GB2165029A - Torsional vibration damper with expanding ring spring - Google Patents

Abstract

In a torsional vibration damper expanding ring springs are employed wherein the ends 12 facing one another are provided with approximately radially extending force action surfaces 13, thus producing a simple and wear-resistant force transmission from the input and output members. <IMAGE>

Description

SPECIFICATION Torsional vibration damper with expanding ring spring The invention relates to a torsional vibration damper, especially for clutch discs of friction clutches, consisting inter alia of an input part provided with friction linings and an output part provided with a hub, where the input part and the output part are rotatable in relation to one another about a common axis against spring means in both directions of rotation, starting from the state of rest, and this spring means consists at least of an expanding ring spring of substantially annular form which is arranged approximately concentrically with the axis of rotation and can be subjected to expanding stress in the end regions facing one another.

A torsional vibration damper with an expanding ring spring of the style of construction as stated above is known for example from German Publication Specification No. 2,907,045. In this known torsional vibration damper in idling operation an expanding ring spring is active the two end zones of which, facing one another, are angled off in different axial directions and are hooked with these angled-off zones into components which are rotatable in relation to one another.

Now it is the problem of the present invention to produce an arrangement which renders possible the use of expanding ring springs to a greater extent in torsional vibration dampers, but in which the springs can be produced as simply as possible, occupy minimum axial construction space and are especially durable.

In accordance with the invention this problem is solved by the characteristic of the Main Claim. Due to the flat formation of the expanding ring spring it can be accommodated in an especially space-saving manner, and due to the arrangement of the force action surfaces between the end zones facing one another and the counter-pieces substantially radially, favourable engagement conditions are provided at the contact position for the introduction of the torque, so that expanding ring springs can also be designed for higher torques such as occur for example in the under-load stages of torsional vibration dampers. It can here be provided by way of example for the enlargement of the force action surfaces that the ends of the expanding ring spring are deformed in a radial direction so that the force action surfaces become larger than the pure cross-section of the expanding ring spring.The surfaces can here be formed swarflessly or machined by cutting.

The counter-pieces likewise comprise force action surfaces for engagement with the force action surfaces of the expanding ring spring, and these are formed on axially extending sheet metal tabs, rivet bolts or radial elevated portions. These force action surfaces also extend substantially radially in order to reduce the pressure per unit area in the torque transmission to a minimum.

Advantageous developments of the rivet bolts are reproduced in Sub-Claims 4 and 5.

The guidance of the expanding ring spring radially inwards takes place preferably at least on part of an annular surface. This can be formed as a radially outwardly open annular groove for example in the hub disc. This annular groove can however in principle also be formed by a surrounding bead of a cover plate.

An outward guidance of the expanding ring spring is advantageously to be provided in the regions which, starting from the force action surfaces in the state of rest, reach by a safety distance further in the circumferential direction than the maximum angle of rotation in each case in this direction of rotation. Thus it is guaranteed that the expanding ring spring cannot shift in the radial direction away from the force action surfaces of the counter-pieces, and at the same time it is ensured that it can move radially freely in the regions diametrically opposite to the force action surfaces.

In an especially advantageous manner in each case two expanding ring springs can be arranged one beside the other in such manner that they are mutually staggered by 1800, whereby the counterpieces are also staggered by 1800, so that during operation no outward unbalance can occur due to the radial shift of the expanding ring springs.

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

Individually: Figures 1 and 2 show a partial section and a longitudinal section through a clutch disc; Figures 3 and 4 show a partial and a longitudinal section through a clutch disc in which the upper half differs constructionally from the lower half; Figure 5 shows a special form of embodiment of an expanding ring spring; Figure 6 shows a longitudinal section through a clutch disc with torsional vibration damper for the underload range and for the idling range.

