GB2297602A

GB2297602A - Torsional vibration damper

Info

Publication number: GB2297602A
Application number: GB9601838A
Authority: GB
Inventors: Johann Jaeckel; Albert Birk
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1995-02-03
Filing date: 1996-01-30
Publication date: 1996-08-07
Anticipated expiration: 2016-01-30
Also published as: DE19603248A1; FR2730290B1; BR9600312A; DE19603248B4; RU2190789C2; ITMI960196A1; GB2297602B; ES2134087B1; ES2134087A1; JPH08240244A; IT1282084B1; GB9601838D0; FR2730290A1; ITMI960196A0

Abstract

A composite flywheel has primary and secondary masses(2, 3, Fig 1) rotatable relative to each other against the resistance of a damper having energy storing means 7 including arcuate springs 8, 9, 10 and an abutment 30 between neighbouring end portions, 27, 28, 29 of such springs. The abutment 30 can move in the circumferential direction of the masses (2, 3) and is connected to at least one of the springs in such a way that it will remain attached thereto, for example by engagement in a groove (34, Fig 3) in the abutment 30.

Description

Torsional Vibration Damper The invention relates to a torsional vibration damper with at least two structural elements which are turnable against the resistance of at least one energy storing device and comprise stressing portions for compression of the energy storing device which is constituted by at least one coil spring, at least one of the two end portions of the coil spring cooperating with a spring abutment which is angularly movable or turnable relative to both structural elements and serves as a support for the corresponding end of the spring.

Published German patent application 36 10 127 discloses a torsionally elastic vibration damping clutch which constitutes a twin-mass flywheel wherein torsionally elastic or vibration damping elements are interposed between a primary flywheel mass which can be connected with a prime mover and a secondary flywheel mass which can be connected with a transmission by way of a clutch, the torsionally elastic elements serving to permit angular movements of the two flywheel masses relative to each other. The torsionally elastic elements are constituted by energy storing devices comprising coil springs. These energy storing devices are compressed, in response to angular movement of the two flywheel masses relative to each other, by stressing portions which are provided on the flywheel masses.Cover plates can be provided between the stressing portions and the coil springs to serve as supports for the respective coil springs. The aforementioned publication further proposes to employ, in a so-called twin-mass flywheel, long energy storing devices which are assembled of springs disposed in a chamber one after the other, namely in series. Wedge-like intermediate pieces are provided between the springs which are inserted into a chamber. This publidation does not disclose any further features of the intermediate pieces.

Furthermore, published German patent applications 37 21 711 and 37 21 712 disclose spring cups or supporting pieces for the end portions of long springs. The spring cups or supporting pieces are provided with projections designed in such a way that, in the event of leaving the interior of the end portion of the corresponding spring, the projections can reenter the respective end portion.

Such spring cups can be put to use only in substantially circumferentially complete sockets conforming to the outer diameters of the springs. However, when utilized in conjunction with spring-receiving chambers which do not conform to the outer diameters of the springs and/or which are not substantially complete in the circumferential direction, such spring cups are apt to change their angular positions or to jam to an extent such that they cannot be reintroduced into the corresponding springs which at least interferes with the operation of the damper or of the twin-mass flywheel; in fact, this can even result in destruction at least of the spring cups and/or of the springs.

An object of the present invention is to provide spring cups or spring abutments which render it possible to achieve satisfactory support for the ends of the springs cooperating therewith and to achieve such satisfactory support under all arising operational conditions, and this under a wide variety of circumstances of use and in connection with a wide variety of designs of torsional vibration dampers. Furthermore, one should ensure the possibility of an extremely simple assembly as well as the making of the torsional vibration dampers at a reasonable cost.Furthermore, the novel design of a torsional vibration damper should render it possible to achieve a large number of possible variations, or a large number of possible conformances to the particular use, of the characteristic curve of the torque or the characteristic curve of the resistance to rotation of the two structural elements relative to each other, such torque or resistance to rotation being generated by the energy storing devices, such as coil springs, which oppose rotation of the two structural elements relative to each other. In other words, it should be possible to realize very soft characteristic curves denoting the resistance to rotation, i.e., curves exhibiting a low ratio, and/or multistage characteristic curves donating a resistance to rotation of the structural elements relative to each other.

