EP3201489A1

EP3201489A1 - Torsional damper with blade

Info

Publication number: EP3201489A1
Application number: EP15770510.4A
Authority: EP
Inventors: Daniel Fenioux; Hervé MAUREL
Original assignee: Valeo Embrayages SAS
Current assignee: Valeo Embrayages SAS
Priority date: 2014-10-01
Filing date: 2015-09-24
Publication date: 2017-08-09
Also published as: WO2016050611A1; US20180231097A1; JP6630352B2; CN106715956A; FR3026802A1; CN106715956B; JP2017530317A; FR3026802B1

Abstract

The invention relates to a torsional damper for a torque-transmission device, which comprises: a first element (102) and a second element (103) which are rotatable; and a resiliently deformable blade (117a, 117b) rigidly connected to one of said first and second elements, a bearing element (121) supported by the other one of said first and second elements and arranged such as to engage with the blade such that, for an angular deflection between the first and second elements relative to an inoperative angular position, the bearing element exerts a bending force on the blade, jointly producing a reaction force capable of returning the first and second elements into said inoperative angular position, said damper being characterised in that the blade comprises an inner portion (132) and an outer portion (134) connected by a bent section (133), the inner portion being located radially between the outer portion and a rotation axis.

Description

BLADE TORSION SHOCK ABSORBER

Technical field of the invention

The invention relates to a torsion damper for equipping a torque transmission device. The invention relates more particularly to the field of transmissions for a motor vehicle.

State of the art

In the field of automotive transmissions, it is known to provide torsion damping torque transmission devices for absorbing and damping vibrations and acyclisms generated by an internal combustion engine.

The torsion dampers comprise an input member and an output member rotatable about a common axis of rotation and resilient damping means for transmitting the torque and damping rotational acyclisms between the input member. and the output element. Such torsion dampers equip including double damping flywheels (DVA) and / or friction clutch, in the case of a manual or robotic transmission, or locking clutches, also called "lock-up" clutches, equipping hydraulic coupling devices, in the case of an automatic transmission. The document FR3000155 illustrates a torsion damper comprising elastic damping means each formed of two resilient blades mounted on the input element and each cooperating with a respective cam follower mounted on the output element.

The blades and cam followers are arranged such that, for angular displacement between the input member and the output member, on either side of a relative angular position of rest, the follower of cam moves along the blade and, in doing so, exerts a bending force on the resilient blade. By reaction, the resilient blade exerts on the cam follower a restoring force which tends to bring the input and output elements to their angular position of rest. The bending of the resilient 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 torque.

However, such blades are subjected to excessive stresses when the torque to be transmitted is high and are therefore not suitable for transmitting high torques.

OBJECT OF THE INVENTION One aspect of the invention is based on the idea of solving the drawbacks of the prior art by proposing an elastic blade torsion damper which is particularly effective and in which the elastic blade is subjected to weaker forces. constraints.

According to one embodiment, the invention provides a torsion damper for a torque transmission device comprising:

a first element and a second element movable in rotation relative to each other about an axis of rotation X; and

blade damping means for transmitting torque and damping rotational acyclisms between the first member and the second member, the blade damping means comprising:

at least one elastically deformable blade integral with one of said first and second elements; and

at least one bearing element carried by the other of said first and second elements and arranged to cooperate with said at least one blade, said at least one blade being arranged such that, for an angular displacement between the first and second elements relative to an angular position of rest, said at least one support member exerts a bending force on said at least one blade jointly producing a reaction force capable of biasing the first and second elements towards said angular position of rest, said damper being characterized in that, for a predetermined angular sector, the blade damping means comprises two flexible blade regions radially offset from one another in a radial direction, a free space radially separating said two regions of flexible blade. 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 blade surface with which the bearing element with a larger circumferential length cooperates. This additional circumferential length of the surface of the blade with which the support element cooperates allows a greater angular displacement between the elements, which allows a decrease in the stiffness of the blade and consequently a better damping of the motor acyclisms. .

