WO1988001947A1

WO1988001947A1 - Vehicle suspension

Info

Publication number: WO1988001947A1
Application number: PCT/GB1987/000638
Authority: WO
Inventors: Adrian Tucker-Peake; Stephen Paul Rawlings
Original assignee: Gkn Technology Limited
Priority date: 1986-09-16
Filing date: 1987-09-14
Publication date: 1988-03-24
Also published as: GB8622291D0; GB2195588A; ES2005331A6; GB8721438D0; GB2195588B

Abstract

A vehicle suspension comprising a Watt's linkage at each side of the vehicle, each comprising first and second links (10, 12) extending forwardly and rearwardly from a carrier member (11), wherein corresponding links are provided by limbs (18) of a generally U-shaped member further comprising a torsionally resilient body (20) extending transversely of the vehicle and pivotally supported in bearing means (21, 22) relative to the vehicle structure. In addition to acting as links, the U-shaped member (18, 19, 20) acts as an anti-roll bar to resist roll of the vehicle.

Description

VEHICLE SUSPENSION

This invention relates to a vehicle suspension comprising, at each side of the vehicle, an arrangement of the type generally known as a Watt's linkage. Each such Watt's linkage comprises a generally upwardly extending wheel carrier member supporting an associated road wheel for rotation about a wheel axis, a first link extending forwardly of the vehicle from a part of the wheel carrier member either above or below the wheel axis and connected to the vehicle structure at a position spaced from the wheel carrier member, and a second link extending rearwardly of the vehicle from a part of the ' wheel carrier member below or above the wheel axis, opposite the first part thereof, and connected to the vehicle structure at a position spaced from the wheel carrier member.

In such a suspension, each of the Watt's linkages constrains its associated wheel to a precisely determined path of movement relative to the structure of the vehicle. In particular, such a path may be linear, which is a path not otherwise obtainable if the wheel is carried by a single pivoted arm or link. It has been proposed in GB-2149254A that at least one of the links of each Watt's linkage may be in the form of a leaf spring connected to the vehicle structure, e.g. to extend as a cantilever therefrom, to provide springing for the vehicle without requiring additional springs to be provided. Even in such an arrangement, however, the Watt's linkages on each side of the vehicle are independent of one another even though the wheel carrier members may be connected by an axle beam extending transversely of the vehicle.

In particular, there is no means for resisting roll of the vehicle. Excessive vehicle roll due to lateral forces during cornering is undesirable, and accordingly many suspensions incorporate means for resisting such roll. The most usual provision is that of the well known anti-roll bar, but to add one of these to the suspension increases the complexity thereof, the space occupied (to the detriment of passenger and/or luggage accommodation in the vehicle) and cost. It is a particular object of the present invention to overcome these problems.

According to the present invention, we provide a vehicle suspension comprising, at each side of the vehicle, a generally upwardly extending wheel carrier member supporting an associated road wheel for rotation about an_.axis; a first link extending forwardly of the vehicle from a part of the wheel carrier member above or below the wheel axis and connected to the vehicle structure at a position spaced from the wheel carrier member; and a second link extending rearwardly of the vehicle from a part of the wheel carrier member below or above the wheel axis opposite the first said part thereof and connected to the vehicle structure at a position spaced from the wheel carrier member; wherein corresponding ones of said first and second links on both sides of the vehicle have their end portions remote from the wheel carrier members connected by a torsionally resilient member extending transversely of the vehicle.

By corresponding links, we mean both the forwardly extending links, or both the rearwardly extending links. of the two Watt's linkages.

In a suspension according to the invention, the connection of the end portions of the corresponding links of the Watt's linkages on both sides of the vehicle by a torsionally resilient member extending transversely of the vehicle, provides the effect of an anti-roll bar. Attempted roll of the vehicle causes the transverse member to become deflected in torsion, so that roll is resisted to an extent according to the torsional stiffness of the member.

The principal advantage of the invention is that it is not necessary to provide a separate anti-roll bar and the associated bushes, mountings and the like which such provision would necessarily entail. Very little extra space is taken up.

Whilst i-t would be possible for the transversely extending torsionally resilient member to be a separate part from the corresponding links it connects, preferably there is provided a generally U-shaped member comprising limbs constituting the corresponding links of the Watt's linkages, joined by a body part constituting the transversely extending torsionally resilient member, the body part being pivotally connected to the vehicle structure by suitable bearing means.

Springing in the suspension may be provided by separate springs, e.g. coil or leaf springs, acting on the wheel carrier members or the links of the Watt's linkages. However, it is convenient if the other corresponding links of the Watt's linkages comprise leaf springs, connected between the wheel carrier members and the vehicle structure in such a way as to provide springing for the vehicle.

The wheel carrier members may be connected by an axle beam extending transversely of the vehicle.

The invention will now be described by way of example with reference to the accompanying drawings, of which:-

Figure 1 is a diagrammatic side elevation of part of a motor vehicle having a suspension according to the invention;

Figure 2 is a diagrammatic perspective view of a suspension according to the invention.

