US20240401827A1 - Air-conditioning apparatus - Google Patents

Air-conditioning apparatus Download PDF

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Publication number
US20240401827A1
US20240401827A1 US18/699,649 US202118699649A US2024401827A1 US 20240401827 A1 US20240401827 A1 US 20240401827A1 US 202118699649 A US202118699649 A US 202118699649A US 2024401827 A1 US2024401827 A1 US 2024401827A1
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United States
Prior art keywords
unit
refrigerant
indoor
valve
outdoor
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Pending
Application number
US18/699,649
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English (en)
Inventor
Nobuhiro Wada
Kazuyoshi Shinozaki
Hiroyuki Okano
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Filing date
Publication date
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Assigned to MITSUBISHI ELECTRIC CORPORATION reassignment MITSUBISHI ELECTRIC CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: OKANO, HIROYUKI, SHINOZAKI, KAZUYOSHI, WADA, NOBUHIRO
Publication of US20240401827A1 publication Critical patent/US20240401827A1/en
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • F24F11/32—Responding to malfunctions or emergencies
    • F24F11/36—Responding to malfunctions or emergencies to leakage of heat-exchange fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F1/00—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station
    • F24F1/06—Separate outdoor units, e.g. outdoor unit to be linked to a separate room comprising a compressor and a heat exchanger
    • F24F1/26—Refrigerant piping
    • F24F1/32—Refrigerant piping for connecting the separate outdoor units to indoor units
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B13/00—Compression machines, plants or systems, with reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F25B41/24—Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/005—Arrangement or mounting of control or safety devices of safety devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
    • F25B2313/0233—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in parallel arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/22—Preventing, detecting or repairing leaks of refrigeration fluids
    • F25B2500/221—Preventing leaks from developing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/22—Preventing, detecting or repairing leaks of refrigeration fluids
    • F25B2500/222—Detecting refrigerant leaks
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2519—On-off valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/19—Pressures

Definitions

  • the present disclosure relates to an air-conditioning apparatus including a shut-off valve.
  • Patent Literature 1 discloses an air-conditioning apparatus that closes, when detecting a leak of refrigerant, a solenoid valve and a shut-off valve in order to reduce further occurrence of the refrigerant leak.
  • the air-conditioning apparatus according to Patent Literature 1 includes an electromagnetic expansion valve and a shut-off valve that are provided in the following manner.
  • the electromagnetic expansion valve is provided in a refrigerant circuit that is located between an outdoor heat exchanger and an indoor heat exchanger such that no compressor is interposed between the outdoor heat exchanger and the indoor heat exchanger.
  • the shut-off valve is provided in a refrigerant circuit that is located between an outdoor heat exchanger and an indoor heat exchanger, with a compressor interposed between the outdoor heat exchanger and the indoor heat exchanger.
  • Patent Literature 1 proposes use of a controller that closes the electromagnetic expansion valve to cause refrigerant to collect on an outdoor heat exchanger side, when a leak of refrigerant is detected, and then closes the shut-off valve.
  • refrigerant leaks from an air-conditioning apparatus further occurrence of such a refrigerant leak is reduced using, for example, the controller described in Patent Literature 1, the air-conditioning apparatus is stopped, and a component of the air-conditioning apparatus is then repaired or replaced by a new one. In this case, it is necessary to find a location at which the refrigerant leak occurs. Furthermore, in the case of repairing or replacing a component of the air-conditioning apparatus, in some cases, the refrigerant is drawn out from the air-conditioning apparatus, the component is repaired or replaced by a new one, and refrigerant is then re-filled into the air-conditioning apparatus.
  • refrigerant pipes have no part that allows connection of external equipment such as, a temperature sensor, a pressure sensor, a pump for drawing the refrigerant, a pump for re-filing refrigerant, and a vacuum pump. Inevitably, it takes time to, for example, find a location where a refrigerant leak occur, draw out refrigerant, and re-fill refrigerant.
  • the present disclosure is applied in view of the above circumstances, and relates to an air-conditioning apparatus that is improved in maintainability.
  • An air-conditioning apparatus includes: an outdoor unit including a compressor and an outdoor heat exchanger, and configured to generate cooling energy or heating energy; an indoor unit including an indoor heat exchanger, and configured to perform an air-conditioning operation with the cooling energy or the heating energy that is generated by the outdoor unit; a refrigerant pipe provided between the outdoor unit and the indoor unit, and forming a refrigerant circuit in which refrigerant circulates; and a shut-off valve provided at the refrigerant pipe, and configured to be closed when a refrigerant leak is detected.
  • the shut-off valve includes a service port communicating with the refrigerant pipe.
  • FIG. 1 is a schematic view illustrating an example of a circuit configuration of an air-conditioning apparatus according to Embodiment 1.
  • the outdoor unit 3 includes a compressor 6 , an outdoor heat exchanger 7 , an expansion valve 8 , the refrigerant flow switching device 9 , and an accumulator 25 .
  • the compressor 6 compresses refrigerant to change it into high-temperature and high-pressure refrigerant, and discharges the high-temperature and high-pressure refrigerant.
  • the outdoor heat exchanger 7 causes heat exchange to be performed between the refrigerant and air (hereinafter referred to as “outdoor air” as appropriate) supplied by an air-sending device such as a fan (not illustrated).
  • the outdoor heat exchanger 7 serves as a condenser that transfers the heat of the refrigerant to the outdoor air to thereby condense the refrigerant.
  • the outdoor heat exchanger 7 serves as an evaporator that evaporates the refrigerant to thereby cool the outdoor air with the heat of vaporization.
  • the accumulator 25 is connected to a suction side of the compressor 6 .
  • the accumulator 25 is connected to the downstream side of the outdoor heat exchanger 7 in the heating operation.
  • the accumulator 25 is connected to the downstream side of an indoor heat exchanger 4 in the cooling operation.
  • the accumulator 25 is a container that stores surplus refrigerant, and absorbs the difference in refrigerant flow rate between the cooling operation and the heating operation.
  • the outdoor unit 3 may include no accumulator 25 .
  • the expansion valve 8 reduces the pressure of refrigerant that flows from the indoor units 2 a , 2 b , and 2 c in the heating operation.
  • the outdoor unit 3 may include no expansion valve 8 .
  • the expansion valve 5 may be used to fulfill the function of the expansion valve 8 .
  • the indoor units 2 a , 2 b , and 2 c are installed in spaces 1 a , 1 b , and 1 c , respectively, which are air-conditioning target spaces.
  • the indoor units 2 a , 2 b , and 2 c supply air for cooling or air for heating to the spaces 1 a , 1 b , and 1 c , respectively, using the cooling energy or heating energy of refrigerant that circulates through the refrigerant pipe 10 .
  • the indoor units 2 a , 2 b , and 2 c include respective indoor heat exchangers 4 and respective expansion valves 5 .
  • indoor unit 2 does not illustrate circuit configurations of the indoor units 2 b and 2 c in detail, these circuit configurations are the same as the circuit configuration of the indoor unit 2 a .
  • the indoor units 2 a , 2 b , and 2 c are each simply referred to as “indoor unit 2 ” as appropriate in the case where they do not particularly be distinguished from each other.
  • the following description is also made assuming that the term “indoor unit 2 ” is applicable to both a single indoor unit 2 and plural indoor units 2 .
