Abstract:
A torsion damper for a motor vehicle clutch comprising, between an entrance component ( 11 ) and an exit component ( 12 ), a pre-damper (C), an intermediate damper (B) and a main damper (A). The intermediate damper (B) guide washer ( 20 B), axially furthest from the main damper (A) disk ( 22 A) has axial pins ( 33 ) to block it rotation on said disk ( 22 A) passing right through said disk ( 22 A), and which, shaped like hooks ( 35 ) capable of elastic deformation beyond said disk ( 22 A), can be engaged on the latter to constitute a subassembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns torsional damper devices of the type used in the construction of a motor vehicle friction clutch, for example. 
     2. Description of Related Art 
     Torsional damper devices of the above kind usually include, between an input member and an output member rotatable relative to each other, two dampers which, in kinematic terms, come into action successively upon relative angular movement between the input member and the output member, namely, in the reverse order to that in which they come into action, a main damper and a pre-damper, each of these dampers including two guide washers which, disposed on respective opposite axial sides of a web, are rotatable relative to the web, circumferentially acting spring means disposed circumferentially between the guide washers and the web, and friction means which, operative between the guide washers and the web or parts constrained to rotate therewith, are acted on by axially acting spring means. 
     In the construction of a friction clutch the input member is for example a disc which carries friction linings at its periphery which are clamped between the pressure plate and the reaction plate of the clutch and the output member is for example a hub adapted to be constrained to rotate with the input shaft of a gearbox. 
     The function of the dampers is to filter out vibrations caused by the engine, when idling in the case of the pre-damper and in normal operation in the case of the main damper. 
     To satisfy particular operating conditions document FR-A-2 735 548, to which this patent application explicitly refers, proposes the provision of a third or intermediate damper which comes into action after the pre-damper and before the main damper. 
     The above document also proposes pre-assembly of some of the components to form sub-assemblies, in order to reduce assembly time. 
     Accordingly, a first sub-assembly, in which the pre-damper is pre-assembled to the output member and/or a second sub-assembly in which a friction washer forming part of the friction means of the main damper is pre-assembled to the guide washer of the main damper at the shorter distance from the friction washer can be provided, if required. 
     SUMMARY OF THE INVENTION 
     The aim of the invention is to develop a sub-assembly form of construction of the above kind to reduce assembly time further. 
     To be more precise, it consists in a torsional damper device of the kind briefly described hereinabove and which includes an intermediate damper, said torsional damper device being generally characterised in that the guide washer of the intermediate damper at the greater axial distance from the web of the main damper has axial tenons constraining it to rotate with said web and said tenons pass completely through said web, are shaped to form elastically deformable hooks beyond said web and are adapted to clip onto said web. 
     Accordingly, if required, a third sub-assembly can advantageously be constructed within the torsional damper device comprising the web of the main damper, the web of the intermediate damper, the circumferentially acting spring members of the intermediate damper and the guide washer of the intermediate damper at the greater axial distance from the web of the main damper, with a friction washer between the web of the main damper and that of the intermediate damper. 
     The axially acting spring means of the intermediate damper are advantageously operative between the guide washer of the pre-damper at the greater axial distance from the web of the main damper and a retaining washer with coupling means adapted to operate axially between said retaining washer and the guide washer of the pre-damper at the shorter axial distance from the web of the main damper. 
     Accordingly the axially acting spring means of the intermediate damper are advantageously joined onto the first sub-assembly. 
     If, as disclosed in document FR-A-2 735 548, the guide washer of the pre-damper at the shorter axial distance from the web of the main damper is formed by the web of the intermediate damper, this latter web is shared by the first sub-assembly and the third sub-assembly and if required these two sub-assemblies can then together form part of a larger sub-assembly, to the further benefit of assembly time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the invention will emerge from the following description given by way of example and with reference to the accompanying diagrammatic drawings, in which: 
     FIG. 1 is a view in axial section of a torsional damper device in accordance with the invention; 
     FIG. 2 shows the detail II from FIG. 1 to a larger scale; and 
     FIGS. 3 through 7 are views in axial section relating to respective sub-assemblies that can be formed from certain of the components of the torsional damper device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The figures show a torsional damper device  10  of the type described in the previously mentioned document FR-A-2 735 548. 
