FR3050245A1 - TORSION DAMPER FOR A TORQUE TRANSMISSION DEVICE OF A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a damper (1), in particular an automobile torsion damper, the damper comprising: - a first element (2) movable in rotation with respect to an axis of rotation X, a second element (3) movable in rotation about the axis of rotation X relative to the first element, - a transmission member (10), carried by the second element, comprising a resilient blade (13) capable of bending and transmitting a torque between these two elements, the flexion of the elastic blade being accompanied by a relative rotation between the first and second elements, along the axis of rotation X, the elastic blade having a cam surface (44), the damper comprising a follower camming device (11) arranged to move on this cam surface during a relative rotation between the first and second elements, characterized in that the elastic blade (13) locally has on its portion having the cam surface a reinforced area ee (Z) having a section of maximum area (A).

Description

TECHNICAL FIELD The invention relates to the field of transmissions for a motor vehicle and more particularly relates to a camber torsion damper.

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 torsion dampers. Such torsion dampers equip including damping dual flywheels (DVA), clutch friction, or locking clutches, also called "lock-up" clutches.

Document FR3008152 discloses a double damping flywheel comprising a primary flywheel and a secondary flywheel movable in rotation relative to one another about an axis of rotation X. The double damping flywheel comprises means damping elastics which are formed of several resilient blades mounted on one of the flywheels and each cooperating with an associated roller rotatably mounted on the other flywheel. The flexion of the elastic blades makes it possible to damp the vibrations and irregularities of rotation between the flywheels of primary and secondary inertia while ensuring the transmission of torque. SUMMARY The invention aims to improve this type of vibration damper of the aforementioned type, in particular by reducing the risk of malfunctions or even destruction, related to the forces exerted on the cam follower and on the blade.

According to one embodiment, the invention provides a damper, in particular an automobile torsion damper, the damper comprising: a first element movable in rotation with respect to an axis of rotation X, a second element movable in rotation around the axis of rotation X relative to the first element, a transmission member carried by the second element, comprising an elastic blade capable of bending and transmitting a torque between these two elements, the bending of the elastic blade being accompanied by relative rotation between the first and second members, along the axis of rotation X, the resilient blade having a cam surface, the damper having a cam follower arranged to move on this cam surface during a rotation relative between the first and second elements, characterized in that the elastic blade has locally, on its portion having the cam surface, a reinforced zone provided with a e section of maximum area, and when the damper is in a high-speed operating speed and low torque, the blade bears against the cam follower on this reinforced area.

Thus, with this type of damper, the forces generated by the centrifugation of the blade are reduced because the mass of the blade is reduced in areas remote from the reinforced zone. The centrifugal forces exerted by the blade on the cam follower are therefore less.

In addition, to reduce the risk of breakage of the blade, particularly when this type of damper is in a high speed and low torque operating speed, the reinforced zone of the blade which ensures contact with the cam follower at this regime makes it possible to strengthen the blade with respect to the forces exerted by the cam follower on the blade. The invention therefore provides a solution combining the advantages of two supposedly antagonistic solutions, namely: strengthening the blade with respect to the forces exerted by the cam follower in the operating regime at high speed and low torque, and - lightening the blade so that it exerts less centrifugal force on the cam follower.

Thanks to the invention, the blade is reinforced locally, for example only in its contact zone with the cam follower when the damper is in a high speed and low torque operating speed.

A blade section is obtained by the intersection of the blade with a plane P parallel to the axis X and locally perpendicular to the tangent to the profile of the cam surface or to the outer contour of the blade observed in a plane perpendicular to the X axis.

In the rest of the application, the indication of an angle or an angular sector 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.

According to other advantageous embodiments, the torsion damper may have one or more of the following features: the maximum area section A is the largest section in the portion of the blade having the cam surface, the blade is made of metal, for example steel, the blade is made in particular by cutting sheet. the reinforced zone has, circumferentially, a length L greater than 5 mm, in particular greater than 10 mm, the reinforced zone has, circumferentially, a length L of between 5 mm and 30 mm, in particular between 10 mm and 20 mm.

The cam follower is arranged radially outside the blade.

