DE102016209926A1 - Arrangement of a pedestrian protection cross member in a front end of a motor vehicle - Google Patents

Abstract

The invention relates to an arrangement of a pedestrian protection crossmember (20) in a front end (12) of a motor vehicle (10), the pedestrian protection crossmember (20) being arranged below a bumper main crossbeam (14) viewed in the vertical direction of the vehicle. Cross member (20) via at least one spring element (22) on a support element (24) of the motor vehicle (10) is fixed, that the pedestrian protection cross member (20) is displaceable in the vehicle longitudinal direction.

Description

The invention relates to an arrangement of a pedestrian protection crossmember in a front end of a motor vehicle according to the preamble of claim 1.

Out DE 2011 119 542 A1 an arrangement of a pedestrian protection cross member is known, which is viewed in the vehicle vertical direction below a bumper main cross member in a front end of a motor vehicle. The pedestrian protection cross member is rigidly connected to the main bumper cross member extending predominantly in the vertical direction of the vehicle vertical struts. A disadvantage of this arrangement is that in the event of a force acting on the pedestrian protection cross member via the vertical struts to an undesirable shear and torque load of the bumper main cross member may occur. Furthermore, only certain relative arrangements of pedestrian protection cross members and bumper main cross members are permitted for reasons of pedestrian protection.

The invention has for its object to provide an arrangement of a pedestrian protection cross member in a front end of a motor vehicle available, which is functionally improved. In particular, it should avoid unwanted shear and moment loads of the bumper main cross member, increases the design freedom and pedestrian protection can be improved.

The object is achieved according to the invention by the features of claim 1. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

In an inventive arrangement of a - usually over a majority of the width of a motor vehicle extending - pedestrian protection crossmember in a front end of a motor vehicle, the pedestrian protection cross member is viewed in the vertical direction of the vehicle below the bumper main cross member. In this case, the pedestrian protection cross member is determined via at least one spring element on a support element of the motor vehicle such that the pedestrian protection cross member is displaceable in the vehicle longitudinal direction. With displaceable here is a reversible, elastic displacement meant, in which potential energy is absorbed by the spring element and then released again.

In the present case, a carrier element is understood to be any element which is defined directly or indirectly on the body shell of the motor vehicle. These include in particular arranged in the vehicle longitudinal direction behind the pedestrian protection cross member elements such. Subcarrier made of plastic or steel.

In the present case, a front end of a motor vehicle is understood to be the region of a motor vehicle which extends from the front of the vehicle to an interior of the motor vehicle, the arrangement according to the invention being arranged in the region of the vehicle front, in particular in the vehicle longitudinal direction, from the vehicle outer skin front to a mounting support for a cooler module. Under a bumper main cross member usually designed with the greatest bending stiffness cross member in the front of the front of a motor vehicle is understood, which is usually connected via so-called crash boxes (also called deformation elements) to two lateral main longitudinal members of the motor vehicle.

The arrangement according to the invention enables a reversible relative movement between pedestrian protection cross member and carrier element in the vehicle longitudinal direction. As a result, in the case of a pedestrian impact - especially in the leg area of a pedestrian - occurring forces can be absorbed via a spring travel path, converted into potential energy and "returned" to the pedestrian. This can be advantageously used for pedestrian protection, which will be explained in more detail below. In a collision of a pedestrian on the front of a motor vehicle usually meets the knee on an upper load level at the height of the bumper main cross member and the thigh in the front flap, while the lower leg meets a lower load level at the height of the pedestrian protection cross member. The pedestrian protection cross member is intended in particular to ensure that there is no overstretching in the area of the knee of an impacting pedestrian. For this purpose, an early return movement of the lower leg must be sought. By an inventive arrangement, the lower leg can be accelerated in the return movement of the lower load level. This effect can be used to improve the pedestrian protection and to reduce a possibly borderline hyperextension in the knee by accelerating the lower leg and / or to benefit from increased design freedom by the pedestrian protection cross member in the vehicle longitudinal direction relative to the bumper main cross member further back can be arranged.

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 to any other carrier element can be made, in particular on a support element which is arranged approximately at the same height as the pedestrian protection cross member so that, if possible, a purely translational displacement of the pedestrian protection cross member without design-related twisting takes place during the elastic displacement and thus no shear and moment loads occur on the bumper main cross member.

