GB2306411A - Suspension system for a steerable wheel of a vehicle - Google Patents

Abstract

The vehicle suspension comprises a suspension member 14 pivotally connected at its inner end to a body 16 of the vehicle 10 with a ground engageable wheel 12 carried by a wheel mounting 13 pivotally mounted at its other end. A resilient strut 18 incorporating a damper 20 is arranged between the wheel mounting 13 and the body 16 for controlling movement of the suspension member 14. A link 28 connects an anti-roll bar 30 with the strut 18 such that, during cornering, a transverse force Pr applied to the strut 18 during cornering will be opposed by a transverse force Tr applied to the strut by the anti-roll member 30 along the link 28 to the strut 18. This will reduce the drag that can be created within the strut 18 caused by side loading, and therefore help alleviate a certain amount of harshness created in vehicle ride when cornering.

Description

A VEHICLE SUSPENSION The invention relates to a vehicle suspension and is particularly concerned with a suspension which includes a resilient suspension strut.

A known type of suspension strut comprises a telescopic spring unit which provides an upwardly extending link in the suspension. It is known that cornering of the vehicle creates side loading on the suspension strut. Such side loading can create drag within the suspension strut thereby creating a certain amount of harshness in vehicle ride when cornering.

An object of the present invention is to provide a suspension which will help to alleviate the foregoing problem.

According to one aspect of the invention there is provided a vehicle suspension system comprising supporting means for attachment to a body of the vehicle and on which a ground engageable wheel can be mounted, a resilient strut having an upper part for attachment to the vehicle body and a lower part connected to the supporting means, said upper and lower parts being movable relative to each other to allow movement of the supporting means relative to the body, and an anti-roll member which is connected to said lower part via a linking part which is, in use, angled to the vertical such that a transverse force applied to the strut by the wheel during cornering will be opposed by a transverse force applied through the linking part to the strut by the anti-roll member.

Preferably said linking part comprises a link pivotably mounted at its ends to the anti-roll member and said lower part respectively.

Preferably the supporting means includes a wheel mounting member on which a wheel can be mounted and a suspension member, the mounting member being connected to said lower part at a connection point and pivotably connected to the suspension member at a pivoting point which is, in use, lower than said connection point.

Preferably the linking part is connected to the antiroll member at its lower end and said lower part at ;ts upper end, and its upper end is outboard of its lower end.

The opposing transverse force applied by the anti-roll member helps to reduce the drag within the strut, The strut may incorporate a damper comprising a piston slidable within a body of the damper. In such a case, the opposing transverse force helps to reduce the drag of the damper piston on the body during cornering. Loading on the strut due to cornering will increase with cornering speed.

However, with increased cornering speed, there is an increased tendency for the body to roll and, therefore, an increased opposing force will be applied by the anti-roll member.

Preferably, the strut has a body connected to one of the suspension member and vehicle body and has a slidable member such as a piston connected, in use, to the other of the suspension member and vehicle body and the body is arranged to be acted upon by the force applied by the antiroll member.

In a preferred embodiment, the suspension member is connected to a wheel mounting by a first pivot, the wheel mounting is connected to the strut, the strut is connected to the vehicle body by a second pivot spaced upwardly from the first pivot and an axis passing through the first and second pivots provides an axis of steering for the wheel, the force applied by the anti-roll member having a component arranged to act on the strut in a direction transverse to the axis of steering.

The strut may be arranged to be acted upon by the force from the anti-roll member along a line of action which lies at an acute angle to the longitudinal axis of the strut which may define the aforesaid axis of steering.

One end of the anti-roll member may be connected, in use, to the strut by means of a link. The use of a simple link is useful from the point of view of packaging.

Preferably, the suspension member is part of a front suspension for a vehicle.

According to another aspect of -he invent ion, there is provided a vehicle having suspension according to the first aspect of the invention.

A vehicle suspension in accordance with the invention will now be described by way of example with reference to the accompanying drawing which is a diagrammatic view looking rearwardly of a vehicle and showing part of a front suspension of the vehicle.

