GB2074696A

GB2074696A - Construction of rubber bush

Info

Publication number: GB2074696A
Application number: GB8112144A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1980-04-22
Filing date: 1981-04-16
Publication date: 1981-11-04
Also published as: DE3015322A1; FR2480682A1

Abstract

An arrangement for the resilient mounting of a chassis element, such as a stabiliser torsion bar, in a motor vehicle comprises at least one rubber sleeve 1, enclosing the said element (not shown), which has a circularly cylindrical bore whose internal diameter is larger than the diameter of the said element and is, in turn, enclosed by a holding sleeve (not shown) having an internal diameter smaller than the external diameter of the rubber sleeve, at least the circularly cylindrical interior of the rubber sleeve having moulded projections, bosses, annular or longitudinal ribs 2, 4, 6, which bear as a result of deformation, on a round outer surface of the element in such a manner that rubber material is pressed into spaces 3, 5, 7, between said projections, in the rubber sleeve. Moulded projections may be provided also on the outside of the rubber sleeve. The projections improve the adhesion between the rubber sleeve and the element. <IMAGE>

Description

SPECIFICATION Arrangement for the mounting of chassis elements in motor vehicles The invention relates to an arrangement for the resilient mounting or suspension of chassis elements in motor vehicles, particularly for the elastic mounting of a stabiliser torsion bar, enclosed by at least one rubber sleeve which has circularly-cylindrical interior of larger diameter than the diameter of the said element and is, in turn, enclosed by a holding sleeve having an internal diameter smaller than the external diameter of the rubber sleeve, the said holding sleeve being preferably secured to the superstructure or body of the vehicle.

The rubber sleeve may then have an elliptical external cross-section.

For mounting a torsion bar in relation to the vehicle body, use is generally made, currently, of rubber blocks having an internal bore within which the torsion bar is gripped. The rubber blocks are enclosed on the outside by a holding sleeve which is conventionally secured to the body. The internal diameter of the bore in the rubber sleeve is usually less than the diameter of the torsion bar and the holding sleeve secured to the body is so clamped together during assembly that the rubber sleeve is put under initial stress. During turning of the torsion bar, additional deforming strains are exerted on the mounting in the circumferential direction. Depending on the dimensions of the mounting, or bearing, and on the quality of the rubber, relative movements can occur between the mounting and the torsion bar. Relatively large movements cause slip and can result in noise.

The invention seeks to prevent or, at least, to reduce slipping movements and noise entailed thereby.

A similar object was to be achieved in a torsion-spring mounting according to U.S. Patent Specification 2,409,500. In this case recesses into which pliable rubber material was to be pressed under initial stress were provided in the outer holding sleeve. However, mountings of this kind have the disadvantage that rubber bulges thereby formed can easily tear off and lead to recurrence of the slip intended to be prevented.

In contrast, according to the present invention, at least the circularly cylindrical bore of the rubber sleeve has moulded projections which, as a result of deformation, bear on the round outer surface of the torsion bar or other element in such a manner that rubber material is pressed into the cavities existing, between the projections, in the rubber itself. The said projections may comprise longitudinal ribs which leave between them channels of approximately equal width or annular transverse ribs which leave between them annular channels of approximately equal width. Further, the projections may comprise bosses of substantially the shape of truncated pyramids which form free spaces of approximately equal width extending around each boss between it and the next boss.

Moulded projections may also be provided on the outside of the rubber sleeve.

When torsion-bar stabilisers are assembled, the moulded projections are put under initial stress. Since positive and negative formations are located side by side in the profile, the compressed rubber material can partially expand laterally into the channels or spaces.

When the torsion bar turns, stress is relieved in these rubber parts and the moulded projections expand. As a result, transverse deformation diminishes. Whereas, in conventional rubber mountings or bearings, transverse contraction becomes effective over the entire surface of the mounting and, consequently, sliding movements parallel to the longitudinal axis of the torsion bar occur or the mounting becomes constricted and lifts away from the torsion bar as a result of resistances to sliding, with torsion-bar mountings according to the invention, such transverse movements are effective in small areas only. With suitable dimensioning of the profile, transverse sliding which favours slip-through can be completely prevented.The total capacity for adhesion between the torsion bar and rubber mounting is available for turning the torsion bar and slip-through in the mountings, which causes noise and wear, is prevented.

