GB2189558A

GB2189558A - Friction clutch

Info

Publication number: GB2189558A
Application number: GB08610260A
Authority: GB
Inventors: Ian Commander Maycock; Anthony John Curtis
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1986-04-26
Filing date: 1986-04-26
Publication date: 1987-10-28
Also published as: GB8610260D0

Abstract

A pressure plate assembly for a friction clutch includes a cover member (10) having a generally cylindrical wall portion (11) and an inwardly directed flange portion (13), the flange portion (13) having an inner peripheral continuous reinforcing rim (26) extending axially of the cover member (10). A Belleville spring (15) is supported coaxially of the cover member (10) between a pair of fulcrum rings (19, 20), said fulcrum rings (19, 20) being mounted against the flange portion (13) by means of a series of tabs (21), the tabs (21) being supported from a continuous annular portion of the flange portion (13), said annular portion being contiguous with the cylindrical wall portion (11). Figs. (3-9) depict modifications of the tabs, the rings and the reinforcing rim. <IMAGE>

Description

SPECIFICATION Friction clutches The invention relates to diaphragm spring friction clutches.

A conventional diaphragm spring clutch design comprises: a cover member, a pressure plate mounted with respect to the cover member and a diaphragm spring interposed between the cover member and the pressure plate. In use, the clutch is mounted on a flywheel and a driVen plate is interposed between the flywheel and the pressure plate.

The diaphragm spring urges the pressure plate into frictional engagement with the driven plate and the driven plate into friction engagement with the flywheel. The diaphragm spring typically incorporates an outer annular plate spring or belville portion which engages the pressure plate with fingers projecting inwardly from the belville portion. The inner edges of the fingers are deflected by means of pressure applied in the direction of the flywheel to deform the belville portion and thus release the clutch. In; order to achieve this, the diaphragm spring is pivotted between a pair of fulcrum rings positioned, one on either side of the spring, adjacent the roots of the fingers, that is inside the ring of contact between the diaphragm spring and the pressure plate.It has been proposed to mount the fulcrum rings in position relative to the cover member, by means of tabs formed by or supported on the cover member, which pass through apertures between the fingers of the diaphragm spring, to engage and locate the fulcrum rings.

These cover members, particularly where the tabs are formed by the cover member itself, have however exhibited a lack of axial stiffness which adversely effects the operation and feel of the clutch.

According to one aspect of the present invention, a pressure plate assembly for a friction clutch comprises; a cover member having a generally cylindrical wall portion and an inwardly directed flange portion, a pressure plate drivingly mounted co-axially relative to the cover member and a diaphragm spring mounted. between the flange portion of the cover member and the pressure plate, said diaphragm spring having an outer belville portion which engages the pressure plate and resilient fingers projecting inwardly from the belville portion, said diaphragm spring being pivotted between a pair of fulcrum rings positioned one on either side of the spring adjacent the roots of the fingers, the fulcrum rings being mounted in position relative to the cover member by means of tabs which extend axially between the fingers of the diaphragm spring from the flange portion of the cover member, said tabs being supported by a continuous annular portion of the flange portion, said annular portion being contiguous with the cylindrical wall portion, and an axially extendingly annular reinforcing rim being provided at or adjacent the inner periphery of the flange portion.

Preferably the tabs are formed by the flange portion of the cover member, portions of the flange portion being cut and bent back towards the wall portion, along fold lines substantially parallel to the wall portion. Alternatively, the tabs may be formed by a separate tab ring.

Various embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a partial plan view of a pressure plate assembly formed in accordance with the present invention; Figure 2 is a section along the line ll-ll of Figure 1; Figure 3 is a section similar to that shown in Figure 2, of an alternative embodiment of the invention; Figure 4 is a partial plan view of a further embodiment of the invention; Figure 5 is a-section along the line V-V in Figure 4; and Figures 6 to 9 are sections similar to that shown in Figure 2, of modifications to the embodiment illustrated in Figures 4 and 5.

As illustrated in Figures 1 and 2, a pressure plate assembly comprises a cover member 10 defined by a generally cylindrical wall portion 11 having an outwardly directed flange 12 at one end, by means of which the pressure plate assembly may be secured to a flywheel (not shown). An inwardly directed flange 13 is provided at the other end of wall portion 11.

