Abstract:
The invention concerns an elastic coupling device comprising a first guide washer ( 1 ) integral in rotation with the drive washer and a disc ( 10 ) integral with a hub ( 17 ) oriented towards the first guide washer ( 1 ), which bears at its outer periphery a second guide washer. The invention is applicable to motor vehicles.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns an elastic coupling device between two aligned or substantially aligned shafts, respectively a driving shaft and a driven shaft, said device including circumferential action spring damper means mechanically disposed between the two shafts. 
     2. Description of Related Art 
     A device of the above kind is described in document FR-A-2 385 940, for example. In that document the coupling device is mounted between the crankshaft of the engine of a motor vehicle and the input shaft of a transmission, referred to as the transmission shaft. 
     The device includes a solid hub with internal splines force-fitted onto the transmission shaft and an external annular flange connected to the crankshaft by a drive plate. The hub extends axially in the opposite direction to the crankshaft. 
     Two guide washers on respective opposite sides of the flange are fixed to the hub. Springs mounted in facing housings in the guide washers and the flange elastically couple the flange to the guide washers. 
     The above solution is not entirely satisfactory because of its relatively large overall size in the axial direction. Also, it uses a large number of components. In document U.S. Pat. No. 2,787,896 the elastic coupling device has a greater overall axial size at its inside periphery. The axial overall size is large because the guide washers are fixed externally to an axially oriented annular rim on a plate. 
     SUMMARY OF THE INVENTION 
     An aim of the present invention is to provide a simple and economic way to overcome the above drawbacks. 
     In accordance with the invention an elastic coupling device of the above kind is characterised in that the drive plate is constrained to rotate with one of the guide washers, referred to as the first guide washer, while the flange is fastened, possibly after taking up circumferential play, to the hub, in that the hub is directed axially towards the first guide washer, in that the first guide washer carries the other guide washer, referred to as the second guide washer, fixed to its outside periphery, and in that said device is thicker at its outside periphery than at its inside periphery. 
     The invention considerably reduces the axial overall size of the device. Also the flange has a reduced radial overall size and is therefore more economical. 
     A starter ring gear and an inertia weight can therefore be installed radially beyond the flange to increase the inertia for the same radial overall size. 
     The first washer then carries rivets for fixing the second guide washer passing axially through said ring gear and said weight. 
     The starter ring gear and the inertia weight therefore form a spacer between the guide washers. 
     In an alternative embodiment the guide washers are in contact with the outside periphery and the rivets pass through the starter ring gear, the contacting parts of the guide washers and the inertia weight so that the guide washers are gripped between the inertia weight and the starter ring gear. 
     The rivets can of course be replaced by nut and bolt fixings or any other assembly means. In an alternative embodiment the guide washers are identical at their outside periphery and are joined face to face by virtue of being fastened together by a weld bead. One of the washers carries the inertia weight and the other carries the starter ring gear. 
     By virtue of the invention the elastic coupling device provides additional functions, in particular starting functions, in a simple and economic manner. 
     The device can have the weight required for good filtration of vibration. 
     In one embodiment the second guide washer is shorter in the radial direction than the first guide washer. To be more precise, the central opening of the second guide washer has a diameter greater than that of the first guide washer. 
     Because of this the axial overall size of the elastic coupling device can be further reduced as the flange can have a tortuous shape with a first internal portion at the level of the second guide washer offset axially relative to a main second portion between the two guide washers. 
     In one embodiment the first guide washer is in one piece with the drive plate, which economises one component. 
     The first guide washer can be fixed using fixing screws the heads of which are disposed axially between the first guide washer and the flange. The flange then has holes for access to the screw heads for turning them by means of a tool such as a screwdriver. 
     In a second embodiment the first guide washer surrounds the drive plate and is connected to it by elastic tongues in the axial direction. 
     Axial vibrations from the crankshaft of the engine of the vehicle, which is subject to axial oscillations, can therefore be damped (filtered). 
     Clearly the drive plate is then reduced to a simple washer and the first guide washer is rotationally connected to the drive plate but able to move axially relatively to it because of the tangential tongues. 
     Such damping can equally be obtained by making the first guide washer flexible, for example by providing holes in it. 
