Bumper assembly for a motor vehicle

Abstract

Described is a bumper assembly 1 for a motor vehicle, comprising a bumper crossmember 2, two energy absorption components 3, 3.1 arranged at a distance from each other in the longitudinal direction of the bumper crossmember 2 and connected to the rear of the bumper crossmember 2, each equipped with a flange plate 4, 4.1 for connecting the bumper assembly 1 to the chassis of a motor vehicle, and a stiffening component 5, 5.1 assigned to each energy absorption component 3, 3.1 and arranged on the outside of each energy absorption component 3, 3.1 in the y-direction, the stiffening component 5, 5.1 being connected at one end at a distance in the longitudinal axial direction of the bumper crossmember 2 from the end of the adjacent energy absorption component 3, 3.1 on the rear of the bumper crossmember 2 and at its second end to the flange plate 4, 4.1 is connected, wherein the stiffening components are realized in the manner of a sheet metal form and each has at least two stiffening structures 6, 7 extending in the connection direction of the stiffening component 5, 5.1 between the flange plate 4, 4.1 and the bumper cross member 2, arranged at a vertical distance from each other and at a distance from the upper and lower termination of the stiffening component 5, 5.1, which counteract buckling.

Description

[0001] The invention relates to a bumper assembly for a motor vehicle with the features of the preamble of claim 1.

[0002] To protect the vehicle's safety cell and external components such as the engine, radiator, and the like, motor vehicles are equipped with a bumper assembly, at least in the front section. This bumper assembly comprises a crossmember that extends across the width of the vehicle. This crossmember is connected to the vehicle's chassis via two energy-absorbing components, known as crash boxes, spaced apart along the longitudinal axis of the crossmember, if a single load path is required. In configurations with more than one load path, more than two energy-absorbing components are arranged between the crossmember and the vehicle's chassis. These components absorb energy in the event of a collision through plastic deformation.

[0003] Since the bumper crossmember extends across the entire width of a vehicle, or at least substantially across its entire width, the energy-absorbing components attached to its rear are positioned at a distance from the ends of the bumper crossmember pointing in the y-direction. Different testing requirements for such a bumper crossmember sometimes necessitate additional stiffening of the sections of the bumper crossmember that project beyond the energy-absorbing components in the transverse direction of the vehicle. This is necessary to prevent excessive buckling during tests such as small-overlap or corner pendulum impact tests, ensuring that the impact energy is transferred into the energy-absorbing component.These additional stiffening components are supported on the rear side of the bumper crossmember and, depending on the design, on the flange plate (baseplate) located at the chassis-facing end of an energy absorption component and / or on the deformation element itself. Typically, such stiffening components are arranged perpendicular to the longitudinal extent of the adjacent energy absorption component, with the greatest distance between such a stiffening component and the energy absorption component at the rear of the bumper crossmember. The specific design of such stiffening components in a bumper assembly depends on the desired crash performance. This can vary between different vehicles.

[0004] WO 2021 / 021842 A1, for example, discloses a bumper assembly with such stiffening components supporting the outer end sections of the bumper crossmember. These stiffening components have vertical ribs, i.e., predetermined buckling points extending in the vertical direction, so that in the event of, for example, a small-overlap impact, this stiffening component can buckle at defined positions in conjunction with the energy absorption in the adjacent energy-absorbing component.

[0005] In the bumper assembly known from DE 10 2021 003 717 A1, additional plates are provided adjacent to the two energy absorption components, inclined to the longitudinal direction (x-direction) of the vehicle, acting as tension elements. These plates connect the bumper cross member to the flange plate of the energy absorption components in a tensile manner, which is intended to advantageously transfer forces from the bumper cross member to the energy absorption components.

[0006] From DE 10 2008 039 513 A1, a bumper assembly is known as an underride protection arrangement for a commercial vehicle. In this bumper assembly, the stiffening components, as well as the energy absorption components and the bumper cross member, are provided by extruded profile sections.

[0007] A support for such an additional stiffening component on the adjacent energy absorption component is known from DE 10 2019 101 718 A1. The stiffening components used in this prior art also have vertical ribs incorporated in the vertical direction so that, in the event of a central pole test, they can buckle at a defined point, just like the adjacent energy absorption component.

