Twist-beam axle for a motor vehicle

The invention relates to a torsion beam axle for motor vehicles.

In the automotive industry is to increase productivity, a general desire for a possible economic and efficient production of automotive components. These requirements are also subject to torsion beam axles, which combine the advantages of a simple structure with low density and good kinematic properties. Such a twist-beam axle comprising two substantially longitudinal arms which are connected by a cross member which acts as a torsion bar. To connect the trailing arm to the crossmember are different joining methods known, a welding determination is the most common.

Usually, the torsion beam axles of steel semi-finished products are manufactured. In the course of a targeted lightweight construction but also aluminum has proved itself as an over steel specifically lighter alternative.

From DE 44 16 725 A1, for example, a torsion beam axle shows which includes two by an integral cross brace of steel connected trailing arm made of aluminum or an aluminum alloy, wherein the trailing arms are manufactured by hot forming. The ends of the cross strut to be inserted in an adapted recess of the longitudinal control arm and then welded. A disadvantage of this design is the production effort and the associated costs. Moreover, the weld naturally a geometrical and metallurgical notch group which may adversely affect the strength behavior.

DE 196 04 286 C1, it also belongs to the prior art to connect the trailing arms and the ends of the cross strut shrink technically. This technology is promising. However, out of the heat load in the manufacture adverse joining stresses result.

By the generic DE 195 42 523 A1 it is known to connect the ends of the cross bar of a twist beam rear axle with trailing arms by gluing. For this purpose, the cross strut is welded at each of their ends with a pipe part made of steel material, which is glued in the respective longitudinal arm. By disconnecting the tube part for gluing in the designated area is formed as a hollow cylinder. The diameter and the wall thickness of the pipe part in the region of the weld is adjusted by uniform deformation to the diameter and the wall thickness of the cross strut in this area. Also this method of production is manufacturing technically complicated by the welding connection of the tubular parts at the ends of the crossbar. Here, too, there is the problem that the welded joint is a potential weak point in terms of their mechanical behavior.

The invention is therefore, starting from the prior art, the object of developing a torsion beam axle for motor vehicles manufacturing technology, in particular, internal stresses in the region of the transitions can be reduced by cross member to the trailing arms.

The solution of this problem lies in the features listed in the claim. 1

Advantageous refinements and developments of the basic concept of the invention form the dependent claims.

Core of the invention is the measure of connecting the trailing arms directly to the crossbar adhesive bonding, for which purpose a klebstoffbefüllbarer annular gap is formed between the ends and the recordings. This enables an efficient production at a high quality connection between trailing arm and cross member, which meets the required high safety standards. The connection is dynamic highly resilient. The recorded during operation of the trailing arms torsional and bending forces are reliably transferred to the cross member and compensated by this.

is therefore in particular not displaced from the joining zone with the use of adhesives of higher viscosity of the adhesive during the joining of the connection, it is provided that between the ends and the receptacles klebstoffbefüllbarer a ring gap is formed. In the annular gap is introduced before or after the joining of the components glue. A subsequent filling can take place via one or more apertures or bores in the components that enable an external terminal.

The annular gap may be accomplished by a suitable shaping of the receptacles or the ends. This can be done for example by a casting, a chipping or a metal forming process.

From a technological and economic point of view is to glue the ends of the cross member in shots in the trailing arm promises many advantages. One of the most noteworthy advantages is the relatively favorable internal stress state of the welded joints. While in the zone of connection of existing twist beam axles with welded or produced by means of pure press fit connections without external loads High voltages, especially joining residual stresses occurred, the present invention bonded connection of cross members and longitudinal control arms on small joining stresses.

The recordings can be configured as a stub-shaped projections, bulges or pin on arm, in or on the ends of the crossbar are plugged. In tubular, shaped by hydraulic internal high-pressure trailing arms the images are preferably formed hydroforming technology to the trailing arms. Of course, may be drafted and internally at the trailing arm shots.

The geometry of the ends and the recording to determine the flow of force between the adherends. With regard to its cross section the ends of the cross member and the recordings may have the force / form-fit between the components increasing design. For consideration is a rotationally symmetrical design of the ends and the photographs as well as in each case to the same butt-jointed cross-sectional configuration with elevations, flats or recesses. In this way maximum capacities can be realized.

Besides exclusively bonded joint of crossbar and trailing arms has an advantageous embodiment of a twist-beam axle according to the invention according to claim 2 on a glued combined / compressed trailing arm crossmember connection. The ends of the cross beam are additionally press-fitted into the receptacles of the trailing arms.

