A DAMPING DEVICE

Abstract: A damping device (10) includes co-axially arranged first and second parts (11, 12) which can rotate relative to each other by a limited amount about an axis (15) of the damping device. The device also includes at least one linkage device (40A) comprising an anchor link (43) pivotally connected via a first pivot (44) to the first part (11) and having a torque transmitting connection (41A) with the second part (12). The linkage device (40A) acting to resist relative rotation of the first and second parts (11, 12). There is also provided a resilient means in the form of coil spring (66A) which acts generally circumferentially between the linkage device (40A) and the first part (11) to resist relative rotation of the first and second parts (11, 12).

Description: A DAMPING DEVICE The present invention relates to damping devices for transmitting torque between an input part and an output part which can rotate relative to each other and also for absorbing or compensating for torque fluctuations Typically such damping devices can be used in vehicle transmissions for example as part of a twin mass fly wheel or in a torque converter or used on their own in a vehicle drive line It is an object of the present invention to provide an improved form of damping device which causes a resistance to relative rotation of input and output parts which varies dependant upon the angular position of the input part relative to the output part Thus, according to the present invention there is provided a damping device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, the damping device also including at least one linkage device comprising an anchor link pivotally connected via a first pivot to the first part and having a torque transmitting connection with the second part, the linkage device acting to resist relative rotation of the first and second parts and a resilient means acting generally circumferentially between the linkage device and the first part to resist relative rotation of the first and second parts According to a fiirther aspect of the invention there is also provided a damping device including co- axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, the damping device also including at least one linkage device comprising an anchor link pivotally connected via a first pivot to the first part, and having a torque transmitting connection with the second part, the linkage device acting to resist relative rotation of the first and second parts, and the first pivot being resiliently mounted on the first part. According to a still further aspect of the invention there is provided a damping device comprising co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, and having damping means acting to resist relative rotation of the first and second parts, stops being provided on the first and second parts respectively which come into contact to substantially limit the relative rotation of the two parts, in which at least one of the stops is resiliently mounted to its respective part so as to permit a further limited amount of relative rotation of the two parts following contact between the stops. The generally circumferentially acting resilient means of the above first statement of invention, the resilient mounting of the first pivot on the first part of the above second statement of invention and the resilient mounting of one of the stops of the above third statement of invention are all independently applicable to the embodiments shown in prior patent applications PCT/GB96/01282, PCT/GB97/00361, GB 9709436.1 and GB-A-2313898. The invention shall now be described by way of example only with reference to the accompanying drawings in which; FIG.1 is an axial cutaway view taken in the direction of arrow A of FIG.2 of a damping device according to the present invention incorporated into a twin mass flywheel; FIG.1 A is a partial view of FIG.1 ; FIG. IB is a view of a spring arrangement of FIG 1; FIG.2 is a radial view taken along the line BB of FIG.1 ; FIG.3 is a radial view taken along the line CC of FIG.1; FIG 4 is a partial axial cutaway view taken in the direction of arrow A of FIG.1 showing the damping device in a full drive condition; FIG.5 is a partial axial cutaway view taken in the direction of arrow A of FIG.1 with the damping device shown in a full over-run condition; FIG.6 is a view similar to FIG.1 of a second embodiment of a damping device according to the present invention; FIG 7 is an axial view of a third embodiment of a damping device according to the present invention; FIG 8 is an axial view of a fourth embodiment of a damping device according to the present invention, With reference to FIGS 1-5 there is illustrated a twin mass flywheel 1 incorporating a damping device 10 The damping device includes first part 11 and second part 12 which can rotate relative to each other via by a bearing arrangement 13 In this case the bearing arrangement consists of two rotating element ball bearings 