FR3045116A1 - VIBRATION SHOCK ABSORBER - Google Patents

Abstract

The invention relates to a vibration damper (1) for a motor vehicle, in particular for a motor vehicle transmission chain comprising: a first element (2) and a second element (3) rotatable relative to one another; another around an axis of rotation X; and an elastic transmission member (14, 15) for transmitting a torque and damping the rotation acyclisms between the first element (2) and the second element (3), the elastic transmission member (14, 15) comprising a securing portion (16) securing the elastic transmission member (14, 15) to the second member (3) and a flexible blade (17) having a cam surface (24) cooperating with a cam follower ( 18) carried by the first element (2); the flexible blade (17) being arranged such that, for relative movement between the first and second members (2, 3) with respect to an angular rest position, the cam follower (18) moves on the surface cam (24) and exerts a bending force on the flexible blade (17) together producing a reaction force adapted to bias the first and second members (2, 3) toward said angular position of rest; said vibration damper being characterized in that the attachment portion (16) is attached to the second member (3) at a radial distance from the X axis greater than the radial distance between the cam follower (18) and the axis X.

Description

Technical Field The invention relates to the field of vibration dampers for a motor vehicle.

Technological background

Explosions engines do not generate a constant torque and exhibit acyclisms caused by explosions succeeding in their cylinders. These acyclisms generate vibrations that are likely to be transmitted to the gearbox and thus generate shocks, noise and noise, particularly undesirable. In order to reduce the undesirable effects of vibrations and to improve the driving comfort of motor vehicles, it is known to equip motor vehicle transmissions with vibration dampers.

The vibration dampers comprise an input member and an output member rotatable about a common axis of rotation and resilient transmission members for transmitting the torque and damping rotational acyclisms between the input member and the output element.

FR3000155 discloses a vibration damper in which the resilient transmission members are formed of one or two flexible blades which are connected to a central body which is attached to one of the input and output elements. Each flexible blade cooperates with a cam follower carried by the other of the input and output elements. Each flexible blade is arranged such that, for relative movement between the input member and the output member, on either side of a relative angular position of rest, the cam follower moves on the along the blade and, in doing so, exerts a bending force on the flexible blade. By reaction, each flexible blade exerts on the respective cam follower a restoring force which tends to return the input and output elements to their angular position of rest. The flexion of the flexible blade thus makes it possible to damp the vibrations and irregularities of rotation between the input element and the output element while ensuring the transmission of the torque between said input and output elements. In the vibration dampers of the aforementioned type, it has been observed in particular that the robustness of the attachment of the flexible blades on one of the input and output elements was necessarily at the expense of an increase in the size of the organs elastic transmission and / or at the expense of a decrease in the length of the flexible blades, and therefore a decrease in performance of the vibration damper. Such a vibration damper is therefore not fully satisfactory. summary

One aspect of the invention is based on the idea of solving the disadvantages of the prior art by proposing a vibration damper comprising an elastic transmission member with a flexible blade which is particularly effective and in which the fastening of the transmission member elastic is provided robustly.

According to one embodiment, the invention provides a vibration absorber for a motor vehicle, in particular for a motor vehicle transmission chain, comprising: a first element and a second element movable in rotation with respect to each other; around an axis of rotation X; and an elastic transmission member for transmitting a torque and damping the rotation acyclisms between the first element and the second element, the elastic transmission member comprising a fixing portion ensuring the attachment of the transmission member to the second element. and a flexible blade having a camming surface cooperating with a cam follower carried by the first member; the flexible blade being arranged such that, for relative movement between the first and second members with respect to an angular position of rest, the cam follower moves on the cam surface and exerts a bending force on the flexible blade jointly producing a reaction force adapted to bias the first and second members toward said angular rest position; said vibration damper being remarkable in that the attachment portion is attached to the second member at a radial distance from the X axis greater than the radial distance between the cam follower and the X axis.

Thus, with respect to the prior art blade vibration dampers in which the flexible blades are attached to a damper member by means of a radially inner central body, the attachment of a blade transmission member to the means of a fixing portion radially outside the cam follower makes it possible to have a fixing portion of greater length, which makes it possible to increase the number and / or the section of the fastening members and therefore, to increase the robustness of the binding, and this without affecting the filtration performance of the damper or the compactness of the elastic transmission member.

