Clutch Disc

The invention relates to a clutch disc for a motor vehicle friction clutch which comprises a torsional vibration spring means and a torsional vibration friction damper.

The friction torque of the friction damper of conventional clutch discs is greatly dependent upon the manufacturing tolerances of the individual components and the spring force tolerances of the stressing spring of the friction damper, and can fluctuate greatly. On the other hand the friction torque must be maintained within narrow tolerance limits if rotating vibrations are to be optimally damped. In conventional clutch discs with a friction damper arranged in protected manner between axially lateral side parts, the clutch disc must be dismantled and re-fitted after working, if the friction torque does not lie within the required tolerance limits.

From German Pat. No. 688,630 a clutch disc for a motor vehicle friction clutch is known, on the hub of which a friction lining carrier is mounted rotatably through a limited angle of rotation. A torsional vibration spring means is arranged in the torque transmission path between the hub and the friction lining carrier. The known clutch disc further comprises a torsional vibration friction damper having a plurality of mutually independently adjustable friction units. Each of the friction units comprises friction discs abutting externally on a disc of the friction lining carrier. The friction discs are seated in openings of side discs of the hub which are arranged axially to both sides of the friction lining carrier disc. A likewise externally arranged helical compression spring stresses the friction discs towards one another. The stress force of each spring is adjustable by means of a nut and a clamp bolt axially penetrating the clutch disc. The friction damper of this known clutch disc is unprotected, so that the friction torque can vary in operation. Furthermore it is difficult to monitor whether the friction units are adjusted uniformly. Friction units adjusted to excessive spring stress wear prematurely, which shortens the life of the clutch disc. Finally the axial overall height of the clutch disc is relatively great.

It is an object of the invention to provide a clutch disc for a motor vehicle friction clutch, the torsional vibration friction damper of which can be adjusted to predetermined friction torque values, particularly without variation of its spring stress.

The invention is based upon a clutch disc, the torsional vibration friction damper of which comprises at least two friction elements or friction faces lying axially resiliently flat against one another. One of the friction elements is connected non-rotatably with the hub of the clutch disc and the other friction element is connected non-rotatably with the friction lining carrier thereof. The above problem is solved in accordance with the invention in that one of the friction elements is held adjustably movably along the friction surface of the other friction element on the hub or the friction lining carrier in such a way that the friction area overlapped by the friction elements is adjustable radially in relation to the rotation axis. The effective friction face region is displaced radially by the adjustment, whereby the friction torque varies with the stress spring force and thus friction force remaining constant.

By a friction element there is to be understood here and below any component generating a friction torque, with or without lining of a special friction material. More especially, it should be emphasized that at least one of the friction elements can also be formed by a construction component of the clutch disc, by way of example by a substantially radially protruding hub flange of the hub, or one of the side discs of the friction lining carrier.

The hub and the friction lining carrier ordinarily comprise disc parts arranged axially side-by-side which are utilized for the axial and/or radial mounting of the friction lining carrier on the hub. With only comparatively low constructional expense it is possible to make the friction torque of the friction damper adjustable if one of the two friction elements lying flat against one another is formed as a friction segment and guided non-rotatably but radially displaceably on one of the disc parts or a thrust ring connected non-rotatably with it. The friction damper can be assembled exclusively with use of such radially adjustable friction segments; it can however also comprise conventional non-adjustable friction damper units to which an additional adjustable friction segment is allocated.

The radially displaceable friction segment can carry a protuberance which is guided in a radial slot of the disc part or of the thrust ring connected non-rotatably with it. The slot ensures the non-rotatable coupling of the friction segment with the hub or the friction lining carrier and can furthermore be utilized for the radial fixing of the friction segment. By way of example the protuberance can be formed as an angled tab which is angled off in relation to the slot edges. Alternatively the protuberance can also be fixed by other methods after the adjustment of the friction torque, for example by adhesion or welding. Finally in the longitudinal direction of the slot detent elements can be provided on which the friction segment can be detained.

Particularly in the last-mentioned embodiment with friction segments detainable on the slot edges, an extensive simplification of the friction damper can be achieved if as detent element there is utilized an arched spring which at the same time takes over the function of the stressing spring and not only detains the detent segment on the detent elements of the slot but also stresses it axially towards the other friction element of the friction damper.