13 A, 13B axially spaced relative to each other First part 11 consists of input plate 20, rim 26 and cover plate 21 Pins 22 and 23 are secured between input plate 20 and cover plate 21 First part 11 further includes a plurality of abutment members (also known as support members) 50A, 50B, 50C, 50D Second part 12 consists of output plate 30 and pivot plate 31 secured rotationally fast to the output plate 30 by rivets 32 The damping device 10 further consists of a plurality of linkage devices 40 A, 40B, 40C, 40D All the linkage devices are identical and all abutment members are identical For the purposes of description it is convenient to consider one linkage device 40A and its associated abutment members 50A and 50B in isolation (see FIG 1 A) Linkage device 40A acts as a torque transmitting connection between the first and second parts and comprises an anchor link 43 pivotally connected by a first pivot 44 to first part 11 via abutment member 50A Anchor link 43 is in the form of a pair of links 43 A, 43B mounted axially one on either side of abutment member 50 A Anchor link 43 is also pivotally connected via a second pivot 45 to a linkage arrangement 41 A Linkage arrangement 41 A acts as a torque transmitting connection between the anchor link and the second part and comprises a plurality of circumferentially spaced main links 60 (in this case two main links). Main links 60 are each pivotally connected to second part 12 via a third pivot 42. Main links 60 are interconnected by a generally circumferentially orientated connecting linkage 61 pivotally mounted at one end via second pivot 45 to one of the main links 60 and the anchor link 43, and pivotally connected at another portion to the other of the main links 60 via a further pivot 62. End 63 of connecting linkage 61 includes a spring abutment portion 64 and a spring guide rod 65. Abutment member 50A is in the form of a U-shape having two limbs 51 joined by a bridging portion 52 (see FIG.3). A resilient means in the form of a spring arrangement 66D is partially mounted between the limbs 51 A, 5 IB and is supported by regions 53 of the limbs 51. Ends 54 (remote from bridging portion 52) of limbs 51 include stop portions 55. It will be noted that bridging portion 52 is mounted circumferentiaUy between rivets 22 and 23, with cut-outs 56 of limbs 51 acting against corresponding rivets 22 and 23. Thus, the rivets 22, 23 substantially prevent rotation of abutment 50a about the axis 15 of the damping device 10. Abutment member 50A is mounted on the first part via leaf spring 57 since each end portion of leaf spring 57 abuts a respective rivet 22, 23 and a mid portion of the leaf spring 57 holds the bridging portion 52 against the inner surface of rim 26. In this case leaf spring 57 is installed in a stressed condition though in further embodiments this need not be the case. This arrangement of mounting the abutment member 50A on the input plate can under certain conditions allow the abutment member 50A to rotate about either pin 22 or pin 23. Thus, the abutment member 50A is resiliently mounted via the leaf spring 57 onto the first part. Although the present embodiment discloses resilient mounting of the abutment member 50A via a leaf spring 57, any suitable form of resilient mounting could be used. For example, the bridging portion 52 could be bonded to an elastomer pad which in turn could be bonded to the inner surface ofrim26. Spring arrangement 66A is mounted between the linkage device 40A (and in particular the connecting linkage 61) and the second part 12 (via abutment member 50B). Spring arrangement 66 A (shown diagrammatically in FIG.l but fully in FIG. IB) consists of an outer spring 67 mounted concentrically relative to an inner spring 68 (see FIG. IB). In this example both springs 67 and 68 are pre-tensioned when the damping device is in the neutral position but in further embodiments one or both springs need not be pre-tensioned. Spring arrangements 66B, 66C, and 66D are all identical to spring arrangement 66A. All spring arrangements are positioned in the damping device substantially tangentially with regard to the axis 15 of the damping device so as to act generally circumferentially of the damping device. The damping device 10 is installed in twin mass flywheel 1 which includes the additional components of a starter ring 2, hub 3 and bearing arrangement 13 which allows relative rotation between the input plate 20 (via hub 3) and the output plate 30. The twin mass flywheel is attached to an engine crank shaft (not shown) via bolts 4. A clutch (not shown) is attached to output plate 30). Positioned adjacent ball bearing 13B and surrounding the hub 3 is a multi-plate friction device 14. Operation of the twin mass flywheel and damping device is as follows. Under normal drive and over-run conditions the twin mass flywheel 1 rotates in a clock-wise direction in the view shown in FIG.1 as indicated by arrow R. Relative rotation between the input plate 20 and output