In accordance with the invention, this is accomplished in that the novel spring abutment, i.e., the novel intermediate piece, is connected against loss with the adjacent end portion of at least one spring. In this manner, one can ensure that the spring abutment invariably remains in an optimum position for the stressing of the spring. For proper positioning and/or securing, the spring abutment, i.e., the intermediate piece, can be provided with at least one shaped portion which overlaps or crosses the neighbouring end portion of the at least one spring, as seen in the direction of the longitudinal axis of the spring.It is of advantage to impart to the shaped portion the configuration of a projection or stud on the spring abutment, i.e., on the intermediate piece, and such projection or stud extends into a space which is defined or surrounded by the corresponding convolutions of the spring. In order to secure it to at least one spring, an abutment or its shaped portion can be provided with one or more configurations or portions which overlie from the outside at least one end convolution or the end portion of a spring to thus secure the abutment relative to the at least one spring.

The novel securing of spring abutments or supporting parts for the coil springs of torsional vibration dampers can be put to use in a particularly advantageous manner when one employs energy storing devices consisting of several coil springs which operate in series and are disposed practically immediately behind one another. Such spring abutments or supporting parts can be installed with advantage between confronting end portions or end convolutions of springs which operate in series. In this manner, one ensures the establishment of a satisfactory support between the series-connected springs and, if necessary, it is further possible to dispose in at least one of the series-connected coil springs an inner coil spring which can also be acted upon by the at least one abutment which acts as an intermediate supporting part.

Additional advantageous design, installation and securing possibilities of the novel spring abutments or intermediate supporting parts, as well as the distribution of coil springs are recited in the claims.

Additional features and advantages of the invention are disclosed in the description of the drawings which follows.

There are shown in: Fig. 1 a section through a novel damping arrangement, Fig. 2 a partially illustrated section taken along the line II - II in Figure 1, Fig. 3 a spring abutment in section, Fig. 4 an end elevational view of that end of a spring which cooperates with the abutment of Figure 3, Fig. 5 a side elevational view as seen in the direction of arrow V in Figure 4, Figures 6 to 9 further possible embodiments of the novel spring abutments and further possible positionings of coil springs which cooperate with the corresponding spring abutments.

The torsional vibration damper a portion of which is illustrated in Figures 1 and 2 comprises a split flywheel 1 which comprises a first or primary flywheel mass 2 adapted to be affixed to a non-illustrated output shaft of a combustion engine as well as a second or secondary flywheel mass 3. The second flywheel mass 3 can be connected, with the interposition of a clutch disc, to a friction clutch which can couple the output shaft with or can disengage the output shaft from a non-illustrated input shaft of a transmission. The flywheel masses 2 and 3 are mounted for rotation relative to each other on a bearing 4 which, in the illustrated embodiment, is disposed radially outwardly of bores 5 for the introduction of fastening screws to mount the first flywheel mass 2 on the output shaft of a combustion engine.A damping arrangement 6 which operates between the two flywheel masses 2 and 3 comprises energy storing devices 7 at least one of which is constituted by pressure coil springs 8, 9, 10. As best shown in Figure 2, the pressure coil spring 9 is received in the space defined by the convolutions 8a of the spring 8 or, otherwise stated, the two coil springs 8 and 9 are interfitted into one another as seen in the longitudinal direction thereof.

In the illustrated embodiment, the angular extension or length 11 of the inner coil spring 9, as seen in the circumferential direction, is less than the extension or length 12 of the outer coil spring 8. It can be of advantage if the inner spring 9 is shorter than the outer spring 8 by a value 13 having a magnitude in the range of between 1 and 5 angular degrees. However, the length differential or the angular differential 13 can also be larger. Furthermore, the springs 8, 9 can have identical lengths , i.e., they can extend along identical angles.

The springs 8, 9 which operate in parallel are installed to operate in series with the coil spring 10. Even though the embodiment which is shown in Figure 2 does not provide an inner spring within the coil spring 10, the provision of such inner spring can be of advantage for many applications. Such inner spring is then received in the spring 10 in a manner similar to that in which the inner spring 9 is installed in the outer spring 8. Furthermore, it can be of advantage for many applications if one provides only the outer spring 8, i.e., if the inner spring 9 is omitted.

