GB2147085A

GB2147085A - Friction clutch for a motor vehicle

Info

Publication number: GB2147085A
Application number: GB08422624A
Authority: GB
Inventors: Dagwin Tomm; Matthias Fischer; Harald Raab
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1983-09-24
Filing date: 1984-09-07
Publication date: 1985-05-01
Also published as: JPS6091031A; GB2147085B; JPH0563649B2; GB8422624D0; FR2552509A1; DE3334657A1; FR2552509B1; DE3334657C2

Abstract

The invention relates to an arrangement for suppressing knocking noises between the toothings of the hub 15 of a clutch disc 11 and of a gear shaft 13, especially during idling. For this purpose on the clutch hub there is held a component 35 which engages with radially resilient tabs 37 in the tooth gaps of the toothing of the gear shaft 13. This component produces a force- effected connection between hub and gear shaft and is capable of transmitting the torques which occur in idling. In order to improve the disengagement behaviour of the clutch after fitting of the clutch disc, this component 35 is braced in the axial direction so that it exerts a force acting in the disengagement direction upon the hub of the clutch disc. In order to adjust the bracing automatically, on one of the cover plates 33 of the clutch disc which twist in relation to the hub on torque loading there are provided tongues which axially displace the component by means of oblique faces. Thus the component comes to abut on a surface of the hub, whereby a precise, predetermined initial axial stress can be maintained. <IMAGE>

Description

SPECIFICATION Friction clutch for a motor vehicle The invention relates to a friction clutch for motor vehicles and especially to a friction clutch in which the play is suppressed between a hub of its clutch disc and a gear shaft.

It is known from Fed. German Pubs. Spec.

No. 2,062,414 to guide movable balls radially resiliently between an internal spline toothing of the hub of a clutch disc and the external spline toothing of a gear shaft on which the hub is axially displaceably guided, which balls suppress the play, which is necessary between the two spline toothings, under force application for low torques. While this play between the two toothings is relatively slight, it is however unavoidable for the facilitation of the assembly of engine and gearing.

Furthermore production tolerances can be reduced only at great expense in production technique. The play is troublesome especially when the internal combustion engine is idling and the clutch is engaged. In this operational condition only a very slight torque is delivered by the friction clutch through the toothings to the gearing. By reason of irregular rotation of the internal combustion engine the flanks of the two toothings strike against one another and generate noises. In the known clutch the flank play can be suppressed at least in the idling range, while the tooth flanks come to abutment only in transmission of a greater torque and the balls move radially against their spring application.

However one considerable disadvantage arises in the case of such an arrangement.

The satisfactory operation of separation of the clutch is dependent upon the fact that the internal spline toothing of the hub is guided axially easily displaceably on the external spline toothing of the gear shaft. For the separation of the clutch, that is in the disengagement of the presser plate, the friction linings of the clutch disc should be spaced both from the flywheel and from the presser plate. In addition the entire clutch disc including its hub must disengage itself from the flywheel. This disengagement of the clutch disc is not guaranteed in the case of the play suppression of the known clutch.

An object of the present invention, with the simplest possible means, is to suppress the noises which occur due to knocking of the flanks of the two toothings when the internal combustion engine is idling with the clutch engaged, while at the same time the functioning of the clutch, especially the function of disengagement of the clutch disc, should not be impaired.

According to the invention the play compensation elements guided radially resiliently on the hub are additionally axially resiliently guided. The play compensation elements are preferably formed as radially resilient tabs pointing in the axial direction and generate a force-operative connection in both the circumferential and axial directions betweenqthe hub of the clutch disc and the gear shaft. The force-effected engagement is dimensioned so that the forces occurring in the idling range between gear shaft and clutch disc can be transmitted. Mutual abutment of the flanks of the toothings takes place only outside the idling range, when greater torques of the under-load range are to be transmitted.The radially resilient tabs are preferably retained on an annular stop part which for its part is axially resiliently held through tabs on the hub or an additional securing ring of the hub. The stop part exerts an initial axial stress force upon the hub of the clutch disc in the disengagement direction. Thus with one single component the knocking noises of the toothing which occur in the idling range can be suppressed and at the same time the readiness to disengage of the clutch disc can be improved. The axial initial stress force of the stop part can be generated in the assembling of clutch and gearing in that distance elements are inserted between clutch disc and flywheel and are removed again after the assembling of clutch and gearing, that is after the introduction of the gear shaft into the hub of the clutch disc.In this way the hub of the clutch disc assumes, in relation to the tabs axially fixed by the friction force, a position which lies nearer to the presser plate and it loads the stop part with an initial axial stress force which endeavours to move the clutch disc away from the presser plate, in relation to the gear shaft. Thus an initial stress force is applied in the sense of a disengagement force.

