WO2024079873A1 - 空気調和装置 - Google Patents

空気調和装置 Download PDF

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Publication number
WO2024079873A1
WO2024079873A1 PCT/JP2022/038333 JP2022038333W WO2024079873A1 WO 2024079873 A1 WO2024079873 A1 WO 2024079873A1 JP 2022038333 W JP2022038333 W JP 2022038333W WO 2024079873 A1 WO2024079873 A1 WO 2024079873A1
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WO
WIPO (PCT)
Prior art keywords
refrigerant
pipe
heat exchanger
outdoor
liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2022/038333
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English (en)
French (fr)
Japanese (ja)
Inventor
勇輝 水野
傑 鳩村
尚平 石村
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP2024551018A priority Critical patent/JP7802195B2/ja
Priority to PCT/JP2022/038333 priority patent/WO2024079873A1/ja
Priority to DE112022007906.1T priority patent/DE112022007906T5/de
Publication of WO2024079873A1 publication Critical patent/WO2024079873A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • 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
    • 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

Definitions

  • This disclosure relates to an air conditioning device having an accumulator.
  • Patent Document 1 discloses a three-pipe simultaneous heating and cooling operation system that controls the opening and closing or direction of a valve so that the refrigerant liquid that flows toward the accumulator during defrosting operation flows through the pipes that have been warmed during heating operation.
  • the air conditioning device of Patent Document 1 has the refrigerant liquid absorb the heat of the pipes that have been warmed by the high-temperature refrigerant gas during heating operation during defrosting operation, and evaporates the refrigerant, thereby preventing liquid from flowing back into the accumulator.
  • Patent Document 1 may be less effective at preventing liquid backflow if a large amount of frost forms and a long defrosting operation is required.
  • This disclosure has been made to solve the problems described above, and aims to provide an air conditioner in which liquid backflow during defrosting operation is continuously suppressed, even when a large amount of frost has formed and a long defrosting operation is required.
  • the air conditioning apparatus comprises an outdoor unit having a compressor for compressing a refrigerant, an accumulator for storing the refrigerant, and an outdoor heat exchanger for exchanging heat between the refrigerant and air, an indoor unit having an indoor heat exchanger for exchanging heat between the refrigerant and air, a relay unit for relaying or blocking the flow of refrigerant between the outdoor unit and the indoor unit, the outdoor unit and the relay unit being connected by a low-pressure gas main pipe through which gas refrigerant flows, a high-pressure gas main pipe through which gas refrigerant at a higher pressure than the gas refrigerant flowing in the low-pressure gas main pipe flows, and a liquid main pipe through which liquid refrigerant flows, and the relay unit and the indoor unit are connected by a gas main pipe through which gas refrigerant flows,
  • the relay unit connects the gas branch pipes to the high-pressure gas main pipe and the low-pressure gas main pipe, and includes a relay gas pipe having a high-pressure gas branch pipe connected to
  • the air conditioning apparatus of the present disclosure has a bypass valve provided in the bypass pipe. Therefore, in the air conditioning apparatus of the present disclosure, the bypass valve is opened during defrost operation, and the flow of refrigerant to the indoor unit is blocked, allowing high-temperature refrigerant to flow into the outdoor heat exchanger while refrigerant liquid is stored in the indoor unit.
  • the air conditioning apparatus of the present disclosure liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during heating operation. Therefore, the air conditioning apparatus of the present disclosure can continuously suppress liquid backflow to the accumulator during defrost operation.
  • FIG. 1 is a refrigerant circuit diagram of an air conditioning apparatus according to a first embodiment.
  • FIG. 2 is a hardware configuration diagram showing a configuration example of a control device according to the first embodiment.
  • FIG. 2 is a hardware configuration diagram showing a configuration example of a control device according to the first embodiment.
  • 1 is a functional block diagram showing an air conditioning apparatus according to a first embodiment.
  • FIG. 2 is a diagram for explaining a heating operation of the air conditioning apparatus according to the first embodiment.
  • FIG. 2 is a diagram for explaining the defrosting operation of the air conditioning apparatus according to the first embodiment.
  • FIG. 2 is a diagram for explaining cooling operation of the air conditioning apparatus according to the first embodiment.
  • FIG. 4 is a diagram for explaining the liquid withdrawal operation of the air conditioning apparatus according to the first embodiment.
  • FIG. 4 is a flowchart showing the operation of the control device for the air conditioning device according to the first embodiment. 4 is a flowchart showing the operation of the control device for the air conditioning device according to the first embodiment.
  • FIG. 6 is a refrigerant circuit diagram of an air conditioning apparatus according to a second embodiment.
  • FIG. 11 is a functional block diagram showing an air conditioning apparatus according to a second embodiment.
  • FIG. 11 is a diagram for explaining the heating operation of the air conditioning apparatus according to the second embodiment.
  • FIG. 11 is a diagram for explaining the defrosting operation of the air conditioning apparatus according to the second embodiment.
  • FIG. 11 is a diagram for explaining the cooling operation of an air-conditioning apparatus according to a second embodiment.
  • FIG. 11 is a diagram for explaining the liquid withdrawal operation of the air conditioning apparatus according to the second embodiment.
  • FIG. 11 is a refrigerant circuit diagram of an air conditioning apparatus according to embodiment 3.
  • FIG. 11 is a functional block diagram showing an air conditioning apparatus according to a third embodiment.
  • FIG. 11 is a diagram for explaining the heating operation of an air conditioning apparatus according to a third embodiment.
  • FIG. 11 is a diagram for explaining the defrosting operation of an air conditioning apparatus according to embodiment 3.
  • FIG. 11 is a refrigerant circuit diagram of an air conditioning apparatus according to embodiment 4.
  • FIG. 13 is a functional block diagram showing an air conditioning apparatus according to a fourth embodiment.
  • FIG. 13 is a diagram for explaining the heating operation of an air conditioning apparatus according to embodiment 4.
  • FIG. 11 is a diagram for explaining the liquid withdrawal operation of the air conditioning apparatus according to the second embodiment.
  • FIG. 11 is a refrigerant circuit diagram of an air conditioning apparatus according to embodiment 3.
  • FIG. 11 is a functional block diagram showing an air conditioning
  • FIG. 13 is a diagram for explaining the defrosting operation of an air conditioning apparatus according to embodiment 4.
  • FIG. 11 is a refrigerant circuit diagram of an air conditioning apparatus according to embodiment 5.
  • FIG. 13 is a diagram for explaining the heating operation of an air conditioning apparatus according to embodiment 5.
  • FIG. 13 is a diagram for explaining the defrosting operation of an air conditioning apparatus according to embodiment 5.
  • FIG. 13 is a diagram for explaining the cooling operation of an air-conditioning apparatus according to embodiment 5.
  • FIG. 13 is a diagram for explaining the liquid withdrawal operation of an air conditioning apparatus according to embodiment 5.
  • FIG. 13 is a refrigerant circuit diagram of an air conditioning apparatus according to embodiment 6.
  • FIG. 13 is a diagram for explaining the heating operation of an air conditioning apparatus according to a sixth embodiment.
  • FIG. 11 is a refrigerant circuit diagram of an air conditioning apparatus according to embodiment 5.
  • FIG. 13 is a diagram for explaining the heating operation of an air conditioning apparatus according to embodiment 5.
  • FIG. 13 is a diagram for explaining the defrosting operation
  • FIG. 13 is a diagram for explaining the defrosting operation of an air conditioning apparatus according to a sixth embodiment.
  • FIG. 13 is a diagram for explaining the cooling operation of an air conditioning apparatus according to a sixth embodiment.
  • FIG. 13 is a diagram for explaining the liquid withdrawal operation of an air conditioning apparatus according to a sixth embodiment.
  • FIG. 13 is a refrigerant circuit diagram of an air conditioning apparatus according to a seventh embodiment.
  • FIG. 13 is a diagram for explaining the heating operation of an air conditioning apparatus according to a seventh embodiment.
  • FIG. 13 is a diagram for explaining the defrosting operation of the air conditioning apparatus according to the seventh embodiment.
  • FIG. 13 is a refrigerant circuit diagram of an air conditioning apparatus according to an eighth embodiment.
  • FIG. 13 is a diagram for explaining the heating operation of an air conditioning apparatus according to an eighth embodiment.
  • FIG. 13 is a diagram for explaining the defrosting operation of an air conditioning apparatus according to an eighth embodiment.
  • Fig. 1 is a refrigerant circuit diagram of an air conditioner 1 pertaining to embodiment 1. As shown in Fig. 1, the air conditioner 1 has an outdoor unit 2, a relay unit 3, a first indoor unit 4a, and a second indoor unit 4b.
  • the outdoor unit 2 and the repeater unit 3 are connected by three pipes: a low-pressure gas main pipe 101, a high-pressure gas main pipe 102, and a liquid main pipe 103.
