GB2125934A

GB2125934A - A friction clutch

Info

Publication number: GB2125934A
Application number: GB08322141A
Authority: GB
Inventors: Harald Raab; Hilmar Gobel
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1982-08-18
Filing date: 1983-08-17
Publication date: 1984-03-14
Also published as: FR2532019A1; GB8322141D0; DE3230663A1; GB2125934B; FR2532019B1; DE3230663C2

Abstract

A motor-vehicle friction clutch comprises a hub (2), hub flange (3) and side discs (7, 8) which are rotatable relative to the hub (2) against the action of springs (5). Between the first side disc (8) and the hub flange (3) is arranged a control disc (9) which controls the operational condition of a load friction damper (16). The latter comprises a friction disc (19) between the hub flange (3) and the control disc (9) and a friction ring (18) between the control disc (9) and a thrust disc (23), which is independent of the side disc (8) and is pressed towards the hub flange (3) by a spring (21). The no-load friction damper (17) is arranged between the hub flange (3) and the second side disc (7) and comprises a friction ring (20), a thrust plate (24) connected to the second side disc (7) to be secured against rotation, and a spring (22) clamped between the thrust plate (24) and the side disc (7). The spring (21) clamps the first side disc (8) via an external edge zone of the friction ring (18), the control disc (9) and the friction ring (19) against the hub flange (3). <IMAGE>

Description

SPECIFICATION A friction clutch The invention relates to a clutch e.g. for a motor-vehicle and, more especially, to a clutch provided with a torsional vibration damper.

A clutch for a motor-vehicle is known from German utility model 7 538 331. The clutch comprises, as usual, a hub with a radially projecting hub flange and two side discs or cover plates which are arranged on axially opposite sides of the hub flange. The side discs are fixedly connected to each other and to the friction linings of the clutch disc. They are rotatable relative to the hub through a limited angle of rotation, this relative rotation being damped by several damping springs. The damping springs sit in windows of the hub flange and of the side discs and are subjected to pressure during the relative movements of these parts.

The known clutch furthermore comprises a load friction damper dimensioned for the load operation condition as well as a no-load friction damper dimensioned for the no-load condition.

The load friction damper is connected in dependence on the torque transmitted by the clutch disc and is disconnected in the no-load operation condition. For controlling the load friction damper there is provided a control disc which sits axially between the first of the two side discs and the hub flange and can be supported on the side discs via at least one control spring.

Friction rings of the load friction damper are active between the control disc and the hub flange, a biassing spring, which is arranged axially outside the two side discs, producing the bias necessary therefor.

The no-load friction damper, including its thrust plate and its biassing spring, sits on the outside of the second side disc which is opposite to the load friction damper.

On this known clutch, there are provided two control plates which are fixedly connected together. Over and above this, additional fastening elements are fitted to the hub for supporting the elements of the no-load friction damper. The known clutch disc is therefore relatively expensive and has relatively large axial dimensions. Over the above this, the relatively sensitive components of the no-load friction damper are unprotected.

It is the object of the invention to improve the afore-described clutch in such a way that the disadvantages thereof are avoided. In particular, the aim is to make it possible to produce the clutch in a simpler manner and with a lower expenditure of components and to render the space requirement in the axial direction as small as possible.

According to the invention, the thrust plate and the biassing spring of the no-load friction damper are arranged axially between the hub flange and the adjacent second side disc. The first side disc is supported on the hub flange. All friction rings of the no-load friction damper are accommodated in a protected manner between the two side discs.

On the side of the no-load friction damper, no stops or the like are necessary for producing the biassing force.

The first side disc may be supported directly on an axial shoulder of the hub or of the hub flange.

However, preferably, the first side disc is supported on the hub flange via the control disc.

The support thereof may be effected via a friction ring of the no-load friction damper, which ring is arranged between the control disc and the first side disc. This friction ring may be a radial extension of a friction ring of the load friction damper, which is utilised in several ways in this manner.

