TORSION SHOCK ABSORBER FOR A FRICTION CLUTCH. IN
PARTICULAR FOR AUTOMOTIVE VEHICLE
DESCRIPTIVE MEMORY
The invention relates to a torsion damper for a friction clutch, in particular for a motor vehicle. In a known manner and as described in EP-0 488 859, a torsion damper of the type preferred by the invention comprises a main damper interposed between an input element such as a friction disk and an annular disc surrounding a hub of an output shaft, the dentures formed on the hub and on the disc to engage it with the other with a circumferential play, and a pre-damper interposed between the disc and the hub and comprising an annular handle rotationally attached to the disc and delimiting with the hub to the housings for the elastic members with circumferential action, such as for example springs. The pre-shock absorber allows absorbing vibrations in the idling speed of an internal combustion engine. When the coupling transmitted by the clutch increases, the elastic members of the pre-damper are compressed and the disc teeth rest on the side of the hub, the collisions of said teeth can be relatively important. To cushion the shocks, a friction washer (also called a hysteresis washer or sliding washer) is provided, which is resiliently supported on a radial face of the annular disk comprising a denture that meshes with that of a bucket , with a lower circumferential clearance than that provided between the dentures of the hub and the disc. Likewise, said friction washer or sliding washer is driven in rotation from the beginning by the annular disc in the idle speed, then when the transmitted coupling increases, its denture rests on that of the hub, then that of the disc Annular is also embedded in the denture of the cube. From that moment, the support of the disc teeth in the hub is braked by the friction of the disk in the sliding washer, which reduces the collisions between the disc and hub dentures and avoids the corresponding noises. In certain embodiments, said sliding washer is closed between the annular disc and a friction handle which is interposed between the disc and a guide washer attached to the friction disc, and which is subjected to the elastic force developed by a placed Belleville washer between said friction handle and said guide washer, the friction of the handle in the disc is intended to dampen the vibrations and the coupling oscillations absorbed by the main damper. In this case, it is the same elastic force developed by the aforementioned Belleville washer that creates the friction of the sliding washer on the annular disc and that of the friction handle on the annular disc or on the guide washer attached to the disc. friction, so that the phenomena intended to be cushioned by these frictions are very different in intensity and energy. In another embodiment, the sliding washer which is rubbed on the annular disc instead of the pre-shock function is associated with a distribution washer and an elastic washer such as a Belleville washer and said stack of three washers is axially closed between the washer and the washer. annular disk and a friction handle interposed between said disk and a guide washer attached to the friction disk, to dampen the vibrations and oscillations absorbed by the main damper. In this case, when the denture of the sliding washer rests on that of the hub, the support of the disc teeth in those of the hub can produce unpleasant noises, due to the friction of the distribution washer in the Belleville washer and / or of the Belleville washer on the friction handle. The invention is particularly aimed at avoiding the drawbacks of said known modalities, retaining their respective advantages and without increasing on the other hand the complexity or cost of the torsion damper. The invention proposes for this effect a torsion damper for a friction clutch, in particular for a motor vehicle, comprising a main damper interposed between an input element such as a friction disk and an annular disc surrounding a shaft hub outlet, dentures formed in the hub and in the disc to engage with a circumferential play, a pre-shock interposed between the disc and the hub and comprising an annular handle rotatably joined to the disc and delimiting with the hub the housings for the elastic members with circumferential action, and an elastic washer of application of a friction washer on the annular disc, the two washers being axially interposed between the disc and the annular handle of the pre-shock, the friction washer comprises a denture that meshes with that of the hub with a circumferential clearance lower than the aforementioned game to stop the collisions of the denture of the co in the hub, characterized in that said elastic washer is rotationally attached to the annular handle of the pre-shock absorber and comprises a bearing face on the friction washer and radial fingers, applied on said annular handle. In said damper, the elastic washer is driven in the friction washer and is rotationally attached to the annular handle of the pre-shock absorber and therefore can not be rubbed therein when the annular disc teeth rest on that of the hub. In addition, the force of application of the friction washer on the annular disc is determined by the elastic washer associated with said friction washer and not by the Belleville washer associated with the friction handle of the main damper. Conveniently, the radial fingers of the elastic washer form spring plates, determining the bearing force of the friction washer on the disk. According to another characteristic of the invention, the aforementioned annular handle and the elastic washer are joined in rotation by the radial fingers of the elastic washer, which cooperate by supporting the slits and / or the projections and an end face of said annular handle. The radial fingers of the elastic washer thus have a multiple function of elastic support on the annular handle and of connection in rotation therewith, and the force exerted by the elastic washer is determined by the depth of the grooves of the face of the spring. end of the annular handle that receives the radial fingers of the elastic washer. By regulating the depth of the slits, the elastic force exerted by the washer is regulated. In a preferred embodiment of the invention, the radial fingers of the elastic washer are grouped in pairs and extend, in each pair, on either side of an axial pin formed as a protrusion on one end face of the handle to join it in rotation with the aforementioned handle. Then, the joining members in rotation to the aforementioned annular handle and annular disc can be split to rotate the elastic washer with the annular handle. Conveniently, the bearing face of the elastic washer on the friction washer is convex, for example toric. The above allows a correct elastic support of the friction washer on the annular disc, reducing the friction between said face of the elastic washer and the friction washer.