According to other advantageous embodiments, such a vibration damper may have one or more of the following characteristics:

The cam follower is, in its entirety, positioned at a radial distance from the X axis less than the radial distance between the fixing portion and the X axis.

The flexible blade is arranged to deform in a plane perpendicular to the axis of rotation X.

The reaction force is generated by the elastic return of the flexible blade

The bending of the blade is accompanied by a relative rotation between the first and second elements.

The flexible blade has a free distal end and is arranged such that the radial distance separating the axis of rotation X from said free distal end varies as a function of the angular displacement between the first and the second elements. The free distal end of the flexible blade is at a radial distance from the X axis lower than the radial distance between the fixing portion and the X axis when the first and second elements are in their angular position of rest.

The cam surface extends over an angular sector greater than 30 degrees, in particular greater than 60 degrees, in particular greater than 90 degrees.

The cam follower is a roller mounted to rotate on the first element, for example by means of a rolling bearing. - Thus, as this roller is arranged, relative to the fixing portion of the transmission member, radially closer to the axis of rotation, the invention offers more freedom for the dimensioning of the roller, which allows optimize the distribution of tangential and radial forces in the transfer of torque and, if necessary, strengthen the strength of this roller by increasing its diameter.

The attachment portion and the flexible blade are integrally formed.

The fixing portion is fixed to the second element by means of at least one fastener, such as a rivet. More particularly, it is attached to the second element through a plurality of fasteners, such as rivets.

The attachment portion extends circumferentially near the radially outer edge of the first member, for example, along said radially outer edge of the second member.

In one embodiment, in a determined diametrical direction, the transmission member comprises two sections offset from one another in said diametrical direction, a free space separating said sections in the diametrical direction. Advantageously, it is the flexible blade which has two sections offset from each other in said diametrical direction. Thus, the superposition of the flexible blade regions allows the development of the blades over longer lengths. Such blades of longer length are subjected to less important constraints, which allows the transmission of high torque. In addition, such a blade arrangement is likely to provide a cam surface having a larger circumferential length. This additional circumferential length of the cam surface allows greater angular movement between the elements, which allows a decrease in the stiffness of the blade and therefore a better vibration filtration.

In one embodiment, for a predetermined angular sector, the flexible blade comprises two sections radially offset from one another, a free space radially separating said sections.

The two sections offset radially from each other are flexible. One of the sections is located between the axis of rotation and the other sections.

The angular sector along which the two sections of the flexible blade are offset radially from one another extends over at least 1 °, for example over at least 5 °. The resilient transmission member has a bend extending between the cam surface and the attachment portion.

The blade has a portion bent around the axis of rotation X extending from the elbow to the free distal end.

The flexible blade is connected to the second element only through its fixing portion.

The flexible blade has an internal strand and an outer strand connected by a bend and respectively comprising one and the other of the two sections offset radially in the predetermined angular sector.

The outer strand connects the attachment portion to the elbow and the inner strand develops with a circumferential component from the elbow to a free distal end.

The inner strand extends circumferentially on an angular sector of at least 45 °, preferably on an angular sector of between 90 and 180 °, for example of the order of 150 to 170 °.

The cam follower cooperates with the inner strand of the flexible blade.

According to one embodiment, the cam follower is located radially between the inner strand of the flexible blade and the attachment portion, so as to maintain the inner strand radially when subjected to centrifugal force.

In other words, the cam surface is located on the outer face of the inner strand. The vibration damper further comprises a stop capable of limiting the relative rotation of the first element relative to the second element.

The abutment comprises a finger carried by the second element adapted to abut against abutment surfaces carried by the first element.

The finger is located radially between the inner strand and the fixing portion of the elastic transmission member.

According to an advantageous embodiment, the finger is located close to, that is to say separated from an angular distance less than 10 °, the elbow of the elastic transmission member.

This finger is radially spaced from the attachment portion of the transmission member.

According to one embodiment, the vibration damper further comprises a damping device with mass of inertia, such as a pendulum or a drummer, comprising at least one mass of inertia and the fixing portion of the elastic transmission member forms a support on which said at least one mass of inertia is mounted oscillatingly. Thus, the elastic coupling function between the first and second elements and the support function of the mass of inertia are performed by the same element. In addition, the fixing portion being located radially outwardly, the mass of inertia is located at a radial distance from the major axis X which allows to give the mass of inertia a significant moment of inertia and therefore, to impart significant filtration efficiency to the centrifugal mass damping device.

