Patent Publication Number: US-2022214082-A1

Title: Refrigeration cycle apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of application Ser. No. 16/976,813 filed on Aug. 31, 2020, which is a U.S. national stage application of International Application PCT/JP2018/018168 filed on May 10, 2018, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a refrigeration cycle apparatus. 
     BACKGROUND 
     Japanese Patent Laying-Open No. 2015-117936 discloses an air conditioner including an outdoor heat exchanger that is divided into a plurality of unit flow paths, in which at least two of the plurality of unit flow paths are connected to each other in series during cooling operation and connected to each other in parallel during heating operation. The above-mentioned air conditioner has improved heat exchange efficiency by proper selection and use of the number and the length of the unit flow paths in the cooling operation and the heating operation. 
     PATENT LITERATURE 
     PTL 1: Japanese Patent Laying-Open No. 2015-117936 
     The above-mentioned air conditioner, however, requires a plurality of pipes to connect a check valve and a solenoid valve to each of the plurality of unit flow paths. Routing of these plurality of pipes is also complicated in the above-mentioned air conditioner. The above-mentioned air conditioner thus requires a large space to install the plurality of pipes, making downsizing difficult. The above-mentioned air conditioner also requires a large number of processing steps for connection of each the plurality of pipes, thus increasing manufacturing cost. 
     Further, if the above-mentioned air conditioner has varying specifications of the outdoor heat exchanger such as the number of the plurality of unit flow paths depending on the horsepower of the air conditioner, whether or not the air conditioner delivers high performance, and the like, it is required to redesign the pipes and routing thereof. 
     SUMMARY 
     A main object of the present invention is to provide a refrigeration cycle apparatus which has simplified routing of pipes compared to the above-mentioned air conditioner, and which eliminates the need to redesign the routing of pipes for each specification of an outdoor heat exchanger. 
     A refrigeration cycle apparatus according to the present invention includes a refrigerant circuit through which refrigerant circulates. The refrigerant circuit includes a compressor, a first flow path switching unit, a second flow path switching unit, a first heat exchanger, a second heat exchanger, and a third heat exchanger. The first heat exchanger has a first flow-in/out portion and a second flow-in/out portion to/from which the refrigerant flows in/out. The second heat exchanger has a third flow-in/out portion and a fourth flow-in/out portion to/from which the refrigerant flows in/out. The first flow path switching unit is configured to switch between a first state and a second state. In the first state, at least one of the first heat exchanger and the second heat exchanger is configured to serve as a condenser while the third heat exchanger is configured to serve as an evaporator. In the second state, at least one of the first heat exchanger and the second heat exchanger is configured to serve as an evaporator while the third heat exchanger is configured to serve as a condenser. The second flow path switching unit has a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port through which the refrigerant flows in/out. The first port is connected to a discharge port of the compressor via the first flow path switching unit in the first state, and is connected to a suction port of the compressor via the first flow path switching unit in the second state. The second port is connected to the first flow-in/out portion. The third port is connected to the third flow-in/out portion. The fourth port is connected to the second flow-in/out portion. The fifth port is connected to the fourth flow-in/out portion. The sixth port is connected to the third heat exchanger. The second flow path switching unit is configured to switch between a third state and a fourth state. In the third state, the first port, the second port, the first heat exchanger, the fourth port, the third port, the second heat exchanger, the fifth port and the sixth port are successively connected in series. In the fourth state, the sixth port, the fourth port, the first heat exchanger, the second port and the first port are successively connected in series, and the sixth port, the fifth port, the second heat exchanger, the third port and the first port are successively connected in series. 
     In the refrigeration cycle apparatus according to the present invention, switching between the third state in which a first outdoor heat exchanger and a second outdoor heat exchanger are connected in series and the fourth state in which they are connected in parallel is implemented in the second flow path switching unit. According to the present invention, therefore, a refrigeration cycle apparatus which has simplified routing of pipes outside the second flow path switching unit compared to the above-mentioned air conditioner, and which eliminates the need to redesign the routing of pipes for each specification of the outdoor heat exchangers can be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a refrigeration cycle apparatus according to a first embodiment. 
         FIG. 2  shows a diagram (A) illustrating a refrigerant flow path in a second flow path switching unit shown in  FIG. 1  when the second flow path switching unit is in a third state, a diagram (B) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 1  when the second flow path switching unit is in a fourth state, a diagram (C) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 1  when the second flow path switching unit is in a fifth state, and a diagram (D) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 1  when the second flow path switching unit is in a sixth state. 
         FIG. 3  illustrates a refrigerant flow path in an outdoor unit when the second flow path switching unit shown in  FIG. 1  is in the third state. 
         FIG. 4  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 1  is in the fourth state. 
         FIG. 5  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 1  is in the fifth state. 
         FIG. 6  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 1  is in the sixth state. 
         FIG. 7  illustrates a refrigeration cycle apparatus according to a second embodiment. 
         FIG. 8  shows a diagram (A) illustrating a refrigerant flow path in a second flow path switching unit shown in  FIG. 7  when the second flow path switching unit is in a third state, a diagram (B) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 7  when the second flow path switching unit is in a fourth state, a diagram (C) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 7  when the second flow path switching unit is in a fifth state, a diagram (D) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 7  when the second flow path switching unit is in a sixth state, and a diagram (E) illustrating a refrigerant flow path in the second flow path switching unit shown in  FIG. 7  when the second flow path switching unit is in a seventh state. 
         FIG. 9  illustrates a refrigerant flow path in an outdoor unit when the second flow path switching unit shown in  FIG. 7  is in the third state. 
         FIG. 10  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 7  is in the fourth state. 
         FIG. 11  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 7  is in the fifth state. 
         FIG. 12  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 7  is in the sixth state. 
         FIG. 13  illustrates a refrigerant flow path in the outdoor unit when the second flow path switching unit shown in  FIG. 7  is in the seventh state. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be described hereinafter in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same characters and description thereof will not be repeated in principle. 
     First Embodiment 
     As shown in  FIG. 1 , a refrigeration cycle apparatus  100  according to a first embodiment includes a compressor  1 , a four-way valve  2  as a first flow path switching unit, a first outdoor heat exchanger  3  as a first heat exchange unit, a second outdoor heat exchanger  4  as a second heat exchange unit, a first indoor heat exchanger  6   a  and a second indoor heat exchanger  6   b  as a third heat exchange unit, a first decompression unit  7   a , a second decompression unit  7   b , a third decompression unit  8   a , a fourth decompression unit  8   b , on-off valves  9   a ,  9   b ,  9   c ,  9   d , and a second flow path switching unit  10 , to form a refrigerant circuit through which refrigerant circulates. 
     From a different viewpoint, refrigeration cycle apparatus  100  includes an outdoor unit  30 , a first indoor unit  40   a , a second indoor unit  40   b , and a relay unit  50 . In outdoor unit  30 , there are disposed first circuitry of the refrigerant circuit including compressor  1 , four-way valve  2 , first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and second flow path switching unit  10 , and an outdoor fan  35 . In first indoor unit  40   a , there are disposed second circuitry of the refrigerant circuit including first indoor heat exchanger  6   a  and first decompression unit  7   a , and an indoor fan (not shown). In second indoor unit  40   b , there are disposed third circuitry of the refrigerant circuit including second indoor heat exchanger  6   b  and second decompression unit  7   b , and an indoor fan (not shown). In relay unit  50 , there is disposed fourth circuitry of the refrigerant circuit including third decompression unit  8   a , fourth decompression unit  8   b  and the plurality of on-off valves  9   a ,  9   b ,  9   c ,  9   d.    
