Air conditioner

Abstract

An air conditioner (100) comprises: an outdoor machine (40); a plurality of branch units (10a, 10b, 10c); a plurality of indoor machines (50a, 50b, 50c); an outgoing main pipe (61) and a return main pipe (62), through which the outdoor machine (40) and the plurality of branch units (10a, 10b, 10c) are connected; a plurality of outgoing branch pipes (51a, 51b, 51c); and a plurality of return branch pipes (52a, 52b, 52c). An intermediate heat exchanger (43) is configured to perform heat exchange between a refrigerant flowing through a first refrigerant pipe path (R1) and a heat medium flowing through a first heat medium circulation path (C1).

Description

air conditioning equipment

[0001] The present disclosure relates to an air conditioning apparatus.

[0002] BACKGROUND ART Conventionally, air conditioners have been known that include an outdoor unit, a plurality of indoor units, and a branch unit, with the outdoor unit and the plurality of indoor units connected via the branch unit.

[0003] International Publication No. 2009 / 133640 discloses an air conditioner in which an outdoor unit (outdoor unit) and a branch unit (relay unit) are connected via first and second extension pipes, and the branch unit and an indoor unit (indoor unit) are connected via third and fourth extension pipes. The air conditioner includes an intermediate heat exchanger disposed in the branch unit.

[0004] In the air conditioner described in the above publication, heat is transferred between the outdoor unit and the branch unit by circulating refrigerant through first and second extension pipes, and heat is transferred between the branch unit and the indoor unit by circulating water through third and fourth extension pipes. Heat is exchanged between the refrigerant and water in an intermediate heat exchanger provided in the branch unit, so that heat is transferred from the indoor unit to the outdoor unit via the intermediate heat exchanger in the branch unit during cooling operation, and from the outdoor unit to the indoor unit via the intermediate heat exchanger in the branch unit during heating operation.

[0005] In the air conditioner described in the above publication, an outdoor unit and a plurality of indoor units are connected via one branch unit (relay section).

[0006] WO 2009 / 133640

[0007] However, the air conditioning device described in the above publication has a problem in that when the first extension pipe and the second extension pipe between the outdoor unit and the branch unit are installed over a long distance (e.g., 110 meters), the amount of refrigerant charged in the air conditioning device increases.

[0008] Furthermore, the air conditioning apparatus described in the above publication has a problem in that it has only one branch unit, which reduces the degree of freedom in piping.

[0009] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide an air conditioning apparatus that can reduce the amount of refrigerant charged and increase the degree of piping flexibility.

[0010] The air conditioning apparatus of the present disclosure includes an outdoor unit, a plurality of branch units, a plurality of indoor units, a main outflow pipe and a main inflow pipe connecting the outdoor unit and the plurality of branch units, and a plurality of branch outflow pipes and a plurality of branch outflow pipes connecting each of the plurality of branch units and each of the plurality of indoor units. The outdoor unit has a first compressor, a first expansion valve, an intermediate heat exchanger, an outdoor heat exchanger, and a first four-way valve arranged therein. The first compressor, the first expansion valve, the intermediate heat exchanger, the outdoor heat exchanger, and the first four-way valve form a first refrigerant piping path connected so that a refrigerant flows. The first four-way valve is configured to switch between flowing the refrigerant in the following order: first compressor, first four-way valve, outdoor heat exchanger, first expansion valve, intermediate heat exchanger, and first four-way valve; or flowing the refrigerant in the following order: first compressor, first four-way valve, outdoor heat exchanger, first expansion valve, intermediate heat exchanger, and first four-way valve. One end of the outward main pipe is connected to one end of the outdoor unit. The other end of the outward main pipe is connected to a plurality of branch units. One end of the return main pipe is connected to the other end of the outdoor unit. The other end of the return main pipe is connected to a plurality of branch units. Each of the plurality of branch units has a first branch header, a first merging header, a plurality of first outward branch pipe on / off valves, a plurality of first return branch pipe on / off valves, a first bypass valve, a first pump, an outward main pipe on / off valve, and a return main pipe on / off valve, which are respectively arranged within the plurality of branch units. The first branch header and the first merging header are connected via a first bypass valve. The plurality of indoor units have a plurality of indoor heat exchangers respectively arranged within the plurality of indoor units. One end of each of the plurality of outward branch pipes is connected to the first branch header via each of the plurality of first outward branch pipe on / off valves. The other end of each of the plurality of outward branch pipes is connected to one end of each of the plurality of indoor heat exchangers. One end of each of the plurality of return branch pipes is connected to the first junction header via each of the plurality of first return branch pipe on-off valves, and the other end of each of the plurality of return branch pipes is connected to the other end of each of the plurality of indoor heat exchangers.The first merging header, the first pump, the outgoing main pipe on / off valve, the outgoing main pipe, the intermediate heat exchanger, the return main pipe, the return main pipe on / off valve, the first branch header, each of the plurality of first outgoing branch pipe on / off valves, each of the plurality of outgoing branch pipes, each of the plurality of indoor heat exchangers, each of the plurality of return branch pipes, and each of the plurality of first return branch pipe on / off valves constitute a first heat medium circulation path connected in this order so that the heat medium flows. The intermediate heat exchanger is configured to perform heat exchange between the refrigerant flowing in the first refrigerant piping path and the heat medium flowing in the first heat medium circulation path.

[0011] According to the air conditioning apparatus of the present disclosure, the amount of refrigerant charged can be reduced and the degree of freedom in piping can be increased.

[0012] FIG. 1 is a refrigerant circuit diagram of an air conditioner according to Embodiment 1. FIG. 2 is a refrigerant circuit diagram for all cooling operation of an air conditioner according to Embodiment 1. FIG. 3 is a refrigerant circuit diagram for all heating operation of an air conditioner according to Embodiment 1. FIG. 4 is a refrigerant circuit diagram for an air conditioner according to Embodiment 2. FIG. 5 is a refrigerant circuit diagram for all cooling operation of an air conditioner according to Embodiment 2. FIG. 6 is a refrigerant circuit diagram for cooling-dominated operation of an air conditioner according to Embodiment 2. FIG. 7 is a refrigerant circuit diagram for all heating operation of an air conditioner according to Embodiment 2. FIG. 8 is a refrigerant circuit diagram for an air conditioner according to Embodiment 3. FIG. 9 is a cross-sectional view of an outward main piping and an inward main piping of an air conditioner according to Embodiment 3. FIG. 10 is a refrigerant circuit diagram for an air conditioner according to Embodiment 4. FIG. 11 is a refrigerant circuit diagram for an air conditioner according to Embodiment 5. FIG. 12 is a refrigerant circuit diagram for an air conditioner according to Embodiment 6.

[0013] Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated in principle.

[0014] Embodiment 1. The configuration of an air conditioning apparatus 100 according to embodiment 1 will be described with reference to FIG. 1. As shown in FIG. 1, the air conditioning apparatus 100 according to embodiment 1 includes a plurality of branch units 10a, 10b, and 10c, an outdoor unit 40, a plurality of indoor units 50a, 50b, and 50c, a plurality of outward branch pipes 51a, 51b, and 51c, a plurality of return branch pipes 52a, 52b, and 52c, an outward main pipe 61 (61a, 61b, and 61c), and a return main pipe 62 (62a, 62b, and 62c). The plurality of outward branch pipes 51a, 51b, and 51c and the plurality of return branch pipes 52a, 52b, and 52c connect each of the plurality of branch units 10a, 10b, and 10c to each of the plurality of indoor units 50a, 50b, and 50c. In this embodiment, the air conditioning apparatus 100 includes nine indoor units. The number of indoor units may be any number as long as it is plural. The outgoing main pipe 61 and the returning main pipe 62 connect the outdoor unit 40 to the plurality of branch units 10a, 10b, and 10c.

[0015] Each of the plurality of branch units 10a, 10b, 10c has a first pump 11, a first branch header 13, a plurality of first outward branch pipe opening / closing valves 14a, 14b, 14c, a plurality of first return branch pipe opening / closing valves 15a, 15b, 15c, a first merging header 16, a first bypass valve 17, a flow control valve 33, an outward main pipe opening / closing valve 34, and a return main pipe opening / closing valve 35, which are respectively arranged within each of the plurality of branch units 10a, 10b, 10c.

