Arrangement of a pedestrian protection crossbeam in the front section of a motor vehicle

Abstract

Arrangement of a pedestrian protection cross member (20) in a front section (12) of a motor vehicle (10), wherein the pedestrian protection cross member (20) is arranged below a bumper main cross member (14) and behind the outer skin panels of the motor vehicle (10) when viewed in the vertical direction of the vehicle, characterized in that the pedestrian protection cross member (20) is fixed to a support element (24) of the motor vehicle (10) via at least one spring element (22) such that the pedestrian protection cross member (20) is displaceable in the longitudinal direction of the vehicle and the arrangement enables a reversible relative movement between the pedestrian protection cross member (20) and the support element (24) in the longitudinal direction of the vehicle.

Description

[0001] The invention relates to an arrangement of a pedestrian protection crossbeam in a front section of a motor vehicle according to the preamble of claim 1.

[0002] US Patent 2011 / 0 227 353 A1 discloses an arrangement in a motor vehicle in which the outer skin of the motor vehicle is supported on a bumper main crossmember via a spring element. DE 10 2006 035 833 A1 also discloses a device in which the outer skin of a motor vehicle is indirectly supported on a stationary component via spring elements. US Patent 7 097 222 B2 discloses a device which, among other things, is arranged between a radiator and an engine and has two retaining elements connected by springs. DE 103 25 992 A1 discloses an air-supported deformation element which is arranged in front of a bumper main crossmember. US Patent 2013 / 0 113 226 A1 discloses an arrangement which has a deformation element between an outer skin and a bumper main crossmember. From US 2013 / 0 193 698 A1, a system is known which is arranged on the outside of the outer skin of a vehicle.From DE 10 2010 056 390 A1 a front area of ​​a motor vehicle is known, wherein the lower front area has a facing apron and is elastically deformable.

[0003] The aforementioned documents concern instructions relating to a main bumper crossmember. They make no reference to a pedestrian protection crossmember.

[0004] From DE 10 2014 011 134 A1, a pedestrian protection crossbeam is known which has a load / deformation characteristic with three stages. To realize this characteristic, it is proposed, among other things, to design the pedestrian protection crossbeam in two parts, wherein the two parts are connected by means of a bolt and a nut, and to achieve a displacement, the clamping force generated by the connection must first be overcome.

[0005] German patent DE 2011 119 542 A1 discloses an arrangement of a pedestrian protection crossmember which, viewed in the vertical direction of the vehicle, is located below a main bumper crossmember in the front of a motor vehicle. The pedestrian protection crossmember is rigidly connected to the main bumper crossmember via vertical struts that extend predominantly in the vertical direction of the vehicle. A disadvantage of this arrangement is that, in the event of a force acting on the pedestrian protection crossmember, undesirable shear and moment loads can occur on the main bumper crossmember via the vertical struts. Furthermore, for reasons of pedestrian protection, only certain relative arrangements of pedestrian protection crossmembers and main bumper crossmembers are permissible.

[0006] The invention is based on the objective of providing a functionally improved arrangement of a pedestrian protection crossmember in the front section of a motor vehicle. In particular, it aims to avoid undesirable shear and moment loads on the bumper's main crossmember, increase design freedom, and improve pedestrian protection.

[0007] The problem is solved according to the invention with the features of claim 1. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

[0008] In an arrangement according to the invention of a pedestrian protection crossmember – typically extending over a large part of the width of a motor vehicle – in the front section of a motor vehicle, the pedestrian protection crossmember, viewed in the vertical direction of the vehicle, is arranged below the main bumper crossmember and behind the body panels forming the outer skin of the motor vehicle. The pedestrian protection crossmember is fixed to a support element of the motor vehicle by means of at least one spring element such that the pedestrian protection crossmember is displaceable in the longitudinal direction of the vehicle and the arrangement allows a reversible relative movement between the pedestrian protection crossmember and the support element in the longitudinal direction of the vehicle. "Displaceable" here refers to a reversible, spring-elastic displacement in which potential energy is absorbed by the spring element and subsequently released.