     In one embodiment the hub is in one piece with the flange of meshing means with circumferential play between the hub and the flange. In an alternative embodiment the hub is separate from the flange. The free end of the hub can be chamfered to enter the interior of the driving shaft. 
     Clearly, by virtue of the invention the elastic coupling device forms a unitary module of small axial overall size that can be tested and balanced dynamically in advance, before it is fixed to the driving shaft. 
     To this end the first guide washer has at its inside periphery first fixing means for fixing it directly or indirectly to the driving shaft and, radially beyond said first fixing means, second fixing means for fixing the second guide washer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following description illustrates the invention with reference to the accompanying drawings in which: 
     FIG. 1 is a half-view in axial section of the elastic coupling device in accordance with the invention; 
     FIG. 2 is a view in section taken along the line  2 — 2  in FIG. 3 for a second embodiment; 
     FIG. 3 is a view in the direction of the arrow  3  in FIG. 2, locally cut away and showing the inertia weight and second guide washer; 
     FIGS. 4 and 5 are views analogous to FIGS. 2 and 3 for a third embodiment, the lefthand part of FIG. 5 being a sectional view without the inertia weight and the starter ring gear being shown in dashed outline; 
     FIGS. 6 and 7 are views similar to FIGS. 2 and 3 for a fourth embodiment with two locally cut away areas in FIG. 7 to show part of the flange, the tongues and the windows; 
     FIGS. 8 and 9 are views similar to FIGS. 2 and 3 with two locally cut away areas in FIG. 9 to show the flange and the first guide washer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The device is adapted to couple two substantially aligned shafts  100 ,  200 , namely a driving shaft  100  and a driven shaft  200  (FIG.  1 ). 
     In the case of a motor vehicle application, the driving shaft  100  is the crankshaft of the internal combustion engine of the vehicle and the driven shaft  200  is the input shaft of a variable pulley type transmission (not shown). The device includes a drive plate  1  with its inside periphery fixed to the end of the crankshaft by fixing screws  4  the heads  5  of which each have an imprint (no reference number) for a tool for turning them. 
     The crankshaft  100  has an axially oriented cylindrical centering bearing surface  7  adapted to come into intimate contact with the inside periphery of the plate  1 . The crankshaft is hollow in the centre and has a chamfer  8  at its free end. 
     The elastic and rotational coupling device further includes two guide washer  1 , 9  (FIGS. 1 through 3,  8  and  9 )— 1 , 3  (FIG.  4  and  5 )— 2 , 9  (FIGS. 6 and 7) disposed on respective opposite sides of a flange  10 , the guide washer  1 — 2  constituting a first guide washer and the guide washer  3 — 9  constituting a second guide washer. 
     Circumferential action spring means  11  (FIGS. 1 through 3,  6 ,  7 ,  8 , and  9 )— 110  (FIGS. 4 and 5) are housed in housings  12 ,  13  (FIGS. 1 through 3,  6 ,  7 ,  8  and  9 )— 120 ,  130  (FIGS. 4 and 5) facing each other in the flange  10  and in the guide washers  1 , 9 — 1 , 3 — 2 , 9 , respectively. The spring means  11 ,  110  are therefore operative between the flange  10  and the guide washers  1 , 9 — 1 , 3 — 2 , 9  and are mechanically disposed between said guide washers and the flange. 
     The spring means can comprise a stack of Belleville springs, as described in document FR-A-2 385 940, to which reference may be had for more information. 
     The spring means  11 ,  110  shown here are coil springs. In FIGS. 1 through 3,  6  and  7  the springs  11  are short coil springs. In FIGS. 4 and 5 they are long curved springs  110  which can be pre-curved. In an alternative embodiment the spring means are elastomer blocks. 
     The spring means  11 ,  110  shown here are all housed without play in the housings  13 ,  130  in the guide washers. 
     The spring means  11 ,  100  can all be housed without play in the housings  12 ,  120  in the flange  10 . 
     In FIGS. 1 through 3,  6 ,  7 ,  8  and  9  and in a manner that is known in itself some of the spring means  11  are housed without play in the housings  12  in the flange  10  and others are housed with circumferential play in the housings  12 , for staggered intervention of said spring means for improved filtering of vibrations. 