In one embodiment, the combined glued / pressed connection, the outside diameter of the ends of the cross member is slightly larger than the inner diameter of the receptacles at room temperature. To join the recordings can be heated. After cooling, then enters a compound or klebgeschrumpfte Querpressklebverbindung. Alternatively, the interference between the parts to be joined can be overcome by pressing the ends into the receptacles. It then creates a Längspressklebverbindung.

One alternative is characterized by the features in claim 3rd The connection of the ends in the seats is dimensioned as a clearance. The adhesive is applied to one or both joining faces and the components joined together. Then the game's now filled with adhesive fit is minimized by a forming operation. Ideally, the forming process has the appearance of a compressive stress in the joint zone result. This can be achieved, for example, that the shape of the components to be joined or the material of which are chosen such that the elastic deformation of the receptacle is greater than the captured ends of a cross member. Upon initiation of the forming operation, the recording deform plastically then, while the ends of the cross member only elastically deformed. After completion of the forming process, the ends spring back. It remains a compressive stress in the joining zone, which accelerating effect on the setting process of the adhesive and improves the strength of the connection.

Another important advantage of the beam axle according to the invention is that wärmearm of different materials existing trailing arm and crossmember or can even add heat free. particularly advantageous for the practice a torsion beam axle is considered according to claim 4, the crossmember is made of steel, whereas the trailing arm made of light metal, preferably, are made of aluminum or an aluminum alloy or magnesium or a magnesium alloy.

This mixed construction of a torsion beam axle allows a high degree of weight reduction while ensuring a very good elastokinetischen behavior of the torsion beam axle.

As the adhesive, among others preferably epoxy resin adhesives are used. The adhesive can be either through a chemical reaction in two-component adhesives or by a physical process, such as the evaporation of the solvent bonding,.

The bond to the joining surfaces between the trailing arms and the ends of the cross member is predominantly due to the adhesion between adhesive and metal, and the cohesive forces within the adhesive.

According to the features of claim 5 is an anaerobically curing adhesive is used. The reliable setting and so that bonding takes place in this adhesive, even without the evaporation of a solvent. The adhesive ensures a good uniform wettability of the surfaces and low internal tension after setting. The tendency to shrink during setting is low.

A likewise highly suitable for the practice of adhesive is a reactive adhesive according to the features of claim 6. A Polyadditionsklebstoff example cures without release of fission products from by an addition reaction. The adhesive is hot and cold cured without pressure and has over the anaerobic adhesive systems a higher viscosity. therefore, the use of such an adhesive is particularly appropriate due to the production-related component tolerances of trailing arms and cross member.

It is further possible the use of physically curing adhesives (claim 7), such as hot melt adhesives.

A further increase of the elastokinetischen behavior of a twist beam axle according to the features of claim 8 achieved by a cross member which has a substantially V- or U-shaped cross section in its central portion. This cross-section goes toward the ends, continuously over a circular or oval tubular cross section.

The inventively provided adhesive technical connection of the trailing arm to the crossmember is dynamic highly resilient. The load-capable connection of the cross section allows a reconciliation of torsional and bending forces of trailing arms in the crossmember. The crossbeam compensated as torsion bar the introduced forces. The twist beam axle according to the invention has been designed in produce efficiently and has good static and dynamic load behavior. Further, a weight-optimized design is possible. Contributes to this, the saving of welds, screws or rivets. Furthermore, can be combined from various metallic materials by the adhesive bond very good trailing arm and crossmember. Particularly useful is the combination of longitudinal beams of light metal on aluminum and / or magnesium base with cross beams of steel.

The invention is described below with reference to exemplary embodiments illustrated in the drawings. Show it:<dl id="dl0001"><dt>figure 1</dt><dd>a torsion beam axle in the invention technically generalized presentation;</dd><dt>figure 2</dt><dd>the detail II of figure 1 in a horizontal section;</dd><dt>figure 3</dt><dd>a side view of the illustration of Figure 2 according to the arrow III;</dd><dt>figure 4</dt><dd>in cross section a detail of the end of a cross member and a portion of a trailing arm before joining the components;</dd><dt>figure 5</dt><dd>the view according to Figure 4 after assembly of the components; </dd><dt>figure 6</dt><dd>also in cross section in each case a section from the end of a cross member and a longitudinal member before joining process;</dd><dt>figure 7</dt><dd>the representation according to Figure 6 after the joining operation;</dd><dt>figure 8</dt><dd>in cross section each having a portion of cross-member and longitudinal member of another embodiment prior to connection of the components;</dd><dt>figure 9</dt><dd>the view according to Figure 8 after the joining operation;</dd><dt>figure 10</dt><dd>a horizontal section through the representation of Figure 9 along the line X_-X with the clarity of a forming operation and</dd><dt>Figures 11 to 13</dt><dd>in the cross section shown schematically three further embodiments.</dd></dl>

The illustrations in the figures 1 to 13 are technically simplified and not to scale. In all representations corresponding components bear the same reference numerals.

