Crash box for a bumper assembly of a motor vehicle and crash management system with two crash boxes

Abstract

Crashbox (1) for a bumper assembly (2) of a motor vehicle with at least two closed hollow chambers (5, 6, 7) extending over their entire longitudinal extent from a bumper-side end (3) to a vehicle-side end (4), each of which is separated from each other by a partition (10, 11) running between an outer wall (8) and an inner wall (9) of the crashbox (1), characterized in that the partition (10, 11) is provided with a slot (13) at its vehicle-side end (4) in its half (12) facing the inner wall (9) of the crashbox (1).

Description

[0001] The invention relates to a crash box for a bumper assembly of a motor vehicle and a crash management system with two such crash boxes.

[0002] Crash boxes and crash management systems are generally used in all motor vehicles and have the task, in the event of a crash, of absorbing the energy introduced via the bumper assembly or a bumper support in the crash boxes by appropriate folding or deformation of the crash boxes and transferring excess energy into the frame or the longitudinal members of the vehicle in order to redirect the energy introduced into the vehicle by the crash around the passenger compartment and to minimize damage to the passenger compartment and thus reduce the risk of injury to the passengers.

[0003] In the case of purely electric vehicles, however, there is no longer a large block of components consisting of an internal combustion engine and transmission in front of the passenger compartment, as is the case with conventional vehicles powered by an internal combustion engine. Therefore, in electric vehicles, there tends to be a larger empty space behind the crash management system and between the longitudinal members, into which the obstacle can penetrate in a crash, whereas in a vehicle with an internal combustion engine, the engine also contributes to dissipating the energy introduced into the vehicle around the passenger compartment.

[0004] The crash management system of an electrically powered vehicle must therefore, together with the front and rear structures, be capable of absorbing energy up to a much higher penetration level during a crash, particularly a central one, through controlled deformation and redirecting it around the passenger compartment than in a conventional vehicle with an internal combustion engine. This places very high demands on the welded joints within the crash management system. Since electric vehicles are generally significantly heavier than conventional vehicles with internal combustion engines due to the batteries required for their electric drive, the requirements for the welded joints within the crash management system are also very demanding.In order to produce electrically powered vehicles as light as possible and to reduce emissions in a global life cycle perspective, it is therefore often sensible to use lightweight aluminium crash management systems as an alternative to steel.

[0005] In the typical tests that a crash management system must pass for the vehicle to meet insurance requirements, the folding of the crash boxes for targeted energy absorption must conform to specific specifications. Therefore, it is crucial to be able to fine-tune the force levels of the maximum peaks during the folding of the crash boxes. In addition to adjusting the profile geometry, wall thicknesses, and the use of trigger embossing, including its position, quantity, and depth, further measures must be taken to optimize the folding, energy absorption, and energy transfer of the crash boxes.

[0006] In US20200269787 A1, DE 195 17 918 A1 and US 9,102,289 B2, crash boxes according to the preamble of claim 1 are shown, with which various crash management systems are implemented. However, further improvements are needed, particularly for electrically powered vehicles.

[0007] It is therefore an object of the invention to provide a crash box for a bumper assembly of a motor vehicle in which the folding in the event of a crash and the energy transfer into the vehicle frame are further optimized and improved. Furthermore, it is an object of the invention to provide a corresponding crash management system with such crash boxes.

[0008] With regard to the crash box, this problem is solved by a crash box with all the features of claim 1. With regard to the crash management system, this problem is solved by a crash management system with all the features of claim 10. Advantageous embodiments of the invention are found in the dependent claims.

[0009] The crash box according to the invention for a bumper assembly of a motor vehicle has at least two closed hollow chambers extending along their entire longitudinal extent from a bumper-side end to a vehicle-side end, each of which is separated from the other by a partition wall running between an outer wall and an inner wall of the crash box. According to the invention, it is now provided that the respective partition wall is provided with a slot at its vehicle-side end in the half facing the inner wall of the crash box.

[0010] The use of such slots in the partition walls of the hollow chambers triggers the inward bending of the crash box in a crash scenario involving a narrow obstacle such as a post or tree trunk in a longitudinal section between the crash boxes, particularly in a central post impact. This inward bending of the crash box essentially acts like a hinge and helps to reduce tensile stresses at the external welds between the crash boxes and the longitudinal beams or the connecting elements to the longitudinal beams, thus maintaining their integrity even to a greater degree of obstacle penetration.These slots within the partition walls of the crash box's hollow chambers allow the crash boxes to bend inwards in the event of a crash, contributing to a positive obstacle impact performance, where the crash management system is able to absorb high energy levels, while the welds within the crash management system remain intact up to a high degree of obstacle penetration.

