor 12. The gaseous refrigerant flowing into the accumulator 14 passes through the accumulator 14, flows through the suction pipe P1, and flows into the suction port 12a of the compressor 12.

[0148] (1-2-9) Liquid stop valve and gas stop valve

[0149] The liquid shutoff valve 26 is a shutoff valve that shuts off one end of the liquid pipe P4. The gas shutoff valve 28a is a shutoff valve connected to one end of the second gas pipe P5a. The gas shutoff valve 28b is a shutoff valve connected to one end of the second gas pipe P5b.

[0150] Furthermore, the liquid shutoff valve 26 is connected to the liquid refrigerant communication pipe 32. The gas shutoff valve 28a is connected to the gas refrigerant communication pipe 34. The gas shutoff valve 28b is connected to the gas refrigerant communication pipe 36. The liquid shutoff valve 26, the gas shutoff valve 28a, and the gas shutoff valve 28b are manually opened and closed valves and are normally open.

[0151] (1-2-10) Heat source control unit

[0152] The heat source control unit 92 is a control device that controls the heat source unit 10 and mainly includes a CPU (processor) and a memory.

[0153] The heat source control unit 92 is electrically connected to the compressor 12, the first to fourth switching valves 16a to 16d, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the subcooling valve 24, the first heat source fan 17a, and the second heat source fan 17b. Furthermore, the heat source control unit 92 is electrically connected to sensors (not shown) such as a pressure sensor and a temperature sensor provided within the heat source control unit 92, and acquires measurement data from the sensors. Furthermore, the heat source control unit 92 is communicatively connected to the utilization control units 94a and 94b, and, together with the utilization control units 94a and 94b, functions as the control unit 90 for controlling the operation of the air conditioning apparatus 100.

[0154] The control of the air-conditioning apparatus 100 by the control unit 90 will be described in the description of the operation of the air-conditioning apparatus 100 .

[0155] (2) Operation of air conditioning system

[0156] Hereinafter, the operation of the air-conditioning apparatus 100 will be briefly described.

[0157] In addition to the cooling operation, the first heating operation, the second heating operation, and the third heating operation described below, the air conditioner 100 can also perform simultaneous cooling and heating operation, in which one of the heat exchanger 52a and the heat exchanger 52b is used as a radiator for heating, and the other of the heat exchanger 52a and the heat exchanger 52b is used as an evaporator for cooling. However, to avoid complicating the description, the description of the simultaneous cooling and heating operation is omitted here.

[0158] (2-1) Refrigeration Operation

[0159] Figure 4 The state of the refrigerant circuit 40 of the air conditioner 100 during cooling operation is shown in FIG. Figure 4 In the figure, the heat exchanger functioning as a radiator is hatched, and the heat exchanger functioning as an evaporator is not hatched.

[0160] During cooling operation, the controller 90 controls the first to fourth switching valves 16a to 16d, so that the first switching valve 16a connects the discharge pipe P2 to the first gas pipe P3a, the second switching valve 16b connects the discharge pipe P2 to the first gas pipe P3b, the third switching valve 16c connects the suction pipe P1 to the second gas pipe P5a, and the fourth switching valve 16d connects the suction pipe P1 to the second gas pipe P5b. During cooling operation, the first and second heat source heat exchangers 18a and 18b function as condensers, and the heat exchangers 52a and 52b function as evaporators.

[0161] During cooling operation, the controller 90 appropriately controls the rotation speed of the compressor 12 according to the required capacity of the air conditioner 100. The high-pressure gas refrigerant discharged from the discharge port 12b of the compressor 12 passes through the first switching valve 16a and the second switching valve 16b via the discharge pipe P2, and condenses into high-pressure liquid refrigerant while passing through the first heat source heat exchanger 18a and the second heat source heat exchanger 18b.

[0162] During cooling operation, the controller 90 controls both the first heat source expansion valve 20a and the second heat source expansion valve 20b to be fully open. The controller 90 also controls the opening of the subcooling valve 24 based on the degree of subcooling detected by a sensor (not shown).

[0163] In this specification, the word "detection" is not limited to detection by a single sensor, but also includes the case of calculating a value based on the detection results of multiple sensors.

[0164] Most of the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b passes through the liquid pipe P4 and flows to the liquid refrigerant communication pipe 32. A portion of the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b passes through the bypass pipe P6 and flows to the suction pipe P1. The refrigerant flowing into the subcooling heat exchanger 22 from the liquid pipe P4 exchanges heat with the refrigerant flowing into the subcooling heat exchanger 22 from the bypass pipe P6, thereby being subcooled.

[0165] If Figure 1 For example, the high-pressure liquid refrigerant that has passed through the subcooling heat exchanger 22 further flows through the liquid pipe P4 and, through the liquid refrigerant connecting pipe 32, flows into the two utilization units 50a and 50b. The high-pressure liquid refrigerant flowing into the utilization units 50a and 50b is decompressed upon passing through the utilization expansion valves 54a and 54b, which are controlled to appropriate openings by the control unit 90 based on sensor detection results, and becomes a gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant evaporates in the utilization heat exchangers 52a and 52b, becoming a low-pressure gas refrigerant, thereby cooling the air in the conditioned spaces of the utilization units 50a and 50b. The low-pressure gas refrigerant that has passed through the utilization heat exchanger 52a flows through the gas refrigerant connecting pipe 34 into the second gas pipe P5a, and then flows through the third switching valve 16c into the suction pipe P1. The low-pressure gas refrigerant that has passed through heat exchanger 52b flows through gas refrigerant communication pipe 36 into second gas pipe P5b, passes through fourth switching valve 16d, and flows into suction pipe P1. The low-pressure gas refrigerant that has flowed into suction pipe P1 passes through accumulator 14 and is then drawn into compressor 12 through suction port 12a.

[0166] (2-2) First heating operation

[0167] The first heating operation is an operation for heating the air-conditioned space by using both the heat source heat exchangers 18a and 18b as evaporators.

[0168] Figure 5 The state of the refrigerant circuit 40 of the air conditioner 100 during the first heating operation is shown in FIG. Figure 5 In the figure, the heat exchanger functioning as a radiator is hatched, and the heat exchanger functioning as an evaporator is not hatched.

[0169] During the first heating operation, the controller 90 controls the first through fourth switching valves 16a to 16d so that the first switching valve 16a connects the suction pipe P1 to the first gas pipe P3a, the second switching valve 16b connects the suction pipe P1 to the first gas pipe P3b, the third switching valve 16c connects the discharge pipe P2 to the second gas pipe P5a, and the fourth switching valve 16d connects the discharge pipe P2 to the second gas pipe P5b. During the first heating operation, the first and second heat source heat exchangers 18a and 18b function as evaporators, and the heat exchangers 52a and 52b function as radiators.

[0170] During the first heating operation, the controller 90 appropriately controls the rotational speed of the compressor 12 based on the required capacity of the air conditioner 100. High-pressure gas refrigerant discharged from the compressor 12's discharge port 12b passes through the discharge pipe P2, passes through the third switching valve 16c and the fourth switching valve 16d, and condenses into high-pressure liquid refrigerant in the heat exchangers 52a and 52b. As the high-pressure gas refrigerant becomes high-pressure liquid refrigerant in the heat exchangers 52a and 52b, it heats the air in the air-conditioned spaces of the utilization units 50a and 50b. Furthermore, during the first heating operation, the controller 90 appropriately controls the openings of the expansion valves 54a and 54b based on, for example, detection results from sensors (not shown).

[0171] The high-pressure liquid refrigerant that has passed through the heat exchangers 52a and 52b flows through the liquid refrigerant communication pipe 32 into the heat source unit 10 and flows through the liquid pipe P4. A portion of the high-pressure liquid refrigerant flowing through the liquid pipe P4 flows through the liquid pipe P4a, where it is decompressed upon passing through the first heat source expansion valve 20a, becoming a gas-liquid two-phase refrigerant and then flowing into the first heat source heat exchanger 18a. The remaining portion of the high-pressure liquid refrigerant flowing through the liquid pipe P4 flows through the liquid pipe P4b, where it is decompressed upon passing through the second heat source expansion valve 20b, becoming a gas-liquid two-phase refrigerant and then flowing into the second heat source heat exchanger 18b. Furthermore, during the first heating operation, the controller 90 controls the openings of the first and second heat source expansion valves 20a and 20b based on sensor detection results (e.g., based on the degree of subcooling determined from the sensor detection results). The gas-liquid two-phase refrigerant evaporates in the first heat source heat exchanger 18a and the second heat source heat exchanger 18b, becoming a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the first heat source heat exchanger 18a flows into the first gas pipe P3a, passes through the first switching valve 16a, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing out of the second heat source heat exchanger 18b flows into the first gas pipe P3b, passes through the second switching valve 16b, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing into the suction pipe P1 passes through the accumulator 14 and is then sucked into the compressor 12 through the suction port 12a.

[0172] (2-3) Second heating operation (first defrosting operation)

[0173] Figure 6 The state of the refrigerant circuit 40 of the air conditioner 100 during the second heating operation is shown in FIG. Figure 6 In the figure, the heat exchanger functioning as a radiator is hatched, and the heat exchanger functioning as an evaporator is not hatched.

