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GB2564995A - Air-conditioning device - Google Patents

Air-conditioning device Download PDF

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Publication number
GB2564995A
GB2564995A GB1817754.3A GB201817754A GB2564995A GB 2564995 A GB2564995 A GB 2564995A GB 201817754 A GB201817754 A GB 201817754A GB 2564995 A GB2564995 A GB 2564995A
Authority
GB
United Kingdom
Prior art keywords
refrigerant
pressure
unit
pipe
indoor units
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.)
Granted
Application number
GB1817754.3A
Other versions
GB201817754D0 (en
GB2564995B (en
Inventor
Okano Hiroyuki
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
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Publication of GB201817754D0 publication Critical patent/GB201817754D0/en
Publication of GB2564995A publication Critical patent/GB2564995A/en
Application granted granted Critical
Publication of GB2564995B publication Critical patent/GB2564995B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • 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
    • F25B13/00—Compression machines, plants or systems, with reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • F24F11/32—Responding to malfunctions or emergencies
    • F24F11/36—Responding to malfunctions or emergencies to leakage of heat-exchange fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/89—Arrangement or mounting of control or safety devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F25B41/24—Arrangement of shut-off valves for disconnecting a part of the refrigerant cycle, e.g. an outdoor part
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/005—Arrangement or mounting of control or safety devices of safety devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/006—Compression machines, plants or systems with reversible cycle not otherwise provided for two pipes connecting the outdoor side to the indoor side with multiple indoor units
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • 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
    • F25B2313/0231—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units with simultaneous cooling and heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
    • F25B2313/0233—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units in parallel arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
    • F25B2313/0272—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using bridge circuits of one-way 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
    • F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
    • F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
    • F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/22—Preventing, detecting or repairing leaks of refrigeration fluids
    • F25B2500/221—Preventing leaks from developing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/22—Preventing, detecting or repairing leaks of refrigeration fluids
    • F25B2500/222—Detecting refrigerant leaks
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves
    • F25B2600/2513—Expansion valves

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Air Conditioning Control Device (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)

Abstract

This air-conditioning device comprises: a heat source unit that has a compressor, a flow path switching valve, and a heat-source-side heat exchanger; a plurality of indoor units that have load-side heat exchangers and perform cooling operations or heating operations; a low-pressure pipe and a high-pressure pipe that connect the heat source unit and the indoor units; a relay unit that has a first branch portion, which has first opening-closing valves which are switched to connect one end of the load-side heat exchangers to the low-pressure pipe, and second opening-closing valves which are switched to connect said ends of the load-side heat exchangers to the high-pressure pipe, and a second branch portion, which connects the other end of the load-side heat exchangers to the high-pressure pipe through first expansion valves and to a medium-pressure return pipe through second expansion valves; a leakage detection unit that detects leakage of a refrigerant; and a control device that controls the first expansion valves and the second expansion valves. The control device performs pump down operation for closing all the first expansion valves and the second expansion valves and recovering the refrigerant to the heat source unit when the leakage of the refrigerant is detected by the leakage detection unit.

Description

The present invention relates to an air-conditioning apparatus including a relay unit which distributes refrigerant supplied from a heat source unit to a plurality of indoor units.
Background Art [0002]
A conventional air-conditioning apparatus using a refrigeration cycle such as a heat pump cycle is provided with a refrigerant circuit in which a heat source unit including a compressor and a heat-source-side heat exchanger is connected by a pipe to an indoor unit including an expansion valve and a load-side heat exchanger, and in which refrigerant flows. The air-conditioning apparatus performs air conditioning while changing the pressure, temperature, etc., ofthe refrigerant flowing in the refrigerant circuit by causing it to receive or transfer heat from or to air in space to be airconditioned, which is to be subjected to heat exchange, when the refrigerant is evaporated or condensed in the load-side heat exchanger. Furthermore, a proposed air-conditioning apparatus includes a heat source unit, a plurality of indoor units, a relay unit which distributes refrigerant supplied from the heat source unit to the plurality of indoor units. In such an air-conditioning apparatus, whether to perform a cooling operation or a heating operation in each ofthe plurality of indoor units is automatically determined in accordance with a temperature set at, for example, a remote control unit included with each indoor unit, the ambient temperature thereof, etc., and a simultaneous cooling and heating operation in which the cooling operation or heating operation is performed for each indoor unit is carried out.
[0003]
In recent years, from the viewpoint of prevention of global warming, the effect of flammable refrigerant on a human body, which flows into a room as leaking refrigerant, and prevention of flaming, it has been necessary to take measures against leakage of refrigerant in order to ensure safety, and air-conditioning apparatuses in which measures against refrigerant leakage are taken have been suggested (see, for example, Patent Literature 1).
In Patent Literature 1, in an air-conditioning apparatus in which simultaneous cooling and heating operation is to be performed, an additional valve device is provided between a relay unit and an indoor unit, and if leakage of refrigerant occurs, the valve device is closed, thereby preventing the refrigerant from flowing out of the indoor unit. Citation List
Patent Literature [0004]
Patent Literature 1: Japanese Patent No. 4076753
Summary of Invention
Technical Problem [0005]
However, in the air-conditioning apparatus disclosed in Patent Literature 1, an additional valve device needs to be provided between a relay unit and an indoor unit in order to prevent leaking refrigerant from flowing from the indoor unit to the outside thereof. Inevitably, the resultant apparatus or system is expensive. Furthermore, it takes long time to retrieve the refrigerant when the apparatus is repaired, unless a further design is applied in addition to closing of the valve in order to prevent refrigerant leakage.
[0006]
The present invention has been made to solve the above problem, and an object of the invention is to provide an air-conditioning apparatus in which refrigerant leakage can be prevented with an inexpensive configuration and the time for retrieving refrigerant can be shortened.
Solution to Problem [0007]
An air-conditioning apparatus of an embodiment of the present invention includes: a heat source unit including a compressor, a flow-passage switching valve, and a heat-source-side heat exchanger; a plurality of indoor units which include loadside heat exchangers and perform a cooling operation or a heating operation; a lowpressure pipe and a high-pressure pipe which connect the heat source unit and each of the indoor units; a relay unit including a first branching portion and a second branching portion, the first branching portion including first opening/closing valves and second opening/closing valves, the first opening/closing valves being each provided to connect one end of an associated one of the load-side heat exchangers to the low-pressure pipe when a state of the each of the first opening/closing valve is switched, the second opening/closing valves being each provided to connect the one end of an associated one of the load-side heat exchangers to the high-pressure pipe when a state of the each of the second opening/closing valves is switched, the second branching portion being provided to connect an other end of each of the load-side heat exchangers to a highpressure liquid pipe through a first expansion valve, and to a return intermediatepressure pipe through a second expansion valve; a leakage detection unit which detects leakage of refrigerant; and a controller which controls the first expansion valve and the second expansion valve. When the leakage detection unit detects leakage of refrigerant, the controller closes all the first and second expansion valves, and performs a pump-down operation to retrieve the refrigerant into the heat source unit. Advantageous Effects of Invention [0008]
An air-conditioning apparatus of an embodiment of the present invention includes a leakage detection unit which detects refrigerant leakage, and upon the detection of refrigerant leakage by the leakage detection unit, the controller closes all the expansion valves to perform the pump-down operation, and recovers the refrigerant to the heat source unit. That is, upon the detection of refrigerant leakage, the indoor units are shut down by the expansion valves to prevent the leakage of the refrigerant from the indoor units to the outside of the indoor units, and the refrigerant is retrieved from the indoor units to the heat source unit, thereby shortening the time for retrieving the refrigerant.
