WO2018108870A1

WO2018108870A1 - Leaf spring torsion damper

Info

Publication number: WO2018108870A1
Application number: PCT/EP2017/082346
Authority: WO
Inventors: Roel Verhoog; Daniel Fenioux
Original assignee: Valeo Embrayages
Priority date: 2016-12-14
Filing date: 2017-12-12
Publication date: 2018-06-21
Also published as: FR3060087B1; FR3060087A1

Abstract

The invention relates to a torsion damper for a motor vehicle, notably for a motor vehicle drivetrain, comprising: – a first element (7) intended to be mounted on a nose (8) of a crankshaft (1) coupled to pistons (2, 27), the said first element (7) having a geometric axis of pivoting (13) about which the first element (7) pivots when mounted on the nose (8) of the crankshaft (1); – a second element (9) mounted with the ability to rotate with respect to the first element (7), – a leaf-spring damping member comprising two cam surfaces and two cam followers (11), which is arranged between the first element (7) and the second element, the cam followers (11) defining a geometric axis of pressing of the cam followers (11), the damper being arranged in such a way that no pressing of a cam follower on its cam surface falls, in projection onto a plane perpendicular to the axis of rotation (X), in a critical angular sector, the said critical angular sector (Cr) being greater than or equal to 40 degrees and extending on either side of the perpendicular (P) to the geometric axis of pivoting (13).

Description

TORSION DAMPER WITH BLADES

Technical area

The invention relates to the field of torsion dampers for equipping motor vehicle transmissions.

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.

The document FR3008152 discloses a double-leaf 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 elastic damping means which are formed of a plurality of resilient blades mounted on one of the flywheels. These flexible blades each carrying a cam surface each cooperate with an associated roller mounted to rotate 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.

In the case of a torque transmission device for a motor vehicle, in order to transmit the torque generated by the combustion engine, the primary flywheel of the double damping flywheel is mounted on the nose of the crankshaft of the internal combustion engine.

It has been found that when the pistons rotate the crankshaft beyond a predetermined speed, they generate an oscillation movement of the crankshaft nose related to the irregularities of the engine explosions. This oscillation movement results in a tilting movement of the steering wheel primary mounted on said nose of the crankshaft about a preferred tilting axis which is perpendicular to the axis of rotation and has a defined angular orientation relative to the crankshaft.

However, the oscillation of the primary flywheel around this preferred tilting axis is not transmitted to the secondary flywheel so that the primary flywheel and the secondary flywheel are not continuously oriented parallel to each other when the crankshaft is rotated by the engine pistons. Thus, the cam followers and the cam surfaces not being held in an optimal cooperation orientation when the primary flywheel is inclined relative to the secondary flywheel, the cooperation between the cam followers and the cam surfaces is degraded by the axial movements of the cam followers caused by the tilting of the primary flywheel. Such tilting of the primary flywheel with respect to the secondary flywheel is likely to cause abnormal operation of the double damping flywheel and deterioration of the cam followers and / or the cam surfaces or the elastic link. This is particularly detrimental when the torque transmitted between the primary flywheel and the secondary flywheel is important since, in this case, heavy loads are likely to be exerted on the cam followers and the flexible blades while they are in an orientation. relative inappropriate.

summary

There is therefore a need for a torsion damper of the aforementioned type in which the damaging effects of the phenomenon of oscillation of the nose of the crankshaft are limited.

For this, the invention provides a torsion damper for a motor vehicle, in particular for a motor vehicle chain, comprising:

a first element having a perpendicular axis of rotation and a geometric axis of tilting, the first element comprising fastening means adapted to mount the first element in a predetermined angular position of mounting on a nose of a crankshaft, the geometric axis of tilting corresponding to an axis about which the first element tilts when said first element is mounted on the nose of the crankshaft in the predetermined angular position and that said crankshaft nose is rotated

a second member rotatably mounted relative to the first member about the axis of rotation, the first and second members being rotatable relative to each other over an angular range of travel extending between a first extreme position and a second extreme position,

a resilient damping member arranged to transmit torque and dampen the acyclisms between the first member and the second member, the resilient damping member having at least one cam surface, at least one cam follower and at least one link resilient, each cam surface being associated with a respective cam follower and elastic linkage, each resilient link being deformable to provide resilient support between the cam surface and the corresponding cam follower and to enable said follower to cam to move in contact with said cam surface, the displacement of said cam follower on said cam surface being accompanied by a relative rotation between the first and second members,

wherein the damper is arranged such that for any relative angular position of the first and second members within the range of angular travel of the damper, no cam follower rest on its cam surface is projection in a plane perpendicular to the axis of rotation, in a critical angular sector, said critical angular sector being greater than or equal to 40 degrees and extending symmetrically on either side of the perpendicular to the geometric axis of tilting .

Thus, the most critical situation of tilting of the first element, that is to say the situation in which the first element tilts, especially at high speed, while the cam followers are in the most remote positions of the tilt axis, is avoided. Therefore, such a torsion damper makes it possible to ensure good cooperation between the cam surfaces and the cam followers. Thanks to these characteristics, the cooperation between the cam followers and the cam surfaces is significantly less disturbed by the tilting of the first element around its geometric tilt axis and regardless of the torque transmitted between the first element and the second element. .

In particular, the relative angular position of mounting of the first element on the crankshaft nose, the geometry and the length of the cam surface and the position occupied by the cam follower on the cam surface in the rest position is that is, when no torque is transmitted, are defined so as to prevent cam follower engagement on the cam surface from entering the critical angular sector.

According to one embodiment, the invention may include one or more of the following features.

