Bumper beam for motor vehicle

Abstract

The invention relates to a bumper cross member (1) for a motor vehicle, comprising a cavity profile comprising three vertical webs (2, 3, 4) which are spaced apart from one another in the direction (L) of the longitudinal axis of the vehicle, and an upper and a lower narrow plate (5, 7, 6, 8) which connect the vertical webs (2, 3, 4) and are spaced apart from one another in the direction of the vertical axis of the vehicle, in this way, two cavity regions (Z1, Z2) which are arranged one behind the other in the longitudinal axis direction (L) and are separated by a central vertical strip (3) are provided. The bumper cross member (1) is characterized in that, along the extension thereof in the vertical direction, the central vertical slat (3) is supported more rigidly relative to the force acting side vertical slat (2) than the chassis side vertical slat (4) relative to the central vertical slat (3), such that when the bumper cross member (1) is deformed due to a collision force F introduced into the bumper cross member (1) against the direction of travel, the bumper cross member (1) is deformed by a collision force F introduced into the bumper cross member (1) against the direction of travel. The vertical slats (2, 3) of the cavity region Z1 on the force acting side are kept at a distance substantially due to support, and the vertical slats (4) on the chassis side are at least partially close to or in contact with the middle vertical slat (3) due to deformation.

Description

TECHNICAL FIELD

[0001] The invention relates to a bumper beam for a motor vehicle having the features of the preamble of claim 1. BACKGROUND

[0002] In the case of a frontal collision, the bumper beam serves to protect devices located behind it and the passenger compartment in the motor vehicle. The bumper beam extends transversely to the direction of travel of the vehicle and is arranged in front of the devices to be protected. The longitudinal extension of the bumper beam is in the transverse direction of the vehicle. The bumper beam is connected on its lateral end regions to longitudinal load-bearing members of the vehicle, typically to crash boxes.

[0003] Bumper beams are used not only in the front region of a motor vehicle but also in the rear region. The invention here is not limited to a particular area of application.

[0004] In absorbing forces acting on the motor vehicle from the front, whether in the context of a frontal collision or a rear collision, the bumper beam conducts the forces introduced as desired to the longitudinal load-bearing members of the motor vehicle and in particular is subjected to bending stresses. To counter this, the bumper beam has a reinforcing structure in order to prevent bending or buckling and the associated fractures as far as possible.

[0005] It is known that such a bumper beam can be formed as a hollow profile. This hollow profile is formed from vertical struts and narrow plates, in particular upper and lower narrow plates, which connect the vertical struts. The vertical struts and the narrow plates enclose one or more cavities which extend essentially in the longitudinal extension of the bumper beam. By forming a cavity, a bumper beam is provided which is resistant to bending and at the same time is lightweight.

[0006] The bumper beam can be implemented in the manner of a shell structure; one half shell is then typically connected to a closure plate, for example by means of welding. The use of two half shells which engage into one another is also conceivable.

[0007] In another design variant, the bumper beam can be designed as an extruded hollow profile. By providing an extruded profile, complex structures within the bumper beam, such as additional vertical struts or horizontal support walls, can be introduced simply and in a process-reliable manner.

[0008] EP 0 718 157 B1 discloses a bumper beam formed from a hollow profile. The bumper beam has three vertical struts which are spaced apart from one another along the longitudinal axis of the motor vehicle, the vertical struts being connected to one another on the outside at their distal ends by means of upper and lower narrow plates. The vertical strut facing the load can be referred to as the force-acting-side vertical strut. The vertical strut facing away from the load can be referred to as the chassis-side vertical strut.

[0009] The central vertical slat is additionally supported in the central region by means of a support wall on two outer vertical slats, thereby providing four separate cavities. Thus, an overall box profile is provided, which is uniformly reinforced on the inner side. The four cavities provided can be divided into two cavity regions along the central vertical slat: a cavity region on the force-acting side and a cavity region on the chassis side.

[0010] DE 601 19 187 T2 discloses a similar reinforcing device for bumpers.

