EP1159146A1

EP1159146A1 - Rear axle for a motor vehicle

Info

Publication number: EP1159146A1
Application number: EP00909310A
Authority: EP
Inventors: Stefan Behrens; Edison Fatehpour
Original assignee: Trelleborg Automotive Technical Centre GmbH
Current assignee: Trelleborg Automotive Germany GmbH
Priority date: 1999-03-04
Filing date: 2000-03-03
Publication date: 2001-12-05
Also published as: KR20010108275A; US20020047244A1; JP2002538046A; DE19909561A1; BR0008736A; WO2000051832A1

Abstract

The invention relates to a rear axle for a motor vehicle that has a guide rod assembly (11). The guide rod assembly is constructed from two wheel-bearing trailing links (13a, 13b) which run parallel to one another and are joined together in the area of the ends furthest away from said wheels by a cross member (14) that is rigid, yet has a high degree of torsional flexibility. Two swivel bearings (16a, 16b) which are located at a certain distance from one another are provided for mounting the guide rod assembly on the motor vehicle body (17). The guide rod assembly (11) is mounted on the motor vehicle body (17) by means of an essentially vertical lever arm (L2) to avoid a longitudinal displacement of the rear axle despite the non-rigid design of the bearing.

Description

Rear axle for a motor vehicle

The invention relates to a rear axle for a motor vehicle with a link assembly which has two wheel-carrying trailing arms which are connected to one another in the region of their ends remote from the wheel via a cross strut and is pivotably mounted on the vehicle body by means of two spaced apart bearings.

Such a rear axle is known from DE 43 22 91 0 A1. Twist-beam rear axles have been used in large numbers in motor vehicles for many years. The axle bearings are the crucial connections between the vehicle body and the axle for driving behavior and comfort. The design of the bearing points of the wheel-guiding parts must therefore be a compromise between driving stability and driving comfort.

A stiff connection, for example via a ball bearing, would be ideal for safe driving behavior. For reasons of comfort, however, the longitudinal spring stiffness of the axle bearings should be kept as low as possible.

Proceeding from this, the object of the invention is to propose a rear axle of the type mentioned at the outset, which if possible low longitudinal rigidity avoids longitudinal displacements of the bearing points when cornering.

To achieve the object, it is proposed according to the invention for a rear axle of the type mentioned at the outset that the link assembly is mounted on the vehicle body via a substantially vertically oriented lever arm.

This makes it possible to make the rear axle bearing very soft in the longitudinal direction, since the longitudinal displacements of the bearing points that occur when cornering are compensated for by the lever arm of the joint due to a superimposed movement. This superimposed movement results from the inevitable deflection of the outer wheel and deflection of the inner wheel when cornering. The lever arm then results in a longitudinal displacement in the opposite direction. The pivotable articulation of the lever arm must take place below the end of the trailing arm which is remote from the wheel. The lever arm of the joint is smaller than the lever arm of the link assembly. In the case of the rear axle according to the invention, a soft design of the bearings is thus possible by compensating for the longitudinal displacement.

If the ends of the trailing arms remote from the wheel are supported by means of bolts, these bolts can be pivoted with respect to the vehicle body. The fulcrum of the swivel movement lies below the end of the respective trailing arm that is far from the wheel

Advantageous refinements of the invention result from the subclaims. The bearing advantageously has an elastic bushing, the housing of which is fixed to the link assembly and the rubber-elastic bearing body is pivotally fixed to the vehicle body via a bolt. Here, the distance of the bolt connected to the vehicle body acts as a lever arm.

To limit the longitudinal displacement of the bearings of the bushing, stops acting in the longitudinal direction are advantageously assigned.

The stops can be designed as spaced stop buffers that interact with the bolt.

In a further embodiment according to the invention, the bearing can have a fork fixed to the handlebar assembly, the fork arms of which are connected via a bolt, the bolt being supported on the elastic bearing body of an elastic bushing which is connected in an articulated manner to the vehicle body. In this embodiment, too, a second lever arm for articulating the rear axle is realized. The fork, which is oriented perpendicular to the handlebar assembly and has a bolt penetrating the bush, in turn enables compensation of the longitudinal movement by means of a superimposed movement.

The socket is advantageously articulated on the vehicle body via a pivot bearing.

In another advantageous embodiment, the socket is connected to the vehicle body via a link guide. Here, the link guides can have at least one guide groove in which a guide pin arranged on the bush engages.