Figures 1 and 2 show a partial section I - I and a longitudinal section II - II through a clutch disc with torsional vibration damper. The friction linings 1, which are firmly connected through spring segments 2 with a lining carrier 3, serve as input part of the torsional vibration damper. The output part is represented by the hub 8 which is fitted by means of an internal splining fast in rotation on a gear input shaft (not shown). The hub 8 is connected through connection rivets 41 with two cover plates 5 and 6 which are held spaced in the axial direction. The lining carrier 3 is situated axially between these two cover plates 5 and 6 and can be rotated in relation to the hub 8 against the force of a conventional friction device 9 and against the resilient force of two expanding ring springs 10.The two expanding ring springs 10 are arranged each in a plane parallel to the lining carrier 3 and to each side of this lining carrier 3. They are guided according to Figure 2 in the axial direction, in the state of rest of the clutch disc by the lining carrier 3 for the one part and by the corresponding cover plate 5 or 6. Guidance in the radial direction is achieved in that each of the two cover plates 5 and 6 forms an all-round bead 43 which, in the radially outer region of the cover plates, is set out pointing in the axial direction away from the lining carrier 3, and thus is adapted to the rest position, arranged concentrically with the rotation axis 25, of the annular expanding ring springs 10. The two expanding ring springs are installed staggered by 1800 in relation to one another, and are actuated as follows.The end zones facing one another are provided with force action surfaces 12 which have a spacing from one another and are arranged radially, so that the imaginary prolongations extend approximately through the axis 25 of rotation. Each of the cover plates 5 and 6 has in the region between these force action surfaces 12 an axially bent-over tab 20 which rests with its force action surfaces 14 parallel on the force action surfaces 12 of the expanding ring springs 10. Furthermore on each side of the lining carrier 3 retaining parts 27 are arranged offset through 1800 thereon, which possess tabs 19 pointing axially away from the lining carrier 3, which likewise act with their force action surfaces 15 upon the force action surfaces 12 of the expanding ring springs 10.The retaining parts 27 are firmly connected for example through rivets 28 with the lining carrier 3. As may be seen clearly from both Figures, the tabs 19 and 20 act respectively on the upper and lower half of the force action surface 12 of the expanding ring springs 10. In the present case the expanding ring spring 10 is equipped with a round cross-section.

However it is readily possible to make this crosssection rectangular or square. On introduction of torque into the clutch disc from the friction linings 1, for example in the clockwise direction according to Figure 1, the force action surface 12 of the expanding ring spring 10 arranged to the left of the section line II - II is loaded and it departs together with the retaining part 27 in the clockwise direction from the tab 20, which is regarded together with the hub 8 as stationary. The torque is transmitted through the two expanding ring springs 10, namely from the retaining part 27 through the springs to the opposite ends of the tabs 20. Each of the two expanding ring springs 10 wil( here yield radially outwards in the region opposite to the force action surfaces 12.In this case the two expanding ring springs 10 are radially outwardly secured in that the retaining part 27 has, outside the tabs 19 in the circumferential direction, an axially bent-over marginal portion 29 which extends radially closely outside the external contour of the expanding ring springs 10. The circumferential extent of this margin 29 on each side of the retaining part 27, seen in the circumferential direction, is here greater by a certain distance than the maximum angle of rotation between the retaining part 27 or between the lining carrier 3 and the hub 8. Thus the expanding ring springs 10 are guided in the radial direction in the region of their force action surfaces 12 even at maximum angle of rotation.The arrangement of two expanding ring springs 10 side by side renders possible the transmission of great torques, while their arrangement turned through 1800 renders possible a compensation of want of balance under torque loading. A reversal of loading in the counter-clockwise direction takes place analogously with the above description, since all components are arranged symmetrically, in relation to a longitudinal section through the clutch disc.

A variant of embodiment of a torsional vibration damper is laid down in Figures 3 and 4. In the case of this construction, constructive differences are provided in each case between the upper half and the lower half of the illustration. For the sake of simplicity the two constructions have been combined in one drawing. Figure 3 shows the section lil - lil according to Figure 4 and Figure 4 shows the section IV - IV according to Figure 3. In principle the present construction has the following assembly : The lining carrier 3 with the spring segments 2 and the friction linings 1 serves in the present case as one of two cover plates, while the second cover plate 4 is arranged with axial spacing from the lining carrier 3 and is connected fast in rotation with the latter and held spaced, inter alia through rivet bolts 30.Between the lining carrier 3 and the cover plate 4 the hub disc 7 of the hub 8 extends in radial direction. Furthermore a conventional friction device 9 is provided between the lining carrier 3 or cover plate 4 for the one part and the hub disc 7 for the other. So much for the principle of assembly of both the upper and the lower half of the illustrations. In the upper half now the hub disc 7 is made widened in the axial direction and it comprises two annular grooves 21 in which the two expanding ring springs 10, arranged side by side, are fixed in their rest position. The two annular grooves 21 have in a specific region according to Figure 3 a radial elevation 22, whereby they form force action surfaces 23 against which the expanding ring springs 10 bear with their force action surfaces 12.This abutment can take place in the state of rest of the torsional vibration damper with or without initial stress. The radial elevation 22 is made somewhat iess than half of the cross-sectional height of the expanding ring springs 10 and of the force action surfaces 12. In the region radially outside this radial elevation 22 of the hub disc 7 there is provided in each case an axially angledoff tab 18 of the lining carrier 3 and of the cover plate 4. These tabs 18 have force action surfaces 24 which likewise correspond with the force action surfaces 12 of the expanding ring springs 10. in the present construction when the torsional vibration damper is in the rest position the force action surfaces 23 and 24 lie against the force action surfaces 12. As may further be seen from the upper halves of the two Figures, the expanding ring springs 10 are radially outwardly guided by sleeves 31 which surround the rivet bolts 30. Thus a lowfriction supporting of the expanding ring springs 10 under torque loading is achieved. The rivet bolts 30 are here situated at an angular distance from the force action surfaces 12 which is somewhat greater than the maximum angle of rotation in both directions of rotation.

