A DAMPING DEVICE

Abstract: A damping device (10) for use in a drive line, the device (10) including co-axially arranged first and second parts (11, 12) which can rotate relative to each other by a limited amount in response to torsional vibrations and/or torque fluctuations in the drive line. The device also includes a spring (50) which is stressed in at least two independent manners to resist relative rotation of the first and second parts (11, 12) and hence damp the said vibrations and/or fluctuations. The damping device (10) may form part of a twin mass flywheel (1) or a fluid coupling such as a torque converter or fottinger coupling. There is also disclosed a damping device (10) in which the co-axially arranged first and second parts (11, 12) are interconnected by a linkage. A friction damper (60, see Figure 3) is provided which acts directly on components pivotally connected by a pivot of the linkage. The friction damper being arranged co-axially of the pivot.

Description: A DAMPING DEVICE The present invention relates to damping devices which include at least one spring to damp and/or absorb torsional vibrations and/or torque fluctuations in a drive line Typically such damping devices can be used in vehicle transmissions as part of a twin mass flywheel or in a fluid coupling such as a torque converter or fottinger coupling In known damping devices which include springs, the spring is acted upon in one particular manner for example the spring 55 of DE3721710 is only axially compressed along its curved axis and the spring 17 of FR2518203 is only put into tension by extending the spring along its axis as the input and output parts of the damping device rotate relative to each other It is an object of the present invention to provide an improved form of a damping device which includes a spring which is relatively cheap and simple and produce and has a relatively long service life It is a further object of the invention to provide a damping device in which the input and output parts can rotate relative to each other and the resistance to rotation caused by the damper 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 for use in a drive line, the device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount in response to torsional vibrations and/or torque fluctuations in the drive line, said first and second parts forming, in use, part of a torque transmission path of the drive line, the device also including a spring which is stressed in at least two independent manners to resist relative rotation of the first and second parts and hence damp said vibrations and/or fluctuations. Preferably the spring is also stressed in a third independent manner to resist relative rotation of the first and second parts. The spring may be a coil spring and one of the manners of stressing the spring may be by rotating a first end of the spring relative to a second end of the spring about the axis of the coils. Where the spring is a coil spring, one of the manners of stressing may be by applying a force to at least one coil in a radial direction with regard to the axis of the coil. In a preferred embodiment the spring may include an arm portion and one of the manners of stressing the spring may be by applying a force substantially perpendicular to the arm According to another aspect of the invention, there is provided a damping device for use in a drive line, the device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount in response to torsional vibrations and/or torque fluctuations in the drive line, the first and second parts being interconnected by at least one linkage means, the device further comprising a fiiction damper which acts directly on components pivotally connected by a pivot of the linkage means to resist relative rotation of the first and second parts and hence damp said vibrations and/or fluctuations. In a preferred embodiment the fiiction damper is arranged co-axially with the pivot of the linkage means. According to further aspect of the invention there is provided damping device for use in a drive line, the 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 in response to torsional vibrations and/or torque fluctuations in the drive line, the damping device also including at least one linkage device to resist relative rotation of the first and second parts and hence damp the said vibrations and/or fluctuations, the linkage device including a link pivotally connected by a pin with the first or second part via a pair of spaced apart bearing surfaces in the said first or second part. 