Refrigeration cycle device

Abstract

When a plurality of heat source heat exchangers are arranged side by side up and down, the frost melting residue of the heat source heat exchanger arranged below is suppressed. The refrigeration cycle device includes a first heat source heat exchanger and a second heat source heat exchanger arranged below the first heat source heat exchanger and aligned with the first heat source heat exchanger. The refrigeration cycle device performs a first defrosting operation for defrosting the first heat source heat exchanger and a second defrosting operation for defrosting the second heat source heat exchanger in the order of the first defrosting operation and the second defrosting operation, thereby performing defrosting of the first heat source heat exchanger and the second heat source heat exchanger. The second input heat quantity is larger than the first input heat quantity, and the second input heat quantity is the total input heat quantity per unit volume of the heat source heat exchanger supplied to the second heat source heat exchanger in the second defrosting operation. The first input heat amount is a total input heat amount per unit volume of the heat source heat exchanger supplied to the first heat source heat exchanger during the first defrosting operation.

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 in which a plurality of heat source heat exchangers are arranged in a vertical arrangement.

[0003] In the refrigeration cycle device of Patent Document 1 (Japanese Gazette No. 9-318206), for example, 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] However, when multiple heat source heat exchangers are arranged in an upper and lower arrangement as in Patent Document 1 (Japanese Gazette No. 9-318206), water generated during defrosting of the heat source heat exchanger arranged above may flow to the heat source heat exchanger arranged below and further frost, and melted frost may remain in the heat source heat exchanger arranged below.

[0005] A refrigeration cycle device according to a first aspect includes a refrigerant circuit. The refrigerant circuit includes a compressor, a first heat source heat exchanger, a second heat source heat exchanger, and a heat utilization exchanger. The second heat source heat exchanger is arranged below the first heat source heat exchanger and aligned with the first heat source heat exchanger. The refrigeration cycle device performs the first and second operations in that order, thereby defrosting the first and second heat source heat exchangers. The first operation is an operation in which the first heat source heat exchanger functions as a radiator and the second heat source heat exchanger functions as an evaporator, thereby defrosting the first heat source heat exchanger. The second operation is an operation in which the second heat source heat exchanger functions as a radiator and the first heat source heat exchanger functions as an evaporator, thereby defrosting the second heat source heat exchanger. The second heat input is greater than the first heat input. The first heat input is the total heat input per unit volume supplied to the first heat source heat exchanger during the first operation. The second heat input is the total heat input per unit volume supplied to the second heat source heat exchanger during the second operation.

[0006] In the refrigeration cycle device of the first viewpoint, defrosting is performed in the order of the first heat source heat exchanger arranged at the top and the second heat source heat exchanger arranged at the bottom. Therefore, even if water generated by the defrosting of the first heat source heat exchanger flows to the second heat source heat exchanger and further frosts, it can be removed by the second operation.

[0007] In addition, in the refrigeration cycle device of the first viewpoint, the total input heat per unit volume of the heat source heat exchanger (second input heat) supplied to the second heat source heat exchanger is greater than the total input heat per unit volume of the heat source heat exchanger (first input heat) supplied to the first heat source heat exchanger, so it is less likely that frost in the second heat source heat exchanger will melt and remain.

[0008] The refrigeration cycle apparatus according to the second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the circulation amount of the refrigerant flowing through the second heat source heat exchanger in the second operation is greater than the circulation amount of the refrigerant flowing through the first heat source heat exchanger in the first operation.

[0009] In the refrigeration cycle apparatus according to the second aspect, the second heat input can be made larger than the first heat input by adjusting the circulation amount of the refrigerant.

[0010] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the second aspect, wherein the rotation speed of the compressor during the second operation is higher than the rotation speed of the compressor during the first operation.

[0011] In the refrigeration cycle apparatus according to the third aspect, the second heat input can be made larger than the first heat input by adjusting the rotational speed of the compressor.

[0012] The refrigeration cycle device of the fourth aspect is based on the refrigeration cycle device of any one of the first to third aspects, and the refrigeration cycle device further includes a first valve and a second valve. The first valve regulates the flow rate of the refrigerant flowing through the first heat source heat exchanger. The second valve regulates the flow rate of the refrigerant flowing through the second heat source heat exchanger. In the first operation, the second heat source heat exchanger functions as an evaporator for the refrigerant flowing through the first heat source heat exchanger. In the second operation, the first heat source heat exchanger functions as an evaporator for the refrigerant flowing through the second heat source heat exchanger. If the defrosting of the first heat source heat exchanger is not completed within the first time during the first operation, the opening of the second valve is increased. If the defrosting of the first heat source heat exchanger is not completed within the second time during the second operation, the opening of the first valve is increased. The second time is shorter than the first time.

[0013] In the refrigeration cycle device of the fourth aspect, by increasing the opening of the valve corresponding to the heat source heat exchanger functioning as the evaporator, refrigerant becomes more easily able to flow through the heat source heat exchanger undergoing defrosting, thereby facilitating the discharge of liquid refrigerant accumulated in the heat source heat exchanger undergoing defrosting out of the heat source heat exchanger. As a result, the refrigeration cycle device of the fourth aspect can shorten the time required for defrosting the heat source heat exchanger and suppress the occurrence of melted frost residue.

[0014] In particular, in the refrigeration cycle device of the fourth viewpoint, when defrosting the second heat source heat exchanger which is easy to spend time on defrosting, the first valve is opened earlier (compared with the time when the second valve is opened during the first operation), so that the defrosting of the second heat source heat exchanger can be completed in a relatively short time while suppressing the melting residue of frost.

[0015] A refrigeration cycle device according to a fifth aspect is the refrigeration cycle device according to any one of the first to fourth aspects, further comprising a first refrigerant pipe, a suction pipe, a bypass pipe, and a bypass valve. A first heat source heat exchanger and a second heat source heat exchanger are connected in parallel at one end of the first refrigerant pipe, and a bypass heat exchanger is connected at the other end of the first refrigerant pipe. 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 disposed in the bypass pipe. During a first operation, the bypass heat exchanger functions as an evaporator for refrigerant flowing through the first source heat exchanger and then through the first refrigerant pipe. During a second operation, the bypass heat exchanger functions as an evaporator for refrigerant flowing through the second source heat exchanger and then through the first refrigerant pipe. If defrosting of the first heat source heat exchanger is not completed within a third time during the first operation, the closed bypass valve is opened, or the opening of the open bypass valve is increased. If defrosting of the first heat source heat exchanger is not completed within the fourth time in the second operation, the closed bypass valve is opened or the opening degree of the opened bypass valve is increased. The fourth time is shorter than the third time.

