GB1563708A

GB1563708A - Clutches

Info

Publication number: GB1563708A
Application number: GB5143875A
Authority: GB
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1975-12-16
Filing date: 1975-12-16
Publication date: 1980-03-26

Description

(54) IMPROVEMENTS IN OR RELATING TO CLUTCHES We, AUTOMOTIVE PRODUCTS LI MITED, a British Company of Tachbrook Road, Leamington Spa, Warwickshire, England do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a mechanism for controlling the movement of an intermediate pressure plate of a multi-plate clutch.

The invention is particularly useful in connection with a twin clutch in which an intermediate pressure plate is disposed between a drive plate and a main pressure plate, the intermediate pressure plate being arranged to clamp one driven plate against the drive plate and the main pressure plate being arranged to clamp another driven plate against the intermediate pressure plate.

A problem associated with a clutch of this type is that of ensuring that during disengagement of the clutch, the intermediate pressure plate withdraws frm the drive plate by an amount sufficient to release the said one driven plate without following the movement of the main pressure plate too closely and thereby maintaining engagement of the other driven plate.

This problem can be solved with the aid of various different types of mechanism for controlling the movement of the intermediate pressure plate. One such mechanism includes a spring or other means arranged to bias the intermediate pressure plate away from the drive plate and a stop which determines the maximum amount of movement which the intermediate pressure plate can perform under the action of this bias. In another mechanism, a spring is arranged to bias the intermediate pressure plate away from the main pressure plate, and means is provided for limiting the separation of the two plates.

When the clutch is in use, the friction surfaces wear and variations take place in the distances between the drive plate and the pressure plates. These variations affect the operation of the mechanism controlling the movement of the intermediate pressure plate, so that adjustments must be made throughout the working life of the clutch.

According to the present invention, a mechanism for controlling the movement of an intermediate pressure plate of a multiplate clutch comprises means for biasing the intermediate pressure plate in a predermined direction, a stop member carried by one of the compenents of the clutch for determining the maximum amount of movement of the intermediate pressure plate under the action of said bias, the stop member being movable in said predetermined direction to compensate for variations in the position occupied by the intermediate pressure plate when the clutch is in its engaged condition, and a locking member movable relative to the stop member in a direction generally perpendicular to said predetermined direction, the locking member being engageable with the stop member to prevent movement of the stop member in a direction opposite to said predetermined direction, whilst allowing the stop member to move relatively freely in said predetermined direction.

The stop member may be housed within an axially extending bore in said one clutch component, and have a first end portion which projects from the bore towards another clutch component for contact therewith. As the friction facings of the clutch wear, the pressure plates move progressively towards the drive plate and the stop member is repositioned by virtue of its contact with said another clutch component.

Adjustment therefore takes place during the working life of the clutch. The locking member may be housed in a bore which extends generally radially of said one clutch component, and which intersects the bore housing the stop member, the bores being offet so that the locking member projects to one side of the stop member. A spring may be provided so as to bias the locking member in the radially outward direction, or centrifugal force alone may be relied upon to produce the same effect. The locking member may have a portion which tapers in the radially outward drection so that an inclined face is presented to the stop member, and the stop member may have a portion which tapers towards said another clutch component so that an inclined face is presented to that of the locking member.

The two inclined faces cooperate in the manner of wedges so as to prevent movement of the stop member relative to said one clutch component in the direction towards said another clutch component. As relative movement of the stop member takes place in the direction away from said another clutch component the locking member moves radially outwards so as to maintain the wedging action. Advantageously, the intermediate pressure plate is said one clutch component, and the drive plate is said another clutch component. Alternatively, the main pressure plate is said one clutch component.