[0011] The objective of this disclosure is to make the bumper beam collapse as uniformly as possible during a frontal collision, so as to avoid crack formation.

[0012] The application of this type of bumper beam is problematic, especially considering the increased requirements for intrusion length within the frame of an electric vehicle: the bumper beam, lacking an internal combustion engine, must be able to absorb significantly greater forces and must not break even after a greater deformation path. Summary of the Invention

[0013] Starting from this technical problem, the object of the present invention is to provide a bumper beam that has better performance in terms of its deformation behavior, especially at large intrusion lengths.

[0014] The objective is achieved by a bumper beam of the same type mentioned at the beginning, having the features of claim 1.

[0015] Advantageous design solutions are derived from the dependent claims and the specification.

[0016] The core of this invention is to provide a bumper beam having two sequentially arranged cavity regions along the longitudinal direction of the vehicle. These two cavity regions exhibit different and therefore asymmetrical deformation behaviors under collision conditions. To this end, the two cavity regions are designed with different stiffnesses in terms of their surface rotational inertia in the load-introduction direction.

[0017] Therefore, it is stipulated that, along its corresponding vertical extension, the middle vertical slat is more rigidly supported relative to the vertical slat on the force-applying side than the vertical slat on the chassis side relative to the middle vertical slat. Because the chassis-side vertical slat is less supported relative to the middle vertical slat in the longitudinal axis direction of the vehicle, it buckles more strongly in a collision than the middle vertical slat towards the force-applying side.

[0018] When the bumper beam deforms due to a frontal impact force acting on it, such as within the frame of a slalom test, the bumper beam—because it is supported on the longitudinal load-bearing components of the vehicle—bears the load as a bending beam. This results in a peak tensile stress on the side where the back force is introduced, and therefore on the chassis side of the bumper beam, more precisely in the longitudinal extension direction of the bumper beam, and therefore in the lateral direction of the vehicle.

[0019] According to the design of the present invention, the bumper beam achieves the following under deformation conditions: the vertical strips on the chassis side deform and buckle locally due to the applied tensile stress; therefore, the cavity area on the chassis side collapses at least partially. Meanwhile, because the middle vertical strip is more reinforced than the vertical strips on the force-applied side, the cavity area on the force-applied side essentially maintains its cross-section.

[0020] In this context, the load-facing cavity region can be referred to as a more buckling-resistant region, while the chassis-side cavity region away from the load can be referred to as a more buckling-prone region.

[0021] Therefore, even with a large intrusion path of the bumper beam, the first cavity provides a cross-section that transmits bending moment through maintained planar rotational inertia and thus ensures high bending stiffness throughout the intrusion path. The second cavity supports the transmission of bending under small deformation; under further deformation, the planar rotational inertia of the bumper beam locally decreases, resulting in a reduction in the stress peak on the load-averse side of the bumper beam. This prevents crack formation on the load-averse side of the bumper beam, and therefore the chassis side. Simultaneously, the deformation of the second cavity absorbs collision energy in a colliding chamber manner.

[0022] For a specific intrusion path, it can be stipulated that the vertical slats on the chassis side abut against the middle vertical slat. The upper and lower narrow plates connecting the vertical slats on the chassis side and the middle vertical slat will deform accordingly.

[0023] To resist the breakage of the narrow plate, it is preferably specified that the narrow plate connecting the central vertical slat to the chassis-side vertical slat is configured with a rounded bend. The radius of this rounded bend is preferably at least two times, preferably three times, the wall thickness of the narrow plate in the rounded area. If the chassis-side vertical slats are close to the central slat, the narrow plate deforms similarly to an arch, especially when these narrow plates are configured with rounded bends and extend from the first cavity area in the form of support ribs or support beads. Therefore, these additional reinforcements to the first cavity area provide the required bending stiffness. The rounded bends with a set radius further resist breakage of the narrow plate on its chassis-side side.

