Refrigeration – Automatic control – Preventing – removing or handling atmospheric condensate
Patent
1995-06-15
1997-07-29
Tanner, Harry B.
Refrigeration
Automatic control
Preventing, removing or handling atmospheric condensate
62278, 62509, F25B 4702
Patent
active
056512619
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an operation control device for air conditioner, and particularly relates to measures for controlling the air conditioner during defrosting operation and for controlling the air conditioner just after completion of defrosting operation.
BACKGROUND ART
There has been a conventional air conditioner which is so composed that an indoor unit is connected to an outdoor unit in which a compressor, a four-way selector valve, a thermal-source-side heat exchanger, a motor-operated expansion valve and a receiver are sequentially connected, as disclosed in Japanese Patent Application Laid-Open Gazette No. 4-344085. The air conditioner performs defrosting operation when a fin of the thermal-source-side heat exchanger is frosted in heating operation.
Further, the defrosting operation is executed in a cooling cycle with a non-shown motor-operated expansion valve of the indoor unit and the motor-operated expansion valve of the outdoor unit fully opened together.
However since the above air conditioner is provided with an accumulator on a suction side of the compressor in order to prevent operation in wet condition of the compressor, the motor-operated expansion valves are fully opened in the defrosting operation so that operation performance is decreased due to pressure loss at the accumulator.
If the accumulator is not provided to solve the above problem, since the defrosting operation with the motor-operated expansion valves fully opened, this causes liquid refrigerant condensed by the thermal-source-side heat exchanger to store in the receiver in the case of heavy frost, low open-air temperature or short refrigerant piping. Thus, an amount of heat required for defrosting is lacked so that the liquid refrigerant in the receiver turns back to the compressor. This invites operation in wet condition of the compressor, so that the compressor is under stress. As a result, the reliability of the compressor is reduced.
In view of the foregoing problems, this invention has been made. An object of this invention is to enhance operation performance without any accumulator while avoiding the compressor from operating in wet condition in defrosting operation.
DISCLOSURE OF INVENTION
To achieve the above object, measures instituted in this invention are so composed as to execute defrosting operation while introducing gas refrigerant in a receiver into a main line through a bypass passage.
More specifically, as shown in FIG. 1, a measure instituted in the invention premises an air conditioner comprising a refrigerant circuit (9) which has a main line (9a) in which a compressor (1), a thermal-source-side heat exchanger (3), an expansion mechanism (5) freely adjustable in opening and a used-side heat exchanger (6) are sequentially connected and which is reversibly operable between cooling cycle operation and heating cycle operation.
A receiver (4) is provided in a high-pressure liquid line of the main line (9a) of the refrigerant circuit (9). There is provided a bypass passage (4a), which is connected at one end thereof to the receiver (4) and at the other end to a low-pressure liquid line of the main line (9a) of the refrigerant circuit (9), for bypassing the expansion mechanism (5) to introduce gas refrigerant in the receiver (4) into the low-pressure liquid line.
Further, the bypass passage (4a) is provided with open/shut-off means (SV) for opening and shutting off the bypass passage (4a).
In addition, there is provided defrosting executing means (11) for making the expansion mechanism (5) fully closed and making the open/shut-off means (SV) open according to a defrosting requiring signal in the heating cycle operation and executing defrosting operation in the reverse cycle.
A further measure instituted in the invention comprises initial control means (12) for outputting an initially closing signal to the defrosting executing means (11) so that the open/shut-off means (SV) is closed until a set time passes after the start of the defrosting operation.
A further measure instituted in th
REFERENCES:
patent: 3343375 (1967-09-01), Quick
patent: 4167102 (1979-09-01), Willitts
patent: 4313313 (1982-02-01), Chrostowski et al.
patent: 4987747 (1991-01-01), Nakamura et al.
patent: 5309733 (1994-05-01), Hayashida et al.
Inoue Seiki
Nakajima Hiroto
Sakai Seiji
Daikin Industries Ltd.
Ferguson Jr. Gerald J.
Tanner Harry B.
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