GB2195413A

GB2195413A - A friction clutch for a vehicle

Info

Publication number: GB2195413A
Application number: GB08622962A
Authority: GB
Inventors: Robert Jolyon Ball; Denzil John William Symonds
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1986-09-24
Filing date: 1986-09-24
Publication date: 1988-04-07
Anticipated expiration: 2006-09-24
Also published as: GB8622962D0; GB2195413B

Abstract

The friction clutch has a clutch release mechanism which includes a first member, a second member and a detent 16 arranged to locate the first member relative to the second member. Such location is effected by moving the first member axially of the clutch in one direction relative to the second member whereby a clutch release force subsequently applied to said first member axially of the clutch in an opposite direction will be transmitted to said second member to release the clutch. Detent release means 18 is provided which enables the detent to be released by urging said first member further in said one direction relative to said second member so that the first and second member can thereafter be separated by subsequently moving the first member in said opposite direction relative to said second member. The detent 16 comprises a ring-like member and said detent release means 18, is arranged to turn the entire ring-like member to effect the detent release.

Description

SPECIFICATION A friction clutch for a vehicle The invention relates to a friction clutch for a vehicle. On certain vehicles, assembly of a release mechanism for a clutch is made easier if clutch release components can be snap-fitted together. A clutch having a snap-fit release mechanism is described in our U.K. Patent Application No. 2131515 and an object of the present invention is to provide an improved clutch which utilises snap-together release mechanism components.

According to the invention there is provided a friction clutch for a vehicle which includes a clutch release mechanism comprising a first member, a second member, a detent arranged to locate the first member relative to the second member by moving the first member axially of the clutch in one direction relative to the second member whereby a clutch release force subsequently applied to said first member axially of the clutch in an opposite direction will be transmitted to said second member to release the clutch, and detent release means which enables the detent to be released by urging said first member further in said one direction relative to said second member so that the first and second members can thereafter be separated by subsequently moving the first member in said opposite direction relative to said second member, said detent comprising a ring-like member and said detent release means being arranged to turn the entire ring to effect detent release.

Preferably, the ring-like member is turned about one of its ends.

The operation of the detent release means preferably induces circumferential loading in said ring-like member during detent release.

Such loading may be used to provide a return bias for said detent whereby the detent will normally be biased towards an operative position.

Preferably, the ring like member includes one or more projections thereon through which clutch release force is transmitted.

The or each of said projections may converge towards the axis of the clutch when in an operative position. The detent release means may be operable to move the projections radially to effect turning movement of the ring-like member during detent release.

The or each of said against abutment means on one of the members through which clutch release forces are transmitted to said detent.

The or each of said projections may be formed with a surface which extends so as to lie against or adjacent a peripheral portion of said one member. The or each surface may be formed on a radially inner face of its projections. Preferably, the or each surface is ramp like to enable it to ride over said abutment means during movement of said first member in said opposite direction following release of the detent.

A friction clutch in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 is a cross section through a friction clutch in accordance with the invention, Fig. 2 is a view of the clutch of Fig. 1 drawn to a larger scale and showing a release mechanism of the clutch in detail, Fig. 3 is an end view of the clutch in Fig. 2 in the direction of arrow Ill and Fig. 2 and shown partly in cross section, Fig. 4 is a cross section showing a release plate of the friction clutch, Fig. 5 is an end view of the release plate of Fig. 4 looking in the direction of arrow V in Fig. 4, Fig. 6 is an elevation of a resilient retaining clip.

Fig. 7 and 8 are end and plan views respectively of the retaining clip of Fig. 6, Fig. 8 is an elevation of a detent ring having convergent projection, Fig. 10 is an end view of the detent ring of Fig. 9 looking in the direction of arrow X in Fig. 9, Figs. 11 and 12 show cross sections through part of the release mechanism drawn to a larger scale in operative and detent release positions respectively, and Fig. 13 is an end view of part of the detent ring Referring to Fig. 1, a clutch pressure plate 10 is retracted by a clutch release mechanism 11 to release the clutch driven plate 12.