The two flywheel masses 2 and 3 comprise stressing portions 14, 15 and 16 for the energy storing devices 7.

In the illustrated embodiment, the stressing portions 14, 15 are formed by embossings in sheet metal parts 17, 18 forming part of the first flywheel mass 2. The stressing portions 16 which are disposed between the stressing portions 14, 15 are formed by at least one flange-like stressing component 20 which is connected to the secondary flywheel mass 3, for example, by rivets 19. This component 20 performs the function of a torque transmitting element between the energy storing devices 7 and the flywheel mass 3. The stressing portions 16 are constituted by radial arms or beams which are provided at the periphery of the flange-like stressing component 20.

The component 20 can be produced as a result of cold forming of metallic sheet material and serves to secure the first flywheel mass 2, i.e., the entire split flywheel 1, on the output shaft of a combustion engine. The radially outer portion of the sheet metal part 17 is connected with the part 18 which also consists of metallic sheet material. The two parts 17, 18 define a ring-shaped space 21 which comprises a toroidal portion 22. The ringshaped space 21 or at least the toroidal portion 22 is at least partially filled with a viscous medium, such as for example grease. As seen in the circumferential direction between the stressing portions or shoulders 14, 15, the parts 17, 18 define recesses which bound the toroidal portion 22 and receive the energy storing devices 7 to guide them not only in the radial but also in the axial direction.At least when the composite flywheel 1 rotates, the convolutions of the springs 8 and 10 abut those portions of the part 17 and/or 18 which are located radially outwardly of the toroidal portion 22. In the illustrated embodiment, there is provided a wear protector 25 which constitutes a hardened intermediate layer of sheet metal or a sheet metal layer which serves as a radial abutment for the springs 8 and 10. The wear protector 25 preferably extends in the circumferential direction at least along the full length or angular distance of the energy storing devices 7 when such devices are in unstressed condition.Due to the abutment of the convolutions of springs 8 and 10 in dependency on the magnitude of the centrifugal force, there develops between such windings and the parts which are in frictional contact therewith a frictional damping action which is a function of the RPM and which arises as a result of a change of the length or compression of the energy storing devices 7 and more specifically of the force storing devices 8 and 10.

The radially inner portion of the radially extending part 17 carries an intermediate portion or hub 26 which confines or carries the inner race of the bearing 4. The outer race of the ball bearing 4 is carried by the flywheel mass 3.

As can be best seen in Figure 2, the angular dimensions of the stressing portions 16 are smaller than those of the stressing portions 14, 15 so that, starting from the theoretical initial position of rest or starting position, the flywheel masses 2 and 3 have freedom of relatively small angular movement relative to each other in both directions without any stressing of the springs.

As can be seen in Figure 2, an intermediate piece 30 is provided between the confronting or neighbouring end convolutions 27, 28 of the springs 8, 9 on the one hand and 29 of the spring 10 on the other hand, and such intermediate piece can be called a spring abutment or spring seat and serves to support the end convolutions 27, 28, 29 or the end portions of the springs 8, 9 and 10.

In the embodiment which is illustrated in Figure 2, the intermediate piece or the spring supporting part 30 comprises a ring-shaped portion 31 against which the springs 8, 9 and 10 abut in the circumferential direction as well as a stud or projection 32 which extends at right angles to the ring-shaped portion 31 and projects into the space which is surrounded by the convolutions 10a, namely into one end portion of the spring 10. In the illustrated embodiment, the supporting part 30 is hollow in that it is provided with a channel 33. As can be seen in Figure 2, the energy storing device 7, i.e., the coil springs 8, 9, 10 which constitute such energy storing device, have end portions which confront the stressing portions 14, 15, 16 and are not provided with any supporting parts or spring sockets.However, it is possible to provide a supporting part or a spring socket at least at one end of each energy storing device 7.

The abutment 30 is connected with the pressure coil spring 10 against loss. To this end, there is provided between the abutment 30 and the spring 10 a form-locking connection which, in the illustrated embodiment and as will be described in greater detail with reference to Figures 3 and 4, constitutes a snap-type connection.

