CROSS BEAM ARRANGEMENT WITH PERFORATED AREAS

Description

[0001] The present invention relates to a cross member arrangement according to the features in the preamble of claim 1.

[0002] Cross member assemblies are known from the prior art and are used at the front or end of motor vehicles. Such a cross member assembly comprises a cross member. The cross member extends essentially across a large part of the vehicle's width in the transverse direction.

[0003] The cross member itself is mounted on longitudinal members, particularly with the integration of crash boxes. The crash boxes are positioned at the ends of the cross member, relative to the transverse direction of the vehicle. The crash boxes are then attached to the front of the longitudinal member of the vehicle or the vehicle body. The cross member can extend laterally beyond the crash boxes with its end sections.

[0004] For example, JP 2008 110679 A discloses a cross member assembly that features a hole pattern in the cross member in the connection area of ​​a crash box, which leads to deformation of the cross member in the event of a crash. Such arrangements are also known from JP 2012 206538 A1, US 2006 / 186680 A1, and KR 2009 011 5522 A.

[0005] If the cross member is impacted, the vehicle is in conflict with the target.

[0006] Firstly, the cross member must have high flexural rigidity to prevent buckling or intrusion by an object. The impact energy is then converted into deformation energy in the crash boxes, thus dampening the crash intensity.

[0007] On the other hand, the cross member itself, as well as any radiators or drive units, should protect, but also dissipate energy at least in certain crash scenarios and, in particular, deform without completely collapsing in a so-called RCAR bumper crash test or central pole test.

[0008] The object of the present invention is therefore to provide a cross member arrangement which produces improved crash properties by deformation of the cross member itself, but at the same time has a high inherent rigidity behavior.

[0009] The above-mentioned object is achieved according to the invention with a cross member arrangement having the features in claim 1.

[0010] Advantageous embodiments of the present invention are the subject of the dependent claims.

[0011] The bumper assembly is coupled to a motor vehicle via crash boxes. It has a cross member. The cross member is referred to below as the main cross member. Within the meaning of the invention, a further auxiliary cross member can be arranged. This is arranged, in particular, below the main cross member in the vertical direction of the motor vehicle. The main cross member itself is formed by a profile with a hollow cross section. In particular, this is a hollow profile with a closed cross section. The cross member is made of a light metal alloy. This is, in particular, an aluminum alloy. In particular, the hollow profile is manufactured as an extruded profile.

[0012] According to the invention, a weakened region is formed on each of the upper and lower chords of the cross member, spaced parallel to one another on both sides in the longitudinal direction of the main cross member. The weakened region is formed by a hole pattern, and the respective width of the weakened region is between 20 mm and 150 mm, with the width of the weakened region being greater than or equal to 1.5 times the depth of the weakened region. Particularly preferably, the width is greater than or equal to 2 times, in particular greater than or equal to 2.5 times, the depth of the weakened region.

[0013] In particular, the depth of the weakened area corresponds to at least 50%, preferably more than 60%, in particular more than 70%, but most preferably a maximum of 95%, in particular less than 90% of the depth of the main cross member in the weakened area at the level of the longitudinal section of the weakened area.

[0014] Preferably or optionally, additionally or alternatively, the width of the weakened area may be greater than or equal to the depth of the main cross member in the weakened area.

[0015] Firstly, according to the invention, it is possible to produce the weakened area both geometrically precisely and with minimal tooling and production effort by milling or punching or another machining or cutting process. Due to the weakened area, the cross member initially deforms in itself or in the weakened area in the event of an impact. Due to the fact that the weakened area has a width, whereby the width is oriented in the transverse direction of the vehicle, which is greater than or equal to the depth of the cross member in this area, a homogeneous or uniform global initial deformation of the cross member is generated. With a narrower area, the cross member would under certain circumstances initially deform due to a buckling process.

