WO2005044603A1

WO2005044603A1 - Twist-beam rear axle and method for producing a cross member

Info

Publication number: WO2005044603A1
Application number: PCT/DE2004/002446
Authority: WO
Inventors: Dieter TÖPKER
Original assignee: Benteler Automobiltechnik Gmbh
Priority date: 2003-11-07
Filing date: 2004-11-03
Publication date: 2005-05-19
Also published as: DE10351954A1; JP2007509795A; EP1680291A1; KR20060060744A

Abstract

The invention relates to a twist-beam rear axle for motor vehicles, which comprises two longitudinal links (2, 3) connected by a cross member (4), and to a method for producing a cross member (4). The cross member is comprised of a hollow profile with a middle section (5) that is open in areas. This middle section has a longitudinally extending cutout (8) at whose edge areas webs (11) are provided at least in sections. Ends (6, 7) that are closed whereby forming a tubular shape are adjoined to the middle section (5). The webs (11) are curved in an arched manner, whereby the aperture angle between a tangent lying on the outer periphery of the middle section (5) and a tangent lying on the end of the webs ranges between 5° and 90°, preferably between 15° and 70°.

Description

Twist beam axle and method for producing a cross member

The invention relates to a torsion beam axle for motor vehicles and a method for producing a cross member therefor.

Twist-beam axles are characterized by a vehicle-specific simple structure with a small footprint and good kinematic properties. The cross member connecting the two lateral trailing arms acts as a torsion profile, so that with a simultaneous deflection, a trailing arm characteristic is obtained and with reciprocal deflection, a semi-trailing arm characteristic.

From DE 199 49 341 A1 a torsion beam axle for motor vehicles is known, with two longitudinal links connected by a cross member, the cross member consisting of a hollow profile with a single-layer regionally open central section, to which tubular ends are connected on both sides.

A similar concept is disclosed in DE 101 22 998 A1. The cross member is tubular and has an oval elongated cutout in the central section.

A vehicle axle according to DE 195 33 479 C2 also belongs to the prior art. The cross member of this axis has a recess which extends axially to the longitudinal axis of the tubular body, the recess in its edge regions being bordered at least in sections by webs which are embodied within the tubular body. The webs are strongly angled inwards, the height of the webs should correspond approximately to the width of the recess in the tubular body.

With the above-mentioned configurations of torsion beam axles, a design of the section modulus can be achieved that is adapted to the dynamic loads. The main stresses occurring during driving are concentrated in the transition areas between the ends and the open middle section, i.e. to the free torsion length behind the connection area to the Längslenkem. This can affect the lifespan of the cross member under torsional loads and thus the entire torsion beam axle.

In order to manufacture the crossbeams of the torsion beam axles, corresponding blanks are punched out. These are then formed into a corresponding tubular shape and joined along longitudinal edges lying against one another. In practice it has been found that the cut edge surface tends to form microcracks in the direction of the sheet due to the blanking of the board. This leads to an increased risk of cracking, which can lead to a considerable reduction in the service life when driving the axle in the event of a load due to the acting gravity. This can be determined in particular when the production tools have been in use for a long time and the cutting gap of the punches or the cutting tools has increased and the tolerance limits have been reached. As a result, there is a hidden risk of sacrificing lifespan due to deteriorated cutting edge conditions.

Also, the high and not always the same recoil forces on the trimmed profile can lead to inaccuracies when shaping the profile, which ultimately leads to irregularities in the roll stiffness behavior of the

Twist beam axle can result.

Based on the prior art, the invention is therefore based on the object of improving a torsion beam axle of the known type with regard to the service life with high dynamic performance and to show a method for producing a cross member which is optimized in terms of application technology.

According to the invention, the objective part of this task is solved in a twist-beam axle with the features of claim 1.

The cross member connecting the two trailing arms is designed as a hollow profile with a regionally open central section that has an elongated cutout — on the other edge regions — at least in sections webs are provided. The ends of the cross member are closed in a tubular shape.

The key point of the invention is the measure that the webs are curved in an arc shape, the opening angle between one on the outer circumference of the Middle section applied tangent and a tangent applied to the end of the webs between 5 ° and 90 °. This measure, that is to say the shaping of the curved webs, places the open cut surface at the end of the trimmed area directly out of the effective area of the shear forces. This leads to a significant increase in the dynamic load capacity of the cross member. Negative influences from quality fluctuations in the blank cut are significantly reduced. Overall, the service life of the cross member and thus the torsion beam axle can be increased. In addition, the shaping process of the trimmed blank to the finished tube profile is improved, since the resilience is significantly reduced by the shaped web or webs. This results in a better shape tolerance for the profile.

