Semi trailing arm suspension pdf

The suspension comprises a wheel support constrained to move about an axis of rotation relative to the vehicle body by a linkage arrangement connected between the wheel support and mountings on the vehicle body.

The linkage arrangement has first and second arm members arranged such that imaginary extensions thereof intersect at a point outside of the centre of a wheel mounted on said wheel support and to the rear of the axis of rotation of the wheel and has a third linkage between said vehicle body and said wheel support which is connected to the vehicle body at a position that lies outwardly from the position at which the second arm is coupled to the vehicle body and to the rear of an imaginary line extending between the position of connection of the first arm to the body and the position of connection of the second arm to the vehicle body.

In order to simplify the manufacture of a given range of vehicles, it is useful to have as many components as possible common to all the vehicles of the range. If, for example, a common rear suspension could be produced for a range of vehicles embracing sports, estate and saloon cars and for low cost utility vehicles, the overall manufacturing costs would be reduced. However, suspension requirements for a such a range of vehicles can differ significantly from vehicle to vehicle.

For example, suspension compliance characteristics are critical on sports vehicles, which may be subjected to frequent and heavy braking and fast cornering, but are generally of less significance on estate and saloon cars and of very little importance on low cost utility vehicles.

Similarly uncontrolled rear wheel steering and camber control are important factors on sports cars and likewise on estate and saloon cars but are of less significance on the low cost utility vehicle. Camber compensation for roll is, again, an important requirement for sports cars but is of lesser importance on saloon and estate cars and of no particular importance for the low cost utility type vehicle.

It has not hitherto been possible to produce a suspension which, at one end of the range, can be tuned to provide the requirements of a sports vehicle and which, at the other end, will suit the requirements of a low cost utility vehicle. From several aspects a semi-trailing arm suspension is ideal as such a suspension can easily be positioned under the floor which will, in turn, lead to a wide load carrying space within the vehicle which is ideal for saloon and estate cars.

A typical prior art semi-trailing arm rear suspension is shown diagrammatically in plan view in FIG. A sub-frame 10 suitably attached to a chassis or body 11 of the vehicle carries bearings 12 for two trailing arms The bearings 12 define respective axes of pivoting 16 for the arms 14 which are inclined at an angle "a" with respect to an axis extending laterally with respect to the vehicle body.

This angle of inclination is known in the art as the "angle of semi-trail". The arms 14 carry wheel mountings 18 at their outer ends for road wheels It is a problem with this type of arrangement that during vertical movement of the wheels 20, the wheels generate a certain amount of bump steer and camber change which can be undesirable factors depending upon the type of vehicle to which the suspension is fitted.

Although the angle of semi-trail can be optimised to provide a reasonable compromise from vehicle to vehicle, the result will not normally be ideal for many vehicles in a range. It is therefore a first object of the present invention to provide an improved semi-trailing arm suspension which will enable the suspension to meet the requirements of a typical range of vehicles.

It is a second object of this invention to provide a suspension that can be tailored in an economical manner to suit various different types of vehicle. With a prior art semi-trailing arm rear suspension, compliance in the suspension due to lateral or longitudinal loading at the wheel centre due to braking or cornering will tend to cause toe-out of the wheel which is an undesirable characteristic for a rear suspension.

By arranging in the suspension according to the invention for the first and second arms to converge towards a point which lies outboard and to the rear of the centre of the wheel of the vehicle during heavy braking the wheel tends to "toe in" which helps to cancel out the toe out due to compliance in the suspension. The pivotal connection between the first arm and the wheel mounting is preferably arranged such that during substantially vertical movement of the wheel mounting, the wheel mounting steers in a controlled manner.

In addition by arranging for the position of connection of the third linkage to the vehicle to be made at a position which lies outboard of the position of connection of the second arm to the vehicle and to the rear of an imaginary line extending between the position of connection of the first arm to the body and the position of connection of the second arm to the vehicle body, vertical movement of the wheel will cause the wheel to undergo a steering movement causing it to toe-out.

In that way, any tendency for the wheel to toe-in during vertical movement of the wheel can be compensated by a toe-out movement which simultaneously takes place due to the action of the third linkage. The connection of the third linkage to the wheel support may be made via the second arm. The third linkage and the second arm may be formed as a single structural member. The connection between the third linkage and the vehicle body may be made by means of a compliance bush.

The third linkage may be formed by a separate structural member coupled to the body of the vehicle by a compliance bush and to the wheel support by a pivot means. The third linkage may be formed by a separate structural member coupled to the wheel support by a compliance bush and to the body of the vehicle by a pivot means.

The second arm may be connected to the wheel support at two vertically separated positions. The second arm may be connected to the wheel support for rotation about a vertical axis.

The linkage arrangement may further comprise a third arm having a first end coupled to part of the vehicle body for rotation with respect thereto about a generally horizontal axis and a second end coupled to said wheel support member, the second and third arm members converging such that imaginary extensions thereof intersect at a point of intersection which lies forwardly with respect to an imaginary line extending from the position of connection of the first arm to the vehicle body and the position of connection of the second arm to the vehicle body so that the axis of rotation about which the wheel support is constrained to move relative to the vehicle body extends from said point of intersection to the position of connection of the first arm to the body.

The positions of connection of the second and third arms to the vehicle body may be vertically disposed with respect to each other.