[0016] The hole pattern itself is made up of at least more than 3, preferably more than 4, even more than 7 holes, preferably between 10 and 40 holes. The holes can be arranged in rows or parallel and offset from one another. The area proportion of the holes in the weakened region is preferably between 5% and 50%, in particular between 10% and 20%. The holes preferably have a diameter between 5 mm and 20 mm, particularly preferably between 5 mm and 15 mm. The holes are most preferably round. However, the holes can also be elongated or oval.

[0017] The hollow profile is also referred to in particular as a hollow profile. The hollow profile can in particular be a multi-chamber hollow profile. Particularly preferably, a partition wall is arranged within the hollow profile, wherein the partition wall runs horizontally relative to the horizontal direction of the vehicle. The partition wall itself is not weakened, perforated, or deformed in the weakened area.

[0018] Particularly preferably, the front wall or rear wall of the hollow profile also has a continuous profile in the weakened area. This means that no embossing, interruptions, recesses, or similar features are homogeneously continuous in the front wall and / or rear wall in the weakened area. In the case of a main cross member having a curve around the vertical direction of the vehicle, the front wall and / or rear wall of the cross member thus have a uniform profile along the curve even in the weakened area.

[0019] Furthermore, the width of the weakened area is preferably between 30 mm and 100 mm. Alternatively or additionally, the width of the weakened area is greater than the depth of the main cross member in the weakened area. The depth of the main cross member is measured orthogonal to the central longitudinal line of the main cross member. This orthogonal line is essentially oriented in the longitudinal direction of the vehicle. Depending on the angle of curvature or course of the curvature, the orthogonal line can therefore run at an angle to the longitudinal direction of the vehicle. Particularly preferably, the width is greater than 1.1 times, in particular 1.2 times the depth of the main cross member in the weakened area. The relatively large width of the main cross member in the weakened area enables deformation of the cross member itself. This increases the energy absorption capacity of the cross member. Likewise, buckling or buckling is prevented.Buckling behavior is prevented, so that a uniform, more homogeneous deformation of the cross member occurs.

[0020] In plan view, the hole pattern can also be formed, for example, by different designs of the holes themselves, by different diameters or different distances between the holes.

[0021] However, the width of each weakened area is less than or equal to 0.1 times the internal distance between the crash boxes in the transverse direction of the vehicle. This, in turn, ensures that the weakened area is not too wide, so that the weakening does not take up too large a portion of the longitudinal extension of the main cross member.

[0022] Furthermore, the front wall and / or the rear wall of the main cross member are particularly preferably arranged in a substantially vertically oriented manner with respect to the vertical direction of the motor vehicle.

[0023] It has also proven particularly advantageous that the hole pattern of the weakened area is spaced from the front wall and / or the rear wall relative to the longitudinal direction of the vehicle, with the distance being particularly preferably at least 0.1 of the depth of the main cross member in this area. Thus, a respective edge is ensured in the area of ​​the front wall or in the area of ​​the rear wall. This edge supports the homogeneous deformation behavior in such a way that buckling precisely does not occur. If the respective hole patterns extended almost to the front wall or the rear wall, buckling could be supported here, which is precisely what the invention is intended to avoid, since homogeneous deformation behavior is desired.

[0024] Furthermore, the main cross member is particularly preferably made of an aluminum alloy, manufactured with a yield strength RP 0.2 of 200 MPa to 450 MPa, in particular 250 MPa to 350 MPa. Such an aluminum alloy has proven advantageous in conjunction with the weakened area. The weakened area is arranged in a range of 0.1 to 0.4 of the internal distance between the crash boxes in the transverse direction of the vehicle. A weakened area is thus arranged on each side of the main cross member relative to the central cross-sectional plane.

[0025] The main cross member may furthermore have a curved profile. The curvature is then related to the vertical direction of the vehicle. Furthermore, the main cross member particularly preferably has a substantially constant cross-sectional profile along its longitudinal extent. This means that the cross-sectional profile does not change substantially in terms of cross-sectional area and / or cross-sectional shape.