For arrangements according to the invention, in particular spring elements are suitable in which during the conversion of kinetic energy into potential energy and back into kinetic energy only small losses occur and, accordingly, the resulting efficiency is high. Preference is given to spring elements with an efficiency of at least 80%, particularly preferably at least 90% and more preferably at least 95%. Accordingly, damping elements or predominantly plastically deforming elements, in which kinetic energy is used to a greater extent for a plastic deformation of the element, no spring elements in the context of the invention. Spring elements in the context of the invention are in particular coil springs, designed as a bending spring spring elements and other springs in the technical sense.

In a practical embodiment of the arrangement according to the invention, the at least one spring element viewed in the vehicle longitudinal direction is arranged between the carrier element and the pedestrian protection cross member. It thus bridges in particular a free space between the support element and the pedestrian protection cross member. A spring-elastic displacement of the pedestrian protection crossmember in the direction of a vehicle longitudinal direction behind it, arranged on the shell side supporting element is in this case particularly easy to realize by means of springs, for example by means of coil springs.

By a relative movement between pedestrian protection cross member and support member, the spring element is elastically deformed, e.g. bent, stretched or compressed and absorbs potential energy. The spring element then gives off a large part of this energy again in the short term in order to at least partially reverse the relative movement.

Regardless of which type of spring element is used, it may be preferable to arrange a plurality of spring elements distributed over the width of the pedestrian protection cross member in order to achieve a uniform as possible restoring force across the width.

In a further embodiment of the arrangement according to the invention, which can be carried out in a cost-effective manner, the spring element is arranged or formed cantilevered outward over at least one lateral end of the pedestrian protection cross member and / or via at least one lateral end of the carrier element in the vehicle transverse direction. In this case, the spring element is preferably at least partially formed as a spiral spring and bridges a space between one end of the pedestrian protection cross member and the support member and / or between one end of the support member and the pedestrian protection cross member. This embodiment is particularly suitable for pedestrian protection cross members, which are attached to a majority of the width extending support elements, which may be arranged in the vehicle longitudinal direction in front of or behind the pedestrian protection cross member. In connection with this embodiment, in particular flexurally elastic sheet steel strips are suitable as simple and inexpensive spring elements. In this case, there is also a simple and inexpensive installation. In particular, the spring element may already be preassembled on the pedestrian protection cross member or the carrier element, so that it only has to be connected to the respective other element at an end assembly line of a motor vehicle production, for example by riveting, screwing or welding.

In a particularly simple embodiment, at least one, in particular plate-like design, elastic bending element is provided as the spring element, which extends predominantly in the vehicle vertical direction and vehicle transverse direction. The bending element may in particular be a sheet-metal strip, in particular of sheet steel. Preferably, the flexure is a simple shaped sheet (e.g., of rectangular shape) having a thickness of between 2mm and 5mm. Such a plate-like elastic bending element is in particular arranged such that it can bend elastically around a bending axis extending in the vehicle vertical direction and / or in the vehicle transverse direction in order to absorb potential energy.

The at least one spring element can be arranged directly adjacent to the carrier element and / or the pedestrian protection cross member. In particular, the spring element can be arranged on the front side, on the rear side or on the front side on the pedestrian protection cross member and / or on the carrier element. An immediate connection, which connects the pedestrian protection cross member with the support element, takes up little space, has a low weight and is therefore inexpensive to implement.

Alternatively or in addition to a bending element can be provided as a spring element at least one variable in length in the vehicle longitudinal direction stretching and / or compression element, which is arranged between the pedestrian protection cross member and the support member. As expansion and / or compression elements in particular coil springs, coil springs or gas springs can be used, which are stretched and / or compressed elastically when a force is applied by a pedestrian impact. As already mentioned, such spring elements are particularly suitable for embodiments in which the spring element extends predominantly over a clearance between pedestrian protection cross member and carrier element in the vehicle longitudinal direction, wherein the axis of action of the spring in this case preferably also predominantly or exclusively oriented in the vehicle longitudinal direction. Coil springs and coil springs are usually very inexpensive and allow in the elastic deformation range a nearly lossless conversion of potential and kinetic energy.

