GB2309948A

GB2309948A - Limiting vehicle roll

Info

Publication number: GB2309948A
Application number: GB9602759A
Authority: GB
Inventors: Michael Anthony Mumford
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-02-10
Filing date: 1996-02-10
Publication date: 1997-08-13
Also published as: GB9602759D0

Abstract

Mechanical anti-roll system for automotive vehicles provides fore/aft torque-resistant roll bars 14,14' connected at their outboard ends to either of the vehicle (front or rear) wheel pairs 12,12'. The inboard ends are connected to the vehicle body by lever arms 18,18' to receive input torque from the body. That torque is resisted at the outboard end of each torque bar by the latter being connected to the relevant wheel pair. The system provides for the inboard ends of the torque bars to be inter connected, for example by a bush 20 or hydraulically, to provide for control of the anti-roll effect. The system offsets the front-end-only operating characteristics of conventional roll bar systems.

Description

DEVICE FOR LIMITING VEHICLE ROLL This invention relates to a system for the reduction of roll angles experienced by vehicles subjected to lateral accelerations such as those arising from cornering forces.

It is known that vehicles, for example motor cars, equipped with sprung suspensions will normally tilt, that is roll, outward when negotiating a corner.

Anti-roll bars are often used to limit the angle of roll. These are torsion bar springs usually mounted transversely on the chassis and connected through lever arms at each end to the axles of each of a transverse pair of vehicle road wheels. This arrangement allows a pair of wheels to move up or down together without inducing torque in the bar. However should the wheels move in opposite directions, such as would be the case when the vehicle rolls during cornering, torque is induced and the consequent reaction through the chassis mounts resists vehicle roll.

There are limitations to this arrangement. If the anti-roll bar is made too stiff in relation to the normal suspension springs the movement of one wheel interferes adversely with the other. Furthermore the sprung roll frequency may become too high and produce unacceptable lateral shake for the vehicle occupants over bumpy road surfaces.

According to the present invention a vehicle chassis is supported by springing means on wheels. A transverse pair of wheels is provided with a torsion bar or tube one end of which is connected to a beam which in turn connects together the axles of the said pair of wheels directly or via linkage locating the wheels relative to the chassis.

The torsion bar or tube is rotationally restrained in its connection to the beam but may have angular freedom. A lever arm pivotally connected to the chassis at one end is fixed to the torsion bar or tube at the opposite end to the beam.

A second transverse pair of wheels is similarly provided with a torsion bar or tube with lever arm and beam.

The ends of both lever arms which are not connected to the chassis are pivotally connected to each other directly or with a fixed or variable length link.

A first embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows in perspective the underneath view of a vehicle having a chassis and two transverse pairs of wheels each pair equipped with a torsion bar, beam and lever arm.

Figure 2 shows a flexible pivotal connection between lever arms.

Referring to the drawing a chassis 10 is supported by springs 11 at each corner on two transverse pairs of wheels 12 and 12'. For clarity the connection of the wheels to the chassis is not shown and may follow any of the conventionally known methods of location.

A torsion bar 14 is connected to a beam 16 by a bracket 17 which restrains the bar 14 rotationally while allowing angular movement. The beam 16 connects a pair of wheels 12 by means of their axles (not shown). The other end of the bar 14 connects rigidly to a lever arm 18. The lever arm 18 is pivotally mounted on the chassis by bracket 19.

A torsion bar 14' is connected to a beam 16' by a bracket 17' which restrains the bar 14' rotationally while allowing angular movement. The beam 16' connects a pair of wheels 12' by means of their axles (not shown). The other end of the bar 14' connects rigidly to a lever arm 18'. The lever arm 18' is pivotally mounted on the chassis by bracket 19'.

The ends of lever arms 18 and 18' are flexibly connected by bush 20 In operation when any transverse pair of wheels rise or fall together no twist is produced in the bar connected to them and the bar has no effect. However if the wheels 12 and 12' on one side of the vehicle move up and those on the other side move down relative to the chassis, as they would if the vehicle were to roll while cornering, a torque is induced in the bars 14 and 14' because while the ends connected to the beams 16 and 16' are caused to rotate the ends connected to the lever arms 18 and 18' are not able to do so as they try to rotate in opposite directions and are prevented from doing so by their common connection 20. The induced torque is reacted through chassis brackets 19 and 19' causing a reduction in the roll angle that would otherwise be experienced by the vehicle.