  • the indoor heat exchanger 4 in each of the indoor units 2 a , 2 b , and 2 c causes heat exchange to be performed between air supplied by an air-sending device such as a fan (not illustrated) and refrigerant, thereby obtaining air for cooling or air for heating, which is to be supplied to an associated one of the spaces 1 a , 1 b , and 1 c .
  • an air-sending device such as a fan (not illustrated)
  • refrigerant carries cooling energy in the cooling operation
  • the indoor heat exchanger 4 operates as an evaporator to perform the cooling operation by cooling the air in the associated one of the spaces 1 a , 1 b , and 1 c , which are air-conditioning target spaces.
  • the indoor heat exchanger 4 operates as a condenser to perform the heating operation by heating the air in the associated one of the spaces 1 a , 1 b , and 1 c , that is, air-conditioning target spaces.
  • a fluid can flow through the flow passage 38 from the outdoor-unit-side connection pipe 32 b toward the indoor-unit-side connection pipe 32 a , or from the indoor-unit-side connection pipe 32 a toward the outdoor-unit-side connection pipe 32 b .
  • the flow passage 38 is shut off when the valve body 37 is moved down to the closed position P.
  • the flow passage 38 is in the open state when the valve body 37 is located above the closed position P.
  • the flow passage 38 includes the first opening 38 a 4 , the main flow passage 38 a 1 , the main-passage communication part 38 a 3 , the main flow passage 38 a 2 , and the second opening 38 a 5 .
  • the second opening 38 a 5 is connected to the outdoor-unit-side connection pipe 32 b , and serves as an inlet or outlet for fluid.
  • the main flow passage 38 a 1 is a passage extending substantially horizontally from the second opening 38 a 5 .
  • the main-passage communication part 38 a 3 is a passage located between the main flow passage 38 a 1 and the main flow passage 38 a 2 , and extending upward from an end of the main flow passage 38 a 1 .
  • the main flow passage 38 a 2 is a passage that is L-shaped as a whole.
  • the main flow passage 38 a 2 extends downward from the lower end of the main-passage communication part 38 a 3 , and further extends substantially horizontally.
  • the main flow passage 38 a 2 is connected at one end to the lower end of the main-passage communication part 38 a 3 as described above, and connected at the other end to the first opening 38 a 4 .
  • the first opening 38 a 4 is connected to the indoor-unit-side connection pipe 32 a , and serves as an inlet or outlet for fluid.
  • the valve body 37 is moved up and down in the main-passage communication part 38 a 3 to open and close the space between the main flow passage 38 a 1 and the main flow passage 38 a 2 .
  • a reference sign denoting the flow passage 38 is not indicated in FIG. 2 .
  • the communication between the main flow passage 38 a 1 and the main flow passage 38 a 2 is shut off when the valve body 37 is located in the closed position P.
  • the closed position P of the valve body 37 corresponds to a position where the main-passage communication part 38 a 3 and the main flow passage 38 a 2 are connected with each other.
  • the main flow passage 38 a 2 is too narrow in width to allow the valve body 37 to move therein.
  • the main flow passage 38 a 2 is connected with the lower end of the main-passage communication part 38 a 3 .
  • valve body 37 when the valve body 37 is moved down in the main-passage communication part 38 a 3 , the valve body 37 cannot be further moved down to a position located below the position where the main-passage communication part 38 a 3 and the main flow passage 38 a 2 connect with each other. That is, in this state, the valve body 37 blocks the space between the main-passage communication part 38 a 3 and the main flow passage 38 a 2 .
  • the main flow passage 38 a 1 is connected to the main-passage communication part 38 a 3 at a position located above the closed position P of the valve body 37 .
  • the valve body 37 blocks the space between the main flow passage 38 a 1 and the main-passage communication part 38 a 3 .
  • the air-conditioning apparatus 100 having the above configuration is operated in the cooling operation and in the heating operation, based on the flow of the refrigerant.
  • all of the indoor units 2 a , 2 b , and 2 c may perform the cooling operation or all of the indoor units 2 a , 2 b , and 2 c may perform the heating operation.
  • the liquid refrigerant that has flowed into the outdoor-unit-side connection pipe 32 b of each of the indoor-unit-side shut-off valves 30 a - 1 , 30 a - 3 , and 30 a - 5 flows through the flow passage 38 of that indoor-unit-side shut-off valve, and flows out from the indoor-unit-side connection pipe 32 a of the indoor-unit-side shut-off valve.
  • the gas refrigerant that has flowed out from each of the indoor heat exchangers 4 flows into the indoor-unit-side connection pipe 32 a of an associated one of the indoor-unit-side shut-off valves 30 a - 2 , 30 a - 4 , and 30 a - 6 .
  • the gas refrigerant that has flowed into the indoor-unit-side connection pipe 32 a of the above indoor-unit-side shut-off valve flows through the flow passage 38 of the above indoor-unit-side shut-off valve, and flows out from the outdoor-unit-side connection pipe 32 b of the indoor-unit-side shut-off valve.
  • the gas refrigerant that has flowed into the outdoor unit 3 returns to the compressor 6 after flowing through the refrigerant flow switching device 9 and the accumulator 25 . In the cooling operation, the circulation of refrigerant as described above is repeated.
  • the refrigerant that has flowed out from the outdoor unit 3 flows through the refrigerant pipe 10 and flows into the outdoor-unit-side connection pipe 32 b of the outdoor-unit-side shut-off valve 30 b - 2 .
  • the refrigerant that has flowed into the outdoor-unit-side connection pipe 32 b of the outdoor-unit-side shut-off valve 30 b - 2 flows through the flow passage 38 of the outdoor-unit-side shut-off valve 30 b - 2 , and flows out from the indoor-unit-side connection pipe 32 a of the outdoor-unit-side shut-off valve 30 b - 2 .
  • the refrigerant that has flowed out from the indoor-unit-side connection pipe 32 a of the outdoor-unit-side shut-off valve 30 b - 2 flows through the refrigerant pipe 10 and flows into the outdoor-unit-side connection pipe 32 b of each of the indoor-unit-side shut-off valves 30 a - 2 , 30 a - 4 , and 30 a - 6 .
  • the refrigerant that has flowed into the outdoor-unit-side connection pipe 32 b of each of the indoor-unit-side shut-off valves 30 a - 2 , 30 a - 4 , and 30 a - 6 flows through the flow passage 38 of that indoor-unit-side shut-off valve, and flows out from the indoor-unit-side connection pipe 32 a of the indoor-unit-side shut-off valve.
  • the refrigerant that has flowed out from the indoor-unit-side connection pipe 32 a of the indoor-unit-side shut-off valve flows into the indoor heat exchanger 4 in an associated one of the indoor units 2 a to 2 c.
  • the refrigerant that has flowed into the indoor heat exchanger 4 exchanges heat with indoor air to condense while transferring heat to the indoor air, thereby heating the indoor air, and thus changes into liquid refrigerant.
  • the liquid refrigerant then flows out from the indoor heat exchanger 4 .
  • the liquid refrigerant that has flowed out form the indoor heat exchanger 4 flows through the expansion valve 5 that is provided in an associated one of the indoor units 2 a to 2 c and that is in the open state, and then flows into the indoor-unit-side connection pipe 32 a of an associated one of the indoor-unit-side shut-off valves 30 a - 1 , 30 a - 3 , and 30 a - 5 .