Conveniently the stop member is in the form of a pin which is cut away in a region between its ends to form the tapered portion. A spring may be provided to bias the pin towards said another clutch component and so hold it in contact with the locking member. If the stop member and locking member are carried by the intermediate pressure plate of a twin clutch and this plate is biased away from the drive plate, the stop member may have a second end portion which projects from the other side of the intermediate pressure plate for contact with a non-axially movable clutch part during disengagement of the clutch. The progressive repositioning of the stop member which takes place ensures that the distance between the stop member and the said clutch part when the clutch is in the engaged condition always remains constant. Alternatively, in the case where the intermediate pressure plate is biased away from the main pressure plate of a twin clutch, the second end portion may extend into or through a bore in the main pressure plate and be formed with a stop surface which faces towards the drive plate and is engaged by an abutment surface of the main pressure plate when the latter has moved through a predetermined distance away from the drive plate during disengagement of the clutch. The progressive readjustment of the stop member relative to the intermediate pressure plate ensures that this distance remains constant despite changes in the engaged positions of the pressure plates caused by clutch wear.

In the case of a twin clutch in which the intermediate pressure plate is biased away from the main pressure plate by coil springs or other means, the stop member may be housed in an axially extending bore in the main pressure plate and be arranged to cooperate with a locking member housed in a radially extending bore in that plate, in the manner generally as described hereinbefore. In this case, the stop member may have a projecting portion which extends into or through a bore in the intermediate pressure plate and has a head which cooperates with an abutment surface of the intermediate pressure plate to prevent more than a predetermined amount of relative separation between the two plates during disengagement of the clutch.

To compensate for wear of the friction facings, the stop member may have an end surface which makes contact with the drive plate in order to shift the stop member in the direction away from the drive plate as and when necessary, upon return of the clutch to its engaged condition.

The stop and locking members may cooperate other than in a wedging action. Thus for example, the members may be provided with ratchet-like teeth.

It also falls within the scope of the invention for the stop member to be carried by the drive plate or a part rotating therewith. In any such embodiment, the clutch is provided with a plurality of mechanisms in accordance with the invention.

One embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which: Figure 1 is an axial section showing parts of a clutch in which the invention is embodied; Figure 2 is a partly sectioned view looking in the direction of arrow II shown in Figure 1; Figure 3 is a section taken on the line III-III in Figure 2; and Figure 4 is a scrap sectional view showing a detail of the main pressure plate.

Figure 5 is a view similar to part of Figure 2 but showing a modification.

Figure 6 is a section taken on the line VI-VI in Figure 5.

Referring to Figure 1 of the drawings, a twin clutch for a motor vehicle includes a drive plate 1 constituted by the flywheel of an internal combustion engine, a main pressure plate 2 and an intermediate pressure plate 3. Pressure applied by a diaphragm spring 4 causes the pressure plates 2 and 3 to clamp driven plates 5 and 6. The diaphragm spring 4 is supported on rivets 7 projecting from a pressed cover 8. To disengage the clutch, a release mechanism is operated so as to press a bearing 10 against radially inwardly projecting fingers of the diaphragm spring 4. The spring 4 is engaged by fulcrum rings 9 so that, during disengagement, the peripheral part of the spring moves in the rearward direction, that is, away from the drive plate 1. As shown in Figure 4, clips 11, fitted to studs projecting from the main pressure plate 2, ensure that this plate follows the rearward movement of the peripheral part of the diaphragm spring 4.

The intermediate pressure plate 3 has radially outwardly projecting lugs 12 which are coupled by straps 13 to the drive plate 1 to ensure that the drive plate and the intermediate pressure plate 3 rotate together. The straps 13 are so prestressed that they cause the intermediate pressure plate 3 to move rearwardly when the pressure applied to it by the main pressure plate 2 is removed. To prevent the pressure plates 2 and 3 from continuing to clamp the driven plate 6, each of the lugs 12 is provided with a stop member 14 which is housed in an axially extending bore in that lug. Each stop member 14 abuts against an adaptor ring 15 when the intermediate pressure plate 3 has moved through a predetermined distance which is less than that through which the main pressure plate 2 is moved by the spring 4 during disengagement.

