Actuator with an overflow chamber and means for returning the fl

Details Actuator with an overflow chamber and means for returning the fl Actuator with an overflow chamber and means for returning the fl

1996-10-17

1998-08-04

Denion, Thomas E.

Expansible chamber devices

With removal conduit for liquid seepage from expansible chamber

92107, F01B 3100

Patent

active

057877904

DESCRIPTION:

BRIEF SUMMARY
This invention relates to actuators hereinafter referred to as actuators "of the kind specified" in which an annular piston defines an annular working chamber in combination with co-operating cylinder walls, the piston being axially displaceable relative to the cylinder walls by pressurisation of fluid within the working chamber.
Actuators of the kind specified are used for a variety of purposes but are particularly suitable for the actuation of a vehicle clutch release bearing when the actuator can be installed concentrically around a gearbox input shaft of the vehicle.
Problems arise with such actuators in that actuating fluid leaks past seals which seal the piston to the cylinder walls and can then contaminate the associated clutch. Also, on rapid movements of the piston, or sudden depressions in the fluid pressure in the working chamber, air may be drawn into the working chamber past the piston seals.
It is an object of the present invention to provide an actuator of the kind specified which is less susceptible to leakage and to the ingress of air.
Thus according to the present invention there is provided an actuator of the kind specified having sealing means for sealing the piston to the cylinder walls, an overflow chamber which retains any fluid which leaks past the sealing means from the working chamber, and return means for returning fluid from the overflow chamber when the piston is not undertaking a working stroke.
The return means may comprise valve means which controls communication between the working chamber and over flow chamber, the valve means opening up communication between said chambers when the piston is not undertaking a working stroke.
Such an actuator is less susceptible to leakage and air ingress since the overflow chamber retains any fluid which leaks past the seals and the valve means enables the piston to such back fluid into the working chamber from the overflow chamber instead of sucking in air.
The valve means may conveniently be built into the sealing means.
For example, pressurisation of the working chamber may cause deflection of the sealing means to close-off communication between the working and overflow chambers.
Alternatively the return means may comprise a valve means separate from the sealing means, said valve means being arranged to be normally biased to a closed position but being opened on a return stroke of the piston following a working stroke.
The overflow chamber may be defined by diaphragm means in combination with the walls.
In an arrangement in which the piston is displaceable between inner and outer cylinder walls one diaphragm may extend between the piston and the inner cylinder wall and a second diaphragm may extend between the piston and the outer cylinder wall.
In an alternative arrangement the overflow chamber may be defined by a diaphragm means and a portion of the outer cylinder wall, passageway means being provided to direct any fluid which leaks past the sealing means to the overflow chamber.
Where the actuator is to be used to operate a vehicle clutch a clutch release bearing is carried by the piston.
Several embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a radial section through an actuator according to the present invention for the operation of a vehicle clutch;
FIG. 2 shows half of FIG. 1 on a larger scale with half of the actuator seal shown in its open position and the other half in its closed position;
FIG. 3 is a section on line III--III of FIG. 1;
FIG. 4 shows a similar view to FIG. 2 with an alternative sealing/valve arrangement;
FIG. 5 is a radial section through an alternative clutch actuator according to the invention which is constructed largely from plastics material;
FIG. 6 is an enlarged view of the sealing/valve arrangement used in FIG. 5, and
FIG. 7 is a radial section through a further alternative clutch actuator which employs a separate return valve.
Referring to FIG. 1 this shows a vehicle clutch actuator in which an annular piston

REFERENCES:
patent: 2194209 (1940-03-01), Mott
patent: 3293994 (1966-12-01), Napolitano
patent: 3584331 (1971-06-01), D'Hooge
patent: 3972396 (1976-08-01), Bochnak
patent: 4036112 (1977-07-01), Hubschmann
patent: 4509409 (1985-04-01), Reeves
patent: 4870821 (1989-10-01), Harada et al.
patent: 4887515 (1989-12-01), Tabata

Affiliated with

Also associated with

Rating

Actuator with an overflow chamber and means for returning the fl does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Actuator with an overflow chamber and means for returning the fl, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Actuator with an overflow chamber and means for returning the fl will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1166564