As can be seen in Figure 3, the spring abutment or supporting part 30 comprises or is provided with a configuration or recess established by a ring-shaped groove 34 which is provided in the axial projection 32 immediately adjacent the ring-shaped portion 31. The outer diameter 35 of the projection 32 corresponds at least substantially to the inner diameters 36 of the convolutions 10a of the spring 10 (Figure 4). Preferably, the outer diameter 35 is a little smaller than that portion of the inner diameter 36 which exists at least in the region of the spring end portion confronting the supporting part 30.

As can be seen in Figure 4, the free end portion 37 of the end convolution 29 which is adjacent the supporting part 30 is displaced, namely bent, radially toward the spring axis 38 relative to the other portions of the end convolution 29 of the spring and hence also relative to the spring convolutions 10a. In this manner, one arrives at a reduced width 39 which is less than the inner diameter 36 of the end convolution 29 and of the convolutions 10a, namely less than the outer diameter 35 of the projection 32. During assembly of the spring 10 with the supporting part 30, the projection 32 is pushed into the respective end portion of the spring 10 which, at first, results in a widening of the end convolution 29 so that the distance 39 is increased. Thus, the end portion 37 is pushed radially outwardly.

As soon as the end portion or end section 37 of the convolution 29 reaches the level of the groove or shaped portion 34, the end convolution 29 is free to resile back to its original position so that the distance 39 is then decreased again whereby the end portion 37 moves or snaps radially into the groove 34 to thus hold the supporting part 30 against loss relative to the spring 10. The free end of the projection 32 is provided with a narrowing or taper 39a which facilitates the pushing or pressing of such projection 32 into the confronting end portion of the spring 10. The taper 39a can forcibly shift the end portion 37 radially outwardly.

As can be seen by referring to Figure 5, save for the end portion 37 which extends radially into the groove 34, the slope or helix angle of the end convolution 29 is the same as that of the convolutions l0a which are disposed between the end convolutions of the spring 10. At least when the spring 10 is in unstressed condition, the end portion 37 of this spring 10 extends in parallelism with the supporting surface 31a (Figure 3) of the ring-shaped portion 31, i.e., of the supporting part 30. To this end, and as can be seen in Figure 5, the end portion 37 is bent in the direction of the longitudinal axis 38 of the spring 10 from the position 37a which is shown by broken lines to that position of the end portion 37 which is shown by solid lines.

The end convolution at that end 39b of the spring 10 which is adjacent the stressing portions 14, 15, 16, is ground and abuts, as a result of deformation in the direction of the spring axis 38, the next-to-the-last convolution so that it presents - in a manner known per se - an abutment surface extending at least substantially at right angles to the spring axis 38. Such design of the end convolution is proposed, for example, in the published German patent application 42 29 416. Both end portions of the coil springs 8 and 9 are also provided with similarly flattened end convolutions so that one can ensure a satisfactory stressing of such springs by the stressing portions 14, 15, 16 as well as satisfactory propping of these springs 8, 9 at the ring-shaped portion 31 of the intermediate piece or supporting part 30.

The spring rates or spring stiffnesses of the coil springs 8 and 10 can be same or different. Furthermore, the ratio of the length of the spring 8 or 9 to that of the spring 10 is to be selected in dependency upon the intended use; such length ratio can be in the range of between 0.5:1 and 3:1, preferably in the range of between 1:1 and 2:1.

The utilization of a supporting part 30 exhibits the following advantages: - It is possible to connect in series springs with a large ratio of spring length to spring diameter but to invariably ensure, nevertheless, that the confronting end portions of these springs are properly acted upon, and also to prevent a slipping out or separation of the supporting part 30 from the corresponding spring. Thus, the intermediate piece is invariably stressed in an optimum manner and cannot be destroyed by the springs 8, 10 as a result of inclination between the respective end portions of such springs.

- If one employs at least one inner - spring 9, the latter can be designed to be shorter because, for the purposes of its compression, such spring need not even extend at least a portion of the overall length of the spring 10.

- Still further, intermediate piece 30 renders it possible to employ inner springs having different lengths and/or stiffnesses. Thus, it is possible to provide at least one inner spring also in the interior of the spring 10, and such inner spring can have the same length as, or can be shorter or longer than, the spring 10.

