GB2044385A

GB2044385A - Clutch Release Mechanisms

Info

Publication number: GB2044385A
Application number: GB7909100A
Authority: GB
Original assignee: Ransome Hoffmann Pollard Ltd
Current assignee: Pilgrim House Group Ltd
Priority date: 1979-03-15
Filing date: 1979-03-15
Publication date: 1980-10-15
Also published as: GB2044385B

Abstract

A clutch release mechanism has a rolling-element bearing (10) supported by a thrust sleeve or hub (26) to which external force (B) is applied. The sleeve (26) is made from a resilient low-friction plastics material and is formed with a shallow recess (36) locating the bearing (10). Axial slots (30) are provided in the sleeve (26) at one end nearest the clutch and whereat there is a raised rim (24) so as to produce a series of elongate spring-like fingers (32) which permit the bearing (10) to be snap-fitted directly to the sleeve (26). <IMAGE>

Description

SPECIFICATION Improvements in Clutch Release Mechanisms The present invention relates in general to bearing assemblies and, more particularly, to clutch release mechanisms incorporating such assemblies.

It is well known to employ a rolling element bearing assembly as a thrust bearing in the clutch release mechanism for a vehicle clutch. Normally the bearing assembly is a radial or angular contact ball bearing assembly and is fixed to a thrust sleeve acted on by an actuated lever. The sleeve and bearing assembly are guided for axial sliding, usually on a further stationary sleeve or spigot or the like on the clutch housing. The bearing assembly contacts a release part, such as a diaphragm spring or analogous springs or a mechanical linkage acting on such a spring or springs. Axial movement of the thrust sleeve then effects release or engagement of the clutch.

Although it is known to make the thrust sleeve integral with one of the bearing races the more usual arrangement is to make an interference fit between the inner bearing race and the thrust sleeve. This press fitting necessitates close tolerances in the dimensions of the interengaging surfaces and consequently accurate machining is required. Also, special assembly equipment is often employed to mate the bearing assembly with the thrust sleeve to preclude damage.

A general objection of the invention is to provide an improved form of clutch release mechanism of the aforementioned kind.

According to the present invention, there is provided a clutch release mechanism composed of a rolling element bearing attached to a thrust sleeve or hub, as a snap-fit.

In a preferred arrangement the sleeve or hub is relieved, as with slots to provide at least in part for resilient deflection in fitting the bearing thereto. A shallow recess in the sleeve or hub may accommodate one or both the bearing raceways.

It is presently preferred to fabricate the sleeve or hub from a synthetic plastics material with low sliding friction characteristics and to provide slots in one end region of the sleeve thereby to produce a series of deflectable, separate fingers or elements. The sleeve or hub can be additionally shaped to facilitate location of the bearing during assembly and to enhance the resilient deflection of the elements as the bearing is snap-fitted to the sleeve or hub.

To aid understanding of the invention, Figures 1 to 4 of the accompanying drawings are sectional side views of typical known forms of clutch release mechanisms.

For convenience, like reference numerals denote like and analogous parts throughout the accompanying drawings. In Figure 1, the mechanism employs an angular-contact rolling element bearing 10 with an outer ring or raceway 1, an inner ring or raceway 2 and rolling elements or balls 5 therebetween. A conventional cage 3 separate and locates the balls 5. The inner raceway 2 is press-fitted onto a shouldered portion 8 of a thrust sleeve or hub 6. The outer raceway 1 is formed with an integral radiallyinwardly extending end region 20 and a complementary cover 4 is located to the raceway 1 to shield the interior of the bearing 10. Duriny use, and as is known, axial thrust (arrow A) displaces the sleeve 6 and is transmitted via the outer raceway end region 20 to a clutch release part (not shown).

In Figure 2, the sleeve 6 is formed with a groove or track for the balls 5 of the angular contact bearing 10 and hence itself constitutes in part 8 the inner bearing raceway 25. Although this integral construction is advantageous, it is costly to fabricate since the sleeve 6 needs to be fabricated from high quality bearing steel since it provides in part the inner bearing raceway.

In Figure 3 the mechanism employs a radialcontact bearing 10 and a separate ring 21 is fitted to the outer raceway 1 to constitute the end region 20.

In Figure 4, a radial-contact bearing 10 is transposed to adopt a thrust-bearing mode and the bearing 10 is again press-fitted or keyed to the sleeve 6.