The or each mass of inertia has two flanks arranged axially on either side of the attachment portion of the elastic transmission member, the two flanks being connected to one another by means of spacers connecting through an opening in said fastening portion.

According to one embodiment, each connecting strut passes through an associated opening formed in the fixing portion. However, in another embodiment, it is also possible to provide for two or more connecting struts to pass through the same opening in the fastening portion.

The attachment portion of the resilient damping member and / or the second member has (s) an axial recess accommodating at least partially one of the sides of the mass of inertia. In other words, the fixing portion and / or the first element has a smaller axial dimension at the deflection region of the or each mass of inertia so as to allow a reduction in axial size.

According to one embodiment, the centrifugal mass damping device is a pendular device.

The pendular device comprises means for guiding the mass of inertia which comprise two rolling members which each cooperate with a first raceway carried by said mass of inertia and with a second raceway carried by the fixing portion of the elastic transmission member.

Each first raceway is formed on one of the connecting struts and each second raceway is formed by an outer edge of one of the passage openings of a connecting strut formed in the attachment portion of the elastic transmission member. The vibration damper further comprises a friction assembly arranged to exert a friction resisting torque between the first element and the second element during a relative rotation between the first element and the second element. The friction assembly comprises at least one friction washer and an elastic washer adapted to exert a force in an axial direction towards the first element so as to press the friction washer against the first element.

The friction washer has an opening in which is housed a finger carried by the second element so that the friction washer is rotated relative to the first element during a relative rotation of the second element relative to the first element.

The finger adapted to drive the friction washer is a finger carried by the second element and adapted to abut against abutment surfaces carried by the first element so as to limit the relative rotation of the first element relative to the second element.

According to one embodiment, the vibration damper comprises a plurality of elastic transmission members for transmitting a torque and damping the rotational acyclisms between the first element and the second element, each elastic transmission member comprising a fastening portion ensuring fixing said elastic transmission member on the second element and a flexible blade cooperating with a respective cam follower carried by the first element, the fixing portion of each of the elastic transmission members being fixed to the second element at a radial distance from the X axis greater than the radial distance between the cam follower cooperating with said transmission member and the X axis.

According to one embodiment, the elastic transmission members are distant from each other.

According to an alternative embodiment, the vibration damper comprises for each of the elastic transmission members a predetermined angular sector, in which the flexible blade of said elastic transmission member comprises two sections radially offset from one another in a radial direction. , a free space radially separating said sections.

When the vibration damper has an even number of elastic transmission members, for example two, the elastic transmission members are symmetrical with respect to the axis of rotation X which contributes to the balance of the vibration damper .

According to an alternative embodiment not illustrated, the vibration damper comprises at least a first and a second elastic transmission members for transmitting torque and damping the rotation acyclisms between the first element and the second element, each elastic transmission member comprising a fixing portion ensuring the attachment of the elastic transmission member on the second element and a flexible blade cooperating with a cam follower carried by the first element; the flexible blade of the first elastic transmission member developing circumferentially beyond the attachment portion of the second elastic transmission member so that the free distal end of the flexible blade of the first transmission member is radially disposed between a portion of the flexible blade of the second elastic transmission member and the axis of rotation X.

According to one embodiment, the vibration damper is a double damping flywheel. In a variant, the first element is a primary flywheel intended to be fixed at the end of a crankshaft and the second element is a secondary flywheel, for example is intended to form a reaction plate for a clutch device. However, in another variant, the first element is a secondary flywheel and the second element a primary flywheel.

According to another embodiment, the invention also provides a vibration absorber for a motor vehicle, in particular for a motor vehicle transmission chain, comprising: a first element and a second element that can rotate relative to each other; another around an axis of rotation X; and an elastic transmission member for transmitting a torque and damping the rotation acyclisms between the first element and the second element, the elastic transmission member comprising a fixing portion ensuring the attachment of the transmission member to the second element. and a flexible blade having a camming surface cooperating with a cam follower, such as a roller, for example, carried by the first member; the flexible blade being arranged such that, for relative movement between the first and second members with respect to an angular position of rest, the cam follower moves on the cam surface and exerts a bending force on the flexible blade jointly producing a reaction force adapted to bias the first and second members toward said angular rest position; the first element having, in a plane passing through the axis of rotation X and the contact interface between the cam follower and the elastic blade, a distance R between its radially outer edge and the axis of rotation X, and the contact interface between the cam follower and the cam surface of the blade is arranged at a distance from the axis of rotation X between R / 4 and 3R / 4, preferably between R / 3 and 2R / 3, for example between R / 2 and 2R / 3.