1 shows a torsion beam axle 1 for front-wheel drive vehicles is schematically represented. The torsion beam axle 1 comprises two longitudinal control arms 2, 3 made of cast aluminum, which are connected by an integral cross member. 4 The crossbeam 4 acts as a torsion section and is made of strength and stiffness reasons of high strength steel. Usually, the cross-member 4 in its central region, a substantially V- or U-shaped profile, which passes its end into an approximately circular or oval cross section.

In the longitudinal control arms 2, 3 jacks 5 and 6 Wheel, shock absorber 7 and optionally 8 spring seats are type justice integrated.

In the figures 2 and 3 the detail II of figure 1 is shown in horizontal section and in the side view.

Each trailing arm 2 has a receptacle 9, which receives one end 10 of the cross member. 4 The recordings 9 are matched in their cross-sectional configuration to which the ends 10 of the cross member 4th The addition of trailing arm 2 and transverse beams 4 is made by an adhesive bond 11th For this purpose, the adhesive or joining surfaces are wetted with adhesive K and been fitted end 10 into the receptacle. 9 Here, an adhesive K high strength and resistance to aging with relevant in an application point temperature range of reliable heat resistance is used.

By the adhesion between adhesive K and metal, a combined force / form-fit is achieved with a high binding and sustainability between trailing arm 2 or 3 and cross members. 4 The torsion beam 1 of the invention is characterized by the weld-free transition from the cross member 4 to the longitudinal control arms 2; 3. Residual stresses in the transition region are minimized. also trailing arm 2, 3 and cross members 4 can advantageously be joined wärmearm of different materials.

Figures 4 and 5 show a section of a beam axle 1 with an adhesive bond 11 between the end 10 of a crossbeam 4 and the trailing arm. 2

The receptacle 9 is constructed as a nozzle-shaped extension 12 at the trailing arm. 2 The extension 12 has at its free end 13 a circumferential, inwardly directed annular collar 14th In approach 12 holes 15 are provided for the introduction of adhesive K.

After the end 10 is inserted into the receptacle 9, 15 K adhesive is introduced into the intermediate annular gap 16 through the holes. The width of the annular gap 16 is determined here X of the annular collar 14 by the width. Preferably, a solvent-free reactive adhesive K is used. A heat input can be used to bind accelerating. Further, thereby, the strength can be improved. After the setting of the adhesive K a reliable adhesive joint 11 of the longitudinal control arm 2 and transverse beams 4 is made.

Figures 6 and 7 show an embodiment of a twist-beam axle, in which the end 10 of the cross member 4 is inserted under plastic deformation of the receptacle 9 in this. The outer diameter D₁₀ the cross member 4 is according to the internal diameter in the end region 17 D₉ matched the receptacle 9, so that it can be inserted into the receptacle 9, forming an annular gap sixteenth The geometric dimensions are selected so that the end 10 of the cross member 4, the wall 18 at the free end 19 is plastically deformed when inserted into the receptacle 9 to the outside and closes.

Through the bores 15 of the formed between the end 10 and the receptacle 9 annular gap with adhesive K is filled. After curing occurs a reliable connection of cross member 4 and longitudinal members 2, a high rigidity of the adhesive joint 11th

Basically, the above-described embodiment is also suitable to apply the adhesive to the joining surfaces K and use the end 10 with a press fit in the receptacle 9 by plastic deformation of the free end 19th Holes in the wall of the receptacle are then not required.

In the figures 8 to 10 an alternative is shown in which the end 10 of the crossbeam 4 is dimensioned with clearance P. Accordingly, the outer diameter D₁₀ slightly smaller than the inner diameter D₉ 9. Recording the adhesive K is applied to one or both joining surfaces after which the end 10 is inserted into the receptacle. 9 Then the game's now filled with adhesive K fit P is minimized by a forming operation.

The forming process is illustrated with reference to FIG 10th On the outer contour of the receptacle 9 and adapted end 10 press sections 20 act on the connecting portion 21st The press pressure is indicated by the arrows U. Here, the clearance between the end 10 and receptacle 9 is minimized. This is done by plastic deformation of the holder 9, whereas the end 10 is elastically deformed and springs back after unloading. In this way, a compressive stress is built up, the beneficial effect on the joining zone or the adhesive connection 11 of the components 9, 10th It comes as a glued combined / compressed adhesive joint 11th

In the preparation of technical joining compound 11 the interaction of a different plastic and elastic deformation capacity of the receptacle 9 and the end 10 can be utilized. In this context it is advantageous if the longitudinal control arm 2 and the receptacle 9 and the cross member 4 and the ends 10 are made of materials having mutually different spring-back properties such as this, and in the combination of longitudinal control arms 2, 3 of aluminum or magnesium based crossbars 4 is the case based on steel.