An embodiment of the present invention will now be described, by way of example only, with reference to Figures 5 to 7 of the accompanying drawings, wherein: Figure 5 is a sectional side view of a clutch release mechanism made in accordance with the present invention; Figure 6 is a sectional side view of the thrust sleeve of the mechanism depicted in Figure 5; and Figure 7 is an enlarged detailed sectional side view of part of the thrust sleeve depicted in Figure 6.

As shown in Figures 5 to 7, the mechanism employs an angular contact rolling element bearing 10 similar to Figures 1 and 2 but having an axially extended inner raceway 25. The thrust sleeve or hub, here designated 26, is made from a resiliently-deformable material, preferably nonmetallic, e.g., synthetic plastics. The inner raceway 25 seats in a shallow recess 36 formed in the exterior of the sleeve 26. The sleeve 26 has a series of longitudinal slots 30 open to its end face 31 and terminating at 29 at a central region.

As with the prior art mechanisms, the sleeve 26 has a flange 40 at the opposite end acted on by the lever during clutch re-engagement to retract the bearing in the direction of arrow B. The slots 30 are spaced uniformly around the circumference of the sleeve 26. At the inner end of the sleeve 26, relative to the associated clutch, there is a radially-projecting rim portion 24 effectively sub-divided by the slots 30. The rim portion 24 is radiused or chamfered as at 23 (Fig.

7) outwardly of the sleeve 26, i.e. towards the end face 31. The inner end face 27 of the rim portion 24 defines with a complementary end face 28 the axial extent of the recess 36. A shallow relief groove 38 deeper than the remainder of the recess 36 is provided adjacent the end face 27.

The presence of the slots 30 provides the sleeve 26 with a series of elongate separate elements 32 which effectively act as cantilevered springs. The degree of resilience and flexure of the elements 32 can be adjusted according to the material used by varying the size and/or the number of slots 30.

These elements 32 can be deflected radially/inwards as the bearing 10 is assembled to the sleeve 26. The inner raceway 25 of the bearing 10 can be urged towards the end face 31 and against the chamfered region 23 of the rim portion 24 thus to deflect the elements 32 radially inwards thereby to permit the raceway 25 to become located in the recess 36 as a snapfit.

The faces 27, 28 then retain the raceway 25 after the elements 32 have deflected back outwards to their former position.

This arrangement allows the assembly of the bearing 10 to the sleeve 26 to be effected quite easily, and avoids the aforementioned difficulties concerned with toierances and damage.

Although the invention has been described in relation to a mechanism of the type shown in Figure 1 and 2, the same principle can be applied in the case of the mechanisms depicted in Figures 3 and 4. In the case of Figure 4 the recess 26 would be shorter than that shown in Figures 5 to 6 to accommodate both the bearing races.

A mechanism constructed in accordance with the invention can also result in a saving in material costs since the sleeve 26 can be moulded or otherwise fabricated in quantity from thermoplastics material. The material used can also be a composite composed of thermoplastics impregnated with fibres or particles. The flexibility of the elements 32 also has advantages in fabrication of the sleeve 26 since deflection of the elements 32 can assist in releasing the sleeve 26 from the mould. In the prior art mechanisms of Figures 1 to 4, it is usual to mount the sleeve 6 to the associated axial guide, e.g., the sleeve, spigot or the like of the clutch, without lubricant or with only a minimal amount of lubricant, such as grease contained in a groove in the inner wall of the sleeve 6. Consequently in time, friction between the inner wall of the sleeve 6 and the guide can cause substantial wear and damage. By making the sleeve 26 from a material which also has low sliding friction characteristics the entire mechanism can slide smoothly over the guide without undue wear and the overall life of the mechanism can be increased.

Claims

1. A clutch release mechanism composed of a rolling element bearing attached to a thrust sleeve or hub as a snap-fit.

2. A mechanism according to claim 1, wherein the sleeve is relieved to provide, at least in part, for resilient deflection in fitting the bearing thereto.

3. A mechanism according to claim 1, wherein the sleeve is provided with slots to provide, at least in part, for resilient deflection in fitting the bearing thereto.

4. A mechanism according to claim 3, wherein the slots are provided at one end region of the sleeve to create a series of separate deflectable strip-like fingers.

5. A mechanism according to claim 4, wherein the sleeve is provided with a radially-projecting rim portion at said end, said rim portion being divided by the slots.

6. A mechanism according to claim 5, wherein the rim portion is radiused or chamfered outwardly of the sleeve to guide the bearing during assembly thereto.

7. A mechanism according to claim 6, wherein the sleeve is provided with means locating the bearing in a pre-determined position.

