Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2000-05-04
2001-12-25
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S222200, C417S270000
Reexamination Certificate
active
06332757
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control valve for a variable displacement compressor, particular to a displacement control valve for a swash-plate-type variable displacement compressor which is applied to an on-vehicle air-conditioning unit or the like.
2. Related Art
Known displacement control valves for a swash-plate-type variable displacement compressor are disclosed in Japan patent Laid-open No. H. 3-53474, Japan Utility Model Laid-open No. H. 6-17010, and Japan patent Application Laid-open No. H. 8-177735.
The swash-plate-type variable displacement compressor having a control valve basically decreases in discharge displacement with increase of a crank chamber pressure of the compressor and increases in the discharge displacement with the decrease of the pressure. The control valve opens and closes a communication passage communicating a suction port of the compressor with the crank chamber by using a valve element moving in response to a suction pressure of the compressor, thereby controlling the pressure of the crank chamber. Furthermore, the valve element of the control valve is moved toward the open position by the discharge pressure of the compressor to vary the opening-closing switching point of the valve element in response to the discharge pressure. Thus, the control valve controls the fluid delivery in relation to an outer-air condition (a related discharge pressure).
The known displacement control valve is constructed in a way to achieve its object. However, the control valve controls the displacement according to an outer-air condition (for example, a cooling condition). Thus, there should be provided a mechanism for applying the discharge pressure of the compressor to the valve element toward the open position such as an actuating rod, a high-pressure regulating chamber, and a passage for applying the discharge pressure of the compressor to the chamber.
The control valve is not sufficiently satisfied by users, because it is desired to provide a more reliable opening and closing operation of the valve element. Moreover, the control valve has an increased number of parts, requiring an increased man hour for assembling thereof. In addition, a passage configuration for conducting the suction and discharge pressures to related portions of the valve is complicated, limiting an easy arrangement on the body of the compressor.
SUMMARY OF THE INVENTION
In view of the above-described disadvantages, an object of the invention is to provide a control valve of a variable displacement compressor for achieving a displacement control related to an outer-air state. The control valve has a simplified constitution and provides a reliable opening and closing operation of a valve element. The control valve does not cause an increase in number of parts and in assembling man-hour for thereof. In addition, the control valve is mounted in a compressor body and has a simple fluid passage, providing an unlimited arrangement on the compressor body.
For achieving the object, a first aspect of the invention is a control valve for variable displacement compressor which includes:
a valve housing having a communication passage communicating a suction port of the compressor with a crank chamber of the compressor,
a valve element opening and closing the communication passage,
a spring member resiliently biasing the valve element toward its closed position, and
a pressure actuated unit for moving the valve element toward its open position by a suction pressure of the compressor.
The spring member includes a spring made of a temperature responsive material, the spring decreasing in its resilient force in an opening direction of the valve element with increase of an outer-air temperature. The spring member may have a primary spring made of an ordinary resilient material for resiliently biasing the valve element toward the closed position and a correction spring made of a material having a temperature positive characteristic material. The correction spring provides a correction spring force smaller than a primary force of the primary spring in the opposite direction to the primary force. A combined spring force of the primary spring and the correction spring acts on the valve element. Preferably, the correction spring is made of a shape memory alloy.
Preferably, the valve housing is inserted in a recess formed in a body of the compressor to be secured thereto, and the valve housing has an end to which the pressure actuated unit is secured. The pressure actuated unit is positioned to extend externally from the recess. The pressure actuated unit accommodates the spring member therein.
Next, advantageous effects of the invention will be discussed.
The spring force of the spring for resiliently biasing the valve element toward the valve closing position decreases with increase of an-outer temperature. This enables a displacement control related to an environmental condition such as an outer temperature proportional to the compressor discharge pressure. This control valve requires neither an additional rod nor a specific pressure transferring passage, allowing a simple configuration with a reliable operation for opening and closing the valve. The control valve can be produced without increase in parts number and in assembling man-our thereof. In addition, the control valve is integrally attached to the compressor body, allowing a simplified passage configuration. Advantageously, the simplified configuration enables an easy arrangement of other equipment on the compressor body.
The combined spring force of the primary spring exerting a spring force in the valve closing direction and the correction spring giving a spring force in a canceling direction against the primary spring force (the primary spring force is larger than the correction spring force) acts on the valve element. The correction spring can be made of a typical temperature responsive material having a temperature positive characteristic.
The correction spring can be made of a typical shape-memory alloy (SMA) having a temperature positive property.
The correction spring assembled in the pressure actuated unit responds to an outer-temperature, allowing a displacement control related to the outer-air that is an environmental condition.
REFERENCES:
patent: 4747753 (1988-05-01), Taguchi
patent: 5607286 (1997-03-01), Takenaka et al.
patent: 6192699 (2001-02-01), Kato et al.
patent: 0258680 (1988-03-01), None
patent: 0748936 (1996-12-01), None
patent: 62-91672 (1987-04-01), None
patent: 3-53474 (1991-08-01), None
patent: 6-17010 (1994-05-01), None
patent: 8-177735 (1996-07-01), None
Adaniya Taku
Kaneko Morio
Nishimura Kenta
Ohkawara Ichiro
Ota Masaki
Freay Charles G.
Hayes E D
Kabushiki Kaisha Saginomiya Seisakusho
McDermott & Will & Emery
LandOfFree
Control valve for variable displacement compressor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control valve for variable displacement compressor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control valve for variable displacement compressor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2583176