[0174] The second heating operation simultaneously operates by defrosting the first heat source heat exchanger 18a, which melts frost adhering to the first heat source heat exchanger 18a, while heating the air-conditioned space by operating the second heat source heat exchanger 18b as an evaporator and the heat exchangers 52a and 52b as condensers. This operation allows users of the air conditioner 100 to continue using heating even while the first heat source heat exchanger 18a is being defrosted. Because the second heating operation also defrosts the first heat source heat exchanger 18a, it is sometimes referred to as the first defrost operation below.

[0175] During the second heating operation, the controller 90 controls the first through fourth switching valves 16a, 16d so that the first switching valve 16a connects the discharge pipe P2 to the first gas pipe P3a, the second switching valve 16b connects the suction pipe P1 to the first gas pipe P3b, the third switching valve 16c connects the discharge pipe P2 to the second gas pipe P5a, and the fourth switching valve 16d connects the discharge pipe P2 to the second gas pipe P5b. During the second heating operation, the second heat source heat exchanger 18b functions as an evaporator, and the first heat source heat exchanger 18a and the heat exchangers 52a and 52b function as radiators.

[0176] The high-pressure gas refrigerant discharged from the discharge port 12b of the compressor 12 is delivered to the utilization heat exchangers 52a and 52b through the discharge pipe P2, similarly to the first heating operation. A portion of the high-pressure gas refrigerant passes through the first switching valve 16a and is delivered to the first heat source heat exchanger 18a. The high-pressure gas refrigerant flowing into the first heat source heat exchanger 18a dissipates heat in the first heat source heat exchanger 18a, melting any frost adhering to the first heat source heat exchanger 18a.

[0177] As in the first heating operation, the high-pressure gas refrigerant supplied to the heat exchangers 52a and 52b condenses in the heat exchangers 52a and 52b, transforming into high-pressure liquid refrigerant, thereby heating the air in the air-conditioned space. During the second heating operation, the controller 90 appropriately controls the opening of the expansion valves 54a and 54b based on, for example, detection results from sensors (not shown). The high-pressure liquid refrigerant that has passed through the heat exchangers 52a and 52b flows through the liquid refrigerant connecting pipe 32 into the heat source unit 10 and flows through the liquid pipe P4. The high-pressure liquid refrigerant flowing through the liquid pipe P4 flows into the liquid pipe P4b, where it is decompressed upon passing through the second heat source expansion valve 20b, transforming into a gas-liquid two-phase refrigerant and flowing into the second heat source heat exchanger 18b.

[0178] In addition, the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a flows through the liquid pipe P4a and then flows into the liquid pipe P4b. When passing through the second heat source expansion valve 20b, it is decompressed and becomes a gas-liquid two-phase refrigerant, and flows into the second heat source heat exchanger 18b.

[0179] The gas-liquid two-phase refrigerant flowing into the second heat source heat exchanger 18b evaporates there and becomes low-pressure gas refrigerant. The refrigerant then flows into the first gas pipe P3b, passes through the second switching valve 16b, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing into the suction pipe P1 passes through the accumulator 14 and is then drawn into the compressor 12 through the suction port 12a.

[0180] In addition, control of the compressor 12, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the supercooling valve 24, the first heat source fan 17a, and the second heat source fan 17b in the second heating operation (first defrosting operation) will be described later.

[0181] (2-4) Third heating operation (second defrosting operation)

[0182] Figure 7 The state of the refrigerant circuit 40 of the air conditioner 100 during the third heating operation is shown in FIG. Figure 7 In the figure, the heat exchanger functioning as a radiator is hatched, and the heat exchanger functioning as an evaporator is not hatched.

[0183] In contrast to the second heating operation, the third heating operation performs a defrosting operation, causing the second heat source heat exchanger 18b to function as a condenser to melt frost adhering to the second heat source heat exchanger 18b. Meanwhile, the first heat source heat exchanger 18a functions as an evaporator, and the heat exchangers 52a and 52b function as condensers to heat the air-conditioned space. This operation allows users of the air conditioner 100 to continue using heating while the second heat source heat exchanger 18b is being defrosted. Because the third heating operation also involves defrosting the second heat source heat exchanger 18b, it will sometimes be referred to as the second defrost operation.

[0184] During the third heating operation, the controller 90 controls the first through fourth switching valves 16a, 16d so that the first switching valve 16a connects the intake pipe P1 to the first gas pipe P3a, the second switching valve 16b connects the discharge pipe P2 to the first gas pipe P3b, the third switching valve 16c connects the discharge pipe P2 to the second gas pipe P5a, and the fourth switching valve 16d connects the discharge pipe P2 to the second gas pipe P5b. During the third heating operation, the first heat source heat exchanger 18a functions as an evaporator, and the second heat source heat exchanger 18b and the heat exchangers 52a, 52b function as radiators.

[0185] The high-pressure gas refrigerant discharged from the discharge port 12b of the compressor 12 is delivered to the heat exchangers 52a and 52b through the discharge pipe P2, similarly to the first heating operation. A portion of the high-pressure gas refrigerant passes through the second switching valve 16b and is delivered to the second heat source heat exchanger 18b. The high-pressure gas refrigerant flowing into the second heat source heat exchanger 18b dissipates heat in the second heat source heat exchanger 18b, melting any frost adhering to the second heat source heat exchanger 18b.

[0186] As in the first heating operation, the high-pressure gas refrigerant supplied to the heat exchangers 52a and 52b condenses in the heat exchangers 52a and 52b, transforming into high-pressure liquid refrigerant, thereby heating the air in the air-conditioned space. During the third heating operation, the controller 90 appropriately controls the opening of the expansion valves 54a and 54b based on, for example, detection results from sensors (not shown). The high-pressure liquid refrigerant that has passed through the heat exchangers 52a and 52b flows through the liquid refrigerant communication pipe 32 into the heat source unit 10 and flows through the liquid pipe P4. The high-pressure liquid refrigerant flowing through the liquid pipe P4 flows through the liquid pipe P4a, where it is decompressed upon passing through the first heat source expansion valve 20a, transforming into a gas-liquid two-phase refrigerant and then flowing into the first heat source heat exchanger 18a.

[0187] In addition, the high-pressure liquid refrigerant flowing out of the second heat source heat exchanger 18b flows through the liquid pipe P4b and then flows into the liquid pipe P4a. When passing through the first heat source expansion valve 20a, it is decompressed and becomes a gas-liquid two-phase refrigerant, and flows into the first heat source heat exchanger 18a.

[0188] The gas-liquid two-phase refrigerant flowing into the first heat source heat exchanger 18a is evaporated there and converted into low-pressure gas refrigerant. The refrigerant then flows into the first gas pipe P3a, passes through the first switching valve 16a, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing into the suction pipe P1 passes through the accumulator 14 and is then drawn into the compressor 12 through the suction port 12a.

[0189] In addition, control of the compressor 12, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the supercooling valve 24, the first heat source fan 17a, and the second heat source fan 17b in the third heating operation (second defrosting operation) will be described later.

[0190] (3) Alternating defrosting operation

[0191] During the first heating operation, if the specified defrost conditions are met, the control unit 90 performs an alternating defrost operation. In this alternating defrost operation, the air-conditioning device 100 performs a first defrost operation (second heating operation) to defrost the first heat source heat exchanger 18a, and the air-conditioning device 100 performs a second defrost operation (third heating operation) to defrost the second heat source heat exchanger 18b.

[0192] The air conditioning device 100 switches the operation without stopping the compressor 12 during the alternating defrost operation. Therefore, in the air conditioning device 100, the user can continue to use the heating mode while the first heat source heat exchanger 18a and the second heat source heat exchanger 18b are being defrosted. In addition, the prescribed defrost condition is not limited, but for example, it is that the measurement value of the temperature sensor (not shown) provided in the first heat source heat exchanger 18a and the second heat source heat exchanger 18b is lower than the prescribed temperature for a prescribed period of time. However, the prescribed defrost condition is not limited to this, and the prescribed defrost condition may also be that the measurement value of the temperature sensor (not shown) provided in the first heat source heat exchanger 18a and the second heat source heat exchanger 18b is lower than the prescribed temperature and the first heating operation is carried out for a prescribed period of time.

[0193] Reference Figure 8 , including the control in the transition state of each operation, the control of the compressor 12, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the supercooling valve 24, the first heat source fan 17a and the second heat source fan 17b performed by the control unit 90 during the alternating defrost operation is explained. Figure 8The diagram explains the operation of various devices when the operation of the air-conditioning apparatus 100 is switched in the order of the first heating operation, the first defrosting operation (the second heating operation), the second defrosting operation (the third heating operation), and the first heating operation.

[0194] In addition, here, the description is based on the case where the first and second defrost operations are each performed once during the alternating defrost operation. However, during the alternating defrost operation, either the first or second defrost operation may be performed multiple times. For example, during the alternating defrost operation, the operation of the air conditioner 100 may be switched in the order of the first heating operation, the second defrost operation (the third heating operation), the first defrost operation (the second heating operation), the second defrost operation (the third heating operation), and the first heating operation.

[0195] In addition, in the alternating defrosting operation, the operation of the air conditioner 100 may be switched in the order of the first heating operation, the second defrosting operation (the third heating operation), the first defrosting operation (the second heating operation), and the first heating operation. Figure 3 In this way, when the first heat source heat exchanger 18a is arranged above the second heat source heat exchanger 18b, during the alternating defrost operation, the operation of the air-conditioning device 100 is preferably switched in the order of the first heating operation, the first defrost operation (the second heating operation), the second defrost operation (the third heating operation), and the first heating operation.