On torque loading through the friction linings 1 the tabs 18 will act with their force action surfaces 24 upon the corresponding force action surfaces 12 of the expanding ring springs 10 and will carry out a relative rotation in relation to the hub disc 7 in the loading direction with the loaded expanding ring spring ends. Such a rotating movement can easily be derived especially from Figure 3. The right end regions of the expanding ring springs 10 in this way will move together with the tabs 18 in the direction towards the right sleeve 31, while the left end regions remain stationary due to the abutment on the force action surfaces 23 of the hub disc 7. In their middle region the expanding ring springs 10 can yield in the radial direction.

In both Figures a somewhat modified construction is represented in the lower half. In place of the solid hub disc 7 here individual disc parts 44 and 45 are firmly connected with the hub 8 through connecting rivets 42. The two disc parts 45 are held axially spaced in their radially outer region, namely by insertion of a rivet bolt 16. This rivet bolt 16, as may be seen especially from Figure 3, is provided with substantially parallel force action surfaces 14 and possesses a substantially square or rectangular cross-section. Directly radially above the rivet bolt 16 at a short distance therefrom a rivet bolt 17 is arranged which however is inserted into the lining carrier 3 and into the cover plate 4.

It likewise has a square or rectangular cross-section and forms force action surfaces 15. The force action surfaces 14 and 15 correspond with the force action surfaces 12 of the expanding ring springs 10, when the torsional vibration damper is in the rest position. The guidance of the expanding ring springs 10 is effected in the present case through a plurality of rivet bolts 33 distributed in a circle, and the diameter of a surrounding circle externally tangential to the rivet bolts 33 corresponds approximately to the internal diameter of the unloaded expanding ring springs 10. For radial guidance two rivet bolts 32 are provided which are arranged with spacing from the rivet bolts 16 in the disc parts 44 and 45, which spacing is somewhat greater than the maximum possible angle of rotation.

Here again the function can be seen easily especially by reference to Figure 3. On introduction of torque from the friction linings 1 the rivet bolt 17 with the corresponding ends of the expanding ring springs 10 moves out in the corresponding direction of rotation in relation to the rivet bolt 16. On change of the direction of loading the opposite force action surfaces 12 of the expanding ring springs 10 will be loaded and pivoted.

In Figure 5 there is reproduced the lateral elevation of a single expanding ring spring 11. This expanding ring spring 11, which can equally well have a round or a rectangular or square cross-section, is angled off radially outwards in hook form in the end zones facing one another, in order in this way that the force action surfaces 12 may be of larger formation compared with the pure crosssection of the spring material. The hooks 13 of the expanding ring spring 11 can be formed either cold or hot. The manner of production will be determined according to the size of the spring and its cross-section. The force action surfaces 12 can here be worked swarflessly or with swarf removal.

An embodiment according to this Figure 5 will be appropriate especially in the case of high forces, for the reduction of the pressure per unit area, in relation to the components which introduce the force.

In Figure 6 there is represented the longitudinal section of a torsional vibration damper in which a conventional torsional vibration damper 35 is provided for the under-load range and a separate torsional vibration damper 40 is provided for the idling range.

Constructions of this kind are known in principle.

In the present case the torsional vibration damper 40 for the idling range is equipped with an expanding ring spring 10. Starting from a conventional torsional vibration damper 35 for the under-load range with several torsion springs 36 distributed on the circumference and a first hub 37, in this construction it is provided that this first hub 37 is provided facing the second hub 38 with a toothing 39 which has play in the circumferential direction, according to the angular range of effect of the torsional vibration damper 40. The second hub 38 is secured in the conventional manner by way of a toothing on a gear input shaft (not shown).Laterally beside the torsional vibration damper 35 the torsional vibration damper 40 is arranged in such a way that its two cover plates 3 and 4 are firmly connected with one another through distance rivets 34 or a rivet bolt 17 and the one cover plate 3 is firmly connected with the first hub 37. Between the two cover plates 3 and 4 a hub disc 7 extends in radial direction, which is arranged with its internal circumference firmly on the second hub 38.

This hub disc 7 is made in principle like the hub disc 7 in the upper half of Figure 3. It has an annular face 26 which extends concentrically with the rotation axis 25, as is also the case in Figure 3.

When the torsional vibration damper 40 is in the rest condition the expanding ring spring 10 extends concentrically about the annular face 26 and rests on it, or is at a slight distance only from it. In the region of the two free ends of the expanding ring spring 10 the hub disc 7 has a radial elevation 22 which forms force action surfaces 23. The force action surfaces 12 of the expanding ring spring 10 bear against these force action surfaces 23. The radial extent of the elevation 22 is now somewhat less than as far as the centre line of the force action surfaces 12. Radially outwards the radial elevation 22 is adjoined by a rivet bolt 17 having force action surfaces 15, as represented by way of example in Figure 3, lower half. These force action surfaces 15 correspond with the radially outwardly situated halves of the force action surfaces 12 of the expanding ring spring 10.