[0024] To intentionally influence the deformation of the vertical slats, it can be stipulated that the chassis-side vertical slats have a region that is thinner relative to the central region of the vertical slats and the narrow slats in the direction of the vehicle's vertical axis, in the area facing the narrow slats. If the chassis-side vertical slats deform towards the central slats, inflection points are created by opposite bending—the bending of the narrow slats towards the vertical slats in one direction and the bending of the vertical slats towards the vertical slats in another direction due to buckling behavior. Advantageously, the vertical slats are thinned precisely in the regions of these inflection points. Conversely, the central region is thickened to allow for the possibility of being as planar and uniformly abutting against the central slats as possible under deformation. Above this region, forces originating from the rounded narrow slats are also introduced into the central vertical slats, requiring a particularly large amount of material to be provided here.

[0025] Preferably, the thinning region thins abruptly in the z-direction within its area facing the narrow plate. This abrupt change should not be understood mathematically, but rather from the perspective of a person skilled in the art. Through this abrupt change, the area of ​​hinged movement thins substantially discontinuously as the vertical slats on the chassis side move towards the central vertical slat. By determining this location with relatively precise accuracy, the deformation behavior of the vertical slats on the chassis side can be selectively influenced.

[0026] In contrast, the central vertical slat is supported relative to the vertical slat on the force-applied side, although it is understandable that the central vertical slat also deforms to some extent under deformation, causing it to deviate towards the vertical slat on the force-applied side. However, this deformation is significantly smaller than that of the vertical slats on the chassis side. The support between the central vertical slat and the vertical slat on the force-applied side helps resist the collapse of the front cavity area.

[0027] The support of the central vertical slats relative to the vertical slats on the force-applied side can be achieved, for example, by foaming the cavity region facing the load direction from the back. Different heat treatments for the two cavity regions are also conceivable, particularly considering the corresponding vertical slats—one for the central and force-applied side, and the other for the chassis side. This also applies to corresponding combinations of different materials for the two cavity regions.

[0028] It is also conceivable that the support of the vertical slats be differentiated in the design: thus, the middle slat can be securely connected to an upper or lower narrow plate that supports the middle vertical slat relative to the vertical slat on the force-applied side, thereby supporting the middle vertical slat against buckling and preventing significant deformation of the middle vertical slat, especially the one facing the force-applied side. The middle vertical slat can also have supporting ribs protruding from it and extending vertically for reinforcement.

[0029] However, it is preferred that a support wall be provided between the middle vertical slat and the vertical slat on the force-applying side, the support wall being spaced apart from the upper or lower narrow plate, approximately at the center of the vertical slat, supporting the middle vertical slat on the vertical slat on the force-applying side. This support wall thus extends in the longitudinal axis direction of the vehicle and in the longitudinal extension direction of the bumper beam. The support wall is typically formed on both vertical slats. The support wall divides the front cavity into two cavities, while the rear cavity area is preferably designed as a single cavity and extends at the height of the two cavities in the front cavity area. This support between the middle vertical slat and the vertical slat on the force-applying side is a particularly simple and cost-effective option for efficient support.

[0030] In one design, the support wall is preferably configured to taper in its extension toward the vehicle's longitudinal axis. By widening the support wall along its height in the region where it connects to the corresponding vertical slats, the forces introduced and transmitted by the support wall are planarly introduced into the vertical slats, thereby resisting buckling of the corresponding vertical slats or breakage of the connection between the support wall and the vertical slats. Material is also saved in the central region of the support wall to provide a bumper beam that is as lightweight as possible.

[0031] If a support wall is provided in the middle region of the central vertical slats and the chassis-side vertical slats are configured to be thickened in their central region, it is preferable that the thickened portion of the chassis-side vertical slats is substantially aligned with the longitudinal extension of the support wall in a cross-sectional view. Thus, the force introduced into the central vertical slats in the event of deformation is transmitted from the rounded narrow plate through the support wall.