plate 30 is controlled by a combination of the linkage devices 40A, 40B, 40C, 40D, spring arrangements 66A, 66B, 66C, 66D, resilient abutment members 50A, 50B, 50C, 50D, and multi-plate friction device 14. Operation of the linkage devices, resilient abutment members, and spring arrangements, are identical so for ease of explanation only the operation of linkage device and its associated resilient abutments and spring arrangements will be described. Under no load conditions with the clutch disengaged centrifugal forces act on the linkage device 40 A and particularly on the connecting linkage 61 to urge main links 60 and anchor link 43 in a radially outward direction with second pivot 45 and further pivot 62 adopting position radially outward of corresponding third pivots 42 as shown in FIGS. 1 and 1A. This position is regarded as the neutral position between the drive and over-run directions of relative rotation of the input and output plates, i.e. the position adopted by the linkage device 40A when the twin mass flywheel is rotating and transmitting zero torque. At higher rotational speeds the centrifugal force is greater and whilst this does not affect the position under no load conditions, it greatly affects the force required to move the output plate 30 relative to the input plate 20, i.e. the flywheel torsional stiffness is increased. If the clutch is engaged and power is transmitted in the drive direction from input plate 20 to output plate 30 there is a tendency for the two plates to rotate relative to each other (input plate 20 rotates clockwise relative to output plate 30 when viewing FIGS.l and 1A). At relatively low speeds when the influence of centrifugal force is relatively small the input and output plates rotate relatively easily relative to each other, i.e. the flywheel torsional stiffiiess is relatively low. However, at relatively high rotational speeds the influence of centrifugal force is much greater and relative rotation of the input and output plates requires greater torque i.e. the flywheel torsional stiflhess is relatively high. Thus, the flywheel torsional stifihess is speed sensitive. If the clutch is engaged and power is transmitted in the over-run direction from the output plate 30 to the input plate 20 the effects are similar to the above except that the direction of relative rotation is reversed (input plate 20 rotates anti-clockwise relative to output plate 30 when viewing FIG.1). Thus, the controlling influence of the linkage arrangement is operable at any rotational speed of twin mass flywheel 1 and also at any relative rotational position of the input and output plates. By comparing the radial position of second pivot 45 as shown in FIG.1 (the neutral position) with its radial position as shown in FIGS.4 and 5 it can be seen that this pivot only moves radially inwards from its neutral position in both the drive and over-run directions of relative rotation. Thus, the anchor link 43 only rotates anti-clockwise as shown in FIG.1 from its neutral position. This results in the distance between spring abutment portion 64 and abutment 50B always being reduced thus always compressing spring arrangement 66A. Thus, the spring arrangement 66A also has the affect of resisting rotation of the input and output plates in both directions of rotation. After a predetermined amount of relative rotation of the input plate relative to the output plate in the over-run direction first stop 33 of output plate 30 contacts a corresponding second stop 55 associated with the first pivot (associated in as much as second stop 55 and first pivot 44 are both mounted on abutment member 50A) (see FIG.5). Whereupon relative rotation of the second part relative to abutment member 50A substantially ceases. However, a further limited amount of relative rotation of second part 12 to first part 11 is still possible since abutment member 50A can pivot about the axis of rivet 23 against the action of leaf spring 57. Thus, increasing the torsional stiffness of the twin mass flywheel. A similar affect occurs when third stop 34 of output plate 30 contacts corresponding fourth stop 59 on abutment member 50B causing abutment member 50B to rotate about the axis of its corresponding pin 22, also resulting in an increase in the torsional stiflhess of a twin mass flywheel 1. 