According to one embodiment, the elastic damping member comprises an intrinsically flexible blade or a rigid blade connected to the first or the second element by an elastic member.

According to one embodiment, the tilting geometrical axis corresponds to an axis about which the first element tilts when said first element is mounted on the nose of the crankshaft in the predetermined angular position and that said crankshaft nose is rotated in rotation. beyond a predetermined rotation regime.

According to one embodiment, the predetermined rotational speed beyond which the first element tilts when said first element is mounted on the nose of the crankshaft is greater than 3500 rpm, in particular greater than 4000 rpm, in particular greater than 5000 rev / min.

According to one embodiment, the damper has a relative position of rest of the two elements when no torque is transmitted by the damper, this relative rest position being between the two extreme relative positions defining the range of angular deflection .

According to one embodiment, the range of angular deflection is greater than 60 degrees, in particular greater than 70 degrees, in particular greater than 80 degrees. According to one embodiment, the relative rest position of the two elements is circumferentially equidistant from the two extreme relative positions defining the range of angular deflection.

According to one embodiment, abutment elements are arranged on the first and second elements to come into mutual abutment in the first extreme position in a first direction of relative rotation.

According to one embodiment, stop elements are arranged on the first and second elements to come into mutual abutment in the second extreme position in a second direction of relative rotation.

According to one embodiment, the range of angular displacement is between a first relative angular position for transmitting a torque of the first element to the second element between 1 and 1, 3 times the maximum engine torque and a second relative angular position. for transmitting a torque of the second element to the first element between 1 and 1, 3 times the maximum engine torque.

According to one embodiment, in at least one relative position of the second element relative to the first element corresponding to a maximum torque threshold transmittable by the torsion damper, no cam follower support on its cam surface is located, in projection in a plane perpendicular to the axis of rotation (X), in a critical angular sector, said critical angular sector being greater than 40 degrees and extending symmetrically on either side of the perpendicular to the geometric axis tipping. Thus, in one of the most critical situations of tilting of the first element, that is to say when a maximum torque is transmitted by the torsion damper, the repercussions of the tilting of the first element around the axis Geometric tilt are limited by ensuring that each cam follower is not in the critical angular sector.

According to one embodiment the cam followers of each pair of cam followers and the cam surfaces of each pair of cam surfaces are respectively symmetrical with respect to the axis of rotation (X).

According to one embodiment, the first element and the second element have a relative position of rest in which no torque is transmitted between the first element and the second element, and in which the transmission of a torque between the first element and the second element is accompanied by a relative displacement between the first element and the second element, the relative position of the second element relative to the first element corresponding to the maximum torque threshold transmissible by the torsion damper being one of the first and second extreme positions of travel between the first element and the second element.

According to one embodiment, the damper is arranged so that, when the speed of rotation of the damper is greater than 3500 rpm, in particular greater than 4000 rpm, in particular greater than 5000 rpm, no cam follower support on its cam surface is situated, in projection in a plane perpendicular to the axis of rotation (X), in a critical angular sector, said critical angular sector being greater than 40 degrees and extending symmetrically on either side of the perpendicular to the geometric axis of tilting. Thus, in one of the most critical situations of tilting of the first element, that is to say when the tilting of the first element is maximal, the repercussions of the tilting of the first element around the geometric tilt axis are limited. ensuring that each cam follower is not in the critical angular sector.

According to one embodiment, the damper comprises, in a plane perpendicular to the axis of rotation, at least one pair of cam followers and at least one pair of cam surfaces, at least two elastic links, each elastic link being adapted to deform to provide resilient support between a cam surface and a respective cam follower and to allow said cam follower to move in contact with said cam surface, displacing the cam followers on their respective cam surfaces being accompanied by a relative rotation between the first and second members, each cam follower having a bearing on the cam surface with which it cooperates so that each pair of cam followers defines a geometric bearing axis substantially perpendicular to the cam. axis of rotation and passing through the axis of rotation, the damper being arranged so that for any relative angular position of the first and second element ts located in the range of angular deflection of the damper, no geometric support axis is, in projection in a plane perpendicular to the axis of rotation, located in the critical angular sector. So, we obtains a balanced damper in which the consequences of the tilting of the first element are limited.

When the damper comprises, in a plane perpendicular to the X axis, exactly two cam followers, the damper is balanced and the angular displacement of the damper is satisfactory.

According to one embodiment, the critical angular sector is greater than 60 degrees, in particular greater than 80 degrees, and extends symmetrically on either side of the perpendicular to the geometric tilt axis. Thus, the inconvenience in case of failover are further limited.

According to one embodiment, the critical angular sector is greater than

82 degrees, especially greater than 92 degrees, especially greater than 98 degrees, in particular greater than 106 degrees and extends symmetrically on either side of the perpendicular to the geometric tilt axis.

Thus, the maximum distance between the cam followers and the tilting axis is reduced by approximately 25%, 30%, 35% and 40% respectively, which significantly reduces wear and damping disturbances in the event of a tilt. of the first element.

According to one embodiment, each cam follower support on its cam surface is located in a target angular sector when the rotation speed of the first element is greater than 3500 rpm, especially greater than 4000 rpm, the angular sector. target being less than 40 degrees and extending symmetrically on either side of the geometric axis of tilting.

According to one embodiment, each cam follower support on its cam surface is located, in at least one relative position of the second element with respect to the first element corresponding to a maximum torque threshold transmittable by the torsion damper, in a target angular sector, the target angular sector being less than 40 degrees and extending symmetrically on either side of the geometric axis of tilting.