Thus, this positioning makes it possible to offer a wide choice of cam follower diameter as a function of the applications, in order to better distribute the tangential forces and the radial forces. This allows in particular the implementation of a large diameter roller when it is necessary to reinforce its robustness.

According to another embodiment, the invention also provides a vibration absorber for a motor vehicle, in particular for a motor vehicle transmission chain, comprising: a first element and a second element that can rotate relative to each other; another around an axis of rotation X; and an elastic transmission member for transmitting a torque and damping the rotation acyclisms between the first element and the second element; a finger, integral in rotation with the second element, and arranged to cooperate with a bearing surface integral with the rotation of the first element for limiting the angular deflection between the first and the second elements, this finger being arranged to drive in rotation a friction washer when the first and second elements rotate relative to each other.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent from the following description of several particular embodiments of the invention, given solely for the purposes of the invention. illustrative and not limiting, with reference to the accompanying drawings. - Figure 1 is a broken view of a double damping flywheel according to a first embodiment. FIG. 2 is a sectional view along the plane II-II of the double damping flywheel of FIG. 1. FIG. 3 is a sectional view along the plane III-III of the double damping flywheel of FIG. FIG. 4 is a perspective front view illustrating the secondary flywheel of the double damping flywheel of FIG. 1. FIG. 5 is a perspective rear view illustrating the primary flywheel of the double damping flywheel of FIG. 1. FIG. sectional view of a double damping flywheel according to a second embodiment. FIG. 7 is a front perspective view of the secondary flywheel of the double damping flywheel of FIG. 6. FIG. 8 is a rear perspective view of the double damping flywheel of FIG. 6 without a secondary flywheel.

Detailed description of embodiments

In the description and the claims, the terms "external" and "internal" as well as the "axial" and "radial" orientations will be used to designate, according to the definitions given in the description, elements of the vibration damper. By convention, the "radial" orientation is directed orthogonally to the axis X of rotation of the vibration damper determining the "axial" orientation and, from the inside towards the outside away from said axis, the "circumferential" orientation is directed orthogonally to the axis of the vibration damper and orthogonal to the radial direction. The terms "external" and "internal" are used to define the relative position of one element relative to another, with reference to the axis X of rotation of the vibration damper, an element close to the axis is thus described as internal as opposed to an external element located radially at the periphery. Furthermore, the terms "rear" AR and "front" AV are used to define the relative position of one element relative to another in the axial direction, an element intended to be placed close to the engine being designated by before and an element intended to be placed close to the gearbox being designated by the rear. The vibration damper is intended to be arranged in the transmission chain of a motor vehicle, between the engine and the gearbox. The vibration damper may in particular be a double damping flywheel, as illustrated in the accompanying figures, or be integrated with a clutch disc.

In relation with FIGS. 1 to 5, a double damping flywheel 1 comprising a primary flywheel 2 intended to be fixed at the end of a crankshaft of an internal combustion engine, not shown, and a secondary flywheel 3 which is centered and guided on the primary flywheel 2 by means of a bearing 4, such as a rolling bearing ball. The secondary flywheel 3 is intended to form the reaction plate of a clutch, not shown, connected to the input shaft of a gearbox. The primary and secondary flywheels 3 are intended to be mounted movably about an axis of rotation X and are, moreover, rotatable relative to each other about said axis X.

The primary flywheel 2 comprises a radially inner hub 5 supporting the bearing 4 and an annular portion 6 extending radially outwardly from the hub 5. The primary flywheel 2 is provided with orifices 7, allowing the passage of fastening screws. 8, for fixing the primary flywheel 2 on the crankshaft of the engine. The primary flywheel 2 carries, on its outer periphery, a ring gear 9 for driving in rotation of the primary flywheel 2, using a starter.