[0032] Similarly, the narrow plate connecting the vertical strip on the force-applying side to the middle vertical strip is configured to taper towards the middle vertical strip, and in the area connecting to the middle vertical strip, it aligns with the connection of the narrow plate connecting the middle vertical strip to the chassis-side vertical strip. When the chassis-side vertical strip deforms and the corresponding upper and lower narrow plates connecting the chassis-side vertical strip to the middle vertical strip bend as a result, the connection area on the middle vertical strip also acts as a hinge. This hinge effect becomes uniform throughout the material in the connection area by reducing the narrow plate connecting the middle vertical strip to the force-applying vertical strip. This avoids cracking in the hinge area. The corresponding upper and lower narrow plates connecting the vertical strips are aligned with each other, therefore, it is preferable for the upper and lower narrow plates to jointly form the bumper crossbeam. The vertical strips that are connected to each other, which were previously referred to as the upper narrow strip and the lower narrow strip, can also be referred to as the upper narrow strip section and the lower narrow strip section, respectively.

[0033] Preferably, the bumper crossbeam is defined on the outer side by vertical strips on the force-applying side and on the rear side by vertical strips on the chassis side. In the vertical axis direction of the vehicle, the bumper crossbeam is defined by upper and lower narrow strips, and if necessary, by upper and lower narrow strip sections. Therefore, it forms a box-shaped bumper crossbeam overall.

[0034] Furthermore, it can be preferably specified that the distance between the vertical slats on the force-applying side and the intermediate vertical slats is greater than the distance between the intermediate slats and the slats on the chassis side. The distance between the vertical slats is understood to be in the longitudinal axis direction of the vehicle. In this way, the surface rotational inertia of the beam is adjusted such that the surface center of gravity shifts from the intermediate vertical slats toward the vertical slats on the force-applying side. This achieves limited deformation of the intermediate vertical slats under deformation conditions, such that the upper and lower narrow plates deform substantially uniformly along a large radius under deformation conditions. This provides a bumper beam that deforms continuously under deformation conditions. This method also resists the formation of cracks.

[0035] Preferably, the cavity profile is supplied by an aluminum alloy, particularly extruded. Cavity profiles made of aluminum alloy are lightweight and allow for a high degree of deformation. However, the degree of deformation is limited by the material's tendency to crack when the stress peak is too high, which is generally avoided by the present invention.

[0036] In another embodiment, at least one reinforcing rib extending in the longitudinal direction of the bumper beam may be provided on the vertical slats on the side facing outwards where the force is applied. The reinforcing rib protrudes from the vertical slats toward the incoming impact force and preferably extends substantially along the entire direction of the bumper beam.

[0037] The vertical slats are equipped with additional material via reinforcing ribs. Therefore, the reinforcing ribs should be understood as additions to the existing vertical slats. Consequently, the side of the vertical slat facing away from the impact force is substantially flat in the region of the reinforcing ribs and does not arch in the direction of the impact force as in a bead-like configuration. Thus, the vertical slats form the basic structure upon which the reinforcing ribs are arranged. The reinforcing ribs are part of the cross-section of the bumper beam that absorbs bending moments.

[0038] Furthermore, the reinforcing ribs create the possibility that the distribution of tensile and compressive stresses along the cross-section of the bumper beam is affected in such a way that the neutral fiber—the plane in which tensile and compressive stresses cancel each other out—can be adjusted in terms of the center of gravity of the surface, and particularly in terms of the central vertical slat. The reinforcing ribs offset the neutral fiber towards the side of force application. Preferably, the neutral fiber is arranged in the region of the central vertical slat, more preferably slightly offset relative to the side of force application.

[0039] Furthermore, by using reinforcing ribs as vertical strips designed as part of the basic structure, the basic structure can be locally weakened in predetermined sections by reducing material, thereby further improving collision performance. Material reduction occurs along the longitudinal direction of the reinforcing ribs on the bumper beam. By reducing material, the moment of inertia of the surface is reduced locally in the cross-section with respect to the impact force to be absorbed, thus actively influencing the overall collision behavior. For this purpose, reducing material in a short section, approximately 3 to 5 cm, along the longitudinal extension of the bumper beam is sufficient.

[0040] Particularly preferably, the reinforcing ribs are arranged on the vertical strips on the force-applied side, aligned with the narrow plates of the hollow profile. This directs the force directly into the narrow plates and thus into the bumper beam in a planar manner.