[0016] In the refrigeration cycle device of the fifth aspect, increasing the opening of the bypass valve facilitates the flow of refrigerant into the heat source heat exchanger undergoing defrosting, thereby facilitating the discharge of liquid refrigerant accumulated in the heat source heat exchanger undergoing defrosting out of the heat source heat exchanger. Consequently, the refrigeration cycle device of the fifth aspect can shorten the time required for defrosting the heat source heat exchanger and suppress the occurrence of melted frost residue.

[0017] In particular, in the refrigeration cycle device of the fifth viewpoint, when defrosting the second heat source heat exchanger which is easy to spend time on defrosting, the bypass valve is opened in advance (compared with the time when the bypass valve is opened during the first operation), so that the defrosting of the second heat source heat exchanger can be completed in a relatively short time while suppressing the melting and residual frost.

[0018] A refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to any one of the first to fifth aspects, wherein a time period of the second operation is longer than a time period of the first operation.

[0019] In the refrigeration cycle apparatus according to the sixth aspect, the second heat input can be made larger than the first heat input by adjusting the time of the first operation and the second operation.

[0020] A refrigeration cycle apparatus according to a seventh aspect is the refrigeration cycle apparatus according to the sixth aspect, wherein the first operation is terminated when a first maximum time has elapsed after the start of the first operation, and the second operation is terminated when a second maximum time has elapsed after the start of the second operation, the second maximum time being longer than the first maximum time.

[0021] The refrigeration cycle apparatus according to the seventh aspect can, by the above-described configuration, make the second maximum operation time longer than the first maximum operation time and make the second heat input greater than the first heat input.

[0022] The refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to the sixth aspect, and after performing the second operation, the first operation and the second operation are sequentially performed to defrost the first heat source heat exchanger and the second heat source heat exchanger.

[0023] In the refrigeration cycle device of the eighth aspect, by performing the second operation twice, the total time of the second operation is made longer than the total time of the first operation, and the second input heat is made larger than the first input heat, so that the frost in the second heat source heat exchanger can be suppressed from melting and remaining.

[0024] A refrigeration cycle device according to a ninth aspect is the refrigeration cycle device according to any one of the first to eighth aspects, further comprising a third valve for regulating the flow rate of refrigerant flowing through the heat exchanger, and a fan for supplying air to the heat exchanger. In the second operation, with the pipe connected so that the heat exchanger functions as a radiator, the third valve is closed, and operation of the fan is stopped.

[0025] In the refrigeration cycle apparatus according to the ninth aspect, the amount of heat input to the second heat source heat exchanger increases, and therefore, it is easy to suppress the frost from melting and remaining. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 2 Yes Figure 1 A block diagram of the control unit of an air conditioning device and the electrical connections of various structures.

[0028] Figure 3 Yes Figure 1 A 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.

[0029] Figure 4 It means in Figure 1FIG. 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Figure 13 This is a diagram showing another example of the alternating defrosting operation.

[0039] Explanation of symbols

[0040] 12 compressors;

[0041] 18a first heat source heat exchanger;

[0042] 18b second heat source heat exchanger;

[0043] 20a first heat source expansion valve (first valve);

[0044] 20b second heat source expansion valve (second valve);

[0045] 21a regulating valve (first valve);

[0046] 21b regulating valve (second valve);

[0047] 24 subcooling valve (bypass valve);

[0048] 52a and 52b utilize heat exchangers;

[0049] 54a and 54b utilize an expansion valve (third valve);

[0050] 56a and 56b utilize fans;

[0051] 152a first heat exchanger (using heat exchanger);

[0052] 152b second heat exchanger (utilizing heat exchanger);

[0053] 100 air conditioning units (refrigeration cycle units);

[0054] 100A air conditioning unit (refrigeration cycle unit);

[0055] 100B air conditioning unit (refrigeration cycle unit);

[0056] 100C air conditioning unit (refrigeration cycle unit);

[0057] H1 first input heat;

[0058] H2 second input heat;

[0059] P1 suction pipe;

[0060] P6 bypass pipe;

[0061] T1 specified time (first time);

[0062] T1' specified time (third time);

[0063] T2 specified time (second time);

[0064] T2' specified time (fourth time);

[0065] Tmax1 maximum time (first maximum time);

[0066] Tmax2 Maximum time (second maximum time). DETAILED DESCRIPTION

[0067] (1) Structure of air conditioning unit

[0068] 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 .

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] (1-1) Utilization Unit

[0074] 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 .

[0075] 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.

[0076] 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.

[0077] 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.

[0078] (1-1-1) Using a heat exchanger

[0079] The heat exchangers 52a and 52b are, for example, fin-tube heat exchangers composed of a plurality of heat transfer tubes and fins.

[0080] 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.

[0081] 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.

[0082] 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).

[0083] (1-1-2) Using an expansion valve

[0084] 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).

[0085] 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.

[0086] (1-1-3) Using a fan

[0087] 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.

[0088] 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).

[0089] 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.

[0090] 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.

[0091] (1-1-4) Utilization Control Unit

[0092] 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.

[0093] 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.

[0094] 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 .

[0095] 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 .

[0096] (1-2) Heat source unit

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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 .

[0101] 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 .

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] Hereinafter, various structures of the heat source unit 20 will be described.

[0109] (1-2-1) Compressor

[0110] 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.

[0111] 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.

[0112] (1-2-2) First Switching Valve and Second Switching Valve

[0113] 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.

[0114] 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.

[0115] 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.

[0116] The second switching valve 16b is a four-way switching valve with one of its four ports blocked (see Figure 1 ).exist Figure 1In 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.

[0117] 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.

[0118] (1-2-3) Third switching valve and fourth switching valve

[0119] 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.

[0120] 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).

[0121] 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.

[0122] 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).

[0123] 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.