Clutch release effected by applying a force in direction A to a release plate 13 engaging a diaphragm clutch spring 14. The force is applied by means of a member 17 which transmits the force through a short hollow shaft 15 through a detent ring 16 and to the release plate 13. The detent ring 16 can be released by means of a release member 18 to enable the release plate 13 and shaft 15 to be separated when required.

Specific areas of the clutch will now be described in greater detail with reference to the remaining accompanying drawings. The diaphragm clutch spring 14 is formed with the usual radial slots 19 so as to leaving spaced fingers 20. The fingers engage a convex surface 21 on an annular flange 22 of the release plate 13 which is formed with four pairs of radial slots 23 which align with the slots 19 in the diaphragm. The fingers 20 are held in engagement with the convex surface 21 by four clips 24 shown in detail in Figs. 6 to 8.

Each clip comprises a strip of metal which is bent to form a top-hat section as shown in rig. 8. The section has two free end sections 25 having inclined upper surfaces 26 as viewed in Fig. 7, a transverse section 28 and two intermediate sections 27 interconnecting the free end sections 25 and the transverse section 28. The intermediate sections 27 are parallel in plan view and converge in end view whereby, in use, they lie substantially in radial planes which intersect on the axis X of the clutch. As viewed in Fig. 8 the free end sections 25 are bent so that the angle 0 between them and their adjacent intermediate sections is slightly less than 90". The transverse section 28 is formed with a protrusion 29.

To assemble the diaphragm spring 14 and clutch release plate 13, the four clips 24 are located on the spring by sliding them radially outwardly along the appropriate slots 19 until the intermediate sections 27 resiliently grip the edges of the fingers 20. The release plate 13 is then positioned as shown in Figs. 2 and 3 and the clips are moved radially inwardly so that the intermediate sections 27 extend through aligned slots 23 in the flange 21. In that position, the protrusion 29 on the transverse section 28 of each clip engages a surface of the associated finger 20 remote from the release plate 13 and the two free end sections 25 engage the surface of the flange 22 remote from the spring.

The length of each intermediate section 27 is selected so that, with the clip in the position shown in Figs. 2 and 3, the free end sections 25 bend whereby angle H will increase towards 90" to hold the release plate 13 and spring 14 in resilient interengagement.

To prevent the clips moving outwardly during transmission of drive through the clutch, the edges 26 of the free end sections 25 are positioned radially inboard of projections 30 on the flange 22. The inclined edges 26 ensure that each clip 24 lies within a notional cylinder containing the outer periphery of the flange 21.

The release plate 13 has an internal bore 32 formed with spaced apart axial slots 33 terminating at a groove 34.

The detent 16 comprises a plurality of projections or sprags 36 extending from a ring section 37. The ring section 37 is formed with a through slot 38 which enables it to be snap fitted in the groove 34 with the sprags 36 located partly in the slots 33. The sprags 36 converge in use, towards the axis of the clutch and are formed with oblique inner surfaces 39 (Figs. 11 and 12). In an unstressed condition of the detent ring, the surfaces 39 preferably converge slightly towards the clutch axis.

The shaft 15 has an elongate peripheral groove 40 which locates the detent release member 18 (in the form of a sleeve) and a stop washer 42. The detent release member 18 is slidable axially along the groove 40. The shaft 15 has a bevelled leading end 43. The outer periphery of the detent.release member 18 grips the bore 32 of the release plate 13.

To assemble the shaft 15 within the release plate 13, the leading end 43 is inserted in the bore 32 and urged axially to the left so that the sprags 36 ride up the bevelled leading end 43 and snap into the groove 40 as in Figs. 2 and 11 with the surfaces 39 engaging the bottom of the groove 40. In order for the sprags to ride up the bevelled leading end, the ring section 37 itself turns within the groove 34 and the sprags move at least partly into their associated slots 33. The turning action is described in greater detail below with reference to Figs 11 and 12.

With the sprags 36 in Figs. 2 and 11 position, the clutch can be released by moving the shaft 15 in direction A so that clutch release force is transmitted from a shoulder 43a at the left hand end of groove 40 as viewed in Fig. 11, through the detent 16 and through the right hand wali of groove 34 to the release plate 13.

