GB2236571A

GB2236571A - Self-centering clutch bearing device

Info

Publication number: GB2236571A
Application number: GB9021340A
Authority: GB
Inventors: Fabrice Caron
Original assignee: SKF France SAS
Current assignee: SKF France SAS
Priority date: 1989-10-02
Filing date: 1990-10-01
Publication date: 1991-04-10
Anticipated expiration: 2010-10-01
Also published as: DE9013580U1; ES2026012A6; FR2652623B1; IT1241704B; FR2652623A1; IT9067742A0; GB9021340D0; GB2236571B; IT9067742A1

Abstract

A clutch bearing device of the traction type comprises a rolling bearing (2); a guide sleeve (3) having a tubular part (15) capable of sliding on a guide tube (16), and a radial collar (17) in frictional contact with self-centring means exerting an axial force on the rolling bearing held by a supporting element; and means of axial connection (4, 20) between the rolling bearing and the clutch diaphragm (23). The self-centring means comprise a self-centring bracket (19) having a fastening part (29) capable of interacting with the non-rotating ring (7) of the rolling bearing, and a resilient part (32) capable of exerting an axial force between the radial collar (17) of the guide sleeve (3) and the rolling bearing (2). A seal may be formed or mounted between the bracket (19) and either one of the rings (6, 7) of the rolling bearing (2) (Figs 3-5). <IMAGE>

Description

SELF-CENTRING CLUTCH BEARING DEVICE OF THE TRACTION TYPE The present invention relates to a self-centring clutch bearing device, especially of the traction type, for motor vehicles. This type of bearing works under traction and in permanent contact with the rear face of the diaphragm of the disengaging device by way of means of axial connection between the rolling bearing and the clutch diaphragm. The permanent contact is obtained during the operating periods of the clutch device by means of a slight axial prestress.

Clutch devices of this type generally comprise a rolling bearing and a guide sleeve which can slide on a guide tube, the rolling bearing being capable of experiencing radial self-centring movements during the clutch release operations. In fact, it is necessary to allow the rolling bearing to move radially in relation to the guide sleeve and to centre itself during operation in relation to the axis of rotation of the said diaphragm. This selfcentring function is indispensable for the smooth functioning of the clutch bearing, for by virtue of construction, in view of the various production tolerances and operating plays, the axis of rotation of the bearing and the axis of rotation of the clutch diaphragm do not necessarily coincide with one another after the various elements have been assembled.It is therefore expedient for the bearing to have the possibility of self-alignment in relation to the diaphragm during each clutch release operation, otherwise operating anomalies and a premature wear of the members would be found.

The self-centring means conventionally used generally comprise an elastic element interposed radially or axially between the rolling bearing and its support, for example the guide sleeve, the rolling bearing thus having some degree of freedom of movement in relation to this support.

French Patent Applications 2,553,846 and 2,545,172 (VALEO) may be mentioned by way of example to illustrate traction-type bearing devices of this type. In these patent applications, the self-centring of the bearing is obtained by means of a corrugated washer interposed between a front face of the non-rotating ring of the rolling bearing and the collar of the guide sleeve. This corrugated washer, by virtue of its structure, has some elasticity and thus exerts on the nonrotating ring of the rolling bearing an axial force tending to push this against the support element which is usually a collar integral with a cover surrounding the rolling bearing.

Although this type of self-centring washer is suitable for rolling bearings comprising solid rings, as described in the abovementioned French patent applications, it is nevertheless particularly inappropriate when the rolling bearing comprises rings produced from deepdrawn sheet metal. In this case, in fact, the rings of the rolling bearing are of a small thickness and their geometry is not suited to the use of such corrugated washers as self-centring means because of the presence of sharp edges and the inadequacy of plane supporting surfaces for the self-centring washer.

Moreover, the known self-centring washers, whether corrugated washers, as described in the abovementioned patent applications, or washers of conical profile of the Belleville washer type, can perform only their self-centring function. Now as regards rolling bearings comprising rings produced by deep-drawing from a metal sheet or tube, it is often necessary also to ensure an axial connection of the rings of the rolling bearing, so that the rolling bearing, once assembled, constitutes a unit which cannot be dismantled during manipulation before the final assembly of the clutch bearing device. It is also frequently necessary to provide a protection and a sealing of the rolling bearing. Where self-centring washers of the conventional type are used, therefore, a plurality of complementary elements, each performing its own function, has to be provided.