[0008] From US 9 045 100 B2, a bumper assembly is known in which each energy absorption component is manufactured in one piece as an extruded profile together with a stiffening component of the aforementioned type arranged for this purpose.

[0009] A bumper assembly with the features of the preamble of claim 1 is known from FR 3 058 693 A1 and also from JP 2013-169875 A. The bumper crossmember in the bumper assembly according to FR 3 058 693 A1 is designed as a closed profile. Adjacent to each crash box are two stiffening components, which are supported at one end on the flange plate and at the other end on the rear of the bumper crossmember. The stiffening components are characterized by several U-shaped structures following their respective longitudinal extent. In the subject matter of JP 2013-169875 A, only one stiffening component is provided for each crash box, which extends between the flange plate and the end section of the bumper crossmember.

[0010] Based on this discussed state of the art, the invention aims to further develop a bumper assembly of the type mentioned at the outset in such a way that it can not only be manufactured in a particularly lightweight manner with regard to the stiffening components used, but also allows for easy adaptation of its crash performance to different vehicles or vehicle derivatives.

[0011] This problem is solved according to the invention by a bumper assembly with the features of claim 1.

[0012] The directional terms used in this description – the x-direction, the y-direction, and the z-direction – are the coordinate directions of a vehicle, where the x-direction represents the longitudinal extent, the y-direction the lateral extent, and the z-direction the vertical extent (vertical axis) of the vehicle. This coordinate system is applied in the same way to the description of the energy absorption component according to the invention.

[0013] The stiffening components of this bumper assembly are manufactured using a sheet metal forming process. This means that such a stiffening component can be produced from a sheet of metal through a forming operation. The required stiffness is achieved by at least two stiffening structures extending between its end connection sections. The two stiffening structures are arranged at a vertical distance (distance in the z-direction) from each other and are designed to counteract buckling. This does not mean that such a reinforcing component cannot buckle under a corresponding load, but rather that the stiffening structures define load paths through which a force acting on the front wall of the bumper crossmember is transferred through the stiffening component into the vehicle chassis.For this purpose, such a stiffening component is connected with its end pointing away from the bumper crossmember to the flange plate of the adjacent energy absorption component, typically by a weld. The bending strength as well as the buckling behavior can be easily adapted to the required specifications by the type and design of the stiffening structures. This allows, for example, different vehicle derivatives or even vehicle types within a series to use identical parts for the bumper crossmember and the energy absorption components, with the desired differences in crash behavior achieved solely through the use of appropriately designed stiffening components.The stiffening structures can be designed to define predetermined buckling points where the reinforcement component buckles in the y-direction when a corresponding force acting in the longitudinal direction of the reinforcement component is applied. Variations in bending strength can be achieved, for example, by the depth or design of the stiffening structures. Furthermore, these stiffening structures offer the advantage that such a reinforcement component can be manufactured with a relatively thin material and still exhibit the required stiffness.

[0014] According to one embodiment, these stiffening structures are spaced apart from the upper and lower edges of the stiffening component. In another embodiment, the stiffening structures simultaneously form the upper and lower edges of the stiffening component. The stiffening structures can also be continuous along the entire length of the stiffening component. For example, a stiffening structure can be designed as a continuous U-shaped structure. Such a U-shaped feature can serve as the upper and lower edge sections of such a stiffening component. The stiffening structures can also be designed in the form of beads, preferably with rounded end sections. A V-shaped cross-section of the beads is sometimes considered advantageous due to the stiffness provided by the edge at the apex of the bead.It is also possible to design the stiffening structures as elongated holes with a modified collar. With this design of a stiffening component, it is considered sufficient if only the edges of the elongated holes extending in the connection direction are modified. A circumferential modification of the collar is also possible. When the stiffening structures are designed as elongated holes with modified collars, unlike when forming beads, there is no, or at least no significant, material thinning, as occurs on the flanks of a bead.

[0015] When designed as beads, the stiffening structures typically end before the end-side connection sections with which such a stiffening component is connected to the bumper cross member or to the flange plate.

