GB2069947A

GB2069947A - Vehicle-wheel suspension

Info

Publication number: GB2069947A
Application number: GB8103361A
Authority: GB
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1980-02-16
Filing date: 1981-02-04
Publication date: 1981-09-03
Also published as: FR2475995A1; JPS56128207A; DE3005916A1

Abstract

In a vehicle-wheel suspension in which the wheel carrier 16 is guided by two members 14, 12 located one above the other and is abutted by means of a shock-absorber leg 13 which is extendable and contractable telescopically under the action of wheel-springing means 24, the leg is pivotably connected to the lower said member 12 which is pivotably connected to the vehicle superstructure, the upper said member 14 being pivotably connected to the leg. The leg is preferably non- rotatable about its longitudinal axis. The axis of the wheel-springing means 24, which surrounds the said leg and is abutted downwardly thereon, may extend obliquely downwardly and outwardly at an acute angle in relation to the axis of the leg. Moments arising from forces from the wheel and the springing means may be arranged to be substantially opposite and equal. <IMAGE>

Description

SPECIFICATION Vehicle-wheel suspension The invention relates to a vehicle-wheel suspension, particularly but not exclusively for a steerable motor-vehicle front wheel, of the kind, hereinafter referred to as the aforesaid kind, in which a wheel carrier is guided by two members, particularly transverse or inclined guide arms, located one above the other and is abutted, mainly in a vertical direction, by means of a shockabsorber leg which is pivotably connected to one said member and is extendable and contractable telescopically under the action of wheel-springing means.

Wheel suspensions are known in which the wheel carrier is guided, on the one hand, by means of a transverse guide member and, on the other hand, by means of a shock-absorber leg which is fixedly connected directly to the wheel carrier and whose movement corresponds to that of the wheel. However, a design of this kind is not well suited to large vehicles.

Wheel suspensions of the aforesaid kind have also been developed in which wheel-guiding members, pivotally connected directly to the vehicle frame, are widely spaced from each other because the upper member is located comparatively high. The forces transmitted from the wheel to the frame can then be kept correspondingly small. However, disadvantages of this design are the large space required, heavy weight, longitudinal bearers weakened by the disposition and abutment of the wheel springing means, an unfavourable forwardly projecting structure for the pivotable connection of the upper guiding member, and relatively difficult axle assembly.

An object of the present invention is to provide a wheel suspension of the aforesaid kind which is distinguished by compactness, low weight, ease of assembly and, consequently, by advantages in terms of cost. A further aim is to achieve advantageous conditions with respect to the forces involved.

According to the invention in a suspension of the aforesaid kind, the shock-absorber leg is pivotably connected to the lower wheel-guiding member which is pivotably connected, directly or indirectly, to the vehicle superstructure, and the upper wheel-guiding member is pivotably connected to the said leg.

Advantageousiy, the shock-absorber leg is pivotably connected and/or abutted, preferably in relation to the upper-wheel guiding member, in such a manner as to be non-rotatable about its longitudinal axis.

By the pivotable connection of the said upper member to the shock-absorber leg, relatively simple construction and ease of assembly can be achieved together with small space requirements and a short wheel carrier or steering knuckle.

Special forwardly projecting structures on the frame or vehicle superstructure are not required for the pivotable connection of the upper wheel guiding member. Also wheel-springing means separate from the shock-absorber leg, can be disposed, in structurally favourable manner, surrounding the said leg. It is particularly advantageous if the shock-absorber leg participates in the up and down movement of the sprung wheel but with a movement ratio, namely with a smaller movement. This may also contribute to compactness.

An important further advantage is that a non jamming shock-absorber leg can be obtained in simple and effective manner by balancing the turning moments which act upon the said leg.

One embodiment of the invention by way of example will now be more fully described with reference to the accompanying drawing which shows a vehicle-wheel suspension in front elevation, partially in section.