[0016] The indoor units 50a, 50b, 50c have indoor heat exchangers 53a, 53b, 53c respectively disposed therein. The indoor units 50a, 50b, 50c have indoor fans 54a, 54b, 54c respectively disposed therein.

[0017] One end of each of the plurality of outward branch pipes 51a, 51b, 51c is connected to the first branch header 13 via each of the plurality of first outward branch pipe on-off valves 14a, 14b, 14c. The other end of each of the plurality of outward branch pipes 51a, 51b, 51c is connected to one end of each of the plurality of indoor heat exchangers 53a, 53b, 53c.

[0018] Each of the first branch pipe opening / closing valves 14 a , 14 b , and 14 c opens and closes a pipe path connecting each of the branch pipes 51 a , 51 b , and 51 c to the first branch header 13 .

[0019] One end of each of the plurality of return branch pipes 52a, 52b, 52c is connected to the first merging header 16 via each of the plurality of first return branch pipe on-off valves 15a, 15b, 15c. The other end of each of the plurality of return branch pipes 52a, 52b, 52c is connected to the other end of each of the plurality of indoor heat exchangers 53a, 53b, 53c.

[0020] Each of the first return branch pipe opening / closing valves 15 a , 15 b , and 15 c opens and closes a pipe path connecting each of the return branch pipes 52 a , 52 b , and 52 c to the first junction header 16 .

[0021] The first branch header 13 and the first merging header 16 are connected via a first bypass valve 17. The first bypass valve 17 opens and closes a bypass path connecting the first branch header 13 and the first merging header 16.

[0022] The first confluence header 16, the first pump 11, the outbound main pipe on / off valve 34, the outbound main pipe 61, the intermediate heat exchanger 43, the return main pipe 62, the return main pipe on / off valve 35, the first branch header 13, each of the plurality of first outbound branch pipe on / off valves 14a, 14b, 14c, each of the plurality of outbound branch pipes 51a, 51b, 51c, each of the plurality of indoor heat exchangers 53a, 53b, 53c, each of the plurality of return branch pipes 52a, 52b, 52c, and each of the plurality of first return branch pipe on / off valves 15a, 15b, 15c constitute a first heat medium circulation path C1 connected in this order so that the heat medium flows through them. The first confluence header 16, the first pump 11, the outbound main pipe on / off valve 34, the outbound main pipes 61a, 61b, 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, 62c, the return main pipe on / off valve 35, the first branch header 13, each of the plurality of first outbound branch pipe on / off valves 14a, 14b, 14c, each of the plurality of outbound branch pipes 51a, 51b, 51c, each of the plurality of indoor heat exchangers 53a, 53b, 53c, each of the plurality of return branch pipes 52a, 52b, 52c, and each of the plurality of first return branch pipe on / off valves 15a, 15b, 15c are connected by pipes to form a first heat medium circulation path C1.

[0023] The outdoor unit 40 has a first compressor 41, a first expansion valve 42, an intermediate heat exchanger 43, an outdoor heat exchanger 44, and a first four-way valve 48 arranged therein. The outdoor unit 40 also has an outdoor blower 45 arranged therein.

[0024] The first compressor 41, the first expansion valve 42, the intermediate heat exchanger 43, the outdoor heat exchanger 44, and the first four-way valve 48 constitute a first refrigerant piping path R1 in which a refrigerant flows. The first compressor 41, the first expansion valve 42, the intermediate heat exchanger 43, the outdoor heat exchanger 44, and the first four-way valve 48 are connected by piping to constitute the first refrigerant piping path R1. The first refrigerant piping path R1 has a refrigeration cycle.

[0025] The first four-way valve 48 is configured to switch between flowing the refrigerant through the first compressor 41, the first four-way valve 48, the outdoor heat exchanger 44, the first expansion valve 42, the intermediate heat exchanger 43, and the first four-way valve 48 in that order, or through the first compressor 41, the first four-way valve 48, the intermediate heat exchanger 43, the first expansion valve 42, the outdoor heat exchanger 44, and the first four-way valve 48 in that order.

[0026] One end of the outgoing main pipe 61 is connected to one end of the outdoor unit 40. The other end of the outgoing main pipe 61 is connected to the plurality of branch units 10a, 10b, and 10c. One end of the return main pipe 62 is connected to the other end of the outdoor unit 40. The other end of the return main pipe 62 is connected to the plurality of branch units 10a, 10b, and 10c.

[0027] The intermediate heat exchanger 43 is configured to perform heat exchange between the refrigerant flowing through the first refrigerant piping path R1 and the heat medium flowing through the first heat medium circulation path C1.

[0028] Each of the branch units 10a, 10b, and 10c has a bypass path B1 that connects between the outward main piping on-off valve 34 and the first pump 11 in the first heat medium circulation path C1 and between the return main piping on-off valve 35 and the first branch header 13 in the first heat medium circulation path C1.

[0029] The bypass path B1 has a flow rate adjustment valve 33 that adjusts the flow rate of the heat medium flowing through the bypass path B1. The flow rate adjustment valve 33 is configured to be able to open and close the bypass path B1.

[0030] The order of the connection points of the branch units 10a, 10b, and 10c in the outward main pipe 61 from the outdoor unit 40 is the same as the order of the connection points of the branch units 10a, 10b, and 10c in the return main pipe 62 from the outdoor unit 40. In this embodiment, each of the branch units 10a, 10b, and 10c is connected to the outward main pipe 61 and the return main pipe 62 by a so-called direct return system.

[0031] The capacity of the first pump 11 of each of the plurality of branching units 10a, 10b, 10c that is closer to the outdoor unit 40 is smaller than the capacity of the first pump 11 of each of the plurality of branching units 10a, 10b, 10c that is farther from the outdoor unit 40. In other words, the capacity of the first pump 11 of the branching unit 10a is smaller than the capacity of the first pumps 11 of the plurality of branching units 10b. Also, the capacity of the first pump 11 of the branching unit 10b is smaller than the capacity of the first pumps 11 of the plurality of branching units 10c.

[0032] <Operation of Air Conditioner> The air conditioner 100 performs full cooling operation or full heating operation depending on the operation modes of the multiple indoor units 50a, 50b, 50c and the outdoor temperature. When all of the multiple operating indoor units 50a, 50b, 50c are in cooling operation mode, the air conditioner 100 performs full cooling operation. When all of the operating indoor units 50a, 50b, 50c are in heating operation mode, the air conditioner 100 performs full heating operation.

[0033] <Cooling only operation> The cooling only operation of the air conditioning apparatus 100 will be described with reference to Fig. 2. As shown in Fig. 2, when the multiple indoor units 50a, 50b, 50c are all operating in the cooling operation mode, the air conditioning apparatus 100 performs cooling only operation. In cooling only operation, the multiple first outward branch pipe on-off valves 14a, 14b, 14c and the multiple first return branch pipe on-off valves 15a, 15b, 15c are opened, and the first bypass valve 17 and the flow rate adjustment valve 33 are closed. This forms a chilled water circuit that passes through the first pump 11, the outbound main pipe on-off valve 34, the outbound main pipes 61a, 61b, 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, 62c, the return main pipe on-off valve 35, the first branch header 13, multiple first outbound branch pipe on-off valves 14a, 14b, 14c, multiple outbound branch pipes 51a, 51b, 51c, multiple indoor heat exchangers 53a, 53b, 53c, multiple return branch pipes 52a, 52b, 52c, multiple first return branch pipe on-off valves 15a, 15b, 15c, the first merging header 16, and again to the first pump 11.

[0034] In the refrigeration cycle, a refrigerant circuit is formed in which the refrigerant passes through the first compressor 41, the first four-way valve 48, the outdoor heat exchanger 44, the first expansion valve 42, the intermediate heat exchanger 43, the first four-way valve 48, and returns to the first compressor 41. At this time, the outdoor heat exchanger 44 functions as a condenser, and the intermediate heat exchanger 43 functions as an evaporator.

[0035] First, the operation of the refrigeration cycle will be described. The single-phase gas refrigerant discharged from the first compressor 41 flows into the outdoor heat exchanger 44 via the first four-way valve 48, where it condenses into a single-phase liquid refrigerant by exchanging heat with outdoor air blown into the outdoor heat exchanger 44 by the outdoor air blown by the outdoor blower 45. The single-phase liquid refrigerant flowing out of the outdoor heat exchanger 44 flows into the first expansion valve 42, where it is decompressed and expanded into a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into the intermediate heat exchanger 43, where it evaporates into a single-phase gas refrigerant by exchanging heat with the heat medium of the chilled water circuit flowing through the intermediate heat exchanger 42. The single-phase gas refrigerant flowing out of the intermediate heat exchanger 43 is drawn back into the first compressor 41 via the first four-way valve 48 and circulates through the refrigerant circuit.

