GB2152634A

GB2152634A - Torsional vibration damper with a spring for both friction devices

Info

Publication number: GB2152634A
Application number: GB08500132A
Authority: GB
Inventors: Harald Raab
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1984-01-04
Filing date: 1985-01-04
Publication date: 1985-08-07
Also published as: FR2557657A1; GB2152634B; DE3400183A1; GB8500132D0; DE3400183C2; FR2557657B1

Abstract

In a torsional vibration damper in a clutch disc, which damper comprises an idling and an under- load friction device, both friction devices are arranged, radially one above the other, on one side of the hub disc 2 and they are loaded in the axial direction by one single spring element 22, the basic body of which is formed as a dished spring and acting upon the under- load friction device. Several spring tabs 23 protrude out beyond the inner radial contour of this basic body, and form an obtuse angle with the basic body. The spring element also loads the idling friction device. This one-piece spring is easier to fit and can be produced with better value for price. <IMAGE>

Description

SPECIFICATION Torsional vibration damper with a spring for both friction devices The invention relates to a torsional vibration damper, especially for motor vehicle clutches, with a spring device for generating friction force, in which a mutual rotation is possible between a hub disc of a hub and cover plates arranged to both sides of the hub disc, against the force of torsion springs, and two different friction devices are provided, namely an idling friction device and an under-load friction device, the friction force generation of which takes place on the same side between hub disc and cover plate in two zones arranged radially one above the other.

A torsional vibration damper of the abovestated construction type was proposed by way of example in British Patent Application No.

84.19,704. In this torsional vibration damper both the idling friction device and also-with radial spacing-the under-load friction device are arranged on the one side of the hub disc.

This arrangement necessitates its own spring for each friction system.

It is the problem of the present invention, in a torsional vibration damper according to the prior art with two different friction devices, to produce an embodiment which is best possible value for price.

This problem is solved in accordance with the invention by the characteristic of the Main Claim.

By arrangement of one single spring, the basic body of which is formed as a dished spring and which comprises issuing from this basic body-spring tabs which form an obtuse angle with the basic body and thus point away from it, it is possible to make one single spring element acting upon two different friction devices suffice. Moreover the fitting of the torsional vibration damper is significantly simplified by this one spring.

According to the Sub-Claims it is advantageous to have the spring tabs reach out preferably radially beyond the radially inner contour of the basic body, in order thus to actuate the radially inwardly arranged idling friction device. In this case the basic body is supported with its internal circumference on the cover plate and with its external circumference on the under-load friction device. Furthermore on the side opposite to the spring an under-load friction disc is part of the underload vibration damper, while tabs of the under-load friction disc penetrate axially through the hub disc, and on their free ends a counterthrust ring is arranged fast in rotation. which comprises a friction ring between itself and a thrust ring which is connected fast in rotation with the cover plate and is loaded by the spring.In this case the spring is guided radially for the generation of the friction forces on the thrust ring, which comprises axially bent-off tabs for rotation-fast connection with the cover plate. According to a further Sub Claim it can be advantageous to form the counter-thrust ring as second under-load friction disc. Thus a more uniform loading is achieved within the two under-load friction discs.

The invention will be explained in greater detail below by reference to an example of embodiment. Individually: Figure 1 shows the upper half of a longitudinal section through a clutch disc on the scale of about 2:1; Figure 2 shows the perspective partial view of the under-load friction disc; Figure 3 shows the view of the spring approximately on the scale 1 :1.

