GB2203515A

GB2203515A - Torsion damper, particularly for a friction disc clutch for an automotive vehicle

Info

Publication number: GB2203515A
Application number: GB08808460A
Authority: GB
Inventors: Michel Graton; Dieter Rohrle
Original assignee: Valeo SE
Current assignee: Valeo SE
Priority date: 1987-04-13
Filing date: 1988-04-11
Publication date: 1988-10-19
Anticipated expiration: 2008-04-11
Also published as: FR2613802B1; FR2613802A1; GB8808460D0; GB2203515B

Abstract

The invention is concerned with a damper, particularly for a friction disc clutch for an automotive vehicle. The damper comprises a damper plate (13) and a hub (10) mounted for rotation with respect to each other against the action of resilient means (20) within the limits of a predetermined range of angular displacement, limited by relative rotational displacement means between the damper plate and hub. The resilient means (20) are disposed between the displacement means in notches respectively provided in opposed relationship to each other in the outer periphery of the hub and the inner periphery of the damper plate. Two support rings (25) disposed axially around the hub (10), fixed to this latter for rotation therewith and respectively situated on either side of the displacement means, ensure the radial positioning of the resilient means. <IMAGE>

Description

TORSION DAMPER. PARTICULARLY FOR A FRICTION DISC CLUTCH FOR AN AUTOMOTIVE VEHICLE The invention relates to a torsion damper, particularly for a friction disc clutch for an automotive vehicle, of the kind comprising a damper plate and a hub mounted for rotation relative to each other against the action of resilient means and within the limits of a predetermined angular displacement, limited by relative rotation displacement means provided between the damper plate and hub, the said resilient means being disposed between the relative rotational displacement means in notches respectively provided in opposed relationship to each other in the outer periphery of the hub and in the inner periphery of the damper plate.

In practice, when such a torsion damping device is applied to the construction of a friction disc clutch for an automotive vehicle, the friction disc and the hub are coupled in rotation by two torsion damping devices acting successively. of which one is called the pre-damper, which comprises resilient means between the damper plate and the hub and is weaker than the other device, which is referred to as the main damper and which includes the resilient means between the damper plate and the friction disc.

In patent FR-2 386 729 there has already been described such a torsion damper, in which the resilient means of the pre-damper comprise at least one helical spring the axis of which is disposed substantially tangentially to one particular pitch circle of the assembly. The spring is interposed between the damper plate and the hub by means of bearing washers having centring pins for the purpose of maintaining the spring radially in position. In greater detail, the spring is arranged in the zone of engagement provided between the hub and the damper plate, in openings which are provided in opposed relationship to each other, respectively in the hub and in the inner periphery of the damper plate.The spring is mounted between two thrust washers located in the apertures, with each thrust washer abutting, in the rest position of the damper, partly against the hub and partly against the damper plate. Each thrust washer is provided with a centring pin which engages in the corresponding end of the spring.

Easy fitting of this spring during assembly is not helped by the presence of the thrust washers, which have the disadvantage of necessitating the provision of openings in the hub and in the damper plate which extend over a greater length than that of the spring.

The invention seeks to reduce these disadvantages while ensuring that the resilient means be maintained satisfactorily in their radial position, and to provide easier and more practical assembly.

To this end the invention offers a torsion damper of the kind described above, in which the resilient means are held by two rings disposed axially around the hub respectively to either side of the displacement means between the damper plate and hub, and being fixed for rotation with the hub.

Thus the rings contribute to the retention of the springs, which are therefore engaged in a cavity defined by the said rings and by the base of the openings in the hub and in the damper plate. The circumferential dimension of the openings is reduced because of the absence of thrust washers. In addition, the shape of the openings is simplified.

In accordance with another advantageous arrangement according to the invention, the resilient means comprise two series of springs, namely a first series of diametrically opposed springs and a second set of springs which are also diametrically opposed but which are of greater stiffness.

As a result of this arrangement, all the resilient means of the pre-damper are adapted to act in stages, the second set of springs, i.e. those of the greater stiffness, being arranged to operate preferably just before the damper plate and the hub come into positive engagement, so as to limit any shocks during the engagement of the teeth.

According to another advantage of the invention, the maintenance of the springs in their radial position, ensured by the two rings fixed to the hub, takes place outside the zone of engagement between the damper plate and the hub, which permits several springs to be located between the teeth.

Other advantages, features and details of the invention will appear from the explicit description which follows, made with reference to the annexed drawings given by way of example and in which: - Figure 1 is an elevation in axial cross section of a torsion damper according to the invention and - Figure 2 is a sectional view taken on the line II-II in Figure 1.