[0036] Next, the operation of the chilled water circuit will be described. The heat medium circulating through the chilled water circuit is water or antifreeze. The heat medium flowing out of the first pump 11 is cooled by exchanging heat with the refrigerant in the intermediate heat exchanger 43 and then flows through the first branch header 13, the first branch pipe on-off valves 14a, 14b, and 14c, and the branch pipes 51a, 51b, and 51c into the indoor heat exchangers 53a, 53b, and 53c in the indoor units 50a, 50b, and 50c. When the indoor units 50a, 50b, and 50c are operating, the indoor fans 54a, 54b, and 54c are also operating, and the heat medium cools the indoor air blown by the indoor fans 54a, 54b, and 54c in the indoor heat exchangers 53a, 53b, and 53c. The heat medium, whose temperature has increased by heat exchange with the indoor air, flows into the first pump 11 via multiple return branch pipes 52a, 52b, and 52c, multiple first return branch pipe opening / closing valves 15a, 15b, and 15c, and the first junction header 16, and circulates through the chilled water circuit.

[0037] <Heating only operation> The heating only operation of the air conditioner 100 will be described with reference to Fig. 3. As shown in Fig. 3, when the multiple indoor units 50a, 50b, 50c are all operating in the heating operation mode, the air conditioner 100 performs heating only operation. In heating only operation, the multiple first outward branch pipe on-off valves 14a, 14b, 14c and the multiple first return branch pipe on-off valves 15a, 15b, 15c are opened, and the first bypass valve 17 and the flow rate adjustment valve 33 are closed. This forms a hot water circuit that passes through the first pump 11, the outbound main pipe on / off valve 34, the outbound main pipes 61a, 61b, 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, 62c, the return main pipe on / off valve 35, the first branch header 13, multiple first outbound branch pipe on / off valves 14a, 14b, 14c, multiple outbound branch pipes 51a, 51b, 51c, multiple indoor heat exchangers 53a, 53b, 53c, multiple return branch pipes 52a, 52b, 52c, multiple first return branch pipe on / off valves 15a, 15b, 15c, the first merging header 16, and again to the first pump 11.

[0038] In the refrigeration cycle, a refrigerant circuit is formed in which the refrigerant passes through the first compressor 41, the first four-way valve 48, the intermediate heat exchanger 43, the first expansion valve 42, the outdoor heat exchanger 44, the first four-way valve 48, and returns to the first compressor 41. In this case, the intermediate heat exchanger 43 functions as a condenser, and the outdoor heat exchanger 44 functions as an evaporator.

[0039] First, the operation of the refrigeration cycle will be described. The single-phase gas refrigerant discharged from the first compressor 41 flows into the intermediate heat exchanger 43 via the first four-way valve 48, where it condenses into a single-phase liquid refrigerant by exchanging heat with the heat medium of the hot water circuit flowing through the intermediate heat exchanger 43. The single-phase liquid refrigerant flowing out of the intermediate heat exchanger 43 flows into the first expansion valve 42, where it is decompressed and expanded into a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into the outdoor heat exchanger 44, where it exchanges heat with outdoor air blown by the outdoor blower 45, where it evaporates into a single-phase gas refrigerant. The single-phase gas refrigerant flowing out of the outdoor heat exchanger 44 is drawn back into the first compressor 41 via the first four-way valve 48 and circulates through the refrigerant circuit.

[0040] Next, the operation of the hot water circuit will be described. The heat medium circulating through the hot water circuit is water or antifreeze. The heat medium flowing out of the first pump 11 is heated by heat exchange with the refrigerant in the intermediate heat exchanger 43 and flows through the first branch header 13, the first branch pipe on-off valves 14a, 14b, and 14c, and the branch pipes 51a, 51b, and 51c into the indoor heat exchangers 53a, 53b, and 53c in the indoor units 50a, 50b, and 50c. When the indoor units 50a, 50b, and 50c are operating, the indoor fans 54a, 54b, and 54c are also operating, and the heat medium heats the indoor air blown by the indoor fans 54a, 54b, and 54c in the indoor heat exchangers 53a, 53b, and 53c. The heat medium, whose temperature has been reduced by heat exchange with the indoor air, flows into the first pump 11 via multiple return branch pipes 52a, 52b, and 52c, multiple first return branch pipe opening / closing valves 15a, 15b, and 15c, and the first junction header 16, and circulates through the hot water circuit.

[0041] <Effects> In the air conditioning apparatus 100 according to Embodiment 1, the intermediate heat exchanger 43 disposed in the outdoor unit 40 is configured to perform heat exchange between the refrigerant flowing through the first refrigerant piping path R1 and the heat medium flowing through the first heat medium circulation path C1. As a result, the refrigerant flows only within the outdoor unit 40. This reduces the refrigerant charge amount compared to when the refrigerant flows through multiple branch units 10a, 10b, and 10c and multiple indoor units 50a, 50b, and 50c. Reducing the refrigerant charge amount reduces refrigerant costs. Furthermore, reducing the refrigerant charge amount reduces the global warming impact of the refrigerant.

[0042] The air conditioning apparatus 100 also includes multiple branch units 10a, 10b, and 10c. This allows each of the multiple branch units 10a, 10b, and 10c to be placed on each floor of a building or in different locations on a single floor, thereby increasing the degree of piping flexibility.

[0043] In the air conditioning apparatus 100 according to the first embodiment, the order of the connection points of the branch units 10a, 10b, and 10c on the outbound main pipe 61 from the outdoor unit 40 is the same as the order of the connection points of the branch units 10a, 10b, and 10c on the inbound main pipe 62 from the outdoor unit 40. That is, each of the branch units 10a, 10b, and 10c is connected to the outbound main pipe 61 and the inbound main pipe 62 by a so-called direct return system. Therefore, compared to a so-called reverse return system, the length of the chilled / hot water pipes can be shortened and pressure loss in the pipe route can be reduced, thereby improving the conveying power. Furthermore, the control response can be improved by reducing the amount of water sealed in the pipes.

[0044] In the air conditioning apparatus 100 according to Embodiment 1, the capacity of the first pump 11 of each of the plurality of branch units 10a, 10b, 10c that is closer to the outdoor unit 40 is smaller than the capacity of the first pump 11 of each of the plurality of branch units 10a, 10b, 10c that is farther from the outdoor unit 40. The branch unit closer to the outdoor unit 40 has relatively smaller power for transporting the heat medium. For this reason, a relatively small heat medium pump can be selected for the branch unit closer to the outdoor unit 40.

[0045] Second Embodiment Unless otherwise specified, the air conditioning apparatus 100 according to the second embodiment has the same configuration, operation, and effects as the air conditioning apparatus 100 according to the first embodiment.

[0046] The configuration of the air conditioning apparatus 100 according to embodiment 2 will be described with reference to Fig. 4. As shown in Fig. 4, in the air conditioning apparatus 100 according to embodiment 2, each of the branch units 10a, 10b, and 10c has a second heat medium circulation path C2 and a second refrigerant piping path R2.

[0047] Each of the plurality of branch units 10a, 10b, 10c has a first heat exchanger 12, a second four-way valve 18, a second pump 21, a second heat exchanger 22, a second branch header 23, a plurality of second outward branch pipe opening / closing valves 24a, 24b, 24c, a plurality of second return branch pipe opening / closing valves 25a, 25b, 25c, a second merging header 26, a second bypass valve 27, a second compressor 31, and a second expansion valve 32, which are respectively arranged within each of the plurality of branch units 10a, 10b, 10c.

[0048] One end of each of the multiple outward branch pipes 51a, 51b, 51c is connected to the first branch header 13 via each of the multiple first outward branch pipe opening / closing valves 14a, 14b, 14c, and is connected to the second branch header 23 via each of the multiple second outward branch pipe opening / closing valves 24a, 24b, 24c.