According to one embodiment, the cam surfaces are resiliently connected to the second member and the cam followers are carried by the first member. The cam followers being carried by the first element, for example by being rotatably mounted on the first element, and moving on the cam surfaces, the cam follower support on the cam surfaces is fixed relative to the first member. Consequently, thanks to these characteristics, the geometric axis of support is fixed relative to the first element and this whatever the torque transiting between the first element and the second element. Thus, the cam followers can be placed closer to the tilting axis so that for any torque transmitted between the first and second members, the cooperation between the cam followers and the cam surfaces is not or little disturbed by the tilting of the first element.

According to one embodiment, the crankshaft on which the first element is intended to be mounted is coupled to pistons rotating said crankshaft about said axis of rotation, and wherein the piston closest to the nose of the crankshaft is slidably mounted. a sliding axis, the tilting geometric axis being offset by an angle of between 5 and 10 ° in a direction of rotation of the first element relative to the perpendicular to said axis of sliding of the piston closest to the nose crankshaft in a top dead center position of said piston.

According to one embodiment, each cam follower support on its cam surface is located in a target angular sector, the target angular sector being less than 40 degrees, in particular less than 30 degrees, in particular less than 20 degrees and extending symmetrically on both sides of the geometric tilt axis. Thus, the axial displacement of the cam followers is low in case of tilting of the first element.

According to one embodiment, each cam surface is carried by a respective flexible blade, each flexible blade having a mounting portion attached to said one of the first member and the second member and a flexible portion carrying said cam surface. Thus the structure of the damper is particularly simple.

Where appropriate, the elastic connection providing the elastic support between the cam surface and the cam follower is at least partly formed by the flexible portion of the flexible blade.

According to one embodiment, each cam surface is formed on a radially outer face of the flexible portion, each cam follower being arranged radially outside the cam surface with which it cooperates. With these features, the blades are retained by the cam followers when subjected to a centrifugal force related to the rotation of one of the first member and the second member carrying said blades.

According to one embodiment, each cam surface is elastically connected to one of the first element and the second element and each cam follower is a roller rotatably mounted on said other one of the first element and the second element.

According to one embodiment, each roller is rotatably mounted on a rod, said rod being parallel to the axis of rotation, said rod being fixed on the other of the first element and the second element.

According to one embodiment, each cam surface is elastically connected to one of the first element and the second element and the other element of the first element and the second element comprises two complementary cam surfaces, each cam follower being arranged radially. between a cam surface and a complementary cam surface so that, at a relative deflection between the first member and the second member, the cam follower moves both on the cam surfaces elastically connected to one of the first element and the second element and on the cam surfaces complementary to said other one of the first element and the second element. Thus, the cam followers do not require complex fastening means on the first or the second element. In addition, the angular displacement between the first and second elements of the damper can also be increased in comparison with an embodiment in which the cam follower is rotatably mounted about a fixed axis relative to the first element or to the second element. In fact, because of the rolling of the cam followers on two cam surfaces radially facing each other, when the cam follower moves at an angle A on the cam surface, the angular displacement between the cam follower first element and the second element is 2A. With respect to an embodiment wherein the cam followers are rotatably mounted on the second member, the angular displacement of the cam followers relative to the first member is halved and the critical angular sector to be avoided can be extended. According to one embodiment, the first element comprises a polarizer intended to cooperate with a complementary polarizer of the nose of the crankshaft in order to define the predetermined angular position of the first element on the nose of the crankshaft. With these features, the first element can be positioned on the nose of the crankshaft simply and directly in the predetermined angular position.

According to one embodiment, the first element comprises through holes intended to be traversed by fasteners, said passage orifices being circumferentially distributed irregularly around the axis of rotation X, the nose of the crankshaft further comprising fixing holes distributed circumferentially identical to the circumferential distribution of the passage orifices of the first element so as to allow the attachment of the first element on the nose of the crankshaft in the predetermined angular position by cooperation of each fastener with a joint through hole and a respective fixing hole.

Thanks to these features, the first element can be positioned in the predetermined angular position by directly producing the polarizer with the passage orifices of the first element, said passage orifices of the first element and the fixing holes of the crankshaft nose. jointly fulfilling the function of polarizer and fixing means of the first element on the nose of the crankshaft.

According to one embodiment, the passage orifices are asymmetrical with respect to the axis of rotation X.

According to one embodiment, the invention also provides a motor vehicle transmission chain comprising a crankshaft and pistons coupled to the crankshaft so as to rotate the crankshaft about an axis of rotation, the transmission chain further comprising a torsion damper as above, the first member of said torsion damper being mounted in a predetermined angular position on a nose of the crankshaft.

According to one embodiment, the relative position of the second element with respect to the first element corresponding to the maximum torque threshold transmissible by the torsion damper is a position in which the travel between the first element and the second element relative to a relative position of rest is maximal.

The invention also relates to a torsion damper for a motor vehicle, particularly for a motor vehicle chain, comprising:

a first member having a perpendicular axis of rotation and a geometrical axis of tilting, the first member being adapted to be mounted in a predetermined angular position on a nose of a crankshaft, the crankshaft being coupled to pistons rotating said crankshaft around said axis of rotation, the geometric tilt axis corresponding to an axis about which the first element tilts when said first element is mounted on the nose of the crankshaft in the predetermined angular position and said crankshaft nose is rotated;

a second element rotatably mounted relative to the first element about the axis of rotation,

damping means arranged to transmit a torque and dampen the acyclisms between the first element and the second element and having two cam surfaces elastically connected to the second element and two cam followers carried by the first element so as to cooperate each with a cam surface,

wherein the supports of the cam followers on the cam surfaces define a bearing geometrical axis, said bearing geometrical axis being perpendicular to the axis of rotation and, in projection in a plane perpendicular to the axis of rotation, said geometric support axis being parallel to the geometric axis of tilting or inclined relative to the geometric axis of tilting by an angle less than 20 °.