     The first circuitry of the refrigerant circuit disposed in outdoor unit  30  and the fourth circuitry of the refrigerant circuit disposed in relay unit  50  are connected to each other via a first pipe C 1  and a second pipe C 2 . The fourth circuitry of the refrigerant circuit disposed in relay unit  50  and the second circuitry of the refrigerant circuit disposed in first indoor unit  40   a  are connected to each other via the two pipes. The fourth circuitry of the refrigerant circuit disposed in relay unit  50  and the third circuitry of the refrigerant circuit disposed in second indoor unit  40   b  are connected to each other via the two pipes. The second circuitry and the third circuitry of the refrigerant circuit are connected in parallel with the fourth circuitry. 
     Compressor  1  has a discharge port through which the refrigerant is discharged, and a suction port through which the refrigerant is sucked. 
     Four-way valve  2  has a first opening connected to the discharge port of compressor  1  via a discharge pipe, a second opening connected to the suction port of compressor  1  via a suction pipe, a third opening connected to first pipe C 1 , and a fourth opening connected to second pipe C 2  via second flow path switching unit  10 . The fourth opening in four-way valve  2  is connected to a first port P 1  of second flow path switching unit  10 . Four-way valve  2  switches between a first state in which each of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  serves as a condenser while the third heat exchange unit serves as an evaporator, and a second state in which each of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  serves as an evaporator while the third heat exchange unit serves as a condenser. Solid line arrows shown in  FIG. 1  indicate a flow direction of the refrigerant circulating through the refrigerant circuit when refrigeration cycle apparatus  100  is in the first state. Dotted line arrows shown in  FIG. 1  indicate a flow direction of the refrigerant circulating through the refrigerant circuit when refrigeration cycle apparatus  100  is in the second state. 
     First outdoor heat exchanger  3  includes a first distribution unit  3   a  as a first flow-in/out portion and a second distribution unit  3   b  as a second flow-in/out portion to/from which the refrigerant flows in/out, and a first heat exchange unit  3   c  disposed between first distribution unit  3   a  and second distribution unit  3   b . First heat exchange unit  3   c  has a plurality of heat transfer tubes and a plurality of fins, for example. First distribution unit  3   a  is connected to one end of each of the plurality of heat transfer tubes. Second distribution unit  3   b  is connected to the other end of each of the plurality of heat transfer tubes. 
     Second outdoor heat exchanger  4  includes a third distribution unit  4   a  as a third flow-in/out portion and a fourth distribution unit  4   b  as a fourth flow-in/out portion to/from which the refrigerant flows in/out, and a second heat exchange unit  4   c  disposed between third distribution unit  4   a  and fourth distribution unit  4   b . Second heat exchange unit  4   c  has a plurality of heat transfer tubes and a plurality of fins, for example. Third distribution unit  4   a  is connected to one end of each of the plurality of heat transfer tubes. Fourth distribution unit  4   b  is connected to the other end of each of the plurality of heat transfer tubes. 
     First outdoor heat exchanger  3  may have a capacity equal to or different from that of second outdoor heat exchanger  4 . First outdoor heat exchanger  3  may have a capacity greater than or smaller than that of second outdoor heat exchanger  4 . 
     In the first state and the second state, first distribution unit  3   a  is disposed on a gas refrigerant side of first outdoor heat exchanger  3 , and second distribution unit  3   b  is disposed on a liquid refrigerant side of first outdoor heat exchanger  3 . In the first state and the second state, third distribution unit  4   a  is disposed on a gas refrigerant side of second outdoor heat exchanger  4 , and fourth distribution unit  4   b  is disposed on a liquid refrigerant side of second outdoor heat exchanger  4 . The liquid refrigerant side of a heat exchanger means a side from which liquid refrigerant flows out when the heat exchanger serves as a condenser, and to which liquid refrigerant flows in when the heat exchanger serves as an evaporator. The liquid refrigerant means liquid single-phase refrigerant or gas-liquid two-phase refrigerant, which includes a high amount of liquid-phase refrigerant. The gas refrigerant side of a heat exchanger, on the other hand, means a side to which gas refrigerant flows in when the heat exchanger serves as a condenser, and from which gas refrigerant flows out when the heat exchanger serves as an evaporator. The gas refrigerant means gas single-phase refrigerant. 
     Second flow path switching unit  10  has first port P 1 , a second port P 2 , a third port P 3 , a fourth port P 4 , a fifth port P 5 , and a sixth port P 6  through which the refrigerant flows in/out. Second flow path switching unit  10  is configured as a single unit. 
     As described above, first port P 1  is connected to the fourth opening in four-way valve  2 . First port P 1  is thereby connected to the discharge port of compressor  1  via four-way valve  2  in the first state, and connected to the suction port of compressor  1  via four-way valve  2  in the second state. Second port P 2  is connected to first distribution unit  3   a . Third port P 3  is connected to third distribution unit  4   a . Fourth port P 4  is connected to second distribution unit  3   b . Fifth port P 5  is connected to fourth distribution unit  4   b . Sixth port P 6  is connected to second pipe C 2 . Sixth port P 6  is connected to first indoor heat exchanger  6   a  and second indoor heat exchanger  6   b  via second pipe C 2  and relay unit  50 . 
     As shown in  FIGS. 2 to 6 , second flow path switching unit  10  switches among a third state, a fifth state, a sixth state and a fourth state. In the third state shown in  FIGS. 2(A)  and  3 , first port P 1 , second port P 2 , fourth port P 4 , third port P 3 , fifth port P 5  and sixth port P 6  are successively connected in series. In the fourth state shown in  FIGS. 2(B)  and  4 , fourth port P 4  and fifth port P 5  are connected in parallel with sixth port P 6 , and second port P 2  and third port P 3  are connected in parallel with first port P 1 . In other words, in the fourth state, sixth port P 6 , fourth port P 4 , first outdoor heat exchanger  3 , second port P 2  and first port P 1  are successively connected in series, and sixth port P 6 , fifth port P 5 , second outdoor heat exchanger  4 , third port P 3  and first port P 1  are successively connected in series. In the fifth state shown in  FIGS. 2(C)  and  5 , first port P 1 , second port P 2 , fourth port P 4  and sixth port P 6  are successively connected in series. In the sixth state shown in  FIGS. 2(D)  and  6 , first port P 1 , third port P 3 , fifth port P 5  and sixth port P 6  are successively connected in series. 
     From a different viewpoint, as shown in  FIG. 2(A) , second flow path switching unit  10  has, in the third state, a first flow path connecting first port P 1  to second port P 2 , a second flow path connecting fourth port P 4  to third port P 3 , and a third flow path connecting fifth port P 5  to sixth port P 6 . As shown in  FIG. 2(B) , second flow path switching unit  10  has, in the fourth state, the first flow path, a fifth flow path, the third flow path, and a fourth flow path. As shown in  FIG. 2(C) , second flow path switching unit  10  has, in the fifth state, the first flow path, and the fourth flow path connecting fourth port P 4  to sixth port P 6 . As shown in  FIG. 2(D) , second flow path switching unit  10  has, in the sixth state, the fifth flow path connecting first port P 1  to third port P 3 , and the third flow path. Arrows shown in  FIGS. 2(A)  to (D) indicate flow directions of the refrigerant in the respective states. 