[0016] In the case of such a stiffening component, implemented in the manner of a sheet metal form, where the stiffening structures are spaced from the upper and lower edges, it is possible to equip the upper and / or lower end with a flange angled in the direction of the longitudinal extension of the bumper crossmember and thus in the y-direction. Such a flange is typically oriented towards the adjacent energy-absorbing component, which preferably also applies to the orientation of the stiffening structures. By providing this at least one additional flange, the stiffness of such a stiffening component is improved. Furthermore, this offers another way to adapt the crash performance to the desired requirements.In such a case, the stiffening component not only has two load paths provided by the stiffening structures, but then three or four, depending on whether one or two such flanks are provided.

[0017] Such a stiffening component has a height in its end section facing the bumper crossmember that essentially corresponds to the z-extent of the bumper crossmember in this section. The stiffening component preferably contacts the rear of the bumper crossmember over its entire end face facing it. This end face can have one or more y-direction angled connection flanges with which the stiffening component is connected to the bumper crossmember, typically by welding it. In the case of multiple connection flanges, these are alternately angled in opposite directions, according to one embodiment. The height of the stiffening component can be reduced at its flange-plate end, and for space reasons, usually is.

[0018] The stiffening structures incorporated into such a stiffening component are preferably arranged with their longitudinal axes inclined relative to each other, with the longitudinal axes being further apart in the end section on the bumper crossmember side than in the opposite end section. In such an arrangement, the stiffening structures are arranged relative to each other in the manner of a truss, which has a positive effect on the force transmission from the bumper crossmember to the flange plate.

[0019] Such a stiffening component is typically welded to the bumper crossmember at its end facing the bumper crossmember, as well as to the flange plate. The flange plate preferably has a connection flange angled relative to its plane, against the outer surface of which the stiffening component rests and is welded. It is considered advantageous if there is a surface contact between the outer surface of the connection flange of the flange plate and the connection section of the stiffening component. In this case, the connection flange is angled relative to the plane of the flange plate in which the longitudinal extent of the stiffening component lies.Providing a connection flange angled relative to the flange plate also has the advantage that dimensional tolerances can be easily compensated for, since the overlap between the connection section of the stiffening component and the connection flange can vary without impairing the desired functionality or crash performance. It is therefore advantageous that the connection section of the stiffening component is not angled relative to its remaining flat surface. Providing such a connection flange angled relative to the plane of the flange also has the advantage that a relatively long weld seam can be applied to connect the stiffening component to the flange plate without adversely affecting other structures or areas through heat input. This measure improves crash performance.

[0020] In one embodiment of such a bumper assembly, the bumper crossmember, the energy absorption components, and the stiffening components are made from sheet steel blanks. All components can then be easily joined together by welding.

[0021] The invention is described below with reference to an exemplary embodiment and the accompanying figures. These show: Fig. 1: A top view of a bumper assembly according to the invention, Fig. 2: A side view of the left end area of ​​the bumper assembly of the Fig. 1, Fig. 3: a perspective side view corresponding to that of the Fig. 2, Fig. 4: the in Fig. 2 and Fig. 3 identifiable stiffening components in a single illustration, Fig. 5: a sectional view along line AA through the stiffening component, Fig. 6: a force-displacement diagram to illustrate the force absorption by the bumper assembly according to the invention during a corner pendulum impact test in comparison to bumper assemblies with other stiffening components, Fig. 7: a stiffening component according to a further embodiment for a bumper assembly according to the invention and Fig. 8: A perspective view of the right end section of a bumper assembly, facing in the direction of travel, using the stiffening component of the Fig. 7.

[0022] A bumper assembly 1 for a motor vehicle comprises a bumper crossmember 2 and two energy absorption components 3, 3.1, so-called crash boxes, which are attached to the rear of the bumper crossmember 2 at a distance from each other in the longitudinal direction. The energy absorption components 3, 3.1 each have a so-called flange plate 4, 4.1 at their end pointing away from the bumper crossmember 2, by means of which the bumper assembly 1 is connected to the chassis of a vehicle.

[0023] The bumper crossmember 2 of the embodiment shown in the figures is curved over its length extending in the y-direction, so that its front side is convex.

