GB2180304A

GB2180304A - Method of fitting a clutch cover assembly

Info

Publication number: GB2180304A
Application number: GB08522758A
Authority: GB
Inventors: Anthony John Curtis
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1985-09-13
Filing date: 1985-09-13
Publication date: 1987-03-25
Also published as: GB8522758D0

Abstract

A clutch cover assembly 4 for a pull-type clutch comprises a cover 16, a diaphragm spring 18 with release fingers 22, and a pressure plate 14 attached to the cover by tangential leaf-springs 30 which pull the pressure plate into the cover 16 when the load of the diaphragm spring 18 on the pressure plate 14 is relieved by a pull on the fingers 22 in direction A. To fit the cover assembly 4 to a flywheel 6, the fingers 22 are pulled in direction A so allowing the release straps 30 to retract the pressure plate 14 into the cover 16. Thus the pressure plate does not press on the clutch driven plate 10 and so there is no opposition by the diaphragm spring to the tightening of the bolts 58 securing the cover 16 to the flywheel. The fitting can be done automatically with a tool 42 which is braced against the cover 16 as a gripping device 46 of the tool pulls back the fingers 22 in direction A. The tool 42, which has a shaft 56 holding the driven plate 10 centrally, offers the cover assembly 4 and driven plate 10 to the flywheel 6 to which the cover 16 is secured by the bolts 58 being automatically inserted and tightened by tool devices 60. <IMAGE>

Description

SPECIFICATION Method of fitting a clutch cover assembly This invention concerns a method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the kind (hereinafter called "the kind referred to") wherein said clutch comprises rotatable counter-pressure means provided with a counter-pressure surface, a clutch cover assembly comprising a cover mounted for rotation with the counter-pressure means, a pressure plate to rotate with the cover and movable axially relative to said cover, and load spring means acting to apply urging force to the pressure plate to move the pressure plate axially relative to the cover in a first direction, and a driven plate clampable between said counter-pressure surface and the pressure plate moved in the first direction under urging by the load spring means.

The clutch of the kind referred to may be used to transmit interruptably rotary power from a power source, for example an internal combustion engine, to one or more road wheels of a motor vehicle via a change-speedgearbox.

In a known clutch of the kind referred to the counter-pressure means can be a fly-wheel of an engine to which fly-wheel the cover is bolted. To fit the cover assembly to the flywheel it is known to move the pressure plate axially relative to the cover in a second direction opposite to the first direction to a position of partial retraction where chocks are inserted between the cover and pressure plate to hold the pressure plate in the partially retracted position. A removable fitting shaft in a central opening or hub of the driven plate holds the latter in a centralised position adjacent to the fly-wheel as the cover assembly is offered up to the fly-wheel and the cover bolted thereto.During the tightening of the mounting bolts the cover is drawn thereby towards the fly-wheel causing the pressure plate to firmly clamp the centralised driven plate against the fly-wheel whilst at the same time the pressure plate is moved axially further in said second direction relatively to the cover against the action of the load spring means until the chocks become loose and drop off and the bolts are sufficiently tight. The fitting shaft is removed leaving the clamped driven plate centralised to accurately receive an input shaft of the gearbox when the gearbox and engine are secured together.

In the known fitting method the tightening of the mounting bolts is opposed by the effort exerted by the load spring means, therefore the bolting load which has to be exerted is greater than it would otherwise need to be.

Also in the case of pull-type clutches having load spring means provided by a diaphragm spring with radially inwardly directed release fingers which are pulled in the second direction to release the clutch, the partial retraction of the pressure plate to its chocked position may still leave the release levers positioned sufficiently far enough along the first direction for them, or a release bearing thereon, to foul the hub of the driven plate as the cover assembly is offered up to the fly-wheel.

According to a first aspect of the invention a method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the type referred to comprises axially moving the pressure plate sufficiently in an opposite or second direction relative to the cover so that during securing of the cover to the counter-pressure means the pressure plate does not or substantially does not press on the driven plate in a manner opposing the securing of the cover to the counter-pressure means.

According to a second aspect of the invention a method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the type referred to comprises using automatically operating apparatus which acts on the cover assembly so that the pressure plate is caused to move axially relative to the cover in an opposite or second direction to a position relative to the cover assembly at which the pressure plate is retained as the cover is secured to the counterpressure means.

According to a third aspect of the invention a method according to the second aspect further comprises the automatically operating apparatus exerting effort on the load spring means to reduce or eliminate the urging force exerted by the load spring means on the pressure plate. The clutch cover assembly may further comprise release spring means acting to urge the pressure plate in the second direction under which urging the pressure plate moves in the second direction relative to the cover when the urging force exerted by the load spring areas is reduced. The clutch may be a pull-type clutch and the automatically operating apparatus pulls on the load spring means to reduce or eliminate the urging force exerted by the load spring means on the pressure plate.

