Bumper beam for motor vehicle

Abstract

The invention relates to a bumper cross-member (2) for a motor vehicle, which extends in the transverse direction of the motor vehicle and has a hollow cross-section, in particular a rectangular cross-section, in which a reinforcing plate (13) is embedded in the central longitudinal section. The reinforcing plate (5) is coupled to the hollow front or rear wall on one side in the longitudinal direction (X) of the motor vehicle and is spaced apart from the remaining front or rear side in the direction of the longitudinal direction (X) of the motor vehicle, and the front or rear side has a profile oriented in the longitudinal direction (X) of the motor vehicle in the region of the coupling, which profile corresponds to at least 80% of the length of the distance.

Description

Technical Field

[0001] The present invention relates to a bumper cross member. Background Art

[0002] Bumper cross members are disclosed in the prior art and can be coupled to the front or rear end of a motor vehicle body. This is typically accomplished by adding a crash box. Such bumper cross members are usually made of metallic materials, especially steel or light sheet metal, and can also be referred to as anti-collision beams, bumpers or cross members.

[0003] The bumper cross member should have sufficient stiffness to achieve a sufficient support effect, especially in a pole impact test. The design of the bumper cross member itself should be as robust as possible. When a motor vehicle impacts an object, the crash box will deform, and at this time, the impact energy is converted into deformation work.

[0004] However, the design of the bumper cross member should also deform to a certain extent without losing any remaining stiffness. For example, in a pole impact test, especially when the acting force exceeds a certain level, the bumper cross member should not bend or collapse.

[0005] For this purpose, for example, patent document WO2020053626A1 discloses a bumper cross member having a reinforcing plate in its central longitudinal section. The reinforcing plate helps to enhance the stiffness of the central region of the bumper cross member.

[0006] Compared with internal combustion engine vehicles, the bumper cross member in an electric vehicle must be designed to have higher stiffness to protect the battery or accumulator behind. This is especially applicable to a pole impact test, so as to effectively prevent the bumper cross member from intruding between the front wheels of the motor vehicle or the front part of the vehicle body.

[0007] Patent document DE4177114A1 discloses a general cross member. Summary of the Invention

[0008] The object of the present invention is to further optimize the impact performance of the bumper cross member, especially to avoid intrusion in a pole impact test.

[0009] The bumper cross member according to the present invention is applicable to a motor vehicle, especially an electric vehicle. The bumper cross member extends transversely along the motor vehicle and is especially coupled to the motor vehicle through a crash box at the front part of the vehicle body. Therefore, the bumper cross member assembly can also be referred to as a bumper cross member assembly. The cross section of the bumper cross member itself is hollow, especially having a rectangular cross section. A reinforcing plate is embedded in the central longitudinal section.

[0010] According to the present invention, the reinforcement plate is coupled, in particular joined, to the inner side of the hollow type from one side in the longitudinal direction of the motor vehicle (i.e., the front wall). Thus, the reinforcement plate is spaced apart from the remaining rear side by a certain distance, which is also measured in the longitudinal direction of the motor vehicle. For example, if the reinforcement plate is coupled to the inner side of the front wall in the bumper cross member, the rear side of the reinforcement plate is spaced apart from the rear wall by a certain distance. The front side or the front wall has a shaping portion that extends outward in the longitudinal direction of the motor vehicle at least in the longitudinal section of the reinforcement plate. "Outward" refers to the inner space of the bumper cross member. The shaping portion is formed in the region of the coupling or the coupling section with the longitudinal section of the reinforcement plate. Thereby, the shaping portion extends in the longitudinal direction of the motor vehicle for at least 80% of the above-mentioned distance, preferably more than 85%, particularly more than 90%, and very preferably more than 95%. However, the shaping portion is less than 120% of the distance, very preferably less than 110%, particularly less than 105%. For this purpose, the above-mentioned distance has a length in the longitudinal direction of the motor vehicle, and the distance extends over this length, that is, from the rear side of the reinforcement plate to the inner side of the rear wall of the hollow type. The percentage refers to the length of the distance. Particularly preferably, the length of the shaping portion in the longitudinal direction of the motor vehicle is substantially equivalent to the distance. The distance is preferably 1 mm to 6 mm, very preferably 5 mm. However, the distance should especially be at least 2 mm to 3 mm.