In some practical cases the range in which the friction torque can be varied by radial displacement of the friction segment does not suffice for the compensation of the friction torque error caused by tolerance fluctuations. The torque adjustment range is increased if in addition to the effective friction force radius the stress force of the stressing spring of the friction damper is also adjusted. This can be achieved in a simple manner in that the hub flange and at least one of the side discs of the friction lining carrier are inclined radially outwards towards one another and form between them a radially outwardly narrowing gap in which the friction element is radially displaceably guided. The friction element is seated in the stress force path of the stressing spring and reduces the axial installation height available for the stressing spring, with decreasing axial width of the gap. By displacement of the friction segment radially outwards, not only the friction force radius but also the stress force of the stressing spring is increased. The stressing spring can be arranged together with the friction segment in the gap, but it can also be arranged on the axially opposite side of the hub flange and can be supported through the friction lining carrier on the friction segment.

In another embodiment the friction segment is on the one hand displaceably guided along a spiral groove wound about the rotation axis, and on the other hand guided radially displaceably on a radial guide connected non-rotatably with one of the disc parts. The distance from the rotation axis effective for the friction torque can be adjusted by rotation of the radial guide in relation to the spiral guide groove. The spiral guide groove can contain several friction segments which are adjusted simultaneously and in common in a predetermined manner.

Friction dampers with a friction face of comparatively large area but nevertheless radially adjustable are obtained if at least one of the two friction elements lying flat against one another is formed as a friction ring enclosing the rotation axis and is guided non-rotatably but axially displaceably on one of the disc parts. The friction ring is mounted rotatably on a radially eccentric ring. The eccentric ring is in turn held non-rotatably but rotationally adjustable about the rotation axis of the clutch disc, particularly on the hub. By rotation of the eccentric in relation to the hub, the area center of gravity of the friction ring is radially displaced and thus the friction torque is varied. This embodiment has the advantage that it is relatively insensitive to centrifugal forces and can easily be secured against unintended shifting.

In an embodiment in which the two friction elements lying flat against one another have elongated friction faces extending at an angle to one another, similar advantages are obtained, if one of the friction elements is guided non-rotatably but rotatably adjustable about the rotation axis either on the hub or the friction lining carrier. By rotation of the two friction faces in relation to one another about the rotation axis it is possible to adjust the distance of the effective, overlapped friction face region from the rotation axis and thus the friction torque.

In such a friction damper the friction torque varies even during damping operation in dependence upon the angle of rotation of the friction lining carrier in relation to the hub. In so far as the dependence of the friction torque upon the rotation angle is undesired, by suitable dimensioning of the friction damper for small maximum relative rotation angles it is possible to achieve the object that the friction torque varies only within the permissible tolerance range.

The friction elements are preferably formed as friction rings with radial distance from the rotation axis varying in the circumferential direction, and preferably have a substantially elliptical form.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention .

In the drawings:

FIG. 1 shows an axial longitudinal section through a clutch disc with a torsional vibration spring means and an adjustable torsional vibration friction damper for a motor vehicle friction clutch;

FIG. 2 shows an axial longitudinal section through a friction damper with steplessly adjustable, radially guided friction segment, usable in the clutch disc according to FIG. 1;

FIG. 3 shows an axial cross-section through the friction damper seen along a line III--III in FIG. 2;

FIG. 4 shows an axial longitudinal section through a variant of the friction damper according to FIG. 2, in which the force of a stressing spring is additionally adjustable;

FIG. 5 shows an axial longitudinal section through a friction damper adjustable in steps and usable in the clutch disc according to FIG. 1;

FIG. 6 shows a lateral elevation of the friction damper seen along a line IV--IV in FIG. 5;

FIG. 7 shows a detail view of a friction segment of the friction damper seen along a line VII--VII in FIG. 6;

FIG. 8 shows an axial longitudinal section through a friction damper usable in the clutch disc according to FIG. 1, the friction segment of which damper is guided radially displaceably in a groove of spiral form;

FIG. 9 shows an axial cross-section through the friction damper seen along a line IX--IX in FIG. 8;

FIG. 10 shows an axial longitudinal section through a friction damper usable in the clutch disc according to FIG. 1, the friction ring of which damper is radially displaceable;

FIG. 11 shows an axial cross-section through the friction damper seen along a line XI--XI in FIG. 10;

FIG. 12 shows an axial longitudinal section through a friction damper with elliptical friction elements, usable in the clutch disc according to FIG. 1; and

FIG. 13 shows an axial cross-section through the friction damper seen along a line XIII--XIII in FIG. 12.

