DE102015211180A1 - Wheel suspension for a motor vehicle - Google Patents

Abstract

The invention relates to a wheel suspension (1) for a motor vehicle, comprising at least - a wheel carrier (2) defining an axis of rotation (8) for a wheel (3), - a spring (5), - a shock absorber (4) the spring (5) and the shock absorber (4) at least indirectly connect the wheel carrier (2) with a vehicle body, supported on the wheel carrier (2) and with respect to the axis of rotation (8) on opposite sides along the X-axis (X) of the motor vehicle are arranged. In order to provide a wheel suspension in which the torsional vibration behavior of the wheel carrier with respect to the Y axis of the vehicle is optimized, it is provided according to the invention that a force action line (10.1, 10.2, 10.3, 10.4) of the spring (5) from a center line (7th ) of the spring (5) deviates.

Description

The invention relates to a wheel suspension for a motor vehicle having the features of the preamble of claim 1.

In modern motor vehicles, all wheels are connected via a suspension with the body or the chassis of the vehicle. The respective wheel and a wheel carrier receiving this are part of the unsprung mass, which follows more or less the height profile of the respective running surface, while body and chassis form parts of the sprung mass, which should be at least largely decoupled from sudden movements of the unsprung mass. Various forms of springs are known in the art. In today's vehicles, above all, either coil springs (for example made of steel) or pneumatic springs are used. The effect of the springs is complemented by shock absorbers, which convert the energy of the movement between sprung and unsprung mass into heat and thus prevent unwanted vibration behavior. Since the motion of the sprung mass with respect to the unsprung mass is predominantly vertical, normally also springs and shock absorbers are oriented substantially vertically. In addition, the wheel carrier is connected to the chassis with more or less horizontally extending arms (eg wishbone or trailing arm). In addition to suspensions in which the spring is at least indirectly connected to the wheel, such designs are known in which the spring acts on a handlebar. The same applies to the shock absorber.

In one type of suspension system used particularly in rear-wheel or all-wheel drives, a shock absorber (with respect to the vehicle's X-axis) is located in front of the drive shaft and the spring is behind the drive shaft, or vice versa; H. Spring and shock absorbers are with respect to the X-axis, d. H. the longitudinal axis, on opposite sides of the drive shaft. Both the spring and the shock absorber are connected to the wheel carrier. A problem that arises here is the adjustment of the vibration behavior of the wheel carrier about the transverse axis (Y-axis) of the vehicle. This is usually influenced by the spring force, the position of the spring, the damper force and the position of the damper. However, the spring and damper forces can vary only to a limited extent, as they are determined inter alia by aspects of driving safety and driving comfort. The positions of spring and damper, more precisely, their distances from the axis of rotation of the wheel, can often vary for structural reasons hardly.

The US 4,903,985 A shows a suspension with a strut, which includes a shock absorber and arranged around a coil spring. The shock absorber is arranged on an inner side of a wheel carrier and connected thereto. In order to avoid contact between the shock absorber and spring at an extreme inclination of the strut, it is provided that the force line of action of the spring is offset and / or tilted with respect to its center line within the YZ plane of the vehicle.

The US 3,573,880 A shows a suspension for motor vehicles with a shock absorber, which is arranged between a frame of the vehicle and a wheel carrier, and a coil spring arranged thereon, which surrounds the shock absorber, arranged eccentrically with respect to the same and is connected at an upper end to the vehicle frame. Both shock absorber and spring are arranged inside the cross member. At a lower end, the spring is arranged in a receptacle, which in turn is mounted on the shock absorber so that it can rotate eccentrically with respect to it. In some embodiments, the spring is attached to the vehicle frame so that it is bent outwardly under normal load.

The DE 202 21 473 U1 discloses a suspension with a wheel-guiding strut comprising a shock absorber and a helical compression spring disposed therearound. In order to compensate for transverse forces, it is provided that the force action line of the spring runs askew to the center line of the shock absorber. The center line of the spring is in the unloaded state in a plane transverse to the vehicle direction S-shaped and long in a plane to the vehicle direction S-shaped or C-shaped.

The GB 1 198 713 A shows a suspension with a strut, which has a shock absorber and a concentrically arranged around this coil spring. In order to compensate for bending moments acting on the shock absorber by the wheel, it is provided that the spring is slightly bent in a relaxed state. Thus, when installed between two parallel shots mounted on the shock absorber, it exerts a compensating bending moment on the shock absorber.

The DE 10 2006 010 054 A1 shows a suspension with spring adjustment. Here, a helical compression spring, which is arranged between the vehicle body and wheel carrier, arranged between two spring plates, of which at least one has a footprint, which is inclined relative to a spring center line perpendicular plane. In addition, the force line of action of the spring is shifted parallel to the center line, causing overall results in a combination of inclination and lateral displacement of the force line of action. The two spring plates are rotatably arranged, so that adjust the spatial position of the line of action and thus adjust the spring stiffness of the suspension.

The summary of CN 201982554 U describes a coil spring, in particular for suspension. A central part of the spring has turns with a larger diameter, which decreases towards the two ends. Furthermore, the centers of the turns towards the ends are offset laterally relative to the middle part.

The DE 10 2004 058 698 B3 discloses a suspension with a vehicle body and on this via a handlebar assembly movably articulated wheel with a wheel. A helical compression spring is supported, on the one hand, on the vehicle body and, on the other hand, on the wheel carrier or on the handlebar arrangement, wherein the spring rigidity of the vehicle body support related to the point of contact of the wheel can be changed in a controlled manner. This is achieved, for example, in that a helical compression spring is used in which the force action line deviates from the geometric spring center line and the spring can be rotated in a controlled manner. In this case, in particular, an S-shaped helical compression spring can be used.

The EP 0 852 188 B1 shows a telescopic suspension strut with a fixed part and a moving part and a flexible bellows with a chamber portion which is connected to a closure part, which in turn is attached to the fixed part, and a Rollbalgbereich, which at one end with an eccentrically offset piston the moving part is attached. The closure part is inclined with respect to a longitudinal axis of the fixed part. From a corresponding inclined position of the Rollbalgbereich is pulled by the piston in the direction of the longitudinal axis, whereby a shearing force. This is used to compensate for lateral forces that can act on the strut.

The EP 2 374 639 B1 discloses a torsion beam axle having two drawn longitudinal wings connected by a tread, each longitudinal wing being associated with a coil spring which is supported at its lower end to the longitudinal rocker and at its upper end to a vehicle body. The coil spring is mounted inclined between upper and lower spring bearings and arranged so that the force line of action has a different inclination angle during compression and rebound. An upper piercing point of the force line of action by an upper spring bearing is located closer to the spring centerline with respect to a lower piercing point of the force line of action by a lower spring bearing, the two piercing points being located opposite to the spring center line and the force action line being more inclined during compression on a bend outside during compression is as on a curve inside the rebound.

The summary of KR 2004 0012 400 A discloses a coil spring for suspensions in vehicles. Here, the diameter of the material used for the coil spring alternates between a first and a second diameter. The first diameter material is positioned on one side of the spring and the second diameter material on the other side. As a result, the center axis of the coil spring can be matched to a load axis.

In view of the prior art presented, the development of a wheel suspension with improved vibration behavior of the wheel carrier around the Y-axis of the vehicle still offers room for improvement.

The invention has for its object to provide a suspension available in which the torsional vibration behavior of the wheel carrier is optimized with respect to the Y-axis of the vehicle.

According to the invention the object is achieved by a suspension with the features of claim 1, wherein the dependent claims relate to advantageous embodiments of the invention.

It should be noted that the features listed in the following description as well as measures in any technically meaningful way can be combined with each other and show other embodiments of the invention. The description additionally characterizes and specifies the invention, in particular in connection with the figures.

The invention provides a wheel suspension for a motor vehicle. As motor vehicles in particular car or truck come into question. It may be the suspension of a front or rear wheel. In particular, it may be the suspension of a driven rear wheel. The suspension comprises a wheel carrier which defines an axis of rotation for a wheel, a spring and a shock absorber. The wheel carrier or stub axle is provided in a known manner to receive the wheel, which is thus rotatably mounted in the installed state with respect to the same. The spring is used to decouple the sprung mass of the vehicle, so usually the body and the chassis of the unsprung mass, part of which is the wheel carrier. It can in principle assume any design that is known in the art. The shock absorber is used in a known manner to dampen vibrations of the sprung mass against the unsprung mass. He also can basically assume any known in the prior art design, for example. It may be designed as a hydraulic shock absorber.

The spring and the shock absorber connect the wheel carrier at least indirectly to a vehicle body. "Vehicle body" here serves as a collective term for the body, the chassis and possibly a subframe.All of these components are attributable to the sprung mass.The connection can be in each case directly or indirectly, ie with the interposition of at least one other component, given the connections can be given such that the spring is supported on the vehicle body or on the wheel and held there in the operating state by your bias, where it is for example included in a kind of spring plate, which in turn is attached to the vehicle body or on the wheel. The connection can thus be provided indirectly by an intermediate spring receptacle (eg spring plate) It is also possible for the spring and / or the shock absorber to be articulated on the vehicle body or on the wheel carrier so that a certain pivoting movement is possible. According to the invention, the spring and the shock absorber are supported on the wheel carrier, the Ab support in turn via an intermediate receiving element such as a spring plate can be given.

In any case, the spring and the shock absorber are arranged with respect to the wheel rotation axis on opposite sides along the X-axis of the motor vehicle. Ie. either the shock absorber along the X-axis is arranged in front of the wheel axis of rotation and the spring behind the Raddrehachse or the shock absorber is located behind the Raddrehachse and the spring in front of the Raddrehachse. In this case, the forces acting on the wheel carrier by spring and shock absorbers cause torques with respect to the axis of rotation of the wheel, which can generally lead to a (limited) rotation of the wheel carrier with respect to this axis of rotation.

According to the invention, a force line of action of the spring deviates from a center line of the spring. Ie. In general, the force line of action may be shifted and / or inclined with respect to the center line. The center line or spring center line corresponds with a cylindrical coil spring of the cylinder axis. For non-cylindrical springs, in which z. For example, if the individual coils have different diameters and / or are offset from one another, a kind of center of each individual coil is normally constructed and said centers are connected by an imaginary line which then forms the center line. While the center line in the unloaded state may possibly be curved, springs known in the prior art are normally designed such that a straight center line exists in the unloaded state. However, the invention is expressly not limited to coil springs, but it can also other types of springs such as pneumatic springs are used.

With a force action line deviating from the center line as described, it is possible to achieve a change in the torque generated by the spring without changing the installation position or dimensioning of the spring. Thus, on the one hand, the static torque which the wheel carrier experiences through the spring changes. From a dynamic point of view, however, the vibration behavior of the wheel carrier is also influenced. In the described suspension system, the shock absorber on the one hand and the spring on the other hand exert forces on the wheel, which lead to torques. These in turn affect the vibration behavior and in particular the resonance frequency (or natural frequency) of the wheel carrier with respect to a torsional vibration about the axis of rotation of the wheel. Thus, it is possible to change the resonant frequency by using only one spring with a different force line of action. As a result, a much better tuning is possible than, for example, by a change in position of the spring. As already indicated, such a change in position is also often set for design reasons, which thus also exist with regard to the influence of the torque. With the described deviating force line of action, these limitations can be overcome.

In general, the torque caused by the spring is calculated as M → = r → × F → or M = r · F · sinα

Here, M is the torque, F is the force caused by the spring, r is the distance of the point of application of the force from the axis of rotation and α is the angle between F and r. As can be seen from the above equation, only the component of force which is perpendicular to the distance vector or only that component of the distance vector which is perpendicular to the force counts for the magnitude of the torque. As will be explained below, by the deviation of the force line of action on the one hand, the distance r, on the other hand, but also the angle α can be changed. Both influence the torque.

According to one embodiment, the force line of action with respect to the center line is along the X-axis. Axis shifts. That is, the position of the line of force of action along the longitudinal axis of the vehicle deviates from the position of the center line, while possibly the alignment of the force line of action remains parallel to the center line. This has the consequence, in comparison to a spring with a central force line of action, that the distance of the point of application of the force from the wheel axis of rotation changes. Thus, the torque changes correspondingly (assuming that the amount of force remains the same). In one case, the force line of action may be farther from the wheel axis of rotation than the center line, increasing the lever arm and thus the torque. In another case, the force line of action is closer to the wheel axis of rotation than the center line, reducing the lever arm and thus the torque.

According to a further embodiment, the force action line is tilted or inclined with respect to the center line in the X-Z plane. In other words, the projection of the force action line on the X-Z plane is at an angle to the projection of the center line. Mathematically, this can also be understood as rotation about the Y-axis. This also affects the torque generated by the spring with respect to the axis of rotation. This results on the one hand compared with a spring in which the force line of action coincides with the center line, a changed lever arm, on the other hand, the angle between the lever arm and leverage changes. The latter may even cause the torque to increase, although the lever arm shortens. If, for example, in the case of a spring which attaches to the wheel carrier below the wheel rotation axis, the force action line is tilted so that its upper end is inclined away from the axis of rotation, its lower end, on which the force acts on the wheel carrier, can approach the axis of rotation, what a lower torque speak. However, at the same time, the angle between the force and the lever arm (i.e., the distance vector from the axis of rotation) becomes less acute, so that, in total, a larger torque actually results. Correspondingly, conversely, despite a longer lever arm, a lower torque results here in a force action line which is inclined towards the axis of rotation. These considerations apply of course only in the event that the spring attaches below the Raddrehachse; in the case of springs which act at height or above the axis of rotation, other conditions apply, which will not be discussed in detail here.

While in terms of torque adjustment, a sloped force line of action allows a similar adjustment to a displaced force line of action, skewing will cause a component of force to vary along the X axis. Depending on the configuration of the other components of the suspension, this can be a desired effect or an effect that you want to avoid.

It should be noted that the force line of action may in principle be offset simultaneously in the X direction and inclined in the X-Z plane.

The above-described embodiments, d. H. the displacement and tilt affect positional deviations within the X-Z plane. Although this is not necessary according to the invention, this may be accompanied by other positional deviations outside the X-Z plane. Thus, for example, the force action line could additionally be displaced along the Y-axis or tilted within the Y-Z plane with respect to the center line.

According to one embodiment, a lower end of the spring and / or a lower end of the shock absorber along the Z-axis is arranged at the height of an installation position of the wheel. In other words, the corresponding lower end is disposed adjacent to the installation position of the wheel. It is thus deeply positioned. As a result, on the one hand, a relatively long spring can be used. This means that the maximum possible spring travel in the operating state in relation to the total length of the spring is smaller. In particular, it is easier to prevent that the spring is fully compressed in the operating state. Even with a shock absorber, it may be advantageous if a larger space is available for this.

According to a further embodiment, the lower end of the spring and / or the lower end of the shock absorber are arranged lower than the axis of rotation of the wheel.

In this way, even if the spring or the shock absorber are arranged relatively low on the vehicle body, there is enough space for the installation of said elements, which normally also an unintentionally strong inclination of the spring or the shock absorber can be avoided. Too strong an inclination may affect the absorption of vertical forces on the one hand, on the other hand, the mediated by the spring lateral forces may be too strong. The wheel carrier may in this embodiment have a kind of lower arm, on which the lower end of the spring and / or the lower end of the shock absorber are supported.

Basically, the spring can be realized by different tree shapes, for example. As a pneumatic spring. According to another embodiment, the spring is designed as a helical spring. It typically consists of spring steel or fiber composite plastic. A coil spring, in which the force line of action and the Center line is usually straight and cylindrical in relaxed state. In the context of the invention, however, come into question designs in which, for example, the radius of curvature of the individual turns varies or the center line is curved in a relaxed state.

According to such an embodiment, the spring is S-shaped. This refers to the shape of the spring or its center line in a relaxed state. As noted above, such springs are normally straight in the tensioned state. However, in the tensioned state, they have a force action line that does not coincide with the center line but is at an angle to it. A similar effect can be achieved with pneumatic springs with a rolling bellows made of a fiber-rubber composite. In this case, an angled to the geometric center line of the pneumatic spring force line of action is achieved by the asymmetric design of the rolling bellows.

According to another embodiment, the spring is C-shaped. Again, this statement refers to the spring or its center line in a relaxed state. When stretched, such a spring is usually straight. In this type of spring, the force line of action is normally parallel to the centerline, but laterally offset therefrom.

Further advantageous details and effects of the invention are explained in more detail below with reference to exemplary embodiments illustrated in the figures. Show it

1 a schematic representation of a first suspension according to the invention; and

2 a schematic representation of a second suspension according to the invention.

In the different figures, the same parts are always provided with the same reference numerals, which is why these are usually described only once.

1 shows a schematic representation of a suspension according to the invention 1 of a motor vehicle, for example a passenger car. The plane of the drawing here corresponds to the XZ plane of the vehicle. A wheel 3 This is a rotation axis 8th rotatable on a wheel carrier 2 stored. The wheel carrier 2 is on the vehicle side connected via links, not shown here with a (also not shown) chassis. In a lower area of the wheel carrier 2 are outriggers 6 arranged in one piece with the wheel carrier 2 trained or attached to this (for example, screwed) can be.

A coil spring 5 , which consists for example of spring steel, is supported by an upper end 11 on a vehicle body, not shown here (the chassis, a body or a subframe) from. The coil spring 5 is here seen along the X-axis of the vehicle in front of the axis of rotation 8th arranged and runs at right angles to the X-axis. With a lower end 12 she leans on one of the outriggers 6 from. A pneumatic or hydraulic shock absorber 4 supports with an upper end 13 also on the vehicle body and with a lower end 14 on one of the outriggers 6 from. The shock absorber 4 is here along the X axis seen behind the axis of rotation 8th arranged and also runs at right angles to the X-axis. The lower ends 12 . 14 as well as the booms 6 are here with respect to the Z-axis at the height of an installation position of the wheel 3 and are located much lower than its axis of rotation 8th ,

The drawing shows the force action line 9 the one by the shock absorber 4 developed force and an associated effective lever arm r _D , so the vertical to the damper force component of the distance vector of the Raddrehachse 8th , A through the shock absorber 4 torque caused corresponds to the product of damper force and effective lever arm r _D. Also marked is a midline 7 the coil spring 5 , In a conventional, non-inventive spring this corresponds to the force line of action. A spring caused by the spring corresponds to the product of spring force and effective lever arm r _F0 .

In the present example, the force action lines 10.1 . 10.2 of coil springs 5 represented, which are C-shaped in the relaxed state. This leads to a shift of the force action line 10.1 . 10.2 opposite the midline 7 the coil spring 5 , so that with appropriate orientation of the coil spring 5 in one case a force line of action 10.1 which results farther from the wheel rotation axis 8th is removed, resulting in a larger effective lever arm r _F1 . This also increases the torque. In another case, a force line of action results 10.2 closer to the axis of rotation 8th is arranged, resulting in a smaller lever arm r _F2 . In conjunction with the (unchanged) torque of the shock absorber 4 can be by these measures the vibration behavior of the wheel carrier 2 with respect to the axis of rotation 8th to adjust. Here, the sizing and the position of the coil spring 5 basically not be changed, ie the constructive intervention is minimal, as in an existing system essentially a coil spring 5 is used with another force line of action. Basically, the different force lines could 10.1 . 10.2 with one and the same coil spring 5 be realized, which would have to be rotated by 180 °.

2 shows an alternative embodiment of a suspension 1 which are essentially the ones in 1 shown and therefore will not be explained again in detail. In this embodiment, however, a coil spring 5 inserted, which is S-shaped in the relaxed state, so that one opposite the center line 7 in the XZ-plane inclined force line of action 10.3 . 10.4 results. The figure shows an example of a force action line 10.3 , in the upper area to the axis of rotation 8th is inclined. This results in a shortened effective lever arm r _F3 , which leads (with the same amount of force magnitude) to a lower torque. Also is a force line of action 10.4 shown at the top of the axis of rotation 8th is inclined. This leads to a prolonged effective lever arm r _F4 and an associated increased torque. Again, the different force lines 10.3 . 10.4 with one and the same coil spring 5 be realized, which is rotated in each case by 180 °. While with regard to the adjustment of the torque, the inclined force action lines shown here 10.3 . 10.4 allow a setting similar to the one in 1 shown shifted force lines of action 10.1 . 10.2 , the skewing leads to force components along the X-axis which, depending on the embodiment, may be desirable or undesirable.

In each of the embodiments shown here, an influence on both the static torque that the coil spring 5 caused, as well as the vibration behavior of the wheel carrier 2 with respect to the axis of rotation 8th be achieved without major redesigns of the entire suspension 1 would be necessary. Rather, it is enough, a suitable coil spring 5 select and install them in the correct orientation.

LIST OF REFERENCE NUMBERS

1

 Arm

2

 wheel carrier

3

 wheel

4

 shock absorber

5

 coil spring

6

 boom

7

 center line

8th

 axis of rotation

9, 10.1-10.4

 Line of action

11, 13

 top end

12, 14

 lower end

r _D , r _F0 , r _F1 , r _F2 , r _F3 , r _F4

effective lever arm

X

 X axis

Z

 Z-axis

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4903985 A [0004]
• US 3573880A [0005]
• DE 20221473 U1 [0006]
• GB 1198713A [0007]
• DE 102006010054 A1 [0008]
• CN 201982554 U [0009]
• DE 102004058698 B3 [0010]
• EP 0852188 B1 [0011]
• EP 2374639 B1 [0012]
• KR 20040012400 A [0013]

Claims (8)

Wheel suspension ( 1 ) for a motor vehicle, at least comprising - a wheel carrier ( 2 ), which has a rotation axis ( 8th ) for a wheel ( 3 ), - a spring ( 5 ), - a shock absorber ( 4 ), the spring ( 5 ) and the shock absorber ( 4 ) the wheel carrier ( 2 ) at least indirectly connect to a vehicle body, on the wheel ( 2 ) and with respect to the axis of rotation ( 8th ) are arranged on opposite sides along the X axis (X) of the motor vehicle, characterized in that a force action line ( 10.1 . 10.2 . 10.3 . 10.4 ) the feather ( 5 ) from a centerline ( 7 ) the feather ( 5 ) deviates. Wheel suspension according to claim 1, characterized in that the force line of action ( 10.1 . 10.2 ) with respect to the center line ( 7 ) is displaced along the X-axis (X). Wheel suspension according to claim 1 or 2, characterized in that the force line of action ( 10.3 . 10.4 ) with respect to the center line ( 7 ) is tilted in the XZ plane. Wheel suspension according to one of the preceding claims, characterized in that a lower end ( 12 ) the feather ( 5 ) and / or a lower end ( 14 ) of the shock absorber ( 4 ) along the Z-axis (Z) at the height of an installation position of the wheel ( 3 ) are arranged. Wheel suspension according to one of the preceding claims, characterized in that a lower end ( 12 ) the feather ( 5 ) and / or a lower end ( 14 ) of the shock absorber ( 4 ) lower than the axis of rotation ( 8th ) are arranged. Wheel suspension according to one of the preceding claims, characterized in that the spring ( 5 ) is designed as a helical spring. Wheel suspension according to claim 6, characterized in that the spring ( 5 ) Is S-shaped. Wheel suspension according to claim 6, characterized in that the spring ( 5 ) Is C-shaped.

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