[0024] Adjacent to each energy absorption component 3, 3.1 on its outer side, the bumper crossmember is additionally supported at its outermost end by a stiffening component 5, 5.1 on the flange plate 4, 4.1 of the respective adjacent energy absorption component 3, 3.1. The stiffening components 5, 5.1 serve to support and thus stiffen the otherwise unsupported end sections of the bumper crossmember for the purpose of improved crash performance, especially with regard to a corner pendulum impact test according to current US requirements.

[0025] The stiffening component 5 and its connection to the bumper crossmember 2 and the flange plate 4 are described in more detail below. Since both stiffening components 5 and 5.1 are identical, the following explanations apply equally to this second stiffening component 5.1 and its connection to the bumper crossmember 2 and the flange plate 4.1.

[0026] The stiffening component 5 is inclined with respect to its longitudinal extent, which corresponds to the connection direction between the bumper crossmember 2 and the flange plate 4, relative to the longitudinal axis of the adjacent energy absorption component 3. The distance between these two components 3 and 5 is greatest in the area of ​​their respective connections to the bumper crossmember 2 and decreases towards the flange plate 4. The connection of the stiffening component 5 to the bumper crossmember 2 is therefore located at a longitudinal axial distance from the bumper-side connection area of ​​the energy absorption component 3.

[0027] The stiffening component 5 is formed from a sheet metal blank. Therefore, the stiffening component 5 is also a sheet metal forming. The stiffening component 5 has two central stiffening structures 6, 7, which are arranged at a distance from the upper and lower edges of the stiffening component 5. These are located in the Fig. 2 and Fig. Figure 3 is shown schematically. The stiffening structures 6, 7 could be ribs created by embossing. In the illustrated embodiment, however, the stiffening structures 6, 7 are elongated holes with collars flared towards the adjacent energy absorption component 3 (see Figure 3). Fig. 5) In the illustrated embodiment, the hole edge regions following the longitudinal extent of the elongated holes are flared to form collars, but not the elongated hole ends. It is also quite possible to form collared hole edge regions extending into the elongated hole ends, for example, in a configuration where the height gradually decreases towards the end apex of an elongated hole and may taper off completely. The longitudinal axes L1, L2 of the two stiffening structures 6, 7 are inclined to each other, with their distance from each other being smaller at their end facing the flange plate 4 than at their end facing the bumper cross member 2. The stiffening structure 5 extends, as shown from Fig. 2, evident at its end section on the bumper crossmember side over the entire height of the bumper crossmember 2. In the illustrated embodiment, the bumper crossmember 2 is provided by a profile open in the direction of the energy absorption components 3, 3.1. A recess 9 extending over the entire longitudinal extent of the bumper crossmember 2 is provided in the front wall 8 for the purpose of stiffening it. The end face of the stiffening component 5 facing the bumper crossmember 2 has a contour complementary to the rear contour of the bumper crossmember 2, so that it is supported over its entire height on the rear of the bumper crossmember 2. The stiffening component 5 is welded to the rear of the bumper crossmember 2 at several points. These joints are shown in Fig. 2 is identified by a grid and with the reference symbol 10.

[0028] The height of the stiffening component 5 decreases towards the flange plate 4. At its end, the stiffening component 5 has a connecting extension 11, which provides a connection section for attaching the stiffening component 5 to the flange plate 4. The connecting extension 11 is located, as also shown in the Fig. 4 is recognizable in the plane of the plate-shaped stiffening component 5. The stiffening structures 6, 7 terminate before the connection sections of the stiffening component 5 to the bumper cross member 2 – on the one hand – and to the flange plate 4 – on the other hand. The flange plate 4 carries a connection flange 12 projecting from its plane into the plane of the longitudinal extent of the stiffening component 5, the surface of which, pointing outwards in the y-direction, is the contact surface for the attachment of the connection extension 11 of the stiffening component 5. Fig. 2 the overlap between the connecting flange 12 of the flange plate 4 and the connecting extension 11 of the stiffening component 5 is visible.