The opening angle is particularly advantageously between 15 ° and 70 °, as provided for in claim 2. The radius of the curved webs depends on the respective sheet thickness.

Depending on the design of the twist beam axle in adaptation to the vehicle type and the required operational parameters, the webs can be directed inwards (claim 3) or outwards (claim 4) with respect to the longitudinal axis of the cross member.

According to the features of claim 5, the webs extend all the way along the entire length of the cutout. This design suggests advantages in practice, particularly in the case of heavy designs of torsion beam links.

In principle, the webs can also extend only in the transition area from the central section to the ends, that is to say in the area in which the cut edges of the cutout converge and the cross member merges into the closed tubular profile. The main stresses occurring during driving are concentrated here. These can be compensated for in these areas by the webs formed according to the invention.

In practice, an oval contour of the section in the middle section is particularly suitable, as provided for in claim 7. The procedural part of the task is solved by a method according to claim 8.

To produce a cross member, a flat board is first manufactured, the geometry of which corresponds to the development of a cross member. The circuit board is fundamentally of rectangular configuration, concave cutouts h being produced on its longitudinal sides in the circuit board trim. The edges of the cutouts are angled in an additional shape or directly in the blank. The circuit board is then rolled up in a known manner in a tubular manner and joined along the longitudinal edges of the ends of the crossmember which are then adjacent to one another. This is preferably done as welding.

The manufacture of the cross member is efficient and very easy to automate. As already explained above, the shaping of the trimmed board into the finished tubular profile shape is improved, since the return forces are significantly reduced by the shaped webs, which contributes to better profile accuracy.

The invention is described below with reference to embodiments shown in the drawings. Show it:

Figure 1 is a perspective view of a torsion beam axle according to the invention;

FIG. 2 shows a vertical section through the central section of a first embodiment of a cross member;

FIG. 3 shows a vertical section through the central section of a second embodiment of a cross member;

FIG. 4 shows the edge area of a section with the representation of an arched web;

Figure 5a the board of a cross member in the development;

5b shows a cross section through the central transverse plane of a circuit board according to the representation of FIG. 5a with the representation of a first embodiment variant of the edge regions and 5c shows a cross section through the central transverse plane of a circuit board in accordance with the illustration in FIG. 5a with the illustration of a second embodiment variant of the edge regions.

Figure 1 shows a torsion beam axle 1 in a perspective representation. The twist beam axle 1 essentially comprises two wheel-guiding trailing arms 2, 3 and a cross member 4 connecting the two trailing links 2, 3. The cross member 4 consists of a single hollow profile with a regionally open central section 5, to which ends 6, 7 which are tubularly closed on both sides connect.

The geometry of the cross member 4 is matched to the loads to be expected of the torsion beam axle 4 in the motor vehicle.

The central section 5 has an oval elongated cutout 8. This results in 5 open cross sections in the central section with a circular sector-shaped, oval or V or U-shaped configuration. The leg length measured in cross section over the circumference in the central section 5 decreases from the ends 6, 7 towards the center of the cross member. Suitable receptacles 9, 10 for the ends 6, 7 of the cross member 4 are formed on the trailing arms 2, 3. The ends 6, 7 are fitted and joined in the receptacles 9, 10, as a rule welded. This ensures good power transmission from the trailing arms 2, 3 into the cross member 4.

The cutout 8 has webs 11, 12 and 13, at least in sections, in an edge region (see FIGS. 2, 3 and 4). The webs 11, 12, 13 are curved in an arc. In the embodiments of the cross member 4 according to FIGS. 2 and 4, the webs 11 and 13 are directed inwards with respect to the longitudinal axis L of the cross member 4, whereas the webs 12 in the cross member 4 in the embodiment according to FIG. 3 refer to the longitudinal axis L of the cross member 4 are directed outwards.

The curvature of the webs 11, 12 and 13 is fundamentally chosen such that the opening angles α, β and γ between a tangent T1, T2 or T3 applied to the outer circumference U of the central section 5 and a tangent to the end 14, 15, 16 of the webs 11, 12 and 13 applied tangent T4, T5, T6 is between 5 ° and 90 °, preferably between 15 ° and 70 °.

The opening angle α of the cross member 4 in the embodiment shown in FIG. 2 is approximately 66 °. Relative to the horizontal planes HE running through the cutout 8 or generally through the cross member 4, the angle δ is 48 °.

