GB2186039A

GB2186039A - Friction clutch cover assembly

Info

Publication number: GB2186039A
Application number: GB08602695A
Authority: GB
Inventors: David Aubrey Davies
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1986-02-04
Filing date: 1986-02-04
Publication date: 1987-08-05
Anticipated expiration: 2006-02-04
Also published as: GB8602695D0; GB2186039B

Abstract

A friction clutch cover assembly 2 comprises a diaphragm spring 8 sandwiched between two resilient wire, wavy fulcrum rings 26 and 28, the undulations of the rings 26 and 28 being substantially parallel to the axis X and the ring 28 being substantially continuously supported along the ring by the wall of cover 4. The cover 4 has spaced tabs 24 passing through radial slots 14 in the diaphragm spring 8 and the ring 26 is substantially continuously supported along its length by an annular support 30 retained by the tabs 24. Axially, rings 26 and 28 are pre-loaded and act to cushion re-engagements of a clutch comprising the assembly 2. The tabs may be replaced by rivets (Figs. 6 and 7). <IMAGE>

Description

SPECIFICATION Friction clutch cover assembly This invention concerns a friction clutch cover assembly of the type (hereinafter called "the type referred to") comprising cover means, a pressure plate, a diaphragm spring acting between first annularfulcrum arrangement on the pressure plate and a second annularfulcrum arrangement mounted on the cover means, and said diaphragm spring having a plurality of release levers formed by a plurality of radially inwardly extending fingers.

Amongst otherthings clutch cover assemblies of the type referred to can be used in automotive transmissions to interruptablytransfer rotary motion from avehicleenginetoa change-speed-gear-box.

British Patent 1,583,403 discloses a clutch cover assembly ofthe type referred to in which the second fulcrum arrangement consists of two flat, coaxial wire rings of the same diameter each pressed against an opposite side ofthe diaphragm spring, and the first fulcrum arrangement includes cushioning means formed by a wavy ring on the pressure plate and having undulations which extend parallel to the axis ofthe diaphragm spring, some of the undulations being ofgreateramplitudethan others. This cover assembly can provide subjectively acceptable cushioning during clutch re-engagements, for example, when no axial cushioning is provided between friction facings of a driven clutch plate in conjunction with which the cover assembly is used.However, when effecting a full clutch release, which requires allowing the wavy ring on the pressure plate to fully relax axially,the necessary movement ofthe diaphragm spring to achieve that can be excessive and this is a disadvantage.

An object of the invention is to provide a clutch cover assembly ofthe type referred to which can be constructed so asto avoid or at least mitigatethe aforesaid disadvantage.

According to the invention there is provided a clutch cover assembly of the type referred to wherein the second annularfulcrum arrangement comprises first annularly arrayed resilient wavy cushioning means at a first side of the diaphragm spring and second annularly arrayed resilient wavy cushioning means at an opposite second side of the diaphragm spring.

At least one of the said annularly arrayed wavy cushioning means may have undulations which extend substantially parallel to the axis of the diaphragm spring.

The first and second annularly arrayed wavy cushioning means may be substantiallyco-axial, and may have substantiallythe same diameter.

At least one of said annularly arrayed wavy cushioning means may have at least two undulations of substantiallythe same amplitude and/or substantially the same wavelength.

If desired, the undulations of at least one of said annularly arrayed wavy cushioning means may be of substantially the same amplitude and/or substantially the same wavelength.

Thefirstannularlyarrayed cushioning means may have at least one undulation which has substantially the same amplitude and/or wavelength as an undulation ofthe second annularly arrayed cushioning means.

lfdesiredthefirstannularly arrayed cushioning means may have at least one undulation which has a different amplitude and/or wavelength from an undulation ofthe second annularly arrayed cushioning means.

At least one of said annularly arrayed cushioning means may be a wavy ring, and preferably the ring is split. Alternatively at least one of said cushioning means may comprise a plurality of arcuate, separate, wavy elements disposed in succession to form an annular array.

At least one of said annularly arrayed wavy cushioning means may be applied directly against said diaphragm spring.

The first and second annularly arrayed wavy cushioning means may be pre-loaded by axial clamping thereof.