It is advantageous to have the stop part abut, close to its radially resilient tabs, on a face of the hub facing the flywheel, when the clutch is engaged, since with this measure an automatic wear compensation takes place at the same time guaranteeing that the lift-away force remains constant over the entire range of wear of the friction linings.

The twisting movement of a torsional vibration damper inteflgrated into the clutch disc is preferably exploited for the setting of the correct axial spring force. By means of a control element the stop part is applied by way of axial thrust faces in the axial direction to the stop face of the hub. At the same time the control element protects the axially resilient tabs against overstretching in the axial direction during the assembling of clutch and gearing, since it is arranged at the predetermined distance from the stop face of the hub and thus limits the axial play space of the stop part. It is in principle immaterial whether the radially resilient tabs-seen in the axial direc tion-are directed from the hub of the clutch disc towards the flywheel or whether they point in the opposite direction.However in every case the introduction of the gear shaft in assembly and the withdrawal of the gear shaft in dismantlement must be guaranteed.

The axially resilient components, especially the axially resilient tabs, are preferably so formed, for example by corrugations proceeding in the circumferential direction, that they additionally provide resilience in the circumferential direction. In or after the transition from the idling range to the under-load range thus the relative rotation in the range of the play of the toothings, occurring between hub and gearing, is compensated by the circumferential resilience. Thus the radially resilient tabs are relieved of a rubbing movement in this range.

The invention will be explained in greater detail below by reference to two examples of embodiment. Individually: Figure 1 shows an axial longitudinal section through a motor vehicle friction clutch; Figure 2 shows an axial view of a middle region of a clutch disc of the friction clutch according to Fig. 1; Figure 3 shows an axial view of a component used in the clutch according to Fig. 1 to bridge over tooth flank play; Figure 4 shows a view in section through the component according to Fig. 3, seen along a line IV-IV; Figure 5 shows a sectional view of a detail of the component according to Fig. 3, seen along a line V-V; Figure 6 shows a sectional view of another detail of the component according to Fig. 3, seen along a line VI-VI; Figure 7 shows a detail VII of the component according to Fig. 3;; Figure 8 shows an axial view of a connecting ring of the friction clutch according to Fig.

1; Figure 9 shows a sectional view of the connecting ring according to Fig. 8, seen along a line IX-IX; Figure 10 shows the view of a rivet; Figure 11 shows an axial section through another form of embodiment of a clutch disc for a motor vehicle friction clutch and Figure 12 shows an axial view of the middle region of the clutch disc according to Fig.

11.

In Figs. 1 and 2 there are represented a motor vehicle friction clutch and its clutch disc respectively. Fig. 1 shows a flywheel 1 which is fitted on a crankshaft (not shown) of an internal combustion engine. A clutch cover 3 is secured on the flywheel 1. On the clutch cover 3 there is pivotably mounted a clutch main spring in the form of a diaphragm spring 5 which, in the region of its external diameter, presses to the flyheel 1 a presser plate 7 connected axially displaceably but fast in rotation in the circumferential direction with the clutch cover 3 and/or the flywheel 1. The friction linings 9 of a clutch disc 11 are clamped in between the presser plate 7 and the flywheel 1. The clutch disc 11 transmits to a gear shaft 1 3 the torque delivered by the internal combustion engine.For this purpose the clutch disc 11 is provided with a hub 1 5 which is arranged with its internal spline toothing 1 7 fast in rotation but axially displaceably on an external spline toothing 1 9 of the gear shaft 1 3. A torsional vibration damper 21 is arranged between the hub 15 and the friction linings 9. The damper 21 comprises damping springs 23 which are arranged in windows 25 and 27 respectively of a hub disc 29 for the one part and of a cover plte 31 and a lining carrier 33 for the other part.On torque loading of the clutch disc 11 the friction linings 9 and the hub 1 5 can rotate in relation to one another about the axis of rotation of the clutch through a predetermined angle of rotation, This rotating movement is additionally damped by friction elements.

Especially in idling, noises can occur as a result of the irregularity of the drive, since the flanks of the toothings 1 7 and 1 9 of the hub 1 5 and the gear shaft 1 3 strike against one another. Such noises cannot be prevented even by a torsional vibration damper especially attuned to the idling range. In order to suppress the idling noises a component 35 constitutes a force-operated connection between the hub 1 5 and the gear shaft 1 3 which can transmit such a great torque that at least in idling the flanks of the two toothings 1 7 and 1 9 do not strike against one another.