In addition, it is not necessary to provide an additional valve for preventing the leakage of the refrigerant from the indoor units to the outside thereof, in addition to the expansion valves. Therefore, it is possible to achieve a configuration at a low cost.
Brief Description of Drawings [0009] [Fig. 1] Fig. 1 is a refrigerant circuit diagram illustrating an air-conditioning apparatus according to an embodiment of the present invention.
[Fig. 2] Fig. 2 is a refrigerant circuit diagram illustrating the state of an airconditioning apparatus according to an embodiment of the present invention during a cooling only operation.
[Fig. 3] Fig. 3 is a refrigerant circuit diagram illustrating the state of the airconditioning apparatus according to an embodiment of the present invention during a heating only operation.
[Fig. 4] Fig. 4 is a refrigerant circuit diagram illustrating the state of the airconditioning apparatus according to an embodiment of the present invention during a cooling main operation.
[Fig. 5] Fig. 5 is a refrigerant circuit diagram illustrating the state of the airconditioning apparatus according to an embodiment of the present invention during a heating main operation.
[Fig. 6] Fig. 6 is a flow chart of the operation of the air-conditioning apparatus according to an embodiment ofthe present invention, which is performed upon detection of refrigerant leakage.
[Fig. 7] Fig. 7 is a refrigerant circuit diagram illustrating the state of the airconditioning apparatus according to an embodiment of the present invention during a pump-down operation.
Description of Embodiments [0010]
An embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited to the embodiment. In addition, there is a case where the relationship in size between the components as illustrated in the drawings is different from that between actual components.
[0011]
Embodiment
An air-conditioning apparatus of the present invention according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 1 is a refrigerant circuit diagram illustrating an air-conditioning apparatus 1 according to the embodiment of the present invention.
The configuration of the air-conditioning apparatus 1 according to the embodiment will be described below with reference to Fig. 1.
As illustrated in Fig. 1, the air-conditioning apparatus 1 includes a heat source unit 100, a plurality of indoor units 300a and 300b, a relay unit 200 and a controller 10. [0012]
It should be noted that although the embodiment will be described by referring to by way of the case where two indoor units 300a and 300b are connected to one heat source unit 100, two or more heat source units 100 may be provided. Also, three or more indoor units 300a and 300b may be provided.
[0013]
As illustrated in Fig. 1, in the air-conditioning apparatus 1, the heat source unit 100, the indoor units 300a and 300b and the relay unit 200 are connected by pipes, thereby forming a refrigerant circuit in which refrigerant circulates.
The heat source unit 100 has a function of supplying heating energy or cooling energy to the two indoor units 300a and 300b. The two indoor units 300a and 300b are connected parallel to each other, and have the same configuration.
[0014]
The indoor units 300a and 300b have a function of cooling or heating space to be air-conditioned, such as the interior of a room, using heating energy or cooling energy supplied from the heat source unit 100.
The relay unit 200 is interposed between the heat source unit 100 and the indoor units 300a and 300b, and has a function of changing the flow of refrigerant supplied from the heat source unit 100 in response to a request from the indoor units 300a and
300b.
[0015]
Furthermore, the air-conditioning apparatus 1 is provided with a load capacity detector 20 which detects cooling and heating load capacities of the indoor units 300a and 300b. The cooling and heating load capacities are cooling load capacities and heating load capacities of the indoor units 300a and 300b. The load capacity detector 20 includes liquid-pipe temperature detection units 303a and 303b and gas-pipe temperature detection units 304a and 304b.
[0016]
The heat source unit 100 and the relay unit 200 are connected to each other on a high-pressure side by a high-pressure pipe 402 in which high-pressure refrigerant flows, and also connected to each other on a low-pressure side by a low-pressure pipe 401 in which low-pressure refrigerant flows. In addition, the relay unit 200 and the indoor units 300a and 300b are connected to each other by respective gas branch pipes 403a and 403b. The gas branch pipes 403a and 403b allow mostly gas refrigerant to flow therethrough. In addition, the relay unit 200 and the indoor units 300a and 300b are connected to each other by respective liquid branch pipes 404a and 404b. The liquid branch pipes 404a and 404b allow mostly liquid refrigerant to flow therethrough. [0017] (Heat source unit 100)
The heat source unit 100 has a function of supplying heating energy or cooling energy to the indoor units 300a and 300b.
The heat source unit 100 includes a compressor 101 whose capacity is variable, a flow-passage switching valve 102 which changes the flow direction of refrigerant in the heat source unit 100, a heat-source-side heat exchanger unit 120, an accumulator 104 which is connected to a suction side of the compressor 101 to store liquid refrigerant, and a heat-source-side flow-passage adjusting unit 140 which limits the flow direction of refrigerant.
It should be noted that although it is illustrated by way of example that the flowpassage switching valve 102 is a four-way valve, the flow-passage switching valve 102 may be a combination of two-way valves, three-way valves, or the like.
[0018]
The heat-source-side heat exchanger unit 120 includes a main pipe 114, a heatsource-side heat exchanger 103, and a heat-source-side fan 112.
The heat-source-side heat exchanger 103 functions as an evaporator or a condenser. The heat-source-side heat exchanger 103 causes heat exchange to be performed between refrigerant and outdoor air in the case where it is of an air-cooled type, and causes heat exchange to be performed between refrigerant and water, brine, or the like in the case where it is of a water-cooled type.
[0019]
The heat-source-side fan 112 changes the amount of air to be sent to the heatsource-side heat exchanger 103, and controls a heat exchange capacity.
One of ends of the main pipe 114 is connected to the flow-passage switching valve 102, and the other is connected to the high-pressure pipe 402, and the heatsource-side heat exchanger 103 is provided between these ends.
[0020]
The heat-source-side flow-passage adjusting unit 140 includes a third check valve 105, a fourth check valve 106, a fifth check valve 107 and a sixth check valve 108.
The third check valve 105 is provided at a pipe connecting the heat-source-side heat exchanger unit 120 and the high-pressure pipe 402, and allows refrigerant from the heat-source-side heat exchanger unit 120 to flow toward the high-pressure pipe 402.
The fourth check valve 106 is provided at a pipe connecting the flow-passage switching valve 102 of the heat source unit 100 and the low-pressure pipe 401, and allows refrigerant from the low-pressure pipe 401 to flow toward the flow-passage switching valve 102.
[0021]
The fifth check valve 107 is provided at a pipe connecting the flow-passage switching valve 102 ofthe heat source unit 100 and the high-pressure pipe 402, and allows refrigerant from the flow-passage switching valve 102 to flow toward the highpressure pipe 402.
The sixth check valve 108 is provided at a pipe connecting the heat-source-side heat exchanger unit 120 and the low-pressure pipe 401, and allows refrigerant from the low-pressure pipe 401 to flow toward the heat-source-side heat exchanger unit 120. [0022]
The heat source unit 100 is provided with a discharge-pressure detection unit 126 and a suction-pressure detection unit 127.
The discharge-pressure detection unit 126 is provided at a pipe connecting the flow-passage switching valve 102 and the discharge side of the compressor 101, and detects a discharge pressure at the compressor 101. The discharge-pressure detection unit 126 is constituted by, for example, a pressure sensor, and transmits a signal indicating the detected discharge pressure to the controller 10.
It should be noted that the discharge-pressure detection unit 126 may include a storage device or the like. In this case, the discharge-pressure detection unit 126 stores data regarding the detected discharge pressure in a storage device or the like for a predetermined period, and transmits a signal including data regarding a discharge pressure detected at regular intervals to the controller 10.
