GB2308173A

GB2308173A - Rotary vibration damper

Info

Publication number: GB2308173A
Application number: GB9625620A
Authority: GB
Inventors: Thomas Lauinger; Holger Seidl
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1995-12-14
Filing date: 1996-12-10
Publication date: 1997-06-18
Anticipated expiration: 2016-12-10
Also published as: JP4138040B2; FR2742509A1; BR9605991A; DE19648342B4; DE19648342A1; GB2308173B; FR2742509B1; JPH09177889A; GB9625620D0

Description

ROTARY VIBRATION DAMPER The invention relates to a rotary vibration damper with at least two structural elements which can be rotated against the resistance of at least one energy accumulator and which have biasing areas to compress the energy accumulator.

A hydrodynamic torque converter is known from US PS 5 377 796 wherein a rotary vibration damper is used whose energy accumulators consist of an outer coil spring and an inner coil spring housed therein. The inner and outer coil springs thereby have approximately the same length.

Energy accumulators of this kind are used, as can be concluded from US PS 5 367 919 in flywheels consisting of several masses. The energy accumulators are thereby provided between the primary flywheel mass connectable with a drive motor and the secondary flywheel mass connectable with a gearbox through a clutch, namely so that between the two flywheel masses a relative rotation is possible against the action of the energy accumulators. The energy accumulators are compressed during relative rotation between the two flywheel masses by the biasing areas provided on the latter.

The object of the present invention is to provide rotary vibration dampers of the kind already described which allow satisfactory biasing or functioning of the energy accumulators, namely in all operating conditions which arise. It is also to be ensured that a particularly simple assembly and cost-effective production of rotary vibration dampers is possible. The structural design of the rotary vibration damper should moreover also allow a number of variations and adapt ion of the torque characteristic line or turning resistance characteristic line existing between the two relatively rotatable structural elements. It should thus be possible to achieve at least over partial areas of the entire turning angle between the structural elements both very soft turning sections, thus having a small turning resistance rate, and turning areas having a higher turning resistance rate.

According to the invention this is achieved in that the at least one energy accumulator provided between the relatively rotatable structural elements consists of at least two coil springs of which the one is housed at least in part inside the hollow cavity formed by the windings of the other coil spring, wherein the one coil spring has an end section with at least one winding which has a larger mean winding diameter than the windings housed inside the other spring so that the end section of the one coil spring can be supported on an end winding of the other coil spring - viewed in the axial direction of the energy accumulator.

The energy accumulators which are used to form the invention each have at least a first coil spring which is housed at least in part in the spring interior defined by the windings of a second coil spring, wherein the first coil spring has at least two types of windings of which the first type has a first mean winding diameter which allows these windings to be housed inside the second coil spring, and the second type of windings has a second larger winding diameter which is larger than the first mean winding diameter wherein this second type of windings - viewed in the direction of the longitudinal axis of the energy accumulator - is located outside of the spring interior defined by the windings of the second coil spring.

Through the design of the energy accumulator according to the invention it can be ensured that the windings with larger mean winding diameter of the first coil spring can be supported on the second coil spring, namely on an end area or end winding of same. It can thereby be ensured that the first coil spring remains positioned opposite the second coil spring, seen in the rotary direction of the rotary vibration damper. The first coil spring can thus not be moved freely inside the second coil spring.Since during compression of the corresponding energy accumulator at least one winding with larger mean diameter of the first coil spring is tensioned between at least one biasing area of at least one of the rotatable structural elements and an end area or end winding of the second coil spring, it is also ensured that the first coil spring inside the rotary vibration damper retains a definite position in the circumferential direction so that during operation of the rotary vibration damper no imbalance can occur which can arise when using energy accumulators with an outer coil spring and a shorter inner coil spring provided inside same.

The energy accumulators designed according to the invention can thus be arranged symmetrical in the rotary vibration damper - viewed over the circumference -, whereby an imbalance is practically excluded.

