DE102017204278B4 - Wishbone for a wheel suspension of a motor vehicle - Google Patents

Abstract

Wishbone (10) for a wheel suspension of a motor vehicle, comprising a control arm base (18) with at least one bearing point (16) on the wheel carrier side and with a front and rear body-side bearing (12, 14) viewed in the vehicle's longitudinal direction (x direction), the control arm base (18) being designed and/or dimensioned such that the control arm base (18) has a greater rigidity in the vehicle's transverse direction (y direction) than in the vehicle's longitudinal direction (x direction), the control arm base (18) having a strut (20) aligned in the vehicle's transverse direction (y direction) and firmly connected to the control arm base (18), and at least one material recess (22) penetrating the control arm base (18) in the vehicle's vertical direction (z direction) and forming a gap (26) in the outer contour (24) of the control arm base (18) is introduced into the control arm base (18). is characterized in that the gap (26) in the outer contour (24) of the handlebar base (18) is dimensioned such that exceeding a defined tensile and/or compressive force acting on the handlebar (10) in the vehicle longitudinal direction (x-direction) causes the gap (26) in the outer contour (24) of the handlebar base (18) to close.

Description

The invention relates to a wishbone for a wheel suspension of a motor vehicle according to the type specified in the preamble of patent claim 1.

Wishbones with two bearings on the body side are well known from the state of the art. The DE 43 30 103 A1 and the DE 20 2015 103 767 U1 referred to.

As a rule, a motor vehicle's wheel suspension should be soft in the vehicle's longitudinal direction, hereinafter also referred to as the x-direction, and stiff in the vehicle's transverse direction, hereinafter also referred to as the y-direction. This requirement, in particular the "longitudinal softness" desired in the vehicle's longitudinal direction, is primarily met by a corresponding design of the body-side bearings of the wheel suspension links.

In relation to a wheel suspension that comprises a wishbone with two body-side bearings, this means that the "longitudinal softness" of the wishbone is adjusted by a corresponding design of the radial and/or axial stiffness of the two body-side bearings.

As explained below, depending on the structural design of the wishbone, i.e. the front body-side bearing is arranged in front of the wheel center (=> first design) or the rear body-side bearing is arranged behind the wheel center (=> second design) or both bearings are arranged at approximately the same distance from the wheel center (=> third design), this can have a negative impact on the body shell (weight), steering angle, package or the transverse rigidity of the axle: while with the first design of the wishbone, due to the exposed position of the front bearing, the necessary rigid bearing connection of the front body-side bearing is only possible with increased weight and leads to a restriction of the steering angle, the second design of the wishbone with a body-side bearing located behind the wheel center proves to be disadvantageous for packaging reasons, since the installation space behind the wheel center is no longer available for other components. The third design has the effect that - since both bearings contribute to the longitudinal softness of the handlebar - the two bearings can also be designed to be relatively soft in the radial direction, with the result that the axle has limited transverse stiffness.

A generic wishbone for a wheel suspension of a motor vehicle, having all the features of the preamble of patent claim 1, is known from EN 10 2008 043 330 A1 known.

The invention is based on the object of developing a wishbone for a wheel suspension of a motor vehicle according to the type specified in the preamble of patent claim 1 in such a way that an optimized arrangement is made possible with regard to the criteria of bodyshell, package, maximum steering angle and axle transverse rigidity.

This problem is solved by the characterizing features of patent claim 1 in conjunction with its preamble features.

The subclaims represent advantageous developments of the invention.

In a known manner, the wishbone for a wheel suspension of a motor vehicle comprises a front pivot bearing on the body side, viewed in the longitudinal direction of the vehicle (x-direction), and a rear pivot bearing on the body side, spaced apart from it, wherein the two body-side bearings define a pivot axis about which the wishbone can pivot in relation to the motor vehicle body. Furthermore, in a known manner, the wishbone comprises at least one wheel carrier-side connection point spaced apart from the pivot axis in the transverse direction of the vehicle (y-direction), as well as a control arm base extending between the two body-side bearings and the wheel carrier-side connection point. The control arm base is designed and/or dimensioned in such a way that the control arm base is significantly stiffer in the transverse direction of the vehicle (y-direction) than in the longitudinal direction of the vehicle (x-direction). This means that the desired "longitudinal softness" of the wishbone is achieved by appropriate design and/or dimensioning of the control arm base.

