GB1586068A

GB1586068A - Vehicle suspension

Info

Publication number: GB1586068A
Application number: GB45017/76A
Authority: GB
Original assignee: Dunlop Ltd
Current assignee: Dunlop Ltd
Priority date: 1976-10-29
Filing date: 1976-10-29
Publication date: 1981-03-18
Also published as: FR2369109A1; JPS5355808A; SU818472A3; FR2369109B1; CA1063628A; PL201796A1; DE2748264A1; JPH028938B2; HU187742B; CH619653A5; PL117792B1; IN147947B; SE433928B; SE7711899L; DE2748264C2

Description

(54) VEHICLE SUSPENSION (71) We, DUNLOP LIMITED, a British Company of Dunlop House, Ryder Street, St.

James's, London Ski, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be particularly described in and by the following statement: This invention relates to a vehicle suspension, and in particular, though not exclusively, to a railway vehicle suspension by means of which a railway vehicle body may be supported by one or more bogie units.

In the Specification of U.K. Patent No.

870,814 there is described a railway vehicle suspension arrangement in which the weight of a vehicle body is carried by resilient side bearers interposed directly between the vehicle body and a wheel-carrying frame, e.g. the frame of a two-wheel or four-wheel bogie. The side bearers accommodate vertical movements of the vehicle body relative to the wheel frame, and must also permit a relatively free horizontal movement of the vehicle body relative to the wheel frame to absorb shock loads or accommodate pivotal movement of the wheel frame about a vertical axis such as when negotiating horizontal curves in a track.

The side bearers described in said specification each comprise in combination a pair of spring means one supporting the other, one of said spring means being in the form of a rubber block which acts mainly in compression to carry the supported vehicle body load and accommodate relative horizontal movements between the body and wheel frame mainly by shear deformation, the other spring means permitting the required relative vertical move ment between the body and frame.

In this context and as used hereinafter it is to be understood that the terms "horizontal" and "vertical" are used in relation to a vehicle standing on level ground.

Whilst providing satisfactory operating characteristics the above described suspension does have the disadvantage that, with each side bearer being formed of two spring means, it is relatively expensive to produce and this is particularly relevant in relation to the pre ferred suspension where the side bearers comprise rubber bonded to metal spring means.

Furthermore said suspension lacks the desired degree of compactness.

According to one aspect of the present invention a vehicle suspension comprises a sidebearer interposed between the body of a vehicle and a wheel carrying frame of the vehicle to support the body relative to the wheel carrying frame, the side-bearer comprising a tubular body of elastomeric material positioned in the suspension such that the weight of the vehicle body causes compression of the tubular body in a direction extending between the ends of the tubular body, the tubular body having a waist disposed substantially centrally between the ends of the tubular body and each end portion of the tubular body is of progressively increasing external diameter following a convex path in a direction leading from the waist to the ends whereby both the vertical compression stiffness and horizontal shear stiffness progressively increase with increase in the compression loading.

The inner surface of each end portion of the tubular body may also be of progressively increasing diameter following a convex path in a direction leading from the waist to the end of the body. The thickness of the wall of each end portion of the body may increase progressively in a direction leading from the waist to the end of the body.

The interior of the tubular body may be closed in the waist region to define two chambers positioned one either side of the waist region.

The waist region of the tubular body is preferably reinforced to reduce or eliminate rupture of the body in the region of the waist.

Thus, a place of substantially rigid material may extend across the waist (i.e. transversely of the body) and is either partly or completely embedded in the body to act as reinforcement.

The plate may extend radially outwards of the body, and be profiled to vary in thickness in the radially outwards direction so that outer surfaces of the body contact the plate at a smaller deflection and thereby modify the deflection characteristics. Alternatively, or additionally, a reinforcement piece may extend axially of the tubular body. The axial reinforcement may be a rod or a tube and may be partly or completely embedded in the tubular body. The axial reinforcement may, for instance, extend through from the hollow interior of one end portion to the other end portion, the ends of the axial reinforcement being exposed, and thereby define at least in part a fluid passage extending through the waist region to the end portions either side of the waist region.

The plate and/or the rod or tube reinforcement are preferably of metal and may be integral if both are provided. The reinforcements are preferably bonded to the tubular body.

Rigid plates may be bonded to the ends of the tubular body to assist in attachment of the side bearer to a vehicle body and wheelcarrying frame, and the plates may extend wholly across the ends of the body to form one or two closed chambers within the body or be apertured to permit venting of air from inside the body during change in length of the body under dynamic operating conditions.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is an end view of a part of a railway vehicle according to the present invention and showing a pair of side-bearers according to the invention; Figure 2 is a longitudinal sectional view of the side-bearer shown in Figure 1; Figure 3 is an end view of the side-bearer shown in Figures 1 and 2; Figure 4 is similar to that of Figure 3 showing the side-bearer loaded in compression; Figure 5 is similar to that of Figure 3 showing the side-bearer loaded in compression and shear; Figure 6 is a graph showing the compression/deflection characteristic of the sidebearer shown in Figures 1-3, and Figure 7 is a graph showing the shear stiffness/deflection characteristic for the sidebearer shown in Figures 1-3.

Referring to Figure 1 a railway vehicle comprises a body 10 and a wheel-carrying bogie frame 11 provided with sole-bars 12 and a transom 13. The vehicle body is connected to the bogie by a pin 14 and longitudinal link 15 in known manner so that tractive and braking forces are applied to the body while permitting relative vertical, horizontal, and pivotal movements between the bogie 11 and vehicle body 10. Such movements occur when the vehicle is negotiating a horizontal curve.