     One of the third state, the fifth state and the sixth state is selected depending on the cooling load when the refrigeration cycle apparatus is in the first state. The fourth state is selected when the refrigeration cycle apparatus is in the second state. 
     Second flow path switching unit  10  may have any configuration so long as it is able to switch among the third state, the fifth state, the sixth state and the fourth state. One configuration example of second flow path switching unit  10  is described below. 
     As shown in  FIGS. 3 to 7 , second flow path switching unit  10  includes a first pipe path connecting first port P 1  to sixth port P 6 , and a second pipe path, a third pipe path, a fourth pipe path and a fifth pipe path that are successively connected to the first pipe path in a direction in which the first pipe path extends from first port P 1  toward sixth port P 6 . The first pipe path extends linearly, for example. 
     The second pipe path connects second port P 2  to the first pipe path. The third pipe path connects third port P 3  to the first pipe path. The fourth pipe path connects fourth port P 4  to the first pipe path. The fifth pipe path connects fifth port P 5  to the first pipe path. A connection portion between the first pipe path and the second pipe path is defined as a first connection portion, a connection portion between the first pipe path and the third pipe path is defined as a second connection portion, a connection portion between the first pipe path and the fourth pipe path is defined as a third connection portion, and a connection portion between the first pipe path and the fifth pipe path is defined as a fourth connection portion. 
     As shown in  FIGS. 3 to 7 , second flow path switching unit  10  further includes, for example, a first on-off valve  11 , a second on-off valve  12 , a third on-off valve  13 , a fourth on-off valve  14 , a fifth on-off valve  15 , a sixth on-off valve  16 , and a seventh on-off valve  17 . First on-off valve  11  opens and closes the second pipe path. Second on-off valve  12  opens and closes the third pipe path. Third on-off valve  13  opens and closes the fourth pipe path. Fourth on-off valve  14  opens and closes the fifth pipe path. Fifth on-off valve  15  opens and closes a portion located between the first connection portion and the second connection portion in the first pipe path. Sixth on-off valve  16  opens and closes a portion located between the second connection portion and the third connection portion in the first pipe path. Seventh on-off valve  17  opens and closes a portion located between the third connection portion and the fourth connection portion in the first pipe path. 
     As shown in  FIG. 3 , in the third state, first on-off valve  11 , second on-off valve  12 , third on-off valve  13 , fourth on-off valve  14  and sixth on-off valve  16  are opened, while fifth on-off valve  15  and seventh on-off valve  17  are closed. 
     As shown in  FIG. 4 , in the fourth state, first on-off valve  11 , second on-off valve  12 , third on-off valve  13 , fourth on-off valve  14 , fifth on-off valve  15  and seventh on-off valve  17  are opened, while sixth on-off valve  16  is closed. 
     As shown in  FIG. 5 , in the fifth state, first on-off valve  11 , third on-off valve  13  and seventh on-off valve  17  are opened, while second on-off valve  12 , fourth on-off valve  14 , fifth on-off valve  15  and sixth on-off valve  16  are closed. 
     As shown in  FIG. 6 , in the sixth state, second on-off valve  12 , fourth on-off valve  14 , fifth on-off valve  15  and seventh on-off valve  17  are opened, while first on-off valve  11 , third on-off valve  13  and sixth on-off valve  16  are closed. 
     Second flow path switching unit  10  may be divided, for example, into a first block and a second block, and sixth on-off valve  16  disposed between the first block and the second block. The first block has a portion of the first pipe path, the second pipe path, the third pipe path, first on-off valve  11 , second on-off valve  12  and fifth on-off valve  15 . The second block has another portion of the first pipe path, the fourth pipe path, the fifth pipe path, fourth on-off valve  14 , fifth on-off valve  15  and seventh on-off valve  17 . The first block is disposed, in the first state and the second state, on the gas refrigerant side with respect to first outdoor heat exchanger  3  and second outdoor heat exchanger  4 . The second block is disposed, in the first state and the second state, on the liquid refrigerant side with respect to first outdoor heat exchanger  3  and second outdoor heat exchanger  4 . 
     Each of first on-off valve  11 , second on-off valve  12  and fifth on-off valve  15  included in the first block has a Cv value higher than that of each of third on-off valve  13 , fourth on-off valve  14  and seventh on-off valve  17  included in the second block, for example. 
     Each of the portion of the first pipe path, the second pipe path and the third pipe path included in the first block has an inner diameter greater than that of each of the another portion of the first pipe path, the fourth pipe path and the fifth pipe path included in the second block, for example. 
     Second port P 2 , third port P 3 , fourth port P 4  and fifth port P 5  are disposed on the same plane, for example. A plane on which first port P 1  is disposed is arranged, for example, opposite to a plane on which sixth port P 6  is disposed. First port P 1 , second port P 2 , third port P 3 , fourth port P 4 , fifth port P 5  and sixth port P 6  may be disposed on the same plane. 
     As shown in  FIGS. 1, and 3 to 4 , in addition to compressor  1 , four-way valve  2 , first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and second flow path switching unit  10 , for example, the first circuitry of the refrigerant circuit only has the discharge pipe, the suction pipe, a connection pipe connecting the third opening in four-way valve  2  to first pipe C 1 , a connection pipe connecting the fourth opening in four-way valve  2  to first port P 1 , a connection pipe connecting second port P 2  to first distribution unit  3   a , a connection pipe connecting third port P 3  to third distribution unit  4   a , a connection pipe connecting fourth port P 4  to second distribution unit  3   b , a connection pipe connecting fifth port P 5  to fourth distribution unit  4   b , and a connection pipe connecting sixth port P 6  to the second pipe. 
     First indoor unit  40   a , second indoor unit  40   b  and relay unit  50  may have any configuration, but are provided to be able to perform, for example, cooling-only operation, cooling-dominated operation, heating-only operation, and heating-dominated operation. First indoor unit  40   a , second indoor unit  40   b  and relay unit  50  have configurations shown in  FIG. 1 , for example. 
     Operation of refrigeration cycle apparatus  100  is now described. 
     Cooling Operation 
     When refrigeration cycle apparatus  100  is in cooling operation, the third state, the fifth state or the sixth state is implemented depending on the cooling load. The third state is selected when the cooling load is relatively high. The third state is implemented during cooling-only operation, for example. The fifth state and the sixth state are implemented during cooling-dominated operation, for example. 
     As shown in  FIG. 3 , in the third state, first outdoor heat exchanger  3  and second outdoor heat exchanger  4  are connected in series in the first circuitry. Specifically, gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . 