The component 35 extends essentially in a plane parallel to the clutch disc 11 and comprises at least two mutually opposite, radially resilient tabs 37 which protrude approximately axially. The tabs 37 are axially aligned with the teeth of the internal spline toothing 1 7 and lie, as may be seen especially from Fig. 7, under radial initial stress upon the external spline toothing 1 9 of the gear shaft 1 3 in such a way that they partially enter tooth gaps 39 each between two axially extending teeth 41.

According to Fig. 1 the tabs 37 point away from the flywheel 1; however as may be seen from Fig. 11 the tabs 37 can also point in the opposite direction. In this case admittedly the external spline toothing 1 9 must be longer in the axial direction.

The force-effected engagement between the resilient tabs 37 and the external spline toothing 1 9 is so dimensioned that the torques occurring in idling are reliably transmitted. In the operating condition under load, compared therewith, substantially greater torques are to be transmitted, and the torque exceeding the idling torque is transmitted in the operating conditions under load by way of the flanks of the two spline toothings 1 7 and 19. In order not to permit any relative movements to occur between the resilient tabs 37 and the flanks of the teeth 41, in the relative movement of the hub 1 5 and the gear shaft 13, the compo nent 35 is made resilient in the circumferential direction.As may be seen from Fig. 2 and especially from Figs. 3 to 7, the component 35, seen in axial view, comprises an annular zone 43 concentric with the axis of rotation and carrying the radially resilient tabs 37, in the present case six tabs in all, on its internal circumference. From its radially outer region two springs tongues 45 of substantially quarter-circular course extend away in the same circumferential direction.At their free ends the spring tongues 45 have openings 47 serving for rivetting with the hub 1 5. The spring tongues 45 are of such configuration that they transmit the torque in idling practically without deformation and yield resiliently in the circumferential direction, to permit the flanks of the two toothings 1 7 and 1 9 to come into abutment, only in the case of a markedly increasing torque. For this purpose the spring tongues 45 are slightly curved or corrugated in their longitudinal directions.

The component 35 not only suppresses the noises between the hub 1 5 and the gear shaft 1 3 in idling, but additionally also transmits an axial force-even though small-to the hub 1 5, supporting the action of disengaging the clutch disc 11. For this purpose a further arrangement is provided without which the component 35 would be shifted in the direction towards the flywheel 1, in the assembling of clutch and gearing by introduction of the gear shaft 1 3 into the hub 15, as a result of the friction force occurring between the resilient tabs 35 and the gear shaft 1 3. After assembly the spring tongues 45 would exert upon the hub 1 5 an axial force acting towards the flywheel 1.Such a force would hinder the operation of disengagement of the clutch disc 11 and at least render a satisfactory separation of the friction linings 9 from the flywheel 1 much more difficult. In order to avoid this the axial deflection of the annular region 43 of the component 35 in relation to the points of securing of the free ends of the spring tongues 45 on the hub 1 5 is limited during assembly and dismantlement. The securing of the free ends of the spring tongues 45 takes plafe through rivets 49 and a ring 51 which is seated fast on the hub 1 5. Furthermore on the hub 1 5 a face 53 is provided upon which the annular zone 43 of the component 35 can strike axially in order that the initial stress in the disengagement direction may be adjusted exactly.During the fitting of the clutch disc 11 the annular zone 43 of the component 35 is at a predetermined distance from the face 53 of the hub 1 5 determined for example by the form of the rivet 49 according to Fig. 10.

Each rivet 49 has a middle part 55 which, as a result of its predetermined axial extent, determines the initial stress force in the in stalled condition. In order that the component 35, after installation, may be intendedly axially braced, a control element 57 is provided by means of which the annular zone 43 of the component 35 can be pushed axially against the face 53. The control element 57 is se cured to the lining carrier 31 and comprises an annular zone 59 which is approximately coincident in the axial direction with the annular zone 43 of the component 35. The annular zone 59, as may be seen especially from Fig. 1, is arranged at a distance from the face 53 of the hub 15.

The annular zone 43 of the component 35 can be displaced axially between the annular zone 59 and the face 53. After the assembling of gearing and clutch the annular zone 43 of the component 35 initially rests against the annular zone 59 of the control element 57, since the gear shaft 1 3 is introduced from the opposite side (from the right in Fig. 1) into the hub 1 5. In order to bring the annular zone 43 of the component 35 into the desired operational position according to Fig. 1, that is to abut on the face 53, the annular zone 59 of the control element 57 comprises several elevations 61 distributed on the circumference which correspond with zones 63 of the component 35, as may be seen especially from Figs. 2 and 3.The zones 63 of the annular zone 43 of the component 35, seen in the circumferential direction, merge into oblique faces 65 which again terminate in zones 67.