8. A mechanism according to any one of claims 1 to 6, wherein the sleeve has a recess for accommodating one or both raceways of the bearing.

9. A mechanism according to claim 6, wherein one race of the bearing is located in a recess in the sleeve, said recess being partly defined by said rim portion.

10. A mechanism according to claim 9, wherein said one race is the inner race which is prolonged axially of the sleeve relative to the outer race.

11. A mechanism according to any one of claims 1 to 10, wherein the sleeve is made from a synthetic plastics material or contains such a material.

12. A mechanism according to any one of claims 1 to 8, wherein the sleeve is moulded from a synthetic plastics material having low sliding friction.

13. A mechanism according tq any one of claims 1 to 12, wherein the sleeve is made from a material which is inherently resilientlydeformable.

14. A mechanism according to any one of Claims 1 to 13, wherein the sleeve is located for axial sliding on a guide of an associated clutch.

1 5. A clutch release mechanism substantially as described with reference to, and as illustrated in, Figures 5 to 7 of the accompanying drawings.

1 6. A clutch release mechanism substantially as described with reference to, and as illustrated in, Figures 3 and 4 of the accompanying drawings as modified by Figures 6 and 7 of the accompanying drawings.

14. A clutch release mechanism including a rolling element bearing located in a recess in the outer wall of a thrust sleeve, the thrust sleeve being made from a resiliently-deformable material and having a radially-outwardly projecting rim portion at one end and a series of axial slots penetrating said rim portion to provide a number of separate strip-like fingers which act as cantilevered springs so that the bearing can be forced over the rim portion to deflect said fingers radially inwardly and the fingers can then deflect radially outwardly to capture the bearing in a snap-fitting action.

1 5. A mechanism according to any one of claims 1 to 14, wherein the sleeve is located for axial sliding on a guide of an associated clutch.

1 6. A clutch release mechanism substantially as described with reference to, and as illustrated in, Figures 5 to 7 of the drawings accompanying U.K. patent application 7909100.

1 7. A clutch release mechanism substantially as described with reference to, and as illustrated in, Figures 3 and 4 of the drawings accompanying U.K. patent application 7909100 as modified by Figures 6 and 7 of the drawings accompanying U.K. patent application 7909100.

New claims or amendments to claims filed on 28/2/80.

Superseded claims 1 to 1 7.

New or Amended Claims:

1. A clutch release mechanism composed of a rolling element bearing attached to a separate thrust sleeve or hub as a snap-fit, wherein the sleeve is relieved to provide, at least in part, for resilient deflection in fitting the bearing thereto.

2. A mechanism according to Claim 1, wherein the sleeve is provided with slots to provide, at least in part, for said resilient deflection.

3. A mechanism according to Claim 2, wherein the slots are provided at one end region of the sleeve to create a series of separate deflectable strip-like fingers.

4. A mechanism according to Claim 3, wherein the sleeve is provided with a radially-projecting rim portion at said end, said rim portion being divided by the slots.

5. A mechanism according to Claim 4, wherein the rim portion is radiused or chamfered outwardly of the sleeve to guide the bearing during assembly thereto.

6. A mechanism according to Claim 5, wherein the sleeve is provided with means locating the bearing in a pre-determined position.

7. A mechanism according to any one of Claims 1 to 5, wherein the sleeve has a recess for accommodating one or both raceways of the bearing.

8. A mechanism according to Claim 5, wherein one race of the bearing is located in a recess in the sleeve, said recess being partly defined by said rim portion.

9. A mechanism according to Claim 8, wherein said one race is the inner race which is prolonged axially of the sleeve relative to the outer race.

10. A mechanism according to any one of claims 1 to 9, wherein the sleeve is made from a synthetic plastics material or contains such a material.

11. A mechanism according to any one of Claims 1 to 9, wherein the sleeve is moulded from a synthetic plastics material having low sliding friction.

12. A mechanism according to any one of Claims 1 to 11, wherein the sleeve is made from a material which is inherently resilientlydeformable.

1 3. A clutch release mechanism including a rolling element bearing located in a recess in the outer wall of a separate thrust sleeve, the thrust sleeve being made from a resiliently-deformable material and having a radially-outwardiy projecting rim portion at one end and a series of axial slots penetrating said rim portion to provide a number of separate strip-like fingers which act as cantilevered springs so that the bearings can be forced over the rim portion to deflect said fingers radially inwardly and the fingers can then deflect radially outwardly to capture the bearing in a snap-fitting action.