GB2332402A

GB2332402A - A vehicle suspension

Info

Publication number: GB2332402A
Application number: GB9826779A
Authority: GB
Inventors: Uwe Neerpasch
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1997-12-17
Filing date: 1998-12-04
Publication date: 1999-06-23
Anticipated expiration: 2018-12-04
Also published as: DE19756066C2; GB2332402B; DE19756066A1; GB9826779D0; FR2772308B1; FR2772308A1; IT1302917B1; ITRM980766A1

Abstract

A vehicle suspension in which the force of the weight of the vehicle body and the lateral forces acting on it are supported independently of one another on the chassis, the suspension having at least one spring damper system 20, and the wheels being coupled by means of levers - directly or by means of intermediate elements - and a power coupling mechanism 30. The power coupling 31 of the power coupling mechanism 30 is guided at its central articulation point in the region between the external articulation points of the power coupling mechanism in a horizontal plane which lies transversely with respect to the longitudinal direction of the vehicle, and is supported on the vehicle body by means of a spring damper system and/or an active roll control device.

Description

1 2332402 1 Vehicle suspensio The invention relates to a vehicle

suspension.

When chassis suspension systems are set up, there is basically a conflict in objectives of, on the one hand, achieving the greatest possible degree of driving comfort and on the other hand of simultaneously keeping the rolling movement of the vehicle body small during cornering. With the axle types which are currently known, the two criteria cannot be influenced independently of one another. As a result of the arrangement of the springs and dampers between the elements of the wheel suspension and the vehicle body, the vertical movement and rolling movement of the vehicle body are coupled. That is to say a design change in the spring stiffness and/or the damping acts, in a travelling vehicle, as an effect both on the vertical movement and on the rolling movement.

By using stabilizers, the spring stiffness is increased in the case of a rolling movement, as a result of which the tendency of the vehicle to roll is reduced but at the same time the damping of the rolling of the vehicle body is also reduced.

The invention is based on the problem of providing a vehicle suspension in which the force of the weight of the vehicle body and the lateral forces acting on it are supported independently of one another on the chassis.

According to the present invention there is provided a vehicle suspension having at least one wheel-bearing radius link, having at least one lever, per vehicle wheel, the wheels being supported one on the other either by means of the levers or by means of the radius links or levers in combination with a balance arm mounted on the vehicle body, on the one hand, and by means of at least one spring damper system, on the other, and the wheels being coupled by means of the levers directly or by means of intermediate elements and a power coupling mechanism, in which the power coupling of the power coupling mechanism is guided at its central articulation point in the region between external articulation points of the power coupling mechanism in a horizontal plane which lies transversely with respect to the longitudinal direction of the vehicle, and is supported on the vehicle body by means of at least a spring damper system and/or an active roll control device.

A vehicle axle having some of these features is known from US- 1 2 PS 2,128,660. Here, a double wishbone axle is described whose upper wishbone is given, by virtue of a frame structure, the shape of lying triangular pyramids whose base is supported on the vehicle body, a horizontally lying helical spring and a power coupling mechanism. The frame structure constitutes, in abstract form, a lever between whose free ends the helical spring and the power coupling mechanism are arranged. The power coupling mechanism is articulated on the vehicle body by means of the central joint of the power coupling. The result of this is that the radius links of both sides are positively coupled. Both wheels of the axle basically experience spring compression or spring extension at the same time.

Although this structure does not constitute a means of solving the problem which has been set, it forms part of the technical basis for one of the illustrated exemplary embodiments.

The invention consists in the fact that the power coupling of the power coupling mechanism is guided at its central articulation point in the region between the external articulation points of the power coupling mechanism in a horizontal plane which lies transversely with respect to the longitudinal direction of the vehicle, and is supported on the vehicle body by means of a spring damper system and/or an active roll control device.

As a result, the two degrees of freedom of lifting and rolling can be configured or adjusted independently of one another in terms of their stiffness and damping. A pure vertical movement with simultaneous spring compression of both wheels leads only to loading of the vertical movement spring damper system and a pure rolling movement with spring compression of the wheels on alternate sides of the vehicle loads the rolling spring damper system exclusively.

This wheel suspension provides significant additional degrees of freedom for the adjustment of the vehicle. It is now possible to adjust the natural oscillating frequency and damping of the body in terms of driving comfort without simultaneously having to permit large movements of the vehicle body during cornering. Furthermore, the damping of rolling may be selected as desired.

In the case of a wishbone or semi-trailing arm axle without active roll control, only two springs and two dampers are required, inter alia, to do this, it being possible to install said springs and dampers in a spacesaving fashion between the 1 1 wheels.