  • the low-pressure gas main pipe 101 is passed by gas refrigerant that flows out of the repeater unit 3 and flows into the outdoor unit 2 during cooling operation.
  • the high-pressure gas main pipe 102 is passed by gas refrigerant that flows out of the outdoor unit 2 and flows into the repeater unit 3 during heating operation.
  • the high-pressure gas main pipe 102 is passed by gas refrigerant with a higher pressure than the gas refrigerant that flows through the low-pressure gas main pipe 101.
  • the liquid main pipe 103 is passed by refrigerant that flows out of the repeater unit 3 and flows into the outdoor unit 2 during heating operation, and by refrigerant that flows out of the outdoor unit 2 and flows into the repeater unit 3 during cooling operation.
  • the low-pressure gas main pipe 101, the high-pressure gas main pipe 102, and the low-pressure liquid main pipe 103 branch off from the part that connects the outdoor unit 2 and the repeater unit 3.
  • the low pressure gas main pipe 101, the high pressure gas main pipe 102, and the liquid main pipe 103 may branch off and be connected to a relay unit other than the relay unit 3, or to an indoor unit.
  • the relay unit 3 and the first indoor unit 4a are connected by the first gas branch pipe 104a and the first liquid branch pipe 105a.
  • the relay unit 3 and the second indoor unit 4b are connected by the second gas branch pipe 104b and the second liquid branch pipe 105b.
  • Gas refrigerant flows through the first gas branch pipe 104a and the second gas branch pipe 104b.
  • Liquid refrigerant flows through the first liquid branch pipe 105a and the second liquid branch pipe 105b.
  • the outdoor unit 2 is a device that supplies hot or cold heat to the first indoor unit 4a and the second indoor unit 4b.
  • the outdoor unit 2 has outdoor piping 201-204, a suction pipe 206, and a discharge pipe 207.
  • the outdoor unit 2 includes a compressor 10, a heat exchanger side flow switching device 21, an outdoor heat exchanger 30, an outdoor expansion valve 40, and an accumulator 50.
  • the outdoor pipe 201 is a pipe that connects the heat exchange side flow path switching device 21 and the low pressure gas main pipe 101.
  • the outdoor pipe 202 is a pipe that connects the heat exchange side flow path switching device 21, the outdoor heat exchanger 30, the outdoor expansion valve 40, and the liquid main pipe 103.
  • the outdoor pipe 203 is a pipe that branches off from the outdoor pipe 201 and connects to the accumulator 50.
  • the outdoor pipe 204 is a pipe that connects the discharge pipe 207 and the high pressure gas main pipe 102.
  • the suction pipe 206 is a pipe that connects the accumulator 50 and the compressor 10.
  • the discharge pipe 207 is a pipe that connects the compressor 10 and the heat exchange side flow path switching device 21.
  • the compressor 10 sucks in a refrigerant in a low-temperature and low-pressure state, compresses the sucked refrigerant, and discharges it in a high-temperature and high-pressure state.
  • the heat exchange side flow path switching device 21 is, for example, a four-way valve. The heat exchange side flow path switching device 21 switches between a direction in which the outdoor heat exchanger 30 and the compressor 10 are connected and a direction in which the outdoor heat exchanger 30 and the accumulator 50 are connected. This switches the flow direction of the refrigerant in the refrigerant circuit.
  • the outdoor heat exchanger 30 exchanges heat between the refrigerant and the outdoor air.
  • the outdoor heat exchanger 30 acts as a condenser during cooling operation and as an evaporator during heating operation.
  • the outdoor expansion valve 40 reduces the pressure of the refrigerant and expands it, and is, for example, an electronic expansion valve with an adjustable opening.
  • the accumulator 50 is a device for storing surplus refrigerant circulating in the outdoor unit 2.
  • the relay unit 3 is a device that relays or blocks the refrigerant flowing between the outdoor unit 2 and the first and second indoor units 4a and 4b.
  • the relay unit 3 has a relay gas pipe 301, a relay liquid pipe 304, and a bypass pipe 305.
  • the relay unit 3 is equipped with a bypass valve 60, a first low pressure valve 71a, a second low pressure valve 71b, a first high pressure valve 72a, and a second high pressure valve 72b.
  • the relay gas pipe 301 connects the first gas branch pipe 104a and the second gas branch pipe 104b to the high pressure gas main pipe 102 and the low pressure gas main pipe 101.
  • the relay gas pipe 301 is a pipe that branches into a high pressure side and a low pressure side, and has a high pressure gas branch pipe 302 and a low pressure gas branch pipe 303.
  • the high pressure gas branch pipe 302 is a pipe that connects the branched portion of the relay gas pipe 301 to the high pressure gas main pipe 102.
  • the low pressure gas branch pipe 303 is a pipe that connects the branched portion of the relay gas pipe 301 to the low pressure gas main pipe 101.
  • the high pressure gas branch pipe 302 branches corresponding to the first indoor unit 4a and the second indoor unit 4b.
  • the low pressure gas branch pipe 303 branches corresponding to the first indoor unit 4a and the second indoor unit 4b.
  • the relay liquid pipe 304 branches out to correspond to the first indoor unit 4a and the second indoor unit 4b, and connects the main liquid pipe 103 to the first liquid branch pipe 105a and the second liquid branch pipe 105b.
  • the bypass pipe 305 connects the high-pressure gas branch pipe 302 to the relay liquid pipe 304.
  • the bypass valve 60 is provided in the bypass pipe 305 and has the function of switching between an open state that allows the flow of refrigerant through the bypass pipe 305 and a closed state that blocks the flow of refrigerant through the bypass pipe 305.
  • the first low pressure valve 71a is provided at a position corresponding to the first indoor unit 4a in the low pressure gas branch pipe 303 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the first low pressure valve 71a has a function of switching between an open state that allows the flow of refrigerant flowing through the region of the low pressure gas branch pipe 303 that corresponds to the first indoor unit 4a and a closed state that blocks the flow of refrigerant flowing through the region of the low pressure gas branch pipe 303 that corresponds to the first indoor unit 4a.
  • the second low pressure valve 71b is provided at a position corresponding to the second indoor unit 4b in the low pressure gas branch pipe 303 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the second low pressure valve 71b has a function of switching between an open state that allows the flow of refrigerant flowing through the region of the low pressure gas branch pipe 303 that corresponds to the second indoor unit 4b and a closed state that blocks the flow of refrigerant flowing through the region of the low pressure gas branch pipe 303 that corresponds to the second indoor unit 4b.
  • the first high pressure valve 72a is provided at a position corresponding to the first indoor unit 4a in the high pressure gas branch pipe 302 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the first high pressure valve 72a has a function of switching between an open state that allows the flow of refrigerant flowing through the area of the high pressure gas branch pipe 302 that corresponds to the first indoor unit 4a and a closed state that blocks the flow of refrigerant flowing through the area of the high pressure gas branch pipe 302 that corresponds to the first indoor unit 4a.
  • the second high pressure valve 72b is provided at a position corresponding to the second indoor unit 4b in the high pressure gas branch pipe 302 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the second high pressure valve 72b has a function of switching between an open state that allows the flow of refrigerant flowing through the area of the high pressure gas branch pipe 302 that corresponds to the second indoor unit 4b and a closed state that blocks the flow of refrigerant flowing through the area of the high pressure gas branch pipe 302 that corresponds to the second indoor unit 4b.
  • the bypass valve 60, the first low pressure valve 71a, the second low pressure valve 71b, the first high pressure valve 72a, and the second high pressure valve 72b are not limited in type as long as they have a mechanism that can switch between allowing and blocking the flow of refrigerant. Therefore, these valves may be, for example, opening/closing valves or expansion valves.
  • the first indoor unit 4a and the second indoor unit 4b are devices for supplying hot or cold heat to the room.
  • the first indoor unit 4a has a first indoor piping 401a.
  • the first indoor unit 4a is equipped with a first indoor heat exchanger 80a and a first indoor expansion valve 90a.
  • the second indoor unit 4b has a second indoor piping 401b.
  • the second indoor unit 4b is equipped with a second indoor heat exchanger 80b and a second indoor expansion valve 90b.
  • the first indoor piping 401a is a piping that connects the first gas branch pipe 104a, the first indoor heat exchanger 80a, the first indoor expansion valve 90a, and the first liquid branch pipe 105a.
  • the second indoor piping 401b is a piping that connects the second gas branch pipe 104b, the second indoor heat exchanger 80b, the second indoor expansion valve 90b, and the second liquid branch pipe 105b.
  • the first indoor heat exchanger 80a and the second indoor heat exchanger 80b exchange heat between the indoor air and the refrigerant.
  • the first indoor heat exchanger 80a and the second indoor heat exchanger 80b act as evaporators during cooling operation and as condensers during heating operation.