The secondary flywheel 3 comprises a flat annular surface 10, turned towards the rear, intended to form a bearing surface for a friction lining of the disc of the clutch, not shown. The secondary flywheel 3 comprises, close to its outer edge, pads 11 and orifices 12, shown in Figure 1, for mounting the cover of the clutch. The secondary flywheel 3 further comprises orifices 13, arranged opposite the orifices 7 formed in the primary flywheel 2, which are intended to allow the passage of the fastening screws 8, when mounting the double damping flywheel 1 on the crankshaft.

The primary flywheels 2 and secondary 3 are rotatably coupled by elastic transmission members 14, 15. The elastic transmission members 14, 15 make it possible to transmit torque and dampen the rotation acyclisms between the primary flywheel 2 and the steering wheel. secondary 3.

Each elastic transmission member 14, 15 comprises an attachment portion 16, fixed on the secondary flywheel 3, and a flexible blade 17. The attachment portion 16 and the flexible blade 17 are here formed in one piece. Each flexible blade 17 has a cam surface 24 which is arranged to cooperate with a support element formed by a cam follower 18 carried by the primary flywheel 2. The cam followers 18 are here rollers 25 mounted to rotate on the primary flywheel 2 about an axis of rotation parallel to the axis of rotation X. Each cam follower 18 is held in abutment against the cam surface 24 of one of the flexible blades 17 and is arranged to roll against said cam surface 24 during a relative movement between the flywheels primary 2 and secondary 3.

Each cam surface 24 is arranged such that, for a relative rotation between the primary flywheel 2 and the secondary flywheel 3 in one direction or the other, relative to a relative angular position of rest, the cam follower 18 moves on the cam surface 24 and, in doing so, exerts a bending force on the flexible blade 17. By reaction, the flexible blade 17 exerts on the cam follower 18 a restoring force having a circumferential component which tends to bring back primary flywheels 2 and secondary 3 to their relative angular position of rest. Thus, the flexible blades 18 are able to transmit a driving torque from the primary flywheel 2 to the secondary flywheel 3 (forward direction) and a resistant torque of the secondary flywheel 3 to the primary flywheel 2 (retro direction). Furthermore, the torsional vibrations and the irregularities of torque which are produced by the motor and transmitted by the crankshaft to the primary flywheel 2 are damped by the flexion of the flexible blades 17.

With reference to FIG. 4, the structure of the elastic transmission members 14, 15 can be observed in detail. In the embodiment shown, the double damping flywheel 1 comprises two elastic transmission members 14, 15. In such an embodiment case, the elastic transmission members are symmetrical to each other relative to the axis X so as to ensure the balance of the double damping flywheel. In other embodiments, the double damping flywheel may comprise a greater number of elastic transmission members 14, 15.

Each elastic transmission member 14, 15 is attached independently to the secondary flywheel 3, at a distance from one another. Each elastic transmission member 14, 15 comprises an attachment portion 16 which develops circumferentially around the axis X along the radially outer edge of the front face of the secondary flywheel 3. The attachment portion 16 of each of the transmission members elastics 14, 15 is thus fixed on the secondary flywheel 3 radially outside the implantation radius of the cam follower 18, that is to say at a radial distance from the axis X which is greater than the distance The fixing portion 16 of each elastic transmission member 14, 15 is fixed to the secondary flywheel 3 by a plurality of fastening members, such as rivets 19. The fastening of each member elastic transmission 14, 15 is preferably carried out by means of at least two rivets 19 to ensure the stability and robustness of the binding, and for example by means of five rivets 19 as in the mod e embodiment shown.

Each fixing portion 16 fixed on the secondary flywheel 3 is extended by a flexible blade 17 which is arranged to deform in a plane perpendicular to the axis of rotation X. Each flexible blade 17 has an outer strand 20 extending the attachment portion 16, an internal strand 21 and a bend 22 connecting the inner strand 21 to the outer strand 20. The inner strand 21 develops around the X axis with a circumferential component from the bend 22 to the free end 23 of the flexible blade 17. The inner strand 21, a portion of the outer strand 20 and especially the bend 22 are each able to absorb a portion of the stresses experienced by the flexible blade 17 during the aforementioned relative movement. The bend 22 forms an angle of the order of 180 ° so that a portion of the inner strand 21 is located radially between a portion of the outer strand 20 and the X axis. In other words, the flexible blade 17 comprises two flexible sections radially offset from one another and separated by a radial space. Such a flexible blade shape 17 allows it to develop over a consistent length which allows to provide a cam surface 24 having a large circumferential length. Thus, the angular stiffness of the elastic transmission members 14, 15 is limited, which leads to a significant increase in filtration performance.

