WO2014194358A1

WO2014194358A1 - A clutch plate

Info

Publication number: WO2014194358A1
Application number: PCT/AU2014/000579
Authority: WO
Inventors: Damian Michael BIBBY
Original assignee: Clutch Industries Pty Ltd
Priority date: 2013-06-04
Filing date: 2014-06-03
Publication date: 2014-12-11
Also published as: CN105431648A; EP3004676A1; EP3004676A4; CN105431648B

Abstract

A clutch plate (10) including a plate assembly (11, 12), a hub (20) for connection to an output shaft and a hub flange (24) which is drivable by the plate assembly (11, 12) to rotate. The hub (20) being drivable to rotate by the hub flange (24). The plate assembly (11, 12) and the hub flange (24) being coupled together by a drive arrangement, (30, 31) that permits angular displacement between the plate assembly (11, 12) and the hub flange (24) within a predetermined range. The drive arrangement (30, 31) comprises a pair of curved drive assemblies (30, 31), mounted concentrically about the hub (20) and being at least partially positioned between the first and second plates (11, 12). The drive assemblies (30 and 31) apply a biasing load against relative angular displacement between the plate assembly (11, 12) and the hub flange (24). The drive assemblies (30, 31) each include a plurality of adjacent housing segments (32), which define cavities between them and positioned in the cavities are resilient dampers (33). Angular displacement between the plate assembly (11 and 12) and the hub flange (24) in a first direction causes movement of the housing segments (32) towards each other to deform the dampers (33) and to increase the biasing load against further relative angular displacement.

Description

A CLUTCH PLATE

TECHNICAL FIELD

[0001] The present invention relates to a friction clutch assembly, principally for use in the automotive sector, for manual transmission cars and trucks. The present invention is particularly directed to the clutch plate of a friction clutch assembly and it will be convenient to describe the invention as it relates to that application.

BACKGROUND OF INVENTION

[0002] The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.

[0003] A friction dutch assembly or "clutch" of a car or other automobile having a manual transmission or gearbox is generally located between the engine and the drive train. The components between the engine and the drive train normally includes several adjacent annular plates, including a flywheel that is rotatably driven by the engine output (a crank shaft usually), a clutch plate (otherwise known as a driven plate), and a pressure plate that is biased by energy storing devices, such as one or more springs, towards the clutch plate and flywheel to clamp the clutch plate between the flywheel and the pressure plate.

[0004] The clutch of a vehicle operates on frictional engagement between coupling faces of the clutch plate with adjacent coupling faces of the flywheel and the pressure plate to allow the clutch plate to transfer power generated by the engine to the remainder of the drive train (commencing with the gearbox). However, unless there is some form of dampening in the drive line to dissipate the irregular impulses which are a natural occurrence of an internal combustion petrol or diesel engine, these impulses will create unwanted driveiine noise and vibration.

[0005] To prevent transmission of engine impulses through to the gearbox, prior art clutch plates include drive springs for dampening purposes. The drive springs are typically coil springs. Thus, a typical clutch plate includes a splined hub that accepts a splined shaft to transmit engine rotation to the gearbox or transmission. The splined hub is connected to a hub flange, either rigidly or with some angular displacement for dampening engine vibration at idle ("idle vibration"), and the hub flange is sandwiched between a main plate and a side plate which are fixed together. The hub flange is driven to rotate when the main plate is shifted into frictiona! engagement with the flywheel of an engine through a friction materia! fixed to the circumferential edge of the main plate. The main and side plate assembly (hereinafter the "plate assembly") and the hub flange are connected by drive springs to provide limited angular displacement between them by small contractions and expansions of the drive springs in response to the irregular impulses of the engine. The angular displacement is provided to dampen torsional vibration in the drive and overrun modes of the vehicle (as compared to other vibration such as idle vibration),

[0006] The drive springs are normally straight springs, and in the past, normally 3 or 4 springs are provided, spaced equidistantly about the splined hub. The preference for using straight coil compression springs arises on the basis that they are easy to manufacture and are therefore inexpensive. Straight drive springs have also been preferred to date because such drive springs can also operate without the need for guides along their length, to maintain them straight. This has the consequential benefits that the springs do not rub on other components of the clutch assembly, which would otherwise cause wear and generate heat, both of which can be detrimental to the life of the clutch plate.

[0007] The amount of dampening available in a clutch is increased as the length of the drive springs increases, as that increases the amount of angular displacement available between the hub flange and the plate assembly. However, the as the length of a straight drive spring is increased, the spring load can move out of alignment with the axis of the spring and that can reduce the normal compressive strength of the spring, The spring can actually be forced into a trapezoidal shape by the hub flange acting against the side and main plates of the clutch plate through the spring. Moreover, the space available in a clutch is very limited and therefore an increase in spring length is not always available. [0008] Applicant has investigated clutch plates that employ curved drive springs. Such springs can allow increased length as compared to straight springs and thus advantageously increase the available dampening and angular displacement. Curved drive springs have been disclosed in JP8121535 (A). That patent disclosed a curved spring with a larger diameter center coil and identified spring wear and subsequent spring failure as the problem to be solved. The patent went on to propose a solution to the wear and failure issue.