Furthermore, it can be of advantage for numerous applications if, as shown in Figure 6, the intermediate piece 130 comprises a ring-shaped supporting portion 131 from which a projection 132, 132a extends in both axial directions 1, i.e., in both circumferential directions of the apparatus. Owing to such design of the intermediate piece 130, not only the spring 10 can establish a strong connection with the intermediate piece - as seen in the axial direction 38 of an energy storing device 7 - but also the spring 9 so that the springs 8 and 10 are reliably coupled to each other as seen in the circumferential direction of the apparatus 1. Due to such design of the intermediate portion, and when compared with the embodiment which is shown in Figure 2, the length of the inner spring 9 must be made shorter at least by the length or axial extension of the projection 132a.

Furthermore, the projection 132a which is shown in Figure 6 can also be configurated in such a way that it also conforms to the inner spring 9 so that, in such instance, at least the spring 9 is connected with the spring 10.

Still further, and as shown in Figure 7, the intermediate piece 230 can be designed in such a way that it comprises a stepped projection 232a and that each of its steps is provided with a shaped portion or groove 234, 234a to permit entry of at least certain portions of the respective end convolutions of the springs 208, 209.

Owing to such design, one additionally achieves that the inner spring 209 is practically incapable of sliding relative to the outer spring 208 or that the inner spring 209 cannot slide out of the outer spring 208. As indicated in Figure 7 by broken lines, the intermediate piece 230 can also be provided with a projection 232 for a spring 10 of the type shown in Figure 2, and such projection is connected with the spring 10 against loss.

If one employs an inner spring within the spring 10, the projection 232 can also be designed in a manner similar to the design of the projection 232a so that the second inner spring is then also connected with the intermediate piece 230.

In the embodiment which is illustrated in Figure 8 and wherein two outer springs 308, 310 are connected in series with the supporting part 330 inserted between them and wherein an inner spring 309, 309a is provided in the interior of the respective spring 308, 310, the intermediate piece 330 is only hooked into the inner spring 309, i.e., it is connected with the inner spring 309 against loss.

Thus, it is possible to resort to a large number of possible variations regarding the attachment or fixing of an intermediate piece 30, 130, 230, 330 to the springs which are adjacent such intermediate piece, the intermediate piece being connected with at least one of these springs against loss. However, the corresponding intermediate piece can also establish a donnection with several springs or even with all of the springs which are adjacent thereto.

In the embodiment of Figure 9, the spring abutment 430 which is connected with a spring 409 includes a projection 432 with a thread-like profile 434 at its external surface. The end convolutions 409a of the spring 409 are wound in such a way that they can be screwed onto the thread-like profile 434. It is preferred to select the inner diameters of the end convolutions 409a in such a way that they can engage the projection 432 in a radially stressed condition to thus avoid unintentional unwinding of the spring abutment or supporting piece from the end portion of the spring 409.

The embodiment which is illustrated in Figure 2 comprises only two series connected springs. However, it is also possible to connect three or more springs or sets of springs in series, and a discrete novel supporting piece can be provided between each pair of confronting ends of springs or spring sets.

The supporting parts, each of which is connected in accordance with the invention against loss to at least one spring end, can also be provided at those end portions of the corresponding springs which confront the stressing portions 14, 15, 16. For example, and referring to Figure 2, the springs 8 and 10 could be of one piece, i.e., they could constitute a single spring and the supporting part 30 could be provided at the end portion 39b of the spring 10. If the springs 8 and 10 were of one piece, it would also be possible to provide a supporting part of the type shown in Figure 7, 8 or 9 also at the end portion 39a of the spring 8.If the springs 8 and 10 are of one piece, i.e., in the event of the provision of a continuous outer spring between the stressing portions 14, 15, 16 cooperating with such spring, the spring abutment or supporting part 30 of the type shown in Figure 2 can be dispensed with.

As seen in the longitudinal direction of a selected coil spring, the at least one end convolution of such coil spring which is anchored in a spring abutment can also be caused to undergo deformation in the direction of the longitudinal axis 38 of the spring so that it is ground and thus enabled to abut against the next-to-the-last convolution. In this respect, reference was already had to the published German patent application 42 29 416. The inner diameter of the thus designed end convolution is preferably smaller than that of the other convolutions so that it can snap into a groove of the corresponding abutment. Such configuration of a spring convolution 208a is shown in Figure 7.This design of the end portion of a spring renders it possible to ensure that, when the spring is compressed, the area of contact between the spring and the abutment is larger with the result that the force which is generated as a result of compression can be divided along a larger supporting surface of the abutment.

