GB2032017A

GB2032017A - Friction clutch and process for the assembly of friction clutches

Info

Publication number: GB2032017A
Application number: GB7933373A
Authority: GB
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1978-09-26
Filing date: 1979-09-26
Publication date: 1980-04-30
Also published as: DE2841763A1; FR2437525B1; GB2032017B; FR2437525A1

Abstract

A diaphragm-spring actuated friction clutch has lugs 9 on its pressure plate 3 which come into contact with abutment tabs 11 on the clutch cover 2 to limit movement of the pressure plate 3 relative to the cover 2 beyond a predetermined position corresponding to maximum acceptable wear. This avoids overstressing drive-transmitting leaf springs 5 interconnecting the pressure plate 3 and the cover 2. To assemble the clutch, the pressure plate 3 is inserted into the cover 2 and then turned to bring extended parts 9a of the lugs 9 axially behind the tabs 11. The leaf springs 5 are then mounted. <IMAGE>

Description

SPECIFICATION Friction clutch and process for the assembly of friction clutches The invention relates to a friction clutch and a process for the assembly of such friction clutches, as are disclosed for example in US patent specification No 3 489 256. In friction clutches of this kind, a plate spring on the one hand bears against a cover and on the other hand applies a loading to a pressure plate, for acting on a friction disc.

The transmission of torque between the cover and the pressure plate is effected by means of a piurality of leaf-spring members which permit axial relative movement of the pressure plate with respect to the cover, wherein so-called movement-restricting means are provided for restricting the axial travel of the pressure plate with respect to the cover, in order to ensure that the leaf springs do not suffer from over-stressing or over-bending, which can occur particularly during transportation, in the course of handling or during assembly or dismantling.As, in by far the greatest number of cases, thus also in the clutches disclosed in the above-mentioned US patent specification, the above-mentioned leaf spring members are also provided to lift off the pressure plate, in addition to the function of transmitting the torque, clutch disengagement would no longer take place in a satisfactory manner if the leaf spring members are over-stressed or deformed.

The movement-restricting means disclosed in the above-mentioned US patent are rivets or loop brackets which are riveted to the cover or to the pressure plate. This construction therefore makes use of separate components which must be inserted individually. This increases the cost of clutches of this kind and, due to the necessary axial space required for fitting the movementfitting restricting means, this clutch construction also requires a considerable axial space, in the axial direction, which makes it difficult, if not quite impossibie, to use clutch discs with thin friction linings.

For this reason, DOS No 26 07 939 has already proposed that the abutment means may be of such a construction that the leaf spring members which are provided for the transmission of torque project beyond the lugs on the pressure plate to which they are secured, as viewed in the peripheral direction, while abutment means are disposed on the cover opposite the abovementioned regions. However, this requires the expenditure on leaf spring material to be higher, if only slightly higher, and also necessitates an assembly operation which is not the optimum operation, in ail cases.

The present invention was based on the problem of avoiding the disadvantages of the previously known friction clutches, and providing friction clutches which are better value for money, both with regard to the materials used and also with regard to assembly, and which moreover ensure easy assembly and reliable operation.

According to the invention, this is achieved in that the movement-restricting means comprise on the one hand radial cantilever arms such as lugs which are formed on the pressure plate and on the other hand, abutments which are formed directly on the cover and which face in the peripheral direction, wherein the cantilever arms and the abutments are disposed axially opposite each other after the pressure plate has first been inserted into the space in the cover and the pressure plate and the cover have been turned relative to each other so that, as viewed in the clutch engagement direction of the pressure plate, the cantilever arms are brought to a position over the abutments, in such a way that they do not come to lie against each other until the pressure plate has covered, relative to the cover, an axial distance corresponding to the travel, caused by wear, of the clutch disc.

In this case, the lug together with the leaf springs secured thereto can come to lie against the abutment which is formed directly by the cover. In by far the greatest number of cases however, it will be advantageous for the pressure plate lug to be directly the movement-restricting means provided on the pressure plate, and for that oh the cover to be a tab-like extension portion which is formed directly from the material of the cover and which engages under the lug. However, this abutment may also be formed by a windowlike opening whose contour which faces in the peripheral direction is disposed opposite the lug.