[0009] The subject matter of Applicant's co-pending Internationa! Patent Application PCT/AU2012/000610 also discloses the use of curved drive springs. That disclosure recognises potential problems associated with curved drive springs, including that when curved drive springs are used to transmit engine torque, the springs are naturally forced radially outwards, bringing them into engagement with other parts of the clutch plate, including the clutch plate housing, causing them to rub against those parts. That rubbing can cause heat, wear, noise, erratic torque dampening and premature failure of the springs.

[0010] Applicant therefore developed an arrangement in which the drive springs are disposed partially within a sleeve which protects the springs from rubbing engagement with other parts of the clutch plate, but still allows the curved drive springs to be used and to function properly.

[0011] Applicant has continued to develop clutch plates In order to improve damping characteristics and angular displacement and the present invention goes to such a new arrangement.

SUMMARY OF INVENTION

[0012] According to the present invention there is provided a clutch plate including:

a plate assembly comprising axially spaced first and second plates and having an annular periphery extending from the first plate to which an assembly of friction material is applied to face in each of opposite directions,

a hub for connection to an output shaft,

a hub flange positioned between the first and second plates and being drivable by the plate assembly to rotate, the hub being drivab!e to rotate by the hub flange,

the plate assembly and the hub flange being coupled together by a drive arrangement that permits angular displacement between the plate assembly and the hub flange within a predetermined range,

the drive arrangement comprising a pair of curved drive assemblies mounted concentricaily about the hub and being at least partly positioned between the first and second plates, each end of the drive assemblies being in engagement with an abutment of the hub flange and an abutment of the plate assembly, the drive assemblies applying a biasing load against relative angular displacement between the plate assembly and the hub flange,

each of the drive assemblies including a plurality of resilient dampers and a housing, the housing being formed from a plurality of adjacent housing segments arranged in a curve that are movable relative to each other and which define cavities between the segments within which the dampers are housed, the dampers being in contact with facing surfaces of adjacent housing segments, whereby

angular displacement between the plate assembly and the hub flange in a first direction causes movement of adjacent housing segments towards each other which shifts the facing surfaces of the housing segments towards each other and deforms the dampers located within the cavities between adjacent housing segments, increasing the biasing load against further relative angular displacement between the plate assembly and the hub flange,

the housing segments being in sliding bearing engagement with a bearing surface of the plate assembly and sliding relative to the bearing surface upon angular displacement between the piate assembly and the hub flange,

[0013] The present invention also provides a clutch in which the clutch plate described above is employed.

[0014] The resilient dampers used in the clutch plate can be of any suitable type or material, Metal spring coils can be used as dampers. Alternatively, non-metallic materials or members that are deformable and that can resiliently return or recover from a deformed condition can be used as dampers. Such non-metallic material or member dampers include polymeric dampers, elastomeric or rubber dampers, plastic dampers, resilient foams of either open or closed ceil formation. The dampers can be natural or synthetic. The dampers can be of concertina or bellows configuration. The requirement is for the damper to aliow for angular displacement between the piafe assembly and the hub flange in the first direction under a torsional load in that direction, and to promote reverse angular displacement once the torsional load is released or reduced. Any form of damper that can act in that manner is an acceptable damper for use in the clutch plate of the present invention.

[0015] The dampers can be constructed from a single material, or a combination of materials or damper components can be employed. Thus, the drive assemblies can comprise a plurality of different dampers, such as elastomeric dampers between some housing segments and coil springs between others and these types of arrangements will be discussed later herein. Individual dampers can comprise a combination of materials. This type of damper construction can provide for further enhancement or refinement of the damper characteristics.

[0016] individual dampers can comprise a constant spring rate or a variable spring rate. For a constant spring rate, the dampers can have a constant hardness and constant cross-sectional area. A damper of this form wiii have a linear curve when plotting angular displacement between the plate assembly and the hub flange relative to the torque applied to create that displacement (the so-called "torque angularity curve").