In its portion having the cam surface, the average area of the reinforced area is greater than the area of the average section of the blade. when no torque is transmitted by the damper and the damper does not rotate about the X axis (at rest), the cam follower is in support against the reinforced zone. the maximum area section is a solid section. - In its portion having the cam surface, the blade is full on all of its sections. - The thickness of the blade along the X axis of the damper is between 4 mm and 20 mm, preferably between 6 mm and 15 mm. - The reinforced zone has, circumferentially, a length L greater than the thickness of the reinforced zone. - The reinforced zone has, circumferentially, a length L greater than the maximum height of the reinforced zone, the height being measured in a plane perpendicular to the axis of rotation, perpendicular to the tangent to the cam surface. - The flexible blade has a free end zone arranged to approach the axis of rotation of the damper when the blade bends under the action of the cam follower. the free end zone is arranged in the extension of the cam surface. the cam follower is carried by the first element. the cam follower comprises a roller arranged to roll on the cam surface when the cam follower is displaced on the cam surface. - The cam follower comprises a rod integral in rotation of the first element about axis of rotation X. the rod is fixed to the first element. the roller is rotatably mounted around the rod. the reinforced zone extends circumferentially about the axis X, on an angular sector less than 40 degrees, in particular less than 30 degrees. - At rest, the roller is fully included in this angular sector, when the damper is in a high speed operating speed and low torque, the roller is fully included in this angular sector. the angular sector extends at most 20 degrees on either side of the section of maximum area of the blade; at most 15 degrees on either side of the section of maximum area of the blade. the cam surface has two ends, one end of the cam surface being on the side of the free end region of the blade, and the other end of the cam surface is on the side of the deformation portion. of the blade. the blade section decreases over at least 50% of at least one of the two angular arcs extending from the maximum area section and ending at one end of the cam surface. the blade section decreases over 100% of at least one of the two angular arcs extending from the maximum area section and ending at one end of the cam surface. the blade section decreases over 100% of the angular arc from the maximum area section to the free end zone of the blade. the blade is arranged so that the stresses concentrated in the reinforced zone, when the damper is in a high speed and low torque operating speed, are less than 500 MPa. the blade is arranged so that the concentrated stresses in the reinforced zone, when the damper is in a high speed and low torque operating speed, are lower than the elastic limit of the material in which the reinforced zone of the blade is formed , the transmission member comprises a fixing portion attached to the second element and the blade. the blade comprises a deformation portion extending between the attachment portion of the transmission member and the blade portion having the cam surface. the deformation portion has a minimum area section. the deformation portion comprises an elbow. the blade section decreases from the maximum area section to the minimum area section of the blade deformation portion. if desired, the blade section decreases to the attachment portion of the transmission member. one of the ends of the cam surface is on the side of the free end zone of the blade. The other end of the cam surface is on the side of the deformation portion of the blade. the blade section decreases from the maximum area section to the free end zone of the blade. - High speeds are above 3000 rpm. the high speeds are between 3000 rpm and 6000 rpm, preferably between 4000 rpm and 5500 rpm, for example between 4500 rpm and 5000 rpm. the low torques are less than 150 N.m, especially less than 100 N.m, for example less than 20 N.m. the low torques are between 0 Nm and 150 Nm, in particular between 10 and 120 Nm, for example between 20 and 100 N.m. in a particular mode of operation at very high speed and low torque, called "burst", the speed is greater than 10000 rpm and the torque is less than 10 Nm, especially less than 5 Nm, especially close to 0 N.m. The burst system can for example be reached when the engine is running at a very high speed and the clutch is disengaged, downstream of the damper, in a direction of flow of torque from the engine. - In burst mode, advantageously, the cam follower bears against the maximum area of the blade section (to within 2 mm), the thickness of the blade, measured along the X axis of the damper, is constant in the reinforced zone. the thickness of the blade, measured along the X axis of the damper is constant over the entire blade. - If desired, when the blade is observed along the axis X of the damper, the reinforced zone has a boss, through which the section of maximum surface area. the boss is on an edge of the blade that is opposite to the cam surface, the boss is substantially rounded. the boss has a thickness equal to the thickness of the blade, the boss extends over an angular sector of less than 40 degrees, for example less than 30 degrees. the boss extends over an angular sector in which is completely comprised the roller. if desired, the blade comprises a section of constant section included in the reinforced zone. the area of the section of the section of constant section is equal to the area of the section of maximum area. the section of constant section extends, circumferentially, over at least 3 mm, preferably at least 5 mm, especially over a length greater than the diameter of the roller. The implementation of a section of constant section simplifies the control of the manufacture of the blade, the cam follower is in contact with the section of constant section when the damper is in a high speed operating speed and low torque. - The damper is arranged so that, when the damper is mounted in the transmisson chain, the first and second elements are both located in the path taken by the engine torque. The damper is arranged so that, when the damper is mounted in the transmisson chain, one of the first and second elements is located in derivation relative to the path taken by the driving torque, that is to say out of the path taken by the engine torque. The invention also relates to a double damping flywheel in which one of the first and second elements is formed by a primary flywheel and the other of the first and second elements is formed by the secondary flywheel.