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

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

one of the flexible blade regions is located between the axis of rotation and the other of the flexible blade regions.

said at least one blade has a radially movable free distal end such that the radial distance between the axis of rotation of said free distal end varies as a function of the angular displacement between the first and second members.

the angular sector along which the two flexible blade regions are radially offset from each other extends over at least 1 °, for example over at least 5 °, preferably at least 10 °, in particular at least 30 ° °. said at least one blade comprises a portion for fixing the blade on said first or second element and an elastic portion, the elastic portion comprising the free distal end of said at least one blade, said at least one support element being arranged to cooperate with the elastic portion of said at least one blade.

the elastic portion has an inner and outer strand connected by a bend, the inner strand developing from the attachment portion to the elbow and the outer strand developing circumferentially from the elbow to the free distal end, the internal strand having one of the two blade regions flexibly and radially offset from the damping means and the outer strand having the other of the two blade regions flexible and radially offset from the damping means.

the fixing portion develops circumferentially and has a thickness in a radial direction less than the thickness of the outer strand of the elastic portion.

the fixing portion develops circumferentially over a length less than the length of the outer strand of the elastic portion.

the fixing portion develops circumferentially over a length less than 50% of the length of the outer strand, preferably less than 30%.

said at least one support element is arranged radially outside the outer strand of said at least one blade.

- The outer strand extends circumferentially over at least 45 ° and can extend circumferentially up to 180 ° in a bent state of the blade corresponding to a maximum angular displacement between the first element and the second element °.

the blade damping means comprises two elastically deformable blades integral with one of said first and second elements and two bearing elements carried by the other of said first and second elements, the support elements being respectively arranged to cooperate with one and the other of the two elastically deformable blades,

and each blade has two flexible blade regions radially offset from each other, a free space radially separating said flexible blade regions from each of the blades.

the blade damping means comprises two elastically deformable blades integral with one of said first and second elements and two bearing elements carried by the other of said first and second elements, the bearing elements being respectively arranged to cooperate with one and the other of the two elastically deformable blades and each blade comprises one of the two flexible blade regions radially offset from one another.

the elastically deformable blades are symmetrical with respect to the axis of rotation X.

the distal end of each elastically deformable blade has an internal clearance, the clearance of a blade having a radius of curvature greater than the radius of curvature of an outer surface of the other blade so that said outer surface of the other blade can fit into the clearance.

the elastically deformable blades are attached independently to the first or second element.

the elastic portion comprises a cam surface and said at least one support member comprises a cam follower arranged to cooperate with the cam surface.

the cam follower is a roller rotatably mounted on the respective first or second element by means of a rolling bearing.

The invention also relates to a torque transmission element, in particular for a motor vehicle, comprising a torsion damper mentioned above.

According to other advantageous embodiments, such a transmission element may have one or more of the following characteristics: the transmission element comprises two aforementioned torsion dampers arranged in series.

the transmission element comprises two aforementioned torsion dampers arranged in parallel.

One aspect of the invention is based on the idea of reducing the stiffness of the damping means in order to allow better damping of the acyclisms. One aspect of the invention is based on the idea of increasing the maximum angular deflection between the input element and the output element. One aspect of the invention starts from the idea to reduce stress concentration areas on a spring blade. One aspect of the invention is to provide a blade torsion damper subject to acceptable stresses when transmitting high torque. An object of the invention is to provide a torsion damper for filtering quality acyclisms. An object of the invention is to provide an elastic blade having a large length. An object of the invention is to provide a blade having a cam surface of great length.

The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly in the course of the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes. with reference to the appended figures.

In these figures:

FIG. 1 is a front view of a double damping flywheel illustrating the general operation of a torsion damper, in which the secondary flywheel is shown, in a transparent manner, so as to display the damping means.

