GB2118273A - Hub assembly for a clutch driven plate - Google Patents

Abstract

A hub assembly for a clutch driven plate includes a hub (40) and flange (46) forced fitted together, the flange having hard teeth which cut serrations in the hub during assembly. To provide space for material cut during the assembly operation, there is a groove in the hub which is partially overhung by an abutment sleeve (45). In a preferred embodiment the sleeve acts as a journal bearing for a friction facing carrier assembly. <IMAGE>

Description

SPECIFICATION Hub assembly for a clutch driven plate This invention relates to clutch driven plates for motor vehicles.

A conventional clutch driven plate includes a splined hub member having a radially extending flange. It has been proposed, for reasons of economy, to fabricate the hub member from a bar turned hub and an annular flange stamping. One means of joining the hub and flange is to force fit the components together, one of the hub or flange being of harder material than the other and having teeth on the mating surface to cut grooves into the softer component.

Such an arrangement provides an attractive and inexpensive way of fabricating the hub member but has several manufacturing disadvantages.

Firstly a recess must be provided for the metal chips cut out of the softer metal, a recess of good chip machining shape can be difficult to machine.

Secondiy, an abutment surface must be provided on the hub against which the flange is urged to both position the flange in the correct axial position with respect to the hub and to ensure minimal flange run-out. Metal chips cut out of the softer metal can become trapped against the abutment surface preventing accurate location of the flange.

According to the present invention there is provided a hub assembly for a clutch driven plate and including a hub and flange force fitted together, the flange being of harder material than the hub and having teeth to cut into the hub on assembly, an abutment being provided on the hub against which the flange is urged and a circumferentially extending groove being provided in the hub for waste material cut by the flange, the abutment overhanging said groove, characterised thereby that said abutment is provided by a sleeve located by a land and a shoulder of said hub.

Preferably the groove is an open groove, that is to say one having no undercut. A hub having such a groove may be turned on a lathe using a radially moving form tool.

The sleeve may provide a journal bearing for a friction facing carrier assembly of the driven plate; hitherto the carrier assembly has been journalled on a land of the relatively soft hub which wears rapidly. The hardness of the sleeve may thus be optimised for bearing loads whilst that of the hub may be optimised for assembly with the flange.

The sleeve may also provide a thrust bearing for the carrier assembly and in a particular embodiment of the invention the sleeve is of 'L' section. In this embodiment the sleeve may be of plastics material, the radial face acting as a friction washer to damp angular movement between the hub and carrier assemblies in a known manner. It is intended that relative movement takes place between the sleeve and the co-operating hub land and positive location between the sleeve and the carrier assembly may be provided by any convenient method.

Other features of the invention are included in the following description of two preferred embodiments shown, by way of example only, in the accompanying drawings in which: Figure 1 is a plan view of a typical clutch driven plate; Figure 2 is an axial section through a typical clutch driven plate and showing the invention; Figure 3 is an axial section through prior art hub and flange components before assembly; Figure 4 is an axial section through the hub, flange and sleeve components according to the invention; Figure 5 is an axial section through a hub assembly formed from the components of Fig.

4; and Figure 6 is a further embodiment of the invention and showing an alternative sleeve.

With reference to Figs. 1 and 2 of the drawings there is shown a clutch driven plate 11 suitable for a motor vehicle and comprising a splined hub 2 having a radially extending flange 1 3 fixed thereto. Circumferentially spaced apertures 14 of the flange 1 3 house coil springs 1 5.

An annular friction facing carrier assembly is mounted on the hub 1 2 for limited relative angular movement. The assembly comprises a carrier plate 1 6 and cover plate 1 7 held together by rivets 1 8 passing through peripheral cut outs 1 9 of the flange 1 3. The plates 16 and 17 have apertures 20, 21 corresponding to the flange apertures 14, the end walls of the apertures 20, 21 abutting the coil springs 1 5. Shrouds 22, 23 of the plates 16, 1 7 retain the springs in the carrier assembly.

Relative angular movement between the carrier assembly and hub/flange assembly is opposed by the springs 1 5 and limited by abutment of a rivet 1 8 with one end wall of a respective cut out 19. A friction washer 24, shown, for example, between the carrier plate 1 6 and flange 1 3 provides a damping effect in a known manner. A Belleville spring 28 may be provided to pre-load the carrier plate 1 6 against the friction washers.

Friction facings 26, 27 are attached by a plurality of thin spring steel plates 29 to the friction facing carrier plate 1 6.