Instead of link 15, a number of alternative devices may be used including mountings with a number of intermediate plate, parallel motion devices, and toggle links to give a progressive rise in transverse stiffness with increasing deflection.

To interconnect the vehicle body and bogie resiliently a pair of side-bearers 16 are interposed therebetween. The side-bearers are provided one each side of the vehicle and attached to the bogie in the region of the junc tion of the transom 13 with the solebars 12.

Each side-bearer 16 is constructed as illustrated in detail in Figures 2 and 3 and comprises a tubular rubber body 20 com prising two integral end portions 21 arranged back-to-back to define a central waist 24.

The inner and outer surfaces 22 and 28 res pectively of each portion 21 are of progress ively increasing diameter following convex paths in a direction leading from the waist 24 to the end 25 of the body. The rate of increase in diameter of the outer surface 28 exceeds that of the inner surface 22 so that the wall thickness of each end portion 21 also pro gressively increases in a direction leading from the waist 24 to the end 25 of the body.

A metal plate 26 is embedded in the waist region 24 and extends radially outwardly of the body 20 to provide a rigid barrier for contact by the outer surface 28 of each end portion 21 during compression of the side bearer. The end portions 21 are secured to the plate 26 by bonding. The cavities 29 are vented to atmosphere. In this particular em bodiment the diameter (d) of the waist 24 is slightly less than one-half of the maximum diameter D of the ends 25 of the body.

The ends 25 of the body (which are annular) are bonded to end plates 27 for attachment to the vehicle body and bogie, and the side-bearer is loaded axially of the tubular body (in the direction of arrows P) to compress the body between the plates 27.

With this arrangement the outer surface 28 of each end portion rolls against the plate 26 as the load increases.

It is preferred that the length L and max imum diameter D of the tubular body are about equal and for loads of a railway vehicle suspension the diameter D is typically in the order of 400 mm.

Use of this side-bearer design in the bogie suspension affords a large deflection for a relatively small side-bearer diameter - indeed the end portions 21 may be deformed until they are in the shape of flat discs and there thus results a compact suspension. Figure 4 shows the side-bearer profile partially loaded in compression without deforming the end portions 21 to a substantially flat disc shape, and Figure 5 shows the profile when the side-bearer is under shear load in conjunction with said partial compression loading.

In addition to large vertical deflection use of this side-bearer design is found also to allow adequate horizontal flexibility and over the normal operating range the shear stiffness increases with compressive load. Furthermore the rising vertical spring rate of the sidebearer gives a substantially constant vertical natural frequency over a wide range of loadings and thus the resulting vehicle suspension characteristic is of substantially constant periodicity and not unduly dependent on the load being carried by the vehicle. Figures 6 and 7 respectively show the compression load-deflections and shear stiffness - compression deflection characteristics of the sidebearer.

A particularly significant feature which has unexpectedly been found to be achieved by the use of a waisted tubular body for the sidebearer is that unlike conventional rubber springs, compression of the bearer increases not only the vertical or axial stiffness of the bearer but also the horizontal or transverse stiffness. In consequence the resulting vehicle suspension exhibits good horizontal stability even when subject to a relatively high degree of vertical loading.

The side-bearer comprises relatively few metal components in comparison to a conventional interleaved rubber-bonded to metal type side-bearer and thus is comparatively economical to manufacture.

In Figure 1 the side-bearers 16 have been shown mounted vertically but in alternative constructions the side-bearers may be mounted inclined relative to the vertical.

WHAT WE CLAIM IS: 1. A vehicle suspension comprising a sidebearer interposed between the body of a vehicle and a wheel carrying frame of the vehicle to support the body relative to the wheel carrying frame, the side-bearer comprising a tubular body of elastomeric material positioned in the suspension such that the weight of the vehicle body causes compression of the tubular body in a direction extending between the ends of the tubular body, the tubular body having a waist disposed substantially centrally between the ends of the tubular body and each end portion of the tubular body is of progressively increasing external diameter following a convex path in a direction leading from the waist to the ends whereby both the vertical compression stiffness and horizontal shear stiffness progressively increase with increase in the compression loading.

2. A vehicle suspension according to Claim 1 wherein the inner surface of each end portion is of progressively increasing diameter following a convex path in a direction leading from the waist to the end of the body.

3. A vehicle suspension according to Claim 1 or Claim 2 wherein the thickness of the wall of each end portion progressively increases in a direction leading from the waist to the end of the body.

4. A vehicle suspension according to any one of the preceding Claims wherein a reinforcement is embedded in the waist region of the body.

5. A vehicle suspension according to Claim 4 wherein a plate of substantially rigid material is provided in the waist region to act as a reinforcement.

6. A vehicle suspension according to Claim 5 wherein the plate extends radially outwards of the tubular body and is profiled to vary in thickness at positions radially outwards of the tubular body.

7. A vehicle suspension according to any one of Claims 4 to 6 wherein the waist region of the tubular body is provided with a reinforcement member extending axially of the tubular body.

8. A vehicle suspension according to Claim 7 wherein the axially extending reinforcement defines at least in part a fluid passage extending through the waist region.

9. A vehicle suspension according to any one of Claims 1 to 7 wherein the interior of the tubular body is closed in the waist region to define two chambers positioned one either side of the waist region.

10. A vehicle suspension according to any one of the preceding Claims wherein a rigid plate is bonded to an end of the tubular body to assist in attachment of the side bearer to a vehicle body or wheel-carrying frame.

11. A vehicle suspension according to any one of the preceding Claims wherein the vertical natural frequency of the suspension is substantially constant over the normal range of suspension loadings.

12. A vehicle suspension constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

13. A vehicle incorporating a vehicle suspension according to any one of the preced

Claims

ing Claims.