  • the first indoor expansion valve 90a and the second indoor expansion valve 90b reduce the pressure of the refrigerant to expand it, and are, for example, electronic expansion valves with adjustable opening.
  • the number of indoor units in the air conditioning device 1 is not limited to two, and may be one, three or more.
  • the indoor units and the configurations corresponding to the indoor units may be referred to as follows. That is, when the first indoor unit 4a and the second indoor unit 4b are not distinguished, they are referred to as the indoor unit 4.
  • the first gas branch pipe 104a and the second gas branch pipe 104b are not distinguished, they are referred to as the gas branch pipe 104.
  • the first liquid branch pipe 105a and the second liquid branch pipe 105b are not distinguished, they are referred to as the liquid branch pipe 105.
  • first low pressure valve 71a and the second low pressure valve 71b are not distinguished, they are referred to as the low pressure valve 71.
  • first high pressure valve 72a and the second high pressure valve 72b are not distinguished, they are referred to as the high pressure valve 72.
  • the indoor piping 401a and the second indoor piping 401b are not distinguished, they are referred to as the indoor piping 401.
  • the indoor heat exchanger 80a and the second indoor heat exchanger 80b are not differentiated from each other, they are referred to as the indoor heat exchanger 80.
  • the indoor expansion valve 90a and the second indoor expansion valve 90b are not differentiated from each other, they are referred to as the indoor expansion valve 90.
  • the air conditioning apparatus 1 has a control device 5 that controls each device of the outdoor unit 2, relay unit 3, and indoor unit 4.
  • the control device 5 controls switching between various operation modes and the execution of each operation mode.
  • the operation modes executed by the air conditioning apparatus 1 of embodiment 1 include heating operation, defrost operation, cooling operation, and liquid drainage operation.
  • the user is instructed to execute the heating operation and cooling operation using a remote control (not shown) or the like.
  • the defrost operation is an operation mode for removing frost that has formed on the outdoor heat exchanger 30 during heating operation.
  • the liquid drainage operation is an operation mode for draining liquid that has accumulated in the high-pressure gas main pipe 102 during cooling operation.
  • FIG. 2 is a hardware configuration diagram showing an example of the configuration of the control device 5 according to the first embodiment.
  • the control device 5 is configured by a processing circuit 501 as shown in FIG. 2.
  • the processing circuit 501 is, for example, a single circuit, a composite circuit, a programmed processor 502, a parallel programmed processor 502, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these.
  • Each function realized by the processing circuit 501 may be realized by separate hardware, or each function may be realized by a single piece of hardware.
  • FIG. 3 is a hardware configuration diagram showing an example of the configuration of the control device 5 according to the first embodiment.
  • the control device 5 is composed of a processor 502 such as a CPU and a memory 503 as shown in FIG. 3.
  • FIG. 3 shows that the processor 502 and the memory 503 are communicatively connected to each other via a bus 504.
  • Each function of the control device 5 is realized by software, firmware, or a combination of software and firmware.
  • the software and firmware are written as programs and stored in the memory 503.
  • the processor 502 realizes the functions of each means by reading and executing the programs stored in the memory 503.
  • a non-volatile semiconductor memory such as a ROM (Read Only Memory), a flash memory, an EPROM (Erasable and Programmable ROM), and an EEPROM (Electrically Erasable and Programmable ROM) may be used.
  • a volatile semiconductor memory such as a RAM (Random Access Memory) may be used as the memory 503.
  • a removable recording medium such as a magnetic disk, a flexible disk, an optical disk, a CD (Compact Disc), an MD (Mini Disc), and a DVD (Digital Versatile Disc) may be used as the memory 503.
  • some of the functions of the processing circuit 501 may be realized by dedicated hardware, and some by software or firmware.
  • FIG. 4 is a functional block diagram showing the air conditioning apparatus 1 according to the first embodiment.
  • the control device 5 controls the compressor 10, the heat exchanger side flow switching device 21, and the outdoor expansion valve 40 of the outdoor unit 2 according to the operation mode.
  • the control device 5 also controls the bypass valve 60, the low pressure valve 71, and the high pressure valve 72 of the relay unit 3 according to the operation mode.
  • the control device 5 controls the first indoor expansion valve 90a of the indoor unit 4 according to the operation mode.
  • the control device 5 controls the execution of the defrost operation and the liquid drain operation based on the measurement results of the frost detection device 6, the defrost detection device 7, and the liquid pool detection device 8.
  • the frost detection device 6 is a sensor for detecting frost on the outdoor heat exchanger 30, and is, for example, a pressure sensor.
  • the frost detection device 6 is not particularly limited, but is, for example, placed in the piping between the outdoor heat exchanger 30 and the compressor 10.
  • the frost detection device 6 transmits the measurement results to the control device 5.
  • the control device 5 determines, based on the measurement results of the frost detection device 27, that frost has occurred in the outdoor heat exchanger 23 to the extent that defrosting is required, it transitions the operation mode from heating operation to defrost operation.
  • the control device 5 determines that frost has occurred in the outdoor heat exchanger 23 to the extent that defrosting is required.
  • the defrost detection means is a sensor for detecting defrost from the outdoor heat exchanger 30, and is, for example, a temperature sensor.
  • the defrost detection device 7 is disposed in the piping between the outdoor heat exchanger 30 and the compressor 10. The defrost detection device 7 transmits the measurement result to the control device 5.
  • the control device 5 determines that the defrosting of the outdoor heat exchanger 23 is completed based on the measurement result of the defrost detection device 28, it transitions the operation mode from the defrosting operation to the heating operation. For example, when the refrigerant temperature measured by the defrost detection device 28 exceeds a predetermined threshold, the control device 5 determines that the defrosting of the outdoor heat exchanger 23 is completed.
  • the liquid pool detection device 8 is a sensor or timer for detecting the occurrence and elimination of liquid pools in the high-pressure gas main pipe 102, and is, for example, a temperature sensor, a pressure sensor, or an integrating timer, or a combination of these.
  • Liquid pools are caused by the condensation of gas refrigerant that accumulates in the high-pressure gas main pipe 102 during cooling operation.
  • This gas refrigerant has a pressure equivalent to the discharge pressure of the compressor 10, and the saturated gas temperature is higher than the ambient air temperature, so it gradually condenses as the cooling operation continues.
  • the occurrence of liquid pools during cooling operation can cause a shortage of refrigerant.
  • the liquid pool detection device 8 is not particularly limited, but is, for example, placed in the high-pressure gas main pipe 102.
  • the liquid pool detection device 8 transmits the measurement results to the control device 5.
  • the control device 5 determines that a liquid pool that needs to be eliminated has occurred in the high-pressure gas main pipe 102 based on the measurement results of the liquid pool detection device 8, it transitions the operation mode from cooling operation to liquid drainage operation. For example, if the refrigerant temperature and pressure measured by the liquid pool detection device 8 are not within the range of a predetermined threshold, the control device 5 determines that a liquid pool that needs to be eliminated has occurred in the high-pressure gas main pipe 102. Furthermore, if the control device 5 determines that the elimination of the liquid pool in the high-pressure gas main pipe 102 has been completed based on the measurement results of the liquid pool detection device 8, it transitions the operation mode from liquid drainage operation to cooling operation. For example, the control device 5 determines that the liquid pool in the high-pressure gas main pipe 102 has been eliminated if the duration of the liquid drainage operation measured by the integrating timer exceeds the range of a predetermined threshold.
  • FIG. 5 is a diagram for explaining the heating operation of the air conditioning device 1 according to embodiment 1.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also closes the bypass valve 60, closes the low pressure valve 71, and opens the high pressure valve 72.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the high-pressure gas branch pipe 302, which is provided with the high-pressure valve 72, and the gas branch pipe 104 and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 passes through the indoor heat exchanger 80, which acts as a condenser.
  • the refrigerant that passes through the indoor heat exchanger 80 exchanges heat with the indoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the indoor expansion valve 90, is decompressed and expanded, and becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant.
  • the gas-liquid two-phase refrigerant passes through the liquid branch pipe 105, the relay liquid pipe 304, and the liquid main pipe 103 and flows into the outdoor unit 2.
  • the refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40, where it is further decompressed and expanded, and passes through the outdoor heat exchanger 30, which acts as an evaporator.
  • the refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the outdoor air, evaporates, and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the heat exchanger side flow switching device 21 and the accumulator 50, and is sucked back into the compressor 10 and circulated.
  • FIG. 6 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1 according to the first embodiment.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow path switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also opens the bypass valve 60, closes the low pressure valve 71, and opens the high pressure valve 72.
  • the control device 5 closes the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302, the bypass pipe 305 with the bypass valve 60, a part of the relay liquid pipe 304, and the liquid main pipe 103, and flows back into the outdoor unit 2.