[0017] For a variable spring rate, the dampers can have a variable or non- constant cross-sectional area. As an example of a damper having a variable spring rate, the cross-section could be relatively small through the first 20% of damper compression under load, and then the cross-section could increase for the remaining 80% of damper compression under load. A damper of this form will give a two stage linear torque angularity curve which reflects light dampening over the first 20% of the anguiar displacement between the plate assembly and the hub flange, and greater or full dampening over the remainder of the angular displacement,

[0018] A variable spring rate can alternatively be provided in a damper by varying the hardness of the damper. This can be achieved by constructing the damper from different materials of different hardness. For example, varying hardness elastomers can be laminated together to achieve light dampening over the first portion of the angular displacement between the plate assembly and the hub flange, and greater or full dampening over the remainder of the angular displacement, in this manner, there can be a graded dampening over the full extent of angular displacement. For example, there could be three levels of dampening comprising light, medium and heavy dampening. A greater number of levels couid be provided as required.

[0019] A variable spring rate can alternatively be provided in a damper by varying the cross-section and the hardness of the damper. Other arrangements could also be employed.

[0020] Deformation of the dampers can be by compression of the dampers to change the shape of the dampers without a reduction in volume of the damper, or with negligible change. Alternatively, deformation by compression can include a shape and/or volume reduction, i.e. the damper reduces in size with or without changing shape. Alternatively, deformation can be by a combination of both. For example, a damper might fill the cavity between adjacent housing segments, so that when the housing segments shift towards each other and the volume of the cavity between them reduces, the damper deforms by a compression that involves a volume reduction in the damper. Alternatively, the cavity can be of a greater volume than the damper so that when the housing segments shift towards each other, the volume of the cavity reduces and the damper deforms by a compression that involves a change of shape of the damper without a reduction in the volume of the damper, or with negligible change. The damper thus deforms in a manner to shift into the available space of the cavity. Alternatively, the cavity can be of a greater volume than the damper, but the volume is such that the damper will fill the cavity prior to the maximum angular displacement between the plate assembly and the hub flange and thereafter the further deformation is by volume reduction.

[0021] Where resilient deformation of a damper takes place without a change in volume of the damper or with negligible change, the damper is most likely an eiastomeric damper. Many elastomeric materials suitable for use in the present invention could have some volume change during deformation, but either negligible change or very small change. [ΟΟ223 Where the deformation is by a resilient damper deforming into the available space of the cavity, it is not a requirement that the damper fill the available space in the cavity upon reaching the maximum angular displacement between the plate assembly and the hub flange. At that maximum displacement, the cavity might fill the damper to 90% or 80% for example.

[0023] In some forms of the invention, the resilient dampers deform radialiy as the housing segments move towards each other. The radial deformation can be in one direction only, such as radially outwards or inwards, or in both radial directions.

[0024] The dampers can be any suitable shape. Suitable shapes include circular (which is preferred), generally polygonal such as square and rectangular, and oval. This is not an exhaustive list and any suitable shape can be employed. As indicated above, the shape can vary in relation to cross-section to vary the dampening spring rate.

[0025] Prior to the maximum angular displacement between the plate assembly and the hub flange being reached, the housing segments can be spaced from each other so that the housing segments can shift towards each other to permit further angular displacement. The housing segments can be arranged to engage each other at the point of maximum angular displacement to prevent further angular displacement. This arrangement advantageously removes the need for prior art stop pins to be employed. This arrangement advantageously allows the maximum angular displacement to be predetermined based on factors such as the initial spacing between the housing segments and the dampening capacity of the dampers.

[0026] Alternatively, the housing segments can be telescopic so that the resilient dampers are contained fully within the housing. The housing segments can include abutments that engage each other at the point of maximum angular displacement to prevent further angular displacement during telescopic movement.

[0027] The resilient dampers can be located within the housing between the housing segments in any suitable manner. In some forms of the invention, each of the facing surfaces of adjacent housing segments includes a projection that the damper deforms about to locate the damper. Alternatively, only one of the facing surfaces can include a projection. The projection can be a single projection, or a plurality of projections. For example a series of outwardly projecting dimples can be formed in one or each of the facing surfaces. The projection or projections can project only a relatively small distance from the facing surfaces. The projection or projections can have any suitable shape, such as annular, or they could be formed as a thread

[0028] Alternatively, one of each of the facing surfaces can be a rough surface to provide a friction grip with the damper.

[0029] Alternatively, one of each of the facing surfaces can include a recess, indent or groove, or a plurality of recesses, indents or grooves that the damper can deform into for location of the damper.

[0030] Contact between the facing surfaces of adjacent housing segments by the resilient dampers is important to maintain the drive assemblies properly located in the clutch plate. The drive assemblies can be installed in a compressed condition against abutments at either end of the assemblies and radially outer surfaces of the housing segments can bear against a facing bearing surface formed by the plate assembly. The installation of the drive assemblies in compression in this manner allows the assemblies to maintain a curved configuration without further guide surfaces.