[0011] According to a first advantageous embodiment of the invention, the partition is also provided with a slot at its bumper-side end in the half facing the inner wall of the crash box. Such a slot at the bumper-side end of the inner wall also contributes significantly to the desired folding of the crash box in the event of a crash, as well as to energy absorption and the transfer of energy into the vehicle's longitudinal members. Thus, this embodiment of the invention also optimizes the performance of the crash box and the crash management system. A corresponding folding of the crash box in the event of a crash is therefore initiated not only on the vehicle side but also on the bumper side, ensuring particularly good energy absorption within the crash box through its deformation in the event of a crash, as well as effective transfer of excess energy into the vehicle's longitudinal members.

[0012] According to a particularly advantageous embodiment of the invention, it has proven especially beneficial that the length of the slot is at least 8 mm and a maximum of 35%, preferably 10% to 25%, of the length of the crash box. This slot geometry ensures particularly good energy absorption within the crash box during a crash, as well as a corresponding transfer of the excess crash energy into the vehicle's longitudinal members surrounding the passenger compartment.

[0013] The invention is further enhanced by ensuring that the width of the slot is at most four times the wall thickness of the inner wall of the crash box, and preferably up to 2 mm. This geometry also results in a particularly effective deformation effect and energy absorption within the crash box during a crash, as well as particularly good dissipation of excess energy within the vehicle's longitudinal members around the passenger compartment. Therefore, this embodiment of the invention also provides particularly good protection for the vehicle occupants within the passenger compartment in a crash.

[0014] According to a particularly advantageous embodiment of the invention, the slot can also be formed by edges of the partition that are bent away from each other. This means that the partition is cut, with one part of the partition being bent upwards in the area of ​​this cut, while the other part of the partition is bent downwards in the area of ​​the cut. This also creates a corresponding slot, which, however, can change during the deformation or bending of the crash box in such a way that longitudinal edges in the area of ​​the cut in the partition come to lie on top of each other or overlap.

[0015] In a particularly advantageous embodiment of the invention, the distance between the central longitudinal axis of the slot and the inner wall of the crash box is a maximum of 1 / 3 of the width of the crash box, preferably a maximum of 20 mm. This slot geometry within the partition of the crash box also achieves a particularly efficient folding of the crash box in the event of a crash, since initiating the folding in the area of ​​the inner wall of the crash box is desired. This embodiment of the invention achieves this in a particularly advantageous manner.

[0016] Furthermore, the slot can be designed to begin a maximum of 15 mm, preferably a maximum of 100 mm, at the vehicle-side end of the crash box and extend towards the bumper-side end, preferably as an elongated slot. The advantages of the invention are also achieved with such slot geometries.

[0017] In a further advantageous embodiment of the invention, the partition wall is provided with at least one cutout element at its bumper-side end. Such cutout elements allow the force level to be precisely controlled during the folding of the crash boxes, thereby further increasing passenger safety within the passenger compartment. These cutout elements within the partition walls of the crash box's hollow chambers assist in folding the crash box and thus significantly reduce the initial force peaks at the beginning of a crash. Furthermore, this embodiment provides additional installation space for a tow hook receptacle in the area of ​​the partition wall, which can, for example, be attached to a bumper support via a threaded element.

[0018] It has proven particularly advantageous that the at least one cutout element is formed as exactly one cutout uniformly spaced from a central longitudinal axis of the partition in the direction of the outer and inner walls. Alternatively, it can also be provided that several cutout elements, preferably uniformly spaced, are provided spaced from a central longitudinal axis of the partition, with the cutouts preferably having the same distance to the central longitudinal axis of the partition in pairs. With both alternatives, it is possible to achieve particularly good folding scenarios of the crash box and a reduction of the initial force peaks in the event of a crash.

[0019] The crash management system according to the invention comprises at least one, but preferably two, previously described crash boxes, which are connected to each other via a bumper support. The bumper support is also frequently referred to as a bumper or crossmember and is used here synonymously.

[0020] It has proven particularly advantageous that the two crash boxes of the crash management system are arranged symmetrically to a longitudinal longitudinal axis of the vehicle on the bumper support.

[0021] Further objectives, advantages, features, and applications of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. All features described and / or illustrated, individually or in any meaningful combination, constitute the subject matter of the present invention, even independently of their compilation in the claims or their cross-references.