The invention is explained in more detail below on the basis of exemplary embodiments, which are shown schematically in the drawing. Here show:

Figure 1 is a plan view of a rear axle according to the invention;

Figure 2 is a side view in the direction of arrow II of Figure 1;

3a-c different rear axle constructions and their behavior in a left turn;

Figure 4 shows the force relationships on a rear axle according to the invention;

5a-d the axle bearing according to FIG. 2 in the area of the right-hand side of the vehicle in different driving conditions;

Figure 6a-d the axle bearing according to Figure 2 on the left side of the vehicle in different driving conditions;

7a-d representations of the axle bearing according to FIG. 2 in different driving conditions;

8 shows a side view of a further embodiment according to the invention;

9 shows a side view of a further embodiment according to the invention;

Figure 10a-d the second embodiment of the rear axle according to the invention in different driving conditions;

Figure 1 1 ad the third embodiment of the rear axle according to the invention in different driving conditions. Figure 1 shows a plan view of a rear axle 10 according to the invention, which is used in a motor vehicle, not shown. The rear axle 1 0 has a link assembly 1 1, which is made up of two mutually parallel longitudinal links 1 3a, 1 3b and a transverse strut 1 4 connecting the longitudinal links 1 3a, 1 3b. The trailing arms 1 3a, 1 3b are each designed to be resistant to bending and torsion. In contrast, the cross strut 14 is designed to be torsionally and compressively rigid.

The rear wheels 1 2a, 1 2b are mounted at one end region of the longitudinal links 1 3a, 1 3b by means of wheel axles 1 5a, 1 5b. At the opposite end, the link assembly 1 1 is pivotally mounted on bearings 1 6a, 1 6b on the vehicle body 1 7, not shown.

FIG. 2 shows a side view of the rear axle in the direction of arrow II in FIG. 1. As can be seen from this illustration, the bearing 1 6a has an elastic bushing 19, in which an elastic bearing body 20 is received. The socket 1 9 is fixed at the free end of the trailing arm 1 3a. A bolt 1 8 penetrates the socket 1 9 and is received on the elastic bearing body 20. A first end region of the bolt 1 8 is articulated on the vehicle body 17 by means of a pivot bearing 22. The bolt 1 8 forms a lever arm L2 between the body-side pivot bearing 22 and the center of the elastomeric bearing body 20.

The bolt 1 8 is pivotable with respect to the vehicle body 1 7 about a pivot point 33. This fulcrum 33 lies below the end of the trailing arm 1 3a remote from the wheel. The bolt 1 8 has an elongated area 1 8a, which projects beyond the socket 1 9. This area 1 8a cooperates with spaced stops 21 a, 21 b, which limit the longitudinal movement of the rear axle 1 0.

Before the functioning of the rear axle 10 shown in FIGS. 1 and 2 is explained, the basic problem of the invention will first be explained in more detail with reference to FIGS. 3 and 4. FIGS. 3a to 3c show different designs of known rear axles and their reactions in a left turn.

Figure 3a shows a rear axle, which behaves neutrally in a left turn. As can be seen from the schematic illustration, the vehicle 23 has a rear axle 1 0, which is mounted on bearings 1 6. A centrifugal force F to the outside occurs on a left-hand curve, which leads to reaction forces F _R at the rear wheels 1 2a, 1 2b. In the rear axle mounting shown, the neutral behavior is achieved in that the bearings 1 6 are very stiff, ideally designed as ball bearings. However, this has the disadvantage that the driving comfort is reduced in the longitudinal direction by the rigid mounting.

Figure 3b shows a rear axle 1 0, which is mounted on bearings 1 6 with rubber bushings on the vehicle body. Oversteer occurs in such a storage, whereby the vehicle 23 can break out more easily.

Understeering occurs in the rear axle bearing shown in FIG. 3c. The bearings 1 6 each have wedges 24, which are the deflection the rear axle 1 0 in the desired longitudinal direction. The disadvantage here is that the rear axle 1 0 must be softly supported in the lateral direction so that a lateral displacement relative to the vehicle 23 can occur at all.

FIG. 4 shows the force relationships present on the rear axle 10 due to the acting forces F _s in the area of the bearings 1 6a, 1 6b.

The mode of operation of the bearing arrangement of the rear axle 10 shown in FIG. 2 will be explained below with reference to FIGS. 5a to 5d.

Figure 5a shows the right side of a vehicle 23, in which the rear axle 10 is in the normal position. The bearing 1 6b is located on the normal axis 25.

FIG. 5d shows a driving state as occurs in a left-hand bend in a rear axle 10 according to the invention. Here, the states shown in FIGS. 5b and c overlap on the right-hand side of the vehicle, the longitudinal movements occurring being compensated for.

