GB2116650A

GB2116650A - Diaphragm spring clutch cover assembly

Info

Publication number: GB2116650A
Application number: GB08207407A
Authority: GB
Inventors: Ronald Dennis Carpenter
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1982-03-13
Filing date: 1982-03-13
Publication date: 1983-09-28
Also published as: GB2116650B

Abstract

In a diaphragm spring clutch the diaphragm spring (16) is mounted at the inner peripheral edge of the cover member (14) by clamping means in the form of tabs (21). The tabs (21) are extended to provide abutment means to limit free coning of the spring. In an alternative (Fig. 6) the abutment means are provided on a support ring (29). <IMAGE>

Description

SPECIFICATION Diaphragm spring clutch cover assembly This invention relates to diaphragm spring clutch cover assemblies particularly, though not exclusive liy for use in drive clutches of motor vehicles.

A diaphragm spring cover assembly usually comprises a clutch cover, a pressure plate held fast for rotation with the cover and a diaphragm spring held by the cover to urge the pressure plate and cover apart. The spring is fulcrumed to the inner periphery of the cover and has a piurality of inwardly directed fingers for contact with a clutch release bearing.

Such clutch cover assemblies have been widely adopted by the motor industry. Our British Patent No. 1 347 485 discloses an assembly in which the spring is held to the cover by bent tabs extending between the spring fingers to trap the spring between fulcrum rings of the cover. This construction is described in greater detail later in this specification.

One problem with existing clutch cover assemblies is that the diaphragm spring adopts its free position, urging the pressure plate and cover apart unless otherwise restrained. This increases the packing envelope of the assembly and can also lead to diaphragm spring breakage as the heavy pressure plate is unrestrianed during transit. A further problem can occur during service replacement of a cover assembly where the envelope of the unrestrained assembly is too large for the access provided by the manufacturer. In this case fitting rings have been proposed to limit coning of the diaphragm spring during removal and replacement.

According to the present invention there is provided a diaphragm spring clutch cover assembly comprising an annular cover member, a pressure plate fast for rotation with the cover member and a diaphragm spring mounted at the inner peripheral edge of the cover member by clamping means including fulcrums for the spring, wherein the clamping means further include abutment means to limit free coning of the spring.

Preferably the invention provides clamping means comprising tabs passing through inwardly extending fingers of the diaphragm spring and turned towards the outer periphery of the assembly to sandwich circular fulcrum rings on either side of the diaphragm spring against the cover member, the tabs extending outwardly from the fulcrum rings to provide abutment means for the spring.

Alternatively the invention provides clamping means comprising tabs passing through inwardly extending fingers of the diaphragm spring and turned towards the outer periphery of the assembly to retain a support ring, the spring being sandwiched by circular fulcrums provided in the support ring and cover member, the support ring extending outwardly from the circular fulcrums and whose edge portion forms said abutment means.

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: Fig. 1 is an axial section through a typical diaphragm spring clutch asembly; Fig. 2 is a plan view of a clutch cover assembly; Fig. 3 is an enlarged section through a clutch cover assembly according to the prior art; Fig. 4 is a part-section corresponding to Fig. 2 and showing the invention; Fig. 5 is a part section through an alternative prior art cover assembly; and Fig. 6 is a part section corresponding to Fig. 5 and showing an alternative embodiment of the invention.

With reference to Figs. 1 and 2 there is shown a typical diaphragm spring clutch assembly for a motor vehicle.

An input shaft 11 from the vehicle engine drives a flywheel 12 having the usual starter ring gear 13. A clutch cover assembly comprising cover pressing 14, pressure plate 15 and diaphragm spring 16 is fixed to the flywheel by bolts 17.

A clutch driven plate 18 is sandwiched between the pressure plate 15 and the flywheel 12 and is splined to an output shaft 19 journalled in the input shaft 11. The output shaft 19 is usually connected to the vehicle transmission.

The diaphragm spring is held by tabs 21 projecting from the inner peripheral cover edge and passing between adjacent spring fingers 22to sandwich the spring between fulcrum rings 23.

Straps 24 transmit drive between the cover 14 and pressure plate 15 and allow limited axial movement therebetween.

As the cover 14 is bolted to the flywheel 12, the pressure plate 15 is urged against the effect of the spring 16to clamp the driven plate 18.

The spring load is released by urging the spring fingers inward to release the load on the pressure plate 15 and so allow the driven plate 18 to spin freely. A release bearing 25 is urged against the inner ends of the fingers for example by a lever 26 connected by a clutch release cable 27 to the driver's clutch pedal. A return spring 28 is provided.

With reference to Fig. 3 there is shown a cover assembly in the free state. Dimension 'A' indicates the packing envelope width and also the minimum access opening needed to remove an assembly in service. It can be seen that the drive straps 24 must allow considerable free movement of the pressure plate with respect to the cover, and because the spring is exerting a negligible load the heavy pressure plate may bounce in transit leading to possible damage to the assembly.

Fig. 4 shows the modification to the assembly wherein the tabs 21 are made slightly longer so that, on assembly, the inwardly turned end of each tab can contact the diaphragm spring to limit its free movement. The load of the spring on the tabs need not be large to appreciably affect the envelope width, shown by dimension 'B'.

The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy. Since the pressure plate 15 is not fully urged out of the cover 14 the drive straps 24 may be shorter thus limiting pressure plate travel during transit. The bolts 17 may also be shorter since the cover can more closely approach the flywheel on initial assembly.

Fig. 5 shows an alternative means of providing an abutment for the diaphragm spring where the fulcrum for the spring is provided by depressions in the cover and in a support ring 29.

The support ring is extended and provided with a stiffening flange at its edge to withstand the load of the spring as shown in Fig. 6.

In both embodiments the spring abutment serves only to restrain the spring during transit and assembly. Once installed the abutment cannot contact the spring in anyway but remains to limit coning of the spring should the cover assembly be removed.

Claims

1. A diaphragm spring clutch cover assembly comprising an annular cover member, a pressure plate fast for rotation with the cover member and a diaphragm spring mounted at the inner peripheral edge of the cover member by clamping means including fulcrums for the spring wherein the clamping means further include abutment means to limit free coning of the spring.

2. A clutch cover assembly according to Claim 1 wherein said clamping means comprise tabs passing through inwardly extending fingers of the diaphragm spring and turned towards the outer periphery of the assembly to sandwich circular fulcrum rings on either side of the diaphragm spring against the cover member, the tabs extending outwardly from the fulcrum rings to provide abut ment means for the spring.

3. A clutch cover assembly according to Claim 1 wherein said clamping means comprise tabs passing through inwardly extending fingers of the diaphragm spring and turned towards the outer periphery of the assembly to retain a support ring, the spring being sandwiched by circular fulcrums provided in the support ring and cover member, the support ring extending outwardly from the circular fulcrums and whose edge portion forms said abutment means.

4. A clutch cover assembly according to Claim 3 wherein said edge portion of the support ring has a peripheral flange turned away from the diaphragm spring.

5. A clutch cover assembly substantially as described herein with reference to Fig. 4 or to Fig.

6.