Figure 2 is a sectional view of the double damping flywheel of Figure 1, according 11-ll.

Figure 3 is a perspective view of the double damping flywheel of Figure 1.

Figure 4 is a perspective view of the dual damping flywheel of Figures 1 to 3, wherein the secondary flywheel is shown, partially broken away and disassembled from the primary flywheel.

Figure 5 is a schematic view of an elastically deformable blade illustrating the deflection of the blade during an angular deflection between a first element and a second element in a direct direction.

Figure 6 is a schematic view of an elastically deformable blade illustrating the deflection of the blade during an angular movement between a first element and a second element in a retro direction.

- Figure 7 is a schematic view of a torsion damper in the rest position comprising a damping means according to one embodiment of the invention. Figure 8 is a schematic view of the torsion damper of Figure 7 in an angular displacement position between the first member and the second member.

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 torsion damper. By convention, the "radial" orientation is directed orthogonally to the axis (X) of rotation of the elements of the torsion damper determining the "axial" orientation and, from the inside towards the outside while moving away of said axis, the "circumferential" orientation is directed orthogonally to the axis of rotation of the torsion damper and orthogonal to the radial direction. Thus, an element described as circumferentially developing is an element whose component develops in a circumferential direction. Similarly, the indication of an angle is interpreted as delimited by two lines of a plane perpendicular to the axis of rotation X and secant at said axis of rotation X. The terms "external" and "internal" are used to define the relative position of one element relative to another, with reference to the axis of rotation of the torsion damper, an element close to the axis is thus described as internal as opposed to an external element located radially at the periphery. Referring first to Figures 1 to 4 which illustrate the general operation of a torsion damper with elastically deformable blades equipping a double damping flywheel 1. The double damping flywheel 1 comprises 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 rolling ball bearing 4. 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 flywheels 2 and secondary 3 are intended to be mounted movable 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 rolling bearing 4, an annular portion 6 extending radially from the hub 5 and a cylindrical portion 7 extending axially, on the opposite side to the motor, from the outer periphery of the annular portion 6. The annular portion 6 is provided, on the one hand, with screw holes 8 for fixing , intended for fixing the primary flywheel 2 on the crankshaft of the engine and, secondly, for passing rivets 9 for fixing a damping means on the primary flywheel 2. The primary flywheel 2 door , on its outer periphery, a ring gear 10 for driving in rotation of the primary flywheel 2, using a starter.

The hub 5 of the primary flywheel has a shoulder 1 1 serving to support an inner ring of the rolling bearing 4 and which retains said inner ring towards the motor. Similarly, the secondary flywheel 3 has on its inner periphery a shoulder 12 serving to support an outer ring of the rolling bearing 4 and retaining said outer ring in the opposite direction to the motor.

The secondary flywheel 3 comprises a flat annular surface 13, turned on the opposite side to the primary flywheel 2, forming a bearing surface for a friction lining of a clutch disc, not shown. The secondary flywheel 3 has, close to its outer edge, pads 14 and orifices 15 for mounting a clutch cover. The secondary flywheel 3 further comprises orifices 16, arranged vis-à-vis the orifices formed in the primary flywheel 2, and for the passage of the screws 8, when mounting the double damping flywheel 1 on the crankshaft.

The primary flywheels 2 and secondary 3 are coupled in rotation by a damping means. In the embodiment shown in Figures 1 to 4, this damping means comprises two resilient blades 17a, 17b mounted integral in rotation with the primary flywheel 2. To do this, the elastic blades 17a, 17b are carried by a ring body 18 provided with holes for the passage of the fastening rivets 9 to the primary flywheel 2. The annular body 18 further comprises orifices 19 for the passage of the screws 8 for fixing the double damping flywheel 1 to the nose of the crankshaft. The two resilient blades 17a, 17b are symmetrical with respect to the axis of rotation X of the clutch disc.