[0029] Fig. Figure 4 shows the stiffening component 5 in a standalone view. In the illustrated embodiment, the ends of the stiffening structures 6, 7 facing the connection sections are rounded. This optimizes force input and transmission to the flange plate 4. The design of the stiffening structures 6, 7 as elongated holes 6.1, 7.1, each with a modified collar 6.2 or 7.2 on its longitudinally extending hole edge regions, can be seen in the sectional view of the Fig. 5. This sectional view also clearly shows that the stiffening component 5 has an angled flange 13, 14 on both its upper and lower sides. The repositioned collars 6.2, 7.2 and the flanges 13, 14 are flared out in the same direction.

[0030] The stiffening structures 6, 7 provide the two main load paths for supplying the desired bending strength of the stiffening component 5. The bent flanges 13, 14 additionally provide two further load paths, which can also be referred to as secondary load paths.

[0031] The crash performance of the stiffening component 5 shown in the figures can be influenced by the width of the elongated holes 6.1, 7.1, the height of the repositioned collars 6.2, 7.2, and the height of the flanges 13, 14. The crash performance can also be influenced by the radius of curvature with which the collars 6.1, 6.2 and the flanges 13, 14 are angled relative to the plane of the stiffening component 5.

[0032] These measures allow such a stiffening component 5 to be readily adapted to the respective requirements in order to exhibit sufficient bending strength before the stiffening component 5 buckles or flexes under higher forces. For example, to pass a corner pendulum impact test, the end section of the bumper crossmember 2 under test must only buckle when a predetermined force is exceeded, whereby the deformation path (penetration path) until buckling should be small. In the force-displacement diagram of the Fig. Figure 6 compares the behavior of the bumper assembly 1 shown in the figures with that of other bumper assemblies that differ solely in the design and / or arrangement of their stiffening components. The force-displacement curve of the bumper assembly according to the invention (curve with solid line) is shown in this diagram compared to the force-displacement curves in which the stiffening component is basically constructed like that of the described embodiment, but is not connected to the flange plate with angled connecting flange on the chassis side, but rather to the end section of the energy absorption component connected to the flange plate (dashed curve). The force-displacement curve of a bumper assembly in which the stiffening component is screwed to the flange plate on the chassis side is shown with a dotted line (dotted line).The force-displacement curve shown by a dash-dotted line is that of a bumper assembly in which the stiffening component is connected to the bumper crossmember and the flange plate, as described in the exemplary embodiments of the invention, except that the stiffening component does not have any stiffening structures. A comparison of these force-displacement curves clearly shows that the curve of the bumper assembly according to the invention exhibits significantly the best crash performance.

[0033] Fig. Figure 7 shows a further stiffening component 15 in a perspective view, with two stiffening structures 16, 16.1 spaced apart from each other in the vertical z-direction. The profiling of the stiffening component 15 with its stiffening structures 16, 16.1 is shown at the right end of the Fig. The stiffening component 15 shown in Figure 7 is clearly visible. The stiffening structures 16, 16.1 are U-shaped projections in the y-direction (direction of the longitudinal extent of a bumper crossmember). The stiffening structures 16, 16.1 each form the upper and lower edges of the stiffening component 15. The two legs of each stiffening structure 16, 16.1 are connected to each other by a web 17, 17.1. The depth of the projection, and thus the position of the webs 17, 17.1 with respect to their extent, is the same in the illustrated embodiment; the outer surfaces of the webs 17, 17.1 are aligned with each other in the vertical direction.

[0034] The stiffening structures 16, 16.1 are also inclined to each other along their longitudinal extent, specifically towards a crash box to be connected. At this end (left end of the illustration of the Fig. 7) The webs 17, 17.1 each have a connecting extension 18, 18.1, which connecting extensions 18, 18.1 serve the same purpose as the connecting extension 11 of the embodiment described in the preceding figures.

[0035] Fig. Figure 8 shows the stiffening component 15 installed in a bumper assembly 1.1. The stiffening component 15 is arranged in this assembly as described in relation to the stiffening component 5 in the preceding figures. Therefore, the same descriptions also apply to the bumper assembly 1.1 with its stiffening component 15.

[0036] Investigations on the bumper assembly 1.1 lead to the same results as those obtained from the diagram of the Fig. 6 is described for the bumper assembly 1.