FIG. 1 shows the fundamental construction of a clutch disc for a motor vehicle friction clutch. The clutch disc comprises a hub 1 of substantially sleeve form which is couplable to its internal toothing 3 non-rotatably but axially displaceably with an input shaft (not shown further) of a motor vehicle gear, rotatable about a rotation axis 5. A friction lining carrier 7 is mounted rotatably through a limited rotation angle about the rotation axis 5 on the hub 1. The friction lining carrier 7 comprises two side discs 9, 11 formed as sheet-metal-shaped parts of substantially annular disc form which are firmly connected with one another with axial spacing from one another by distance rivets 13 or the like. A driver disc 17 likewise of annular disc form in turn carrying clutch friction linings 19 on both axial sides is secured with rivets 15 to the external circumference of the side disc 11. A hub flange 21 of disc form protruding substantially radially from the hub 1 extends axially between the side disc 9, 11. The distance rivets 13 pass through apertures 23 on the circumference of the hub flange 21 and limit the angle of rotation of the friction lining carrier 7 in relation to the hub 1.

On the side discs 9, 11 and the hub flange 21 there are provided windows 25, 27 and 29 respectively, substantially axially aligned with one another when the clutch disc is in the rest position, in which windows helical compression springs 31 are seated. The helical compression springs 31 are subjected to compression stress in the relative rotation of the friction lining carrier 7 and the hub 1 and form a torsional vibration spring means. FIG. 1 shows only one of several helical compression springs 31 arranged in distribution in the circumferential direction.

An adjustable torsional vibration friction damper, explained in greater detail below in various embodiments, is arranged at 33 in FIG. 1. The friction torque of the friction damper 33 is adjustable when the clutch disc is assembled, in order that component tolerances of the clutch disc may be compensated. For this purpose the friction damper 33 comprises friction elements, the radial position of which is adjustable in relation to one another.

In the following explanation of different embodiments of friction dampers, components which have been explained by reference to the clutch disc according to FIG. 1 are designated by the same reference numerals and additionally by a letter. For more detailed explanation of the components designated with the same reference numerals, reference will be made to the description of FIG. 1.

FIGS. 2 and 3 show a friction damper 33a, the friction torque of which is adjustable within predetermined limits, without variation of its spring stress, with the clutch disc assembled. The friction lining carrier 7a is guided rotatably but axially movably on the hub 1a by means of its side disc 9a. The side disc 11a is connected into one unit with the side disc 9a by means of the distance rivets 13a. A thrust ring 35 carrying tongues 37 pointing axially away from the hub flange 21a on its internal circumference is arranged axially between the hub flange 21a and the side disc 11a. The tongues 37 engage in apertures 39 on the internal circumference of the side disc 11a and guide the thrust ring 35 non-rotatably but axially displaceably on the side disc 11a. A friction ring 41 is arranged axially between the thrust ring 35 and the hub flange 21a. A dished spring 43 is braced in axially between the side disc 11a and the thrust ring 35.

A friction segment 45, which is pressed by the dished spring 43 through the side disc 11a, the distance rivets 13a and the side disc 9a against the friction face 47 of the hub flange 21a extending perpendicularly to the axis at least in the region of the friction segment 45, is arranged axially between the hub flange 21a and the side disc 9a. In order that the mean friction force radius of the friction segment 45 may be adjusted, the friction segment 45 is guided non-rotatably but radially displaceably on the side disc 9a. For this purpose, in the side disc 9a there is provided a radially extending slot 49 through which an offset tab 51 protruding axially on the side of the friction segment 45 remote from the hub disc passes and is angled off on the side of the side disc 9a axially remote from the hub flange 21a, in the position of the desired friction torque, for the radial fixing of the friction segment 45.

In FIG. 2 only one friction segment 45 is represented; alternatively it is also possible to provide several friction segments offset in relation to one another in the circumferential direction and/or radially. Each friction segment can be guided on several angled-off tabs and possibly several slots of the side disc 9a.