[0124] (1-2-4) First heat source heat exchanger and second heat source heat exchanger

[0125] The first heat source heat exchanger 18a and the second heat source heat exchanger 18b are, for example, fin-and-tube heat exchangers composed of a plurality of heat transfer tubes and fins.

[0126] 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 3An 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] (1-2-5) First Heat Source Fan and Second Heat Source Fan

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] (1-2-6) First Heat Source Expansion Valve and Second Heat Source Expansion Valve

[0136] 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.

[0137] 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.

[0138] 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.

[0139] (1-2-7) Subcooling heat exchanger and subcooling valve

[0140] 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.

[0141] 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.

[0142] (1-2-8) Storage tank

[0143] 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.

[0144] (1-2-9) Liquid stop valve and gas stop valve

[0145] 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.

[0146] 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.

[0147] (1-2-10) Heat source control unit

[0148] 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.

[0149] 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.

[0150] 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 .

[0151] (2) Operation of air conditioning system

[0152] Hereinafter, the operation of the air-conditioning apparatus 100 will be briefly described.

[0153] 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.

[0154] (2-1) Refrigeration Operation

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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).

[0159] In this specification, the word “detection” is not limited to detection by a single sensor, but also includes calculation of a value based on detection results of multiple sensors.

[0160] 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.

[0161] 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.

[0162] (2-2) First heating operation

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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).

[0167] 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.

[0168] (2-3) Second heating operation (first defrosting operation)

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] (2-4) Third heating operation (second defrosting operation)

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] (3) Alternating defrosting operation

[0187] During the first heating operation, for example, if a predetermined defrost condition is met, the control unit 90 performs an alternating defrost operation. In this alternating defrost operation, the air conditioner 100 performs a first defrost operation (second heating operation) to defrost the first heat source heat exchanger 18a, and the air conditioner 100 performs a second defrost operation (third heating operation) to defrost the second heat source heat exchanger 18b. The first defrost operation is an example of the first operation in the claims, and the second defrost operation is an example of the second operation in the claims.

[0188] 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.

[0189] 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 8 The 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.

[0190] In addition, here, the case where the first defrost operation and the second defrost operation are performed once each in the alternating defrost operation is described as an example, but in the alternating defrost operation, one of the first defrost operation and the second defrost operation may be performed multiple times. Figure 13 As shown, in the alternating defrost operation, the operation of the air-conditioning device 100 can also 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.

[0191] (3-1) First switching valve and second switching valve

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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).

[0196] 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).

[0197] 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.

[0198] 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.

[0199] 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.

[0200] (3-2) Compressor

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] 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.

[0208] 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.

[0209] 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.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] 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.

[0216] 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.

[0217] 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.

[0218] (3-3) First Heat Source Expansion Valve and Second Heat Source Expansion Valve

[0219] 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.

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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).

[0224] 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).

[0225] 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).

[0226] 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.

[0227] 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 specified time T1 (<maximum time Tmax1), the opening of the second heat source expansion valve 20b begins to gradually increase at the time point when the specified time T1 has passed.

[0228] 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.

[0229] 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.

[0230] 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.

[0231] 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.

[0232] 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).

[0233] 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).

[0234] 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).

[0235] 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.

[0236] 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 specified time T2 (<maximum time Tmax2), the opening of the first heat source expansion valve 20a is gradually increased at the time point after the specified time T2 has passed.

[0237] 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.

[0238] 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.

[0239] 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.

[0240] (3-4) Subcooling valve

[0241] The subcooling valve 24 is an example of a bypass valve in the claims.

[0242] 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.

[0243] 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.

[0244] 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 Tmax2, and based on the result, when it is predicted that the first defrost operation cannot be completed within the specified time T1' (<maximum time Tmax1) and the second defrost operation cannot be completed within the specified time T2' (<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' 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' has passed.

[0245] 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.

[0246] 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.

[0247] (3-5) First heat source fan and second heat source fan

[0248] 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.

[0249] 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.

[0250] (4) Defrosting measures for the second heat source heat exchanger

[0251] In the air conditioning apparatus 100, the second heat source heat exchanger 18b is arranged side by side with the first heat source heat exchanger 18a below the first heat source heat exchanger 18a. Furthermore, the second heat source heat exchanger 18b is arranged side by side with the first heat source heat exchanger 18a below the first heat source heat exchanger 18a, meaning that the first heat source heat exchanger 18a and the second heat source heat exchanger 18b are arranged in a positional relationship such that at least a portion of the first heat source heat exchanger 18a overlaps with the second heat source heat exchanger 18b when viewed from above (when viewed from directly above).

[0252] When the first heat source heat exchanger 18a and the second heat source heat exchanger 18b are arranged in this manner, when the defrosting operation is performed in the first heat source heat exchanger 18a, the water generated at this time may flow into the second heat source heat exchanger 18b and freeze in the second heat source heat exchanger 18b.

[0253] Therefore, in the air conditioning apparatus 100, after defrosting the first heat source heat exchanger 18a, defrosting is performed in the second heat source heat exchanger 18b. In other words, when the air conditioning apparatus 100 defrosts the first heat source heat exchanger 18a and the second heat source heat exchanger 18b in the alternating defrosting operation, the first defrosting operation and the second defrosting operation are sequentially performed. Figure 10 As shown, the second defrost operation may be performed first in the alternating defrost operation. In this case, the second defrost operation is also executed after the first defrost operation.

[0254] In addition, when the second heat source heat exchanger 18b is arranged below the first heat source heat exchanger 18a, due to the above reasons, the amount of frost in the second heat source heat exchanger 18b is likely to become greater than the amount of frost in the first heat source heat exchanger 18a. Therefore, the air-conditioning device 100 is designed so that the heat supplied to the second heat source heat exchanger 18b during defrosting is greater than the heat supplied to the second heat source heat exchanger 18b during defrosting.

[0255] More specifically, in the air-conditioning device 100, the second input heat H2 is designed to be greater than the first input heat H1. The second input heat H2 is the total input heat per unit volume of the heat source heat exchanger supplied to the second heat source heat exchanger 18b during the second defrost operation, and the first input heat H1 is the total input heat per unit volume of the heat source heat exchanger supplied to the first heat source heat exchanger 18a during the first defrost operation.

