GB2327732A

GB2327732A - Clutch release bearing actuating mechanism

Info

Publication number: GB2327732A
Application number: GB9816115A
Authority: GB
Inventors: Ulrich Husse
Original assignee: Mannesmann Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1997-07-23
Filing date: 1998-07-23
Publication date: 1999-02-03
Anticipated expiration: 2018-07-23
Also published as: FR2766533A1; GB2327732B; DE19731612A1; DE19731612B4; FR2766533B1; GB9816115D0

Abstract

A clutch 15 release bearing actuating mechanism 16 comprises a guide sleeve 3, fixed on a wall of a gearbox 2, on which a release bearing 5 is slidably displaceable. The release bearing 5 is engaged in aperture 6 for actuation by a lever 1 having a discrete planar contact surface 8 which contacts a discrete spherical contact surface 7 on the release bearing 5. Surfaces 7, 8 transfer a thrust load from the lever 1 to the bearing 5 and thereby to a diaphragm spring to release the clutch 15. Lever 1 is coupled at one end with a ball-and-socket joint 9, 10 and the force is applied at the other end to effect clutch 15 release. Between the two ends the lever 1 has a substantially planer region which conforms in shape to a shape of a transverse wall of the gearbox 2.

Description

1 2327732 ACTUATING MECHANISM FOR FRICTION CLUTCHES The present invention

relates to an actuating mechanism for a friction clutch in a motor vehicle.

An actuating mechanism is known, for example, from DE 297 00 508 Ul. This known mechanism is composed of a rolling-element bearing carried on a thrust member which is guided on a sleeve fixed to a gearbox. To displace the thrust member along the guide sleeve a lever with an aperture in a central region encompassing the sleeve and the thrust member is used. This lever is pivotably connected to the gearbox at one end and force is applied to its opposite end. The actuating lever has to perform a minimum pivotal movement so that the clutch is released completely. Since the release lever is connected to the gearbox at one end, forming the pivot joint, and the actuating force is introduced at the opposite end, the axial path covered by the free end is inevitably greater than the release path required for the release bearing. Where a friction clutch does not have automatic adjustment for wear, the diaphragm spring loading the pressure plate tends to be tilted as a result of the wear of the fliction linings. The tongues of the spring then act on the release bearing and thrust member to displace these components in the direction of the gearbox, causing the release lever to pivot in the same direction. Consequently there must be adequate space to allow the release lever to operate and to accommodate for wear.

The space available in the engine compartment of the vehicle decreases as vehicles continue to be perfected, with a simultaneous increase in the diversity of fittings. Hence the 2 requirement for all components to be as compact and fight as possible. Motor vehicles in the so-called compact class are also fitted with high performance engines nowadays. The engine and gearing have to be installed transversely to obtain the compact structure of such a vehicle. Hence the particular requirement for this engine/gearing unit to be designed as short as possible axially. Even a few millimetres can make all the difference as to whether or not an engine/gearing unit can be used in a certain vehicle.

An object of the invention is to provide an improved actuating mechanism of the type described above so that the space required for the release lever can be reduced without the need to change the release path of the clutch.

According to the invention there is provided an actuating mechanism for a friction clutch of a motor vehicle; said mechanism comprising a thrust member guided for displacement on a guide sleeve connected to a gearbox and a lever for effecting the displacement of the thrust member, wherein the lever has one end region pivotably connected to the gearbox with a pivot joint, another end region to which force is applied and an intermediate region in operative engagement with the thrust member to cause the thrust member to be displaced to effect release of the clutch, when force is applied to the other end region of the lever, wherein the intermediate region of the lever and the thrust member are provided with contact surfaces one of which is curved and the other of which is rectilinear and the lever has one or more distinct rectilinear contact surfaces extending in a difFerent direction to an adjacent surface of the intermediate region or one or more curved surfaces on the intermediate region of the lever.