  • the liquid refrigerant that has flowed into the indoor-unit-side connection pipe 32 a of the above indoor-unit-side shut-off valve flows through the flow passage 38 of the indoor-unit-side shut-off valve, and flows out from the outdoor-unit-side connection pipe 32 b of the indoor-unit-side shut-off valve.
  • the liquid refrigerant that has flowed out from the outdoor-unit-side connection pipe 32 b flows through the refrigerant pipe 10 and flows into the indoor-unit-side connection pipe 32 a of the outdoor-unit-side shut-off valve 30 b - 1 .
  • the liquid refrigerant that has flowed into the indoor-unit-side connection pipe 32 a of the outdoor-unit-side shut-off valve 30 b - 1 flows through the flow passage 38 of the outdoor-unit-side shut-off valve 30 b - 1 and flows out from the outdoor-unit-side connection pipe 32 b of the outdoor-unit-side shut-off valve 30 b - 1 .
  • FIG. 3 is a perspective view illustrating an example of the configuration of the appearance of the shut-off valve unit 300 according to Embodiment 1.
  • FIG. 3 illustrates, for the purpose of explanation, an example in which the indoor-unit-side shut-off valves 30 a - 1 and 30 a - 2 as illustrated in FIG. 1 are formed as the shut-off valve unit 300 .
  • the vertical section as illustrated in FIG. 2 corresponds to a portion A indicated by chain double-dashed lines in FIG. 3 .
  • the shut-off valve unit 300 may be formed as a single unit made up of three or more shut-off valves 30 .
  • shut-off valves 30 connected to the same indoor unit 2 can be provided as a shut-off valve unit 300 . Therefore, in the air-conditioning apparatus 100 as illustrated in FIG. 1 , the indoor-unit-side shut-off valves 30 a - 1 and 30 a - 2 connected to the indoor unit 2 a can be provided as a first shut-off valve unit 300 ; the indoor-unit-side shut-off valves 30 a - 3 and 30 a - 4 connected to the indoor unit 2 b can be formed as a second shut-off valve unit 300 ; and the indoor-unit-side shut-off valves 30 a - 5 and 30 a - 6 connected to the indoor unit 2 c can be formed as a third shut-off valve unit 300 .
  • the outdoor-unit-side shut-off valves 30 b - 1 and 30 b - 2 connected to the outdoor unit 3 can be formed as a single shut-off valve unit 300 .
  • the shut-off valve unit 300 includes two shut-off valves 30 , that is, the indoor-unit-side shut-off valve 30 a - 1 and the indoor-unit-side shut-off valve 30 a - 2 .
  • the block body 31 of the indoor-unit-side shut-off valve 30 a - 1 and the block body 31 of the indoor-unit-side shut-off valve 30 a - 2 are formed as a single block body 31 A.
  • the flow passage 38 of the indoor-unit-side shut-off valve 30 a - 1 and the flow passage 38 of the indoor-unit-side shut-off valve 30 a - 2 are arranged side by side in the block body 31 A. As illustrated in FIG.
  • the block body 31 A of the shut-off valve unit 300 has the first opening 38 a 4 and the second opening 38 a 5 of the indoor-unit-side shut-off valve 30 a - 1 and the first opening 38 a 4 and the second opening 38 a 5 of the indoor-unit-side shut-off valve 30 a - 2 .
  • respective indoor-unit-side connection pipes 32 a are connected.
  • respective outdoor-unit-side connection pipes 32 b are connected.
  • the service port 50 is provided in the block body 31 of the shut-off valve 30 such that the service port 50 communicates with the flow passage 38 . Therefore, the service port 50 communicates with the refrigerant pipe 10 via the flow passage 38 .
  • the service port 50 has a tip 51 and a connection part 52 .
  • the tip 51 can be formed to have an opening that allows external equipment to be inserted from the tip 51 into the service port 50 . When being inserted from the tip 51 of the service port 50 , the external equipment can communicate with the refrigerant pipe 10 .
  • the tip 51 may be shaped to serve as a joint that allows connection of the external equipment. For example, a push-in joint may be provided as the tip 51 . Alternatively, a screwed-threaded joint and a sealing component may be provided as the tip 51 .
  • connection part 52 of the service port 50 has a tubular shape, and connects the tip 51 of the service port 50 and the flow passage 38 of the shut-off valve 30 .
  • the external equipment inserted from the tip 51 can be moved to the flow passage 38 of the shut-off valve 30 through the connection part 52 .
  • FIG. 4 illustrates two service ports 50 that communicates with the first main flow passage 38 a 1 and the main flow passage 38 a 2 , respectively.
  • a first one of the service ports 50 is provided at a location where the first service port 50 communicates with the main flow passage 38 a 1
  • a second one of the service ports 50 is provided at a location where the second service port 50 communicates with the main flow passage 38 a 2 .
  • the two service ports 50 can be used to communicate with the indoor-unit-side connection pipe 32 a and the outdoor-unit-side connection pipe 32 b . That is, when the external equipment is connected with the two service ports 50 , it can communicate with the refrigerant pipe 10 connected to the indoor unit 2 and the refrigerant pipe 10 connected to the outdoor unit 3 .
  • the number of service ports 50 and the installation positions of the service ports 50 are not limited to those as illustrated in FIG. 4 .
  • a single service port 50 may be provided in such a manner as to communicate with some portion of the flow passage 38 provided in the block body 31 .
  • another service port 50 may be provided.
  • the service port 50 provided in the flow passage 38 does not necessarily have to protrude from the bottom of the block body 31 .
  • the service port 50 may protrude from the side or top of the block body 31 .
  • service port 50 is provided in the block body 31 of the shut-off valve 30 .
  • service ports 50 may be provided in the indoor-unit-side connection pipe 32 a and the outdoor-unit-side connection pipe 32 b .
  • the service port 50 may be provided in either the indoor-unit-side connection pipe 32 a or the outdoor-unit-side connection pipe 32 b .
  • one service port 50 may be provided in the block body 31
  • another service port 50 may be provided in either the indoor-unit-side connection pipe 32 a or the outdoor-unit-side connection pipe 32 b.
  • service ports 50 are provided in the indoor-unit-side connection pipes 32 a and the outdoor-unit-side connection pipes 32 b of the shut-off valve unit 300 .
  • respective service ports 50 are provided in all the outdoor-unit-side connection pipes 32 b and the indoor-unit-side connection pipes 32 a .
  • a combination of the number of service ports 50 and the locations of the service ports 50 is not limited to those illustrated in FIG. 6 .
  • the number of service ports 50 and the locations of the service port 50 may be combined such that the service port or ports 50 are provided in the following manner: for example, in the service port 50 in the outdoor-unit-side connection pipe 32 b of the indoor-unit-side shut-off valve 30 a - 1 and in the indoor-unit-side connection pipe 32 a of the indoor-unit-side shut-off valve 30 a - 2 , respective service ports 50 are provided.
  • the service port 50 may be provided in the block body 31 A in such a manner as to communicate with the flow passage 38 .
  • External equipment for use in maintenance of the air-conditioning apparatus 100 can be directly connected to the tip 51 of the service port 50 .
  • the maintenance of the air-conditioning apparatus 100 means work such as installation, removal, relocation, repair, modification, and inspection of the air-conditioning apparatus 100 .