  • the high-temperature, high-pressure gas refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40 and the outdoor heat exchanger 30, which acts as an evaporator.
  • the high-temperature, low-pressure gas refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the frost attached to the outdoor heat exchanger 30, condenses, and becomes a low-temperature, low-pressure gas state.
  • the outdoor heat exchanger 30 is defrosted.
  • the low-temperature, low-pressure gaseous refrigerant passes through the heat exchanger-side flow switching device 21 and the accumulator 50, and is again sucked into the compressor 10 and circulated.
  • the low-pressure valve 71 is closed, and the indoor expansion valve 90 is also closed. This blocks the flow of refrigerant to the indoor unit 4, and the liquid refrigerant is stored in the indoor unit 4.
  • FIG. 7 is a diagram for explaining the cooling operation of the air conditioning apparatus 1 according to embodiment 1.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the compressor 10 and the outdoor heat exchanger 30.
  • the control device 5 also closes the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the heat exchange side flow switching device 21 and passes through the outdoor heat exchanger 30.
  • the refrigerant passing through the outdoor heat exchanger 30 exchanges heat with the outdoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the outdoor expansion valve 40 and is reduced in pressure and expanded.
  • the liquid state refrigerant passes through the liquid main pipe 103 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the relay liquid pipe 304 and the liquid branch pipe 105 and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 is further reduced in pressure and expanded by the indoor expansion valve 90, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant.
  • the low-temperature, low-pressure, two-phase gas-liquid refrigerant passes through the indoor heat exchanger 80, exchanges heat with the indoor air, evaporates, and gasifies. At this time, the indoor air is cooled, and cooling is performed in the room.
  • the gaseous refrigerant passes through the gas branch pipe 104 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the low-pressure gas branch pipe 303, which is provided with the low-pressure valve 71 of the relay gas pipe 301, and the low-pressure gas main pipe 101, and flows into the outdoor unit 2.
  • the refrigerant that flows into the outdoor unit 2 passes through the accumulator 50 and is sucked into the compressor 10 again, and circulates.
  • FIG 8 is a diagram for explaining the liquid drainage operation of the air conditioning apparatus 1 according to embodiment 1.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the compressor 10 and the outdoor heat exchanger 30.
  • the control device 5 also opens the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • a main circuit and a bypass circuit are formed.
  • the refrigerant flows in the same manner as in cooling operation.
  • the bypass circuit the high-temperature and high-pressure gas-state refrigerant discharged from the compressor 10 passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302 and the bypass pipe 305 in which the bypass valve 60 is provided, flows into the relay liquid pipe 304, and merges into the main circuit.
  • the liquid refrigerant that has accumulated in the high-pressure gas main pipe 102 is released and merges into the main circuit.
  • FIGS 9 and 10 are flowcharts showing the operation of the control device 5 of the air conditioning device 1 according to embodiment 1.
  • the control device 5 determines whether or not defrosting of the outdoor heat exchanger 30 is necessary based on the measurement results of the frost detection device 6 (step S1). If it is determined that defrosting of the outdoor heat exchanger 30 is not necessary (step S1: NO), the process of step S1 is repeated until it is determined that defrosting of the outdoor heat exchanger 30 is necessary. If it is determined that defrosting of the outdoor heat exchanger 30 is necessary (step S1: YES), the operation mode is transitioned from heating operation to defrosting operation (step S2).
  • step S3 determines whether or not the defrosting of the outdoor heat exchanger 30 has been completed based on the measurement results of the defrosting detection device 7 (step S3). If it is determined that the defrosting of the outdoor heat exchanger 30 has not been completed (step S3: NO), the process of step S3 is repeated until it is determined that the defrosting of the outdoor heat exchanger 30 has been completed. If it is determined that the defrosting of the outdoor heat exchanger 30 has been completed (step S3: YES), the operation mode is transitioned from the defrosting operation to the heating operation (step S4).
  • step S11 determines whether or not it is necessary to remove the liquid pool in the high-pressure gas main pipe 102 based on the measurement results of the liquid pool detection device 8 (step S11). If it is determined that it is not necessary to remove the liquid pool in the high-pressure gas main pipe 102 (step S11: NO), the process of step S11 is repeated until it is determined that it is necessary to remove the liquid pool in the high-pressure gas main pipe 102. If it is determined that it is necessary to remove the liquid pool in the high-pressure gas main pipe 102 (step S11: YES), the operation mode is transitioned from cooling operation to liquid drainage operation (step S12).
  • the control device 5 determines whether or not the liquid pool in the high-pressure gas main pipe 102 has been cleared based on the measurement results of the liquid pool detection device 8 (step S13). If it is determined that the liquid pool in the high-pressure gas main pipe 102 has not been cleared (step S13: NO), the process of step S13 is repeated until it is determined that the liquid pool in the high-pressure gas main pipe 102 has been cleared. If it is determined that the liquid pool in the high-pressure gas main pipe 102 has been cleared (step S13: YES), the operation mode is transitioned from the liquid drainage operation to the cooling operation (step S14).
  • the bypass valve 60 is provided in the bypass pipe 305. Therefore, in the air conditioning device 1 of the first embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4.
  • the air conditioning device 1 of the first embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • Embodiment 2 is a refrigerant circuit diagram of an air conditioning apparatus 1A according to embodiment 2. As shown in Fig. 11, embodiment 2 differs from embodiment 1 in that the outdoor unit 2 has a high-pressure pipe side flow switching device 22. In embodiment 2, the same parts as those in embodiment 1 are given the same reference numerals and their explanations are omitted, and the explanation will focus on the differences from embodiment 1.
  • the outdoor unit 2 further has an outdoor pipe 205.
  • the outdoor unit 2 also has a high-pressure pipe side flow path switching device 22.
  • the outdoor pipe 205 connects the high-pressure pipe side flow path switching device 22 and the outdoor pipe 201.
  • the high-pressure pipe side flow path switching device 22 is provided on the outdoor pipe 204.
  • the high-pressure pipe side flow path switching device 22 switches between a direction in which the high-pressure gas main pipe 102 and the compressor 10 are connected and a direction in which the high-pressure gas main pipe 102 and the accumulator 50 are connected.
  • FIG. 12 is a functional block diagram showing an air conditioning apparatus 1A according to embodiment 2.
  • the control device 5 controls the compressor 10, heat exchanger side flow path switching device 21, high pressure pipe side flow path switching device 22, and outdoor expansion valve 40 of the outdoor unit 2 according to the operation mode.
  • the control device 5 also controls the bypass valve 60, low pressure valve 71, and high pressure valve 72 of the relay unit 3 according to the operation mode.
  • the control device 5 controls the first indoor expansion valve 90a of the indoor unit 4 according to the operation mode.
  • FIG. 13 is a diagram for explaining the heating operation of the air conditioning apparatus 1A according to the second embodiment.
  • the arrows indicate the direction of the refrigerant flow.
  • the control device 5 switches the heat exchange side flow switching device 21 to a direction connecting the outdoor heat exchanger 30 and the accumulator 50, and switches the high pressure pipe side flow switching device 22 to a direction connecting the compressor 10 and the high pressure gas main pipe 102.
  • the control device 5 closes the bypass valve 60, closes the low pressure valve 71, and opens the high pressure valve 72.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the high-pressure pipe side flow switching device 22, passes through the high-pressure gas main pipe 102, and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the high-pressure gas branch pipe 302, which is provided with a high-pressure valve 72, and the gas branch pipe 104, and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 passes through the indoor heat exchanger 80, which acts as a condenser.
  • the refrigerant that passes through the indoor heat exchanger 80 exchanges heat with the indoor air, condenses, and liquefies. At this time, the indoor air is warmed, and heating is performed in the room.
  • the liquid state refrigerant passes through the indoor expansion valve 90, is decompressed and expanded, and becomes a low-temperature, low-pressure two-phase gas-liquid refrigerant.
  • the refrigerant in a gas-liquid two-phase state passes through the liquid branch pipe 105, the relay liquid pipe 304, and the main liquid pipe 103, and flows into the outdoor unit 2.
  • the refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40, is further decompressed and expanded, and passes through the outdoor heat exchanger 30, which acts as an evaporator.
  • the refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the outdoor air, evaporates, and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the heat exchanger side flow switching device 21 and the accumulator 50, and is sucked back into the compressor 10 and circulates.
  • FIG 14 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1A according to the second embodiment.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the outdoor heat exchanger 30 and the accumulator 50, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the compressor 10 and the high-pressure gas main pipe 102.
  • the control device 5 also opens the bypass valve 60, closes the low-pressure valve 71, and opens the high-pressure valve 72. Furthermore, the control device 5 closes the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 passes through the high-pressure pipe side flow switching device 22, passes through the high-pressure gas main pipe 102, and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302, the bypass pipe 305 with the bypass valve 60, a part of the relay liquid pipe 304, and the liquid main pipe 103, and flows again into the outdoor unit 2.