10 The resilient mounting of stops 55, 59 provides cushioning of the damping device at the limits of relative rotation of the input plate 20 and the output plate 30 whilst permitting the use of metal to metal contact which is more durable than would be the case if an elastomeric stop were employed. Also the resilience of each of the stops 55, 59 has a built-in pre-load due to the leaf spring 57. The concept of having a resiliently mounted stop can be applied independently to damping devices other than those described herein. For example the concept could be applied to damping devices having damping means other than those in the form of a linkage device. Also it is not essential that the resiliently mounted stop(s) be provided on the input part of the device, alternatively the resiliently mounted stop(s) could be provided on the output part or the stops on both parts could be resiliently mounted. It can be seen that the first pivot 44 of linkage device 40A is mounted on abutment member 50A, the abutment member 50A also being engaged by the spring arrangement 66D associated with the circumferentially adjacent linkage device 40D. In the present embodiment the pre-stressing of leaf spring 57 ensures that abutment member 50A does not pivot about pins 22 and 23 as a result of any forces applied to member 50A by links 43 A, 43B but only as a result of contact between stops 33, 55 and 34, 59 described above. In further embodiments the leaf spring 57 may not be pre- stressed or be pre-stressed to a lessor extent so that pivotal movement of the abutment member 50A about pins 22, 23 can occur as a result of forces applied by the links 43 A, 43B and/or by the spring 66D. 11 FIG.6 shows a second embodiment of a damping device 110 wherein components equivalent to those shown in damping device 10 are labelled 100 greater. In this case abutment members 150-4, 150B, 150C, 150D are rigidly secured to the input plate 120 via rivets 170. Spring arrangements 166A, 166B, 166C, 166D are all identical, thus for simplicity only one spring arrangement will be described in detail. Spring arrangement 166 A is mounted between two end supports 171, 172 and comprises concentrically arranged inner and outer springs identical to springs 67 and 68. End support 171 is pivotally mounted on abutment member 150B via first pivot 144. End support 171 includes a spring guide rod 165. End support 172 is pivotally mounted on a portion of the connecting linkage 161 A and includes a hole through which spring guide rod 165 can slide. Spring guide rod 165 passes through the centre of spring arrangement 166 A and ensures that during compression of the spring arrangement no buckling takes place. Further embodiments of the invention can include linkage devices which have different linkage arrangements or torque transmitting connections between the anchor link and the second part. For example, FIG.7 shows damping device 210 having a linkage device 240 similar to that disclosed in the applicant's prior British Patent Application No.GB9709436.1 to which the reader is referred for further details. Damping device 210 comprises a linkage device 240 having an anchor link 243 pivotally connected to the first part 211 by a first pivot 244. A torque transmitting connection between the anchor link 243 and the second part 212 is provided by a linkage arrangement 241 12 comprising a first rotating element bearing 273 connected to the free end of anchor link 243 by second pivot 245 and a second rotating element bearing 274 connected to the first bearing 273 by a generally circumferentially orientated link 261. Each of the bearings acts on a respective track 231 A, 23 IB rotationally fast with the second part 212. In accordance with the present invention, damping device 210 includes the additional feature of spring 266 acting generally circumferentially between a spring abutment portion 264 of the linkage device 240 and an abutment member 250 provided on the first part 211. In a preferred construction, spring abutment portion 264 is rigidly connected to the link 261. Alternatively, the abutment portion 264 may be pivotally connected to the link 261 in which case a guide rod extending centrally through the spring 266 will be provided similar to guide rod 165 in the embodiment shown in Figure 6. In the present embodiment the rotating element bearings form a rolling connection acting on the track 231 A, 23 IB, however such a rolling contact is not essential and the torque transmitting connection could take the form of a sliding connection acting on a track. Further embodiments of the invention could include linkage devices with linkage arrangements in the form of a link pivotally connected to the second part and also pivotally connected to the anchor link. FIG.8 shows diagrammatically a damping device 310 comprising a first part 311, a second part 312, an anchor link 343 pivotally connected to the first part 311 by a first pivot 344, a linkage arrangement 341 in the form of a link 346 pivotally connected to the anchor link 343 by a second pivot 345 and to the second part by a third pivot 342. In this case a resilient means in the form of a 13 tangentially orientated spring 366 acts between the anchor link 343 and a spring anchor 350 on the first part to resist relative rotation of the first and second parts. Although various aspects of the invention have been described above in relation to twin mass flywheels they are equally applicable to torsional vibration dampers used in combination with fluid couplings of the type disclosed in earlier patent applications GB-A-2220464 and PCT/GB97/00362 and to dampers used on their own in a drive-line.