     In the third state, with first on-off valve  11  opened and fifth on-off valve  15  closed, the entire gas single-phase refrigerant that has flowed into the first pipe path passes through the second pipe path and flows into first distribution unit  3   a , and exchanges heat with outdoor air and condenses in first outdoor heat exchanger  3 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in first outdoor heat exchanger  3  passes through second distribution unit  3   b , and flows through fourth port P 4  into the fourth pipe path. With third on-off valve  13 , sixth on-off valve  16  and second on-off valve  12  opened and fifth on-off valve  15  and seventh on-off valve  17  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fourth pipe path, the first pipe path and the third pipe path and flows into third distribution unit  4   a , and exchanges heat with outdoor air and condenses in second outdoor heat exchanger  4 . The liquid single-phase refrigerant condensed in second outdoor heat exchanger  4  passes through fourth distribution unit  4   b , and flows through sixth port P 6  into the fifth pipe path. With fourth on-off valve  14  opened and seventh on-off valve  17  closed, the entire liquid single-phase refrigerant that has flowed into the fifth pipe path passes through the fifth pipe path and the first pipe path and flows out through second port P 2 . The liquid single-phase refrigerant that has flowed out through second port P 2  flows into relay unit  50  via the second pipe. 
     In the second circuitry, the third circuitry and the fourth circuitry of the refrigerant circuit, the refrigerant is appropriately distributed by relay unit  50  depending on whether the operational status of refrigeration cycle apparatus  100  is cooling-only operation or cooling-dominated operation. During the cooling-only operation, for example, a part of the liquid single-phase refrigerant that has flowed into relay unit  50  is supplied to first indoor unit  40   a , decompressed in first decompression unit  7   a , then exchanges heat with indoor air and evaporates in first indoor heat exchanger  6   a , and turns into gas single-phase refrigerant. Further, the remaining liquid single-phase refrigerant that has flowed into relay unit  50  is supplied to second indoor unit  40   b , decompressed in second decompression unit  7   b , then exchanges heat with indoor air and evaporates in second indoor heat exchanger  6   b , and turns into gas single-phase refrigerant. The gas single-phase refrigerants that have flowed out of the indoor units join together in relay unit  50 , and the joined refrigerant passes through the first pipe and is sucked through the suction port of compressor  1 . The gas single-phase refrigerant is compressed by compressor  1 , and then discharged through the discharge port again. 
     As shown in  FIG. 5 , in the fifth state, the refrigerant is not supplied to second outdoor heat exchanger  4 , and second outdoor heat exchanger  4  does not serve as a condenser. In the fifth state, only first outdoor heat exchanger  3  serves as a condenser. Specifically, the gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . With first on-off valve  11  opened and fifth on-off valve  15  closed, the entire gas single-phase refrigerant that has flowed into the first pipe path passes through the second pipe path and flows into first distribution unit  3   a , and exchanges heat with outdoor air and condenses in first outdoor heat exchanger  3 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in first outdoor heat exchanger  3  passes through second distribution unit  3   b , and flows through fourth port P 4  into the fourth pipe path. With third on-off valve  13  and seventh on-off valve  17  opened and fourth on-off valve  14  and sixth on-off valve  16  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fourth pipe path and the first pipe path and flows out through second port P 2 . 
     As shown in  FIG. 6 , in the sixth state, the refrigerant is not supplied to first outdoor heat exchanger  3 , and first outdoor heat exchanger  3  does not serve as a condenser. In the fifth state, only second outdoor heat exchanger  4  serves as a condenser. Specifically, the gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . With second on-off valve  12  and fifth on-off valve  15  opened and first on-off valve  11  and sixth on-off valve  16  closed, the entire gas single-phase refrigerant that has flowed into the first pipe path passes through the third pipe path and flows into third distribution unit  4   a , and exchanges heat with outdoor air and condenses in second outdoor heat exchanger  4 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in second outdoor heat exchanger  4  passes through fourth distribution unit  4   b , and flows through sixth port P 6  into the fifth pipe path. With fourth on-off valve  14  opened and seventh on-off valve  17  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fifth pipe path and the first pipe path and flows out through second port P 2 . 
     Heating Operation 
     When refrigeration cycle apparatus  100  is in heating operation, the fourth state is implemented. As shown in  FIG. 4 , in the fourth state, first outdoor heat exchanger  3  and second outdoor heat exchanger  4  are connected in parallel in the first circuitry. Specifically, the gas single-phase refrigerant discharged from compressor  1  condenses in at least one of first indoor heat exchanger  6   a  and second indoor heat exchanger  6   b  shown in  FIG. 1 , and turns into liquid single-phase refrigerant. The liquid single-phase refrigerant is decompressed in first decompression unit  7   a  or second decompression unit  7   b , and turns into gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant passes through second pipe C 2  and flows through sixth port P 6  into the first pipe path of second flow path switching unit  10 . 
     In the fourth state, third on-off valve  13 , fourth on-off valve  14  and seventh on-off valve  17  are opened, while sixth on-off valve  16  is closed. Thus, a part of the gas-liquid two-phase refrigerant that has flowed into the first pipe path passes through the third pipe path and flows into second distribution unit  3   b , exchanges heat with outdoor air and evaporates in first outdoor heat exchanger  3 , and turns into gas single-phase refrigerant. The remaining gas-liquid two-phase refrigerant that has flowed into the first pipe path passes through the fourth pipe path and flows into fourth distribution unit  4   b , exchanges heat with outdoor air and evaporates in second outdoor heat exchanger  4 , and turns into gas single-phase refrigerant. 
     The gas single-phase refrigerant evaporated in first outdoor heat exchanger  3  passes through first distribution unit  3   a , and flows through second port P 2  into the second pipe path. The gas single-phase refrigerant evaporated in second outdoor heat exchanger  4  passes through third distribution unit  4   a , and flows through third port P 3  into the third pipe path. With first on-off valve  11 , second on-off valve  12  and fifth on-off valve  15  opened and sixth on-off valve  16  closed, the entire gas single-phase refrigerant passes through the first pipe path and flows out through first port P 1 . The gas single-phase refrigerant that has flowed out through first port P 1  is sucked through the suction port of compressor  1 . 
     Functions and Effects 
     Refrigeration cycle apparatus  100  includes compressor  1 , four-way valve  2 , second flow path switching unit  10 , first outdoor heat exchanger  3 , second outdoor heat exchanger  4 , first indoor heat exchanger  6   a , second indoor heat exchanger  6   b , and second flow path switching unit  10 , to form a refrigerant circuit through which refrigerant circulates. First outdoor heat exchanger  3  has first distribution unit  3   a  and second distribution unit  3   b  to/from which the refrigerant flows in/out. Second outdoor heat exchanger  4  has third distribution unit  4   a  and fourth distribution unit  4   b  to/from which the refrigerant flows in/out. Four-way valve  2  switches between the first state in which at least one of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  serves as a condenser, and the second state in which at least one of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  serves as an evaporator. Second flow path switching unit  10  has first port P 1 , second port P 2 , third port P 3 , fourth port P 4 , fifth port P 5 , and sixth port P 6  through which the refrigerant flows in/out. First port P 1  is connected to the discharge port of compressor  1  via four-way valve  2  in the first state, and is connected to the suction port of compressor  1  via four-way valve  2  in the second state. Second port P 2  is connected to first distribution unit  3   a . Third port P 3  is connected to third distribution unit  4   a . Fourth port P 4  is connected to second distribution unit  3   b . Fifth port P 5  is connected to fourth distribution unit  4   b . Sixth port P 6  is connected to the third heat exchanger. Second flow path switching unit  10  switches between the third state in which first port P 1 , second port P 2 , the first heat exchanger, fourth port P 4 , third port P 3 , the second heat exchanger, fifth port P 5  and sixth port P 6  are successively connected in series, and the fourth state in which sixth port P 6 , fourth port P 4 , first outdoor heat exchanger  3 , second port P 2  and first port P 1  are successively connected in series, and sixth port P 6 , fifth port P 5 , second outdoor heat exchanger  4 , third port P 3  and first port P 1  are successively connected in series. 
