GB2211271A

GB2211271A - Rubber sleeve spring

Info

Publication number: GB2211271A
Application number: GB8824735A
Authority: GB
Inventors: Hans-Werner Schwerdt
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 1987-10-22
Filing date: 1988-10-21
Publication date: 1989-06-28
Anticipated expiration: 2008-10-21
Also published as: GB8824735D0; GB2211271B; DE3735698A1; FR2622268B1; FR2622268A1; JPH01145439A; DE3735698C2

Description

1 2211271 Rubber sleeve sprin The invention relates to a hydraulically

damped rubber sleeve spring comprising a supporting part and an outer tube, which are supported elastically on one another by a first elastic body of rubber, the elastic body containing at least two chambers which are located one behind the oiher in the direction of the forces introduced and which are connected by at least one throat and filled with fluid.

Such a rubber sleeve spring is known from European Patent Application 0,009,120. It can be used in the mounting of engines or gearboxes of motor vehicles and possesses very good properties. However, with respect to high-frequency vibrations, its very limited bump travel and its far from sufficient damping power provide little satisfaction.

The present invention seeks to provide an improved rubber sleeve spring such that its bump travel is increased and the isolation effect achieved with respect to the introduction of high-frequency vibrations is improved.

According to the invention there is provided a hydraulically damped rubber sleeve spring comprising a supporting part and an outer tube, which are supported elastically on one another by a first elastic body of rubber, the elastic body containing at least two chambers which are located one behind the other in the direction of the forces introduced and which are connected by at least one throat and filled with fluid, wherein the outer tube is located in a supporting tube and together with the supporting tube delimits a gap, and wherein a second elastic body is located in the gap.

In rubber sleeve springs according to the invention, the first elastic body and the second elastic body are arranged in series, which on the one hand increases the 2 available spring travel and on the other hand reduces the total resultant elastic stiffness. Rubber sleeve springs according to the invention are therefore suitable for absorbing without difficulty lowfrequency vibrations of large amplitude, which can arise, for example, when driving over bumps in a road. Moreover, they are also suitable for isolating high-frequency vibrations of an internal combustion engine, so that when- they are used as engine mounting of a motor vehicle, vibrations of this type can no longer make themselves felt as a disturbance in the motor vehicle.

The first and the second elastic bodies can have the same elastic stiffness and in this case the total available elastic stiffness. is halved.

Moreover, it is possible to prestress the second elastic body in an elastic fashion, for example by radial compression between the outer tube and the supporting tube.

The total load capacity achieved for the ready-to-use rubber sleeve spring can be improved thereby.

The second elastic body can be attached adhesively to the outer tube and/or to the supporting tube, for example by direct pre-vulcanization. The safety of the relative arrangement is thereby improved.

Designs in which the second elastic body is fixed adhesively only on one side have the advantage, by contrast, that the shrinkage stresses caused by the vulcanization can more easily be balanced. Corresponding designs are therefore preferred for use within the scope of the present invention.

The second elastic body can be provided with at least one recess running parallel to its extent, inorder to improve the resilience in this direction. The application to special features of the use is therefore readily 3 possible.

Generally speaking, large forces are required to be absorbed from only a single direction and it has proved to be advantageous for such instances to use a second elastic body which is bounded inside and outside by cylindrical faces arranged eccentrically to one another. In this connection, the magnitude of the eccentricity being applied can be measured so that a static load, superimposed on the dynamic forces to be absorbed, is -absorbed in such a way that a concentric arrangement of the two cylindrical faces one to another arises in the ready-to use state. All the available spring travels of the rubber sleeve spring are balanced in all directions.

To limit its relative axial mobility with respect to the outer tube, the supporting tube can be provided at least at one end with a flange projecting inwards in the radial direction, which at least partially overlaps the end face of the outer tube in the radial direction. With the application of a supporting tube of a plastically formable material, the making of an appropriate flange is relatively simple and can take place, for example, by flanging an end section of the supporting tube which at first projects in the axial direction.

An appropriately designed flange can be located on the boundary surface. at the end face of the outer tube such that no significant play is present between the two. In this way, it is possible to achieve very high restrictions on relative axial displacements of the outer tube with respect to the supporting tube.

According to an advantageous embodiment, it is envisaged that at least one of the two faces considered above, which are axially opposite one another, is provided with an impact-damping coating, for example a coating of rubber. This can be designed in one piece with the second 4 elastic body, and can prevent the occurrence of noises due to road bumps.

The outer tube can, of course, also be encompassed at both ends in the axial direction by radially inwardly projecting flanges of the supporting tube. It is possible in this way to encounter relative axial displacements in both directions.

The present invention is further illustrated with reference to the accompanying drawings, in which:

Figure 1 shows a rubber sleeve spring according to the invention in cross-section; Figure 2 shows the rubber sleeve spring of Figure 1 in longitudinal section along the line A in Figure 1; Figure 3 shows an enlarged partial detail of the 15 region marked "Z" of a spring similar to the spring of Figure 2; and Figure 4 shows another rubber sleeve spring according to the invention.

