GB2410778A

GB2410778A - Annular clutch actuator with deep drawn single piece cylinder

Info

Publication number: GB2410778A
Application number: GB0402419A
Authority: GB
Inventors: Yannick Frank Theop Christiaen
Original assignee: Automotive Products France SA
Current assignee: Automotive Products France SA
Priority date: 2004-02-04
Filing date: 2004-02-04
Publication date: 2005-08-10
Also published as: GB0402419D0

Abstract

A concentric slave cylinder has an annular piston 11 which slides in an annular bore defined between inner and outer walls 15a, 15b of a cylinder formed by a deep drawing process. The piston 11 and the inner and outer walls 15a, 15b form an annular actuating chamber 30 into which fluid is introduced to displace the piston 11 relative to the cylinder to move a clutch release bearing 14 carried by the piston 11 for engagement with associated clutch release fingers of a clutch. The cylinder is formed from a single-piece metal component which defines the inner and outer cylinder walls 15a, 15b and an end wall 15c of the cylinder, the single-piece cylinder having bayonet-type connections which are received in slots in a mounting block 19 that attaches the cylinder to a transmission or clutch housing of a vehicle.

Description

24 1 0778

CLUTCH ACTUATORS

This invention relates to clutch actuators and in particular to so-called concentric slave cylinders (CSCs) [hereinafter referred to as of the type described] in which an annular piston slides in sealed contact with an annular bore defined between inner and outer walls of a cylinder to provide an annular actuating chamber into which fluid is introduced to displace the piston relative to the cylinder to move a clutch release bearing carried by the piston for engagement with associated clutch release fingers of the associated clutch.

CSCs of the type described are well known and generally a very effective means of actuating a vehicle clutch since the CSC can conveniently surround the input shaft of an associated transmission into which the clutch is to transmit drive.

There is a requirement to reduce the manufacturing cost and weight of such CSCs and to provide a CSC design which is easy to install in its operational position on the vehicle.

Thus in accordance with the present invention there is provide a CSC of the type described in which the cylinder is formed as a single-piece metal component which defines the inner and outer cylinder walls and an end wall of the cylinder, the single- piece cylinder being received in a mounting block for attachment to an associated vehicle.

Preferably the single-piece cylinder is formed by a deep drawing process if formed from steel or by a back extrusion process if formed from aluminium.

Using these methods of forming the cylinder enables the thickness of the cylinder walls to be significantly reduced thus saving weight.

In a preferred arrangement the single-piece metal cylinder is received in a cylindrical recess in the mounting block. The single-piece metal cylinder may be held in the recess in the mounting block by a bayonettype attachment. This bayonet-type attachment may be formed by a radially projecting inlet connection for the cylinder bore which is received in a bayonet slot cut in the walls of the cylindrical recess in the mounting block.

Preferably the mounting block also receives the end of a coil spring which surrounds the metal cylinder to provide a pre-load for the associated clutch release bearing.

The invention also provides a CSC of the type described in which the cylinder is detachably mounted in a mounting block for attachment to an associated vehicle.

Preferably the cylinder is attached to the mounting block by a bayonettype attachment. This bayonet attachment may comprise a radially projecting inlet connection for the cylinder bore which is received in a bayonet slot cut in the walls of a cylindrical recess in the mounting block into which the cylinder is inserted.

One embodiment of the present invention will now be described, by way of example only, with reference to accompanying drawings in which: Figures 1 and 2 show axial cross sections through a CSC in accordance with the present invention in the retracted and extended positions respectively; Figure 3 shows a perspective view of a single-piece metal cylinder used in the CSC of Figures 1 and 2, and Figure 4 shows a perspective view of the complete CSC with its bayonet-type attachment to its mounting block.

The concentric slave cylinder 10 shown in Figures 1 and 2 basically comprises a piston 1 1 which slides in a bore 12, the piston being sealed to the bore by a seal 13.

The piston carries a clutch release bearing 14 whose outer race 14a operates associated clutch release fingers (not shown) in the normal manner. The inner race 14b of bearing 14 carries a spring guard 31 and a seal 32.

In accordance with the present invention the bore 12 is formed in a one piece metal cylinder body 15 which has an inner wall 15a, an outer wall 15b and an end wall 15c.

This single-piece metal cylinder body 15 may be formed from a sheet of steel by a deep drawing process or from a billet of aluminium using a back extrusion process.

The single-piece metal cylinder body is shown most clearly in Figure 3. It has an inlet connection in the form of a tube 16 which is welded into a hole 17 machined into the body. This inlet tube 16 is subsequently connected with a conduit (not shown) through which the CSC receives hydraulic fluid from an associated master cylinder (not shown) to pressurise a working chamber 30 formed between the piston 11 and body 15 in the normal manner.

The single-piece metal cylinder body 15 is received in a cylindrical recess 18 formed in a mounting block 19. The mounting block may be formed from metal or plastics material and includes two or more radially projecting mounting lugs 19a which include fastening holes 20 through which bolts or other suitable fasteners may be passed to secure the mounting block 19 to a transmission or clutch housing of the associated vehicle.

The single-piece cylinder body 15 is held in the mounting block 19 by the inlet tube 16 which engages in a bayonet attachment slot 21 formed in the walls of the cylindrical recess 18 of the mounting block. If desired, one or more additional projections may be formed on the cylinder at circumferentially space locations which engage additional corresponding slots in the walls of recess 18 to provide a more balanced attachment of the cylinder to the block 19.

A coil spring 22 surrounds the cylinder body 15 and is received in a recess 23 formed in the mounting block. This coil spring provides a preload on the clutch release bearing 14 when the CSC is in its retracted clutch released condition shown in Figure 1.

As will be appreciated, the assembly of the CSC is greatly facilitated by the bayonet attachment of the cylinder body into the mounting block 19. The CSC may be fully assembled prior to its attachment to the vehicle or the mounting block may be attached to the vehicle first and then the cylinder body etc. attached to the mounting block using the bayonet fastening.

In accordance with a second aspect of the present invention the bayonet attachment of the cylinder into the mounting block may be used on a single or multiple piece cylinder body.

Claims

1. A CSC of the type described in which the cylinder is formed as a single-piece metal component which defines the inner and outer cylinder walls and an end wall of the cylinder, the single-piece cylinder being received in a mounting block for attachment to an associated vehicle.

2. A CSC according to claim 1 in which the single-piece cylinder is formed by a deep drawing process if formed from steel or by a back extrusion process if formed from aluminium.

3. A CSC of the type described in which the cylinder is detachably mounted in a mounting block for attachment to an associated vehicle.

4. A CSC according to any one of claims 1 to 3 in which the cylinder is held in a recess in the mounting block by a bayonet-type attachment.

5. A CSC according to claim 4 in which the bayonet-type attachment is formed by a radially projecting inlet connection for the cylinder bore which is received in a bayonet slot cut in the walls of the cylindrical recess in the mounting block.

6. A CSC according to claim 5 in which one or more additional radial projections are formed at circumferentially spaced locations on the cylinder which engage additional corresponding slots in the walls of the recess.

7. A CSC according to any one of claims 1 to 6 in which the mounting block also receives the end of a coil spring which surrounds the metal cylinder to provide a pre-load for the associated clutch release bearing.

8. A CSC of the type described constructed and arranged substantially as hereinbefore described with reference to and as shown in the accompanying drawings.