FR3045117A1 - VIBRATION SHOCK ABSORBER WITH FLEXIBLE BLADE - Google Patents

Abstract

The invention relates to a vibration damper for a motor vehicle chain, comprising: - a first element (2) and a second element movable in rotation relative to one another about an axis of rotation X ; and an elastic transmission member (14, 15) fixed to the second element for transmitting a torque and damping the rotational acyclisms between the first element (2) and the second element, the elastic transmission member (14, 15) comprising a flexible blade (17) cooperating with a cam follower (18) carried by the first member (2); the flexible blade (17) being arranged such that, for relative movement between the first and second members (2) with respect to an angular rest position, the cam follower (18) exerts a bending force on the blade flexible hose (17) jointly producing a reaction force adapted to bias the first and second members (2) towards said angular rest position; said vibration damper being characterized in that the cam follower (18) is radially disposed within the flexible blade (17).

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 and is arranged such that, for relative movement between the input member and the output member, from and other a relative angular position of rest, the cam follower moves 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.

The cam followers are arranged radially outside their respective flexible blades. Thus, the stiffness of the flexible blades and, consequently, the load exerted on the cam followers by the flexible blades increases under the effect of the centrifugal force. Also, because of this increase in load under the effect of the centrifugal force, the cam followers must be able to withstand considerable radial loads, which complicates their design and / or increases their size. Similarly, the stresses exerted on the flexible blades increase substantially under the effect of the centrifugal force. Thus, this increase in the stresses due to the centrifugal force, leads to decrease the maximum torque that can be transmitted by the vibration dampers of the aforementioned type and therefore limits their application to transmission chains equipped with motor delivering more low couples. The vibration dampers of the aforementioned type are therefore not fully satisfactory. summary

One aspect of the invention is based on the idea of solving the disadvantages of the prior art by providing a vibration damper comprising a resilient flexible blade transmission member which is simple and in which the flexible blade and the cam follower are subject to lower constraints.

According to one embodiment, the invention provides a vibration damper for a motor vehicle transmission chain comprising: a first element and a second element that are rotatable relative to each other about an axis of rotation; rotation X; and an elastic transmission member fixed to the second element for transmitting a torque and damping the rotation acyclisms between the first element and the second element, the elastic transmission member comprising a flexible blade having a cam surface cooperating with a follower of cam carried by the first element; 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 bearing member is radially disposed within the flexible blade.

Thus, the load exerted by the flexible blade decreases under the effect of the centrifugal force, which makes it possible to limit the maximum radial loads likely to be exerted on the cam follower and the blade and, consequently, to simplify the design cam followers and / or to limit their bulk.

Indeed, the stresses exerted on the flexible blades decrease under the effect of the centrifugal force which limits the maximum stresses likely to be exerted on the flexible blades when the torque transmitted by the vibration damper is high. and thus extends the field of application of vibration dampers of the aforementioned type to transmissions equipped with engines delivering larger torques.

Finally, these features are particularly advantageous when the cam follower is a roller rotatably mounted on the first element by means of a lubricated rolling bearing, since the lubricant of the rolling bearing is plated under the effect of the centrifugal force outwards towards the point of contact of the roller with the cam surface carried by the flexible blade, which improves the lubrication of the rolling bearing.

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

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

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

The flexible blade has a portion bent around the axis of rotation X.

The flexible blade has a concavity facing the axis of rotation of the damper so that the cam surface extends circumferentially along the blade within this concavity. Thus, independently of the effects of the centrifugal force, the invention makes it possible to obtain both a cam surface having a relatively large length while obtaining a transmission of effort between the blade and the follower of cam having a greater proportion tangential efforts and a smaller proportion of radial forces.

The concavity is formed on the portion of the blade curved around the axis of rotation X

The flexible blade has a free distal end region 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 end zone is arranged in the extension of the cam surface. The transmission member comprises a fixing portion which is fixed to the second element. The transmission member is connected to the second element only through the fixing portion.

The fixing portion is fixed to the second element at a radial distance from the X axis greater than the radial distance between the support element and the X axis. Advantageously, 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. Thus, with respect to vibration dampers with blades in which the flexible blades are attached to a damper element at means of a radially inner central body, the attachment of a blade transmission member by means of a fixing portion radially outside the cam follower makes it possible to have a fixing portion of a longer length. important, which allows to increase the number and / or the section of the fasteners and, therefore, to increase the robustness of the binding, and this without affecting the filtration performance of the damper or to the compactness of the elastic transmission member.