[0196] (3-1) First switching valve and second switching valve

[0197] The first switching valve 16a is in a state of connecting the suction pipe P1 and the first gas pipe P3a during the first heating operation. Figure 8 In the first heating operation, when the defrosting condition is met, the control unit 90 controls the first switching valve 16a to connect the discharge pipe P2 to the first gas pipe P3a in order to perform the first defrosting operation. Figure 8 Indicates disconnected state.

[0198] When the first defrosting operation is completed, the controller 90 controls the first switching valve 16a to connect the suction pipe P1 and the first gas pipe P3a (open the valve) in order to start the second defrosting operation.

[0199] Although not limited to this, the control unit 90 determines that the first defrost operation is complete when, for example, the measurement value of a temperature sensor (not shown) provided on the first heat source heat exchanger 18a exceeds a predetermined temperature for a predetermined period of time. Furthermore, although not limited to this, the control unit 90 also terminates the first defrost operation when, for example, a predetermined maximum time Tmax1 has expired, the measurement value of the temperature sensor provided on the first heat source heat exchanger 18a has not exceeded the predetermined temperature for a predetermined period of time.

[0200] Furthermore, when the first heating operation is started after the second defrosting operation is completed, the controller 90 maintains the first switching valve 16a in the closed state (in other words, does not operate the first switching valve 16a).

[0201] The second switching valve 16b is in a state of connecting the suction pipe P1 and the first gas pipe P3b during the first heating operation. Figure 8 In the first heating operation, when the defrosting condition is met, the air conditioner 100 performs the first defrosting operation. However, at this time, the controller 90 maintains the second switching valve 16b in the on state (in other words, does not operate the second switching valve 16b).

[0202] When the first defrosting operation is completed, in order to start the second defrosting operation, the control unit 90 controls the second switching valve 16b so that the second switching valve 16b connects the discharge pipe P2 to the first gas pipe P3b. Figure 8 Indicates disconnected state. Figure 8 In the figure, the first switching valve 16a and the second switching valve 16b operate at the same time, but the present invention is not limited thereto. For example, the control unit 90 may operate the second switching valve 16b at a slightly different time after the operation of the first switching valve 16a.

[0203] When the second defrosting operation is completed, the controller 90 controls the second switching valve 16b to connect the suction pipe P1 and the first gas pipe P3a (open state) in order to start the first heating operation.

[0204] Although not limited to specific conditions, the control unit 90 determines that the second defrost operation is complete when, for example, the measurement value of a temperature sensor (not shown) provided in the second heat source heat exchanger 18b exceeds a predetermined temperature for a predetermined period of time. Furthermore, although not limited to specific conditions, the control unit 90 also terminates the second defrost operation when, for example, a predetermined maximum time Tmax1 has expired, the measurement value of the temperature sensor provided in the second heat source heat exchanger 18b has not exceeded the predetermined temperature for a predetermined period of time.

[0205] (3-2) Compressor

[0206] When the defrosting condition is satisfied during the first heating operation, the controller 90 continues the operation of the compressor 12 and changes the rotation speed of the compressor 12 to a predetermined rotation speed Rc. The predetermined rotation speed Rc is a rotation speed lower than the maximum rotation speed Rmax of the compressor 12.

[0207] The maximum rotation speed Rmax of the compressor 12 is defined as follows: In the first heating operation, the controller 90 changes the rotation speed of the compressor 12 within a predetermined rotation speed range according to the required capacity. The maximum rotation speed within the predetermined rotation speed range is the maximum rotation speed Rmax.

[0208] In short, when the defrost conditions are met during the first heating operation, the controller 90 continues the operation of the compressor 12 while controlling the rotational speed of the compressor 12 so as not to be excessively high. This control makes it easier to suppress the noise generated when the first switching valve 16a is switched from the on state to the off state while the compressor 12 is running.

[0209] Furthermore, the predetermined rotational speed Rc is preferably a value smaller than 1 / 2 of the maximum rotational speed Rmax. From the viewpoint of suppressing noise, the predetermined rotational speed Rc is more preferably 10 to 15% of the maximum rotational speed Rmax.

[0210] Preferably, when the defrost condition is met during the first heating operation, the controller 90 sets the speed of the compressor 12 to the predetermined speed Rc and then switches the first switching valve 16a to the open state after a predetermined time (e.g., one minute) has elapsed. However, this is not limiting. For example, the controller 90 may switch the first switching valve 16a to the open state at the time the speed of the compressor 12 is changed to the predetermined speed Rc. Alternatively, the controller 90 may switch the first switching valve 16a to the open state and then change the speed of the compressor 12 to the predetermined speed Rc.

[0211] The controller 90 changes the rotation speed of the compressor 12 to the second rotation speed Rb during the first defrosting operation. To promote defrosting of the first heat source heat exchanger 18a, the second rotation speed Rb is preferably as large as possible. For example, the second rotation speed Rb is greater than 1 / 2 of the maximum rotation speed Rmax and less than the maximum rotation speed Rmax.

[0212] When the control unit 90 terminates the first defrost operation under the above conditions and switches to the second defrost operation, the control unit 90 continues the operation of the compressor 12 and changes the speed of the compressor 12 to the predetermined speed Rc. As described above, the predetermined speed Rc is a value less than the maximum speed Rmax. Preferably, the predetermined speed Rc is less than 1 / 2 of the maximum speed Rmax. More preferably, the predetermined speed Rc is 10-15% of the maximum speed Rmax from the perspective of noise reduction.

[0213] At the time of transition from the first defrost operation to the second defrost operation, the operation of the compressor 12 continues, and the air conditioning apparatus 100 changes from a state in which the second heat source heat exchanger 18b functions as an evaporator and the first heat source heat exchanger 18a functions as a radiator to a state in which the second heat source heat exchanger 18b functions as a radiator and the first heat source heat exchanger 18a functions as an evaporator. In other words, Figure 8 As shown, when the first defrost operation transitions to the second defrost operation, while the compressor 12 is operating, both the first switching valve 16a and the second switching valve 16b are in operation. Therefore, during the transition from the first defrost operation to the second defrost operation, the switching of the first switching valve 16a and the second switching valve 16b is likely to generate loud noise. By setting the rotational speed of the compressor 12 to the predetermined rotational speed Rc during the transition from the first defrost operation to the second defrost operation, the noise generated when the states of the first switching valve 16a and the second switching valve 16b are switched while the compressor 12 is operating can be easily suppressed.

[0214] Furthermore, by providing the silencer member 25 , the silencer member 25 can also make it difficult for noise generated when the states of the first switching valve 16 a and the second switching valve 16 b are switched to be transmitted to the air-conditioned space.

[0215] In addition, Figure 8 In the example, the predetermined rotational speed Rc at the time of transition from the first defrost operation to the second defrost operation is described as being the same as the predetermined rotational speed Rc at the time of transition from the first heating operation to the first defrost operation. However, this is not limiting. For example, the predetermined rotational speed at the time of transition from the first defrost operation to the second defrost operation may be a value smaller than the predetermined rotational speed at the time of transition from the first heating operation to the first defrost operation.

[0216] Preferably, when the first defrost operation ends, the controller 90 sets the speed of the compressor 12 to a predetermined speed Rc, and then, after a predetermined time (e.g., one minute), switches the first switching valve 16a to the on state and the second switching valve 16b to the off state. Alternatively, when switching from the first defrost operation to the second defrost operation, the controller 90 may wait a longer time (e.g., two minutes) after setting the speed of the compressor 12 to the predetermined speed Rc, compared to when switching from the first heating operation to the first defrost operation, before switching the first switching valve 16a to the on state and the second switching valve 16b to the off state.

[0217] However, the timing of the operation of the first switching valve 16a and the second switching valve 16b is not limited to the above method. For example, the control unit 90 may switch the first switching valve 16a and the second switching valve 16b to the open state at the time when the rotation speed of the compressor 12 is changed to the predetermined rotation speed Rc. Alternatively, for example, the control unit 90 may switch the first switching valve 16a and the second switching valve 16b to the open state and then change the rotation speed of the compressor 12 to the predetermined rotation speed Rc.

[0218] During the second defrosting operation, the controller 90 changes the rotation speed of the compressor 12 to the first rotation speed Ra. To promote defrosting of the first heat source heat exchanger 18a, the first rotation speed Ra is preferably as high as possible. For example, the first rotation speed Ra is greater than the second rotation speed Rb and is equal to or less than the maximum rotation speed Rmax.

[0219] Furthermore, by making the first rotational speed Ra greater than the second rotational speed Rb, the following effects can be achieved. When the second heat source heat exchanger 18b is positioned below the first heat source heat exchanger 18a, as in this embodiment, water used for defrosting in the first heat source heat exchanger 18a could flow into the second heat source heat exchanger 18b and freeze. Therefore, defrosting the second heat source heat exchanger 18b tends to require more heat than defrosting the first heat source heat exchanger 18a. By making the first rotational speed Ra greater than the second rotational speed Rb, defrosting the second heat source heat exchanger 18b is also easier and more reliable.

