CLUTCH DRIVE MEMBER

Abstract: A drive member (13) for a fluid pressure engaged clutch has two generally annular components (15, 16) fixed together to define a radially extending box-section to both stiffen the drive member and provide a duct (18) for the passage of fluid under pressure to engage the clutch. Several radial ducts may be provided for the passage of fluid under pressure to separate users.

Description: "Clutch Drive Member" This invention relates to drive members for fluid pressure engaged friction clutches particularly though not exclusively for use in motor vehicle transmissions. For motor vehicles it is important that such clutches have a small axial length in order to reduce the overall length of the transmission to a minimum. This is especially so for small transverse-engined front wheel drive motor vehicles where the available space for transmission installation can be seriously limited by the vehicle suspension and steering systems. A fluid pressure engaged clutch usually incorporates piston means in the drive member operable to clamp a clutch driven member for transmission of drive. One problem with such drive members is to form the hydraulic cylinder for the piston in an economical manner. Drive members manufactured from solid material are expensive and heavy, moreover the material chosen is not always ideal for use both as a hydraulic cylinder and as a drive transmitting member. Fabricated drive members are not easy to manufacture to the desired tolerances. A further problem is to provide a passage way in the drive member for supply of fluid under pressure to the cylinder. The ideal drive member must also be rigid, light and not increase the transmission length unduly. According to the present invention there is provided a drive member for fluid pressure engaged clutch characterised thereby that the member comprises two generally annular components fixed together to define a radially extending boxsection to both stiffen the drive member and provide a duct for the passage of fluid under pressure to engage the clutch. Such a drive member has the usual advantages of a box-section of being both light and strong and is moreover economical to manufacture. In one embodiment the drive member comprises two annular sheet metal pressings only, the clutch including a hydraulic cylinder having a piston responsive to fluid under pressure to engage the clutch, said piston being entrained for rotation with the drive member by tags sheared out of one wall of said box-section and for location in corresponding recesses of the piston. This provides an extremely economical and space saving way of driving the piston. Hitherto connection has been made by, for example, precision machined splines or rivetted straps between the piston and the drive member. The shearing operation also provides a convenient fluid opening from the box-section to the piston. In an alternative embodiment the annular components of the drive member are fixed together by a plurality of rivets at two or more radially seperate pitch circles of the drive member. Thus is provided an easily fabricated drive member having a plate member for transmission of torque, preferably stamped from sheet steel, and a cylinder body member preferably die cast in aluminium for accuracy and light weight. The drive member is by virtue of its construction rigid and provides a convenient fluid passageway to the cylinder. Other features of the invention are included in the following description of three preferred embodiments shown, by way of example only, in the accompanying drawings, in which: Fig. 1 is an axial section through a fluid pressure actuated clutch according to one embodiment of the invention; Fig. 2 is an axial section through a fluid pressure actuated clutch according to a second embodiment of the invention; and Fig. 3 is an axial section through a fluid pressure actuated clutch according to a third embodiment of the invention. With reference to Fig. 1 a clutch input shaft 11 has a radial flange 12 to which a clutch drive member 13 is attached by rivets 14. The drive member 13 comprises inner and outer annular metal pressings, respectively 15 and 16, fixed together for example by soldering, welding or adhesives. The outer pressing 16 has radial ribs 17 pressed therein in the manner of corrugations to form radial passages 18 on assembly with the inner pressing 15. On assembly the ribs 17 each complete a box-section which substantially stiffens the radial wall of the cover member. An annular wall 19 is attached to the inner pressing 15, by for example welding, and together with an axial portion 21 of the drive member 13, defines a hydraulic chamber for an annular piston 22. Tags 23 sheared out of the inner pressing 15 locate in recesses 24 of the piston 22 to both prevent relative angular movement between the piston 22 and drive member 13 and provide fluid communication from the passages 18 to the piston. The tags 23 allow limited axial movement of the piston 22 relative to the drive member 13. A clutch driven plate 25 has friction linings for engagement respectively with the piston 22 and a reaction plate 26 attached to the drive member 13 by screws 27. The plate 25 is attached to an output shaft 28 by rivets 29. An annular corrugated return spring 31 acts to urge the reaction plate 26 and piston 22 apart. A fluid passage 32 is provided in the input shaft 11 for communication with the radial passages 18. In operation fluid pressure is admitted through the passages 32 and 18 to urge the piston 22 against the effect of the return spring 31 to clamp the driven plate 25. It may be seen that the drive member 13 is very narrow whilst being inherently stiff, as a consequence the member l3 is both space saving and light. It will be realised that the shape and number of tags 23 and corresponding recesses 24 may be dependent on the size and duty of the clutch but that it is their function rather than the particular shape chosen which is the primary factor. With Withreference to Fig. 2 there is shown drive member having seperate ducts for the passage of fluid under pressure to actuate two clutches. An input shaft 31 is connected to the impeller 32 of a torque converter 33. The turbine 34 is connected to a drive member 35 which in turn drives an output shaft 36. A clutch 37 is enclosed within the impeller housing and includes a driven plate 38 engagable with a drive face of the turbine 34, by an annular piston 39, the plate 38 being connected to an annular shaft 41 co-axial about the output shaft 36. A hydraulic chamber for the piston 39 is defined by the drive member 35 and by an annular cylinder 42 welded to the member 35. A corrugated return spring 43 is provided between the piston 39 and the turbine 34. The drive member 35 comprises inner and outer metal pressings, respectively 44 and 45, fixed together by, for example, soldering, welding or adhesives. The outer pressing 45 has radial ribs 46 pressed therein to form radial passages on assembly with the inner pressing 44. Each rib 46 forms part of a radial box-section which substantially stiffens the radial wall of the drive member. Tags 47 sheared out of the inner pressing 44 locate in recesses 48 of the piston 39 to prevent relative angular movement between the piston and the drive member 35, as previously described. Fluid under pressure to actuate the clutch 37 is supplied through a bore 49 of the output shaft 36 through one or more radial passages 51 formed by the radial ribs 46. The sheared tag 47 conveniently provides fluid communication from the passage 51 to the back face of the piston 39. A lock up clutch 52, housed in the torus of the torque converter, is provided to couple together the impeller 32 and turbine 34 at low speed differentials. The clutch plate 53 is. engaged by a piston 54 dogged to and slidable in an annular bore of the turbine 34. Fluid under pressure to actuate the lock up clutch 52 is supplied through the annular space between the shafts 36 and 41 and at least one other radial passage 55 formed by the radial ribs 46. A fluid duct 56 through the turbine blading provides fluid communication to the back face of the piston 54. In operation either of the clutches 37 and 52 can be independently engaged by admission of fluid under pressure to the appropriate actuating piston. The box-section construction of the drive member 35 provides a light strong component which takes up little axial length whilst being very economical to manufacture. The number of fluid passages 51,55 can be chosen to suit the operating conditions of the appropriate clutch and also the number and size of the tags 47. In use the torque converter 33 may be used to drive a vehicle transmission through the output shaft 36 and a power take off device through the clutch 37 and the output shaft 41. Alternatively the torque converter and clutch may be used in a rotary transmission of the type disclosed in European Patent Application No. 0 034 412A and where all speed ratios are driven through the torque converter. Other types of dual clutch device' using a drive member as described may be envisaged, for example a conventional dual clutch for a motor vehicle having one clutch for vehicle drive and another for a power take off device. Further radial ducts may be used for supply of fluid for other purposes, for example cooling. A third embodiment of the invention is shown in Fig. 3. With reference to the drawing there is shown a clutch drive member comprising an annular plate member 61 secured to an annular reaction member 62, for example by bolts 63. The plate member is secured fast for rotation with an input member 64 for example by welding 65. The walls of a hydraulic cylinder are defined by aluminium castings 66, 67. The inner wall member 66 extends radially inwardly to the input member 64 to define, with the plate member 61 a hydraulic passage 68. A plurality of shouldered studs or rivets 69 welded to the plate member 61 pass through corresponding apertures of the wall member 66 to be riveted over. The studs 69 both retain the members 61 and 16 for rotation together and define the passage 18. The outer wall member 67 is retained against rotation by splines 71 formed on the inner wall of the reaction member 62. The studs are provided on at least two radially seperate pitch circles of the drive member to provide an effective box section. The splines 71 are principally to support a pressure plate 72 between a piston 73 and one friction face of a conventional clutch driven plate 74. The other friction face is for engagement with an inwardly extending flange 75 of the reaction member 62. The driven plate 74 has the usual splined hub for co-operation with a splined output shaft (not shown). A light corrugated spring 76 urges the pressure plate 72 and hence piston 73 away from the reaction member 62 to release the driven plate 74. Engagement of the clutch is effected by passage of hydraulic fluid under pressure through the duct 68 to the rear face of the piston 73. The plate member 61 is preferably of steel for strength whilst the castings 66,67 are of aluminium for accuracy and light weight. Other means for spacing the members 61 and 66 apart are envisaged, such as bosses or ribs on the member 66, and the method of attachment to the input member 64 could be by screws or bolts. In this way a composite drive member may be manufactured using materials to their best advantage whilst retaining a box-section construction for both strength and to define the fluid passageway.