     Accordingly the torsional damper device  10  does not need to be described in complete detail here and, as and when required, the description of document FR-A-2 735 548 must be deemed to constitute an integral part of the present description. 
     The torsional damper device  10  includes three dampers A, B, C between an input member  11  and an output member  12  that are rotatable relative to each other. In kinematic terms the three dampers come into action successively upon relative angular movement between the input member  11  and the output member  12 , namely, and in the reverse order to that in which they come into action, a main damper A, an intermediate damper B and a pre-damper C. 
     Because the present example refers to a motor vehicle friction clutch, here the input member  11  is a disc  13  carrying annular friction linings  14  at its periphery and on both faces. 
     Here the output member  12  is a hub with internal splines  15 , a reduced height external portion  16  at one end and an external frustoconical bearing surface  17  at the other end, with splines  18  between them. 
     At the same end as the reduced height portion  16  the output member  12  has a transverse shoulder  19  continuous with the corresponding end edge of the splines  18 . 
     The dampers A, B, C each comprise respective pairs of guide washers  20 A- 21 A,  20 B- 21 B,  20 C- 21 C which, on respective opposite axial sides of a respective web  22 A,  22 B,  22 C, can rotate relative to the web within particular relative angular movement limits, respective circumferentially acting spring means  20 A,  23 B,  23 C disposed circumferentially between the guide washers  20 A- 21 A,  20 B- 21 B,  20 C- 21 C and the web  22 A,  22 B,  22 C and respective friction means  25 A,  25 B,  25 C operative between the guide washers  20 A- 21 A,  20 B- 21 B,  20 C- 21 C and the web  22 A,  22 B,  22 C or parts constrained to rotate therewith, are acted on by respective axially acting spring means  26 A,  26 B,  26 C. 
     Here the guide washers  20 A,  21 A of the main damper A are fastened together and held a particular distance apart by spacers  27  at their periphery and by which the disc  13  carrying the friction linings  14  is fastened to the guide washer  20 A. 
     The spacers  27  pass with circumferential clearance through notches  28  provided for this purpose at the outside periphery of the web  22 A and co-operate with the ends of the notches  28  to define the limits of angular movement of the guide washers  20 A,  21 A relative to the web  22 A. 
     The web  22 A also has notches  29  at its inside periphery, through which it meshes with circumferential clearance with the splines  18  of the output member  12 . 
     The circumferentially acting spring means  23 A of the main damper A are partly located inside windows  30  in the guide washers  20 A,  21 A and partly inside facing windows  31  in the web  22 A. 
     Here each comprises two elongate coaxial coil springs substantially tangential to a circumference of the assembly. 
     Here the intermediate damper B and the pre-damper C are both on the same axial side of the web  22 A of the main damper A, between that web  22 A and the guide washer  20 A. 
     They are therefore both axially between the guide washers  20 A,  21 A of the main damper A. 
     The intermediate damper B, which surrounds the pre-damper C, is for the most part radially under, i.e. short of, the circumferentially acting spring means  23 A of the main damper A. 
     Its guide washer  21 B is formed by the web  22 A of the main damper A, to be more precise by the radially innermost portion of that web  22 A. 
     Its guide washer  20 B is a synthetic material confinement member disposed axially in contact with the guide washer  20 A of the main damper A. 
     The guide washer  20 B, which is the guide washer of the intermediate damper B at the greater axial distance from the web  22 A of the main damper A, has axial tenons  33  constraining it to rotate with the web  22 A, the tenons  33  engaging with notches  34  provided for this purpose in the edges of the windows  31  in the web  22 A. 
     In accordance with the invention the tenons  33  pass completely through the web  22 A, are shaped to form elastically deformable hooks  35  beyond the web  22 A and are adapted to clip onto the web. 
     At its inside periphery the web  22 B has notches  36  which mesh with circumferential clearance with the splines  18  on the output member  12 , but the clearance here is less than that of the web  22 A of the main damper A. 
     The circumferentially acting spring means  23 B of the intermediate damper B are engaged partly in recesses  37  in the guide washer  20 B and in windows  38  in the guide washer  21 B and partly in facing windows  39  in the web  22 B. 
     Here each comprises two elongate coaxial coil springs substantially tangential to a circumference of the assembly. 