The energy accumulator 507 illustrated in Figure 10 differs from the energy accumulator 7 according to Figure 2 substantially in that a helical spring 509a is housed inside the helical spring 510. The spring 509a is fixedly connected to the spring supporting part 530 at least in the circumferential or axial direction 538 of the energy accumulator 507. As in Figure 2 an outer spring 508 and an inner spring 509 contained therein are provided which are connected in series with the springs 510, 509a.

The inner spring 509a has a substantially higher stiffness than the outer spring 510. Also the length of the inner spring 509a considered in the circumferential direction or longitudinal axial direction 538 of the spring is substantially less than that of the outer spring 510.

The length or angular extension of the unstretched stiff inner spring 509a is selected so that an adequate turning angle of the softer outer spring 510, thus having a lighter spring stiffness is guaranteed before the inner spring 509a is compressed.

As can be seen from Figure 10 as a result of the distance between two adjoining windings, the inner spring 509a, viewed in the direction of the axis 538 of the energy accumulator 507, has a smaller pitch than the outer spring 510. In the illustrated example the spring 509a is designed in relation to the spring 510 so that during turning between the two flywheel masses 2,3 according to Figure 1 the windings of the inner spring 509a become blocked before the windings of the outer spring 510 can become blocked whereby the outer spring 510 is prevented from being overstrained.

The inner spring 509a can however in relation to spring 510 also be designed so that already as a result of the high stiffness or high spring rate of the inner spring 509a the torque which arises with large vibration amplitudes and which can be substantially higher than the nominal torque released by the internal combustion engine, is taken up predominantly resiliently by the inner spring 509a so that the outer spring 510 which is more sensitive regarding blocking strain need only take up a part of this torque. If the inner spring 509a sufficiently dampens or resiliently absorbs the torque shocks a blocking strain of the outer springs 510 can also arise or be taken into consideration.

In a modification to the embodiment shown in Figure 10 the inner spring 509a, viewed in the axial direction 538 of the energy accumulator 507, can also have a greater winding pitch than the outer spring 510.

It is advantageous if the pitch of the windings of the inner spring 509a is directed opposite that of the windings of the outer spring 510. When looking in the same axial or circumferential direction of the energy accumulator 507 this thus means that the windings of one spring are wound in the clockwise direction with a corresponding pitch whilst the windings of the other spring are wound in the anti-clockwise direction with a corresponding pitch.

The turning angle between the two flywheel masses 2,3 through which the two springs 509a and 520 are connected in parallel can be in the order of between 5 and 20 degs.

This angle can however depending on the type of use be even greater and in extreme cases the inner spring 509a can also be only slightly shorter than the outer spring 510 as is the case for example in Figure 2 for springs 8,9. However the inner spring 509a is preferably to prevent an overstraining of the windings of the outer spring 510 wherein at least one of the two springs 509a,510 becomes blocked. The outer spring 510 can have a spring rate which is such that it produces between the relatively rotatable component groups 2,3 a turning resistance which is in the order of 0.5 to 4 No/0. The turning resistance produced by the spring 509a can be in the order of between 20 and 80 No/0. These values can however also be smaller or greater.Preferably however the inner spring 509a will have a stiffness which produces between the two structural groups 2,3 a turning resistance in the order of 20 to 50 No/0.

The spring 508 which is connected in series with the spring 510 can have a stiffness which is equal to, smaller or preferably larger than that of the spring 510. The stiffness of the spring 509 can in turn be equal to, larger or smaller than that of the spring 508.

With the energy accumulator 507 shown in Figure 10 the coaxially arranged springs 509a, 510 are connected in series with the likewise coaxially arranged springs 508, 509. The method of operation described in connection with springs 509a and 510 can however also be used for energy accumulators which only consist of two coaxially arranged and interfitted springs. This means that in Figure 10 the coil spring 510 would be stretched over the entire length of the energy accumulator 507 wherein the inner spring 509a then has to be correspondingly adapted regarding its length and spring properties. With an energy accumulator of this kind the outer spring would thus have an angular extension or length which would correspond to the sum of the extensions of the spring 510, spring 508 and intermediate member 530. The spring 509a must then likewise be made longer.