3 Preferably the lever has a rectilinear contact surface in the area where it makes contact with the thrust member of the releasing device. The rectilinear contact surface extends in a non-radial direction relative to the axis of rotation of the clutch and the axis of the sleeve aligned therewith when the clutch is coupled and operating and in a different direction to adjacent surfaces of the intermediate region.

The centre point of contact between the contact surfaces of the lever and the thrust member is offset from the axis of the sleeve and moves to become offset in the other sense as the lever pivots to release the clutch. The curved and rectilinear contact surfaces provides slight friction when the lever pivots and a slightly displacement of the contact centre point from the axis. By restricting the contour of the lever contact surface to a discrete position only a few functional requirements are imposed on the remainder of the lever and the shaping the lever can start immediately outside of the contact surface. Thus the lever can be adapted to the structural and movement space defined by, on the one hand, by the clutch housing and, on the other hand, the gearbox.

The intermediate region of the lever preferably possesses an aperture into which the thrust member extends and the lever may have rectilinear contact surfaces on lateral portions bordering the aperture which engage with spherical contact surfaces of the thrust member. This has a further advantage in that the size of the aperture in the release lever required to receive the thrust member or releasing device can be kept to a minimum. The thrust member and releasing device only goes into the aperture in the obliquely inclined 4 release lever when the clutch is in the decoupled state. The aperture, which is of a reduced size compared to the state of the art, means that the resistance torque of the release lever increases. This keeps the elastic deflection at a low level.

The shape of the release lever should advantageously change at both limits of the or each contact surface. This would allow the release lever to be given a shape which allows it to be as close as possible to the clutch housing at the pivot joint, whilst the other end connected to an actuating device can be guided in the other axial direction, so that angular displacement of the lever during actuation of the clutch may be reduced.

A particular advantage can be gained if the contour of the release lever in the region of its other end is adapted to the internal contour of the gearbox. A particular advantage can be gained if the other end of the release lever runs approximately parallel to an internal transverse wall of the gearbox when the clutch has maximum wear. This type of arrangement can bring a saving of axial length of about 3.5 mm compared to conventional arrangements. A further reduction can be made in conjunction with a clutch equipped with automatic adjustment for wear.

The invention may be understood more readily, and various other aspects and features of the invention may become apparent, from consideration of the following description.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:

Figure 1 is an axial section through an actuating mechanism constructed in accordance with the invention; Figure 2a is a schematic representation of the kinematic relationships of a known actuating mechanism.

Figure 2b is a representation corresponding to Figure 2a and showing an optimised relationship; and Figure 2c is a representation corresponding to Figures 2a and 2b and showing the relationship with the actuation mechanism constructed in accordance with the invention and shown in Figure 1.

As shown in Figure 1, a fliction clutch 15 is arranged in a gearbox 2 of a motor vehicle. The clutch 15 is composed of a clutch housing 12, carrying a diaphragm spring 13 which acts on a pressure plate 11. The pressure plate 11 acts upon the ffiction linings of a ffiction disk (not shown) and presses them against a flywheel of an internal combustion engine (likewise not shown). The clutch housing 12 is engaged with the flywheel, for rotation therewith. An actuating mechanism 16 for operating the ffiction clutch 15 is mounted in the space defined within the housing of the gearbox 2, and between a transverse wall of the gearbox 2 and the diaphragm spring 13. The actuating mechanism 16 is composed of a guide sleeve 3 coaxial with the rotation axis on which a flanged thrust 6 member 5 is slidably guided for axial movement. The sleeve 3 is fixed to the transverse wall of the gearbox 2 with screws 4 engaged in bores in a flange 3a of the sleeves 3. A rollingelement release bearing is mounted on the clutch side of the flange of the thrust member 5. The bearing is composed of flanged inner and outer rings with balls spaced apart with a cage therebetween. The flanged beating inner ring engages directly on spring tongues 1Y of the diaphragm spring 13 of the clutch 15 and the flanged bearing outer ring is supported on the flange of the thrust member 5. The member 5 along with the bearing can be moved along the sleeve 3 towards the clutch 15 in response to the movement of a lever 1 to effect decoupling and release of the clutch 15. The lever 1 is pivotably supported at one end region with the aid of a ball-and-socket joint 9, 10. This joint is formed by a head 10 of a peg fitted to the transverse wall of the gearbox 2 and a socket 9 formed at the one end region of the lever 1. The head 10 is retained in the socket 9 with the aid of a detachable spring. The ball-and-socket 9, 10 is as close as possible to the clutch housing 12. The other end region of the lever 1 is subjected to thrust force from a device (not shown) such as a piston and cylinder unit in response to the depression of a clutch pedal. When the lever 1 is subjected to thrust force it pivots about the ball-and-socket joint 9, 10.

