GB2110173A

GB2110173A - Steering system for a motor vehicle

Info

Publication number: GB2110173A
Application number: GB08229361A
Authority: GB
Inventors: Braeckel Dirk Van
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1981-11-25
Filing date: 1982-10-14
Publication date: 1983-06-15
Also published as: GB2110173B; DE3146612C2; DE3146612A1

Abstract

The steerable wheels (2, 3) are guided by wheel suspension members (4, 5) with a variable wheel base. Each wheel (2, 3) is acted upon in front of and behind the vertical median wheel plane (X) by two independent steering linkages (6, 7). In the case of a steering movement to the left one steering linkage (7) is actuated and the other steering linkage (6) is fixed so as to form the steering axes of the wheels (2 and 3 respectively), while in the case of a steering movement to the right the second steering linkage (6) is actuated and the first steering linkage (7) is fixed so as to form the pivoting axes of the wheels (2 and 3 respectively). <IMAGE>

Description

SPECIFICATION Steering system for a motor vehicle The invention relates to a steering system for motor vehicles.

References in this specification to "a pair of opposite steerable wheels" means one wheel on each side of a vehicle with the wheel axes of rotation being colinearwhen the vehicle is moving straight ahead, e.g. the two front wheels of a conventional motor car.

In the conventional steering systems for motor cars the steerable wheels are guided by a wheel suspension with a wheel base which remains essentially constant. The steerable wheels are pivoted by way of a steering linkage about a steering axis which normally lies essentially in the vertical median plane of the wheels.

Thus, in the case of the known steering systems for motor cars, when a steering movement is made to the left or the right, each steered wheel turns only with its front part in the desired direction, while the rear part swings in the opposite direction.

A corresponding space for movement must therfore be made available in the bodywork not only inwards towards the centre of the vehicle but also outwards.

In the course of the intensive efforts being made today in the motor car industry to develop the most favourable bodywork shapes in terms of flow dynamics, the adverse effect of wheel openings upon the steered wheels and their momentary projection beyond the contour of the bodywork during steering movements was recognized at a very early stage.

According to the invention, there is provided a steering system for a pair of opposite steerable wheels of a motor vehicle, comprising suspension means mounting the wheels and arranged so that the wheel base between the two wheels can alter, and two independent steering linkages of which one steering linkage for steering movements to the left acts upon the left-hand steerable wheel behind the vertical median wheel plane and upon the right-hand steerable wheel in front of the vertical median wheel plane and the other steering linkage for steering movements to the right acts upon the right-hand steerable wheel behind the vertical median wheel plane and upn the left-hand steerable wheel in front of the vertical median wheel plane, so that when a steering movement is undertaken to the left the one steering linkage is actuated and the other steering linkage is fixed so as to form the steering axes of the steerable wheels at the points where the other linkage acts upon the wheels, while in the case of a steering movement to the right the other steering linkage is actuated and the one steering linkage is fixed so as to form the steering axes of the steerable wheels at the points where the one linkage acts upon the wheels.

By virtue of the fact that the steerable wheels have a variable wheel base, and each wheel is acted upon in front of and behind its vertical median plane by two independent steering linkages, the steerable wheels may be arranged on a maximum wheel base without any projection beyond the outer vehicle skin, and with the contour of the bodywork faired across the wheel positions.

This may be advantageous in particular when, in order to achieve maximum performance, a motor car is to be designed with the smallest possible drag coefficient.

The invention is described in greater detail, by way of example, with reference to diagrammatic sketches shown in the accompanying drawings, in which: Figure 1 is a top view of a steering system according to the invention, Figure 2 is the position of the steering system shown in Figure 1, in a steering movement to the left, and Figure 3 is the position of the steering system shown in Figure 1, when steering to the right Steerable wheels 2 and 3 are arranged inside a fully faired bodywork 1. The wheels are mounted on wheel suspension members 4 and 5, with a variable wheel base. The possible wheel base variation is indicated in the diagrammatic drawing by elongate holes in the wheel suspension members 4 and 5.

Each steerable wheel 2 and 3 is acted upon in fron of and behind the vertical median plane X of the wheels by two essentialiy independent steering linkages 6 and 7.

In order to distinguish clearly between the two different steering linkages 6 and 7, the steering linkage 6 has been left blank, while the steering linkage 7 has been accentuated by stippling. The steering linkages 6 is provided for steering movements to the right and the steering linkage 7 is provided for steering movements to the left.

The steering linkage 6 acts upon the left-hand steerable wheel 2 at a pivoting point 8 in front ofthe vertical median wheel plane X, while it acts upon the right-hand steerable wheel 3 at a pivoting point 9 behind the vertical median wheel plane X.

In a similar way the steering linkage 7 acts upon the right-hand steerable wheel 3 at a pivoting point 10 in front of the vertical median wheel plane X and acts upon the left-hand steerable wheel 2 at a pivoting point 11 behind the vertical median plane X.

In Figure 1 the two steering linkages 6 and 7 are shown in their rest position, in which they hold the steerable wheels 2 and 3 in the straight ahead direction.

The linkages 6 and 7 are connected to a steering control such as a steering wheel (not shown) so that use of the control produces the movements set out below.

In Figure 2, which shows a steering movement to the left, the steering linkage 6 remains in its rest position, while the steering linkage 7 is actuated.

Thus the steering linkage 7 pivots the left-hand steerable wheel 2 about the pivoting point 8 of the steering linkage 6 forming the steering axis, while it displaces the pivoting point 11 towards the inside.

In a similar way the steering linkage 7 pivots the right-hand steerable wheel 3 about the pivoting point 9 of the steering linkage 6, while it displaces the pivoting point 10 towards the inside.

The corresponding movement of the wheel cen tres of the steerable wheels 2 and 3 in the plane Xis made possible by movement of the wheel centres along the elongate holes in the wheel suspension members 4, 5. It will be seen that the effective wheelbase between the steered wheels is reduced during a steering movement.

In Figure 3, which shows a steering movement to the right, the steering linkage 7 remains in its rest position, while the steering linkage 6 is actuated. The steering linkage 6 pivots the left-hand steerable wheel 2 about the rear pivoting point 11 of the steering linkage 7, while it displaces the pivoting point 8 towards the inside. The steering linkage 6 pivots the right-hand steerable wheel 3 about the front pivoting point 10 of the steering linkage 7, while it displaces the rear pivoting point 9 towards the inside.

The technical construction of the wheel suspension and of the two steering linkages is, after their principal mode of functioning has been explained, entirely possible for the person skilled in the art.

Claims

1. A steering system for a pair of opposite steerable wheels of a motor vehicle, comprising suspension means mounting the wheels and arranged so that the wheel base between the two wheels can alter, and two independent steering linkages of which one steering linkage for steering movements to the left acts upon the left-hand steerable wheel behind the vertical median wheel plane and upon the right-hand steerable wheel in front of the vertical median wheel plane and the other steering linkage for steering movements to the right acts upon the right-hand steerable wheel behind the vertical median wheel plane and upn the left-hand steerable wheel in front of the vertical median wheel plane, so that when a steering movement is undertaken to the left the one steering linkage is actuated and the other steering linkage is fixed so as to form the steering axes of the steerable wheels at the points where the other linkage acts upon the wheels, while in the case of a steering movement to the right the other steering linkage is actuated and the one steering linkage is fixed so as to form the steering axes of the steerable wheels at the points where the one linkage acts upon the wheels.

2. A steering system substantially as herein described, with reference to the accompanying drawings.

3. A motor vehicle having a steering system as claimed in Claim 1 or Claim 2, and bodywork including fairings over the steerable wheels.