[0031] The abutments referred to above can engage with the ends of the drive assemblies in any suitable manner and simple bearing engagement can be employed in some forms of the invention. In other forms of the invention, there can be a more positive engagement with the ends of the assemblies. For example, the abutments could include a projection that engages with recesses formed in the ends of the assemblies, or the assembly ends can include a projection and the abutments include a recess. Alternatively, the drive assemblies could be fixed to the abutments such as by adhesive or by screws or rivets.

[0032] Advantageously, the drive assemblies of the present invention can remove the need for stop pins as currently used in prior art clutch plates. Stop pins are currently provided for safety against overload of the clutch plate and can be removed and their function taken by the drive assemblies. As explained above, the function of the stop pins can be taken by arranging the housing segments to engage each other at the point of maximum angular displacement to prevent further angular displacement.

[0033] Any number of resilient dampers can be employed in each drive assembly. The minimum number is two dampers between three housing segments. However, a greater number of dampers is expected to be preferred and some forms of the invention have been developed with eleven elastomeric dampers between twelve housing segments. Alternative combinations include four elastomeric dampers between five housing segments, six elastomeric dampers between seven housing segments and eight elastomeric dampers between nine housing segments. Equally, five, seven and nine elastomeric dampers can be employed between six, eight and ten housing segments.

[0034] The above figures represent damper and housing segment numbers for smaller clutch plates such as 10' clutch plates. For larger clutch plates, such as 15' plates, up to 30 housing segments could be employed in each drive assembly, so that a dutch plate could include up to 60 housing segments. As wil! be appreciated, larger clutch plates could have larger numbers of housing segments again.

[0035] While in some forms of the invention the housing segments can all be movable through the same distance or angle, in other forms of the invention, the movement available to the housing segments can vary. For example, some housing segments can be spaced apart by a 3° arc, while oth er housing segments can be spaced apart by a 6° arc. Other arc spacings can b e adopted. Where some housing segments are spaced apart by a greater arc than other housing segments, the cavity formed between the housing segments of greater spacing can be larger and in larger cavities, a larger resilient damper can be housed. By varying the cavity size and the size of the dampers, and by varying the amount of angular movement available to the housing segments, the characteristics of the drive assemblies can be modified and tuned.

[0036] The housing segments are preferably formed from materials having a low coefficient of friction, typically plastic materials, so that they can slide freely against bearing surfaces of the plate assembly. The housing segments should also be capable of handling heat generated not only by the movement of the housing segments relative to the bearing surface of the plate assembly, but also by other components of the clutch assembly, such as heat generated by the friction material of the clutch plate rubbing on the flywheel and the pressure plate. Suitable materials include high temperature plastics, metal bearing materials such as bronze, white metal or similar, graphite/metal alloys, graphite/bronze alloys, iron or copper graphite alloys, or ceramics. These are example materials and do not constitute and exhaustive list.

[0037] The housing segments of plastic can be formed in any suitable manner, such as by injection moulding.

[0038] The amount of angular displacement between the plate assembly and the hub flange in drive and overrun directions can be varied to suit the requirements of the clutch plate. The lower end of angular displacement can be for example, 6° and the higher end could be 60°. The displacement angle s can alternatively be any amount in-between. This compares favourably with prior art clutch plates.

[0039] While the expectation is that a pair of drive assemblies will be included in a clutch assembly according to the invention, three or more drive assemblies can be provided, such as four drive assemblies.

[0040] The bearing surface of the plate assembly will be a concave surface and in some forms of the invention, the bearing surface has a base surface and a pair of diverging wall surfaces. The base surface can extend substantially perpendicular to the general plane of the plate assembly and the diverging wall surfaces can extend from the base surface at approximately 60°. In thi s form of the invention, the facing surface of the housing segments can be formed substantially the same so that there is close surface to surface contact between an outer surface of the housing segments and the bearing surface.

[0041] The bearing surface can be formed partially by the first and second plates of the plate assembly, whereby one of the diverging wall surfaces is formed by the first plate and the base and the other of the diverging wall surfaces is formed by the second plate, or the bearing surface can be formed in a symmetrical manner whereby each of the first and second plates forms both a diverging wall surface and a portion of the base surface. [0042] Wide angularity, or in other words, wide angular displacement between the piate assembly and the hub flange is an aim of the present invention to provide. By arranging the drive assemblies in a curve, the length of the drive assemblies is greater than if the drive assemblies were straight. By increasing the length of the drive assemblies, greater angularity can be achieved.

