GB2147668A

GB2147668A - A clutch actuator

Info

Publication number: GB2147668A
Application number: GB08326978A
Authority: GB
Inventors: Robert Jolyon Ball
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1983-10-08
Filing date: 1983-10-08
Publication date: 1985-05-15
Also published as: GB8326978D0; GB2147668B

Abstract

A hydraulic actuator for a friction clutch comprises a stationary coupling (21) for connection to a hydraulic pressure supply, a body (16) driveably connected to a cover (11) of the friction clutch, and a stepped piston (27) slideably supported by the body (16) to selectively disengage the friction clutch under the action of hydraulic pressure. The clutch release force is reacted directly through the body (16) against the cover (11) and no axial end load is therefore transferred to the flywheel (12). <IMAGE>

Description

SPECIFICATION A clutch actuator This invention relates to a hydraulic clutch actuator for use in friction clutches particularly but not exclusively for motor vehicles.

It is already known for example from GB 2 112 490 A to provide a hydraulic clutch actuator concentrically positioned with respect to an engine flywheel and attached to an extension of a gearbox.

The actuator reacts against the fingers of a diaphragm spring by means of a release bearing to disengage the friction clutch.

A disadvantage with this type of actuator is that the actuating force is reacted against the clutch and hence by the thrust bearings fitted to the output shaft of the engine so producing increased wear and a reduction in expected life of these components.

A further disadvantage is that the actuator is difficult to use with a pull type clutch since a coupling device is required to attach the release bearing to the actuator.

According to the invention there is provided a hydraulic actuator for use in friction clutches of the type in which a cover is attached to a flywheel, the cover being driveably connected to a pressure plate biased by spring means to grip a driven plate driveably mounted upon the input shaft of a gearbox, the hydraulic actuator being in use concentrically positioned with respect to the flywheel and operable to move the pressure plate relative to the flywheel against the loading of the spring means to release the clutch and comprising a piston component and a cylinder component which together define a working chamber for fluid, one of said components being adapted to be mounted on the cover and the other being movable relative thereto to release the clutch and hydraulic coupling means on one of said components to connect the chamber to a hydraulic pressure supply, including a coupling body rotatable relative to said components so that in use the coupling body is restrained from rotation with the clutch.

One embodiment of the invention will now be described with reference to the accompanying drawing which shows a hydraulic clutch actuator according to the invention attached to a pull type diaphragm spring friction clutch.

With reference to the drawing there is shown a cover 11 attached by fixing bolts to a flywheel 12 attached to the end of an engine output shaft or crankshaft. A pressure plate 13 is driveably connected to the cover 11 and is biased away from the cover 11 by spring means in the form of a diaphragm spring 14 to grip a driven plate 15 interposed between the flywheel 12 and the pressure plate 13. The driven plate 15 is driveably connected by means of intermeshing splines to the input shaft of a gearbox (not shown).

A hydraulic actuator includes a cylinder component in the form of a cylinder body 16. Means for mounting the cylinder body 16 to the cover 11 include a groove for a circlip retaining ring 17 which holds a shoulder 18 on the cylinder body 16 against the cover 11. The cylinder body 16 rotates with the cover 11 and means such as a peg or key (not shown) may be used to ensure a driving connection.

The bore of the cylinder body 16 is stepped and co-operates by means of two seals 28 with a stepped tubular piston 27 to define an annular working chamber 29. The working chamber 29 is connected to an hydraulic coupling means by an inlet passage 30 passing through a wall of the cylinder body 16.

The hydraulic coupling means includes a coupling body 21 encircling the cylinder body 16 and two rotary seals 23 interposed between the cylinder body 16 and the coupling body 21. The coupling body is connected to a driver controlled hydraulic pressure supply (not shown) by means of a supply pipe 25 spigotted into the coupling body 21 and sealed by a rubber seal 24. The coupling body 21 is axially located by means of a thrust washer 19 spring loaded by a Belleville spring 20 to bias the coupling body 21 against another circlip retaining ring 22 in a groove in the cylinder body 16.

The piston 27 protrudes into the cover 11 to cooperate with the radially inner ends of the fingers 34 of the diaphragm spring 14 by means of a reaction ring 32 attached to the piston 27 by a retaining circlip 33.

Operation of the hydraulic clutch actuator is as follows. Fluid from the driver-controlled hydraulic pressure supply enters the actuator by means of the inlet pipe 25 and passes into the working chamber 29. This causes the piston 27 to be displaced away from the flywheel 12 and disengages the clutch by moving the diaphragm spring fingers 34 in the same direction. The force applied to diaphragm spring 14 by the piston 27 is reacted by the cylinder body 16 against the cover 11 through the abutment of the shoulder 18. Hence, no axial force is transferred from the friction clutch to the engine crankshaft.