     According to refrigeration cycle apparatus  100 , second flow path switching unit  10  switches between the third state in which first outdoor heat exchanger  3  and second outdoor heat exchanger  4  are connected in series, and the fourth state in which first outdoor heat exchanger  3  and second outdoor heat exchanger  4  are connected in parallel. Thus, the third state is implemented during cooling operation and the fourth state is implemented during heating operation by second flow path switching unit  10 , allowing refrigeration cycle apparatus  100  to have a coefficient of performance COP higher than that of a conventional refrigeration cycle apparatus which does not include second flow path switching unit  10  and in which the switching does not takes place. 
     For example, in refrigeration cycle apparatus  100  in which the third state is implemented during the cooling operation, the refrigerant flowing through one heat transfer tube of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  during the cooling operation has an increased flow rate, and has an increased flow velocity, leading to an increased heat transfer rate in the pipe, compared to a refrigeration cycle apparatus in which the fourth state is maintained during the cooling and heating operations. As a result, refrigeration cycle apparatus  100  has condensation heat transfer performance higher than that of the above-mentioned refrigeration cycle apparatus, and refrigeration cycle apparatus  100  has a coefficient of performance COP higher than that of the above-mentioned refrigeration cycle apparatus. 
     In addition, for example, in refrigeration cycle apparatus  100  in which the fourth state is implemented during the heating operation, a pressure loss of the refrigerant flowing through the heat transfer tubes of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  during the heating operation can be reduced, compared to a refrigeration cycle apparatus in which the third state is maintained during the cooling and heating operations. As a result, refrigeration cycle apparatus  100  has a coefficient of performance COP higher than that of the above-mentioned refrigeration cycle apparatus. 
     Further, in refrigeration cycle apparatus  100 , second flow path switching unit  10  is configured as a single unit having first port P 1 , second port P 2 , third port P 3 , fourth port P 4 , fifth port P 5  and sixth port P 6 . Thus, switching among the third state, the fifth state, the sixth state and the fourth state is implemented by switching of the flow paths in second flow path switching unit  10 . As a result, pipes connecting the ports of second flow path switching unit  10  to the components other than second flow path switching unit  10  disposed in outdoor unit  30  in a one-to-one relationship are the only pipes forming the first circuitry in outdoor unit  30  outside second flow path switching unit  10 . Accordingly, routing of the pipes forming the first circuitry in outdoor unit  30  outside second flow path switching unit  10  is simplified compared to routing of pipes connecting a check valve and an on-off valve to a plurality of unit flow paths in the above-mentioned conventional air conditioner. 
     Further, the relative positions of first port P 1 , second port P 2 , third port P 3 , fourth port P 4 , fifth port P 5  and sixth port P 6  of second flow path switching unit  10  do not need to be changed upon connection to first outdoor heat exchanger  3  and second outdoor heat exchanger  4  having different specifications. Thus, second flow path switching unit  10  can remain unchanged among a plurality of refrigeration cycle apparatuses  100  having different horsepowers and the like. That is, in refrigeration cycle apparatus  100 , it is unnecessary to change the design of the routing of the refrigerant pipes depending on the horsepower, the time when the apparatus is put into use, whether or not the apparatus is a so-called high-performance apparatus, and the like. That is, in refrigeration cycle apparatus  100 , a standardized design of the first circuitry of the refrigerant circuit in outdoor unit  30  is possible. 
     In this manner, in refrigeration cycle apparatus  100 , the routing of the refrigerant pipes disposed in outdoor unit  30  can be simplified to reduce the length of the refrigerant pipes, compared to a refrigeration cycle apparatus in which the routing of refrigerant pipes including a check valve and a solenoid valve needs to be designed depending on the horsepower and the like of the refrigeration cycle apparatus. As a result, the space to install the refrigerant pipes in outdoor unit  30  is reduced compared to the above-mentioned refrigeration cycle apparatus, and the manufacturing cost of refrigeration cycle apparatus  100  is reduced compared to the above-mentioned refrigeration cycle apparatus. 
     In refrigeration cycle apparatus  100 , second flow path switching unit  10  switches among the third state, the fourth state, the fifth state in which first port P 1 , second port P 2 , the first heat exchanger, fourth port P 4  and sixth port P 6  are successively connected in series, and the sixth state in which first port P 1 , third port P 3 , the second heat exchanger, fifth port P 5  and sixth port P 6  are successively connected in series. One of the third state, the fifth state and the sixth state is selected when the refrigeration cycle apparatus is in the first state. The fourth state is selected when the refrigeration cycle apparatus is in the second state. 
     According to refrigeration cycle apparatus  100 , second flow path switching unit  10  switches among, in addition to the third state and the fourth state, the fifth state in which the refrigerant is not supplied to second outdoor heat exchanger  4 , and the sixth state in which the refrigerant is not supplied to first outdoor heat exchanger  3 . The fifth state and the sixth state are implemented during cooling operation with a relatively low air-conditioning load (during cooling low-load operation). 
     When outdoor air temperature is low during cooling-dominated operation, for example, heat dissipation performance of each of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  becomes excessive if each of them is operated as a condenser, resulting in a reduction in condensing pressure compared to that during normal cooling operation. As a result, gas-phase refrigerant to be supplied to the indoor heat exchanger in heating operation decreases in saturation temperature, resulting in inability to obtain required heating performance. In addition, if a compression ratio (condensing pressure/evaporating pressure) is maintained at low level due to the reduction in condensing pressure, the reliability of the compressor decreases. 
     In such a case, in refrigeration cycle apparatus  100 , the fifth state or the sixth state is implemented by second flow path switching unit  10 , allowing a reduction in heat dissipation performance of the condenser, to suppress the reduction in condensing pressure. As a result, in refrigeration cycle apparatus  100 , required heating performance can be obtained even in the case such as described above. Further, in this case, the reliability of compressor  1  is ensured because the reduction in condensing pressure is suppressed in refrigeration cycle apparatus  100 . 
     In addition, when first outdoor heat exchanger  3  and second outdoor heat exchanger  4  have different capacities, second flow path switching unit  10  can switch between the fifth state and the sixth state depending on the air-conditioning load. Variation in condensing pressure is thereby suppressed. 
     Second Embodiment 
     A refrigeration cycle apparatus  101  according to a second embodiment has a configuration basically similar to that of refrigeration cycle apparatus  100  according to the first embodiment, but differs in that the refrigerant circuit includes a second flow path switching unit  20  instead of second flow path switching unit  10 , and further includes a third outdoor heat exchanger  5  as a fourth heat exchange unit. 
     Third outdoor heat exchanger  5  has a fifth distribution unit  5   a  as a fifth flow-in/out portion and a sixth distribution unit  5   b  as a sixth flow-in/out portion to/from which the refrigerant flows in/out. 
     Second flow path switching unit  20  has a configuration basically similar to that of second flow path switching unit  10 , but differs in that it further has a seventh port P 7  and an eighth port P 8  through which the refrigerant flows in/out. Seventh port P 7  is connected to fifth distribution unit  5   a . Eighth port P 8  is connected to sixth distribution unit  5   b.    