The mounting of the side discs, which have been fixedly connected together so as to form a unit, on the hub is expediently effected by means of an angle ring which guides the side disc adjacent to the no-load friction damper radially. In order to reduce any undesired extraneous friction in the no-load operation, the angle ring, which is preferably made of metal, is expediently coated with a plastics material with good sliding properties. However, the angle ring may be completely made of this plastics material.

Expediently, the control springs of the load friction damper sit under bias in windows of the hub flange. The control springs co-operate with stops in the side discs, which are formed by the windows of the side discs. For an exalt guidance of the control springs, provision has been made for the windows of the side discs to be designed as pockets which are closed axially towards the outside. The pockets are so formed that the control springs bear against the pockets only punctiformly or linearly in the axial direction. In this way, it is possible to reduce the friction between the control springs and the side discs to a minimum.

Hereinafter, an exemplified embodiment of the invention will be explained in more detail with reference to the drawings, in which: Figure 1 shows a partial view of a vibration damped motor-vehicle friction clutch, considered from the side of its load friction step; Figures 2A and 2B show cross-sectional views of the clutch shown in Fig. 1, considered along a line Il-Il; Figure 3 shows a partial sectional view of the clutch shown in Fig. 1, considered along a line Ill-Ill of Fig. 2A, and Figure 4 shows a detail view of the clutch, partly cut away and considered in the direction of an arrow IV in Fig. 2A.

The clutch 1 comprises a hub 2 which is mounted on a gear shaft not shown so as to be secured against rotation but so as to be axially displaceable. The hub 2 has a radially outwardly extending hub disc 3 which, in hub windows 4, receives damping springs 5 of different strength and, in hub windows 4a, receives control springs 6. In Fig. 2A, there are shown by means of an angularly displaced representation, both one of the damping springs 5 and one of the control springs 6. In the present case, there are provided, as Fig. 1 shows, two control springs 6, which are approximately opposite to each other, whilst the damping springs 5 are arranged therebetween in the circumferential direction.On either side of the hub disc 3 there are provided cover plates 7 and 8 respectively, which are fastened to each other via separating rivets 1 0. The separating rivets 10 penetrate corresponding oblong holes 1 0a in the hub disc 3. Between the cover plate 8 and the hub disc 3, there is additionally arranged a control plate 9 which is in communication with the control springs 6, also via a window 12. In the zone of the control springs 6, the cover plates 7 and 8 are provided with pockets 14 which guide the control springs 6 in the axial direction.

Considered in the circumferential direction, these pockets 14 end in stops 1 5 which co-operate with the control springs 6. The damping springs 5 engage in windows 13 of the two cover plates 7, 8. 8. The load friction step 1 6 on the side of the control plate 9 consists of a friction ring 1 9 between the hub disc 3 and the control plate 9, a friction ring 1 8 between the control plate 9 and the cover plate 8, this friction ring having a diameter which is larger than the inside diameter 27 of the cover plate 8, and furthermore of a thrust ring 23, which is arranged approximately radially inside the inside diameter 27, and a spring 21 as well as a supporting ring 33 which is arranged on the hub 2 so as to be secured against rotation and so as to be axially fixed.The thrust ring 23 is guided via axially bent tabs 35 in corresponding slots 36 in the supporting ring 33 so as to be secured against rotation but so as to be axially movable. The no-load friction step 1 7 on the axially opposite side of the hub flange 3 consists of a friction ring 20, adjoining the hub disc 3, and of a thrust ring 24, which is mounted via appropriately axially angled tabs 24a in openings 24b in the cover plate 7 so as to be secured against rotation but so as to be axially displaceable, as well as of a spring 22 between the thrust ring 24 and the cover plate 7. The mounting of all parts which are rotatable relative to one another on the hub 2 is effected via an angle ring 28, which is approximately L-shaped in cross section, has a cylindrical zone 29 as a guide with respect to the hub 2 and comprises a disc shaped zone 30.The disc-shaped zone 30 carries tabs 31 which are angled towards the outside in an approximately U-shaped manner and which engage in corresponding slots 32 in the cover plate 7 for a rotation-proof connection (Fig. 5).

