GB2038439A - Clutch release mechanism - Google Patents

Abstract

A clutch release mechanism for use in a motor vehicle and which includes an adjusting mechanism to compensate for clutch wear and changes in cable length comprises a rod (18) slideable in an aperture (19) in a plate (20), but lockable to the plate when the plate is tipped by a clutch pedal (11) acting against the bias of a spring (22). Upon return of the clutch pedal (11), plate (20) is realigned by an abutment (21) in conjunction with spring (22) to unlock the rod and plate and allow adjustment of their relative positions. <IMAGE>

Description

SPECIFICATION Clutch release mechanisms This invention relates to clutch release mechanisms suitable for use in motor vehicles.

In a well known form of motor vehicle clutch release mechanism a cable or mechanical connection is used to connect the manually operated clutch pedal to the clutch release lever which is arranged to provide the requisite axial movement of the clutch release bearing. As clutch wear-in takes place, the rest position of the clutch pedal changes unless adjustment is provided to enable the effective length of the connection to increase. Mechanisms are known for providing automatic adjustment but these have been .complex and expensive.

The invention provides a clutch release mechanism including an elongate member having a substantially uniform transverse cross-section, a locking member having an aperture through which said elongate member passes, said elongate member being relatively slidable within the locking member when said elongate member is substantially aligned with said aperture, actuating means for applying force to the locking member in a direction parallel to the elongate member and in such manner as to exert a locking tipping moment on the locking member so as to turn said aperture out of alignment with the elongate member and thus lock said members together, and means arranged to exert a tipping moment on said locking member in a sense counter to that of said locking tipping moment.

The invention extends to a motor vehicle incorporating a clutch release mechanism as described above.

An Embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which :- Figure 1 is a cross-section through a clutch release mechanism in accordance with the invention; Figure 2 is a perspective view of some of the elements of the mechanism of Figure 1; and Figure 3 is a cross-section through a second embodiment of the invention.

Figure 1 shows the upper part only of a clutch pedal 11 which is mounted for pivotal movement about an axis 12 extending perpendicular to the cross-sectional plane, and is supported by a bracket which is not shown. Clutch engagement is effected by movement of pedal 11 in a counter clockwise direction as shown, and this movement is limited by an abutment 1 3 on a bracket 1 4 mounted by a cylindrical neck 1 5 located in an aperture in a motor vehicle's forward bulkhead 1 6.

Located coaxially through neck 1 5 is a bearing 1 7 through which there is slidably carried an elongate member 18 which is connected to a clutch actuating cable (not shown). In the present example elongate member 1 8 is a rod of hexagonal cross-section but alternatively it may, for example, be of circular or square cross-section or indeed the elongate member may be tubular.

Essentially, however, elongate member 1 8 is of substantially uniform transverse cross-section such that it will pass through an aperture 19 in a locking member 20, and permit relative sliding of the members 1 8 and 20 when the axis of aperture 19 is substantially aligned with elongate member 18.

Locking member 20 is urged against a stop 21 (shown also in Figure 2) by a resilient means which in the present example comprises a coil spring 22. Coil springs 22 rests on an extension bracket 23 which also supports the Free end of elongate member 18 in a grommet 24 of a suitable material such as rubber, PTFE or other plastics.

In operation, to release the clutch of the motor vehicle pedal 11 is rotated in a clockwise sense as shown causing an actuating lobe 25 at its end to force locking member 20 to the right. Movement of the locking member is, however, resisted by spring 22, and the combined force exerted by lobe 25 and spring 22 produce a tipping moment which acts on the locking member to tip it in an anti-clockwise sense. The aperture 1 9 is therefore moved out of its precise alignment with elongate member 1 8 until the ends of the aperture engage the surface of member 18.Frictional forces at the points of contact of the two members then effectively lock them together and obviate any relative sliding so that further movement of the clutch pedal 11 forces locking member 20 and elongate member 1 8 to the right (as illustrated), compressing spring 22 and pulling on the clutch cable to diengage the clutch.

To re-engage the clutch the pedal 11 is rotated anti-clockwise and the elongate and locking members are moved to the left under the influence of tension in the clutch cable and compression in the spring 22. As the components return to their rest positions, locking member 20 engages stop 21 which with spring 22 exerts a tipping moment in a sense counter to that of the locking moment caused by the spring and pedal 11. As a result the locking member is rotated until its aperture 1 9 is once more aligned with elongate member 1 8 so that the frictional lock between members 18 and 20 is broken and relative sliding is once again possible.

Thus when the clutch is engaged and the components are in their rest positions the elongate member is able, under the influence of the clutch cable, to move relative to the locking member to take account of any wear in the clutch which will require an increase in the effective length of the clutch cable. As a result of clutch wear, elongate member 1 8 will move to the left (as illustrated).

Whilst the illustrated embodiment is preferred for some applications, it will be apparent that numerous variations are possible within the scope of the invention.

For example, whilst elongate member 1 8 is shown as a smooth rod of precisely uniform transverse cross-section and this is useful in that it allows infinitessimal adjustment of the cable length between successive clutch dis/reengagements, in some circumstances it might be preferred to forgo the stepless variation offered by a smooth surfaced rod and to utilise instead a member having a mild saw-tooth longitudinal profile so that the locking force between members 18 and 20 is enhanced.