[0220] However, the present invention is not limited thereto, and the first rotation speed Ra and the second rotation speed Rb may be the same value.

[0221] When the control unit 90 ends the second defrosting operation under the above-mentioned conditions, the control unit 90 continues the operation of the compressor 12 and changes the rotation speed of the compressor 12 to the predetermined rotation speed Rc when switching to the first heating operation. The predetermined rotation speed Rc is as described above.

[0222] Preferably, when the second defrost operation ends, the controller 90 sets the speed of the compressor 12 to the predetermined speed Rc and then switches the second switching valve 16b to the open state after a predetermined time (e.g., one minute) has elapsed. However, this is not limiting. For example, the controller 90 may switch the second switching valve 16b to the open state at the time the speed of the compressor 12 is changed to the predetermined speed Rc. Alternatively, the controller 90 may switch the second switching valve 16b to the open state and then change the speed of the compressor 12 to the predetermined speed Rc.

[0223] (3-3) First Heat Source Expansion Valve and Second Heat Source Expansion Valve

[0224] In the first heating operation, the control unit 90 controls the opening degrees of the first heat source expansion valve 20a and the second heat source expansion valve 20b based on, for example, the degree of subcooling, as described above.

[0225] When the defrosting conditions are met, the controller 90 continues the operation of the compressor 12 and changes the opening of the first heat source expansion valve 20a to opening Op12 and the opening of the second heat source expansion valve 20b to opening Op22. The openings Op12 and Op22 may be the maximum openings.

[0226] Then, when the operation shifts to the first defrosting operation, the controller 90 changes the opening of the first heat source expansion valve 20a corresponding to the first heat source heat exchanger 18a undergoing defrosting to an opening Op11. The opening Op11 is preferably as large as possible. The opening Op11 will be described in detail.

[0227] When the first heat source heat exchanger 18a is used as an evaporator (simply, when the air conditioner 100 uses the first heat source heat exchanger 18a as an evaporator and performs the first heating operation or the third heating operation), the control unit 90 controls the opening of the first heat source expansion valve 20a within a predetermined opening range. Preferably, the opening Op11 is a larger opening than the predetermined opening range. In other words, the opening Op11 is larger than the opening of the first heat source expansion valve 20a when the first heat source heat exchanger 18a is used as an evaporator. The opening Op11 may also be the maximum opening that the first heat source expansion valve 20a can assume.

[0228] Furthermore, when the operation is switched to the first defrosting operation, the control unit 90 controls the opening of the second heat source expansion valve 20b corresponding to the second heat source heat exchanger 18b functioning as an evaporator within a range that is substantially not higher than 1 / 2 of the maximum opening that can be taken, based on, for example, the degree of subcooling. Figure 8 solid line in the figure).

[0229] However, the control unit 90 stops the normal opening control of the second heat source expansion valve 20b (within the range of not more than 1 / 2 of the maximum opening that can be taken) based on the accumulation of liquid refrigerant in the first heat source heat exchanger 18a, and increases the opening of the second heat source expansion valve 20b to an opening larger than the previous opening of the second heat source expansion valve 20b (refer to Figure 8 dashed line in the middle).

[0230] Specifically, when the specified conditions are met, the control unit 90 stops the normal opening control of the second heat source expansion valve 20b and gradually increases the opening of the second heat source expansion valve 20b to an opening larger than the previous opening of the second heat source expansion valve 20b (increased to an opening larger than 1 / 2 of the maximum opening as needed).

[0231] The predetermined condition here is that defrosting of the first heat source heat exchanger 18a is not completed within a predetermined time. For example, the control unit 90 measures the time elapsed since the start of the first defrost operation and, if the first defrost operation is not determined to be complete after a predetermined time T1 (less than the maximum time Tmax1) has elapsed, gradually increases the opening of the second heat source expansion valve 20b.

[0232] Alternatively, the control unit 90 stores the time required for defrosting during the last first defrost operation and whether the first defrost operation can be completed within the maximum time Tmax1, and based on the result, when it is predicted that the defrost of the first heat source heat exchanger 18a cannot be completed within the maximum time Tmax1, the opening of the second heat source expansion valve 20b is gradually increased at a time point after the specified time T1 (<maximum time Tmax1) has passed.

[0233] By performing such control, the refrigerant easily flows through the second heat source heat exchanger 18b. Thus, even if liquid refrigerant accumulates in the first heat source heat exchanger 18a during defrosting, the liquid refrigerant is easily discharged out of the first heat source heat exchanger 18a. As a result, the time required to defrost the first heat source heat exchanger 18a can be shortened, and the amount of melted frost remaining in the first heat source heat exchanger 18a can be suppressed.

[0234] When the first defrost operation ends, the controller 90 continues the operation of the compressor 12 and changes the opening of the first heat source expansion valve 20a to opening Op12 and the opening of the second heat source expansion valve 20b to opening Op22. As described above, the openings Op12 and Op22 may be the maximum openings.

[0235] Then, when the second defrosting operation is switched, the control unit 90 changes the opening of the second heat source expansion valve 20b corresponding to the second heat source heat exchanger 18b undergoing defrosting to an opening Op21. The opening Op21 is preferably as large as possible. The opening Op21 will be described in detail.

[0236] When the second heat source heat exchanger 18b is used as an evaporator (simply, when the air conditioner 100 uses the second heat source heat exchanger 18b as an evaporator and performs the first heating operation or the second heating operation), the control unit 90 controls the opening of the second heat source heat exchanger 18b within a predetermined opening range. Preferably, the opening Op21 is a larger opening than the predetermined opening range. In other words, the opening Op21 is larger than the opening of the second heat source expansion valve 20b when the second heat source heat exchanger 18b is used as an evaporator. The opening Op21 may also be the maximum opening that the second heat source expansion valve 20b can adopt.

[0237] Furthermore, when the second defrosting operation is switched, the control unit 90 controls the opening of the first heat source expansion valve 20a corresponding to the first heat source heat exchanger 18a functioning as an evaporator within a range that is substantially not higher than 1 / 2 of the maximum opening that can be taken, based on, for example, the degree of subcooling. Figure 8 solid line in the figure).

[0238] However, the control unit 90 stops the normal opening control of the first heat source expansion valve 20a (within the range of not more than 1 / 2 of the maximum opening that can be taken) based on the accumulation of liquid refrigerant in the second heat source heat exchanger 18b, and increases the opening of the first heat source expansion valve 20a to an opening larger than the previous opening of the first heat source expansion valve 20a (refer to Figure 8 dashed line in the middle).

[0239] Specifically, when the specified conditions are met, the control unit 90 stops the normal opening control of the first heat source expansion valve 20a and gradually increases the opening of the first heat source expansion valve 20a to an opening larger than the previous opening of the first heat source expansion valve 20a (increased to an opening larger than 1 / 2 of the maximum opening as needed).

[0240] The predetermined condition is that defrosting of the second heat source heat exchanger 18b is not completed within a predetermined time. For example, the control unit 90 measures the time elapsed since the start of the second defrost operation and gradually increases the opening of the first heat source expansion valve 20a if the second defrost operation is not determined to be complete after a predetermined time T2 (less than the maximum time Tmax2) has elapsed.

[0241] Alternatively, the control unit 90 stores the time required for defrosting during the last second defrost operation and whether the second defrost operation can be completed within the maximum time Tmax2, and based on the result, when it is predicted that the defrost of the second heat source heat exchanger 18b cannot be completed within the maximum time Tmax2, the opening of the first heat source expansion valve 20a is gradually increased at the time point when the specified time T2 (<maximum time Tmax2) has passed.

[0242] By performing such control, the refrigerant easily flows through the first heat source expansion valve 20a. Therefore, even if liquid refrigerant accumulates in the second heat source heat exchanger 18b undergoing defrosting, the liquid refrigerant is easily discharged out of the second heat source heat exchanger 18b. As a result, the time required to defrost the second heat source heat exchanger 18b can be shortened, and any remaining frost in the second heat source heat exchanger 18b can be suppressed.

[0243] When the second defrost operation ends, the controller 90 continues the operation of the compressor 12 and changes the opening of the first heat source expansion valve 20a to opening Op12 and the opening of the second heat source expansion valve 20b to opening Op22. The openings Op12 and Op22 may be the maximum openings.

[0244] The opening degree control of the first heat source expansion valve 20a and the second heat source expansion valve 20b by the controller 90 after the start of the first heating operation is as described above.

[0245] (3-4) Subcooling valve

[0246] The subcooling valve 24 is an example of a bypass valve in the claims.

[0247] The control unit 90 closes the subcooling valve 24 during the first heating operation, but controls the subcooling valve 24 to a predetermined opening Op31 during the first and second defrosting operations, so that part of the refrigerant flowing from the heat exchangers 52a and 52b is bypassed to the suction pipe P1.

[0248] However, the control unit 90 increases the opening of the subcooling valve 24 compared to the opening Op31 based on the accumulation of liquid refrigerant in the first heat source heat exchanger 18a undergoing defrosting, or based on the accumulation of liquid refrigerant in the second heat source heat exchanger 18b undergoing defrosting. Specifically, the control unit 90 increases the opening of the subcooling valve 24 compared to the opening Op31 when a predetermined condition is satisfied during the first defrosting operation or the second defrosting operation.

