GB2245337A

GB2245337A - Torsional vibration damper having a hydraulic damping arrangement

Info

Publication number: GB2245337A
Application number: GB9111410A
Authority: GB
Inventors: Oswald Reis
Original assignee: Fichtel and Sachs AG
Current assignee: ZF Sachs AG
Priority date: 1990-05-31
Filing date: 1991-05-28
Publication date: 1992-01-02
Anticipated expiration: 2011-05-28
Also published as: GB2245337B; FR2662774B1; GB9111410D0; FR2662774A1; DE4017514A1

Description

k TORSIONAL VIBRATION DAMPER HAVING A HYDRAULIC DAMPING ARRANGEMENT This

invention relates to a torsional vibration damper, in particular for the drive train of a motor vehicle.

German Patent 28 48 748 discloses a vibration damper for the drive train of a motor vehicle having a spring device and, disposed parallel thereto, a hydraulic damping arrangement. The vibration damper comprises a hub disk with apertures for receiving helical springs arranged substantially tangentially about an axis of rotation, housing parts disposed on either side of the hub disk and having pockets into which the helical springs engage, and an elongation of the hub disk which projects beyond the radial extension of the helical springs, extends in a circumferential annular chamber formed by the housing parts and, together with noses projecting radially from the outer diameter of the hub disk and inward- directed noses of the housing arranged in an offset manner over the periphery, forms displacement areas which are filled with a damping medium.

In said known construction, the displacement areas provided in the region radially outside of the helical springs are filled with a viscous medium and produce a hydraulic damping effect in the event of torsional stress and torsional vibrations.

An object of the present invention is further to develop a vibration damper according to prior art in such a way that under normal, substantially stable, operating conditions damping is kept to a minimum and only becomes fully effective under operating conditions in which extreme relative displacements occur between the input and output parts of the vibration damper.

According to the invention there is provided a torsional vibration damper, in particular for the drive train of a motor vehicle comprising a substantially disk-shaped first damper part arranged so as to be rotatable about an axis of rotation, a second damper part forming a housing arranged coaxially to the first damper part and rotatable through a limited relative rotation angle relative to the first damper part, said second damper part accommodating the first damper part axially between two side wall portions and, to form a hydraulic damper arrangement together with the first damper part, enclosing in an externally sealing manner at least one ring segment-shaped displacement area containing a damping fluid, which is defined in a peripheral direction by noses of one of the two damper parts and into which protrudes a nose, bridged in a peripheral direction by a (first) throttle channel, of the other of the two damper parts, and a plurality of springs, which are arranged substantially tangentially on the side of the displacement area allocated to the axis of rotation and connect the two damper parts to one another in a torsionally elastic manner, said springs being disposed in apertures of the first damper part and engaging into recesses in the side wall portions of the second damper part, characterised in that there is guided movably in a peripheral direction in the displacement area a displacer, which together with one of the damper parts defines a displacement chamber likewise containing damping fluid, into which nose of said one damper protrudes with clearance in a peripheral direction, and that the nose protruding into the displacement chamber is bridged within the displacement chamber by a second throttle channel.

By using preferably cap-shaped displacers, which are inverted over the displacement noses and have clearance in a peripheral direction relative to the noses, it is possible by suitably tuning said clearance to achieve a "delayed" damping effect which does not come into effect until a specific torsion angle is exceeded. It is thereby ensured that, under stable operating conditions such as, for example, no load or uniform tensile or axial load, damping is kept to a minimum, thereby making it possible to achieve good isolation of the drive train from the internal combustion engine. The full damping capacity only comes into effect when the specific torsion angle is exceeded, as is the case particularly when passing through resonant frequencies or in the event of an abrupt change of load.

To maintain the full damping capacity it is advantageously provided that the housing is sealed off by an annular seal provided radially inside of the outer diameter of the disk of the first damper part on both sides. Said seal may be a labyrinth seal b,t may alternatively be a contact seal or a combination of the two.

It is further proposed to provide the displacer with connecting channels which connect the interior, i e the displacement chamber, to the relevant externally adjoining displacement area. Said connecting channels are closed by the displacement noses of, e 9, the first damper part during non-stable operating conditions. It is thereby ensured that the displacers, if loosely installed, remain stationary relative to the second damper part in the event of slight vibrations.

At the same time, the damping elements, which are preferably made of plastic, may be designed as torsion angle stop buffers.

The invention will now be described by way of example with reference too the accompanying drawings in which:

FIGURE 1 is the upper half of a longitudinal section through a twin-mass flywheel with delayed hydraulic damping, viewed along a line I-I in Figure 2; and FIGURE 2 is a partial view as section II-II of Figure 1.

