GB2184812A

GB2184812A - Torsional vibration damper

Info

Publication number: GB2184812A
Application number: GB08630261A
Authority: GB
Inventors: Matthias Fischer; Franz Hartig; Norbert Ament; Rainer Ziss
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1985-12-21
Filing date: 1986-12-18
Publication date: 1987-07-01
Also published as: DE3545745C2; GB2184812B; GB8630261D0; DE3545745A1; FR2592116B1; FR2592116A1

Abstract

The invention relates to a delayed under-load friction device where the angle in which this friction device is not effective is made greater than the angle range over which the idling system is operative. Thus a premature onset of the friction device with high friction value is suppressed within the idling operation. <IMAGE>

Description

SPECIFICATION Torsional vibration damper The invention relates to a torsional vibration damper, especially for motor vehicle friction clutches.

A torsional vibration damper known for example from Fed. German Insp. Doc. No.

3,206,623 consists of an under-load system with components rotatable in relation to one another against the force of torsion springs of steep characteristic curve, an idling system between under-load system and a hub with torsion springs of flat characteristic curve, an idle rotation play in accordance with the range of action of the idling system being provided between the output parts of the under-load system and the hub, a friction device with low friction moment which is effective at least in the idling range, and a friction device with higher friction moment which is effective with delay due to play.The vibration damper has a delayed friction device which, in change of load and passing through the idling range, is to prevent noises which occur due to striking of the window edges of those torsion springs which come into use following upon the flat spring characteristic curves of the idling springs.

Now however the situation is that this delayed friction device can come into action not only in idling operation shortly before the end of the idling spring characteristic, but at every point of the traction-thrust diagram where the torsion damper is situated at the time. Equipment of this system solely for the idling range is therefore not sensible, for this delayed friction device should suppress load-change impacts which occur above all when for example a change is made from a high traction moment suddenly into the overrun range or vice versa. In this case it has appeared that the friction moment necessary for this friction device must be made higher by more than only one power of ten than the friction moment which is practically suitable in idling operation.

There are application cases where the delayed friction moment must be made up to a hundred times the idling moment. In such a case the making of the idle travel less than the idling range would be very troublesome, since the danger would exist here that additional noises would already occur in the idling range due to striking upon this high friction device.

It is therefore the problem of the present invention to improve a delayed friction device to the effect that on the one hand it effectively suppresses the load-change noises but on the other hand it in no way negatively influences the idling operation.

In accordance with the invention this problem is solved by the characteristic of the claim 1. By increase of the delay angle for the action of the friction device with high friction moment to a value which is greater than the range of the idling system it is ensured that within the idling range at all occurring operational conditions the action of the high friction device is precluded. Thus it is possible to attune the friction device exactly to the purpose attributed to it, namely to the suppression of noises and vibrations during a load change.

The invention will next be explained in greater detail by reference to several examples of embodiment.

Individually: Figure 1 shows the partial longitudinal section through a clutch disc with integrated idling system; Figures 2 and 3 show a partial elevation and partial section of a variant of embodiment; Figure 4 shows the upper half of a partial longitudinal section through an embodiment with separately arranged idling system.

