GB2269641A

GB2269641A - Clutch disc assembly with lining springs

Info

Publication number: GB2269641A
Application number: GB9316753A
Authority: GB
Inventors: Harald Jeppe; Klaus Memmel; Norbert Ament; Harald Raab
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1992-08-13
Filing date: 1993-08-12
Publication date: 1994-02-16
Anticipated expiration: 2013-08-12
Also published as: GB9316753D0; BR9303368A; FR2694795A1; FR2694795B1; DE4226762C2; GB2269641B; DE4226762A1

Abstract

A clutch disc assembly for a motor vehicle comprises a hub (2) and a disc section (3), which are coaxially arranged and connected to the disc section (3) there are fraction lining springs (6) and a pair of oppositely directed friction lining rings (5). The lining springs (6) are connected circumferentially to the disc section (3) and have a resilience which increases over the radial extension of the friction lining rings (5). The springs may be separate from each other or have common foot areas. <IMAGE>

Description

2269641 CLUTCH DISC ASSEMBLY WITH LINING SPRING The invention relates to a

clutch disc assembly to be positioned in a motor-vehicle friction clutch, comprising a hub to be connected to a transmission shaft; a disc section arranged concentrically with the hub and displaying in the area of its outer circumference at least one axially sprung lining spring; and two frictionlining rings, fastened back to back to the lining spring, the latter being interposed between them, so that the lining spring displays, in the radial direction, a flat area for contacting the friction-lining rings and at least one arched or angled area which adjoins the flat area and essentially corresponds with the radially outer or radially inner area of the friction-lining rings.

Clutch disc assemblies of the above type are known, eg from US-A-2309950. In this friction disc, 11ning springs are built together in pairs and both display both a flat area for contacting the frictionlining rings and an arched or angled area with one of the lining springs being arched radially outwards and the other being arched radially inwards- A clutch disc is also known from DE-OS 2920 095 in which, likewise, lining springs are built together in pairs and display an arched aea both radially outwards and radially inwards.

In both cases, the arched areas induce axial 2 resilience between the two friction-lining rings. This axial resilience contributes substantially to drive comfort and to uniform frictional contact of the friction-lining rings.

The task of the present invention is to create a lining spring arrangement for friction-lining rings that displays greater spring stiffness in the radially outer area than in the radially inner area, and by means of which the smallest possible mass moment of inertia can be achieved.

In accordance with the invention, there is provided a clutch disc assembly for a motor-vehicle friction clutch, comprising:

hub concentric with an axis of rotation to be mounted on a transmission shaft, disc section concentric with and connected to the hub; an axially sprung lining-spring arrangement connected to an outer circumference of the disc section; and two friction-lining rings, fastened back to back and on either side of the lining-spring arrangement; wherein the lining-spring arrangement comprises several circumferentially distributed arched lining springs each of which defines a f lat contact area radially outwards from a foot are-a adjacent the disc si-c:tion for contact with and securing to one of the two friction-lining rings and a support area bent out towards 3 the other of the two friction-lining rings;and wherein the support area of each lining spring is arranged radially exterior the flat contact area, extends between the lining rings at an angle to the axis of rotation and has an substantially radially projecting end area which lies against the other friction-lining ring.

Because of the form of the invention it is possible to avoid the construction of double-sided lining springs, thus markedly reducing the inertial mass. Secondly, the form of the lining spring used is such that the radially outer connecting area has a substantially greater spring excursion available than does the radially inner one, so that spring stiffness increases with diameter. This feature ensures during the startup, the mean effective frictional radius is shifted into the radially outer area of the frictional- lining rings, so that the effectively transmissible torque becomes a maximum for a particular category of clutch disc diameter. As a result, a coupling using such a clutch disc has a reduced tendency to slip and consequently the lining wears less during coupling.

The lining spring, when not under load, may have its foot area positioned midway between the frictionlining rings and is connected to the flat area via slanted or inclined connecting areas. In this way, a "uiliform distribution of spring force for the curvatures of the lining spring is achieved in both directions, 4 even in the radially inner area.

A single ring can be provided to connect the lining in which the separation of the individual alternatina curvatures occurs via essentially radially running slits, which run radially inward as far as the foot area. The use of a single surrounding lining spring ring enables assembly to be carried out simply.

In a further embodiment the springs may be provided in circumferentially distributed individual spring pairs. Each spring pair is circumferentially divided in two by a radially running slit, the slit running radially inwards as far as the foot area, and the parts extending circumferentially outwards from the slit being arched in opposite directions. Such lining springs can be manufactured with very little stamping waste and can be assembled in exactly the same way as other individual lining springs.

It can also be advantageous, however, and without difficulty, to use a single circumferentially distributed lining spring or axially acting cantilever springs that are arched alternately in one or the other axial direction. In this latter type of lining spring -axrangement, the greatest circumferential separation between individual lining springs is achieved, so that this construction provides a large degree of ifitensitivity to warping at peak temperatures.

It is advantageous for each friction-lining ring to be fastened by a lining rivet, approximately in the middle of.-its radial extension, to a corresponding arch in the f lat area of the lining spring. In this way, verv few rivets are required in order to implement a low mass moment of inertia yet fasten the components together with sufficient strength.

The invention will now be described in more detail with the aid of a specific embodiment shown in -L,--he accompanying drawing wherein:

Figure 1 shows the upper half of a longitudinal section through a clutch disc assembly constructed in accordance with the invention as seen along a line I-I in Fig. 2; and Figure 2 shows the front view of a lining spring appropriate to Figure 1.

The clutch disc assembly 1 in Figure 1 shows the principle of construction, with a hub 2 which is for mounting with torsional stiffness on a transmission shaft, not shown. A disc sect-ion 3 is fastened with rivets 9 to the hub 2 and carries lining springs 6 on its external diameter. A torsional vibration damper can be arranged in the area of the disc section 3.

