Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2000-04-06
2001-05-22
Tapolcai, William E. (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S225000, C236S09200D
Reexamination Certificate
active
06233956
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an expansion valve equipped in an air conditioner mounted on a vehicle for controlling the flow of a refrigerant travelling to an evaporator, wherein a bypass passage formed to the expansion valve is opened by an electromagnetic valve when the expansion valve is in a closed state, circulating a minimum amount of refrigerant so as to secure the lubrication of a compressor and the like constituting the refrigerant cycle.
DESCRIPTION OF THE RELATED ART
The expansion valve equipped in an air conditioner of a vehicle includes a valve chamber for controlling the flow of the refrigerant into which the refrigerant being supplied from a compressor is introduced, a first passage for guiding the refrigerant exiting the valve chamber toward an evaporator, and a second passage through which the refrigerant returning from the evaporator travels. A shaft-like valve drive member having a heat sensing function is equipped in the second passage for sensing the refrigerant temperature flowing thruogh the passage and for transmitting the sensed temperature to a valve drive mechanism called a power element. Further, the distance between a valve means and a valve seat of the expansion valve is operated so as to control the flow of the refrigerant.
SUMMARY OF THE INVENTION
According to the above-mentioned type of expansion valves, when the air-conditioning load is low, the flow path between the valve means and the valve seat is nearly closed, and only very little refrigerant flows through the valve. A lubricating oil is included in the refrigerant, which lubricates the sliding units of the compressor and the like constituting the refrigeration cycle.
Therefore, if the flow of the refrigerant circulating in the refrigeration cycle is reduced greatly, it may cause malfunction of the equipment constituting the refrigeration cycle such as the compressor due to insufficient lubrication.
Accordingly, the present invention aims at providing an expansion valve capable of circulating a minimum amount of refrigerant even when the air-conditioning load is low.
In order to achieve the above object, the present invention provides an expansion valve equipped in an air conditioner for decompressing and expanding a refrigerant and supplying the same to an evaporator, wherein a valve body comprising a first passage through which said refrigerant being transferred to said evaporator travels, a second passage through which said refrigerant returning from said evaporator toward a compressor travels, and a valve chamber equipped in said first passage into which the refrigerant enters, is further equipped with a bypass passage for supplying said refrigerant from said valve chamber to said compressor, and an electromagnetic valve for opening and closing said bypass passage, said electromagnetic valve being operated so as to open said bypass passage according to the output from a sensing means for detecting a predetermined air-conditioning load.
Preferably, the bypass passage communicates the valve chamber and the first passage. Moreover, the bypass passage communicates the valve chamber and the second passage.
In a more preferable example, the sensing means is a pressure sensor or a temperature sensor.
Moreover, the expansion valve according to the present invention is equipped in an air conditioner for decompressing and expanding a refrigerant and supplying the same to an evaporator, said expansion valve including a valve body comprising a first passage through which said refrigerant being transferred to said evaporator travels and a second passage through which said refrigerant returning from said evaporator travels, a valve chamber equipped in said first passage into which said refrigerant enters, a bypass passage for communicating said valve chamber and said first or said second passage, an electromagnetic valve for opening or closing said bypass passage, and a pressure switch equipped to said second passage, wherein said pressure switch detects the reduction of pressure of said refrigerant inside said second passage, and operates said electromagnetic valve to open said bypass passage.
Preferably, the electromagnetic valve is equipped with a plunger and a pilot valve being opened and closed by the end portion of said plunger, said pilot valve being operated to open or close a conduit equipped within said bypass passage.
The expansion valve according to the present invention defined as above realizes a valve which is capable of supplying a minimum amount of refrigerant to the refrigeration cycle even when the valve is nearly or completely closed.
REFERENCES:
patent: 3150502 (1964-09-01), Tucker
patent: 3363433 (1968-01-01), Barbier
patent: 3839879 (1974-10-01), Redfern et al.
patent: 4688390 (1987-08-01), Sawyer
patent: 4741178 (1988-05-01), Fujiu et al.
patent: 5588590 (1996-12-01), Sakakibara et al.
patent: 5653118 (1997-08-01), Cocchi et al.
patent: 5836438 (1998-10-01), Ohishi et al.
patent: 6053417 (2000-04-01), Hotta et al.
Katayama Toshiharu
Watanabe Kazuhiko
Fujikoki Corporation
Rader Fishman & Grauer
Tapolcai William E.
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