In order to take account of any elasticity varying in the vehicle transverse direction, in particular in the region of an upper load plane with a bumper main crossbeam, and to use this knowledge for optimizing a corresponding pedestrian protection crossbeam in a lower load plane, it is preferred if the pedestrian protection Cross member at least two at least in terms of their displaceability in the longitudinal direction of the motor vehicle partially decoupled segments comprises. The elasticities in the upper load level, for example, due to the arrangement of a manufacturer logo, headlamp housing or other structural elements that extend only over part of the width of the motor vehicle in front of the bumper main cross member may be different. Preferably, the pedestrian protection cross member is divided into a plurality of segments, in particular in as many segments as different elasticity ranges are present in the region of an upper load level.

In this case, at least one spring element may be provided per segment and / or per connection point between two segments. In a spring element per segment, the segments are completely decoupled from each other and it can actually move those segments relative to the support element, which forces - for example, in a pedestrian impact - act at least partially in the vehicle longitudinal direction. With an at least partial coupling of the individual spring elements, adjacent segments of the pedestrian protection cross member also shift relative to the carrier element. There is a wave-like propagation of the force from the impact to the outside, the intensity of the coupling can be interpreted as needed.

In a further practical embodiment of the pedestrian protection cross member is arranged in a height measured in the vehicle vertical direction of 100 mm to 400 mm of the motor vehicle, more preferably in a height of 150 mm to 300 mm. By means of experiments it has been found that in an arrangement according to the invention of the pedestrian protection cross member at this height, a suitable force transmission to the lower leg of a pedestrian takes place in order to counteract hyperextension of the knee.

As a preferred maximum travel for the spring element (or the spring elements used), a travel has been found to 40 mm, more preferably between 10 mm and 30 mm. The pedestrian protection cross member shifts in this case only a maximum of this travel relative to the support element and then returns the absorbed potential energy. A longer travel is increasingly associated with the risk that the lower leg of a pedestrian could move too far in the vehicle longitudinal direction to the rear and has an excessive hyperextension of the knee result.

Further practical embodiments of the invention are described below in conjunction with the drawings. Show it:

1 a motor vehicle in a side view,

2 a first embodiment of an inventive arrangement in a perspective view obliquely from the front,

3 the marked with III section of the arrangement 2 in a perspective view from the side,

4 A second embodiment of an arrangement according to the invention in a view from above,

5 A third embodiment of an arrangement according to the invention in a view from above,

6 a fourth embodiment of an inventive arrangement in a view from above, and

7 a fifth embodiment of an inventive arrangement in a view from above

In 1 is a motor vehicle 10 shown in a side view. The invention relates to an arrangement in the front region of the front carriage shown in dashed lines 12 of the motor vehicle 10 is arranged, in particular immediately behind the outer skin forming trim parts of the motor vehicle 10 , in particular behind a bumper cover and / or behind radiator grille.

In the 2 and 3 a first embodiment of an arrangement according to the invention is shown, wherein in these representations the motor vehicle 10 is shown without the outer skin forming trim parts. Evident are two over a majority of the width of the motor vehicle extending cross member in the form of an upper bumper main cross member 14 and one in the vehicle vertical direction (z-direction) below the bumper main cross member 14 arranged pedestrian protection cross member 20 ,

At the bumper main cross member 14 are in the vehicle longitudinal direction (x-direction) extending rear crash boxes 16 arranged. On the back of the crash boxes 16 each closes a bulkhead 18 at. On the back of the tartan plates 18 close to side members (not shown).

In the embodiment shown, the pedestrian protection cross member 20 (measured to the center line) in a vehicle height direction (z-direction) extending height H of 250 mm above the footprint arranged (see. 1 ).

The pedestrian protection cross member 20 is in the in the 2 and 3 shown embodiment via two spring elements 22 on a support element 24 established. In this case, the support element 24 in the vehicle longitudinal direction (x-direction) behind the pedestrian protection cross member 20 arranged and directly or indirectly on the shell of the motor vehicle 10 (not shown). In particular, two can be attached to the support element for fixing to the shell 24 in the vehicle longitudinal direction (x-direction) to the rear extending support elements 34 be used. The carrier element 24 but may alternatively have a different geometry and / or different on the motor vehicle 10 be attached.

