EP3472494A1

EP3472494A1 - Torque transmission device

Info

Publication number: EP3472494A1
Application number: EP17728871.9A
Authority: EP
Inventors: GyuBong Jeon
Original assignee: Valeo Embrayages SAS
Current assignee: Valeo Embrayages SAS
Priority date: 2016-06-20
Filing date: 2017-06-12
Publication date: 2019-04-24
Also published as: US20170363193A1; WO2017220358A1; US10054209B2; JP2019518920A; CN109312841A

Abstract

The invention relates to a torque transmission device comprising an input torque element (17a, 17b) and an output torque element (8) that are able to pivot relative to one another about an axis (X), and at least one resilient blade (22), connected to the output torque element (8) or the input torque element (17a, 17b) so as to rotate therewith, the resilient blade (22) being able to be maintained resiliently and radially supported on a support member (18) carried by the input torque element (17a, 17b) or the output torque element (8), the resilient blade (22) being able to bend during rotation of the input torque element (17a, 17b) relative to the output torque element (8).

Description

Torque transmission device

The present invention relates to a torque transmission device and a hydrokinetic clutch for a motor vehicle, such as for example a torque converter or a double damping flywheel.

A known hydrodynamic torque converter is illustrated schematically and partially in FIG. 1 and makes it possible to transmit a torque of an output shaft of an internal combustion engine of a motor vehicle, such as for example a crankshaft 1 , to an input shaft 2 of a gearbox.

The torque converter conventionally comprises an impeller wheel 3 capable of hydrokinetically driving a turbine wheel 4 via a reactor 5.

The impeller wheel 3 is coupled to the crankshaft 1 and the turbine wheel 4 is coupled to guide washers 6.

A first group of elastic members 7a, 7b of the compression spring type is mounted between the guide washers 6 and a central hub 8 is coupled to the input shaft 2 of the gearbox. The elastic members 7a, 7b of the first group are arranged in series via a phasing member 9, so that said elastic members 7a, 7b deform in phase with each other, the phasing member 9 being movable relative to the guide washers 6 and relative to the hub 8.

A second group of elastic members 7c is mounted with clearance between the guide washers 6 and the central hub 8, in parallel with the first group of elastic members 7a, 7b, said elastic members 7c being designed to be active over an angular range. limited, in particular at the end of angular travel of the guide washers 6 with respect to the central hub 8. The angular stroke, or the angular offset noted a, of the guide washers 6 with respect to the hub 8, is defined with respect to a rest position (a = 0) in which no torque is transmitted through the damping means formed by the elastic members 7a, 7b above.

The torque converter also comprises clutch means 10 making it possible to transmit a torque from the crankshaft 1 to the guide washers 6 in a determined operating phase, without involving the impeller wheel 3 and the turbine wheel 4.

The second group of elastic members 7c makes it possible to increase the stiffness of the damping means at the end of the angular stroke, that is to say for a significant angular offset of the guide washers 6 with respect to the hub 8 (or Conversely).

It can be seen that the representation of the function M = f (a) defining the torque M transmitted through the device as a function of the angular offset a, comprises a first linear portion of slope Ka (for small values of the angular offset a) and a second linear portion of slope kb larger (for the high values of the angular offset a). Ka and Kb are the angular stiffness of the device, respectively at the beginning and end of the angular stroke. If we define by K1 the cumulative stiffnesses of the first springs of each pair of the first group, by K2 the cumulative stiffness of the second springs of each pair of the first group and by K3 the cumulative stiffness of the springs of the second group, then Ka = ( K1 .K2) / (K1 + K2) and Kb = Ka + K3.

The rupture of slope between the first and second portions of the curve can generate vibrations and a high hysteresis during operation of the torque converter affecting the quality of the filtration obtained using the damping means.

In order to remedy this drawback, patent FR 3,008,152, in the name of the Applicant, proposes a torque transmission device comprising a torque input element and a torque output element able to pivot about an axis. relative to one another, two resilient blades rotatably connected to the torque output member or respectively to the torque input element, said resilient blades being held elastically and radially bearing on bearing members carried by the torque input member or respectively by the torque output member, said blades resilient being able to flex upon rotation of the torque input member relative to the torque output member.

