DE10102759A1 - Composite suspension arm rear axle for motor vehicles has longitudinal profiles with hollow chamber and walls separated by full-length gap - Google Patents

Abstract

The axle (1) is of tubular material (14) with a central double-walled longitudinal profile (4) and rounded ends (5,6). It has at least one hollow chamber in the area of the profile, and the walls (9,10) of the chamber are at a distance to each other. The hollow chambers are positioned between the central profiled part (3) and transitional areas (7,8), and each has a local gap (2) to separate the walls.

Description

The invention relates to a torsion beam rear axle made of tubular material for a Motor vehicle, with ends having essentially round cross sections, between which have a medium length range with double walls Longitudinal profile is arranged, the walls between the ends and the middle length range each with a transition range from the circular Cross section into a profile cross section. EP 0 229 576 discloses one of a torsion beam rear axle made of a tube, the wheel-leading trailing arms run parallel to each other and are undeformed tubular, whereas the Trailing arm connecting rigid but torsionally soft cross members except for also circular ends an L-, V-. T, U, X or H shaped cross section having. Such a torsion beam rear axle has the disadvantage that it is in the transition areas between the deformed and the undeformed Long sections is exposed to high loads.

X- or Y-shaped profiled cross members have a longer service life because of their The center of thrust coincides with the center of gravity of the cross member. The disadvantage is with these cross sections, however, the limited possibility of variation Flexural rigidity in terms of weight and positioning for driving properties responsible shear center of the cross member. Around Twist-beam rear axles will improve the high voltage loads Transitional areas between the deformed and non-deformed lengths of the cross member designed so that the stresses occurring over the entire Profile area can be evenly distributed. To do this, when transitioning from a middle U-shaped length range of the cross member on the adjacent Transitional area in which the U-shaped cross-section continuously in the round tubular cross section merges at the end of the cross member, impressions are produced, their shape, location and depth from the diameter and wall thickness of the round tubular exit cross-section, from the free torsion length of the middle U- shaped length range and are dependent on the predetermined torsion rate.  

To the high-voltage transition areas between deformed and not thus deformed longitudinal sections of a cross member of a twist beam axle design that the occurring tensions over the entire profile area are evenly distributed, is known from EP 0 752 332, with a wishbone, the circular tubular end section and in the middle length range by non-cutting Forming has a double-walled U-shaped torsion section, the intermediate section between the end sections and the torsion section continuously transition from circular to U-shaped cross-section, such Training to provide that the cross member end of the U-shaped Torsional section on an arcuate web with inward or outward on the outside, with rounded edges.

DE 196 53 959 also describes a twist beam rear axle, on which the Transitions from the end sections to the intermediate sections the torsion section frontally facing, extending largely radially to the longitudinal axis, from the Trough bottoms of the intermediate sections shaped crosspieces are provided. at two torsion beam rear axles are the walls of the Longitudinal profile equally shaped with impressions.

The prior art also emphasizes that the return behavior of the Material and thus the air gap formed between the walls can be reduced to improve the mutual interlocking of the impressions. With these Twist-beam rear axles lie on the walls of the double-walled longitudinal profile to each other. The disadvantage here is that the loads introduced Relative movements of the adjacent walls, especially in the U or V-shaped cross section are possible. Relative movements of the adjacent Walls in the transition areas as well as in the middle length range lead to Abrasion and unwanted vibrations that limit driving comfort can. Furthermore, such relative movements are usually used as signs deemed to be of lower quality. The object of the invention is therefore to these disadvantages avoid doing the coordinated functions of different areas of the Twist-beam rear axles, especially with regard to the torsion rate, are retained should.

A solution to this problem is provided in that the Twist-beam rear axle in the area of the longitudinal profile at least one cavity  and that the walls of the cavity are spaced apart. It has proved to be advantageous, one or more cavities between the walls to form the longitudinal profile in a targeted manner.

It is advantageously provided that the cavity is in one Transition area is arranged, since in particular in these transition areas the stresses occurring during the journey are the greatest.

It has proven to be particularly advantageous that the cavity between the Transitional areas and the middle length range at least one local gap having. The gap is arranged in the profile cross-sectional plane so that it Connects profile edges with each other. Through the targeted arrangement of the gap achieved that the relative movements are largely avoided without the Strength, torsional rigidity and durability of the torsion beam rear axle is restricted.

It is envisaged that the gap is essentially the shape of the longitudinal profile having. This is advantageously achieved in that the longitudinal profile has an L, V, T, U, X or H-shaped profile cross-section and the gap in one Profile cross-sectional plane is arranged perpendicular to the longitudinal axis. It is in this advantageously provided that the torsion beam rear axle in one piece a pipe is made. The behavior of the material in the formation of the Longitudinal profile are used, namely that after the compression Jump back walls due to elasticity.

Alternatively, the torsion beam rear axle can be manufactured by a method be that the cavity before profiling the longitudinal profile of the middle Length range, preferably formed by expanding the tubular material becomes. By expanding the undeformed tube in the space provided for the gap The material is prepared in the area so that the opposing Do not touch walls when molding. It is possible to put the pipe in expand one level or radially so that the expansion at the intended Profile cross section or to the longitudinal profile of the torsion beam rear axle can be customized.  