     In these figures there are eight regularly distributed springs  11  and the housings  12 ,  13  are facing windows as described in document FRA-A-2 494 795, to which reference may equally be had for more information. As seen better in FIGS. 3,  7  and  9 , some windows  12  in the flange  10  have a greater circumferential length than the windows  13  in the facing guide washers  1 , 9 — 2 , 9 . All the springs  11  are mounted without play in the windows  13 . Axial action friction means  14  operate between the guide washers  1 , 9 — 1 , 3 — 2 , 9  and the flange  10 . 
     The friction means  14  are radially below the circumferential action spring means  11 ,  110  and are carried by the guide washers  1 , 9 — 1 , 3 — 2 , 9 . The friction means  14  are radially above the fixing members  4 . 
     To be more precise, and as described in the above-mentioned document FR-A-2 494 795, the friction means shown here comprise a first application washer  15  constrained to rotate with the second guide washer  9  and rubbing against the flange  10  (on the face thereof facing towards the second guide washer  3 , 9 ). A pre-stressed axial action spring washer  16 , shown here as a Belleville washer but in an alternative embodiment a corrugated washer, is inserted between the second guide washer  3 , 9  and the first application washer  15 . The application washer  15  has projections, shown here as cylindrical pins (no reference number), inserted in holes (no reference number) in the second guide washer for rotationally coupling the first application washer  15  to the second guide washer  3 , 9  with axial mobility. 
     The first application washer shown here is made of plastics material and rubs directly against the flange  10 . It is charged with glass fibres, for example. 
     A second friction washer  25  which here is exactly the same shape as the first application washer  15  faces the first application washer  15  on the opposite side of the flange  10 . 
     The washer  25  is inserted between the first guide washer  1 - 2  and the flange  10 . The washer  25  rubs against the flange  10  (on the side facing towards the first guide washer) and is rotationally coupled to the first guide washer by cylindrical pins on it inserted in holes in the first guide washer. The spring washer  16  bears on the second guide washer to urge the first application washer  15  towards the flange  10  so that the reaction force presses the second friction washer  25  against the first guide washer  1 , which is connected to the second guide washer as described below, to generate friction through contact with the flange  10 . 
     The windows  13  in the guide washers are delimited by lips for retaining the springs. 
     In an alternative embodiment the housings consist of pressed portions  130  in the guide washers  1 , 3  and notches  120  opening radially outwards in the flange  10  (see FIGS.  4  and  5 ). The notches  120  are delimited by radial lugs  121  with circumferential fingers  122  engaging in a recess in a bearing cup  123  against which the curved springs  110  bear. Shoes  124  are each clipped onto one turn of the spring  110  and are disposed between the outside periphery of the springs  110  and the inside periphery of the generally semicircular pressed portions  130  in order to reduce friction, as described in document U.S. Pat. No. 2,002,115. The cups  123  are extended at their outside periphery to form a shoe retaining the end turns of the springs  110 , there being two of them as shown here subtending an angle of substantially 180°. 
     Large ranges of relative angular movement can be obtained, as in the other figures. As shown here the guide washers  1 , 3  have identical outside peripheries. The washers are fastened together face to face at their free edge by welding them together, as described in document FR-A-2 411 999. 
     The pressed portions  130  thus form a torus at the outside periphery of the guide washers  1 , 3  of the same thickness. 
     The respective torus envelopes the major part of each spring  110 . To be more precise, the pressed portions  130  are extended at their inside periphery by transverse portions of the main parts of the guide washers. Sealing washers  40  are gripped between the flange  10  and the first friction washer  15  and the second friction washer  25 . The washers  40  are inclined beyond the washers  15 ,  25  to bear on the respective inside faces of the washers  1  and  3 , facing towards the flange  10 . This defines a fluid-tight cavity delimited by the pressed portions  130  and closed on the inside by the sealing washers. This cavity is filled with a paste-like or viscous agent such as grease in order to lubricate the springs  110 , which therefore operate under good conditions without any risk of them being pressed into the pressed portions  130  by the shoes  124 , which can be replaced by channels. 
     Facing the lugs  121  the guide washers  1 , 3  are of course flattened to form parallel flat plates  126  and bearing portions at the ends of the springs  110  mounted without play in the pressed portions  130 , interrupted by the flat parts  126 , and in the notches  120 . 
     This exploits the friction means  14 , the lugs  121  of the flange  10  entering the aforementioned cavity. 
     The washers  15 ,  25  are of course cut-out to form a centering shoulder for the sealing washer  40  concerned. 