[0023]
The suction-pressure detection unit 127 is provided at a pipe connecting the flowpassage switching valve 102 and the accumulator 104, and detects a suction pressure at the compressor 101. The suction-pressure detection unit 127 is constituted by, for example, a pressure sensor, and transmits a signal indicating the detected suction pressure to the controller 10.
It should be noted that the suction-pressure detection unit 127 may include a storage device or the like. In this case, the suction-pressure detection unit 127 stores data regarding the detected suction pressure in a storage device or the like for a predetermined period, and transmits a signal including data regarding the suction pressure detected at regular intervals to the controller 10.
[0024] (Indoor units 300a and 300b)
The indoor units 300a and 300b include respective load-side heat exchangers 301a and 301b, which function as condensers or evaporators.
[0025]
The indoor unit 300a is provided with the gas-pipe temperature detection unit 304a and the liquid-pipe temperature detection unit 303a, and the indoor unit 300b is provided with the gas-pipe temperature detection unit 304b and the liquid-pipe temperature detection unit 303b.
The gas-pipe temperature detection unit 304a is provided between one of ends of the load-side heat exchanger 301a and the relay unit 200, and detects the temperature of the refrigerant flowing through the gas branch pipe 403a connecting the load-side heat exchanger 301a and the relay unit 200; and the gas-pipe temperature detection unit 304b is provided between one of ends of the load-side heat exchanger 301 b and the relay unit 200, and detects the temperature of the refrigerant flowing through the gas branch pipe 403b connecting the load-side heat exchanger 301b and the relay unit 200. The gas-pipe temperature detection units 304a and 304b are constituted by, for example, thermistors, and each transmit a signal indicating the detected temperature to the controller 10.
[0026]
It should be noted that the gas-pipe temperature detection units 304a and 304b may each include a storage device or the like. In this case, the gas-pipe temperature detection units 304a and 304b each store data regarding the detected temperature in the storage device or the like for a predetermined period, and transmit a signal including data regarding a temperature detected at regular intervals to the controller 10.
[0027]
The liquid-pipe temperature detection unit 303a is provided between the other end of the load-side heat exchanger 301a and the relay unit 200, and detects the temperature of the refrigerant flowing through the liquid branch pipe 404a connecting the load-side heat exchanger 301a and the relay unit 200; and the liquid-pipe temperature detection unit 303b is provided between the other end of the load-side heat exchanger 301b and the relay unit 200, and detects the temperature of the refrigerant flowing through the liquid branch pipe 404b connecting the load-side heat exchanger 301 b and the relay unit 200. The liquid-pipe temperature detection units 303a and 303b are constituted by, for example, thermistors, and each transmit a signal indicating the detected temperature to the controller 10.
[0028]
It should be noted that the liquid-pipe temperature detection units 303a and 303b may each include a storage device or the like. In this case, the liquid-pipe temperature detection units 303a and 303b each store data regarding the detected temperature in the storage device or the like for a predetermined period, and transmit a signal including data regarding a temperature detected at regular intervals to the controller 10. [0029] (Relay unit 200)
The relay unit 200 is interposed between the heat source unit 100 and the indoor units 300a and 300b, and has a function of changing the flow of refrigerant supplied from the heat source unit 100 in response to a request from the indoor units 300a and 300b, and distributing the refrigerant supplied from the heat source unit 100 to the indoor units 300a and 300b.
The relay unit 200 includes a first branching portion 240, a second branching portion 250, a gas-liquid separator 201, a relay bypass pipe 209, a high-pressure gas pipe 402A, a high-pressure liquid pipe 402B, a return intermediate-pressure pipe 401 A, a liquid discharge flow-rate adjustment valve 204, a heat-exchange unit 26, and a relay bypass flow-rate adjustment valve 205.
[0030]
In the first branching portion 240, one of ends thereof is connected to gas branch pipes 403a and 403b, and the other is connected to the low-pressure pipe 401 and the high-pressure gas pipe 402A, and the flow direction of refrigerant during the cooling operation is different from that during the heating operation. The first branching portion 240 includes heating solenoid valves 202a and 202b and cooling solenoid valves 203a and 203b.
[0031]
One of ends of the heating solenoid valve 202a is connected to the gas branch pipe 403a, and the other is connected to the high-pressure gas pipe 402A; and one of ends of the heating solenoid valve 202b is connected to the gas branch pipe 403b, and the other is connected to the high-pressure gas pipe 402A. The heating solenoid valves 202a and 202b are opened during the heating operation, and closed during the cooling operation.
One of ends of the cooling solenoid valve 203a is connected to the gas branch pipe 403a, and the other is connected to the low-pressure pipe 401; and one of ends of the cooling solenoid valve 203b is connected to the gas branch pipe 403b, and the other is connected to the low-pressure pipe 401. The cooling solenoid valves 203a and 203b are opened during the cooling operation, and closed during the heating operation. [0032]
It should be noted that the cooling solenoid valves 203a and 203b correspond to the “first opening/closing valves” of the present invention, and the heating solenoid valves 202a and 202b correspond to the “second opening/closing valves” of the present invention.
[0033]
In the second branching portion 250, one of ends thereof is connected to the liquid branch pipes 404a and 404b, and the other is connected to the return intermediate-pressure pipe 401A and the high-pressure liquid pipe 402B, and the flow direction of refrigerant during the cooling operation is different from that during the heating operation. The second branching portion 250 includes first expansion valves 210a and 210b and second expansion valves 211a and 211b.
[0034]
The first expansion valves 210a and 210b and the second expansion valves 211a and 211 b have a function of adjusting the flow rate of refrigerant flowing through the indoor units 300a and 300b. The first expansion valves 210a and 210b and the second expansion valves 211a and 211b are each constituted by, for example, an electric expansion valve whose opening degree is variable.
[0035]
One of ends of the first expansion valve 210a is connected to the liquid branch pipe 404a, and the other is connected to the high-pressure liquid pipe 402B; and one of ends of the first expansion valve 210b is connected to the liquid branch pipe 404b, and the other is connected to the high-pressure liquid pipe 402B. The opening degrees of the first expansion valves 210a and 210b are controlled to control the degrees of superheating at the outlets ofthe load-side heat exchangers 301a and 301b during the cooling operation.
One of ends of the second expansion valve 211a is connected to the liquid branch pipe 404a, and the other is connected to the return intermediate-pressure pipe 401 A; and one of ends of the second expansion valve 211b is connected to the liquid branch pipe 404b, and the other is connected to the return intermediate-pressure pipe 401 A. The opening degrees ofthe second expansion valves 211a and 211b are controlled to control the degrees of subcooling at the outlets of the load-side heat exchangers 301a and 301b during the heating operation.
[0036]
The indoor units 300a and 300b have a function of cooling or heating the space to be air-conditioned, such as the interior of a room, using heating energy or cooling energy supplied from the heat source unit 100.
The gas-liquid separator 201 separates gas refrigerant and liquid refrigerant from each other, and has an inlet connected to the high-pressure pipe 402, a gas outlet connected to the first branching portion 240 by the high-pressure gas pipe 402A, and a liquid outlet connected to the second branching portion 250 by the high-pressure liquid pipe 402B.
The relay bypass pipe 209 connects together with the high-pressure liquid pipe 402B the second branching portion 250 and the low-pressure pipe 401.
[0037]
The liquid discharge flow-rate adjustment valve 204 is connected to the liquid outlet of the gas-liquid separator 201, and constituted by, for example, an electric expansion valve whose opening degree is variable. The liquid discharge flow-rate adjustment valve 204 adjusts the flow rate of liquid refrigerant flowing out of the gasliquid separator 201.