The internal strand 21 on which is formed the cam surface 24 is developed on an angular sector greater than 45 °, preferably between 90 and 180 °, for example of the order of 150 to 170 ° in the embodiment shown .

As illustrated in FIG. 1, the cam followers 18 are each arranged radially between the outer and inner strands 21 of their respective flexible blade 17 and are arranged to cooperate with the radially outer face of the inner strand 21. Thus, the surfaces of cam are developed on the outer face of the inner strand 21 and the cam followers 18 are arranged outside their respective cam surface 24 so as to maintain radially the inner strand 21 of the flexible blades 17 when they are subjected to the centrifugal force. Each cam surface 24 develops circumferentially on an angular sector between 70 and 120 °, for example of the order of 90 ° in the embodiment shown.

In order to reduce the parasitic friction likely to affect the damping function, the rollers 25 are advantageously rotatably mounted on the primary flywheel 2 by means of rolling members 26, such as balls, rollers or rollers. needles. In the embodiment shown in Figures 1 to 5, the rollers 25 are each carried by a cylindrical rod 27 extending along an axis parallel to the axis of rotation X. Each cylindrical rod 27 has an end which is fixed to the inside of a bore 28 formed in the primary flywheel 2. Furthermore, the cylindrical rod 27 is received inside a through hole formed in a sleeve 29 and has a rearwardly inclined head 30 which rests against a counterbore formed in the rear face of the sleeve 29. The roller 25 is rotatably mounted around the sleeve 29. To do this, the rolling members 26 cooperate, on the one hand, with a raceway formed on the outer periphery. the sleeve 29 and, secondly, with a rolling track formed on the inner periphery of the roller 25. The rolling members 26 are retained axially and protected, forwards, by a protective washer 3 1 fitted on the sleeve 29 and, aft, by a collar formed at the rear end of the sleeve 29. A retaining ring 32 is mounted tightly around the sleeve 29. The retaining ring 32 is axially supported between the primary flywheel 2 and the protective washer 31 and is housed in a cylindrical bore formed in the primary flywheel 1 so that the radial forces supported by the cam followers 18 are taken up by the primary flywheel 2 on a large axial dimension which limits the risk of deformation of the cylindrical rod 27.

The double damping flywheel 1 further comprises one or more stops capable of limiting the relative rotation between the primary flywheel 1 and the secondary flywheel 2 so as to protect the elastic transmission members 14, 15 against the overtires. In the lower part of FIG. 3, it can be seen that each abutment comprises a finger 33 that develops axially forwardly from the secondary flywheel 3. The end of each finger 33 is housed inside a groove 34 formed in the rear surface of the primary flywheel 2. The circumferentially opposite ends of the groove 34 each form an abutment surface adapted to cooperate with the associated finger 33 so as to limit the relative rotation of the secondary flywheel 3 with respect to the primary flywheel 2.

As represented in FIG. 4, each finger 33 is here located radially between the internal strand 21 and the fastening portion 16 of one of the elastic transmission members 14, 15. Thus, such an arrangement makes it possible to dispose the stop surfaces relatively far from the axis of rotation X, which limits the forces exerted on the stops when they reach the end of the race. In addition, each finger 33 is located near the bend 22 of the elastic transmission member 14, 15 so that the length of the cam surface 24 is not or only slightly impacted by the arrangement of the finger 22. This finger 33 is here radially spaced from the fixing portion 16 of the transmission member 14, 15.

The double damping flywheel 1 is also equipped with a friction assembly 35, in particular represented in FIGS. 2, 3 and 5, also called hysteresis assembly, arranged to exert a friction-resistant torque during the relative rotation between the flywheels. primary 2 and secondary 3. The friction assembly 35 is thus able to dissipate the energy accumulated in the flexible blades 17. The friction assembly 35 comprises a set of washers 37, 38, 39 mounted around a cylindrical portion 36 is formed in the primary flywheel 2. The friction assembly 35 comprises an elastic washer 37, a first friction washer 38 secured in rotation to the primary flywheel 2 and a second friction washer 39 adapted to be rotated relative to the flywheel primary 2, during a relative movement between the primary flywheels 2 and secondary 3. The spring washer 37 is, for example, a metal washer type ron delle "Belleville", while the first and the second friction washers 38, 39 are preferably made of plastic.