[0249] The predetermined condition here is that the first or second defrost operation is not completed within the predetermined time. The control unit 90, for example, measures the time elapsed from the start of the first defrost operation and, if it is determined that the first defrost operation is not completed after a predetermined time T1' (less than the maximum time Tmax1) has elapsed, or measures the time elapsed from the start of the second defrost operation and, if it is determined that the second defrost operation is not completed after a predetermined time T2' (less than the maximum time Tmax2) has elapsed, increases the opening of the subcooling valve 24 relative to the opening Op31. Alternatively, the control unit 90 stores the time required for defrosting during the last first defrost operation and the second defrost operation, and whether the first defrost operation and the second defrost operation can be completed within the maximum time Tmax1 and Tmax, and based on the result, when it is predicted that the first defrost operation cannot be completed within the maximum time Tmax1 and the second defrost operation cannot be completed within the maximum time Tmax2, if it is the first defrost operation, the opening of the subcooling valve 24 is increased from the opening Op31 at the time point after the specified time T1' (<maximum time Tmax1) has passed, and if it is the second defrost operation, the opening of the subcooling valve 24 is increased from the opening Op31 at the time point after the specified time T2' (<maximum time Tmax2) has passed.

[0250] By performing such control, even if liquid refrigerant accumulates in the heat source heat exchangers 18a and 18b undergoing defrosting, the liquid refrigerant is easily discharged out of the heat source heat exchangers 18a and 18b. As a result, the time required to defrost the heat source heat exchangers 18a and 18b can be shortened, and the amount of melted frost remaining in the heat source heat exchangers 18a and 18b can be suppressed.

[0251] In another embodiment, the control unit 90 may substantially close the supercooling valve 24 during the first and second defrost operations. Furthermore, the control unit 90 may control the supercooling valve 24 to open when the aforementioned predetermined conditions are met during the first or second defrost operations.

[0252] (3-5) First heat source fan and second heat source fan

[0253] When the heat source heat exchangers 18a and 18b are used as evaporators, the control unit 90 controls the rotation speeds of the heat source fans 17a and 17b corresponding to the heat source heat exchangers 18a and 18b according to the performance required of the air conditioner 100.

[0254] Furthermore, in the first and second defrosting operations, when defrosting the heat source heat exchangers 18a and 18b, the controller 90 preferably stops the heat source fans 17a and 17b corresponding to the heat source heat exchangers 18a and 18b to be defrosted.

[0255] (4) Characteristics

[0256] Hereinafter, an air conditioner 100 as an example of the refrigeration cycle device of the present disclosure will be described, taking as an example a case where the first heat source heat exchanger 18a corresponds to the first heat source heat exchanger in the claims and the second heat source heat exchanger 18b corresponds to the second heat source heat exchanger in the claims.

[0257] However, as previously mentioned, it is also possible to replace the first heat source heat exchanger 18a with the second heat source heat exchanger in the claims, and the second heat source heat exchanger 18b with the first heat source heat exchanger in the claims. In addition, when such a replacement is performed, it is also necessary to appropriately replace the first switching mechanism, the second switching mechanism, the first valve, the second valve, etc.

[0258] (4-1)

[0259] The air conditioning apparatus 100 includes a compressor 12, a first heat source heat exchanger 18a as an example of a first heat source heat exchanger, a second heat source heat exchanger 18b as an example of a second heat source heat exchanger, a first switching valve 16a as an example of a first switching mechanism, a second switching valve 16b as an example of a second switching mechanism, and a controller 90. The first switching valve 16a switches between a state in which refrigerant discharged from the discharge port 12b of the compressor 12 flows into the first heat source heat exchanger 18a and functions as a radiator, and a state in which refrigerant that has passed through the first heat source heat exchanger 18a and functions as an evaporator flows into the intake port 12a of the compressor 12. The second switching valve 16b switches between a state in which refrigerant discharged from the discharge port 12b of the compressor 12 flows into the second heat source heat exchanger 18b and functions as a radiator, and a state in which refrigerant that has passed through the second heat source heat exchanger 18b and functions as an evaporator flows into the intake port 12a of the compressor 12. The controller 90 controls the operation of the compressor 12, the first switching mechanism 16a, and the second switching mechanism 16b. The controller 90 continues the operation of the compressor 12 and changes the state from one in which the second heat source heat exchanger 18b functions as an evaporator and the first heat source heat exchanger 18a functions as a radiator (a first defrost operation state) to one in which the second heat source heat exchanger 18b functions as a radiator and the first heat source heat exchanger 18a functions as an evaporator (a second defrost operation state). The rotational speed of the compressor 12 during this change is a predetermined rotational speed Rc that is less than the maximum rotational speed Rmax of the compressor 12.

[0260] In the air conditioning apparatus 100, when the functions of the heat source heat exchangers 18a and 18b are switched while the compressor 12 continues to operate, the rotation speed of the compressor 12 is suppressed below the maximum rotation speed Rmax. Therefore, noise associated with the operation of the switching valves 16a and 16b can be suppressed.

[0261] (4-2)

[0262] In the air-conditioning apparatus 100 , the predetermined rotation speed Rc is smaller than ½ of the maximum rotation speed Rmax.

[0263] In the air conditioning apparatus 100, when the functions of the heat source heat exchangers 18a and 18b are switched while the compressor 12 continues to operate, the rotation speed of the compressor 12 is suppressed to be lower than 1 / 2 of the maximum rotation speed Rmax, thereby suppressing noise associated with the operation of the switching valves 16a and 16b.

[0264] (4-3)

[0265] In the air conditioning apparatus 100, the control unit 90 continues the operation of the compressor 12 and changes the state from one in which both the first heat source heat exchanger 18a and the second heat source heat exchanger 18b function as evaporators (a first heating operation state) to one in which one of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b functions as a radiator (a first defrost operation state or a second defrost operation state). The rotational speed of the compressor 12 during this change is a rotational speed less than the maximum rotational speed Rmax of the compressor 12.

[0266] In the air-conditioning device 100, when the function of one of the heat source heat exchangers 18a and 18b, which act as an evaporator, is switched to a radiator while continuing the operation of the compressor 12, the rotation speed of the compressor 12 is also suppressed to be lower than the maximum rotation speed Rmax, thereby suppressing the noise associated with the operation of the switching valves 16a and 16b.

[0267] (4-4)

[0268] The air conditioning device 100 includes heat exchangers 52a and 52b, an exhaust pipe P2 as an example of piping, and a muffler 25. The exhaust pipe P2 connects the first and second switching valves 16a and 16b to the heat exchangers 52a and 52b (the exhaust pipe P2 is part of the piping connecting the first and second switching valves 16a and 16b to the heat exchangers 52a and 52b). The muffler 25 is provided on the exhaust pipe P2.

[0269] In the air conditioning apparatus 100, by installing the silencer member 25 in the discharge pipe P2, it is possible to suppress the propagation of noise to the space where the heat exchangers 52a and 52b are installed (for example, the air-conditioned space when air conditioning is performed using the heat exchanger) or the space nearby.

[0270] (4-5)

[0271] The air conditioning apparatus 100 includes a housing 10a that houses a first heat source heat exchanger 18a, a second heat source heat exchanger 18b, and a first switching valve 16a and a second switching valve 16b. A single muffler member 25 is provided in the housing 10a.

[0272] In the air conditioning apparatus 100 , the single silencer member 25 can suppress the propagation of noise to the space where the heat exchangers 52 a and 52 b are installed, while suppressing an increase in the number of components.

[0273] (4-6)

[0274] The air conditioning apparatus 100 includes a first heat source expansion valve 20a, an example of a first valve that regulates the flow rate of refrigerant flowing through the first heat source heat exchanger 18a, and a second heat source expansion valve 20b, an example of a second valve that regulates the flow rate of refrigerant flowing through the second heat source heat exchanger 18b. A controller 90 controls the operation of the first heat source expansion valve 20a and the second heat source expansion valve 20b. When defrosting the second heat source heat exchanger 18b by using the first heat source heat exchanger 18a as an evaporator and the second heat source heat exchanger 18b as a radiator, the controller 90 opens the second heat source expansion valve 20b wider than when the second heat source heat exchanger 18b is used as an evaporator.

[0275] During defrosting, if liquid refrigerant accumulates in the second heat source heat exchanger 18b, the time required to defrost the second heat source heat exchanger 18b may be prolonged, and there is a risk of residual melted frost. To address this issue, in this air conditioning apparatus 100, the opening of the second heat source expansion valve 20b corresponding to the first heat source heat exchanger 18a undergoing defrosting is larger than when the second heat source heat exchanger 18b is used as an evaporator. This reduces the likelihood of liquid refrigerant accumulating in the second heat source heat exchanger 18b during defrosting. Consequently, this air conditioning apparatus 100 can shorten the time required for defrosting and prevent residual melted frost.

[0276] (4-7)

[0277] In the air conditioning apparatus 100, the control unit 90 increases the opening of the first heat source expansion valve 20a if a predetermined condition is satisfied when defrosting the second heat source heat exchanger 18b by using the first heat source heat exchanger 18a as an evaporator and the second heat source heat exchanger 18b as a radiator.

