GB2147254A

GB2147254A - Vehicle wheel suspension linkage

Info

Publication number: GB2147254A
Application number: GB08326330A
Authority: GB
Inventors: Ronald Alan Cook
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1983-09-30
Filing date: 1983-09-30
Publication date: 1985-05-09
Also published as: GB2147254B; GB8326330D0

Abstract

A wheel suspension for a vehicle makes use of a Watt's linkage in which at least one of the links 20,22 supporting a spindle carrier 10 is a leaf spring. Normally both links will be leaf springs. The springs are arranged with their flat faces horizontal to provide rigidity in a horizontal plane, and their presence in the linkage guides vertical movement of the wheel axle in a straight vertical line as in a conventional Watt's linkage and also provides springing to the wheel. <IMAGE>

Description

SPECIFICATION Suspension linkage This invention relates to a wheel suspension linkage, particularly for motor vehicles.

It has been proposed to use a Watt's linkage as a suspension linkage. Such a linkage connected between two members ensures that movement of one member relative to the other occurs in a straight line. In a vehicle suspension, the linkage can be fitted between the vehicle body and a wheel axle so that up and down movement of the wheel is in a straight line. This avoids any tendency for the wheel to steer as it moves on its suspension.

A Watt's linkage has a mounting block which mounts the movable member. In a suspension linkage, the mounting block acts as a spindle carrier.

The linkage also has two links which connect opposite ends of the spindle carrier to points on the other member, on opposite sides of the block.

According to the present invention, there is provided a suspension linkage comprising a Watt's linkage, in which the spindle carrier is adapted to mount a wheel axle, and in which at least one of the supporting links which support the spindle carrier on the vehicle body is formed by a leaf spring, at least one end of which is clamped to either the vehicle body or the spindle carrier.

Preferably both the supporting links are leaf springs clamped at one or both ends, so that they flex as the spindle carrier moves relative to the vehicle body.

The use of a spring or springs in this way enables the suspension linkage to provide the necessary springing for the wheel, and a separate spring can then be dispensed with. Furthermore, the use of a leaf spring, which is stiff in a plane at right angles to the plane in which it flexes, can make it possible also to dispense with any additional means for lateral location of the axle.

The leaf springs will be clamped at one end, but may be pivoted at their other ends. If a rigid link is used as one supporting link, then it will be pivoted at both ends, to the spindle carrier and to the vehicle body.

The springs are preferably made from composite plastics materials such as carbon fibre or glass reinforced resins. These materials have the advantage that they can be formed with a varying thickness along their length, so that only a single leaf is required. Alternatively however, metal leaf springs may be used with multiple leaves where necessary.

It may be advantageous to have supporting links formed by leaf springs of different rates. This can make it possible to vary the springing characteristics for different stages of wheel movement.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a suspension linkage according to the invention; Figure 2 is a schematic illustration of the linkage showing various stages of movement; and Figures 3 to 6 show alternative arrangements for attaching the ends of the spring links.

Figure 1 shows a spindle carrier 10 at the end of an axle 21, and with a centre indicated at 12. A wheel 14 is mounted on a spindle located at the centre 12. The block 10 is supported on fixed parts 16 and 18 of the vehicle body by means of a lower leaf spring link 20 and an upper leaf spring link 22.

Figure 1 shows the suspension under design load. However under differing loads, the leaves 20 and 22 flex to positions such as those shown in Figure 2. Figure 2 shows the design load position, the full jounce position above the design load position and the rebound position below. The centre 12 of the block follows a path 24 as the block moves.

This path deviates marginally from an ideal straight line, but this deviation is considered to be insignificant. The deviation occurs because the distance between the ends of each spring changes slightly as the spring flexes. The block 10 also twists, as can be seen in Figure 2. This twist may be taken up by twisting of the axle 21.

Figure 2 also shows that the two springs deflect to different extents. Following from this, by choosing the characteristic of spring 20 to be different from that of spring 22, the overall spring characteristic of the linkage can be arranged so that a constant spring frequency is obtained over the entire deflection range. To this end, the combined effect of the springs is to give a low spring rate between the rebound and the design load positions and a higher spring rate between the design load and the full jounce positions.

From Figure 1, the arrangement of the springs with their major cross sectional dimension horizontal can be seen. A result of this arrangement is that the linkage shown in Figure 1 provides considerable lateral resistance, effectively preventing movement of the axle in the directions indicated by arrows 26, without any additional restraining being required.

In Figures 1 and 2, the ends of the springs 20 and 22 are shown clamped to the block 10 and to the vehicle body at 16 and 18. This is a simple, and therefore preferred, way of attaching the ends.

However other arrangements as shown in Figures 3, 4, 5 and 6 are also possible. In Figure 3, both springs are pivoted to the vehicle body and clamped to the block 10. In Figure 4, both springs are pivoted to the block 10 but clamped to the vehicle. In Figure 5, a pivoted, rigid link 28 supports the spindle carrier at one side, and the spring 22 on the other side is pivoted to the block and clamped to the vehicle. In Figure 6, the lower spring 20 is clamped at both ends and a rigid link 28 supports the block from the other side and is pivoted at both ends. The variations shown in these Figures are not intended to be exhaustive, and other combinations of mountings are possible.

It is likely to be preferable to have the lower spring leading in the direction of movement of the vehicle, but the opposite arrangement is possible.

Claims

1. A suspension linkage comprising a Watt's linkage, in which the spindle carrier is adapted to mount a wheel axle, and in which at least one of the supporting links which support the spindle carrier on the vehicle body is formed by a leaf spring, at least one end of which is clamped to either the vehicle body or the spindle carrier.

2. A suspension linkage as claimed in Claim 1, wherein both the supporting links are leaf springs.

3. A suspension linkage as claimed in Claim 1 or Claim 2, wherein the leaf springs are clamped at their ends to the spindle carrier and to the vehicle body.

4. A suspension linkage as claimed in Claim 1 or Claim 2, wherein one end of the, or one of the, leaf springs is pivoted to either the spindle carrier or the vehicle body.

5. A suspension linkage as claimed in any preceding claim, wherein the springs are made from composite plastics materials.

6. A suspension linkage as claimed in any one of Claims 2 to 5, wherein the supporting links are formed by leaf springs of different rates.

7. A suspension linkage substantially as herein described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: Claim 1 above has been deleted or textually amended.

New or textually amended claims have been filed as follows:

1. A suspension linkage for a wheel of a vehicle, the linkage comprising a spindle carrier and links generally parallel to the vehicle centre line connecting the carrier to the vehicle body in the manner of a Watt's linkage, at least one of the links being a leaf spring, the or each leaf spring being clamped at at least one of its ends and providing all the springing function required for the wheel, and the linkage controlling locatiion of the spindle carrier in both vertical and horizontal planes.