[0038]
The heat-exchange unit 26 includes a first heat-exchange unit 206 and a second heat-exchange unit 207.
The first heat-exchange unit 206 is provided at a pipe between the liquid outlet of the gas-liquid separator 201 and the liquid discharge flow-rate adjustment valve 204, and at the relay bypass pipe 209. The first heat-exchange unit 206 causes heat exchange to be performed between the liquid refrigerant flowing out ofthe gas-liquid separator 201 and refrigerant flowing through the relay bypass pipe 209 toward the lowpressure pipe 401.
The second heat-exchange unit 207 is provided at a pipe located downstream of the liquid discharge flow-rate adjustment valve 204 and at the relay bypass pipe 209. The second heat-exchange unit 207 causes heat exchange to be performed between the refrigerant flowing out of the liquid discharge flow-rate adjustment valve 204 and refrigerant flowing through the relay bypass pipe 209 toward the low-pressure pipe 401. [0039]
The relay bypass flow-rate adjustment valve 205 is connected to part of the relay bypass pipe 209, which is located upstream of the second heat-exchange unit 207, and is constituted by, for example, an electric expansion valve whose opening degree is variable. The relay bypass flow-rate adjustment valve 205 adjusts the flow rate of refrigerant which has flowed out of the second heat-exchange unit 207 and flowed into the relay bypass pipe 209.
[0040]
Furthermore, the relay unit 200 is provided with a first liquid discharge-pressure detection unit 231, a second liquid discharge-pressure detection unit 232, and a replay bypass temperature detection unit 208.
The first liquid discharge-pressure detection unit 231 is provided between the first heat-exchange unit 206 and the liquid discharge flow-rate adjustment valve 204, and detects the pressure of refrigerant at the liquid outlet of the gas-liquid separator 201. The first liquid discharge-pressure detection unit 231 is constituted by, for example, a pressure sensor, and transmits a signal indicating the detected pressure to the controller 10. It should be noted that the first liquid discharge-pressure detection unit 231 may include a storage device or the like. In this case, the first liquid dischargepressure detection unit 231 stores data regarding the detected pressure in the storage device or the like for a predetermined period, and transmits a signal including data regarding a pressure detected at regular intervals to the controller 10.
[0041]
The second liquid discharge-pressure detection unit 232 is provided between the liquid discharge flow-rate adjustment valve 204 and the second heat-exchange unit 207, and detects the pressure of refrigerant which has flowed out of the liquid discharge flowrate adjustment valve 204. The second liquid discharge-pressure detection unit 232 is constituted by, for example, a pressure sensor, and transmits a signal indicating the detected pressure to the controller 10. It should be noted that the second liquid discharge-pressure detection unit 232 may include a storage device or the like. In this case, the second liquid discharge-pressure detection unit 232 stores data regarding the detected pressure in the storage device or the like for a predetermined period, and transmits a signal including data regarding a pressure detected at regular intervals to the controller 10.
[0042]
The opening degree of the liquid discharge flow-rate adjustment valve 204 is adjusted such that the difference between the pressure detected by the first liquid discharge-pressure detection unit 231 and the pressure detected by the second liquid discharge-pressure detection unit 232 is constant.
[0043]
The replay bypass temperature detection unit 208 is provided at the relay bypass pipe 209, and detects the pressure of the refrigerant flowing into the relay bypass pipe
209. The replay bypass temperature detection unit 208 is constituted by, for example, a thermistor, and transmits a signal indicating the detected temperature to the controller 10. It should be noted that the replay bypass temperature detection unit 208 may include a storage device or the like. In this case, the replay bypass temperature detection unit 208 stores data regarding the detected temperature in a storage device or the like for a predetermined period, and transmits a signal including data regarding a temperature detected at regular intervals to the controller 10.
[0044]
The opening degree of the relay bypass flow-rate adjustment valve 205 is adjusted based on at least one of the pressure detected by the first liquid dischargepressure detection unit 231, the pressure detected by the second liquid dischargepressure detection unit 232, and the temperature detected by the replay bypass temperature detection unit 208.
[0045] (Refrigerant)
In the air-conditioning apparatus 1, the pipes are filled with refrigerant. As the refrigerant, for example, natural refrigerant, such as carbon dioxide (CO2), hydrocarbons or helium, HFC 410Α or flammable R32 refrigerant is applied. It should be noted that the pipes of the air-conditioning apparatus 1 may be filled with a heat medium, not refrigerant. The heat medium is, for example, water, brine or the like. [0046] (Leakage detection unit)
A leakage detection unit 400 is a refrigerant leakage detection unit which detects leakage of refrigerant and outputs a signal. For example, the leakage detection unit 400 is a semiconductor gas sensor which detects, as the concentration of refrigerant gas in the air, a change in a resistance which occurs when a metal oxide semiconductor contacts the refrigerant gas. It should be noted that instead of the semiconductor gas sensor, for example, the following devices may be used: a non-dispersive infrared type sensor which performs detection based on the amount of infrared rays absorbed by gas; a device which cannot measure the concentration of refrigerant gas, but can detect the presence or absence of refrigerant gas; and an oxygen concentration meter which measures the concentration of oxygen in a room. Information indicating that refrigerant leakage is detected by the leakage detection unit 400 is transmitted to the controller 10 to trigger a pump-down operation.
[0047]
Although in the embodiment, the number of leakage detection units 400 provided for the entire system is only one, it is not limited to such a configuration. For example, in the case where for indoor units or rooms, respective leakage detection units 400 are provided, it is possible to determine in which of the indoor units or of the rooms leakage of refrigerant occurs.
[0048] (Controller 10)
The controller 10 controls the entire system ofthe air-conditioning apparatus 1, and is constituted by, for example, a microprocessor unit including a CPU, a memory, etc. The controller 10 controls, for example, the driving frequency of the compressor 101, the rotation speed of the heat-source-side fan 112, the rotation speed of an indoor fan (not illustrated) provided at each of the load-side heat exchangers 301a and 301b, switching of the flow-passage switching valve 102, closing and opening of the heating solenoid valves 202a and 202b and the cooling solenoid valves 203a and 203b, the opening degrees of the first expansion valves 210a and 210b, the second expansion valves 211a and 211b, the liquid discharge flow-rate adjustment valve 204, and the relay bypass flow-rate adjustment valve 205, on the basis of an instruction given from a remote control unit (not illustrated) and detection information received from the gas-pipe temperature detection units 304a and 304b, the liquid-pipe temperature detection units 303a and 303b, the first liquid discharge-pressure detection unit 231, the second liquid discharge-pressure detection unit 232, the replay bypass temperature detection unit 208, the discharge-pressure detection unit 126, and the suction-pressure detection unit 127.
[0049]
Although the controller 10 includes a first controller 141 provided at the heat source unit 100 and a second controller 220 provided at the relay unit 200, it is not limited to such a configuration. Only one of the heat source unit 100, the indoor units 300a and 300b and the relay unit 200 may be provided with the controller 10, or the heat source unit 100, the indoor units 300a and 300b and the relay unit 200 may be provided with respective controllers 10. Alternatively, the controller 10 may be provided separate from the heat source unit 100, the indoor units 300a and 300b, and the relay unit 200. It should be noted that the first controller 141 and the second controller 220 are connected to each other such that they can perform wireless communication with each other or wired communication with each other, and can transmit and receive various kinds of data or the like to and from each other. In addition, the controller 10 may be constituted by only one controller.