The elastic blades 17a, 17b have a cam surface 20 which is arranged to cooperate with a cam follower, carried by the secondary flywheel 3. The resilient blades 17a, 17b have a curved portion extending substantially circumferentially. The radius of curvature of the curved portion and the length of this curved portion are determined according to the desired stiffness of the elastic blade 17a, 17b. The elastic blade 17a, 17b may, as desired, be made in one piece or be composed of a plurality of lamellae arranged axially against each other.

The cam followers are rollers 21 carried by cylindrical rods 22 fixed on the one hand to the secondary flywheel 3 and on the other hand to a web 23. The rollers 21 are rotatably mounted on the cylindrical rods 22 around a axis of rotation parallel to the axis of rotation X. The rollers 21 are held in abutment against their respective cam surface 20 and are arranged to roll against said cam surface 20 during a relative movement between the primary and secondary 2 flywheels 3. The rollers 21 are radially disposed outside their respective cam surface 20 so as to radially maintain the resilient blades 17a, 17b when subjected to centrifugal force. In order to reduce the parasitic friction likely to affect the damping function, the rollers 21 are advantageously mounted in rotation on the cylindrical rods by means of a rolling bearing. For example, the rolling bearing may be a ball bearing or roller. In one embodiment, the rollers 21 have an anti-friction coating.

The cam surface 20 is arranged such that, for an angular displacement between the primary flywheel 2 and the secondary flywheel 3, relative to a relative angular position of rest, the roller 21 moves on the cam surface 20 and, in doing so, exerts a bending force on the elastic blade 17a, 17b. By reaction, the elastic blade 17a, 17b exerts on the roller 21 a return force which tends to bring the primary flywheels 2 and secondary 3 to their relative angular position of rest. Thus, the resilient blades 17a, 17b 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).

The operating principle of a damping means with elastic blades 17a, 17b is detailed in relation with FIGS. 5 and 6. When a driving motor torque is transmitted from the primary flywheel 2 to the secondary flywheel 3 (forward direction), the torque to be transmitted causes a relative movement between the primary flywheel 2 and the secondary flywheel 3 in a first direction (see Figure 5). The roller 21 is then moved by an angle with respect to the elastic blade 17a. The displacement of the roller 21 on the cam surface 20 causes a flexion of the elastic blade 17a along an arrow Δ. To illustrate the bending of the elastic blade 17a, the elastic blade 17a is shown in solid lines in its angular position of rest and in dashed lines during an angular movement. The bending force P depends in particular on the geometry of the elastic blade 17a and its material, in particular its transverse modulus of elasticity. The bending force P is decomposed into a radial component Pr and a tangential component Pt. The tangential component Pt allows the transmission of the engine torque. In response, the elastic blade 17a exerts on the roller 21 a reaction force whose tangential component constitutes a restoring force which tends to bring the primary flywheels 2 and secondary 3 to their relative angular position of rest.

When a resistive torque is transmitted from the secondary flywheel 3 to the primary flywheel 2 (retro direction), the torque to be transmitted causes a relative movement between the primary flywheel 2 and the secondary flywheel 3 in a second opposite direction (see Figure 6). The roller 21 is then moved by an angle β relative to the elastic blade 17a. In this case, the tangential component Pt of the bending force has a direction opposite to the tangential component of the bending force illustrated in FIG. 5. Similarly, the elastic blade 17a exerts a reaction force of opposite direction. to that illustrated in Figure 5, so as to bring the primary flywheels 2 and secondary 3 to their relative angular position of rest.