[0009] In this context, a support element is understood to be any element directly or indirectly attached to the body shell of the motor vehicle. This includes, in particular, elements located behind the pedestrian protection crossmember when viewed in the longitudinal direction of the vehicle, such as auxiliary supports made of plastic or steel.

[0010] In this context, the term "front section" of a motor vehicle refers to the area of ​​the vehicle extending from the front to the interior of the vehicle, wherein the arrangement according to the invention is located in the area of ​​the front of the vehicle, in particular, viewed in the longitudinal direction of the vehicle, from the front of the outer skin to a mounting bracket for a radiator module. The term "bumper main crossmember" refers to the crossmember in the area of ​​the front section of a motor vehicle, which is typically designed with the greatest bending stiffness and is usually connected to two lateral main longitudinal members of the vehicle via so-called crash boxes (also called deformation elements).

[0011] The arrangement according to the invention enables reversible relative movement between the pedestrian protection crossmember and the support element in the longitudinal direction of the vehicle. This allows forces occurring in the event of a pedestrian impact—particularly in the leg area—to be absorbed via a spring travel path, converted into potential energy, and "returned" to the pedestrian. This can be advantageously used for pedestrian protection, as will be explained in more detail below. When a pedestrian impacts the front of a motor vehicle, the knee typically impacts an upper load plane at the level of the bumper's main crossmember, the thigh in the area of ​​the hood, and the lower leg impacts a lower load plane at the level of the pedestrian protection crossmember. The pedestrian protection crossmember is intended, in particular, to prevent hyperextension in the knee area of ​​an impacting pedestrian.This requires an early return movement of the lower leg. An arrangement according to the invention allows the lower leg to be accelerated from the lower load plane during this return movement. This effect can be used to improve pedestrian protection and reduce potentially limiting hyperextension of the knee by accelerating the lower leg, and / or to benefit from increased design freedom by positioning the pedestrian protection crossmember further rearward in the longitudinal direction of the vehicle relative to the main bumper crossmember.

[0012] The arrangement according to the invention has the further advantage that the pedestrian protection cross member can be decoupled from the bumper main cross member, since the connection can be made to any other support element, in particular to a support element that is arranged at approximately the same height as the pedestrian protection cross member, so that, if possible, a purely translational displacement of the pedestrian protection cross member takes place without any design-related twisting movement during the spring-elastic displacement and thus no shear and moment loads occur on the bumper main cross member.

[0013] For arrangements according to the invention, spring elements are particularly suitable in which only minor losses occur during the conversion of kinetic energy into potential energy and back into kinetic energy, and consequently, the resulting efficiency is high. Spring elements with an efficiency of at least 80% are preferred, particularly preferably at least 90%, and more preferably at least 95%. Accordingly, damping elements or elements that predominantly deform plastically, in which a large proportion of the kinetic energy is used for plastic deformation of the element, are not spring elements within the meaning of the invention. Spring elements within the meaning of the invention are, in particular, helical springs, spring elements designed as bending springs, and other springs in the technical sense.

[0014] In a practical embodiment of the arrangement according to the invention, the at least one spring element is arranged, viewed in the longitudinal direction of the vehicle, between the support element and the pedestrian protection crossbeam. It thus bridges, in particular, a gap between the support element and the pedestrian protection crossbeam. In this case, a spring-elastic displacement of the pedestrian protection crossbeam in the direction of a support element located behind it, and fixed in the vehicle's body shell, is particularly easy to achieve using springs, for example, coil springs.

[0015] Due to relative movement between the pedestrian protection crossbeam and the support element, the spring element is deformed elastically, e.g., bent, stretched, or compressed, and absorbs potential energy in the process. The spring element then releases a large portion of this energy briefly to at least partially reverse the relative movement.

[0016] Regardless of the type of spring element used, it may be preferable to arrange several spring elements distributed across the width of the pedestrian protection crossbeam in order to achieve the most uniform restoring force effect possible across the width.

