GB2346939A

GB2346939A - Intermediate clutch plate biasing means

Info

Publication number: GB2346939A
Application number: GB9903372A
Authority: GB
Inventors: David Robertson Grant; Christian Robert Salmon
Original assignee: LIPE Ltd
Current assignee: LIPE Ltd
Priority date: 1999-02-16
Filing date: 1999-02-16
Publication date: 2000-08-23
Also published as: GB9903372D0

Abstract

A clutch assembly comprises a pressure plate 13 and a drive plate 11, disposed between which is a pair of driven plates (16, Figure 1) separated by an intermediate plate 17. Biasing means, comprises first and second springs 31,32 secured on opposite sides of the intermediate plate by headed pins 30, are provided to maintain the intermediate plate in a position generally equidistant from the pressure plate and the drive plate. The pressure plate, intermediate plate and drive plate may be removed/replaced as a single unit, whereby they are secured onto the clutch cover 23 by retaining bolts (40, Figure 2). As wear occurs and the separation between the drive and pressure plates is reduced, the springs become compressed, assuming a flatter profile, so as to account for wear and maintain the central position of the intermediate plate, up to a minimum separation, whereby the unit must be replaced.

Description

PATENTS ACT 1977 A9648GB Title: Clutch Assembly Description of Invention This invention relates to a clutch assembly and in particular a clutch assembly hereinafter referred to as a clutch assembly of the kind specified comprising a pressure plate and a drive plate, disposed between which is a pair of driven discs separated by an intermediate plate, the pressure plate, when the clutch is engaged, being biased in an axial direction towards the driven plate such that the pressure plate, driven discs, intermediate plate and drive plate are held together in torque transmitting relationship.

In a clutch assembly of the kind specified, it is desirable that the spacing between, on the one hand, the pressure plate and the intermediate plate, and on the other hand, the intermediate plate and the drive plate, is generally equal and that clearance be achieved between all the plates and driven discs, to avoid or reduce any possibility of inter-plate drag during actuation of the clutch. It is also desirable that the clutch assembly accommodate wear in its components.

An object of the invention is to provide a new or improved clutch assembly of the kind specified.

According to one aspect of the present invention, we provide a clutch assembly of the kind specified wherein biasing means are provided to maintain the intermediate plate in a position generally equidistant from the pressure plate and the drive plate.

The biasing means may comprise spring means.

The spring means may comprise a first spring disposed to act between the pressure plate and the intermediate plate and a second spring disposed to act between the intermediate plate and the drive plate.

The biasing means may comprise a pin means passing through the intermediate plate which engages said spring means.

The pin means may comprise a pin having a first head at one end and a second head at a second end.

The first head may be adapted to engage a first part of the first spring, a second part of the first spring being adapted to act on the intermediate plate.

The first spring may be a leaf spring, said first and second parts being spaced apart in a direction which is transverse to the axial direction.

The second spring may have a first part adapted to act on the pressure plate and a second part adapted to act on the drive plate.

The second spring may be a leaf spring, said first and second parts being spaced apart in a direction which is transverse to the axial direction.

The clutch assembly may comprise spacing means to maintain the separation of the pressure plate and drive plate above a predetermined minimum.

Said spacing means may comprise stop means acting on the pressure plate to limit movement of the pressure plate towards the drive plate.

Said stop means may comprise a bolt passing through a cover means.

The drive plate may comprise a flywheel saver, or altematively may comprise a flywheel.

The pressure plate, intermediate plate and drive plate may be connected to be mounted or removed from the clutch assembly as a single unit.

According to a second aspect of the invention we provide a clutch assembly of the kind specified wherein the pressure plate, intermediate plate and drive plate are connected to be mounted or removed from the clutch assembly as a single unit.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a side elevation, partly broken away and partly in section of a friction clutch embodying the invention, Figure 2 is an end view of part of the clutch of Figure 1, and Figure 3 is a part section on line 3-3 of Figure 2, Figure 4 is a partly broken-away part section on line 4-4 of Figure 2 showing the clutch in an unworn, engaged position, Figure 5 is a view similar to that of Figure 4 but showing the clutch in a fully worn position, Figure 6 is a part section on line 6-6 of Figure 2, and Figure 7 is a part section on line 7-7 of Figure 2 Referring to the Figures, a basically conventional friction clutch 10 is shown comprising a drive plate 11, in the present example in the form of a flywheel saver, bolted to a vehicle flywheel 12 and a pressure plate 13. The clutch is mounted for rotation about an axis 14. The drive plate could alternatively comprise the flywheel itself, or any other suitable part, for example an adapter ring, if desired.