[0256] The total heat input per unit volume of the heat source heat exchanger is used here because the internal volume of the first heat source heat exchanger 18a (roughly the internal volume of the heat transfer tubes that comprise the heat exchanger 18a) and the internal volume of the second heat source heat exchanger 18b (roughly the internal volume of the heat transfer tubes that comprise the heat exchanger 18b) may differ. Furthermore, if the internal volumes of the first and second heat source heat exchangers 18a and 18b are the same, the total heat input to the second heat source heat exchanger 18b during the second defrost operation can be simply set to be greater than the total heat input to the first heat source heat exchanger 18a during the first defrost operation.

[0257] By making the second heat input H2 to the second heat source heat exchanger 18b larger than the first heat input H1 supplied to the first heat source heat exchanger 18a, defrosting can be easily and reliably performed even in the second heat source heat exchanger 18b where the amount of frost is likely to increase.

[0258] Specifically, in order to make the second input heat amount H2 larger than the first input heat amount H1 , for example, one of the following structures (A) to (C) is applied to the air conditioning apparatus 100 or a combination thereof is applied to the air conditioning apparatus 100 .

[0259] (A) The circulation amount of the refrigerant flowing through the second heat source heat exchanger 18b during the second defrost operation is made greater than the circulation amount of the refrigerant flowing through the first heat source heat exchanger 18a during the first defrost operation. Specifically, the first rotational speed Ra of the compressor 12 during the second defrost operation is made greater than the second rotational speed Rb of the compressor 12 during the first defrost operation.

[0260] (B) The second defrosting operation time is made longer than the first defrosting operation time.

[0261] More specifically, as described above, the first defrost operation is forcibly terminated after the maximum time Tmax1 has elapsed, and the second defrost operation is forcibly terminated after the maximum time Tmax2 has elapsed. Therefore, by making the maximum time Tmax2 longer than the maximum time Tmax1, even when frost is difficult to melt, the second heat input H2 can be increased relative to the first heat input H1, thereby preventing any melted frost from remaining in the second heat source heat exchanger 18b.

[0262] (C) The second defrosting operation is performed more often than the first defrosting operation.

[0263] For example, Figure 10 As shown, by performing two second defrosting operations for one first defrosting operation, even when frost is difficult to melt, the second input heat H2 can be increased relative to the first input heat H1, thereby suppressing the melted frost remaining in the second heat source heat exchanger 18b.

[0264] Furthermore, in order to promote defrosting in the second heat source heat exchanger 18b, the following controls (D) and (E) may be performed.

[0265] (D) As described above, when the specified conditions are satisfied during the first defrost operation, the controller 90 stops normal control of the opening of the second heat source expansion valve 20b and increases the opening of the second heat source expansion valve 20b to a larger opening than the previous opening of the second heat source expansion valve 20b. Furthermore, when the specified conditions are satisfied during the second defrost operation, the controller 90 stops normal control of the opening of the first heat source expansion valve 20a and increases the opening of the first heat source expansion valve 20a to a larger opening than the previous opening of the first heat source expansion valve 20a.

[0266] Here, by making the predetermined conditions different between the first defrosting operation and the second defrosting operation, the defrosting of the second heat source heat exchanger 18b can be facilitated.

[0267] As described above, the prescribed conditions here are, for example, that the defrosting of the heat source heat exchanger 18a / the heat source heat exchanger 18b is not completed within the prescribed time. The control unit 90, for example, measures the time from the start of the first defrost operation / the second defrost operation, and increases the opening of the second heat source expansion valve 20b / the first heat source expansion valve 20a if it is not determined that the first defrost operation is completed even after the prescribed time T1 / T2.

[0268] Therefore, for example, as long as the prescribed time T2 is shorter than the prescribed time T1, even if liquid refrigerant is accumulated in the second heat source heat exchanger 18b, the liquid refrigerant can be easily discharged outside the second heat source heat exchanger 18b, and the melting and residual frost in the second heat source heat exchanger 18b can be easily suppressed.

[0269] In addition, the control unit 90 stores the time required for defrosting during the last first defrost operation / second defrost operation and whether the first defrost operation / second defrost operation was completed within the maximum time Tmax1 / Tmax2, and when it is predicted based on the result that the defrosting of the first heat source heat exchanger 18a / the second heat source heat exchanger 18b is not completed within the specified time T1 (<maximum Tmax1) / T2 (<maximum Tmax2), even at the moment when the specified time T1 / T2 has passed, when the control of increasing the opening of the second heat source expansion valve 20b / the first heat source expansion valve 20a is performed, as long as the specified time T2 is shorter than the specified time T1, even when liquid refrigerant accumulates in the second heat source heat exchanger 18b, the liquid refrigerant is easily discharged to the outside of the second heat source heat exchanger 18b, and it is easy to suppress the melting of frost residue in the second heat source heat exchanger 18b.

[0270] (E) As described above, when the predetermined conditions are satisfied during the first defrosting operation or the second defrosting operation, the control unit 90 increases the opening degree of the supercooling valve 24 or opens the supercooling valve 24 that is closed.

[0271] Specifically, the control unit 90 measures the time elapsed from the start of the first defrost operation, and when it is determined that the first defrost operation is not completed after the specified time T1' (<maximum time Tmax1) has passed, or measures the time elapsed from the start of the second defrost operation, and when it is determined that the second defrost operation is not completed after the specified time T2' (<maximum time Tmax2) has passed, increases the opening of the subcooling valve 24, or opens the subcooling valve 24 that is closed.

[0272] Therefore, for example, as long as the prescribed time T2' is shorter than the prescribed time T1', even if liquid refrigerant is accumulated in the second heat source heat exchanger 18b, the liquid refrigerant can be easily discharged outside the second heat source heat exchanger 18b, and the melting and residual frost in the second heat source heat exchanger 18b can be easily suppressed.

[0273] In addition, the control unit 90 stores the time required for defrosting during the last first defrost operation / second defrost operation and whether the first defrost operation / second defrost operation was completed within the maximum time Tmax1 / Tmax2, and when it is predicted based on the result that the defrosting of the first heat source heat exchanger 18a / the second heat source heat exchanger 18b will not be completed within the specified time T1' (<maximum time Tmax1) / T2' (<maximum time Tmax2), at the moment when the specified time T1' / T2' has passed, the opening of the subcooling valve 24 is increased or the closed subcooling valve 24 is controlled to be opened. As long as the specified time T2' is shorter than the specified time T1', even if liquid refrigerant accumulates in the second heat source heat exchanger 18b, the liquid refrigerant is easily discharged to the outside of the second heat source heat exchanger 18b, and it is easy to suppress the melting of frost residue in the second heat source heat exchanger 18b.