  • the high-temperature, high-pressure gas refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40 and the outdoor heat exchanger 30 that acts as an evaporator.
  • the high-temperature, low-pressure gas refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the frost attached to the outdoor heat exchanger 30, condenses, and becomes a low-temperature, low-pressure gas state.
  • the outdoor heat exchanger 30 is defrosted.
  • the low-temperature, low-pressure gaseous refrigerant passes through the heat exchanger-side flow switching device 21 and the accumulator 50, and is again sucked into the compressor 10 and circulated.
  • the low-pressure valve 71 is closed, and the indoor expansion valve 90 is also closed. This blocks the flow of refrigerant to the indoor unit 4, and the liquid refrigerant is stored in the indoor unit 4.
  • FIG. 15 is a diagram for explaining the cooling operation of the air conditioning apparatus 1A according to the second embodiment.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the compressor 10 and the outdoor heat exchanger 30, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the accumulator 50 and the high-pressure gas main pipe 102.
  • the control device 5 also closes the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the heat exchange side flow switching device 21 and passes through the outdoor heat exchanger 30.
  • the refrigerant passing through the outdoor heat exchanger 30 exchanges heat with the outdoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the outdoor expansion valve 40 and is reduced in pressure and expanded.
  • the liquid state refrigerant passes through the liquid main pipe 103 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the relay liquid pipe 304 and the liquid branch pipe 105 and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 is further reduced in pressure and expanded by the indoor expansion valve 90, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant.
  • the low-temperature, low-pressure, two-phase gas-liquid refrigerant passes through the indoor heat exchanger 80, exchanges heat with the indoor air, evaporates, and gasifies. At this time, the indoor air is cooled, and cooling is performed in the room.
  • the gaseous refrigerant passes through the gas branch pipe 104 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the low-pressure gas branch pipe 303, which is provided with the low-pressure valve 71 of the relay gas pipe 301, and the low-pressure gas main pipe 101, and flows into the outdoor unit 2.
  • the refrigerant that flows into the outdoor unit 2 passes through the accumulator 50 and is sucked into the compressor 10 again, and circulates.
  • FIG 16 is a diagram for explaining the liquid drainage operation of the air conditioning apparatus 1A according to the second embodiment.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the compressor 10 and the outdoor heat exchanger 30, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the accumulator 50 and the high-pressure gas main pipe 102.
  • the control device 5 also opens the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • a main circuit and a bypass circuit are formed.
  • the refrigerant flows in the same manner as in cooling operation.
  • the bypass circuit the high-temperature and high-pressure gas-state refrigerant discharged from the compressor 10 passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302 and the bypass pipe 305 in which the bypass valve 60 is provided, flows into the relay liquid pipe 304, and merges into the main circuit.
  • the liquid refrigerant that has accumulated in the high-pressure gas main pipe 102 is released and merges into the main circuit.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the first embodiment. Therefore, in the air conditioning device 1A of the second embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1A of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1A of the second embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • Embodiment 3 is a refrigerant circuit diagram of an air conditioning apparatus 1B according to embodiment 3. As shown in Fig. 17, embodiment 3 differs from embodiment 1 in that the relay unit 3 has a first medium pressure valve 73a and a second medium pressure valve 73b. In embodiment 3, the same parts as those in embodiment 1 are given the same reference numerals and their explanations are omitted, and the explanation will focus on the differences from embodiment 1.
  • the relay unit 3 has a first medium pressure valve 73a and a second medium pressure valve 73b.
  • the first medium pressure valve 73a and the second medium pressure valve 73b are provided between the connection part of the relay liquid pipe 304 with the bypass pipe 305 and the connection part of the liquid branch pipe 105.
  • the first medium pressure valve 73a is provided at a position corresponding to the first indoor unit 4a in the relay liquid pipe 304 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the first medium pressure valve 73a has a function of switching between an open state that allows the flow of refrigerant flowing through the area of the relay liquid pipe 304 that corresponds to the first indoor unit 4a, and a closed state that blocks the flow of refrigerant flowing through the area of the relay liquid pipe 304 that corresponds to the first indoor unit 4a.
  • the second medium pressure valve 73b is provided at a position corresponding to the second indoor unit 4b in the relay liquid pipe 304 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the second medium pressure valve 73b has a function of switching between an open state that allows the flow of refrigerant through the area of the relay liquid pipe 304 corresponding to the second indoor unit 4b, and a closed state that blocks the flow of refrigerant through the area of the relay liquid pipe 304 corresponding to the second indoor unit 4b.
  • the first medium pressure valve 73a and the second medium pressure valve 73b are not distinguished, they may be referred to as medium pressure valves 73.
  • the type of medium pressure valve 73 is not limited as long as it has a mechanism that can switch between allowing and blocking the flow of refrigerant. Therefore, the medium pressure valve 73 may be, for example, an opening/closing valve or an expansion valve.
  • FIG. 18 is a functional block diagram showing an air conditioning apparatus 1B according to embodiment 3.
  • the control device 5 controls the compressor 10, heat exchanger side flow switching device 21, and outdoor expansion valve 40 of the outdoor unit 2 according to the operation mode.
  • the control device 5 also controls the bypass valve 60, low pressure valve 71, high pressure valve 72, and medium pressure valve 73 of the relay unit 3 according to the operation mode.
  • the control device 5 controls the first indoor expansion valve 90a of the indoor unit 4 according to the operation mode.
  • FIG. 19 is a diagram for explaining the heating operation of the air conditioning device 1B according to the third embodiment.
  • the arrows indicate the direction of the refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 closes the bypass valve 60, closes the low pressure valve 71, opens the high pressure valve 72, and opens the medium pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the high-pressure gas branch pipe 302, which is provided with a high-pressure valve 72, and the gas branch pipe 104 and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 passes through the indoor heat exchanger 80, which acts as a condenser.
  • the refrigerant that passes through the indoor heat exchanger 80 exchanges heat with the indoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the indoor expansion valve 90, is decompressed and expanded, and becomes a low-temperature, low-pressure, two-phase gas-liquid refrigerant.
  • the refrigerant in a gas-liquid two-phase state passes through the liquid branch pipe 105, the relay liquid pipe 304 with the medium pressure valve 73, and the main liquid pipe 103, and flows into the outdoor unit 2.
  • the refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40, is further decompressed and expanded, and passes through the outdoor heat exchanger 30 that acts as an evaporator.
  • the refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the outdoor air and evaporates and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the heat exchanger side flow switching device 21 and the accumulator 50, is sucked back into the compressor 10, and circulates.
  • FIG 20 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1B according to embodiment 3.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow path switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also opens the bypass valve 60, closes the low pressure valve 71, opens the high pressure valve 72, and closes the medium pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and opens the outdoor expansion valve 40. Note that the indoor expansion valve 90 may be closed.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302, the bypass pipe 305 with the bypass valve 60, a part of the relay liquid pipe 304, and the liquid main pipe 103, and flows back into the outdoor unit 2.
  • the high-temperature, high-pressure gas refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40 and the outdoor heat exchanger 30, which acts as an evaporator.
  • the high-temperature, low-pressure gas refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the frost attached to the outdoor heat exchanger 30, condenses, and becomes a low-temperature, low-pressure gas state.
  • the outdoor heat exchanger 30 is defrosted.
  • the low-temperature, low-pressure gaseous refrigerant passes through the heat exchanger-side flow switching device 21 and the accumulator 50, and is again sucked into the compressor 10 and circulated.
  • the low-pressure valve 71 is closed, and the indoor expansion valve 90 is also closed. This blocks the flow of refrigerant to the indoor unit 4, and the liquid refrigerant is stored in the indoor unit 4.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the first embodiment. Therefore, in the air conditioning device 1B of the third embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1B of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1B of the third embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • Embodiment 4 is a refrigerant circuit diagram of an air conditioning apparatus 1C according to embodiment 4. As shown in Fig. 21, embodiment 4 differs from embodiment 1 in that the outdoor unit 2 has a high-pressure pipe side flow path switching device 22 and the relay unit 3 has a first intermediate pressure valve 73a and a second intermediate pressure valve 73b. In other words, embodiment 4 corresponds to a combination of embodiment 2 and embodiment 3. In embodiment 4, the same parts as in embodiment 1 are given the same reference numerals and their description is omitted, and the differences from embodiment 1 will be mainly described.
  • the outdoor unit 2 further has an outdoor pipe 205.
  • the outdoor unit 2 also has a high-pressure pipe side flow path switching device 22.
  • the outdoor pipe 205 connects the high-pressure pipe side flow path switching device 22 and the outdoor pipe 201.
  • the high-pressure pipe side flow path switching device 22 is provided on the outdoor pipe 204.