According to one embodiment, the cam followers are rollers mounted rotatably on the first element. The damper may be a double damping flywheel, the first element forming a primary flywheel and the second element forming a secondary flywheel.

An idea underlying the invention is to ensure a good orientation of cam followers and blades including in the presence of oscillations of the primary flywheel and a large torque transmission between the primary flywheel and the secondary flywheel.

Brief description of the figures

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 accompanying drawings.

- Figure 1 is a schematic side view of a transmission chain comprising a crankshaft coupled to four pistons of a combustion engine, a torsion damper blade not in accordance with the invention being mounted on said crankshaft, with the cam followers in the critical angular sector .;

- Figure 2 is a front view of a torsion damper according to a first embodiment in which the secondary flywheel is omitted, the damper in a relative position of rest between the primary flywheel and the secondary flywheel.

FIG. 3 is a front perspective view of a double damping flywheel according to a second embodiment in which the secondary flywheel is omitted to visualize the cam surfaces and the cam followers.

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 torsion damper. By convention, the "radial" orientation is directed orthogonal to the axis (X) of rotation of the torsion damper determining the "axial" orientation and, from the inside towards the outside away from said axis (X) rotation. The "circumferential" orientation is directed orthogonally to the axis (X) of rotation of the torsion damper and orthogonal to the radial direction. Terms "external" and "internal" are used to define the relative position of one component relative to another, with reference to the axis (X) of rotation of the torsion damper, a component close to said axis is thus qualified internally as opposed to an outer component radially peripherally. The remainder of the description is made with reference to the figures in the context of a torsion damper of the double damping flywheel type. This description is not limiting and the invention is applicable by analogy to any other type of torsion damper comprising two elements mounted in relative rotation and coupled by a torque transmission member and damping acyclisms and whose one of the elements is mounted on a crankshaft nose of a combustion engine.

FIG. 1 illustrates a motor vehicle transmission chain in which a crankshaft 1 is associated with four pistons 2 of an internal combustion engine (not shown). The four pistons 2 are aligned in the same plane common to the axis of rotation X of the crankshaft 1. Each piston 2 has a first end 3 movably housed in an explosion chamber 4 and a second end 5, opposite the first end 3, coupled to the crankshaft 1.

In known manner, during successive explosions in the engine, the pistons 2 slide in the explosion chambers 4. The second ends 5 of the pistons 2 are each coupled to the crankshaft 1 by a connecting rod and a crankpin so that during the movements of pistons 2 in the explosion chambers 4, the crankshaft 1 is rotated about the axis of rotation X. This rotation of the crankshaft 1 is intended to be transmitted to a driven shaft such as a box input shaft. speed (not shown).

In order to transmit the torque between the crankshaft 1 and the driven shaft and to dampen the acyclisms generated by the explosions in the internal combustion engine, a torsion damper 6 is arranged between the crankshaft 1 and the driven shaft. More particularly, a primary flywheel 7 of the torsion damper 6 is mounted on a nose 7 of the crankshaft 1 and a secondary flywheel 9 of the torsion damper 7 is intended to form the reaction plate of the engine. a clutch, not shown, connected to the input shaft of a gearbox. The primary flywheel 7 and the secondary flywheel 9 are mounted centrally and in rotation relative to one another about the axis of rotation X via a bearing 10 (see FIG. 2). Such a bearing is for example a plain bearing, a rolling bearing or other.

A damping member with blades makes it possible to transmit the torque and to dampen the acyclisms between the primary flywheel 7 and the secondary flywheel 9. Such a blade damping member comprises rollers 11 mounted on the primary flywheel 7 and cooperating with flexible blades 12 mounted on the secondary flywheel 9. Such a blade damping member is described below in more detail with reference to Figure 2.

For legibility issues, Figure 1 illustrates the torsion damper 6 in an exploded manner, the primary flywheel 7 being away from the secondary flywheel 9. In operation the primary and secondary flywheels 7, 9 are arranged with the aid of the bearing 10 so that the flexible blades 12 and the rollers January 1 are located in the same radial plane in order to cooperate together.

It has been found that, in operation, an flywheel mounted on a crankshaft deforms in diametric flexion (bending deformation in which the flywheel tilts along a diametral axis) and in oscillation around a geometric tilt axis 13 which is perpendicular to the axis of rotation X and which has a determined angular position relative to the crankshaft 1, this oscillation being linked to a bending of the last crankpin crankshaft 1. The geometric tilt axis 13 is perpendicular to the axis of rotation X. The primary flywheel may be more or less inclined relative to the axis of rotation X as illustrated by the arrows 14 in Figure 1, depending on the amplitude of the oscillations of the primary flywheel.

FIG. 1 illustrates, by way of deliberately exaggerated example, two extreme positions of the primary flywheel 7 that can be reached during the tilting of the primary flywheel 7 around the geometric tilt axis 13. In this example, the rollers are in a critical angular sector remote from the tilting axis 13, which causes a significant axial movement of the rollers in case of tilting of the primary flywheel.