Although at least one of the windings with larger mean diameter of the first coil spring can be supported on an end winding of the second coil spring with the interposition of a supporting ring, it can be particularly advantageous if the winding with larger mean diameter of the first coil spring is supported directly on a winding of the second coil spring. The two adjoining windings of the first and second coil spring can advantageously be designed so that they have contact at least over 40% of the winding circumference.

With a straight energy accumulator it is endeavoured to obtain the largest possible contact area.

When using an intermediate ring between the at least two associated windings of the two springs it can be expedient if the side faces of this ring are adapted to the path of the relevant winding of the two coil springs so that a satisfactory mutual support and biasing of the two coil springs is ensured. When using an intermediate ring of this kind the windings can have, for the mutual support of the springs, a pitch which agrees where required with that of the other windings wherein the side faces of the intermediate ring have corresponding ramps on which these windings are supported. Particularly for the outer coil spring a design of this kind can be advantageous since the corresponding end winding can then be formed merely by cutting off or separating off the wire spring. Thus with a design of this kind no laid and polished end winding is required at least on the outer coil spring.The intermediate ring is set on windings with smaller mean winding diameter of the first spring.

In order to ensure a satisfactory mutual support of the two coil springs it can be particularly advantageous if at least one of the windings of the first coil spring and at least one end winding of the second coil spring have the same mean winding diameter. It can thereby be avoided that the two windings supporting one another move radially relative to each other. The latter is particularly important in the case of energy springs which have been stressed to block.

The windings of the coil springs can be flattened at least slightly at least in the area of mutual contact.

Although the first coil spring can have in practice only one spring winding with larger diameter which can be clamped between biasing areas of at least one of the rotatable structural elements and an end winding of the second coil spring, it can also be expedient for many cases if the first coil spring has at least two windings with larger diameter.

The windings with larger diameter can thereby be formed in the non-biased state of the first coil spring and viewed in the axial direction thereof so that they adjoin one another at least substantially.

In many cases it an also be expedient if the first coil spring has further windings adjoining the winding supported on an end winding of the second coil spring wherein these further windings have a certain winding pitch whereby the first coil spring forms a further spring section which is active in series with the second coil spring, whilst the spring areas of the first coil spring housed in the second coil spring act parallel to the second coil spring.

In many cases it can be advantageous if the two coil springs have at least approximately the same wire diameter. In many other cases it can however also be expedient if the first coil spring has a smaller wire diameter than the second coil spring. The first coil spring can however also have a larger wire diameter than the second coil spring.

It can be particularly advantageous if at least the section of the first coil spring which can be housed in the inner space defined by the windings of the second coil spring, is shorter than the length of the second coil spring. A rotary vibration damper can thereby be formed with an at least twin-step spring characteristic line. According to a further development of the invention the energy accumulator can have a third coil spring which is similar to the first coil spring wherein the windings with smaller mean diameter of the first and third coil spring are each pushed into an end area of the second coil spring.The first and third coil spring thereby each extend only over a partial area of the length of the second coil spring wherein between the facing end windings of the first and third coil spring there is preferably a play or a distance which allows a certain relative rotation between the structural elements of the rotary vibration damper only against the action of the second coil spring. The first and third coil springs can thereby have the same wire diameter or a different wire diameter. Furthermore the spring rate of the first and third coil springs can be different.

It can be particularly advantageous if the windings of the first coil spring and where applicable the third coil spring have a different winding sense than the windings of the second coil spring. The resilient windings of the coil springs can have at least approximately the same winding pitch. It can however also be expedient if the winding pitch of the second coil spring is larger or smaller than the winding pitch of the windings of the first and where applicable of the third coil spring housed in same.

When using energy accumulators which in relation to the longitudinal axis have a large length-outer diameter ratio it can be particularly advantageous if the energy accumulators have a curved shape in the relaxed state. To this end at least one of the coil springs can have in the relaxed state a forwardly curved shape wherein it is however expedient in most cases if two and where required all three coil springs have a forwardly curved shape in the relaxed state. Although it can be advantageous if - in relation to the longitudinal axis of the energy accumulator - the coil springs have different radii of curvature, it is expedient for the majority of cases to design the coil springs with an at least approximately identical radius of curvature.