A diaphragm spring 15 acts, when the clutch is engaged, so as to bias the pressure plate 13 in a direction towards the drive plate 11. Disposed between the pressure plate 13 and the drive plate 11 are a pair of driven discs 16 separated by an intermediate plate 17.

The diaphragm spring 15 comprises a generally radially outer part 18 and a plurality of inwardly directed fingers 19 with generally radial slots 20 there between. The. pressure plate 13 carries a wire 21, which is circular in cross section, in a circumferentially extending groove 22. The wire 21 acts as a fulcrum against which the diaphragm spring 15 bears and about which dishing of the diaphragm spring 15 is varied during clutch actuation by means of operation of a clutch release actuator engaged in a socket S, all in conventional manner. An example spring and clutch release actuator is disclosed in our copending application no. GB-A-2305484.

The clutch further comprises a cover member 23 attached to the fly wheel 12. Passing through an aperture 24 in the cover member 23 is a headed bolt 25 which is attached to the pressure plate 13. The aperture 24 is smaller than a head 25a of the headed bolt 25 and thus movement of the pressure plate 13 to the right as shown in the Figures is constrained.

Referring now to Figures 3 and 4, the drive plate 11 has biasing means comprising a projecting part 26 having an aperture 27 in which a part 28 of the intermediate plate 17 is received. Slidably received in apertures 29 in the intermediate plate 17 is a pair of headed pins 30. Each headed pin 30 comprises a first head 30a and a second head 30b. In the present example each head being provided on one of two parts which are a press fit one in the other to make up said pins. The heads 30a, 30b are disposed at opposite ends of each headed pin 30, and are separated by a desired spacing. A part of the head 30a is disposed to act on the pressure plate 13.

One end of a return strap 33 engages a flange 25b of the headed bolt 25.

The other end of the return strap 33 is secured to the cover member 23 by a locking bolt 34. The return strap 33 acts to urge the pressure plate 13 in a leftwards direction as seen in Figures 3 and 4 away from the intermediate plate 17.

The biasing means further comprises resilently deformable spring means in the form of first springs 31. Said first springs 31 are provided with apertures 3 la through which the pins 30 pass. A first part 31b of the first spring acts 31 on the heads 30a whilst a second part 31c of the first spring acts on the intermediate plate 17, to urge the intermediate plate 17 and the heads 30a away from one another and to urge the heads 30a into contact with the pressure plate 13.

Second springs 32 are provided which are similarly attached to the pins 30, the pins passing through apertures 32a. A first part 32b of the second spring 32 engages the intermediate plate 17, while a second part 32c of the second spring 32 is disposed to act on the drive plate 11 to urge the intermediate and drive plates in opposite directions.

It is desirable that the pressure plate 13, intermediate plate 17 and drive plate 11 may be removed from or replaced in the clutch assembly 10 as a single unit. As shown in Figure 6, in the present example the cover 23 is attached to the drive plate 11 by a plurality of retaining bolts 40. In the present example, each bolt 40 comprises a bolt head 41 which is received in a recess 42 provided in the face of the drive plate 11 disposed adjacent to the flywheel when the clutch unit is in place. The cover member 23, drive plate 11, pressure plate 13 and intermediate plate 17 are thus held together as a unit.

As shown in Figure 7, the clutch may be attached to the flywheel 12 as described hereinbefore, by means of bolts 47 which pass through the cover 23, drive plate 11, and flywheel 12.

The cover 23 and hence the pressure plate 13 and intermediate plate 7 clearly cannot be detached from the drive plate 11 when the clutch unit is operably attached to the flywheel. Only by removing the bolts 47 can the clutch unit be removed from the clutch assembly 10, exposing the bolt heads 41 to enable the bolts 40 to be removed.

When the clutch components are unworn, the intermediate plate 17 is thus biased to a central position as seen in Figure 4, with the heads 30a of the pins 30 abutting the pressure plate 13 and the heads 30b spaced from the intermediate plate by a predetermined spacing in the engaged position, in the present example 0.040" (1.02mm).

When the clutch 10 is operated to disengage the pressure plate 13, drive plate 11, driven discs 16 and intermediate plate 17, the pressure plate 13 is retracted to the left as seen in the Figures by the strap 33. The pressure plate is moved by a predetermined distance, in the present example 0.080" (2.04mm).