The torsional vibrations and the irregularities of torque that are produced by the internal combustion engine are transmitted by the crankshaft to the primary flywheel 2 and generate relative rotations between the primary flywheel 2 and secondary 3. These vibrations and irregularities are damped. by flexing the elastic blade 17a. FIG. 7 represents a schematic view of a torsion damper in the rest position comprising damping means according to one embodiment of the invention. With reference to FIGS. 7 and 8, elements identical or similar to the elements of FIGS. 1 to 6, that is to say fulfilling the same function, bear the same reference numeral increased by 100

In FIGS. 7 and 8, the resilient blades 17a, 17b are fastened independently of each other on the secondary flywheel 103. The cam followers 121 are fixed on the primary flywheel 102. Each blade 17a , 1 17b has a fastening portion 1 18 fixed relative to the secondary flywheel 103 to enable the rotation of the resilient blades 1 17a, 1 17b with the secondary flywheel 103.

A rolling bearing 104 is mounted between the primary flywheel 102 and the secondary flywheel 103. This rolling bearing 104 has an outer ring 127 carried by the secondary flywheel 103 which cooperates with an inner ring 128 carried by the primary flywheel 102. The fixing portion 1 18 of the blades 1 17a, 1 17b develops circumferentially around the outer ring 127. The inner ring 128 of the rolling bearing ball 104 is carried by the hub 105 of the primary flywheel 102.

The fixing portion 1 18 of each elastic blade 1 17a, 1 17b is fixed to the secondary flywheel 103 by three rivets 129. In order to ensure a good fixing of the elastic blades 1 17a, 1 17b, the three rivets 129 are not aligned. on the same axis. Attaching an elastic blade 1 17a, 1 17b with less than three rivets 129 would not provide a good fixation. In addition, the fixing of an elastic blade 1 17a, 1 17b with a larger number of rivets 129 would generate either, in the case of rivets 129 of the same dimensions, a problem of space, or, in the case of rivets 129 of lower dimensions, a problem of mechanical resistance.

The fixing portion 1 18 fixed to the secondary flywheel 103 is extended by an elastic portion 130. The elastically deformable portion 130 of the blade 11a is schematically represented by a dotted curve 131 in FIG. 7. The elastic portion 130 bears on a radially outer face the cam surface 120 cooperating with the cam follower 121. The elastic portion 130 of each elastic blade 1 17a, 1 17b comprises an internal strand 132, a bend 133 and an outer strand 134. The inner strand 132 of a blade 1 17a, 1 17b extends the fixing portion 1 18. The elbow 133 extends inner strand 132 and outer strand 134 extends elbow 133. Internal strand 132 develops circumferentially around outer ring 127 from attachment portion 1 to elbow 133. Internal strand 132 being not fixed with the rivets 129 on the secondary flywheel 103, it deforms during an angular displacement between the primary flywheel 102 and the secondary flywheel 103. Thus, the internal strand 133 absorbs a portion of the stresses experienced by the resilient blade 1 17a, 1 17b during this angular deflection.

The elbow 133 forms an angle of approximately 180 ° so that a first end 135 of the contiguous elbow 133 of the inner strand 132 is located radially between the axis of rotation X and a second end 136 of the contiguous elbow 133 of the outer strand 134 The elastic blade 1 17a, 1 17b thus has a general shape of a hairpin, one branch of which is formed by the outer strand 134 and the other branch is formed jointly by the fixing portion 1 18 and the internal strand 132. In other words, the elastic portion 130 has two flexible blade regions radially offset from each other and separated by a void space.

The outer strand 134 develops circumferentially from the elbow 133 to the free end 137 of the spring blade 17a, 17b. The outer strand 134 develops over a circumference of at least 45 ° and up to 180 ° in the bent state of the resilient blade 17a, 17b. The cam surface 120 develops on an outer face of the outer strand 134. Advantageously, the cam surface 120 develops circumferentially at an angle of about 125 ° to 130 °. The cam surface 120 develops circumferentially according to a radius of curvature determined according to the desired stiffness of the resilient blades 11a, 17b. This cam surface 120 may have different radii of curvature depending on the desired point stiffness, in order to allow slope variations of the characteristic curve of the torsion damper, representing the torque transmitted as a function of the angular displacement.