The function of the clutch 1 is as follows:- With the clutch engaged, the clutch 1 is connected into the flux of force between the internal-combustion engine and the drive wheels of the motor vehicle. The transmitted torque causes, in dependence on its magnitude and on its coefficient of cyclic irregularity, the input part of the clutch 1, namely the friction linings 11 with the cover plates 7 and 8, and the output part, the hub 2, to be rotated relative to one another. The control plate 9 is also partly rotated, as will be described in detail later.During any rotational movements between the cover plates 7 and 8 and the hub 2, there is effected a reciprocal guidance via the angle ring 28 which is provided, for example, with a plastics material coat so as to keep the friction low, in the first place, and, in the second place, to allow it to be limited in a defined range since the friction arising here is also active during a no-load operation and during the relative movements occurring as a result. During a no-load operation the no-load friction step 1 7 is active, which consists of the friction ring 20 which comes into action through the spring 22 and the thrust ring 24 on the friction surface 25 of the hub disc 3.The spring 22, in turn, is supported on the hub disc 3 via the cover plate 7, the separating rivets 10, the cover plate 8 and the radially outside zone of the friction ring 1 8 via the control plate 9 and the friction ring 1 9. These mentioned parts also determine the axial position with respect to the hub disc 3.During the no-load operation, the control plate 9 continues to be at rest with respect to the hub disc 3 due to its clamping via the load friction step 1 6. This load friction step 1 6 causes, due to the force in the spring 21 , the control plate 9 to be clamped between the hub disc 3 and the thrust ring 23 with the interposition of the two friction rings 1 8 and 1 9. The slight no-load friction between the radially inside zone of the cover plate 8 and the radially outside zone of the friction ring 1 8 does not cause any change in this regard since the load friction step 1 6 ensures a substantially higher friction force.As soon as the relative rotations increase and, as shown in Fig. 3 in particular, the separating rivets 10 come into abutting contact with the windows 34 in he control plate 9, when, due to appropriate coordination, the stops 1 5 of the pockets 1 4 in the cover plates 7 and 8 simultaneously come into abutting contact with the front ends of the control springs 6, there is effected an entrainment of the control plate 9 with the cover plates 7 and 8 with respect to the hub disc 3. This causes the load friction step 1 6 to come into use, in addition to the no-load friction step 17; there having however to be deducted that proportion of the no-load friction step 1 7 which was active in the no-load range due to the radially inside zone of the cover plate 8 and the radially outside zone of the friction ring 18. In the load range, the cover plate 8 and the control plate 9 must now be regarded as a constructional unit which is secured against rotation, causing the friction force to be produced between the friction surface 26 of the hub disc 3 and the thrust ring 23 which is non-rotatably connected to the hub disc 3 via the tabs 35 and the slots 36 of the supporting ring 33. In the load range, there is added to this friction force the friction force of the no-load friction step 17, produced by means of the friction surface 25, the friction ring 20 and the thrust ring 24 and the pressure force exerted by the spring 22. In the load range, the control springs 6 are also compressed to a greater or lesser degree. They ensure, during the return rotation to the central position, the re-setting of the control plate 9.By the appropriate adjustment of the biassing force of the control springs 6 it is possible to allow this return to occur in advance or to postpone it upon the movement reversal.

The mode of operation of the other torsion springs 5 is like that of the prior art, and it is only a question of adjustment whether these springs come into action together or successively so as to produce a specific spring load deflection curve.

They only serve for producing a specific spring characteristic in the torque transmission range.

A brief reference will now be made to Fig. 4 which shows a partial view of the clutch 1 from the side of the no-load friction step 1 7. It shows the radially inside zone of the cover plate 7 which has been joined with the angle ring 28 so as to form a constructional unit. The angle ring 28 is pressed with its axially projecting tabs 31 in corresponding slots 32 of the cover plate 7 so that the two components form one unit. By this means, it is possible to mount the two cover plates 7 and 8 via the cylindrical zone 29 of the angle ring 28 on the hub 2 in the radial direction. The disc shaped zone 30 of the angle ring 28 serves, with respect to the hub disc 3, as a stop during the production or assembly of the clutch 1 for protecting the spring 22 from overloading.