[0043] Angularity can be increased or decreased by appropriate selection of housing segments and resilient dampers. As indicated above, movement of the housing segments towards each other as anguiar displacement between the plate assembly and the hub fiange occurs can be limited to a predetermined maximum amount by the housing segments engaging each other at the predetermined maximum angular displacement. Moreover, the plate assembly and the hub flange have a "home" position when there is no torsional load on the clutch plate and which is between the drive and overrun directions of the angular movement and at that position, the housing segments can be spaced apart sufficient amounts to allow the required angular displacement. For example, in some forms of the invention, spacing between the housing segments can be about a 3° arc with the maximum angular displacement available being the total of the number of spacings in the drive assembly. Thus, where there are eleven spacings and each spacing is 3°, the total maximum angular displacement is 33° on each side of the home position, so 33° in each of the drive and overrun directions. The spacing between housing segments can be increased or decreased as required.

[0044] in the example given above, each housing segment will shift on the bearing surface of the plate assembly in either of the drive and overrun directions up to the maximum anguiar displacement provided between the housing segments. However, the arrangement is intended that the maximum anguiar displacement will only rarely be reached and under only maximum load conditions. In the normal running of the clutch plate, the housing segments will not engage each other as the angular displacement in the drive assemblies wiil be less than the maximum angular displacement. Obviously, various factors determine how much angular displacement occurs under torsional load and these include the inherent resistance to deformation of the resilient dampers, the spacing between housing segments, or the spacing between abutments of the housing segments and the curved length of the drive assemblies.

[0045] The discussion above has been made in relation to drive assemblies that principally employ elastomeric dampers between housing segments. While the invention extends to arrangements in which different resilient dampers are employed, such as non-elastomeric resilient dampers, the invention also extends to arrangements in which the drive assemblies include combinations of different dampers. In some forms of the invention, coil springs can be employed between some of the housing segments while elastomeric dampers (for example) are employed between other housing segments. The axis of the coil springs wouid extend between the facing surfaces of the housing segments and the axis could be slightly curved. For example, the drive assemblies could include twelve housing segments and between those segments could be six elastomeric dampers and five coil springs. The arrangement could be that the coil springs could be positioned between pairs of elastomeric dampers. Alternative arrangements could include two or more coil springs located adjacent one another, with elastomeric dampers to either side or one side of the coil springs.

[0046] In all forms of the invention, the characteristics of the drive assemblies can be modified by:

varying the size, shape or volume of the resilient dampers,

varying the hardness of the resilient dampers,

varying the cavity size,

varying the spacing of the housing segments,

varying the total length of the curved drive assemblies, and

varying the number of segments and resilient dampers of the drive assemblies.

[0047] in some forms of the invention that employ non-elastomeric dampers, such as coil springs or resilient foams, the characteristics of the drive assemblies can be modified by varying the characteristics of the non-elastomeric dampers. Thus, for coii springs, the spring constant of the springs could be varied as an example. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order that the invention may be more fully understood, some embodiments will now be described with reference to the drawings in which:

[0049] Figure 1 is a f perspective view of a clutch piate according to the invention.

[0050] Figure 2 is a plan view of a drive assembly according to the invention.

[0051] Figures 3 and 4 are unloaded and loaded views of a portion of the drive assembly of Figure 2.

[0052] Figure 5 is a cross-sectional view radially through the hub of Figure 1 to the friction facings.

[0053] Figures 6 and 7 are plan views of alternative arrangements of drive assemblies according to the invention.

[0054] Figures 8 and 9 are unloaded and loaded views of a portion of an alternative drive assembly.

DETAILED DESCRIPTION

[0055] With reference to Figures 1 , a clutch plate 10 is illustrated. The dutch plate 10 includes main and side plates 11 and 12, a plurality of facing segments 13 which are fixed to the main plate 11 , and friction facings 14 and 15 which are fixed to each side of the facing segments 13. in practice, the facing segments 13 and the friction facings 14 and 15 extend for the full circumference of the side plate 11 , but in Figure 1 , a gap is shown in the facing segments 13 and the friction facings 14 and 15 for clarity purposes. The technique of fixing the facing segments 13 to the main plate 11 is well known. Likewise, the technique for fixing the friction facings 14 and 15 to the facing segments 13 is also well known.

[0056] The clutch plate 10 includes a hub 20, which includes an internally spiined surface 21. The internal surface 21 is sized to accept a complementary spiined shaft (not shown) which connects to a vehicle transmission or gearbox. The spline connection between the hub 20 and the shaft allows axial movement of the shaft relative to the hub 20, but constrains the shaft to rotate with the hub 20 when the hub 20 is rotated.

[0057] Figure 1 includes a cross-sectional portion to show that the hub 20 further inciudes a radially short flange 24 which is integrally formed with a radially larger flange 27. The radial flange 27 includes a pair of abutments 28.