In operation torque is transmitted from the friction facings 26, 27 to the hub 12, the springs and friction washers acting together to cushion the drive. The springs can be of different rate or pre-load and may act in parallel or series as desired. Such driven plates are well understood in the art.

With reference to Fig. 3 a prior art means of fastening the hub and flange is shown.

The hub 30 has the usual splines 31 and a stepped outer periphery including a bearing face 32, an abutment face 33, a chip receiv ins groove 34 and a fastening rim 35. The annular flange 36 has axially extending serrations defining a plurality of individual cutting teeth 37.

On assembly the flange is urged on to the hub towards the abutment face 33 in the direction of arrow A, the teeth 37 cutting grooves in the rim 35 and the resultant waste metal chips being urged into the groove 34. A further rim 38 of the hub may be turned up to secure the flange or other means, such as circlips may be employed.

The bearing face 32 locates and guides the carrier plate 16, and hence carrier assembly, for angular movement relative to the hub. The carrier plate 1 6 frequently grooves the bearing face 32 after a period of service resulting in misalignment of the hub and carrier assembly and also in unwanted extra friction opposing movement between the hub and assembly.

Such a fabrication provides a strong hub assembly of good accuracy and neat appearance.

The outer periphery of the hub 30 is conveniently formed by turning on a lathe but the chip receiving groove 34 is difficult to machine because it undercuts the abutment face 33. The cutting tool is required to move both radially and axially of the workpiece and as a result the hub periphery must be machined in several stages. It is important for the groove 34 to be accurately machined to ensure that the waste metal chips are retained and do not become trapped against the abutment face.

With reference to Fig. 4 there is shown improved means for fabricating the hub member.

The hub 40 is formed as before and includes a shoulder 41, groove 42, and rims 43 and 44. The periphery of the hub may be machined in a single turning operation by means of a radially moving form tool. A plain sleeve 45 fits snugly on the hub against the shoulder 41 and substantially closes the groove 42 to form a chip receiving recess.

The outer face of the sleeve 45 now forms the abutment against which the flange 46 is urged, the waste metal chips being contained in the recess formed by the groove 42 and sleeve 45. The flange is secured as previously described or by any other convenient method.

The fabricated hub assembly is shown in Fig.

5, the flange secured by a turned up ring 47.

Apart from the ease of maching the hub 40, a further advantage of this construction is that the sleeve 45 may be of hard material to resist grooving by the carrier plate 1 6.

The internal edge of the sleeve 45 may be chamfered to guide the waste metal chips into the recess.

An alternative construction, shown in Fig.

6, has the plain sleeve 45 replaced by a 'L' section bearing sleeve 51 which provides a radial and axial bearing surface for the carrier plate 52 or may co-operate with a friction washer 53 to damp movement of the carrier plate with respect to the hub. The bearing sleeve 51 defines a chip-receiving recess 54 and provides an abutment for the flange 46 as previously described. Dependent on the mechanical properties of the sleeve material, which may be for example a plastics moulding, some additional radial support may be required for the sleeve as the flange is pushed onto the hub.

Where a plastics material is used for the sleeve 51 it is desirable that relative movement takes place between the sleeve and the hub to avoid grooving of the sleeve by the carrier plate 52.

The sleeve may be located in the carrier plate by means of flats or a keyway or any other convenient means.

Claims (7)

1. A hub assembly for a clutch driven plate and including a hub and flange force fitted together, the flange being of harder material than the hub and having teeth to cut into the hub on assembly, an abutment being provided on the hub against which the flange is urged and a circumferentially extending groove being provided in the hub for waste material cut by the flange, the abutment overhanging said groove, characterised thereby that said abutment is provided by a sleeve located by a land and a shoulder of said hub.

2. A hub assembly according to Claim 1, characterised thereby that said groove is an open groove as hereinbefore defined.

3. A hub assembly according to Claim 2, characterised thereby that said sleeve provides a journal bearing for a friction facing carrier assembly of the clutch.

4. A hub assembly according to Claim 3, characterised thereby that said sleeve provides a thrust bearing for a friction facing carrier assembly of the clutch.

5. A hub assembly according to Claim 4, characterised thereby that said sleeve is substantially of 'L' section.

6. A hub assembly according to any of Claims 2-5, characterised thereby that said groove is substantially of rectangular section.

7. A hub assembly substantially as described herein with reference to the accompanying drawings.