The elastic blades 1 17a, 1 17b shown diagrammatically in FIG. 7 are symmetrical with respect to the axis of rotation X. Figure 8 is a schematic view of the torsion damper of Figure 7 in an angular displacement position between the primary flywheel and the secondary flywheel.

When a driving torque is transmitted from the primary flywheel 102 to the secondary flywheel 103 (forward direction), the torque to be transmitted causes a relative movement between the primary flywheel 102 and the secondary flywheel 103 in a first direction. The rollers 121 are then moved by an angle Ω with respect to the elastic blades 1 17a, 1 17b. The displacement of the rollers 121 on the cam surfaces 120 causes the resilient blades 17a, 17b to bend. The flexion of the resilient blades 17a, 17b causes the approximation on the one hand of the outer strands 134 of the blade 17a, 17b with its attachment portion 18 and, on the other hand, the approach of the free end 137 of one of the blades 1 17a, 1 17b with the elbow 133 of the other of the blades 1 17b, 1 17a. Preferably, these connections must not cause contacts between the outer strand 134 and the fixing portion 1 18 of the blade 1 17a, 1 17b, such contacts generating disturbances in the damping of acyclisms and vibrations.

To avoid such contacts, the circumferential length of the fixing portion 1 18 is limited so that, in the rest position shown in Figure 7, the fixing portion 1 18 does not develop circumferentially beyond the axis formed by the alignment between the cam follower 121 and the axis of rotation X. Preferably, an end 138 of the fastening portion 1 18 opposite the elastic portion 130 of a blade 1 17a, 1 17b is located between the cam follower 121 corresponding and the axis of rotation X during a maximum angular displacement in the retro direction between the primary flywheel 102 and the secondary flywheel 103, as represented by the axis 143. Such a maximum angular movement is for example limited by an end stop having a stop 139 on the primary flywheel 102 facing circumferentially a stop 140 on the secondary flywheel 103. In another embodiment, not shown, to avoid contact between the outer strand 134 of an elastic blade 1 17a, 1 17b and its fixing portion 1 18, the thickness of the fixing portion 1 18 is reduced relative to the thickness of the elastic portion 130, and more particularly to the minus the thickness of the end 138 of the fixing portion 1 18 is reduced relative to the thickness of the elastic portion 130.

To avoid contact between the free end 137 of one of the blades 1 17a, 1 17b and the elbow 133 of the other of the blades 1 17b, 1 17a, the free end 137 of the blades 1 17a, 1 17b comprises a clearance 141. This clearance 141 is formed on an inner face of the outer strand 134. The clearance 141 advantageously has a radius of curvature identical or close to the radius of curvature of a portion 142 of the outer face of the elbow 133 of the blades 1 17a, 1 17b. Thus, during a flexion of the blades 1 17a, 1 17b, the free end 137 of each blade 1 17a, 1 17b is close to the elbow 133 of the other blade 1 17b, 1 17a, and the portion 142 of the outer surface of the elbow 133 of each blade 1 17b, 1 17a is housed in the clearance 141 of the other blade 1 17a, 1 17b to delay or even avoid contact.

The length of the elastic blade 1 17a, 1 17b and the arrangement of the outer strand 134, the elbow 133 and the inner strand 132 of an elastic blade 1 17a, 1 17b allows the transmission of a high torque without risk of degradation of the resilient blades 17a, 17b or loss of cooperation between the cam followers 121 and the cam surfaces 120.

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, the blades of the damping means may be independent of one another or linked to one another by a central section. Similarly, it is possible to secure one of the blades of the damping means to one of the elements and the other of the blades of the damping means to the other of the elements.

Furthermore, the figures illustrate a torsion damper in the context of a double damping flywheel, but such a torsion damper can be installed on any suitable device. Thus, such torsion dampers can equip the clutch friction, in the case of a manual or robotic transmission, or the locking clutches, also called "lock-up" clutches, equipping hydraulic coupling devices, in the case of an automatic transmission.