     The friction means  14  can have a different shape but the friction means shown here are economical because they employ a small number of washers  15 ,  16 ,  25  and the friction and application washers  25 ,  15  are identical apart from their thickness. 
     Another result of this is that the two guide washers  1 , 9 — 1 , 3 — 2 - 9  have identical holes for the pins on the washers  15 ,  25 . 
     The elastic coupling device generally includes a drive plate  1  for rotationally coupling said device to the driving shaft (here the crankshaft  100 ) and a hub  17  for rotationally coupling said device to the driven shaft (here the input shaft  200 ). Between the plate  1  and the hub  17  there are two coaxial parts which can move angularly relatively to each other against circumferential action spring means  11 ,  110  and axial action friction means  14 . 
     One of these parts comprises the guide washers  1 , 9 — 2 , 9 — 1 , 3  and the other part comprises the flange  10 . 
     FIG. 1 shows the rotation axis X—X of the device, which is coincident with the axes of the substantially aligned shafts  100 ,  200 , allowing for manufacturing and assembly tolerances. 
     On relative angular movement between the guide washers  1 , 9  and the flange  10  disposed between said washers, the spring means  11  are compressed and friction is generated between the flange  10  and the friction and application washers  25 ,  15 . The same applies in the other figures. 
     In accordance with the invention, to reduce the axial overall size the first guide washers  1 , 2  are constrained to rotate with the drive plate and the flange  10  is fastened, possibly after taking up circumferential play, to the hub  17  directed axially towards the first guide washer  1  forming the drive plate. 
     In FIGS. 1 through 5 the first guide washer  1  is in one piece with the drive plate  1 . 
     This reduces the number of components of the elastic coupling device. 
     In accordance with another feature of the invention the second guide washer  3 , 9 , which has a simple shape, the flange  10  and the first guide washer  1  are fixed to the first guide washer  1 . 
     The guide washers  1 , 9 , the flange  10  and the hub  17  are metal parts. The flange  10  and the guide washers  1 , 9  are simple to manufacture by pressing. The same applies to the other figures. 
     The hub  17  can be in one piece with the flange  10 , the inside periphery of which is then in the form of a sleeve splined at the front. The flange  10  shown here is crimped to the end of the hub  17 . 
     To achieve this, and in a manner that is known in itself, the hub  17  is softer than the flange  10  and has a stepped diameter at the end opposite the first guide washer  1 . The flange  10  has splines on its inside periphery and is force-fitted onto the smaller diameter portion of the hub  17  until it abuts against the shoulder formed by the change in the diameter of the hub  17 . During this force-fitting operation the flange  10  cuts grooves in the hub  17 . 
     After this operation the material at the end of the hub  17  is peened to form a second shoulder and to lock the flange  10  in the other axial direction. The flange  10  is constrained to rotate with the hub  17  by the grooves that it has cut into it and its splines engaged in said grooves. 
     In an alternative embodiment the flange  10  is welded to the end of the hub  17 . 
     In FIG. 1 the other end of the hub  17  is joined to the fixing area of the flange  10  by a frustoconical portion  18  so that the axially projecting part of the hub  17  is chamfered. The hub  17  is thicker at the axial end adjacent the flange  10  than at the other axial end adjacent the crankshaft. The heads of the fixing screws  4  are radially above the hub  17 . 
     Accordingly, the hub  17  penetrates slightly into the interior of the crankshaft  100 , to be more precise into the interior of the central recess  16  in the crankshaft  100  previously mentioned as providing a receptacle for the free end of the input shaft  200 , which has the benefit of reducing axial overall size. The hub  17  extends partly radially below the heads  5  of the fixing screws  4  and penetrates into the interior of the chamfer  8  on the crankshaft  100 , the frustoconical portion  18  of the hub  17  being parallel to said chamfer  8 . 
     When the flange  10  forms the hub in the aforementioned manner, said hub is thinner and as a result penetrates further into the recess  6 . 
     Accordingly, in FIG. 1 the flange  10  is fastened to the hub  17  both rotationally and axially. 