[0049] Each of the second outward branch pipe on-off valves 24a, 24b, 24c opens and closes a piping path connecting each of the outward branch pipes 51a, 51b, 51c to the second branch header 23. The piping path connecting each of the outward branch pipes 51a, 51b, 51c to the second branch header 23 branches off from the piping path connecting each of the outward branch pipes 51a, 51b, 51c to the first branch header 13.

[0050] One end of each of the multiple return branch pipes 52a, 52b, and 52c is connected to the first merging header 16 via each of the multiple first return branch pipe opening / closing valves 15a, 15b, and 15c, and is connected to the second merging header 26 via each of the multiple second return branch pipe opening / closing valves 25a, 25b, and 25c.

[0051] Each of the second return branch pipe on-off valves 25 a, 25 b, 25 c opens and closes a piping path connecting each of the return branch pipes 52 a, 52 b, 52 c to the second junction header 26. The piping path connecting each of the return branch pipes 52 a, 52 b, 52 c to the second junction header 26 branches off from a piping path connecting each of the return branch pipes 52 a, 52 b, 52 c to the first junction header 16.

[0052] The second branch header 23 and the second merging header 26 are connected via a second bypass valve 27. The second bypass valve 27 opens and closes a bypass path connecting the second branch header 23 and the second merging header 26.

[0053] The second confluence header 26, the second pump 21, the second heat exchanger 22, the second branch header 23, each of the plurality of second outward branch pipe opening / closing valves 24a, 24b, 24c, each of the plurality of outward branch pipes 51a, 51b, 51c, each of the plurality of indoor heat exchangers 53a, 53b, 53c, each of the plurality of return branch pipes 52a, 52b, 52c, and each of the plurality of second return branch pipe opening / closing valves 25a, 25b, 25c constitute a second heat medium circulation path C2 connected in this order so that the heat medium flows. The second confluence header 26, the second pump 21, the second heat exchanger 22, the second branch header 23, each of the plurality of second outward branch pipe opening / closing valves 24a, 24b, 24c, each of the plurality of outward branch pipes 51a, 51b, 51c, each of the plurality of indoor heat exchangers 53a, 53b, 53c, each of the plurality of return branch pipes 52a, 52b, 52c, and each of the plurality of second return branch pipe opening / closing valves 25a, 25b, 25c are connected by pipes to form a second heat medium circulation path C2.

[0054] The second compressor 31, the second expansion valve 32, the second four-way valve 18, the first heat exchanger 12, and the second heat exchanger 22 constitute a second refrigerant piping path R2 in which a refrigerant flows. The second compressor 31, the second expansion valve 32, the second four-way valve 18, the first heat exchanger 12, and the second heat exchanger 22 are connected by piping to constitute the second refrigerant piping path R2. The second refrigerant piping path R2 has a refrigeration cycle.

[0055] The second four-way valve 18 is configured to switch between flowing the refrigerant through the second compressor 31, second four-way valve 18, first heat exchanger 12, second expansion valve 32, second heat exchanger 22, and second four-way valve 18 in that order, or through the second compressor 31, second four-way valve 18, second heat exchanger 22, second expansion valve 32, first heat exchanger 12, and second four-way valve 18 in that order.

[0056] The first heat exchanger 12 is configured to exchange heat between the heat medium flowing through the first heat medium circulation path C1 and the refrigerant flowing through the second refrigerant piping path R2. The second heat exchanger 22 is configured to exchange heat between the heat medium flowing through the second heat medium circulation path C2 and the refrigerant flowing through the second refrigerant piping path R2.

[0057] <Operation of Air Conditioner> The air conditioner 100 performs full cooling operation, cooling-dominated operation, full heating operation, or heating-dominated operation depending on the operation modes of the multiple indoor units 50a, 50b, and 50c and the outdoor temperature. When all of the multiple operating indoor units 50a, 50b, and 50c are in cooling operation mode, the air conditioner 100 performs full cooling operation. When all of the multiple operating indoor units 50a, 50b, and 50c are in heating operation mode, the air conditioner 100 performs full heating operation. There are cases where the multiple operating indoor units 50a, 50b, and 50c are operating in a mixture of cooling and heating operation modes. When the total air conditioning load of the indoor units in cooling operation mode is greater than the total air conditioning load of the indoor units in heating operation mode, the air conditioner 100 performs cooling-dominated operation. When the total air conditioning load of the indoor units in heating operation mode is greater than the total air conditioning load of the indoor units in cooling operation mode, the air conditioner 100 performs heating-dominated operation.

[0058] <Cooling only operation> The cooling only operation of the air conditioner 100 will be described with reference to Fig. 5. As shown in Fig. 5, when the multiple indoor units 50a, 50b, 50c are all operating in the cooling operation mode, the air conditioner 100 performs cooling only operation. In cooling only operation, the multiple first outward branch pipe on-off valves 14a, 14b, 14c, the multiple first return branch pipe on-off valves 15a, 15b, 15c, and the second bypass valve 27 are opened, and the multiple second outward branch pipe on-off valves 24a, 24b, 24c, the multiple second return branch pipe on-off valves 25a, 25b, 25c, the first bypass valve 17, and the flow rate adjustment valve 33 are closed. As a result, a chilled water circuit is formed that passes through the first pump 11, the first heat exchanger 12, the outbound main pipe on / off valve 34, the outbound main pipes 61a, 61b, and 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, and 62c, the return main pipe on / off valve 35, the first branch header 13, the plurality of first outbound branch pipe on / off valves 14a, 14b, and 14c, the plurality of outbound branch pipes 51a, 51b, and 51c, the plurality of indoor heat exchangers 53a, 53b, and 53c, the plurality of return branch pipes 52a, 52b, and 52c, the plurality of first return branch pipe on / off valves 15a, 15b, and 15c, and the first junction header 16, and again to the first pump 11. Note that in full cooling operation, all indoor units are operating in cooling mode, so there is no demand for hot water, and therefore the second pump 21 is not operated, and no hot water circuit is formed.

[0059] In the refrigeration cycle of the outdoor unit 40, a refrigerant circuit is formed in which the refrigerant passes through the first compressor 41, the first four-way valve 48, the outdoor heat exchanger 44, the first expansion valve 42, the intermediate heat exchanger 43, the first four-way valve 48, and returns to the first compressor 41. At this time, the outdoor heat exchanger 44 functions as a condenser, and the intermediate heat exchanger 43 functions as an evaporator.

[0060] Furthermore, in full cooling operation, all indoor units are operating in cooling mode, so there is no need to generate hot water. Therefore, in each of the multiple branch units 10a, 10b, and 10c, the compressor 31 is not operated, and a refrigeration cycle is not formed.

[0061] First, the operation of the refrigeration cycle of the outdoor unit 40 will be described. The single-phase gas refrigerant discharged from the first compressor 41 flows into the outdoor heat exchanger 44 via the first four-way valve 48, where it condenses into single-phase liquid refrigerant by exchanging heat with outdoor air blown into the outdoor heat exchanger 44 by the outdoor air blown by the outdoor blower 45. The single-phase liquid refrigerant flowing out of the outdoor heat exchanger 44 flows into the first expansion valve 42, where it is decompressed and expanded into two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into the intermediate heat exchanger 43, where it evaporates into single-phase gas refrigerant by exchanging heat with the heat medium of the chilled water circuit flowing through the intermediate heat exchanger 42. The single-phase gas refrigerant flowing out of the intermediate heat exchanger 43 is drawn back into the first compressor 41 via the first four-way valve 48 and circulates through the refrigerant circuit.

[0062] Next, the operation of the chilled water circuit will be described. The heat medium circulating through the chilled water circuit is water or antifreeze. The heat medium flowing out of the first pump 11 passes through the first heat exchanger 12, the outbound main pipe on-off valve 34, and the outbound main pipes 61a, 61b, and 61c, and is cooled by heat exchange with the refrigerant in the intermediate heat exchanger 43. The heat medium then flows into the return main pipes 62a, 62b, and 62c, the return main pipe on-off valve 35, the first branch header 13, the first outbound branch pipe on-off valves 14a, 14b, and 14c, the outbound branch pipes 51a, 51b, and 51c, and the indoor heat exchangers 53a, 53b, and 53c. While the indoor units 50a, 50b, 50c are operating, the indoor fans 54a, 54b, 54c are also operating, and the heat medium cools the indoor air blown by the indoor fans 54a, 54b, 54c in the indoor heat exchangers 53a, 53b, 53c. The heat medium, whose temperature has increased by heat exchange with the indoor air, flows into the first pump 11 via the return branch pipes 52a, 52b, 52c, the first return branch pipe on-off valves 15a, 15b, 15c, and the first junction header 16, and circulates through the chilled water circuit.