The set of washers is wedged axially backwards by a circlip 40 which is retained in an annular groove formed at the rear end of the cylindrical portion 36. The elastic washer 37 is interposed between the friction washer 38 and the circlip 40. The circlip 40 forms a bearing surface for the spring washer 37 which provides an axial load pressing the first friction washer 38 against the second friction washer 39 and the latter against the annular portion 6 of the primary flywheel 2. The first washer friction is secured in rotation to the primary flywheel 2 by means of fingers, not shown, projecting radially inwards which are housed in grooves 41, illustrated in Figure 5, formed in the cylindrical portion 36 of the primary flywheel 2 .

Furthermore, the second friction washer 39 has two lugs 42 oriented radially outwards, illustrated in FIG. 5. Each of the two lugs 42 has an opening 43 through which passes one of the fingers 33. Each finger 33 is interposed with a determined circumferential clearance between two circumferentially opposite edges 44, 45 of the opening 43. Thus, the finger 33 abuts against one of the edges 44, 45 so as to drive in rotation the second friction washer 39 compared to the primary flywheel 2 when the circumferential clearance has been caught.

When the second friction washer 39 is rotated relative to the primary flywheel 2, frictional forces are exerted on the one hand between the front face of the second friction washer 39 and the annular portion 6 of the primary flywheel 2, and, on the other hand, between the rear face of the second friction washer 39 and the front face of the first friction washer 38.

The double damping flywheel illustrated in FIGS. 6 to 8 differs from the double damping flywheel described above in that it furthermore comprises a pendulum device 46. The pendular device 46 comprises a plurality of inertia masses 47, also known as flyweights. Pendulum. The fixing portion 16 of each of the elastic transmission members 14, 15 forms a support on which at least one mass of inertia 47 is mounted oscillatingly. Thus, the function of elastic coupling between the primary flywheels 2 and secondary 3 and the inertia mass support function 47 are performed by the same elements. In addition, the attachment portions 16 of the elastic transmission members 14, 15 being disposed along the outer edge of the secondary flywheel 3, the inertial masses 47 are located at a radial distance from the major axis X which allows to increase their moment of inertia and, consequently, the efficiency of the pendular device 46. In addition, the elastic transmission members 14, 15 being here fixed on the secondary flywheel 3, the pendular device 46 is disposed at the exit of a damping stage which makes it all the more effective. In fact, a pendulum device 46 is all the more effective if it is disposed at the outlet of one or more damping stages and, consequently, it is subjected to a lower level of torsional excitations. which prevents it from saturating.

The masses of inertia 47 are able to oscillate in a plane orthogonal to the axis of rotation X, in response to the irregularities of rotation. Each mass of inertia 47 has a general shape of an arc of a circle. In addition, each mass of inertia 47 comprises two flanks 48, 49 which are disposed on either side of one of the attachment portions 16 and are connected axially to one another via two Linking struts 50. To this end, each sidewall 48, 49 has two cutouts for mounting by force-fitting the connecting struts 50. Each connecting strut passes axially through a respective opening, not shown, formed in one of the fixing portions 16.

The oscillations of the masses of inertia 47 are guided by guide means. The guide means comprise, for each mass of inertia 47, two rolling elements which each cooperate with a first raceway carried by the mass of inertia 47 and with a second raceway, carried by the fixing portion 16 respectively. For each rolling element, the first and second raceways are arranged radially facing each other. The first rolling tracks are carried by the connecting struts 50 connecting the flanks 48, 19 and the second raceways are formed by the outer edge of the passage openings of the connecting struts 50. The rolling elements are, for example, formed by cylindrical rollers of circular section. The first and second race tracks have a generally epicyclic or circular shape. The shapes of the raceways are arranged in such a way that the masses of inertia 47 are tuned to an order taking a value close to the rank of the predominant harmonic vibrations generated by the motor. A motor operating with 2n cylinders generating primarily harmonic rank n the pendulum damper must be granted to an order taking a value close to n to dampen the main vibrations.