The rollers 1 1 being fixed on the primary flywheel 7, the tilting of the primary flywheel 7 around its geometric tilt axis 13 is echoes at the rollers 1 1 by a tilting of said rollers 1 1 which make them move away from their normal operating plane, namely a plane perpendicular to the axis of rotation X. Or the secondary flywheel 9 linked to the primary flywheel 7 by a bearing is only slightly subject to tilting caused by the displacement of the nose 8 of the crankshaft 1 so that the flexible blades 12 remain in a plane perpendicular to the axis of rotation X. In other words , the support of the rollers 1 1 on the cam surfaces 26 carried by the flexible blades 12 varies as a function of the degree of tilting of the primary flywheel 7 around its geometric tilt axis 13.

Also, when the rollers are remote from the axis of tilting of the primary flywheel, especially when the rollers are in a critical angular sector Cr located in the vicinity of a perpendicular to the tilting axis, the tilting of the primary flywheel can cause a large tilting of the rollers, as shown in Figure 1. The tilting of the rollers 1 1 associated with the absence of tilting of the flexible blades 12 does not allow an optimal cooperation between the rollers 1 1 and the flexible blades 12.

FIG. 2 is a front view of a torsion damper 6 according to a first embodiment of the invention in which the secondary flywheel 9 is omitted and in a relative position of rest between the primary flywheel 7 and the secondary flywheel 9.

The primary flywheel 7 comprises a radially inner hub 16 supporting an inner ring of the bearing 10, an annular portion 17 extending radially from the radially inner hub 16 and a cylindrical portion 18 extending axially on the opposite side to the motor. , from the outer periphery of the annular portion 17. The annular portion 17 is provided with passage holes 19 of fastening screws (not shown) for fixing the primary flywheel 7 on the nose 8 of the crankshaft 1 .

The passage holes 19 illustrated in Figure 2 are distributed circumferentially irregularly. More particularly, the primary flywheel 7 illustrated in FIG. 2 has six through-holes 19. Five common through-holes 29 are arranged circumferentially around the axis of rotation X in a regular angular pitch, typically an angular pitch of 60 degrees. The sixth passage opening 19 is a singular passage opening 30 and is arranged circumferentially at a distinct angular pitch of each adjacent through-hole 29. In the example illustrated in FIG. 2, this singular passage orifice 30 is angularly distant from a first 45 degree angle of a first adjacent current flow orifice 29 and a 75 degree angle of a second orifice of current passage 29 adjacent. The nose 8 of the crankshaft 1 has a plurality of attachment orifices (not shown) complementary to the passage orifices 19 of the primary flywheel 7, that is to say circumferentially distributed identical to the passage orifices 19. Thus, when the primary flywheel 7 is mounted on the nose 8 of the crankshaft 1, each passage opening 19 is in axial vis-à-vis of a mounting orifice of the nose 8 of the complementary crankshaft so that the steering wheel primary inertia 7 can be fixed on the nose 8 of the crankshaft 1 with screws, each screw cooperating with a respective through hole 19 and a fixing hole.

Because of this irregular circumferential distribution of the orifices of passages 19, the orifices of passages 19 are asymmetrical with respect to the axis of rotation X. The orifices of passage 19 thus fulfill the function of polarizer allowing the positioning in a single angular position of the first element on the nose 8 of the crankshaft.

In a non-illustrated embodiment, this keying function to indicate a single angular position of attachment of the primary flywheel 7 on the nose 8 of the crankshaft 1 can be achieved by any other means such as for example by a mark made on the primary flywheel 7 and on the crankshaft, by a lug of the primary flywheel 7 cooperating with a housing of the nose 8 of the crankshaft 1 or any other means. The secondary flywheel 9 has a radially outer hub 20 carrying an outer ring of the bearing 10, a flat annular surface (not shown) extending radially from the radially outer hub 20 and facing the opposite side to the primary flywheel 7, this annular surface forming a bearing surface for a friction lining of a clutch disc (not shown). The secondary flywheel 9 further comprises orifices (not shown), arranged vis-à-vis the through-holes 19 formed in the primary flywheel 7, and intended for the passage of the screws, during assembly of the primary flywheel 7 on the nose 8 of the crankshaft 1. The blade damping member comprises two flexible blades 12 mounted integral in rotation with the secondary flywheel 7. These two flexible blades 12 are symmetrical with respect to the axis of rotation X.

Each flexible blade 12 has a fastening portion 21 fastened to the secondary flywheel 9 by three fastening rivets in order to enable the flexible blades 12 to be secured in rotation with the secondary flywheel 9. The fastening portion 21 of the fasteners 21 flexible blades 12 develops circumferentially around the radially outer hub 20

The fastening portion 21 is extended by a flexible portion 22. This flexible portion 22 is curved and extends substantially circumferentially. The radius of curvature of the flexible portion 22 as well as the length of this flexible portion 22 are determined according to the desired stiffness of the flexible blade 12. The flexible blade 12 can, as desired, be made in one piece or be composed of a plurality of lamellae arranged axially against each other. The flexible portion 22 of each flexible blade 12 carries on a radially outer face a cam surface 26. These cam surfaces 26 are arranged to cooperate with a respective cam follower, typically a respective roller 1 1 carried by the flywheel primary 7.

The rollers 1 1 are carried by cylindrical rods 24 fixed to the primary flywheel 7. The rollers January 1 are rotatably mounted on the cylindrical rods 24 about an axis of rotation parallel to the axis of rotation X In order to reduce the parasitic friction likely to affect the damping function, the rollers 1 1 are advantageously rotatably mounted on the cylindrical rods 24 by means of a rolling bearing. For example, the rolling bearing may be a ball bearing or roller. In one embodiment, the rollers 1 1 have an anti-friction coating.