[0017] In a further cost-effective embodiment of the arrangement according to the invention, the spring element is arranged or designed to project outwards in the transverse direction of the vehicle over at least one lateral end of the pedestrian protection crossbeam and / or over at least one lateral end of the support element. The spring element is preferably designed at least partially as a bending spring and bridges a gap between an end of the pedestrian protection crossbeam and the support element and / or between an end of the support element and the pedestrian protection crossbeam. This embodiment is particularly suitable for pedestrian protection crossbeams that are attached to support elements extending over a large part of the width, which can be arranged in front of or behind the pedestrian protection crossbeam in the longitudinal direction of the vehicle.In conjunction with this embodiment, flexible steel sheet strips are particularly suitable as simple and cost-effective spring elements. This also results in simple and cost-effective assembly. In particular, the spring element can already be pre-assembled on the pedestrian protection crossbeam or the support element, so that it only needs to be connected to the other element at a final assembly line in a motor vehicle manufacturing plant, for example by riveting, screwing, or welding.

[0018] In a particularly simple embodiment, at least one elastic bending element, preferably plate-shaped, is provided as a spring element, extending predominantly in the vehicle's vertical and transverse directions. The bending element can, in particular, be a sheet metal strip, especially made of sheet steel. Preferably, the bending element is a simply shaped sheet (e.g., with a rectangular base) with a thickness between 2 mm and 5 mm. Such a plate-shaped elastic bending element is, in particular, arranged such that it can bend elastically around a bending axis extending in the vehicle's vertical and / or transverse direction in order to absorb potential energy.

[0019] The at least one spring element can be arranged directly adjacent to the support element and / or the pedestrian protection crossbeam. In particular, the spring element can be arranged on the front, rear, or end face of the pedestrian protection crossbeam and / or the support element. A direct connection linking the pedestrian protection crossbeam to the support element requires little installation space, is lightweight, and is therefore cost-effective to implement.

[0020] Alternatively or in addition to a bending element, at least one expansion and / or compression element, which is variable in length, particularly in the longitudinal direction of the vehicle, can be provided as a spring element and is arranged between the pedestrian protection crossbeam and the support element. In particular, coil springs, helical springs, or gas springs can be used as expansion and / or compression elements, which are elastically expanded and / or compressed when subjected to a force from a pedestrian impact. As already mentioned, such spring elements are particularly suitable for embodiments in which the spring element extends predominantly over a gap between the pedestrian protection crossbeam and the support element in the longitudinal direction of the vehicle, with the effective axis of the spring preferably also being oriented predominantly or exclusively in the longitudinal direction of the vehicle.Spiral springs and helical springs are generally very cost-effective and allow for an almost lossless conversion of potential and kinetic energy in the elastic deformation range.

[0021] To account for any elasticity that may vary in the transverse direction of the vehicle, particularly in the area of ​​an upper load plane with a bumper main crossmember, and to use this knowledge for optimizing a corresponding pedestrian protection crossmember in a lower load plane, it is preferred if the pedestrian protection crossmember comprises at least two segments that are at least partially decoupled from each other with respect to their longitudinal displacement. The elasticities in the upper load plane may differ, for example, due to the arrangement of a manufacturer's logo, headlight housing, or other structural elements that extend only over a portion of the vehicle's width in front of the bumper main crossmember.Preferably, the pedestrian protection crossbeam is divided into a large number of segments, in particular into as many segments as there are different elasticity zones in the area of ​​an upper load plane.

[0022] At least one spring element can be provided per segment and / or per connection point between two segments. With one spring element per segment, the segments are completely decoupled from each other, and only those segments subjected to forces – for example, in a pedestrian collision – at least partially in the longitudinal direction of the vehicle can actually shift relative to the support element. With at least partial coupling of the individual spring elements, adjacent segments of the pedestrian protection crossbeam also shift relative to the support element. This results in a wave-like propagation of the force from the point of impact outwards, and the intensity of the coupling can be designed as needed.

[0023] In another practical embodiment, the pedestrian protection crossbeam is arranged at a height of 100 mm to 400 mm of the vehicle, measured in the vertical direction, and preferably at a height of 150 mm to 300 mm. Tests have shown that, with the pedestrian protection crossbeam arranged according to the invention at this height, a suitable force is transmitted to the lower leg of a pedestrian to counteract hyperextension of the knee.