[0041] Therefore, this material reduction can be used to decrease stress peaks in the bumper beam. For this purpose, material reduction is particularly applied in the area where the bumper beam connects to the longitudinal load-bearing components of the vehicle, such as the crash box. Especially in cases of large intrusion distances, the bumper beam is threatened with fracture in the area where it connects to the longitudinal load-bearing components of the vehicle. Additional reinforcing elements, such as tow sleeves, can also be introduced into the bumper beam. The bumper beam is already reinforced by other elements due to its connection to the longitudinal load-bearing section or the tow sleeve. Additional reinforcement by means of reinforcing ribs may lead to premature failure of the bumper beam. By locally reducing material in the connection area, these stress peaks are made uniform and diffused into the material, thus resisting fracture. For this purpose, material reduction is particularly applied in sections further than the connection to the longitudinal load-bearing components or the crash box. The material reduction extends beyond the connection to the longitudinal load-bearing components.

[0042] In another design, the reinforcing ribs may be specified as having reduced material in the central region of the bumper beam, particularly in at least two regions symmetrically arranged about the center of the bumper beam. The center of the bumper beam can be understood as the center in the longitudinal extension direction of the bumper beam, pointing towards the vertical direction of the vehicle. Here, material reduction is used to form predetermined bending sections, which can achieve a certain deformation in predetermined tests, such as pile tests. Through these predetermined bending sections, peak stress in the material can also be achieved by reducing the surface drag moment in the areas of material reduction, particularly on the side of the bumper beam away from the load. Typically, the areas of material reduction used for this behavior are only relatively short, at least shorter than the material reduction in the areas where the bumper beam connects to the longitudinal load-bearing members. Attached Figure Description

[0043] The invention will be explained in more detail with reference to the accompanying drawings. The drawings show: Figure 1A cross-sectional view comparing an undeformed and a deformed bumper beam according to the invention is shown. Figure 2 The undeformed bumper beam is shown in a cross-sectional view. Figure 3 The bumper beam according to the invention is shown in top view. Figure 4 Shown in top view Figure 3 The bumper beam deformed after the pile test. Figure 5 Shown in a three-dimensional view from the oblique front. Figure 1 The bumper crossbeam. Detailed Implementation

[0044] The bumper beam 1 is installed in a vehicle (not shown in detail). This bumper beam is connected to a chassis C (not shown in detail) via impact boxes C1 and C2 through longitudinal support members. The impact force F acting on the bumper beam 1 acts on the force-acting side of the bumper beam 1.

[0045] Figure 1 The bumper beam 1 is shown in cross-sectional views in its undeformed (1a) and deformed (1b) states. The undeformed cross-section is shown in dashed lines, and the deformed cross-section is shown in solid lines. Figure 3 and Figure 4 Before deformation occurs within the framework of the pile test ( Figure 3 ) and afterwards ( Figure 4 The top view shows the bumper beam 1. In the pile test, the pile P is pressed against the bumper beam 1 at the front with a predetermined force.

[0046] For details regarding the cross-sectional design, please refer to the following text for clarity. Figure 2 The bumper beam 1 is constructed as an extruded hollow profile made of aluminum alloy, and has three vertical strips 2, 3, and 4 arranged sequentially in the longitudinal direction L of the vehicle, facing the direction of travel. The middle vertical strip 3 is connected to the vertical strip 2 on one side of the force-acting side by means of upper and lower narrow plates 5, 6, 7, and 8, and to the vertical strip 4 on the chassis side on the other side. The vertical strips 2, 3, and 4 are thus supported against each other and form two hollow areas Z1 and Z2.

[0047] The force-acting side and therefore the front cavity region Z1 is formed by two cavities H1 and H2 separated by the support wall 9. The chassis side and therefore the rear cavity region Z2 is formed by a continuous cavity H3 extending beyond the two front cavities H1 and H2.