If a single wheel moves up or down the resulting torque in its associated bar is reacted through the lever arm connection and twists the other bar, thus the torque generated is less than would have been produced for the same wheel movement in roll when both wheels on one side move together.

If diagonally opposite wheels move up or down together rotation of the bars is not resisted by the lever arms as they move in the same direction at their connection.

A second embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 3 shows a variable length link connecting the lever arms together.

This second embodiment of the invention is the same as the first described above with the exception that the connection of the lever arms, with reference to the drawing, is by means of an variable length link 21. The link 21 takes the form of a double acting hydraulic ram extension or retraction of which will generate torque in the bars 14 and 14' The torque so generated will react against the chassis and modify the roll angle experienced by the vehicle when cornering. The length of link 21 may be controlled by any suitable means to achieve the desired modification of vehicle roll angle..

Claims

1 A vehicle comprising : a) a vehicle body having at least two pairs of ground support wheels spaced apart in the travel direction and suspension means supporting said body on said wheels; b) said suspension means comprising vehicle body anti-roll means comprising a torque-resistant element connected between one of said pairs of wheels of said vehicle and said vehicle body, said wheels of said one of said pairs being laterally spaced apart with respect to the travel direction of said vehicle; and c) said torque-resistant element being adapted to resist resiliently torque applied thereto in use by said vehicle body; characterised by d) said anti-roll means having said torque resistant element connected at a first location to said one pair of said wheels so as to be able to resist torque transmitted thereto in use from said vehicle body; and e) said anti-roll means having said torque resistant element extending from said first location generally in the travel direction of said vehicle and being connected to said vehicle body at a second location intermediate said spaced pairs of ground support wheels and so as to resist body roll at said second location between said pairs of wheels.

2 A vehicle comprising a suspension system wherein a body-roll-resisting torque-resistant element extends from a given wheel pair generally in the travel direction of the vehicle and is coupled to the vehicle body and resists body roll at a location offset from said wheel pair in said travel direction.

3 A vehicle according to claim 1 or claim 2 characterised by said torque-resistant element being connected to said vehicle body at a location generally in the region of the centre of gravity of the vehicle.

4 A vehicle according to any one of claims 1 to 3 characterised by said torque-resistant element being connected to said one pair of wheels through a beam axle.

5 A vehicle according to any one of claims 1 to 3 characterised by said torque resistant element being connected to said one pair of wheels through a linkage interconnecting independent suspension linkages of said wheels.

6 A vehicle according to claim 5 characterised by said linkage being adapted to apply torque to said torque-resistant element from either of said wheels.

7 A vehicle according to any one of claims 1 to 3 characterised by said torque-resistant element being adapted to perform a function additional to that of a torque-resistant element.

8 A vehicle according to claim 7 characterised by said additional function of said torque-resistant element comprising acting as a location member for an axle of said vehicle in relation to the chassis thereof.

9 A vehicle according to any one of the preceding claims characterised by said torque-resistant element constituting a first torque-resistant element, and being operatively associated with a first pair of wheels of the vehicle and a second torque-resistant element being provided in relation to a second pair of wheels of the vehicle, and coupling means being provided to couple said first and second torqueresistant elements to the vehicle body so that the degree of roll-resistance provided thereby is determined.

10 A vehicle according to claim 9 characterised by said coupling means comprising control means for controlling the degree of roll resistance provided by said first and second torque-resistant elements.

11 A vehicle according to claim 10 characterised by said coupling means comprising pivoted lever means pivotally interconnecting the adjacent ends of said torque-resistant elements

12 A vehicle according to claim 11 characterised by said lever means being coupled to a thrust device operable to increase the torsion in either or both of said torque-resistant elements.

13 A vehicle according to claim 12 characterised by said thrust device comprising a fluid pressure actuator operable to change said torsional loading in either or both of said torque-resistant elements.

14 A vehicle according to claim 13 characterised by a fluid pressure control system to provide automatic control of said fluid pressure actuator in accordance with sensed dynamic parameters of said vehicle's travel characteristics.

15 A vehicle substantially as described herein with reference to the accompanying drawings.

16 A vehicle comprising an anti-roll suspension system having an elongated torque-resistant resilient element extending generally in the travel direction of the vehicle.

17 A vehicle according to claim 16 characterised by said torque-resistant element being coupled to the vehicle body at a location spaced longitudinally from the pair of vehicle wheels to which the torqueresistant element is coupled.