[0037] The invention has been described using exemplary embodiments. Without departing from the scope of protection described by the applicable claims, numerous further embodiments of the inventive concept would be apparent to a person skilled in the art, without these needing to be explained in more detail within the scope of these explanations. Reference symbol list 1, 1.1 Bumper assembly 2 bumper crossmembers 3.1 Energy absorption component 4, 4.1 Flange plate 5, 5.1 Stiffening component 6 Stiffening structure 6.1 Slotted hole 6.2 Adjusted collar 7 Stiffening structure 7.1 Slotted hole 7.2 Adjusted collar 8 Front wall 9 In-depth study 10 joint 11 Connecting extension 12 Connection flange 13 Flange 14 flange 15 stiffening component 16, 16.1 Stiffening structure 17, 17.1 Footbridge 18, 18.1 Connecting extension L1, L2 Longitudinal axis

Claims

[1] Bumper assembly for a motor vehicle, comprising a bumper cross member (2), two energy absorption components (3, 3.1) arranged at a distance from each other in the longitudinal direction of the bumper cross member (2) and connected to the rear of the bumper cross member (2), each equipped with a flange plate (4, 4.1) for connecting the bumper assembly (1) to the chassis of a motor vehicle, and a stiffening component (5, 5.1) assigned to each energy absorption component (3, 3.1) and arranged on the outside of each energy absorption component (3, 3.1) in the y-direction, the stiffening component being connected at a first end at a distance in the longitudinal axial direction of the bumper cross member (2) from the bumper cross member-side end of the adjacent energy absorption component (3, 3.1) to the rear of the bumper cross member (2) and at its second end to the flange plate (4, 4.1) is connected, with the stiffening components (5, 5.1; 15) are realized in the manner of a sheet metal form and each has at least two stiffening structures (6, 7; 17, 17.1) extending in the connection direction of the stiffening component (5, 5.1; 15) between the flange plate (4, 4.1) and the bumper cross member (2), arranged at a vertical distance from each other and at a distance from the upper and lower termination of the stiffening component (5, 5.1), which counteract buckling. characterized by , that the bumper cross member (2) is designed as a rear-open profile, in whose front wall (8) a recess (9) following its longitudinal extent has at least in its end sections, in which a stiffening component (5, 5.1; 15) is connected to it, and that the extension of the longitudinal axes (L1, L2) of the stiffening structures (6, 7) intersects the front wall (8) adjacent to the recess (9). [2] Bumper assembly according to claim 1, characterized bythat the stiffening structures are designed as beads. [3] Bumper assembly according to claim 1, characterized by , that the stiffening structures (6, 7) are designed as elongated holes (6.1, 7.1; 17, 17.1) with reversed collars (6.2, 7.2). [4] Bumper assembly according to any one of claims 1 to 3, characterized by , that the stiffening structures (6, 7) terminate in front of the end-side connection sections with which the stiffening component (5, 5.1) is connected to the bumper cross member (2) and to the flange plate (4, 4.1). [5] Bumper assembly according to claim 1, characterized by , that the stiffening structures are designed as features extending over the entire longitudinal extent of the stiffening component (15), in particular in the form of U-shaped features. [6] Bumper assembly according to any one of claims 1 to 5, characterized by, that the distance between the spaced stiffening structures (6, 7) decreases in the direction towards the flange plate (4, 4.1). [7] Bumper assembly according to any one of claims 1 to 6, characterized by , that the stiffening component (5, 5.1; 15) has a flange (13, 14) angled on the top and / or bottom in the y-direction. [8] Bumper assembly according to any one of claims 1 to 7, characterized by , that the height of the stiffening component (5, 5.1; 15) is greater at its end facing the bumper cross member (2) than at its end connected to the flange plate (4, 4.1). [9] Bumper assembly according to any one of claims 1 to 8, characterized by , that the flange plate (4, 4.1) has on its side facing the stiffening component (5, 5.1) an angled connection flange (12) to which the stiffening component (5, 5.1) is connected with its flange plate-side end. [10] Bumper assembly according to claim 9, characterized by , that the contact surface of the connecting flange (12) of the flange plate (4, 4.1) and the contact surface of the connecting section of the stiffening component (5, 5.1) lie flat against each other. [11] Bumper assembly according to claim 9 or 10, characterized by , that the connection section of the stiffening component (5, 5.1) is provided by a connection extension (11; 18, 18.1).

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