The zones 63 and 67 are arranged with axial spacing from one another. On the first torsional stressing of the torsional vibration damper 21 after assembly the elevations 61 of the control element 57 shift the component 35 automatically in the axial direction along the oblique faces 65 of the annular zone 43 until it abuts on the face 53 of the hub 15. Thus the component 35 is automatically brought into its position necessary for functioning in order to be able to exert a disengaging force upon the hub 1 5. By suitable dimensioning of all components thus an exactly predetermined axial bracing of the component 35 can be achieved automatically. In order that the annular zone 43 of the inherently elastic component 35 may not be elastically deformed too much during this shift action, on the external circumference of the annular zone 43 there is provided an axially protruding edge 69 which acts as stiffening in this zone. The control element 57 is provided with two mutually opposite arms 71 which, during the fitting of the clutch disc 11, are inserted into a centring step 73 of the lining carrier 33, fixed and preferably welded there. Other types of connection, as for example rivetting or adhesion, are also possible.

This style of assembly has the advantage that the control element 57 can easily be orientated in relation to the component 35, after the assembling of the hub 1 5 and the component 35.

In the clutch according to Fig. 1 spring segments 75 serving for the axial springing of the friction linings 9 are secured directly to the lining carrier 33. In principle their securing to the cover plate 31 is also possible.

Figs. 8 and 9 show the ring 51 in axial view and in section. The ring 51 forms a connection member between the hub 1 5 and the component 35. The component 35 and the ring 51 are connected by rivets 49 such as are visible from Fig. 10. The ring 51 secured to the hub 1 5 ends flush with the face 53 of the hub 1 5. When rivets 49 with a suitably thickly dimensioned middle part 55 are used, the correct initial stressing distance of the component 35 from the face 53 is automatically produced. In this way an exactly fixed axial bracing of the component 35 and an exactly defined disengagement force are achieved.

Since the control element 57 is held on a component of the torsional vibration damper 21 which twists in relation to the hub 15 and the gear shaft 1 3 on torque loading in operation, the component 35, which is fixed in the circumferential direction in relation to the hub 1 5, can be axially displaced selectively by means of its oblique faces 65 in order to correct its position, which in itself is incorrect after the assembling of gearing and clutch.

This adjustment takes place automatically at the first torque loading of the clutch disc so that the present clutch disc with the play suppression can be fitted exactly as simply as all clutch disc hitherto.

A further form of embodiment of a clutch disc 11 for the friction clutch according to Fig. 1 is shown in Figs. 11 and 12. Here in Fig. 11 only the longitudinal section through the clutch disc with gear shaft is shown and in Fig. 1 2 the axial view of this clutch disc is shown, omitting the friction linings. In departure from the design according to Figs. 1 and 2, here the component 35 is formed so that the resilient tabs 37, pointing away from the hub 15, extend in the direction towards the flywheel 1. Furthermore the lining carrier 33 at the same time takes over the function of the control element 57 as explained with reference to Figs. 1 and 2. For this purpose the lining carrier 33 has two fingers 77 which point radially inwards and maintain a predetermined spacing from the face 53 of the hub 1 5. The fingers 77 co-operate with the component 35 in conformity with the elevations 61 in Fig. 1 and 2 and bring the annular zone 43 of the component 35 into the predetermined operational position after the assembling of gearing and clutch, that is to say into abutment on the face 53. This takes place likewise by means of the oblique faces 65 in the annular zone 43 of the component 35.

The elements in Figs. 11 and 1 2 otherwise correspond to the elements in Figs. 1 to 10 and are designated by the same reference numerals. For further explanation reference is made to the description of Figs. 1 to 10.

Claims

1. Friction clutch for motor vehicles, comprising: a) a flywheel defining an axis of rotation, b) a clutch cover secured to the flywheel, c) a presser plate guided fast in rotation but axially movably on the flywheel or the clutch cover, d) a clutch spring arrangement braced in between the clutch cover and the presser plate and resilient initially stressing the presser plate towards the flywheel, e) a clutch disc comprising friction linings clampable axially between the flywheel and the presser plate, a ahub connected with the friction linings with an axial, central hub opening, on the internal circumference of which there is provided an internal spline toothing consisting of a plurality of axially elongated spline teeth distributed in the circumferential direction, for a rotation-fast but axially displaceable coupling of the hub with an external spline toothing of a gear shaft, and several play-compensation elements offset in the circumferential direction of the hub which, oriented axially in relation to spline teeth of the internal spline toothing, in the circumferential direction are held substantially radially fixedly but movably on the hub and are resiliently initially stressed radially inwards for engagement in the external spline toothing of the gear shaft, characterised in that the play compensation elements are held axially resiliently on the hub and exert an initial stress force upon the hub which moves the clutch disc away from the flywheel.