[0274] (5) Characteristics

[0275] (5-1)

[0276] The air conditioning apparatus 100 includes a refrigerant circuit 40. The refrigerant circuit 40 includes a compressor 12, a first heat source heat exchanger 18a, a second heat source heat exchanger 18b, and heat exchangers 52a and 52b. The second heat source heat exchanger 18b is arranged below the first heat source heat exchanger 18a and aligned with the first heat source heat exchanger 18a. The air conditioning apparatus 100 performs a first defrost operation as a first operation and a second defrost operation as an example of a second operation in this order, thereby defrosting the first heat source heat exchanger 18a and the second heat source heat exchanger 18b. The first defrost operation is an operation in which the first heat source heat exchanger 18a functions as a radiator and the second heat source heat exchanger 18b functions as an evaporator to defrost the first heat source heat exchanger 18a. The second defrost operation defrosts the second heat source heat exchanger 18b by causing the second heat source heat exchanger 18b to function as a radiator and the first heat source heat exchanger 18a to function as an evaporator. The second heat input H2 is greater than the first heat input H1. The first heat input H1 is the total heat input per unit volume of the heat source heat exchanger supplied to the first heat source heat exchanger 18a during the first defrost operation. The second heat input H2 is the total heat input per unit volume of the heat source heat exchanger supplied to the second heat source heat exchanger 18b during the second defrost operation.

[0277] In the air-conditioning device 100, defrosting is performed in the order of the first heat source heat exchanger 18a arranged at the top and the second heat source heat exchanger 18b arranged at the bottom. Therefore, even if water generated by the defrosting of the first heat source heat exchanger 18a flows to the second heat source heat exchanger 18b and further frosts, it can be removed by the second defrosting operation.

[0278] In addition, in the air-conditioning device 100, the total input heat per unit volume of the heat source heat exchanger supplied to the second heat source heat exchanger 18b (the second input heat H2) is greater than the total input heat per unit volume of the heat source heat exchanger supplied to the first heat source heat exchanger 18a (the first input heat H1), so it is less likely that frost in the second heat source heat exchanger 18b will melt and remain.

[0279] (5-2)

[0280] In the air-conditioning apparatus 100, the circulation amount of the refrigerant flowing through the second heat source heat exchanger 18b in the second defrosting operation is made larger than the circulation amount of the refrigerant flowing through the first heat source heat exchanger 18a in the first defrosting operation.

[0281] In the air-conditioning apparatus 100 , the second heat input H2 can be made larger than the first heat input H1 by adjusting the circulation amount of the refrigerant.

[0282] (5-3)

[0283] In the air-conditioning apparatus 100 , it is preferable that the first rotation speed Ra of the compressor 12 during the second defrosting operation is set to be higher than the second rotation speed Rb of the compressor 12 during the first defrosting operation.

[0284] In the air-conditioning apparatus 100 , the second input heat amount H2 can be made larger than the first input heat amount H1 by adjusting the rotation speed of the compressor 12 .

[0285] (5-4)

[0286] The air conditioning device 100 includes a first heat source expansion valve 20a as an example of a first valve and a second heat source expansion valve 20b as an example of a second valve. The first heat source expansion valve 20a regulates the flow rate of the refrigerant flowing through the first heat source heat exchanger 18a. The second heat source expansion valve 20b regulates the flow rate of the refrigerant flowing through the second heat source heat exchanger 18b. During the first defrost operation, the second heat source heat exchanger 18b functions as an evaporator for the refrigerant flowing through the first heat source heat exchanger 18a. During the second defrost operation, the first heat source heat exchanger 18a functions as an evaporator for the refrigerant flowing through the second heat source heat exchanger 18b.

[0287] Furthermore, for example, if defrosting of the first heat source heat exchanger 18a is not completed within the predetermined time T1 during the first defrost operation, the opening degree of the second heat source expansion valve 20b is increased. If defrosting of the first heat source heat exchanger 18a is not completed within the predetermined time T2 during the second defrost operation, the opening degree of the first heat source expansion valve 20a is increased. The predetermined time T2 is shorter than the predetermined time T1.

[0288] In another example, if defrosting of the first heat source heat exchanger 18a is not completed within a predetermined time T1 (less than the maximum time Tmax1) during the first defrost operation ("not completed" herein includes a predicted incompleteness), the opening degree of the second heat source expansion valve 20b is increased after the predetermined time T1 has elapsed. If defrosting of the first heat source heat exchanger 18a is not completed within a predetermined time T2 (less than the maximum time Tmax2) during the second defrost operation ("not completed" herein includes a predicted incompleteness), the opening degree of the first heat source expansion valve 20a is increased after the predetermined time T2 has elapsed. The predetermined time T2 is shorter than the predetermined time T1.

[0289] In this air conditioner 100, by increasing the opening of the valve corresponding to the heat source heat exchanger functioning as an evaporator, refrigerant flows more easily through the heat source heat exchanger undergoing defrosting. This facilitates the discharge of liquid refrigerant accumulated in the heat source heat exchanger undergoing defrosting out of the heat source heat exchanger. As a result, in the air conditioner 100, the time required for defrosting the heat source heat exchanger can be shortened, thereby suppressing the occurrence of melted frost residue.

[0290] In particular, in the air-conditioning device 100, when defrosting the second heat source heat exchanger 18b, which is easy to spend time on defrosting, the first heat source expansion valve 20a is opened in advance (compared to the time when the second heat source expansion valve 20b is opened during the first defrost operation), so that the defrost of the second heat source heat exchanger 18b can be completed in a relatively short time while suppressing the melting residue of frost.