To separate shaft 15 from release plate 13, the shaft 15 is pushed in the direction of arrow B so that the release member 18 engages the sprags 36 and moves them radially outwardly until the surfaces 39 of the sprags are presented in a ramp-like manner to the outer edge of shoulder 43 as in Fig. 12. In that position, the stop washer 42 engages the right hand end of the release plate 13. The shaft 15 is then moved in direction A relative to the release member 18 so that the surfaces 39 ride over the shoulder 43 whereby the shaft 15 can be separated from the release plate 13.

The turning movement of the detent 16 in direction D in Fig. 12 induces circumferential forces in the ring section 37, i.e. tensile circumferential forces T (Fig. 13) at the radially inner surface of the ring section and compressive circumferential forces C at the radially outer surface. These forces create a return bias to the ring which urges the sprags normally towards the Fig. 11 position. Such an arrangement is advantageous in that the sprags 36 do not bend relative to a fixed part of a ring from which they extend which leads to increased life due to better distribution of stresses. Also, the detent 16 is axially shorter than a detent in which sprags bend relative to a fixed part thereby enabling the length of the clutch release mechanism 11 to be kept to a minimum; an advantage where space is restricted in the vehicle.

Clutch release forces are transmitted from the member 17 to the shaft 1 5 via a release bearing 44, the inner race of which is formed by a groove 45 in shaft 15. The outer race 46 of the bearing 44 is made axially fast with the member 17 by means of a cylindrical metal pressing 47 having a left hand flange 48 and a series of indentations 49 which overlie an annuiar flange 50 on member 17.

For ease of manufacture, the release plate 13 may be formed by sintering.

The use of the clips 24 to hold the release plate 13 and diaphragm spring together is ad vantageous as it eliminates the need to provide the well known Belleville washer and circlip arrangement, the latter requiring the provision of a circumferential groove in the release plate 13 indicated in broken lines at 52 in Fig. 1. The omission of the groove leads to a stronger, and axially shorter, release plate which can be made of reduced radial thickness in the region where the groove 52 would normally be formed. As the clips 24 extend through the slots 19in the diaphragm spring 14, the clips key the release plate 13 in a rotary sense to the diaphragm spring. Such an arragement makes it unnecessary to provide the usual locating pins on the release plate for that purpose.

Claims

1. A friction clutch for a vehicle which includes a clutch release mechanism comprising a first member, a second member, a detent arranged to locate the first member relative to the second member by moving the first member axially of the clutch in one direction relative to the second member whereby a clutch release force subsequently applied to said first member axially of the clutch in an opposite direction will be transmitted to said second member to release the clutch, and detent release means which enables the detent to be released by urging said first member further in said one direction relative to said second member so that the first and second members can thereafter be separated by subsequently moving the first member in said opposite direction relative to said second member, said detent comprising a ring-like member and said detent release means being arranged to turn the entire ring to effect detent release.

2. A friction clutch according to Claim 1 in which the ring-like member is turned about one of its ends.

3. A friction clutch according to Claim 1 or 2 in which the detent release means induces circumferential loading in said ring-like member during detent release.

4. A friction clutch according to Claim 3 in which said circumferential loading provides a return bias for said detent whereby the detent will normally be biased towards an operative position.

5. A friction clutch according to any preceding claim in which the ring-like member has one or more projections thereon through which clutch release for is transmitted.

6. A friction clutch according to Claim 5 in which the projections converge towards the axis of the clutch when in an operative position.

7. A friction clutch according to Claim 5 or 6 in which the detent release means is operable to move said projections radially to effect turning movement of said ring-like member during detent release.

8. A friction clutch according to Claim 5, 6 or 7 in which said projections locate against abutment means on one of the members through which clutch release forces are transmitted to said detent.

9. A friction clutch according to Claim 8 in which each said projection is formed with a surface which extends so as to lie against or adjacent a peripheral portion of a said member.

10. A friction clutch according to Claim 9 in which the surfaces are formed on radially inner faces of said projections.

11. A friction clutch according to Claim 8 or 9 in which said surfaces are ramp-like to enable them to ride over said abutment means during movement of said first member in said opposite direction following release of the detent.