In a given diametrical direction, the transmission member comprises two sections offset from each other 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. The vibration damper has a plurality of resilient transmission members for transmitting torque and damping rotational acyclisms between the first member and the second member, each resilient member having a flexible blade having a camming surface cooperating with a member. respective cam follower carried by the first member and disposed radially inside the flexible blade.

In one embodiment, each elastic transmission member is formed of a separate piece. In another embodiment, a plurality of elastic transmission members are formed in the same one-piece piece.

When the vibration damper comprises 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 shock absorber. vibration.

According to one embodiment, the or each flexible blade and the respective cam follower are arranged such that, when the torque transmitted between the first member and the second member reaches a predetermined torque threshold, the cam follower leaves the surface of the cam. cam so as to limit the forces experienced by the flexible blade and the cam follower.

According to one embodiment, the elastic transmission members and the cam followers are arranged such that, during a relative rotation between the first and second elements, according to at least one direction of rotation, each cam follower is suitable to move from a position in which it cooperates with the cam surface of one of the elastic transmission members to a position in which it cooperates with the cam surface of another of the elastic transmission members. Thus, the torsion damper is able to limit the torque passing through the transmission chain of the motor vehicle, which protects the transmission chain elements sensitive to overcouples.

The elastic transmission members each comprise at least one ramp arranged so that, for a certain direction of relative rotation, when each cam follower moves from a position in which it cooperates with the cam surface of one of the elastic transmission at a position in which it cooperates with the cam surface of another of the resilient transmission members said cam follower is transferred from one to the other of the cam surfaces through this ramp.

The ramp is arranged on the free end zone of each flexible blade, the ramp being arranged so that when a cam follower cooperates with said ramp away from the free end, said free end s' away from the X axis.

The ramp has an inverted slope to that of the area of the adjacent cam surface. The at least one direction of rotation for which the support elements are able to pass from one flexible blade to another corresponds to a direction of retro rotation, that is to say a transmission of torque of the wheels towards the engine. The vibration damper has no stop capable of limiting the relative rotational movement between the first and second elements.

The resilient transmission members and cam followers are arranged such that each cam follower is adapted to move from a position in which it cooperates with the cam surface of one of the resilient transmission members to a position in the cam. which it cooperates with the cam surface of another of the elastic transmission members only when the torque transmitted between the first element and the second element reaches a torque threshold. Advantageously, the torque threshold is greater than the maximum torque of the motor with which the vibration damper is intended to be associated. By way of example, the maximum torque that can be delivered by a motor is typically between 100 and 600 Nm. The elastic transmission member has a bend that extends between the cam surface and the fixing portion.

According to an alternative embodiment of the invention, for a predetermined angular sector, the or each flexible blade comprises two sections radially offset from one another in a radial direction, 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 elastic blade are offset radially from one another extends over at least 1 °, for example over at least 5 °.

The or each flexible blade comprises an inner and outer strand connected by the bend and respectively comprising one and the other of the two sections offset radially in the predetermined angular sector, the cam follower cooperating with said inner strand. Also, the cam surface is located on the inner face of the inner strand.

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 °.

According to another variant embodiment, each elastic transmission member comprises a fixing portion which is fixed to the second element and the flexible blade of each elastic transmission member develops circumferentially at least up to the attachment portion of another member. of elastic transmission so that the free distal end of the flexible blade of each elastic transmission member is radially disposed between a portion of another elastic transmission member and the axis of rotation X. Advantageously, the flexible blade of each elastic transmission member develops circumferentially beyond the attachment portion of the other elastic transmission member so that the free distal end of the flexible blade of each transmission member is radially disposed between a portion of the blade flexible of another elastic transmission member and the axis of rotation X.

Each flexible blade extends circumferentially over at least 140, for example at least 180 °.

The cam follower is a roller rotatably mounted on the first member via a lubricated rolling bearing.

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 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.

The one or more elastic transmission members are capable of transmitting a maximum torque of between 100 and 600 Nm, for example of the order of 150 to 300 Nm. According to one embodiment, the invention also provides a motor vehicle comprising a shock absorber. aforementioned vibrations.

The flexible blade and the cam follower are arranged so that the cam follower leaves the cam surface so as to limit the forces experienced by the flexible blade when the torque transmitted between the first member and the second member reaches a torque threshold. predetermined.

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 rear view of a double damping flywheel according to a first embodiment. FIG. 2 is a sectional view along plane II-II of the double damping flywheel of FIG. 1. FIG. 3 is a sectional view along the plane III-III of FIG. 1. FIG. perspective rear view of the dual damping flywheel of Figure 1 without the secondary flywheel. - Figure 5 is a rear view in perspective of a double damping flywheel without the secondary flywheel according to a second embodiment.