[0024] A maximum spring travel of up to 40 mm has proven preferred for the spring element (or elements), with a travel between 10 mm and 30 mm being particularly preferred. In this case, the pedestrian protection crossmember only shifts relative to the support element by a maximum of this spring travel and then releases the absorbed potential energy. A longer spring travel is increasingly associated with the risk that a pedestrian's lower leg could move too far backward in the longitudinal direction of the vehicle, resulting in excessive hyperextension of the knee.

[0025] Further practical embodiments of the invention are described below in connection with the drawings. They show: Fig. 1. A motor vehicle in a side view, Fig. 2 a first embodiment of an arrangement according to the invention in a perspective view from an oblique front view, Fig. 3 the section of the arrangement marked III Fig. 2 in a perspective view from the side, Fig. 4 a second embodiment of an arrangement according to the invention in a top view, Fig. 5 a third embodiment of an arrangement according to the invention in a top view, Fig. 6 a fourth embodiment of an arrangement according to the invention in a top view, and Fig. 7 a fifth embodiment of an arrangement according to the invention in a top view

[0026] In Fig. Figure 1 shows a motor vehicle 10 in a side view. The invention relates to an arrangement that is located in the front area of ​​the front section 12 of the motor vehicle 10, shown in dashed lines, in particular directly behind the body panels of the motor vehicle 10, especially behind a bumper cover and / or behind radiator grilles.

[0027] In the Fig. 2 and Fig. Figure 3 shows a first embodiment of an arrangement according to the invention, wherein in these illustrations the motor vehicle 10 is shown without the body panels forming the outer skin. Two cross members extending over a large part of the width of the motor vehicle are visible, in the form of an upper bumper main cross member 14 and a pedestrian protection cross member 20 arranged in the vehicle's vertical direction (z-direction) below the bumper main cross member 14.

[0028] Crash boxes 16 extending rearward in the longitudinal direction (x-direction) of the vehicle are arranged on the main bumper crossmember 14. A bulkhead plate 18 is attached to the rear of each crash box 16. Longitudinal members (not shown) are attached to the rear of the bulkhead plates 18.

[0029] In the embodiment shown, the pedestrian protection crossbeam 20 (measured to the center line) is arranged at a height H of 250 mm above the contact surface, extending in the vehicle's vertical direction (z-direction) (see figure). Fig. 1).

[0030] The pedestrian protection crossbeam 20 is in the Fig. 2 and Fig. In the embodiment shown in Figure 3, the pedestrian protection crossmember 20 is fixed to a support element 24 via two spring elements 22. The support element 24 is arranged behind the pedestrian protection crossmember 20 in the longitudinal direction (x-direction) of the vehicle and is fixed directly or indirectly to the body shell of the vehicle 10 (not shown). For fixing it to the body shell, two support elements 34 extending rearward along the support element 24 in the longitudinal direction (x-direction) of the vehicle can be used. Alternatively, the support element 24 can also have a different geometry and / or be attached to the vehicle 10 in a different manner.

[0031] As from the Fig. 2 and Fig. As can be seen in Figure 3, the spring elements 22 extend from both lateral ends of the pedestrian protection crossbeam 20 in an arc shape to the support element 24, both in the transverse direction (y-direction) and in the longitudinal direction (x-direction) of the vehicle. The spring elements 22 are designed as two plate-like, elastic bending elements 26 in the form of simple sheet metal strips. In the embodiment shown, steel sheets approximately 3 mm thick were used.

[0032] When a force acts on the pedestrian protection crossbeam 20 from the front in the longitudinal direction (x-direction) of the vehicle, such as occurs when a pedestrian's lower leg makes contact, the pedestrian protection crossbeam 20 is displaced relative to the support element 24 in the longitudinal direction (x-direction) of the vehicle. The bending element 26 is thereby subjected to spring-elastic bending stress and stores the energy primarily in the form of potential energy (spring energy). In the illustrated embodiment, the bending element 26 bends essentially around the vertical direction (z-direction) of the vehicle. When the force is reduced, for example, immediately after the impact of a lower leg, the elastic bending element 26 relaxes and springs back, releasing the potential energy.This allows for controlled and targeted acceleration of a pedestrian's lower leg forward in the longitudinal direction (x-direction) of the vehicle, in order to reduce the risk of injury in the event of a pedestrian collision, in particular by counteracting impending hyperextension with the help of acceleration from the spring energy. The bending element 22 is located in the [unclear - possibly a reference to a specific part or section]. Fig. 2 and Fig. 3 the embodiment shown is designed such that a spring travel s, i.e. a maximum relative displacement of the pedestrian protection crossbeam 20 relative to the support element 22 in the longitudinal direction of the vehicle (x-direction) of 25 mm results.

