The present invention pertains to a wheel suspension for a motor vehicle with a vehicle wheel, which is fastened to a wheel carrier, wherein said wheel carrier is connected to said vehicle body via a first control arm and a second control arm, which are arranged at spaced locations from one another at said wheel carrier and extend in a mutually intersecting arrangement
Increasingly strict requirements have been imposed on the chassis of modern motor vehicles. Thus, greater accelerations and higher top velocities and higher velocities of driving in curves also entail higher safety requirements, and growing needs for comfort must be taken into account as well.
Single-wheel suspensions (half shafts) have increasingly come into use in motor vehicles because of their comparatively small space requirement, the lower weight and the fact that the wheels of the vehicle hardly affect each other. Low weight and negligible mutual effects of the wheels of the vehicle on one another, in particular, represent decisive advantageous properties of the single-wheel suspensions for road grip and during driving in curves with uneven road surface.
The king pin angle of the vehicle wheels, which is given, for example, during driving in a curve, plays an important role for directional stability and also for the life of the tires. The wheel of the vehicle that is the outer wheel in the curve always has a positive king pin angle. Attempts are made in prior-art axle kinematics to counteract the positive king pin angle of the vehicle wheel that is the outer wheel in the curve by applying an opposing motion by the wheel of the vehicle being brought into the direction of a negative king pin angle during inward deflection. One possibility of achieving this, for example, in a double wishbone wheel suspension is to make the upper wishbone shorter than the lower wishbone. If a parallel arrangement of the wishbone planes is favored, the inwardly acting lateral force generates pressing forces in the lower wishbones and tensile forces in the upper wishbones. However, this force couple causes a torque, which additionally increases the slope of the body (roll) generated by the centrifugal force in a curve, to develop at the vehicle body.
The tendency of the single-wheel suspension to enhance especially the roll of the vehicle is counteracted by the use of a stabilizer, which couples with one another the wheels of the vehicle that are located opposite each other, but it at least partly eliminates the advantages of the single-wheel suspension.
A wheel suspension must be able to optimally guide the motor vehicle, i.e., to hold it in its track and not to transmit forces and torques generated during braking and start as well as in curves or due to unevennesses of the road surfaces to the vehicle body or to transmit these in a greatly reduced form only in order to reduce or prevent roll or pitching of the vehicle body.
To reduce the tendency of a vehicle to roll, it is known that wishbones can be provided in a mutually intersecting arrangement. Thus, U.S. Pat. No. 6,173,978 B1 shows a wheel suspension for a motor vehicle with a vehicle wheel, which is attached to a wheel carrier. The wheel carrier is connected in this embodiment to the vehicle body via at least two control arms, which are arranged spaced from one another at the wheel carrier and extend in a mutually intersecting arrangement. The intersecting of the control arms in space can be illustrated by a projection of the control arms onto a common plain, because the intersecting does not mean that the control arms are connected to one another at the point of intersection.
Such a wheel suspension has the drawback that a relatively short instantaneous pole radius is formed. The change in the king pin angle and hence also the change in the track width of the wheels are very great during the inward and outward excursions of the wheels. Moreover, such a solution leads to considerable problems in terms of the directional stability of the vehicle on a road section with an uneven road surface, and it is therefore necessary to accept reduced driving safety and reduced comfort here. Moreover, it was possible to observe that a force component, which causes the wheel suspension to lift off, on the whole, from the road surface, is brought about during driving in a curve in case of an intersected arrangement of the wishbones according to U.S. Pat. No. 6,173,978 B1. Such serious shortcomings in terms of safety develop especially in case of sudden steering motions and at higher velocities and cannot, of course, be accepted.
The basic object of the present invention is to provide a wheel suspension for a motor vehicle, which has the advantages of mutually intersecting control arms but avoids the drawbacks of such an arrangement of the control arms and leads, in particular, to slight changes in the king pin angle and to a reduced tendency of the vehicle body to roll during the inward excursion of a vehicle wheel.
To accomplish the object described above, according to the present invention, a wheel suspension for a motor vehicle with a vehicle wheel, which is attached to a wheel carrier, is perfected by providing the wheel carrier connected to the vehicle body via at least two control arms, which are arranged at spaced locations from one another and extend in a mutually intersecting arrangement, such that the wheel suspension has a rotary control arm, which forms a connection by means of a coupling member between the vehicle body-side end of the first control arm and the wheel carrier and/or the wheel carrier-side end of the second control arm.
An inward deflection component, which increases driving safety, because it counteracts the lifting off of the vehicle wheel from the road surface, is now generated by a lateral force acting on the wheel of the vehicle.
The mutually intersecting control arms have an arrangement in space which, projected onto a common plane, shows a mutually intersecting shape when viewed from a direction of view at right angles to that plane.