Each roller 1 1 has an inner radial end forming, in the axial thickness of said roller 1 1, a bearing line 25 of the roller January 1 on a cam surface 26 carried by a respective flexible blade 12. Similarly, the axial thickness of the cam surfaces 26 defines a moving surface of the bearing line 25 of the rollers 1 1. This displacement surface develops parallel to the axis of rotation X. In other words, the line of 25 support of each roller 1 1 is intended to be in contact with the displacement surface of a respective cam surface 26 and to move on said moving surface at an angular displacement between the primary flywheel 7 and the secondary flywheel 9. support 25 of the two rollers 1 1 thus define a contact plane of the rollers 1 1 on the cam surfaces 26 having the axis of rotation X. The rollers 1 1 are advantageously arranged radially outside their cam surface 26 respective so as to maintain radially flexible blades 12 when subjected to centrifugal force.

The cam surface 26 and the rollers 11 are arranged such that, for an angular displacement between the primary flywheel 7 and the secondary flywheel 9, relative to a relative angular position of rest, the roller 1 1 moves on the cam surface 26 and, in doing so, exerts a bending force on the flexible blade 12. By reaction, the flexible blade 12 exerts on the roller 1 1 a restoring force which tends to reduce the flywheels primary and secondary inertia 7, 9 to their relative angular position of rest. Thus, the flexible blades are capable of transmitting a driving torque from the primary flywheel 7 to the secondary flywheel 9 (forward direction) and a resistant torque of the secondary flywheel 9 to the primary flywheel 7 (retro sense).

The angular displacement between the primary flywheel 7 and the secondary flywheel 9 is limited by an end stop comprising a stop 31 on the primary flywheel 7 facing a circumferential circumference of a stop 32 on the secondary flywheel 9. The document FR3008152 describes the general operation of such a torsion damper with flexible blades 12.

FIG. 2 illustrates an embodiment of the invention in which the cam followers 1 1 are rotatably mounted on the first element 7. As illustrated in FIG. 2, the primary flywheel 7 is advantageously mounted on the nose 8 of the crankshaft 1 so that the geometric tilt axis 13 of the primary flywheel 7 defined by the crankshaft 1 is included in the contact plane defined by the bearing lines 25 of the rollers January 1. The tilting of the primary flywheel 7 linked to the deflection of the nose 8 of the crankshaft 1 being around the geometric axis of tilting 13, the tilting of the primary flywheel 7 around the geometric tilt axis 13 n ' not lead to failover and axial displacement of the cam followers. The positioning of the primary flywheel 7 so that the contact plane defined by the bearing lines 25 of the rollers 1 1 comprises the geometric tilt axis 13 allows to maintain axially in position the bearing lines 25. The maintaining the bearing lines 25 axially in position makes it possible to keep said bearing lines 25 in a plane parallel to the axis of rotation X and therefore parallel to the displacement surfaces of the cam surfaces 26. Thus, the bearing lines Rollers 11 remain in contact with the displacement surfaces of cam surfaces 26 and provide good cooperation between rollers 11 and cam surfaces 26.

Indeed, a positioning of the primary flywheel 7 on the nose 8 of the crankshaft 1 so that the plane of contact of the rollers 1 1 on the cam surfaces 26 is, in an extreme case, perpendicular to the geometric axis of tilting 13 would, during a tilting of the primary flywheel, on the one hand a tilting around the geometric tilt axis 13 of the bearing lines 25 of the rollers and on the other hand an axial displacement of the cam followers that could cause axial friction of the cam followers on the cam surfaces or torsion of the blade in the event that the cam follower tends to axially drive the blade. In the extreme case where the plane of contact of the rollers 1 1 on the cam surfaces 26 is perpendicular to the geometric tilt axis 13, the axial displacement of the cam followers is maximum and the damping would be deteriorated. This is why the invention aims to reduce the axial displacement of the cam followers by arranging them at a distance from a critical angular sector Cr extending over at least 40 degrees on either side of the perpendicular to the axis. tilting 13.

Ideally, when the cam followers are carried by the primary flywheel as in Figure 1, the contact plane defined by the bearing lines 25 of the rollers January 1 comprises the geometric axis of tilting. However, an angular tolerance of 5 °, 10 °, 15 ° or even 20 ° can be envisaged without detrimental deterioration of the cooperation between the rollers 11 and the cam surfaces 26. This angular tolerance defines a target angular sector Ci.

In an aligned four-cylinder engine as shown in FIG. 1, the geometric tilt axis 13 is determined by the top dead center position of an end piston 27 (see FIG. 1) positioned closest to the nose 8 of the crankshaft 1 1. More particularly, the geometric tilt axis 13 is shifted by an angle of between 5 and 10 ° in a driving direction of the first element relative to the perpendicular to said sliding axis 28 of the piston 27 closest to the nose 8 of the crankshaft 1 in a neutral position top of said piston 27 This axis 28 of top dead center position of the end piston 27 is a manufacturer's data which is generally found in the mounting manual of the torsion damper.

In a non-illustrated embodiment, the flexible blades 12 are fixed on the primary flywheel 7 and the rollers January 1 are fixed on the secondary flywheel 9.

In this embodiment, the bearing lines 25 of the rollers 1 1 carried by the secondary flywheel 9 remain parallel to the axis of rotation X. Conversely, the displacement surface of the cam surface 26 carried by the primary flywheel 7 is subject to tilting of the primary flywheel 7 around its geometric tilt axis 13.