It may also be advantageous if, in the peripheral direction, the lug is longer, relative to the rivet hole, on the side which is towards the abutment formed on the cover, than on the side of the rivet hole which is remote from the abutment onthe cover.

The process for assembly of such a friction clutch may be distinguished in that the pressure plate is inserted into the axial assembly space in the cover and the pressure plate and the cover are turned relative to each other whereby the lugs come to lie under the abutment of the cover.

For this purpose, the leaf springs may be secured, for example riveted, to the cover, before the pressure plate is introduced into the space in the cover and before the pressure plate and the cover are turned relative to each other, and the leaf springs may be connected to the pressure plate, after the pressure plate has been turned relative to the cover, by connecting means such as rivets being introduced into suitable openings in the leaf springs and the lugs However, the leaf springs may also be secured, for example riveted, to the lugs of the pressure plate, before the pressure plate is introduced into the assembly space in the cover, and the connection between the cover and the leaf springs may be formed, after the pressure plate has been introduced into the space in the cover and after the pressure plate and the cover have been turned relative to each other, in order to bring the lugs over the abutments on the cover, the connection being formed for example by means of rivets which are introduced into suitable openings in the leaf springs and the cover.

It is moreover possible for the connection between the cover and the pressure plate to be made by way of the leaf springs, after the pressure plate has been introduced into the space in the cover and after the pressure plate and the cover have been turned in order to bring the lugs over the abutments, by connecting means such as rivets being inserted on the one hand into the opening in the leaf springs and the lugs and on the other hand into the opening in the leaf springs and the opening in the cover, thereby forming the connection.

The invention will now be described in greater detail with reference to Figures 1 to 4. In the drawings: Figure 1 shows a view of part of a clutch, Figure 2 shows a view in section taken along line Il-Il in Figure 1, and Figures 3 and 4 show two alternative embodiments as viewed along lines Ill and IV in Figure 1.

A plate spring 1 is tiltably secured to and bears against a cover 2 in per se known manner, by way of thrust means (not shown), and applies a loading to a pressure plate 3 in the direction of arrow 4, namely, towards a clutch disc (not shown). The cover 2 and the pressure plate 3 are joined together by way of leaf spring members 5. The difference between the embodiments shown in Figures 3 and 4 is that, in the embodiment shown in Figure 3, the leaf springs 5 are on the side which is remote from the friction surface of the pressure plate 3, while in the embodiment shown in Figure 4, they are on the side which is towards the friction surface of the pressure plate.

The end of the leaf springs 5 which is the leading end, as viewed in the normal direction of rotation as indicated by arrow 6, is secured to the cover by way of rivets 7, while the trailing end is connected by way of rivets 8 to lugs 9 which project radially beyond the friction surface. It will be assumed that the illustrated position of the plate spring in Figure 1 corresponds to that position which it assumes when the clutch is secured by way of the fixing edge portion 10 to the flywheel of an internal combustion engine, with new friction linings on the clutch disc.For the purposes of disengaging the clutch, the plate spring must be pivoted into the position 1 a shown in broken lines, whereby the pressure plate 3 moves into the position 3a shown in broken lines, the pressure plate being lifted away by a distance corresponding to the travel of the plate spring, by the force of the leaf springs 5 which is in opposition to the pressure force of the plate spring.

It will be assumed that a travel, caused by wear, corresponding to the position 3b of the pressure plate on the clutch, as illustrated in dashdotted lines, is available for the clutch, this therefore corresponding to the position 1 b of the plate spring as shown by dash-dotted lines. In this position, the clutch has reached the outermost value of its working range.

In order to ensure that the pressure plate 3 moves outwardly at least corresponding to the working range of the clutch and in order to avoid excessive bending of the leaf springs 5, the cover 2 has cantilever arms 11 which are formed from the material of the cover and which point in the peripheral direction. The lugs 9 lie opposite the arms 11 in the axial direction and can come to bear directly against the arms. It is desirable for the lugs 9 to have a larger portion 9a on this side, as viewed in the peripheral direction on the trailing side thereof, than the portion 9b on the leading side.

It will be seen that the pressure plate, after being inserted into the axial assembly space in the clutch, was turned relative to the cover in order to bring the lugs with their portions 9a to a position over the arms 11.