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 to FIGS. 1 to 4, 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 17 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 fastened independently to the secondary flywheel 3. Each elastic transmission member 14, 15 has a fastening portion 16 which develops circumferentially around the axis X along the radially outer edge of the the front portion of the secondary flywheel 3. The attachment portion 16 of each of the elastic transmission members 14, 15 is therefore fixed on the secondary flywheel 3 radially outside the implantation radius of the cam followers 18, it is that is to say at a radial distance from the X axis which is greater than the radial implantation distance of the cam followers 18. The fixing portion 16 of each elastic transmission member 14, 15 is fixed to the secondary flywheel 3 by a plurality of fasteners, such as rivets 19. The fixing of each elastic transmission member 14, 15 is preferably made by means of at least two rivets 19 in order to to improve the stability and strength of the fastener, for example by means of five rivets 19 as in the 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. The elastic transmission members 14 and 15 comprise a bend 22 which extends between the cam surface 24 and the fixing portion 16. Advantageously, each flexible blade 17 comprises an outer strand 20 extending the attachment portion 16, an inner strand 21 and the elbow 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 elbow 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 elbow 22 are each capable of absorbing part of the stresses on the flexible blade 17 during the relative movement mentioned above. 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 regions radially offset from each other 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. 4, the cam followers 18 are each arranged radially inside one of the flexible blades 17. The cam followers 18 are therefore arranged to cooperate with the internal face of the internal strand 21 of the In other words, the cam surfaces 24 develop on the internal face of the inner strand 21. Each cam surface 24 develops circumferentially on an angular sector between 70 and 130 °, for example the order of 90 ° in the embodiment shown. We observe that such an arrangement of the cam followers 18 radially inside the flexible blades 17 is particularly advantageous in combination with the shape of the flexible blades 17 presented above because it leads to a closure of the elbow 22, rather than when it is opened, when a bending force is exerted on a flexible blade, which causes less stress on the flexible blade 17.

Moreover, the double damping flywheel 1 has no stop capable of limiting the relative rotation of the primary and secondary flywheels 3. The flexible blades 17 and the cam followers 18 are arranged in such a way that, during a relative rotation between the primary and secondary flywheels 2, 3, the cam followers 18 are able to pass from a cam surface 24 carried by the flexible blade 17 to another cam surface 24 carried by the other flexible blade 17. The flexible blades 17 are arranged so as to allow this change of cam surface 24 in at least the direction of retro rotation which corresponds to the transmission direction of the torque for which overtires are likely to occur and advantageously in the two directions of direct and retro rotation . The double damping flywheel 1 therefore acts as a torque limiter capable of limiting the torque passing through the transmission chain of the motor vehicle. The double damping flywheel 1 thus makes it possible to protect the elements of the transmission chain that are sensitive to overtapes, in particular the blades.

The stiffness of the flexible blades 17 is such that the passage from one cam surface 24 to another can occur only when the torque transmitted from the secondary flywheel 3 to the primary flywheel 1 reaches a torque threshold which is greater than the maximum torque. the engine, that is to say greater than the value of torque that can be delivered by the combustion engine to which the double damping flywheel 1 is intended to be associated.

In the embodiment of FIG. 4, the double damping flywheel 1 is shown just after the cam followers 18 have passed from one flexible blade 17 to the other during a relative rotation between the primary and secondary flywheels 2. 3 in the retro sense. The flexible blades 17 are thus oriented so that the cam followers 18 move from their equilibrium position to the bend 22 of the flexible blade 17 with which it cooperates during a relative rotation in the retro direction.

In the embodiment shown, the free end zone 23 of the flexible blades 17 further comprises a bevelled inner surface forming a ramp 33. This ramp 33 has a slope arranged so that when the cam follower 18 moves on this ramp 33, during a relative rotation of the primary flywheels 2 and secondary 3 in a direction of retro rotation, that is to say when the cam follower 18 away from the free end 23, it bends the flexible blade 17 and moves its free end 23 away from the X axis. Thus, the ramp 33 allows the cam follower 18 to join the cam surface 24 of the adjacent flexible blade 17 after a cam surface change 24.