     Here the limits of relative angular movement between the guide washers  20 B,  21 B of the intermediate damper B and the web  22 B thereof are defined by the circumferential ends of the notches  29  in the web  22 A of the main damper A abutting on the splines  18  of the output member  12 . 
     Here one of the guide washers  20 C,  21 C of the pre-damper C is formed by the web  22 B of the intermediate damper B, to be more precise by the radially innermost portion of that web  22 B. 
     Here it is the guide washer  21 C at the shorter axial distance from the web  22 A of the main damper A. 
     The two guide washers  20 C,  21 C of the pre-damper C are constrained to rotate together by axial lugs  40  on one of them engaged with corresponding notches  41  on the other of them. 
     Here the guide washer  20 C,  21 C with the axial lugs  40  is the guide washer  21 C at the shorter axial distance from the web  22 A of the main damper A and the notches  41  are at the outside periphery of the guide washer  20 C. 
     The axial lugs  40  therefore extend away from the web  22 A of the main damper A. 
     Here the axial lugs  40  are formed in windows  39  of the web  22 B of the intermediate damper B, the material constituting them normally being removed in forming the windows  39  (FIG.  4 ). 
     Here the web  22 C of the pre-damper C is constrained to rotate with the output member  12 , its inside periphery being engaged with and crimped to a reduced height portion of the splines  18  of the output member  12 . 
     The circumferentially acting spring members  23 C of the pre-damper C are partly engaged in windows  43  in the guide washers  20 C,  21 C and partly in facing windows  44  in the web  22 C. 
     Here each comprises an elongate coil spring substantially tangential to a circumference of the assembly. 
     Here the limits of relative angular movement between the guide washers  20 C,  21 C of the pre-damper C and its web  22 C are defined by circumferential ends of the notches  36  in the web  22 B of the intermediate damper B abutting against the splines  18  of the output member  12 . 
     The friction means  25 A of the main damper A include, in addition to the guide washer  20 B of the intermediate damper B, a friction washer  45  on the opposite side of the web  22 A to the guide washer  20 B and in contact with the web  22 A. 
     The associated axially acting spring means  26 A are here in the form of a Belleville washer that bears on the corresponding guide washer  21 A of the main damper A. 
     Here the friction washer  45  is substantially leveL with the guide washer  20 B and therefore at a distance from the output member  12 . 
     Here the friction washer  45  has axial tenons  46  which are offset radially away from the output member  12  and constrain it to rotate with the nearer guide washer  21 A of the main damper A, the tenons  46  engaging with openings  48  provided for this purpose in the guide washer  21 A. 
     The tenons  46  advantageously pass completely through the guide washer  21 A, are shaped as elastically deformable hooks  49  beyond the guide washer  21 A and are adapted to clip onto the guide washer. 
     The tenons  46  are also used to centre the Belleville washer constituting the axially acting spring means  26 A. 
     Here the friction means  25 C of the pre-damper C include, on the one hand, a bearing  50  operative between the output member  12  and one of the guide washers  20 A,  21 A of the main damper A, here the guide washer  20 A, to centre the guide washer  20 A, and which has a frustoconical bearing surface  51  through which it bears on the frustoconical bearing surface  17  of the output member  12  and, on the other hand, a friction washer  52  at the other end of the output member  12  which bears on the transverse shoulder  19  of the output member  12 , possibly through an intermediate washer, not shown. 
     The friction washer  52  has axial tenons  53  constraining it to rotate with the guide washer  21 A of the main damper A, the tenons  53  engaging with notches  54  provided for this purpose at the inside periphery of the guide washer  21 A. 
     Similarly, the bearing  50  is constrained to rotate with the guide washer  20 C of the pre-damper C by tenons that cannot be seen in the figures. 
     Here the associated axially acting spring means  26 C are formed by a Belleville washer which is centred by the tenons  53  with which it is engaged via notches  55 . 
     For reasons that will become apparent hereinafter, the friction washer  45  forming part of the friction means  25 A of the main damper A has a radial extension  56  towards the axis of the assembly adapted to retain the friction washer  52  that is part of the friction means  25 C of the pre-damper C. 
     The radial extension  56  can be circumferentially continuous or subdivided into radial lugs. 