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 along the line AA of FIG.2 of a damping device according to the present invention, as installed in a twin mass flywheel; 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 developed view taken along the line EE of FIG.1; FIG.5 is a view similar to FIG.1 with the damping device shown in a drive position; FIG 6 is a view similar to FIG 1 with the damping device shown in an over-run position, FIG 7 is an axial cut away view taken along the line FF of FIG 8 of a second embodiment of a damping device according to the present invention, FIG 8 is a radial view taken along the line GG of FIG 7, FIG 9 is a radial view taken along the line HH of FIG 7, FIG 10 is a developed view taken along the line LI of FIG 1, FIG 11 is an axial cut away view taken along the line JJ of FIG 12 of a third embodiment of a damping device according to the present invention, as installed in a torque converter, FIG 12 is a radial view taken along the line KK of FIG 11, and FIG 13 is an axial cutaway view similar to Fig 5 of a fourth embodiment of a damping device according to the present invention, as installed in a twin mass flywheel With reference to FIGS 1-6 there is illustrated a twin mass flywheel 1 incorporating a damping device 10 The damping device includes first part 11 and a second part 12 which can rotate relative to each other via bearing 13 First part 11 consists of input plate 20 which is secured rotationally fast with and spaced from a plurality of cover plates 21 via respective rivets 22 and 23 Second part 12 consists of output plate 30 and pivot plate 31 secured rotationally fast to the output plate 30 via rivets 32 The damping device further consists of a plurality of linkage devices 40 and a plurality of springs 50 (in this case four linkage devices and four springs only one of each being shown in detail) Each linkage device 40 comprises an anchor link 43 pivotally connected via a first pivot 44 to the input plate 20 and corresponding cover plate 21 The linkage device 40 also includes a linkage arrangement 41 comprising a link 41 A which is pivotally connected via second pivot 45 to anchor link 43 and pivotally connected via a third pivot 42 to the output plate 30 and pivot plate 31 The anchor link 43 is in the form of a pair of plates 43 A, 43B mounted one on each axial side of the link 41A (see FIG 2) The spring 50 is generally in the form of a clock spring, that is to say a spring in which successive coils are of a reduced radius thus enabling each successive coil to be mounted radially inside its preceding coil A portion of spring 50 adjacent end 51 has a wasted section 59 to allow tabs 43 C of plates 43 A, 43B to be bent into this wasted section thus rotationally securing end 51 with anchor link 43 A substantially straight arm portion 53 extends tangentially from the coils of spring 50 towards end 52 of spring 50 End 52 is in the form of a hook Anchor link plates 43 A and 43B are mirror images of each other and each consist of a disk portion 43D with tabs 43C, an arm portion 43E and a lug portion 43F Mounted between lug portions 43F of link plates 43 A and 43B is a spacer rivet 43 G Additionally, there is provided a fiiction damping device 60 which is arranged co-axially of the first pivot 44 The friction damping device 60 consists of a belleville spring 61 which acts on input plate 20 to bias a friction plate 62 towards link plate 43B The belleville spring load is reacted via link 43 A loading fiiction plate 63 against the associated cover plate 21 The damping device 10 is installed in twin mass flywheel 1 which includes the additional components of a starter ring 2 and hub 3 and a bearing 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 the crankshaft of an engine (not shown) via bolts (not shown) which pass through holes 4 A clutch (not shown) is attached to output plate 30 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 clockwise 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 linkage devices 40, springs 50 and friction damping devices 60 The operation of each linkage device 40 and its associated spring 50 and fiiction device 60 is identical For simplicity the operation of the device will be described with reference to one linkage device 40 and its associated spring 50 and friction device 60 only Under no load conditions with the clutch disengaged, centrifugal forces act on the linkage device 40 and particularly on the link 41 A to urge link 41 A and anchor link 43 in a radially outward direction with second pivot 45 adopting a position radially outward of third pivot 42 as shown in FIG.1. 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 40 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 plates 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 FIG.1). At relatively low speeds when the influence of centrifugal force is relatively small and the input and output plates move readily relative to each other, i.e. the flywheel torsional stiflhess is relatively low. However at relatively high speeds, the influence of centrifugal force is much greater and relative rotation of the input and output plates requires greater torque i.e. torsional stiffness is relatively high. Thus, the flywheel torsional stiffness is speed sensitive. If the clutch is engaged and power is transmitted and 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 mass 20 rotates anti-clockwise relative to input plate 30 when viewing FIG.1) and the link 41 A folds between the anchor plates 43 A, 43B. Thus the controlling influence of the linkage arrangement is operable at any rotational speed of the 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. 