Whilst a resilient means is preferably incorporated, it is possible to omit it for example by suitable orientation of the mechanism to enable gravitational force on a suitable weighted locking member to take the piace of the spring force.

Moreover, whilst the description refers to a clutch cable, the invention is also suitable for use with other fixed length connections, such as a rod linkage.

Again whilst the adjusting mechanism is shown incorporated at the clutch pedal end of the release mechanism, the adjustment could instead be incorporated adjacent the clutch. In such a case the actuating means for the locking member could be constituted by a simple connection between the locking member and the clutch cable, the other end of the cable being connected direct to the clutch pedal.

Figure 3 illustrates such an arrangement, wherein the mechanism is located on the clutch housing 30, with cable 31, consisting of an outer part 32 and an inner part 33, extending from the mechanism, through the vehicles forward bulkhead, to be fixed to the clutch pedal in a conventional manner. Cable outer 32 is anchored on a flange 34 which is fixed relative to the clutch housing; cable inner 33 extends through the flange 34 to be held in the enlarged base of a slot 35 in a locking member 36 by the force of compression spring 37 acting between the flange and the locking member.

Locking member 36 has an aperture 37 through which passes a slidable elongate member comprising a push rod 38 which acts on the clutch release lever 39. The other end of rod 38 is supported in a bush 40 which can be moved axially by means of a screw thread 41 by which the bush is held in flange 42. Rod 38 is biased to the right of the drawing by a compression spring 43 so as to bias the rod toward its clutch engaged position. The locking member can be locked to the rod, if the circumstances make such desirable, by tightening a set-screw 44.

A saddle leaf-spring 45 is attached to the bottom of locking member 36 and slides on the base of the mechanism mounting plate 46 at each side of a central rib 47 which extends parallel to the push rod 38. Spring 45 serves to provide a predetermined frictional resistance to movement of the bottom of the locking member 36, which with the net force exerted by cable 33 and spring 37 produces a tipping moment on the locking member to ensure either a locking or an unlocking action between the member 36 and push rod 38.

Thus in operation the mechanism is actuated by pulling on the cable inner 33 by means of the clutch pedal, thereby tipping the locking member 36 so that it locks with rod 38 and draws it to the left of the figure to the position shown wherein the clutch is disengaged. To re-engage the clutch, the pedal, and hence cable 33, are released by the operator allowing spring 37 and 43 to draw the locking member and push rod to the right of the figure. When the clutch has engaged, the locking member 36 will have moved until its edge 46 abuts bush 40. Reaction with bush 40 then, with spring 37, produces a tipping moment on the locking member in a sense which unlocks it from rod 38 and permits the rod to adjust its position relative to the locking member to take account of clutch wear, that is to say, move toward the right of Figure 3. The screw thread 41 on bush 40 enables the mechansim to adjust for varying travel of member 36 between individual mechanisms to take account of cable tolerances etc.

Claims (14)

1. A clutch release mechanism including an elongate member having a substantially uniform transverse cross-section, a locking member having an aperture through which said elongate member passes, said elongate member being relatively slideable within te locking member when said elongate member is substantially aligned with said aperture, actuating means for applying force to the locking member in a direction parallel to the elongate member and in such manner as to exert a locking tipping moment on the locking member so as to turn said aperture out of alignment with the elongate member and thus lock said members together, and means arranged to exert a tipping moment on said locking member in a sense counter to that of said locking tipping moment

2. A clutch release mechanism as claimed in Claim 1, wherein said elongate member comprises a rod.

3. A clutch release mechanism as claimed in Claim 1 or 2, wherein said locking member is plate shaped.

4. A clutch release mechanism as claimed in Claim 1,2 or 3, wherein said aperture is so aligned that said locking member is substantially perpendicular to the length of said elongate member when the two members are locked together.

5. A clutch release mechanism as claimed in any one of claims 1 to 4, including means for exerting a tipping moment on said locking member, comprising resilient means arranged to act in a direction substantially parallel to said elongate member.

6. A clutch release mechanism as claimed in any preceding claim, wherein said means for exerting a tipping moment on said locking member in a sense counter to that of said locking tipping moment, include an abutment for engaging the locking member at the end of its travel toward a clutch-engaged position.

7. A clutch release mechanism as claimed in any preceding claim, including means for exerting a tipping moment on said locking member, comprising means arranged to exert a frictional resistance to movement of one side of the locking member.

8. A clutch release mechanism as claimed in Claim 7, wherein said frictional means comprises a spring.

9. A clutch release mechanism as claimed in any preceding claim, including means for securing said locking member to said rod for movement in concert therewith.

10. A clutch release mechanism as claimed in any preceding claim, wherein said actuating means comprises a portion of said clutch pedal.

11. A clutch release mechanism as claimed in Claim 10, wherein said elongate member is attached to one end of a release cable.

12. A clutch release mechanism as claimed in any one of claims 1 to 9, wherein said actuating means comprises the end of a clutch cable remote from the clutch pedal.

13. A clutch release mechanism as claimed in Claim 12., wherein said elongate member is connected to a clutch release lever.

14. A clutch release mechanism substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

1 5. A clutch release mechanism substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

1 6. A motor vehicle including a clutch release mechanism as claimed in any preceding claim.