GB2052001A - Clutch withdrawal bearing assembly - Google Patents

Abstract

A clutch withdrawal bearing assembly comprises a ball bearing (1, 6) which can move radially in relation to a guide sleeve (10) to enable it to centre itself with respect to the clutch. Axial clamping of a radial portion (8) of the outer bearing ring (6) to a portion (9) of the guide sleeve (10) to enable the self-centering to take place is effected by a plurality of clamping blades (37) which form integral parts of a friction plate (38) on which in use, a clutch withdrawal fork acts. The blades (37) produce a resilient axial clamping force. The clamping arrangement is simple and reduces the total number of parts in the assembly and thus the cost. <IMAGE>

Description

SPECIFiCATION Clutch withdrawal bearing assembly This invention relates to clutch withdrawal bearing assemblies incorporating devices for selfcentering the assembly with the clutch when the clutch is disengaged.

The devices incorporate means which ciamp a portion of a bearing ring of the assembly against a portion of a guide sleeve, but allows some radial movement between the two portions to take place to provide the self-centering action. The assembly is particularly for use with diaphragm clutches, and comprises a guide sleeve which, in use, is slidable axially on a guide tube, the sleeve having a radially outwardly extending portion, a rolling contact bearing which has an inner bearing ring and an outer bearing ring, one of the bearing rings having a radially extending portion which is clamped in frictional sliding contact with one face of the radially outwardly extending portion of the sleeve, an opposite face of the radially outwardly extending portion of the sleeve being covered by a plate which, in use, is engaged by a clutch withdrawal fork, and the other bearing ring, in use, engaging with a clutch release member.

Some assemblies such as this are provided with resilient devices allowing a certain amount of radial movement of the sleeve with respect to the guide tube. The radial portion of the guide sleeve is protected by the plate and this makes it possible to make the guide sleeve of a plastics material, for example, by moulding. This lightens the assembly and improves the sliding of the sleeve on the guide tube.

The object of the present invention is to provide a self-centering clutch assembly as described above of simplified form and accordingly of reduced cost.

According to this invention, we provide a selfcentering clutch withdrawal bearing assembly comprising a guide sleeve which, in use, is slidable axially on a guide tube, the sleeve having a radially outwardly extending portion, a rolling contact bearing which has an inner bearing ring and an outer bearing ring, one of the bearing rings having a radially extending portion which is clamped in frictional sliding contact with one face of the radially outwardly extending portion of the sleeve, an opposite face of the radially outwardly extending portion of the sleeve being covered by a plate which, in use, is engaged by a clutch withdrawal fork, and the other bearing ring, in use, engaging with a clutch release member, wherein the radially extending portion of the bearing ring is clamped resiliently to the radially outwardly extending portion of the sleeve by a plurality of clamping blades which extend from the plate and exert substantially axial clamping forces on the radially extending portion of the bearing ring, the ends of the blades remote from the plate being in engagement with the radially extending portion of the bearing ring.

The plate and the resilient clamping blades form a single unit, which simplifies the manufacture and assembly of the bearing assembly.

The clamping blades can engage with either an outwardly directed or an inwardly directed portion of the bearing ring.

The clamping blades can engage with either part of the radial portion of the bearing ring which is in contact with the radial portion of the guide sleeve or with some other part of the radial portion of the said bearing ring. The clamping blades include in all cases a resilient flexible portion which provides the necessary resilience of clamping.

In one example, the radial portion of the bearing ring has radial projections which interlock with the clamping blades. To ensure locking against rotation of the fixed bearing ring relative to the guide sleeve, one of the radial projections preferably has a slot and one of the clamping blades engages in this slot.

In another example, the clamping blades each comprise two tongues separated by a slot at one end of which there is a bent section, and a locking clip extends from the bent section. Alternatively it is possible to provide at least one resiliently flexible corrugation in each clamping blade to provide the resilience.

When the blades engage with an outwardly directed radial portion of the bearing ruing, it is of advantage if the ends of the clamping blades engage over the outside of a bearing protection plate fitted co-axially with the friction plate. The radial portion of the guide sleeve preferably has slots in which the clamping blades fit to lock the plate and the blades in position angularly.

In another example, in which the blades are engaged with an inwardly directed radial portion of the bearing ring, the clamping blades pass through openings in the radial portion of the guide sleeve, the openings being near the inner periphery of the radial portion. The assembly in accordance with the invention can have a bearing in which the inner bearing ring rotates when it comes into contact with the diaphragm or other release member of the clutch, or, on the other hand, the outer bearing ring may be rotatable with the inner ring being fixed. In all cases, the resilient clamping blades interlocking with the radial portion of the guide sleeve grip the bearing ring which remains fixed.

Several examples of assemblies in accordance with the invention are illustrated in the accompanying drawings in which: Figure 1 is an axial sectional view of a first example; Figure 2 is a developed partiai external view showing part of the example of Figure Figure 3 is an axial sectional view of a second example; Figure 4 is an axial sectional view of a third example; Figure 5 is a section on the line V-V in Figure 4; and Figure 6 is an axial sectional view of a fourth example.