A vehicle 10 has front and rear ground engageable wheels, the left hand front wheel 12 being shown, viewed from behind, in the drawing. The wheel 12 is carried by a wheel mounting 13 mounted on a pivot 15 at one end cf a suspension arm 14, the wheel mounting 13 and the suspension arm 14 together serving to support the wheel in the desired position relative to the vehicle body 16. The suspension arm 14 is pivotally connected at its inner end to a body 15 of the vehicle 10. A MacPherson strut 18 is arranged between the wheel mounting 13 and the body 16 and comprises a damper 20 having a lower part in the form of a body 22 and an upper part in the form of a piston rod 24. A helical compression spring 25 extends around the piston rod 24 in known manner to control relative movement of the two parts 22, 24.The damper body 22 is rigidly connected to the wheel mounting 13 and the piston rod 24 is connected to the body 16 by means of a pivot 26 arranged at the upper end of the piston rod 24 as viewed in the drawing. An axis A passing through the pivots i5, 26 defines an inclined axis of steering for the wheel 12. A suitable steering mechanism (not shown) is provided on the vehicle.

The damper body 22 is connected via a pivot 27 to the upper end of a link 28. The lower end of the link 28 is connected via a pivot 29 to one end of an anti-roll bar 30 of known kind on the vehicle 10. The other end of the anti-roll bar is connected to a link 28 of a suspension arrangement on the right hand side of the vehicle which is a mirror image of that shown in the drawing. It will be noted that the link 28 is arranged at an angle t to the axis of steering A. It is also at an angle to the vertical, its upper end being outboard of its lower end.

When cornering around a right hand bend, a frictional force Fr is acts on the contact patch 32 of the wheel 12 which tends to tip the wheel 12 anti-clockwise about the pivot 15, as seen in Figure 1, thereby creating a force Pr on the damper 20. However, cornering will also induce body roll in the direction Rr which will cause the anti-roll bar 30 to apply a downward force through the link 28 along a line of action L passing through the centres of pivots 27, 29 at angle t to the axis A. The downward force will have a transverse component Tr which acts in opposition to the force Pr.

When cornering around a left hand bend, a frictional force Fl acts on the contact patch 32 of the wheel and tends to rotate the wheel 12 in a clockwise direction, as seen in Figure 1, about the pivot 15 thereby effectively creating a force Pl on the damper 20. However, the cornering also causes the body 16 to roll in direction Rl thereby causing the anti-roll bar 30 to apply an upward force on the strut 28 along the line of action L. The upward force has a transverse component T1 which opposes the force P1.

Increased cornering speed will increase the forces Fr, Fl but will also increase the roll indicated by arrows Rr, Rl. Therefore, whilst the forces Pr and P1 will increase with cornering speed, the forces Tr and T1 will also be increased as a result of increasing roll forces.

It will be appreciated that the angle of the link 28, the stiffness of the anti-roll bar, and the relative dimensions and positions of the other parts of the suspension system, are preferably all tuned and arranged such that the forces Tr and T1 produced by the anti-roll bar are substantially equal to the forces Pr and Pl, thereby substantially eliminating drag induced in the strut due to cornering. However, even if this is not possible, the system can be designed such that the amount of drag during cornering Is significantly reduced.

Claims (9)

1. A vehicle suspension system comprising supporting means for attachment to a body of the vehicle and on which a ground engageable wheel can be mounted, a resilient strut having an upper part for attachment to the vehicle body and a lower part connected to the supporting means, said upper and lower parts being movable relative to each other to allow movement of the supporting means relative to the body, and an anti-roll member which is connected to said lower part via a linking part which is, in use, angled to the vertical such that a transverse force applied to the strut by the wheel during cornering will be opposed by a transverse force applied through the linking part to the strut by the anti-roll member.

2. A suspension system according to claim 1 wherein said linking part comprises a link pivotably mounted at its ends to the anti-roll member and said lower part respectively.

3. A system according to claim 1 or claim 2 wherein the supporting means includes a wheel mounting member on which a wheel can be mounted and a suspension member, the mounting member being connected to said lower part at a connection point and pivotably connected to the suspension member at a pivoting point which is, in use, lower than said connection point.

4. A system according to any foregoing claim wherein the linking part is connected to the anti-roll member at its lower end and said lower part at its upper end, and its upper end is outboard of its lower end.

5. A system according to any foregoing claim in which said upper and lower parts comprise a body connected to one of the supporting means and vehicle body and a slidable member connected, in use, to the other of the supporting means and vehicle body and the body is arranged to be acted upon by the force applied by the anti-roll member.

6. A system according to any foregoing claim in which the strut is elongate and is arranged to be acted upon by the force applied by the anti-roll member along a line of act ion which lies at an acute angle to the longitudinal axis of the strut.

7. A system according to any preceding claim in which the supporting means is part of a front suspension for the vehicle.

8. A vehicle suspension system constructed and arranged substantially as described herein with reference to the accompanying drawings.

9. A vehicle having a suspension according to any preceding claim.