Claims: Claims 1. A drive member (13) for a fluid pressure engaged clutch characterised thereby that the member (13) comprises two generally annular components (15,16) fixed together to define a radially extending box-section to both stiffen the drive member and provide a duct (18) for the passage of fluid under pressure to engage the clutch. 2. A drive member according to Claim 1, characterised thereby that an axially extending portion of one of said annular components (15,16) defines a wall (21) of a hydraulic cylinder responsive to fluid under pressure in said duct. 3. A drive member according to Claim 2, characterised thereby that the drive member comprises two sheet metal pressings (15,16) only. 4. A drive member according to Claim 3, characterised thereby that one of said pressings (16) is corrugated to define multiple radially extending box-sections. 5. A drive member according to Claim 3 or Claim 4, characterised thereby that a tag (23) sheared out of one box-section wall provides both a drive member for a piston (22) of'the cylinder and an opening for fluid communication between said duct (18) and said cylinder. 6. A drive member according to any of Claims 3 - 5 characterised thereby that an additional fluid duct (55) is-provided in the drive member, the additional duct (55) being for a second individually operable fluid pressure engagable clutch (52). 7. A drive member according to Claim 2, characterised thereby that the annular components are fixed together by a plurality of rivets (69) at two or more radially seperate pitch circles of the drive member. 8. A drive member according to Claim 7, characterised thereby that the rivets (69) are shouldered to space apart the annular components (61,66).

Inventors: BURKE, JOHN PIUS, STANBRIDGE, PETER JOHN
Applicants: AUTOMOTIVE PRODUCTS PUBLIC LIMITED COMPANY
Application year: 1982
Main classification: F16D25
IPC codes: F16D25