By fixing the flexible blades 12 on the primary flywheel 7, the displacement surfaces of the cam surfaces 26 are fixed relative to the geometric axis of tilting 13 of the primary flywheel 7 about the axis However, the angular displacement between the primary flywheel 7 and the secondary flywheel 9 during a transmission of torque between the primary flywheel 7 and the secondary flywheel 9 changes the speed. position of the bearing lines 25 of the rollers 1 1 on the displacement surfaces of the cam surfaces 26. In other words, the contact plane of the rollers 1 1 on the cam surfaces 26 is rotatable about the axis of rotation X with respect to the cam surfaces 26 as a function of the torque passing between the primary flywheel 7 and the secondary flywheel 9. Consequently, the contact plane of the rollers 11 on the cam surfaces 26 is also movable in rotation around the axis of rotat X ion with respect to the geometric axis of tilting 13 of the primary flywheel 7.

In such a configuration, it is therefore not possible to maintain the bearing lines 25 of the rollers 1 1 in the vicinity of the tilt axis irrespective of the torque passing between the primary flywheel 7 and the flywheel. secondary inertia 9. In order to avoid a maximum axial displacement, the damper is arranged so that for any relative angular position of the primary and secondary flywheels situated in the angular displacement range of the defined damper here by the stops 31 32, no cam follower support 1 1 on its cam surface 26 is located, in projection in a plane perpendicular to the axis of rotation X, in a critical angular sector Cr, said critical angular sector. Cr being greater than or equal to 40 degrees and extending symmetrically on either side of the perpendicular P to the geometric tilt axis 13. In other words, the primary flywheel 7 is positioned on the nose 8 of the crankshaft 1 so that the contact between the rollers 1 1 and the cam surfaces 26 is optimal when the torque to be transmitted between the primary flywheel 7 and the secondary flywheel 9 is the largest.

As in the previous embodiment, an angular variation is allowed, for example of the order of 5 to 10 degrees.

In the case of an engine with 3 cylinders or 6 cylinders, aligned or "V", the nose 8 of the crankshaft 1 behaves similarly to the behavior of a four-cylinder engine as illustrated in FIG. point of view of the geometric tilt axis 13. That is to say that the primary flywheel 7 has a geometric tilt axis 13 regardless of the number of cylinders of the engine. In particular, this geometric tilt axis has the same inclination with respect to the top dead center axis of the first piston regardless of the structure of the engine. The primary flywheel 7 can be positioned to optimize the cooperation between the rollers 1 1 and the cam surfaces 26 regardless of the number of cylinders of the engine.

According to another embodiment of the device of the torsion damper, the flexible blades 12 are attached to one of the primary and secondary flywheels 7, 9 and the other of the primary and secondary flywheels 7, 9 has other complementary cam surfaces 26 '. In this embodiment, the cam followers are rollers 1 1 mounted movably between the primary and secondary flywheels 7, 9. Thus, the rollers 1 1 can be respectively arranged radially between on the one hand the cam surfaces carried by one of the primary flywheel 7 and the secondary flywheel 9 and, on the other hand, the cam surfaces 26 of the flexible blades 12 so that a relative rotation between the primary and secondary flywheels 7, 9 is accompanied by both a displacement of the rollers 1 1 on the cam surfaces 26 of the flexible blades 12 and also a displacement of the rollers 1 1 on the other complementary cam surfaces 26 '. This type of damper is described in particular in the patent application FR3032248. The FIG. 3 shows a variant thereof with the flexible blades 12 mounted on the secondary flywheel 9 (not shown) and cam followers in the form of rollers able to roll both on the cam surfaces 26 of the blades 12 and on complementary cam surfaces 26 'formed the primary flywheel.

In this embodiment, the contact plane comprises both the bearing lines 25 of the rollers 1 1 in contact with the cam surfaces 26 carried by the flexible blades 12 but also the bearing lines of the rollers 25 'opposite to the bearing lines 25 and formed by a radially outer end of the rollers 1 January. These bearing lines of the rollers 1 1 opposite to the bearing lines 25 cooperate with the cam surface carried by the flywheel not carrying the flexible blades 12.

In a similar manner to the embodiment described above in the context of flexible blades 12 fixed to the primary flywheel 7 and roller 1 1 fixed on the secondary flywheel 12, the contact plane of the rollers 1 1 on the cam surfaces 26 is rotatable relative to the primary flywheel 7. Nevertheless, the angular displacement of the cam followers with respect to the first element is here halved and the critical angular sector Cr to be avoided can then be extended.

Therefore, the primary and secondary flywheels 7, 9, the blades and the rollers January 1 are advantageously arranged so that the contact plane remains away from the critical angular sector, for any angular position of the first and second elements in the range of travel, especially when transmitting maximum torque. This positioning is all the more important in this embodiment that it is necessary to maintain good cooperation between the rollers January 1 and each cam surface, a tilting of the primary flywheel 7 can disturb both the cooperation between the rollers 11 and the cam surfaces carried by the primary flywheel 7 and the cooperation between the rollers 11 and the cam surfaces carried by the secondary flywheel 9. Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations if they fall within the scope of the invention . This invention is applicable to any variable stiffness damper having in a plane perpendicular to the X axis cam followers moving on cam surfaces.

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 the 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.