The lever 1 has an intermediate region between its end regions in which there is an aperture 6 which receives and axial region of the thrust member 5 on the side of the flange opposite the bearing and an axial region of the inner guide sleeve 3. The lever 1 has rectilinear portions alongside the aperture 6 deflected and offset from adjacent portions of the lever 1 to provide separate discrete rectilinear or planar contact surfaces 8 which establish contact with curvilinear contact surfaces 7 formed by corresponding confronting 7 portions of the thrust member 5. In the position represented in Figure 1 the clutch 15 is coupled and the contact surfaces 7,8 of the thrust member and the lever 1 contact one another over non-radial contact regions intersecting a central plane containing the axis of rotation at an angle and these contact regions have central points which are offset and displaced as at 14 to the central axial plane.

As mentioned, the contour of the lateral portions of the lever 1 changes outside the contact surfaces 8. More particularly, the contact surfaces 8 smoothly merge into portions parallel to the transverse wall of the gearbox 2 and radial to the axis of rotation in the upward direction towards the force receiving end of the lever 1. These parallel portions of the lever 1 merge outside the apertures 6 back into the main body of the lever 1 which is then cranked to follow the contour of the transverse wall of the gearbox 2 and this region runs into the end region of the lever 1 to which force is applied which extends parallel to the transverse wall of the gearbox 2 and radial to the axis of rotation. In the other direction, towards the ball-and-socket joint 9, 10 the contact surfaces 8 are cranked inwardly relative to the gearbox 2 to run into portions of the lever 1 parallel to the transverse wall of the gearbox 2 and radial to the axis of rotation. These parallel portions are then cranked out away from the gearbox 2 to merge into the main body of the lever and which forms an inclined region leading to the end region with the socket 9.

When the lever 1 is operated to release the clutch 15 the contact surfaces 7, 8 are displaced so their central contact point moves through the central axial plane to adopt a position ofiEset (as at 14) from the central axial plane in the other direction.

8 The position of the diaphragm spring 13 represented as unsectional corresponds to the position when the clutch 15 is engaged and where the fliction linings have worn to the maximum extent. The far left sectional view of the diaphragm spring 13 corresponds to the state when the clutch 15 is released.

By adapting the release lever 1 to the contour of the gearbox 2 it is possible to keep the central aperture 6 in the release lever 1 small, because the thrust member 5 only enters the aperture 6 fully in the uncoupled state. However, this only requires a slight pivoting movement of the release lever 1. The displacement from the central plane containing the axis of rotation of the contact 7,8 Le, the change in the central point of the contact surfaces 7,8 in the coupled and uncoupled state is small.

A conical biasing spring 17 is arranged between the sleeve flange 3a and the release lever 1 to further optimise space. The conical biasing spring 17 has the advantage that it only requires a little space when flat.