[0050]
The controller 10 further includes a storage unit 11 and a setting unit 12. Although in the embodiment, the storage unit 11 and the setting unit 12 are provided in the heat source unit 100, they may be provided in a component other than the heat source unit 100. The storage unit 11 and the setting unit 12 may be provided separate from the controller 10.
[0051]
The storage unit 11 stores data necessary for processing by the controller 10 temporarily or for long time, and is constituted by, for example, a memory.
The setting unit 12 has a function of determining whether the air-conditioning apparatus 1 is in the cooling main operation or the heating main operation. Furthermore, the setting unit 12 has a function of determining, during the cooling main operation, whether a target condensation temperature for the heat-source-side heat exchanger 103 is higher than or equal to a target condensation temperature threshold. It should be noted that with respect to the indoor units 300a and 300b, the setting unit 12 may calculate cooling and heating load capacities based on the number of indoor units which are in the cooling operation and the number of indoor units which are in the heating operation. The setting unit 12 may also calculate the cooling and heating load capacities based on the discharge pressure detected by the discharge-pressure detection unit 126 or the suction pressure detected by the suction-pressure detection unit 127 or the like. In this case, the discharge-pressure detection unit 126 or the suction-pressure detection unit 127 functions as a component in the load capacity detector 20.
[0052]
The operation of the air-conditioning apparatus 1 will now be explained.
The operation modes of the air-conditioning apparatus 1 correspond to the cooling only operation, the heating only operation, the cooling main operation and the heating main operation.
The cooling only operation corresponds to a mode in which all the indoor units, that is, both the indoor units 300a and 300b in this case, perform the cooling operation.
The heating only operation corresponds to a mode in which all the indoor units, that is, both the indoor units 300a and 300b in this case, perform the heating operation.
The cooling main operation corresponds to a mode of the simultaneous cooling and heating operation, in which the capacity of the cooling operation is greater than that of the heating operation.
The heating main operation corresponds to another mode of the simultaneous cooling/heating operation, in which the capacity of the heating operation is greater than that of the cooling operation.
[0053] (Cooling only operation)
Fig. 2 is a refrigerant circuit diagram illustrating the state of the air-conditioning apparatus 1 according to the embodiment of the present invention during the cooling only operation. In Fig. 2, the high pressure refrigerant is indicated by solid arrows, and the low pressure refrigerant is indicated by dotted arrows. The same is true of Figs 3 to 5 to be described later.
The cooling only operation of the air-conditioning apparatus 1 will now be explained with reference to Fig. 2. In the air-conditioning apparatus 1, in the cooling only operation, both the indoor units 300a and 300b perform the cooling operation.
As illustrated in Fig. 2, high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow-passage switching valve 102, exchanges heat with the outdoor air sent by the heat-source-side fan 112 in the heat-source-side heat exchanger 103, and is thus condensed and liquefied. The condensed and liquefied refrigerant passes through the third check valve 105 and the high-pressure pipe 402, and then reaches the gas-liquid separator 201 of the relay unit 200.
[0054]
The refrigerant is separated by the gas-liquid separator 201 into gas refrigerant and liquid refrigerant. After flowing out of the liquid outlet of the gas-liquid separator 201, the liquid refrigerant passes through the first heat-exchange unit 206, the liquid discharge flow-rate adjustment valve 204, the second heat-exchange unit 207, and the high-pressure liquid pipe 402B, and then reaches the second branching portion 250. At the second branching portion 250, the liquid refrigerant is separated into two. These two liquid refrigerants pass through the first expansion valves 210a and 210b and the liquid branch pipes 404a and 404b, and flow into the indoor units 300a and 300b, respectively.
[0055]
In the indoor units 300a and 300b, the pressures of the refrigerants are reduced to a low pressure at the first expansion valves 210a and 210b which are controlled in accordance with the degrees of superheating at the outlets of the load-side heat exchangers 301a and 301b, respectively. Thereafter, the refrigerants flow into the load-side heat exchangers 301 a and 301 b, exchange heat with indoor air in the loadside heat exchangers 301a and 301b, respectively, and is thus evaporated and gasified. At that time, all the rooms are cooled. The gasified refrigerants pass through the gas branch pipes 403a and 403b and the cooling solenoid valves 203a and 203b in the first branching portion 240, respectively, and then join each other to flow as single refrigerant, and the refrigerant passes through the low-pressure pipe 401.
[0056]
Part of the refrigerant which has passed through the second heat-exchange unit 207 flows into the relay bypass pipe 209. The pressure of the refrigerant having flowed into the relay bypass pipe 209 is reduced to a low pressure at the relay bypass flow-rate adjustment valve 205, and is then evaporated by exchanging heat, in the second heatexchange unit 207, with refrigerant having passed through the liquid discharge flow-rate adjustment valve 204, that is, refrigerant which has not yet separated or flowed into the branch relay bypass pipe 209. Furthermore, in the first heat-exchange unit 206, the refrigerant is evaporated by exchanging heat with refrigerant which has not yet flowed into the liquid discharge flow-rate adjustment valve 204. The evaporated refrigerant flows into the low-pressure pipe 401, and join refrigerant which has passed through the cooling solenoid valves 203a and 203b to flow as single refrigerant. The single refrigerant then passes through the fourth check valve 106, the flow-passage switching valve 102, and the accumulator 104, and is sucked into the compressor 101.
[0057]
It should be noted that in the cooling only operation, the heating solenoid valves 202a and 202b are closed. Further, the cooling solenoid valves 203a and 203b are opened. Since the pressure in the low-pressure pipe 401 is low and the pressure in the high-pressure pipe 402 is high, the refrigerant flows through the third check valve 105 and the fourth check valve 106. In addition, the second expansion valves 211 a and 211 b are closed, and thus do not allow refrigerant to flow therethrough. [0058] (Heating only operation)
Fig. 3 is a refrigerant circuit diagram illustrating the state of the air-conditioning apparatus 1 according to an embodiment of the present invention during the heating only operation.
The heating only operation of the air-conditioning apparatus 1 will now be explained with reference to Fig. 3. In the air-conditioning apparatus 1, in the heating only operation, all the indoor units, that is, both the indoor units 300a and 300b in this case, perform the heating operation.
As illustrated in Fig. 3, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow-passage switching valve
102, the fifth check valve 107, and the high-pressure pipe 402 in this order, and then reaches the gas-liquid separator 201 of the relay unit 200.
[0059]
The refrigerant is separated by the gas-liquid separator 201 into gas refrigerant and liquid refrigerant. After flowing from the gas outlet of the gas-liquid separator 201, the gas refrigerant passes through the high-pressure gas pipe 402A, and separates into two at the first branching portion 240. These two refrigerants flow through the heating solenoid valves 202a and 202b and the gas branch pipes 403a and 403b, and flow into the indoor units 300a and 300b, respectively.
[0060]
In the indoor units 300a and 300b, the refrigerants exchange heat with the indoor air in the load-side heat exchangers 301a and 301b, respectively, and are thus condensed and liquefied. At that time, all the rooms are heated. The condensed and liquefied refrigerant passes through the second expansion valves 211a and 211b which are controlled in accordance with the degrees of subcooling at the outlets of the loadside heat exchangers 301a and 301b, respectively.