     In accordance with the invention the axially acting spring means  26 B of the intermediate damper B are operative between the guide washer  20 C of the pre-damper C at the greater axial distance from the web  22 A of the main damper A and a retaining washer  57  with coupling means  58  operative axially between the retaining washer  57  and the guide washer  21 C of the pre-damper C at the shorter axial distance from the web  22 A of the main damper A. 
     Here the coupling means  58  comprise axial lugs  59  on the retaining washer  57  extending towards the web  22 A of the main damper A and shaped to form hooks  60  at their ends and detents  61  on the guide washer  21 C of the pre-damper C at the shorter axial distance from the web  22 A of the main damper A. 
     Here the detents  61  are each formed by the edge of an opening  62  provided for this purpose in the axial lugs  40  of the guide washer  22 C of the pre-damper C. 
     Here the axial lugs  40  of the guide washer  22 C extend a right-angle lip  64  on the guide washer  22 C against which the guide washer  20 C abuts in the axial direction. 
     Here the retaining washer  57  is one piece with the bearing  50  and the axially acting spring means  26 B of the intermediate damper B comprise a Belleville washer centred by the tenons constraining the bearing  50  to rotate with the guide washer  20 C of the pre-damper C, which has notches engaged with the tenons. 
     The friction means  25 B of the intermediate damper B comprise a friction washer  67  disposed axially between the web  22 A of the main damper A and the web  22 B of the intermediate damper B. 
     Here the friction washer  67  meshes with clearance with the output member  12 . 
     To this ends its inside periphery incorporates notches  68  engaging with clearance on the splines  18  of the output member  12 . 
     Here the friction washer  67  has windows  69  in which the circumferentially acting spring members  23 C of the pre-damper C are axially engaged, which reduces the overall axial size of the assembly. 
     The corresponding arrangements are described in document EP-A-0 732 525 which may be referred to for more information, in particular with regard to the width of the windows  69 . 
     Here the outside periphery of the friction washer  67  incorporates notches  70  in which the circumferentially acting spring members  23 B of the intermediate damper B are axially engaged, so that the friction washer  67  is subject to a return spring effect of the circumferentially acting spring members  23 B. 
     It follows from the foregoing description that various sub-assemblies are constituted or can be constituted within the torsional damper device  10 . 
     Firstly there is a first sub-assembly I comprising the output member  12 , the pre-damper C, the axially acting spring means  26 B of the intermediate damper B and the retaining washer  57 , the web  22 C of the pre-damper C being axially keyed to the output member  12  to retain the assembly relative to it. 
     The first sub-assembly I is shown separately in FIG.  6 . 
     Note that on the side at the axially greater distance from the web  22 A of the main damper A, it is the retaining washer  57  that axially closes the first sub-assembly I. 
     Then there is a second sub-assembly II comprising the web  22 A of the main damper A, the web  22 B of the intermediate damper B, the circumferentially acting spring members  23 B of the intermediate damper B and the guide washer  20 B of the intermediate damper B at the greater axial distance from the web  22 A of the main damper A, with the friction washer  67  forming part of the friction means  25 B of the intermediate damper B between the web  22 A of the main damper A and the web  22 B of the intermediate damper B. 
     The second sub-assembly II is shown separately in FIG.  4 . 
     Finally there is a third sub-assembly III comprising at least the guide washer  21 A concerned of the main damper A, the friction washer  45  which forms part of the friction means  25 A of the main damper A and is constrained to rotate with the guide washer  21 A and the axially acting spring means  26 A of the main damper A between the guide washer  21 A and the friction washer  45 . 
     The third sub-assembly III is shown separately in FIG.  5 . 
     Here it also includes the friction washer  52  forming part of the friction means  25 C of the pre-damper C and the axially acting spring means  26 C of the pre-damper C between the friction washer  52  and the corresponding guide washer  21 A of the main damper A, the friction washer  52  being retained by the radial extension  56  of the friction washer  45 . 
     This being the case, the assembly procedure can be as follows. 
     As shown in FIGS. 3 through 5, for example, the first step is to produce a sub-assembly I′ formed exclusively of the output member  12  and the web  22 C of the pre-damper C and then to stack this sub-assembly I′ with the second sub-assembly II, the third sub-assembly III and the other components of the torsional damper device  10 . 