The invention is explained using the example of a twin-mass flywheel. It may be used with equal success in a standard clutch disk. In the present example, the twin-mass flywheel comprises a flywheel 1 on the engine side and a flywheel 2 on the clutch side, with the two flywheels 1, 2 being supported rotatably and in a fixed manner relative to one another by means of a bearing 3. All the structural components extend concentrically to a common axis of rotation 8. The flywheel 1 on the engine side is substantially pot-shaped and is tightly closed off from the side of the flywheel 2 bv a lateral disk 5. The lateral disk 5 is sealed off on the one hand at 30 from the flywheel 1 and on the other hand by a seal 29 from the flywheel 2. The flywheel 1 and the lateral disk 5 form a housing having an area in which there extends substantially in a radial direction a hub disk 4, which in its radially inner region is disposed by means of toothing 28 in a torsion-resistant manner on an extension of the flywheel 2, has approximately in its central region apertures 6 for disposing substantially tangentially mounted helical springs 7 and, radially outside of the helical springs, forms a circular cylindrical outer periphery 13, from which emanates a plurality of radially projecting noses 10 which are distributed over the periphery. The flywheel 1 has an inner periphery 12 at a radial distance from the noses 10 and, with the outer periphery 13 of the hub disk 4, defines an annular area in which noses 11 of the flywheel 1 are situated and are in fact situated over the periphery in an offset manner relative to the noses 10 of the hub disk 4. A displacer 16 is inverted radially from the outside over each of the noses 10 of the hub disk 4, said displacer substantially filling the radial area between the two peripheries 12 and 13 and forming an inner chamber which, in terms of the periphery, is greater than the peripheral extension of the noses 10. A gap 17 is further provided between the bottom region of the displacer - 5 16 and the radially outer end region of the nose 10. The annular area is axially defined by a side wall 14 of the flywheel 1 and by an opposing side wall 15 of the lateral disk 5, with the axial distance between the two side walls 14 and 15 being greater than the material thickness of the hub disk 4. Said area axially between the hub disk 4 and the two side walls 14 and 15 is basically filled by the material of t he displacer 16. Also disposed circumferentially in the displacer 16 are approximately tangentially extending channels 27, each of which terminates in an inner wall 26 corresponding with an approximately radially extending wall 25 of the nose 10, with the result that, after the clearance 18 between the nose 10 and one or the other inner wall 26 of the damping element 16 has been used up, the relevant channel 27 is blocked. The displacers 16 distributed over the periphery and the noses 11 of the flywheel 1 form displacement areas 19, 20, 21, 22 which are filled with a liquid or pastelike damping medium or fluid. Gaps between the displacers 16 and the walls of the displacement areas, which are described in greater detail below, form throttle channels which bridge the displacers 16 in shunt. For sealing said displacement areas in a radially inward direction, in the present example there is provided both a circumferential labyrinth seal by means of corresponding webs 24 on the flywheel 1 and the lateral disk 5 as well as a seal 23 on either side of the hub disk 4. The sealing lips of the seals 23, which slope radially outwards, may be designed in such a way that, from a predetermined speed of, for example, 1000 revolutions, they lift slightly from the hub disk 4 with the result that, on the one hand, no wear.can occur at said points during operation and, on the other hand, the damping medium, some of which is also in the spring chamber, can be moved outwards again by centrifugal force. The inner areas of the displacers 16 likewise contain damping medium and form damping chambers into which the noses 10 acting as displacers protrude. The gaps 17 thereby form throttle channels which bridge the noses 10 in shunt. The activation of the helical springs 7 by the flywheel 1 is effected by means of pockets 9 provided both in the flywheel 1 and in the lateral disk 5.

The torsional vibration damper of Figs.1 and 2 operates as follows: In a position of rest, the hub disk 4 assumes, for example, the position shown in Fig.2 relative to the flywheel 1. Proceeding from said position of rest, during no-load operation virtually no torque is transmitted and the excursions resulting from the cyclic irregularity of the internal combustion engine may with suitable tuning be so selected that the noses 10 do not exceed the prescribed clearance 18. In said operating state there is therefore a very slight damping effect occasioned by the viscosity of the damping medium and by the size of the gap 17. Durin4 a subsequent starting process involving the application of a high torque or when passing through resonance speeds, the flywheel I is first accelerated and with the hub disk 4 moves ahead of the flywheel 2. One wall 25 of the nose 10 therefore strikes the inner wall 26 of the displacer 16 and hence closes the channel 27. With closing of the channel 27, the high damping force sets in and the damping medium is compelled to pass from one displacement area into another, with very small gaps which bridge the displacers 16 being provided as an obstacle. Maintaining said gaps to achieve a defined maximum damping effect may be achieved, for example, by designing the displacers 16 so that they are slightly narrower in an axial direction than the clearance between the side walls 14 and 15. It is however also possible, for improved fixing in position of the displacers 16, to prestress said displacers slightly in an axial direction, in which case it is then possible, for example, to provide the damping gap radially between the displacer 16 and the inner periphery 12. It is equally possible to fix a damping gap between the noses 11 and the outer periphery 13 of the hub disk 4. During steady-state operation while the motor vehicle is travelling, good isolation is again achieved in that the noses 10 may move relatively freely within the clearance 18 in the displacers 16. Only in the event of an abrupt change of load, e.g. as a result of sudden deceleration, will the full damping force set in again, once the clearance 18 has been used up.