  • the high-pressure pipe side flow path switching device 22 switches between a direction in which the high-pressure gas main pipe 102 and the compressor 10 are connected and a direction in which the high-pressure gas main pipe 102 and the accumulator 50 are connected.
  • the relay unit 3 has a first medium pressure valve 73a and a second medium pressure valve 73b.
  • the first medium pressure valve 73a and the second medium pressure valve 73b are provided between the connection part of the relay liquid pipe 304 with the bypass pipe 305 and the connection part of the liquid branch pipe 105.
  • the first medium pressure valve 73a is provided at a position corresponding to the first indoor unit 4a in the relay liquid pipe 304 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the first medium pressure valve 73a has a function of switching between an open state that allows the flow of refrigerant flowing through the area of the relay liquid pipe 304 that corresponds to the first indoor unit 4a, and a closed state that blocks the flow of refrigerant flowing through the area of the relay liquid pipe 304 that corresponds to the first indoor unit 4a.
  • the second medium pressure valve 73b is provided at a position corresponding to the second indoor unit 4b in the relay liquid pipe 304 that branches into the first indoor unit 4a and the second indoor unit 4b.
  • the second medium pressure valve 73b has a function of switching between an open state that allows the flow of refrigerant through the area of the relay liquid pipe 304 corresponding to the second indoor unit 4b, and a closed state that blocks the flow of refrigerant through the area of the relay liquid pipe 304 corresponding to the second indoor unit 4b.
  • the first medium pressure valve 73a and the second medium pressure valve 73b are not distinguished, they may be referred to as medium pressure valves 73.
  • the type of medium pressure valve 73 is not limited as long as it has a mechanism that can switch between allowing and blocking the flow of refrigerant. Therefore, the medium pressure valve 73 may be, for example, an opening/closing valve or an expansion valve.
  • FIG. 22 is a functional block diagram showing an air conditioning apparatus 1C according to embodiment 4.
  • the control device 5 controls the compressor 10, heat exchanger side flow switching device 21, high pressure pipe side flow switching device 22, and outdoor expansion valve 40 of the outdoor unit 2 according to the operation mode.
  • the control device 5 also controls the bypass valve 60, low pressure valve 71, high pressure valve 72, and medium pressure valve 73 of the relay unit 3 according to the operation mode.
  • the control device 5 controls the first indoor expansion valve 90a of the indoor unit 4 according to the operation mode.
  • FIG. 23 is a diagram for explaining the heating operation of the air conditioning device 1C according to the fourth embodiment.
  • the arrows indicate the direction of the refrigerant flow.
  • the control device 5 switches the heat exchange side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50, and switches the high pressure pipe side flow switching device 22 to a direction that connects the compressor 10 and the high pressure gas main pipe 102.
  • the control device 5 closes the bypass valve 60, closes the low pressure valve 71, opens the high pressure valve 72, and opens the medium pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the compressor 10 passes through the high-pressure pipe side flow switching device 22, passes through the high-pressure gas main pipe 102, and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the high-pressure gas branch pipe 302, which is provided with a high-pressure valve 72, and the gas branch pipe 104, and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 passes through the indoor heat exchanger 80, which acts as a condenser.
  • the refrigerant that passes through the indoor heat exchanger 80 exchanges heat with the indoor air, condenses, and liquefies. At this time, the indoor air is warmed, and heating is performed in the room.
  • the liquid state refrigerant passes through the indoor expansion valve 90, is decompressed and expanded, and becomes a low-temperature, low-pressure two-phase gas-liquid refrigerant.
  • the refrigerant in a gas-liquid two-phase state passes through the liquid branch pipe 105, the relay liquid pipe 304 with the medium pressure valve 73, and the main liquid pipe 103, and flows into the outdoor unit 2.
  • the refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40, is further decompressed and expanded, and passes through the outdoor heat exchanger 30 that acts as an evaporator.
  • the refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the outdoor air and evaporates and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the heat exchanger side flow switching device 21 and the accumulator 50, is sucked back into the compressor 10, and circulates.
  • FIG 24 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1C according to the fourth embodiment.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the outdoor heat exchanger 30 and the accumulator 50, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the compressor 10 and the high-pressure gas main pipe 102.
  • the control device 5 opens the bypass valve 60, closes the low-pressure valve 71, opens the high-pressure valve 72, and closes the medium-pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • the indoor expansion valve 90 may be closed.
  • the refrigerant sucked into the compressor 10 is compressed by the compressor 10 and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas refrigerant discharged from the compressor 10 passes through the high-pressure pipe side flow switching device 22, passes through the high-pressure gas main pipe 102, and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302, the bypass pipe 305 with the bypass valve 60, a part of the relay liquid pipe 304, and the liquid main pipe 103, and flows again into the outdoor unit 2.
  • the high-temperature, high-pressure gas refrigerant that flows into the outdoor unit 2 passes through the outdoor expansion valve 40 and the outdoor heat exchanger 30 that acts as an evaporator.
  • the high-temperature, low-pressure gas refrigerant that passes through the outdoor heat exchanger 30 exchanges heat with the frost attached to the outdoor heat exchanger 30, condenses, and becomes a low-temperature, low-pressure gas state.
  • the outdoor heat exchanger 30 is defrosted.
  • the low-temperature, low-pressure gaseous refrigerant passes through the heat exchanger-side flow switching device 21 and the accumulator 50, and is again sucked into the compressor 10 and circulated.
  • the low-pressure valve 71 is closed, and the medium-pressure valve 73 is also closed. This blocks the flow of refrigerant to the indoor unit 4, and the liquid refrigerant is stored in the indoor unit 4.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the first embodiment. Therefore, in the air conditioning device 1C of the fourth embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1C of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1C of the fourth embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • FIG. 25 is a refrigerant circuit diagram of an air conditioning apparatus 1D pertaining to embodiment 5. As shown in Fig. 25, embodiment 5 differs from embodiment 1 in that it has a first outdoor unit 2a and a second outdoor unit 2b. In embodiment 5, the same parts as in embodiment 1 are given the same reference numerals and their explanations are omitted, and the explanation will focus on the differences from embodiment 1.
  • the first outdoor unit 2a and the second outdoor unit 2b have the same configuration as the outdoor unit 2 described in the first embodiment. That is, the first outdoor unit 2a includes a first compressor 10a, a first heat exchange side flow switching device 21a, a first outdoor heat exchanger 30a, a first outdoor expansion valve 40a, and a first accumulator 50a.
  • the first compressor 10a draws in a refrigerant in a low temperature and low pressure state, compresses the drawn refrigerant, and discharges it in a high temperature and high pressure state.
  • the first heat exchange side flow switching device 21a is, for example, a four-way valve.
  • the first heat exchange side flow switching device 21a switches between a direction in which the first outdoor heat exchanger 30a and the first compressor 10a are connected and a direction in which the first outdoor heat exchanger 30a and the first accumulator 50a are connected. This switches the flow direction of the refrigerant in the refrigerant circuit.
  • the first outdoor heat exchanger 30a exchanges heat between the refrigerant and the outdoor air.
  • the first outdoor expansion valve 40a reduces the pressure of the refrigerant to expand it, and is, for example, an electronic expansion valve with an adjustable opening.
  • the first accumulator 50a is a device for storing excess refrigerant circulating through the first outdoor unit 2a.
  • the second outdoor unit 2b includes a second compressor 10b, a second heat exchange side flow switching device 21b, a second outdoor heat exchanger 30b, a second outdoor expansion valve 40b, and a second accumulator 50b.
  • the second compressor 10b draws in a refrigerant in a low-temperature and low-pressure state, compresses the drawn-in refrigerant, and discharges it in a high-temperature and high-pressure state.
  • the second heat exchange side flow switching device 21b is, for example, a four-way valve.
  • the second heat exchange side flow switching device 21b switches between a direction in which the second outdoor heat exchanger 30b and the second compressor 10b are connected and a direction in which the second outdoor heat exchanger 30b and the second accumulator 50b are connected. This switches the flow direction of the refrigerant in the refrigerant circuit.
  • the second outdoor heat exchanger 30b exchanges heat between the refrigerant and the outdoor air.
  • the second outdoor expansion valve 40b reduces the pressure of the refrigerant to expand it, and is, for example, an electronic expansion valve with an adjustable opening.
  • the second accumulator 50b is a device for storing excess refrigerant circulating through the second outdoor unit 2b.
  • the outdoor units 2 in the air conditioning apparatus 1D are not limited to one or two, and may be three or more.
  • they when the outdoor units and the configurations corresponding to the outdoor units are not particularly distinguished, they may be referred to as in the same manner as in embodiment 1 as follows. That is, when the first outdoor unit 2a and the second outdoor unit 2b are not distinguished, they are referred to as the outdoor units 2.