The illustrated suspension comprises, at each side of the vehicle, a Watt's linkage constituted by a first link 10, a generally upwardly extending wheel carrier member 11, and a second link 12. The wheel carrier member 11 supports, by suitable bearings for rotation about an axis 13, a wheel 14. Links 10, 12 are pivotally connected to the member 11 approximately eguidistantly above and beneath the axis 13, such pivotal connections providing for relative movement about respective axes parallel to axis 13.

Each first link 10 is constituted by part of a leaf spring which is connected to the vehicle structure (to a chassis part, or part of an an integral body/chassis structure of the vehicle) to extend, lengthwise of the vehicle, as a cantilever. In the drawings, each leaf spring 15, which preferably is of compos.ite, fibre- reinforced plastics, material, is connected at a position 16 approximately midway alorig the leaf to the vehicle structure, and extends rearwardly therefrom to the associated wheel carrier member 11. By way of example, such connection 16 may be disclosed in our international patent application publication no. WO86/02886, to provide limited pivotal movement about an axis extending transversely of the vehicle. At its free end forwardly of position 16, each spring 15 is supported by the vehicle structure by an abutment 17. Such support is in the sill region of the vehicle structure. The spring thus resists upward movement of the wheel carrier member 11 relative to the vehicle structure. As an alternative arrangement to that illustrated, the spring may be rigidly connected to the wheel carrier member 11 and pivoted or rigidly connected to the vehicle structure.

The leaf springs 15 constituting the first links 10 are sufficiently broad and stiff and are appropriately secured to the vehicle and to the carrier members 11 to locate the axle beam (referred to below) laterally of the vehicle.

The second links of the respective Watts linkages are provided by substantially parallel, forwardly extending limbs 18 of a generally U-shaped member further comprising a torsionally resilient body part 20 extending transversely of the vehicle between the limbs 18 and supported to the vehicle structure by bearings 21, 22. The generally U-shaped member 18, 20 acts as an anti-roll bar in addition to providing the links of the Watts linkages, roll of the vehicle being resisted by the torsional stiffness of the body part 20.

As shown in Figure 2 of the drawings, the wheel carrier members 11 are interconnected by an axle beam 23 extending transversely of the vehicle. It will be noted that beam 23 lies beneath the axis 13, to reduce to a minimum its encroachment on the space which, in a typical passenger car where the suspension is used for the rear wheels thereof, is occupied by the rear seats and/or luggage compartment of the vehicle. Hub members 19 for the wheels 14 are shown on the carriers 11.

Although in the example above described it is the rearwardly extending links 12 of the Watt's linkages which are connected, it could alternatively be the forwardly extending links 10 which have their ends remote from the wheel carrier members connected by a transverse torsionally resilient member. Preferably, such connection is established by the provision of an integral U-shaped member as the member 18, 20. In this case, the rearwardly extending links 12 could be provided by leaf springs in order to spring the vehicle.

As an alternative to the use of leaf springs constituting links of the Watt's linkages, springing may be provided by separate springs, e.g. coil or leaf springs. Dampers may be provided as appropriate. In any event, the invention resists vehicle roll without requiring the provision of separate anti-roll apparatus.

As above described, the invention is applied to non-driven wheels, but it is equally applicable to driven wheels of a vehicle.

Claims

1. A vehicle suspension comprising, at each side of the vehicle, a generally upwardly extending wheel carrier member (11) supporting an associated road wheel (14) for rotation about an axis; a first link (10) extending forwardly of the vehicle from a part of the wheel carrier member above or below the wheel axis and connected to the vehicle structure at a position spaced from the wheel carrier member; and a second link (12) extending rearwardly of the vehicle from a part of the wheel carrier member below or above the wheel axis opposite the first said part thereof and connected to the vehicle structure at a position spaced from the wheel carrier member; wherein corresponding ones (12) of said first and second links on both sides of the vehicle have their end portions remote from the wheel carrier members (11) connected by a torsionally resilient member (20) extending transversely of the vehicle.

2. A vehicle suspension according to Claim 1 wherein there is provided a generally U-shaped member comprising limbs (18) constituting said corresponding links, joined by a body part (20) constituting said torsionally resilient member, said body part being pivotally connected to the vehicle structure by bearing means (21, 22).

3. A vehicle suspension according to Claim 1 or Claim 2 wherein the other corresponding links comprise leaf springs (15) , connected between the wheel carrier members, and the vehicle structure to provide springing for the vehicle.

4. A vehicle suspension according to Claim 3 wherein each of the leaf springs (15) is pivotally supported, between its ends (at 16) , relative to the vehicle structure, and is further supported by an abutment (17) .

5. A vehicle suspension according to any one of the preceding claims wherein the wheel carrier members (11) are connected by an axle beam (23) extending transversely of the vehicle.