According to a fourth aspect of the invention a method of fitting a clutch cover assembly according to the second aspect wherein the pressure plate is moved in the second direction relative to the cover by the automatically operating apparatus.

According to a fifth aspect of the invention a method of fitting a clutch cover assembly according to the fourth aspect in which the pressure plate is provided with projections pulled by the automatically operating apparatus to move the pressure plate in the second direction relative to the cover. Said projection may be rivets. The clutch cover assembly may be provided with drive strap release springs attached to the pressure plate by said rivets.

The automatically operating apparatus may be robot means.

The automatically operating apparatus may automatically fasten the cover assembly to the counter-pressure means, for example by automatically securing the cover assembly to the counter-pressure means using screw-threaded securing means.

According to a sixth aspect of the invention a method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the kind referred to in which the pressure plate has projections which are pulled in said second direction to move the pressure plate in the second direction relative to cover to a position in which the pressure plate is held by pull exerted on the projections whilst the cover assembly is being secured to the counter-pressure means. The pulling effort may be, or be derived from, manual effort.

The projections may be rivets. Said rivets may be securing drive strap release springs to the pressure plate.

The invention will now be further described, by way of example, with reference to the accompanying drawings in which Fig. 1 is a diagrammatic representation of automatically operating apparatus performing a method according to the invention of fitting a clutch cover assembly to counter-pressure means; Fig.2 is an enlarged view partly in section of a fragment of the automatically operating apparatus of Fig. 1 in conjunction with a clutch cover assembly in section and a driven plate and counter-pressure means in section; Figs.3 and 4 are views comparable to Fig.2 of respective modifications of the automatically operating apparatus;; Fig.5 is a view comparable to Fig.2 of a further modification of the automatically operating apparatus performing the method according to the fourth or the fifth aspect of the invention; Fig.6 is a fragmentary plan view illustrating a stage in a manual method according to the sixth aspect of the invention, using a special holding tool, of fitting a clutch cover assembly to counter-pressure means to form a clutch of the kind referred to, Fig.7 is a section on line VII-VII in Fig.6, and Fig.8 is a perspective view of a fragment of the holding tool in Fig.6.

In the drawings like references refer to like or comparable parts.

Referring to Figs. 1 and 2 automatically operating apparatus 2 in the form of a robot is shown in the course of fitting a clutch cover assembly 4 to rotatable counter-pressure means 6 or driving plate exemplified in this case as a fly-wheel (shown in dotted line in Fig.2) of an internal combustion engine 8 to form a friction clutch of the kind referred to in which a driven plate 10 of any suitable kind known per se (shown in dotted line in Fig.2 and having friction facings 11) is disposed between a counter-pressure surface 12 of the fly-wheel and a pressure plate 14 of the clutch cover assembly.

The clutch cover assembly 4 is for a pulltype clutch and comprises a cover 16, the pressure plate 14 and load spring means which in this example takes the form of a diaphragm spring 18 known per se with-a circumferential Belleville portion 20 integral with inwardly directed radial fingers 22 separated by radial slots 24. The diaphragm spring 18 acts between a fulcrum ring 26 on the cover 16 and annular fulcrum 28 on the pressure plate. A plurality of substantially equispaced release and driving straps (for example three, but only one shown at 30) known per se and formed by tangentially orientated leaf springs are each secured at one end to the cover 16 and secured at the other end to a radial lug on the pressure plate 14 by a rivet 32.Therefore when the radially inner ends 22a of the fingers 22 are pulled in direction A (Fig.2), whilst the cover 16 is maintained axially stationary relative to the fingers, the load exerted by the diaphragm spring 18 on the pressure plate is reduced or eliminated so that under the urging of the release springs 30 the pressure plate is retracted axially in direction A relative to the cover 16.

The robot 2 is an industrial robot constructed in accordance with any suitable robotic technique known per se and appropriately programmed by any suitable means known per se to perform the novel and specialised functions described below. The robot comprises a mobile arm 34, 36 articulated at 38 and 40 and to which arm a hand or tool body 42 is articulated at 44, the various articulations enabling the tool body 42 to move in substantially any direction.

The hand or tool body 42 (Fig.2) comprises a gripping device 46 comprising a radially expanding ring comprising hook-shaped segments 48 on a mobile carrier 50 in guide passage 52. At its periphery the tool 42 has an axially extending counter-pressure flange 54.