  • external equipment for example, a pressure sensor, a device for drawing refrigerant, a vacuum pump, and a tank for re-filing refrigerant.
  • a connection hose may be directly connected to the tip 51 . In the case where the external equipment cannot be directly connected to the tip 51 , it suffices that the external equipment is connected to a connection hose connected to the tip 51 .
  • respective pressure sensors 60 are connected in order to detect pressures in the respective regions. It is therefore possible to determine from which of the first region AR1, the second region AR2, and the third region AR3 refrigerant leaks.
  • the pressure sensor 60 may be connected to the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 or the outdoor-unit-side shut-off valve 30 b - 2 that communicates with the third region AR3.
  • FIG. 8 illustrates an example in which refrigerant leaks at a refrigerant leak position LP at the refrigerant pipe 10 .
  • respective pressure sensors 60 are connected to all of the service ports 50 , it is not indispensable that the pressure sensors 60 are connected to all the service ports 50 simultaneously, and it suffices that the pressure sensors 60 are successively connected to the respective service ports 50 to detect the pressures in the respective regions.
  • the value detected by the pressure sensor 60 connected to the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 is close to the atmospheric pressure.
  • the pressure sensor 60 connected to the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 is indicated in a dotted pattern.
  • the values detected by the pressure sensors 60 connected to the respective service ports 50 of the indoor-unit-side shut-off valve 30 a - 1 , the indoor-unit-side shut-off valve 30 a - 2 , and the outdoor-unit-side shut-off valve 30 b - 2 are kept constant after deactivation of the air-conditioning apparatus 100 .
  • FIG. 9 is a schematic view illustrating an example in which external equipment is connected to the service ports 50 as illustrated in FIG. 7 .
  • a vacuum pump 61 is connected as external equipment to the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 .
  • the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 is provided at a location where the service port 50 communicates with the indoor-unit-side connection pipe 32 a . As illustrated in FIG.
  • the vacuum pump 61 as illustrated in FIG. 9 is connected to the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 , but can also be connected to the service port 50 of any one of the indoor-unit-side shut-off valve 30 a - 1 , the indoor-unit-side shut-off valve 30 a - 2 , and the outdoor-unit-side shut-off valve 30 b - 2 .
  • vacuum pumps 61 can be connected to the service port 50 of the outdoor-unit-side shut-off valve 30 b - 1 and the service port 50 of the outdoor-unit-side shut-off valve 30 b - 2 , and evacuate the refrigerant pipes 10 located in the second region AR2 at the same time. It is therefore possible to shorten the time required to perform evacuation.
  • external equipment can be inserted into the refrigerant pipe 10 via the service port 50 . That is, it is possible to use necessary external equipment via the service port 50 at the time of performing maintenance of the air-conditioning apparatus 100 , and thus possible to improve the maintainability of the air-conditioning apparatus 100 .
  • the service ports 50 of the air-conditioning apparatus 100 according to Embodiment 1 each have the tip 51 that can be opened and closed and allows external equipment to be attached to and detached from the tip 51 .
  • the tip 51 is opened when the external equipment is connected to the tip 52 .
  • a pressure sensor, a device for drawing refrigerant, a vacuum pump, a tank for re-filing refrigerant, and a connection hose can be directly or indirectly connected to the service port 50 .
  • the shut-off valves 30 according to Embodiment 1 each include the block body 31 , the valve body 37 , and the connection pipes 32 .
  • the block body 31 includes the passages 38 that communicate with the refrigerant pipes 10 .
  • each of the flow passage 38 is made to be opened or closed.
  • the connection pipes 32 are connected to the passages 38 , and protrudes from the block body 31 .
  • the connection pipes 32 are connected to the refrigerant pipes 10 .
  • the service ports 50 are provided at the connection pipes 32 .
  • the service ports 50 are provided at the connection pipes 32 of the shut-off valves 30 , which are pipes directly connected to the refrigerant pipes 10 . Therefore, when external equipment needs to be inserted all the way into the refrigerant pipe 10 , this insertion can be relatively easily performed. It is therefore possible to further improve the maintainability of the air-conditioning apparatus 100 .
  • the shut-off valves 30 include the indoor-unit-side shut-off valves 30 a and the outdoor-unit-side shut-off valves 30 b .
  • the indoor-unit-side shut-off valves 30 a are located closer to the indoor unit 2 than to the outdoor unit 3 .
  • the outdoor-unit-side shut-off valves 30 b are located closer to the outdoor unit 3 than to the indoor unit 2 .
  • a region where the refrigerant pipes 10 located between the indoor-unit-side shut-off valve 30 a and the outdoor-unit-side shut-off valve 30 b are provided can be handled as a single region.
  • the plural indoor-unit-side shut-off valves 30 a are provided.
  • the indoor-unit-side shut-off valves 30 a - 1 and 30 a - 2 include the indoor-unit-side shut-off valve 30 a - 1 that is provided at part of the refrigerant pipe 10 through which the refrigerant passes to flow into the indoor unit 2 , and the outdoor-unit-side shut-off valve 30 a - 2 that is provided at part of the refrigerant pipe 10 through which the refrigerant passes after flowing out from the indoor unit 2 .
  • the plural outdoor-unit-side shut-off valves 30 b are provided.
  • the outdoor-unit-side shut-off valves 30 b - 1 and 30 b - 2 include the outdoor-unit-side shut-off valve 30 b - 1 that is provided at part of the refrigerant pipe 10 through which the refrigerant passes to flow into the outdoor unit 3 , and the outdoor-unit-side shut-off valve 30 b - 2 that is provided at part of the refrigerant pipe 10 through which the refrigerant passes after flowing out from the outdoor unit 3 .
  • the inside of the air-conditioning apparatus 100 is divided into the first region AR1 where the indoor unit 2 is installed, the second region AR2 where the refrigerant pipe 10 connecting the indoor unit 2 and the outdoor unit 3 is provided, and the third region AR3 where the outdoor unit 3 is installed, and in this state, the maintenance of the air-conditioning apparatus 100 can be performed. It is therefore possible to perform maintenance on the first to third regions AR1 to AR3 simultaneously, using the service ports 50 associated with these regions. In addition, in the case of offering service to only a region, maintenance can be performed on only the region, using the service port 50 associated with the region. It is therefore possible to shorten the time required for performing maintenance on the air-conditioning apparatus 100 , and further improve the maintainability of the air-conditioning apparatus 100 .
  • the total length of refrigerant pipes connecting an outdoor unit and plural indoor units can be several hundred meters.
  • the amount of refrigerant for use in the air-conditioning apparatus is also increased. Therefore, in an air-conditioning apparatus having refrigerant pipes the total length of which is great, in some cases, it takes a long time to determine a location where a refrigerant leak occurs, since it is necessary to check whether the refrigerant leak occurs, over a relatively large region. For this reason, it may sometimes take time to determine a location where a leak occurs.
  • the air-conditioning apparatus 100 in the air-conditioning apparatus 100 according to Embodiment 1, it is possible to perform maintenance on the first to third regions AR1 to AR3 at the same time, which are provided independently of each other, using the service ports 50 . Accordingly, it is possible to check the first to third regions AR1 to AR3 simultaneously as to whether a refrigerant leak occurs or not. In addition, it is possible to perform an operation for drawing back refrigerant, an operation for re-filling refrigerant, and an operation for evacuation, on the first to third regions AR1 to AR3, at the same time. Furthermore, it is also possible to perform different maintenance operations on the regions at the same time. The maintainability of the air-conditioning apparatus 100 is thus further improved.
