GB2306613A

GB2306613A - A torsional vibration damper having a gap formed by cooling after vulcanization

Info

Publication number: GB2306613A
Application number: GB9621403A
Authority: GB
Inventors: Hans-Werner Schwerdt
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 1995-10-21
Filing date: 1996-10-14
Publication date: 1997-05-07
Anticipated expiration: 2016-10-14
Also published as: GB2306613B; DE19539232A1; DE19539232C2; GB9621403D0

Description

2306613 Torsional Vibration Damper The present invention relates to a

torsional vibration damper, comprising at least two machine parts which bound a clearance and are connected by at least one spring body made of elastomeric material arranged in the clearance, the spring body having at least two adhesive surfaces which are each fixed on one of the machine parts, the other surfaces of the spring body and machine part(s) which lie opposite one another being formed by guide surfaces which are spaced apart, and the gap formed by the spacing being of liquid-tight design and being filled with a viscous liquid.

A torsional vibration damper of this type is known from DE 33 34 881 Al. The spring body is connected to the adjoining machine parts only by the adhesive surfaces, the adhesive surfaces forming constituent parts of extensions which absorb the relative displacements of the two machine parts mainly by elastic deformation, whereas the spring body itself is largely unaffected by this. The gap has a width of a few tenths of a millimetre and is filled with a viscous liquid which brings about good damping of the relative motion of the connected machine parts. Owing to the fact that the spring body remains substantially undeformed outside its adhesive surfaces, a good radial support between the two machine parts is ensured even when a relative rotation is introduced.

It is an object of the invention to develop a torsional vibration damper of the previously known type in such a way as to result in simplified manufacture of the gap and improved damping.

According to the invention, there is provided a torsional vibration damper, comprising at least two machine parts which bound a clearance and are connected by at least one spring body made of elastomeric material arranged in the clearance, the spring body having at least two adhesive surfaces which are each fixed on one of the machine parts, the other surfaces of the spring body and machine part(s) which lie opposite one another being formed by guide surfaces which are spaced apart, and the gap formed by the spacing being of liquid-tight design and being filled with a viscous liquid, characterized in that the gap is formed by at least one shrinkage clearance which is due to manufacture, and in that the shrinkage clearance is designed in a meandering form, viewed in cross-section.

During the vulcanization of rubber and metal parts, due to the chemical reaction and the cooling of the spring body consisting of an elastomeric material, shrinkage stresses occur which lead to a reduction in diameter and to a detachment of the rubber from the adjoining machine part if there is no fastening. The size of shrinkage can be increased by using a suitable elastomeric material in such a way that a shrinkage clearance of a f ew tenths of a millimetre in width occurs.

owing to the shrinkage stresses in the elastomeric material, a heat shrinkage gap develops due to manufacture, following the cooling of the spring body. The gap is filled with a viscous liquid. By shearing of the viscous liquid which consists, for example, of a silicon oil, damping of the movement of the two machine parts relative to one another is brought about. The damping is dependent on the size of the shearing surface and thus on the size of the shrinkage clearance. Owing to the meandering design, the shearing surface within the shrinkage clearance is enlarged considerably and the damping thus improved.

The gap in the torsional vibration damper according to the invention can be manufactured in a very simple manner, and the damping of the torsional vibration damper is improved by the enlargement of the shearing surface within the shrinkage clearance which is due to manufacture. An enlarged shearing surface can be achieved advantageously by an increased number of meanders and/or by a greater axial extent of the shrinkage clearance.

The machine part bounding the shrinkage clearance and the spring body may have a surface profile of congruent design on the mutually facing sides. The projections of the surface profiles engaging in one another may, for example, be of trapezoidal design, viewed in cross-section. In this case, it is advantageous that shrinkage of the spring body, due to maanufacture, while it is cooling brings about a shrinkage clearance which is largely of uniform size along the entire axial and circumferential extent of the spring body. The trapezoidal design of the shrinkage clearance ensures an excellent support of the machine part provided with the surface profile on the spring body both in the radial and in the axial direction. A differing surface profile may, for example, be formed by a congruently designed, undulating surface profile of the spring body and adjoining machine part. In this case, too, in the case of rotations of the two machine parts relative to one another, an excellent axial and radial support of the parts on one another is guaranteed. An excellent damping effect is achieved by the meandering shrinkage clearance and the comparatively large shearing surface of the damping liquid arranged within the clearance.

The machine part bounding the shrinkage clearance can have a duct-shaped and closeable opening for filling with the liquid. The opening may, for example, be formed by a bore which passes through the machine part in the radial direction and opens out in the shrinkage clearance. Following the filling, the opening may, for example, be closed in a liquid-tight manner by a grub screw in order to avoid loss of the damping liquid during the intended use of the torsional vibration damper.

In order to avoid contact of the surface profile of the machine part and the spring body which form the shrinkage clearance and to avoid any damage to the spring body, the viscous liquid may be forced into the shrinkage clearance under a relative overpressure and held therein. 5 This further improves the damping.

The spring body and the adjoining machine parts are preferably designed to be rotationally symmetrical. The risk of any undesired unbalance is thus reduced to a minimum.

The machine parts are preferably f ormed by a hub ring and a flywheel ring which surrounds the hub ring with radial spacing, the spring body being arranged in the clearance formed by the spacing. in this case, it is advantageous that the flywheel ring is arranged radially on the outer side of the hub ring, and a comparatively large inertia mass is thus made available for damping torsional vibrations.

According to another configuration, it is possible for the machine parts to be f ormed by a hub ring and a flywheel ring which is surrounded by the hub ring with radial spacing, the spring body being arranged in the clearance formed by the spacing.