[0048] By means of a support wall 9 formed in its end region onto the intermediate vertical slat 3 and the vertical slat 2 on the force-applying side, the intermediate vertical slat 3 is more rigidly supported relative to the vertical slat 2 on the force-applying side than the vertical slat 4 on the chassis side is supported relative to the intermediate vertical slat 3. The support wall 9 is configured to be tapered (see region P6), such that force is introduced in a planar manner from either the side of the intermediate vertical slat 3 or the side of the vertical slat 2 on the force-applying side.

[0049] The distance between the vertical strip 2 on the side where the force is applied and the middle vertical strip 3, pointing in the longitudinal axis direction L of the motor vehicle, is greater than the distance between the middle vertical strip 3 and the vertical strip 4 on the chassis side.

[0050] Reference Figure 1 , Figure 3 and Figure 4 The deformation behavior of the bumper beam 1 according to the present invention will be explained in more detail as follows: During deformation, tension arises in the vertical slats 4 on the chassis side due to stretching in the longitudinal extension direction of the bumper beam 1, resulting in tension towards the collision boxes C1 and C2. These tensions, due to the resulting stress peaks, in many cases cause the slats away from the collision force F, where the vertical slats 4 on the chassis side, to break.

[0051] To counteract this, it is stipulated that the vertical slat 4 on the chassis side facing away from the impact force F provides a deformation path in the event of deformation, in such a way that the vertical slat 4 on the chassis side is supported less than the middle vertical slat 3 relative to the vertical slat 2 on the force-applying side. Due to the lack of support—here, relative to the middle vertical slat 3 within the central region P5—the vertical slat 4 on the chassis side can deform such that its central region P5 abuts against the central region 11 of the middle vertical slat 3. Thus, the central region P5 of the vertical slat 4 is supported on the central region 11 of the middle vertical slat 3. The narrow plates 7 and 8 connecting the vertical slat 4 on the chassis side and the middle vertical slat 3 are correspondingly deformed into a circular shape and form chassis-side ribs that integrally strengthen the bending resistance of the bumper beam 1. The rear cavity region Z2 collapses in this manner.

[0052] In contrast, there exists a cavity region Z1 at the front. This cavity region deforms only slightly due to the support wall 9 of the middle vertical strip 3, which reinforces the vertical strip 2 on the front side of the cavity region Z1, or rather, the vertical strip 2 on the front side of the force application. Even after deformation, it provides a bending-resistant cross-sectional profile. The two vertical strips 2 and 3 of this cavity region Z1 remain substantially spaced apart from each other despite deformation.

[0053] To facilitate the deformation of the vertical slats 4 on the chassis side, in the current reference... Figure 2 Introducing the optimized cross-section of bumper beam 1: Narrow plates 7 and 8, connecting the vertical slats 4 on the chassis side to the central vertical slat 3, are bent through a rounded portion (region P3). This rounding portion is achieved with a radius of approximately 20 mm. The narrow plates 7 and 8 transition into the vertical slats 4 on the chassis side. In region P3, there is a material that is stretched and thus thinned within the deformed frame of the vertical slats 4 on the chassis side.

[0054] A region P4 that suddenly thins out connects to region P3. After the vertical slat 4 on the chassis side deforms, this thinning region P4 essentially provides a turning point, originating from the central region P5 of the opposite curve of the rounded portions of the narrow plates 7 and 8 toward the vertical slat 4 on the chassis side. This sudden thinning provides a defining area for the hinge portion.

[0055] To reduce the load on the narrow plates 7 and 8 during further bending within the deformable frame, it is stipulated that the narrow plates 5 and 6, which connect the intermediate vertical slat 3 to the vertical slat 2 on the force-acting side, taper in the connection region P2 (region P1) to the intermediate vertical slat 3. This taper also creates hingeability in the transition region P2 of the connection region between the upper narrow plates 5 and 7 or the lower narrow plates 6 and 8 and the intermediate vertical slat 3. This hingeability provides stiffness to the front cavity region Z1 on the one hand, and resists cracking due to stress peaks within the deformable frame, particularly the deformable vertical slat 4 on the chassis side.