  • the outdoor unit 3 includes plural check valves 16 a , 16 b , 16 c , and 16 d ; and a relay unit 17 is installed between the outdoor unit 3 and plural indoor units 2 .
  • the air-conditioning apparatus 100 according to Embodiment 2 is different in configuration from the air-conditioning apparatus 100 according to Embodiment 1. It should be noted that regarding Embodiment 2, components that are the same as those in Embodiment 1 will be denoted by the same reference signs and their description will thus be omitted.
  • FIG. 10 is a schematic view illustrating an example of a circuit configuration of the air-conditioning apparatus 100 according to Embodiment 2.
  • the air-conditioning apparatus 100 according to Embodiment 2 is a two-pipe type air-conditioning apparatus 100 in which two pipes are provided as refrigerant pipes 10 located between the outdoor unit 3 and the relay unit 17 .
  • the outdoor-unit-side shut-off valves 30 b - 1 and 30 - b 2 are provided at the refrigerant pipes 10 between the outdoor unit 3 and the relay unit 17 .
  • the air-conditioning apparatus 100 includes the indoor-unit-side shut-off valves 30 a - 1 , 30 a - 2 , 30 a - 3 , 30 a - 4 , 30 a - 5 , and 30 a - 6 associated with the indoor units 2 a , 2 b , and 2 c .
  • the shut-off valves 30 according to Embodiment 2 are the same as those in Embodiment 1, and their descriptions will thus be omitted.
  • illustration of dashed lines indicating connection between the controller 20 and the shut-off valve 30 is omitted.
  • the air-conditioning apparatus 100 it is possible to activate an indoor unit that performs the cooling operation and an indoor unit that performs the heating operation at the same time.
  • a cooling load on the indoor unit that performs the cooling operation exceeds a heating load on the indoor unit that performs the heating operation
  • a heating main operation is performed.
  • the cooling main operation is performed as the cooling load exceeds the heating load, for example, the number of indoor units that perform the cooling operation is larger than that of indoor units that perform the heating operation.
  • the heating main operation is performed as the heating load exceeds the cooling load, the number of indoor units that perform the heating operation is larger than that of indoor units that perform the cooling operation.
  • FIG. 10 as an example of the flow of the refrigerant in the cooling main operation, solid arrows indicate the flow of the refrigerant in the case where the indoor units 2 a and 2 b perform the cooling operation and the indoor unit 2 c performs the heating operation. Also, in FIG. 10 , as an example of the flow of the refrigerant in the heating main operation, dashed arrows indicate the flow of the refrigerant in the case where the indoor units 2 a and 2 b perform the heating operation and the indoor unit 2 c performs the cooling operation.
  • the outdoor unit 3 includes plural check valves 16 a , 16 b , 16 c , and 16 d .
  • the check valves 16 a , 16 b , 16 c , and 16 d adjust the flow of the refrigerant by preventing backflow of the refrigerant, such that the refrigerant circulates in a single direction.
  • the relay unit 17 is provided between the outdoor unit 3 and the indoor-unit-side shut-off valves 30 a - 1 to 30 a - 6 .
  • the outdoor unit 3 and the relay unit 17 are connected by refrigerant pipes 10 .
  • the refrigerant pipes 10 between the outdoor unit 3 and the relay unit 17 include a refrigerant-pipe communication part 10 a and a refrigerant-pipe communication part 10 b .
  • Refrigerant that flows from the outdoor unit 3 to the relay unit 17 passes through the refrigerant-pipe communication part 10 a .
  • Refrigerant that flows from the relay unit 17 to the outdoor unit 3 passes through the refrigerant-pipe communication part 10 b .
  • the outdoor-unit-side shut-off valve 30 b - 1 is provided at the refrigerant-pipe communication part 10 a .
  • the outdoor-unit-side shut-off valve 30 b - 2 is provided at the refrigerant-pipe communication part 10 b.
  • the indoor-unit-side shut-off valves 30 a - 1 to 30 a - 6 are provided at the refrigerant pipes 10 between the indoor unit 2 and the relay unit 17 .
  • check valves 21 a and 21 b are provided at the refrigerant pipe 10 extending from the indoor-unit-side shut-off valve 30 a - 1 .
  • check valves 21 c and 21 d are provided at the refrigerant pipe 10 extending from the indoor-unit-side shut-off valve 30 a - 3 .
  • check valves 21 e and 21 f are provided at the refrigerant pipe 10 extending from the indoor-unit-side shut-off valve 30 a - 5 .
  • the indoor-unit-side shut-off valve 30 a is located closer to an associated one of the indoor units 2 than to the relay unit 17 . Accordingly, the indoor-unit-side shut-off valve 30 a - 1 and the indoor-unit-side shut-off valve 30 a - 2 are located closer to the indoor unit 2 a than to the relay unit 17 .
  • the indoor-unit-side shut-off valve 30 a - 3 and the indoor-unit-side shut-off valve 30 a - 4 are located closer to the indoor unit 2 b than to the relay unit 17 .
  • the indoor-unit-side shut-off valve 30 a - 5 and the indoor-unit-side shut-off valve 30 a - 6 are located closer to the indoor unit 2 c than to the relay unit 17 .
  • on-off valves 22 a and 22 b are provided at the refrigerant pipe 10 extending from the indoor-unit-side shut-off valve 30 a - 2 .
  • on-off valves 22 c and 22 d are provided at the refrigerant pipe 10 extending from the indoor-unit-side shut-off valve 30 a - 4 .
  • on-off valves 22 e and 22 f are provided at the refrigerant pipe 10 extending from the indoor-unit-side shut-off valve 30 a - 6 .
  • the indoor-unit-side shut-off valves 30 a - 1 to 30 a - 6 and the indoor units 2 a to 2 c are the same in configuration as those according to Embodiment 1, and their descriptions will thus be omitted.
  • the indoor units 2 b and 2 c each include the indoor heat exchanger 4 and the expansion valve 5 as well as the indoor unit 2 a , illustration of the indoor heat exchangers 4 and the expansion valves 5 of the indoor units 2 b and 2 c is thus omitted in FIG. 10 .
  • the relay unit 17 includes a gas-liquid separator 18 , heat exchangers 23 a and 23 b , expansion valves 19 a and 19 b , the check valves 21 a , 21 b , 21 c , 21 d , 21 e , and 21 f , the on-off valves 22 a , 22 b , 22 c , 22 d , 22 e , and 22 f , and pipes 24 a , 24 b , 24 c , and 24 d .
  • the outdoor unit 3 and the gas-liquid separator 18 are connected by the refrigerant-pipe communication part 10 a .
  • the gas-liquid separator 18 , the heat exchangers 23 a and 23 b , the expansion valves 19 a and 19 b , the check valves 21 a to 21 f , the on-off valves 22 a to 22 f , and the pipes 24 a to 24 d in the relay unit 17 will be described later; that is, these components are described in the following description concerning the cooling main operation.
  • the refrigerant is compressed in the compressor 6 to change into gas refrigerant, and the gas refrigerant passes through the refrigerant flow switching device 9 and flows into the outdoor heat exchanger 7 .