[0063] <Cooling-dominated operation> Cooling-dominated operation of the air conditioning apparatus 100 will be described with reference to Fig. 6. As shown in Fig. 6, when the multiple indoor units 50a, 50b are operating in the cooling operation mode and the indoor unit 50c is operating in the heating operation mode, the air conditioning apparatus 100 performs cooling-dominated operation. In cooling-dominated operation, the multiple first outward branch pipe on / off valves 14a, 14b, the multiple first return branch pipe on / off valves 15a, 15b, the second outward branch pipe on / off valve 24c, the second return branch pipe on / off valve 25c, and the second bypass valve 27 are opened, and the first outward branch pipe on / off valve 14c, the first return branch pipe on / off valve 15c, the first bypass valve 17, the multiple second outward branch pipe on / off valves 24a, 24b, the multiple second return branch pipe on / off valves 25a, 25b, and the flow rate adjustment valve 33 are closed. This forms a chilled water circuit that passes through the first pump 11, the first heat exchanger 12, the forward main pipe on / off valve 34, the forward main pipes 61a, 61b, 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, 62c, the return main pipe on / off valve 35, the first branch header 13, a plurality of first forward branch pipe on / off valves 14a, 14b, a plurality of forward branch pipes 51a, 51b, a plurality of indoor heat exchangers 53a, 53b, a plurality of return branch pipes 52a, 52b, a plurality of first return branch pipe on / off valves 15a, 15b, the first merging header 16, and leads back to the first pump 11. In addition, a hot water circuit is formed that passes through the second pump 21, the second heat exchanger 22, the second branch header 23, the second outward branch pipe opening / closing valve 24c, the outward branch pipe 51c, the indoor heat exchanger 53c, the return branch pipe 52c, the second return branch pipe opening / closing valve 25c, or from the second branch header 23 via the second bypass valve 27, passes through the second confluence header 26, and returns to the second pump 21.

[0064] In the refrigeration cycle of each of the branch units 10a, 10b, and 10c, a refrigerant circuit is formed in which the refrigerant passes through the second compressor 31, the second four-way valve 18, the second heat exchanger 22, the second expansion valve 32, the first heat exchanger 12, the second four-way valve 18, and returns to the second compressor 31. At this time, the second heat exchanger 22 functions as a condenser, and the first heat exchanger 12 functions as an evaporator.

[0065] The operation of the refrigeration cycle of the outdoor unit 40 is the same as during full cooling operation. The operation of the refrigeration cycles of the multiple branch units 10a, 10b, and 10c will now be described. The single-phase gas refrigerant discharged from the second compressor 31 flows into the second heat exchanger 22 via the second four-way valve 18, where it condenses into a single-phase liquid refrigerant by exchanging heat with the heat medium of the hot water circuit flowing through the second heat exchanger 22. The single-phase liquid refrigerant flowing out of the second heat exchanger 22 flows into the second expansion valve 32, where it is decompressed and expanded into a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into the first heat exchanger 12, where it evaporates into a single-phase gas refrigerant by exchanging heat with the heat medium of the chilled water circuit flowing through the first heat exchanger 12. The single-phase gas refrigerant flowing out of the first heat exchanger 12 is drawn back into the second compressor 31 via the second four-way valve 18 and circulates through the refrigerant circuit.

[0066] The operation of the chilled water circuit is also the same as in the cooling-only operation. Next, the operation of the hot water circuit will be described. The heat medium flowing out of the second pump 21 flows into the second heat exchanger 22 and is heated by exchanging heat with the refrigerant. The heat medium, whose temperature has increased by exchanging heat with the refrigerant, flows into the indoor heat exchanger 53c in the indoor unit 50c via the second branch header 23, the second outward branch pipe on-off valve 24c, and the outward branch pipe 51c. When the indoor unit 50c is operating, the indoor blower 54c is operating, and the heat medium heats the indoor air blown by the indoor blower 54c in the indoor heat exchanger 53c. The heat medium, whose temperature has decreased by exchanging heat with the indoor air, reaches the second merging header 26 via the return branch pipe 52c and the second return branch pipe on-off valve 25c. The remaining heat medium that is not sent to the indoor heat exchanger 53c reaches the second merging header 26 via the second bypass valve 27, merges with the heat medium returning from the indoor heat exchanger 53c, flows into the first pump 11, and circulates through the hot water circuit.

[0067] <Heating only operation> The heating only operation of the air conditioner 100 will be described with reference to Fig. 7. As shown in Fig. 7, when the multiple indoor units 50a, 50b, 50c are all operating in the heating operation mode, the air conditioner 100 performs heating only operation. In heating only operation, the multiple first outward branch pipe on-off valves 14a, 14b, 14c, the multiple first return branch pipe on-off valves 15a, 15b, 15c, and the second bypass valve 27 are opened, and the multiple second outward branch pipe on-off valves 24a, 24b, 24c, the multiple second return branch pipe on-off valves 25a, 25b, 25c, the first bypass valve 17, and the flow rate adjustment valve 33 are closed. As a result, a hot water circuit is formed that passes through the first pump 11, the first heat exchanger 12, the outbound main pipe on / off valve 34, the outbound main pipes 61a, 61b, and 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, and 62c, the return main pipe on / off valve 35, the first branch header 13, the plurality of first outbound branch pipe on / off valves 14a, 14b, and 14c, the plurality of outbound branch pipes 51a, 51b, and 51c, the plurality of indoor heat exchangers 53a, 53b, and 53c, the plurality of return branch pipes 52a, 52b, and 52c, the plurality of first return branch pipe on / off valves 15a, 15b, and 15c, and the first junction header 16, and again to the first pump 11. Note that in full heating operation, all indoor units are performing heating operation and there is no demand for chilled water, so the second pump 21 is not operated and no chilled water circuit is formed.

[0068] In the refrigeration cycle of the outdoor unit 40, a refrigerant circuit is formed in which the refrigerant passes through the first compressor 41, the first four-way valve 48, the intermediate heat exchanger 43, the first expansion valve 42, the outdoor heat exchanger 44, the first four-way valve 48, and returns to the first compressor 41. At this time, the intermediate heat exchanger 43 functions as a condenser, and the outdoor heat exchanger 44 functions as an evaporator.

[0069] Furthermore, in full heating operation, all indoor units are in heating operation and there is no need to produce chilled water, so in each of the multiple branch units 10a, 10b, and 10c, the compressor 31 is not operated and a refrigeration cycle is not formed.

[0070] First, the operation of the refrigeration cycle of the outdoor unit 40 will be described. The single-phase gas refrigerant discharged from the first compressor 41 flows into the intermediate heat exchanger 43 via the first four-way valve 48, where it condenses and becomes single-phase liquid refrigerant by exchanging heat with the heat medium of the hot water circuit flowing through the intermediate heat exchanger 43. The single-phase liquid refrigerant flowing out of the intermediate heat exchanger 43 flows into the first expansion valve 42, where it is decompressed and expanded into two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into the outdoor heat exchanger 44, where it exchanges heat with outdoor air blown by the outdoor blower 45, where it evaporates and becomes single-phase gas refrigerant. The single-phase gas refrigerant flowing out of the outdoor heat exchanger 44 is drawn back into the first compressor 41 via the first four-way valve 48 and circulates through the refrigerant circuit.

[0071] Next, the operation of the hot water circuit will be described. The heat medium circulating through the hot water circuit is water or antifreeze. The heat medium flowing out of the first pump 11 passes through the first heat exchanger 12, the outward main pipe on-off valve 34, and the outward main pipes 61a, 61b, and 61c, and is heated by heat exchange with the refrigerant in the intermediate heat exchanger 43. The heat medium then flows through the return main pipes 62a, 62b, and 62c, the return main pipe on-off valve 35, the first branch header 13, the first outward branch pipe on-off valves 14a, 14b, and 14c, and the outward branch pipes 51a, 51b, and 51c, and into the indoor heat exchangers 53a, 53b, and 53c in the indoor units 50a, 50b, and 50c. While the indoor units 50a, 50b, 50c are operating, the indoor fans 54a, 54b, 54c are also operating, and the heat medium heats the indoor air blown by the indoor fans 54a, 54b, 54c in the indoor heat exchangers 53a, 53b, 53c. The heat medium, whose temperature has been reduced by heat exchange with the indoor air, flows into the first pump 11 via the return branch pipes 52a, 52b, 52c, the first return branch pipe on-off valves 15a, 15b, 15c, and the first junction header 16, and circulates through the hot water circuit.