A pressure plate 14 is mounted co-axially with the cover member 10 by means of three drive straps (not shown). The drive straps are flexible so that they permit a limited amount of axial movement of the pressure plate 14 relative to the cover member 10, while locating the pressure plate 14 co-axially with respect to the cover member 10 and providing a circumferential drive connection.

A diaphragm spring 15 having an outer belville portion 16 and inwardly directed fingers 17 is located between the flange 13 of cover member 10 and an annular projection 18 on the pressure plate 14. The spring 15 is located between a pair of fulcrum rings 19 and 20 which are located on either side of the spring 15 at the junction between the belville portion 16 and the fingers 17.

The fulcrum rings 19 and 20 are located in position by means of a series of circumferentially spaced tabs 21 which extend between the fingers 17 of the spring 15. The tabs 21 are formed in the flange 13 intermediate of its inner periphery and wall 11, by cutting along the radial edges 22 and 23 and inner circumferential edge 24 to form a generally rectangular tab 21 as shown in broken line in Figure 1.

The tab 21 is then bent back towards the cylindrical wall 11, so that it is substantially axial therewith and the end 25 of tab 21 is then bent over to engage fulcrum ring 20 and urge fulcrum ring 19 into engagement with the flange 13. An axially extending annular rim 26 is provided at the inner periphery of the flange 13, to axially reinforce the flange 13.

The diaphragm spring 15 is thereby arranged to act between the fulcrum ring 19 adjacent flange 13 and annular projection 18 on pressure plate 14, to urge the pressure plate 14 axially away from the cover member 10. Thus, when the cover member 10 is mounted upon a flywheel (not shown) with a driven plate (not shown) interposed between the flywheel and the pressure plate 14, the driven plate will be clamped between the flywheel and the pressure plate 14 under the load applied to the pressure plate 14 by diaphragm spring 15, so that the clutch will be in the engaged condition. Release of the clutch may be achieved by applying a pressure to the inner ends of fingers 17 of the diaphragm spring 15, in the direction of the pressure plate 14.This will cause the spring 17 to pivot against the fulcrum ring 20 and the belville portion 16 will move away from the pressure plate 14, thereby reducing the clamping pressure on the driven plate. Pressure may be applied to the fingers 17 of the spring 15, by a release bearing of conventional design.

In the modification illustrated in Figure 3, the tabs 31 are formed separately of the flange 13 of cover member 10. These tabs 31 are formed by a tab ring 32 having a continuous annular portion 33 and a series of axially extending castellations 34 which extend between the fingers 17 of the diaphragm spring 15 and are bent over to locate the fulcrum rings 19 and 20. The free end of the annular portion 33 is formed with an outwardly directed flange 35 which engages over an axially extending rim 26a at the inner periphery of the flange 13 of cover member 10, so that the fulcrum rings 19 and 20 will be clamped against the flange 13.

In the embodiment illustrated in Figures 4 and 5, tabs 41 are formed at the inner periphery of flange 13 of cover member 10. The inner periphery of the flange 13 is foided over around a circumference radially outside the roots of tabs 41, so as to form a continuous axially extending rim 42 from which the tabs 41 extend axially. The ends of the tabs 41 may then be folded over to clamp the fulcrum rings 19 and 20 against the flange 13 as described above.

In order to increase the axial stiffening effect of the rim portion 42, the depth of the rim 42 may be increased and a spacer ring 43 included between the fulcrum ring 19 and flange 13 of cover member 10, as illustrated in Figure 6, or an oval fulcrum ring 45 may be used as illustrated in Figure 7. Further stiffening of the flange 13 of cover member 10 may be achieved by providing circumferentially spaced radially extending ribs 46 in the spaces between the tabs 41, as illustrated in Figure 8.

In the embodiment illustrated in Figure 9, an axially extending reinforcing rim 50 is formed by folding the flange 13 back upon itself to form an axially extending rib. This rim 50 may replace or reinforce the rim 41 of the embodiments illustrated in Figures 4 to 8.