Fig. 5b shows the components of the longitudinal displacement to the front, which is caused by the deflection of the outer wheel and the existing lever arm.

Fig. 5c shows the displacement of the rear axle to the rear, which is caused by the support of the lateral forces on the wheel on the outside of the curve. Neither state 5b nor state 5c occurs on its own in the rear axle 10 according to the invention.

As can be seen from FIG. 5d, there is no displacement of the bearing 1 6b with respect to the normal axis 25. Despite the soft design of the bearing 1 6b in the longitudinal direction, the longitudinal movement is compensated for by a superimposed movement which results from the articulation of the bearing 1 6b via an interposed bolt 1 8.

FIGS. 6a to 6b show the conditions in the area of the left side of the vehicle in the driving conditions according to FIGS. 5a to 5d.

FIG. 6d shows that even in the area of the left side, by compensating the movements according to FIGS. 6b and 6c, there is no displacement with respect to the normal axis 25.

FIGS. 7a to 7d show the individual states according to FIGS. 5a to 5d again in an enlarged representation. From Figure 7d it can be seen particularly well that, despite the soft design of the bearings 1 6a, 1 6b, no longitudinal displacement occurs, since this is compensated for by a superimposed movement when cornering.

Figure 8 shows a further embodiment, in which the trailing arms 1 3a, 1 3b of the rear axle 10 each have a fork 27 at the end. The fork 27 is aligned perpendicular to the longitudinal axis of the trailing arms 1 3a, 1 3b. Two spaced fork arms 28a, 28b are connected by a bolt 29 which penetrates the bushing 19 and on the outer circumference of which the elastic bearing body 20 is arranged. The Bushing 1 9 is pivotally mounted on the vehicle body 1 7 by means of a pivot bearing 26.

Even with this mounting, there is a joint with a lever arm (L2), which leads to compensation of the longitudinal movements by a superimposed movement. The fulcrum 33 of the bolt 29 lies below the end of the trailing arm 1 3a remote from the wheel.

FIGS. 10a to 10d show various rear axle reactions in the area of the right side of a motor vehicle in accordance with FIGS. 5a to 5d. Figure 1 0d shows that there is no longitudinal displacement due to the superimposition of the movements.

FIG. 9 shows a further embodiment variant similar to FIG. 8, in which the pivotable articulation to the vehicle body 17 is achieved via a link guide. The link guide 30 has mutually parallel guide grooves 31 a, 31 b. Guide bolts 32a, 32b, which are fixed to the bushing 19, engage in the guide groove. This achieves a pivotable articulation of the bushing 1 9 on the vehicle body 1 7. In this way, the virtual pivot point 33 can be shifted further downwards without losing ground clearance. The fulcrum 33 lies below the end of the trailing arm 1 3a remote from the wheel.

In Figures 1 1 a to 1 1 d it is shown that even in this embodiment variant there is no longitudinal displacement due to the compensation of the longitudinal movement by a superimposed movement.

Claims

claims

Rear axle for a motor vehicle with a link assembly (11) which has two wheel-carrying trailing arms (13a, 13b) which are connected to one another in the region of their ends remote from the wheel via a cross strut (14), and by means of two spaced apart bearings (16a, 16b) on the Vehicle body (17) is pivotally mounted, characterized in that the link assembly (11) is mounted on the vehicle body (17) via an essentially vertically oriented lever arm (L2).

Rear axle according to claim 1, characterized in that the bearing (16a, 16b) has an elastic bushing (19) which is fixed to the link assembly (11) and whose elastic bearing body (20) is pivotable on the vehicle body via a bolt (18) (17) is set.

Rear axle according to claim 2, characterized in that the bushing (19) is assigned stops (21a, 21b) which act in the longitudinal direction.

Rear axle according to claim 3, characterized in that the stops (21a, 21b) are designed as spaced stop buffers which cooperate with the bolt (18).

Rear axle according to claim 1, characterized in that the bearing (16a, 16b) has a fork (27) fixed to the link assembly (11), the fork arms (28a, 28b) of which are connected by a bolt (29) are connected, the bolt being supported on the elastic bearing body (20) of an elastic bushing (1 9) which is connected in an articulated manner to the vehicle body (1 7).

6. Rear axle according to claim 5, characterized in that the bush (1 9) via a pivot bearing (22) on the vehicle body (1 7) is articulated.

7. Rear axle according to claim 6, characterized in that the bushing (1 9) is connected via a link guide (30) to the vehicle body (1 7).

8. Rear axle according to claim 7, characterized in that the link guide (30) has at least one guide groove (31 a, 31 b), in which on the socket (1 9) arranged guide pin (32 a, 32 b) engages.