Rear suspension

Abstract: In a rear suspension which is equipped with wheel carrier arms (4,5), which wheel carrier arms are coupled to each other via a cross-beam (6), which cross-beam runs largely parallel to the wheel-axles and has ends (7,8), which ends are each connected to the chassis (15) by means of a steering arm (9,10), the steering arms are resilient. To this end, the steering arms can be bent, or they can be embodied as, for example, leaf springs. The end regarding the leaf spring which is to be mounted to the chassis is preferably formed into a housing (18) for a rubber bearing element (16). The rear suspension compensates for the inclination towards oversteer in a vehicle, which oversteer arises under the influence of transverse forces which arise during the vehicle's engagement of a corner.

Description: The current invention pertains to a rear suspension equipped with wheel carrier arms, which wheel carrier arms are coupled to each other by way of a torsion-weak cross-beam having high bending stiffness, which cross-beam runs largely parallel to the wheel-axles and has ends, which ends are each connected to the chassis of a vehicle by means of a resilient steering arm. Such a rear suspension is known from SE-457866. The cross-beam is hereby constructed from two mutually coupled portions and an end of each of the portions is connected to the chassis by means of a steering arm. The steering arms are thereby enclosed by rubber elements in such a manner that a rotation-stiffness in the vertical sense, which rotation-stiffness is necessary for the absorption of the transverse forces which mainly occur during the engagement of corners, is provided. With this, the problem of inclination towards oversteer during the engagement of a corner as a result of the transverse forces which are then experienced is addressed, in a way, however, which is relatively complicated and expensive from both a development and production point of view. Other known solutions to the problem on hand, as known from the article "Die neue Hinterachs-Generation im VW Passat", published in ATZ Automobiltechnische Zeitschrift 83 (1981) 1, page's 3-7, employ a track-correcting bearing, which track-correcting bearing contains a couple of asymmetrically composed wedge-shaped rubber tubes, at the location of each connection between a steering arm and the chassis. This known solution is, however, also complicated and expensive. The aim of the current invention is to use another principle, in order to compensate for the inclination towards oversteer during the engagement of a corner, in an inexpensive and simple manner. To that end, the rear suspension according to the invention is characterised in that the steering arm is embodied as a leaf spring made from sheet steel, or otherwise is made from carbon/glass-fibre reinforced composite material with elastic properties, and that each steering arm has ends, whereby one end is rigidly connected to the cross-beam, while the other end is equipped with a rubber bearing element, which rubber bearing element is fixed to the chassis and whereby the bending plane of the spring is substantially horizontal. The advantage of this resilient steering arm is that the steering arm is in principle capable of transferring forces in a flexible manner to the chassis in all desired directions. The new principle realised therewith makes use of the advantages of the well-known delta-link principle, whereby the oversteer problem is combated by the creation of, in addition to a first movement-pole of the suspension, which first movement-pole lies forward of the virtual axle between the wheels, a second movement-pole which rightly lies behind this axle, with which second movement-pole a rotation is achieved which compensates for the oversteer. The advantage is that in the case of an in general equal length of the steering arms the relation between the bending and the maximum tension arising in the steering arms is optimal. In a simple embodiment according to the invention, the rear suspension has a steering arm which is bent, whereby in this manner, forces are absorbed elastically through the steering arm in the bending-plane. In a further preferential embodiment of the rear suspension according to the invention, the rubber bearing element has such a low rotation stiffness that the respective steering arms act as unilaterally clamped beams with one free end. The advantage of this preferential embodiment is that in the case of an in general equal length of the steering arms the relation between the bending and the maximum tension arising in the steering arms is optimal. In a further preferential embodiment, the rear suspension according to the invention is characterised in that the axis of rotation of the rubber bearing element in a fitted state runs substantially vertical. The advantage hereof is that, in principle, the affixation of the rubber bearing element to the chassis can occur in a simple manner, for example with the aid of a bolt. Furthermore, it is an advantage that, given the vertical axis of rotation of the rubber bearing element, the rotation of the bearing element during the engagement of a corner occurs in substantially the same direction as the direction of mobility of the resilient steering arm. An interaction and interchange ability between the elastic properties of the steering arms and the stiffness of the rubber of the bearing element is a result thereof, whereby a greater additional freedom is provided in the choice of the stiffness of the resilient steering arms and the rubber bearing elements. Yet a further preferential embodiment is characterised in that the aforementioned other end of the respective steering arms is formed to a housing for the rubber bearing element, whereby namely in the case of a vertical orientation of the aforementioned affixation, the end of a steering arm formed in this manner can be simply employed as a housing for the rubber bearing element, whereby an extremely simple construction of the oversteer-compensating elements is acquired. The invention will be further elucidated on the basis of the accompanying drawing, wherein consistent reference numbers are used for the indication of one and the same element. The subjects of the figures are as follows: figure 1 is a schematic depiction of the basic principle which is applied in the rear suspension according to the invention; figure 2 is a depiction of a partially-shown practical preferential embodiment of the rear suspension according to the invention; and figure 3 is a plan view of the rear suspension of figure 2. Figure 1 shows the principle of a rear suspension 1, which in addition to wheels fixed to wheel-axles 2 and 3, contains wheel carrier arms 4, 5 affixed to the wheel-axles 2, 3, between which wheel carrier arms 4, 5 a cross-beam 6 is fixed, which cross-beam 6 runs largely parallel to the wheel carrier axles 2, 3. The cross-beam 6 has ends 7 and 8 which are coupled to resilient steering arms 9 and 10, respectively. Steering arm 9 has ends 11 and 12 and steering arm 10 has ends 13 and 14, whereby the respective ends 12 and 14 are coupled with the schematically-depicted chassis 15. A practical preferential embodiment of the rear suspension 1 is schematically depicted in figures 2 and 3. In this preferential embodiment the steering arm is implemented elastically as a leaf spring. If desired, the steering arm 9, 10 can also have a curved form. The one end 13 of the steering arm 10 depicted namely in figure 2 is rigidly connected to the end 8 of the cross-beam 6, while the other end 14 is equipped with a schematically-depicted rubber bearing element 16, which rubber bearing element 16 is fixed to the - not depicted in this figure - chassis. The rubber bearing element 16 preferably has such a low rotation stiffness that the steering arm 10 acts as a unilaterally clamped beam with a free end 13, whereby the relationship between bending and the highest tension in the steering arm in question is optimal namely in the vertical orientation of the axle 17 shown in figure 3. The central axle 17 of the thereby rotation-symmetric rubber bearing element 16 runs preferably vertically, so that in addition to a simple affixation to the chassis the end 14 in question can contain an eye which serves as a housing 18 for the bearing element 16.