[0061]
The refrigerant which has passed through the second expansion valves 211a and 211b passes through the return intermediate-pressure pipe 401A and the second heatexchange unit 207, flows into the relay bypass pipe 209, and its pressure is reduced to a low pressure at the relay bypass flow-rate adjustment valve 205. Then, the refrigerant is evaporated by exchanging heat, in the second heat-exchange unit 207, with refrigerant having passed through the liquid discharge flow-rate adjustment valve 204, that is, refrigerant which has not yet separated or flowed into the branch relay bypass pipe 209. Further, in the first heat-exchange unit 206, the refrigerant is evaporated by exchanging heat with refrigerant which has not yet flowed into the liquid discharge flow-rate adjustment valve 204. The evaporated refrigerant flows into through the low-pressure pipe 401 and passes through the sixth check valve 108, exchanges heat with the outdoor air sent by the heat-source-side fan 112 in the heatsource-side heat exchanger 103, and is thus evaporated and gasified. The gasified refrigerant passes through the flow-passage switching valve 102 and the accumulator
104, and is sucked into the compressor 101.
[0062]
It should be noted that in the heating only operation, the heating solenoid valves 202a and 202b are opened. Further, the cooling solenoid valves 203a and 203b are closed. Since the pressure in the low-pressure pipe 401 is low and the pressure in the high-pressure pipe 402 is high, the refrigerant flows through the fifth check valve 107 and the sixth check valve 108. It should also be noted that the liquid discharge flowrate adjustment valve 204 is closed. In addition, the first expansion valves 210a and 210b are closed, and thus do not allow refrigerant to flow therethrough.
[0063] (Cooling main operation)
Fig. 4 is a refrigerant circuit diagram illustrating the state of the air-conditioning apparatus 1 according to an embodiment of the present invention during the cooling main operation.
The cooling main operation of the air-conditioning apparatus 1 will now be explained with reference to Fig. 4. In the air-conditioning apparatus 1, in the cooling main operation, the indoor unit 300a issues a request for cooling, and the indoor unit 300b issues a request for heating.
As illustrated in Fig. 4, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow-passage switching valve 102, exchanges heat with outdoor air sent by the heat-source-side fan 112 in the heatsource-side heat exchanger 103, and is thus condensed and liquefied. The condensed and liquefied refrigerant passes through the third check valve 105 and the high-pressure pipe 402, and reaches the gas-liquid separator 201 of the relay unit 200.
[0064]
The refrigerant is separated by the gas-liquid separator 201 into gas refrigerant and liquid refrigerant. After flowing from the liquid outlet of the gas-liquid separator
201, the liquid refrigerant passes through the first heat-exchange unit 206, the liquid discharge flow-rate adjustment valve 204, the second heat-exchange unit 207, and the high-pressure liquid pipe 402B, and reaches the second branching portion 250. Then, the refrigerant flows through the first expansion valve 210a ofthe second branching portion 250 and the liquid branch pipe 404a, and flows into the indoor unit 300a. [0065]
For the refrigerant having flowed into the indoor unit 300a, the degree of superheating at the outlet of the load-side heat exchanger 301a is controlled through the first expansion valve 210a, and the pressure of the refrigerant is reduced to a low pressure. Thereafter, the refrigerant flows into the load-side heat exchanger 301a, exchanges heat with the indoor air in the load-side heat exchanger 301a, and is thus evaporated and gasified. At that time, a room where the indoor unit 300a is installed is cooled. The gasified refrigerant passes through the gas branch pipe 403a and the cooling solenoid valve 203a in the first branching portion 240, and then flows into the low-pressure pipe 401.
[0066]
On the other hand, after flowing from the gas outlet of the gas-liquid separator 201, the gas refrigerant passes through the high-pressure gas pipe 402A, the heating solenoid valve 202b of the first branching portion 240, and the gas branch pipe 403b, and flows into the indoor unit 300b. In the indoor unit 300b, the refrigerant is condensed and liquefied by exchanging heat with the indoor air in the load-side heat exchanger 301b. At that time, a room where the indoor unit 300b is installed is heated. The condensed and liquefied refrigerant then passes through the liquid branch pipe 404b, and the degree of subcooling of the refrigerant at the outlet is controlled by the second expansion valve 211b, whereby the refrigerant changes into intermediatepressure liquid refrigerant, that is, liquid refrigerant whose pressure is intermediate between high pressure and low pressure. The intermediate-pressure liquid refrigerant passes through the return intermediate-pressure pipe 401A and flows into the second heat-exchange unit 207.
[0067]
Thereafter, the refrigerant flows into the relay bypass pipe 209, its pressure is reduced to a low pressure at the relay bypass flow-rate adjustment valve 205, and it is then evaporated by exchanging heat, in the second heat-exchange unit 207, with the refrigerant having passed through the liquid discharge flow-rate adjustment valve 204, that is, the refrigerant which has not yet separated or flowed into the branch relay bypass pipe 209. Furthermore, in the first heat-exchange unit 206, the refrigerant exchanges heat with the refrigerant that has yet to flow into the liquid discharge flowrate adjustment valve 204, and is thereby evaporated. The evaporated refrigerant flows into the low-pressure pipe 401 and joins the refrigerant that has passed through the cooling solenoid valve 203a to flow as single refrigerant. The single refrigerant then passes through the fourth check valve 106, the flow-passage switching valve 102 and the accumulator 104, and is sucked into the compressor 101.
[0068]
It should be noted that in the cooling main operation, the heating solenoid valve 202a is closed, and the heating solenoid valve 202b is opened. Further, the cooling solenoid valve 203a is opened, and the cooling solenoid valve 203b is closed. Since the pressure in the low-pressure pipe 401 is low and the pressure in the high-pressure pipe 402 is high, the refrigerant flows through the third check valve 105 and the fourth check valve 106. In addition, the second expansion valve 211a is closed, and thus does not allow refrigerant to flow therethrough. Also, the first expansion valve 210b is closed, and does not allow refrigerant to flow therethrough.
[0069] (Heating main operation)
Fig. 5 is a refrigerant circuit diagram illustrating the state of the air-conditioning apparatus 1 according to an embodiment of the present invention during the heating main operation.
The heating main operation of the air-conditioning apparatus 1 will now be explained with reference to Fig. 5. In the air-conditioning apparatus 1, in the heating main operation, the indoor unit 300b issues a request for heating, and the indoor unit 300a issues a request for cooling.
As illustrated in Fig. 5, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow-passage switching valve
102, the fifth check valve 107 and the high-pressure pipe 402 in this order, and then reaches the gas-liquid separator 201 of the relay unit 200.
[0070]
The refrigerant is separated by the gas-liquid separator 201 into gas refrigerant and liquid refrigerant. After flowing from the gas outlet of the gas-liquid separator 201, the gas refrigerant passes through the high-pressure gas pipe 402A, and reaches the first branching portion 240. The refrigerant then flows through the heating solenoid valve 202b of the first branching portion 240 and the gas branch pipe 403b, and flows into the indoor unit 300b.
[0071]
In the indoor unit 300b, the refrigerant is condensed and liquefied by exchanging heat with the indoor air in the load-side heat exchanger 301 b. At that time, the room where the indoor unit 300b is installed is heated. The degree of subcooling of the condensed and liquefied refrigerant at the outlet is then controlled by the second expansion valve 211b, whereby the refrigerant changes into intermediate-pressure liquid refrigerant, that is, liquid refrigerant whose pressure is intermediate between high pressure and low pressure. The intermediate-pressure liquid refrigerant passes through the liquid branch pipe 404b, the second expansion valve 211b of the second branching portion 250 and the return intermediate-pressure pipe 401 A, and flows into the second heat-exchange unit 207. At this time, the refrigerant joins the liquid refrigerant having flowed from the liquid outlet of the gas-liquid separator 201 and passed through the first heat-exchange unit 206 and the liquid discharge flow-rate adjustment valve 204, that is, they are combined into a single refrigerant. The single refrigerant separates into refrigerant which will pass through the high-pressure liquid pipe 402B and flow into the second branching portion 250, and refrigerant which will flow into the relay bypass pipe 209.