3 Further details of the invention emerge from the following description of two embodiments which are illustrated schematically in the drawings, in which:

Figure 1 shows a front view of a multi-link individual-wheel suspension with the suspension links positioned in a neutral position, Figure 2 shows the same as Figure I but in a position of spring compression on both sides; Figure 3 shows the same as Figure 2 but in a position of spring compression on alternate sides; Figure 4 shows a diametric illustration of a trailing arm individual- wheel suspension.

Fi&res. 1 to 3 show a double link suspension with a decoupled lifting and rolling suspension. The double link suspension has a lower linkage 11, 11' and an upper linkage 13, 13' per wheel 2, 2'. The linkages are, for example of wishbone type with A-arms which are mounted on the vehicle body 5 in pivot joints which are arranged in parallel. In this embodiment, the pivot axes of the linkages are arranged in idealized fashion both parallel to the longitudinal axis of the vehicle and parallel to the carriage way 1. At the wheel end, the linkages are coupled by means of wheel carriers 14, 14'.

In Figures 2 and 3, two auxiliary lines are drawn respectively above or below the carriage way 1 in the vicinity of the wheel contact areas. The auxiliary lines mark the wheel contact area with respect to the displaced vehicle body in the neutral position of the chassis.

On each lower linkage 11, 11' a lever 12, 12', which transforms the vertical movement into a transverse movement during the spring compression and spring extension, is rigidly arranged. On the levers 12, 12' there are, inter alia, the lifting articulation points 15, 15' between which a vertical movement spring damper unit 20 is supported in an articulated fashion.

Said unit 20 comprises a damper 21, 22 which, by means of its piston rod 21, is articulated on the left-hand lever 12 and is articulated by means of its cylinder 22 on the right-hand lever 12', cf. Figure 2. A plateshaped adaptor element 23, 24 is mounted in the vicinity of the left-hand end of the piston rod 21 and in the 4 vicinity of the right-hand cylinder end, respectively. The vertical movement spring 26 is seated between the adaptor elements 23, 24, concentrically with respect to the cylinder 22.

In Figures 1 to 3, the vertical movement spring 26 and the adaptor elements 23, 24 are shaped and arranged at a distance from one another in such a way that the vertical movement spring 26 can either be subjected to tensile loading or, when the wheels 2, 2' have experienced complete spring extension, is still subjected to compression.

In this respect the linkages 11, 11', the levers 12, 12' and the vertical movement spring damper unit 20 form independently of the dimensioning of the vertical movement spring damper unit a known transverse spring compensation means. Given spring compression or spring extension of both wheels 2, 2' on both sides, cf. Figure 2, the distance between the lifting articulation points 15, 15' changes. For example, given spring compression, the distance is shortened, the vertical movement spring 26 being subjected to compressive loading, and the compressive loading of the vertical movement spring 26 increasing.

Given spring compression or spring extension of both wheels 2, 2' on alternate sides, cf. Figure 3, the distance between the lifting articulation points 15, 15' does not change - while the wheel travel is approximately the same in each case. The vertical movement spring damper unit 20 oscillates to the right without effect.

In addition, the rolling articulation points 16, 16' are arranged on the levers 12, 12'. A power coupling mechanism 30 which is guided by a rolling spring damper unit 40 is arranged between these articulation points. The power coupling mechanism 30 is composed of the coupling rods 32, 33 which are articulated on the levers 12, 12' and a power coupling 31 which lies between them in an articulated fashion. The coupling rods 32, 33 and the power coupling 31 form a planar "Z" in the illustrated ideal case. The power coupling 31 has half way along it a pivoting articulation point 48 by means of which it is pivotally mounted on the rolling spring damper unit 40.

The rolling spring damper unit 40 has a design which is comparable to the vertical movement spring damper unit 20. It is composed of a rolling damper 41 42 of which the piston rod 41 and the cylinder 42 are illustrated. The cylinder 42 is, 1 depending on the design, seated on the vehicle body 5 in a cylinder bearing 49 in an articulated or rigid fashion, while the piston rod 41 is at least linearly guided in a piston rod bearing 47. The adaptor elements 43, 44 which clamp in the rolling spring 46 are secured to the piston rod 41 and to the cylinder 42.

As illustrated in Figure 2, given spring compression of the wheels 2, 2' on both sides, the rolling spring damper unit 40 behaves in a neutral fashion although the distance between the rolling articulation points 16, 16' is shortened. The coupling rods 32, 33 only pivot the power coupling 31 in the pivoting articulation point 48 which is arranged on the piston rod 41. The pivoting articulation point 48 is not displaced in relation to the vertical axis 6 of the vehicle.