[0058] Figure 1 also illustrates curved drive assemblies 30 and 31. The drive assembiies 30 and 31 are of substantially the same length and are of a constant radius of curvature. The drive assemblies 30 and 31 are mounted concentrically about the hub 20 and are spaced equidistantly about the hub 20. One end of each of the assemblies 30 and 31 engages against the abutments 28 of the flange 27, while the opposite ends of the assembiies 30 and 31 engage against abutments 29 of the plates 11 and 12, The arrangement is such that the hub 20 and the flanges 24 and 27 are rotatably or angularly displaceable relative to the plates 11 and 12 for damping purposes by virtue of compression and expansion of the drive assembiies 30 and 31. While the arrangement illustrated in Figure 1 is very different to prior art arrangements, the damping effect is similar, except that the illustrated clutch plate 10 is considered to have superior damping characteristics as will be apparent from the discussion herein.

[0059] Each of the drive assemblies 30 and 31 includes a housing that comprises a plurality of housing segments 32, and which houses a plurality of dampers 33. The dampers 33 are e!astomeric dampers and will be referred to as such in the subsequent discussion. In Figure 1 , the drive assembly 31 is shown partially cut away to illustrate the housing segments 32 and the e!astomeric dampers 33 more clearly.

[0060] The elastomeric dampers 33 are circular as shown at reference number 34. in cross section, at reference numeral 35, it can be seen that the dampers include a central recess on each side to receive a projection that extends from adjacent housing segments 32, Figure 2 illustrates this arrangement also and shows a complete cross sectional view of the drive assembly 31 iilustrating the damper recesses 36 and the housing segment projections 37. [0061] Each housing segment 32 comprises a central wall or web 38 and a radial flange, which, in the cross-sectional view of Figure 2 comprises radially inner and outer end flanges 39 and 40, The end flanges 39 and 40 form a continuous and circular fiange as shown at reference numeral 34 in Figure 1. In a rest or home position of the drive assemblies 30 and 31 , which occurs when there is no torsional load on the clutch plate 10 in either the drive or overrun directions, the radially inner and outer surfaces 42 and 43 of the dampers 33 are spaced from facing surfaces 44 and 45 of the flanges 39 and 40. That spacing between the surfaces 42 and 43, and the facing surfaces 44 and 45, is the space into which the dampers 33 expand upon torsional load being applied to the drive assembly 31. In this respect, the dampers 33 are incompressible in that they can deform to change shape, but do not lose volume, or lose negligible volume, upon deformation.

[0062] The torsionaily unloaded and torstonally fully loaded conditions of the dampers 33 are illustrated in Figures 3 and 4. In Figure 3, the housing segments 32 are spaced apart through a 3° arc, while in Figure 4, the segments 32 and 33 have been pushed together to the point at which facing surfaces 46 of the respective segments 32 engage. In Figure 4, it can be seen that the damper 33 has deformed radia!ly inwardly and outwardly to almost fill the radially inner and outer spaces Si and S₂ of the cavity 47 between the segments 32.

[0063] Returning to Figure 1 , the elastomeric damper 35 is shown fully in cross sectional view, while the elastomeric damper 34 is shown without the housing segment 32 extending about it. Beyond the referenced elastomeric dampers 33, 34 and 35, the housing segments 32 fully enclose the dampers 33 as shown in relation to the drive assembly 30.

[0064] To further illustrate the clutch plate 10, Figure 5 is a cross sectional view through the friction facings 14 and 15 of the plate 10 of Figure 1 , through to the hub 20. A housing segment 32 is illustrated within which is disposed the elastomeric damper 33. Figure 5 clearly shows the spaces Si and S₂ as illustrated in Figure 3, although from the cross sectional view in Figure 5, it can be seen that the spaces Si and S₂ are part of an annular space about the circular damper 33, so that there is space within the housing segment 32 completely about the damper 33. [0065] Figure 5 further illustrates the arrangement of the recess 36 and the projection 37 to locate the damper 33 within the housing segment 32.

[0066] Figures 6 and 7 illustrate alternative versions of the invention. With reference to Figure 6, a drive assembly 49 that includes a plurality of housing segments 50 is shown between which are housed a plurality of eiastomeric dampers 51 as well as a plurality of coil springs 52. In the illustrated example, the sequence is that each spring 52 is interposed between a pair of dampers 51 , so that within the twelve segments 50, the five coil springs 52 are interposed between six eiastomeric dampers 51. in the Figure 6 arrangement, the characteristics of the drive assembly shown can be different to that of the drive assemblies 31 and 32, by the provision of the coil springs 52. Moreover, the spring constant or spring rate of the coil springs 52 can be varied throughout the drive assembly.

[0067] With reference to Figure 7, the drive assembly 55 is similar to the drive assembly 49 of Figure 6 but varies by the provision of different arcuate gaps between some of the housing segments 56 and different sizes of the eiastomeric dampers 57. For example, between the facing surfaces 58 and 59 of the housing segments 60 and 61 , a 6° gap exists. However, between the surfaces 62 and 63 between the segments 64 and 65, a 3° gap exists. The 6° gap ex ists twice in the drive assembly 55 while the 3°gap exists at all of the other gaps .

