FR2834022A1 - Double damper flywheel transmission comprises coaxial flywheels connected by torsion damper and rotating with motor shaft and receptor shaft respectively and bending vibration filtering element between first flywheel and motor shaft - Google Patents

Abstract

The transmission device comprises first and second (4,5) coaxial inertia flywheels rotating respectively with a motor shaft (2) and a receptor shaft (3). The flywheels are connected by means of a torsion damper (41,44). There is also a connection element (6) between the first flywheel and the motor shaft having a torsional rigidity and bending suppleness so that it allows bending vibration filtering. An Independent claim is included for a method of driving a receptor shaft from a motor shaft.

Description

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 Transmission device of the double damping flywheel type and method.

 The present invention relates to a transmission device of the double damping flywheel type, intended to be disposed between a motor shaft and a receiving shaft.

 Torsion damping devices are provided to dampen variations in torque at the output of internal combustion engines, in particular more sensitive for low rotational speeds, or during accelerations. Torque variations cause vibrations which are a source of noise. Torque variations are due in part to the offset combustion cycles in the cylinders of internal combustion engines. Successive explosions cause irregularities in the rotational drive torque of a crankshaft of the internal combustion engine. Such a damping device is arranged between the crankshaft and a receiving shaft, for example an input shaft of a gearbox.

 To attenuate variations in torque, a flywheel can be placed on the crankshaft. The greater the inertia of rotation of the flywheel, the more the variations in low frequency torque will be attenuated. The torque at the output of the crankshaft is smoothed. The inertia of rotation of the flywheel is adapted to filter vibrations, in particular in the field of audible frequencies. However, a flywheel represents an additional load applied to the crankshaft of the internal combustion engine, penalizing for the consumption or acceleration performance of the internal combustion engine.

 Known torsional damping devices with double flywheel are known. Two coaxial flywheels are linked in rotation with the possibility of angular displacement against elastic means with circumferential action. Friction damping means also act during an angular displacement of a flywheel relative to the other to dampen oscillations of angular displacement.

flexion. Or un couplage entre des fréquences propres de flexion du dispositif de C > Furthermore, in internal combustion engines, a reciprocating translational movement of pistons is transformed into rotational movement by a connecting rod and crankshaft assembly. The crankshaft undergoes bending stresses causing bending vibrations of a transmission device disposed at the outlet of the internal combustion engine. Damping devices with a flywheel or a double flywheel do not allow satisfactory attenuation of vibrations of

bending. Now a coupling between natural frequencies of bending of the device of C>

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 transmission fixed on the crankshaft and bending frequencies of the crankshaft and the internal combustion engine causes a resonance increasing the transmission of noise source vibrations in a vehicle.

d'irrégularités de couple et de vibrations de flexion. The present invention relates to a transmission device intended to be arranged at the outlet of an internal combustion engine, and allowing attenuation

torque irregularities and bending vibrations.

ZD
Such a transmission device, of the double damping flywheel type, comprises first and second coaxial flywheels linked in rotation respectively to a motor shaft and a receiving shaft, the first and second flywheels being linked in rotation by means of a torsion damping means, the transmission device comprising a connecting element of the motor shaft and the first flywheel, the connecting element having a torsional rigidity and a flexibility in bending such that the connecting element allows a filtering bending vibrations.

permet un premier lissage d'irrégularité de couple en sortie de l'arbre moteur. La c liaison en rotation des premier et second volants à l'aide de moyens d'amortissement de torsion permet un amortissement d'irrégularités de torsion. Le filtrage de vibrations de flexion de l'arbre moteur permet un découplage entre l'arbre moteur et l'ensemble volants et moyens d'amortissement de torsion, afin de limiter une transmission de vibrations de l'arbre moteur vers l'ensemble d'un véhicule automobile. The increase in the inertia of rotation of the motor and receiver shafts

allows a first smoothing of torque irregularity at the output of the motor shaft. The rotational connection of the first and second flywheels using torsion damping means allows damping of torsional irregularities. Filtering the bending vibrations of the motor shaft allows decoupling between the motor shaft and the flywheel and torsion damping assembly, in order to limit the transmission of vibrations from the motor shaft to the assembly. a motor vehicle.