Fig. 1 shows the longitudinal section through the upper half of a clutch disc with a torsional vibration damper. It consists of a hub 1 which is arranged fast in rotation but axially displaceably on a gear shaft (not shown). A hub disc 2 is made integral with the hub 1. To both sides of the hub disc 2 there are arranged cover plates 3 and 4, with the one cover plate carrying the friction linings 5. In corresponding windows 7 of the cover plates 3 and 4 and in windows 6 of the hub disc 2 there are arranged torsion springs 8 which, on torque loading of the torsional vibration damper render possible a relative rotation between the cover plates 3 and 4 and the hub 1, against their spring force. In this relative rotation two differently designed friction devices come into effect in succession.In the case of slight angular deflections from the neutral position firstly the idling friction device is effective. In the following description the basis is always to be adopted that the two cover plates 3 and 4 are fixed circumferentially and in the axial direction by means of distance pieces. The idling friction device is composed of the two friction rings 20 and 21 to both sides of the hub disc 2, the pressure plate 16, which comprises axially angled-off tabs 1 7 which are circumferentially guided in corresponding openings of the cover plate 3 but axially displaceably mounted. and the spring tabs 23 of the spring 22 which exert an axial force upon the pressure plate 1 6 and the friction ring 21.The reaction force of this axial force is transmitted by way of the cover plate 3, the connecting elements between cover plate 3 and cover plate 4 to the latter and thence by way of the friction ring 1 8 and the under-load friction disc 9 to the friction ring 20 again. Thus in idling operation the following components are entrained fast in rotation in relation to the hub 1 and the hub disc 2 by the under-load friction device, to be described in greater detail below, with its higher friction force:-the cover plates 3 and 4, the friction ring 18, the under-load friction disc 9, the counter-pressure ring 1 3, the friction ring 19, the thrust ring 14 and the spring 22.Thus the idling friction occurs between the hub disc 2 and the two friction ring 20 and 21 and between the pressure plate 16 and the under-load friction disc 9.

On exceeding of a pre-determined angular deflection the under-load friction disc 9 and counter-pressure ring 1 3 are made fast in relation to the hub disc 2 by stops, so that now on further rotation the under-load friction device comes into action. To the latter there pertains the spring 22 with its basic body 24 shown in elevation in Fig. 3, which is supported with its external circumference 25 on the thrust ring 14 and with its internal circumference 26 on the cover plate 3. The thrust ring 14 is in this case guided in the circumferential direction, but held axially displaceably, by means of its axially protruding tabs 1 5 by openings 24 in the cover plate 3.It transmits the initial stress force of the spring 22 through the friction ring 1 9 to the counterpressure ring 13, which rests fast in rotation on the tabs 10 of the under-load friction disc 9. The configuration of these tabs 10 of the under-load friction disc 9 is represented in perspective and diagrammatically in Fig. 2.

The under-load friction disc 9 comprises several axially angled-off tabs 10 each possessing an end face 11 for the support of the counterpressure ring 1 3. For its entraining fast in rotation the counter-pressure ring 1 3 comprises openings which grasp without play around the noses 1 2 of the tabs 10, in the circumferential direction. In this case the axial extent of the noses 1 2 is less than the material thickness of the thrust ring 14. Thus the initial stress force of the spring 22 is transmitted to the tabs 10 of the under-load friction disc 9 and thence through the friction ring 1 8 to the cover plate 4. The force transmission to the spring 22 is closed by the firm connection of the two cover plates 3 and 4 with one another.Thus in the under-load range the friction rings 18. 19 and 21 are in action, since for the one part the under-load friction disc 9 with the counter-pressure ring 1 3 is fast in relation to the hub disc 2 and for the other part the cover plates 3 and 4 with the thrust ring 1 4 and the pressure plate 1 6 carry out a relative movement. In the present case the counter-pressure ring 1 3 is formed as second under-load friction disc parallel to the under-load friction disc 9. This brings a better loading distribution for the under-load friction disc 9 with the tabs 10.

The spring 22 can of course also be of a configuration such that the spring tabs 23 protrude radially outwards, whereby then logically the external circumference 25 of the basic body 24 of the spring 22 would be brought to abut on the cover plate 3.

In operation the clutch disc according to Fig. 1 behaves as follows:- As long as the clutch disc is unloaded, the tab 10 assumes a middle position within the window 6. This middle position- is determined by the fact that in the under-load friction disc 9 there are formed fork openings 9a which abut on the ends of the helical compression spring 8. The extent of the tabs 10 in the circumferential direction is less than the extent of the windows 6 in the circumferential direction.

The friction moment generated by the spring 22 and the friction rings 1 8 and 1 9 is greater than the friction moment generated by the spring tabs 23 and the friction rings 20 and 21. As long as the cover plates 3 and 4 carry out only small angular deflections in relation to the hub 1, and the tab 10 moves within the window 6 and the parts 4, 3, 10, 13, 14, 1 8 and 1 9 behave as one unit. This unit carries out an angular movement in relation to the disc 2. This angular movement is damped by the friction rings 20 and 21 which are kept under pressure by means of the spring tabs 23 between the parts 9 and 2 and between 1 6 and 2 (idling damping).At this point it should be mentioned again that the tabs 1 7 hold the pressure plate 1 6 nonrotatably fast in relation to the cover plate 3, that the tabs 1 5 hold the thrust ring 14 nonrotatably fast in relation to the cover plate 3 and that the noses 1 2 of the tabs 10 connect the counter-pressure ring 1 3 non-rotatably with the under-load friction disc 9.