The rolling motions of the vehicle body during driving in a curve are not fully eliminated with a solution according to the present invention, but they are at least reduced very substantially. The prior-art drawbacks already mentioned in the introduction, which occur in wheel suspensions with intersecting control arms, such as losses concerning driving safety and comfort, are avoided with the present invention. A wheel suspension is made available, which leads to a passive adjustment of the kinematic point of the vehicle body-side connection point of one of the control arms of the wheel suspension. Consequently, the body-side connection point of the first control arm of the wheel suspension is not fastened directly to the vehicle body, i.e., for example to the subframe or to the chassis, but to a rotary control arm, which in turn establishes a connection to the wheel carrier via a coupling member.
A very essential advantage of the present invention is especially that besides the reduction of the tendency of the vehicle body to roll, it is possible to eliminate altogether the stabilizer, which is usually necessary in single-wheel suspensions to connect the two mutually opposite wheel sides in order to achieve, for example, stabilization of the vehicle body during driving in curves, which was mentioned in the introduction. Thus, a cost-intensive component can be eliminated, which reduces the manufacturing costs of a wheel suspension according to the present invention as a whole. The elimination of the stabilizer necessary in usual single-wheel suspensions also leads, of course, to considerable reductions in the weight of the motor vehicle with the advantages resulting therefrom.
The reduction or elimination of the king pin angle of the vehicle wheels leads to a decisively reduced risk in extreme driving situations. Moreover, disturbing effects, which may develop during straight-line driving on uneven road surfaces due to changes in the king pin angle and the track width, can be avoided. The contact surface between the vehicle tire and the road surface is optimized in such a design. This in turn leads to improved static friction and hence to an increase in the driving safety of the vehicle.
According to a very simple embodiment variant of the present invention, the rotary control arm may be a wishbone having three connection points. A complicated mechanism for connecting the control arms is avoided due to the use of such a wishbone. A rocker pendulum may be used as a coupling member.
Another highly advantageous variant of the present invention can be seen in the use of a plurality of coupling members, which together form a deflecting linkage. The changes in the king pin angle at the vehicle wheel can be nearly completely eliminated with such a design. The vehicle wheel thus has an optimal contact with the road surface at any time and even in extreme situations and thus it increases the safety of the vehicle as a whole.
Since the individual coupling members of the deflecting linkage must be connected movably to one another, it is advantageous if suitable joints are used here. A sufficient selection of joints is available in the state of the art. Joints, such as ball sleeve joints, rotary slide bearings, sleeve-type rubber springs or other elastomer bearings shall be mentioned as examples only. The joints have one degree of freedom or two degrees of freedom.
Just as articulated connections are provided in the deflecting linkages, it is meaningful to also connect the rotary control arms to the vehicle body in an articulated manner. This also applies to the second control arm, which should be connected to the vehicle body on the vehicle body side via a joint.
Wishbones of a conventional design can be advantageously used as control arms for a wheel suspension in a solution according to the present invention. The wheel suspension presented is an single-wheel suspension, which is designed as a multiple control arm.
The present invention will be explained in more detail below on the basis of the drawings attached. The exemplary embodiments shown do not represent any limitation to the variants being shown, but are used only to explain some principles of wheel suspensions according to the present invention. Identical components or very similar components are designated by the same reference numbers. To make it possible to illustrate the mode of action according to the present invention, the figures show only highly simplified schematic views, in which components that are not essential for the present invention, such as springs, absorbers and other wheel suspension components, are not shown. However, this does not mean that such components are not present in a wheel suspension according to the present invention.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
In the drawings:
It shall be pointed out at the beginning that whenever a connection of components to the vehicle body 5 is referred to below, the fastening to the vehicle body may be carried out either directly or indirectly, an indirect connection being defined as the arrangement, for example, on a subframe.
When viewed in the longitudinal direction of the vehicle,
The third hinge 9 of the wishbone 6 is connected via a coupling member 10 to the wheel carrier-side end of the control arm 4 and to the wheel carrier 2. At least one hinge 11 is present at this connection point between the coupling member 10 and the control arm 4, and the coupling member 10 and the second control arm 4 may also be arranged by means of two hinges 11 (and 11′, not shown) located on a common axis. The vehicle body-side end of the control arm 4 is arranged on the vehicle body 5 by means of a hinge 12.
The coupling member 10 is directed approximately vertically in a non-deflected position in the view shown. The angles indicated in
The wishbone 6 thus creates a connection between the vehicle body-side end of the first control arm 3 and the wheel carrier-side end of the second control arm 4 or the wheel carrier 2 by means of a coupling member 10.
The components in the view shown in
A simplified view of a non-deflected wheel suspension with an arrangement of the rotary control arm 6 that is different from the design shown in
While the coupling member 10 and the wheel carrier-side end of the second control arm 4 are connected on a common axis extending through the hinge point 11 in the variant of a wheel suspension shown in
By contrast,
It is remarkable in
The wheel suspension shown in
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
Number | Date | Country | Kind |
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10 2006 004 959.4 | Feb 2006 | DE | national |
This application is a United States National Phase application of International Application PCT/DE2007/000202 and claims the benefit of priority under 35 U.S.C. § 119 of German Patent Application DE 10 2006 004 959.4 filed Feb. 1, 2006, the entire contents of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/DE07/00202 | 1/31/2007 | WO | 00 | 7/31/2008 |