The spring body is preferably vulcanized onto the hub ring as a continuous coating.

Five exemplary embodiments of the torsional vibration damper according to the invention are described in greater detail below with reference to the accompanying drawings, in which:

Figure 1 shows a first embodiment of a torsional vibration damper, the machine part designed as a flywheel ring being arranged radially on the outer side; Figure 2 shows a second embodiment, in which the flywheel ring is arranged radially on the inner side; Figure 3 shows a third embodiment, similar to the embodiment of Figure 1, the spring body 4 being of differing design in the region of its axial boundaries; Figure 4 shows a fourth embodiment, similar to the embodiment of Figure 2, the second adhesive surfaces having a comparatively smaller diameter; and Figure 5 shows a fifth embodiment, in which the axial boundaries of the spring body of Figures 3 and 4 are combined with one another.

Figures 1 to 5 each show an embodiment of a torsional vibration damper which comprises a first machine part 2 and a second machine part 3 supported thereon by a spring body 4 made of elastomeric material. The spring body 4 is vulcanized onto the first machine part 2 as a continuous coating and, with the second machine part 3, bounds a gap 8 which is designed as a shrinkage clearance 10. The spring body 4 is attached to the first machine part 2 by its first adhesive surface 5, while the second adhesive surfaces 6 are connected to the second machine part 3. The surfaces of the spring body 4 and the machine parts 2, 3 which lie opposite one another comprise guide surfaces 7 which are spaced apart, the gap 8 being formed by the spacing and being formed as a shrinkage clearance 10 due to manufacture. The viscous liquid 9 consists of silicon oil.

In each of the five exemplary embodiments, the shrinkage clearance 10 is designed in a meandering form, viewed in cross-section.

An opening 13 is provided in each case for filling the shrinkage clearance 10 with the liquid 9, which opening 13 is designed as a bore and can be closed following the filling of the shrinkage clearance 10.

The shrinkage clearance 10 is bounded by the surface profiles 11, 12 of the second machine part 3 and of the spring body 4, which surface profiles each have a trapezoidal cross-section and are designed to be congruent.

Figure 1 shows a f irst embodiment of the torsional vibration damper according to the invention, in which the f irst machine part 2 is designed as a hub ring and is surrounded on the outer circumference with radial spacing by the second machine part 3 which is formed by a f lywheel ring, the spring body 4 being arranged in the clearance 1 formed by the spacing. The shrinkage clearance 10 is bounded on the radially outer side by the second machine part 3 and on the radially inner side by the spring body 4.

Figure 2 shows a second embodiment in which, in contrast to the embodiment of Figure 1, the second machine part 3 is arranged radially within the first machine part 2 and the spring body 4. The first machine part 2 is designed as a pot-shaped hub ring and, with radial spacing, surrounds the second machine part 3 which is designed as a flywheel ring, the spring body 4 being arranged in the clearance 1 formed by the spacing.

Figure 3 shows a third embodiment which differs from the embodiment of Figure 1 by the fact that the second adhesive surfaces 6 are arranged at a greater diameter than the guide surfaces 7. The radial extent of the spring body 4 is greater at the second adhesive surfaces 6 than at the guide surfaces 7.

Figure 4 shows a fourth embodiment, similar to the embodiment of Figure 2, the second adhesive surfaces 6 being arranged at a smaller diameter than the guide surfaces 7, and the radial extent of the spring body 4 being smaller at the second adhesive surfaces 6 than at the guide surfaces 7. Owing to such a configuration, in the case of equal rotation of the two machine parts 2, 3 relative to one another, due to the second adhesive surfaces 6 being located relatively - 7 further inside, the shearing stress on them is reduced compared to the embodiment of Figure 2. Such a configuration is exceptionally advantageous in terms of consistently good properties of use throughout a long service life.

Figure 5 shows a fifth embodiment, in which the radial extent of the second adhesive surfaces 6 corresponds to the greatest radial extent of the guide surfaces 7. In this embodiment the first adhesive surface 5 is offset outwards in the radial direction in relation to the embodiments of Figures 1 and 3. The mechanical load on the first adhesive surface 5 is thus reduced in the case of rotations of the two machine parts 2, 3 relative to one another.

Claims

1. A torsional vibration damper, comprising at least two machine parts which bound a clearance and are connected by at least one spring body made of elastomeric material arranged in the clearance, the spring body having at least two adhesive surfaces which are each fixed on one of the machine parts, the other surfaces of the spring body and machine part(s) which lie opposite one another being formed by guide surfaces which are spaced apart, and the gap formed by the spacing being of liquid-tight design and being filled with a viscous liquid, characterized in that the gap is formed by at least one shrinkage clearance which is due to manufacture, and in that the shrinkage clearance is designed in a meandering form, viewed in cross-section.

2. A torsional vibration damper according to Claim 1, characterized in that the machine part bounding the shrinkage clearance and the spring body each have a congruently designed surface profile on the mutually facing sides.

3. A torsional vibration damper according to either of Claims 1 or 2, characterized in that the machine part bounding the shrinkage clearance has a duct-shaped and closeable opening for filling with the liquid.

4. A torsional vibration damper according to any one of Claims 1 to 3, characterized in that the shrinkage clearance can be pressurized.

5. A torsional vibration damper according to any one of Claims 1 to 4, characterized in that the spring body and the adjoining machine parts are designed to be rotationally symmetrical.

6. A torsional vibration damper according to any one of Claims 1 to 5, characterized in that the machine parts are formed by a hub ring and a f lywheel ring which surrounds the hub ring with radial spacing, and in that the spring body is arranged in the clearance formed by the spacing.

7. A torsional vibration damper substantially as hereinbefore described with reference to any one of the accompanying drawings.