Claims: 14 CLAIMS 1. A damping device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, the damping device also including at least one linkage device comprising an anchor link pivotally connected via a first pivot to the first part and having a torque transmitting connection with the second part, the linkage device acting to resist relative rotation of the first and second parts and a resilient means acting generally circumferentially between the linkage device and the first part to resist relative rotation of the first and second parts. 2. A damping device as defined in claim 1 in which the linkage device further includes a linkage arrangement having the torque transmitting connection with the second part and a second pivot for pivotally connecting the anchor link to the linkage arrangement. 3. A damping device as defined in claim 1 or 2 in which the torque transmitting connection is in the form of a sliding or rolling connection acting on a track. 4. A damping device as defined in claims 2 or 3 in which the linkage arrangement comprises a second link pivotally connected to the second part. 5. A damping device as defined in claims 2 or 3 in which the linkage arrangement comprises a plurality of circumferentially spaced main links pivotally connected to the second part with 15 circumferentially adjacent main links being interconnected by a generally circumferentially orientated connecting linkage. 6. A damping device as defined in claim 2 to 5 in which when the damping device is in a neutral position the first pivot is at a smaller radial distance from the axis than the second pivot. 7. A damping device as defined in any one of claims 2 to 6 in which the resilient means acts between the linkage arrangement and the first part. 8. A damping device as defined in any preceding claim in which the resilient means is a coil spring arrangement. 9. A damping device as defined in claim 8 in which the coil spring arrangement comprises two concentrically arranged coil springs. 10. A damping device as defined in claim 9 in which one of the coil springs operates before the other of the coil springs. 11. A damping device as defined in any one of claims 8 to 10 in which at least one end of the spring arrangement reacts against an end support, said end support being pivotally mounted on the linkage device or first part. 16 12. A damping device as defined in any one of claims 8 to 11 in which the spring arrangement is guided by a central rod mounted on the first part or linkage device or end support. 13. A damping device as defined in claim 12 when dependant upon claim 10 in which both ends of the spring arrangement react against corresponding end supports and the rod is guided by one of the end supports. 14. A damping device as defined in claim 8 in which the spring arrangement is guided by a support member mounted on the linkage arrangement or first part. 15. A damping device as defined in any previous claim in which the first pivot and/or the resilient means is resiliently mounted on the first part. 16. A damping device as defined in any preceding claim in which a first stop on the second part contacts a second stop associated with the first pivot to limit rotation of the second part relative to the first part. 17. A damping device as defined in any preceding claim in which a third stop on the second part contacts a fourth stop on an abutment member on the first part against which the resilient means acts. 17 18. A damping device as defined in any preceding claim in which the damping device includes a plurality of linkage devices and the first pivot of one linkage device is mounted on an abutment member engaged by the resilient means of another linkage device. 19. A damping device as defined in claim 18 in which the abutment member is of a U-shaped form having two limbs joined by a bridging portion. 20. A damping device as defined in claim 19 in which the anchor link is pivotally mounted between the limbs. 21. A damping device as defined in claims 19 or 20 in which the resilient means is at least partially mounted between the limbs. 22. A damping device as defined in any one of claims 19 to 21 when dependent upon claim 16 or 17 in which ends of the limbs remote from the bridge portion act as the second and fourth stops. 23. A damping device as defined in any one of claims 19 to 22 in which the bridge portion is mounted between two rivets secured rotationally fast with the first part. 24. A damping device as defined in claim 23 in which the rivets substantially prevent rotation of the abutment member about the axis of the damping device. 18 25. A damping device as defined in claims 23 or 24 in which the rivets allow rotation of the abutment member about an axis of at least one of the rivets. 26. A damping device as defined in any one of claims 17 to 25 in which the abutment member is resiliently mounted on the first part by a leaf spring. 27. A damping device as defined in claim 26 when dependant upon claim 20 in which each end portion of the leaf spring react against a respective rivet and a mid portion of the leaf spring reacts against the bridge portion to resiliently mount the abutment member. 28. A damping device as defined in claims 26 or 27 in which the leaf spring is pre-stressed. 