Assembly is also facilitated.

When using forwardly curved coil springs it is particularly expedient if the winding of the first and where applicable of the third coil spring axially adjoining an end winding of the second coil spring adjoin at least in the radially inner area of the end winding of the second coil spring - in the relaxed state of the energy accumulator It is particularly advantageous if the coil springs which have spring areas which can be housed in a second coil spring have at least one intermediate winding with a section which extends spirally from a winding with small mean winding diameter to a winding or a winding section with larger mean winding diameter.

The end windings of the second coil spring as well as at least the end winding with larger mean diameter of the first and where required of the third coil spring can advantageously be designed according to DE-OS 42 29 416 since a satisfactory biasing of the coil springs is thereby guaranteed and furthermore the risk of breakage for these end windings can be considerably reduced.

The energy accumulators are advantageously designed so that they allow between the relatively rotatable structural elements of the rotary vibration damper at least a turning angle of 300 in both turning directions. It can be expedient if at least two and a maximum of four energy accumulators are provided which are preferably arranged symmetrical relative to the axis of rotation of the rotary vibration damper.

The rotary vibration damper can advantageously be a component part of a flywheel consisting of several masses or can form same.

Additional features and advantages of the invention are apparent from the following description of the drawings in which: Figure 1 is a sectional view through a damping device according to the invention; Figure 2 is a partial section along the line II/II of Figure 1; Figures 3a to 3b show a design according to the invention of an energy accumulator for use with an apparatus according to Figures 1 and 2; Figures 4 to 4b show a further design possibility of an energy accumulator according to the invention; and Figures 5 to 5b show a further design possibility of an energy accumulator.

The rotary vibration damper shown in part in Figures 1 and 4 forms a divided flywheel 1 which has a first or primary flywheel mass 2 fixable on an output shaft (not shown) of an internal combustion engine, as well as a second or secondary flywheel mass 3. A friction clutch can be fixed on the second flywheel mass 3 with the interposition of a clutch disc through which an input shaft (not shown) of a gearbox can be engaged and disengaged. The flywheel masses 2 and 3 are mounted rotatable relative to each other through a bearing 4 which in the illustrated embodiment is mounted radially outside of bores 5 for passing through fixing screws for fitting the first flywheel mass 2 on the output shaft of an internal combustion engine. Operating between the two flywheel masses 2 and 3 is a damping device 6 which comprises energy accumulators 7 of which at least one is formed by coil compression springs 8,9. As can be seen in particular from Figure 2 the coil compression spring 9 is housed practically completely in the space formed by the windings 8a of the spring or in other words the two coil springs 8 and 9 are boxed inside each other viewed over their longitudinal extension. In the illustrated embodiment the angular extension or length 11 of the section 10 of the coil spring 9 housed in the coil spring 8, viewed circumferentially, is less than the extension 12 of the outer coil spring 8. It can thereby be expedient if the section 10 of the spring 9 is shorter by an amount opposite the outer spring 8 which is in the order of between 30 and 900, preferably in the area of 45 to 700.The length difference or angular difference can however also be larger or smaller.

The two flywheel masses 2 and 3 have biasing areas 14, 15 or 16 for the energy accumulators 7. With the illustrated embodiment the biasing areas 14, 15 are formed by indentations formed in the sheet metal parts 17,18 which make up the first flywheel mass 2. The biasing areas 16 provided axially between the biasing areas 14,15 are formed through a flange-like biasing component 20 connected at least with the secondary flywheel mass 3, such as by rivets 19. This component part 20 serves as the torque transfer element between the energy accumulators 7 and the flywheel mass 3. The biasing areas 16 are formed by radial arms or extensions 16 provided on the outer circumference of the flange-like biasing means 20.The component part 17 produced by cold forming sheet metal material serves to fix the first flywheel mass 2 or the entire divided flywheel 1 on the output shaft of an internal combustion engine.