Such a transmission device provides damping means, formed by the elastic blades, having a progressive characteristic curve, without breaking the slope. Such a device thus makes it possible to reduce the vibrations generated during operation and ensures a good quality of filtration.

The manufacture of such blades is however complex to implement. Indeed, these blades are relatively massive and it is difficult to manufacture them, for example by cutting, and to obtain a good state of the surfaces of the blades in contact with the support members.

The invention aims in particular to provide a simple, effective and economical solution to this problem.

For this purpose, it proposes a torque transmission device comprising a torque input element and a torque output element able to pivot about an axis relative to one another, at least one elastic blade. rotatably connected to the torque output member or the torque input member, said resilient blade being resiliently and radially supported on a support member carried by the torque input member or respectively by the torque output member, said resilient blade being adapted to flex upon rotation of the torque input member with respect to the torque output member, characterized in that the elastic blade comprises at least two stacked elastic lamellae, said lamellae comprising a connection zone to the torque output element, respectively to the torque input element, and a bearing zone of the support member, said lamellae being connected to one another via at least one link secured to a first blade and engaged with a radial clearance in at least a second lamella.

The production of the elastic blade from a stack of several slats facilitates the manufacture of said blade. The slats can in fact be easily made by thin cutting sheets while obtaining a good surface condition at the surfaces in contact with the support member.

The radial clearance compensates for any misalignment of the surfaces in contact with the support member between the different lamellae, such a misalignment being due to manufacturing dimensional tolerances.

This ensures that the support member is able to bear simultaneously on all the lamellae of the same elastic blade.

It will be noted that the terms "radial" and "axial" are defined with respect to the axis of the transmission device, which is in particular the axis of rotation of the torque input element relative to the output element. of couple.

The slats can be connected to each other in said bearing zone, via the connecting member.

The connection zone and the support zone may be offset radially relative to one another and connected by a curved zone.

The connecting member may be designed to maintain the axial position of the slats relative to each other.

The connecting member is for example a rivet.

The slats can be connected to each other in said bearing zone by means of at least two connecting members, each connecting member being integral with a slat and engaged with a radial clearance in at least one other slat .

The support member may comprise a rolling body pivotally mounted about an axis, said axis being fixed to the torque input member, respectively to the torque output member. In this case, the rolling body of the support member may be formed by a roller pivotally mounted about an axis, by means of a rolling bearing, such as for example a needle bearing.

The resilient blade may be designed so that, in a relative angular position between the torque input member and the torque output member different from a rest position, the support member exerts a bending force on the resilient blade producing a counteracting force of the resilient blade on the bearing member, said reaction force having a circumferential component tending to bias the torque input member and the output member torque to said relative rest position.

The resilient blade may be designed so that, in a relative angular position between the torque input member and the torque output member different from a rest position, the support member exerts a bending force on the elastic blade producing an opposite reaction force of the elastic blade on the support member, this reaction force having a radial component tending to maintain the elastic blade in contact with the support member.

The angular displacement of the torque input element relative to the torque output element may be greater than 20 ° preferably greater than 40 °.

The damping means may comprise at least two resilient blades, each resilient blade being integral in rotation with the torque output member, or respectively with the torque input member, each blade being associated with a member of support rotatably connected to the torque input element, or respectively to the torque output element, each blade being resiliently held in abutment on said corresponding support member, each resilient blade being able to flex during the rotating the torque input member relative to the torque output member. The zones of connection of the lamellae may be annular and comprise radially internal grooves, able to cooperate with splines of the torque output element, respectively of the torque input element.

The invention also relates to a hydrokinetic clutch for a motor vehicle, comprising

an impeller wheel intended to be coupled in rotation to a crankshaft,

- A turbine wheel adapted to be driven hydrokinetically in rotation by the impeller wheel, and adapted to be coupled in rotation to an input shaft of a gearbox,

clutch means,

a torque transmission device of the aforementioned type, the torque input element being connected or formed by the clutching means, the torque output element being connected or formed by a hub intended to be coupled in rotation; to the input shaft of the gearbox,

the clutch means being movable between an engaged position in which the impeller wheel and the torque input member of the torque transmission device are coupled in rotation and a disengaged position in which the impeller wheel and said torque input member is decoupled in rotation.

Such a hydrokinetic clutch is also relatively easy to assemble and inexpensive.