Like from the 2 and 3 it can be seen, the spring elements extend 22 each from the two lateral ends of the pedestrian protection cross member 20 both in the vehicle transverse direction (y-direction) and in the vehicle longitudinal direction (x-direction) arcuate to the support element 24 , The spring elements 22 are as two plate-like, elastic bending elements 26 formed in the form of simple metal strips. In the embodiment shown approximately 3 mm thick steel sheets were used.

When a force in the vehicle's longitudinal direction (x-direction) is exerted on the pedestrian protection cross member from the front 20 as it occurs, for example, when in contact with a lower leg of a pedestrian, the pedestrian protection cross member 20 relative to the carrier element 24 shifted in vehicle longitudinal direction (x-direction). The bending element 26 It is resiliently stressed to bending and stores the energy mainly in the form of potential energy (spring energy). In this case, in the embodiment shown, a bending of the bending element 26 essentially to the vehicle vertical direction (z-direction) instead. With a reduction of the force, for example, immediately after the impact of a lower leg, the elastic flexure relaxes 26 again and springs back by releasing the potential energy again. This allows a controlled and targeted acceleration of the lower leg of a pedestrian in the vehicle longitudinal direction (x-direction) made to the front to reduce the risk of injury in the event of a pedestrian impact, in particular by counteracting a threat of hyperextension by means of the acceleration by the spring energy. The bending element 22 is in the in the 2 and 3 shown embodiment designed so that a spring travel s, ie a maximum relative displacement of the pedestrian protection cross member 20 opposite the carrier element 22 in the vehicle longitudinal direction (x-direction) of 25 mm results.

In the following, for describing further embodiments in connection with the 4 to 7 for identical or at least functionally identical elements the same reference numerals used as for the description of the first embodiment.

In 4 a second embodiment of an arrangement according to the invention is shown, wherein in this figure, only the pedestrian protection cross member 20 and the carrier element 24 are shown in a view from above. Also in this embodiment, the pedestrian protection cross member 20 below an in 4 not shown bumper main cross member arranged.

As can be seen, the pedestrian protection cross member points 20 in this embodiment, a larger, in the vehicle transverse direction (y-direction) extending width, as the carrier element 24 , As spring elements 22 are from the lateral ends of the support element 24 in the vehicle transverse direction (y-direction) to the outside and in the vehicle longitudinal direction (x-direction) arcuately extending rearwardly bending elements 26 provided that on the back of the pedestrian protection cross member 20 are attached.

Also in this embodiment, the bending element 26 in the event of a pedestrian impact due to a displacement of the pedestrian protection cross member 20 relatively in the direction of the carrier element 24 too, resiliently stressed on bending. In this embodiment, a maximum spring deflection s of 30 mm is provided in this embodiment. Also in this embodiment is of the spring elements 22 temporarily stored energy as spring energy and - as soon as possible - returned back in the form of kinetic energy, in particular to an impacting lower leg of a pedestrian.

In conjunction with the 5 to 7 shown embodiments are again only the pedestrian protection cross member 20 , the carrier element 24 and spring elements 22 shown, but not a likewise existing, arranged in the vehicle vertical direction above the bumper main cross member.

In conjunction with the 5 to 7 embodiments shown are as spring elements 22 in the vehicle longitudinal direction (x-direction) between the carrier element 24 and the pedestrian protection cross member 20 arranged compression elements 28 arranged in the form of coil springs.

Here is the pedestrian protection cross member 20 in the in 5 illustrated third embodiment via two compression elements 28 on the carrier element 24 established. The pedestrian protection cross member 20 is integrally formed.

It is noted at this point that over the vehicle transverse direction extending width of the pedestrian protection cross member 20 alternatively also distributes more or less spring elements 22 can be arranged. Further, instead of helical springs, other types of compression elements may also be used 28 used, for example, coil springs or gas springs.

In the event of a pedestrian impacting the pedestrian protection cross member 20 becomes the pedestrian protection cross member 20 elastic on the carrier element 14 too moved. The compression elements 28 are maximum over a spring travel s, here with a length s of 35 mm, compressed until they reach their block length in the coil springs shown, store potential energy and return this largely as the impact force decreases in the form of kinetic energy.

In the in the 6 and 7 shown fourth and fifth embodiment is the pedestrian protection cross member 20 each in a variety of segments 30 divided. Here are the segments 30 at least partially decoupled from each other, ie each segment 30 can - depending on any coupling means (not shown) - independent of an adjacent segment 30 in the vehicle longitudinal direction (x-direction) on the support element 24 to move. Either one segment can be used 30 via at least one separate spring element 22 on the carrier element 24 be determined (cf. 6 ), or it can at least one spring element 22 at a junction 32 between two segments 30 be arranged (cf. 7 ).