Radially outside, the component part 17 is connected to the component part 18 likewise made of sheet metal. The two component parts 17 and 18 form a ring-shaped space 21 which has a toroidal area 22. The ring-shaped space 21 or toroidal area 22 is filled at least in part with a viscous medium such as for example grease. Viewed in the circumferential direction between the moulded areas or biasing areas 14,15 the component parts 17,18 form bulges 23, 24 which define the toroidal area 22 and house the energy accumulators 7, as well as run in both the radial and axial direction. At least with the rotating device 1 at least the windings of the springs 8 are supported on the areas of the component part 17 and/or 18 which define the toroidal area 22 radially outwards.With the illustrated embodiment an anti-wear member 25 formed by at least a hardened sheet metal insert or intermediate layer is provided on which at least the springs 8 are radially supported. The anti-wear member 25 extends circumferentially advantageously at least over the entire length or angular extension of the relaxed energy accumulators 7. As a result of the support of the windings of at least the spring 8 through centrifugal force a speeddependent friction damping is produced between these windings and the component parts in friction engagement therewith when there is a change in length or during compression of the energy accumulators 7 and coil springs 8.

The radially extending component part 17 supports radially inside an intermediate part or hub 26 which houses or supports the inner bearing ring of the ball bearing 4. The outer bearing ring of the ball bearing 4 supports the flywheel mass 3.

As can be seen in particular from Figure 2 the biasing areas 16 are designed smaller in terms of angles than the biasing areas 14,15 positioning the energy accumulators 7 in the circumferential direction so that starting from the theoretical rest position or starting position shown in Figure 2 a slight turn is possible in both rotary directions of the flywheel masses 2 and 3 relative to each other without spring action.

Figures 3a to 3b show the end area of the energy accumulator 7 shown in Figure 2 wherein in Figure 3a the spring is shown in cross-section and in Figure 3b in complete form thus viewed from outside whereby the path of the individual windings of this spring in relation to the path of the windings of the spring 8 can be seen more clearly. The coil spring 9 has an end section 27 which in the illustrated embodiment has about two complete windings 28. The winding adjoining the end winding 29 of the coil spring 8 is supported directly on this end winding 29, namely at least in the radially inner area 30. It is thereby ensured that when the energy accumulator 7 becomes blocked the torque is transferred at least over the inner areas of the windings 28a and 8a.It is however advantageous if the end winding 29 and the adjoining winding 28 are supported on each other over a larger area of the circumferential extension so that during compression of the energy accumulator 7 the spring 8 is biased satisfactorily by the end section 27. The windings 28 of the end section 27 adjoining the spring 8 and at least the end winding 29, preferably also the remaining windings 8a of the spring, preferably have at least approximately the same mean winding diameter 30 whereby a satisfactory support is ensured between the two springs 8 and 9. The section 10 of the coil spring 9 housed inside the channel or hollow cavity defined by the windings 8a of the coil spring 8 has windings 9a with a smaller mean winding diameter 31.As can be seen from Figures 3a and 3b the windings of the springs 8 and 9 are wound in opposite directions, thus have viewed in the circumferential direction of the windings, an opposite pitch. This means that the windings of one spring rise in the clockwise direction whilst the windings of the other spring rise in the anti-clockwise direction. The pitch size of the windings 8a and 9a can thereby be the same size or can be different wherein it can be expedient if the pitch size of the windings 8a is larger than that of the windings 9a. The latter is shown in the drawings.

It can be expedient if the two coil springs 8 and 9 have at least approximately the same wire diameter. In many cases it can also be expedient if the wire cross-section of the coil spring 9 has a smaller diameter than the wire crosssection of the coil spring 8.

During compression of an energy accumulator 7 the windings of the end section 27 of the spring 9 are tensioned or clamped between an end winding 29 of the corresponding spring 8 and the biasing areas 14, 15 or 16 (Figure 1 and 2).