[0068] Figure 7 further illustrates relatively elongate dampers 70 compared to relatively compact dampers 71 , while the drive assembly 55 continues to include the coil springs 52 of the drive assembly 49.

[0069] It will be appreciated from Figures 6 and 7, that a wide variety of variations of the drive assemblies can be employed. Thus, eiastomeric dampers of the same or differing size can be employed with coii springs, or alternatively, non- eiastomeric dampers which are other than coil springs can be employed with eiastomeric dampers.

[0070] Moreover, the eiastomeric dampers can be of a generally incompressible form of the kind shown in Figures 3 and 4, that deform without a loss of volume, or the dampers can be compressible in the sense that a loss of volume occurs upon deformation. This is the case for example, with dampers that are of a foam material that have an open or closed cell structure that can collapse under load. Figures 8 and 9 illustrate this arrangement in which the housing segments 32 shift from the torsionaily unloaded to the torsionally fully loaded condition. In Figure 8, the volume Vi of the damper 79 is about twice the volume V₂ of the damper 79 when the housing segments have shifted together.

[0071] Figures 10 to 15 illustrate still further alternatives in relation to the use of dampers that have non-constant shape or varying hardness. Each of Figures 10 to 15 shows a pair of housing segments 85 with dampers of different characteristics located between them. The dampers can be described as follows:

- Damper 86 is of variable cross-sectional area so that light dampening takes place in the smaller cross-sectional area 87, followed by greater dampening over the larger cross-sectional area section 88.

- In figure 11 , damper 89 is of variable density, achieved by laminating together three different density materials. In damper 89₅ light dampening would take place through material 90, while medium dampening would occur through material 91 and heavy dampening would take place through material 92.

- In Figure 12, damper 95 is a combination of the characteristics of the dampers 86 and 89 of Figures 10 and 11 , so that damper 95 is comprised of a variable cross-section and variable density. Thus, section 96 is comprised of a reduced cross-sectional area 97 and greater cross-sectional area 98, while section 99 is a laminated section of different density so the sections 97 and 98 and is laminated to the section 98.

- The damper 100 of Figure 13 comprises a reduced cross-sectional section 101 which is laminated to a greater cross-sectional and greater density section 102.

[0072] Finally, in Figures 14 and 15, different forms of cross-sectional area are shown in dampers 105 and 106. Returning to Figure 1 , it can be seen that the drive assemblies 30 and 31 engage against the abutments 28 at one end and at the abutments 29 at the opposite ends. It can further be seen that the housing segments 32 (hereinafter the "end segments") that engage the abutments 28, 29 have a different construction to the housing segments 32 inboard of those end segments. With reference to Figure 2, the end segments 76 have a flat end 77 and include only a single projection 78 facing inboard.

[0073] The drive assemblies 30 and 31 are maintained in position between the abutments 28, 29 by portions of the main and side piates 11 and 12. With reference to Figures 1 and 5, the plates 11 and 12 form a recessed base 80 and a pair of side walls 81 and 82. The facing surface of the housing segments 32 is shaped complementary to the base 80 and the side walls 81 and 82. Further side walls 83 and 84 are formed and while Figure 5 shows those walls in engagement against the opposite side of the housing segment 32, it is expected that the housing segments 32 will be spaced from the walls 83 and 84, i.e. not in engagement.

[0074] As a torsional load is applied to the clutch plate 10, and as the hub flange 27 moves relative to the main and side plates 11 and 12, the housing segments 32 slide relative to each other as the eiastomeric dampers 33 deform within the segments 32 (such as shown in Figures 3 and 4), The housing segments 32 include a base 85 which slides against the base 80 of the plate 12 and by appropriate selection of a material for the housing segments that has a low co-efficient friction, sliding movement occurs easily and without significant wear or generation of heat. It will be appreciated that during drive of a vehicle that employees a clutch plate 10, there is constant relative movement between the housing segments 32 as the impulse damping of an internal combustion engine takes place. The selection of a suitable material for the housing segments 32 can also ensure that the relative movement is smooth and free from significant vibration.

[0075] The use of dampers of an eiastomeric kind is expected to allow a clutch plate according to the invention to form a smooth curve, without potential problems associated with the use of curved springs. Moreover, the characteristic of the eiastomeric dampers can be varied in hardness quite easily, giving almost an infinite array of torque versus angularity.