[0278] When the second heat source heat exchanger 18b is used as a radiator and the first heat source heat exchanger 18a is used as an evaporator, a portion of the refrigerant passing through the second heat source heat exchanger 18b is transferred to the first heat source heat exchanger 18a. In this air conditioning apparatus 100, the opening of the second heat source expansion valve 20b is increased when specified conditions are met. This facilitates the flow of refrigerant through the first heat source heat exchanger 18a. Consequently, even if liquid refrigerant accumulates within the second heat source heat exchanger 18b during defrosting, it is easily discharged outside the second heat source heat exchanger 18b. As a result, this air conditioning apparatus 100 can shorten the time required to defrost the second heat source heat exchanger 18b and prevent the accumulation of melted frost in the second heat source heat exchanger 18b.

[0279] (4-8)

[0280] The air conditioning device 100 includes a first refrigerant pipe (liquid pipe P4 and liquid refrigerant connecting pipe 32), an intake pipe P1, a bypass pipe P6, and a subcooling valve 24, which is an example of a bypass valve. The first heat source heat exchanger 18a and the second heat source heat exchanger 18b are connected in parallel to one end of the first refrigerant pipe, and the other end of the first refrigerant pipe is connected to heat exchangers 52a and 52b. The intake pipe P2 is connected to the intake port 12a of the compressor 12. The bypass pipe P6 connects the first refrigerant pipe and the intake pipe P1. The subcooling valve 24 is provided in the bypass pipe P6. The control unit 90 controls the operation of the subcooling valve 24. When the first heat source heat exchanger 18a is used as an evaporator and the second heat source heat exchanger 18b is used as a radiator to defrost the second heat source heat exchanger 18b, the control unit 90 opens the closed subcooling valve 24 or increases the opening degree of the opened subcooling valve 24 if specified conditions are met.

[0281] In the air conditioning apparatus 100, by opening the closed subcooling valve 24 or increasing the opening degree of the opened subcooling valve 24, a portion of the refrigerant flowing into the first heat source heat exchanger 18a flows through the bypass pipe P6. Therefore, even if liquid refrigerant accumulates in the second heat source heat exchanger 18b undergoing defrosting, the liquid refrigerant can be easily discharged out of the second heat source heat exchanger 18b. As a result, in the air conditioning apparatus 100, the time required for defrosting the second heat source heat exchanger 18b can be shortened, and the amount of melted frost remaining in the second heat source heat exchanger 18b can be suppressed.

[0282] (4-9)

[0283] In the air conditioning apparatus 100, the predetermined condition in (4-8) and (4-9) is that defrosting of the second heat source heat exchanger 18b is not completed within a predetermined time.

[0284] From the perspective of defrosting efficiency, it is preferable not to excessively open the first heat source expansion valve 20a and the subcooling valve 24. However, if liquid refrigerant accumulates in the second heat source heat exchanger 18b, as described above, the time required for defrosting may be prolonged, and melted frost may remain.

[0285] In the air conditioning device 100, when defrosting is not completed within the specified time, the openings of the first heat source expansion valve 20 and the supercooling valve 24 are increased, thereby suppressing a decrease in defrosting efficiency, and suppressing a prolonged defrosting time and residual melted frost.

[0286] (5) Modification

[0287] The following describes modifications of the above embodiment. The following modifications can be combined as appropriate unless they are inconsistent with each other.

[0288] (5-1) Modification A

[0289] In the above embodiment, the air conditioning device 100 includes only one compressor, but multiple compressors may be provided. For example, the air conditioning device 100 may include two compressors, with the discharge pipe extending from the discharge port of one compressor connected to the first switching valve 16a, and the discharge pipe extending from the discharge port of the other compressor connected to the second switching valve 16b.

[0290] (5-2) Modification B

[0291] In the above embodiment, the heat source unit 10 is provided with the third switching valve 16c and the fourth switching valve 16d for the purpose of switching the functions of the heat exchangers 52a and 52b. However, the present invention is not limited to the above embodiment. Instead of providing the third switching valve 16c and the fourth switching valve 16d in the heat source unit 10, a flow path switching unit for switching the functions of the heat exchangers 52a and 52b may be provided separately for each of the utilization units 50a and 50b.

[0292] (5-3) Modification C

[0293] In the above embodiment, the subcooling valve 24 is used as a bypass valve, but it may be that in the refrigeration cycle device, in addition to the subcooling valve 24, a bypass valve is also provided in a bypass pipe different from the bypass pipe P6 connecting the first refrigerant pipe (liquid pipe P4 and liquid refrigerant connecting pipe 32) and the suction pipe S1.

[0294] (5-4) Modification D

[0295] In the above embodiment, the first heat source expansion valve 20a is set in the liquid pipe P4a to regulate the flow of refrigerant passing through the first heat source heat exchanger 18a, and the second heat source expansion valve 20b is set in the liquid pipe P4b to regulate the flow of refrigerant passing through the second heat source heat exchanger 18b.

[0296] However, the present invention is not limited to such a correspondence. For example, the regulating valve 21a may be provided on the first gas pipe P3a in order to directly regulate the flow rate of the refrigerant passing through the first heat source heat exchanger 18a, and the regulating valve 21b may be provided on the first gas pipe P3b in order to directly regulate the flow rate of the refrigerant passing through the second heat source heat exchanger 18b (see FIG. Figure 9 The regulating valves 21a and 21b are, for example, electric valves with variable opening degrees.

[0297] exist Figure 9 In the air conditioning apparatus 100, the controller 90 may control only the opening of the regulating valve 21a to regulate the flow rate of refrigerant passing through the first heat source heat exchanger 18a, or may control both the opening of the regulating valve 21a and the opening of the first heat source expansion valve 20a to regulate the flow rate of refrigerant passing through the first heat source heat exchanger 18a. Furthermore, the controller 90 may control only the opening of the regulating valve 21b to regulate the flow rate of refrigerant passing through the second heat source heat exchanger 18b, or may control both the opening of the regulating valve 21b and the opening of the second heat source expansion valve 20b to regulate the flow rate of refrigerant passing through the second heat source heat exchanger 18b.

[0298] (5-5) Modification E

[0299] As an air conditioning device of refrigeration cycle device, it can also be Figure 10 The air conditioner 100A shown here includes a utilization unit 150 instead of the utilization units 50a and 50b of the above embodiment. Figure 10 , only one usage unit 150 is shown. However, the present invention is not limited thereto, and the air-conditioning apparatus 100A may include a plurality of usage units 150, and the plurality of usage units 150 may be connected in parallel in the refrigerant circuit 40A.

[0300] The main difference between the air conditioning apparatus 100A having utilization unit 150 and the air conditioning apparatus 100 of the above-described embodiment having utilization units 50a and 50b is that, in addition to being able to perform cooling and heating operations, it can also perform reheat dehumidification operation. Reheat dehumidification operation dehumidifies the air conditioned space of utilization unit 150 while suppressing overcooling of the air in the conditioned space.

[0301] Hereinafter, the main differences between the air-conditioning apparatus 100A and the air-conditioning apparatus 100 of the above-described embodiment, namely, the configuration of the utilization unit 150 and the operation of the air-conditioning apparatus 100A will be described.

[0302] Utilization unit 150 is connected to heat source unit 10 via refrigerant communication pipes 32, 34, and 36, and constitutes a portion of refrigerant circuit 40A. Utilization unit 150 is installed, for example, indoors (air-conditioned space) in a building or behind a ceiling of the air-conditioned space.

[0303] The utilization unit 150 mainly includes a first heat exchanger 152 a , a second heat exchanger 152 b , a first expansion valve 154 a , a second expansion valve 154 b , a utilization fan 156 , and a utilization control unit 94A.

[0304] The heat exchangers 152a and 152b are, for example, fin-and-tube heat exchangers composed of a plurality of heat transfer tubes and fins. In the heat exchangers 152a and 152b, the refrigerant flowing through the heat exchangers 152a and 152b exchanges heat with the air in the air-conditioned space.

[0305] One end (liquid side) of the first heat exchanger 152a is connected to the liquid refrigerant communication tube 32 via a pipe, and the other end (gas side) thereof is connected to the gas refrigerant communication tube 36 via a pipe. One end (liquid side) of the second heat exchanger 152b is connected to the liquid refrigerant communication tube 32 via a pipe, and the other end (gas side) thereof is connected to the gas refrigerant communication tube 34 via a pipe.

[0306] The first heat exchanger 152a functions as a radiator (condenser) or an evaporator (heat absorber) of the refrigerant, depending on the connection state of the piping achieved by the fourth switching valve 16d. The second heat exchanger 152b functions as a radiator (condenser) or an evaporator (heat absorber) of the refrigerant, depending on the connection state of the piping achieved by the third switching valve 16c.

[0307] The first expansion valve 154a is disposed in the pipe connecting the first heat exchanger 152a and the liquid refrigerant connecting pipe 32 (the pipe located closer to the first heat exchanger 152a than the branching portion where the pipe connected to the liquid refrigerant connecting pipe 32 branches off). The second expansion valve 154b is disposed in the pipe connecting the second heat exchanger 152b and the liquid refrigerant connecting pipe 32 (the pipe located closer to the second heat exchanger 152b than the branching portion where the pipe connected to the liquid refrigerant connecting pipe 32 branches off).