     In an alternative embodiment, the flange  10  is axially fastened to the hub  17 , possibly after taking up axial play, and rotationally fastened to the hub  17  after taking up circumferential play. This can also apply in the other figures. To be more precise, in an alternative embodiment, as described in document FR-A-2 496 210 (U.S. Pat. No. 4,613,029), the flange  10  has female teeth at its inside periphery and the hub has male teeth at its outside periphery. In each case the teeth alternate with notches and both are advantageously trapezoidal. The male teeth enter the notches between the female teeth with circumferential play and the female teeth enter the notches between the male teeth with circumferential play to form meshing means with circumferential play. 
     Facing notches are formed in the male and female teeth to accommodate low-stiffness spring members for filtering vibration when the engine of the vehicle is idling. The spring members are usually coil springs with bearing plates having a dihedral dorsal surface disposed between the circumferential ends of the springs and the notches, as shown in FIG. 3 of the previously mentioned document FR-A-2 496 210, the content of which is deemed to be incorporated into the present invention. 
     The male teeth are formed in an area of increased thickness so that it is possible to delimit the male teeth laterally by two washers attached, for example welded, riveted or crimped, to the hub. The washers then plug the axial ends of the notches between the male teeth and thereby constitute axial abutments for the female teeth of the flange  10  so that the flange  10  is connected axially to the hub  17 . 
     In all cases, because of the axial locking of the flange  10  onto the hub, a module can be formed in the manner described below. 
     The first guide washer  1  has holes  36  at its inside periphery through which the threaded part of the screws  4  passes. After fitting it to the crankshaft  100  the first guide washer  1  is disposed and gripped between the crankshaft and the heads  5  of the fixing screws  4  which are regularly distributed in the circumferential direction. 
     The number of screws depends on the application. In an alternative embodiment the first guide washer  1  forming a supporting member is fixed to the crankshaft by studs or bolts, rivets or other fixing means. 
     In all cases the first guide washer  1 , 2  has first fixing means at its inside periphery for fixing it either directly or indirectly to the driving shaft, here the holes  36  through which the screws  4  pass (see FIGS.  6  and  7 ). 
     Radially beyond said first means the first guide washer  1 , 2  carries and has fixed to it the second guide washer  3 , 9 . To be more precise, the first guide washer carries the other guide washer which is fixed to its outside periphery. 
     To this end the two guide washers  1 , 9  can be connected and fixed together by means of spacers passing through the notches in the flange  10 , as described in document FR-A-2 494 795. The notches alternate circumferentially with the windows  12 , 13 . 
     In an alternative embodiment the notches are in the bottom edge of the windows. 
     In FIG. 1 the second guide washer  9  is fixed to the first guide washer  1  radially beyond the circumferential action spring means  11 , at the outside periphery of the first guide washer. 
     This fixing is effected by rivets  20  fastening the guide washers  1 , 9  together. 
     The rivets therefore pass through axially aligned openings in the guide washers and openings in axial coincidence therewith in a starter ring gear  21  in contact with the first guide washer  1  and in an inertia weight  22  in contact with the second guide washer  9 . The starter ring gear  21  and the inertia weight  22  therefore form a spacer between the two guide washers  1 , 9 , projecting radially outwards relative to said washers  1 , 9 . 
     To achieve this the first guide washer  1  has at its outside periphery a transversely oriented portion  23  offset axially outwards relative to the main part of the first guide washer  1  and thus in the opposite direction to the second guide washer  9 . The starter ring gear  21  is in contact with the portion  23 , the height of which depends on the ring gear  21 . 
     The inertia weight  22  has projections on its inside periphery in the form of lugs directed radially inwards to cooperate with notches at the outside periphery of the flange  10 . 
     The projections engage in the notches with circumferential play. Thus relative angular movement between the guide washers  1 , 9  and the flange  10  is limited by the projections coming into contact with the lateral edges concerned of the notches. 
     In an alternative embodiment such limitation is achieved by the turns of the springs  11  coming into contact. 
     Because of the portion  23  the starter ring gear  21  in FIG. 1 is offset axially relative to the flange  10  with the result that the inertia weight  22  can mesh with play with the flange  10 . The inertia weight  22  extends radially partly over the second guide washer  9 . 
     The weight  22  projects axially outwards relative to the second washer  9  by an amount corresponding to the thickness of the rivet head  20 . 