[0026] To further achieve homogeneous deformation behavior, it has proven advantageous if the crash boxes are arranged at an angle greater than 0° to each other. The crash boxes are thus arranged in toe-in relation to each other in the longitudinal direction of the vehicle. Consequently, the crash boxes are oriented toward the front and outward, or rather, the crash boxes are not parallel, but rather diagonally to each other. This also preferably increases the homogeneous deformation behavior of the main cross member.

[0027] Furthermore, it is particularly preferred to have an indentation or molding on the rear wall of the main cross member, at the level of the weakened area relative to the transverse direction of the vehicle. This also promotes the homogeneous deformation behavior of the main cross member in the event of a crash and prevents local buckling.

[0028] Further advantages, features, properties, and aspects of the present invention are the subject of the following description. Preferred embodiments are illustrated in schematic figures. These serve to facilitate understanding of the invention. They show: Figure 1 shows a cross member arrangement according to the invention in perspective view, Figure 2 shows an alternative embodiment to Figure 1, Figure 3 shows a crash scenario, Figure 4 shows a cross member after the crash, Figure 5 shows a cross member according to the invention and a cross member according to the prior art, Figure 6 shows a cross-sectional view along the section line VII-VII from Figure 1 Figure 7a, b different top views of a respective hole pattern in the weakened area with asymmetric design.

[0029] In the figures, the same reference symbols are used for identical or similar components, even if a repeated description is omitted for reasons of simplification.

[0030] Figure 1shows a perspective view of a cross member arrangement 1 according to the invention. This has a main cross member 2, which extends substantially in the transverse direction Y of the motor vehicle with its longitudinal direction. Crash boxes 3 are arranged in a respective end region, via which the main cross member 2 is attached to a motor vehicle (not specified in detail). The crash boxes 3 have an internal distance 4 from one another. On an upper chord 5, a weakened region 6 in the form of a hole pattern 7 is formed. The weakened region 6 has a width 8 that is greater than the depth 9 of the cross member in the weakened region 6. For illustrative purposes, the depth 9 is shown slightly offset. The arrangement of the weakened region 6 is arranged, relative to a central cross-sectional plane 10 of the main cross member 2, in a region B of 0.1 to 0.4 times the internal distance 4 between the crash boxes 3. In Figure 1shown, rather in the area outwards towards the crash boxes 3. Furthermore, the depth 20 of the weakened area 6 is shown. The width 8 of the weakened area 6 is at least 1.5 times, preferably more than 2 times, particularly preferably more than 2.5 times greater than the depth 20 of the weakened area 6. The depth 20 of the weakened area 6 is measured essentially in the vehicle longitudinal direction X. One weakened area 6 is shown on each side. Two weakened areas can also be formed on each side.

[0031] Figure 2 shows an analog arrangement of Figure 1 , whereby the weakened areas 6 are arranged in the area B, more towards the center, relative to the central cross-sectional plane 10. It is also possible to see in Figures 1 and 2that the front wall 15 has an uninterrupted profile in the weakened area 6. Furthermore, the depth 20 of the cross member between the inner sides of the crash boxes 3 is essentially constant over the longitudinal profile 12 of the cross member.

[0032] Figure 3shows a crash scenario. The main cross member 2 impacts an obstacle 11, here preferably another cross member. Furthermore, the longitudinal orientation of the crash boxes 3 to the longitudinal direction of the vehicle is arranged at an angle α greater than 0°, thus the two crash boxes 3 are oriented outwards to each other or are in toe-in to each other. The main cross member 2 has a curvature around the vertical direction Z of the vehicle. An indentation 14 can preferably be formed on the rear wall 13 of the cross member. The indentation 14 is shown here in an outer region near the crash box 3 and thus not in the weakened region 6. The front wall 15 of the cross member itself is essentially continuous and has an uninterrupted course. As an alternative to the representation of Figure 3 The crash boxes can also be arranged parallel to each other. The angle α is thus 0°.