[0072] <Heating-dominated operation> Heating-dominated operation of the air conditioning apparatus 100 will be described with reference to Fig. 8. As shown in Fig. 8, when the multiple indoor units 50a, 50b are operating in the heating operation mode and the indoor unit 50c is operating in the cooling operation mode, the air conditioning apparatus 100 performs heating-dominated operation. In heating-dominated operation, the multiple first outward branch pipe on / off valves 14a, 14b, the multiple first return branch pipe on / off valves 15a, 15b, the second outward branch pipe on / off valve 24c, the second return branch pipe on / off valve 25c, and the second bypass valve 27 are opened, and the first outward branch pipe on / off valve 14c, the first return branch pipe on / off valve 15c, the first bypass valve 17, the multiple second outward branch pipe on / off valves 24a, 24b, the multiple second return branch pipe on / off valves 25a, 25b, and the flow rate adjustment valve 33 are closed. This forms a hot water circuit that passes through the first pump 11, the first heat exchanger 12, the forward main pipe on / off valve 34, the forward main pipes 61a, 61b, 61c, the intermediate heat exchanger 43, the return main pipes 62a, 62b, 62c, the return main pipe on / off valve 35, the first branch header 13, multiple first forward branch pipe on / off valves 14a, 14b, multiple forward branch pipes 51a, 51b, multiple indoor heat exchangers 53a, 53b, multiple return branch pipes 52a, 52b, multiple first return branch pipe on / off valves 15a, 15b, the first merging header 16, and then leads back to the first pump 11. In addition, a chilled water circuit is formed that passes through the second pump 21, the second heat exchanger 22, the second branch header 23, the second outward branch pipe opening / closing valve 24c, the outward branch pipe 51c, the indoor heat exchanger 53c, the return branch pipe 52c, the second return branch pipe opening / closing valve 25c, or from the second branch header 23 via the second bypass valve 27, passes through the second confluence header 26, and returns to the second pump 21.

[0073] In each of the refrigeration cycles of the branch units 10a, 10b, and 10c, a refrigerant circuit is formed in which the refrigerant passes through the second compressor 31, the second four-way valve 18, the first heat exchanger 12, the second expansion valve 32, the second heat exchanger 22, the second four-way valve 18, and returns to the second compressor 31. At this time, the first heat exchanger 12 functions as a condenser, and the second heat exchanger 22 functions as an evaporator.

[0074] The operation of the refrigeration cycle of the outdoor unit 40 is the same as during heating only operation. The operation of the refrigeration cycles of the multiple branch units 10a, 10b, and 10c will now be described. The single-phase gas refrigerant discharged from the second compressor 31 flows into the first heat exchanger 12 via the second four-way valve 18, where it condenses into a single-phase liquid refrigerant by exchanging heat with the heat medium of the hot water circuit flowing through the first heat exchanger 12. The single-phase liquid refrigerant flowing out of the first heat exchanger 12 flows into the second expansion valve 32, where it is decompressed and expanded into a two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into the second heat exchanger 22, where it evaporates into a single-phase gas refrigerant by exchanging heat with the heat medium of the chilled water circuit flowing through the second heat exchanger 22. The single-phase gas refrigerant flowing out of the second heat exchanger 22 is drawn back into the second compressor 31 via the second four-way valve 18 and circulates through the refrigerant circuit.

[0075] The operation of the hot water circuit is also the same as in the heating only operation. Next, the operation of the chilled water circuit will be described. The heat medium flowing out of the second pump 21 flows into the second heat exchanger 22 and is cooled by exchanging heat with the refrigerant. The heat medium, whose temperature has been reduced by heat exchange with the refrigerant, flows into the indoor heat exchanger 53c in the indoor unit 50c via the second branch header 23, the second outward branch pipe on-off valve 24c, and the outward branch pipe 51c. When the indoor unit 50c is operating, the indoor blower 54c is operating, and the heat medium cools the indoor air blown by the indoor blower 54c in the indoor heat exchanger 53c. The heat medium, whose temperature has been increased by heat exchange with the indoor air, reaches the second merging header 26 via the return branch pipe 52c and the second return branch pipe on-off valve 25c. The remaining heat medium that is not sent to the indoor heat exchanger 53c reaches the second merging header 26 via the second bypass valve 27, merges with the heat medium returning from the indoor heat exchanger 53c, flows into the first pump 11, and circulates through the chilled water circuit.

[0076] <Operation and Effect> In the air conditioning apparatus 100 according to the second embodiment, the second compressor 31, the second expansion valve 32, the second four-way valve 18, the first heat exchanger 12, and the second heat exchanger 22, which are respectively arranged in each of the plurality of branch units 10 a, 10 b, and 10 c, constitute a second refrigerant piping path R2 connected so that a refrigerant flows through them. Therefore, the plurality of indoor units 50 a, 50 b, and 50 c connected to each of the plurality of branch units 10 a, 10 b, and 10 c can be independently operated in either cooling or heating mode.

[0077] Furthermore, by using the hot and cold energy generated by the refrigeration cycles provided in the multiple branch units 10a, 10b, and 10c, it is possible to switch between all-cooling operation, cooling-dominated operation, all-heating operation, and heating-dominated operation according to the settings of the cooling operation mode and heating operation mode of each of the multiple indoor units 50a, 50b, and 50c. For example, in air conditioning equipment for large buildings, while indoor units located in general living rooms are operated in heating mode, indoor units located in rooms with high heat output, such as computer rooms or kitchens, may be operated in cooling mode. The air conditioning apparatus 100 according to embodiment 2 is suitable for such air conditioning equipment.

[0078] Third Embodiment Unless otherwise specified, the air conditioning apparatus 100 according to the third embodiment has the same configuration, operation, and effects as the air conditioning apparatus 100 according to the second embodiment.

[0079] The configuration of an air conditioning apparatus 100 according to embodiment 3 will be described with reference to Fig. 9. As shown in Fig. 9, in the air conditioning apparatus 100 according to embodiment 3, an outward main pipe 61a and a return main pipe 62a are connected to branch unit 10a. An outward main pipe 61b and a return main pipe 62b are connected to branch unit 10b. An outward main pipe 61c and a return main pipe 62c are connected to branch unit 10c.

[0080] 10 , the inner diameters of the outgoing main pipe 61 and the return main pipe 62 connected to the branch units 10a, 10b, 10c that are closer to the outdoor unit 40 are equal to or larger than the inner diameters of the outgoing main pipe 61 and the return main pipe 62 connected to the branch units 10a, 10b, 10c that are farther from the outdoor unit 40. The inner diameters of the outgoing main pipe 61a and the return main pipe 62a are equal to or larger than the inner diameters of the outgoing main pipe 61b and the return main pipe 62b. The inner diameters of the outgoing main pipe 61b and the return main pipe 62b are equal to or larger than the inner diameters of the outgoing main pipe 61c and the return main pipe 62c.

[0081] Next, the effects of the air conditioning apparatus 100 according to Embodiment 3 will be described. In the air conditioning apparatus 100 according to Embodiment 3, the inner diameters of the outbound main pipe 61 and the return main pipe 62 connected to the branch units 10a, 10b, 10c that are closer to the outdoor unit 40 are larger than or equal to the inner diameters of the outbound main pipe 61 and the return main pipe 62 connected to the branch units 10a, 10b, 10c that are farther from the outdoor unit 40. During operation of the air conditioning apparatus 100, the flow rate of the heat medium in the outbound main pipe 61a and the return main pipe 62a is greater than or equal to the flow rate of the heat medium in the outbound main pipe 61b and the return main pipe 62b, and the flow rate of the heat medium in the outbound main pipe 61b and the return main pipe 62b is greater than or equal to the flow rate of the heat medium in the outbound main pipe 61c and the return main pipe 62c. Therefore, the inner diameters of the outward main pipe 61a and the return main pipe 62a are larger than or equal to the inner diameters of the outward main pipe 61b and the return main pipe 62b, and the inner diameters of the outward main pipe 61b and the return main pipe 62b are larger than or equal to the inner diameters of the outward main pipe 61c and the return main pipe 62c, thereby suppressing the flow resistance inside the outward main pipe 61 and the return main pipe 62.