In the damper according to the invention, the aforementioned annular handle constitutes a closed friction member between the annular disc and a guide washer on which the clutch friction disc is fixed, and which comprises a peripheral axial shoulder flange on the annular disc, said peripheral rim delimits a cylindrical housing in which the aforementioned elastic washer and friction washer are received. Said solution is interesting because its compact axial nature facilitates the assembly of the elastic washer and the friction washer in the damper according to the invention and also avoids any interference between the friction washer and the aforementioned annular handle. The invention will be better understood and other features, details and advantages thereof will be more apparent upon reading the following description, elaborated by way of example with reference to the accompanying drawings in which: - Figure 1 is a schematic view in axial coupling of a torsion damper according to the invention with local extraction of the guide washer adjacent to the annular handle of the pre-shock for better display; Figure 2 is a sectional perspective view of the annular handle, the elastic washer and the friction washer according to the invention;
Figure 3 is a schematic half-view, in radial section, explaining the operation of the friction washer; - Figure 4 is a partial schematic view in axial section of a variant of the embodiment of the invention. In a very general way, a friction clutch, particularly for a motor vehicle, comprises a disk which carries the friction linings which are normally closed between a flywheel resting on the motor shaft and a pressure plate operated by a clutch mechanism, for transmitting a rotation coupling to a rotation axis, such as, for example, the input shaft of a gearbox. A torsion damper is interposed between the friction disk and the output shaft to absorb vibrations and coupling oscillations, and generally comprises a main damper 10 which is interposed between the disk 12 carrying the friction linings and an annular disk 14 surrounding a hub 16 rotatably joined to the output shaft 18, and a pre-damper 20 which is actuated between the annular disk 14 and the hub 16. The annular disk 14 comprises an internal peripheral dentition 22 which meshes with a predetermined circumferential play with an outer peripheral teeth 24 of the hub 16 (Figure 3) and of elastic members with circumferential action, such as coil springs 26 of weak stiffness (Figure 1), are interposed between the annular disk 14 and the hub 16 for absorb the vibrations in the idle speed of the internal combustion engine in which the clutch is associated.