With the illustrated embodiments only two interfitted springs are provided each time. In many cases it can however also be advantageous if three or where necessary even four springs are provided fitted in each other wherein these springs are advantageously secured in the circumferential direction relative to each as was already described. Thus for example a further spring could be provided by way of example inside the spring according to Figure 9 wherein this additional spring can be housed on a further attachment adjoining the attachment 432 of the spring socket 430. This additional attachment can be formed for example like the attachment for spring 209 according to Figure 7.

The novel construction exhibits the advantage that, and as already mentioned above, the supporting pieces or spring abutments cannot slide out of the adjoining end portion or portions of the spring or springs so that one can invariably ensure a reliable stressing of the springs and a reliable mutual support of springs which are arranged in series.Such slipping out or sliding out of supporting parts can develop particularly when one employs long springs on a relatively large diameter and with a relatively small spring gradient because, and as described, for example in published German patent applications 37 21 711 and 37 21 712, the magnitude of centrifugal force acting upon the springs when the apparatus 1 rotates can be so large that, following a compression of the spring, eg, as a result of an abrupt rise of the load, the pronounced friction between convolutions of the springs and the supporting regions therefor does not permit the springs to fully dissipate the stored energy so that their length is less than that when the springs are completely unstressed.In the absence of the novel securing of the stressing parts or supporting pieces, they can fall out or slip out of the end portion or portions of the corresponding spring or springs to thereupon change their orientation, eg, by turning or twisting, in the chamber 21 or in the toroidal space 22. During a renewed compression or stressing of the corresponding springs, one can no longer invariably ensure that the projection or projections of the intermediate pieces can find their way into the adjacent spring or into the respective spring ends which can bring about a destruction of the intermediate pieces.

The patent claims which are being filed with the application are to be considered as proposed formulations without prejudicing the attainment of broader patent protection. The assignee reserves the right to direct claims to additional features which, at the present time, are pointed out only in the specification and/or in the drawings.

The features which are recited in the dependent claims point out further developments of the subject matter of the main claim; they are not intended to be comprehended as a waiver of the achievement of independent objective protection for the features of the dependent claims.

It is to be borne in mind that the features recited in the dependent claims constitute separate inventions independent of those in the preceding dependent claims.

Furthermore, the invention is not limited to those embodiments which are actually described. Thus, numerous alterations and modifications can be carried out within the purview of the invention especially all such variations, elements and combinations and/or materials which, for example, can be arrived at as a result of combination or modification of individual features or elements or method steps which are outlined in the general description in connection with various embodiments as well as in the claims and shown in the drawings. All of these are deemed to be inventive and they also embrace combinations of features which lead to a new device or novel method steps and/or series of process steps, and this also encompasses the methods of making, testing and operating.

Claims

CLAIMS:

1. Torsional vibration damping apparatus comprising at least two structural elements rotatable relative to each other about a common axis; at least one energy storing device arranged to oppose rotation of said structural elements relative to each other and being compressible by stressing means provided on said structural elements, said at least one energy storing device including at least one coil spring having first and second end portions; at least one abutment adjacent one of said end portions and being movable relative to said structural elements about said axis, said abutment including a portion engaged by an end convolution of one of said end portions; and means for connecting said abutment to said one end portion against loss.

2. Apparatus as claimed in Claim 1, wherein said at least one coil spring has a longitudinal axis and said portion of said at least one abutment overlaps the one end portion of said at least one spring as seen in the direction of said longitudinal axis.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein said connecting means includes a form-locking connection.

4. Apparatus as claimed in Claim 3, wherein said formlocking connection is provided between said abutment and at least said end convolution of said one end portion.

5. Apparatus as claimed in Claim 3, wherein said formlocking connection is a snap-type connection.

6. Apparatus as claimed in any preceding claim, wherein said connecting means is provided between said portion of said at least one abutment and said one end portion of said at least one coil spring.