 In one embodiment, the connecting element comprises bending damping means allowing damping of bending vibrations transmitted by the motor shaft. The damping means can operate in particular by dissipating energy in the form of heat.

 In one embodiment, the bending connection comprises a flexible disc, the area of smaller diameter is secured to the motor shaft, the area of larger diameter being secured to a peripheral portion of the first flywheel. A disc has a high torsional rigidity along its axis of revolution, which makes it possible to use it to link in rotation the motor shaft and the first flywheel. On the other hand, the flexibility of a disc can be adapted to obtain the desired vibrational characteristics when it is subjected to a bending force along an axis perpendicular to its axis of symmetry of revolution.

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Advantageously, the flexible disc is formed by a superposition of thin plates fixed together. During a bending of the disc, adjacent plates, supporting different deformations, slide in friction contact against each other. Such friction allows damping of bending vibrations transmitted by the disc, by dissipation of energy in the form of heat.
Preferably, the flexibility of bending of the connecting element is adapted so that the transmission device fixed on the motor shaft has a natural frequency in bending between 80 and 120 Hz. A transmission device having a natural frequency in bending included in such a frequency range allows decoupling between the internal combustion engine and the transmission device. The bending vibrations at the output of the crankshaft, when the internal combustion engine is operating in a usual speed range, will not excite the first harmonics of the bending modes of the transmission device, avoiding significant transmission of vibrations and noise to a chassis of the vehicle.

 In one embodiment, the first flywheel can move angularly with respect to the second flywheel against elastic elements with circumferential action, of the spring type, to filter irregularities in torque transmitted by the drive shaft. Advantageously, friction means are arranged between the first flywheel and the second flywheel, to improve damping of irregularity in torque.

 In one embodiment, the transmission device comprises a centering element for the first and second flywheels. The centering element can for example be fixed on a steering wheel, the other steering wheel being rotatably mounted on an axis of the centering element. The bending vibrations from the motor shaft are filtered by the connecting element of the motor shaft and the first flywheel, and are attenuated downstream of the first flywheel. Depending on the connecting element used, the latter will allow filtering of bending vibrations in a preferred frequency range. The attenuation of bending vibrations allows the centering link of the flywheels while ensuring satisfactory filtering of the bending vibrations. The centering of the steering wheels allows better functioning of the torsional damping means arranged between the steering wheels. The filtering of bending vibrations upstream of the transmission device makes it possible to prevent bending stresses from causing

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 relative bending movements between the first and second steering wheels, which could be the source of noise.

 In one embodiment, the second flywheel is linked in rotation to the receiving shaft by means of a disengageable coupling. Such a transmission device is suitable in the case where the latter is disposed between a crankshaft of an engine, forming the engine shaft, and an input shaft of a gearbox of the manually controlled type, forming the receiving shaft.

 The invention also relates to a method of driving a receiving shaft from a driving shaft in which the rotation inertia of the driving shaft is increased by means of a first flywheel, increases the inertia of rotation of the receiving shaft using a second flywheel, the first flywheel and the second flywheel are linked in rotation by damping torque variations, and bending vibrations are filtered the drive shaft between the drive shaft and the first flywheel.

 The present invention and its advantages will be better understood on studying the detailed description of embodiments taken by way of nonlimiting example and illustrated by the appended drawings, in which: - Figure 1 is an axial sectional view d 'a transmission device according to one aspect of the invention; and - Figure 2 is a partial sectional view of a second embodiment of a connecting element, according to one aspect of the invention.

In FIG. 1, a transmission device 1 is arranged between a motor shaft 2 and a receiving shaft 3. The transmission device 1 comprises a first flywheel 4, a second flywheel 5, a connecting element 6 of the first flywheel 4 with the motor shaft 2, and a disengageable coupling 7 for connecting the second flywheel 5 with the receiving shaft 3.

The first flywheel 4 comprises a radial wall 8 provided with a bore 9 and 1 with a thicker peripheral portion 10, projecting axially from a first side.