FIG. 4 shows a friction damper 33b which differs from the friction damper 33a only in that its friction face 55, corresponding to the friction face 47 of the friction damper 33a, and the side disc 9b extending in a plane perpendicular to the axis form a radially outwardly narrowing gap 57 in which a friction segment 59 likewise of wedge form is radially displaceably guided. The friction segment 59 carries again an angled-off tab 61 on its side axially remote from the hub flange 21b which tab engages through a radial slot 63 of the side disc 9b and can be offset on the outside of the side disc 9b. The effective friction force radius and thus the friction torque can be adjusted by means of the friction segment 59 guided non-rotatably but radially adjustably on the side disc 9b.

In dependence upon the radial position of the friction segment 59, the axial position of the side disc 9b and of the side disc 11b secured thereto through the distance rivets 13b from the hub flange 21b varies. There is corresponding variation of the installation height of the dished spring 69 braced in by means of the thrust ring 65 and a friction ring 67 on the hub flange 21b for the one part and the side disc 11b for the other. With increasing effective friction force radius of the friction segment 59, the installation height of the dished spring 69 decreases and thus so does its initial stress force, increasing the friction torque.

FIGS. 5 to 7 show a friction damper 33c with friction torque adjustable in steps. The side discs 9c and 11c of the friction lining carrier 7c are connected into one unit by distance rivets 13c and guided rotatably on the hub 1c on both sides of a hub flange 21c protruding radially from the hub 1c. The hub flange 21c has friction faces 71, 73 extending normal to the axis on axially opposite sides, on which friction segments 75, 77 rest flat. The friction segments 75, 77 each carry arched springs 79 and 81 on their side axially remote from the hub flange 21c. The arched springs 79, 81 engage through radially extending slots 83 and 85 respectively, of the side discs 9c, 11c and guide the friction segments 75, 77 non-rotatably but radially adjustably on the side discs 9c, 11c.

FIGS. 6 and 7 show details of the fixing and guidance of the friction segments 75, 77 for the friction segment 75. The radial longitudinal edges of the slot 83 are provided with a plurality of cut-out portions 87 arranged in the radial direction at distance from one another, in which the two circumferentially resilient legs 89, 91 of the arched spring 79, arranged with spacing from one another in the circumferential direction, engage and detain the friction segment 75 on the side disc 9c.

In the region of the radial longitudinal edges of the slot 83 the legs 89, 91 converge on one another away from the hub flange 21c. Thus the arched springs 79 and 81 generate stress forces directed axially towards one another which press the friction segment 75, 77 against the friction faces 71, 73. An additional stressing spring is not necessary. By compression of the legs 89, 91 in the circumferential direction, the detent engagement can be released and the effective friction force radius and thus the friction torque can be adjusted.

FIGS. 8 and 9 show a friction damper 33d having a plurality of friction segments 95 adjustable in common in a predetermined manner.

The friction lining carrier 7d is guided rotatably but axially displaceably on the hub 1d by means of its side disc 11d. The side disc 9d held by means of distance rivets 13d on the side disc 11d forms an annular gap 97 between its internal circumference and the hub 1d. A friction ring 99 is seated axially between the hub flange 21d and the side disc 11d. The friction segments 95 are clamped in between the face 101 of the hub flange 21d lying axially opposite to the friction ring 99 and a thrust ring 103 arranged axially between the hub flange 21d and the side disc 9d. On its external circumference the thrust ring 103 carries tabs 105 which engage in apertures 107 of the side disc 9d and guide the thrust ring 103 non-rotatably but axially displaceably on the side disc 9d. A dished spring 109 which is supported with its internal circumference through the thrust ring 103 and the friction segments 95 on the face 101 of the hub flange 21d and is supported with its external circumference through the side disc 9d, the distance rivets 13d, the side disc 11d and the friction ring 99 on the axially opposite side of the hub flange 21d is braced in axially between the thrust ring 103 and the side disc 9d.

The friction segments 95 are seated radially displaceably in radial slots 111 of a guide disc 113 arranged axially between the hub flange 21d and the thrust ring 103 and are guided rotatably on the hub 1d. The friction face 101 of the hub flange 21d carries a guide rib 115 of spiral form forming a spiral guide groove 117 between its turns in which the friction segments 95 are displaceable in the circumferential direction. By rotation of the guide disc 111 in relation to the hub flange 21d, the friction segments 95 are displaced along the guide groove 117 and thus radially movably adjusted. The friction torque is also adjusted in accordance with the effective friction force radius of the friction segments 95.