The object of the present invention is to over come these difficulties by a simple self-centring means which can be used especially for rolling bearings comprising thin rings produced by the deep-drawing of a tube or a metal sheet, but which is also suitable for rolling bearings having solid rings produced by lathe-turning, the said self-centring means performing not only the self-centring function, but also the function of axial retention of the bearing rings after assembly.

Another object of the invention is to provide such a self-centring means which, furthermore, can perform simultaneously a function of protecting and/or of sealing the rolling bearing.

The clutch bearing device of the traction type according to the invention comprises a rolling bearing, a guide sleeve having a tubular part capable of sliding on a guide tube, and a radial collar in frictional contact with self-centring means exerting an axial force on the rolling bearing held by the supporting element, and means of axial connection between the rolling bearing and the clutch diaphragm. According to the invention, the self-centring means comprise a self-centring bracket having a solid fastening part of general cylindrical shape, capable of interacting closely with the outer cylindrical surface of the non-rotating ring of the rolling bearing, and an elastic part capable of exerting an axial force between the radial collar of the guide sleeve and the rolling bearing.

The elastic part of the self-centring bracket can advantageously have a general conical shape similar to an umbrella, with a large aperture angle.

The elastic part of the self-centring bracket can be solid or can have a plurality of tabs separated by recesses, so as to increase its elasticity.

The fastening of the self-centring bracket takes place in the vicinity of the free edge of the fastening part which for this purpose can possess means for fixing to the non-rotating ring of the bearing. The fastening can be carried out by crimping, by snapping or by any other equivalent means.

In an advantageous embodiment, the fixing means consist of elastic snapping tabs which are fastened to the non-rotating ring of the bearing.

In an advantageous embodiment of the invention, the elastic part of the self-centring bracket is connected to the fastening part by means of a connecting part penetrating between the two rings of the bearing in order to ensure the protection of the rolling bearing, in the manner of a labyrinth gasket.

An elastic sealing ring can also be mounted between the bracket and at least one of the rings of the rolling bearing in order to ensure the sealing of the bearing.

A cover surrounding the rolling bearing and the guide sleeve generally completes the clutch bearing device of the invention and performs the function of a supporting element for the rolling bearing counter to the force exerted by the self-centring bracket.

In an advantageous embodiment of the invention, the rolling rings of the bearing are produced by deepdrawing from a metal sheet or a tube. It will be appreciated, however, that the invention can also be used when the rings of the bearing are solid and produced by latheturning.

The invention will be understood better from a study of the detailed description of some embodiments taken.as non-limiting examples and illustrated by the accompanying drawings in which: Figure 1 is a sectional half-view of a first embodiment of a clutch bearing device according to the invention; Figure 2 is a partial sectional half-view identical to that of Figure 1, showing essentially the selfcentring means; Figure 3 is a partial sectional half-view, similar to that of Figure 2, of an alternative embodiment; Figure 4 is a partial sectional half-view showing a second alternative embodiment of the self-centring means; Figure 5 is a similar partial sectional half-view showing a third version of the self-centring means; Figure 6 is an outer side half-view of the selfcentring bracket used in the clutch bearing device illustrated in Figures 1 and 2; and Figure 7 is a partial elevation view of the selfcentring bracket of Figure 6.

As illustrated in Figures 1 and 2, the clutch device according to the invention comprises an accosting piece 1, a rolling bearing 2 and a guide sleeve 3. The rolling bearing 2 and the accosting piece 1 are fixed to one another in an axial direction by means of an elastic fixing ring 4 which, here, is a split metal hoop formed by a winding of a metal wire, the assembly as a whole having a general toroidal shape of circular cross-section and being capable of experiencing a variation of diameter.

The rolling bearing 2 comprises, in the conventional way, a plurality of balls 5 capable of rolling on the respective rolling tracks of a rotating inner ring 6 and of a stationary outer ring 7 which are produced by deep-drawing. The balls 5 are maintained at uniform circumferential spacings by means of a cage 8. The outer ring 7 has a radial collar 9 directed inwards and a cylindrical portion 10. A cover 11 grips the assembly consisting of the rolling bearing 2 and of the guide sleeve 3. For this purpose, the cover 11 possesses, at one of its ends, a radial collar 12 directed inwards and coming to bear axially against the collar 9 of the outer ring 7.At its other end, the cover 11 has an outwardly directed radial collar 13, on which can come to bear the fingers 14 of the clutch fork, illustrated diagrammatically in the Figure, which are capable of exerting an axial pull on the clutch bearing device as a whole.