The wire cross-section of the springs 8, 9 as well as their relevant winding pitch and extension 11 of the spring section 10 and extension 12 of the spring 8 are preferably matched with each other so that when carrying out the complete turning angle possible between the two flywheel masses 2 and 3 the windings 8a or the spring 8 become blocked.

For the assembly and functioning of the rotary vibration damper it is particularly advantageous if at least one of the coil springs 8,9 has a forwardly curved shape in the relaxed state. For the majority of cases it is expedient if the two coil springs 8,9 have in the relaxed state a forwardly cured shape wherein in relation to the longitudinal axis of the energy accumulator 7 the two coil springs 8,9 can have at least approximately the same radius of curvature. In some cases it can also be expedient if to optimize the tension in the corresponding spring wire the radius of curvature of at least one of the springs 8,9 is slightly larger or slightly smaller than the mean radius 32 (Figure 2) on which the energy accumulator 7 is installed.

The outer diameter of the windings 9a is matched with the inner diameter of the windings 8a so that the windings 9a of the spring section 10 are guided particularly play-free or with only a slight play through the windings 8a in the radial direction. As can be seen from Figure 2 the energy accumulator 7 or coil spring 8 has a large length-outer diameter ratio whereby large turning angles are possible between the two flywheel masses or flywheel elements 2,3.

As can be seen also from Figures 3 to 3b the coil spring 9 has an intermediate winding 33 which connects the two windings 9a and 28 together and which forms a section which extends spirally from one winding with small mean winding diameter 31 to one winding with larger mean winding diameter 30. The intermediate winding 33 is thereby designed and positioned relative to the windings 28 and 29 so that a satisfactory support for the functioning of the rotary vibration damper is guaranteed between the two springs 8 and 9. This defined path or defined position of the intermediate winding 33 is maintained as a result of the forwardly curved shape of the coil springs 8,9 since as a result of this curvature the springs 8,9 cannot turn relative to each other.

In order to increase the service life of the springs 8,9 and to prevent breakage of the end winding 29 of the spring 8 and end winding 34 of the spring 9 it is expedient if these end windings are designed according to DE-OS 42 29 416.

With a design of the energy accumulator 7 according to Figure 2 two such energy accumulators can be arranged over the circumference of the ring-shaped space 21 wherein as is apparent from Figure 2 the installation is undertaken so that practically no imbalance can arise in the system. The end sections 27 of the springs 9 are thus mounted diametrically opposite.

As a result of the construction according to the invention the areas 10 of the coil springs 9 housed in the coil springs 8 are clearly positioned opposite the spring 8 in the circumferential direction so that the sect ions 10 cannot move or wander inside the coil spring 9. The formation of an imbalance during operation of the rotary vibration damper is thereby avoided.

According to an embodiment (not shown) at least one spring 8 could also hold two coil springs which are formed according to a spring 9, namely one spring 8 according to Figure 2 could also house on its second end area a spring 9 which is adapted accordingly regarding its length. The length 11 of the relevant area 10 would have to be shortened accordingly whereby it can be expedient if a play or distance remains between the facing end areas of the corresponding sections 10 of the two springs.

The individual springs can have the same spring rate. It can however also be advantageous if the springs have different spring rates.

The energy accumulator 107 according to Figures 4 to 4b is constructed similar to the energy accumulator 7 according to Figures 3 to 3b, thus likewise has two coil springs 108 and 109. The coil spring 109 differs from the coil spring 9 in that it has practically only one full winding 128 with a large mean winding diameter. As far as the other features are concerned however the spring 109 corresponds to spring 9. Thus for example a spiral shaped intermediate winding 133 is also provided.

The energy accumulator 207 according to Figures 5 to 5b likewise has two coil springs 208, 209 which viewed in the longitudinal direction 132 of the energy accumulator 107 are boxed inside each other in the same way as described in connection with the embodiment according to Figures 3 to 3b.