[0072]
The refrigerant having flowed into the second branching portion 250 passes through the first expansion valve 210a of the second branching portion 250 and the liquid branch pipe 404a, and flows into the indoor unit 300a. In the indoor unit 300a, the degree of superheating of the refrigerant at the outlet of the load-side heat exchanger 301a is controlled by the first expansion valve 210a, and the pressure of the refrigerant is reduced to a low pressure. Thereafter, the refrigerant flows into the loadside heat exchanger 301a, and is evaporated and gasified by exchanging heat with the indoor air in the load-side heat exchanger 301a. At that time, the room where the indoor unit 300a is installed is cooled. The gasified refrigerant passes through the gas branch pipe 403a and the cooling solenoid valve 203a in the first branching portion 240, and then flows into the low-pressure pipe 401.
[0073]
On the other hand, the pressure of the refrigerant having flowed into the relay bypass pipe 209 is reduced to a low pressure at the relay bypass flow-rate adjustment valve 205, and is evaporated by exchanging heat, in the second heat-exchange unit 207, with refrigerant having passed through the liquid discharge flow-rate adjustment valve 204, that is, refrigerant which has not yet flowed into the branch relay bypass pipe 209. Further, in the first heat-exchange unit 206, the refrigerant is evaporated by exchanging heat with refrigerant which has not yet flowed into the liquid discharge flowrate adjustment valve 204. The evaporated refrigerant flows into the low-pressure pipe 401 and joins refrigerant which has passed through the cooling solenoid valve 203a to flow as single refrigerant. Then, the single refrigerant passes through the sixth check valve 108, and flows into the heat-source-side heat exchanger 103.
[0074]
In the heat-source-side heat exchanger 103, the refrigerant is evaporated and gasified by exchanging heat with the outdoor air sent from the heat-source-side fan 112 in the heat-source-side heat exchanger 103, and then passes through the flow-passage switching valve 102 and the accumulator 104, and is sucked into the compressor 101. [0075]
It should be noted that in the heating main operation, the heating solenoid valve 202b is opened, and the heating solenoid valve 202a is closed. Further, the cooling solenoid valve 203a is opened, and the cooling solenoid valve 203b is closed. Since the pressure in the low-pressure pipe 401 is low and the pressure in the high-pressure pipe 402 is high, the refrigerant flows through the fifth check valve 107 and the sixth check valve 108. In addition, the second expansion valve 211a is closed, and thus does not allow refrigerant to flow therethrough. Also, the first expansion valve 210b is closed, and thus does not allow refrigerant to flow therethrough.
[0076]
Fig. 6 is a flow chart illustrating the operation of the air-conditioning apparatus 1 according to an embodiment of the present invention, which is performed upon detection of refrigerant leakage.
The operation of the air-conditioning apparatus 1 which is performed upon detection of refrigerant leakage will now be explained with reference to Fig. 6.
The leakage detection unit 400 detects whether refrigerant leaks from a refrigerant circuit (step S1).
In the case where the leakage detection unit 400 detects leakage of refrigerant (Yes in step S1), a detection signal indicating the leakage of refrigerant is transmitted to the controller 10 (step S2).
[0077]
At this time, in the case where the air-conditioning apparatus 1 is in the cooling only operation (Yes in step S3), the operation is continued without changing the operation mode.
In contrast, in the case where it is not in the cooling only operation, that is, it is in any of the heating only operation, the cooling main operation and the heating main operation or it is stopped (No in step S3), the controller 10 forcibly changes the operation mode to cause it to perform the cooling only operation (Step S4). [0078]
Even in the cooling only operation, the controller 10 closes all the first expansion valves 210a and 210b and the second expansion valves 211 a and 211 b (step S5). It should be noted that the indoor units are set such that they are not made in a thermo-off state even if the suction temperature reaches the set temperature.
[0079]
Next, for example, in the case where the indoor units or the rooms are individually associated with the leakage detection unit 400, that is, refrigerant leakage in indoorunits systems or room systems can be individually detected by the leakage detection unit 400 (Yes in step S6), the controller 10 opens only the cooling solenoid valve 203a or 203b which is associated with an indoor unit or a room where refrigerant leakage occurs (step S7).
In contrast, for example, in the case where the indoor units or the rooms are not individually associated with the leakage detection unit 400, that is, refrigerant leakage in indoor-unit systems or room systems cannot be individually detected by the leakage detection unit 400 (No in step S6), the controller 10 opens all the cooling solenoid valves 203a and 203b (step S8).
Even in the case where the indoor units or the rooms are individually associated with the leakage detection unit 400, all the cooling solenoid valves, that is, both the cooling solenoid valves 203a and 203b in this case, may be opened if it is necessary to inspect the entire system of the air-conditioning apparatus 1.
[0080]
At this time, since the cooling only operation is performed, all the heating solenoid valves, that is, both the heating solenoid valves 202a and 202b in this case, are closed. [0081]
Thereafter, the controller 10 starts the pump-down operation of the airconditioning apparatus 1 (step S9). The pump-down operation will be described later in detail.
The pump-down operation is performed until retrieval of the refrigerant is completed. When the retrieval of the refrigerant is completed (Yes in step S10), the controller 10 stops the compressor 101, and closes both the cooling solenoid valves 203a and 203b (step S11), and the pump-down operation ends.
[0082]
With respect to determination concerning retrieval of refrigerant, for example, by attaching a liquid level determination unit to the accumulator 104, it can be determined using the liquid level determination unit that when an amount of retrieved refrigerant exceeds a certain amount, the retrieval is completed. Alternatively, the determination can be made in the following manner: in the case where liquid refrigerant is retrieved, the suction pressure on the suction side ofthe compressor 101 lowers, since on the suction side ofthe compressor 101, gas refrigerant is sucked; and this is detected by the suction-pressure detection unit 127, and when the pressure reaches a predetermined level, for example, less than 1 kg/cm2, it can be determined that the retrieval is completed.
[0083] (Pump-down operation)
Fig. 7 is a refrigerant circuit diagram illustrating the state of the air-conditioning apparatus 1 according to an embodiment of the present invention during the pumpdown operation.
The pump-down operation of the air-conditioning apparatus 1 will now be explained with reference to Fig. 7.
As illustrated in Fig. 7, the high-temperature and high-pressure gas refrigerant discharged from the compressor 101 passes through the flow-passage switching valve 102, exchanges heat with outdoor air sent by the heat-source-side fan 112 in the heatsource-side heat exchanger 103, and is thus condensed and liquefied. The condensed and liquefied refrigerant passes through the third check valve 105 and the high-pressure pipe 402, and reaches the gas-liquid separator 201 of the relay unit 200.
[0084]
The refrigerant is separated by the gas-liquid separator 201 into gas refrigerant and liquid refrigerant. After flowing from the liquid outlet of the gas-liquid separator 201, the liquid refrigerant passes through the first heat-exchange unit 206, the liquid discharge flow-rate adjustment valve 204 and the second heat-exchange unit 207 in this order, but does not flow into the indoor units 300a and 300b since the first expansion valves 210a and 210b and the second expansion valves 211a and 211b are closed.