[0056] The bumper beam 1 shown here is further reinforced against bending by three reinforcing ribs 12, 13, and 14 aligned with the narrow plates 5 and 6 and the support wall 9. The reinforcing ribs 12, 13, and 14 are arranged on the vertical strip 2 on the force-applied side and thicken the material there toward the impact force F. The reinforcing ribs 12, 13, and 14 constitute protruding additions relative to the vertical strip 2 on the force-applied side.

[0057] As in Figure 5 As can be seen, reinforcing ribs 12, 13, and 14 extend substantially in the longitudinal direction of the bumper beam 1. Reinforcing ribs 12 and 14 are respectively located in the upper and lower regions of the end areas of the bumper beam 1. An additional reinforcing rib 13 is centrally located with respect to the height of the bumper beam 1.

[0058] The reinforcing ribs 12, 13, and 14 are configured with straight profiles facing the impact force F, thus providing planar force-introducing surfaces 15, 16, and 17. This avoids point loads.

[0059] In this embodiment, the reinforcing ribs 12, 13, and 14 are made of solid material. This allows for the possibility of individually reducing material locally through machining. In the areas of material reduction M1.1, M1.2, M2.1, and M2.2, the corresponding reinforcing ribs 12, 13, and 14 are completely interrupted in this embodiment, thereby exposing the basic structure in the form of vertical strips 2 on the force-acting side below them. Through this measure, the bumper beam 1 is intentionally designed to be softer in these areas M1.1, M1.2, M2.1, and M2.2 by reducing the surface rotational inertia resisting the impact force F. Therefore, local stress peaks are avoided, and the introduced impact force F is uniformly introduced into the bumper beam 1 in a planar manner.

[0060] Therefore, in areas M1.1 and M1.2, it is specified that reinforcing ribs 12, 13, and 14 are designed in a way that reduces material usage in a certain area where the bumper beam 1 is connected to the chassis side, for example via collision boxes C1 and C2. One of the two collision boxes C1 and C2, collision box C1, in addition to its connection to the bumper beam 1, also has a trailing sleeve A. This trailing sleeve additionally reinforces the bumper beam 1 in its connection area. To prevent the bumper beam 1 from breaking in this area, the additional rigidity is compensated for by reducing the material used in the bumper beam 1, making it softer.

[0061] Also taking into account Figure 3 The additional areas M2.1 and M2.2 of reinforcing ribs 12, 13, and 14 are areas of reduced material, more specifically in the central region of bumper beam 1, in at least two areas symmetrically arranged about the center of the bumper beam. These are used to form the intended bending section. In the pile test (see also...) Figure 4 Even in cases of large intrusion distances, these improvements improve the likelihood of abutting against the stake P marked here.

[0062] It can also be seen that, in the extending direction of the reinforcing ribs 12, 13, and 14, the transition portions 18 and 19 (shown only by way of example in the figure) for reducing the material of the reinforcing ribs 12, 13, and 14 are concavely bent with a radius of at least the protrusion height V of the reinforcing ribs 12, 13, and 14 protruding from the vertical strip 2 on the side of force application.

[0063] By machining or removing the additional reinforcing ribs 12, 13, 14 and especially the local areas M1.1, M1.2, M2.1, M2.2 of the reinforcing ribs 12, 13, 14, a simple and tool-independent possibility is created to influence the surface rotational inertia of the bumper beam 1 in such a way that stress peaks that could lead to the breakage of the bumper beam 1 are avoided.

[0064] Furthermore, the reinforcing ribs 12, 13, and 14 create the possibility that the distribution of tensile and compressive stresses along the cross-section of the bumper beam 1 is affected in such a way that the neutral fiber—the plane in which tensile and compressive stresses cancel each other out—can be adjusted about the center of gravity of the surface and, in particular, about the central vertical slat 3. The reinforcing ribs 12, 13, and 14 offset the neutral fiber towards the side of force application. Preferably, the neutral fiber is arranged within the area of ​​the central vertical slat 3, and more preferably slightly offset relative to the side of force application.