[0291] (5-5)

[0292] The air conditioning unit 100 further includes a first refrigerant pipe (liquid pipe P4 and liquid refrigerant connecting pipe 32), a suction pipe P1, a bypass pipe P6, and a subcooling valve 24, which serves as 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 the utilization heat exchangers 52a and 52b. The suction pipe P1 is connected to the suction port 12a of the compressor 12. The bypass pipe P6 connects the first refrigerant pipe and the suction pipe P1. The subcooling valve 24 is provided on the bypass pipe P6. During the first defrost operation, the utilization heat exchangers 52a and 52b function as evaporators for the refrigerant flowing through the first source heat exchanger 18a and the first refrigerant pipe. During the second defrost operation, the utilization heat exchangers 52a and 52b function as evaporators for the refrigerant flowing through the second source heat exchanger 18b and the first refrigerant pipe.

[0293] Furthermore, if defrosting of the first heat source heat exchanger 18a is not completed within the predetermined time T1', which is an example of the third time, during the first defrost operation, the subcooling valve 24, which is closed, is opened, or the opening degree of the subcooling valve 24, which is open, is increased. If defrosting of the first heat source heat exchanger 18a is not completed within the predetermined time T2', which is an example of the fourth time, during the second defrost operation, the subcooling valve 24, which is closed, is opened, or the opening degree of the subcooling valve 24, which is open, is increased. The predetermined time T2' is shorter than the predetermined time T1'.

[0294] In another example, if defrosting of the first heat source heat exchanger 18a is not completed within a predetermined time T1' (less than the maximum time Tmax1) during the first defrost operation ("not completed" herein includes a predicted incompleteness), the opening degree of the second heat source expansion valve 20b is increased after the predetermined time T1' has elapsed. If defrosting of the first heat source heat exchanger 18a is not completed within a predetermined time T2' (less than the maximum time Tmax2) during the second defrost operation ("not completed" herein includes a predicted incompleteness), the opening degree of the first heat source expansion valve 20a is increased after the predetermined time T2' has elapsed. The predetermined time T2' is shorter than the predetermined time T1'.

[0295] In this air conditioning apparatus 100, increasing the opening of the subcooling valve 24 facilitates the flow of refrigerant through the heat source heat exchanger undergoing defrosting, thereby facilitating the discharge of liquid refrigerant accumulated in the heat source heat exchanger undergoing defrosting out of the heat source heat exchanger. Consequently, this air conditioning apparatus 100 can shorten the time required for defrosting the heat source heat exchanger and prevent the formation of melted frost residue.

[0296] In particular, in the air-conditioning device 100, when defrosting the second heat source heat exchanger 18b, which is easy to spend time on defrosting, the subcooling valve 24 is opened in advance (compared to the time when the subcooling valve 24 is opened during the first defrost operation), so that the defrosting of the second heat source heat exchanger 18b can be completed in a relatively short time while suppressing the melting and residual frost.

[0297] (5-6)

[0298] In the air-conditioning apparatus 100 , the second defrosting operation may be performed for a longer period than the first defrosting operation.

[0299] By configuring the air conditioning apparatus 100 in this manner, the second heat input H2 can be made larger than the first heat input H1 by adjusting the timing of the first defrosting operation and the second defrosting operation.

[0300] (5-7)

[0301] In the air conditioning apparatus 100, the first defrost operation is terminated when a maximum time Tmax1, which is an example of a first maximum time, has elapsed after the start of the first defrost operation, and the second defrost operation is terminated when a maximum time Tmax2, which is an example of a second maximum time, has elapsed after the start of the second defrost operation. The maximum time Tmax2 is longer than the maximum time Tmax1.

[0302] In the air-conditioning apparatus 100 , the maximum time Tmax2 can be made longer than the maximum time Tmax1 , and the second input heat amount H2 can be made larger than the first input heat amount H1 .

[0303] (5-8)

[0304] The air-conditioning apparatus 100 may perform the first defrost operation and the second defrost operation in sequence after performing the second defrost operation, thereby defrosting the first heat source heat exchanger 18a and the second heat source heat exchanger 18b.

[0305] By configuring the air conditioner 100 in this manner, the second heat input H2 can be made larger than the first heat input H1 by making the total time of the second defrosting operation longer than the total time of the first defrosting operation, thereby suppressing the frost from being melted and remaining in the second heat source heat exchanger 18b.

[0306] (6) Modification

[0307] The following describes modifications of the above embodiment. The following modifications can be combined as appropriate unless they are inconsistent with each other.

[0308] (6-1) Modification A

[0309] 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.

[0310] (6-2) Modification B

[0311] 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.

[0312] (6-3) Modification C

[0313] 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 P1.

[0314] (6-4) Modification D

[0315] 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.

[0316] 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.

[0317] 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.

[0318] (6-5) Modification E

[0319] 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.

[0320] 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.

[0321] 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.

[0322] 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.

[0323] 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.

[0324] 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.

[0325] 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.

[0326] 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.

[0327] 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).

[0328] 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.

[0329] 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.

[0330] 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.

[0331] 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.

[0332] The flow of the refrigerant in the refrigerant circuit 40A during the cooling operation will be briefly described.

[0333] 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.

[0334] 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.

[0335] 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 .

[0336] 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.

[0337] The main flow of the refrigerant in the refrigerant circuit 40A during the reheat dehumidification operation will be briefly described.

[0338] 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.

[0339] 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.

[0340] 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-conditioned space.

[0341] 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.

[0342] 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.

[0343] The flow of the refrigerant in the refrigerant circuit 40A during the heating operation (first heating operation) will be briefly described.

[0344] 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.

[0345] 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.

[0346] 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.

[0347] (6-6) Modification F

[0348] 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.

[0349] 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.

[0350] 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.

[0351] 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.

[0352] (6-7) Modification G

[0353] 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.

[0354] 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.

[0355] 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.

[0356] 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.

[0357] 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.

[0358] 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.

[0359] (6-8) Modification H

[0360] In the first defrost operation described in the above embodiment, the first heat source heat exchanger 18a functions as a radiator, the second heat source heat exchanger 18b functions as an evaporator, and the utilization heat exchangers 52a and 52b function as radiators. Furthermore, in the second defrost operation described in the above embodiment, the second heat source heat exchanger 18b functions as a radiator, the first heat source heat exchanger 18a functions as an evaporator, and the utilization heat exchangers 52a and 52b function as radiators. With this configuration, heating of the air-conditioned space can continue while the heat source heat exchangers 18a and 18b are being defrosted.

[0361] However, the present invention is not limited to this embodiment, and heating of the air-conditioned space may be stopped in order to improve the defrosting operation capability.