 The connecting element 6 is arranged on the first side of the first flywheel 4.

The connecting element 6 comprises a disc 11 provided with a bore 12 and an annular radial portion 13 whose inner diameter is greater than the outer diameter of the disc 11. The annular radial portion 13 is offset axially towards the first flywheel 4, in being connected to the outer edge 14 of larger diameter of the disc 11 by a curved portion 15. The curved portion 15 projects axially towards the first

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 flywheel 4 from the outer edge 14, and bends radially outward to come into connection with the zone of smaller diameter of the annular radial portion 13.

démontages. Une rondelle annulaire 19 est disposée axialement entre les têtes des vis ZD 18 et l'embase 17 pour permettre un serrage des vis 18 sans abîmer une surface de l'embase 17. Selon un agencement différent, les têtes des vis 18 sont situées du côté de l'embase 17 orienté vers le premier volant 4, une rondelle annulaire étant disposée axialement entre les têtes des vis 18 et l'embase 17 pour permettre un serrage des vis 18 sans abîmer une surface de l'élément de liaison 6. The annular radial portion 13 is in contact with the peripheral portion 10 of the first flywheel 4. The annular radial portion 13 and the peripheral portion 10 of the first flywheel 4 are mutually fixed by screws 16 arranged axially and symbolized, for reasons of clarity, by mixed lines. The drive shaft 2 is located on the side of the disc 11 opposite the first flywheel 4. The portion of smaller diameter of the disc 11 is fixed on a portion of larger diameter of a base 17 of the axial end of the drive shaft 2 , by means of screws 18 arranged axially, and represented by dashed lines. The screws 18 radially surround the motor shaft 2. The heads of the screws 18 are located on the side of the base 17 opposite the first flywheel 4, to facilitate access to the screw heads 18 during assemblies or

disassembly. An annular washer 19 is disposed axially between the heads of the ZD screws 18 and the base 17 to allow tightening of the screws 18 without damaging a surface of the base 17. According to a different arrangement, the heads of the screws 18 are located on the side of the base 17 oriented towards the first flywheel 4, an annular washer being disposed axially between the heads of the screws 18 and the base 17 to allow tightening of the screws 18 without damaging a surface of the connecting element 6.

 The second flywheel 5, similar to the first flywheel 4, is coaxial with the first flywheel 4. The second flywheel 5 is located on the side of the first flywheel 4 opposite the motor shaft 2. The second flywheel 5 comprises a radial wall 20 provided with a bore 21 and a thicker peripheral portion 22, projecting axially from the side opposite to the first flywheel 4.

 The disengageable coupling 7 comprises a first friction ring 23 fixed to the radial wall 20, on the side opposite to the first flywheel 4. A second friction ring 24 is arranged opposite the first friction ring 23, on the side opposite to the radial wall 2 of the second flywheel 5, being axially distant from the first friction ring 23. The second friction ring 24 is intended to be pressed axially against the first friction ring 23 for their mutual drive in rotation by friction. The second friction ring 24 is integral in rotation with the end of the receiving shaft 3. The second friction ring 24 is fixed to the outer edge of a thin drive disc 25, the inner edge of which is connected to an intermediate portion of a sleeve 26 surrounding the end of the receiving shaft 3. The sleeve 26 and the receiving shaft 3

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 are in rotation by means of grooves and corresponding grooves not shown. The sleeve 26 comes into axial abutment against an end shoulder 27 of the receiving shaft 3.

 An actuating disc 28 is disposed on the side of the second friction ring 24 opposite to the first friction ring 23. The actuating disc 28 comprises an outer edge 29 bent axially in the direction of the second friction ring 24, and an inner edge 30. The actuating disc 28 is in pivoting connection with the second flywheel 5 by means of a cup 31 comprising a first radial portion 32, a tubular portion 33, a second radial portion 34 and a portion toroidal 35. The first radial portion 32 is fixed on the peripheral portion 22, on the side opposite to the first flywheel 4. The tubular portion 33 extends axially on the side opposite to the second flywheel 5 from the zone of smaller diameter of the portion radial 32, and beyond the actuating disc 28. The second radial portion 34 extends inward from the free edge of the tubular portion 33. The toroidal portion 35 extends starting from the zone of smaller diameter of the second radial portion 34 while returning axially towards the second friction ring 24 and radially towards the outside, by forming a groove for housing an intermediate portion of the actuating disc 28.