  • the first compressor 10a and the second compressor 10b are not distinguished, they are referred to as the compressors 10.
  • the first heat exchanger side flow path switching device 21a and the second heat exchanger side flow path switching device 21b are not distinguished, they are referred to as the heat exchanger side flow path switching device 21.
  • first outdoor heat exchanger 30a and the second outdoor heat exchanger 30b are not distinguished, they are referred to as the outdoor heat exchanger 30.
  • first outdoor expansion valve 40a and the second outdoor expansion valve 40b are not distinguished, they are referred to as the outdoor expansion valves 40.
  • accumulator 50 When there is no need to distinguish between the first accumulator 50a and the second accumulator 50b, they are referred to as accumulator 50.
  • the control device 5 controls the compressor 10, the heat exchanger side flow switching device 21, and the outdoor expansion valve 40 of the outdoor unit 2 according to the operation mode.
  • the control device 5 also controls the bypass valve 60, the low pressure valve 71, and the high pressure valve 72 of the relay unit 3 according to the operation mode.
  • the control device 5 controls the first indoor expansion valve 90a of the indoor unit 4 according to the operation mode.
  • FIG 26 is a diagram for explaining the heating operation of the air conditioning apparatus 1D according to embodiment 5.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also closes the bypass valve 60, closes the low pressure valve 71, and opens the high pressure valve 72.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the first compressor 10a is compressed by the first compressor 10a and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the first compressor 10a passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the high-pressure gas branch pipe 302, which is provided with a high-pressure valve 72, and the gas branch pipe 104 and flows into the indoor unit 4.
  • the refrigerant that flows into the indoor unit 4 passes through the indoor heat exchanger 80, which acts as a condenser.
  • the refrigerant that passes through the indoor heat exchanger 80 exchanges heat with the indoor air, condenses, and liquefies. At this time, the indoor air is warmed, and heating is performed in the room.
  • the liquid state refrigerant passes through the indoor expansion valve 90, is decompressed and expanded, and becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant.
  • the refrigerant in the gas-liquid two-phase state passes through the liquid branch pipe 105, the relay liquid pipe 304, and the main liquid pipe 103 and flows into the first outdoor unit 2a.
  • the refrigerant that flows into the first outdoor unit 2a passes through the outdoor expansion valve 40, is further decompressed and expanded, and passes through the first outdoor heat exchanger 30a that acts as an evaporator.
  • the refrigerant that passes through the first outdoor heat exchanger 30a exchanges heat with the outdoor air and evaporates and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the first heat exchanger side flow switching device 21a and the accumulator 50, and is sucked back into the first compressor 10a.
  • the refrigerant sucked into the second compressor 10b is compressed by the second compressor 10b and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the second compressor 10b flows into the high-pressure gas main pipe 102 and merges with the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3.
  • the refrigerant in a gas-liquid two-phase state flowing through the liquid main pipe 103 branches off from the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3 and flows into the second outdoor unit 2b.
  • the refrigerant that flows into the second outdoor unit 2b passes through the outdoor expansion valve 40, is further decompressed and expanded, and passes through the second outdoor heat exchanger 30b, which acts as an evaporator.
  • the refrigerant passing through the second outdoor heat exchanger 30b exchanges heat with the outdoor air, evaporates, and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the second heat exchanger side flow switching device 21b and the accumulator 50, and is sucked back into the second compressor 10b.
  • Figure 27 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1D according to embodiment 5.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow path switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also opens the bypass valve 60, closes the low pressure valve 71, and opens the high pressure valve 72.
  • the control device 5 closes the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • the refrigerant sucked into the first compressor 10a is compressed by the first compressor 10a and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the first compressor 10a passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302, a bypass pipe 305 with a bypass valve 60, a part of the relay liquid pipe 304, and the liquid main pipe 103, and flows again into the first outdoor unit 2a.
  • the high-temperature, high-pressure gas state refrigerant that flows into the first outdoor unit 2a passes through the outdoor expansion valve 40 and the first outdoor heat exchanger 30a acting as an evaporator.
  • the high-temperature, low-pressure gas state refrigerant that passes through the first outdoor heat exchanger 30a is heat exchanged with the frost attached to the first outdoor heat exchanger 30a, condenses, and becomes a low-temperature, low-pressure gas state.
  • the first outdoor heat exchanger 30a is defrosted.
  • the low-temperature, low-pressure gaseous refrigerant passes through the first heat exchanger side flow switching device 21a and the accumulator 50, and is sucked back into the first compressor 10a.
  • the low-pressure valve 71 is closed, and the indoor expansion valve 90 is also closed. This blocks the flow of refrigerant to the indoor unit 4, and the liquid refrigerant is stored in the indoor unit 4.
  • the refrigerant sucked into the second compressor 10b is compressed by the second compressor 10b and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the second compressor 10b flows into the high-pressure gas main pipe 102 and merges with the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3.
  • the refrigerant in a gas-liquid two-phase state flowing through the liquid main pipe 103 branches off from the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3 and flows into the second outdoor unit 2b.
  • the refrigerant that flows into the second outdoor unit 2b passes through the outdoor expansion valve 40, is further decompressed and expanded, and passes through the second outdoor heat exchanger 30b, which acts as an evaporator.
  • the refrigerant passing through the second outdoor heat exchanger 30b exchanges heat with the outdoor air, evaporates, and gasifies.
  • the evaporated low-temperature, low-pressure gaseous refrigerant then passes through the second heat exchanger side flow switching device 21b and the accumulator 50, and is again sucked into the second compressor 10b.
  • Figure 28 is a diagram for explaining the cooling operation of the air conditioning apparatus 1D according to embodiment 5.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the compressor 10 and the outdoor heat exchanger 30.
  • the control device 5 also closes the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the refrigerant sucked into the first compressor 10a is compressed by the first compressor 10a and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the first compressor 10a passes through the first heat exchange side flow switching device 21a and passes through the first outdoor heat exchanger 30a.
  • the refrigerant passing through the first outdoor heat exchanger 30a exchanges heat with the outdoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the outdoor expansion valve 40 and is reduced in pressure and expanded.
  • the liquid state refrigerant passes through the liquid main pipe 103 and flows into the relay unit 3.
  • the refrigerant that has flowed into the relay unit 3 passes through the relay liquid pipe 304 and the liquid branch pipe 105 and flows into the indoor unit 4.
  • the refrigerant that has flowed into the indoor unit 4 is further reduced in pressure and expanded by the indoor expansion valve 90 to become a low-temperature, low-pressure gas-liquid two-phase refrigerant.
  • the low-temperature, low-pressure gas-liquid two-phase refrigerant passes through the indoor heat exchanger 80, exchanges heat with the indoor air, evaporates, and gasifies. At this time, the indoor air is cooled, and cooling is performed in the room.
  • the gaseous refrigerant passes through the gas branch pipe 104 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through the low-pressure gas branch pipe 303, which is provided with the low-pressure valve 71 of the relay gas pipe 301, and the low-pressure gas main pipe 101, and flows into the first outdoor unit 2a.
  • the refrigerant that flows into the first outdoor unit 2a passes through the accumulator 50 and is sucked into the first compressor 10a again.
  • the refrigerant sucked into the second compressor 10b is compressed by the second compressor 10b and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the second compressor 10b passes through the second heat exchange side flow switching device 21b and passes through the second outdoor heat exchanger 30b.
  • the refrigerant passing through the second outdoor heat exchanger 30b exchanges heat with the outdoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the outdoor expansion valve 40 and is reduced in pressure and expanded.
  • the liquid state refrigerant flows into the liquid main pipe 103 and merges with the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3.
  • the refrigerant flowing through the low-pressure gas main pipe 101 branches off from the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3 and flows into the second outdoor unit 2b.
  • the refrigerant that flows into the second outdoor unit 2b passes through the accumulator 50 and is sucked back into the second compressor 10b.
  • Figure 29 is a diagram for explaining the liquid drainage operation of the air conditioning apparatus 1D according to embodiment 5.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction that connects the compressor 10 and the outdoor heat exchanger 30.
  • the control device 5 also opens the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • a main circuit and a bypass circuit are formed.
  • the refrigerant flows in the same manner as in the cooling operation.
  • the bypass circuit the high-temperature and high-pressure gas-state refrigerant discharged from the first compressor 10a passes through the high-pressure gas main pipe 102 and flows into the relay unit 3.
  • the refrigerant that flows into the relay unit 3 passes through a part of the high-pressure gas branch pipe 302 and the bypass pipe 305 in which the bypass valve 60 is provided, flows into the relay liquid pipe 304, and merges into the main circuit.
  • the liquid refrigerant that has accumulated in the high-pressure gas main pipe 102 is caused to flow and merges into the main circuit.