Claims

1. A pressure plate assembly for a friction clutch comprising a cover member having a generally cylindrical wall portion and an inwardly directed flange portion, a pressure plate drivingly mounted co-axially relative to the cover member and a diaphragm spring mounted between the flange portion of the cover member and the pressure plate, said diaphragm spring having an outer belville portion which engages the pressure plate and resilient fingers projecting inwardly from the belville portion, said diaphragm spring being pivotted between a pair of fulcrum rings positioned one on either side of the spring adjacent the roots of the fingers, the fulcrum rings being mounted in position relative to the cover member by means of tabs which extend axially between the fingers of the diaphragm spring from the flange portion of the cover member, said tabs being supported by a continuous annular portion of the flange portion, said annular portion being contiguous with the cylindrical wall portion, and an axially extendingly annular reinforcing rim being provided at or adjacent the inner periphery of the flange portion.

2. A pressure plate assembly according to Claim 1 in which the tabs are formed by the flange portion of the cover member.

3. A pressure plate assembly according to Claim 2 in which the tabs are formed in the flange portion, intermediate of its inner periphery and the wall portions, the tabs being connected to the flange portion along the side adjacent the wall portion, a reinforcing rim being provided at the inner periphery of the flange portion.

4. A pressure plate assembly according to Claim 2 in which the tabs are formed at the inner periphery of the flange portion, the inner periphery of the flange portion being folded over to form an axially extending rim from which the tabs extend axially.

5. A pressure plate assembly according to Claim 4 in which the depth of the rim is equal to the cross-sectional diameter of the fulcrum ring.

6. A pressure plate assembly according to Claim 4 in which the depth of the rim is greater than the cross-sectional diameter of the fulcrum ring.

7. A pressure plate assembly according to Claim 6 in which a spacer ring is positioned between the fulcrum ring and the flange portion of the cover member.

8. A friction plate assembly according to Claim 6 in which the fulcrum ring is of oval section, the depth of the rim being equal to the length of a major axis of the fulcrum ring.

9. A pressure plate assembly according to any one of the preceding claims in which the axially extending reinforcing rim is disposed radially outwardly of the tabs.

10. A pressure plate assembly according to Claim 9 in which the axially extending reinforcing rim is formed by deforming the flange portion to form an axially extending rib.

11. A pressure plate assembly according to Claim 1 in which the tabs are formed separately of the cover member.

12. A pressure plate assembly according to Claim 11 in which the tabs are formed by a tab ring having a continuous annular portion and a series of axially extending castellations which extend between the fingers of the diaphragm spring, the end of the annular portion remote from the castellations having an outwardly directed flange portion which engages over an axially extending reinforcing rim at the inner periphery of the flange portion of the cover member.

13. A pressure plate assembly as claimed in any one of the preceding claims in which circumferentially spaced radially extending ribs are provided in the flange portion in the spaces between the tabs.

14. A pressure plate assembly substantially as described herein with reference to and as shown in Figures 1 and 2, 3, 4 and 5, 6, 7, 8 or 9 of the accompanying drawings.

15. A friction clutch assembly comprising a pressure plate assembly as claimed in any one of Claims 1 to 14.

CLAIMS New claims or amendments to claims fiied on 9:3:87.

Superseded claims 1, 2, 8-12.

New or amended claims:

1. A pressure plate assembly for a friction clutch comprising a cover member having a generally cylindrical wall portion and an inwardly directed flange portion, a pressure plate drivingly mounted co-axially relative to the cover member and a diaphragm spring mounted between the flange portion of the cover member and the pressure plate, said diaphragm spring having an outer Belleville portion which engages the pressure plate and resilient fingers projecting inwardly from the Belleville portion, said diaphragm spring being pivotted between a pair of fulcrum rings positioned one on either side of the spring adjacent the roots of the fingers, the fulcrum rings being mounted in position relative to the cover member by means of tabs which extend axially between the fingers of the diaphragm spring from the flange portion of the cover member, said tabs being supported by a continuous annular portion of the flange portion, said annular portion being contiguous with the cylindrical wall portion, and an axially extendingly annular reinforcing rim being provided at or adjacent the inner periphery of the flange portion.

8. A pressure plate assembly according to Claim 6 in which the fulcrum ring is of oval section, the depth of the rim being equal to the length of a major axis of the fulcrum ring.