Claims

1. A friction clutch comprising a) a hub (2) which defines an axis of rotation of the clutch disc and carries a radially projecting rigid hub flange (3), b) two fixedly connected side discs (7, 8) which are arranged on axially opposite sides of the hub flange (3) and which are rotatable relative to the hub (2) through a limited angle of rotation and are axially displaceably mounted thereon, c) friction linings (11) which are connected to the side discs (7, 8), d) at least one damping spring (5) which is arranged in windows (4a, 13) of the hub flange (3) and of the side discs (7, 8) and which is subjected to pressure during the relative movements of the side discs (7, 8) and the hub (2), e) a control disc (9) which annularly embraces the hub (2) and is axially arranged between the first (8) of the two side discs (7, 8) and the hub flange (3) and which is mounted on the hub (2) so as to be rotatable through a limited angle of rotation relative to the side discs (7, 8), f) at least one control spring (6) which is arranged in windows (4, 12, 14) of the hub flange (3) of the control disc (9) and at least one of the side discs (7, 8) and which is subjected to pressure during the relative movements of the side discs (7, 8) and the control disc (9), g) a load friction damper (16) provided with a friction ring (19), which is arranged axially between the hub flange (3) and the control disc (9), and with a biassing spring (21), which presses the control disc (9) via the friction ring (19) against the hub flange (3), on that side of the first side disc (8) that is axially directed away from the control disc (9), and with an axially displaceable pressure transmission element (23), which passes through at least one opening (27) in the first side disc (8), axially between the control disc (9) and the biassing spring (21), h) a no-load friction damper (17) provided with a friction ring (2), which is arranged axially between the hub flange (3) and the second (7) of the two side discs (7, 8), and with a thrust plate (24), which is guided on the second side disc (7) so as to be secured against rotation but so as to be axially displaceable, and with a biassing spring (22) which is clamped between the thrust plate (24) and the second side disc (7), characterised in that the thrust plate (24) of the no-load friction damper (17) is arranged axially between the second side disc (7) and the friction ring (20) of the no-load friction damper (17), and in that the first side disc (8) is supported on a surface of the hub (2) or of the hub flange (3) that is directed axially towards it.

2. A clutch as claimed in Claim 1, characterised in that the first side disc (8) is supported on the hub flange (3) via the control disc (9).

3. A clutch as claimed in Claim 2, characterised in that axially between the first side disc (8) and the control disc (9) there is arranged a friction ring (18), via which the first side disc (8) is supported on the control disc (9).

4. A clutch as claimed in Claim 3, characterised in that the pressure transmission element of the load friction damper is designed as a thrust plate (23), and in that the friction ring (18) arranged between the first side disc (8) and the control disc (9) is simultaneously clamped axially between this thrust plate (23) and the control disc (9) and forms part of the load friction damper (16).

5. A clutch as claimed in one of Claims 1 to 4, characterised in that the second side disc (7) is mounted on the hub (2) via an angle ring (28), a hollow-cylindrical part (29) of the angle ring (28) guiding the second side disc (7) radially on the hub (2) and a radially projecting disc-shaped part (30) being arranged between the second side disc (7) and the hub flange (3).

6. A clutch as claimed in Claim 5, characterised in that the angle ring (28) is fixedly connected to the second side disc (7).

7. A clutch as claimed in Claim 6, characterised in that there have been bent from the disc-shaped part (30) of the angle ring (28) several tabs (31) which engage in recesses (32) in the second side disc (7) and retain the angle ring (28) on the second side disc (7) so that it is secured against rotation.

8. A clutch as claimed in one of Claims 1 to 7, characterised in that the control spring (6) is retained in the window (4) of the hub flange (3) in the circumferential direction and under biassing, and in that the windows of the side discs which are associated with the control spring (6) are designed as pockets (14) which are closed axially towards the outside.

9. A friction clutch substantially as described herein with reference to Figures 1 to 4 of the accompanying drawings.