We observe, moreover, that such an arrangement makes it possible to favor the assembly operations of the double damping flywheel 1. In fact, to carry out the assembly operation of such a double damping flywheel 2, the primary flywheel 2 is positioned opposite the secondary flywheel 3 in a relative angular position such that the cam followers 18 are each facing a free space arranged circumferentially between the free end 23 of a flexible blade 17 and the elbow 22 of the other flexible blade 17. The blades are not constrained in this phase. Subsequently, the primary flywheels 2 and secondary 3 are moved axially from each other until the secondary flywheel 3 comes to get into the primary flywheel 2 via the rolling bearing 4. A relative rotation of primary flywheels 2 and secondary 3 in the retro direction is then performed so that the cam followers 18 each cooperate with the ramp 33 of one of the flexible blades 17 and move the free end 23 of the flexible blades 17 of the X axis during said relative rotation so that the cam follower 18 join one of the cam surfaces 24. The simplicity of the assembly operations is ensured.

It can be seen in FIGS. 2 and 3 that the rollers 25 are advantageously rotatably mounted on the primary flywheel 2 by means of rolling members 26, so as to reduce the parasitic friction that may affect the damping function. 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 a front end which is fixed inside a bore 28 formed in the steering wheel. primary 2. The cylindrical rod 27 has, at its front end, a groove in which is housed a circlip 29 for securing the cylindrical rod 27 to the primary flywheel 2. The rolling members 26 are for example balls, rollers or needles. The rolling members 26 are arranged in a running space which is formed between an outer raceway which is formed on the inner periphery of the roller 25 and an inner raceway which is formed on the outer periphery of the cylindrical rod 27. The rolling members 26 are retained axially and protected, forwards, by a protective washer 30 fitted on the cylindrical rod 27 and, aft, by a collar 31 formed at the rear end of the cylindrical rod 27 A retaining ring 32 is tightly mounted around the cylindrical rod 27. The retaining ring 32 is axially in abutment between the primary flywheel 2 and the protective washer 30 and is housed in a cylindrical bore formed in the primary flywheel 1 of such that the radial forces supported by the cam followers 18 are taken up by the primary flywheel 2 over a large axial dimension, which limits the risk of deformation of the tig cylindrical 27.

The double damping flywheel 101 partially illustrated in FIG. 5 differs from the double damping flywheel described above in relation to FIGS. 1 to 4 by the shape of its elastic transmission members 114, 115. The elements that are identical or similar to the elements of the figures 1 to 4, that is to say fulfilling the same function, carry the same reference number increased by 100.

The two elastic transmission members 114, 115 are symmetrical to each other with respect to the axis X and each comprise an attachment portion 116 which develops circumferentially about the axis X along the radially outer edge of the front face of the secondary flywheel, not shown. Each attachment portion 116 is attached to the secondary flywheel by a plurality of rivets 119, five in the illustrated embodiment.

Each fixing portion 116 is extended by a flexible blade 117 which is arranged to deform in a plane perpendicular to the axis of rotation X. The flexible blade 117 of each elastic transmission member 114, 115 develops circumferentially at least until at the fixing portion 116 of the other elastic transmission member 114, 115, and preferably beyond, so that the free distal end 123 of the flexible blade 117 of each elastic transmission member 114, 115 is radially disposed between a portion of the other elastic transmission member 114, 115 and the axis of rotation X. Thus, the elastic transmission members are arranged one around the other. Thus, the elastic transmission members 14, 15 each extend around the X axis over an angular sector greater than 180 °, for example of the order of 280 to 340 °. In other words, each transmission member 114, 115 comprises at least in a given diametrical direction, two sections offset from one another, that is to say two diametrically opposite sections. Advantageously, each flexible blade 117 has a length such that its free distal end 123 is radially disposed between a portion of the other flexible blade 117 and the axis of rotation X.

To do this, each flexible blade 117 has a first portion 134 extending the attachment portion 116 and developing with a circumferential component about the X axis, a second portion 136 developing with a circumferential component to the free end 123 and a bend 135 connecting the first portion 134 and the second portion 136. The bend 135 of each flexible blade 117 is radially opposite the free end 123 of the other flexible blade 117 so that each flexible blade 117 passes into the space between the free end 123 and the attachment portion 116 of the other elastic transmission member 114, 115.

It is seen that, as in the embodiment of FIGS. 1 to 4, such a flexible blade shape 117 allows cam followers 118 to pass from a cam surface 124 of one of the flexible blades 117 to a surface of cam 124 of the other flexible blade 117. Similarly, as in the previous embodiment, the free end zone 123 of the flexible blades 117 is equipped with a ramp 133 which is adapted to receive the cam followers 118 when a resisting torque transmitted from the secondary flywheel to the primary flywheel 102 reaches a threshold torque greater than the maximum torque that can be delivered by the engine. The ramp 133 is arranged such that when a cam follower moves on said ramp away from the free end, the cam follower exerts on the flexible blade a bending force away from its free end of the cam. X axis.