The guide sleeve 3 has a tubular part 15 capable of sliding on a guide tube 16 and a radial collar 17. The tubular part 15 extends on either side of the radial collar 17. The radial collar 17, at its free end, has an annular portion 18 which engages into a receptacle provided on the cover 11, so as to ensure that the sliding sleeve 3 and the cover 11 are fixed to one another.

An annular self-centring bracket 19 is mounted on the stationary outer ring 7 and ensures elastic frictional contact against one of the front faces of the radial collar 17. The rolling bearing 2 can thus move radially slightly in relation to the guide sleeve 3, so as to enable it to self-centre during a clutch release operation.

The accosting piece 1 has a cylindrical part 20 directed towards the rolling bearing 2 and having an annular groove for receiving the fixing ring 4. The accosting piece 1 also possesses, at its opposite end, a toroidal part 22 which engages the rear face of the diaphragm 23 of the clutch. The axial connection between the accosting piece 1 and the diaphragm 23 before and during the assembly operations on the vehicle is made by the snapping of a washer 24 onto the cylindrical part 20 of the accosting piece 1, with the interposition of an elastic hoop 25 which makes it possible to improve the centring of the accosting piece on the diaphragm before the rolling bearing 2 is assembled on the accosting piece 1.

The inner ring 6 has an annular rim 26, the profile of which is designed to be capable of interacting with the fixing ring 4 when the latter is seated in its receiving groove. Once mounted, the traction-type clutch bearing device always undergoes an axial pulling force exerted in the same direction, this force varying between a preload value, when the clutch pedal is not actuated, and an increasing disengaging force during an operation to release the clutch under the action of the fingers 14 of the clutch fork. It will be seen that the fingers 14 of the clutch fork which, here, bear on the supporting surface of the collar 13 of the cover 11 can also act directly on the guide sleeve 3 which therefore has a suitable configuration.The axial forces exerted by the fingers 14 of the clutch fork are consequently transmitted by the cover 11 to the rolling bearing 2 which subsequently retransmits them to the diaphragm 23 by way of the accosting piece 1 fixed to the rolling bearing 2 as a result of the presence of the ring 4.

An annular crown fixed to the collar 17 of the guide sleeve 3 by means of three flexible elastic tabs 28 can come in contact with the fixing ring 4 during the assembly operations.

The self-centring bracket 19 has a fastening part 29 of general continuous cylindrical shape, which interacts with the cylindrical portion 10 of the non-rotating outer ring 7 of the bearing 2. In the embodiment illustrated, the fastening of the self-centring bracket 19 is obtained by the snapping of a plurality of elastic fastening tabs 30 (Figure 7), the free end 31 of which is curved to make it easier for the bracket 19 to be mounted on the outer ring 7. As can be seen from an examination of Figures 1 and 2, the fastening tabs 30 are curved inwards slightly and follow the profile of the outer ring 7, thus ensuring the fastening of the self-centring bracket 19 on the bearing 2.

The cylindrical fastening part 29, in contrast to the part having the tabs 30 arranged along the free edge of the said fastening part, is therefore solid and thus ensures excellent interaction with the cylindrical outer surface of the non-rotating outer ring 7. The centring of the bracket 19 in relation to the ring 7 is thereby ensured. The close contact resulting from this between the bracket 19 and the ring 7 makes it possible, furthermore, to guarantee a correct sealing relative to the lubricant contained in the bearing.

Moreover, the self-centring bracket 19 comprises an elastic part 32 which, in the embodiment illustrated in Figures 1, 2, 6 and 7, is of general conical shape similar to an umbrella with a very large vertex angle in a rather similar way to a Belleville washer. In the embodiment illustrated in the abovementioned Figures, the elastic part 32 has a plurality of elastic tabs 33 separated from one another by recesses 34, so as further to improve the elasticity of the elastic part 32. The free ends 35 of the elastic tabs 33 are curved axially, to prevent any risk of jamming during radial selfcentring movements of the rolling bearing 2 accompanied by the self-centring bracket 19 which remains in frictional contact against the front surface of the radial collar 17.

The elastic part 32 equipped with its tabs 33 exerts an axial force on the non-rotating ring 7 of the rolling bearing 2 which bears with its radial collar 9 against the radial collar 12 of the cover 11, the latter thus serving as an axial supporting element for the rolling bearing 2.

Although the fastening of the self-centring bracket 19 to the non-rotating ring 7 by the snapping of the elastic tabs 30 has been shown here, it will be appreciated that this fastening can be obtained in another way, for example by crimping or by any other means.

In the same way, the elastic part 32, comprising elastic tabs 33 here, could be made solid in another embodiment.