This design of the wishbone has the positive effect that - since the "longitudinal softness" is now primarily represented by the wishbone - the x-position of the two body-side bearings, i.e. the position of the bearings in the vehicle's longitudinal direction relative to the wheel center, can be selected relatively freely, so that optimal positions for the bodyshell, package and steering angle can now be achieved.

The handlebar base has a basically triangular basic shape in the top view and the handlebar base is provided with a strut aligned in the transverse direction of the vehicle (y-direction) and firmly connected to the handlebar base. The strut is designed to be pressure-resistant in the transverse direction of the vehicle (y-direction) and flexible in the longitudinal direction of the vehicle (x-direction). In addition, at least one strut is integrated into the handlebar base, the handlebar base in the vertical direction of the vehicle (z-direction). A material recess is introduced that penetrates the outer contour of the handlebar base and forms a gap.

While the desired increased rigidity of the wishbone in the vehicle's transverse direction (y-direction) is ensured by the bracing which is designed to be flexurally and torsionally rigid in the vehicle's transverse direction (y-direction), the longitudinal softness of the wishbone in the vehicle's longitudinal direction (x-direction) is achieved by the bracing which is flexible in the vehicle's longitudinal direction (x-direction) in combination with the material recess introduced into the arm base and which forms a gap in the outer contour.

According to the invention, the gap in the outer contour of the handlebar is dimensioned in such a way that exceeding a defined tensile and/or compressive force acting on the handlebar in the longitudinal direction of the vehicle (x-direction) causes the gap in the outer contour of the handlebar base to close. This ensures, in a simple manner, a progressive characteristic curve in the stiffness of the handlebar base in the x-direction, i.e. the longitudinal direction of the vehicle.

Preferably, the material recess is designed in the form of a circular hole with a neck-shaped extension, whereby the neck-shaped extension extends to the outer contour and thus forms the gap in the outer contour. The longitudinal stiffness or softness can be easily adjusted via the number and size of the material recesses.

Preferably, the handlebar base is designed and/or dimensioned such that, for a vehicle longitudinal force of 1000N, the stiffness ratio of longitudinal stiffness (=> stiffness in x-direction) to transverse stiffness (=> stiffness in y-direction) of the handlebar base is as follows: $$\frac{L\ddot{a}nGssteieiGkeit}{QuersteieiGkeit}<0.3$$

Preferably, the bearings on the body are designed in such a way that they each have a bearing stiffness of > 5000N in the radial direction. The bearings, which are preferably designed as rubber-metal bearings, can thus be designed as identical parts, which is associated with corresponding cost and variance advantages.

Preferably, the handlebar base is designed and/or dimensioned such that the stiffness of the handlebar base has a progressive characteristic curve in the transverse direction of the vehicle (y-direction). In particular, different progressions of the longitudinal stiffness of the handlebar base can also be implemented, for example one in the direction of travel and one opposite to the direction of travel.

Another preferred embodiment provides that, viewed in the longitudinal direction of the vehicle (x-direction), the handlebar base at the front, i.e. in the area of the front body-side bearing, has a different longitudinal stiffness (=> stiffness in the x-direction) than at the rear, i.e. in the area of the rear body-side bearing. This advantageously enables improved coordination, e.g. with a handlebar in the upper handlebar level, the handlebar base is stiff at the front to ensure high braking stiffness and soft at the rear for reasons of edge comfort.

According to a further, unclaimed embodiment of the wishbone, the control arm base again has a substantially triangular basic shape in plan view and the control arm base is provided with a strut that is aligned in the transverse direction of the vehicle (y-direction), firmly connected to the control arm base, flexible in the x-direction and compression-resistant in the y-direction. In contrast to the embodiment already explained, the control arm base has an S-shaped outer contour when viewed in the transverse direction of the vehicle (y-direction) and at least one material recess that follows the S-shaped outer contour and penetrates the control arm base in the vertical direction of the vehicle (z-direction). In this embodiment, the bracing ensures the increased rigidity of the wishbone in the transverse direction of the vehicle (y-direction), while the elongation (tensile force) or compression (compressive force) of the S-shaped, curved outer contour resulting from the action of a force directed in the longitudinal direction of the vehicle ensures the longitudinal softness of the wishbone in the longitudinal direction of the vehicle (x-direction). The geometry of the curved outer contour allows the progressiveness of the longitudinal rigidity of the wishbone to be adjusted. This can involve any number of material recesses.