The hydraulically damped rubber sleeve spring shown in Figures 1, to 3 comprises a supporting part 1 having a bore 14 which penetrates the supporting part completely in the longitudinal direction. The supporting part 1 is sur rounded, concentrically with the bore 14, by a two part outer tube 2, 4 and is attached elastically to the inner wall of the latter by the first elastic body 3 of rubber.

The elastic body 3 has two chambers 9, 9a located one behind the other in the direction of the forces introduced, and these chambers are connected by two throats 12, and filled with fluid. The direction of the forces introduced is indicated by an arrow.

The outer tube 2, 4 is located in a supporting tube 6 and together with the latter delimits a gap, in which a second elastic body 5 is located. The second elastic body 5 is designed to be specular in the direction of the forces 6 introduced owing to the operational conditions and indicated by the arrow A and has two recesses 7 located one behind the other in this direction. The elastic stiffness in this direction is thereby reduced, which is equivalent to an improvement of the isolation of high-frequency vibrations.

The second elastic body 3 is attached adhesively by means of direct prevulcanization to the inwards-looking surface of the supporting tube 6. As conditioned by a manufacturer, its internal diameter is slightly smaller than the outer diameter of the outer tube 4, so that when it is pushed onto the latter, there is a build-up of radially directed prestressing in the second elastic body. The fatigue limit is thereby greatly improved.

-As can be seen in particular from the longitudinal 20 section (Figure 2) of the ring, the supporting tube 6 is provided at both ends in the axial direction with flanges 8 projecting inwards, and these flanges overlap the faces of the outer tube 4 inwards in the radial direction. In this connection, the axial separation between the faces and the flanges is dimensioned so as to guarantee a good radial mobility of the supporting tube 6 with respect to the outer tube 4 while avoiding a significant play.

In the illustrated embodiment, the recess 7 is filled with air and connected to the atmosphere by a ventilation bore, not shown. The chambers 9, ga and the throats 12 are filled with a frost-resistant mixture of glycol and water.

As can be seen from Figure 3, an impact-damping layer of rubber may be provided in the region of the end face of the outer tube 4 and the face of the flange 8 which is 6 axially opposite to it. This layer may be manufactured in one piece with the second elastic body 5.

The design of the spring shown in Figure 4 resembles the spring according to Figure 1 in its basic construction.

In this case, however, the second elastic body is bounded inside and outside by cylindrical faces, which are arranged eccentrically to one another in the unloaded stage of the rubber sleeve spring. Moreover, the recesses 7 of the second elastic body 5, which, as in the design according to Figure 1, extend parallel to the longitudinal direction of the rubber sleeve spring, are bounded in a semicircular fashion, as shown. Their cross-section is of a larger dimension in the lower part of the drawing than in the upper part of the drawing. In conjunction with the larger radial width of the elastic body 5 in the lower part, the rubber sleeve spring shown in Figure 3 is thereby able to absorb a static initial load in such a way that in the loaded state there is a concentric arrangement of the axial bore 14 of the supporting part 1 in the supporting tube 6.

The mutual radial mobility of the two parts to one another is balanced in all directions.

Claims

7 Claims

1. A hydraulically damped rubber sleeve spring comprising a supporting part and an outer tube, which are supported elastically on one another by a first elastic body of rubber, the elastic body containing at least two chambers which are located one behind the other in the dfrection of the forces introduced and which are connected by at least one throat and filled with fluid, wherein the outer tube is located in a supporting tube and together with the supporting tube delimits a gap, and wherein a second elastic body is located in the gap.

2. A rubber sleeve spring according to claim 1, wherein the second elastic body is' radially compressed between the outer tube and the supporting tube.

3. A rubber sleeve spring according to claim 1, wherein the second elastic body is attached adhesively to the outer tube and/or to the supporting tube.

4. A rubber sleeve spring according to any of claims 1 to 3, wherein the second elastic body is provided with at least one recess running parallel to its extent.

5. A rubber sleeve spring according to any of claims 1 to 4, wherein the second elastic body is bounded inside and outside by pylindrical faces arranged eccentrically to one another.

6. A rubber sleeve spring according to claim 4 or 5, wherein the second elastic body is designed to be specular in the direction of the forces introduced.

7. A rubber sleeve spring according to any of claims 1 to 6, wherein the supporting tube is provided at least at one end with a flange projecting inwards in the radial direction and in that the flange overlaps the outer tube in 8 the radial direction.

8. A rubber sleeve spring according to claim 7, wherein the outer tube and the flange haveno significant separation in the region of their faces which are axially oppos-ite one another.

9. A rubber sleeve spring according to claim 8, wherein at least one of the said faces is provided with an impact-damping coating.

10. A rubber sleeve spring according to any of claims 7 to 9, wherein the outer tube is overlapped at both ends by radially inwardly projecting flanges of the supporting tube.

11. A hydraulically damped rubber sleeve spring substantially as hereinbefore described with reference to Figures 1 and 2 or Figure 3 or Figure 4 of the accompanying drawings.

Published 1989 atThe PatentOffice, StateRouse, 66171 High HolboMLondonWC1R4TP. Purther copies maybe obtainedfrom. The Patentomce. Sales Branch, St Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con- 1187