A preferred embodiment of the method is provided in that the tubular material for profile formation after expanding the tubular material in a pressing tool is used, which with a to the expanded area adapted recess is provided that the pressing tool for producing the Longitudinal profile applied to the walls of the tubular material and that the flared walls when pressed together at a distance from each other fit the recess. These steps ensure that the walls have a distance after the profile is formed. It is therefore advantageous possible to make the gap regardless of the material of the tube.

A preferred procedure is provided in that the tubular Material is expanded and pressed depending on the desired gap size. This enables the gap dimension to be determined constructively.

The invention is explained below with reference to the drawings. Show it

Figure 1a is a longitudinal section of the twist beam rear axle according to the invention with a gap in the V-shaped longitudinal profile.

FIG. 1b is a torsion beam rear axle according to Figure 1a in cross-section through the plane II-II.

FIG. 1c is a dead beam rear axle according to Figure 1a in cross-section through the plane III-III.

Figure 2a is a longitudinal section of the twist beam rear axle according to the invention with a gap outside the V-shaped longitudinal profile.

FIG. 2b shows a torsion beam rear axle according to Figure 2a in cross section through the plane II-II.

Fig. 3a-c the gradual production of a moderate invention torsion beam rear axle based on the workpiece diagrams in longitudinal section and in a perspective view.

Fig. 1a shows a torsion beam rear axle 1 with a gap 2 of the present invention in longitudinal section. The torsion beam rear axle 1 is made of tubular material, preferably sheet steel. In the unprocessed state, the tubular material has a substantially round cross section. In order to produce the torsion beam rear axle 1 , a longitudinal profile 4 is pressed into a middle length region 3 . This longitudinal profile 4 can be provided with an L, V, T, U, X or H-shaped profile cross section. In the drawing, the longitudinal profile is 4 V-shaped. The tubular material has 5 , 6 round cross sections at both ends. Between the middle length area 3 and the ends 5 , 6 , transition areas 7 , 8 are arranged, in which the longitudinal profile 4 merges into the round cross section. The longitudinal profile 4 and the transition areas 7 , 8 are provided with double walls 9 , 10 due to the tubular basic shape of the material. The walls 9 , 10 are largely firmly pressed together in the middle length region 3 and detach from one another in the transition region 7 , 8 towards the ends 5 , 6 and increasingly form the ends 5 , 6 with circular cross sections. The longitudinal profile 4 thus has two upper profile edges 11 and a lower profile edge 12 .

The gap 2 serves to reduce the relative movements of the adjacent walls 9 , 10 . When loaded while driving, the walls 9 , 10 perform relative movements. With the help of the columns 2 , which are arranged in a defined manner and adapted to the respective conditions of the twist beam rear axle 1 , abrasion or undesirable vibrations that arise can be reduced since the columns 2 form interruptions with which tensions between the walls 9 , 10 are avoided.

In Fig. 1b a torsion beam rear axle 1 in cross section through the plane II-II of FIG. 1. The plane II-II is located in the middle length region 3 of the torsion beam rear axle 1 , in which the longitudinal profile 4 is formed. In the present illustration, the longitudinal profile is V-shaped. The walls 9 , 10 abut each other and open to the ends 5 , 6 of which only the end 5 is visible in the drawing. The longitudinal profile 4 merges into the ends 5 , 6 in the transition regions 7 , 8 . In these transition areas 7 , 8 , the walls 9 , 10 are essentially spaced apart. Between the middle length area 3 and the transition areas 7 , 8 there is in each case a gap 2 , which is shown in the drawing by an elevation 13 of the inner wall 10 .

In order to form the elevation 13 on the wall 10 and thus the gap 2 , the tubular material of the twist beam rear axle 1 is expanded by inner tube expansion before the profile is formed and is shaped by a press tool adapted to the gap 2 to be formed when the longitudinal profile 4 is pressed. The walls of the profile are pressed together in the area of the gap 2 up to a predetermined distance from one another. In the remaining area of the longitudinal profile 4 , the walls 9 , 10 are pressed firmly against one another in order to produce the necessary torsional rigidity of the torsion beam rear axle 1 .

In Fig. 1c is a dead beam rear axle 1 as shown in Fig. 1b, but in cross-section through the plane III-III of FIG. 1. The plane III-III is located between the central length portion 3 and a transition portions of the torsion beam rear axle 1, in which the longitudinal profile 4 merges into the round cross section. The plane III-III, which is also the profile cross-sectional plane, intersects the gap 2 .

In FIGS. 2a and 2b are torsion beam rear axle 1 according to Fig. 1a and 1c. The gap 2 is arranged outside the longitudinal profile 4 .