     The elastic coupling device is therefore thicker at its outside periphery than at its inside periphery and has second fixing means  20 ,  21 ,  22  separate from the first fixing means to form a unitary module that can be handled and transported separately. The device has weights (the ring gear  21  and the weight  22 ) increasing its inertia radially beyond the spring means  11 ,  110 . 
     The inertia weight  22  is softer than the starter ring gear  21  and there is therefore no need to harden the flange  10 . 
     In FIGS. 2 and 6, as in FIG. 1, the rivets  20  pass through axially aligned openings in the starter ring gear  21  and in the rings  41  and  42  respectively forming part of the first guide washer  1 , 2  and the second guide washer  9 . 
     The rings  41 ,  42  of the guide washers are therefore clamped between the parts  21 ,  22  each of which has a spot facing (no reference number) to accommodate respective opposite ends of the rivets  20 . 
     The rings  41 ,  42  are offset axially relative to the main part of the associated guide washers  1 , 2 — 9  and extend to the outside periphery of said washers. 
     The ring  41  of the guide washer  1 , 2  has lugs  43  projecting radially inwards. The lugs are obtained by cutting and bending the first guide washer  1 , 2 , producing a slot  44 . The lugs  43  are in the plane of the flange  10  and are adapted to cooperate with the edges of notches, here the notches  143 , in the flange  10  at its outside periphery to limit relative angular movement between the flange  10  and the guide washers  1 , 2 — 9 . 
     The first guide washer  1 , 2  shown here is thicker than the second guide washer  9  because its outside periphery carries the second guide washer  9 . 
     In FIGS. 4 and 5 the guide washers  1 , 3  are the same thickness for manufacturing reasons, because they are identical at their outside periphery, the first guide washer  1  carrying the second guide washer by means of a continuous weld bead (no reference number). 
     The second fixing means between the two guide washers can therefore consist in a weld or employ fixing members  20  in the form of rivets or bolts (nut and bolt system), or any other means. 
     In FIGS. 4 and 5 the inertia weight  22  extends radially above the second guide washer  3  to which it is fixed by a weld bead (no reference number). 
     Similarly the starter ring gear  21  extends radially above the first guide washer  1  to which it is fixed by a weld bead (no reference number). 
     The coupling device in accordance with the invention comprises four radial stages, namely, from the outside periphery to the inside periphery of the elastic coupling device, a first stage including the rivets  20  or the welds or other fixing means, the ring gear  21  (driven by the starter motor of the vehicle) and the inertia weight  22 , a second stage comprising the circumferential action spring means  11 ,  110 , a third stage comprising the friction means  15 ,  25 ,  16  and a fourth stage comprising the first fixing means of the first guide washer  1 . 
     This arrangement makes best use of the available space combined with providing the maximum functions and a small axial overall size. This arrangement does not required centering bearings, the guide washers  1 , 9 — 2 , 9 ,  1 - 3  extending radially beyond the hub  17 . 
     The way the distribution washers  15  and friction washers  25  are mounted enables the friction means  14  to be suspended from the guide washers  1 , 9 . 
     In an alternative embodiment at least one of the washer  25 ,  15  is replaced by a friction washer adhesively bonded to a metal washer including drive lugs engaging in holes in the guide washer concerned. 
     The flange  10  has at it inside periphery a transversely oriented portion  24  offset axially relative to the main part of the hub  10  between the two guide washers  1 , 9 . 
     The portion  24  extends radially below the friction means  14 . 
     The inside portion  24  is offset axially towards the second guide washer  3 , 9 , i.e. in the opposite axial direction to the outside portion  23  of the first guide washer  1 . This axial offset is made possible by the configuration of the second guide washer  3 , 9 , which is shorter than the first guide washer  1 . The second guide washer  3 , 9  surrounds the inside portion  24  in all cases. The inside portion penetrates into the central opening of the second guide washer  3 , 9 . 
     To be more precise, the opening in the second guide washer  3 , 9  (FIGS. 1 through 5 and  8 , 9 ) has a diameter greater than that of the opening in the first guide washer  1 , 2 , which projects radially inwards relative to the second guide washer  3 , 9 . 
     Accordingly the portion  24  of the flange can penetrate into the opening in the second guide washer by being axially offset towards said opening. 
     This does not increase the axial overall size and the heads  5  of the fixing screws can be disposed axially between the first guide washer  1  and the inside portion  24  of the flange  10 . The portion  24  has holes  26  providing access to the screw heads. The diameter of the hole  26  can be greater than that of the head  5  of the screw or less than the diameter of the head  5  of the screw  4 , as shown in the figure. 