The tool body 42 may also be provided with holding means so that when the robot initially automatically picks up the clutch cover assembly 4 from a supply source the holding means initially support the cover assembly, or the gripping device 46 and flange 54 may serve to support the cover assembly without the need for other holding means. However the robot operates so that the gripping means 46 is automatically inserted through the central opening in the diaphragm spring 18 and the segments 48 swung outwards from the dotted line positions hook onto the finger ends 22a and are then pulled by carrier 50 in direction A relative to the tool body against which the cover 16 is stationarily braced at the flange 54.Therefore the loading exerted by diaphragm spring 18 on the pressure plate 14 is substantially eliminated so that the pressure plate 14 is substantially fully retracted into the cover 16 by the release springs 30 (i.e. a state corresponding to full disengagement of a clutch formed using the cover assembly 4).

The tool body 42 also mounts a fitting shaft 56 on which the driven plate 10 is automatically picked up from a supply and carried in a centralised attitude relative to the cover assembly 4.

The robot 2 automatically offers up the cover assembly 4 and driven plate 10 to the fly-wheel 6 which is pre-drilled to receive bolts 58 securing the cover 16 to the flywheel. The bolts 58 are supplied automatically and automatically screwed home by insertion devices 60 on the tool body 42. During the bolting of the cover assembly to the fly-wheel the diaphragm spring 18 does not (or substantially does not) oppose the insertion of the bolts 58 to fully secure the cover to the fly-wheel.

Now the insertion devices 60 may be released from the bolts 58 as the robot 2 pulls the tool body 42 back from the clutch cover assembly 4 after the gripping device 46 has been radially contracted to release the diaphragm spring 18 before the robot pulls the fitting shaft 56, co-axially of the clutch cover assembly 4, from the driven plate 10. Therefore under urging by the released diaphragm spring 18 the pressure plate 14 firmly clamps the centralised driven plate 10 against the flywheel 6 in the thus formed clutch. Accordingly when a gearbox is to be fitted to the engine 2 the driven plate 10 of the clutch is thus positioned to automatically and accurately receive the input shaft.of the gearbox.

In the modification in Fig.3 the cover assembly 4 for a pull-type clutch is shown already provided with a release bearing 62 in the finger ends 22a. In this case the gripping device 46a comprises the mobile carrier 50 with a radially contracting ring of hook-shaped segments 48a which are automatically movable between the full and dotted line positions shown in Fig.3 and when in the full line position can grip the bearing 70 to pull back the diaphragm spring 18.

In the modification in Fig.4 the gripping device 46b is an electro-magnet device which when energised holds the diaprhagm spring 18 by magnetic attraction sufficiently strong to pull the fingers 22 in direction A with the device 46b when the latter is moved automatically in that direction relative to the tool body 42.

Referring to Fig.5 rivets 32a are used to secure the drive straps and release springs to the lugs on the pressure plate 14. The rivets 32a all have projections on the same side of the pressure plate 14. Each projection is formed by a head 70 on a thin neck 72 attached to the main part of the respective rivet 32a. The robot is provided with a modified tool body 42a provided with a plurality of collets or other gripping devices 46c for gripping the respective rivet heads 70. Radially inwardly of the gripping devices 46c, the tool body has an axial reaction flange 54a against which the cover 16 bears as the rivets 32a automatically gripped by the gripping devices 46c are automatically pulled thereby relative to the tool body 42a in direction A.This causes the pressure plate 16 to be fully retracted into the cover 16 in readiness for the cover assembly 4 to be offered to the fly-wheel by the robot. After the cover assembly is secured to the fly-wheel the gripping devices 46c may act to shear off the rivet heads 70 at the necks 72. The tool body 42a may also be provided with clutch cover assembly holding means and bolt insertion devices.

In the manual fitting method shown in Figs.6 to 8 the clutch cover assembly 4 is the same as that in Fig.5 having projecting headed rivets 32a which co-operate with a manual holding tool 80. The tool 80 comprises a planar triangular frame of side bars 82 welded at each apex of the triangle to a corresponding reaction bar 84 which bears on the cover 16.

At the free end of each reaction bar 84 is a latch in the form of a generally V-shaped stirrup 86 with a flat base 88 which is slotted at 90 to engage the head 70 of a said rivet 32a.