In Fig. 3, the method for producing a torsion beam rear axle 1 is outlined. Fig. 3a shows the tubular material 14 in longitudinal section before processing. In order to work out the defined column 2 in the area of the longitudinal profiles 4 still to be molded, the tubular material 14 is expanded as shown in FIG. 2b. For this purpose, an expanding tool 15 is inserted into the tubular material 14 and pressed apart by a mechanism. Alternatively, the process of hydroforming can also be used. Due to the expansion, the elevation 13 is produced on the tubular material. The torsion beam rear axle 1 is then completed by generating the longitudinal profile 4 . This is shown in Fig. 3c. In order to form the longitudinal profile 4 , the expanded, tubular material 14 is inserted into a pressing tool 16 . This has a corresponding recess 17 for receiving the elevation 13 . The pressing tool comprises an upper pressing die 18 and a lower pressing die 19 , the lower pressing die in the example shown having the recess 17 and the upper pressing die 18 being provided for producing a V-shaped profile cross section. By loading the tubular material 14 , the twist beam rear axle 1 with a V-shaped profile cross section and a gap 2 outside the longitudinal profile 4 is produced, as shown in FIG. 2.

When the molds 18 , 19 are pressed together, the wall 10 of the tubular material 14 lying outside the mold 19 is acted upon such that it is essentially pressed against the wall 9 lying in the inner region of the mold 19 . The elevation 13 is formed in the area of the expansion of the tubular material 14 . In the region of the elevation 13 , the walls 9 and 10 are not pressed against one another, but rather remain separated from one another so that the gap 2 is formed.

It is intended to arrange this gap at the transition areas of the torsion beam rear axle 1 . In order to achieve optimal results, it is also provided according to the invention to distribute a plurality of gaps 2 in the central length region 3 of the longitudinal profile 4 .

In Fig. 3d, the finished torsion beam rear axle 1 is shown in a perspective view with a section through the profile cross-sectional plane. The longitudinal profile 4 is shaped in such a way that the walls 9 , 10 are essentially spaced apart. With a suitable crimping tool 16 as shown in Fig of the gap 2 can. 3c, are formed and form different but mutually corresponding molds 18, 19 the longitudinal profile 4 is pressed, the walls 9, 10 are in contact solely at the lower profiled edge 12, where there is no gap. This gives the torsion beam rear axle 1 stability, wherein the relative movements can be largely prevented, since the walls 9 , 10 do not essentially touch.

LIST OF REFERENCE NUMBERS

1

Torsion beam rear axle

2

gap

3

medium length range

4

longitudinal profile

5

The End

6

The End

7

Transition area

8th

Transition area

9

wall

10

wall

11

upper profile edge

12

lower profile edge

13

survey

14

tubular material

15

Aufdehnwerkzeug

16

press tool

17

recess

18

Upper mold

19

Lower mold

Claims (9)

1. Twist-beam rear axle ( 1 ) made of tubular material ( 14 ) for a motor vehicle, with ends ( 5 , 6 ) having essentially round cross sections, between which a middle length region ( 3 ) with a double wall ( 9 , 10 ) has longitudinal profile ( 4 ) is arranged, the walls ( 9 , 10 ) between the ends ( 5 , 6 ) and the middle length region ( 3 ) each having a transition region ( 7 , 8 ) from the circular cross section to a profile cross section, characterized in that the torsion beam rear axle ( 1 ) in the area of the longitudinal profile ( 4 ) has at least one cavity ( 2 ) and that the walls ( 9 , 10 ) of the cavity ( 2 ) are spaced apart. 2. Twist beam rear axle ( 1 ) according to claim 1, characterized in that the cavity ( 2 ) is arranged in each case in a transition region ( 7 , 8 ). 3. Twist-beam rear axle ( 1 ) according to claim 1 or 2, characterized in that the cavity ( 2 ) between the transition regions ( 7 , 8 ) and the central longitudinal region ( 3 ) has at least one local gap ( 2 ), which in the entire profile cross-sectional plane separates the walls ( 9 , 10 ) from each other. 4. Twist-beam rear axle ( 1 ) according to claim 1 to 3, characterized in that the gap ( 2 ) has essentially the shape of the longitudinal profile ( 4 ). 5. Twist-beam rear axle ( 1 ) according to claim 1 to 4, characterized in that the longitudinal profile ( 4 ) has an L, V, T, U, X or H-shaped profile cross section. 6. twist link rear axle ( 1 ) according to claim 1 to 5, characterized in that the twist link rear axle ( 1 ) is made in one piece from a tube. 7. A method for producing a twist beam rear axle ( 1 ) according to one of claims 1 to 6, characterized in that the cavity ( 2 ) before the profile formation of the longitudinal profile ( 4 ) of the central longitudinal region ( 3 ), preferably by expanding the tubular material ( 14 ), is molded on. 8. The method according to claim 7, characterized in that the tubular material ( 14 ) is used for widening for profile shaping in a press tool ( 16 ) which is provided with a recess ( 17 ) adapted to the expanded area, that the press tool ( 16 ) for the production of the longitudinal profile ( 4 ) the walls ( 9 , 10 ) of the tubular material ( 14 ) are applied and that the flared walls ( 9 , 10 ) bear at a distance from each other in the recess ( 17 ) when pressed together. 9. The method according to claim 6 or 7, characterized in that the tubular material ( 14 ) is expanded and pressed depending on the desired gap size.