[0011] This unexpectedly achieves the following technical effects. The shaping portion in the region of the coupling is substantially shaped outward relative to the inner side of the bumper cross member, so that the reinforcement plate is relatively offset within the bumper cross member. In a collision scenario, due to the deformation of the bumper cross member itself, first, the region of the shaping portion will move relative to the region of the bumper cross member, so that the distance between the reinforcement plate and the inner side of the rear wall is reduced to zero. The reinforcement plate comes into contact with the inner side of the rear wall of the bumper cross member. Preferably, the front wall is deformed only in a small range of the shaping portion, and other parts of the front wall are not deformed, and the bumper cross member will not be deformed. If the collision object is further rammed, the reinforcement plate abuts against the inside of the bumper cross member. In the case of further deformation, the reinforcement plate must be deformed further together with the bumper cross member. At this stage of the collision process, the two components of the reinforcement plate and the bumper cross member are not deformed. This is exactly the advantage of the present invention, that is, to improve the local bending strength, thereby particularly effectively improving the collision performance of the bumper cross member of the present invention without, for example, increasing the material usage. Due to manufacturing tolerances, there is a distance.

[0012] Another technical effect is that the geometry of the shaping portion is especially created by two longitudinally formed folds, which will also additionally reinforce or strengthen the cross member.

[0013] The hollow type of the cross member is especially formed by a hat type with a crash plate. Very preferably, the crash plate is arranged forward in the longitudinal direction of the motor vehicle. In this way, due to the connection between the outer bulge fold of the hat type and the crash plate, the available impact surface is increased.

[0014] The cross section of the reinforcement plate itself is shaped, especially U-shaped or V-shaped or W-shaped or Ω-shaped.

[0015] Particularly preferably, the bumper crossmember itself is made of steel, in particular the impact plate is also made of steel, in particular, for example, hot-formed press-hardened steel bars can be used, and particularly preferably, a tensile strength greater than 1300 MPa can be provided in at least some areas.

[0016] The wall thickness of the crossmember, in particular of the hat profile, can be 1 mm to 3 mm, preferably 2 mm. Particularly preferably, the wall thickness of the impact plate is 1 mm to 1.5 mm, particularly preferably 1 mm to 2 mm. For example, it can be envisaged that the tensile strength Rm of the hat profile is higher than that of the impact plate. For example, the hat profile can be made of high-strength or ultra-high-strength steel or hot-formed steel, while the impact plate can be made of ordinary steel or high-strength steel or ultra-high-strength steel.

[0017] The reinforcement plate is thermally joined, in particular welded, to the impact plate on the inside. The impact plate itself is preferably thermally joined, in particular welded, to the flange of the hat profile.

[0018] The reinforcement plate is centered transversely to the motor vehicle. In particular, the reinforcement plate is 10% to 50% of the length of the bumper crossmember, preferably 20% to 40%. However, the reinforcement plate can also extend over a larger part transversely to the motor vehicle. Particularly preferably, the reinforcement plate extends transversely to the motor vehicle to at least partially overlap with the crash box. This can significantly enhance the overall stiffness of the crossmember.

[0019] The reinforcement plate itself can be designed such that its ends (the ends in the transverse direction of the motor vehicle) are tapered or narrowed with respect to the longitudinal direction of the motor vehicle. For example, this can be achieved by cutting the reinforcement plate.

[0020] The impact plate can also have a bulge instead of two outwardly protruding folds. In terms of the front wall itself, this bulge or geometry is substantially equivalent to the distance between the reinforcement plate and the inner side of the rear wall of the bumper crossmember. Description of the Drawings

[0021] The following describes more advantages, features and characteristics of the subject matter of the present invention. Preferred variants are shown in the schematic drawings. These drawings are used to clearly understand the present invention.

[0022] In the figures:

[0023] Figure 1 A top view of a bumper crossmember assembly according to the present invention is shown;

[0024] Figure 2 Shows along Figure 1 A cross-sectional view taken along the mid-section line A-A;

[0025] Figure 3a , Figure 3b and Figure 3c Show cross-sectional views taken along the section line A-A before and after a collision scenario occurs;

[0026] Figure 4a and Figure 4b shows a top view of the bumper arrangement in a collision scenario;

[0027] Figure 5a and Figure 5b shows Figure 2 an alternative variant of

[0028] Figure 6a and Figure 6b shows Figure 5a and Figure 5b an alternative variant of

[0029] Reference numerals:

[0030] 1: bumper beam assembly; 2: bumper beam; 3: crash box; 4: central longitudinal section; 5: reinforcement plate; 6: front wall of the bumper beam; 7: end of the reinforcement plate; 8: rear wall of the bumper beam; 9: welded longitudinal section; 10: non-welded longitudinal section; 11: upper flange; 12: lower flange; 13: impact plate; 14: hat profile; 15: additional longitudinal section; 16: column / pile; 17: buckling point; 18: bulge; 19: welding; 20: load relief member; 21: rear wall of the reinforcement plate; 22: protrusion / molding; 23: end; 24: inner side of the front wall of the bumper beam; 25: spacing; 26: inner side of the rear wall of the bumper beam; 27: length; 28: front side of the front wall of the bumper beam or front side of the impact plate; 29: object / obstacle; 30: rear side of the reinforcement plate; 31: wall; 32: wall; A: spacing; T: depth; T7: depth of the end of the reinforcement plate; T15: depth of the additional longitudinal section; L: length of the bumper beam; X: longitudinal direction of the motor vehicle; Y: transverse direction of the motor vehicle Detailed Description

[0031] The same reference numerals in the drawings are used for the same or similar components, and for the sake of brevity, the redundant description is omitted.

[0032] Figure 1 shows a top view of the bumper beam assembly 1. The bumper beam 2 is coupled to the crash box 3. The bumper beam assembly 1 is then coupled to the motor vehicle body (not shown in the figure). The bumper beam 2 has a substantially curved linear shape along its length. The central longitudinal section 4 can also be substantially straight.

[0033] In the central longitudinal section 4, the individual reinforcing plate 5 shown in the present figure is arranged in the bumper cross member 2 and coupled to the impact plate 13. The impact plate 13 and the reinforcing plate 5 are further coupled to the front wall or flange of the bumper cross member 2. The reinforcing plate 5, the impact plate 13, and the hollow type of the bumper cross member 2 or the bumper cross member 2 are three individual components. At each end 7 of the reinforcing plate 5, the reinforcing plate 5 tapers with its depth T. The depth T is substantially oriented in the longitudinal direction X of the motor vehicle. The longitudinal extent of the central longitudinal section 4 is about 20% to 50%, especially 20% to 40% of the length L of the bumper cross member 2. The length L refers to the transverse direction Y of the motor vehicle.

[0034] The reinforcing plate 5 has tapered ends 7, which increase the spacing A between the rear wall 8 of the bumper cross member 2 and the corresponding tapered ends 7. Throughout the longitudinal profile, the reinforcing plate 5 and the rear wall 8 of the bumper cross member 2 do not come into direct contact with each other.

[0035] In addition, the corresponding longitudinal section is designed as a welded longitudinal section 9, where the reinforcing plate is welded to the impact plate 6. Particularly preferably, the welded longitudinal section 9 is 5% to 20%, especially 5% to 10% of the central longitudinal section 4. When a collision occurs, the intermediate non-welded longitudinal section 10 will deform, or the front wall 6 and the reinforcing plate will move relative to each other. The entire longitudinal section 4 can also be welded between the front wall and the reinforcing plate.

[0036] Also particularly preferably, unloading elements 20 can be arranged on the opposite side walls of the collision box 3. The unloading elements 20 can be designed, for example, as slots, oblong holes, round holes, or even embossings. Here, the collision box 3 is weakened purposefully. In the collision situation shown in Figure 4, the collision boxes 3 can move towards each other, thereby further promoting the deflection of the bumper cross member 2, especially as Figure 4b shown.

[0037] Figure 2 shows Figure 1 a cross-sectional view taken along the section line A-A at Y = 0 in the figure. As shown, the cross-section of the bumper cross member 2 is in the shape of a hat 14, that is, the hat 14 and the front impact plate in front of the motor vehicle in the X direction. Two pleated protrusions 22 are formed on the impact plate 13. These two protrusions 18 protrude forward relative to the impact plate 13 in the longitudinal direction of the motor vehicle. The reinforcing plate 5 is coupled to the impact plate 13 within the protrusions 22. Here, the end of the web is coupled to the inner side of the impact plate 13 and thus coupled to the front wall 6. In Figure 2 the enlarged detailed view shown, there is a spacing from the inner side of the rear wall to the rear side of the reinforcing plate 5 pointing in the longitudinal direction X of the motor vehicle. This spacing 25 is substantially equivalent to the length or dimension 27 by which the protrusion protrudes from the front side of the impact plate 13.

[0038] This will generate Figure 3a and Figure 3b the technical effects of the present invention shown. Therefore, the bumper assembly will impact a collision object in the X direction of the motor vehicle. Figure 3aShows the situation at the moment just before the collision. Figure 3b Shows the state at the moment just after the object initially collides with the bumper assembly. The spacing 25 is reduced to zero. The rear side of the reinforcement plate 5 abuts against the inner side of the rear wall. In this state, as Figure 3b shown, within a few milliseconds after the first collision, the bumper cross member itself and the reinforcement plate have not deformed further.