Similarly, helical springs 28 having a strong stiffness are interposed between the annular disk 14 and the friction disc 12 to absorb vibrations and coupling oscillations in other operating modes of the engine. More precisely, the springs 28 are housed in the elongated lights 30 of the disk 14 and are held in the openings formed in the two parallel guide washers 32 and 34, located on either side of the disk 14 and rigidly supported one envelope. the other by the non-represented columns, the washer 32 of the guide washers carries the disc 12 which is fixed on its internal periphery in said washer 32. The disc lights 30 and the openings (in the form of a window) of the washers of guide 32, 34 can be replaced respectively by the recesses open towards the outside and by the molds. Similarly, the springs 26 of the pre-shock absorber 20 are received in the housings in the form of recesses radially open on one side, which are delimited, on the one hand, by an internal dentition of an annular handle 36 rotatably connected to the disk 14 and, on the other hand by an external teeth of a handle 38 fixedly mounted in rotation on the hub 16, said handle 38 also being the conical bearing support and guide of the washer 32 on which the friction disk 12 is fixed. In a known manner, said torsion damper operates in the following manner:
In the internal combustion idling regime, the friction disc 12 and its guide washers 32 and 34 are rotationally joined to the disc 14, because of the strong stiffness of the springs 28, and the rotation of the disc 14 is transmitted to the hub 16 of the output shaft 18 by the intermediary of the springs 26 of the pre-shock absorber 20, which absorbs vibrations. When the rotation coupling transmitted by the clutch increases, the springs 26 of the pre-shock are compressed until the teeth 22 of the disk 14 rest on the external teeth 24 of the hub 16 which then joins in rotation to the disk 14, the vibrations and the coupling oscillations then being absorbed by the springs 28 of the main damper until said spring is compressed to the maximum, the disc 14 then joining in rotation to the guide washers 32 and 34 and to the friction disk 12. In addition, the connecting collars of the washers 32, 34 are those that limit the angular movement between the disk and its washers. In a similar manner, a friction plate washer or sliding washer 40 is associated with the annular disk 14 for braking the collisions of its teeth 22 on the teeth 24 of the hub 16, which are caused by an increase in the rotation coupling. transmitted by the clutch. The washer 40 surrounds the teeth 24 of the hub 16 and comprises on its internal periphery a dent 42 which meshes with the teeth 24 of the hub, with a predetermined circumferential clearance lower in the circumferential clearance between the dentures 22 and 24 of the disc 14 and of the hub 16, as can be seen in figure 3. Said washer 40, which is interposed between the disk 14 and the pre-shock 20, is applied to the disk by an elastic washer 44 of the Belleville washer type. According to the invention, the washer 44 rests, on its outer periphery, on the annular handle 36 of the pre-shock 20 and, on its internal periphery, on the sliding washer 40 to elastically apply it on the annular disk 14. The outer periphery of the elastic washer 44 is formed with the radial fingers 46, grouped in pairs as shown in figure 2, which are folded or layered in the form of a die wherein the vertices are turned towards the annular handle 36, and which are hooked , with a substantially zero circumferential clearance, on either side of the axial pins 48 formed in protrusion on an end face of the handle 36 to join it in rotation with the disc 14, said pins 48 being coupled in the corresponding holes of the disc. The radial fingers 46 of the washer 44 form spring plates and largely determine the elasticity of said washer. As seen in Figure 2, the pins 48 of the handle 36 have lateral planes, which form guide surfaces of the fingers 46 of the washer 44. At its internal periphery, the elastic washer 44 is of a non-curved shape in the radial direction , for example in toric form, its support face on the support washer 40 being convex. In the embodiment shown, the face of the end of the handle 36 rotates towards the annular disk
14 is formed with an axial peripheral flange 50 delimiting a cylindrical housing 52 in which the elastic washer 44 and the sliding washer 40 are received, which allows the latter to be applied to the annular disc 14 without being axially compressed by the handle 36 and subjecting only to the axial force developed by the elastic washer 44. Likewise any risk of parasitic friction between the sliding washer 40 and the annular handle 36 is thus avoided. The decouples 54 are formed in the flange 50 for the passage of the radial fingers 46 of the washer 44, said disengagements open at the flat radial surfaces 56 of the handle 36, extend on either side of the pins 48 and serve as support faces at the vertices of the dice formed by the fingers 46 The depth of the decoupling 54 allows to regulate the elastic load exerted by the washer 44. In a known manner, the annular handle 36 is closed axially between the annular disk 14 and the guide washer 32 of the disk 12, by means of the intermediate of a friction washer 58 and a Belleville washer 60 interposed between the annular disk 14 and the other guide washer 32 A further friction washer 62 associated with another