Claims: Rear suspension equipped with wheel carrier arms (4, 5), which wheel carrier arms are coupled to each other via a torsion-weak cross-beam (6) having a high bending stiffness, which cross-beam runs largely parallel to the wheel-axles (2, 3) and has ends (7, 8), which ends are each connected to the chassis (15) of a vehicle by means of a resilient steering arm (9, 10), characterised in that the steering arm (9, 10) is embodied as a leaf spring made from sheet steel, or otherwise is made from carbon/glass-fibre reinforced composite material with elastic properties, and each steering arm (9, 10) has ends (11, 12, 13, 14), whereby one end (11, 13) is rigidly connected to the cross-beam (6), while the other end (12, 14) is equipped with a rubber bearing element (16), which rubber bearing element is fixed to the chassis (15) and the bending plane of the spring is substantially horizontal. Rear suspension according to claim 1, characterised in that the steering arm (9, 10) is bent. Rear suspension according to claim 1 or 2, characterised in that the rubber bearing element (16) has such a low rotation stiffness that the respective steering arms (9, 10) act as unilaterally clamped beams with one free end. Rear suspension according to claim 3, characterised in that the axis of rotation (17) of the rubber bearing element (16) in a fitted state runs substantially vertical. Rear suspension according to claim 4, characterised in that the aforementioned other end (12, 14) of the respective steering arms (9, 10) is formed to a housing (18) for the rubber bearing element (16).

Inventors: FUN JOHANNES KRYN, FUN, JOHANNES KRYN
Applicants: NETHERLANDS CAR BV, NETHERLANDS CAR B.V.
Application year: 1993
Main classification: B60G21
IPC codes: B60G9, B60G11, B60G21