second volant 5. L'élément de centrage 36 est fixé à la zone de moindre diamètre de e la paroi radiale 8 du premier volant 4 par l'intermédiaire de vis 39 symbolisées par des traits mixtes, et traversant axialement l'épaulement 38. Les têtes des vis 39 sont disposées du côté du premier volant 4 opposé au second volant 5, pour des raisons de commodité d'accès. Le second volant 5 est fixé à rotation sur l'élément de centrage 36 par l'intermédiaire d'un palier 40 qui peut être un palier à roulement ou un palier lisse. The first and second flywheels 4,5 are connected by a centering element 36, comprising an axis 37 crossing the bores 9,21 of the first and second flywheels 4, 5, and a shoulder 38 disposed axially on the side of the first flywheel 4 opposite the

second flywheel 5. The centering element 36 is fixed to the zone of smallest diameter of the radial wall 8 of the first flywheel 4 by means of screws 39 symbolized by dashed lines, and passing axially through the shoulder 38. The screw heads 39 are arranged on the side of the first flywheel 4 opposite to the second flywheel 5, for reasons of convenience of access. The second flywheel 5 is fixed to rotation on the centering element 36 by means of a bearing 40 which can be a rolling bearing or a plain bearing.

 The first and second flywheels 4,5 are linked in rotation with the possibility of angular displacement against elastic elements with circumferential action.

Helical springs 41 are arranged in notches 42,43 formed opposite in the radial walls 8,20 of the first and second flywheels 4,5. The springs 41 are each aligned with a direction perpendicular to the axis of revolution of the first and second flywheels 4,5, and offset with respect to said axis of revolution. The

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 ends of a spring 41 come to bear, not shown, on the one hand against an axial wall of the first flywheel 4, and on the other hand against an axial wall of the second flywheel 5 opposite to the corresponding axial wall of the first flywheel 4. Friction means 44 are arranged between the first flywheel 4 and the second flywheel 5. The friction means 44 comprise a ring 44a fixed on the radial wall 10 of the first flywheel 4 and coming into frictional contact with the radial wall 20 of the second flywheel 5. The friction means 44 exert a force opposing an angular displacement of one flywheel relative to the other.

 The disengageable coupling 7 allows the second flywheel 5 and the receiving shaft 3 to be joined or disengaged in rotation. The actuating disc 28 is prestressed and elastically deformable. The actuating disc 28 comprises in a known manner openings extending radially from the inner edge 30 and not visible in FIG. 1, to facilitate elastic deformation. The actuating disc 28 is associated in a known manner with a clutch stop (not shown) which can be moved axially between a retracted inactive position of the clutch, and an advanced active declutching position, bearing against the inner edge 30 of the disc d actuation 28. In the neutral position, the prestressed actuating disc 28 exerts, by its outer edge 29, an axial force for pressing the second friction ring 24 against the first friction ring 23. The drive disc 25 is slightly elastically deformed to allow an axial movement of approach of the second friction ring 24 fixed on its zone of larger diameter, towards the first friction ring 23.

When the friction rings 23, 24 are in contact, and that sufficient axial force is exerted, the first and second friction rings 23, 24 are linked in rotation. The second flywheel 5 is linked in rotation to the receiving shaft 3.

première couronne de friction 23. La seconde couronne de friction 24 s'éloigne t'D axialement de la première couronne de friction 23. Le second volant 5 et l'arbre récepteur 3 ne sont plus liés en rotation. When the clutch bearing is in the active position, the axial force exerted on the inner edge 30 of the actuating disc 28 causes an elastic deformation of the actuating disc 28. The outer edge 29 moves axially away from the

first friction ring 23. The second friction ring 24 moves axially away from the first friction ring 23. The second flywheel 5 and the receiving shaft 3 are no longer linked in rotation.