In the chosen embodiment which is shown in Figures 1 and 2, the torsion damper, particularly for a friction disc clutch for an automotive vehicle, comprises two coaxial parts A, B mounted so as to be rotatable within the limits of a predetermined angular range, and against the biassing action of resilient means, one of these parts comprising a hub 10 while the other carries a support plate 11 for friction pads 12.

In a manner known per se, the hub 10 is provided at its internal periphery with splines 10a adapted to allow it to be coupled to the input shaft of the gearbox, while the friction pads 12 are adapted to be gripped between two clutch plates mounted on the crank shaft of the vehicle, for rotation therewith.

The first part A of the said parts comprises, apart from the hub 10, an annular radial damper plate 13 mounted so as to surround the hub coaxially. The hub 10 and the damper plate 13 are mounted so as to be rotatable with respect to each other against the action of resilient means and within the limits of a predetermined range of angles, which is limited by relative rotational displacement means provided between them for this purpose.

In regard to the construction of such displacement means the hub 10 carries externally, in its middle zone and projecting radially therefrom, a peripheral collar 15, which only extends over one portion of its axial link, and in which there are provided radially extending grooves 16, similar to each other, with pairs of these grooves defining teeth 17. In association therewith, the damper plate 13 has at its internal periphery teeth 18 defined by grooves 19. The teeth 18 of the plate 13 are engaged radially within the grooves 16 of the hub, so that the teeth 17 of the hub are radially engaged in the grooves 19 of the damper plate. This radial engagement takes place with a predetermined circumferential clearance defining the limits of the angular displacement between the damper plate 13 and the hub 10.

The hub 10 has two pairs of teeth 17 diametrically opposed to each other, and the damper plate 13 has at least two diametrically opposed full teeth 18 which respectively engage between the pairs of teeth 17.

The resilient means mentioned. above are arranged in the zone of mutual engagement between the hub 10 and damper plate 13, and comprise two pairs of helical springs 20, 20', the springs 20' being of greater stiffness than the springs 20.

The springs 20 are individually mounted in through openings 21A, 21B of the hub 10 and of the damper plate 13 respectively, being mutually in opposed relationship to each other (Figure 2).

The through openings 21A, which are two in number, comprise notches provided in the outer peripheral surface of the collar 15 of the hub 10, and extend over lengths substantially equal to that of each of the springs 20. The two through openings 21A are diametrically opposed and respectively situated on either side of the zone of engagement between damper plate and hub.

The through openings 21B, which are two in number, comprise notches formed on the inner periphery of the damper plate 13, and extend over lengths substantially equal to those of each of the springs 20. The two through openings 21B are diametrically opposed and are situated respectively on either side of the zone of engagement between damper plate and hub.

In a similar way, the springs 20' are also individually mounted in through openings 22A, 22B of the hub 10 and of the damper plate 13, and are mutually opposite to each other. The two through openings 22A comprise diametrically opposed notches on the outer periphery of the collar 15 of the hub 10, and the two through openings 22B comprise diametrically opposed notches in the inner periphery of the damper plate 13, these through openings 22B each extending over a length greater than that of the springs 20' so that the latter, under the rotational action of the damper plate 13, act after the springs 20. In practice, only one of the side edges of each through opening 22B is in contact with the associated spring 20'.It is also to be noted that the side edges of the grooves 19 and the adjacent side edges of the notches 21B, 22B define two truncated teeth 18' which are situated respectively on either side of the pair of full teeth 18.

In order to ensure, particularly, that the resilient means 20, 20' are satisfactorily maintained in their radial location, two rings 25 are provided which are respectively mounted on either side 'of the peripheral collar of the hub 10, and which are fixed to the latter.

The outer peripheral surface of the hub 10 has, on either side of its peripheral collar 15, a radially projecting annular peripheral zone 26 and an annular peripheral terminal zone of smaller diameter, which defines with the zone 26 a transverse shoulder 27.

Each support ring 25, provided with teeth in its inner peripheral surface and made of a harder material than that of the hub, is force fitted on to the zone 26 of the hub 10 so as to bear against the adjacent face of the peripheral collar 15 of the hub 10. Each support ring is fully secured to the hub 10, particularly in the axial direction, by means of a securing element 28 which is then applied to the zone 26 of the hub 10.

Each ring 25 has notches 25A in its inner periphery to accommodate the different springs 20, 20' without any circumferential clearance, these notches being four in number in the example shown, and disposed mutually opposite to the notches 21A, 22A 21B, 22B of the damper plate and hub.

The second part of the torsion damper has two guide rings 30A, 30B which are disposed respectively on either side of the damper plate 13. These two guide rings 30A, 30B are secured to each other by means of tie bars 31, which are inserted through the guide rings and through holes provided in the damper plate 13, the latter with clearance. The support plate 11 for the friction pads 12 is secured to one of the guide rings, 30A, by rivets 32.