The positions of connection of the second and third arms to the wheel support may be vertically disposed with respect to each other. The second and third arms may be connected to the vehicle body by a mounting means which can be selected from a number of mounting means each of which provides a different vertical distance between the positions of connection of the second and third arms thereby allowing the position of the point of intersection to be selected to suit the dynamic charateristics required for a particular vehicle of a range of vehicles.

This has the advantage that the position of the point of intersection and hence the angle of semi-trail can be easily changed to suit a particular vehicle of the range.

A semi-trailing arm suspension in accordance with the invention will now be described by way of example with reference to the further accompanying drawings in which:. In the following description, parts corresponding to parts shown in FIG. In FIGS. The vertically spaced bearings 34 define a vertical axis of pivoting 36 about which wheel support 18 can rotate a small amount.

A stub axle 8 extends outwardly from the wheel support 18 to rotatably locate a road wheel 20 not shown on FIG. The bearing 30 linking the arm 26 to the body 10 provides the aforesaid first pivot. Between the wheel support 18 and the vehicle body there is disposed a spring means in the form of a substantially vertically extending strut assembly 7 which is used to compliantly support the weight of the vehicle body. The strut assembly 7 comprises of a coil spring 6 and an oleo damper 5 which is pivotally connected to the wheel support 18 at its lower end so as to allow a certain amount of angular movement with respect to the wheel support The arm arrangement 25 also comprises second and third arms 38, 39 which are vertically spaced apart.

The second arm 38 is connected via a bearing 40 to a mounting member 42 attached to the sub-frame 10 mounted on the vehicle body or chassis. The third arm 39 is also connected to the mounting member 42 by a bearing The bearings 40, 44 are vertically spaced apart and provide the aforesaid second and third pivots.

The opposite end of the arm 38 is connected to the wheel support 18 by a fourth bearing 46 and the third arm 39 is connected to the wheel support 18 by a fifth bearing The bearings 46, 48 provide the aforesaid fourth and fifth pivots and are vertically spaced by a distance greater than the vertical spacing between bearings 40, The bearings 40, 44, 46 and 48 provide parallel axes of pivoting. The semi-trailing arm axle for the motor vehicle according to claim 13 , wherein a virtual pivoting point 9 of the semi-trailing arm 1 is located outside a braking force application point in relation to a transverse direction of the vehicle.

The semi-trailing arm axle for the motor vehicle according to claim 12 , wherein the semi-trailing arm 1 is manufactured from one of sheet metal component and a fiber composite component. The semi-trailing arm axle for the motor vehicle according to claim 12 , wherein a spring damper unit 8 is provided for each wheel suspension. The semi-trailing arm axle for the motor vehicle according to claim 18 , wherein the spring damper unit 8 is attached to one of the semi-trailing arm 1 and a wheel carrier 7.

The semi-trailing arm axle for the motor vehicle according to claim 12 , wherein at least one transverse leaf spring is connected to one of the semi-trailing arm 1 and a wheel carrier 7 , and for each wheel suspension at least one damper, connected to one of the flexible semi-trailing arm 1 and a wheel carrier 7 , is provided.

The semi-trailing arm axle for the motor vehicle according to claim 12 , wherein the semi-trailing arm 1 is made integrally and ends of the semi-trailing arm 1 are bolted to one another by connecting bolts, and at least one of the connecting bolts 14 has an eccentric for adjusting a track of the semi-trailing arm 1. The semi-trailing arm axle for the motor vehicle according to claim 12 , wherein a stabilizer 6 is connected to one of a damper of the semi-trailing arm axle, the flexible semi-trailing arm 1 and a wheel carrier 7.

A semi-trailing arm axle for a motor vehicle, the semi-trailing arm axle comprises a semi-trailing arm 1 supporting a wheel 4 , via a wheel carrier 7 and a wheel bearing 5 , the semi-trailing arm 1 being flexible about a vertical axis and being a lone wheel-guiding element,.

USB2 en. EPB1 en. JPB2 en. KRA en. CNB en. DEA1 en. WOA1 en. Rear-wheel independent suspension of a motor vehicle with an electric drive train. Wheel suspension system for vehicle e. Wheel suspension of driven wheels, especially of the rear wheels of a motor vehicle. Independent wheel suspension in semi-trailing, trailing or compound arm construction with an uncoupled wheel carrier.

Arm for a motor-vehicle independent suspension system and a motor-vehicle independent suspension system comprising the arm. EPA1 en. CNA en. JPA en. USA1 en. KRB1 en. USA en. Independent wheel suspension for steered wheels of passenger motor vehicles and the like. It is relatively space-engaging but offers very good handling; Honda Accord's multi-link is essentially a double wishbones suspension added with the fifth control arm.

Audi A4's Quadralink front suspension has four links. It looks alike double wishbones but eliminates torque steer.

In any suspensions, the pivot joints must be inserted with rubber bushing to absorb noise and vibration. For conventional semi-trailing arm suspension first row in the following picture , whenever under braking, the momentum of the car body tries to pull the car "away" from the rear suspension.

Due to the elasticity of the rubber bushing, the rear wheel will toe-out. As a result, the car will oversteer. Weissach axle was designed to eliminate this oversteer second row in the picture. By splitting one trailing link into two pieces, with a pivot joint added between them, the oversteer under braking can be elinimated or even introduce some understeer! This help stablizing the cornering motion. Some people call it as "passive rear-wheel steering". Porsche All round, few weakness.

Golf's torsion beam rear suspension. Fiat Punto's torsion beam. Theoretically inferior ride and handling. Good handling and ride.