In the embodiment illustrated in Figure 3 where identical or similar parts bear the same references, the self-centring bracket 19 has an annular connecting part 36 arranged between the elastic part 32 and the fastening part 29. The connecting part 36 penetrates partially into the space located between the outer ring 7 and the inner ring 6 which, in this embodiment, is without the outwardly directed radial collar which it had in the embodiment illustrated in Figures 1 and 2. The connecting part 36 thus performs a function of protecting the rolling bearing 2, virtually preventing the penetration of any foreign body. The connecting part 36 also performs a sealing function in the manner of a labyrinth gasket between the self-centring bracket 19, stationary since it is fixed to the stationary outer ring 7, and the rotating inner ring 6.

In the embodiment illustrated in Figure 4 where identical or similar parts bear the same references, a sealing ring 37 having an annular lip 38 is gripped between the self-centring bracket 19 and the front edge of the stationary outer ring 7. This gripping is obtained directly by means of the elastic tabs 30 snapped onto the outer ring 7. The sealing lip 38 is in contact with the cylindrical outer surface of the rotating inner ring 6 which has the same structure as in the embodiment of Figure 3, thus ensuring the sealing of the rolling bearing 2. In this embodiment, the self-centring bracket 19 has virtually the same structure as in the embodiment of Figures 1, 2, 6 and 7, the axial dimensions of the fastening part 29 being increased in order to allow for the thickness of the ring 37.

In the embodiment of Figure 5 in which identical or similar parts bear the same references, the selfcentring bracket 19 possesses, as in the embodiment illustrated in Figure 3, a connecting part 36 which partially penetrates between the two rings 9 and 6. A sealing ring 39 equipped with a lip 40 is also fastened in the vicinity of the free end of the elastic part 32 on the inner face of the cone, in such a way that the sealing lip 40 comes in contact with the bore of the rotating inner ring 6. The sealing ring 39 is advantageously moulded onto the elastic part 32 of the self-centring-bracket 19.

The invention makes it possible to obtain a selfcentring means of simple structure which is capable of performing its self-centring function, whatever the structure of the rings of the bearing. Although the bearing rings were produced by the deep-drawing of a metal sheet or a tube in the examples illustrated, it will be appreciated, in fact, that the self-centring bracket illustrated can easily be modified so as to be suitable for a solid ring of a rolling bearing.

Moreover, the self-centring bracket of the invention also makes it possible to perform simultaneously the functions of protecting and/or sealing the rolling bearing.

Claims

1. Clutch bearing device of the traction type comprising a rolling bearing; a guide sleeve having a tubular part capable of sliding on a guide tube, and a radial collar in frictional contact with self-centring means exerting an axial force on the rolling bearing held by a supporting element; and means of axial connection between the rolling bearing and a clutch diaphragm; the self-centring means comprising a self-centring bracket having a fastening part of generally cylindrical shape capable of interacting with the outer shape of the non-rotating ring of the rolling bearing, and an elastic part capable of exerting an axial force between the radial collar of the guide sleeve and the rolling bearing tending to move the said non-rotating ring away from the said radial collar.

2. Clutch bearing device according to claim 1, in which the elastic part of the self-centring bracket has a generally conical shape similar to an umbrella.

3. Clutch bearing device according to claim 2, in which the elastic part of the self-centring bracket is solid.

4. Clutch bearing device according to claim 2, in which the elastic part of the self-centring bracket has a plurality of elastic tabs separated by recesses.

5. Clutch bearing device according to any one of the preceding claims, in which the fastening part of the selfcentring bracket possesses, in the vicinity of its free edge, means for fixing to the non-rotating ring of the bearing.

6. Clutch bearing device according to claim 5, in which the fixing means consist of elastic tabs for snapping onto the non-rotating ring of the bearing.

7. Clutch bearing device according to any one of the preceding claims, in which the elastic part is connected to the fastening part by means of a connecting part penetrating between the two rings of the bearing in order to ensure the protection of the bearing.

8. Clutch bearing device according to any one of the preceding claims, in which an elastic sealing ring is mounted between the self-centring bracket and at least one of the rings of the bearing.

9. Clutch bearing device according to any one of the preceding claims, in which a cover surrounds the rolling bearing and the guide sleeve and performs the function of an axial support for the rolling bearing counter to the force exerted by the self-centring bracket.

10. Clutch bearing device according to any one of the preceding claims, in which the rings of the rolling bearing are produced by deep-drawing from a metal sheet or a tube.

11. Clutch bearing device substantially as hereinbefore described with reference to Figures 1, 2, 6 and 7, or Figure 3, Figure 4, or Figure 5, of the accompanying drawings.