5 and 6 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 whether relative rotation of the input plate 20 and output plate 30 is in the drive or over-run direction. This means that the spring 50 is wound up (i.e. the spring coils are tightened) as a result of any relative rotational movement from the neutral position of the input and output plates. Thus the spring 50 directly acts to resist pivotal movement of the first pivot by directly acting on the two components pivotally connected by the first pivot, i.e. the spring 50 directly acts on the anchor link 43 and the input plate 20. The spring 50 also, therefore, has the effect of resisting rotation of the input and output plates. After a predetermined amount of rotation of the input plate 20 relative to the output plate 30 in the drive direction (see FIG. 5) the spacer rivet 43G will have moved to a position so as to contact arm 53 of spring 50. Further relative rotation will cause spacer rivet 43G to bend arm 53 resulting in an increase in the torsional stiflhess of the twin mass flywheel as a whole. Yet fiirther relative rotation of the input and output plates in the drive direction causes abutment 33 of output plate 30 to contact the outside coil of spring 50 and squeezes the coil as a whole between abutments 33 and abutment 25 of spacer 24 (see FIG.5). This results in the general spiral nature of the spring coil 50 being distorted which results in a yet further increase in the torsional stiffness of twin mass flywheel. The effects of relative rotation in the over-run direction are similar except eventually abutment 34 contacts the outside coil of spring 50 and deforms the spring coils between abutment 34 and pivot 44 (see FIG 6) However in this case there is no diametrically opposed abutment equivalent to abutment 25 of spacer 24 It can therefore be seen that the spring 50 is acted upon in three distinct and independent manners resulting in the torsional stiffness of the twin mass flywheel being progressively increased In this case the first manner is the winding up of the spring coils, i e rotation of one end 51 of spring 50 relative to the other end 52 The second manner is the deflection an arm portion 53 adjacent to one end of the spring and third manner is to apply a force to the coils in a radial direction with regard to the axis of the coils to squash or otherwise distort the coils It should be noted that rotation of the anchor link 43 relative to pivot 44 is not proportional to the rotation of the input plate 20 relative to output plate 30 For example, with the damping device in its neutral position a one degree rotation of the input plates relative to the output plate causes only a small rotation of anchor link 43 relative to its pivot 44 However as the damping device approaches its limit of relative rotation in either the drive or over-run directions, a one degree rotation of the input plates relative to the output plate causes a relatively larger rotation of the anchor link 43 relative to its pivot 44 This effect means that having the spacer rivet 43 G contact the arm 53 when the input plate is near the end of its rotation relative to the output plate causes a higher increase in torsional stiflhess of the twin mass flywheel than if the spacer rivet 43 G were to 10 contact the arm 53 when the twin mass flywheel was in its neutral position This can be particularly advantageous Friction plate 62 is rotationally fast with input plate 20 since tabs 62 A of the plate 62 engage holes 20A of input plate 20 In a fiirther embodiment it is possible for friction plate 62 to rotate relative to input plate 20 to a limited degree, i e to produce lost motion between friction plate 62 and input plate 20 During relative rotation of the input and output plates fiiction is generated between fiiction plate 62 and anchor link 43B Friction is also generated either between anchor link 43A and fiiction plate 63 or between fiiction plate 63 and cover plate 21 depending upon the relative friction coefficients of these components with one another It should be noted that the movement of fiictionally engaging surfaces of the fiiction damping device is not proportional to relative rotation of the input and output plates (see explanation above in relation to movement of the anchor link 43) and this can be particularly advantageous for a friction device The concept of a fiiction damper acting directly on the components pivotally connected by a pivot of the linkage device and which may be arranged co-axially of the pivot is applicable independently from the concept of having a damper including a spring which is stressed in at least two independent manners or any other inventive concept outlined herein FIGS 7-10 show a second embodiment of a twin mass flywheel 101 incoφorating a damping device 110 similar to twin mass flywheel 1 and damping device 10 of FIGS 1-6, with components of the twin mass flywheel 110 which perform the same fimction as components of the twin mass flywheel 1 labelled 100 greater 11 Notable differences are as follows. Third pivot 142 comprises a pin 146 rotationally fast with link 141 A (in this case via an interference fit). The pin projects on either lateral side of link 141 A when viewing FIG 8 and the ends of the pins act as bearings and can rotate relative to bushes 147 A and 147B which are secured by an interference fit rotationally fast in pivot plate 131 and output plate 130 respectively. This has the advantage of increasing the bearing surface of the pivot