Inthe example shown in Figures 1 and 2, the assembly comprises a thin-walled inner bearing ring 1 of pressed sheet-metal or metal tubing having a tubular section 2 and an annular bearing race 3 for a ring of balls 4. The tubular section 2 has an annular extension which in operation engages a clutch diaphragm or other clutch release member (not shown) to disengage the clutch. The bearing of the assembly also includes a fixed outer bearing ring which is also thin-walled and made of pressed sheet metal or tubing. The outer ring 6 has an annular bearing race for the balls 4 and a radial portion 8 directed inwards, and aligned axially with the section of the inner ring 1.

Part of a front annular surface of the portion 8 is in friction contact with annular radially extending section 9 which is an integral part of a guide sleeve 10. The sleeve 10 is preferably made of reinforced plastics material and is able to slide on a guide tube 11 which is shown in chain-dotted lines in Figure 1.

Resilient clamping betweenthe radial section 9 and the outer bearing ring 6 is effected by four clamping blades 37 which are formed as axial extensions of a plate 38. The plate 38, which is annular, is a metal plate covering the right hand face of the radial section 9, the left hand face of which is in contact with the radial portion 8 of the outer ring 6. When the assembly is in use, a clutch withdrawal fork (not shown) exerts a force on the plate 38 and in this way moves the assembly axially on the guide tube 11 with the guide sleeve 10 sliding on the guide tube.

The plate 38 has pairs of axially extending tongues 39 which are separated by a slot having at one end a part 40 bent inwards. A locking clip 41 extends from the bent part 40 and has at its end a hole 42 which receives a radial projection 43 of a protection plate 44, which prevents dirt from penetrating into the bearing. After bending over the projections 43, of which there are the same number as there are blades 37, the blades are fixed and clamped on the protection plate 44 by crimping. A radial portion 14 of the outer bearing ring 6 is gripped between the protection plate 44 and a part 41 a which separates the locking clip 41 from the rest of the clamping blade 37. The periphery of the radial portion 9 of the guide sleeve 10 has slots 46 (see Figure 2) through which the tongues 39 extend to lock the plate 38 and the parts connected to it against rotation on the sleeve 10.

To allow the size of the metal sheet from which the single part comprising the plate 38 and the clamping blades 37 is produced to be reduced as far as possible, it will be noted that the locking clip 41 is cut out from a section of metal sheet between the two tongues 39, and is then bent at 1 800 outwards. This produces the structure which has been described and which is shown in Figures 1 and 2. In this method of manufacture, the resilient clamping is produced by the bowing of the section 40 in an axial direction as shown by the dotted line 40a in Figure 2.

Other ways of producing the resilience of clamping are of course possible, e.g. by providing corrugations on the clamping blades 37 between the radial portion 9 of the guide sleeve 10 and the radial portion 14 of the outer bearing ring 6.

When the clutch withdrawal fork acts on the plate 38 to produce an axial thrust, the whole of the assembly moves axially in relation to the guide tube 11 with the guide sleeve 1 0 sliding on the tube 11. The ball bearing of the assembly can move in a radial plane so that it centres itself in relation to the clutch plate which comes into contact with the annular section 5 of the inner bearing ring 1 which is thus caused to rotate. Selfcentering is brought about by radial movement of the ball bearing, while the radial portion 8 of the outer bearing ring is kept in contact with the face of the radial section 9 of the guide sleeve 10. The freedom needed for self-centering is produced by the elastic clamping effect obtained by the axial tongues 39 and the locking clips 41 which are elastically joined together by means of the bent sections 40.

In the example shown in Figure 3, in which the parts which are the same as in the first example are designated by the same reference numerals, an annular friction plate 47 has at its inner periphery four axial tongues 48 joined to a radial section of the friction plate 47 by curved pieces which allow the resilience of the tongues 48 to be maintained. A radial portion 50 of a guide sleeve 51 has four openings 52 through which the tongues 48 extend. The inwardly directed radial portion 8 of the outer bearing ring 6 is clamped against the radial portion 50 by outwardly bent sections 53 of the tongues 48, the resilience of clamping being maintained by the curved pieces 49. It will be noted that the radial portion 8 has an entry chamfer 54 which facilitates the bending of the tongues 48 when they are fitted within the portion 8.Moreover, there is freedom of movement between the tongues 48 and the inner periphery of the radial portion 8 to allow the selfcentering of the assembly to take place in operation. In this example, a protection plate 55 of the ball bearing is simply crimped on to the radial section 14 of the outer bearing ring 6.

The example shown in Figures 4 and 5 differs from the previous examples in that the contact between the assembly and the clutch plate or other clutch release member is effected by means of the outer bearing ring of the assembly which is rotatable. For this purpose the outer ring 56 has an annular section 57. A bearing protection plate 58 is crimped on to a radial section 59 of the outer ring 56. The inner bearing ring 60 which is fixed has a tubular section 61 and an annular bearing race for the balls 4. The inner bearing ring 60 has an outwardly directed radial portion 63 one face of which is in contact with a corresponding face of a radial ring-shaped section 64 of the guide sleeve 65.