The wheel 11 is guided, in a substantially perpendicular direction, on a motor-vehicle superstructure or frame 10 by means of a lower guide member or radius arm 12, a telescopic shock-absorber leg 1 3 and an upper guide member or radius arm 14. The lower arm 12 is pivotably connected directly to the frame 10 by a joint 15, preferably with interposed rubber, and is connected to the steering knuckle or wheel carrier 1 6 by a ball-and-socket joint 1 7. The upper arm 14 is pivotably connected by a ball-and-socket joint 1 8 to the wheel carrier 1 6 and, at its end towards the vertical longitudinal centre plane of the vehicle, to the leg 13 by a joint 19 in such a manner as to be non-rotatabie about the axis dof the said leg.The leg 13 is abutted by a joint 20, on the lower arm 12 in such a manner as to be nonrotatable about the axis d.

The leg 1 3 consists, in conventional fashion, of a shock-absorber cylinder 21 and a piston 22 slidable longitudinally therein and abutted at its upper end against the superstructure or frame 10 by way of rubber buffers 23. A helical spring 24 which serves as the vehicle-wheel springing surrounds the upper part of the leg 13. Its spring axis fis directed obliquely in relation to the axis d of the leg 13 by an acute angle bx, so that it extends outside the joint 20 at a distance a. The lower end of the spring 24 is abutted against the superstructure or frame 10 by way of an abutment 25 which is fixed, above the joint 19, to the cylinder 21 of the shock-absorber leg 1 3. At its upper end, the spring is abutted against the superstructure or frame 10 by way of an abutment 26 which serves also to accommodate the buffers 23 for the leg 13.On upward sprung movement of the wheel 11 , the leg 13 is contracted and, on downward movement of the wheel, the leg is extended. By means not shown, the wheel 11 can also be steered about the steering, or carnber, axis s which is defined by the centres of the joints 17 and 1 8 and advantageously intersects the vehicle base at the point of road contact A.

The wheel load R produces on the shockabsorber leg 13 in the joint 19 a force S which produces, about the joint 20, a turning moment S.b, on the leg, where b is the distance between the centres of the joints 1 9, 20 at right angles to the arm between those centres. The spring force F which arises at the same time applies a moment F.a about the joint 20 in a direction opposite to that of the moment S.b.

The distances a and b are selected so that the moments F.a and S.b are equal or substantially so and cancel each other. Consequently, a zero transverse force Q arises at the abutment point B of the leg 13 or spring 24. As the force F is a function of the force S, balancing of the aforesaid moments can be effected, irrespective of how large the wheel load R is at any time.

Claims

1. A vehicle-wheel suspension in which the wheel carrier is guided by two members located one above the other and is abutted mainly in a vertical direction by means of a shock-absorber leg which is extendable and contractable telescopically under the action of the wheelspringing means, the said leg being pivotably connected to the lower said member which is pivotably connected, directly or indirectly, to the vehicle superstructure and the upper said member being pivotably connected to the said leg.

2. A suspension according to claim 1 wherein the said leg is so pivotably connected and/or abutted as to be non-rotatable about its longitudinal axis.

3. A suspension according to claim 1 or 2, wherein the axis of action of the wheel-springing means, which surrounds the said leg and is abutted downwardly thereon, extends obliquely downwardly and outwardly, at an acute angle in relation to the axis of the leg.

4. A suspension according to any one of claims 1-3, wherein a lower abutment for the wheel-springing means is located on the said leg above the pivotal joint between the upper said member and the leg.

5. A suspension according to any one of claims 1-4, wherein the said members are so disposed and pivotably connected to the said leg and the wheel springing means are so disposed and abutted on the leg that the moment with which force is applied by the wheel, through the joint between the wheel carrier and upper said member, to that member and which acts in the joint between said upper member and leg at a distance from the joint between the leg and the lower said member is opposite and equal, or substantially opposite and equal, to the moment with which the force of the springing means acts upon the leg at a distance between the joint of action of that force and the joint between the lower said member and the leg.

6. A suspension according to any one of claims 1-5, wherein the distance between the joints between the said leg and the upper, shorter, said member on the one hand and the lower, longer, said member on the other hand is less than the distance between the joints between the wheel carrier and the upper said member on the one hand and the lower said member on the other hand, and the axis through the two last-named joints passes through or approximately through the point of contact of the wheel with the road.

7. A vehicle-wheel suspension substantially as hereinbefore described with reference to the accompanying drawing.