The opening angle β in the embodiment of the cross member 4 according to the illustration in FIG. 3 is 50 °. Relative to a horizontal plane HE intersecting the cross member 4, an angle ε of 32 ° results.

The opening angle γ of a cross member 4 according to the illustration in FIG. 4 is 36 °. This results in an angle η of the tangent T6 from the end 16 or web 13 with respect to the horizontal plane HE of 16 °.

The curved webs 11, 12 and 13 lead to the open cutting surface at the ends 14, 15 and 16 being moved from the normal contour of the hollow profile of the cross member 4. Possible negative influences from the circuit board section, for example microcracks, are thus shifted out of the area of the main stresses and the main force curve. This comparatively simple measure contributes significantly to an increase in the service life with high dynamic performance of a torsion beam axle 1.

It can be seen from FIG. 1 that the webs 11 extend over the entire length of the cutout 5. It is also possible that the webs 11, 12 or 13 are only provided in the transition area from the central section 5 to the ends 6, 7.

To manufacture the cross member 4, a latin 17 is made of metal, for example steel, aluminum or another metallic material. This receives a sheet metal trim, so that its circumferential geometry corresponds to the development of the cross member 4. The basic configuration of the development is rectangular, with concave cutouts 19 being punched on the longitudinal sides 18 of the circuit board 17. The contour can be seen in FIG. 5a. In a separate one Forming step, the edges 20 of the cutouts are angled in an arc relative to the planes of the plate 17, as can be seen in FIGS. 5b and 5c. Subsequently, the trimmed board 17 is shaped into a tube and the longitudinal edges 21, 22 lying against one another at the ends 6, 7 are welded together. The ends 6, 7 then have the round closed cross section.

REFERENCE NUMBERS:

1 - Twist beam axle

2 - trailing arm

3 - trailing arm

4 - cross member 5- middle section

6 - end of 4th

7 - end of 4th

8 - neckline

9 - Recording

10 - Recording

11 - bridge

12-bridge

13-web

14 - end of November 11

15- end of 12

16- Endev. 13

17-board

18- long side

19- neckline

20 edge

21 - longitudinal edge 22 - Long edge

L - longitudinal axis

U - outer circumference

T1 - tangent

T2 - tangent

T3 - tangent

T4 - tangent

T5 - tangent

T6 - tangent

HE - horizontal plane

α - opening angle ß - opening angle γ - opening angle δ- angle ε - angle η - angle

Claims

claims

1. twist link axle for motor vehicles, which has two longitudinal links (2, 3) connected by a cross member (4), the cross member (4) consisting of a hollow profile with a regionally open central section (5) with an elongated cutout (8) the edge regions of which are provided at least in sections with webs (11, 12, 13) and adjoin the middle section (5) with tubular ends (6, 7), characterized in that the webs (11, 12, 13) are curved in an arc shape, the opening angle (α, β, γ) between a tangent (T1, T2, T3) applied to the outer circumference (U) of the central section (5) and one at the end (14, 15, 16) of the webs (11, 12 , 13) applied tangent (T4, T5, T6) is between 5 ° and 90 °.

2. Twist beam axle according to claim 1, characterized in that the opening angle (α, β, γ) is between 15 ° and 70 °.

3. Twist beam axle according to claim 1 or 2, characterized in that the webs (11, 13), with respect to the longitudinal axis (2) of the cross member (4), are directed inwards.

4. Twist beam axle according to claim 1 or 2, characterized in that the webs (12), based on the longitudinal axis (2) of the cross member (4), are directed outwards.

5. Twist beam axle according to one of claims 1 to 4, characterized in that the webs (11, 12, 13) extend over the entire length of the cutout (8).

6. Twist beam axle according to one of claims 1 to 4, characterized in that the webs (11, 12, 13) extend in the transition region from the central section (5) to the ends (6, 7).

7. Twist beam axle according to one of claims 1 to 6, characterized in that the cutout (8) is elongated oval. Method for producing a cross member (4) for a torsion beam link according to one of claims 1 to 7, characterized in that first a flat board (17) is manufactured, the geometry of which corresponds to the development of a cross member (4), the board ( 17) has concave cutouts (19) on its longitudinal sides (18), after which the edges (20) of the cutouts (19) are angled in an arc shape relative to the plane of the circuit board and then the circuit board is formed into a tube shape and along the adjacent longitudinal edges (21, 22) is added.