when compared with pivot 42 without increasing the overall axial length of twin mass flywheel. Spring 150 is constructed from wire with a round cross-section and consists of a pair of adjacent coils 154A and 154B connected via a bridging portion 155 near the centre of the coils. Each coil has an arm 156 projecting substantially tangentially from the coils 154A and 154B. Each arm 156 is substantially U-shaped with one portion 156A connecting the bridging portion 156C of the U- shaped arm to the spring coils and a further portion 156B acting as a cantilevered beam, that is to say the end of arm 156B adjacent bridging portion 156C being supported (in this case by rivet 123) and the other end of arm 156B being unsupported. Anchor link 143 is in the form of a pair of mirror image links 143 A, 143B. However each anchor link 143A, 143B has a notch 143H which in combination with bridging portion 155 of spring 150 ensures that end 151 of spring 50 is rotationally fast with anchor link 143. 12 In an alternative embodiment which is not shown in the drawings, rather than a single spring 150 having a pair of adjacent coils 154A, 154B connected by a bridging portion, two separate coil springs could be used each having an end portion for engagement with the anchor link 143. Rotation of input plate 120 relative to output plate 130 causes the spring 150 to be acted upon as follows: - a) The spring 150 is initially wound up b) Rivet 143G acts in a cantilever fashion on arm 156B c) End 157 of arm 156B contacts a mid portion of arm portion 156A d) Spring coils 154 are compressed between abutments 133 and 125 in the drive direction or abutment 134 and first pivot 144 in the over-run direction. Friction damping device 160 is arranged co-axially of the pivot 144. The belleville spring 161 and fiiction plate 162 are identical to their counteφarts in twin mass flywheel 1. However fiiction plate 162 abuts a second friction plate 164 which is independent of the anchor plates 143A, 143B. The belleville spring load is reacted via bush 165 and third friction plate 166 against cover plate 121. Second and third fiiction plates 164 and 166 are secured rotationally fast to anchor link 143 via bush 165. FIGS.11 and 12 show a third embodiment of a damping device 210 installed in a fluid flywheel 205, similar to the damping device 10 of FIGS. 1 to 6 with similar components labelled 200 greater. In this case the fluid flywheel is a torque converter though in further embodiments it could be a Fottinger coupling. 13 Operation of the damping device is substantially the same as previously described in relation to damping device 10. For a full explanation of how the linkage device operates in a fluid flywheel see the applicants prior patent application PCT/GB97/00362. In summary, torque from the engine crankshaft 270 is transmitted via flex plate 271, housing 272, input impeller 273, hydraulic fluid 274, output impeller 275, and hub 275A to the gear box (not shown). However when clutch 276 is engaged the majority of torque is transmitted via input plate 220 and cover plate 221 (in the form of a single annular plate) through the damping device 210, output plate 230 and pivot plate 231 via splined connection 276 and hub 275 A to the gear box. In this case there is no fiiction device but other embodiments may include a fiiction device. Although the invention has been described in relation to embodiments in which the damper spring is a clock spring, the invention could equally be applied to dampers having any other suitable form of spring such as a helical or leaf spring for example. Figure 13 shows a further embodiment twin mass flywheel incoφorating a damping device which is similar to the flywheel disclosed in the applicant's co-pending UK patent application GB 9803048 to which the reader is referred for further details. The damping device comprises an anchor link 343 pivotally connected via a first pivot 344 to a first part 311 and having a 14 torque transmitting connection 341 with a second part 312. The torque transmitting connection 341 comprises a generally circumferentially extending linkage 360 pivotally connected to the anchor link 343 via a second pivot 345 and two circumferentially spaced main links 341 A pivotally connected via third pivots 342 to the second part. The main links being interconnected by the circumferentially extending linkage 360 via fourth pivots 362. One end of a helical compression spring 350 is contacted by a spring abutment portion 361 on one end of the circumferentially extending linkage 360. The other end of the spring contacts an abutment 370 mounted to the first part 311. The geometry of the device is such that relative rotational displacement in either direction between the first 311 and second 312 parts results in compression of the spring 350 between abutments 361 and 370. In accordance with the present invention, the spring 350 is also stressed following clockwise (as viewed in Fig. 13) rotational displacement of the first part 311 relative to the second part 312, i.e. during drive conditions, by the coils being squeezed between abutment 333 on the second part 312 and abutment 324 on the first part 311. The spring 350 may comprise a pair of springs one mounted inside the other.