The hub can be rotatably coupled to the turbine wheel.

The clutch means may comprise a piston.

The support member may be cylindrical and extend parallel to the axis of the torque transmission device.

It will be noted that a hydrokinetic clutch can be a torque converter when the hydrokinetic coupling means comprise an impeller wheel, a turbine wheel and a reactor, or can be a coupler when the hydrokinetic coupling means are devoid of reactor.

The impeller wheel may be rotatably coupled to the torque input member and adapted to hydrokinetically drive the turbine wheel through a reactor.

The hydrokinetic clutch may also include one or more of the following features:

the support member is mounted at the radially outer periphery of at least one flange belonging to the torque input element,

said flange is coupled in rotation to the piston, for example at the radially outer periphery of the flange,

the flange is pivotally mounted around the torque output element,

the support member is mounted axially between two radially extending flanges axially offset from one another,

the impeller wheel is rotatably coupled to a cover in which at least a portion of the impeller wheel, the turbine wheel and / or the torque transmission device are housed,

the torque output element comprises a hub intended to be coupled in rotation to an input shaft of a gearbox.

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the accompanying drawings in which:

FIG. 1 is a schematic representation of a torque converter of the prior art,

FIG. 2 is a half-section, according to an axially extending plane, of a torque converter according to the invention;

FIG. 3 is a perspective view of a portion of an elastic blade and a support member, according to one embodiment of the invention; FIG. 4 is an exploded perspective view of the elements illustrated in FIG. 3;

- Figure 5 is a detail view in section along an axial plane, illustrating the connection between the different lamellae of the same elastic blade and the corresponding support member, when the support member constrains the together said slats,

FIG. 6 is a view similar to FIG. 5, illustrating a case of rest or non-stress of all the slats by the support member,

- Figure 7 is a front view of the slats and the support member, in the rest position.

A hydrokinetic clutch according to a first embodiment of the invention is shown in Figures 2 to 7. The hydrokinetic clutch is in particular a hydrodynamic torque converter. The latter makes it possible to transmit a torque of an output shaft of an internal combustion engine of a motor vehicle, such as for example a crankshaft 1, to an input shaft 2 of a gearbox. The axis of the torque converter has the reference X.

In what follows, the terms "axial" and "radial" are defined with respect to the axis X.

The torque converter comprises an impeller impeller 3 capable of driving a hydrokinetic turbine wheel 4 by means of a reactor 5.

The impeller wheel 3 is fixed to a lid formed of several parts 1 1a, 1 1b, 1 1c assembled by welding to each other and delimiting an internal volume 12 housing the impeller wheel 3, the wheel of turbine 4 and the reactor 5. Said lid 1 1a, 1 1b, 1 1c, also noted more generally lid 1 1, comprises fastening means 13 for rotatably coupling said lid 1 1 to the crankshaft 1. The torque converter further comprises a central hub 8 whose radially inner periphery is grooved, of axis X and housed in the internal volume 12 of the lid January 1. The central hub 8 comprises an annular flange 14 extending radially outwards and an annular groove 15 opening axially opposite the impeller wheel 3 and the turbine wheel 4.

The turbine wheel 4 is fixed to the first annular flange 14 of the central hub 8, for example by means of rivets 16 or by welding.

The torque converter further comprises two flanges

17a, 17b radial, axially offset from each other. The flanges 17a, 17b are pivotally mounted around the hub 8.

Two support members or rolling bodies 18, in the form of rollers or cylindrical rollers, are fixed at the radially outer periphery of the flanges 17a, 17b, axially between the flanges 17a, 17b. The rolling bodies 18 are located with respect to one another diametrically opposite. In particular, the rolling bodies 18 are mounted around axes 19 extending axially between the flanges 17a, 17b and coupling said flanges 17a, 17b in rotation. The pins 19 are mounted on the flanges 17a, 17b by means of rivets 20, screws or bolts for example. The rolling bodies 18 are mounted on the axes 19 by rolling bearings, such as for example needle bearings 21.

The torque converter further comprises two opposed resilient blades 22 formed by three lamellae 23a, 23b, 23c stacked one on top of the other. As best seen in FIGS. 3 to 7, each lamella 23a, 23b, 23c is symmetrical with respect to the X axis, only one half of the lamellae being shown in FIGS. 3 and 4.