As the friction facings 16 of the clutch wear and become thinner, the pressure plates 2 and 3 will take up engaged positions which are nearer to the drive plate than those illustrated. To ensure that the distance through which the intermediate pressure plate 3 moves during disengagement remains constant, each stop member 14 has a portion which projects from its bore and makes contact with the drive plate 1. Each stop member 14 is, therefore, shifted axially within its bore as and when necesary by contact with the drive plate 1. In order to prevent each stop member 14 sliding in its bore upon contact with the adaptor ring 15, a respective locking member 17 is arranged in a respective radial bore which intersects that of that stop member. Each stop member 14 and its associated locking member 17 each have tapered portions so that they make contact by way of inclined, plane faces, 20, 21 respectively. Each locking member 17 thus acts in the manner of a wedge to prevent return movement of its stop member 14. As adjustment of the stop member 14 takes place, the locking members move radially outwardly under the action of centrifugal force, assisted, preferably, by compression springs 18. Each stop member 14 is preferably biased towards the drive plate 1 by a compression spring 19 interposed between the side of the corresponding lug 12 and a circlip fitted to an end portion of that stop member.

Referring now to Figures 5 and 6, a twin plate clutch generally as shown in Figures 1 to 4 has modified stop members 14 each of which, as before, is formed from a cylindrical pin which has been machined to form an inclined face 20 for co-operation with the inclined face 21 of the associated locking member 17.

Instead of leaving the remaining partcylindrical surface portion of each stop member 14 intact, this surface portion is relieved by machining two intersecting flats 22 and 23 at an angle of 1200 to each other, so that the only portions of the stop member to bear against the wall of the bore are the two remaining generally opposite, part cylindrical portions 24 and 25.

The line of intersection between the flats 22 and 23 lies in a plane A which includes the axis of the cylindrical blank from which the stop member 14 is formed, and which is spaced, rotationally, by an angle of 10 from a plane B which includes said axis and is perpendicular to the inclined face 20.

It has been found that a modified stop member of this construction has less tendency, if any, to be dislodged by certain vibrations, than the stop member shown in Figures 2 and 3. Of course, other forms of stop member are possible and likewise changes may be made in the arrangement of the clutch. Thus, each stop member may abut against the cover itself rather than a ring bolted to the cover. Separate springs may be provided to bias the intermediate pressure plate away from the drive plate.

Alternatively, the intermediate pressure plate may be biased away from the main pressure plate, and the a stop members may each project through a bore in a lug projecting from the main pressure plate. In this case, each stop member has a head which is engageable with the rearward side face of the associated lug. Another possibility is to mount the stop members and the locking members in bores in the main pressure plate. In this latter case, each stop member may pass through an aperture in the intermediate pressure plate and have an enlarged head which engages on one side with the drive plate and on the other side with the intermediate pressure plate.

Also, the stop members may be progressively adjusted relative to the intermediate pressure plate by contact with the clutch cover or adaptor ring. With this arrangement, each stop member may have a neck portion which projects through an aperture in the adaptor ring and/or clutch cover. The neck portion is provided with a head for contact with the rear surface of the adaptor ring or clutch cover. The main body part of each stop member has an annular stop face surrounding the neck for contact with the forward side of the adaptor ring as described.

Alternatively, the stop members and locking members may be housed within the drive plate, the adaptor ring or the clutch cover. With this arrangement, progressive adjustment of the stop members in response to wear is produced by contact between the stop member and the intermediate pressure plate as clutch engagement takes place. As the wear on the friction surfaces increases, the stop members must move progressively towards the drive plate, or further into their bores in the drive plate, as the case may be.

WHAT WE CLAIM IS: 1. A mechanism for controlling the movement of an intermediate pressure plate of a multi-plate clutch, said mechanism comprising means for biasing the intermedi ate pressure plate in a predetermined direction, a stop member carried by one of the components of the clutch for determining the maximum amount of movement of the intermediate pressure plate under the action of said bias, the stop member being movable in said predetermined direction to compensate for variations in the position occupied by the intermediate pressure plate when the clutch is in its engaged condition, and a locking member movable relative to the stop member in a direction generally perpendicular to said predetermined direction, the locking member being engageable with the stop member to prevent movement of the stop member in a direction opposite to said predetermined direction, whilst allowing th stop member to move relatively freely in said predetermined direction.

2. A mechanism as claimed in Claim 1, wherein the stop member is housed within an axially extending bore in said one clutch component, and has a first end portion which projects from the bore towards another clutch component for contact therewith.

