GB2230572A

GB2230572A - Clutch cover assemblies

Info

Publication number: GB2230572A
Application number: GB8828938A
Authority: GB
Inventors: Tadamasa Kobayashi; Chiaki Saida
Original assignee: Aisin Seiki Co Ltd
Current assignee: Aisin Corp
Priority date: 1987-12-18
Filing date: 1988-12-12
Publication date: 1990-10-24
Anticipated expiration: 2008-12-12
Also published as: GB8828938D0; JPH01164821A; JP2705075B2; GB2230572B

Abstract

A clutch cover assembly has a damper or cushion ring 1 disposed between a pressure plate 2 and a diaphragm spring 4. This makes it possible to hold a pre-settled load between the pressure plate 2 and the diaphragm spring 4 in disengaging, and to have a wide stroke range. The cushion ring 1 may be a ring-shaped tube with a slot on the inner side of the ring or a waved strip in a ring-shape. The tube may have a radial cut away part. <IMAGE>

Description

TITLE: Clutch cover assemblies DESCRIPTION: The invention is concerned with clutch cover assemblies suitable for vehicle transmissions, and particularly with a damper for ensuring smooth clutch engagement, together with clutch mechanisms comprising such assemblies.

The invention provides a clutch cover assembly comprising a clutch cover, a pressure plate inside the clutch cover, a diaphragm spring between the clutch cover and the pressure plate, and a damper between the pressure plate and the diaphragm spring.

The damper is preferably a ring-shaped tube with a slot on the inner side of the ring or a waved strip in a ring-shape. The tube may have a radial cut away part, and the pressure plate may have a groove of semi-circular or square cross-section for receiving the damper.

This makes it possible for the clutch to have a wide stroke range in the half-clutch operating, and for frictional material to be fixed directly to the pressure plate for contacting a clutch disc.

DRAWINGS: Figure 1 is a front view of a clutch cover assembly according to the invention; Figure 2 is a section on II-II in Figure 1; Figure 3 shows a detail from the assembly at III in Figure 2; Figure LI is a front view of a damper in the assembly of Figures 1 and 2; Figure 5 is a section on V-V in Figure 4; Figure 6 is a detailed section on VI-VI in Figure 4; Figure 7 is a front view of an alternative form of damper in the assembly of Figures 1 and 2; Figure 8 is a side view at VIII in Figure 7; Figure 9 is a front view of a further alternative form of damper in the assembly of Figures 1 and 2; Figure 10 shows side views of alternative damper rings at X in Figure 9; Figure 11 is a front view of an alternative pressure plate in the assembly of Figures 1 and 2; Figure 12 is a section on XII-XII in Figure 11;; Figure 13 is a section of an alternative pressure plate on XII-XII in Figure 1; and Figure 14 shows a cushioning characteristic of clutch assemblies according to the invention in comparison to a conventional clutch.

In Figure 1, a clutch cover 3 has a shell shape and a flange 3a (Figure 2) contacting an outer side face 9a of a flywheel 9 (shown by a two-dot chain line), and is fixed to the flywheel 9 by bolts 10. The clutch cover 3 leaves a space 11 between a flat wall 3c, a side wall 3b and the flywheel 9. The flywheel 9 connects to a crankshaft of an engine (not shown). A diaphragm spring has a number of fingers 4a projecting inward, and is supported by rolled over portions 3d extending through recesses 4b in the spring LI, by projections 3e of the cover 3, and by a pivot ring 5. Recesses 3f are formed by pressing to give projections 3e on the underside of the cover 3. The diaphragm spring'4 turns at a supported point when the top of the fingers 4a receives pressure.

A pressure plate 2 is disposed between the diaphragm spring LI and the flywheel 9, and has three projections 2a on the outer side in the radial direction, and is connected to the clutch cover 3 through straps 7 by rivets 6. The pressure plate 2 rotates integrally with the cover 3 and slides axially in relation thereto. A clutch disc (not shown) is disposed between the pressure plate 2 and the flywheel 9, and connected to an input shaft of a transmission. On a disc plate of the clutch disc, frictional materials are directly fixed.

Between the outer part 4c of the diaphragm spring LI and a circular projection 2b on the pressure plate 2 a damper is disposed. The damper is constructed with a cushion ring 1 as shown in Figures 4 and 5. The cushion ring 1 comprises an annular tube with a circular slot 1a in an inner side of the ring. The cushion ring 1 as shown in Figure 4 has an optional radial cutaway part 12. The circular slot 1a makes the cushion ring 12 function as a spring, as the slot la has a width t greater than a gap 6 in Figure 3 between the pressure plate 2 and the diaphragm spring 4. That is, the gap 6 or extent of flexibility is determined by the width t or damping range of the cushion ring 1.

In Figures 7 and 8 the damper is a wave strip 13 in a ring shape which is welded at a point 15. There are twelve waves 13a. The spring load is 30 kg, and can be changed according to the number of waves.