With reference to FIGS. 7 and 8, it can be seen that each fastening portion 16 has a recess 51 formed on its front face, at the level of the deflection zone of the inertia mass 47. On the other hand, the secondary flywheel 3 has recesses 52 formed in its front face at the deflection zone of each mass of inertia 47. Advantageously, the recesses 51, 52 each have a depth according to the axial dimension which is greater than the thickness of one of the flanks 48, 49. Such recesses 51, 52 make it possible to limit the impact of the integration of the pendular device 46 on the overall compactness of the double damping flywheel 1.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

In particular, although in the embodiments shown, the elastic transmission members 14, 15 are each formed of a separate piece, it is also possible for several elastic transmission members, or even all of the elastic transmission members of the invention. vibration damper, are formed in the same one-piece piece which is then fixed on the second element by a common fastening portion. The use of the verb "to include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or steps other than those set out in a claim. The use of the indefinite article "a" or "an" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps.

In the claims, any reference sign in parentheses can not be interpreted as a limitation of the claim.

Claims (13)

Vibration damper (1) for a motor vehicle, in particular for a motor vehicle transmission chain, comprising: a first element (2) and a second element (3) movable in rotation relative to one another; around an axis of rotation X; and an elastic transmission member (14, 15) for transmitting a torque and damping the rotation acyclisms between the first element (2) and the second element (3), the elastic transmission member (14, 15) comprising a securing portion (16) securing the elastic transmission member (14, 15) to the second member (3) and a flexible blade (17) having a cam surface (24) cooperating with a cam follower ( 18) carried by the first element (2); the flexible blade (17) being arranged such that, for relative movement between the first and second members (2, 3) with respect to an angular rest position, the cam follower (18) moves on the surface of cam (24) and exerts a bending force on the flexible blade (17) together producing a reaction force adapted to bias the first and second members (2, 3) toward said angular position of rest; said vibration damper being characterized in that the attachment portion (16) is attached to the second member (3) at a radial distance from the X axis greater than the radial distance between the cam follower (18) and the axis X. 2. Vibration damper according to claim 1, wherein the fastening portion (16) is fixed to the second member (3) via at least one fastener (19), such as a rivet. Vibration damper according to claim 1 or 2, wherein the fastening portion (16) is disposed along a radially outer edge of the second member (3). 4. Vibration damper according to any one of the preceding claims, wherein, for a predetermined angular sector, the flexible blade (17) comprises two sections radially offset from one another, a free space radially separating said sections. Vibration damper according to one of the preceding claims, wherein the elastic transmission member (14, 15) has a bend (22) extending between the cam surface (24) and the fixing portion ( 16). A vibration damper according to the combination of claims 4 and 5, wherein the flexible blade (17) has an inner strand (21) having the cam surface (24) and an outer strand (20) connected by the elbow (22). ) and respectively comprising one and the other of the two sections offset radially in the predetermined angular sector. Vibration damper according to claim 6, wherein the outer strand (20) connects the attachment portion (16) to the elbow (22) and the inner strand (21) develops with a circumferential component from the elbow (22). to a free distal end (23). 8. Vibration damper according to claim 6 or 7, wherein the cam follower (18) cooperates with the inner strand (21) of the flexible blade (17). Vibration damper according to claim 6, wherein the cam surface (24) is located on the outer face of the inner strand (21). 10. Vibration damper according to any one of claims 6 to 9, comprising a stop adapted to limit the relative rotation of the first element relative to the second element, the stop comprising a finger (33) carried by the second element (3). ) adapted to abut against abutment surfaces carried by the first element (2) and wherein the finger (3) is located radially between the inner strand (21) and the attachment portion (16) of the elastic transmission (14, 15). 11. Vibration damper according to any one of claims 1 to 10, further comprising a damping device with mass of inertia (46) such as a pendulum or a drummer, comprising at least one mass of inertia ( 47) and wherein the attachment portion (16) of the elastic transmission member (14, 15) forms a support on which said at least one inertia mass (47) is oscillatingly mounted. 12. Vibration damper according to claim 11, wherein the mass of inertia (47) comprises two flanks (48, 49) arranged axially on either side of the attachment portion (16) of the transmission member. resilient member (14, 15), the two flanks (48, 49) being connected to one another via connecting struts (50) which pass through an opening in said fastening portion (16). 13. Vibration damper according to claim 11 or 12, wherein the attachment portion (16) of the resilient damping member (14, 15) and / or the second member (3) has (s) an axial recess. (50, 51) accommodating at least partially one of the flanks (48, 49) of the mass of inertia (47).