In the illustration, several lining springs 6 are arranged on the circumference of the disc section 3 with fastening rivets 8, their top view being shown in Figure 2... The lining springs 6 are made in pairs as individual parts and, circumferentially distributed, are fastened to 6 the disc section 3. Viewed circumferentially, each pair of these -lining springs 6 displays two areas that are separated from each other by a radially running slit 15.

This slit 15 extends radially inwards as far as a common foot area 13. Each Dart of the lining spring adjoining the slit 15 is arched as shown in Figure 1, one area is arched towards one friction-linina rina 5 and the other area is arched towards the other ring 5 and which serves as an extensive contact area for the corresponding friction-lining ring 5. At the same time a fastening to the friction-lining rings 5, in the form of a lining rivet 7, is provided in each case at a mean radius within the flat area 10. Between the flat areas 10 of the lining springs 6 and a foot area 13 adjacent the disc section 3, inner connecting areas 14 are provided for which extend at an angle to a radial plane through the axis of rotation 4. Shaping the two areas of each lining spring 6 in the same way results in a symmetrical arrangement being achieved between the flat areas 10 and the foot area 13. By this means, when not under load, the foot area 13 is the same distance away from both friction-lining rings 5. Radially beyond the flat area 10, inclined connecting areas 11 are again arranged that run from the inner wall, ie. the back, of one of the friction-lining rings 5 as far as the inner wall of the oiter friction-lining ring 5 and are supported on the side opposite to the f lat area 10 with an end area 12 7 adjoining the connecting area 11. The end area 12 also lies against an extensive area of the friction lining ring 5.

Arranging the lining springs in accordance with Figures 1 and 2 ensures that the spring stiffness of all the lining springs increases in an axial direction from radially inside to radially outside over the radial extent of the fric-1Cion-lining rings 5. This influence by the formation of the connecting areas 14, in that their radial extension, i.e. the size of their axial projection, can be altered. Furthermore, this formation of the lining springs 6 achieves a reduction in the inertia of the clutch disc since in each case, viewed circumferentially, the lining spring portions do not overlap.

By modifying the lining springs shown in Figures 1 and 2, however, it is also possible to connect the lining springs, into a single spring ring. Such as spring ring is self-contained in its foot area and is divided radially outwards by a number of slits into individual spring areas, each of which nestles circumferentially and alternately against one or the other friction-lining ring 5.

In a further variant as shown in principle in Figures 1 and 2, individual lining springs 6 are provided oh>the circumference but separated from each other, each lining spring 6 being arched in only one or the other 8 direction.

It.. can be ensured by the possible implementations described above that, f or example, during start-up the mean effective radius is established in the radially outer area of the friction-lining rings 6, so that the effectively transmissible torque is particularly high. Torque transmission capability can thus be markedly increased during the start- up and the coupling has less tendency to slip, which also has a positive influence on lining wear. At the same time it is ensured that a clutch disc fitted with these linings springs displays a very low mass moment of inertia, which increases the ease of engaging and disengaging the subordinate gear train as well as extending the latter's useful life.

---. Z 9

Claims

1 A clutch disc assembly for a motor-vehicle friction clutch, comprising:

hub concentric with an axis of rotation to be mounted on a transmission shaft, disc section concentric with and connected to the hub; an axially sprung lining-spring arrangement connected to an outer circumference of the disc section; and two friction-lining rings, fastened back to back and on either side of the lining-spring arrangement; wherein the lining-spring arrangement comprises several circumferentially distributed arched lining springs each of which defines a flat contact area radially outwards from a foot area adjacent the disc section for contact with and securing to one of the two friction-lining rings and a support area bent out towards the other of the two friction-lining rings; and wherein the support area of each lining spring is arranged radially exterior the flat contact area, extends between the lining rings at an angle to the axis of rotation and has an substantially radially projecting end area which lies against the other friction-lining ring.

2. A clutch disc assembly according to claim 1,,7hrein the flat contact area of each lining spring is connected to the foot area through a further radially inner connecting area extending at an angle to the axis of rotati-on and the radially outer connecting area is longer in the axial direction than is the radially inner connecting area.

3. A clutch disc assembly according to claim 2. wherein the radiallv inner connecting area of each of the springs is so formed that, when the lining spring is not under load, the foot area runs at least approximately midway between the friction-lining rings.

4. A clutch disc assembly accordina to anv one of claims 1 to 3, wherein the lining springs are separate from each other.

5. A clutch disc assembly according to any one of claims 1 to 3, wherein a number of circumferentiallv adjacent lining springs have common foot areas adjacent the disc section that are joined together in one piece and are separated from each other by at least one slit which runs radially inwards as far as the foot area.

6. A clutch disc assembly according to claim 5, wherein each pair of facing lining springs are joined together in one piece by their foot areas.

7. A clutch disc. as in claim 5, wherein the foot areas of all lining springs are joined in one piece into a ring.

8. A clutch disc assembly according to any one of c'l'aims 1 to 7 wherein the f lat contact area of each lining spring is joined to the foot area via a further 11 radially inner connecting area extending at an angle to the axis of rotation and that the radially outer connecting area is so dimensioned that it has greater resilience than the radially inner connecting area.

9. A clutch disc assembly according to any one of claims 1 to 8 wherein each frictionlining ring is fastened ar)r)roxi-;matelv in the middle of its radial extension, by means of one lining rivet in each case, to the flat contact area of the linina sDrinas axiallv adjacent thereto.

10. A clutch disc assembly substantially as described herein with reference to anv one or both of the figures of the accompanying drawings.

-.-.. Z