Fig. 1 shows the partial longitudinal section of a torsional vibratin damper which consists of the following parts:- A hub 1 is provided in the usual way with an internal toothing with which it engages axially displaceably but without play in the circumferential direction in a gear shaft (not shown). The hub 1 is integrally provided with an annular flange 2 having an external toothing 3 on its external circumference. A hub disc 6 engages with an internal toothing 7 with play in this external toothing 3. This play between the two toothings 3 and 7 corresponds to the range of action of the idling system. The idling system consists of several circumferentially distributed springs 12 with flat spring characteristic curve., which are arranged for example according to Fed. German Insp. Doc. No. 3,415,927 within the toothings 3 and 7.On both sides of the annular flange 2 there are arranged two cover plates 4 and 5 which cover the toothings 3 and 7 and the springs 12. To the idling system there further pertains a friction device, consisting of an angle ring 14, a spring 15 and a friction ring 13. The torsional vibration damper further comprises an under-load system which consists of the springs 11 with steep spring characteristic curve and of the cover plates 8 and 9 with which the springs 11 co-operate. The cover plates 8 and 9 are connected fast in rotation with one another and held spaced in a manner not further illustrated. The one cover plate 8 carries the friction linings 10 on its external circumference, through which linings the torque can be introduced into the torsional vibration damper.The under-load system further comprises a friction device which is effective between the cover plates 8 and 9 and the hub disc 6. It consists of two friction rings 25 and 26 which are arranged to both sides of the hub disc 6. The friction ring 25 is inserted directly between hub disc 6 and cover plate 9, while on the opposite side a thrust ring 27 and a dished spring 28 are provided. The thrust ring 27 reaches with axially angled-off noses 29 without play in the circumferential direction into corresponding openings 30 of the cover plate 8. This friction device is effective only in relative rotation between the hub disc 6 and the two cover plates 8 and 9 and has a high friction moment. Furthermore what is called a delayed friction device is provided in the torsional vibration damper.This consists of a control plate 17 which is mounted on the hub 1 freely rotatably against the force of a friction clamp. The control plate 17 is here arranged close beside the cover plate 9 and is in connection therewith with play according to Fig. 2 through an engaging device. This engaging device consists in the present case of axially angled-off noses 16 of the cover plate 9 which engage with play in corresponding apertures 18 of the control plate 17. The play amounts in the one direction to the value a and in the other direct- the value ss. These two angles, which together constitute the play, can be equal or unequal in the rest position, this division arising by tuning on the corresponding vehicle.The friction clamping of the control plate 17 is effected through a friction ring 19 between cover plate 5 and control plate 17, a friction ring 21 on the other side of the control plate 17 and a support ring 22 which is guided fast in rotation but axially displaceably in a groove 31 of the hub 1, also further through a dished spring 23 and a circlip 24 for axial support. Here the cover plate 9 has an internal diameter D which is greater than the internal diameter of the cover plate 8 for the reception of the delayed friction device.

The function of the torsional vibration damper according to Figs. 1 and 2 is as follows: Starting from a rest position according to Fig. 2, let it be assumed that the torsional vibration damper initially works only when the internal combustion engine is idling, that is only a moment which drives the gear main shaft is transmitted through the friction linings 10. In this idling range the under-load system, consisting of the cover plates 8 and 9, the springs 11 and the friction device 25, 26, 27, 28, is to be regarded as a rigid unit. The torsional vibrations occurring in idling are damped by the idling system and between under-load system and hub 1 there occur only relative movements which are smaller than the play between the internal toothing 7 of the hub disc 6 and the external toothing 3 of the hub 1.In this case the springs 1 2 with flat characteristic curve are under load and the friction device of the idling system, consisting of the angle ring 14, the spring 15 and the friction ring 13, is effective. The components participating in this friction have a very low coefficient of friction, so that in combination with the spring 15 a friction moment of 0.5 Nm. at maximum occurs. The inherently loosely accompanying cover plates 4 and 5 therefore remain in fixed abutment in relation to the annular flange 2, as a result of their relatively high coefficient of friction. On loading of the torsional vibration damper in driving operation a considerably greater deflection of the cover plates 8 and 9 in relation to the hub 1 takes place. Thus the range of the idling system is passed and this is not further loaded.In this range the under-load system comes into use, that is now the two cover plates 8 and 9 can turn in relation to the hub disc 6 against the force of the springs 11.

The hub disc 6 is here made fast in relation to the hub 1 by the using up of the play between the toothings 3 and 7. In the case of deflections which significantly overstep the range of action of this play, the additional friction device also comes into effect. In that case the control plate 17 is turned by the noses 16 of the cover plate 9, the friction clamping of the control plate 1 7 becoming effective. In the case as illustrated friction rings 19 and 21 with a coefficient of friction less than steel upon steel are in use. Thus the cover plate 5 also reliably remains stationary in relation to the annular flange 2. Thus in this range an additional slight friction force also arises from the relative movement between cover plate 9 and annular flange 2 at the position of the friction ring 13.This additional friction is admittedly of subordinate value, since in the under-load range in all a friction moment of up to 30 to 40 Nm. can be necessary. On reversal of movement, that is on a change from pulling to overrun operation or vice versa, over an angle range of a+B only the under-load friction device corresponding to the parts 25, 26, 27 and 28 is effective, with co-operation of the friction ring 13 with a very small proportion. Only thereafter does the delayed friction device come into action again.