Ways of carrying the invention into effect will now be more fully described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective longitudinal section through a rubber sleeve comprising three regions having moulded projections of different kinds, Figures 2 and 3 are perspective views illustrating applications of rubber sleeves in mountings on front and rear axles respectively of a motor vehicle, and Figure 4 is a graphic representation of the results of slip-through tests on rubber mountings with moulded projections in accordance with the invention and with a known mounting for comparison.

The rubber sleeve 1 illustrated in Fig. 1 has three types of moulded projections in accordance with the invention. The three types may be used either singly or in combinations of two or three said types in a sleeve. In the region I, there are moulded projections consisting of bosses 2 of truncated pyramidal form, leaving gaps or spaces 3 of approximately equal width, extending around each boss and to the next adjacent boss.

In the region II, there are moulded projections consisting of annular transverse ribs 4 between which are annular gaps or channels 5 of approximately equal width.

In the region Will, there are moulded projections consisting of longitudinal ribs 6 between which are longitudinal gaps or channels 7 of approximately equal width.

When a torsion-bar stabiliser is assembled, the moulded projections, namely the bosses 2, transverse ribs 4 and/or longitudinal ribs 6, are partially pressed into the spaces 3, annular channels 5 and longitudinal channels 7 respectively.

Examples of use of such rubber sleeves shown in Figs. 2 and 3 illustrate mounting or bearing elements to which the sleeves can be applied on front and rear axles of a motor vehicle. On the front axle (Fig. 2), these elements are bearings for transverse links 8 and 9, a transverse-link support 11 and torsion-bar mountings or bearings 1 2. On the rear axle (Fig. 3), for example, oblique-link bearings 1 3 can be designed with such rubber sleeves.

Slip tests with torsion-bar bearings produced results shown basically in Fig. 4, in which torsional moment in Nm is plotted as ordinate and the angle of torsion as abscissa.

The upper curve 14 shows the slip behaviour in the case of a standard series produced torsion-bar mounting used heretofore, whilst the lower curve 1 5 shows the slip behaviour in the case of a mounting with a rubber sleeve in accordance with the invention. It is evident that a mounting in accordance with the invention could increase the critical angle, with reference to the initial condition, at which slip takes place to more than double, given that slip already begins at the limit marked by the arrow 1 6 in the case of the standard mounting.

The relationship shown in Fig. 4 still obtains even in the event of unforseen overloading of such a mounting or bearing.

If required, projections similar to those described above could be provided on the exterior of a rubber sleeve or on both the interior and exterior thereof.

Claims

1. An arrangement for the resilient mounting of a chassis element in a motor vehicle, comprising at least one rubber sleeve, enclosing the said element, which has a circularly cylindrical bore whose internal diameter is larger than the diameter of the said element and is, in turn, enclosed by a holding sleeve having an internal diameter smaller than the external diameter of the rubber sleeve, wherein at least the circularly cylindrical interior of the rubber sleeve has moulded projections which bear, as a result of deformation, on a round outer surface of the said element in such a manner that rubber material is pressed into spaces, between the said projections, in the rubber sleeve.

2. An arrangement according to Claim 1, wherein the moulded projections comprise longitudinal ribs between which there are channels of approximately equal width.

3. An arrangement according to Claim 1 or 2, wherein the moulded projections comprise annular transverse ribs between which there are annular channels of approximately equal width.

4. An arrangement according to Claim 1, 2 or 3, wherein the moulded projections comprise bosses of truncated pyramidal form between which there are spaces, of approximately equal width, extending around each boss and between it and the next boss.

5. An arrangement according to any one of Claims 1 to 4, wherein moulded projections are provided also on the outside of the rubber sleeve.

6. An arrangement according to any one of claims 1 to 5, wherein the said element is the torsion bar, of a torsion-bar stabilizer, resiliently mounted in the rubber sleeve.

7. An arrangement for the resilient mounting of a chassis element in a motor vehicle substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

8. An arrangement according to any one of claims 1 to 7 and incorporated in mountings or bearings for elements of front and/or rear motor-vehicle axles substantially as hereinbefore described with reference to Fig. 2 and/or Fig. 3 of the accompanying drawings.