The essential difference between an embodiment according to Figures 3 to 3b and an embodiment according to Figures 5 to 5b is in the type of construction of the end section 227 of the spring 209 supported on the spring 208. As can be seen in particular from Figure 5 the end section 227 consists of ring-shaped or spiral shaped wound winding sections 228.

The ring-shaped area 228a of the winding section 228 is thereby designed so that this extends circumferentially over about 210 to 2800, wherein as can be seen from Figures 5 to 5b the wire cross-section remains constant. In the embodiment according to Figures 5 to 5b the winding area 228a running in a ring extends over about 2700 in the circumferential direction. The end winding or winding section 228 is thus not cut - viewed in the longitudinal direction of the energy accumulator 207. The latter is the case for example with the winding or winding section 34 of the spring 9 according to Figures 3 to 3b. The winding section 228 has a cut 234 only in the area of its free end area 228b on the outer circumference of the wire forming the winding 228.The cut 234 ensures that as can be seen from Figure 5, the outer overall contour of the energy accumulator 207 or of the end section 227 has a circular shape. Between the winding area 228a running in a ring and which viewed in the axial direction of the coil spring has no or practically no pitch, and the windings 209a which are housed inside the spring 208 is a spiral winding area 233 which ensures a transition from the windings 209a to the winding or winding area 228a. With the illustrated embodiment according to Figures 5 to 5b each mean winding diameter of the windings 209a and end winding area 228a correspond to the amount 31 or 30 of Figure 3.

In many cases it can be expedient if the coil springs 9, 109, 209 have for supporting on the corresponding second spring 8, 108, 208 adjoining their end section 27, 227 or adjoining the end windings 28, 128, 228 further windings which have a certain winding pitch whereby an additional spring section is formed which is active in series with the corresponding spring 8, 108, 208 or with the spring section (10 of Figures 3a and 3b) of the spring springs 9, 109, 209 housed inside the spring 8, 108, 208. Through such a design of an energy accumulator when using two springs a threestepped spring characteristic line is possible.The additional spring section of the corresponding spring 9, 109, 209 can thereby have a lower spring rate than the associated spring 8, 108, 208 so that the additional spring area and the corresponding spring 8, 108, 208 are at first active in series wherein the additional spring area first becomes blocked so that then first only the spring 8, 108, 208 can be active. After further compression of the spring 8, 108, 208 the windings 9, 109, 209 housed therein then come to act parallel so that the overall spring rate of the energy accumulator becomes greater.

With an embodiment of the end section 27 according to Figures 3 to 3b the windings 28 having a larger mean winding diameter could instead of adjoining one another also have a certain spacing from each other so that this end section 27 produces a damping action over a certain relative turning angle between the two flywheel masses 2,3. The spring rate of the windings 28 forming the end section 27 is then preferably less than that of the spring 8.

The patent claims filed with the application are proposed wordings without prejudice for obtaining further patent protection. The applicant retains the right to claim further features disclosed up until now only in the description and/or drawings.

References used in the sub-claims refer to the further development of the subject of the main claim through the features of the relevant sub-claim; they are not to be regarded as dispensing with obtaining an independent subject protection for the features of the sub-claims referred to.

The subjects of the sub-claims also represent independent inventions which have a design independent of the subjects of the preceding sub-claims.

The invention is also not restricted to the embodiments of the description. Rather numerous modifications and alterations are possible within the scope of the invention, more particularly those variations, elements and combinations and/or materials which are inventive for example through combination or modification of individual features or elements or method steps contained in the drawings and described in the general description and claims and which through combinable features lead to a new subject or new method steps or sequence of method steps, insofar as they relate to manufacturing, testing and working methods.

Claims

PATENT CLAIMS

1. Rotary vibration damper with at least two structural elements which can be rotated against the resistance of at least one energy accumulator and which have biasing areas to compress the energy accumulator, characterised in that the energy accumulator consists of at least two coil springs of which the first coil spring is housed at least in part inside the hollow cavity formed by the windings of the other second coil spring, wherein the first coil spring has an end section with at least one winding, which has a larger mean winding diameter than the windings included within the second spring so that the end section of the first coil spring can be supported against an end winding of the second coil spring - viewed in the axial direction of the energy accumulator.