[0362] Specifically, during the first defrost operation, the controller 90 may control the third switching valve 16c and the fourth switching valve 16d so that the heat exchangers 52a and 52b function as radiators (condensers), close the expansion valves 54a and 54b, and stop the fans 56a and 56b. In other words, during the first defrost operation, the expansion valves 54a and 54b, as an example of a third valve, may be closed and the fans 56a and 56b may be stopped, with the piping connected so that the heat exchangers 52a and 52b function as radiators (condensers). This configuration increases the amount of refrigerant flowing through the first heat source heat exchanger 18a during the first defrost operation, thereby facilitating defrosting of the first heat source heat exchanger 18a.

[0363] Furthermore, during the second defrost operation, the controller 90 may control the third switching valve 16c and the fourth switching valve 16d so that the heat exchangers 52a and 52b function as radiators (condensers), close the expansion valves 54a and 54b, and stop the fans 56a and 56b. In other words, during the second defrost operation, the expansion valves 54a and 54b, as an example of a third valve, may be closed and the fans 56a and 56b may be stopped, with the piping connected so that the heat exchangers 52a and 52b function as radiators (condensers). With this configuration, the amount of refrigerant flowing through the second heat source heat exchanger 18b can be increased during the second defrost operation, thereby facilitating defrosting of the second heat source heat exchanger 18b.

[0364] Alternatively, closing the expansion valves 54a and 54b and stopping the fans 56a and 56b may be performed only during either the first or second defrost operation. For example, closing the expansion valves 54a and 54b and stopping the fans 56a and 56b are preferably performed during the second defrost operation. With this configuration, the second heat input H2 is more likely to be greater than the first heat input H1, thereby easily preventing the formation of melted frost residue in the second heat source heat exchanger 18b.

[0365] Here, in addition to closing the expansion valves 54a and 56b, the fans 56a and 56b are stopped to prevent the refrigerant from accumulating in the heat exchangers 52a and 52b and causing insufficient refrigerant circulation in the refrigerant circuit 40.

[0366] (6-9) Modification Example 1

[0367] In the first defrost operation described in the above embodiment, the first heat source heat exchanger 18a functions as a radiator, the second heat source heat exchanger 18b functions as an evaporator, and the utilization heat exchangers 52a and 52b function as radiators. Furthermore, in the second defrost operation described in the above embodiment, the second heat source heat exchanger 18b functions as a radiator, the first heat source heat exchanger 18a functions as an evaporator, and the utilization heat exchangers 52a and 52b function as radiators. This configuration allows continued heating of the air-conditioned space even while the heat source heat exchangers 18a and 18b are being defrosted.

[0368] However, the present invention is not limited to this embodiment, and in order to improve the defrosting operation performance, the heat exchangers 52a and 52b may be made to function as evaporators and the fans 56a and 56b may be stopped during the first or second defrosting operation.

[0369] Specifically, during the first defrost operation, the controller 90 may also control the heat exchangers 52a and 52b to function as evaporators, and then stop the fans 56a and 56b. This configuration allows heat to be absorbed from the heat exchangers 52a and 52b during the first defrost operation, thereby increasing the amount of heat transferred to the first heat source heat exchanger 18a and the amount of heat input to the first heat source heat exchanger 18a. Furthermore, during this operation, even if the speed of the compressor 12 is increased, the low pressure in the refrigeration cycle does not drop excessively, making it easier to increase the amount of heat input to the first heat source heat exchanger 18a.

[0370] Furthermore, during the second defrost operation, the controller 90 may also control the heat exchangers 52a and 52b to function as evaporators, and then stop the fans 56a and 56b. This configuration allows heat to be absorbed from the heat exchangers 52a and 52b during the second defrost operation, thereby increasing the amount of heat transferred to the second heat source heat exchanger 18b and the amount of heat input to the second heat source heat exchanger 18b. Furthermore, during this operation, even if the speed of the compressor 12 is increased, the low pressure in the refrigeration cycle does not drop excessively, making it easier to increase the amount of heat input to the second heat source heat exchanger 18b.

[0371] Furthermore, the control described in Modification 1 can be performed only during either the first or second defrost operation. For example, the control described in Modification 1 is particularly preferably performed during the second defrost operation. With the above configuration, the second heat input H2 easily becomes greater than the first heat input H1, thereby easily suppressing the occurrence of melted frost residue in the second heat source heat exchanger 18b.

[0372] Furthermore, when the heat exchangers 52a and 52b function as evaporators, the fans 56a and 56b are stopped in order to suppress the flow of cold air into the air-conditioned space.

[0373] (6-10) Modification J

[0374] When performing the second defrost operation (defrosting the second heat source heat exchanger 18b) by performing the control described in variant example I (control of making the heat exchangers 52a and 52b function as evaporators and stopping the fans 56a and 56), the use of the first heat source heat exchanger 18a as an evaporator can also be further stopped.

[0375] Specifically, during the second defrost operation, the controller 90 may control the heat exchangers 52a and 52b to function as evaporators, then stop the fans 56a and 56b, and further stop the first heat source fan 22a. Alternatively, during the second defrost operation, the controller 90 may control the heat exchangers 52a and 52b to function as evaporators, then stop the fans 56a and 56b, and further close the first heat source expansion valve 20a.

[0376] For example, when the first heat source heat exchanger 18a and the second heat source heat exchanger 18b are in contact with each other, by stopping the use of the first heat source heat exchanger 18a as an evaporator, the following phenomenon can be suppressed: the first heat source heat exchanger 18a acts as an evaporator and the temperature of the refrigerant decreases, resulting in a decrease in temperature at the contact portion of the second heat source heat exchanger 18b with the first heat source heat exchanger 18a.

[0377] In addition, especially when the first heat source fan 22a is stopped, both the first heat source fan 22a and the second heat source fan 22b are stopped. Therefore, no airflow generated by the heat source fans 22a and 22b passes through the second heat source heat exchanger 18b, making it easy to complete the defrosting of the second heat source heat exchanger 18b in a short time.

[0378] In addition, here, the control described in Modification Example 1 is performed during the second defrost operation, and the control of further stopping the use of the first heat source heat exchanger 18a as an evaporator is described. However, this is not limited to this. Alternatively, the control described in Modification Example 1 may be performed during the first defrost operation, and the use of the second heat source heat exchanger 18b as an evaporator may be stopped.