     Second flow path switching unit  10  switches among the third state, the fifth state, the sixth state, the fourth state, and a seventh state. 
     In the third state shown in  FIGS. 8(A)  and  9 , first port P 1 , second port P 2 , fourth port P 4 , third port P 3 , fifth port P 5  and sixth port P 6  are successively connected in series, and first port P 1 , seventh port P 7 , eighth port P 8 , third port P 3 , fifth port P 5  and sixth port P 6  are successively connected in series. That is, in the third state, first outdoor heat exchanger  3  and second outdoor heat exchanger  4  are connected in series, and third outdoor heat exchanger  5  and second outdoor heat exchanger  4  are connected in series. From a different viewpoint, in the third state, first outdoor heat exchanger  3  and third outdoor heat exchanger  5  are connected in parallel with second outdoor heat exchanger  4 . 
     As shown in  FIG. 8(A) , in the third state, in addition to the first flow path, the second flow path and the third flow path, second flow path switching unit  20  further has a sixth flow path connecting first port P 1  to seventh port P 7 , and a seventh flow path connecting eighth port P 8  to third port P 3 . In the third state, the first flow path and the sixth flow path are connected in parallel, and the second flow path and the seventh flow path are connected in parallel. 
     In the fourth state shown in  FIGS. 8(B)  and  10 , fourth port P 4 , fifth port P 5  and eighth port P 8  are connected in parallel with sixth port P 6 , and second port P 2 , third port P 3  and seventh port P 7  are connected in parallel with first port P 1 . Second flow path switching unit  20  has, in the fourth state, the first flow path, the fifth flow path, the sixth flow path, the third flow path, the fourth flow path and the seventh flow path. The first flow path, the fifth flow path and the sixth flow path are connected to one another in parallel. The third flow path, the fourth flow path and the seventh flow path are connected to one another in parallel. That is, in the fourth state, first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and third outdoor heat exchanger  5  are connected in parallel. 
     In the fifth state shown in  FIGS. 8(C)  and  11 , a state similar to the fifth state shown in  FIGS. 2(C)  and  5  is implemented. Second flow path switching unit  20  has, in the fifth state, only the first flow path and the fourth flow path. In the sixth state shown in  FIGS. 8(D)  and  12 , a state similar to the sixth state shown in  FIGS. 2(D)  and  6  is implemented. Second flow path switching unit  20  has, in the sixth state, only the fifth flow path and the third flow path. That is, in the fifth state, the refrigerant flowing through the first circuitry is not supplied to second outdoor heat exchanger  4  and third outdoor heat exchanger  5 , and the refrigerant is supplied only to first outdoor heat exchanger  3 . In the sixth state, the refrigerant flowing through the first circuitry is not supplied to first outdoor heat exchanger  3  and third outdoor heat exchanger  5 , and the refrigerant is supplied only to second outdoor heat exchanger  4 . 
     In the seventh state shown in  FIGS. 8(E)  and  13 , first port P 1 , seventh port P 7 , eighth port P 8  and sixth port P 6  are successively connected in series. Second flow path switching unit  20  has, in the seventh state, only the sixth flow path and an eighth flow path. That is, in the seventh state, the refrigerant flowing through the first circuitry is not supplied to first outdoor heat exchanger  3  and second outdoor heat exchanger  4 , and the refrigerant is supplied only to third outdoor heat exchanger  5 . Arrows shown in  FIGS. 8(A)  to (E) indicate flow directions of the refrigerant in the respective states. 
     The seventh state is selected when refrigeration cycle apparatus  100  is in the first state. 
     In addition to the first pipe path, the second pipe path, the third pipe path, the fourth pipe path, the fifth pipe path, first on-off valve  11 , second on-off valve  12 , third on-off valve  13 , fourth on-off valve  14 , fifth on-off valve  15 , sixth on-off valve  16  and seventh on-off valve  17 , second flow path switching unit  20  further includes a sixth pipe path, a seventh pipe path, an eighth on-off valve  18  and a ninth on-off valve  19 . 
     The sixth pipe path connects seventh port P 7  to the first pipe path. The seventh pipe path connects eighth port P 8  to the first pipe path. The second pipe path, the third pipe path, the fourth pipe path, the fifth pipe path, the sixth pipe path and the seventh pipe path are connected to one another in parallel with respect to the first pipe path. A connection portion between the first pipe path and the seventh pipe path is defined as a fifth connection portion, and a connection portion between the first pipe path and an eighth pipe path is defined as a sixth connection portion. 
     The seventh pipe path is connected to a portion located between the first connection portion and the second connection portion in the first pipe path. The eighth pipe path is connected to a portion located between the third connection portion and the fourth connection portion in the first pipe path. 
     Eighth on-off valve  18  opens and closes the sixth pipe path. Ninth on-off valve  19  opens and closes the seventh pipe path. Fifth on-off valve  15  opens and closes a portion located between the fifth connection portion and the second connection portion in the first pipe path. Seventh on-off valve  17  opens and closes a portion located between the sixth connection portion and the fourth connection portion in the first pipe path. 
     As shown in  FIG. 9 , in the third state, first on-off valve  11 , second on-off valve  12 , third on-off valve  13 , fourth on-off valve  14 , sixth on-off valve  16 , eighth on-off valve  18  and ninth on-off valve  19  are opened, while fifth on-off valve  15  and seventh on-off valve  17  are closed. 
     As shown in  FIG. 10 , in the fourth state, first on-off valve  11 , second on-off valve  12 , third on-off valve  13 , fourth on-off valve  14 , fifth on-off valve  15 , seventh on-off valve  17 , eighth on-off valve  18  and ninth on-off valve  19  are opened, while sixth on-off valve  16  is closed. 
     As shown in  FIG. 11 , in the fifth state, first on-off valve  11 , third on-off valve  13  and seventh on-off valve  17  are opened, while second on-off valve  12 , fourth on-off valve  14 , fifth on-off valve  15 , sixth on-off valve  16 , eighth on-off valve  18  and ninth on-off valve  19  are closed. 
     As shown in  FIG. 12 , in the sixth state, second on-off valve  12 , fourth on-off valve  14 , fifth on-off valve  15  and seventh on-off valve  17  are opened, while first on-off valve  11 , third on-off valve  13  and sixth on-off valve  16  are closed. 
     As shown in  FIG. 13 , in the seventh state, seventh on-off valve  17 , eighth on-off valve  18  and ninth on-off valve  19  are opened, while first on-off valve  11 , second on-off valve  12 , third on-off valve  13 , fourth on-off valve  14 , fifth on-off valve  15  and sixth on-off valve  16  are closed. 
     Second flow path switching unit  10  is configured as a single unit. Second flow path switching unit  20  may be divided, for example, into a first block and a second block, and sixth on-off valve  16  disposed between the first block and the second block. The first block has a portion of the first pipe path, the second pipe path, the third pipe path, the sixth pipe path, first on-off valve  11 , second on-off valve  12 , fifth on-off valve  15  and eighth on-off valve  18 . The second block has another portion of the first pipe path, the fourth pipe path, the fifth pipe path, the seventh pipe path, fourth on-off valve  14 , fifth on-off valve  15 , seventh on-off valve  17  and ninth on-off valve  19 . The first block is disposed, in the first state and the second state, on the gas refrigerant side with respect to first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and third outdoor heat exchanger  5 . The second block is disposed, in the first state and the second state, on the liquid refrigerant side with respect to first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and third outdoor heat exchanger  5 . 