Each strip 23a, 23b, 23c comprises a radially inner annular connection zone 24, with grooves or radially inner teeth cooperating with radially corrugated grooves. 26 of the hub 8 so as to rotate said hub 8 and said slats 23a, 23b, 23c. Each lamella further comprises two radially outer and diametrically opposite strands 27 (only one strand 27 is shown in the figures), forming the blades 22, each connected to the connecting zone 24 by a curved or arcuate zone 28. Each outer strand 27 and each curved zone 28 are elastically deformable. Curved area 28 has an angle of about 180 °.

Each outer strand 27 develops circumferentially at an angle of between 120 ° and 180 °. The radially outer strand 27 has a radially outer surface 29 forming a rolling track abutting the corresponding rolling body 18, said rolling body 18 being located radially outside the outer strands 27 of the elastic lamellae 23a, 23b, 23c . Each raceway 29 has a generally convex shape. The running track 29 may be formed directly by a zone of the outer strand 27 or by a piece which is attached to said outer strand 27.

The strips 23a, 23b, 23c are connected to each other by rivets 34, 35, 36 mounted at the outer strands 27 of said strips, in particular by three rivets 34, 35, 36 circumferentially offset from each other. A first rivet 34 is located facing the rolling body 18 in a rest position of the torque converter, that is to say in a position where no torque is transmitted through said torque converter, the second and third rivets 35, 36 being situated on either side of the first rivet 34, respectively close to the free end of the outer strand 27 and close to the curved zone 28.

As can be seen more clearly in FIGS. 5 and 6, each rivet 34, 35, 36 has a part, denoted 34a for the rivet 34, fastened to one of the slats, here the slat 23a, the remainder 34b of the rivet 34 being engaged. with a radial clearance, for example between 0.01 and 10 mm, in the other strips 23b, 23c. The ends of the rivets comprise 34c heads resting on the outer lateral surfaces of the slats 23a and 23c, so as to axially hold the slats 23a, 23b, 23c together.

The manufacturing dimensional tolerances between the lamellae 23a, 23b, 23c can generate a radial offset between the rolling tracks 29 of the different lamellae 23a, 23b, 23c, as can be seen in the rest position illustrated in FIG. slats 23b and 23c are not supported on the rolling body 1 8 corresponding.

In operation, when the rolling body 1 8 moves along the running tracks 29, it then forces the three strips 23a, 23b, 23c simultaneously, as illustrated in FIG. 5, the radial clearances j between the rivets 34, 35, 36 and the lamellae 23a, 23b, 23c making it possible to absorb or compensate for the dimensional differences between the lamellae 23a, 23b, 23c and thus allow simultaneous contact of the rolling body 1 8 on the three lamellae 23a, 23b, 23c.

Between each elastic strip 23a, 23b, 23c and the corresponding rolling body 1 8, the transmitted torque is decomposed into radial forces and circumferential forces. The radial forces allow to bend the corresponding plate 23a, 23b, 23c and the circumferential forces allow the corresponding rolling body 1 8 to move on the runway 29 of the blade 23a, 23b, 23c and transmit the torque.

The torque converter further comprises clutch means 1 0 capable of rotating the lid 1 1 and the flanges 1 7a, 1 7b in a clutched position, and able to release the lid 1 1 and the flanges 17a, 17b, in a disengaged position.

The clutch means 1 0 comprise an annular piston 30 extending radially, housed in the internal space 12 of the cover 10, whose radially outer periphery comprises a bearing zone equipped with friction linings 31 and adapted to come into pressing on the part 1 1 c of the cover 1 1 in the engaged position so as to make a coupling in rotation of the lid 1 1 and the piston 30. The radially outer periphery of the piston 30 further comprises at least one coupling lug 32 extending axially, engaged in a notch or recess of complementary shape of the flanges 17a, 17b, so as to effect a rotation coupling of the piston 30 and flanges 17a, 17b while allowing axial displacement of the piston 30 relative to the flanges 17a, 17b.

The radially inner periphery of the piston 30 comprises a cylindrical rim 33 housed in the annular groove 15 of the hub and guided in rotation around the radially inner cylindrical surface of said groove 15.

The axial displacement of the piston 30 is controlled by pressure chambers located on either side of the piston 30.