[0033] The following describes further embodiments in connection with the Fig. 4 to 7 use the same reference numerals for identical or at least functionally equivalent elements as for the description of the first embodiment.

[0034] In Fig. Figure 4 shows a second embodiment of an arrangement according to the invention, wherein in this figure only the pedestrian protection crossbeam 20 and the support element 24 are shown in a top view. In this embodiment as well, the pedestrian protection crossbeam 20 is located below a Fig. 4 bumper main crossmembers not shown.

[0035] As can be seen, in this embodiment the pedestrian protection crossbeam 20 has a greater width extending in the transverse direction (y-direction) of the vehicle than the support element 24. Bending elements 26 are provided as spring elements 22, extending outwards in the transverse direction (y-direction) of the vehicle and in an arc-shaped manner to the rearwards in the longitudinal direction (x-direction) of the vehicle from the lateral ends of the support element 24, and are attached to the rear of the pedestrian protection crossbeam 20.

[0036] In this embodiment as well, the bending element 26 is subjected to spring-elastic bending upon impact by a pedestrian, due to a displacement of the pedestrian protection crossbeam 20 relative to the support element 24. In this embodiment, a maximum spring travel s of 30 mm is provided. In this embodiment as well, energy is temporarily stored as spring energy by the spring elements 22 and – as soon as possible – released again in the form of kinetic energy, in particular to the impacting lower leg of a pedestrian.

[0037] In connection with the Fig. In embodiments 5 to 7 shown, only the pedestrian protection cross member 20, the support element 24 and spring elements 22 are shown, but not a bumper main cross member that is also present and arranged above it in the vehicle's vertical direction.

[0038] In connection with the Fig. In the embodiments shown in Figures 5 to 7, compression elements 28 in the form of coil springs are arranged as spring elements 22 in the longitudinal direction (x-direction) of the vehicle between the support element 24 and the pedestrian protection cross member 20.

[0039] The pedestrian protection crossbeam 20 is located in the Fig. In the third embodiment shown in Figure 5, the pedestrian protection crossbeam 20 is fixed to the support element 24 via two compression elements 28. The pedestrian protection crossbeam 20 is formed in one piece.

[0040] It should be noted here that, alternatively, more or fewer spring elements 22 can be arranged distributed across the width of the pedestrian protection crossbeam 20, which extends transversely across the vehicle. Furthermore, other types of compression elements 28, such as spiral springs or gas springs, can be used instead of coil springs.

[0041] When a pedestrian impacts the pedestrian protection crossbeam 20, the pedestrian protection crossbeam 20 is moved towards the support element 14 by spring action. The compression elements 28 are compressed to a maximum extent over a spring travel s, here with a length s of 35 mm, until they reach their block length in the case of the coil springs shown, thereby storing potential energy and releasing it again as kinetic energy as the impact force decreases.

[0042] During the Fig. 6 and Fig. In the fourth and fifth embodiments shown in Figure 7, the pedestrian protection crossbeam 20 is each divided into a plurality of segments 30. The segments 30 are at least partially decoupled from one another, i.e., each segment 30 can move – depending on any coupling means (not shown) – independently of an adjacent segment 30 in the longitudinal direction (x-direction) of the vehicle towards the support element 24. Each segment 30 can be fixed to the support element 24 by at least one separate spring element 22 (see Figure 7). Fig. 6), or at least one spring element 22 can be arranged at a connection point 32 between two segments 30 (see Fig. 7).