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

1. Torsion damper for a torque transmission device comprising:

a first element (102) and a second element (103) rotatable relative to one another about an axis of rotation X; and

at least one resiliently deformable blade (1 17a, 1 17b) integral with one of said first and second elements; and

at least one bearing element carried by the other of said first and second elements and arranged to cooperate with said at least one blade, said at least one blade being arranged in such a way that, for angular displacement between the first and second members with respect to an angular position of rest, said at least one support member exerts a bending force on said at least one blade jointly producing a reaction force capable of biasing the first and second elements towards said angular position rest,

said damper being characterized in that, for a predetermined angular sector, the blade damping means comprises two flexible blade regions (132, 134) radially offset from one another in a radial direction, a free space separating radially said two flexible blade regions.

A torsion damper according to claim 1, wherein said at least one blade has a radially movable free distal end (137) such that the radial distance between the axis of rotation of said free distal end varies as a function of the deflection angular between the first and the second elements.

3. torsion damper according to one of claims 1 to 2, wherein the angular sector along which the two flexible blade regions are radially offset from each other extends over at least 1 °, for example at least 5 °, preferably at least 10 °, in particular at least 30 °.

4. torsion damper according to one of claims 1 to 3, wherein said at least one blade comprises a fixing portion (1 18) of the blade on said first or second element and an elastic portion (130), the portion elastic element comprising the free distal end (137) of said at least one blade, said at least one support element being arranged to cooperate with the elastic portion of said at least one blade,

and wherein the elastic portion has an inner strand (132) and an outer strand (134) connected by a bend (133), the inner strand developing from the attachment portion to the elbow and the outer strand developing circumferentially from the elbow to the free distal end, the inner strand having one of the two blade regions flexibly and radially offset from the damping means and the outer strand having the other of the two flexible blade regions radially offset from the means of depreciation.

5. A torsion damper according to claim 4, wherein the fastening portion is circumferentially developed and has a thickness in a radial direction less than the thickness of the outer strand of the elastic portion.

6. torsion damper according to claim 4 or 5, wherein the fastening portion develops circumferentially over a length less than the length of the outer strand of the elastic portion.

7. torsion damper according to one of claims 4 to 6, wherein said at least one support member is disposed radially outside the outer strand of said at least one blade.

A torsion damper according to any one of claims 4 to 7, wherein the outer strand extends circumferentially over at least 45 ° and may extend circumferentially up to 180 ° in a bent state of the blade corresponding to a maximum angular movement between the first element and the second element.

9. torsion damper according to one of claims 4 to 8, wherein the blade damping means comprises two resiliently deformable blades integral with one of said first and second elements and two bearing elements carried by the other said first and second elements, the support elements being respectively arranged to cooperate with one and the other of the two elastically deformable blades, and wherein each blade comprises two regions of flexible blade radially offset from each other, a free space radially separating said flexible blade regions of each of the blades.

Torsion damper according to claim 9, wherein the elastically deformable blades are symmetrical with respect to the axis of rotation X.

1 1. A torsion damper according to claim 9 or 10, wherein the distal end of each elastically deformable blade has an internal clearance (141), the clearance of a blade having a radius of curvature greater than the radius of curvature of an outer surface (142) of the other blade so that said outer surface (142) of the other blade can be inserted into the recess.

12. torsion damper according to one of claims 9 to 1 1, wherein the elastically deformable blades are independently attached to the first or second element.

The torsion damper according to one of claims 4 to 12, wherein the resilient portion has a cam surface (120) and wherein said at least one support member has a cam follower (121) arranged to cooperate with the cam surface.

The torsion damper of claim 13, wherein the cam follower is a roller rotatably mounted on the respective first or second member through a rolling bearing.

15. Torque transmission element, in particular for a motor vehicle, comprising a torsion damper according to one of claims 1 to 14.