Such clutch means 10 make it possible to transmit a torque of the crankshaft 1 to the input shaft 2 of the gearbox, in a determined operating phase, without involving the hydrokinetic coupling means formed by the gear wheel. impeller 3, the turbine wheel 4 is the reactor 5.

In operation, the torque coming from the crankshaft 1 is transmitted to the cover 1 1 by means of the fastening means 13. In the disengaged position of the piston 30, the torque passes through the hydrokinetic coupling means, namely the impeller wheel 3 and then the turbine wheel 4 fixed to the hub 8. The torque is thus transmitted to the input shaft of the gearbox 2 coupled to the hub via the internal grooves of the hub 8.

In the engaged position of the piston 30, the torque from the cover 1 1 is transmitted to the flanges 17a, 17b by means of the damping means formed by the resilient blades 22 and by the support members 18. The torque is then transmitted at the inner hub 8 coupled to the slats 23a, 23b, 23c and then to the input shaft of the gearbox 2 coupled to the hub 8 via the internal splines of said hub 8. In the engaged position of the piston 30, when the torque transmitted between the cover 1 1 and the hub 8 varies, the radial forces exerted between each elastic blade 22 and the corresponding rolling body 18 vary and the flexion of the elastic blade 22 is modified . The modification of the flexion of the blade 22 is accompanied by a displacement of the rolling body 18 along the corresponding rolling tracks 29 under the action of the circumferential forces.

The rolling tracks 29 have profiles arranged in such a way that, when the transmitted torque increases, the rolling bodies 18 each exert a bending force on the corresponding resilient lamellae 23a, 23b, 23c, bringing them closer to the free distal end of the tubes. elastic strips 23a, 23b, 23c in the direction of the X axis and a relative rotation between the lid 1 1 and the hub 8 such that the latter deviate from their relative position of rest. The relative position of the cover 1 1 with respect to the hub 8 in which no torque is transmitted between the latter is defined by the rest position.

The profiles of the rolling tracks 29 are such that the rolling bodies 18 exert on the elastic blades 22 bending forces having radial components and circumferential components.

The elastic blades 22 exert on the rolling bodies 18 a restoring force having a circumferential component which tends to rotate the rolling bodies 18 in an opposite direction of rotation and thus to recall the turbine wheel 4 and the hub 8 to their relative position resting, and an outwardly directed radial component tending to maintain the rolling tracks 29 resting on the corresponding rolling body 18.

Preferably, when the cover 1 1 and the hub 8 are in their rest position, the elastic blade 22 is prestressed radially towards the axis X so as to exert a reaction force directed radially outwardly, so as to maintain at least one plate 23a, 23b, 23c resting on the corresponding rolling body 18, here the plate 23a.

The profiles of the raceways 29 can be arranged in such a way that the characteristic curve of transmission of the torque as a function of the angular displacement is symmetrical or not with respect to the rest position. According to an advantageous embodiment, the angular displacement can be greater in a direction of rotation said direct, than in a direction of rotation opposite, said retro direction.

The angular displacement of the cover 1 1 relative to the hub 8 may be greater than 20 ° preferably greater than 40 °.

The elastic blades 22 are regularly distributed around the X axis and are symmetrical with respect to the X axis so as to ensure the balance of the torque converter.

The torque converter may also comprise friction means arranged to exert a resistant torque between the cover 1 1 and the hub 8 during their relative deflection so as to dissipate the energy accumulated in the elastic strips 22.

Of course, the number of lamellae of each elastic blade 22 may vary. Each blade 22 can thus be formed of two slats for example.

Claims

1. A torque transmitting device having a torque input member (17a, 17b) and a torque output member (8) pivotable about an axis (X) relative to each other, to the at least one resilient blade (22) rotatably connected to the torque output member (8) or the torque input member (17a, 17b), said elastic blade (22) being elastically and radially bearing on a support member (18) carried by the torque entry element (17a, 17b) or respectively by the torque output member (8), said elastic blade (22) being able to flex when rotating the torque input member (17a, 17b) relative to the torque output member (8),

characterized in that the elastic blade (22) comprises at least two stacked resilient lamellae (23a, 23b, 23c), said lamellae comprising a zone (24) for connection to the torque output element (8), respectively torque input member (17a, 17b), and a bearing region (27) of the support member (18), said slats (23a, 23b, 23c) being connected to one another by intermediate of at least one connecting member (34, 35, 36) integral with a first blade (23a) and engaged with a radial clearance (j) in at least a second blade (23b, 23c).