In Fig. 3 there is reproduced the partial section of a variant compared with Fig. 1. In this case the additional friction device is arranged in a space-saving manner in the axial direction, in that the support ring 22 abuts directly on the control plate 1 7 and the friction ring 20 likewise consists of metal. Thus from the outset the higher friction value of metal on metal is effective, and thus either the friction force can be increased or the initial stress force of the dished spring 23 can be reduced. The remainder of the arrangement and effect corresponds to that of Fig. 1. However it should be mentioned here that by the use of metal on metal under some circumstances the cover plate 5 can also carry out a relative movement in relation to the annular flange 2. This however is not harmful to the function, since the share of the friction ring 13 in the total friction is insignificant as a result of the low force of the spring 1 5 and the low friction value.

Fig. 4 shows the upper half of a partial section through a torsional vibration damper having a completely different assembly. The two cover plates 8 and 43 of the under-load system co-operate with springs 11 and a hub disc 42 is arranged between the cover plates.

This disc is made L-shaped in its radially inner region and inserted with its internal toothing 7 into the external toothing 3 of the hub 1, with play in the circumferential direction corresponding to the range of effect of the idling system. The end zone of the cylindrical flange of the hub disc 42 penetrates the radially inner zone of the cover plate 8 in axial direction and is connected outside the cover plate 8 fast in rotation with the two cover plates 39 and 40 of the idling system. The hub disc 38, which is seated fast on the hub 1, is arranged between the two cover plates 39 and 40. The springs 12 are arranged in known manner between the cover plates 39 and 40 and the hub disc 38. Furthermore a friction device is provided which consists of a spring 15 and a friction ring 37 which are arranged between cover plate 39 and hub disc 38.The friction device for the under-load system is situated in the cylindrical region of the L-shaped hub disc 42, between the latter and the cover plate 8.

It consists in the usual way of a friction ring 36 between cover plate 40 and cover plate 8, a thrust ring 27 which engages with noses 29 without play in the circumferential direction in corresponding openings 30 of the cover plate, and a dished spring 28 and a further friction ring 26 between thrust ring 27 and hub disc 42. The friction device with delayed onset is arranged between cover plate 43 and hub 1.

For this purpose the external toothing 3 is stepped and merges into an external toothing 45 with reduced external diameter. This results in an axial stop 46 which serves for supporting a friction ring 33 which engages fast in rotation in the external toothing 45.

This is adjoined by a control plate 32 which is provided in its radially outer region with axially angled-off noses 35 which engage with play according to Fig. 2 in corresponding apertures 34 in the cover plate 43. A support ring 22 is laid from the exterior upon the control plate 32, and likewise engages without play in the external toothing 45. The three parts 33,32 and 22 are loaded by a dished spring 23 which is supported against the hub 1 by a circlip 24. The manner of operation of this torsional vibration damper is in principle in conformity with that of Figs. 1 to 3. The difference is to be seen merely in the constructive assembly. The lateral arrangement of the idling system in the present case involves greater freedom in attunement.

Claims

1. Torsional vibration damper, especially for a motor vehicle clutch, comprising a) two components (1, 10) rotatable in relation to one another about a common axis of rotation, b) a spring system (12) dimensioned for idling operation, effective at least at a relative angle of rotation of the components (1, 10) within a first angle range including a rest position and rotationally elastically coupling the components (1, 10) with one another, c) a second spring system (11) dimensioned for operation under load, effective at least at a relative angle of rotation greater than the angle range including the rest position, and rotationally elastically coupling the components (1, 10) with one another, d) a first friction device 13, 15; 15, 37) dimensioned for idling operation and effective at least in the first angle range, e) a second friction device (17, 19, 21, 23; 22, 23, 32, 33) arranged in a torque shunt path to the second spring system (11), which is coupled through an idle motion clutch (16, 18; 34, 35) to the components (1, 10) and after take-up of the idle travel of the idle motion clutch (16, 18; 34, 35), independently of the relative angle of rotation of the components (1, 10), generates a friction moment which is greater than the friction moment of the first friction device (13, 15; 15, 37), characterised in that the idle travel of the idle motion clutch (16, 18; 34 35) is greater than the first angle range including the rest position of the components (1, 10).