In the in 6 shown fourth embodiment, the individual segments 30 independently relative to the carrier element 24 in the vehicle's longitudinal direction (x-direction). Alternatively or in addition, by preset different spring constants of the spring elements 22 and / or by different lengths of springs, if necessary, different suspension travel s are set, for example, different elasticities in the area before the pedestrian protection cross member 20 arranged outer skin to take into account.

In the in 7 illustrated fifth embodiment of an inventive arrangement are each two segments 30 via a spring element 22 coupled together. When on a segment 30 a force in the vehicle longitudinal direction (x-direction) is applied to the rear, the force applied directly to the segment 30 most in the vehicle longitudinal direction (x-direction) designed to the rear. At the same time but also at least the two adjacent segments 30 due to the coupling via the spring elements 22 Waveform also in the vehicle longitudinal direction (x-direction) deflected backwards.

It should be noted that also a combination of different spring elements 22 in any number and position on the width of a pedestrian protection cross member extending in the vehicle transverse direction (y direction) 20 can be arranged distributed. Furthermore, in addition to or instead of a coupling via spring elements 22 two adjacent segments 30 be coupled by means of additional coupling elements such that affect a segment 30 acting forces partially or largely also on adjacent segments 30 be transferred so that the segments 30 interact with each other.

LIST OF REFERENCE NUMBERS

10

motor vehicle

12

front end

14

Bumper bolster

16

crash box

18

Schott plate

20

Pedestrian protection cross member

22

spring element

24

support element

26

flexure

28

upsetting element

30

segment

32

junction

34

support element

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2011119542 A1 [0002]

Claims (10)

Arrangement of a pedestrian protection crossmember ( 20 ) in a front end ( 12 ) of a motor vehicle ( 10 ), the pedestrian protection cross member ( 20 ) viewed in the vehicle vertical direction below a bumper main cross member ( 14 ), characterized in that the pedestrian protection cross member ( 20 ) via at least one spring element ( 22 ) on a support element ( 24 ) of the motor vehicle ( 10 ), that the pedestrian protection cross member ( 20 ) is displaceable in the vehicle longitudinal direction. Arrangement according to the preceding claim, characterized in that the at least one spring element ( 22 ) viewed in the vehicle longitudinal direction between the carrier element ( 24 ) and the pedestrian protection cross member ( 20 ) is arranged. Arrangement according to one of the preceding claims, characterized in that the at least one spring element ( 22 ) via a lateral end of the pedestrian protection crossmember ( 20 ) in the vehicle transverse direction and / or via a lateral end of the carrier element ( 24 ) is arranged or formed projecting outward in the vehicle transverse direction. Arrangement according to one of the preceding claims, characterized in that as a spring element ( 22 ) at least one elastic bending element ( 26 ) is provided, which extends predominantly in the vehicle vertical direction and in the vehicle transverse direction. Arrangement according to one of the preceding claims, characterized in that the at least one spring element ( 22 ) directly adjacent to a carrier element ( 24 ) and / or a pedestrian protection cross member ( 20 ) is arranged. Arrangement according to one of the preceding claims, characterized in that as a spring element ( 22 ) at least one between the pedestrian protection cross member ( 20 ) and the carrier element ( 24 ) arranged expansion and / or compression element ( 28 ) is provided. Arrangement according to one of the preceding claims, characterized in that the pedestrian protection cross member ( 20 ) At least two at least in terms of their displacement in the longitudinal direction of the motor vehicle ( 10 ) partially decoupled segments ( 30 ). Arrangement according to the preceding claim, characterized in that at least one spring element ( 22 ) per segment ( 30 ) and / or each connection point ( 32 ) between two segments ( 30 ) is provided. Arrangement according to one of the preceding claims, characterized in that the pedestrian protection cross member ( 20 ) in a height measured in the vehicle vertical direction of 100 mm to 400 mm of the motor vehicle ( 10 ) is arranged. Arrangement according to one of the preceding claims, characterized in that the spring element ( 22 ) is designed for a maximum travel s of up to 40 mm.

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