[0379] (6-11) Modification K

[0380] The control described in variant example H (closing the expansion valves 54a and 54b and stopping the fans 56a and 56b) and the control described in variant example I (making the heat exchangers 52a and 52b function as evaporators and stopping the fans 56a and 56b) may not always be performed in the first defrost operation or the second defrost operation.

[0381] In addition, the control described in variant example J (control of making the heat exchangers 52a and 52b function as evaporators and stopping the fans 56a and 56b, and control of stopping the first heat source fan 22a or closing the first heat source expansion valve 20a) may not always be performed during the second defrost operation.

[0382] For example, the control unit 90 may also operate the air-conditioning device 100 (in other words, it may also heat the air-conditioned space) by controlling the third switching valve 16c and the fourth switching valve 16d to utilize the heat exchangers 52a and 52b to function as condensers, the expansion valves 54a and 54b to be open, and the fans 56a and 56b to operate within a specified time from the start of the first defrost operation or the second defrost operation.

[0383] Furthermore, the control unit 90 may continue the first or second defrost operation after a predetermined time has elapsed from the start of the first or second defrost operation while performing the control described in Modification H or Modification I. Furthermore, the control unit 90 may continue the second defrost operation while performing the control described in Modification J after a predetermined time has elapsed from the start of the second defrost operation.

[0384] Furthermore, the control unit 90 may determine whether to execute the control described in Modifications H to J based on the temperature of the heat source heat exchangers 18a and 18b in addition to the predetermined time. For example, if the temperature of the heat source heat exchangers 18a and 18b to be defrosted remains below the predetermined temperature even after the predetermined time has elapsed, the control unit 90 may execute the control described in Modifications H to J and continue the defrosting operation.

[0385] By configuring as in Modification K, the interruption time of the heating operation is shortened, and it is easy to ensure comfort even in the first defrosting operation or the second defrosting operation.

[0386] <Postscript>

[0387] 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.

[0388] Prior art literature

[0389] Patent Literature

[0390] Patent Document 1: Japanese Patent Application No. 9-318206.

Claims

1. A refrigeration cycle device (100, 100A, 100B, 100C), comprising a refrigerant circuit, the refrigerant circuit comprising: compressor (12); a first heat source heat exchanger (18a); a second heat source heat exchanger (18b), the second heat source heat exchanger being arranged below the first heat source heat exchanger and aligned with the first heat source heat exchanger; as well as Using heat exchangers (52a, 52b, 152a, 152b), The refrigeration cycle device is characterized in that The refrigeration cycle device sequentially performs a first operation and a second operation to defrost the first heat source heat exchanger and the second heat source heat exchanger. In the first operation, the first heat source heat exchanger functions as a radiator and the second heat source heat exchanger functions as an evaporator to defrost the first heat source heat exchanger. In the second operation, the second heat source heat exchanger functions as a radiator and the first heat source heat exchanger functions as an evaporator to defrost the second heat source heat exchanger. The second input heat (H2) is greater than the first input heat (H1), and the second input heat is the total input heat per unit volume of the heat source heat exchanger supplied to the second heat source heat exchanger during the second operation, and the first input heat is the total input heat per unit volume of the heat source heat exchanger supplied to the first heat source heat exchanger during the first operation.

2. The refrigeration cycle device according to claim 1, wherein The circulation amount of the refrigerant flowing through the second heat source heat exchanger in the second operation is greater than the circulation amount of the refrigerant flowing through the first heat source heat exchanger in the first operation.

3. The refrigeration cycle device according to claim 2, wherein: The rotation speed of the compressor during the second operation is higher than the rotation speed of the compressor during the first operation.

4. The refrigeration cycle device according to claim 1 or 2, characterized in that: Also includes: a first valve (20a, 21a) for regulating the flow of refrigerant flowing through the first heat source heat exchanger; as well as The second valve (20b, 21b) is configured to adjust the flow rate of the refrigerant flowing through the second heat source heat exchanger. In the first operation, the second heat source heat exchanger functions as an evaporator through which the refrigerant flowing through the first heat source heat exchanger flows. In the second operation, the first heat source heat exchanger functions as an evaporator through which the refrigerant flowing through the second heat source heat exchanger flows. In the first operation, when the defrosting of the first heat source heat exchanger is not completed within the first time (T1), the opening degree of the second valve is increased. In the second operation, when the defrosting of the first heat source heat exchanger is not completed within the second time (T2), the opening degree of the first valve is increased. The second time is shorter than the first time.

5. The refrigeration cycle device according to claim 1 or 2, characterized in that: 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, In the first operation, the utilization heat exchanger functions as an evaporator for the refrigerant flowing through the first source heat exchanger and then through the first refrigerant pipe. In the second operation, the utilization heat exchanger functions as an evaporator for the refrigerant flowing through the second source heat exchanger and then through the first refrigerant pipe. In the first operation, when the defrosting of the first heat source heat exchanger is not completed within the third time (T1'), the closed bypass valve is opened, or the opening degree of the opened bypass valve is increased. In the second operation, when the defrosting of the first heat source heat exchanger is not completed within the fourth time (T2'), the closed bypass valve is opened, or the opening degree of the opened bypass valve is increased. The fourth time is shorter than the third time.

6. The refrigeration cycle device according to claim 1, wherein The second operation time is longer than the first operation time.

7. The refrigeration cycle device according to claim 6, wherein: The refrigeration cycle device ends the first operation when a first maximum time (Tmax1) has passed after the start of the first operation, and ends the second operation when a second maximum time (Tmax2) has passed after the start of the second operation. The second maximum time is longer than the first maximum time.

8. The refrigeration cycle device according to claim 6, wherein: After performing the second operation, the refrigeration cycle device sequentially performs the first operation and the second operation, thereby defrosting the first heat source heat exchanger and the second heat source heat exchanger.

9. The refrigeration cycle device according to claim 1 or 2, characterized in that: Also includes: a third valve (54a, 54b) for regulating the flow of the refrigerant flowing through the heat exchanger; as well as utilizing fans (56a, 56b) that supply air to the heat exchanger, In the second operation, in the pipe connection state in which the heat exchanger functions as a radiator, the third valve is closed and the operation using the fan is stopped.

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