7. Apparatus as claimed in any preceding claim, wherein said at least one coil spring has a plurality of convolutions including said end convolution and said portion of said at least one abutment is substantially ring-shaped, said at least one abutment further comprising at least one projection extending from said ring-shaped portion into an internal space surrounded by said one end portion of said at least one coil spring, said connecting means being provided between said at least one projection and at least a portion at least one of said plurality of convolutions.

8. Apparatus as claimed in any preceding claim, wherein said end convolution includes a free end portion forming part of said connecting means.

9. Apparatus as claimed in any preceding claim, wherein said at least one coil spring comprises a plurality of convolutions including said end convolution, said connecting means comprising a substantially radial recess provided in said at least one abutment and a portion of one of said plurality of convolutions, said portion of said one of said plurality of convolutions being formlockingly received in said recess.

10. Apparatus as claimed in any preceding claim, wherein said at least one abutment has a recess adjacent said portion thereof and forming part of said connecting means1 said end convolution having a free end portion also forming part of said connecting means and extending at least substantially radially into said recess.

11. Apparatus as claimed in any preceding claim, wherein said at least one coil spring has a plurality of convolutions including said end convolution and additional convolutions, said additional convolutions having first helix angles in the uncompressed condition of said at least one coil spring and, save for a free end portion thereof, said end convolution having a second helix angle at least approximating said first helix angle in the uncompressed condition of said at least one coil spring.

12. Apparatus as claimed in any preceding claim, wherein said portion of said at least one abutment has a supporting surface for said one end portion of said at least one coil spring, said end convolution having a free end portion adjacent and at least substantially parallel to said supporting surface in an uncompressed condition of said at least one coil spring.

13. Apparatus as claimed in any preceding claim, wherein said at least one coil spring has a longitudinal axis and a plurality of convolutions including said end convolution and a plurality of additional convolutions, said end convolution having a free end portion adjacent said portion of said abutment and forming part of said connecting means and extending at least substantially radially inwardly toward said longitudinal axis beyond said additional convolutions.

14. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises an inner spring confined in said at least one coil spring.

15. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises a second spring surrounding said at least one coil spring.

16. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises a second spring confined in said at least one coil spring, and further comprising means for connecting said at least one abutment against loss with said second spring.

17. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises a second coil spring in series with said at least one coil spring between said stressing means, said second coil spring having an end portion adjacent the one end portion of said at least one coil spring and said at least one abutment being disposed between the end portion of said at least one coil spring and the end portion of said second coil spring.

18. Apparatus as claimed in Claim 17, wherein said at least one energy storing device further comprises a third spring confined in one of said coil springs, said third spring having a first length and the coil spring confining said third spring having a second length at least matching said first length.

19. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises an inner spring confined in said at least one coil spring and having a first length, said at least one coil spring having a second length greater than said first length.

20. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises an inner spring confined in said at least one coil spring and having a first length, said at least one coil spring having a second length at least approximating said first length.

21. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises a second spring in series with said at least one coil spring, said stressing means being disposed between said springs and said second spring having an end portion remote from said stressing means and confronting said one end portion of said at least one coil spring, said at least one abutment being disposed between said one end portion of said at least one coil spring and said end portion of said second spring.

22. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device further comprises at least one second coil spring and at least one of said coil springs has a precurved shape.

23. Apparatus as claimed in any preceding claim, wherein said at least one energy storing device has a length in a circumferential direction of said structural elements and said at least one coil spring has a plurality of convolutions including said end convolution, each of said convolutions having an outer diameter which is a small fraction of said length.

24. Apparatus as claimed in any preceding claim, comprising at most three energy storing devices together forming an annulus spacedly surrounding said axis.

25. Apparatus as claimed in any preceding claim, wherein said structural elements are rotatable relative to each other from a neutral position through angles of at least 300 in clockwise and counterclockwise directions.

26. Apparatus as claimed in any preceding claim, wherein at least one of said structural elements forms part of or constitutes a flywheel.

27. A torsional vibration damping apparatus comprising two structural elements rotatable relative to each other about a common axis; at least one energy storing device arranged to oppose rotation of said structural elements relative to each other and comprising at least two springs operating in series, said at least two springs having first end portions adjacent stressing means provided on said structural elements and second end portions; and an abutment disposed between the second end portions of said at least two springs.

28. Torsional vibration damping apparatus substantially as herein described with reference to the accompanying drawings.