     However, the first sub-assembly I described hereinabove and the second sub-assembly II preferably and advantageously share the web  22 B of the intermediate damper B and the first sub-assembly I and the second sub-assembly II are first assembled separately, as shown in FIGS. 3 and 5, and then joined together. 
     They then form a larger sub-assembly I-II shown in FIG.  7 . 
     The sub-assembly I-II is then stacked as previously with the third sub-assembly III and the other components of the torsional damper device  10 . 
     The stiffness of the circumferentially acting spring members  23 C of the pre-damper C is less than that of the circumferentially acting spring members  23 B of the intermediate damper B which is in turn less than that of the circumferentially acting spring members  23 A of the main damper A. 
     The stiffness of the axially acting spring means  26 C of the pre-damper C is lower than that of the axially acting spring means  26 B of the intermediate damper B which is in turn less than that of the axially acting spring means  26 A of the main damper A. 
     When the input member  11  and the output member  12  rotate relative to each other in operation only the circumferentially acting spring members  23 C of the pre-damper C are initially compressed. 
     At this time only the friction means  25 C of the pre-damper C are operative. 
     The circumferentially acting spring members  23 B of the intermediate damper B and the members  23 A of the main damper A constrain the guide washers  20 C,  21 C of the pre-damper C to rotate with the guide washers  20 A,  21 A of the damper A with which the friction washer  52  constituting the friction means  25 C is constrained to rotate, and likewise the bearing  50  through the intermediary of the guide washer  20 C of the pre-damper C. 
     The circumferentially acting spring members  23 B of the intermediate damper B are then compressed but the circumferentially acting spring members  23 C of the pre-damper C remain compressed. 
     At the same time the friction means  25 B of the intermediate damper B add their effects to those of the friction means  25 C of the pre-damper C. 
     The guide washer  21 B of the intermediate damper B, constrained to rotate with the output member  12 , turns relative to the web  22 A of the main damper A and, with a certain time-delay due to the corresponding circumferential clearance, the same goes for the friction washer  67  disposed axially between the guide washer  22 B and the web  22 A and forming the friction means  25 B of the intermediate damper B. 
     Finally, the circumferentially acting spring members  23 A of the main damper A are compressed but the circumferentially acting spring members  23 B of the intermediate damper B and those  23 C of the pre-damper C remain compressed. 
     At the same time, the friction means  25 A of the main damper A come into action, adding their effects to those of the friction means  25 C of the pre-damper C, but the friction means  25 B of the intermediate damper B are not operative. 
     The guide washer  21 C of the pre-damper C and the web  22 A of the main damper A between which the friction washer  67  constituting the friction means  25 B is operative are then both constrained to rotate with the output member  12 . 
     Consequently, on relative angular movement between the input member  11  and the output member  12 , the pre-damper C directly upstream of the output member  12  is the first to come into action, the intermediate damper B is the second to come into action and the main damper A, which in kinematic terms is driven directly by the input member  11 , is the third and last to come into action. 
     It follows from the aforegoing description that the three dampers A, B, C are disposed in series. 
     If required their circumferentially acting spring members  23 A,  23 B,  23 C can be pre-stressed in their respective housings (windows  30 ,  38 ,  43  or recesses  37 ). In this case, the torque applied by the members  23 C at the end of their intervention is greater than the torque applied by the members  23 B at the beginning of their intervention. The torque applied by the members  23 B at the end of their intervention is greater than the torque applied by the members  23 A at the beginning of their intervention. 
     To prevent discontinuous operation the final torque of the pre-damper C can be greater than the pre-stressing of the circumferentially acting spring member  23 B of the intermediate damper B and the final torque of the intermediate damper B can be greater than the pre-stressing of the circumferentially acting spring members  23 A of the main damper A. 
     The hooks  35 ,  49  are advantageously in one piece with the corresponding tenons  33 ,  46  and are preferably narrower than the tenons in the circumferential direction so as not to contribute to the transmission of torque, which reduces the stresses on them. 
     Of course, the invention is not limited to the embodiment described and shown but encompasses any variant execution within the scope of the claims. 
     For example the axially acting spring means employed can consist at least in part in a corrugated washer. 
     Also, all the embodiments disclosed in document FR-A-2 735 548 can be envisaged.