  • the gas refrigerant that has flowed into the outdoor heat exchanger 7 exchanges heat with outdoor air to condense while transferring heat to the outdoor air, thereby changing into two-phase gas-liquid refrigerant.
  • the two-phase gas-liquid refrigerant then flows out from the outdoor heat exchanger 7 .
  • the two-phase gas-liquid refrigerant that has flowed out form the outdoor heat exchanger 7 passes through the expansion valve 8 and the check valve 16 a , and then flows out from the outdoor unit 3 .
  • the two-phase gas-liquid refrigerant that has flowed out from the outdoor unit 3 passes through the refrigerant-pipe communication part 10 a and the outdoor-unit-side shut-off valve 30 b - 1 and flows into the relay unit 17 .
  • the two-phase gas-liquid refrigerant that has flowed into the relay unit 17 flows into the gas-liquid separator 18 , and is separated into gas refrigerant and liquid refrigerant.
  • the gas refrigerant flows into the pipe 24 a , and the liquid refrigerant flows into the pipe 24 b .
  • the on-off valves 22 b , 22 d , and 22 f are connected.
  • the heat exchanger 23 b With the pipe 24 b to which the liquid refrigerant flows, the heat exchanger 23 b , the expansion valve 19 a , the heat exchanger 23 a , and the check valves 21 b , 21 d , and 21 f are connected.
  • the gas refrigerant that has flowed into the pipe 24 a flows toward the indoor unit 2 c which performs the heating operation.
  • the gas refrigerant that has flowed into the pipe 24 a passes through the on-off valve 22 f and through the indoor-unit-side shut-off valve 30 a - 6 associated with the indoor unit 2 c , and then flows into the indoor unit 2 c .
  • the gas refrigerant that has flowed into the indoor unit 2 c flows into the indoor heat exchanger 4 .
  • the gas refrigerant that has flowed into the indoor heat exchanger 4 of the indoor unit 2 c exchanges heat with indoor air to condense while transferring heat to the indoor air, thereby heating the indoor air.
  • the gas refrigerant changes into liquid refrigerant, and the liquid refrigerant flows out from the indoor heat exchanger 4 .
  • the liquid refrigerant that has flowed out from the indoor heat exchanger 4 is reduced in pressure by the expansion valve 5 , and then flows out from the indoor unit 2 c .
  • the liquid refrigerant that has flowed out from the indoor unit 2 c passes through the indoor-unit-side shut-off valve 30 a - 5 and flows into the relay unit 17 .
  • the liquid refrigerant that has flowed into the relay unit 17 passes through the check valve 21 e and flows into the pipe 24 d .
  • the pipe 24 d is connected to the pipe 24 b located close to the outlet of the expansion valve 19 a . Therefore, in the pipe 24 b , the liquid refrigerant that has flowed into the pipe 24 d joins the liquid refrigerant that has been subjected to separation by the gas-liquid separator 18 and then expanded by the expansion valve 19 a.
  • the subcooled liquid refrigerant joins the liquid refrigerant flowing from the pipe 24 d .
  • the liquid refrigerant obtained by the above joining is further subcooled in the heat exchanger 23 a , and then branches off. Branching part of the refrigerant flows from the pipe 24 b into the pipe 24 c .
  • the pipe 24 c is connected with the expansion valve 19 b and the heat exchangers 23 a and 23 b .
  • the pipe 24 c is connected with a pipe 24 e at a location close to the outlet of the heat exchanger 23 b .
  • the above branching part of the liquid refrigerant that has flowed into the pipe 24 c after flowing out from the heat exchanger 23 a is reduced in pressure in the expansion valve 19 b , and then flows through the heat exchangers 23 a and 23 b .
  • the liquid refrigerant exchanges heat with the liquid refrigerant flowing in the pipe 24 b to receive heat therefrom, thereby subcooling the liquid refrigerant flowing in the pipe 24 b .
  • the refrigerant After flowing out from the heat exchanger 23 b , the refrigerant joins the gas refrigerant flowing in the pipe 24 e .
  • the refrigerant obtained through the above joining then flows through the outdoor-unit-side shut-off valve 30 b - 2 and the refrigerant-pipe communication part 10 b , and flows into the outdoor unit 3 .
  • the above remaining part of the liquid refrigerant that has not flowed into the pipe 24 c after flowing out from the heat exchanger 23 a flows through the check valve 21 b or the check valve 21 d , then flows through the indoor-unit-side shut-off valve 30 a - 1 associated with the indoor unit 2 a or through the indoor-unit-side shut-off valve 30 a - 3 associated with the indoor unit 2 b , and flows into the indoor unit 2 a or the indoor unit 2 b .
  • the liquid refrigerant that has flowed into the indoor unit 2 a or the indoor unit 2 b is reduced in pressure by the expansion valve 5 , and then flows into the indoor heat exchanger 4 .
  • the liquid refrigerant that has flowed into the indoor heat exchanger 4 exchanges heat with indoor air to receive heat therefrom and evaporate, thereby cooling the indoor air.
  • the liquid refrigerant changes into gas refrigerant, and the gas refrigerant flows out from the indoor heat exchanger 4 .
  • the gas refrigerant that has flowed out from the indoor heat exchanger 4 flows through the indoor-unit-side shut-off valve 30 a - 2 or the indoor-unit-side shut-off valve 30 a - 4 and flows into the relay unit 17 .
  • the gas refrigerant that has flowed into the relay unit 17 flows through the on-off valve 22 a or the on-off valve 22 c and flows into the pipe 24 e .
  • the gas refrigerant that has flowed into the pipe 24 e joins the refrigerant flowing in the pipe 24 c , and the refrigerant obtained through the joining then flows through the outdoor-unit-side shut-off valve 30 b - 2 and the refrigerant-pipe communication part 10 b and flows into the outdoor unit 3 .
  • the gas refrigerant that has flowed from the relay unit 17 into the outdoor unit 3 through the outdoor-unit-side shut-off valve 30 b - 2 flows through the check valve 16 d , the refrigerant flow switching device 9 , and the accumulator 25 , and returns to the compressor 6 . In the cooling main operation, the above circulation of the refrigerant is repeated.
  • Refrigerant compressed in the compressor 6 flows through the refrigerant flow switching device 9 and the check valve 16 b , flows out from the outdoor unit 3 , then flows through the refrigerant-pipe communication part 10 a and the outdoor-unit-side shut-off valve 30 b - 1 , and flows into the relay unit 17 .
  • the refrigerant that has flowed into the relay unit 17 flows into the gas-liquid separator 18 and is separated into gas refrigerant and liquid refrigerant.
  • the gas refrigerant flows into the pipe 24 a , and the liquid refrigerant flows into the pipe 24 b.
  • the gas refrigerant that has flowed into the pipe 24 a flows toward one of the indoor unit 2 a and the indoor unit 2 b that performs the heating operation. More specifically, the gas refrigerant that has flowed into the pipe 24 a passes through the on-off valve 22 b or the on-off valve 22 d , then flows through the indoor-unit-side shut-off valve 30 a - 2 associated with the indoor unit 2 a or through the indoor-unit-side shut-off valve 30 a - 4 associated with the indoor unit 2 b , and flows into the indoor unit 2 a or the indoor unit 2 b . The gas refrigerant that has flowed into the indoor unit 2 a or the indoor unit 2 b flows into the indoor heat exchanger 4 .