[0085]
Furthermore, the heating solenoid valves 202a and 202b are closed, the cooling solenoid valves 203a and 203b are opened, and the refrigerant in the indoor units 300a and 300b is guided by the cooling solenoid valves 203a and 203b into the low-pressure circuit. Thus, the refrigerant in the indoor units 300a and 300b evaporates and gasifies, as a result of which the amount of refrigerant in the indoor units 300a and 300b lowers, and finally the entire refrigerant therein is retrieved.
[0086]
It should be noted that when the indoor units are in the cooling operation, the indoor fans are operated to promote evaporation and gasification of the refrigerant, and are also expected to stir the indoor air; however, it is not necessarily indispensable that the indoor fans are operated. Furthermore, when in the indoor units 300a and 300b, refrigerants are changed into gas liquids, pass through the gas branch pipes 403a and 403b and the cooling solenoid valves 203a and 203b in the first branching portion 240, respectively, and then join each other to flow as single refrigerant, and then the single refrigerant passes through the low-pressure pipe 401.
[0087]
Part of the refrigerant which has passed through the second heat-exchange unit 207 flows into the relay bypass pipe 209. At this time, it is preferable that the liquid discharge flow-rate adjustment valve 204 and the relay bypass flow-rate adjustment valve 205 be opened to the maximum opening degree within a control range, since the refrigerant can be caused to flow into the relay bypass pipe 209 such that it has lowquality, that is, it contains much liquid, thereby shortening time required for retrieval of refrigerant.
[0088]
The liquid refrigerant having flowed into the relay bypass pipe 209 flows into the low-pressure pipe 401, and joins the refrigerant that has passed through the cooling solenoid valves 203a and 203b to flow as single refrigerant. The single refrigerant then passes through the fourth check valve 106 and the flow-passage switching valve 102, and is retrieved into the accumulator 104. When the retrieval of the refrigerant is completed, the compressor 101 is automatically stopped, and all the cooling solenoid valves, that is, both the cooling solenoid valves 203a and 203b in this case, are closed.
[0089]
As described above, the air-conditioning apparatus 1 according to the embodiment includes the leakage detection unit 400 which is provided to detect leakage of refrigerant, and upon the detection of refrigerant leakage by the leakage detection unit 400, the controller 10 closes all the expansion valves, which serve as gates for flowing of refrigerant into the indoor units 300a and 300b, to perform the pump-down operation, and retrieves the refrigerant into the accumulator 104 of the heat source unit 100.
[0090]
To be more specific, if leakage of refrigerant is detected in an indoor unit, the indoor unit is shut down to prevent the refrigerant from leaking from the indoor unit to the outside thereof, and the refrigerant is retrieved from the indoor unit into the heat source unit 100, thereby shortening the time required for completion of retrieval of the refrigerant. In addition, since the indoor unit is shut down by an associated expansion valve to prevent the refrigerant from leaking from the indoor unit to the outside of the indoor unit, it is not necessary to provide an additional valve for preventing leakage of the refrigerant from the indoor unit to the outside thereof, and as a result the configuration can be made simple.
[0091]
Although in the embodiment, the refrigerant is retrieved into the accumulator 104 of the heat source unit 100 during the pump-down operation, retrieval of refrigerant is not limited to such a manner, and it may be retrieved into the compressor 101, a pipe, or another component in the heat source unit 100.
Reference Signs List [0092] air-conditioning apparatus 10 controller 11 storage unit setting unit 20 load capacity detector 26 heatexchangeunit 100 heat source unit 101 compressor
102 flow-passage switching valve 103 heat-source-side heat exchanger
104 accumulator 105 third check valve 106 fourth check valve 107 fifth check valve
108 sixth check valve
112 heat source side fan
114 main pipe
120 heat-source-side heat exchanger unit 126 discharge pressure detector 127 source side flow path adjusting unit
201 gas-liquid separator
202b heating solenoid valve
suction pressure detector 140 heat
141 first controller 200 relay
202a heating solenoid valve
203a cooling solenoid valve
204 liquid discharge flow-rate adjustment
203b cooling solenoid valve valve 205 relay bypass flow-rate adjustment valve
206 first heatexchange unit
207 second heat-exchange unit
208 replay bypass temperature detection unit
209 relay bypass pipe
210a first expansion valve
210b first expansion valve
211a second expansion valve
211b second expansion valve
220 second controller
231 first liquid discharge-pressure detection unit
232 second liquid discharge-pressure detection unit 240 first branching portion250 second branching portion 300a indoor unit 300b indoor unit
301a load-side heat exchanger 301b load-side heat exchanger
303a liquid-pipe temperature detection unit 303b liquid-pipe temperature detection unit 304a gas-pipe temperature detection unit304b gas-pipe temperature detection unit 400 leakage detection unit401 low-pressure pipe 401A return intermediate-pressure pipe 402 highpressure pipe
402A high-pressure gas pipe
402B high-pressure liquid pipe
403a gas branch pipe
403b gas branch pipe
404a liquid branch pipe
404b liquid branch pipe

Claims (4)

  1. An air-conditioning apparatus comprising:
    a heat source unit including a compressor, a flow-passage switching valve, and a heat-source-side heat exchanger;
    a plurality of indoor units including load-side heat exchangers and configured to perform a cooling operation or a heating operation;
    a low-pressure pipe and a high-pressure pipe which connect the heat source unit and each of the indoor units;
    a relay unit including a first branching portion and a second branching portion, the first branching portion including first opening/closing valves and second opening/closing valves, the first opening/closing valves being each configured to connect one end of an associated one of the load-side heat exchangers to the low-pressure pipe when a state of the each of the first opening/closing valve is switched, the second opening/closing valves being each configured to connect the one end of an associated one of the loadside heat exchangers to the high-pressure pipe when a state of the each of the second opening/closing valves is switched, the second branching portion being configured to connect an other end of each of the load-side heat exchangers to a high-pressure liquid pipe through a first expansion valve, and to a return intermediate-pressure pipe through a second expansion valve;
    a leakage detection unit configured to detect leakage of refrigerant; and a controller configured to control the first expansion valve and the second expansion valve, wherein when the leakage detection unit detects leakage of refrigerant, the controller closes all the first and second expansion valves, and performs a pump-down operation to retrieve the refrigerant into the heat source unit.
  2. [Claim 2]
    The air-conditioning apparatus of Claim 1, having a cooling only operation mode in which all the plurality of indoor units perform the cooling operation, and one or more other operation modes, wherein before the controller starts the pump-down operation, in a case where any of the one or more other operation modes is set, the controller switches a state of the flow-passage switching valve to set the cooling only operation mode.
  3. [Claim 3]
    5 The air-conditioning apparatus of Claim 1 or 2, wherein when the leakage detection unit detects leakage of refrigerant, the controller opens all the first opening/closing valves.
  4. [Claim 4]
    The air-conditioning apparatus of Claim 1 or 2, wherein
    10 the plurality of indoor units are provided with respective leakage detection units including the leakage detection unit, and when leakage of refrigerant in one of the plurality of indoor units is detected by a respective one of the leakage detection units, the controller opens one of the first opening/closing valves which is associated with the one of the plurality of indoor units.
    15 [Claim 5]
    The air-conditioning apparatus of any one of Claims 1 to 4, wherein the heat source unit includes an accumulator.
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CN110887166B (en) * 2018-09-10 2021-05-18 奥克斯空调股份有限公司 Air conditioner refrigerant leakage detection method and air conditioner
CN111912079A (en) * 2019-05-09 2020-11-10 珠海格力电器股份有限公司 Fixed-frequency air conditioner, defrosting control method of fixed-frequency air conditioner, computer device and computer readable storage medium
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WO2018003096A1 (en) 2018-01-04
GB2564995B (en) 2021-04-28

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