 The motor shaft 2 rotates the first flywheel 4 along an axis of rotation 45 of the first and second flywheels 4,5, which is their axis of axial alignment, via the connecting element 6. The first and second flywheels 4.5 are

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 linked in rotation by the circumferential action springs 41 and the friction means 44, which form a spring / damper type connection: the first flywheel 4 rotates the second flywheel 5 with a possibility of angular movement, with filtration and a damping of torque irregularities at the output of the motor shaft 2.

 In steady state, the motor shaft 2 rotates at a constant speed, and provides constant torque. The springs 41 are compressed so as to transmit the torque from the first flywheel 4 to the second flywheel 5. The angular displacement between the first and second flywheels 4,5 is constant. If the coupling 7 is engaged, the second flywheel rotates the receiving shaft 3, which exerts a resisting torque, for example a driving torque of the wheels of a motor vehicle.

par les moyens de friction 44. L'augmentation de couple est lissée par l'ensemble t : l double volant amortisseur formé par les premier et second volant 4,5, les ressorts 41 et les moyens de friction 41. Le lissage du couple de sortie dépend des inerties de rotation des premier et second volant 4,5, de la raideur et de l'agencement des ressorts 41 et des effort exercés par les moyens de friction 44. If the drive torque supplied by the drive shaft 2 increases, the first flywheel 4, tending to accelerate relative to the second flywheel 5, moves angularly relative to the second flywheel 5. The springs 41 are gradually compressed and exert a force upper torque transmission between the first and second flywheels 4,5. Torsional oscillations caused by the springs 41 are damped

by the friction means 44. The increase in torque is smoothed by the assembly t: l double damping flywheel formed by the first and second flywheel 4,5, the springs 41 and the friction means 41. The smoothing of the torque output depends on the inertias of rotation of the first and second flywheels 4,5, on the stiffness and arrangement of the springs 41 and on the forces exerted by the friction means 44.

 If the driving torque supplied by the drive shaft 2 decreases, the springs 41 gradually relax and exert a lower force. Torsional oscillations caused by the springs 41 are damped by the friction means 44.

 In operation, the torque supplied by the crankshaft of an internal combustion engine is irregular, in particular due to the offset combustion cycles in each cylinder of the internal combustion engine. The double torsional damping flywheel assembly allows smoothing and damping of torque irregularities transmitted between the motor shaft 2 and the receiving shaft 3. The flywheels 4,5 also allow, by their own rotational inertia, filtering of couple irregularities. Indeed, a torque variation on the motor shaft 2 or the receiving shaft 3 is smoothed by the first flywheel 4 or the second flywheel 5 which absorb rotational drive energy when they are accelerated or braked in rotation. Plus one

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 flywheel has a large rotational inertia, the more the flywheel can smooth low frequency torque variations.

 The flexible connecting element 6 allows filtering of bending vibrations transmitted by the drive shaft 2. In a conventional internal combustion engine, the rectilinear reciprocating movement of the pistons is transformed into the rotation movement of the crankshaft. The crankshaft, which is the output shaft of the engine, is subjected to bending forces which are the source of bending vibrations of the crankshaft transmitted to the double damper flywheel assembly. The frequencies of these vibrations can coincide with natural modes of vibration of the double damping flywheel assembly. Such a coincidence of frequencies will cause amplification of vibrations transmitted to a chassis of a motor vehicle. In particular, such frequencies may lie in the range of audible frequencies. Flexural vibrations will therefore be a source of noise in the passenger compartment of the vehicle.

 The bending characteristics of the connecting element 6 are adapted to best filter the bending vibrations which can be transmitted by the motor shaft 2. For example, depending on the bending stiffness of the connecting element 6, the vibrations of bending having a frequency within a determined range will be filtered. The connecting element 6 could be adapted so that the double damping flywheel assembly fixed on the motor shaft 2 has a natural frequency in bending of between 80 and 120 Hz. Indeed, a transmission device having such a natural frequency in bending when fixed on a motor shaft 2 allows decoupling between on the one hand the motor shaft 2 and an internal combustion engine, and on the other hand the transmission device.