[0076] Throughout the description and claims of this specification the word "comprise" and variations of that word, such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps, [0077] The invention described herein is susceptible to variations, modifications and/or additions other than those specificaliy described and it is to be understood that the invention includes all such variations, modifications and/or additions which fa!! within the spirit and scope of the present disclosure.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A clutch plate including:

a hub for connection to an output shaft,

a hub flange positioned between the first and second plates and being drivable by the plate assembly to rotate,

the hub being drivable to rotate by the hub flange,

the plate assembly and the hub flange being coupled together by a drive arrangement that permits angular displacement between the plate assembly and the hub flange within a predetermined range ,

the drive arrangement comprising a pair of curved drive assemblies mounted concentrically about the hub and being at least partly positioned between the first and second plates, each end of the drive assemblies being in engagement with an abutment of the hub flange and an abutment of the plate assembly, the drive assemblies applying a biasing load against relative angular dispiacement between the plate assembly and the hub flange,

each of the drive assemblies including a plurality of resilient dampers and a housing, the housing being formed from a plurality of adjacent housing segments arranged in a curve that are movable relative to each other and which define cavities between the segments within which the resilient dampers are housed, the dampers being in contact with facing surfaces of adjacent housing segments, whereby

angular displacement between the plate assembly and the hub flange in a first direction causes movement of adjacent housing segments towards each other which shifts the facing surfaces of the housing segments towards each other and deforms the dampers located within the cavities between adjacent housing segments, increasing the biasing load against further relative angular displacement between the plate assembly and the hub flange.

2. A clutch plate according to claim 1 , the resilient dampers being elastomeric dampers.

3. A clutch plate according to claim 1 , the resilient dampers being spring coils or resilient foam of either open or closed ceil formation,

4. A clutch plate according to any one of claims 1 to 3, deformation of the resilient dampers being by changing the shape of the dampers without a reduction in volume of the dampers.

5. A clutch plate according to any one of claims 1 to 3, deformation of the resilient dampers being by changing the shape of the dampers with a reduction in volume of the dampers.

6. A clutch plate according to any one of claims 1 to 3, deformation of the resilient dampers being in a first stage by changing the shape of the dampers without a reduction in volume of the dampers and in a second stage by changing the shape of the dampers with a reduction in volume of the dampers.

7. A clutch plate according to any one of claims 1 to 6, the housing segments being spaced apart in advance of the point of maximum angular displacement between the plate assembly and the hub flange and being shiftable towards each other upon angular displacement between the plate assembly and the hub flange in the first direction.

8. A clutch plate according to claim 7, the housing segments being arranged to engage each other at the point of maximum angular dtspiacement to prevent further angular dtspiacement between the plate assembly and the hub flange in the first direction.

9. A clutch plate according to any one of claims 1 to 6, the housing segments being telescopic.

10. A clutch plate according to claim 9, the housing segments including abutments that engage each other at the point of maximum angular displacement to prevent further angular displacement between the plate assembly and the hub flange in the first direction.

11. A clutch pfate according to any one of claims 1 to 10, the resilient dampers being located within the housing between the housing segments by projections extending from the facing surfaces of the housing segments and extending into opposite sides of the resilient dampers.

12. A clutch plate according to any one of claims 1 to 11 , the drive assemblies engaging with the abutments of the hub flange and the plate assembly by bearing engagement.

13. A clutch plate according to any one of claims 1 to 12, the housing segments each being movable through the same angle during angular displacement between the plate assembly and the hub flange.

14. A dutch plate according to any one of claims 1 to 12, the angular movement of respective the housing segments during angular displacement between the plate assembly and the hub flange being variable.

15. A clutch plate according to any one of claims 1 to 12, the housing segments being spaced apart the same distance.

16. A clutch plate according to any one of claims 1 to 12, some of the housing segments being spaced apart a greater distance relative to other housing segments.

17. A clutch plate according to claim 16, the housing segments that are spaced apart a greater distance having a larger resilient damper between them relative to housing segments that are spaced apart a lesser distance.

18. A clutch plate according to any one of claims 1 to 17, one or more of the resilient dampers being of a different size to the other resilient dampers.

19. A clutch plate according to any one of claims 1 to 18, one or more of the resilient dampers being of a different shape to the other resilient dampers.

20. A dutch plate according to any one of claims 1 to 19, one or more of the resilient dampers being of a different volume to the other resilient dampers.

21. A clutch plate according to any one of claims 1 to 20, one or more of the resilient dampers being of a different hardness to the other resilient dampers,

22. A dutch plate according to any one of claims 1 to 21 , one or more of the cavities between respective housing segments being of a different size to the other cavities.

23. A clutch plate according to any one of claims 1 to 22, the spacing between the housing segments varying.

24. A clutch plate according to any one of claims 1 to 23, the shape of the resilient dampers being selected from circular, polygonal, square, rectangular, and oval.

25. A clutch plate according to any one of claims 1 to 24, drive assemblies mounted equidistantly about the hub.

26. A clutch including a dutch plate according to any one of the preceding claims.