The stirrup 86 is pivoted at 92 to a locking tube 94 with a limb 96 pivoted at 98 to the reaction bar 84. With all of the locking tubes 94 pivoted in turn to a position corresponding to B in Fig.7 each stirrup can be brought into engagement with the respective rivet 32a by bringing its neck 72 into the slot 90. Then as each locking tube 94 is pivoted in turn manually to position C where the tube is at right angles to the plane of the triangular frame, and sits on the reaction bar 84, the stirrup pulls the rivet 32a (and therefore the pressure plate 14) in the axial direction A relative to the cover 16 so that the pressure plate is fully retracted.In this state the clutch cover assembly 4 held by the holding tool 80 can be manually offered to counter-pressure means of the clutch to which counter-pressure means the clutch cover assembly is bolted or otherwise secured with the driven plate held centralised therebetween by any suitable known technique. Then the pressure plate 14 is released by pivoting the locking tubes 94 back to position B so that the stirrups 86 can be slipped off the rivet heads 70. If desired the heads 70 may then be broken off.

If desired the pivoting of the locking tubes 94 between positions B and C may be accomplished using a removable handle fitted into open end 100 of each locking tube.

The methods described with reference to Figs.5 to 8 require no special modification of the clutch cover assemblies other than the provision of rivets 32a with projecting heads 70. In the case of the methods described with reference to Figs. 1 to 4 no modification of the clutch cover assembly is needed at all.

The methods described with reference to Figs.5 to 8 may also be used to fit clutch cover assemblies of clutches of the push-torelease type so arranged that the pressure plate retracts when the fingers of the diaphragm spring are pushed towards the pressure plate. The methods described with reference to Figs. 1 to 4 may be modified for pushto-release type clutches by replacing the gripping devices 46, 46a, 46b by pushing devices to push the diaphragm spring fingers and by providing the tool body 42 with holding means to hold the cover of the cover assembly stationary relative to the diaphragm spring as the latter is pushed.

Claims

1. A method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the type referred to comprising axially moving the pressure plate sufficiently in an opposite or second direction relative to the cover so that during securing of the cover to the counter-pressure means the pressure plate does not or substantially does not press on the driven plate in a manner opposing securing of the cover to the counterpressure means.

2. A method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the type referred to comprising using automatically operating apparatus which acts on the cover assembly so that the pressure plate is caused to move axially relative to the cover in an opposite or second direction to a position relative to the cover assembly at which the pressure plate is retained as the cover is secured to the counter pressure means.

3. A method according to Claim 2, further comprising the automatically operating apparatus exerting effort on the load spring means to reduce or eliminate the urging force exerted by the load spring means on the pressure plate.

4. A method according to Claim 3, in which the clutch cover assembly further comprises release spring means acting to urge the pres sure plate in the second direction under which urging the pressure plate moves in the second direction relative to the cover when the urging force exerted by the load spring means is re duced.

5. A method according to Claim 3 or Claim 4, in which the clutch is a pull-type clutch and the automatically operating apparatus pulls on the load spring means to reduce or eliminate the urging force exerted on the load spring means on the pressure plate.

6. A method according to Claim 5, in which the automatically operating apparatus pulls on the load spring means through a magnetic attachment.

7. A method according to Claim 2, in which the pressure plate is moved in the second direction relative to the cover by the automatically operating apparatus.

8. A method according to Claim 7, in which the pressure plate is provided with projections pulled by the automatically operating apparatus to move the pressure plate in the second direction relative to the cover.

9. A method according to Claim 8, in which the projections are rivets.

10. A method according to Claim 9, in which said rivets are used to attach drive strap release springs to the pressure plate.

11. A method according to any one of Claims 2 to 10, in which the automatically operating apparatus is robot means.

12. A method according to any one of Claims 2 to 11, in which the automatically operating apparatus automatically fastens the cover assembly to the counter-pressure means.

13. A method according to Claim 12, in which the cover assembly is fastened to the counter-pressure means using screw-threaded securing means.

14. A method of fitting a clutch cover assembly to counter-pressure means to form a friction clutch of the kind referred to in which the pressure plate has projections which are pulled in said second direction to move the pressure plate in the second direction relative to the cover to a position in which the pressure plate is held by pull exerted on the projections whilst the cover assembly is being secured to the counter-pressure means.

15. A method according to Claim 14, in which the pulling effort is, or is derived from, manual effort.

16. A method according to Claim 14 or Claim 15, in which the projections are rivets.

17. A method according to Claim 16, in which the rivets are used to secure drive strap release springs to the pressure plate.

18. A method of fitting a clutch cover assembly to counter-pressure means to form a clutch of the kind referred to substantially as hereinbefore described with reference to Figs.1 to 3, or to Fig.4, or to Fig.5, or to Figs.6 to 8 of the accompanying drawings.

19. A clutch of the kind referred to made by a method according to any one preceding Claim.

20. A motor vehicle having a clutch as claimed in Claim 19.