GB2240307A

GB2240307A - A leaf spring vehicle suspension

Info

Publication number: GB2240307A
Application number: GB9002066A
Authority: GB
Inventors: Lester Thomas Wilcox
Original assignee: GKN Technology Ltd
Current assignee: GKN Technology Ltd
Priority date: 1990-01-30
Filing date: 1990-01-30
Publication date: 1991-07-31
Also published as: GB9002066D0

Abstract

An arm (10) pivoted to the vehicle structure for carrying a road wheel is sprung by a leaf spring (14) extending lengthwise of the arm, the spring being pivoted between its ends to the vehicle structure and the pivot axes (12, 21) of the arm and spring being arranged so that the spring end bearing on the arm moves through an arc centered on the pivot axis (12) of the arm. <IMAGE>

Description

VEHICLE SUSPENSION This invention relates to a vehicle suspension, comprising an arm pivoted to the vehicle structure and adapted to carry a road wheel, and a leaf spring extending generally lengthwise of the arm, the spring having its respective ends engaging the arm and the vehicle structure and being pivotally supported by the vehicle structure at a position between its ends, so that pivoting of the arm causes bending of the spring.

An example of such a suspension is disclosed in EP-202964A. In that suspension, the pivotal support of the spring between its ends is provided by a strap arrangement, with a pivotal axis which is the same as that of the arm. The one end of the spring bears on an elastomeric pad within the arm which is hollow, while the other end of the spring is connected to the vehicle structure by means of a shackle.

It will be appreciated that when the spring bends, which it does along its whole length by virtue of its pivotal support between its ends, the straight-line distance between the ends of the spring changes. The result is that the end of the spring bearing on the elastomeric pad within the arm moves through an approximately arcuate path whose centre of curvature does not coincide with the pivotal support of the spring and arm. The arc through which the spring end moves has a radius of curvature which is actually somewhat shorter than the distance from the spring end to the pivotal support of the spring. The result of this is that a significant relative movement has to be accommodated at the elastomeric pad by which the spring bears on the arm, leading to friction and thus to wear.

It is the object of the present invention to overcome this disadvantage.

Accordingly, the invention provides that in a suspension of the kind first above set forth, the pivotal axis of the arm is so disposed that the centre of curvature of the substantially arcuate path about which the associated end of the spring moves lies on or substantially on such axis.

Thus the relative movement that occurs between the arm and associated end of the spring is greatly reduced, with a reduction of the above referred to disadvantageous consequences thereof.

The invention will now be described by way of example with reference to the accompanying drawing, which shows diagrammatically a suspension according to the invention.

The illustrated suspension comprises an arm 10 which at its one end 11 is adapted, in a manner not shown, to carry a road wheel and at its other end is connected to the vehicle structure, not shown, for pivoting about an axis 12. The arm 10 is hollow.

A leaf spring 14, of composite (fibre-reinforced plastics) material extends into the hollow arm 10 from its end adjacent the pivot axis 12. Within the arm, the one end portion 15 of the spring bears on an elastomeric pad 16 within the arm 10. The other end, 17, of the spring bears on a pad 18 supported by a part of the vehicle structure indicated diagrammatically at 19.

Between its two ends 15, 17, the spring is pivotally supported by a strap arrangement 20 which is carried by the vehicle structure for pivoting about an axis 21.

When the spring is caused to bend as the arm 10 pivots, the straight-line distance between its two ends 15, 17 changes. Therefore the end 15 of the spring moves through a substantially arcuate path, indicated at 22, whose radius of curvature R is somewhat less than the distance between the end 15 of the spring and the pivot axis 21. The positions of the spring under the conditions of maximum jounce and rebound respectively are indicated in broken lines at 23, 24.

According to the invention, the pivot axis 12 of the arm 10 is arranged substantially to coincide with the centre of curvature of the path 22 of movement of the spring end portion 15. Therefore the relative movement between the spring end portion 15 and arm 10, which has to be accommodated by elastomeric pad 16, is much reduced compared to that which would have to be accommodated if the arm were pivoted about the axis 21.

Claims

1. A vehicle suspension comprising an arm pivoted to the vehicle structure and adapted to carry a road wheel, and a leaf spring extending generally lengthwise of the arm; the spring having respective ends engaging the arm and the vehicle structure and being pivotally supported by the vehicle structure at a position between its ends so that pivoting of the arm causes bending of the spring; the pivotal axis of the arm being so disposed that the centre of curvature of the substantially arcuate path about which the associated end of the spring moves lies on or substantially on such axis.

2. A vehicle suspension substantially as hereinbefore described with reference to the accompanying drawing.