[0022] They show: Fig. 1: A first embodiment of a crash box according to the invention in a perspective view of the bumper-side end, Fig. 2: a longitudinal section view of the crash box of the Fig. 1 above the partition wall of this crash box, Fig. 3: a cross-sectional view of a further embodiment of a crash box according to the invention with three hollow chambers and two partition walls, Fig. 4: A perspective view of the bumper-side end of the crash box of the Fig. 1, Fig. 5: a perspective view of the bumper-side end of an embodiment of a further crash box according to the invention, Fig. 6: a crash management system according to the invention directly before the impact of an obstacle in a top view and Fig. 7: the crash management system of the Fig. 6 after an impact with an obstacle in a top view.

[0023] In the Fig. Figure 1 shows a first embodiment of a crash box 1 according to the invention. The crash box 1 has two hollow chambers 5 and 6, which are separated from each other by a partition 10. The partition extends from an outer wall 8 to an inner wall 9 of the crash box 1. The partition 10 has a slot 13 at its vehicle-side end 4, which is located within the half 12 of the partition 10 facing the inner wall 9. At the bumper-side end 3 of the crash box 1, the partition 10 has a recess 15, which extends almost over the entire transverse extent of the crash box 1. This is particularly evident in the longitudinal section view of the Fig. 2 of the exemplary embodiment of the crash box of the Fig. 1. Additionally, the crash box has indentations as intended deformation points at the bumper-side end 3 in the area of ​​the four longitudinal edges, which serve the defined initial wrinkling of the crash box, for example in small-overlap and RCAR bumper crash scenarios.

[0024] In the presentation of the Fig. Figure 2 also clearly illustrates the geometry of the partition 10, whose geometry is responsible for the particularly effective folding of the crash box in the event of a crash. It is clearly visible in this illustration that the partition 10 has a greater longitudinal extent in the area of ​​the inner wall 9 of the crash box 1 than in the area of ​​the outer wall 8 of the crash box. Therefore, the cutout element 15 at the bumper-side end 3 of the crash box 1 is not mirror-symmetrical with respect to a central longitudinal axis 16 of the crash box 1, just like the partition 10 itself. The lack of mirror symmetry of the partition 10 with respect to the central longitudinal axis 16 of the crash box 1 is further emphasized by the slot 13 at the vehicle-side end 4 of the crash box 1, which is located in the half 12 of the partition 10 facing the inner wall 9.The slot 13 has a central longitudinal axis 14 that runs parallel to the central longitudinal axis 16 of the crash box 1 or the partition 10. The slot 13 is arranged near the inner wall 9 of the crash box 1, with the central longitudinal axis 14 of the slot 13 being spaced from the inner wall 9 by a maximum of one-third of the width of the crash box, preferably a maximum of 10 mm.

[0025] In the Fig. Figure 3 shows the cross-section of a further embodiment of a crash box 1 according to the invention. In contrast to the previously described embodiment, this crash box 1 now has three hollow chambers 5, 6 and 7, wherein the hollow chambers 5 and 6 are separated from each other by a partition 10 and the hollow chambers 6 and 7 by a partition 11. The partitions 10 and 11 of this embodiment correspond in their geometry to the partition 10 of the embodiment of the Fig. 1 and Fig. 2, so that the longitudinal section view of the Fig. 2 also the partition walls 10 and 11 of the Fig. 3 describes. It is clearly recognizable in the representation of the Fig. 3, that the slots 13 of the partitions 10 and 11 are again clearly located near the inner wall 9 of the crash box 1 in the half 12 of the partitions 10 and 11 facing the inner wall 9.

[0026] In the Fig. Figure 4 is now a perspective view of the crash box of the Fig. 1 is shown at its bumper-side end 3. In this representation, the cutout element 15 is again visible as cutout 17 in its entire extent at the bumper-side end 3 of the crash box 1.

[0027] In the Fig. Figure 5 shows a further embodiment of a crash box according to the invention in a perspective view of the bumper-side end of the crash box 1. In contrast to the embodiment of the Fig. 1, Fig. 2 and Fig. 4 This embodiment features a partition 10, at the bumper-side end 3 of which two cutout elements 15 in the form of cutouts 18 and 19 are arranged. These cutouts 18 and 19 are each located away from a central longitudinal axis 16 of the partition 10 or the crash box 1 in the area of ​​the outer wall 8 and the inner wall 9 of the crash box 1, respectively. At its vehicle-side end 4 of the crash box 1, the partition 10 of this embodiment is configured according to the embodiment of Fig. 1, Fig. 2 and Fig. 4 trained.

