Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
1999-12-22
2001-06-26
Leung, Philip H. (Department: 3742)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S269000
Reexamination Certificate
active
06250891
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a variable displacement compressor. More specifically, the present invention pertains to a controller for controlling the inclination of a swash plate in a variable displacement compressor.
Japanese Examined Patent Publication No. 2-9188 describes a swash plate type variable displacement compressor. The compressor includes a swash plate and pistons. The swash plate, which is located in a crank case (pressure control chamber), integrally moves with a drive shaft and inclines with respect to the drive shaft. The strokes of the pistons vary in accordance with the inclination of the swash plate. When the pressure in the crankcase is relatively high, the inclination of the swash plate is small, which causes the compressor to operate at a small displacement. When the pressure in the crankcase is relatively low, the inclination of the swash plate is large, which causes the compressor to operate at a large displacement. Adjusting the pressure in the crankcase controls the displacement of the compressor. It is important to determine a precise minimum inclination position of the swash plate and to precisely control the inclination of the swash plate. In the compressor described in Publication 2-9188, the swash plate is located between two springs, that is, a displacement restoration spring and an inclination reduction spring. The restoration spring is located between a snap ring fixed on the drive shaft and a hinge ball supporting the swash plate on the drive shaft. The restoration spring continuously contacts the hinge ball and urges the swash plate to incline. The restoration spring increases the inclination of the swash plate from the minimum inclination position and helps restore the displacement. The restoration spring also precisely determines the minimum inclination position of the swash plate, which reduces power consumption.
To maintain a certain minimum inclination of the swash plate, the minimum inclination is determined by the minimum length of the restoration spring (the length when fully compressed). The longer the restoration spring is when uncompressed, the longer it is when compressed. Therefore, the uncompressed length of the restoration spring also determines the distance between the hinge ball and the snap ring at the minimum inclination position of the swash plate. In other words, the longer the uncompressed length of the restoration spring is, the greater the distance between the hinge ball and the snap spring at the minimum inclination position becomes, which increases the axial length of the compressor.
To reduce the distance between the hinge ball and the snap spring at the minimum inclination position, the characteristic of the restoration spring may be changed. For example, the length of the spring may be reduced and the spring may be hardened. However, if the length of the restoration spring is less than the distance between the hinge ball and the snap ring at the maximum inclination, the spring moves along the drive shaft, which may cause noise and damage the compressor.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a compact compressor that prevents producing noise and damaging the compressor.
To achieve the above objective, the present invention provides a variable displacement compressor. The displacement is varied by controlling the pressure in a crank chamber. The compressor includes a drive shaft, a piston for compressing a gas, a swash plate located in the crank chamber, and a displacement restoration spring. The swash plate integrally rotates with the drive shaft. The inclination of the swash plate relative to the drive shaft determines the stroke of the piston. The inclination of the swash plate is varied between a maximum inclination position and a minimum inclination position. The displacement restoration spring urges the swash plate to increase its angle. The restoration spring fails to urge the swash plate when the swash plate is positioned at or near the maximum inclination position. One end of the restoration spring being fixed to a predetermined part of the drive shaft.
REFERENCES:
patent: 4475871 (1984-10-01), Roberts
patent: 5231914 (1993-08-01), Hayase et al.
patent: 5375981 (1994-12-01), Fujii et al.
patent: 5486098 (1996-01-01), Kimura et al.
patent: 5533870 (1996-07-01), Takenaka et al.
patent: 5588807 (1996-12-01), Kimura et al.
patent: 5636973 (1997-06-01), Sonobe et al.
patent: 5857402 (1999-01-01), Hoshida et al.
patent: 5897298 (1999-04-01), Unemura
patent: 5974946 (1999-11-01), Kanou et al.
patent: 6077047 (2000-06-01), Nahai et al.
Kawaguchi Masahiro
Mizutani Hideki
Nakaima Hiroyuki
Yamada Kiyohiro
Fastovsky Leonid
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Leung Philip H.
Morgan & Finnegan , LLP
LandOfFree
Variable displacement compressor having displacement controller does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Variable displacement compressor having displacement controller, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Variable displacement compressor having displacement controller will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2482466