[0039] Next, Figure 4a and Figure 4b show a comparison of the technical effects of the present invention. The bumper assembly 2 is subjected to extrusion or undergoes bending or arcuate deformation due to the column or pile 16. As Figure 4a shown, a buckling point 17 is generated, and even a crack appears in the center of the rear wall, which will cause the bumper to collapse completely immediately and cannot dissipate energy further. In this case, either no reinforcement plate is used, or a reinforcement plate 5 with non-tapered ends and not coupled to the bulge in the impact plate is used.

[0040] As Figure 4b shown, the rear wall of the bumper cross member 8 preferably further adheres closely to the tapered end 7 of the reinforcement plate 5 of the present invention, and it can be clearly seen from Figure 3c that the upper flange 11 and the lower flange 12 of the cross member and the horizontal walls 31, 32 of the reinforcement plate 5 deform in the same way simultaneously. This can prevent buckling and reduce a large amount of impact energy. Both the front wall 6 and the rear wall 8 can be displaced relative to the reinforcement plate 5 in the transverse direction of the motor vehicle. On the rear wall 8, this displacement is achieved according to the principle of a guy wire. There is a slight bulge 18 on the front wall 6, but no buckling or bending occurs. According to the present invention, this can ensure targeted deformation to dissipate energy dissipation without piercing the bumper cross member 2.

[0041] After Figure 3b the state shown does Figure 4a and Figure 4b the actual deformation shown occur, and during the state of Figure 3b , the bending moment resistance is extremely high. Figure 3a Or Figure 2 shown, the initial spacing 25 between the rear side of the reinforcement plate and the inner side of the rear wall is for meeting the tolerance requirements when manufacturing the bumper cross member with the impact plate 13. However, by purposefully utilizing or standardizing the spacing between the rear wall of the reinforcement plate and the inner side of the hollow rear wall and the protruding bulge, a favorable impact can be exerted on the collision performance.

[0042] Figure 5a and Figure 5b show embodiments similar to Figure 3a and Figure 3b , but the forward forming part or bulge is not designed as two pleats, but as an offset surface of the impact plate 13. The technical effects of the present invention can also be obtained here. Figure 5bShows the state immediately after the collision. At this time, the spacing 25 also becomes zero, and then the reinforcement plate and the bumper cross member 2 also start to deform.

[0043] Figure 6a and Figure 6b illustrates a similar Figure 5a and Figure 5b embodiment, but the cross-section of the reinforcement plate itself is W-shaped. In Figure 2 , Figure 3a and Figure 3b as well as Figure 5a and Figure 5b the cross-section of the reinforcement plate 13 itself is U-shaped or V-shaped.

Claims

1. A bumper beam (2) for a motor vehicle, the bumper beam (2) extending in a transverse direction (Y) of the motor vehicle and having a hollow cross section, in particular a cross section at least partially closed in the longitudinal direction, wherein: A reinforcing plate (13) is embedded in the central longitudinal section; It is characterized in that the reinforcing plate (13) is coupled to the hollow front wall (6) on one side in the longitudinal direction (X) of the motor vehicle and is separated from the hollow rear wall (8) by a certain distance (25) in the longitudinal direction (X) of the motor vehicle, and the front wall (6) has a molded portion (22) oriented along the longitudinal direction (X) of the motor vehicle in the coupling area, and the molded portion (22) corresponds to at least 80% and less than 120% of the distance (25).

2. The bumper beam (2) according to claim 1, characterized in that: The hollow type is designed as a hat type (14) having a collision plate (13).

3. The bumper beam (2) according to claim 1 or 2, characterized in that: The striker plate (13) is designed as the hollow front wall (6) and is arranged forward in the longitudinal direction (X) of the motor vehicle.

4. Bumper beam (2) according to the preceding claim, characterized in that The cross section of the reinforcing plate (5) is irregularly shaped, in particular, U-shaped, V-shaped or W-shaped.

5. The bumper beam (2) according to any one of the preceding claims, characterized in that The length of the reinforcing plate (5) extending in the transverse direction (Y) of the motor vehicle is 10% to 50% of the length of the bumper beam (2), preferably 20% to 40%.

6. Bumper beam (2) according to any one of the preceding claims, characterized in that The reinforcing plate (5) is coupled, in particular welded, to the front wall in its longitudinal upper portion.

7. Bumper beam (2) according to any one of the preceding claims, characterized in that The coupling wall has two folds that are raised outward in the longitudinal direction (X) of the motor vehicle, and the folds extend in the transverse direction of the motor vehicle at least in the area of ​​the reinforcing plate (5), and are particularly preferably at least 70% of the length (L) of the hollow section in the transverse direction of the motor vehicle, preferably more than 80%, in particular at least partially long enough to cover the crash box.

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