Claims: 15 CLAIMS 1. A damping device for use in a drive line, the device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount in response to torsional vibrations and/or torque fluctuations in the drive line, said first and second parts forming, in use, part of a torque transmission path of the drive line, the device also including a spring which is stressed in at least two independent manners to resist relative rotation of the first and second parts and hence damp said vibrations and/or fluctuations. 2. A damping device as defined in claim 1 in which the spring is stressed in a third independent manner to resist relative rotation of the first and second parts. 3. A damping device as defined in claims 1 or 2 in which the spring is a coil spring and one of the manners of stressing the spring is by rotating a first end of the spring relative to a second end of the spring about the axis of the coils. 4. A damping device as defined in claims 1 or 2 in which the spring is a coil spring and one of the manners of stressing the spring is by applying a force to at least one coil in a radial direction with regard to the axis of the coil. 16 5. A damping device as defined in claims 3 or 4 in which the coil spring is a spirally wound spring. 6. A damping device as defined in claims 3 or 4 in which the coil spring is a helically wound spring. 7. A damping device as defined in any one of claims 1, 2, 3, 4 or 6 in which the spring is a helically wound spring and one of the manners of stressing the spring is by altering the axial length of the spring. 8. A damping device as defined in any one of claims 1 to 7 in which the spring includes an arm portion and one of the manners of stressing the spring is by applying a force substantially peφendicular to the arm portion. 9. A damping device as defined in claim 8 in which the spring includes two arm portions which are stressed sequentially. 10. A damping device as defined in any one of claims 1 to 9 which also includes 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. 17 11. A damping device as defined in claim 10 in which the linkage device fiirther 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. 12. A damping device as defined in claim 10 or 11 in which the torque transmitting connection is in the form of a sliding or rolling connection acting on a track. 13. A damping device as defined in claim 11 in which the linkage arrangement comprises a second link pivotally connected to the second part by a third pivot. 14. A damping device as defined in claim 11 in which the linkage arrangement comprises a plurality of circumferentially spaced main links pivotaUy connected via third pivots to the second part with circumferentially adjacent main links being interconnected via fourth pivots on a generally circumferentially extending connecting linkage. 15. A damping device as defined in any one of claims 10 to 14 in which the spring acts directly on the components pivotally connected by one of the pivots of the linkage device to resist relative rotational movement between those components. 16. A damping device as defined in claim 15 in which the spring acts directly on the anchor link and the first part to the resist relative rotational movement therebetween. 18 A damping device as defined in any one of claims 10 to 14 in which two springs act directly on the components pivotally connected by one of the pivots of the linkage device both springs being stressed in at least two independent manners to resist relative rotational movement between those components A damping device as defined in any one of claims 1 to 17 fiirther comprising fiiction means acting to resist relative rotation of the first and second parts A damping device as defined in claim 18 when dependent on any of claims 10 to 18 in which the friction means acts directly on the components pivotally connected by one of the pivots of the linkage device to resist relative rotational movement between the components A damping device as defined in claim 19 in which the fiiction means is arranged co-axially with the pivot of the linkage device A damping device as defined in any of claims 18 to 20 in which the fiiction device consists of a fiiction plate being biased into engagement with a relatively rotatable friction surface by a bias means A damping device as defined in any of claims 18 to 21 in which no relative rotation takes place between the bias means and an adjacent friction plate 19 23. A damping device for use in a drive line, the device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount in response to torsional vibrations and/or torque fluctuations in the drive line, the first and second parts being interconnected by at least one linkage means, the device further comprising a fiiction damper which acts directly on components pivotally connected by a pivot of the linkage means to resist relative rotation of the first and second parts and hence damp said vibrations and/or fluctuations. 24 A damping device as defined in claim 23 in which the friction damper is arranged co-axially with the pivot of the linkage means. 25. A damping device as defined in any one of claims 1 to 22 in which the spring is initially stressed in a first manner during relative rotation of the first and second parts and is stressed in a second independent manner only in end ranges of travel of said relative rotation. 26. A damping device as defined in claim 25 in which the spring is stressed in a third independent manner after stressing in said second manner has already commenced. 27. A damping device as defined in any of claims 10 to 22 or claim 25 or claim 26, all when dependent on claim 10, in which the linkage device includes a link pivotally connected by a pin with the first or second part via a pair of spaced apart bearing surfaces in the said first or second part. 20 A damping device for use in a drive line, the 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 in response to torsional vibrations and/or torque fluctuations in the drive line, the damping device also including at least one linkage device to resist relative rotation of the first and second parts and hence damp the said vibrations and/or fluctuations, the linkage device including a link pivotally connected by a pin with the first or second part via a pair of spaced apart bearing surfaces in the said first or second part A twin mass flywheel incoφorating a damping device as defined in any preceding claim A fottinger coupling incoφorating a damper device as defined in any one of claims 1 to 28 A torque converter fluid coupling incoφorating a damper device as defined in any one of claims 1 to 28 A damping device constructed and arranged substantially as hereinbefore described with reference to and as shown in figures 1 to 6 or 7 to 10 or 11 to 12 or 13 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