     Each of first on-off valve  11 , second on-off valve  12 , fifth on-off valve  15  and eighth on-off valve  18  included in the first block has a Cv value higher than that of each of third on-off valve  13 , fourth on-off valve  14 , seventh on-off valve  17  and ninth on-off valve  19  included in the second block, for example. 
     Each of the portion of the first pipe path, the second pipe path, the third pipe path and the sixth pipe path included in the first block has an inner diameter greater than that of each of the another portion of the first pipe path, the fourth pipe path, the fifth pipe path and the seventh pipe path included in the second block, for example. 
     Second port P 2 , third port P 3 , fourth port P 4 , fifth port P 5 , seventh port P 7  and eighth port P 8  are disposed on the same plane, for example. First port P 1 , second port P 2 , third port P 3 , fourth port P 4 , fifth port P 5 , sixth port P 6 , seventh port P 7  and eighth port P 8  may be disposed on the same plane. 
     Operation of refrigeration cycle apparatus  101  is now described. 
     Cooling Operation 
     When refrigeration cycle apparatus  101  is in cooling operation, the third state, the fifth state, the sixth state or the seventh state is implemented depending on the cooling load. The third state is selected when the cooling load is relatively high. The third state is implemented during cooling-only operation, for example. The fifth state, the sixth state and the seventh state are implemented during cooling-dominated operation, for example. 
     As shown in  FIG. 9 , in the third state, first outdoor heat exchanger  3  and second outdoor heat exchanger  4  are connected in series in the first circuitry, and third outdoor heat exchanger  5  and second outdoor heat exchanger  4  are connected in series in the first circuitry. 
     The gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . 
     In the third state, first on-off valve  11  and eighth on-off valve  18  are opened, while fifth on-off valve  15  is closed. Thus, a part of the gas single-phase refrigerant that has flowed into the first pipe path passes through the second pipe path and flows through second port P 2  into first distribution unit  3   a , and exchanges heat with outdoor air and condenses in first outdoor heat exchanger  3 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in first outdoor heat exchanger  3  passes through second distribution unit  3   b , and flows through fourth port P 4  into the fourth pipe path. The remaining gas single-phase refrigerant that has flowed into the first pipe path passes through the sixth pipe path and flows through seventh port P 7  into fifth distribution unit  5   a , and exchanges heat with outdoor air and condenses in third outdoor heat exchanger  5 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in third outdoor heat exchanger  5  passes through sixth distribution unit  5   b , and flows through eighth port P 8  into the seventh pipe path. 
     With third on-off valve  13 , ninth on-off valve  19 , sixth on-off valve  16  and second on-off valve  12  opened and fifth on-off valve  15  and seventh on-off valve  17  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fourth pipe path, the first pipe path and the third pipe path and flows through third port P 3  into third distribution unit  4   a , and exchanges heat with outdoor air and condenses in second outdoor heat exchanger  4 . The liquid single-phase refrigerant condensed in second outdoor heat exchanger  4  passes through fourth distribution unit  4   b , and flows through sixth port P 6  into the fifth pipe path. With fourth on-off valve  14  opened and seventh on-off valve  17  closed, the entire liquid single-phase refrigerant that has flowed into the fifth pipe path passes through the fifth pipe path and the first pipe path and flows out through second port P 2 . The liquid single-phase refrigerant that has flowed out through second port P 2  flows into relay unit  50  via the second pipe. 
     As shown in  FIG. 11 , in the fifth state, the refrigerant is not supplied to second outdoor heat exchanger  4  and third outdoor heat exchanger  5 , and each of second outdoor heat exchanger  4  and third outdoor heat exchanger  5  does not serve as a condenser. In the fifth state, only first outdoor heat exchanger  3  serves as a condenser. Specifically, the gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . With first on-off valve  11  opened and fifth on-off valve  15  and eighth on-off valve  18  closed, the entire gas single-phase refrigerant that has flowed into the first pipe path passes through the second pipe path and flows into first distribution unit  3   a , and exchanges heat with outdoor air and condenses in first outdoor heat exchanger  3 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in first outdoor heat exchanger  3  passes through second distribution unit  3   b , and flows through fourth port P 4  into the fourth pipe path. With third on-off valve  13  and seventh on-off valve  17  opened and fourth on-off valve  14 , sixth on-off valve  16  and ninth on-off valve  19  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fourth pipe path and the first pipe path and flows out through second port P 2 . 
     As shown in  FIG. 12 , in the sixth state, the refrigerant is not supplied to first outdoor heat exchanger  3  and third outdoor heat exchanger  5 , and each of first outdoor heat exchanger  3  and third outdoor heat exchanger  5  does not serve as a condenser. In the fifth state, only second outdoor heat exchanger  4  serves as a condenser. Specifically, the gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . With second on-off valve  12  and fifth on-off valve  15  opened and first on-off valve  11 , sixth on-off valve  16  and eighth on-off valve  18  closed, the entire gas single-phase refrigerant that has flowed into the first pipe path passes through the third pipe path and flows into third distribution unit  4   a , and exchanges heat with outdoor air and condenses in second outdoor heat exchanger  4 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in second outdoor heat exchanger  4  passes through fourth distribution unit  4   b , and flows through sixth port P 6  into the fifth pipe path. With fourth on-off valve  14  opened and sixth on-off valve  16 , seventh on-off valve  17  and ninth on-off valve  19  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fifth pipe path and the first pipe path and flows out through second port P 2 . 
     As shown in  FIG. 13 , in the seventh state, the refrigerant is not supplied to first outdoor heat exchanger  3  and second outdoor heat exchanger  4 , and each of first outdoor heat exchanger  3  and second outdoor heat exchanger  4  does not serve as a condenser. In the seventh state, only third outdoor heat exchanger  5  serves as a condenser. Specifically, the gas single-phase refrigerant discharged from compressor  1  flows through first port P 1  into the first pipe path of second flow path switching unit  10 . With eighth on-off valve  18  opened and first on-off valve  11  and fifth on-off valve  15  closed, the entire gas single-phase refrigerant that has flowed into the first pipe path passes through the sixth pipe path and flows into fifth distribution unit  5   a , and exchanges heat with outdoor air and condenses in third outdoor heat exchanger  5 . The liquid single-phase refrigerant or gas-liquid two-phase refrigerant condensed in third outdoor heat exchanger  5  passes through sixth distribution unit  5   b , and flows through eighth port P 8  into the seventh pipe path. With seventh on-off valve  17  and ninth on-off valve  19  opened and third on-off valve  13 , fourth on-off valve  14  and sixth on-off valve  16  closed, the entire liquid single-phase refrigerant or gas-liquid two-phase refrigerant passes through the fifth pipe path and the first pipe path and flows out through second port P 2 . 