2. Device according to claim 1, characterized in that the strips (23a, 23b, 23c) are connected to each other in said bearing zone (27), via the connecting member (34). , 35, 36).

3. Device according to claim 1 or 2, characterized in that the connecting zone (25) and the bearing zone (27) are offset radially relative to one another and connected by a curved zone (28). ).

4. Device according to one of claims 1 to 3, characterized in that the connecting member (34, 35, 36) is designed to maintain the axial position of the slats (23a, 23b, 23c) relative to the other.

5. Device according to one of claims 1 to 4, characterized in that the connecting member is a rivet (34, 35, 36).

6. Device according to one of claims 1 to 5, characterized in that the slats (23a, 23b, 23c) are connected to each other in said bearing zone (27) via at least two connecting members (34, 35, 36), each connecting member (34, 35, 36) being integral with a lamella (23a) and engaged with a radial clearance (j) in at least one other lamella (23b, 23c ).

7. Device according to one of claims 1 to 6, characterized in that the support member comprises a body (1 8) mounted pivotally mounted about an axis (1 9), said axis (1 9) being attached to the torque input member, respectively to the torque output member.

8. Device according to claim 7, characterized in that the rolling body of the support member is formed by a roller (18) pivotally mounted about an axis (1 9), via a bearing rolling bearing (21), such as for example a needle bearing.

9. Device according to one of claims 1 to 8, characterized in that the elastic blade (22) is designed so that, in a relative angular position between the torque input member (1 7a, 1 7b) and the torque output member (8) different from a rest position, the support member (1 8) exerts a bending force on the elastic blade (22) producing a counteracting reaction force of the resilient blade (22) on the support member (1 8), said reaction force having a circumferential component tending to bias the torque input member (17a, 17b) and the output member torque (8) to said relative rest position.

Device according to one of Claims 1 to 9, characterized in that the elastic blade (22) is designed such that, in a relative angular position between the torque input element (17a, 1 7b) and the torque output member (8) different from a rest position, the support member (1 8) exerts a bending force on the resilient blade (22) producing a counteracting force of the elastic blade (88) on the support member (1 8), this reaction force having a radial component tending to maintain the elastic blade (22) in contact with the support member (1 8).

1 1. Device according to one of claims 1 to 1 0, characterized in that the angular displacement of the torque input element (17a, 17b) relative to the torque output element (8) is greater than 20 ° preferably greater than 40 °.

1 2. Device according to one of claims 1 to 1 1, characterized in that the damping means comprise at least two resilient blades (22), each resilient blade (22) being integral in rotation with the output member of torque (3), or respectively of the torque input element (1 7a, 1 7b), each blade (22) being associated with a support member (1 8) rotatably connected to the element torque input (1 7a, 1 7b), or respectively to the torque output member (8), each blade (22) being elastically supported on said corresponding support member (1 8), each blade elastic member (22) being adapted to flex upon rotation of the torque input member (17a, 17b) relative to the torque output member (8).

1 3. Hydrokinetic clutch for a motor vehicle, comprising

an impeller wheel (3) intended to be coupled in rotation to a crankshaft (1),

- A turbine wheel (4) adapted to be driven hydrokinetically in rotation by the impeller wheel (3), and adapted to be coupled in rotation to an input shaft (2) of a gearbox,

clutch means (10),

- A torque transmission device according to one of claims 1 to 1 2, the torque input member (17a, 17b) being connected or formed by the clutch means (1 0), the a torque output member being connected or formed by a hub (8) to be rotatably coupled to the input shaft (2) of the gearbox, the clutch means (10) being movable between an engaged position in which the impeller (3) and the torque input member (17a, 17b) of the torque transmission device are coupled in rotation and a position disengaged wherein the impeller wheel (3) and said torque input member (17a, 17b) are decoupled in rotation.

Hydrokinetic clutch according to claim 13, characterized in that the hub (8) is rotatably coupled to the turbine wheel (4).

15. Hydrokinetic clutch according to claim 13 or 14, characterized in that the clutch means (10) comprise a piston (30).