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 (12)

Vibration damper (1, 101) for a motor vehicle transmission chain, comprising: - a first element (2, 102) and a second element (3) rotatable relative to each other around an axis of rotation X; and - an elastic transmission member (14, 15, 114, 115) attached to the second member for transmitting torque and damping rotation acyclisms between the first member (2, 102) and the second member (3), the member resilient transmission member (14, 15, 114, 115) having an elastic flexible blade (17, 117), the flexible blade having a cam surface (24, 124) cooperating with a cam follower (18, 118) carried by the first element (2, 102); the flexible blade (17, 117) being arranged such that, for relative movement between the first and second members (2, 102, 103) with respect to an angular rest position, the cam follower (18, 118) moves on the cam surface (24, 124) and exerts a bending force on the flexible blade (17, 117) together producing a reaction force adapted to bias the first and second members (2, 102, 103) toward said angular position of rest; said vibration damper being characterized in that the cam follower (18, 118) is radially disposed within the flexible blade (17, 117). Vibration damper according to Claim 1, in which the transmission member comprises a fixing portion (16, 116) which is fixed to the second element (3). A vibration damper according to claim 2, wherein the resilient transmission member (14, 15, 114, 115) has a bend (22) extending between the cam surface (24, 124) and the portion fixing (116). A vibration damper according to any one of claims 1 to 3, wherein the flexible blade (17,117) and the cam follower (18,118) are arranged such that when the torque transmitted between the first member (2, 102) and the second member (3) reaches a predetermined torque threshold, the cam follower (18, 118) leaves the cam surface (24, 124) so as to limit the forces experienced by the flexible blade ( 17, 117) and the cam follower. Vibration damper according to any one of claims 1 to 4, comprising a plurality of elastic transmission members (14, 15, 114, 115) for transmitting a torque and damping the rotation acyclisms between the first element (2 102) and the second member (3), each resilient transmission member having a flexible blade (17,117) having a cam surface (24,124) cooperating with a respective cam follower (18,118). by the first element (2, 102) and arranged radially inside the flexible blade (17, 117). Vibration damper according to claim 5, wherein the elastic transmission members (14, 15, 114, 115) and the cam followers (18, 118) are arranged such that, in a relative rotation between the first and second members (2, 102, 103), in at least one direction of rotation, each cam follower (18, 118) is adapted to move from a position in which it cooperates with the cam surface (24, 124) of one of the resilient transmission members (14, 15, 114, 115) at a position in which it cooperates with the cam surface (24, 124) of another of the resilient transmission members (14, 15, 114). , 115). The vibration damper according to claim 6, wherein the resilient transmission members (14,15,114,115) and the cam followers are arranged such that each cam follower (18,118) is fit to pass through. a position in which it cooperates with the cam surface (24, 124) of one of the resilient transmission members (14, 15, 114, 115) at a position in which it cooperates with the cam surface (24, 124). , 124) of another of the elastic transmission members (14, 15, 114, 115) only when the torque transmitted between the first member and the second member reaches the torque threshold. 8. Vibration damper according to claim 6 or 7, wherein the elastic transmission members (14, 15, 114, 115) each comprise at least one ramp (33, 133) arranged so that for a certain direction of rotation relative, when each cam follower moves from a position in which it cooperates with the cam surface (24, 124) of one of the elastic transmission members (14, 15, 114, 115) to a position in which it cooperates with the cam surface (24, 124) of another of the resilient transmission members (14, 15, 114, 115) said cam follower (18, 118) is transferred from one to the other of the surfaces cam via this ramp. Vibration damper according to claim 8, wherein the ramp (33, 133) is arranged on the free end zone of each flexible blade, the ramp (33, 133) being arranged so that when a follower cam (18, 118) cooperates with said ramp (33, 133) away from the free end (23, 123), said free end (23, 123) away from the X axis. 10. Vibration damper according to any one of claims 1 to 9, wherein, for a predetermined angular sector, the or each flexible blade (17) comprises two sections radially offset from one another in a radial direction, a free space radially separating said sections. 11. Vibration damper according to any one of claims 1 to 10, wherein the cam follower is a roller (25, 125) rotatably mounted on the first member (2, 120) via a lubricated rolling bearing. A vibration damper according to any one of claims 1 to 11, wherein the flexible blade (17, 117) has a concavity facing the axis of rotation X, the cam surface extending circumferentially along the blade inside this concavity (24, 124).