Belleville washer 64 is provided between the second guide washer 34 and an end face of the hub 16, the washers 62, 64 are surrounded by the washers 58, 60. In said torsion damper , the operation of the sliding washer 40 is as follows: In the idling mode, the teeth 22 of the disc 14 and the teeth 42 of the sliding washer 40 are embedded in the teeth 24 of the hub 16, as shown in FIG. Figure 3. When the transmission coupling increases, the shock springs 26 are compressed and the dentures 22 of the disc 14, 42 of the sliding washer 40 move in the direction indicated by the arrow in figure 3, relative to the hub 16, the sliding washer 40 being pressed into the annular disc 14 by the elastic washer 44 which is rotationally attached to the annular handle 36 rotationally attached to the disk 14, so that , under said conditions, the sliding washer 40 is rotatably joined to the disk 14. When the transmitted coupling increases, the teeth 42 of the sliding washer 40 rest on the teeth 24 of the hub 16, so that the sliding washer 40 then joins in rotation to the hub 16. When the transmitted coupling increases further, the denture 22 joins the teeth 24 of the hub 16 until it rests on it, however, said movement is braked by the friction of the disc 14 on the sliding washer 40, the importance of said friction being determined by the axial force developed by the elastic washer 44. The friction of the washer 62 on the end face of the hub 16 also contributes to slow down the rotation of the annular disk 14 relative to the hub 16. In this embodiment, the annular handle 36 is made of moldable plastic material, the handle 38 is made of moldable plastic material or material frit, and the washers 40 and 44 they are metallic, just like the annular disk 14, which allows to obtain a strong coefficient of friction by contact of metal in metal and an important braking of the disk 14. The decoupling 54 of the rim 50 allows to accommodate the elastic washer 44 and the washer of friction 40 inside the handle 36. The number of springs 26 and 28 mentioned above depends on the applications. In the described and represented embodiment, four springs 26 are provided and arranged in four (not referenced) housings of the handle 36 (Figure 2). The hub 16 is the output element of the torsion damper, wherein the input element is the disk 12 equipped with friction linings. In addition, the disc 12 or an extension of the guide washer 32 can be fixed directly on the motor flywheel. In the embodiment of FIGS. 1 to 3, the handle 38 of the pre-shock engages with the teeth 24 of the hub 16 thanks to the axial ends which extend into the recesses defined by the teeth 24, where the outer diameter is equal to that of the handle 38 and that of its axial extremities. In the embodiment of figure 4, where the elements correspond to those of figures 1 to 3 are designated by the same increased references of a hundred, the pre-shock comprises no more than an annular handle 136 made of a mouldable material such as a plastic material and comprising axial pins 148 for rotating connection with the annular disc 114, said pins 148 penetrate the recesses or grooves 149 formed in the windows 130 of the disc (which allows to suppress the holes formed in the disc 14 for the reception of the pins 48 of the embodiment of Figures 1 to 3). Said pins 148 are outwardly profiled to couple the shape of the springs 128. It will also be noted that, in the embodiment of figure 4, the arrangement of the washers 162 and 164 is reversed in relation to that of figure 1, and that the washer 158 is placed in rotation on the springs 128 of the main damper and presents for this purpose the minus one radial armlexion.
159 that penetrates a window 130 of the disc 114. The hub 116 is staggered in diameter at its outer periphery to form spring-shaped recesses 126 of the pre-shock and comprises a dent 124 of reduced axial length engaging with the disc teeth 122 114. The handle 136 forms a bearing and cooperates with a radially internal cylindrical flange of the guide washer 132. The handle 136 is likewise formed with an internal frustoconical section which cooperates with a complementary frusto-conical portion of the hub 116. The friction washer 140 it is applied to the disk 114 by the spring washer 144 in the form of Belleville washer comprising the radially deformable spring fingers 146 forming the spring and extending in the decoupling 154 of an axial peripheral flange 150 of the handle 136, said flange 150 supports the disk 114. For the rest, the mode of Figure 4 corresponds to that of Figures 1 to 3 and the operation is identical co to the one described previously. In addition, the annular handle 36 is metallic, so that the pins 48 are replaced by the axially oriented limbs taking into account that the handle is then less thick. The handle 136 can be similarly metallic except for its internal periphery which serves as a support. In the case of one face at least according to the applications and covered with a bed of plastic material for rubbing on the guide washer 132 or the frustroconical section of the hub. The foregoing is carried out, for example, by means of the molding technique of the handle 136 which comprises the holes by anchoring the plastic material advantageously extending from one part of the handle 136 to the level of the support and at least to the face of the handle 136. turned to the washer 132 to contact it. Everything depends on the applications.