[0033] Figure 4shows the cross member after the crash. A homogeneous deformation behavior is observed, without the cross member buckling or any other unintentional deformation.

[0034] Such unintentional uncontrolled deformation is, for example, in Figure 5 For cross members, this is shown with a continuous line. This cross member has no weakened area 6. It has buckled at a bending point 16 of the front wall 15, with only moderate impact energy absorption.

[0035] A significantly more homogeneous, larger-area deformation, which is thus optimized in terms of impact energy reduction, is shown in Figure 5Here, the dashed line shows a cross member according to the prior art. This cross member has two weakened areas due to off-center, vertical embossing in the front wall and is significantly more deformed than the main cross member 2 according to the invention with hidden off-center hole patterns. The energy absorption capacity is poorer across the entire cross member due to the very localized deformation.

[0036] Figure 6 shows a cross-sectional view along section line VII-VII of Figure 1The hole pattern 7 of the weakened area 6 is shown. This hole pattern 7 is spaced apart from a front wall 15 and a rear wall 13 of the main cross member 2. The distance 17 is preferably more than 0.1 times the depth 9 of the main cross member 2 in the weakened area 6. This creates an edge between the upper chord 5 and the front wall 15, or between the upper chord 5 and the rear wall 13. This edge prevents premature buckling of the main cross member 2 in the weakened areas 6.

[0037] In this case, the lower chord 19 is not provided with a hole pattern 7. Furthermore, an optional partition 18 is arranged horizontally, thus parallel to the upper chord 5 and lower chord 19. However, the partition 18 is continuous relative to the vertical direction of the vehicle and also has no perforation weakening or the like.

[0038] In case of Figure 7aThe hole pattern is essentially triangular. The hole pattern tapers toward the center of the cross member. Towards the outside, toward the side of the crash box 3, the hole pattern has a greater depth 20 than toward the central cross-sectional plane 10. With regard to the depth 20 of the hole pattern itself, an average value can be calculated in order to obtain a relationship to the inventive feature of the width 8 of the weakened area 6. Instead of the triangle-shaped hole pattern, a more trapezoidal hole pattern can also achieve a similar effect.

[0039] According to the design variant of Figure 7bThe respective weakened area 6 is designed asymmetrically such that the hole patterns are offset from one another. This results in a configuration that deviates from a rectangular arrangement of the weakened area in plan view. An arcuate section 22 is directed forward in the longitudinal direction X of the vehicle. For all the aforementioned embodiments, regardless of Figure 7b, it applies that an arcuate course or section 22 of the weakened area 6 directed forward in the longitudinal direction X of the vehicle has a beneficial effect on a uniform or homogeneous global deformation of the cross member. Buckling of the cross member due to a deformation is avoided by the arcuate course of the front edge or front side of the weakened area 6. A uniform deformation of the cross member is promoted by the arcuate course. The arcuate section 22 or arcuate course can follow the course of the curvature of the cross member in the case of a curved cross member. The arcuate section 22 or arcuate course can also be more curved than the arcuate course of the cross member. Such a stronger curvature is in Figure 7b shown. Reference symbol:

[0040] 1 -Cross member arrangement 2 -Main cross member 3 -Crash box 4 -Inner distance from 3 5 -Top chord 6 -Weakened area 7 -Hole pattern 8 -Width to 6 9 -Depth to 6 10 -Central cross-sectional plane to 2 11 -Obstacle 12 -Longitudinal course to 3 13 -Rear wall 14 -Indentation 15 -Front wall 16 -Buckling point 17 -Distance 18 -Partition wall 19 -Lower chord 20 -Depth to 6 21 -Row of slots 22 -Arched section α -angle X -longitudinal direction of the vehicle Y -transverse direction of the vehicle Z -vertical direction of the vehicle B -area