As can best be seen in Figure 5, the radial portion 63 of the inner bearing ring 60 has pairs of radial projections 71 regulariy spaced around its external periphery. Each pair of projections interlocks with a clamping blade 67 formed by an extension bent at 900 from the plate 68. The clamping blades 67 are resilient owing to their inwardly bent curved form at their ends 69.

To ensure locking during rotation of the single piece formed by the friction plate 68 and the various clamping blades 67, one of the radial projections, numered 66a, has a slot 70 of larger radial extent than that of the clamping blades 67.

As can be seen from Figures 4 and 5, the clamping blade 67 which interlocks with the radial projection 66a can therefore project into the slot 70 with a certain amount of clearance. The end 69 of this clamping blade 67 therefore rests against the radial sides of the slot 70, preventing rotation of the plate 68 and the blades 67 relative to the inner ring 60.

In the example shown in Figure 6, the parts which are the same as those in the previous examples are designated by the same reference numerals. In the example shown in Figure 6, there is again a ball bearing fitted with an inner ring 1 which is rotatable in the same way as in the examples shown in Figures 1 to 3. The fixed outer bearing ring 6 has a radial portion 14 which is directed outwards and has, on its outer periphery, several projections 66 which have the same shape as in the example shown in Figures 4 and 5. The projections 66 interlock with the curved ends 69 of clamping blades 67 which form an integral part of an annular friction plate 72, which is similar to the friction plate 68. A protection plate 75 is crimped on to the radial portion 14 between the projections 66.As in the example shown in Figures 4 and 5, at least one of the projections 66 has a slot 70 which effects locking during rotation of the fixed outer ring 6 relative to sleeve 74. In this example, a radial portion 73 of the guide sleeve 74 is axially curved in the direction of the annular face 5 of the inner bearing ring 1. The outermost part 73a of the portion 73 comes into contact on one of its faces, with the adjacent face of the radial portion 14 of the outer bearing ring 6.

The frictional sliding contact which allows selfcentering is therefore produced by means of movement of the radial portion 14. On the other hand, in the examples illustrated in Figures 1 and 3, the frictional sliding contact which ensures selfcentering is made on the radial portion 8, which is directed inwards.

In all cases, manufacture and assembly is simple and enables resilient axial clamping to be effected by means of a single clamping part which incorporates the friction plate of the assembly.

Claims (12)

1. Aself-centering clutch withdrawal bearing assembly comprising a guide sleeve which, in use, is slidable axially on a guide tube, the sleeve having a radially outwardly extending portion, a rolling contact bearing which has an inner bearing ring and an outer bearing ring, one of the bearing rings having a radially extending portion which is clamped in frictional sliding contact with one face of the radially outwardly extending portion of the sleeve, an opposite face of the radially outwardly extending portion of the sleeve being covered by a plate which, in use, is engaged by a clutch withdrawal fork, and the other bearing ring, in use, engaging with a clutch release member, wherein the radially extending portion of the bearing ring is clamped resiliently to the radially outwardly extending portion of the sleeve by a plurality of clamping blades which extend from the plate and exert substantially axial clamping forces on the radially extending portion of the bearing ring, the ends of the blades remote from the plate being in engagement with the radially extending portion of the bearing ring.

2. an assembly according to claim 1, in which the said ends engage a radially outwardly extending portion of the bearing ring.

3. An assembly according to claim 1, in which the said ends engage a radially inwardly extending portion of the bearing ring, the clamping blades extending through openings in the radially extending portion of the sleeve, the openings being near the inner periphery of the said portion of The sleeve.

4. An assembly according to any one of the preceding claims, in which each clamping blade has a flexible section to provide the resilient clamping.

5. An assembly according to any one of the preceding claims, in which the clamping blades grip the part of the radial portion of the bearing ring which is in contact with the radial portion of the guide sleeve.

6. An assembly according to claim 5, in which the radial portion of the bearing ring has radial projections which interlock with the clamping blades.

7. An assembly according to claim 6, in which one of the radial projections has a slot into which one of the clamping blades extends to lock the bearing ring against rotation relative to the sleeve.

8. An assembly according to claim 4, in which each clamping blade comprises two tongues separated by a slot having a bent portion at one end, and a locking clip extends from the bent portion.

9. An assembly according to claim 8, in which the radial portion of the guide sleeve has slots through which the clamping blades pass and lock in position.

10. An assembly according to claim 4, in which the clamping blades each include at least one flexible corrugation.

11. An assembly according to claim 1 or claim 2, in which the end of each clamping blade has a locking clip with a hole and a radial projection on a bearing protection plate extends through, and is locked in, the hole, the locking being brought about by bending over the projection.

12. An assembly according to any one of the preceding claims, in which the bearing ring having the radially extending portion is the outer bearing ring, the inner bearing ring engaging, in use, with the clutch release member.

1 3. An assembly according to claim 1, substantially as described with reference to Figures 1 and 2, or Figure 3, or Figures 4 and 5, or Figure 6 of the accompanying drawings.