3. A mechanism as claimed in Claim 2, wherein the locking member is housed within a bore which extends generally radially of said one clutch component, and which intersects the bore housing the stop member, the bores being offset so that the locking member projects to one side of the stop member.

4. A mechanism as claimed in Claim 3, wherein the locking member has a portion which tapers in the radially outwards direction, whereby the locking member presents an inclined face to the stop member.

5. A mechanism as claimed in Claim 4, wherein the stop member has a portion which tapers towards said another clutch component so that the stop member presents an inclined face to the inclined face of the locking member.

6. A mechanism as claimed in Claim 5, wherein the stop member is in the form of a pin which is cut away in a region between its ends to form the tapered portion.

7. A mechanism as claimed in Claim 6, wherein the remaining surface portion of the pin is relieved axially to reduce the area of contact between the stop member and the surface of its bore.

8. A mechanism as claimed in any one of Claims 2 to 7, including a spring for biasing the stop member towards said another clutch component.

9. A mechanism as claimed in any of Claims 2 to 8, wherein the intermediate pressure plate is said one clutch component and the drive plate is said another clutch component.

10. A twin clutch comprising an intermediate pressure plate disposed between a drive plate and a main pressure plate, the intermediate pressure plate being arranged to clamp one driven plate against the drive plate, and the main pressure plate being arranged to clamp another driven plate against the intermediate pressure plate, and a plurality of mechanisms as claimed in any of Claims 1 to 9.

11. A clutch as claimed in Claim 10 when appendant to Claim 9, wherein said biasing means biases the intermediate pressure plate away from the drive plate; the stop member of each mechanism having a second end portion which projects from the side of the intermediate pressure plate remote from the drive plate for contact with a non-axially movable clutch part as clutch disengagement takes place.

12. A clutch as claimed in Claim 10 when appendant to Claim 9, said biasing means biases the intermediate pressure plate away from the main pressure plate, the stop member of each mechanism having a second end portion which extends into or through a bore in the main pressure plate and is formed with a stop surface which faces towards the drive plate and is engaged by an abutment surface of the main pressure plate when the latter has moved through a predetermined distance away from the drive plate during disengagement of the clutch.

13. A clutch as claimed in Claims 10 when appendant to any one of Claims 1 to 8, wherein said biasing means biases the intermediate pressure away from the main pressure plate, and each mechanism is carried by the main pressure plate; the stop member of each mechanism having a portion which extends into or through a bore in the intermediate pressure plate, said portion having a head for co-operation with an abutment surface of the intermediate pressure plate to limit the separation of the pressure plates, each stop member having

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. each stop member has an annular stop face surrounding the neck for contact with the forward side of the adaptor ring as described. Alternatively, the stop members and locking members may be housed within the drive plate, the adaptor ring or the clutch cover. With this arrangement, progressive adjustment of the stop members in response to wear is produced by contact between the stop member and the intermediate pressure plate as clutch engagement takes place. As the wear on the friction surfaces increases, the stop members must move progressively towards the drive plate, or further into their bores in the drive plate, as the case may be. WHAT WE CLAIM IS:

1. A mechanism for controlling the movement of an intermediate pressure plate of a multi-plate clutch, said mechanism comprising means for biasing the intermedi ate pressure plate in a predetermined direction, a stop member carried by one of the components of the clutch for determining the maximum amount of movement of the intermediate pressure plate under the action of said bias, the stop member being movable in said predetermined direction to compensate for variations in the position occupied by the intermediate pressure plate when the clutch is in its engaged condition, and a locking member movable relative to the stop member in a direction generally perpendicular to said predetermined direction, the locking member being engageable with the stop member to prevent movement of the stop member in a direction opposite to said predetermined direction, whilst allowing th stop member to move relatively freely in said predetermined direction.

an end surface for contact with the drive plate.

14. A mechanism as claimed in Claim 1 for controlling the movement of an intermediate pressure plate of a multi-plate clutch and substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

15. A multi-plate clutch substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

16. A multi-plate clutch substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings, but as modified by Figures 5 and 6 thereof.