 The connecting element 6 comprises a disc 11 and a radial portion 13 connected by a curved portion 15. Of course, any connecting element, having a torsional rigidity and a flexural flexibility allowing filtering of flexural vibrations and decoupling , may be suitable. In a variant, the flexing element comprises a disc whose region of larger diameter is in contact with the peripheral portion 10 of the first flywheel 4.

 The connecting element may advantageously comprise means for damping bending. In Figure 2, a connecting element 6 shown partially comprises a disc 46 without bore and formed of a superposition of thin annular plates 47, here four in number.

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 During the bending stress of the disc 46, along an axis perpendicular to its axis of revolution, the annular plates 47 each undergo a different deformation. In particular, two adjacent plates slide in frictional contact with each other. The friction between the two annular plates 47 causes dissipation of energy in the form of heat. When the connecting element 6 is stressed by bending vibrations, the friction causes damping of the vibrations by dissipation of energy. The connecting element then allows better damping of bending vibrations, and better decoupling between the motor shaft 2 and the double damping flywheel assembly.

d'irrégularités de couple fourni par un arbre moteur, et une filtration et un ZD amortissement de vibrations de flexion résultant de la sollicitation en flexion de l'arbre moteur. La diminution des vibrations transmises entre l'arbre moteur et un arbre récepteur permet de diminuer le bruit de fonctionnement du dispositif de transmission, et notamment le bruit ambiant de l'habitacle d'un véhicule automobile équipé d'un tel dispositif de transmission.Thanks to the invention, a transmission device of the double damping flywheel type is obtained which allows both filtration and damping.

torque irregularities provided by a motor shaft, and filtration and ZD damping of bending vibrations resulting from the bending stress of the motor shaft. The reduction in vibrations transmitted between the motor shaft and a receiving shaft makes it possible to reduce the operating noise of the transmission device, and in particular the ambient noise from the passenger compartment of a motor vehicle equipped with such a transmission device.

Claims (9)

1. Transmission device, of the double damping flywheel type, comprising first and second flywheels (4,5) of coaxial inertia linked in rotation respectively to a motor shaft (2) and a receiving shaft (3), the first and second flywheels (4,5) being linked in rotation by means of a torsion damping means (44,41), characterized in that it comprises a connecting element (6) of the first flywheel (4) and of the motor shaft (3), the connecting element (6) having a torsional rigidity and a flexibility in bending such that the connecting element allows filtering of bending vibrations.  2. Device according to claim 1, characterized in that the flexible connecting element (6) comprises means for damping bending.  3. Device according to any one of claims 1 or 2, characterized in that the connecting element (6) comprises a flexible disc (11) whose zone of smaller diameter is integral with the motor shaft (2) , the area of larger diameter being integral with a peripheral portion (10) of the first flywheel (4).  4. Device according to claim 3, characterized in that the flexible disc is formed by a superposition of thin plates (47).  5. Device according to any one of the preceding claims, characterized in that the flexibility of bending of the connecting element (6) is adapted so that the transmission device linked to the motor shaft (2) has a natural frequency in bending between 80 and 120 Hz.  6. Device according to any one of the preceding claims, characterized in that the first flywheel (4) can move angularly relative to the second flywheel against elastic elements with circumferential action (41).  7. Device according to any one of the preceding claims, characterized in that it comprises a centering element (36) of the first and second flywheels (4,5).  8. Device according to any one of the preceding claims, characterized in that the second flywheel (5) is linked in rotation to the receiving shaft (3) by means of a disengageable coupling (7).  9. Method for driving a receiving shaft (3) from a driving shaft (2), in which the rotation inertia of the driving shaft (2) is increased to <Desc / Clms Page number 12>  using a first flywheel (4), we increase the inertia of rotation of the receiving shaft (3) using a second flywheel (5), we link in rotation the first flywheel (4) and the second flywheel (5) by damping torque variations, characterized in that bending vibrations of the motor shaft (2) are filtered between the motor shaft (2) and the first steering wheel (4).