# US 9,518,755 B2 · Outdoor unit for air-conditioning apparatus, and air-conditioning apparatus

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- Number: US 9,518,755 B2
- Document ID: US9518755B2
- Status: Granted
- Kind: B2
- Application number: 13/943,098
- Filed: 2013-07-16
- Published: 2014-01-30
- Granted: 2016-12-13
- Earliest claimed: 2012-07-30
- Assignees: Fujitsu General Limited
- Applicants: Fujitsu General Limited
- Inventors: Kotaro Toya; Hideya Tamura; Takahiro Matsunaga; Shinju Watanabe; Takashi Kimura; Yasuhiro Oka; Ken Nakashima
- Web page: https://patentgrep.com/patent/US9518755B2

## CPC

- F25B 49/02: for compression type machines, plants or systems
- F24F 1/0003: characterised by a split arrangement, wherein parts of the air-conditioning system, e.g. evaporator and condenser, are in separately located units
- F24F 1/06: Separate outdoor units, e.g. outdoor unit to be linked to a separate room comprising a compressor and a heat exchanger
- F24F 3/065: {with a plurality of evaporators or condensers}
- F24F 11/30: for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F 11/64: using pre-stored data
- F24F 11/72: for controlling the supply of treated air, e.g. its pressure
- F24F 11/83: by controlling the supply of heat-exchange fluids to heat-exchangers
- F24F 11/84: using valves
- F24F 2110/00: Control inputs relating to air properties
- F24F 2140/12: Heat-exchange fluid pressure
- F24F 2140/20: Heat-exchange fluid temperature
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)

## Abstract

An outdoor unit for an air-conditioning apparatus includes an outdoor heat exchanger; a compressor; a refrigerant pipe configured to couple the outdoor heat exchanger and the compressor with an indoor unit including an indoor heat exchanger; and a control unit that determines whether the heating capacity of the indoor unit performing a heating operation is decreased by the refrigerant stagnated in the indoor heat exchanger.

## Claims

### Claim 1

An air-conditioning apparatus, comprising:
a plurality of indoor units, each of the indoor units comprising an indoor heat exchanger;
an outdoor unit comprising an outdoor heat exchanger, a compressor and a control unit configured to determine whether stagnation of refrigerant in the indoor heat exchanger lowers heating capacity of the indoor unit performing a heating operation; and
a refrigerant pipe configured to couple the outdoor heat exchanger and the compressor with each of the indoor units, wherein
the outdoor unit further comprises a high-pressure sensor that is disposed at the refrigerant pipe coupling the compressor with the each of the indoor units, the high-pressure sensor configured to detect a pressure of refrigerant that flows from the compressor to the indoor heat exchanger,
each of the indoor units further comprises a refrigerant temperature sensor that is disposed at the refrigerant pipe coupling the indoor heat exchanger with the outdoor heat exchanger, the refrigerant temperature sensor configured to detect an indoor unit side refrigerant temperature of the refrigerant that is flowed out from the indoor heat exchanger, and
the control unit is configured to:
calculate a high-pressure saturation temperature based on the pressure detected by the high-pressure sensor;
calculate an average indoor unit side refrigerant temperature based on the indoor unit side refrigerant temperatures detected by each of the refrigerant temperature sensors,
determine that the stagnation of the refrigerant in the indoor heat exchanger lowers the heating capacity of the indoor unit performing a heating operation when a temperature difference between the high-pressure saturation temperature and the average indoor unit side refrigerant temperature is a predetermined value or more, the high-pressure saturation temperature is a first predetermined temperature or more and the indoor unit side refrigerant temperature detected by at least one of the refrigerant temperature sensors is a second predetermined temperature or less; and
perform refrigerant stagnation elimination control when the control unit determines that the stagnation of the refrigerant in the indoor heat exchanger lowers the heating capacity of the indoor unit performing the heating operation.

### Claim 2 (depends on 1)

The air-conditioning apparatus according to claim 1, wherein the outdoor unit further comprises a flow rate adjustment unit configured to adjust the flow rate of the refrigerant flowing in the refrigerant pipe, and
the control unit increases the flow rate of the refrigerant from the indoor heat exchanger by controlling the flow rate adjustment unit during the refrigerant stagnation elimination control.

### Claim 3 (depends on 2)

The air-conditioning apparatus according to claim 2, wherein the flow rate adjustment unit is an expansion valve.

### Claim 4 (depends on 3)

The air-conditioning apparatus according to claim 3, wherein the control unit increases the flow rate of the refrigerant from the indoor heat exchanger by increasing the degree of opening of the expansion valve by a predetermined amount of change during the refrigerant stagnation elimination control.