For example, the first element is formed by the primary flywheel and the second element is formed by the secondary flywheel.

According to one embodiment, the invention also provides a transmission chain and a motor vehicle comprising such a torsion damper.

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 half-sectional view of a double damping flywheel according to a first embodiment of the invention. - Figure 2 is a schematic view of a transmission member and the cam follower of the first embodiment, in a high speed operating speed and low torque. - Figure 3 is a schematic view of a transmission member and a cam follower according to a second embodiment, in a high speed operating speed and low torque.

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 X axis of rotation of the torsion damper determines the axial orientation. On the other hand, when a member of a cam follower is designated, the "radial" orientation is directed orthogonally to the Y axis of rotation of the follower of the cam follower. Nevertheless, when designating any other element of the vibration damper, the "radial" orientation is directed orthogonal to the axis X of rotation of the vibration damper. An element close to the axis in question is 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 closer to the engine being designated by the rear and an element intended to be placed closer to the gearbox being designated by before.

In relation with FIG. 1, a double damping flywheel 1 is seen comprising a primary flywheel 2 intended to be fixed at the end of a crankshaft of an internal combustion engine, not shown, and a steering wheel. secondary inertia 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, an annular portion 6 extending radially from the hub 5 and a cylindrical portion 7 extending axially forwardly from the outer periphery of the annular portion. 6. The primary flywheel 2 is provided with orifices (not shown) allowing the passage of fixing screws for fixing the primary flywheel 2 on the crankshaft of the engine. The primary flywheel 2 carries, on its outer periphery, a ring gear 8 for driving in rotation of the primary flywheel 2, using a starter.

The secondary flywheel 3 comprises a flat annular surface 9, turned forwards, intended to form a bearing surface for a friction lining of a clutch disc, not shown. The secondary flywheel 3 has, close to its outer edge, studs and orifices, not shown, for mounting a cover of the clutch device. The secondary flywheel 3 further includes orifices, not shown, arranged vis-à-vis the orifices formed in the primary flywheel 2, and intended for the passage of the fastening screws of the primary flywheel 2 on the crankshaft, during assembly of the double damping flywheel 1 on the crankshaft.

With reference to FIG. 1, it can be seen that the double damping flywheel 1 comprises cam follower elements 11 which are fixed on the primary flywheel 2 and each have a roller 12 mounted rotatably on the primary flywheel 2 around a Y axis of rotation. Each roller is arranged to roll on a cam surface as the cam follower moves on the cam surface. Each roller 12 cooperates with a cam surface 44 carried by an elastic blade 13 of a transmission member 10 fixed to the secondary flywheel 3. The rollers 12 are arranged radially outside their respective cam surface 44 so as to radially maintain the resilient blades 13 when subjected to centrifugal force. The rollers 12 are arranged to roll against said cam surface 44 during a relative movement between the primary flywheels 2 and secondary 3.

The first element is thus formed here by the primary flywheel 2 and the second element is formed by the secondary flywheel 3. The reverse mounting may also be possible. The transmission member comprises a fixing portion 25 fixed to the second element, here to the secondary flywheel 3, and also comprises the blade.

Each cam surface 44 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 roller 12 moves on the cam surface 44 and, in doing so, exerts a bending force on the elastic blade 13. By reaction, the elastic blade 13 exerts on the roller 12 a restoring force having a circumferential component which tends to bring back the primary flywheels 2 and secondary 3 to their relative angular position of rest. Thus, the resilient blades are capable of transmitting 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). Moreover, 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 elastic blades 13. For more details on the operation and the structure resilient blades 13, in particular may be referred to documents FR3000155, FR3002605 and FR3008152.

Each cam follower 11 comprises a rod 14 which comprises an attachment 15 and a support portion 16. The attachment 15 is cylindrical of complementary shape to an orifice 17 formed in the annular portion 6 of the primary flywheel 2. The fixing portion 15 is advantageously force-fitted into said orifice 17.

The roller 12 is rotatably mounted around the rod 14. The support portion 16 projects axially forwardly from the annular portion 6, that is to say in the direction of the secondary flywheel 3. The roller 12 is mounted in rotation along the Y axis on the support portion 16. In order to reduce the parasitic friction, the roller 12 is rotatably mounted on the fastening portion 16 by means of a plurality of rolling bodies. The rolling bodies 18 are for example balls, rollers or needles. The rolling bodies 18 are disposed in a running space which is formed between an outer raceway which is formed on the inner periphery of the roller 12 and an inner raceway which is formed on the outer periphery of the support portion 16.