     In the latter case the screw  4  is trapped and is fitted before the rivets  10  are inserted. 
     The first guide washer  1  facilitates assembly of the coupling device in the form of a module. The device is assembled by putting the first guide washer  1  down flat and then stacking the other components axially on the first guide washer  1 , the second guide washer completing the assembly. 
     Of course, the present invention is not limited to the embodiment described. 
     Accordingly, in FIGS. 6 and 7, the first guide washer  2  is separate from the drive plate  1  fixed by screws  4  to the crankshaft of the engine of the vehicle (not shown), as in FIG. 1, the flange  10  therefore having holes  26  as in the other figures. The drive plate  1  is simplified and is surrounded by the guide washer  2 , rotationally coupled to the drive washer by axially elastic tongues  50  and allowing axial displacement of the first guide washer  2  relative to the drive plate. 
     Thus axial vibrations generated by axial oscillations of the crankshaft can be filtered out. 
     Two diametrically opposed tongues  50  are provided here. The tongues are in the form of plates and are fixed to the inside periphery of the first guide washer  2  by rivets  150  at their outside periphery. 
     At its inside periphery each tongue  50  is fixed by two of the holes for the screws  4 , for which purpose a hollow rivet  151  is inserted in each hole (no reference number). 
     Each rivet bears against one face of the plate  1  and is peened on the other face of the plate  1 , in contact with the tongue  5 , to fix the latter. 
     The tongues  50  are therefore in contact with the face of the drive plate facing towards the flange  10 . 
     The plate  1  has lugs  160  at its outside periphery to limit axial movement of the tongues  50  before the coupling device is mounted on the crankshaft. 
     The lugs  160  are obtained by cutting and bending the plate and project axially away from the flange  10 . The lugs  160  cooperate with the inside periphery of the guide washer  2 , to be more precise with the face thereof facing away from the flange  10 . 
     In practice the lugs  160  are part of a bayonet coupling  161  between the inside periphery of the first guide washer  2  and the outside periphery of the plate  1 . 
     There are passages in the washer  2  and after the lugs  160  have been inserted in these passages the plate is rotated so that the lugs  160  face the lugs  170  of the plate  1 . 
     Accordingly, before it is fixed to the crankshaft, the washer  2  is locked axially between the lugs  160 ,  170  of the plate  1 . In service the lugs  170  limit movement of the tongues. 
     Vibration can of course be filtered by making the first guide washer  1  flexible, as shown in FIGS. 8 and 9. 
     The first guide washer then has trapezoidal holes below the windows  13 . The other reference numbers have the same significations as in FIGS. 2 and 3. 
     The first guide washer  1  can carry the starter ring gear  21  and for this purpose can have at its outside periphery a ring member directed axially towards the second guide ring  9 . The ring gear  21  is then force 20  fitted onto the ring member, which can also carry a timing mark. 
     The timing mark can of course be provided on the inertia weight  22  in FIG. 1, the outside diameter of which is equal to that of the ring gear  21 . 
     In an alternative embodiment the ring gear  21  and the weight  22  are one and the same. The weight  22  may not be needed in some cases. 
     If so, the first guide washer  1  can carry the ring gear  21  in the aforementioned manner and the rivets  10  can be replaced by spacers of the type described in document FR-A-2 494 795. 
     In an alternative embodiment the second fixing means include a ring member extending continuously from the periphery of one of the guide washers to the other, as described in document FR-A-2 411 999. 
     For example, the ring member extends radially above the flange  10 , originating from the first guide washer  1 , the second washer being fixed to the end of the ring gear, for example crimped or welded to it, as described in document FR-A-2 411 999. The starter ring gear can be force-fitted onto the fixing ring member. 
     Clearly the module in accordance with the invention can quickly be fastened to the crankshaft, the tool for turning the screws being passed through the holes  26  axially coinciding with the holes  36  in the first guide washer  1 . 
     The rivets  20  can of course be replaced by bolts. The transmission casing can be very close to the coupling device in accordance with the invention, to be precise very close to the line D in FIG.  1 . 
     Note that in FIGS. 6 and 7 the first fixing means include the tongues.