2. Rotary vibration damper with at least two structural elements which can be turned against the resistance of at least one energy accumulator and which have biasing areas to compress the energy accumulator, characterised in that the energy accumulator has at least one first coil spring which is housed at least in part in the spring interior defined by the windings of a second coil spring wherein the first coil spring has at least two types of windings of which the first type has a first mean winding diameter which allows these windings to be housed inside the second coil spring and the second type of windings has a second mean winding diameter which is larger than the first mean winding diameter wherein this second type of windings - viewed in the direction of the longitudinal axis of the energy accumulator - is located outside the spring interior defined by the windings of the second coil spring.

3. Rotary vibration damper according to claim 2 characterised in that the second type of windings has a mean winding diameter which allows these windings to be supported on an end winding of the second coil spring.

4. Rotary vibration damper according to claim 1 or 2 characterised in that at least one of the windings of the first coil spring and at least one end winding of the second coil spring have the same mean winding diameter.

5. Rotary vibration damper according to one of claims 1 to 4 characterised in that the at least one spring winding with larger diameter of the first coil spring can be clamped between biasing areas of at least the rotatable structural element and an end winding of the second coil spring.

6. Rotary vibration damper according to one of claims 1 to 5 characterised in that the two coil springs have at least approximately the same wire diameter.

7. Rotary vibration damper according to one of claims 1 to 6 characterised in that the first coil spring has a smaller wire diameter than the second coil spring.

8. Rotary vibration damper according to one of claims 1 to 7 characterised in that the first coil spring has at least two windings with larger diameter.

9. Rotary vibration damper according to claim 8 characterised in that the windings - viewed in the axial direction of the first coil spring and in the non-biased state - adjoin one another

10. Rotary vibration damper according to one of claims 1 to 8 characterised in that at least the section of the first coil spring which can be housed in the inner space defined by the windings of the second coil spring is shorter than the second coil spring.

11. Rotary vibration damper according to one of claims 1 to 10 characterised in that the windings of the first coil spring have a different winding direction than the windings of the second coil spring.

12. Rotary vibration damper according to one of claims 1 to 11 characterised in that the two coil springs have at least approximately the same winding pitch.

13. Rotary vibration damper according to one of claims 1 to 12 characterised in that the winding pitch of the second coil spring is larger than the winding pitch of the windings of the first coil spring housed inside same.

14. Rotary vibration damper according to at least one of the preceding claims, characterised in that at least one of the coil springs has a forwardly curved shape in the relaxed state.

15. Rotary vibration damper according to at least one of the preceding claims, characterised in that in relation to the longitudinal axis of the energy accumulator both coil springs have at least approximately the same radius of curvature.

16. Rotary vibration damper according to at least one of the preceding claims, characterised in that the energy accumulator has a large length-outer diameter ratio.

17. Rotary vibration damper according to one of claims 1 to 16 characterised in that the winding of the first coil spring adjoining an end winding of the second coil spring adjoins at least in the radial inner area of this end winding in the relaxed state of the energy accumulator.

18. Rotary vibration damper according to one of claims 1 to 17 characterised in that the first coil spring has at least one intermediate winding with a section which extends spirally from one winding with small mean winding diameter to another winding with larger mean winding diameter.

19. Rotary vibration damper according to at least one of the preceding claims, characterised in that the energy accumulator allows at least a turning angle of 300 in both directions between the structural elements which are rotatable relative to each other.

20. Rotary vibration damper according to at least one of the preceding claims, characterised in that at least two energy accumulators are provided symmetrical relative to the axis of rotation of the rotary vibration damper.

21. Rotary vibration damper according to at least one of the preceding claims, characterised in that this component part is a flywheel consisting of several masses or forms same.

22. Rotary vibration damper substantially as herein described with reference to the accompanying drawings.