2. Friction clutch according to Claim 1, characterised in that first, axially resilient tabs are secured by one end to the hub or a part connected with the hub and in that with the other ends of the first tabs there are connected second, radially resilient tabs which extend substantially axially and with their free ends form the play compensation elements.

3. Friction clutch according to Claim 2, characterised in that the first tabs are made resilient in the circumferential direction of the hub.

4. Friction clutch according to Claim 2 or 3, characterised in that the second tabs are held by means of a stop part on the first tab, which part in its region adjacent to the second tabs comprises a stop face which abuts, when the friction clutch is in the engaged condition, on a stop face of the hub axially facing the flywheel.

5. Friction clutch according to Claim 4, characterised in that the first tabs protrude from the external circumference of an annular disc enclosing the axis of rotation and forming the stop part, and the second tabs protrude from the internal circumference of the annular disc.

6. Friction clutch according to Claim 5, characterised in that the first tabs extend in the same direction substantially in the circumferential direction of the annular disc radially outside the annular disc.

7. Friction clutch according to Claim 6, characterised in that two first tabs offset by 180 in relation to one another are provided, each of which extends over a circumferential sector of about 90 .

8. Friction clutch according to Claim 6 or 7, characterised in that the first tabs are domed in their longitudinal direction.

9. Friction clutch according to one of Claims 5 to 8, characterised in that the annular disc is provided with an axially protruding stiffening edge along its external circumference between the first tabs.

10. Friction clutch according to one of Claims 2 to 9, characterised in that an annular disc is secured on the hub and in that the first ends of the first tabs are secured to the annular disc.

11. Friction clutch according to one of Claims 4 to 10, characterised in that the clutch disc comprises a torsional vibration damper having two components rotatable through a limited angle of rotation in relation to one another about the axis of rotation, of which the first component is connected fast in rotation with the hub and the second component is connected dast in rotation with the friction linings, in that on the second component a control element is secured which radially overlaps the stop part on the side axially remote from the hub and in that the control element and/or the stop part is provided in the overlapped region with an axial thrust face which on a relative rotation of the control element and of the stop part moves the stop part against the stop face of the hub.

1 2. Friction clutch according to Claim 11, characterised in that the stop part has on its side facing the flywheel several depressions offset in relation to one another in the circumferential direction, each of which is limited on both sides by oblique faces rising in the circumferential direction and in that the control element comprises projections engaging in the depressions.

1 3. Friction clutch according to Claim 11 or 12, characterised in that the first component of the torsional vibration damper comprises a hub disc firmly connected with the hub and protruding radially therefrom and the second component comprises cover discs arranged axially on both sides of the hub disc and firmly connected with one another and with the friction linings, and in that the control element is held on one of the cover discs and overlaps with the stop part in regions which are placed in the circumferential direction between adjacent first tabs.

14. Friction clutch according to Claim 1 3, characterised in that at least the regions of the control element which radially overlap the stop part extend with axial spacing from the one cover disc, in that this cover disc and the first tabs radially overlap and in that the stop part is arranged axially between the zones of the one cover disc which overlap the first tabs and the zones of the control element which overlap the stop part.

1 5. Friction clutch according to Claim 1 3 or 14, characterised in that at least the zones of the control element which radially overlap with the stop part are formed integrally on the one cover disc.

1 6. Friction clutch according to Claim 15, characterised in that the overlapping zones of the control element are formed as fingers formed integrally on the one cover disc and protruding radially inwards in cranked form towards the flywheel.

1 7. Friction clutch according to Claim 1 3 or 14, characterised in that the control element is formed as a separate component and is secured on the outer side, facing away from the stop part, of the one cover disc.

18. Friction clutch according to Claim 1 7, characterised in that the control element is formed as an annular disc from the external circumference of which several arms protrude which are offset in the circumferential direction in relation to one another, in that the one cover disc comprises at least one centring step, in that the arms, guided on the centring step, are secured to the cover disc and in that the annular disc radially overlaps the stop part and is provided in the overlapping region with axial thrust projections protruding axially to the stop part.

1 9. Friction clutch substantially as described by way of example with reference to Figs. 1-10 or Figs 11 and 12 of the accompanying drawings.