Preferably the first and second annularly arrayed wavy cushioning means are clamped between a part ofthe cover and another part or member on the cover.

The invention will now be further described, by way of example, with reference to the accompanying drawings in which: Figure 1 isa planview of one embodiment of a diaphragm spring clutch cover assembly formed according to the invention in an attitude corresponding to full engagement of a clutch comprising the cover assembly; Figure2 is a diagrammatic section on line Il-Il in Figure 1; FigureS is a diagrammatic section on line Ill-Ill in Figure 1; Figure 4 is a plan view on a reduced scale of a wavy ring forming one of the annularly arrayed wavy cushioning means in Figures 1 to3; Figure 5shows a fragment of a development, on an enlarged scale, of the wavy ring in Figure4;; Figure6isan enlarged fragment of a section, comparable to Figure 3, of a modification ofthe embodiment in Figures 1 to 3; Figure 7is a diagrammatic cross-section of afully engaged pull-type clutch including a second embodiment of a clutch cover assembly formed according to the invention, and Figure 8 is fragment of a section, comparabie to Figure7,ofa modificationoftheembodimentin Figure 7.

In the drawings like reference numerals refer to likeorcomparable parts.

Figures 1 to 5 show a clutch cover assembly 2 suitableforuse in a motor vehicle push-type clutch and comprising a cover4 apertured at6for bolts (not shown) to secure the cover assembly to a rotatably driven driving plate (not shown though represented by chain dot line F) for example a fly-wheel of a motor vehicle engine. The cover assemblyfurther comprises an annular diaphragm spring 8 centred on axis X and an annular pressure plate 10 which rotates with the coveraboutthe axis X due tothe coverand pressure plate being interconnected in known manner bytangential, spring driving straps 12. The diaphragm spring is radially slotted at 1 4to form a plurality of radially inwardly extending fingers 16.

On its side to face the driving plate the pressure plate has a pressure face 18, and when the clutch is in use a driven clutch plate (not shown) of any type known perse is disposed between the pressure face 18 and the driving plate F, the driven clutch plate engaging in known manneran outputshaftknown persetobe rotatably driven about axis X by the driven plate which is axially slidable relatively to the shaft. On the side ofthe pressure plate remote from pressure face 18 is an annularfulcrum arrangement centred on axis X and formed by a ridge formation 22.The cover 4 has hooked tabs 24 each disposed in a respective slot 14, the tabs collectively serving to retain an annularabutmentorplatearrangement30 supporting a resilientwirewavyfulcrum ring 26 centred on axis X and pressing against a side ofthe diaphragm spring 8 on the pressure plate side thereof. The annular abutment 30 may beformed by a single annular plate or buy a plurality ofarcuate plates disposed in a circle, and can provide a substantially continuous supportforthe ring 26. On the cover side ofthe diaphragm spring 8 there is retained another resilient wire wavy fulcrum ring 28 pressing againstthe diaphragm spring.The ring 28 is also centred on the axisXand has substantially the same diameter as the ring 26.

When a clutch comprising the coverassembly 2 is in use the aforesaid driven plate is released by axial movement in direction Ytowards driven plate F of a clutch release bearing (not shown) known perse which pushes on the radially inner ends ofthe fingers 16to relievethe clamp load (derived from the diaphragm spring) exerted on the driven plate by the pressure plate 10. The biasing load ofthe driven straps 12 ensures in known mannerthatthe pressure plate moves in the opposite direction to Y by an amount which frees the driven plate for clutch release.

The undulations ofthewavy rings 26 and 28 provide cushioning so that the clamp load increases progressively during movement of the diaphragm spring during re-engagementthe clutch that the re-engagement of the driven plate is smooth.

The undulations of each wavy ring are substantially parallel to the axis X ofthe cover assembly 2. Each wavy ring as exemplified by the ring 26 in Figure 4 is a split ring. The ring 26 has successive undulations of substantially the same sinusoidal wave form (Figure 5), all the undulations having substantiallythe same amplitude a and su bstantia l ly the same wavelength 1.The ring 28 also has successive undulations ofsubstantiallythe samesinusoidalwaveform in which all the undulations have substantially the same amplitude and substantiallythe same wavelength. The undulations ofthetwo rings 26 and 28 can have the same amplitude and the same wavelength.