[0065] The invention has been described with reference to embodiments. Many other designs for implementing the inventive concept will be found by those skilled in the art without departing from the scope of protection described in the present claims, and these designs need not be explained in more detail within the framework of these descriptions.

[0066] List of reference numerals 1. Bumper crossbeam 2. Vertical strip on the side where the force is applied 3. The middle vertical strip 4. Vertical strips on the side of the chassis 5, 7 Narrow boards 6, 8 Narrow plates 9 Supporting walls The central area of ​​the vertical slats on the side of the P5 chassis. 11. The central area of ​​the middle vertical slats 12, 13, 14 Reinforcing ribs 15, 16, 17 Force introduction surface 18, 19 Transition Section V-shaped reinforcing rib protrusion height Areas P1 to P6 Z1 and Z2 cavity regions Areas where material is reduced in M1.1, M1.2, M2.1, and M2.2 H1, H2, H3 cavities C chassis C1, C2 collision boxes A drag sleeve L: The longitudinal axis direction of the motor vehicle P pile F Collision force

Claims

1. A bumper beam (1) for a motor vehicle, having a cavity profile comprising three vertical strips (2, 3, 4) spaced apart from each other in the longitudinal axis direction (L) of the vehicle, and upper and lower narrow plates (5, 7, 6, 8) connecting these vertical strips (2, 3, 4) and spaced apart from each other in the longitudinal axis direction of the vehicle, thereby providing two cavity regions (Z1, Z2) arranged sequentially in the longitudinal axis direction (L) and separated by an intermediate vertical strip (3), wherein, Along its vertical extension, the middle vertical strip (3) is more rigidly supported relative to the vertical strip (2) on the force-acting side than the vertical strip (4) on the chassis side relative to the middle vertical strip (3), such that when the bumper beam (1) deforms due to the impact force (F) introduced into the bumper beam (1) in the opposite direction of travel, the vertical strips (2, 3) in the cavity area (Z1) on the force-acting side remain basically spaced apart due to support, while the vertical strip (4) on the chassis side partially approaches or contacts the middle vertical strip (3) due to deformation. The feature is that the narrow plate (5, 6) connecting the vertical strip (2) on the force-acting side to the middle vertical strip (3) is configured to taper toward the middle vertical strip (3) and is aligned with the connection of the narrow plate (7, 8) connecting the middle vertical strip (3) to the vertical strip (4) on the chassis side in the area (P2) connecting to the middle vertical strip (3).

2. The bumper beam according to claim 1, characterized in that, The cavity profile is made of aluminum alloy.

3. The bumper beam according to any one of claims 1 to 2, characterized in that, In order to support the middle vertical strip (3) relative to the vertical strip (2) on the side of force application, an additional support wall (9) extending in the longitudinal axis direction (L) of the vehicle is provided between the two vertical strips (2, 3) with respect to the extension of the vertical strips (2, 3) in the vertical direction.

4. The bumper beam according to claim 3, characterized in that, The support wall (9) is configured to taper in its extension in the direction of the longitudinal axis (L) pointing toward the vehicle.

5. The bumper beam according to any one of claims 1 to 4, characterized in that, The narrow plate (7, 8) connecting the middle vertical strip (3) and the vertical strip (4) on the chassis side is configured to have a rounded bend.

6. The bumper beam according to any one of claims 1 to 5, characterized in that, The vertical strip (4) on the chassis side has a region (P4) that is thinner relative to the central region (P5) of the vertical strip (4) and the narrow plate (7, 8) in the region (P4) facing the narrow plate (7, 8) in the direction of the vehicle's vertical axis.

7. The bumper beam according to claim 6, characterized in that, The thinned region (P4) thins abruptly in the z-direction within its region facing the narrow plates (7, 8).

8. The bumper beam according to any one of claims 1 to 7, characterized in that, The distance between the vertical strip (2) on the side where the force is applied and the middle vertical strip (3) is greater than the distance between the middle vertical strip (3) and the vertical strip (4) on the side of the chassis.

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