As the pressure plate 13 is withdrawn to the left, the spring 31 acts to maintain the heads 30a of the pins 30 in contact with the pressure plate 13. The intermediate plate 17 is urged in a leftward direction by springs 32, the springs 31,32 acting such that the intermediate plate 17 is held in a central position between the pressure plate 13 and the drive plate 11. The heads 30b of the pins 30 constrain the intermediate plate 17 to move a minimum of 0.040" (1.02mm) to the left, i. e. half the distance of movement of the pressure plate 13, to ensure that the intermediate plate 17 is disposed equal distantly between the drive plate 11 and the pressure plate 13.

As the driven discs 16, pressure plate 13 and drive plate 11 wear through use throughout the life of the device, when the pressure plate 13 is in its engaged position, the separation between the pressure plate 13 and the drive plate 11 will reduce. As shown in Figure 5, the springs 31,32 will be compressed, assuming a flatter profile as the elements of the clutch 10 wear.

The springs 31,32 continue to act on opposite sides of the intermediate plate 17 to maintain the intermediate plate 17 in a central position between the clutch plate 13 and the drive plate 11. As wear takes place, the headed pins 30 will be gradually displaced to the right as seen in Figure 5 so that the intermediate plate 17 and hence the first part of the springs 32 is displaced further away from the heads 30b of the pins 30.

As shown in Figure 5, the distance between the pressure plate 13 and drive plate 11 cannot fall below a minimum as set by the head 25a of the headed bolt 25. When the head 25a of the bolt 25 abuts the cover plate 23 in the region of the aperture 24a, the gap between the pressure plate and the drive plate it cannot be reduced any further and it becomes necessary to change the unit.

By maintaining equal spacing between the various parts of the clutch in operation, any drag between the elements of the clutch during actuation or operation is reduced, and in particular there is no difference in the forces on the two driven discs. The springs 31, 32 act to maintain this equal separation throughout the life of the clutch without requiring manual adjustment.

The drive plate 11 represents a sacrificial unit which accommodates any wear, preventing wear or damage to the friction face of the flywheel 12 itself.

It will be clear that such an arrangement would be suitable for use in any friction type of clutch, not merely a diaphragm spring friction clutch.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS 1. A clutch assembly of the kind specified wherein biasing means are provided to maintain the intermediate plate in a position generally equidistant from the pressure plate and the drive plate.
2. A clutch assembly according to claim 1 wherein the biasing means comprises spring means.
3. A clutch assembly according to claim 2 wherein the spring means comprises a first spring disposed to act between the pressure plate and the intermediate plate and a second spring disposed to act between the intermediate plate and the drive plate.
4. A clutch assembly according to claim 2 or claim 3 wherein the biasing means comprises a pin means passing through the intermediate plate which engages said spring means.
5. A clutch assembly according to claim 4 wherein the pin means comprises a pin having a first head at one end and a second head at a second end.
6. A clutch assembly according to claim 5 wherein the first head is adapted to engage a first part of the first spring and a second part of the first spring is adapted to act on the intermediate plate.
7. A clutch assembly according to claim 6 wherein the first spring is a leaf spring, said first and second parts being spaced apart in a direction which is transverse to the axial direction.
8. A clutch assembly according to claim 5 or claims to 7 wherein is the second spring has a first part adapted to act on the pressure plate and a second part adapted to act on the drive plate.
9. A clutch assembly according to claim 8 wherein the second spring is a leaf spring, said first and second parts being spaced apart in a direction which is transverse to the axial direction.
10. A clutch assembly according to any one of claims 5 to 9 wherein the first and second heads are disposed at a desired separation.
11. A clutch assembly according to any one of the preceding claims wherein the clutch assembly comprises spacing means to maintain the separation of the pressure plate and drive plate above a predetermined minimum.
12. A clutch assembly according to claim 11 wherein said spacing means comprises stop means acting on the pressure plate to limit movement of the pressure plate towards the drive plate.
13. A clutch assembly according to claim 12 wherein said stop means comprises a bolt passing through a cover means.
14. A clutch assembly according to any one of the preceding claims wherein the drive plate comprises a flywheel saver.
15. A clutch assembly according to any one of the preceding claims wherein the pressure plate, intermediate plate and drive plate are connected to be mounted or removed from the clutch assembly as a single unit.
16. A clutch assembly of the kind specified wherein the pressure plate, intermediate plate and drive plate are connected to be mounted or removed from the clutch assembly as a single unit.
17. A clutch assembly as described herein with referance to the accompanying drawings.
18. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.