[0308] The expansion valves 154a and 154b are electrically operated valves whose openings can be adjusted. The expansion valves 154a and 154b adjust the flow rate of the refrigerant. Furthermore, the expansion valves 154a and 154b reduce the pressure (expand) of the refrigerant passing through them according to their openings.

[0309] In order to promote heat exchange between the air and the refrigerant in the heat exchangers 152a and 152b, the fan 156 draws air from the air-conditioned space and supplies it to the heat exchangers 152a and 152b. The air that has undergone heat exchange with the refrigerant in the heat exchangers 152a and 152b is then blown out to the air-conditioned space. In the direction of the airflow generated by the fan, the second heat exchanger 152b is positioned downstream of the first heat exchanger 152a. Therefore, the air that has passed through the first heat exchanger 152a (the air that has undergone heat exchange with the refrigerant in the first heat exchanger 152a) is transported to the second heat exchanger 152b. The fan 156 is a variable speed fan. The type of fan used as the fan 156 can be appropriately selected.

[0310] The use control unit 94A functions as the control unit 90 for controlling the operation of the air conditioning apparatus 100A together with the heat source control unit 92. The physical structure of the use control unit 94A is the same as that of the use control units 94a and 94b in the above embodiment, and therefore, description thereof will be omitted.

[0311] During cooling operation, the controller 90 controls the first to fourth switching valves 16a to 16d so that the first and second heat exchangers 152a and 152b of the utilization unit 150 function as evaporators and the heat source heat exchangers 18a and 18b function as condensers. The control of the various devices by the controller 90 is similar to that during cooling operation in the above-described embodiment, and therefore, a detailed description thereof will be omitted.

[0312] The flow of the refrigerant in the refrigerant circuit 40A during the cooling operation will be briefly described.

[0313] The high-pressure gas refrigerant discharged from the discharge port 12b of the compressor 12 passes through the first and second switching valves 16a and 16b via the discharge pipe P2 and is condensed into high-pressure liquid refrigerant while passing through the first and second heat source heat exchangers 18a and 18b.

[0314] Most of the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b passes through the liquid pipe P4 and flows to the liquid refrigerant communication pipe 32. A portion of the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b passes through the bypass pipe P6 and flows to the suction pipe P1. The refrigerant flowing into the subcooling heat exchanger 22 from the liquid pipe P4 exchanges heat with the refrigerant flowing into the subcooling heat exchanger 22 from the bypass pipe P6, thereby being subcooled.

[0315] After passing through the subcooling heat exchanger 22, the high-pressure liquid refrigerant further flows through the liquid pipe P4 and flows through the liquid refrigerant connecting pipe 32 into the utilization unit 150. The high-pressure liquid refrigerant flowing into the utilization unit 150 is decompressed upon passing through the expansion valves 154a and 154b, which are controlled to appropriate openings by the controller 90 based on sensor detection results, and becomes a two-phase gas-liquid refrigerant. As the two-phase gas-liquid refrigerant evaporates in the heat exchangers 152a and 152b, becoming a low-pressure gas refrigerant, it cools the air in the conditioned space of the utilization unit 150. The low-pressure gas refrigerant that has passed through the first heat exchanger 152a flows through the gas refrigerant connecting pipe 36 into the second gas pipe P5b, passes through the fourth switching valve 16d, and flows into the suction pipe P1. The low-pressure gas refrigerant that has passed through the second heat exchanger 152b flows through the gas refrigerant connecting pipe 34 into the second gas pipe P5a, passes through the third switching valve 16c, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing into the suction pipe P1 passes through the accumulator 14 and is then sucked into the compressor 12 through the suction port 12 a .

[0316] During the reheat dehumidification operation, the controller 90 controls the first to fourth switching valves 16a to 16d so that the first heat exchanger 152a functions as an evaporator, the second heat exchanger 152b functions as a condenser, and the heat source heat exchangers 18a and 18b function as condensers.

[0317] The main flow of the refrigerant in the refrigerant circuit 40A during the reheat dehumidification operation will be briefly described.

[0318] During reheat dehumidification operation, a portion of the high-pressure gas refrigerant discharged from the discharge port 12b of the compressor 12 passes through the discharge pipe P2, through the first switching valve 16a and the second switching valve 16b, and condenses into high-pressure liquid refrigerant while passing through the first heat source heat exchanger 18a and the second heat source heat exchanger 18b, as in the cooling operation. Furthermore, a portion of the high-pressure gas refrigerant discharged from the discharge port 12b of the compressor 12 passes through the discharge pipe P2, through the third switching valve 16c, and condenses into high-pressure liquid refrigerant while passing through the second heat exchanger 152b.

[0319] Most of the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b passes through the liquid pipe P4 and flows to the liquid refrigerant communication pipe 32. A portion of the high-pressure liquid refrigerant flowing out of the first heat source heat exchanger 18a and the second heat source heat exchanger 18b passes through the bypass pipe P6 and flows to the suction pipe P1. The refrigerant flowing into the subcooling heat exchanger 22 from the liquid pipe P4 exchanges heat with the refrigerant flowing into the subcooling heat exchanger 22 from the bypass pipe P6, thereby being subcooled.

[0320] The high-pressure liquid refrigerant, supercooled by passing through the subcooling heat exchanger 22, further flows through the liquid pipe P4, passes through the liquid refrigerant connecting pipe 32, and flows into the first heat exchanger 152a of the utilization unit 150. Furthermore, the high-pressure liquid refrigerant condensed by passing through the second heat exchanger 152b merges with the high-pressure liquid refrigerant flowing from the heat source unit 10 and flows into the first heat exchanger 152a. Furthermore, the refrigerant flowing into the first heat exchanger 152a is decompressed upon passing through the first expansion valve 154a, whose opening is appropriately controlled by the controller 90 based on sensor detection results, and becomes a gas-liquid two-phase refrigerant. As the gas-liquid two-phase refrigerant evaporates in the first heat exchanger 152a and becomes a low-pressure gas refrigerant, it cools the air supplied to the air-conditioned space by the fan 156, condensing (condensing) the water vapor in the air and thus dehumidifying it. The air dehumidified in the first heat exchanger 152a is heated (reheated) in the second heat exchanger 152b functioning as a condenser, and is then blown out to the air-conditioning target space.

[0321] The low-pressure gas refrigerant that has passed through the first heat exchanger 152a flows through the gas refrigerant communication pipe 36 into the second gas pipe P5b, passes through the fourth switching valve 16d, and flows into the suction pipe P1. The low-pressure gas refrigerant that has flowed into the suction pipe P1 passes through the accumulator 14 and is then sucked into the compressor 12 through the suction port 12a.

[0322] During heating operation (first heating operation), the controller 90 controls the first through fourth switching valves 16a through 16d so that the first and second heat exchangers 152a and 152b of the utilization unit 150 function as condensers, and the heat source heat exchangers 18a and 18b function as evaporators. The control of the various devices by the controller 90 is similar to that during heating operation in the aforementioned embodiment, and therefore, a detailed description thereof will be omitted.

[0323] The flow of the refrigerant in the refrigerant circuit 40A during the heating operation (first heating operation) will be briefly described.

[0324] High-pressure gas refrigerant discharged from discharge port 12b of compressor 12 passes through discharge pipe P2, passes through third switching valve 16c and fourth switching valve 16d, and condenses into high-pressure liquid refrigerant in heat exchangers 152b and 152a. As the high-pressure gas refrigerant is converted into high-pressure liquid refrigerant in heat exchangers 152a and 152b, the refrigerant heats the air in the air-conditioned space of utilization unit 150.

[0325] The high-pressure liquid refrigerant that has passed through the heat exchangers 152a and 152b flows through the liquid refrigerant communication pipe 32 into the heat source unit 10 and flows through the liquid pipe P4. A portion of the high-pressure liquid refrigerant flowing through the liquid pipe P4 flows through the liquid pipe P4a. It is decompressed when passing through the first heat source expansion valve 20a, becoming a gas-liquid two-phase refrigerant, and then flows into the first heat source heat exchanger 18a. The remaining portion of the high-pressure liquid refrigerant flowing through the liquid pipe P4 flows through the liquid pipe P4b. It is decompressed when passing through the second heat source expansion valve 20b, becoming a gas-liquid two-phase refrigerant, and then flows into the second heat source heat exchanger 18b. The gas-liquid two-phase refrigerant evaporates in the first and second heat source heat exchangers 18a and 18b, becoming a low-pressure gas refrigerant. The low-pressure gas refrigerant flowing out of the first heat source heat exchanger 18a flows into the first gas pipe P3a, passes through the first switching valve 16a, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing out of the second heat source heat exchanger 18b flows into the first gas pipe P3b, passes through the second switching valve 16b, and flows into the suction pipe P1. The low-pressure gas refrigerant flowing into the suction pipe P1 passes through the accumulator 14 and is sucked into the compressor 12 through the suction port 12a.

[0326] In addition, regarding the control of the compressor 12, the first switching valve 16a, the second switching valve 16b, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the first heat source fan 17a, the second heat source fan 17b and the supercooling valve 24 for interrupting the first heating operation and performing alternate defrosting (the second heating operation (the first defrosting operation) and the third heating operation (the second defrosting operation)) and returning to the first heating operation, the same as in the above embodiment is referred to. Figure 8 The control described is the same, so the description is omitted here.