k The channels 27 provided in the displacers 16 on the one hand reduce the damping effect during no-load operation and on the other hand ensure that the interior of the displacer is completely filled with damping medium.

1

Claims

CLAIMS:

1. Torsional vibration damper, in particular for the drive train of a motor vehicle, comprising a substantially disk-shaped first damper part (4) arranged so as to be rotatable about an axis of rotation (8), a second damper part (1, 5) forming a housing arranged coaxially to the first damper part (4) and rotatable through a limited relative rotation angle relative to the first damper part (4), said second damper part accommodating the first damper part (4) axially between two side wall portions (1, 15) and, to form a hydraulic damper arrangement together with the first damper part (4), enclosing in an externally sealing manner at least one ring segment-shaped displacement area (19, 20, 21, 22) containing a damping fluid, which is defined in a peripheral direction by noses (11) of one (1, 5) of the two damper parts and into which protrudes a nose (10), bridged in a peripheral direction by a (first) throttle channel, of the other of the two damper parts (4), and a plurality of springs (7), which are arranged substantially tangentially on the side of the displacement area (19, 20, 21, 22) allocated to the axis of rotation (8) and connect the two damper parts (1, 5; 4) to one another in a torsionally elastic manner, said springs being disposed in apertures (6) of the. ' first damper part (4) and engaging into recesses (9) in the side wall portions (14, 15) of the second damper part (1, 5), characterised in that there is guided movably in a peripheral direction in the displacement area (19, 20, 21, 22) a displacer (16), which together with one (4) of the damper parts defines a displacement chamber (18) likewise containing damping fluid, into which nose (10) of 1 J k - 9 said one damper part (4) protrudes with clearance in a peripheral direction, and that the nose (10) protruding into the displacement chamber (18) is bridged within the displacement chamber (18) by a second throttle channel (17).

2. Torsional vibration damper according to claim 1, characterised in that the nose (10) protruding into the displacement chamber (18) of the displacer (16) projects radially from the outer periphery of the first damper part (4), and that the displacer (16) is approximately cap-shaped and is inverted over said nose (10).

3. Torsional vibration damper according to claim 1 or 2, characterised in that the second throttle channel (17) comprises a gap between the radial front end of the nose (10) protruding into the displacement chamber (18) and a radially opposing wall surface of the displacement chamber (18).

4. Torsional vibration damper according to claims 1 to 3, characterised in that the displacement chamber (18) of the displacer (16) is defined in a peripheral direction on both sides by end walls (26), of which at least one contains a channel (27) extending through in a peripheral direction and connecting the displacement chamber (18) to the displacement area (19, 20, 21, 22), and that the nose (10) protruding into the displacement chamber (18) overlaps the channel (27) and, after compensation for its clearance of motion in the displacement chamber (18), closes the channel (27).

5. Torsional vibration damper according to one of claims 1 to 4, characterised in that annular seals (23, 24) are provided axially on either side of the first damper part (4), said seals sealing off the first damper part (4) radially between the ring segment-shaped damper area (19, 20, 21, 22) and the springs (7) from the side wall portions (14, 15) of the second damper part (1, 5).

6. Torsional vibration damper according to claim 5, characterised in that the seals comprise labyrinth seals (24).

Torsional vibration damper according to claim 5 or 6, characterised in that the seals comprise contact sealing rings (23). -

8. Torsional vibration damper according to claim 7, characterised in that the contact sealing rings (23) have sealing lips which slope radially outwards and at an angle to the axis of rotation.

9. Torsional vibration damper according to claims 1 to 8, characterised in that the displacer (16) forms a stop buffer for limiting the relative rotation angle of the two damper parts (1, 5; 4).

1T. A torsional vibration damper substantially as described by way of example with reference to the accompanying drawings.

Published 1991 at The Patent Office, Concept House. Cardiff Road. Newport. Gwent NP9 1 RH. Further co may be obtained frorn pies ltd. St Mary Cray. Kent.

Sales Branch, Unit 6 Nine Mile Point, Cwmfelinfach. Cross Keys, Newport. NP1 7HZ. Printed by Multiplex techniques