On its internal circumference the dished spring carries detent elements 119 which couple it non-rotatably with the guide disc 113. On the external circumference of the dished spring 109 there are provided detent elements 121 by means of which the dished spring 109 can be detained on the side disc 9d in several angular positions. The detent engagement of the dished spring 109 can be released and the dished spring 109 together with the guide disc 113 can be rotated in relation to the hub 1d for the adjustment of the friction torque, by means of a tool or the like introducible through the annular gap 97.

FIGS. 10 and 11 show a friction damper 33e having a friction ring 125 enclosing the hub 1e, which ring is adjustable through an eccentric drive radially of the friction face 127 normal to the axis, formed by the hub flange 21e.

The friction lining carrier 7e is guided rotatably but axially displaceably on the hub 1e through its side disc 11e. The side disc 9e is secured through the distance rivets 13e to the side disc 11e and forms an annular gap 129 between its internal circumference and the hub 1e. A friction ring 131 is arranged axially between the side disc 11e and the hub flange 21e. The friction ring 125 is secured on its side axially remote from the hub flange 21e to a thrust ring 133. An axially resilient dished spring 135 is braced in axially between the thrust ring 133 and the side disc 9e.

The thrust ring 133 carries two guide tongues 137 lying diametrically oppositely in relation to the rotation axis 5e, which tongues engage in radial slots 139 of the side disc 9e and guide the thrust ring 133 and thus the friction ring 125 non-rotatably but both axially and radially displaceably on the side disc 9e.

The thrust ring 133 has a guide opening 141 arranged eccentrically in relation to the friction ring 125, in which an eccentric ring 143 seated rotationally adjustably on the hub 1e is rotatably guided. The eccentricities of the eccentric ring 143 and the guide opening 141 are dimensioned so that the friction ring 125 is radially displaceable by twice the eccentricity out of the position concentric with the rotation axis 5e by a rotation of the eccentric ring 143 through 180.degree.. By rotation of the eccentric ring 143 by means of a tool or the like introducible through the annular gap 129, the friction ring 125 can be displaced radially and thus the effective friction force radius and the friction torque can be adjusted. After adjustment the eccentric ring 143 is secured against rotation, for example by spot welds 145 or by adhesion or swaging.

FIGS. 12 and 13 show a friction damper 33f in which the friction torque of the friction damper 33f can be adjusted by rotation of two friction elements in relation to the rotation axis 5f.

The friction lining carrier 7f is guided rotatably but axially displaceably on the hub 1f by means of its side disc 11f. The side disc 9f is held on the side disc 11f by distance rivets 13f and forms an annular gap 151 between its internal circumference and the hub 1f. A friction ring 153 is arranged axially between the side disc 11f and the hub flange 21f. A substantially elliptical friction ring 155 is secured on the side of the hub flange 21f axially remote from the friction ring 153. A thrust ring 157, carrying a likewise substantially elliptical ring elevation 159 on its side axially facing the friction ring 155, is guided rotatably but axially displaceably on the hub 1f axially between the friction ring 155 and the side disc 9f. The ring elevation 159 forms a friction face of ring form corresponding as regards the size and ratio of its half axes to the friction ring 155. A dished spring 161 is braced in axially between the thrust ring 157 and the side disc 9f. The dished spring 161 is coupled through detent elements 163 on its internal circumference non-rotatably with the thrust ring 157 and through detent elements 165 on its external circumference non-rotatably with the side disc 9f. The dished spring 161 detains the thrust ring 157 non-rotatably but axially displaceably on the side disc 9f in several angle positions.

By rotation of the thrust ring 157 the elliptical friction face 159 is rotated in relation to the friction ring 155. The rotation axis distances of the overlap zones 166 responsible for the friction torque, and thus the friction torque, vary correspondingly.

The friction torque varies slightly also in the vibration damping operation. If such a variation is undesired the friction torque variation of operation in damping can be kept within predetermined permissible tolerance limits by suitable dimensioning of the friction properties of the friction damper.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.