  • the refrigerant sucked into the second compressor 10b is compressed by the second compressor 10b and discharged in a high-temperature, high-pressure gas state.
  • the high-temperature, high-pressure gas state refrigerant discharged from the second compressor 10b passes through the second heat exchange side flow switching device 21b and passes through the second outdoor heat exchanger 30b.
  • the refrigerant passing through the second outdoor heat exchanger 30b exchanges heat with the outdoor air, condenses, and liquefies.
  • the liquid state refrigerant passes through the outdoor expansion valve 40 and is reduced in pressure and expanded.
  • the liquid state refrigerant flows into the liquid main pipe 103 and merges with the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3.
  • the refrigerant flowing through the low-pressure gas main pipe 101 branches off from the flow of refrigerant flowing between the first outdoor unit 2a and the relay unit 3 and flows into the second outdoor unit 2b.
  • the refrigerant that flows into the second outdoor unit 2b passes through the accumulator 50 and is sucked back into the second compressor 10b.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the first embodiment. Therefore, in the air conditioning device 1D of the fifth embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1D of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1D of the fifth embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • Embodiment 6 is a refrigerant circuit diagram of an air conditioning apparatus 1E according to embodiment 6. As shown in Fig. 30, embodiment 6 differs from embodiment 2 in that it has a first outdoor unit 2a and a second outdoor unit 2b as described in embodiment 5. In embodiment 6, the same parts as in embodiment 2 are given the same reference numerals and their description is omitted, and the description will focus on the differences from embodiment 2.
  • the second outdoor unit 2b has a second high-pressure pipe side flow path switching device 22b.
  • the second high-pressure pipe side flow path switching device 22b switches between a direction in which the high-pressure gas main pipe 102 is connected to the second compressor 10b and a direction in which the high-pressure gas main pipe 102 is connected to the second accumulator 50b.
  • the high-pressure pipe side flow path switching device 22 when there is no need to distinguish between the first high-pressure pipe side flow path switching device 22a and the second high-pressure pipe side flow path switching device 22b, they may be referred to as the high-pressure pipe side flow path switching device 22.
  • FIG. 31 is a diagram for explaining the heating operation of the air conditioning device 1E according to the sixth embodiment.
  • the arrows indicate the direction of the refrigerant flow.
  • the control device 5 switches the heat exchange side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50, and switches the high pressure pipe side flow switching device 22 to a direction that connects the compressor 10 and the high pressure gas main pipe 102.
  • the control device 5 closes the bypass valve 60, closes the low pressure valve 71, and opens the high pressure valve 72.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • FIG 32 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1E according to embodiment 6.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the outdoor heat exchanger 30 and the accumulator 50, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the compressor 10 and the high-pressure gas main pipe 102.
  • the control device 5 also opens the bypass valve 60, closes the low-pressure valve 71, and opens the high-pressure valve 72. Furthermore, the control device 5 closes the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • FIG 33 is a diagram for explaining the cooling operation of the air conditioning apparatus 1E according to embodiment 6.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the compressor 10 and the outdoor heat exchanger 30, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the accumulator 50 and the high-pressure gas main pipe 102.
  • the control device 5 closes the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • Figure 34 is a diagram for explaining the liquid draining operation of the air conditioning apparatus 1E according to embodiment 6.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the compressor 10 and the outdoor heat exchanger 30, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the accumulator 50 and the high-pressure gas main pipe 102.
  • the control device 5 also opens the bypass valve 60, closes the high-pressure valve 72, and opens the low-pressure valve 71.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the second embodiment. Therefore, in the air conditioning device 1E of the sixth embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1E of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1E of the sixth embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • Embodiment 7 is a refrigerant circuit diagram of an air conditioning apparatus 1F according to embodiment 7. As shown in Fig. 35, embodiment 7 differs from embodiment 3 in that it has a first outdoor unit 2a and a second outdoor unit 2b as described in embodiment 5. In embodiment 7, the same parts as in embodiment 3 are given the same reference numerals and their description is omitted, and the description will focus on the differences from embodiment 3.
  • FIG. 36 is a diagram for explaining the heating operation of the air conditioning device 1F according to the seventh embodiment.
  • the arrows indicate the direction of the refrigerant flow.
  • the control device 5 switches the heat exchange side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also closes the bypass valve 60, closes the low pressure valve 71, opens the high pressure valve 72, and opens the medium pressure valve 73. Furthermore, the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • Figure 37 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1F according to embodiment 7.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow path switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50.
  • the control device 5 also opens the bypass valve 60, closes the low pressure valve 71, opens the high pressure valve 72, and closes the medium pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and opens the outdoor expansion valve 40. Note that the indoor expansion valve 90 may be closed.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the third embodiment. Therefore, in the air conditioning device 1F of the seventh embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1F of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1F of the seventh embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • Embodiment 8 is a refrigerant circuit diagram of an air conditioning apparatus 1G according to embodiment 8. As shown in Fig. 38, embodiment 8 differs from embodiment 1 in that it has a first outdoor unit 2a and a second outdoor unit 2b as described in embodiment 5. In embodiment 8, the same parts as in embodiment 4 are given the same reference numerals and their description is omitted, and the description will focus on the differences from embodiment 4.
  • FIG. 39 is a diagram for explaining the heating operation of the air conditioning device 1G according to the eighth embodiment.
  • the arrows indicate the direction of the refrigerant flow.
  • the control device 5 switches the heat exchange side flow switching device 21 to a direction that connects the outdoor heat exchanger 30 and the accumulator 50, and switches the high pressure pipe side flow switching device 22 to a direction that connects the compressor 10 and the high pressure gas main pipe 102.
  • the control device 5 closes the bypass valve 60, closes the low pressure valve 71, opens the high pressure valve 72, and opens the medium pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and the outdoor expansion valve 40.
  • FIG 40 is a diagram for explaining the defrosting operation of the air conditioning apparatus 1G according to the eighth embodiment.
  • the arrows indicate the direction of refrigerant flow.
  • the control device 5 switches the heat exchanger side flow switching device 21 to a direction connecting the outdoor heat exchanger 30 and the accumulator 50, and switches the high-pressure pipe side flow switching device 22 to a direction connecting the compressor 10 and the high-pressure gas main pipe 102.
  • the control device 5 opens the bypass valve 60, closes the low-pressure valve 71, opens the high-pressure valve 72, and closes the medium-pressure valve 73.
  • the control device 5 opens the indoor expansion valve 90 and opens the outdoor expansion valve 40.
  • the indoor expansion valve 90 may be closed.
  • the bypass valve 60 is provided in the bypass pipe 305, as in the fourth embodiment. Therefore, in the air conditioning device 1G of the eighth embodiment, the bypass valve 60 is opened during the defrost operation, and the flow of the refrigerant to the indoor unit 4 is blocked, so that the high-temperature refrigerant can be allowed to flow into the outdoor heat exchanger 30 while the refrigerant liquid is stored in the indoor unit 4. In other words, in the defrost operation of the air conditioning device 1G of the present disclosure, liquid backflow is suppressed without using the heat of the piping warmed by the high-temperature refrigerant gas during the heating operation.
  • the air conditioning device 1G of the eighth embodiment can continuously suppress liquid backflow to the accumulator 50 during the defrost operation.
  • the high-pressure gas main pipe 102 and the liquid main pipe 103 do not cool during the defrost operation, so heating can be resumed early.
  • the liquid drainage operation may be performed at a predetermined time interval.
  • the liquid drainage operation may be performed at a predetermined time interval.
  • simultaneous cooling and heating operation may be performed in which one indoor unit 4 performs cooling operation and the other indoor unit 4 performs heating operation.
  • a defrosting operation is performed after a heating operation
  • a liquid drainage operation is performed after a cooling operation, but the order of the operating modes is not limited to this case.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Conditioning Control Device (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
PCT/JP2022/038333 2022-10-14 2022-10-14 空気調和装置 Ceased WO2024079873A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05149638A (ja) * 1991-11-27 1993-06-15 Sanyo Electric Co Ltd 多室型空気調和機
WO2018062528A1 (ja) * 2016-09-30 2018-04-05 ダイキン工業株式会社 冷凍装置
JP2018077040A (ja) * 2016-10-28 2018-05-17 ダイキン工業株式会社 空気調和装置
WO2021001869A1 (ja) * 2019-07-01 2021-01-07 三菱電機株式会社 空気調和装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05149638A (ja) * 1991-11-27 1993-06-15 Sanyo Electric Co Ltd 多室型空気調和機
WO2018062528A1 (ja) * 2016-09-30 2018-04-05 ダイキン工業株式会社 冷凍装置
JP2018077040A (ja) * 2016-10-28 2018-05-17 ダイキン工業株式会社 空気調和装置
WO2021001869A1 (ja) * 2019-07-01 2021-01-07 三菱電機株式会社 空気調和装置

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