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

Claims

1. Torsion damper for a motor vehicle, in particular for a motor vehicle transmission chain, comprising:

a first element (7) having a perpendicular axis of rotation (X) and a geometric axis of tilting (13), the first element (7) comprising fixing means able to mount the first element in a predetermined angular position of mounting on a nose (8) of a crankshaft (1), the geometric tilt axis (13) corresponding to an axis about which the first element (7) tilts when said first element (7) is mounted on the nose (8) the crankshaft (1) in the predetermined angular position and that said nose (8) of the crankshaft (1) is rotated

a second element (9) rotatably mounted relative to the first element (7) about the axis of rotation (X), the first and second elements being rotatable relative to each other on a beach angular deflection extending between a first extreme position and a second extreme position,

an elastic damping member arranged to transmit torque and dampen the acyclisms between the first member (7) and the second member (9), the resilient damping member having at least one cam surface (26), at least a cam follower (1 1) and at least one elastic connection, each cam surface being associated with a respective cam follower and a resilient link, each elastic connection being able to deform to provide an elastic support between the surface of the cam; cam and the cam follower thereof and to enable said cam follower to move in contact with said cam surface (1 1), the displacement of said cam follower (1 1) on said cam surface being accompanied by a rotation relative between the first and second elements,

wherein the damper is arranged such that for any relative angular position of the first and second members within the range of angular travel of the damper, no cam follower rest on its cam surface is projection in a plane perpendicular to the axis of rotation (X), in a critical angular sector, said critical angular sector (Cr) being greater than or equal to 40 degrees and extending symmetrically on either side of the perpendicular (P) to the geometric axis of tilting ( 13).

A torsion damper according to claim 1 wherein the damper comprises, in a plane perpendicular to the axis of rotation (X), at least one pair of cam followers (1 1) and at least one pair of cam surfaces. cam (26), at least two resilient links, each resilient connection being deformable to provide elastic support between a respective cam surface (26) and cam follower (1 1) and to enable said cam follower ( 1 1) to move in contact with said cam surface, the displacement of the cam followers on their respective cam surfaces being accompanied by a relative rotation between the first and second members, each cam follower (1 1) having a supporting (25) on the cam surface (26) with which it cooperates so that each pair of cam followers defines a geometric bearing axis substantially perpendicular to the axis of rotation (X) and passing through the axis of rotation X, the damper being arranged so that, for any relative angular position of the first and second elements located in the range of angular displacement of the damper, no geometric support axis is, in projection in a plane perpendicular to the axis of rotation (X ), located in the critical angular sector (Cr).

3. torsion damper according to one of the preceding claims wherein said critical angular sector (Cr) is greater than 60 degrees, especially greater than 80 degrees and extends symmetrically on either side of the perpendicular to the axis geometric tilt.

4. torsion damper according to one of the preceding claims wherein said critical angular sector is greater than 82 degrees, especially greater than 92 degrees, especially greater than 98 degrees, especially greater than 106 degrees and extends symmetrically on both sides from the perpendicular to the geometric axis of tilting.

Torsion damper according to one of the preceding claims, in which the crankshaft (1) on which the first element is intended to be mounted is coupled to pistons (2, 27) rotating said crankshaft (1) about said crankshaft (1). axis of rotation (X), and in which the piston near the nose of the crankshaft is slidably mounted along a sliding axis (28), the tilting geometric axis (13) being offset by an angle of between 5 and 10 ° in a driving rotational direction of the first element by perpendicularly to said sliding axis (28) of the piston (27) closest to the nose (8) of the crankshaft (1) in a top dead position of said piston (27).

The torsion damper according to one of the preceding claims, wherein each cam follower rest on its cam surface is located in a target angular sector (Ci), the target angular sector being less than 40 degrees, especially less than 30 degrees, especially less than 20 degrees and extending symmetrically on either side of the geometric axis of tilting.

A torsion damper according to one of claims 1 to 6, wherein each cam surface (26) is carried by a respective flexible blade (12), each flexible blade (12) having a mounting portion (21) attached on said one of the first member (7) and the second member (8) and a flexible portion (22) carrying said cam surface (26).

Torsion damper according to the preceding claim, wherein each cam surface is formed on a radially outer face of the flexible portion, each cam follower (1 1) being arranged radially outwardly of the cam surface (26). ) with which he cooperates.

The torsion damper according to one of the preceding claims, wherein each cam surface is resiliently connected to one of the first member (7) and the second member (9) and each cam follower (1 1) is a roller rotatably mounted on said other of the first member (7) and the second member (9).

10. Torsion damper according to the preceding claim, wherein each roller is rotatably mounted on a rod, said rod being parallel to the axis of rotation, said rod being fixed on the other of the first element and the second element. .

1 1. A torsion damper according to one of claims 1 to 10 in combination with claim 2, wherein each cam surface is resiliently connected to one of the first member (7) and the second member (9) and said other the first element (7) and the second element (9) comprises two complementary cam surfaces, each cam follower (1 1) being arranged radially between a cam surface and a complementary cam surface so that, at a relative deflection between the first member (7) and the second member (9); ), the cam follower moves both on the cam surfaces (26) elastically connected to one of the first member (7) and the second member (9) and to the complementary cam surfaces of the other one of the first member (7) and the second element (9).

12. torsion damper according to one of claims 1 to 1 1, wherein the first element comprises a polarizer for cooperating with a polarizing complementary key of the crankshaft to define the predetermined angular position of the first element on the nose of the crankshaft. .

The torsion damper according to one of the preceding claims, wherein the cam surfaces (26) are resiliently connected to the second member (9) and the cam followers (1 1) are carried by the first member (7).

14. A motor vehicle chain comprising a crankshaft (1) and pistons (2, 27) coupled to the crankshaft (1) for rotating the crankshaft (1) about an axis of rotation (X), the transmission chain further comprising a torsion damper according to one of claims 1 to 13, the first member (7) of said torsion damper being mounted in a predetermined angular position on a nose (8) of the crankshaft (1).