In Figures 9 and 10 the damper comprises rings 14 having waves 16,16',16". The spring load can be changed and settled by varying the number of waves. In Figure 10 the alternatives (a), (b) and (c) have four, six and eight waves respectively.

In Figures 11, 12 and 13, the pressure plate 2 has a higher outer axial part on the projection 2b. On the top of the projection 2b, a groove 2c is formed for accepting the damper. A semi-circular groove 2c in Figure 12 is used for the cushion ring 1 or the wave ring 14, while a square-section groove 2'c in Figure 13 receives the wave strip 13.One side of the ring 1 contacts to the groove 2c while the opposite side contacts an outer part 4c of the diaphragm spring 4. In disengaging, the ring 1 is forced by the spring load of the straps 7 through the pressure plate 2 against the diaphragm spring 4. In engaging, the ring 1 is forced by the load of the diaphragm spring 4 against the pressure plate 2, so the ring 1 is held between the pressure plate 2 and the diaphragm spring 4.

On a radially outer side of the groove 2c, an axial projection 2d is formed (Figures 2,3). In disengaging, between a contact point 4d of the diaphragm spring 4 and the axial projection 2d, the gap 6 is about 1 mm. In engaging, the gap 6 operates as cushioning flexure: when the ring 1 flexes by 6, the contact point Lid contacts the axial projection 2d, and the spring load of the diaphragm spring 4 forces the pressure plate 2 directly.

The axial projection 2d can be formed on the radially inner side of the groove 2c instead of the radially outer side.

In Figures 2 and 3, when a foot is set on the clutch pedal, a release bearing (not shown) slides in the direction of an arrow D, and moves the top of the fingers 4a of the diaphragm spring LI. The diaphragm spring 4 operates as a release lever, and the outer part 4c rotates anti-clockwise around the pivot ring 5.

Consequently, the pressure of the diaphragm spring 4 on the pressure plate 2 is removed, and the spring load of the straps 7 forces the pressure plate 2 in the direction of an arrow E. A frictional face 2e is removed from the clutch disc (not shown), and the clutch is disengaged.

The contacting faces of the axial projection 2d and the contact point 4d are separated from each other by the rotation of the outer part 4c, and the gap between the contacting faces is held at 6 by the ring 1 in disengaging. When engaging, the release bearing slides in the direction of arrow E, the diaphragm spring Li is removed from pressure, the outer part lic rotates clockwise around the projections 3e owing to its flexibility and forces the pressure plate 2 through the ring 1 with a pressure proportionate to the flexure.

Consequently the pressure plate 2 is forced in the direction of arrow D. On the frictional face 2e of the pressure plate 2, torque accurs owing to the pressure, and the clutch engages. The ring 1 shrinks in proportion to the rotation of the outer part 4c, and when the ring 1 flexes by 6, this projection 2d contacts the point 4c. After this, the pressure is transmitted to the plate 2 through the contacting faces.

In Figure 14, a two-dot chain line shows the cushioning characteristic of a conventional clutch which comprises a clutch disc having wave springs. A full line shows the cushioning characteristic of an assembly according to the invention which comprises with a clutch cover having a tube 1. A dot line shows the cushioning characteristic of an assembly according to the invention which comprises a wave strip 13. The characteristic of the conventional clutch changes as a curve of second degree, and it is difficult to control the stroke minutely. The cushioning characteristics of the invention change slowly over wide range, and show the slow cushioning. Consequently the stroke range of half clutch operation is wide, the clutch engages smoothly, and clutch engagement is easy. The cushioning amount is controlled easily by the gap between the pressure plate 2 and the diaphragm spring 4. The cushioning characteristic is easily maintained, and the stability of the clutch is good. The cushioning characteristic can easily be changed by changing the material or shape of the damper.

Claims

CLAIMS:

1. A clutch cover assembly comprising a clutch cover, a pressure plate inside the clutch cover, a diaphragm spring between the clutch cover and the pressure plate, and a damper between the pressure plate and the diaphragm spring.

2. An assembly according to claim 1 in which the damper comprises a ring-shaped tube with a slot on the inner side of the ring.

3. An assembly according to claim 2 in which the tube has a radial cutaway part.

LI. An assembly according to claim 1 in which the damper comprises a waved strip in a ring-shape.

5. An assembly according to any preceding claim in which the pressure plate has a groove of semi-circular or square cross-section for receiving the damper.

6. A clutch cover assembly substantially as herein described with reference to Figures 1 to 6 of the drawings.

7. A clutch cover assembly according to claim 7 as modified by Figures 7 and 8, or 9 and 10 of the drawings.

8. A clutch cover assembly according to claim 6 or claim 7 as modified by Figure 11 of the drawings.

9. A clutch cover assembly according to any of claims 6 to 8 as modified by Figure 12 or 13 of the drawings.

10. A clutch mechanism comprising a clutch cover assembly according to any preceding claim.