It can be seen in FIG. 2, which describes the transmission member of FIG. 1, that the transmission member 10, carried by the secondary flywheel 3, comprises an elastic blade 13 capable of flexing and transmitting a torque of rotation between these two flywheels, the bending of the elastic blade 13 being accompanied by a relative rotation between the flywheels of primary and secondary inertia, along the axis of rotation X.

The elastic blade 13 comprises a cam surface 44. The double damping flywheel 1 comprises a cam follower 11 arranged to move on this cam surface 44 during a relative rotation between the two flywheels.

The elastic blade 13 locally comprises, on its portion having the cam surface 44, a reinforced zone Z having a section of maximum area A. A blade section is obtained here by the intersection of the blade with a parallel plane P to the X axis and locally perpendicular to the tangent to the profile of the cam surface observed in a plane perpendicular to the X axis.

The reinforced zone Z extends circumferentially about the X axis, over an angular sector S of about 30 degrees. This angular sector extends here 15 degrees on either side of the maximum area section A of the blade 13.

Figure 2 illustrates the position occupied by the cam follower when the dual mass flywheel is in a high speed and low torque operating speed. Note that the blade 13 bears against the cam follower 11 via its reinforced zone Z. Thus the blade is reinforced locally in its contact zone with the cam follower when the damper is in a high speed operation regime. and low torque.

When the damper is at rest, the roller 12 is also fully included in this angular sector S.

The position of the cam follower shown in FIG. 2 corresponds more precisely to a particular speed called "burst" corresponding to a speed of about 12000 rpm and a torque of between 0 and 10 Nm, in particular close to 0, for which the cam follower is preferably in contact with the maximum area section A of the blade (within 2 mm).

For other operating speeds at high speed and low torque (other than the burst), the contact between the cam follower 11 and the blade 13 is possible at any point on the cam surface 44 belonging to the reinforced zone Z.

The maximum area section A is the largest section in the portion of the blade 13 having the cam surface 44. This elastic blade 13 is made of metal, for example steel, for example by cutting sheet.

The reinforced zone Z has, circumferentially, a length L greater than 5 mm, for example between 5 mm and 30 mm, in particular between 10 mm and 20 mm, for example 15 mm. The average area of the section of the reinforced zone Z is greater than the area of the average section of the blade 13.

The length of the reinforced zone is here greater than the thickness of the reinforced zone and its maximum height (in section A).

According to this embodiment, when no torque is transmitted by the damper 1 or when the damper is at rest, the cam follower 11 is also in abutment against the reinforced zone Z.

The maximum area section A is a solid section. The blade 13 is here full on all of its sections. The thickness of the blade 13 along the X axis of the damper is between 4 mm and 20 mm, preferably between 6 mm and 15 mm, for example 10 mm.

The flexible blade 13 comprises a free end zone 30 arranged to approach the axis of rotation X of the damper 1 when the blade 13 bends under the action of the cam follower 11. This free end zone 30 is arranged in the extension of the cam surface 44.

The blade 13 is arranged so that the concentrated stresses in the reinforced zone Z, when the damper 1 is in a high speed and low torque operating speed, are less than the elastic limit of the material in which the reinforced zone is formed. of the blade.

In this example, the blade 13 is arranged so that the stresses concentrated in the reinforced zone Z, when the damper 1 is in a high speed and low torque operating speed, are less than 500 MPa. The transmission member 10 comprises a fixing portion 25 fixed to the secondary flywheel 3.

The blade comprises a deformation portion D extending between the attachment portion 25 of the transmission member 10 and the blade portion having the cam surface 44.

This deformation portion D has a minimum area section B. A blade section is obtained here by the intersection of the blade with a plane P parallel to the axis X and locally perpendicular to the tangent to the outer contour of the observed blade. in a plane perpendicular to the X axis.

The deformation portion has an elbow.

It can be seen in FIG. 2 that the blade section decreases from the maximum area section A to the minimum area section B of the deformation portion D of the blade.

The cam surface 44 has two ends e1 and e2. The end e1 is on the side of the free end zone 30. The end e2 is on the side of the deformation portion D. Here, the blade section decreases on 100% of the angular arc starting from the cross section. maximum area A and ending at the end el of the cam surface 44. The blade section decreases from the maximum area section A to the free end area 30 of the blade 13. The thickness of the blade 13, measured along the axis X of the damper, is constant in the reinforced zone Z. The thickness of the blade 13, measured along the X axis of the damper is constant over the entire blade 13.