The force is then the component 9 and 10 with the lower elastic deformation capacity. Due to the stronger spring-back of the other component is a press fit remains after the joining.

With the material combination aluminum / steel, for example, steel has the lower elasticity. The arrangement is designed to be a receptacle 9 is plastically deformed under the influence of an external force, while the end is deformed 10 elastically. With the material combination aluminum / steel, therefore, the external force is introduced via the component of steel. Due to the stronger spring-back of the aluminum component of a press fit remains after the joining. This affects both an accelerating effect on the setting process as well as strength-increasing effect on the connection 11th

The introduction of force at a forming process can also take place from the inside via the end 10 of a cross member 4, as shown schematically in the figure eleventh Here, the end 10 is widened from the inside by a tool 22 under force distribution F in the receptacle 9 of a trailing arm 2 of aluminum. Here, there is a deformation in the adhesive K wetted connection area and it adapts a combined glued / squeezed glue joint 11th

A further alternative is shown in the figure 12, in which the end 10 of a cross member 4 is inserted on a peg-shaped receptacle 9 of a trailing arm 2 with introduction of adhesive K. In addition, the end 10 can plastically under external forces and the recording will be 9 elastically deformed. Again, it comes with a material combination aluminum / steel to an interference fit after joining.

Finally, in the Figure 13, an embodiment is shown, in which in turn one with adhesive K filled annular gap 16 between the receptacle 9 and formed end of the tenth To this end, the receptacle 9 and the end 10 are graded. The end 10 transitions into a reduced diameter pin 24 via a shoulder 23rd The receptacle 9 has an upper portion 25 and a lower portion 26, the lower portion 26 is reduced via a step 27 compared to the diameter of the upper portion 25th The pin 24 fits a geometrically aligned and sealed in the lower section of the 26th The end 10 with its longitudinal section l₁ out in the upper portion 25th Between the upper portion 25 and the pin 24 of the adhesive-filled annular gap 16 is formed like this. By applying a joining force P_F in the axial direction of the cross member 4 is built up in the joint zone in the adhesive K a compressive stress on. Preferably, the joining force is P_F maintained during curing of the adhesive K.

<u>REFERENCE NUMBERS</u>

<dl id="dl0002" compact="compact"><dt>1 -</dt><dd>Torsion beam axle</dd><dt>2 -</dt><dd>Trailing arm</dd><dt>3 -</dt><dd>Trailing arm</dd><dt>4 -</dt><dd>crossbeam</dd><dt>5 -</dt><dd>socket</dd><dt>6 -</dt><dd>Bearing</dd><dt>7 -</dt><dd>shock absorber</dd><dt>8th -</dt><dd>spring seat</dd><dt>9 -</dt><dd>admission</dd><dt>10 -</dt><dd>End v. 4</dd><dt>11 -</dt><dd>adhesive bond</dd><dt>12 -</dt><dd>approach</dd><dt>13 -</dt><dd>free end v. 12</dd><dt>14 -</dt><dd>gorget</dd><dt>15 -</dt><dd>drilling</dd><dt>16 -</dt><dd>annular gap</dd><dt>17 -</dt><dd>end-side portion v. 2</dd><dt>18 -</dt><dd>Wall v. 9</dd><dt>19 -</dt><dd>free end v. 9</dd><dt>20 -</dt><dd>Press half</dd><dt>21 -</dt><dd>connecting portion</dd><dt>22 -</dt><dd>Tool</dd><dt>23 -</dt><dd>paragraph</dd><dt>24 -</dt><dd>spigot</dd><dt>25 -</dt><dd>upper portion v. 9</dd><dt>26 -</dt><dd>lower portion v. 9</dd><dt>27 -</dt><dd>step</dd></dl><dl id="dl0003" compact="compact"><dt>K -</dt><dd>adhesive</dd><dt>D₉ -</dt><dd>Inner diameter v. 9</dd><dt>D₁₀ -</dt><dd>Outside diameter v. 10</dd><dt>X -</dt><dd>Width v. 14</dd><dt>P -</dt><dd>Fit betw. 9 u. 10</dd><dt>U -</dt><dd>Pressedruck</dd><dt>F -</dt><dd>force</dd><dt>P_F -</dt><dd>joining force</dd><dt>l₁ -</dt><dd>Length section v. 10</dd></dl>