Preferably, the strut is connected to the handlebar base in a material-locking manner, in particular by welding. Alternatively, the handlebar base and the strut can also be formed as a single piece from metal or from a fiber-reinforced plastic.

Preferably, the bracing is designed in the form of a beam with a rectangular cross-section. Since the beam fulfils the function of a bending beam, which should be as flexible as possible in the longitudinal direction of the vehicle, the beam is arranged on the handlebar base as a raised cross-section. Other elements can also be mounted on the raised cross-section. elements of the wheel suspension, such as a damper or a stabilizer coupler, can be arranged.

By appropriately positioning the strut in the vehicle's longitudinal direction (x-direction), i.e. the strut is arranged centrally between the body-side bearings or the strut is arranged closer to the front or closer to the rear body-side bearing, the lateral force steering of the axle can also be influenced.

Another, unclaimed embodiment of the wishbone provides that the control arm base has a substantially trapezoidal basic shape in plan view and that a material recess is introduced into the control arm base, which penetrates the control arm base in the vertical direction of the vehicle (z-direction) and follows the outer contour of the control arm base and has four corner areas. The material recess is dimensioned in such a way that the corner areas form areas in the control arm base that tend to be bendable but pressure-resistant, which allow the control arm base to bend elastically in this area when a tensile or compressive force is applied in the longitudinal direction of the vehicle (x-direction). This means that in this embodiment, the increased rigidity of the control arm in the transverse direction of the vehicle (y-direction) is ensured by the closed, straight outer contour of the control arm base and the longitudinal flexibility of the control arm is ensured by the described bendable areas of the control arm base and a parallelogram-like elastic deformation.

In order to ensure a progressive characteristic curve of the rigidity of the wishbone in the vehicle's longitudinal direction, it is provided that one or more of the corner areas mentioned comprise two webs aligned with one another, forming a gap, viewed in the vehicle's longitudinal direction (x-direction), wherein the webs are dimensioned such that exceeding a defined tensile and/or compressive load acting on the link in the vehicle's longitudinal direction (x-direction) causes the gap defined by the two webs to close.

The desired longitudinal flexibility of the wishbone can be specifically adjusted using the number, size and shape of the material recesses in the control arm base. For example, positioning a material recess in the area of the wheel carrier connection point has the effect that the wheel carrier bearing experiences a higher delta offset in the vehicle's transverse direction (y-direction), with the result that the change in the wheel's toe angle when subjected to a longitudinal force, such as when braking, can be specifically influenced.

Preferably, the handlebar base is made of a fiber composite material. In addition to the low component weight, the design of the handlebar base from a fiber composite material has the advantage that, in addition to the geometric designs described, the longitudinal stiffness and the progressivity of the handlebar base can also be influenced by an appropriate choice of material or fiber orientation.

It is also conceivable that materials with hysteresis are incorporated into the control arm base, i.e. materials that, when a tensile or compressive force acts on the wishbone in the vehicle's longitudinal direction (x-direction), only react with increasing counterforce after a certain soft path.

For the sake of completeness, it is pointed out that within the scope of the present invention, the handlebar base can of course also be designed as a metal component.

Preferably, the material recess(es) in the handlebar base are filled or injected with an elastic material, e.g. rubber or another plastic.

Further advantages and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments shown in the figures.

• 1 eine schematische Darstellung einer ersten Ausführungsform eines erfindungsgemäßen Querlenkers für eine Radaufhängung eines Kraftfahrzeugs;
• 2 eine zweite, nicht beanspruchte Ausführungsform eines Querlenkers in schematischer Draufsicht, und
• 3 eine Draufsicht auf eine dritte, nicht beanspruchte Ausführungsform eines Querlenkers in einer schematischen Ansicht.