  • the gas refrigerant that has flowed into the indoor heat exchanger 4 of the indoor unit 2 a or the indoor unit 2 b exchanges heat with indoor air to condense while transferring heat to the indoor air, thereby heating the indoor air.
  • the gas refrigerant changes into liquid refrigerant, and the liquid refrigerant flows out from the indoor heat exchanger 4 .
  • the liquid refrigerant that has flowed out from the indoor heat exchanger 4 is reduced in pressure by the expansion valve 5 of the indoor unit 2 a or the indoor unit 2 b , and then flows out from the indoor unit 2 a or the indoor unit 2 b .
  • the liquid refrigerant that has flowed out from the indoor unit 2 a or the indoor unit 2 b flows through the indoor-unit-side shut-off valve 30 a - 1 or the indoor-unit-side shut-off valve 30 a - 3 and flows into the relay unit 17 .
  • the liquid refrigerant that has flowed into the relay unit 17 flows through the check valve 21 a or the check valve 21 c and flows into the pipe 24 d .
  • the pipe 24 d is connected to the pipe 24 b , and the liquid refrigerant that has flowed into the pipe 24 d thus joins, in the pipe 24 b , the liquid refrigerant that has been obtained through separation by the gas-liquid separator 18 and expanded by the expansion valve 19 a.
  • the liquid refrigerant flowing from the pipe 24 d joins the liquid refrigerant that has flowed into the pipe 24 b after being obtained through the separation by the gas-liquid separator 18 .
  • the liquid refrigerant obtained through the separation by the gas-liquid separator 18 flows through the heat exchanger 23 b and the expansion valve 19 a and is subcooled.
  • the subcooled liquid refrigerant joins the liquid refrigerant flowing from the pipe 24 d .
  • the liquid refrigerant obtained through the above joining is further subcooled in the heat exchanger 23 a , and branches off. Then, branching part of the liquid refrigerant flows from the pipe 24 b into the pipe 24 c .
  • the pipe 24 c is connected to the pipe 24 e , and the above branching part of the liquid refrigerant that has flowed into the pipe 24 c passes through the expansion valve 19 b and the heat exchangers 23 a and 23 b and then flows into the pipe 24 e .
  • the refrigerant that has flowed into the pipe 24 e passes through the outdoor-unit-side shut-off valve 30 b - 2 and the refrigerant-pipe communication part 10 b and flows into the outdoor unit 3 .
  • Remaining part of the liquid refrigerant that has not flowed into the pipe 24 c flows through the pipe 24 b and flows toward the indoor unit 2 c , which performs the cooling operation. Specifically, the above remaining part of the liquid refrigerant that has not flowed into the pipe 24 c passes through the check valve 21 f , then passes through the indoor-unit-side shut-off valve 30 a - 5 associated with the indoor unit 2 c , and flows into the indoor unit 2 c . The liquid refrigerant that has flowed into the indoor unit 2 c is reduced in pressure by the expansion valve 5 and then flows into the indoor heat exchanger 4 .
  • the liquid refrigerant that has flowed into the indoor heat exchanger 4 exchanges heat with indoor air to receive heat therefrom and evaporate, thereby cooling the indoor air.
  • the liquid refrigerant changes into gas refrigerant, and the gas refrigerant flows out from the indoor heat exchanger 4 .
  • the gas refrigerant that has flowed out form the indoor heat exchanger 4 flows out from the indoor unit 2 c , passes through the indoor-unit-side shut-off valve 30 a - 6 , and flows into the relay unit 17 .
  • the gas refrigerant that has flowed into the relay unit 17 passes through the on-off valve 22 e and flows into the pipe 24 e .
  • the gas refrigerant that has flowed into the pipe 24 e joins the refrigerant flowing in the pipe 24 c , then passes through the outdoor-unit-side shut-off valve 30 b - 2 and the refrigerant-pipe communication part 10 b , and flows into the outdoor unit 3 .
  • the gas refrigerant that has flowed from the relay unit 17 into the outdoor unit 3 through the outdoor-unit-side shut-off valve 32 b - 2 passes through the check valve 16 c , the expansion valve 8 , and the outdoor heat exchanger 7 , and is completely gasified.
  • the completely gasified refrigerant returns to the compressor 6 through the refrigerant flow switching device 9 and the accumulator 25 . In the heating main operation, the above circulation of the refrigerant is repeated.
  • each of the shut-off valves 30 is closed as described above regarding Embodiment 1.
  • the region where each indoor unit 2 is located, the region where the relay unit 17 is located, and the region where the outdoor unit 3 is located are isolated from each other as independent regions.
  • external equipment such as a pressure sensor or a vacuum pump is connected to the shut-off valve 30 , whereby it is possible to determine the location at which the refrigerant leak occurs, and perform maintenance. For example, in the case where a refrigerant leak occurs in the vicinity of the check valve 21 a that is provided as illustrated in FIG.
  • a detection value obtained by the pressure sensor connected to the indoor-unit-side shut-off valve 30 a - 1 is close to the atmospheric pressure. Therefore, at the time of determining the location at which the refrigerant leak occurs, it is possible to shorten the time required for the checking by starting the checking from part of the refrigerant pipe 10 that is close to the indoor-unit-side shut-off valve 30 a - 1 .
  • devices for drawing refrigerant are connected to respective indoor-unit side shut-off valves, that is, the indoor-unit-side shut-off valves 30 a - 1 to 30 a - 6 , to draw back the refrigerant.
  • the indoor-unit-side shut-off valves 30 a - 1 to 30 a - 6 By applying this way, it is possible to reduce the amount of time required to draw back the refrigerant.
  • vacuum pumps are connected to plural shut-off valves 30 . Thus, they can be evacuated at the same time. It is therefore possible to reduce the time that is required for maintenance from the time at which refrigerant leaks from the air-conditioning apparatus 100 .
  • the plural indoor units 2 is provided; the relay unit 17 is installed between the outdoor unit 3 and the indoor units 2 a to 2 c , and switches the flow passage to be used in the refrigerant circuit between plural flow passages; the outdoor unit 3 , the relay unit 17 , and the indoor units 2 a to 2 c are connected by the refrigerant pipes 10 ; and for the indoor units 2 a to 2 c , the respective indoor-unit-side shut-off valves 30 a are provided, and each of the indoor-unit-side shut-off valves 30 a is located closer to an associated one of the indoor units 2 than to the relay unit 17 .
  • the inside of the air-conditioning apparatus 100 is divided into a region where the outdoor unit 3 is installed, a region located between the relay unit 17 and the indoor unit 2 , a region where the indoor unit 2 a is installed, a region where the indoor unit 2 b is installed, and a region where the indoor unit 2 c is installed, whereby those regions can be subjected to maintenance independently of each other. It is therefore possible to perform maintenance on the above regions simultaneously, and thus reduce the time required for maintenance on the air-conditioning apparatus 100 . Accordingly, the maintainability of the air-conditioning apparatus 100 is improved.
  • the shut-off valves 30 and the air-conditioning apparatus 100 according to Embodiment 3 will be described below.
  • the air-conditioning apparatus 100 according to Embodiment 3 plural relay units 17 are provided between the outdoor unit 3 and the plural indoor units 2 , and the shut-off valves 30 include relay-unit-side shut-off valves 30 c .