Claims

1. Bumper assembly which is coupled to a motor vehicle via crash boxes (3), having a main cross beam (2) which is formed by a profile which is hollow in cross-section and is produced from a light metal alloy, and wherein one weakened zone (6) is formed respectively on an upper flange (5) and / or a lower flange (19) on both sides, spaced apart parallel to one another, in the longitudinal direction of the main cross beam (2), wherein the weakened zone (6) is formed by a hole pattern (7), characterised in that the respective width (8) of the weakened zone (6) is between 20 mm and 150 mm, wherein the width (8) of the weakened zone (6) is greater than or equal to 1.5 times the depth (20) of the weakened zone (6), and in that a respective weakened zone (6) is arranged in a zone (B) of 0.1 times to 0.4 times the inner wall spacing (4) of the crash boxes (3) relative to a central cross-sectional plane (10) of the main beam (2).

2. Bumper assembly according to claim 1, characterised in that a partition wall (18) is arranged in the hollow profile, which runs horizontally oriented with respect to the horizontal direction (Y) of the vehicle.

3. Bumper assembly according to any one of the aforementioned claims, characterised in that the width (8) of the weakened zone (6) is between 30 mm and 100 mm and / or in that the width (8) of the weakened zone (6) is greater than the depth (9) of the main cross beam (2), in particular the width (8) is greater than 1.1 times the depth of the main cross beam (2).

4. Bumper assembly according to any one of the aforementioned claims, characterised in that the hole pattern (7) is formed from at least 4, in particular more than 7, holes, wherein the holes are completely recessed.

5. Bumper assembly according to any one of the aforementioned claims, characterised in that the width (8) of the weakened zone (6) is, respectively, less than or equal to 0.1 times the inner spacing (4) of the crash boxes (3) from one another.

6. Bumper assembly according to any one of the aforementioned claims, characterised in that a front wall (15) and / or a rear wall (13) of the main cross beam (2) are arranged in a vertical orientation with respect to the vertical direction (Z) of the motor vehicle.

7. Bumper assembly according to any one of the aforementioned claims, characterised in that the main cross beam (2) has a substantially constant cross-sectional profile over its longitudinal course (12), but at least the cross-sectional profile of the main cross beam (2) between the inner sides of the crash boxes (3) is substantially constant.

8. Bumper assembly according to any one of the aforementioned claims, characterised in that the main cross beam (2) has a curved course about the vertical direction (Z) of the motor vehicle.

9. Bumper assembly according to any one of the aforementioned claims, characterised in that the main cross beam (2) is formed as an extruded profile and has a yield strength Rp of 200 MPa to 450 MPa, in particular 250 MPa to 350 MPa.

10. Bumper assembly according to any one of the aforementioned claims, characterised in that the front wall (15) has an uninterrupted course in the weakened zone (6).

11. Bumper assembly according to any one of the aforementioned claims, characterised in that the hole pattern (7) has a distance to the front wall (15) and / or rear wall (13) with respect to the longitudinal direction of the motor vehicle, or a distance to the front wall is formed smaller than a distance (17) to the rear wall (13), wherein the distance (17) to the rear wall is preferably at least twice as large as the distance (17) to the front wall (15), preferably the distance is at least 0.1 of the depth (9) of the main cross beam (2).

12. Bumper assembly according to any one of the aforementioned claims, characterised in that the rear wall (13) has a depression and / or indentation (14), in particular within a distance of 150 mm from an inner side of a crash box.

13. Bumper assembly according to any one of the aforementioned claims, characterised in that two weakened zones (6) are arranged on each side of the main cross beam (2), relative to the central cross-sectional plane (10), with respect to the transverse direction Y of the motor vehicle.

14. Bumper assembly according to any one of the aforementioned claims, characterised in that a weakened zone (6) is formed only in the upper flange (5) or only in the lower flange (19) on the respective side of the main cross beam (2).

15. Bumper assembly according to any one of the aforementioned claims, characterised in that the weakened zone (6) has a forwardly directed arcuate section (22) with respect to the longitudinal direction (X) of the motor vehicle.