Figures 2a to 2c represent the kinematic relationship of the contact surfaces 7,8 of the lever 1 and the thrust member 5 inside the gearbox 2. All three figures apply to an identical friction clutch 15 and consequently attain the same release path. Figure 2a refers to a state of the art actuating mechanism, with symmetrical movement and a contact surface 8 wholly aligned with the lever 1 and extending non radially when the clutch is released or coupled. A path of 26.864 mm must be left between the gearbox 2 and the centre point of the contact 9 surfaces 7,8 correspond to the limiting positions of the releasing mechanism 16 to allow full release and to take account of movement after wear. Here the displacement from the axis of the centre point of contact surfaces 7,8 between the release lever 1 and the member 5 is 3.136 mm: these displacements are set symmetrically to the central axis. By having the contact surface 8 of the release lever 1 with the engaged clutch 15 aligned with the lever 1 and parallel to the gearbox 2, as shown in Figure 2b the distance between the centre point of the contact surfaces 7, 8 and the gearbox 2 with the clutch released is reduced to 23.919 mm. This would mean a displacement of the centre point of the contact surfaces 7,8 from the axis of 3.119 nun which would only occur on one side of the central axis. By adopting the construction and measures represented in Figure 1 the dimension required inside the gearbox is reduced even more to 23.448 mm as shown in Figure 2c. The displacement of the centre point of the contact surfaces 7,8 (14 in Figure 1) has the dimensions as shown.

The provision of the planar contact surface 8 on the lever 1 which is separate to the other adjacent regions and runs in a diffierent direction thus provides significant advantages. It is however feasible to reverse the contact surface 7,8 so that the planar surface 7 is on the thrust member 5 and the curved surface 8 is on the lever 1.

List of reference numerals 1 Release lever 2 Gearbox 3 Guide sleeve 3a Sleeve flange 4 Screws Thrust member 6 Aperture 7 Contact surface 8 Contract surface 9 Socket Ball head 11 Pressure plate 12 Clutch housing 13 Diaphragm spring 14 Displacement from axis of centre point contact surfaces 7,8 Friction clutch 16 Actuating mechanism 17 Biasing spring

Claims

1. An actuating mechanism for a ffiction clutch (15) of a motor vehicle; said mechanism comprising a thrust member (5) guided for displacement on a guide sleeve (3) connected to a gearbox (2) and a lever (1) for effecting the displacement of the thrust member (5), wherein the lever (1) has one end region pivotably connected to the gearbox with a pivot joint (9,10), another end region to which force is applied and an intermediate region in operative engagement with the thrust member (5) to cause the thrust member (5) to be displaced to effect release of the clutch when force is applied to the other end region of the lever (I). wherein the intermediate region of the lever (1) and the thrust member (5) are provided with contact surfaces (7,8) one of which is curved and the other of which is rectilinear and the lever (1) has one or more distinct rectilinear contact surfaces (8) extending in a different direction to an adjacent surface of the interTnediate region or one or more curved surfaces on the intermediate region of the lever (1).

2. A mechanism according to claim 1, wherein the or each contact surface (8) on the lever is rectilinear.

3. An actuating mechanism according to claim 1 or 2, wherein at least portions of the interTnediate and other end regions of the lever (1) are shaped to extend in close proximity to a transverse wall of the gearbox (2).

12

4. An actuating system according to claim 3, wherein the other end region of the lever (1) predominantly runs approximately parallel to a confronting surface of the transverse wall of gearbox (2) when the clutch (15) has maximum wear.

5. An actuating mechanism according to claim 1, 2,3, or 4 wherein the intermediate region of the lever possesses an aperture (6) in to which the thrust member (5) extends and the lever has rectilinear contact surfaces (8) on lateral portions bordering the aperture which engage with spherical contact surfaces of the thrust member.

6. An actuating mechanism according to claim 5, wherein the contact surfaces (8) on the lateral portions extend in a different direction to adjacent portions of the intermediate region ofthelever.

7. An actuating mechanism according to any one of the preceding claims wherein the thrust member (5) carries a rolling-element bearing which is adapted to engage with a diaphragm spring (13) of the clutch (15).

8. An actuating mechanism according to any one of the preceding claims wherein the pivot joint is a ball-and-socket joint (9,10) disposed closely adjacent a housing (12) of the clutch (15).

9. An actuating mechanism for motor vehicle clutches substantially as described with reference to and as illustrated in Figure 1 of the accompanying drawings or Figure 1 of the 13 accompanying drawings and with other characteristics of Figure 2c of the accompanying drawings.