The function of the torsional vibration damper 40 according to Figure 6 is as follows : - The torsional vibration damper 40 is effective within the fixed angle of rotation of the toothing 39. The torque transmission in this case takes place by way of the two cover plates 3 and 4 to the rivet bolt 17 and thence by way of one of the two force action surfaces 12 to the expanding ring spring 10. The opposite force action surface 12 in each case is supported on the corresponding force action surface 23 of the radial elevation 22, and thus transmits the torque to the second hub 38. The guidance of the expanding ring spring 10 can be made in accordance with one of the constructions described previously.

The advantages achieved with the proposed constructions are to be seen in that with the aid of expanding ring springs large angles of rotation can be realised without need to attenuate the cover plates or hub discs by excessively large windows such as would be necessary when using conventional helical compression springs. Furthermore a low pressure per unit area can be achieved by the force introduction as described and the formation of the force action surfaces, whereby the construction is made durable. Moreover better utilisation of space is possible compared with conventional torsional vibration dampers, since firstly the intermediate pieces otherwise necessary between compression springs can be eliminated and also for example the expanding ring springs can be arranged radially one above the other. The distance rivets provided between the cover plates can be used at the same time as radial guidance for the expanding ring springs.

Claims (14)

1.) Torsional vibration damper, especially for clutch discs of friction clutches, consisting of an input part provided with friction linings and an output part provided with a hub, input part and output part being rotatable in relation to one another about a common axis against spring means in both directions of rotation starting from the condition of rest while this spring means consists at least of an expanding ring spring of substantially annular form which is arranged approximately concentrically with the rotation axis and is subjectable to expanding stress in the end zones facing one another, characterised in that the expanding ring spring (10, 11) is made flat and the force action surfaces (12, 14, 15, 23, 24) between the end zones facing one another and the counter-pieces (3, 4, 5, 6, 7) are arranged substantially radially and their imaginary prolongations pass approximately through the axis (25) of rotation.

2.) Torsionai vibration damper according to Claim 1, characterised in that the force action surfaces (12) of the expanding ring spring (11) are enlarged in the radial direction beyond the extent of the pure material cross-section by at least partial hook-shaped deformation of the spring ends (13) radially outwards.

3.) Torsional vibration damper according to Claim 1 or 2, characterised in that counter-pieces (3, 4, 5, 6, 7) provided with force action surfaces (14, 15) are equipped with axially extending sheet metal tabs (18, 19, 20), rivet bolts (16, 17) or radial elevations (22).

4.) Torsional vibration damper according to Claim 3, characterised in that the rivet bolts (16, 17) are flattened off to form the force action surfaces (14, 15).

5.) Torsional vibration damper according to Claim 4, characterised in that the rivet bolts (16, 17) have preferably approximately square crosssection.

6.) Torsional vibration damper according to one of Claims 1 to 5, characterised in that the expanding ring spring (10, 11) is guided radially inwards, in the rest condition, preferably at least on a part of an annular surface (26).

7.) Torsional vibration damper according to Claim 6, characterised in that the annular surface is part of a radially outwardly open annular groove (21).

8.) Torsional vibration damper according to Claim 7, characterised in that the annular groove (21) is part of a hub disc (7) and force action surfaces (23) for the expanding ring spring (10) are formed by a radial elevation (22) in the region deviating from the annular surface.

9.) Torsional vibration damper according to Claim 7, characterised in that the annular groove is formed at least by a cover plate (5, 6) provided with a surrounding bead (43).

10.) Torsional vibration damper according to one of Claims 1 to 9, characterised in that the guidance of the expanding ring springs (10, 11) takes place radially outwards in the region of its force action surfaces (12) through axially extending limiting elements (29, 30, 31, 32) which, starting from the force action surfaces in the state of rest, reach further by a safety interval in the circumferential direction than the maximum angle of rotation in each case in this direction of rotation.

11.) Torsional vibration damper according to one of Claims 1 to 10, characterised in that several expanding ring springs are arranged side by side.

12.) Torsional vibration damper according to Claim 11, characterised in that preferably two like expanding ring springs are provided side by side, the two springs and the corresponding counterpieces being arranged turned in relation to one another by 180 .

13.) Torsional vibration damper according to one of Claims 1 to 10, characterised in that several expanding ring springs are arranged radially one above another.

14.) Torsional vibration damper, as claimed in Claim 1, substantially as described herein with reference to and as illustrated by any one of the examples shown in the accompanying drawings.