In the figures:

• 1 a schematic representation of a first embodiment of a wishbone according to the invention for a wheel suspension of a motor vehicle;
• 2 a second, not claimed embodiment of a wishbone in a schematic plan view, and
• 3 a plan view of a third, not claimed embodiment of a wishbone in a schematic view.

In the following description and in the figures, to avoid repetition, identical parts and components are identified by the same reference symbols unless further differentiation is necessary or useful.

1 until 3 show a wishbone for a wheel suspension of a motor vehicle, designated overall with reference number 10. The vehicle's longitudinal direction is designated with x, the vehicle's transverse direction with y and the vehicle's vertical direction with z.

According to the 1 In the embodiment shown, the control arm 10 is designed as a wishbone and comprises a front body-side bearing 12, viewed in the vehicle's longitudinal direction x, a rear body-side bearing 14, a wheel carrier-side bearing point 16 and a control arm base 18 extending between the body-side bearing points 12, 14 and the wheel carrier-side bearing point 16.

The two body-side bearings 12, 14, which are designed as rubber-metal bearings, are in this case designed as identical parts and each have a greater bearing rigidity in the radial bearing direction than in the axial bearing direction.

How 1 further shows, the control arm base 18 of the wishbone 10 comprises a strut 20 extending in the vehicle transverse direction y. The strut 20 is in this case firmly welded at its axial ends to the control arm base 18 of the wishbone 10. The strut 20 is designed to be compression-resistant in the vehicle transverse direction y and flexible in the vehicle longitudinal direction x. This ensures that the strut 20 ensures a high degree of rigidity of the wishbone 10 in the vehicle transverse direction y, while viewed in the vehicle longitudinal direction x, due to the flexible design of the strut 20, the strut 20 has a smaller influence on the longitudinal rigidity of the wishbone 10 viewed in the vehicle longitudinal direction x.

In order to achieve the desired longitudinal softness of the wishbone 10 in the vehicle's longitudinal direction x, the link base 18 of the wishbone 10 also comprises two material recesses 22 that penetrate the link base 18 in the vehicle's vertical direction z. The material recesses 22 are each designed in the form of a circular hole with a neck-shaped extension, wherein the neck-shaped extension of the two material recesses 20 each extends to the outer contour 24 of the wishbone 10 and forms a gap 26 in the outer contour 24 of the wishbone 10. The gap width is designated below with b.

The gap width b is dimensioned such that when a defined tensile or compressive force acting on the wishbone 10 in the vehicle's longitudinal direction x is exceeded, the gap 26 closes, so that a progressive stiffness curve of the link base 18 and thus of the wishbone 10 in the vehicle's longitudinal direction x is ensured. The various material recesses 22 can have different gap widths b. Depending on the desired stiffness curve, more or fewer material recesses 22 can be provided.

The described measures, namely bracing 20 and material recesses 22, have the effect that the control arm base 18 and thus the wishbone 10 have a significantly greater rigidity in the vehicle transverse direction y than in the vehicle longitudinal direction x.

Since the longitudinal softness is now realized according to the invention via the control arm base 18 of the wishbone 10, the position of the body-side bearings 12, 14 can be selected relatively freely, so that optimal positions for the body shell, package and steering angle can now be achieved.

Even in the 2 In the embodiment shown, the wishbone 10 is again designed as a triangular link. In addition, in accordance with the 1 shown embodiment - a strut 20 is welded to the handlebar base 18, which is designed accordingly and by means of which the required rigidity of the handlebar base 18 and thus of the wishbone 10 in the vehicle transverse direction y is ensured.

In contrast to the 1 In the embodiment shown, the outer contour 24 of the handlebar base 18 has an S-shaped profile when viewed in the transverse direction y of the vehicle. In addition, the handlebar base 18 has two material recesses 22 which are opposite one another in relation to the strut 20 and penetrate the handlebar base 18 in the vertical direction z of the vehicle and essentially follow the S-shaped outer contour.

While as under 1 As already explained, in the vehicle transverse direction y, the bracing ensures a high degree of rigidity of the control arm base 18 and thus of the wishbone 10, 2 In the embodiment shown, the longitudinal softness of the wishbone 10 in the vehicle's longitudinal direction x is ensured by the described S-shaped, curved design of the outer contour 24 and the elongation or compression thus made possible when a force is applied directed in the vehicle's longitudinal direction x.