Resilient means are circumferentially interposed between the coaxial parts A, B of the damper. These resilient means generally comprise a plurality of springs, all of which extend circumferentially on the same pitch circle, and these springs may have different stiffnesses.

In the example under consideration, only one spring 33 is shown, and, using an arrangement which is known in itself and which need not be described in detail hereafter, the spring 33 is mounted in a through opening partly formed in the damper plate 13 and partly in the guide rings 30A, 30B.

Two friction rings 40, having an internal diameter greater than that of the support rings 25, are disposed respectively on either side of the damper plate 13. These rings 40 carry axially extending pins 41, which engage in corresponding holes provided in the adjacent guide rings 30A, 30B so as to secure them for rotation with these latter. Between the friction ring 40 and the guide ring 30A, a spacer ring is inserted, having on its outer periphery axially extending tabs 43, which engage in corresponding notches of the damper plate 13 to retain them and to entrain them for rotation with the latter.

On the other side of the damper plate 13, between the friction ring 40 and guide ring 30B, there is mounted a resilient biassing means 44 such as a Belleville washer, which is centred by means of a shoulder 45 provided on the internal periphery of the friction ring 40. The purpose of this biassing means 44 is to urge the friction rings 40 against the damper plate 13.

On one side of the guide ring 30A, a bush 46 mounted around the hub 10 bears against the shoulder 27. This bush 46 includes a radial face plate 47 which extends between the shoulder 27 and the guide ring 30A. The bush 46 is disposed radially between the hub 10 and the inner peripheral edge of the guide ring 30A, and is secured for rotation with this latter, for example by projections engaged in recesses.

On the other side, a friction ring 48 is mounted against the shoulder 27 of the hub 10 and is held against the latter by a resilient biassing means 49 mounted around the hub 10 between the ring 48 and the guide ring 30B.

In a low torque mode, for example at the dead point position of the gear box of a motor car, the reaction torque encountered by the hub 10, mounted on the input shaft of the gear box, is in the neighbourhood of zero, so that the movement transmitted by the guide rings 30A, 30B is transmitted almost directly on to the damper plate 13, the stiffness of the angular displacement springs 33 being of an order of magnitude greater than the forces brought into play at this stage.

Within the limits of the angular clearance provided between the damper plate 13 and the hub 10, the movement is thus transmitted through the damper plate, first compressing the springs 20 which are opposed to rotation of the damper plate 13 with respect to the hub, since they are mounted without clearance in the through openings 21A, 21B and the notches 25A.

Continued rotation of the damper plate 13 causes the edge of the notches 22B to compress the springs 20' before the damper plate 13 and the hub 10 come into positive engagement with each other through their respective teeth, so as to reduce as much as possible the oscillations that are liable to arise, and to limit shocks during engagement of the teeth, whereby to avoid premature wear of the latter.

Subsequently, when the torque increases it is the springs 30 of the main damper which come into play.

The invention is of course not limited to the embodiment described. In particular, the springs 20' may be of different stiffness and the notches 22B may be different, while the invention may be applied to any torsion damper, the support plate for friction pads being replaced by another element.

Claims

CLAIMS:

1. A torsion damper, particularly for a friction disc clutch for an automotive vehicle, of the kind comprising a damper plate and a hub mounted for rotation relative to each other against the action of resilient means and within the limits of a predetermined angular displacement, limited by relative rotation displacement means provided between the damper plate and hub, the said resilient means being disposed between the relative rotational displacement means in notches respectively provided in opposed relationship to each other in the outer periphery of the hub and in the inner periphery of the damper plate, and wherein support rings for the said resilient means are disposed axially around the hub and fixed to the hub for rotation therewith.

2. A torsion damper according to Claim 1, wherein support rings are fixed with a force fit around the hub and secured.

3. A torsion damper according. to Claim 1 or Claim 2, wherein said rings have notches in their inner periphery which are mutually opposite to notches of the hub and of the damper plate.

4. A torsion damper according to any one of Claims 1 to 3, wherein said resilient means comprise at least two springs of different stiffness.

5. A torsion damper according to Claim 4, wherein said resilient means comprise two pairs of springs, the springs of each pair being substantially diametrically opposed.

6. A torsion damper according to any one of the preceding Claims wherein said relative rotational displacement means between the damper plate and hub comprise at least two full teeth, substantially diametrically opposed, in the inner periphery of the damper plate, and two teeth in the outer periphery of the hub situated respectively on either side of each tooth.

7. A torsion damper according to Claim 6, wherein said relative rotational displacement means also comprise two truncated teeth respectively on either side of each tooth.

8. A torsion damper for a friction disc clutch, substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.