[0327] (5-6) Modification F

[0328] In the air-conditioning apparatus 100 of the above embodiment, the heat source unit 10 and the plurality of usage units 50 a and 50 b are connected via the three refrigerant communication pipes 32 , 34 , and 36 , but the present invention is not limited thereto.

[0329] like Figure 11 As shown in the air conditioning apparatus 100B, the heat source unit 10 and the plurality of utilization units 50a and 50b can also be connected via two refrigerant communication pipes 32 and 34. This air conditioning apparatus 100B does not include the fourth switching valve 16d, the gas refrigerant communication pipe 36, the gas shutoff valve 28b, and the second gas pipe P5a. In this air conditioning apparatus 100B, one end (liquid side) of the utilization heat exchanger 52b is connected to the liquid refrigerant communication pipe 32 via piping, and the other end (gas side) is connected to the gas refrigerant communication pipe 34 via piping.

[0330] The main difference between air conditioner 100B and air conditioner 100 is that air conditioner 100B cannot operate in which one of heat exchanger 52a and heat exchanger 52b is used as a condenser, and the other of heat exchanger 52a and heat exchanger 52b is used as an evaporator. In other words, air conditioner 100B can only operate in which heat exchanger 52a and heat exchanger 52b are used as a condenser or in which heat exchanger 52a and heat exchanger 52b are used as an evaporator.

[0331] The other aspects of the air conditioning apparatus 100B are the same as those of the air conditioning apparatus 100 of the above embodiment. For example, the control of the compressor 12, the first switching valve 16a, the second switching valve 16b, the first heat source expansion valve 20a, the second heat source expansion valve 20b, the first heat source fan 17a, the second heat source fan 17b, and the supercooling valve 24 for interrupting the first heating operation and performing alternate defrosting (the second heating operation (first defrosting operation) and the third heating operation (second defrosting operation)) and returning to the first heating operation is the same as that in the above embodiment. Figure 8 The control described above is the same, so the description of other aspects of the air-conditioning apparatus 100B will be omitted.

[0332] (5-7) Modification G

[0333] In the above embodiment, the first switching valve 16a and the second switching valve 16b are used to switch the state in which the first heat source heat exchanger 18a and the second heat source heat exchanger 18b both act as condensers, the state in which the first heat source heat exchanger 18a and the second heat source heat exchanger 18b both act as evaporators, the state in which the first heat source heat exchanger 18a acts as a condenser and the second heat source heat exchanger 18b acts as an evaporator, and the state in which the first heat source heat exchanger 18a acts as an evaporator and the second heat source heat exchanger 18b acts as a condenser, but this can also be achieved through other structures.

[0334] For example, in Figure 12 In the air conditioning unit 100C, the first switching valve 16a is not provided. The four ports of the second switching valve 16b, a four-way reversing valve, are connected to the exhaust pipe P2, the first gas pipe P3a, the first gas pipe P3b, and the bypass pipe P6, respectively. Furthermore, the first gas pipes P3a and P3b are connected via a bypass pipe P7. A solenoid valve 29a is located between the end of the first gas pipe P3a connected to the second switching valve 16b and the junction between the first gas pipe P3a and the bypass pipe P7. Furthermore, a solenoid valve 29b is located in the bypass pipe P7.

[0335] In the above configuration, when both the first heat source heat exchanger 18a and the second heat source heat exchanger 18b function as condensers, the second switching valve 16b connects the discharge pipe P2 with the first gas pipe P3b and connects the first gas pipe P3a with the bypass pipe P6. Furthermore, when both the first heat source heat exchanger 18a and the second heat source heat exchanger 18b function as condensers, the solenoid valve 29a is closed and the solenoid valve 29b is opened.

[0336] When both the first heat source heat exchanger 18a and the second heat source heat exchanger 18b function as evaporators, the second switching valve 16b connects the exhaust pipe P2 with the first gas pipe P3a and connects the first gas pipe P3b with the bypass pipe P6. Furthermore, when both the first heat source heat exchanger 18a and the second heat source heat exchanger 18b function as condensers, the solenoid valve 29a is closed and the solenoid valve 29b is opened.

[0337] When the first heat source heat exchanger 18a functions as a condenser and the second heat source heat exchanger 18b functions as an evaporator, the second switching valve 16b connects the discharge pipe P2 with the first gas pipe P3b and connects the first gas pipe P3a with the bypass pipe P6. Furthermore, when the first heat source heat exchanger 18a functions as a condenser and the second heat source heat exchanger 18b functions as an evaporator, the solenoid valve 29a opens and the solenoid valve 29b closes.

[0338] When the first heat source heat exchanger 18a functions as an evaporator and the second heat source heat exchanger 18b functions as a condenser, the second switching valve 16b connects the discharge pipe P2 with the first gas pipe P3a and connects the first gas pipe P3b with the bypass pipe P6. Furthermore, when the first heat source heat exchanger 18a functions as an evaporator and the second heat source heat exchanger 18b functions as a condenser, the solenoid valve 29a opens and the solenoid valve 29b closes.

[0339] <Postscript>

[0340] 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.

[0341] Prior art literature

[0342] Patent Literature

[0343] Patent Document 1: Japanese Patent Application No. 9-318206.

Claims

1. A refrigeration cycle device (100, 100A, 100B, 100C), characterized in that: include: compressor (12); A first heat source heat exchanger (18a, 18b) and a second heat source heat exchanger (18b, 18a); a first switching mechanism (16a, 16b, 29a, 29b) for switching between a state in which the refrigerant discharged from the discharge port (12b) of the compressor flows into the first heat source heat exchanger to function as a radiator and a state in which the refrigerant, having passed through the first heat source heat exchanger and functioning as an evaporator, flows into the suction port (12a) of the compressor; a second switching mechanism (16b, 16a, 29a, 29b) for switching between a state in which the refrigerant discharged from the discharge port of the compressor flows into the second heat source heat exchanger to function as a radiator and a state in which the refrigerant, having passed through the second heat source heat exchanger functioning as an evaporator, flows into the suction port of the compressor; as well as a control unit (90) for controlling the operation of the compressor, the first switching mechanism, and the second switching mechanism; When the following change is made, the speed of the compressor is a specified speed that is smaller than the maximum speed (Rmax) of the compressor. The change means that the control unit changes the state from the state in which the second heat source heat exchanger acts as an evaporator and the first heat source heat exchanger acts as a radiator to the state in which the second heat source heat exchanger acts as a radiator and the first heat source heat exchanger acts as an evaporator while continuing the operation of the compressor.

2. The refrigeration cycle device according to claim 1, wherein The predetermined rotation speed is smaller than 1 / 2 of the maximum rotation speed.

3. The refrigeration cycle device according to claim 1 or 2, characterized in that: When the following change is made, the speed of the compressor is smaller than the maximum speed. The change means that the control unit changes the state from a state in which both the first heat source heat exchanger and the second heat source heat exchanger act as evaporators to a state in which one of the first heat source heat exchanger and the second heat source heat exchanger acts as a radiator while continuing the operation of the compressor.

4. The refrigeration cycle device according to claim 1 or 2, characterized in that: Also includes: utilizing heat exchangers (52a, 52b, 152a, 152b); a pipe (P2) connecting the first switching mechanism and the second switching mechanism to the heat exchanger; and A silencer member (25) is provided on the pipe.

5. The refrigeration cycle device according to claim 4, wherein: The refrigeration cycle device further includes a housing (10a) for housing the first heat source heat exchanger, the second heat source heat exchanger, and the first switching mechanism and the second switching mechanism. A single sound-absorbing member is provided in the housing.

6. The refrigeration cycle device according to claim 1, wherein Also includes: a first valve (20a, 20b, 21a, 21b) for adjusting the flow rate of the refrigerant flowing through the first heat source heat exchanger (18a, 18b); and The second valve (20b, 20a, 21b, 21a) adjusts the flow rate of the refrigerant flowing through the second heat source heat exchanger (18b, 18a). The control unit also controls the actions of the first valve and the second valve. When the first heat source heat exchanger is used as an evaporator and the second heat source heat exchanger is used as a radiator to defrost the second heat source heat exchanger, the control unit opens the second valve wider than when the second heat source heat exchanger is used as an evaporator.

7. The refrigeration cycle device according to claim 6, wherein: When defrosting the second heat source heat exchanger using the first heat source heat exchanger as an evaporator and the second heat source heat exchanger as a radiator, the control unit increases the opening degree of the first valve when a predetermined condition is satisfied.

8. The refrigeration cycle device according to claim 6, wherein: Also includes: a first refrigerant pipe, one end of which is connected in parallel to the first heat source heat exchanger and the second heat source heat exchanger, and the other end of which is connected to the utilization heat exchanger; a suction pipe (P1) connected to the suction port of the compressor; a bypass pipe (P6) connecting the first refrigerant pipe and the suction pipe; and A bypass valve (24) is provided on the bypass pipe, The control unit also controls the operation of the bypass valve. When the first heat source heat exchanger is used as an evaporator and the second heat source heat exchanger is used as a radiator to defrost the second heat source heat exchanger, when a specified condition is met, the control unit opens the closed bypass valve or increases the opening degree of the opened bypass valve.

9. The refrigeration cycle device according to claim 7 or 8, characterized in that: The prescribed condition is that defrosting of the second heat source heat exchanger is not completed within a prescribed time.

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