According to the 3 In the embodiment shown, the wishbone 10 has a substantially trapezoidal basic shape in plan view. In addition, a relatively large material recess 22, which essentially follows the trapezoidal outer contour 24, is introduced into the control arm base 18 of the wishbone 10. The material recess 22, which in turn completely penetrates the control arm base 18 in the vehicle's vertical direction z, is dimensioned such that the corner regions 28 of the material recess 22 form regions in the control arm base 18 which tend to be bend-soft but pressure-resistant, which allow a defined elastic buckling of the control arm base 18 in this region when a tensile or compressive force is applied in the vehicle's longitudinal direction x.

To ensure a progressive stiffness curve of the control arm base 18 and thus of the wishbone 10 in the vehicle longitudinal direction x, 3 further shows - in a corner region 28 two webs 30 are arranged which are essentially aligned with one another in the vehicle's longitudinal direction x and form a gap 26. The webs 30 are designed in such a way that exceeding a defined tensile and/or compressive load acting on the wishbone 10 in the vehicle's longitudinal direction x causes the gap 26 defined by the two webs 30 to close.

Thus, in the 3 The embodiment shown ensures, through the measures described, namely on the one hand through the closed and straight outer contour as viewed in the vehicle transverse direction y and on the other hand through the bend-soft corner regions 28, that the wishbone 10 has a significantly greater rigidity in the vehicle transverse direction y than in the vehicle longitudinal direction x.

Claims (8)

Wishbone (10) for a wheel suspension of a motor vehicle, comprising a control arm base (18) with at least one bearing point (16) on the wheel carrier side and with a front and rear body-side bearing (12, 14) viewed in the vehicle's longitudinal direction (x direction), the control arm base (18) being designed and/or dimensioned such that the control arm base (18) has a greater rigidity in the vehicle's transverse direction (y direction) than in the vehicle's longitudinal direction (x direction), the control arm base (18) having a strut (20) aligned in the vehicle's transverse direction (y direction) and firmly connected to the control arm base (18), and at least one material recess (22) penetrating the control arm base (18) in the vehicle's vertical direction (z direction) and forming a gap (26) in the outer contour (24) of the control arm base (18) is introduced into the control arm base (18). is characterized in that the gap (26) in the outer contour (24) of the handlebar base (18) is dimensioned such that exceeding a defined tensile and/or compressive force acting on the handlebar (10) in the vehicle longitudinal direction (x-direction) causes the gap (26) in the outer contour (24) of the handlebar base (18) to close. Wishbone (10) for a motor vehicle according to Claim 1 , characterized in that the material recess (22) is designed in the form of a circular hole with a neck-shaped extension, wherein the neck-shaped extension extends to the outer contour (24) and thus forms the gap (26) in the outer contour (24). Wishbone (10) for a motor vehicle according to Claim 1 , characterized in that the handlebar base (18) is designed and/or dimensioned such that the handlebar base (18) has a stiffness ratio of: $$\frac{SteieiGkeitinFaHrzeuGl\ddot{a}nGsricHtunG\left(x-RicHtunG\right)}{SteieiGkeitinFaHrzeuGl\ddot{a}nGsricHtunG\left(y-RicHtunG\right)}<0.3$$

having. Wishbone (10) for a motor vehicle according to Claim 1 , characterized in that the front and rear body-side bearings (12, 14) have a bearing stiffness of > 5000 N/mm. Wishbone (10) for a motor vehicle according to one of the Claims 1 until 4 , characterized in that the handlebar base (18) is designed and/or dimensioned such that the rigidity of the handlebar base (18) is progressive in the vehicle longitudinal direction (x-direction). Wishbone (10) for a motor vehicle according to one of the preceding claims, characterized in that the control arm base (18) is designed with different stiffness in the region of the front body-side bearing (12) and in the region of the rear body-side bearing (14) viewed in the vehicle longitudinal direction (x-direction). Wishbone (10) according to one of the preceding claims, characterized in that the material recess(es) (22) is/are filled with an elastic material. Wishbone (10) for a motor vehicle according to one of the preceding claims, characterized in that the control arm base (18) is made of a fiber composite material.

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