The invention relates to a wheel suspension system for steerable rear wheels of a motor vehicle.
Rear wheel suspension systems of the generic type are known. For example, German Patent Document DE-OS 36 30 984, discloses an arrangement in which an arm connected at one end with the wheel carrier extends in the longitudinal direction of the vehicle, and is connected at its other end with a hydraulically operable adjusting element. The wheel carrier is pivotally supported between joints of transversely aligned control arms which are held on the vehicle body side. In such an arrangement, because of the arm connected with the wheel carrier, the position of the adjusting element is fixed with respect to the vehicle, and can be changed only at a relatively high cost.
Due to space limitations (and also for kinematic and elastokinematic reasons), it may be necessary, particularly in the case of a double wishbone axle having an additional separate rod link, that the adjusting element not be connected directly with the wheel carrier.
It is therefore an object of the present invention to provide a wheel suspension for steerable rear wheels of motor vehicles in which direct control of a wheel suspension link is made possible for achieving a rear-wheel locking angle. This object is achieved according to the invention, in a double-wishbone suspension system wherein the wheels are adapted to react resiliently as a result of longitudinal or lateral forces and which, at the same time, can be controlled for the adjustment of a rear wheel steering angle by way of an adjusting element, such as a hydraulic control cylinder, a motor operator or similar devices. The two wishbones arranged in planes situated above one another, are pivotally connected to the wheel carrier as well as to the vehicle body and, either in the lower plane or in the upper plane, are supplemented by an additional rod link. The arrangement of the wheel suspension links and bearing members is such that a resilient rotating axis is established outside the wheel center longitudinal plane and-with respect to the driving direction--behind the wheel center transverse plane. (The words "front", "rear" and "behind" are used herein relative to the forward driving direction F as shown in FIG. 1.) Under the influence of outside forces and torques in the wheel contact area, the wheel rotates around this axis in the wheel contact surface. The extent of the rotation, for example in the case of a bump toe-in, is essentially a function of the elasticity of a control bearing between the adjusting element and a control arm, and the elasticity of the additional rod link. The control bearing also has an advantageous effect on the active adjustment of the rear-wheel locking angle by way of the adjusting element and, for this purpose, has a correspondingly defined marking.
Depending on the construction of the double-wishbone axle and the connection of the adjusting element with one of the control arms, a corresponding active center of rotation for the wheel is disposed either in the intersecting point of the longitudinal axes of the control arms of the wheel suspension links or directly in the wheel-carrier-side joint of the wheel suspension link. As noted previously, the passive center of rotation of the wheel suspension system is determined by the elastic swivel axis and by the wishbones.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.