However, the wavy ring 26 can have undulations of a different amplitude and/orwavelength to the undulations ofthewavy ring 28.

In an alternative, undulations of a said wavy ring can have an amplitude and/or a wavelength which differs from one undulation to another.

The wavy rings 26 and 28 are clamped againstthe opposite sides of the diaphragm spring 8 bythe axial clamping effect of the cover 4 and the tabs 24 (via abutment 30) on the wavy rings. The pre-load or initial axial compression of the undulations ofthe wavy rings (before the cover assembly 2 is mounted in place to form a clutch) can be controlled to have a predetermined desired value by a suitable choice of axial lengthy of the tabs 24. The extent of pre-load can control or determine the cushioning effect or characteristic provided by the wavy rings 26 and 28 during clutch re-engagements.

In the modification shown in Figure 6 the tabs 24 of Figures 1 to3 are omitted andthe annularabutment 30 is secured to the cover 4 by rivets 32 extending through the slots 14. the modification in Figure 6 is a preferred arrangement and has the advantage ofthe degree of pre-load of the wavy rings 26 and 28 being relatively easy to control simply by choosing an appropriate length for each rivet 32.

The rings 26 and 28 are shown having a circular cross-section, however, they may each have any desired cross-sectional shape, for example square or rectangular, and may be formed of strip material.

Alsothewavyrings may have undulations having a waveform otherthan sinusoidal.

Figure 7 shows a pull-type clutch comprising a clutch cover assembly 2A, hub H known perse carrying a known driven plate D which may be non-cushioned, and a known clutch release bearing B engaging the radially inner ends ofthe Figures 1 6A of the diaphragm spring 8Aon freely passing pins 34 pressed to the pressure plate 10. The fulcrum arrangement 22 is of lesser diameter than the wavy rings 26 and 28 clamped between the cover4A and a plurality of tabs 36 pressed at intervals from a side wall 38 side wall of the cover to retain the abutment 30 against the ring 26. To release the driven plate the bearing Bis pulled in directionzand is allowedto return in the opposite direction for the clutch to be re-engaged.

The modification in Figure 8 which is also a preferred arrangement, shows thatthe tabs 36 of Figure 7 can be omitted and the abutment arrangement 30 held by the rivets 32 beyond the outer periphery of the diaphragm spring 8A.

In all the above described embodiments or modifications, each wavy ring 26,28 can be replaced by an annular wavy cushion comprising arcuate lengths or pieces of wavy wire or strip disposed in a circle around the axis X.

CLAIMS 1. A clutch cover assembly of the type referred to wherein the second annularfulcrum arrangement comprises first annularly arrayed resilientwavy cushioning means at a first side of the diaphragm spring and second annularly arrayed resilient wavy cushioning means atan opposite second side of the diaphragm spring.

2. Aclutch cover assembly as claimed in Claim 1 in which at least one of said annularly arrayed wavy cushioning means has undulationswhich extend substantially parallel to the axis ofthe diaphragm spring.

3. A clutch cover assembly as claimed in Claim 1 or Claim 2, in which the first and second annularly arrayed wavy cushioning means are substantially co-axial.

4. Aclutch cover assembly as claimed in anyone preceding claim, in which the first and second annularly arrayed wavy cushioning means have substantially the same diameter.

5. A clutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed wavy cushioning means has at least two undulations of substantiallythe same amplitudeand/orsubstantiallythesame wavelength.

6. Aclutch cover assembly as claimed in any one preceding claim, in which the undulations of at least one of said wavy cushioning means are of substantially the same amplitude and/orthe same wavelength.

7. A clutch cover assembly as claimed in any one preceding claim, in which thefirst annularlyarrayed cushioning means has at least one undulation which has substantially the same amplitude and/or wavelength as an undulation ofthe second annularly arrayed cushioning means.

8. A clutch cover assembly as claimed in any one preceding claim, in which the first annularly arrayed cushioning means has at least one undulation which has a different amplitude and/orwavelength from an undulation of the second annularly arrayed cushioning means.

9. Aclutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed cushioning means is a wavy ring.

10. A clutch cover assembly is claimed in Claim 9, in which the ring is a split ring.

11. A clutch cover assembly as claimed in any one of Claims 1 to 8, in which at least one of said cushioning means comprises a plurality of arcuate, separate, wavy elements disposed in succession to form an annular array.

12. Aclutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed wavy cushioning means is applied directly against said diaphragm spring.

13. A clutch cover assembly as claimed in any one preceding claim, in whichthefirstand second annularly arrayed wavy cushioning means are pre-located by axial clamping thereof.

14. A clutch cover assembly as claimed in any one preceding claim, in which thefirstand second annularly arrayed wavy cushioning means are clamped between a partofthecoverandanother part or member on the cover.

15. A clutch cover assembly substantially as hereinbefore described with reference to Figures 1 to 5,orto Figure 6, orto Figure 7, orto Figure 8 of the accompanying drawings.

16. A clutch comprising a clutch cover assembly as claimed in any one preceding claim.

17. A motorvehicle provided with a clutch as claimed in Claim 16.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1-17 above have been deleted ortextually amended.

(b) Newortextually amended claims have beenfiled as follows:

Claims

1. A clutch cover assembly of the type referred to wherein the second annularfulcrum arrangement comprises first annularly arrayed resilient wavy cushioning means at afirstside ofthe diaphragm spring and second annularly arrayed resilient wavy cushioning means at an opposite second side ofthe diaphragmspring,thefirstcushioning means being disposed between the diaphragm spring andthe cover means, the second cushioning means being substantially continuously supported along its length by an annularly disposed abutment, and said first and second cushioning means being pre-loaded by axial clamping thereof between said abutment and said cover means.

2. Aclutch cover assembly as claimed in Claim 1, in which the annularly disposed abutment comprises an annular plate or a plurality of arcuate plates disposed in a circle.

3. Aclutch cover assembly as claimed in Claim 1 Claim 2, in which the cover has tabswhich retain the abutment.

4. A clutch cover assembly as claimed in Claim 1 or Claim 2, in which the abutment is riveted to the cover.

5. A clutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed wavy cushioning means has undulationswhich extend substantially parallel to the axis ofthe diaphragm spring.

6. A clutch cover assembly as claimed in any one preceding claim, in which the first and second annularly arrayed wavy cushioning means are substantially co-axial.

7. Aclutch cover assembly as claimed in anyone preceding claim, in which the first and second annularly arrayed wavy cushioning means have substantially the same diameter.

8. Aclutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed wavy cushioning means has at least two undulations of substantially the same amplitude and/or substantiallythe same wavelength.

9. A clutch cover assembly as claimed in any one preceding claim, in which the undulations of at least one of said wavy cushioning means are of substantially the same amplitude and/orthe same wavelength.

10. Aclutch coverassemblyasclaimed in any one preceding claim, in which the first annularly arrayed cushioning means has at least one undulation which has substantially the same amplitude and/orwavelength as an undulation ofthe second annularly arrayed cushioning means.

11. Aclutchcoverassemblyasclaimed in any one preceding claim, in which the first annularly arrayed cushioning means has at least one undulation which has a different amplitude and/or wavelength from an undulation ofthe second annularly arrayed cushioning means.

12. A clutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed cushioning means is a wavy ring.

13. A clutch cover assembly is claimed in Claim 12, inwhich the ring is a split ring.

14. A clutch cover assembly as claimed in any one of Claims 1 toll, in which at least one of said cushioning means comprises a plurality of arcuate, separate, wavy elements disposed in succession to form an annular array.

15. A clutch cover assembly as claimed in any one preceding claim, in which at least one of said annularly arrayed wavy cushioning means is applied directly against said diaphragm spring.

16. A clutch cover assembly substantially as hereinbefore described with reference to Figures 1 to 5, orto Figure 6, orto Figure 7, orto Figure 8 ofthe accompanying drawings.

17. A clutch comprising a clutch cover assembly as claimed in any one preceding claim.

18. A motor vehicle provided with a clutch as claimed in Claim 17.