In FIG. 2, it can be seen that, when the blade is observed along the X axis of the damper, the reinforced zone Z has a boss 80 through which the maximum surface area A passes. The boss 80 is on one edge of the blade which is opposed to the cam surface 44. This boss 80 is substantially rounded.

The boss 80 has a thickness equal to the thickness of the blade 13.

The boss 80 extends over an angular sector S of about 30 degrees.

FIG. 3 illustrates, for a second embodiment of the invention, the position occupied by the cam follower 111 when the double damping flywheel is in a high speed and low torque operating speed.

In this second embodiment, the elements that are identical or that fulfill the same function bear the same reference as that which they bear in the first embodiment increased by 100.

The blade 113 here comprises a section of constant section 190 included in the reinforced zone Z.

The area of the section of section of constant section 190 is equal to the area of the section of maximum area A.

The section of constant section here extends over 18 mm.

The cam follower 111 is in contact with this section of constant section 190 when the damper is in a high speed and low torque operating speed. The cam follower 111 is also in contact with this section of constant section 190 when the damper is at rest.

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 as well as their combinations if these are within the scope of the invention. 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.

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

Claims (13)

1. Damper (1), in particular an automobile torsion damper, the damper comprising: - a first element (2) movable in rotation with respect to an axis of rotation X, - a second element (3) movable in rotation around the axis of rotation X relative to the first element, - a transmission member (10, 110) carried by the second element, comprising a resilient blade (13, 113) capable of bending and transmitting a torque between these two elements, the flexion of the elastic blade being accompanied by a relative rotation between the first and second elements, along the axis of rotation X, the elastic blade having a cam surface (44, 144), the damper comprising a follower cam follower (11, 111) arranged to move on said cam surface during relative rotation between the first and second members, characterized in that the elastic blade (13, 113) locally has on its portion having the surface cam, a reinforcing zone (Z) having a maximum area section (A), and when the damper is in a high speed and low torque operating speed, the blade bears against the cam follower on this reinforced area. 2. Damper according to the preceding claim characterized in that the reinforced zone (Z) extends circumferentially about the axis X, on an angular sector S less than 40 degrees. 3. Shock absorber according to one of the preceding claims characterized in that the angular sector (S) extends at most 20 degrees on either side of the maximum area section (A) of the blade (13). 4. Shock absorber according to one of the preceding claims characterized in that the blade section decreases over at least 50% of at least one of the angular arches from the maximum area section (A) and ending at one end (el e2) of the cam surface (44, 144). 5. Shock absorber according to one of the preceding claims characterized in that the flexible blade comprises a free end zone (30) arranged to approach the axis of rotation of the damper when the blade bends under the action of cam follower, and the blade section decreases over 100% of the angular arc starting from the maximum area section (A) and ending at the free end area (30) of the blade. 6. Damper according to one of the preceding claims characterized in that the blade (13, 113) is arranged so that the concentrated stresses in the reinforced zone (Z), when the damper (1) is in an operating regime at high speed and low torque, are below the elastic limit of the material in which the reinforced zone of the blade is formed. 7. Damper according to one of the preceding claims characterized in that the transmission member (10, 110) comprises a fixing portion (25, 125) attached to the second element and the blade (13, 113) comprises a portion of deformation (D) extending between the attachment portion (25, 125) of the transmission member and the blade portion having the cam surface (44, 144), said deformation portion (D) having a section of minimum area (B). 8. Shock absorber according to the preceding claim characterized in that the blade section decreases from the maximum area section (A) to the minimum area section (B) of the deformation portion (D) of the blade (13, 113). 9. Damper according to one of the preceding claims characterized in that, when the blade (13) is observed along the axis X, the reinforced zone (Z) comprises a boss (80), through which the section of maximum surface area (AT). 10. Damper according to one of the preceding claims characterized in that the boss (80) is on an edge of the blade which is opposite the cam surface (44,144). 11. Shock absorber according to one of the preceding claims characterized in that the blade comprises a section of constant section (190) included in the reinforced zone (Z). Damper according to one of the preceding claims, characterized in that the area of the section of the section of constant section (190) is equal to the area of the section of maximum area (A). 13. Shock absorber according to one of the preceding claims, wherein one of the first and second elements is formed by a primary flywheel (2) of a double damping flywheel and the other of the first and second elements is formed by a secondary flywheel (3) of the double damping flywheel.