If the angular deflections of the cover plates 3, 4 in relation to the hub 1 become greater, then according to the direction of the deflection the tab 10 comes to abut on the one or the other end of the window 6. If then a further rotation of the cover plates 3 and 4 in relation to the hub 1 takes place, the parts 9 and 1 3 are stationary in relation to the hub disc 2.Then the cover plate 4 rubs against the under-load friction disc 9 through the intermediary of the friction ring 18, the thrust ring 1 4 rubs against the counter-pressure ring 1 3 through the intermediary of the friction ring 19; moreover the friction of the underload friction disc 9 against the disc 2, through the intermediary of the friction ring 20, and the friction of the thrust plate 1 6 against the disc 2, through the intermediary of the friction ring 21, are still as effective as before. One speaks of operation under load.

When the loading of the clutch disc is terminated, the cover plates 3 and 4 return, due to the action of the helical compression springs 8, into the rest position in relation to the disc 2 and the hub 1. At the same time the under-load friction disc 9, through the intermediary of the fork opening 9a, returns again into that angular position in which the tab 10 assumes a middle position within the circumferential extent of the window 6.

Claims

1. Torsional vibration damper, especially for motor vehicle clutches, having a spring device for generating friction force, in which a mutual rotation is possible between a hub disc of a hub and cover plates arranged to both sides of the hub disc, against the force of torsion springs, and two different friction devices are provided, namely an idling and an under-load friction device, the friction force generation of which takes place on the same side between hub disc and cover plate in two regions arranged radially one above the other, characterised in that the spring device consists of a single spring (22) the basic body (24) of which is formed as dished spring which is supported between cover plate (3) and the one friction device (4, 9, 13, 14, 18, 19) and comprises spring tabs (23) reaching out beyond its radial contour, which form an obtuse angle with the basic body (24)-seen in cross-section-and bear on the other friction device (2, 9, 16, 20, 21).

2. Torsional vibration damper according to Claim 1, characterised in that the spring tabs (23) preferably reach out beyond the internal circumference (26) of the basic body (24) and bear upon the idling friction device (16), with the external circumference (25) of the basic body (24) bearing on the under-load friction device (4, 9, 13, 14, 18, 19) and the internal circumference (26) on the cover plate (3).

3. Torsional vibration damper according to Claims 1 and 2, in which an under-load friction disc is arranged between the hub disc and the one cover plate on the side opposite to the spring, with axially angled-off tabs which penetrate corresponding opeings in the hub disc and are loaded with the spring force of the spring for the under-load friction device, characterised in that between the spring (22) bearing on the cover plate (3) and the ends (11) of the tabs (10) a thrust ring (14), a friction ring (1 9) and a counter-pressure ring (13) are arranged, the thrust ring (14) being connected fast in rotation but axially dispiaceably with the cover plate (3) and the counter-pressure ring (1 3) being connected fast in rotation with the tabs (10).

4. Torsional vibration damper according to Claim 3, characterised in that the thrust ring (14) reaches with axially bent-off tabs (15) into openings (24) in the cover plate (3), the spring (22) is fixed with its external contour (25) radially on the tabs (1 5) and the spring tabs (23) point radially inwards and towards the hub disc (2)-for the axial loading of the idling friction device (2, 9, 16, 20, 21).

5. Torsional vibration damper according to Claims 1 to 4, characterised in that the counter-pressure ring (1 3) is guided in the circumferential direction by noses (1 2) arranged on the ends (11) of the tabs (10) of the underload friction disc (9), which noses engage in corresponding openings of the counter-pressure ring (1 3).

6. Torsional vibration damper according to Claims 1 to 5, characterised in that the axial extent of the noses (12) is less than the material thickness of the counter-pressure ring (13).

7. Torsional vibration damper according to Claims 1 to 6, characterised in that the counter-pressure ring (13) is formed as second under-load friction disc.

8. Torsional vibration damper substantially as herein described with reference to the accompanying drawings.