The clutch may be assembled by the leaf springs 5 firstly being secured to the lugs 9, whereupon, after the pressure plate has been introduced into the space in the cover and after the relative rotary movement thereof, the openings in the leaf springs and the cover for the rivets 7 are aligned, the rivets 7 then being inserted and subsequently riveted.

However, the cover and the pressure plate may also be secured together by a process whereby, for example in the embodiment shown in Figure 3, the leaf springs are firstly riveted to the cover by means of the rivets 7 and, after the pressure plate has been introduced and turned relative to the cover, the leaf springs are riveted to the lugs 9 by means of the rivets 8.

A further possible way of assembling the clutch provides that, after the pressure plate has been introduced and turned relative to the cover, the leaf springs 5 are fitted into place, the rivets 7 and 8 are inserted and the rivets are riveted possibly at a common station.

Under some circumstances, for many assembly situations, it may be advantageous if, relative to the axial travel of the pressure plate, the plate spring already comes to lie against an abutment 2a on the cover, while the abutment 11 and the lug 9 are still at a small spacing from each other.

Claims

1. A friction clutch, in particular for motor vehicles, wherein a plate spring on the one hand bears against a cover and on the other hand applies a loading to a pressure plate for acting on a friction disc, and the transmission of torque between the cover and the pressure plate is effected by means of a plurality of leaf spring-like members which provide for an axial relative movement of the pressure plate with respect to the cover at least over the working range of the clutch which comprises the clutch engagement and disengagement travel and the travel, caused by wear, of the clutch disc, wherein movementrestricting means are provided for restricting the axial travel of the pressure plate relative to the cover, characterised in that the movement restricting means comprise on the one hand radial cantilever arms such as lugs (9) which are formed on the pressure plate (3) and on the other hand, abutments (1') which are formed directly on the cover (2) and which face in the peripheral direction, wherein the cantilever arms and the abutments are disposed axially opposite each other after the pressure plate has first been inserted into the space in the cover and the pressure plate and the cover have been turned relative to each other so that, as viewed in the clutch engagement direction of the pressure plate, the cantilever arms are brought to a position over the abutments, in such a way that they do not come to lie against each other until the pressure plate has covered, relative to the cover, an axial distance corresponding to the travel (3b), caused by wear, of the clutch disc.

2. A friction clutch according to claim 1 characterised in that the pressure plate lugs (9) are directly the movement-restricting means provided on the pressure plate (3), and those provided on the cover (2) are tab-like extension portions (11) which are formed directly from the material of the cover and which engage under the lugs (9).

3. A friction clutch according to claim 1 or claim 2 characterised in that, in the peripheral direction, the lug (9) is longer, relative to the rivet hole, on the side (at 9a) which is towards the abutment ( 1 1 ) formed on the cover (2), that on the side of the rivet hole which is remote from the abutment (11).

4. A process for the production of a friction clutch according to one of claims 1 to 3 characterised in that the pressure plate is inserted into the axial assembly space in the cover and the pressure plate and the cover are turned relative to each other whereby the lugs come to lie under the abutment of the cover.

5. A process according to.claim 4 characterised in that, before the turning operation, the leaf springs are connected, for example riveted, to the cover, and, after the turning operation, the leaf springs are connected to the pressure plate by connecting means such as rivets being inserted for this purpose into the corresponding openings in the leaf springs and the lugs.

6. A process according to claim 4 characterised in that, before the pressure plate is introduced into the assembly space in the cover, the leaf springs are secured, for example riveted, to the lugs of the pressure plate and, after the pressure plate has been introduced and after the pressure plate and the cover have been turned relative to each other, in order to bring the lugs over the abutments, the connection between the cover and the leaf springs is formed, for example by means of rivets which are introduded into suitable openings in the leaf springs and the cover.

7. A friction clutch according to claim 4 characterised in that after the pressure plate has been introduced into the assembly space in the cover and after the pressure plate and the cover have been turned, in order to move the lugs over the abutments, the connection between the cover and the pressure plate is formed by connecting means such as rivets being introduced on the one hand into the openings in the leaf springs and the lugs and on the other hand into the openings in the leaf springs and the cover.

8. A friction clutch substantially as hereinbefore described with reference to the accompanying drawings.