[0028] In the Fig. Figure 6 now shows a crash management system that connects two of the previously described crash boxes 1 according to the invention by means of a bumper support 20. The crash boxes 1 each have an inner wall 9 and an outer wall 8 and are designed to be mirror-symmetrical about a central longitudinal axis 21 of the crash management system. Fig. Figure 6 shows the crash management system immediately before an impact with an obstacle 22. The impact of the obstacle 22 occurs centrally in the area of ​​the central longitudinal axis 21 of the crash management system. This is also referred to as a center pole test.

[0029] In the Fig. 7 is now the crash management system of the Fig. Figure 6 shows the crash management system after the obstacle 22 penetrated the system, with the dashed lines representing the crash management system before the impact, i.e., according to the Fig. 6. As can be seen from the representation of the Fig.As can be seen in Figure 7, the bumper support 20 was pushed inwards by the obstacle 22, and the crash boxes 1 were deformed accordingly inwards in the area of ​​their respective inner walls 9, with the outer walls 8 of the crash boxes 1 also being deformed accordingly. The design of the crash boxes 1 according to the invention achieves particularly good deformation or folding of the crash boxes, thus reducing the risk of failure of the welded connections (or alternative screw connections) between the crash box and the vehicle longitudinal member, and ensuring particularly effective energy absorption by the crash boxes 1 and the transfer of excess energy into the vehicle longitudinal members around the passenger compartment. The effect according to the invention can also be achieved in the case of non-central impact events that are locally limited between the crash boxes. Reference symbol list 1 Crashbox 2 Bumper arrangement 3 bumper-side end 4 vehicle-side end 5 hollow chamber 6 hollow chambers 7 Hollow chamber 8 Exterior wall 9 Interior wall 10 Partition wall 11 Partition wall 12 Half 13 slots 14 Central longitudinal axis 15 cutout element 16 Central longitudinal axis 17 Excerpt 18 Excerpt 19 Excerpt 20 bumper supports 21 Vehicle longitudinal axis 22nd obstacle QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 20200269787 A1

[0006] DE 19517918 A1

[0006] US 9102289 B2

[0006]

Claims

[1] Crashbox (1) for a bumper assembly (2) of a motor vehicle with at least two closed hollow chambers (5, 6, 7) extending over their entire longitudinal extent from a bumper-side end (3) to a vehicle-side end (4), each of which is separated from each other by a partition (10, 11) running between an outer wall (8) and an inner wall (9) of the crashbox (1), characterized by , that the partition (10, 11) is provided with a slot (13) at its vehicle-side end (4) in its half (12) facing the inner wall (9) of the crash box (1). [2] Crashbox according to claim 1, characterized by , that the partition (10, 11) is provided with a slot (13) at its bumper-side end (3) in its half (12) facing the inner wall (9) of the crash box (1). [3] Crashbox according to claim 1 or 2, characterized by, that the length of the slot (13) is at least 8 mm and at most 35%, preferably 10% to 25% of the length of the crashbox (1). [4] Crashbox according to claims 1 to 3, characterized by , that the width of the slot (13) is at most four times the wall thickness of the inner wall (9) of the crash box (1) and preferably up to 2 mm. [5] Crashbox according to any one of the preceding claims, characterized by , that the slot (13) is formed by edges of the partition (10, 11) that are bent away from each other. [6] Crashbox according to any one of the preceding claims, characterized by , that the distance of a central longitudinal axis (14) of the slot (13) from the inner wall (9) of the crash box (1) is at most one third of the width of the crash box (1), preferably at most 20 mm. [7] Crashbox according to any one of the preceding claims, characterized by, that the slot starts a maximum of 15 mm, preferably a maximum of 100 mm from the vehicle-side end (4) of the crash box (1) and extends towards the bumper-side end (3) and is preferably designed as an elongated slot. [8] Crash management system with two crash boxes (1) which are connected to each other via a bumper support (20), wherein at least one of the crash boxes (1) is designed according to at least one of the preceding claims. [9] Crash management system according to claim 8, characterized by , that at least one of the crash boxes (1) is provided with at least one cutout element (15) at its bumper-side end (3). [10] Crash management system according to claim 9, characterized by , that at least one cutout element (15) is designed as exactly one cutout (17) which is preferably spaced evenly from a central longitudinal axis (16) of the partition wall (10, 11) in the direction of the outer wall (8) and the inner wall (9). [11] Crash management system according to claim 9, characterized by , that the at least one cutout element (15) is designed as several cutouts (18, 19) which are preferably spaced evenly apart from a central longitudinal axis (16) of the partition (10, 11), wherein the cutouts (18, 19) are particularly preferably arranged in pairs at the same distance to the central longitudinal axis (16) of the partition (10, 11).

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