29. A damping device as defined in claim 28 when dependant upon claims 17 or 18 in which the leaf spring pre-stress is such that the resilient mounting of the abutment member only operates as a result of contact between the first and second stops or the third and fourth stops. 30. A damping device as defined in any preceding claim in which the resilient means is mounted substantially tangentially with regard to the axis of the damping device. 31. A damping device as defined in any preceding claim in which the resilient means acts to resist relative rotation of the first part relative to the second part in both a first direction of relative rotation and a second direction of relative rotation. 19 32. A damping device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, the damping device also including at least one linkage device comprising an anchor link pivotally connected via a first pivot to a first part, and having a torque transmitting connection with the second part, the linkage device acting to resist relative rotation of the first and second parts, and the first pivot being resiliently mounted on the first part. 33. A damping device as defined in claim 32 in which the first pivot is mounted on a support member which is resiliently mounted on the first part. 34. A damping device as defined in claim 32 in which the support member is of a U-shaped form having two limbs joined by a bridging portion. 35. A damping device as defined in claim 34 in which the anchor link is pivotally mounted between the limbs. 36. A damping device as defined in claims 34 or 45 in which the bridge portion is mounted between two rivets secured rotationally fast with the first part. 37. A damping device as defined in claim 36 in which the rivets substantially prevent rotation of the support member about the axis of the damping device. 20 38. A damping device as defined in claims 36 or 37 in which the rivets allow rotation of the support member about an axis of at least one of the rivets. 39. A damping device as defined in any one of claims 33 to 38 in which the support member is resiliently mounted on the first part by a leaf spring. 40. A damping device as defined in claim 39 when dependant upon claim 36 in which each end portion of the leaf spring reacts against a respective rivet and a mid portion of the leaf spring reacts against the bridge portion to resiliently mount the support member. 41. A damping device as defined in claims 39 or 40 in which the leaf spring is pre-stressed. 42. A damping device as defined in any of claims 32 to 41 in which a first stop on the second part contacts a second stop on the first part to limit rotation of the second part relative to the first part in a first direction 43. A damping device as defined in claim 42 in which a third stop on the second part contacts a fourth stop on the first part to limit rotation of the second part relative to first part in a second direction opposite to the first direction. 44. A damping device as defined in claim 43 when dependant on claim 33 in which at least one of the second and fourth stops are provided on the support member. 21 45. A damping device as defined in claim 44 when dependant on claim 34 in which ends of the limbs remote from the bridge portion act as the second and fourth stops. 46. A damping device as defined claim 44 or 45 when dependant upon claim 41 in which the leaf spring pre-stress is such that the resilient mounting of the support member only operates as a result of contact between the first and second stops or the third and fourth stops. 47. A damping device comprising co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, and having damping means acting to resist relative rotation of the first and second parts, stops being provided on the first and second parts respectively which come into contact to substantially limit the relative rotation of the two parts, in which at least one of the stops is resiliently mounted to its respective part so as to permit a further limited amount of relative rotation of the two parts following contact between the stops. 48. A damping device as claimed in claim 47 in which the stops are both made of metal. 49. A damping device as claimed in claims 47 or 48 in which the at least one stop is provided on a support member which is resiliently mounted to the respective part. 50. A damping device as claimed in any of claims 47 to 49 in which the damping means is a linkage device comprising an anchor link pivotally connected via a first pivot to the first part and having a torque transmitting connection with the second part. 22 51. A damping device according to any previous claim in the form of a twin mass flywheel in which the first and second parts comprise input and output masses of the flywheel which are supported for relative axial rotation on two axially spaced bearings. 52. A damping device constructed and arranged substantially as hereinbefore described with reference to and as shown in FIGS.1 to 5 or 6 or 7 or 8 of the accompanying drawings.

Inventors: YOUNG ALASTAIR JOHN, YOUNG, ALASTAIR, JOHN
Applicants: AUTOMOTIVE PRODUCTS PLC, YOUNG ALASTAIR JOHN, YOUNG, ALASTAIR, JOHN
Application year: 1999
Main classification: F16F15
IPC codes: F16F15