  • the air-conditioning apparatus 100 of Embodiment 3 is different in configuration from the air-conditioning apparatus 100 of Embodiment 1.
  • components that are the same as those in Embodiment 1 and/or Embodiment 2 will be denoted by the same reference signs, and their descriptions will thus be omitted.
  • FIG. 11 is a schematic view illustrating an example of a circuit configuration of the air-conditioning apparatus 100 of Embodiment 3.
  • the air-conditioning apparatus 100 of Embodiment 3 is a three-pipe air-conditioning apparatus 100 in which three pipes are provided as refrigerant pipes 10 between the outdoor unit 3 and relay units 17 a and 17 b .
  • the refrigerant pipes 10 between the outdoor unit 3 and the relay units 17 a and 17 b are a refrigerant-pipe communication part 10 a , a refrigerant-pipe communication part 10 b , and a refrigerant-pipe communication part 10 c . It should be noted that in FIG.
  • relay unit 17 a and the relay unit 17 b are each simply referred to as “relay unit 17 ” as appropriate when they do not particularly need to be distinguished from each other. Also, the following description is also made assuming that the term “relay unit 17 ” is applicable to both a single relay unit 17 and plural relay units 17 .
  • Outdoor-unit-side shut-off valves 30 b - 1 , 30 b - 2 , and 30 b - 3 are provided between the outdoor unit 3 and the relay units 17 a and 17 b .
  • the outdoor-unit-side shut-off valve 30 b - 1 is provided at the refrigerant-pipe communication part 10 a .
  • the outdoor-unit-side shut-off valve 30 b - 2 is provided at the refrigerant-pipe communication part 10 b .
  • the outdoor-unit-side shut-off valve 30 b - 3 is provided at the refrigerant-pipe communication part 10 c .
  • the outdoor-unit-side shut-off valves 30 b - 1 to 30 b - 3 are located closer to the outdoor unit 3 than to the relay unit 17 .
  • relay-unit-side shut-off valves 30 c - 1 , 30 c - 2 , 30 c - 3 , 30 c - 4 , 30 c - 5 , and 30 c - 6 are provided.
  • relay-unit-side shut-off valves 30 c - 1 to 30 c - 6 are simply referred to as “relay-unit-side shut-off valves 30 c ” as appropriate when they do not particularly need to be distinguished from each other, and the following description is also made assuming that the term “relay-unit-side shut-off valve 30 c ” is applicable to both a single relay-unit-side shut-off valve 30 c and plural relay-unit-side shut-off valves 30 c.
  • the relay-unit-side shut-off valves 30 c - 1 , 30 c - 2 , and 30 c - 3 are associated with the relay unit 17 a .
  • the relay-unit-side shut-off valves 30 c - 4 , 30 c - 5 , and 30 c - 6 are associated with the relay unit 17 b .
  • the relay-unit-side shut-off valve 30 c are each provided at the refrigerant pipe 10 connecting the outdoor unit 3 and the relay unit 17 , at a location close to an associated one of the relay units 17 . That is, the relay-unit-side shut-off valves 30 c - 1 to 30 c - 3 are located closer to the relay unit 17 a than to the outdoor unit 3 .
  • the relay-unit-side shut-off valves 30 c - 4 to 30 c - 6 are located closer to the relay unit 17 b than to the outdoor unit 3 .
  • the air-conditioning apparatus 100 includes plural indoor units 2 a , 2 b , 2 c , and 2 d .
  • the indoor unit 2 a , 2 b , 2 c , and 2 d are provided in spaces 1 a , 1 b , 1 c , and 1 d , respectively, which are air-conditioning target spaces.
  • Refrigerant leak detection devices 15 a , 15 b , 15 c , and 15 d are provided in the spaces 1 a , 1 b , 1 c , and 1 d , respectively, to detect a refrigerant leak.
  • the refrigerant leak detection devices 15 a to 15 d according to Embodiment 3 are the same as the refrigerant leak detection device 15 according to Embodiment 1, and their descriptions will thus be omitted.
  • the indoor units 2 a and 2 b are connected to the relay unit 17 a .
  • the indoor units 2 c and 2 d are connected to the relay unit 17 b .
  • the refrigerant pipe 10 between the indoor unit 2 a and the relay unit 17 a is provided with the indoor-unit-side shut-off valves 30 a - 1 and 30 a - 2 .
  • the indoor-unit-side shut-off valves 30 a - 3 and 30 a - 4 are provided.
  • the indoor-unit-side shut-off valves 30 a - 5 and 30 a - 6 are provided.
  • the indoor-unit-side shut-off valves 30 a - 7 and 30 a - 8 are provided.
  • the configurations of the shut-off valves 30 according to Embodiment 3 are the same as those according to Embodiment 1, and their descriptions will thus be omitted.
  • the air-conditioning apparatus 100 includes the relay-unit-side shut-off valves 30 c .
  • regions where the respective indoor units 2 are installed, regions where the respective relay units 17 are installed, regions located between the relay units 17 and the outdoor unit 3 , and a region where the outdoor unit 3 is located are isolated from each other as independent regions.
  • a detection value obtained by a pressure sensor connected to any one of the outdoor-unit-side shut-off valve 30 b - 1 , the relay-unit-side shut-off valve 30 c - 1 , and the relay-unit-side shut-off valve 30 c - 4 can be considered to be close to the atmospheric pressure. Therefore, it is possible to shorten the time required for checking to determine part of the refrigerant pipe 10 where the refrigerant leak occurs, by starting the checking from an area close to the shut-off valve 30 connected to the pressure sensor that obtains the detection value close to the atmospheric pressure. It is therefore possible to reduce the time required for the checking.
  • the device for drawing refrigerant connected to each of the outdoor-unit-side shut-off valve 30 b - 1 , the relay-unit-side shut-off valve 30 c - 1 , and the relay-unit-side shut-off valve 30 c - 4 to draw back refrigerant.
  • vacuum pumps are connected to the outdoor-unit-side shut-off valve 30 b - 1 , the relay-unit-side shut-off valve 30 c - 1 , and the relay-unit-side shut-off valve 30 c - 4 to enable simultaneous evacuation to be performed. It is therefore possible to reduce the time required for maintenance that is performed after refrigerant leaks from the air-conditioning apparatus 100 . Therefore, the maintainability of the air-conditioning apparatus 100 can be further improved.
  • the shut-off valves 30 according to Embodiment 3 include the plural indoor-unit-side shut-off valves 30 a , the plural outdoor-unit-side shut-off valves 30 b , and plural relay-unit-side shut-off valves 30 c . It is therefore possible to divide the inside of the air-conditioning apparatus 100 according to Embodiment 3 into a region where the indoor unit 2 a is installed, a region where the indoor unit 2 b is installed, a region where the indoor unit 2 c is installed, a region where the indoor unit 2 d is installed, a region where the relay unit 17 a is installed, a region where the relay unit 17 b is installed, and a region located between the outdoor unit 3 and the relay unit 17 .
  • each of the above regions can be subjected to maintenance as an independent region.
  • existing air-conditioning apparatuses including a relay unit since the total length of refrigerant pipes is great and the amount of refrigerant to be used is large, in some cases, it takes time to perform maintenance such as an operation to determine the location where a refrigerant leak occurs, an operation to draw back an operation to re-fill refrigerant, and an operation to evacuate refrigerant pipes.

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