1. A hydraulic clutch actuator for use in friction clutches of the type in which a cover is attached to a flywheel, the cover being driveably connected to a pressure plate biased by spring means to grip a driven plate driveably mounted upon the input shaft of a gearbox, the hydraulic actuator being in use concentrically positioned with respect to the flywheel and operable to move the pressure plate relative to the flywheel against the loading of the spring means to release the clutch and comprising a piston component and a cylinder component which together define a working chamber for fluid, one of said components having means for mounting on the cover for rotation therewith and the other being movable relative thereto to release the clutch and hydraulic coupling means on one of said components to connect the chamber to a hydraulic pressure supply, including a coupling body rotatable relative to said components so that in use

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A clutch actuator This invention relates to a hydraulic clutch actuator for use in friction clutches particularly but not exclusively for motor vehicles. It is already known for example from GB 2 112 490 A to provide a hydraulic clutch actuator concentrically positioned with respect to an engine flywheel and attached to an extension of a gearbox. The actuator reacts against the fingers of a diaphragm spring by means of a release bearing to disengage the friction clutch. A disadvantage with this type of actuator is that the actuating force is reacted against the clutch and hence by the thrust bearings fitted to the output shaft of the engine so producing increased wear and a reduction in expected life of these components. A further disadvantage is that the actuator is difficult to use with a pull type clutch since a coupling device is required to attach the release bearing to the actuator. According to the invention there is provided a hydraulic actuator for use in friction clutches of the type in which a cover is attached to a flywheel, the cover being driveably connected to a pressure plate biased by spring means to grip a driven plate driveably mounted upon the input shaft of a gearbox, the hydraulic actuator being in use concentrically positioned with respect to the flywheel and operable to move the pressure plate relative to the flywheel against the loading of the spring means to release the clutch and comprising a piston component and a cylinder component which together define a working chamber for fluid, one of said components being adapted to be mounted on the cover and the other being movable relative thereto to release the clutch and hydraulic coupling means on one of said components to connect the chamber to a hydraulic pressure supply, including a coupling body rotatable relative to said components so that in use the coupling body is restrained from rotation with the clutch. One embodiment of the invention will now be described with reference to the accompanying drawing which shows a hydraulic clutch actuator according to the invention attached to a pull type diaphragm spring friction clutch. With reference to the drawing there is shown a cover 11 attached by fixing bolts to a flywheel 12 attached to the end of an engine output shaft or crankshaft. A pressure plate 13 is driveably connected to the cover 11 and is biased away from the cover 11 by spring means in the form of a diaphragm spring 14 to grip a driven plate 15 interposed between the flywheel 12 and the pressure plate 13. The driven plate 15 is driveably connected by means of intermeshing splines to the input shaft of a gearbox (not shown). A hydraulic actuator includes a cylinder component in the form of a cylinder body 16. Means for mounting the cylinder body 16 to the cover 11 include a groove for a circlip retaining ring 17 which holds a shoulder 18 on the cylinder body 16 against the cover 11. The cylinder body 16 rotates with the cover 11 and means such as a peg or key (not shown) may be used to ensure a driving connection. The bore of the cylinder body 16 is stepped and co-operates by means of two seals 28 with a stepped tubular piston 27 to define an annular working chamber 29. The working chamber 29 is connected to an hydraulic coupling means by an inlet passage 30 passing through a wall of the cylinder body 16. The hydraulic coupling means includes a coupling body 21 encircling the cylinder body 16 and two rotary seals 23 interposed between the cylinder body 16 and the coupling body 21. The coupling body is connected to a driver controlled hydraulic pressure supply (not shown) by means of a supply pipe 25 spigotted into the coupling body 21 and sealed by a rubber seal 24. The coupling body 21 is axially located by means of a thrust washer 19 spring loaded by a Belleville spring 20 to bias the coupling body 21 against another circlip retaining ring 22 in a groove in the cylinder body 16. The piston 27 protrudes into the cover 11 to cooperate with the radially inner ends of the fingers 34 of the diaphragm spring 14 by means of a reaction ring 32 attached to the piston 27 by a retaining circlip 33. Operation of the hydraulic clutch actuator is as follows. Fluid from the driver-controlled hydraulic pressure supply enters the actuator by means of the inlet pipe 25 and passes into the working chamber 29. This causes the piston 27 to be displaced away from the flywheel 12 and disengages the clutch by moving the diaphragm spring fingers 34 in the same direction. The force applied to diaphragm spring 14 by the piston 27 is reacted by the cylinder body 16 against the cover 11 through the abutment of the shoulder 18. Hence, no axial force is transferred from the friction clutch to the engine crankshaft. CLAIMS

1. A hydraulic clutch actuator for use in friction clutches of the type in which a cover is attached to a flywheel, the cover being driveably connected to a pressure plate biased by spring means to grip a driven plate driveably mounted upon the input shaft of a gearbox, the hydraulic actuator being in use concentrically positioned with respect to the flywheel and operable to move the pressure plate relative to the flywheel against the loading of the spring means to release the clutch and comprising a piston component and a cylinder component which together define a working chamber for fluid, one of said components having means for mounting on the cover for rotation therewith and the other being movable relative thereto to release the clutch and hydraulic coupling means on one of said components to connect the chamber to a hydraulic pressure supply, including a coupling body rotatable relative to said components so that in use the coupling body is restrained from rotation with the clutch.

2. An actuator as claimed in Claim 1, wherein said other of the piston and cylinder components is movable under hydraulic pressure in the direction away from the flywheel to release a pull type clutch.

3. An actuator as claimed in Claim 1 or Claim 2, wherein said other component comprises means for co-operation with the fingers of the diaphragm spring of a diaphragm spring clutch.

4. A hydraulic clutch actuator substantially as described herein with reference to the accompanying drawing.

5. A clutch incorporating an actuator as claimed in any preceding claim.