[0082] Furthermore, by not overdesigning the internal volumes of the outward branch pipes 51a, 51b, 51c and the return branch pipes 52a, 52b, 52c, the total amount of heat medium held in the air conditioning apparatus 100 can be reduced. This reduces the time required to demonstrate air conditioning capacity at the start of cooling / heating operation, and also reduces the wasted time required to transport the heat medium. This improves air conditioning control response.

[0083] Embodiment 4 Unless otherwise specified, the air conditioning apparatus 100 according to embodiment 4 has the same configuration, operation, and effects as the air conditioning apparatus 100 according to embodiment 2.

[0084] The configuration of an air conditioning apparatus 100 according to embodiment 4 will be described with reference to Fig. 11 . As shown in Fig. 11 , in the air conditioning apparatus 100 according to embodiment 4, the outbound main pipe 61 and the inbound main pipe 62 are not branched outside the multiple branch units 10a, 10b, and 10c, but are directly connected to the multiple branch units 10a, 10b, and 10c. The outbound main pipe 61 and the inbound main pipe 62 connect the outdoor unit 40 to one of the multiple branch units, and connect one of the multiple branch units to the rest in series. The outbound main pipe 61a and the inbound main pipe 62a connect the outdoor unit 40 to the branch unit 10a. The outbound main pipe 61b and the inbound main pipe 62b connect the branch unit 10a to the branch unit 10b. The outbound main pipe 61c and the inbound main pipe 62c connect the branch unit 10b to the branch unit 10c.

[0085] Next, we will explain the effects of the air conditioning apparatus 100 according to Embodiment 4. In the air conditioning apparatus 100 according to Embodiment 4, the outgoing main pipe 61 and the returning main pipe 62 connect the outdoor unit 40 and one of the plurality of branch units, and connect one of the plurality of branch units to the rest in series.

[0086] When the outbound main pipes 61a, 61b, 61b and the return main pipes 62a, 62b, 62c are connected to the branch units 10a, 10b, 10c via T-type joints, when adding one branch unit to the air conditioning apparatus 100, a total of eight connection points are required: six additional connection points for two T-type joints, and two connection points for the inlet and outlet pipes of the branch unit.

[0087] By incorporating the branching of the T-shaped joint portion within the branching unit, when adding a branching unit to the air conditioning device 100, only four connection works are required: two inlet / outlet pipes of the outbound main pipes 61b and 61c of the branching units 10b and 10c, and two inlet / outlet pipes of the return main pipes 62b and 62c.

[0088] Pipe connection work requires screwing or welding, which not only takes time and effort, but also poses the risk of pipe rupture or heat medium leakage from the connection points in the future, so it is preferable to have as few connections as possible during construction.By extending and connecting the outbound main pipes 61b, 61c and the inbound main pipes 62b, 62c via the connected branch units 10a, 10b in this way, construction costs, construction time, and construction defects can be reduced.

[0089] Fifth Embodiment Unless otherwise specified, the air conditioning apparatus 100 according to the fifth embodiment has the same configuration, operation, and effects as the air conditioning apparatus 100 according to the second embodiment.

[0090] The configuration of an air conditioning apparatus 100 according to embodiment 5 will be described with reference to Fig. 12. As shown in Fig. 12, in the air conditioning apparatus 100 according to embodiment 5, the outdoor unit 40 is installed above all of the branch units 10a, 10b, and 10c. The outdoor unit 40 is disposed above the multiple branch units 10a, 10b, and 10c.

[0091] Next, the effects of the air conditioning apparatus 100 according to the fifth embodiment will be described. In the air conditioning apparatus 100 according to the fifth embodiment, the outdoor unit 40 is located above the branch units 10a, 10b, and 10c. When the air conditioning apparatus 100 is installed in a high-rise building in an urban area, there is generally no ground space for the outdoor unit 40, and the outdoor unit 40 is generally installed on the building roof or in a machine room on each floor. During operation of the heat medium circulation pump, the heat medium at the pump discharge port is pressurized while the heat medium at the pump suction port is depressurized. Therefore, particularly when the pump is installed at an upper position in the heat medium circuit, cavitation (decompression boiling of the heat medium) may occur in the heat medium at the pump suction port. Cavitation can result in insufficient heat medium circulation, noise, or pump wear and tear. Since the outdoor unit 40 is disposed above the branch units 10a, 10b, and 10c, the heat medium circulation pump is disposed relatively lower in the heat medium circuit, which makes it possible to suppress pressure drop and cavitation at the pump suction section even during pump operation, thereby preventing malfunctions of the air conditioning apparatus 100 or pump failures.

[0092] Sixth Embodiment Unless otherwise specified, the air conditioning apparatus 100 according to the sixth embodiment has the same configuration, operation, and effects as the air conditioning apparatus 100 according to the second embodiment.

[0093] The defrosting operation of the air conditioning apparatus 100 according to embodiment 6 will be described with reference to Fig. 13. As shown in Fig. 13, in the air conditioning apparatus 100 according to embodiment 6, when frost forms on the outdoor heat exchanger 44 during heating only operation or heating-dominant operation and defrosting is required, the defrosting operation is performed.

[0094] In defrosting operation for removing frost adhering to the outdoor heat exchanger 44 of the outdoor unit 40, the air conditioner 100 operates as follows. In the first refrigerant piping path R1, a refrigerant circuit is formed in which the refrigerant passes through the first compressor 41, the first four-way valve 48, the outdoor heat exchanger 44, the first expansion valve 42, the intermediate heat exchanger 43, and the first four-way valve 48, before returning to the first compressor 41. In the second refrigerant piping path R2, a refrigerant circuit is formed in which the refrigerant passes through the second compressor 31, the second four-way valve 18, the first heat exchanger 12, the second expansion valve 32, the second heat exchanger 22, and the second four-way valve 18, before returning to the second compressor 31.

[0095] When a certain amount of frost is detected on the outdoor heat exchanger 44, or when the outdoor heat exchanger 44 has continued to operate as an evaporator at a temperature below a predetermined outdoor temperature (e.g., below 7°C) for a predetermined time or more (e.g., four hours or more), the air conditioning apparatus 100 starts a defrosting operation. In each of the branch units 10a, 10b, and 10c, in the branch unit 10c that is farthest from the outdoor unit 40, the first pump 11 is operated with the outbound main pipe on-off valve 34 and the return main pipe on-off valve 35 open and the flow rate adjustment valve 33 closed. In the branch units 10a and 10b other than the branch unit 10c that is farthest from the outdoor unit 40, the first pump 11 is operated with the outbound main pipe on-off valve 34 and the return main pipe on-off valve 35 closed and the flow rate adjustment valve 33 open.

[0096] Next, the effects of the air conditioning apparatus 100 according to embodiment 6 will be described. In the air conditioning apparatus 100 according to embodiment 6, in branch unit 10c, which is the farthest from the outdoor unit 40 among the plurality of branch units 10a, 10b, and 10c, the first pump 11 is operated with the outgoing main pipe on / off valve 34 and the return main pipe on / off valve 35 open and the flow rate adjustment valve 33 closed. In branch units 10a and 10b other than branch unit 10c, which is the farthest from the outdoor unit 40, the first pump 11 is operated with the outgoing main pipe on / off valve 34 and the return main pipe on / off valve 35 closed and the flow rate adjustment valve 33 open.

[0097] During defrosting operation of the outdoor unit 40, the heat medium circulating through the outward main pipes 61a, 61b, and 61c and the return main pipes 62a, 62b, and 62c absorbs heat as a defrosting heat source for the outdoor heat exchanger 44 via the intermediate heat exchanger 43. This causes the temperature of the heat medium to drop. To maximize the heat medium volume in the outward main pipes 61a, 61b, and 61c and the return main pipes 62a, 62b, and 62c during defrosting operation of the outdoor unit 40, a heat medium circulation circuit is formed using the branch unit 10c farthest from the outdoor unit 40, and the heat medium circulation circuits in the branch units having other heating-operating indoor units are separated from the outward main pipe 61 and the return main pipe 62. This minimizes the temperature drop of the heat medium circulating through the indoor units 50a, 50b, and 50c even during defrosting operation of the outdoor unit 40. This minimizes the reduction in the heating capacity of the heating indoor units.