Given spring compression on alternate sides as in Figure 3 - the wheels 2, 2' carry out the same travel in terms of absolute value but with different signs - the distance between the rolling articulation points 16, 16' remains constant as a result of the parallel pivoting of the levers 12, 12'. As a result of the vehicle body 5 rolling to the left, the rolling spring damper unit 40 which is supported on the levers 12, 12' by means of the power coupling mechanism 30 is compressed by the amount "a". In the process, the vehicle body 5 is supported on the chassis by means of the rolling spring 46 without loading the vertical movement spring 26.

The levers 12, 12' may also be jibs, which are stiffened with the respective linkage by means of rods, a frame structure or plate-like elements.

In contrast to the embodiment in Figures 1 to 3, the vertical movement spring and the rolling spring damper units may each be installed between separate pairs of levers. Here, for example, the lower linkages may each be fitted with two levers, the lever pair for the vertical movement spring damper unit lying, for example, in front of the lever pair for the rolling spring damper unit. Alternatively, one lever may be arranged at each of the four linkages so that, for example, the vertical movement spring is supported on the lower linkage and the rolling spring on the upper linkage.

Instead of the wheel suspension in a double wishbone arrangement as explained, said suspension may also be a multi-link arrangement, and any type of axle - even a rigid axle - in which the spring and damper are supported on a wheel-bearing component or radius link, i.e. do not have any wheel- guiding property. Once the radius links are pivotally arranged in a position which is not parallel to the vehicle axis, such 6 as is the case with the semi-trailing arms, at least the pivot joints of the coupling rods 32, 32' must be replaced by ball joints and/or cardan universal joints, for example. If appropriate, the support of the rolling spring damper system on the vehicle body together with the central articulation point must be displaceably arranged in the longitudinal direction of the vehicle, the displacement path corresponding, for example, to the average dislocation component of the external rolling articulation points in the same direction.

Figure 4 schematically illustrates a pure trailing arm suspension. The lifting suspension is provided here by means of two vertical movement spring elements 57, 57' which are supported on the trailing arms 51, 51', on the one hand, and on a balance arm 55, on the other. The balance arm 55 is pivotally mounted at the articulation point 56 on the vehicle body 5. The vertical movement spring elements 57, 57' contain the dampers.

For the rolling suspension, the levers 52, 52' are arranged on the trailing arms 51, 51', said levers 52, 52' transforming the pivoting movement of the levers 52, 52' about a transverse axis into a pivoting movement about a vertical axis by means of angular levers 53, 53' which are mounted on the vehicle body 5 and form intermediate elements. A power coupling mechanism 30 and a rolling spring damper unit 40 lie between the angular levers 53, 53'.

Given spring compression of the wheels 2, 2' in the same direction, the balance bar 55 does not pivot. The vertical movement spring elements 57, 57' are subjected to compression in the same direction. The power coupling 31 pivots in the pivoting articulation point 48 without displacing the piston rod 41.

Given spring compression on alternate sides, the balance bar 55 pivots without bringing about a change in the stiffness of the vertical movement spring elements 57, 57'. The levers 52, 52' and the angular levers 53, 53' displace the power coupling 31 transversely in the direction of the wheel 2' which is on the inside of the bend. The rolling spring damper unit 40 is loaded.

By means of the decoupling of the lifting suspension and rolling suspension it is possible to implement, with simple means, an active roll control according to the principle of tilting into a curve. The rolling spring damper units which are illustrated in Figures I to 4 are expanded with a linear actuator element. If 1 7 appropriate, a hydraulic and/or pneumatic linear actuator element may also replace the rolling spring damper unit. The linear actuator unit performs the translatory guidance of the power coupling. By displacing the coupling rods in the same direction, the vehicle body is pivoted through an appropriate rolling angle.

1 8

Claims

Claims

A vehicle suspension having at least one wheel-bearing radius link, having at least one lever, per vehicle wheel, the wheels being supported one on the other either by means of the levers or by means of the radius links or levers in combination with a balance arm mounted on the vehicle body, on the one hand, and by means of at least one spring damper system, on the other, and the wheels being coupled by means of the levers directly or by means of intermediate elements and a power coupling mechanism, in which the power coupling of the power coupling mechanism is guided at its central articulation point in the region between external articulation points of the power coupling mechanism in a horizontal plane which lies transversely with respect to the longitudinal direction of the vehicle, and is supported on the vehicle body by means of at least a spring damper system and/or an active roll control device.
2. A vehicle suspension, substantially as described herein with reference to and as illustrated in the accompanying drawings.

1