[0043] In the Fig. In the fourth embodiment shown in Figure 6, the individual segments 30 can move independently of one another relative to the support element 24 in the longitudinal direction (x-direction) of the vehicle. Alternatively or additionally, different spring travels s can be set as required by preset different spring constants of the spring elements 22 and / or by using springs of different lengths, for example to accommodate different elasticities in the area of ​​an outer skin arranged in front of the pedestrian protection crossbeam 20.

[0044] In the Fig.In the fifth embodiment of an arrangement according to the invention, shown in Figure 7, two segments 30 are coupled to each other via a spring element 22. When a force is exerted on a segment 30 in the longitudinal direction (x-direction) of the vehicle towards the rear, the segment 30 directly subjected to the force is deflected most strongly in the longitudinal direction (x-direction) of the vehicle. At the same time, at least the two adjacent segments 30 are also deflected rearward in a wave-like manner in the longitudinal direction (x-direction) of the vehicle due to the coupling via the spring elements 22.

[0045] It is noted that a combination of different spring elements 22 can also be arranged in any number and position across the width of a pedestrian protection crossbeam 20 extending in the transverse direction (y-direction) of the vehicle. Furthermore, in addition to or instead of coupling via spring elements 22, two adjacent segments 30 can also be coupled by means of additional coupling elements such that forces acting on one segment 30 are partially or largely transmitted to adjacent segments 30, so that the segments 30 interact with each other. Reference symbol list 10 motor vehicle 12 Front section 14 Bumper main crossmember 16 Crashbox 18 bulkhead plate 20 pedestrian protection crossbeams 22 Spring element 24 support element 26 Bending element 28 compression element 30 segment 32 liaison point 34 Support element

Claims

[1] Arrangement of a pedestrian protection cross member (20) in a front section (12) of a motor vehicle (10), wherein the pedestrian protection cross member (20) is arranged below a bumper main cross member (14) and behind the outer skin panels of the motor vehicle (10) when viewed in the vertical direction of the vehicle, characterized by , that the pedestrian protection crossbeam (20) is fixed to a support element (24) of the motor vehicle (10) via at least one spring element (22) in such a way that the pedestrian protection crossbeam (20) is displaceable in the longitudinal direction of the vehicle and the arrangement enables a reversible relative movement between the pedestrian protection crossbeam (20) and the support element (24) in the longitudinal direction of the vehicle. [2] Arrangement according to the foregoing claim, characterized by , that the at least one spring element (22) is arranged between the support element (24) and the pedestrian protection cross member (20) when viewed in the longitudinal direction of the vehicle. [3] Arrangement according to any of the foregoing claims, characterized by , that the at least one spring element (22) is arranged or designed to project outwards in the transverse direction of the vehicle over a lateral end of the pedestrian protection crossbeam (20) and / or over a lateral end of the support element (24) in the transverse direction of the vehicle. [4] Arrangement according to any of the foregoing claims, characterized by , that at least one elastic bending element (26) is provided as a spring element (22), which extends predominantly in the vertical direction of the vehicle and in the transverse direction of the vehicle. [5] Arrangement according to any of the foregoing claims, characterized by , that the at least one spring element (22) is arranged directly adjacent to a support element (24) and / or a pedestrian protection crossbeam (20). [6] Arrangement according to any of the foregoing claims, characterized by, that at least one expansion and / or compression element (28) is provided as a spring element (22) between the pedestrian protection crossbeam (20) and the support element (24). [7] Arrangement according to any of the foregoing claims, characterized by , that the pedestrian protection crossbeam (20) comprises at least two segments (30) that are at least partially decoupled from each other with respect to their displacement in the longitudinal direction of the motor vehicle (10). [8] Arrangement according to the foregoing claim, characterized by , that at least one spring element (22) is provided per segment (30) and / or per connection point (32) between two segments (30). [9] Arrangement according to any of the foregoing claims, characterized by , that the pedestrian protection crossbeam (20) is arranged at a height of 100 mm to 400 mm of the motor vehicle (10) as measured in the vehicle's vertical direction. [10] Arrangement according to any of the preceding claims, characterized by, that the spring element (22) is designed for a maximum spring travel s of up to 40 mm.

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