[0098] The above-described embodiments can be combined as appropriate. The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0099] 10a, 10b, 10c Branch unit, 11 First pump, 12 First heat exchanger, 13 First branch header, 14a, 14b, 14c First outward branch pipe on / off valve, 15a, 15b, 15c First return branch pipe on / off valve, 16 First merging header, 17 First bypass valve, 18 Second four-way valve, 21 Second pump, 22 Second heat exchanger, 23 Second branch header, 24a, 24b, 24c Second outward branch pipe on / off valve, 25a, 25b, 25c Second return branch pipe on / off valve, 26 Second merging header, 27 Second bypass valve, 31 Second compressor, 32 Second expansion valve, 33 Flow control valve, 34 Outward main pipe on / off valve, 35 Return main pipe on / off valve, 40 Outdoor unit, 41 First compressor, 42 First expansion valve, 43 Intermediate heat exchanger, 44 Outdoor heat exchanger, 45 Outdoor blower, 48 First four-way valve, 50a, 50b, 50c Indoor units, 51a, 51b, 51c Outward branch piping, 52a, 52b, 52c Return branch piping, 53a, 53b, 53c Indoor heat exchanger, 54a, 54b, 54c Indoor blower, 61 Outward main piping, 62 Return main piping, 100 Air conditioning apparatus, B1 Bypass path, C1 First heat medium circulation path, C2 Second heat medium circulation path, R1 First refrigerant piping path, R2 Second refrigerant piping path.

Claims

1. An air conditioner comprising: an outdoor unit; a plurality of branch units; a plurality of indoor units; a main outward piping and a main return piping connecting the outdoor unit and the plurality of branch units; a plurality of outward branch piping and a plurality of return branch piping connecting each of the plurality of branch units and each of the plurality of indoor units; the outdoor unit has a first compressor, a first expansion valve, an intermediate heat exchanger, an outdoor heat exchanger and a first four-way valve arranged therein; the first compressor, the first expansion valve, the intermediate heat exchanger, the outdoor heat exchanger and the first four-way valve constitute a first refrigerant piping path connected so that a refrigerant flows through it; the first four-way valve is configured to switch between flowing the refrigerant through the first compressor, the first four-way valve, the outdoor heat exchanger, the first expansion valve, the intermediate heat exchanger, and the first four-way valve in this order, or flowing the refrigerant through the first compressor, the first four-way valve, the intermediate heat exchanger, the first expansion valve, the outdoor heat exchanger, and the first four-way valve in this order, one end of the outward main pipe is connected to one end of the outdoor unit, the other end of the outward main pipe is connected to the multiple branch units, one end of the return main pipe is connected to the other end of the outdoor unit, and the other end of the return main pipe is connected to the multiple branch units, each of the multiple branch units has a first branch header, a first junction header, a multiple of first outward branch pipe on-off valves, a multiple of first return branch pipe on-off valves, a first bypass valve, a first pump, an outward main pipe on-off valve, and a return main pipe on-off valve, which are respectively arranged in each of the multiple branch units, the first branch header and the first junction header are connected via the first bypass valve, the indoor units have a plurality of indoor heat exchangers respectively arranged within each of the indoor units, one end of each of the plurality of outward branch pipes is connected to the first branch header via each of the plurality of first outward branch pipe opening / closing valves, the other end of each of the plurality of outward branch pipes is connected to one end of each of the plurality of indoor heat exchangers, one end of each of the plurality of return branch pipes is connected to the first junction header via each of the plurality of first return branch pipe opening / closing valves, and the other end of each of the plurality of return branch pipes is connected to the other end of each of the plurality of indoor heat exchangers,the first junction header, the first pump, the outbound main pipe on-off valve, the outbound main pipe, the intermediate heat exchanger, the return main pipe, the return main pipe on-off valve, the first branch header, each of the plurality of first outbound branch pipe on-off valves, each of the plurality of outbound branch pipes, each of the plurality of indoor heat exchangers, each of the plurality of return branch pipes, and each of the plurality of first return branch pipe on-off valves constitute a first heat medium circulation path connected so that a heat medium flows in this order, and the intermediate heat exchanger is configured so that heat exchange is performed between the refrigerant flowing through the first refrigerant piping path and the heat medium flowing through the first heat medium circulation path.

2. Each of the plurality of branch units has a second branch header, a second junction header, a plurality of second outward branch pipe on-off valves, a plurality of second return branch pipe on-off valves, a second bypass valve, a second pump, a first heat exchanger, a second heat exchanger, a second compressor, a second four-way valve, and a second expansion valve, each of the plurality of outward branch pipes having one end connected to the first branch header via each of the plurality of first outward branch pipe on-off valves and connected to the second branch header via each of the plurality of second outward branch pipe on-off valves, each of the plurality of return branch pipes having one end connected to the first junction header via each of the plurality of first return branch pipe on-off valves and connected to the second junction header via each of the plurality of second return branch pipe on-off valves, the second branch header and the second junction header are connected via the second bypass valve, the second junction header, the second pump, the second heat exchanger, the second branch header, each of the plurality of second outward branch piping on / off valves, each of the plurality of outward branch piping, each of the plurality of indoor heat exchangers, each of the plurality of return branch piping, and each of the plurality of second return branch piping on / off valves constitute a second heat medium circulation path connected to allow the heat medium to flow in this order; the second compressor, the second four-way valve, the first heat exchanger, the second expansion valve, and the second heat exchanger constitute a second refrigerant piping path connected to allow a refrigerant to flow, and the second four-way valve is configured to switch between flowing the refrigerant in the order of the second compressor, the second four-way valve, the first heat exchanger, the second expansion valve, the second heat exchanger, and the second four-way valve, or flowing the refrigerant in the order of the second compressor, the second four-way valve, the second heat exchanger, the second expansion valve, the first heat exchanger, and the second four-way valve, 2. The air-conditioning apparatus of claim 1, wherein the first heat exchanger is configured to perform heat exchange between the heat medium flowing through the first heat medium circulation path and the refrigerant flowing through the second refrigerant piping path, and the second heat exchanger is configured to perform heat exchange between the heat medium flowing through the second heat medium circulation path and the refrigerant flowing through the second refrigerant piping path.

3. An air conditioning apparatus as described in claim 1 or 2, wherein the order of the connection points from each of the plurality of branch units in the outward main piping from the outdoor unit is the same as the order of the connection points from each of the plurality of branch units in the return main piping from the outdoor unit.

4. An air conditioning apparatus as described in any one of claims 1 to 3, wherein the inner diameter of the outward main pipe and the return main pipe connected to each of the plurality of branch units closer to the outdoor unit is greater than or equal to the inner diameter of the outward main pipe and the return main pipe connected to each of the plurality of branch units farther from the outdoor unit.

5. An air conditioning apparatus as described in any one of claims 1 to 4, wherein the capacity of the first pump of each of the plurality of branch units that is closer to the outdoor unit is smaller than the capacity of the first pump of each of the plurality of branch units that is farther from the outdoor unit.

6. An air conditioning apparatus as described in any one of claims 1 to 5, wherein the main outward piping and the main return piping connect the outdoor unit to one of the plurality of branch units, and connect one of the plurality of branch units to the rest in series.

7. An air-conditioning apparatus according to any one of claims 1 to 6, wherein the outdoor unit is disposed above the plurality of branch units.

8. The air conditioning apparatus according to any one of claims 1 to 7, wherein each of the plurality of branch units has a bypass path connecting between the outgoing main piping on-off valve and the first pump in the first heat medium circulation path and between the return main piping on-off valve and the first branch header in the first heat medium circulation path, the bypass path has a flow control valve for adjusting a flow rate of the heat medium flowing through the bypass path, and in a defrosting operation for removing frost adhered to the outdoor heat exchanger of the outdoor unit, the first pump is configured to be operated with the outgoing main piping on-off valve and the return main piping on-off valve open and the flow control valve closed in the branch unit farthest from the outdoor unit among the plurality of branch units, and the first pump is configured to be operated with the outgoing main piping on-off valve and the return main piping on-off valve closed and the flow control valve open in the branch unit other than the branch unit farthest from the outdoor unit.

Images