     Heating Operation 
     When refrigeration cycle apparatus  101  is in heating operation, the fourth state is implemented. As shown in  FIG. 10 , in the fourth state, first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and third outdoor heat exchanger  5  are connected in parallel in the first circuitry. Specifically, the gas single-phase refrigerant discharged from compressor  1  condenses in at least one of first indoor heat exchanger  6   a  and second indoor heat exchanger  6   b  shown in  FIG. 1 , and turns into liquid single-phase refrigerant. The liquid single-phase refrigerant is decompressed in first decompression unit  7   a  or second decompression unit  7   b , and turns into gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant passes through second pipe C 2  and flows through sixth port P 6  into the first pipe path of second flow path switching unit  10 . 
     In the fourth state, third on-off valve  13 , fourth on-off valve  14 , seventh on-off valve  17  and ninth on-off valve  19  are opened, while sixth on-off valve  16  is closed. Thus, a part of the gas-liquid two-phase refrigerant that has flowed into the first pipe path passes through the third pipe path and flows into second distribution unit  3   b , exchanges heat with outdoor air and evaporates in first outdoor heat exchanger  3 , and turns into gas single-phase refrigerant. Another part of the gas-liquid two-phase refrigerant that has flowed into the first pipe path passes through the fourth pipe path and flows into fourth distribution unit  4   b , exchanges heat with outdoor air and evaporates in second outdoor heat exchanger  4 , and turns into gas single-phase refrigerant. The remaining gas-liquid two-phase refrigerant that has flowed into the first pipe path passes through the seventh pipe path and flows into sixth distribution unit  5   b , exchanges heat with outdoor air and evaporates in third outdoor heat exchanger  5 , and turns into gas single-phase refrigerant. 
     The gas single-phase refrigerant evaporated in first outdoor heat exchanger  3  passes through first distribution unit  3   a , and flows through second port P 2  into the second pipe path. The gas single-phase refrigerant evaporated in second outdoor heat exchanger  4  passes through third distribution unit  4   a , and flows through third port P 3  into the third pipe path. The gas single-phase refrigerant evaporated in third outdoor heat exchanger  5  passes through fifth distribution unit  5   a , and flows through seventh port P 7  into the sixth pipe path. With first on-off valve  11 , second on-off valve  12 , fifth on-off valve  15  and eighth on-off valve  18  opened and sixth on-off valve  16  closed, the entire gas single-phase refrigerant passes through the first pipe path and flows out through first port P 1 . The gas single-phase refrigerant that has flowed out through first port P 1  is sucked through the suction port of compressor  1 . 
     Functions and Effects 
     According to refrigeration cycle apparatus  101 , which has a configuration basically similar to that of refrigeration cycle apparatus  100 , effects similar to those of refrigeration cycle apparatus  100  can be provided. 
     Further, in refrigeration cycle apparatus  101 , in the third state, a part of the gas single-phase refrigerant discharged from compressor  1  condenses in first outdoor heat exchanger  3  and turns into gas-liquid two-phase refrigerant of a reduced degree of dryness, and the remaining gas single-phase refrigerant condenses in third outdoor heat exchanger  5  and turns into gas-liquid two-phase refrigerant of a reduced degree of dryness. Then, the gas-liquid two-phase refrigerants join together in second flow path switching unit  20 , and the joined refrigerant further condenses in second outdoor heat exchanger  4  and turns into liquid single-phase refrigerant. 
     Thus, when refrigeration cycle apparatus  101  and refrigeration cycle apparatus  100  have an equal amount of sealed refrigerant, the refrigerant flowing through each of first outdoor heat exchanger  3  and third outdoor heat exchanger  5  when refrigeration cycle apparatus  101  is in the third state has a flow rate lower than that of the refrigerant flowing through first outdoor heat exchanger  3  when refrigeration cycle apparatus  100  is in the third state. Thus, in this case, the gas single-phase refrigerant or gas-liquid two-phase refrigerant flowing through each of first outdoor heat exchanger  3  and third outdoor heat exchanger  5  of refrigeration cycle apparatus  101  has a flow velocity lower than that of the gas single-phase refrigerant or gas-liquid two-phase refrigerant flowing through first outdoor heat exchanger  3  of refrigeration cycle apparatus  100 . As a result, the gas single-phase refrigerant or gas-liquid two-phase refrigerant flowing through each of first outdoor heat exchanger  3  and third outdoor heat exchanger  5  when refrigeration cycle apparatus  101  is in the third state has a pressure loss smaller than that of the gas single-phase refrigerant or gas-liquid two-phase refrigerant flowing through first outdoor heat exchanger  3  when refrigeration cycle apparatus  100  is in the third state. 
     That is, in refrigeration cycle apparatus  101 , the flow velocity of the liquid single-phase refrigerant flowing through second outdoor heat exchanger  4  in the third state is raised as in refrigeration cycle apparatus  100 , but at the same time, the flow velocity of the gas-liquid two-phase refrigerant flowing through first outdoor heat exchanger  3  and third outdoor heat exchanger  5  in the third state is lowered compared to that of refrigeration cycle apparatus  100 . Accordingly, refrigeration cycle apparatus  101  has condensation heat transfer performance during cooling operation still higher than that of refrigeration cycle apparatus  100  during cooling operation. 
     In addition, the capacity of first outdoor heat exchanger  3  and third outdoor heat exchanger  5  in refrigeration cycle apparatus  101  can be reduced compared to the capacity of first outdoor heat exchanger  3  in refrigeration cycle apparatus  100 . The condensation heat transfer performance of refrigeration cycle apparatus  101  during cooling operation can thereby be more finely controlled depending on the cooling load than the condensation heat transfer performance of refrigeration cycle apparatus  100  during cooling operation. A range of air-conditioning load over which refrigeration cycle apparatus  101  can perform cooling operation is wider than a range of air-conditioning load over which refrigeration cycle apparatus  100  can perform cooling operation. 
     MODIFICATIONS 
     Although refrigeration cycle apparatuses  100  and  101  each include four-way valve  2  as the first flow path switching unit, this is not restrictive. The first flow path switching unit may have any configuration so long as it is able to switch between the first state and the second state, and may be formed of a plurality of on-off valves, for example. 
     Refrigeration cycle apparatuses  100  and  101  may each further have any configuration so long as it has the above-described configuration. For example, refrigeration cycle apparatuses  100  and  101  may each include four or more outdoor heat exchangers. In that case, the third state in which three or more outdoor heat exchangers are connected to one another in series may be implemented by second flow path switching units  10  and  20 . 
     Although refrigeration cycle apparatuses  100  and  101  each include relay unit  50 , this is not restrictive, and they may not include relay unit  50 . Refrigeration cycle apparatuses  100  and  101  may each further include a heat medium circuit through which a heat medium circulates, and the third heat exchanger may be provided as a heat exchanger that exchanges heat between the refrigerant circulating through the refrigerant circuit and the heat medium circulating through the heat medium circuit. 
     In refrigeration cycle apparatuses  100  and  101 , first outdoor heat exchanger  3 , second outdoor heat exchanger  4  and third outdoor heat exchanger  5  may each have any configuration so long as it is able to exchange heat between the refrigerant and a heat medium such as air. First outdoor heat exchanger  3  and second outdoor heat exchanger  4  may be configured as a single heat exchanger, for example. First outdoor heat exchanger  3 , second outdoor heat exchanger  4  and third outdoor heat exchanger  5  may be configured as a single heat exchanger, for example. 
     Although the embodiments of the present invention have been described as above, the embodiments described above can be modified in various manners. In addition, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims.