Counter-steering vehicle rear axle

Abstract

Counter-steering motor vehicle rear axle (1), in which, under the action of a lateral force (F) on a wheel (R) on the outside of the curve and fastened to a wheel carrier (3), a rotational movement of the wheel carrier (3) about a virtual axis (A) in the direction of a toe-in (γ) occurs, wherein the virtual axis (A), when projected onto a plane extending in the vehicle's longitudinal direction, is inclined at an angle (α) at ​​least in the direction of travel (FR), characterized in that the virtual axis (A) runs below a wheel center point (M) and has an intersection point (6) with a wheel contact plane (E), which, viewed in the direction of travel (FR), lies behind a wheel contact point (5), wherein the wheel carrier (3) is connected to an axle body (2) extending transversely to the vehicle's longitudinal direction, wherein the wheel carrier (3), in a view in the longitudinal extension of the axle body (2), is provided with at least one belt-like connection around the axle body (2) extending material thickening (30),which has at least two material weakenings (31a, 31b) transversely to its longitudinal extent, of which a front material weakening (31a) is higher than a rear material weakening (31b) when viewed in the direction of travel (FR) and measured from the wheel contact plane (E).

Description

[0001] The invention relates to a counter-steering motor vehicle rear axle with the features of the preamble of patent claim 1.

[0002] Simply constructed vehicle rear axles, especially rigid or semi-rigid axles, are particularly prone to oversteering when cornering under the influence of lateral forces, unlike axles with independent wheel suspension. To remedy this disadvantage, it is known to design such rear axles in such a way that the outer wheel of the curve is moved into toe-in under the influence of lateral forces.

[0003] This results in understeering of the rear axle when cornering, which contributes to more stable dynamic handling.

[0004] DE 101 26 192 A1 discloses a rigid rear axle in which, under the influence of a lateral force on a wheel on the outside of the curve, the wheel carrier, and thus the wheel, rotates around a virtual axis in the direction of toe-in. Specifically, the wheel carriers are each connected to the rigid axle via a weakened material offset against the direction of travel. This creates an approximately vertically arranged, virtual pivot axis around which the respective wheel carrier can pivot under the influence of lateral force.

[0005] DE 10 2008 031 123 A1 describes a counter-steering vehicle rear axle with the features of the preamble of patent claim 1. Specifically, the wheel carriers are each connected to an axle body via a helmet-shaped support member and reinforcing plates. Several flexible areas and recesses are arranged in the support member in such a way that the wheel carrier pivots around a virtual axis under the influence of a lateral force when cornering and enters toe-in.

[0006] The virtual axis is inclined on the one hand in the direction of travel and on the other hand in the direction of the vehicle's longitudinal center plane.

[0007] Finally, DE 10 2009 024 831 A1 discloses a twist-beam rear axle with two trailing arms, each of whose rear end sections is connected to a node element. The node elements support wheel carriers and serve to insert an end section of a cross member. The cross member is designed as a hollow profile at its end sections, the profile cross-sections of which are fully enclosed by corresponding receptacles of the node elements. The trailing arms are stiffer on their side facing the axle center than on the wheel side, so that a slight deformation in the direction of toe-in is caused under the influence of lateral forces.

[0008] The present invention is based on the object of providing an alternative motor vehicle rear axle with which good driving dynamics properties can be achieved, in particular when cornering.

[0009] This object is achieved by the features of patent claim 1. Advantageous embodiments or further developments of the invention can be found in the dependent claims.

[0010] The invention is based on a counter-steering motor vehicle rear axle in which, under the action of a lateral force on an outer wheel attached to a wheel carrier, a rotational movement of the wheel carrier about a virtual axis in the direction of toe-in occurs. When projected onto a plane running in the vehicle's longitudinal direction, the virtual axis is inclined at an angle in the direction of travel.

[0011] The invention proposes that the virtual axis runs below a wheel center point and has an intersection point with a wheel contact plane, which lies behind a wheel contact point when viewed in the direction of travel.

[0012] Simulations and tests conducted by the applicant have shown that in this way a high camber and toe-in stiffness of the rear axle could be achieved, which enables good driving behaviour to be achieved.

[0013] According to an advantageous embodiment of the inventive concept, the virtual axle is inclined at an angle that (measured from a horizontal plane) lies in a range of approximately 40° to 50°. An inclination in such an angular range could also contribute to good driving characteristics of the rear axle.

[0014] In particular, it was shown that the best values ​​were achieved when the virtual axis was tilted at an angle of approximately 45 degrees.

[0015] If, according to another embodiment of the inventive concept, the virtual axis runs approximately parallel to a wheel center plane, this can contribute to the simple and compact construction of the motor vehicle rear axle.

[0016] According to the invention, the wheel carrier is further connected to an axle body extending transversely to the vehicle's longitudinal direction. In a view along the longitudinal extension of the axle body, the wheel carrier is provided with at least one thickened material extending around the axle body in a belt-like manner.

[0017] According to the invention, the material thickening in turn has at least two material weakenings transversely to its longitudinal extent, of which a front material weakening is higher than a rear material weakening when viewed in the direction of travel and measured from the wheel contact plane.

[0018] According to another expedient development, the belt-like material thickening can be arranged on a side of the wheel carrier facing the vehicle's longitudinal center plane.

[0019] In this way, space can be created for the wheel and brake on the assembly side.

[0020] It is beneficial to a simple and compact design of the motor vehicle rear axle if the wheel center is arranged above the axle body, with an imaginary connecting line between the wheel center and a longitudinal axis of the axle body running approximately vertically.

[0021] The invention also claims protection for a motor vehicle which is equipped with a rear axle according to the invention.

[0022] The motor vehicle can be further developed in such a way that the axle body of the motor vehicle rear axle is connected in the area of ​​a wheel carrier to a leaf spring which runs like a belt around the axle body and in the longitudinal direction of the vehicle and which is fastened to the motor vehicle body.

[0023] This increases the stability of the rear axle in a simple way and at the same time creates a spring effect.

[0024] A preferred embodiment of the invention is illustrated in the figures and explained in more detail in the following description. Like reference numerals refer to like, comparable, or functionally identical components, whereby corresponding or comparable properties and advantages are achieved, even if a repeated description is omitted.

[0025] They show, schematically Fig. 1 the representation of a rear axle from above, Fig. 2 a side view of the rear axle according to view II of Fig. 1, Fig. 3 a side view of the rear axle according to view III of Fig. 1, Fig. 4 a sectional view according to section IV of Fig. 3, Fig. 5 a sectional view according to section view V of Fig. 3, Fig. 6 a perspective view of the rear axle, also showing part of the body of the motor vehicle, Fig. 7 the left part of the rear axle, seen from behind in the direction of travel, under lateral force when cornering and Fig. 8 a representation of the rear axle according to view VIII of Fig. 7.

[0026] First, the Fig. 1 referred to.

[0027] This figure shows a motor vehicle rear axle 1. The motor vehicle rear axle 1 comprises a cylindrical axle body 2, which is preferably made of carbon fiber reinforced plastic. The axle body 2 has a longitudinal axis 20, which extends approximately perpendicular to a vehicle longitudinal center plane FM.

[0028] FR indicates a normal direction of travel.

[0029] On each side, the axle body 2 is connected to a wheel carrier 3, each wheel carrier 3 supporting a wheel R having a wheel center plane RM. The wheel carrier 3 is preferably made of cast metal.

[0030] Material thickenings 30 are now applied to each wheel carrier 3 on the side facing the vehicle's longitudinal center plane FM.

[0031] As will be explained later, these material thickenings 30 are provided locally with targeted material weakenings, so that a wheel R on the outside of the curve rotates around a virtual axis under the influence of a lateral force and thus goes into toe-in.

[0032] The figure shows that the virtual axis A runs approximately parallel to the wheel center plane RM and is offset from the wheel center plane RM in the direction of the vehicle's longitudinal center plane FM. However, other orientations of the virtual axis A are conceivable.

[0033] The axle body 2 is further connected in the area of ​​each wheel side to a leaf spring 4, which in turn is fastened to a vehicle body (not shown here).

[0034] In Fig. For the sake of clarity, wheel R is only indicated by dashed lines in Figure 2.

[0035] E denotes a wheel contact plane. Furthermore, a wheel contact point 5 is shown, where the wheel R rests on the wheel contact plane E. Under real load conditions, however, a wheel contact area (so-called contact patch) L results.

[0036] From this view, it is clearly visible that the virtual axis A, when projected onto a vertical plane running in the vehicle's longitudinal direction (here, the plane of the image), is inclined at an angle α to the direction of travel FR. The angle α is an acute angle between the virtual axis A and a horizontal plane, e.g., the wheel contact plane E.

[0037] The angle α is preferably in a range of about 40 degrees to 50 degrees, particularly preferably it has a value of about 45 degrees.

[0038] M denotes a wheel center point of the wheel R, around which the wheel R is rotatably mounted on the wheel carrier 3, which is shown only very schematically.

[0039] It can be seen that the virtual axis A runs at a vertical distance a1 below the wheel center point M and, viewed in the direction of travel FR, intersects the wheel contact plane E at a distance a2 behind the wheel contact point 5 at an intersection point 6. The intersection point 6 is preferably located behind the wheel contact area L.

[0040] Due to this position of the virtual axle A, extremely good driving characteristics can be achieved with a simple design of the rear axle 1, which are otherwise only possible with much more complex rear axles (independent wheel suspensions).

[0041] The wheel carrier 3 is further connected to the axle body 2 in such a way that it extends upwards from the axle body 2. This is done in such a way that the wheel center M lies above the longitudinal axis 20 of the axle body 2 and the wheel center M and the longitudinal axis 20 lie on a common vertical axis V. From the Fig. 3 it can be seen that the already mentioned material thickening 30 extends like a belt around the wheel center M on the one hand and the axle body 2 on the other hand.

[0042] The material thickening 30 provides the wheel carrier 3 with sufficient strength.

[0043] However, in order to be able to realize the desired virtual axis A in a simple manner, the material thickening 30 is specifically provided with material weakenings 31a and 31b.

[0044] Specifically, the material thickening 30, viewed in the direction of travel FR, has a front section 30a and a rear section 30b.

[0045] The material weakening 31a is introduced in the front section 30a and the material weakening 31b is introduced in the rear section 30b.

[0046] As can be seen from the Fig. 4 and Fig. As can be seen in Figure 5, the material weakenings 31a, 31b have the shape of a trench-like depression. Furthermore, the material weakenings 31a, 31b extend transversely to the longitudinal extent of the material thickenings 30a and 30b, respectively.

[0047] Furthermore, it can be seen that (measured from the wheel contact plane E) the material weakening 31b has a height h1 and the material weakening 31a has a height h2.

[0048] The height h2 is higher than the height h1. This allows the desired angle α of the virtual axis A to be easily specified.

[0049] In Fig. 6 the rear axle 1 is shown in a slightly more detailed design.

[0050] It can be seen that the rear axle 1 is connected on the left side to a body 8 of a motor vehicle K via a damper 9 and the aforementioned leaf spring 4. Specifically, the leaf spring 4 is attached to a rigid connecting part 7, which in turn is firmly connected to the body 8. The leaf spring 4 extends in the direction of travel FR of the motor vehicle K and wraps around the axle body 2 of the rear axle 1 like a belt.

[0051] 32 are the fastening holes for a braking device of wheel R, which is not shown in detail.

[0052] In order to better understand the effect of the virtual axis, it is shown using the Fig. 7 and Fig. 8 outlined.

[0053] In these figures, only the wheel center plane RM of a wheel on the outside of the curve (not shown in detail) is shown under the action of a lateral force F.

[0054] Thus, the virtual axis A causes, on the one hand, the wheel center plane RM, viewed in the direction of travel FR, to move outwards on the upper side away from the vehicle's longitudinal center plane FM under the influence of the lateral force F (cf. RM'). This creates a positive camber angle γ or increases it (cf. Fig. 7).

[0055] On the other hand, the wheel center plane RM moves under this lateral force F in a view from above onto the rear axle 1 at the front inwards in the direction of the vehicle's longitudinal center plane FM, so that a positive toe angle δ (so-called toe-in) is established or increased.

[0056] Thus, by designing and aligning the virtual axle A, high camber and toe-in stiffness and thus good handling can be achieved. List of reference symbols 1 motor vehicle rear axle 2 axle beams 3 wheel carriers 4 leaf spring 5 Wheel contact point 6 Intersection of the virtual axis with the wheel contact plane 7 Connection part 8 Body 9 dampers 20 Longitudinal axis 30 Material thickening 30a front section of the material thickening 30b rear section of the material thickening 31a trench-like material weakening 31b trench-like material weakening 32 mounting holes a1 distance a2 distance A virtual axis E Wheel contact plane F Lateral force when cornering FM vehicle longitudinal center plane FR direction of travel h1 height h2 height K Motor vehicle L Wheel contact patch (tread pattern) M Wheel center point R wheel RM, RM' wheel center plane V vertical axis α angle δ toe angle y Sturzwinkel

Claims

[1] Counter-steering motor vehicle rear axle (1), in which, under the action of a lateral force (F) on a wheel (R) on the outside of the curve, which is fastened to a wheel carrier (3), a rotational movement of the wheel carrier (3) about a virtual axis (A) in the direction of a toe-in (γ) occurs, wherein the virtual axis (A) is inclined at an angle (α) at ​​least in the direction of travel (FR) when projected onto a plane running in the longitudinal direction of the vehicle, characterized byin that the virtual axis (A) runs below a wheel center point (M) and has an intersection point (6) with a wheel contact plane (E), which intersection point lies behind a wheel contact point (5) when viewed in the direction of travel (FR), the wheel carrier (3) being connected to an axle body (2) extending transversely to the vehicle's longitudinal direction, the wheel carrier (3), in a view in the longitudinal extension of the axle body (2), being provided with at least one material thickening (30) running like a belt around the axle body (2), which has at least two material weakenings (31a, 31b) transversely to its longitudinal extension, of which a front material weakening (31a) is higher than a rear material weakening (31b) when viewed in the direction of travel (FR) and measured from the wheel contact plane (E). [2] Counter-steering motor vehicle rear axle (1) according to claim 1, characterized by that the angle (α) is in a range of approximately 40° to 50°. [3] Counter-steering motor vehicle rear axle (1) according to claim 1 or 2, characterized by that the angle (α) is approximately 45°. [4] Counter-steering motor vehicle rear axle (1) according to one of the preceding claims, characterized by that the virtual axis (A) runs approximately parallel to a wheel center plane (RM). [5] Counter-steering motor vehicle rear axle (1) according to one of the preceding claims, characterized by that the belt-like material thickening (30) is arranged on a side of the wheel carrier (3) facing the vehicle center plane (FM). [6] Counter-steering motor vehicle rear axle (1) according to one of the preceding claims, characterized by that the wheel center (M) is arranged above the axle body (2), wherein an imaginary connecting line between the wheel center (M) and a longitudinal axis (20) of the axle body (2) runs approximately vertically. [7] Motor vehicle (K) with a rear axle (1) according to one of the preceding claims. [8] Motor vehicle (K) according to claim 7, characterized by that the axle body (2) of the rear axle (1) is connected in the region of a wheel carrier (3) to a leaf spring (4) which runs like a belt around the axle body (2) and in the longitudinal direction of the vehicle and which is fastened to the motor vehicle body (8).

Images