2. Torsional vibration damper according to Claim 1, having a hub (1), a hub disc (6; 42) and two firmly interconnected cover discs (8, 9; 8, 43) arranged on axially opposite sides, which are mounted on the hub (1) rotatably in relation thereto and coupled through the second spring system (11) rotationally elastically with the hub disc (6; 42), the second friction device (17, 19, 21, 23; 22, 23, 32, 33) comprising a control disc (17; 32) clamped in in frictional engagement in relation to the hub (1) and rotatable in relation to the hub (1), which control disc is connected through the idle motion clutch (16, 18; 34, 35) with a first (9; 43) of the two cover discs (8, 9; 8, 43), characterised in that the hub disc (6; 42) is mounted rotatably on the hub (1) and is coupled through a toothing (3, 7) with the hub (1) with a play in rotation defining the first angle range, in that the first spring system (12) couples the hub disc (6; 42) rotationally elastically with the hub (1) and in that a third friction device (25, 26, 28; 26, 28, 36) dimensioned for under-load operation and effective independently of the relative angle of rotation between the cover discs (8, 9; 8, 43) and the hub disc (6; 42) is arranged in a torque shunt path to the second spring system (11).

3. Torsional vibration damper according to Claim 2, characterised in that the second (8) of the two cover discs (8, 9; 8, 43) is guided radially on the hub (1), in that the control disc (17; 32) is clamped in together with an axially acting spring (23) between two shoulder faces facing axially towards one another and provided on the hub (1) and in that the idle mo tion clutch (16, 18; 34, 35) is formed by apertures (18; 34) and noses (16; 35) of the first cover disc (9; 43) and of the control disc (17; 32) which engage axially movably in the apertures (18; 34).

4. Torsional vibration damper according to Claim 3, characterised in that the first cover disc (9) together with the hub (1) limits an annular gap, in that the toothing (3) of the hub (1) is provided on an annular flange (2) which radially overlaps the first cover disc (9), and in that a friction ring (13) of the first friction device (13, 15) is arranged in the overlap region and a friction ring (19) of the second friction device (17, 19, 21, 23) is arranged in the region of the annular gap.

5. Torsional vibration damper according to Claim 4, characterised in that the first friction device (13, 15) comprises an axially acting spring (15) clamped in axially between the second cover disc (8) and the annular flange (2) and in that the axially acting spring (23) of the second friction device (17, 19, 21, 23) is arranged on the side of the control disc (17) remote from the annular flange (2).

6. Torsional vibration damper according to Claim 4 or 5, characterised in that the control disc (17) is arranged on the side of the first cover disc (9) axially remote from the annular flange (2) and in that the noses (16) are arranged on the first cover disc (9).

7. Torsional vibration damper according to one of Claim 3 to 5, characterised in that cover discs (4, 5) radially overlapping the toothing (3, 7) are arranged axially on both sides of the annular flange (2) and rest rotatably on the annular flange (2).

8. Torsional vibration damper according to Claim 2 or 3, characterised in that the hub disc (42) carries an extension directed axially away from the control disc (32) and carrying the toothing (7), on which extension the second (8) of the two cover discs (8, 43) is rotatably guided radially, in that the first spring system (12) is arranged on the side of the second cover disc (8) remote from the hub disc (42) and couples the extension with the hub (1) and in that the toothing (3) of the hub (1) forms a stop step (46) for the axial clamping-in of the second friction device (22, 23, 32, 33).

9. Torsional vibration damper according to Claim 8, characterised in that the second friction device (22, 23, 32, 33) comprises two annular discs (22, 33) guided fast in rotation but axially movably on the toothing (3) of the hub (1), between which the control disc (32) is clamped in by means of an axially acting spring (23) which is arranged between the annular disc (22) remote from the stop step (46) and a securing ring (24) of the hub (1).

10. Torsional vibration damper according to Claim 8 or 9, characterised in that the first spring system (12) includes a disc (40) fixedly arranged on the extension of the hub disc (42) and in that the third friction device (26, 28, 36) comprises an axially acting spring (28) arranged between the second cover disc (8) and the hub disc (42).

11. Torsional vibration damper according to Claim 10, characterised in that the third friction device (26, 28, 36) comprises a first friction ring (36) between the disc (40) of the first spring system (11) and the second cover disc (8), a second friction ring (26) between its spring (28) and the hub disc (42) and a thrust ring (27) between its spring (28) and the second friction ring (26).

12. Torsional vibration damper as claimed in claim 1, substantially as described with reference to Fig. 1, Fig. 2, and Fig. 3, or Fig. 4 of the accompanying drawing.