WO2008107587A1

WO2008107587A1 - Motor vehicle pedestrian impact absorber

Info

Publication number: WO2008107587A1
Application number: PCT/FR2008/050054
Authority: WO
Inventors: Laurent Rocheblave; Arnold Fayt; Laurent Martin
Original assignee: Compagnie Plastic Omnium
Priority date: 2007-01-12
Filing date: 2008-01-11
Publication date: 2008-09-12
Also published as: CN101646584A; EP2111351A1; FR2911312A1; JP2010515619A; FR2911312B1

Abstract

The invention relates to a pedestrian impact absorber (10) for a motor vehicle, capable of deforming under the action of a load corresponding to impact with a pedestrian, of the type comprising: an upper part (16) to which the load corresponding to the pedestrian impact is liable to be applied, a lower part (18) liable to bear against a rigid structure of the motor vehicle during the pedestrian impact, an intermediate part (20) liable to deform under the action of the load corresponding to the pedestrian impact in such a way that the upper part moves closer to the lower part. In this absorber: at least one of the upper and lower parts comprises a rigid region (22) designed to be non-deformable under the action of the load corresponding to the pedestrian impact, the intermediate part comprises a region (24) of weakness designed to collapse under the action of the load corresponding to the pedestrian impact.

Description

Pedestrian shock absorber for a motor vehicle.

The present invention relates to a shock-pedestrian absorber for a motor vehicle. In the interest of protecting a pedestrian in the event of a frontal collision of a motor vehicle with this pedestrian, the current motor vehicles usually comprise means for damping the impact of the head or the leg or the femur of the pedestrian against the pedestrian. motor vehicle, for example against the hood.

In some cases, the damping means comprise at least one absorber designed to work in compression so as to dampen the impact of the pedestrian's head or leg to a sufficient height.

Thus, it is already known in the state of the art, particularly according to FR 2 880 320, a shock-pedestrian absorber for a motor vehicle, able to deform under the action of a force corresponding to a pedestrian impact, of the type comprising: - an upper part, on which the force corresponding to the pedestrian impact may be applied, a lower part capable of bearing against a rigid structure of the motor vehicle during the pedestrian impact, an intermediate part, capable of to deform under the action of the force corresponding to the pedestrian impact so that the upper part approaches the lower part.

During an impact, the intermediate portion deforms so as to dampen the impact. For effective protection of the pedestrian, it is usually expected that the absorber breaks in places to allow compression, and thus an optimal absorption height.

However, in some cases, the breakage of the absorber occurs in undesirable areas, the absorber deforming and then breaking in an inappropriate manner, for example asymmetrically forming a hard point, because a height of absorber is not deformed, which introduces a resistance to effort corresponding to the shock, and which can be dangerous for the pedestrian. For example, only the rear part of the absorber deforms, so that its front part, not sinking, can hurt the pedestrian.

The object of the invention is in particular to remedy these drawbacks by providing an absorber capable of deforming in an optimal and repeatable manner, that is to say providing results with variations of less than 20% between these results in tests using pedestrian impact criteria (head HIC, femoral efforts and moments, deceleration, flexion, knee shear).

For this purpose, the subject of the invention is a shock-pedestrian absorber for a motor vehicle, capable of deforming under the action of a force corresponding to a pedestrian impact, of the type comprising: an upper part, on which is susceptible to be applied the force corresponding to the pedestrian impact, a lower part, likely to bear against a rigid structure of the motor vehicle during the pedestrian impact, - an intermediate part, likely to deform under the action of the corresponding effort to the pedestrian impact so that the upper part approaches the lower part, characterized in that: at least one of the upper and lower parts comprises a stiffness zone, shaped so as to be dimensionally stable under the action of the force corresponding to the pedestrian impact, the intermediate portion comprises at least one zone of weakness capable of collapsing under the action of the force corresponding to the pedestrian impact. Thus, by rendering certain parts of the absorber indeformable under the action of the force corresponding to the pedestrian impact, and by making other parts weakened so that they can sag under the action of this effort, ensures that the deformation and / or rupture of the absorber takes place in the desired areas (areas of weakness) and not in undesirable areas. As the lower or upper part is dimensionally stable, it is ensured that its eventual collapse will occur repeatedly or even relatively uniformly.

Moreover, since the lower or upper part is stiffened relative to the intermediate part, it is capable of transmitting the impact forces to the intermediate part as it is (because it does not deform). In other words, the fact of stiffening makes it possible to attract the forces of the shock towards the zone of weakness, guaranteeing more certainly that the deformation of the zone of weakness takes place.

In addition, by arranging symmetrically fragile areas, for example by means of strictions or ridges arranged symmetrically, it is possible to obtain a substantially symmetrical deformation of the absorber.

Thus, thanks to the invention, it is ensured that the deformations and breaks will always take place substantially in the same zones, which ensures a good repeatability of the deformation of an absorber. The collapse of the absorber will therefore take place repeatable from one test to another, since by stiffening the lower or upper part, it is required to deformable intermediate portion to break. It is then possible to predict the behavior of the shock absorber, and to conform this absorber so as to protect pedestrians as well as possible. Indeed, those skilled in the art will be able to choose the most suitable areas of weakness for the absorber to deform so as to optimize the damping of a pedestrian impact.

The invention also has the advantage of offering few incompressible parts, and therefore to allow the collapse of the absorber over a relatively large height in comparison with the total height of this absorber. In other words, the damper can sag until it no longer has a vertical wall. The residual height of the damper after deformation is therefore the lowest possible.

Since the absorber can be compressed over substantially its entire height in the event of a pedestrian impact, the damping of this impact is favored since it is achieved over a relatively large height. An absorber according to the invention may further comprise one or more of the following features.

The upper and lower parts are both undeformable under the action of a force corresponding to the pedestrian impact. This further promotes the deformation of the intermediate portion, since it alone can be deformed during the pedestrian impact.

The stiffness zone comprises at least one form of stiffening, for example a groove or a rib.

The stiffness zone has a wall thicker than the wall thickness of the intermediate portion. - The zone of weakness comprises a material recess or an edge forming a preferred fold zone.

The lower, upper and intermediate parts have walls arranged to form a hollow body. Indeed, it is known that a hollow body crashes more easily when a force is applied to it than a solid body. The absorber is thus formed by a stud.

The upper, lower and intermediate parts are made of different materials, the material forming the weakened zone being the most fragile material.

The absorber is of trapezoidal overall shape, a first portion of which is located at the top and bottom of the trapezium, -AT-

second part of these upper and lower parts forms the base of the trapezium, and the intermediate part forms the flanks of the trapezium. The portion forming the base of the trapezium comprises a support flange. The absorber is of staggered general shape, of which at least one bearing comprises the weakened zone.

The absorber is generally H-shaped whose branches diverge and whose central portion forms the intermediate portion. The absorber is of general S-shape.

The upper part is flanged, the intermediate part is V, diverging towards the upper part and converging towards the lower part, and the lower part is inverted V, converging towards the intermediate part, and adapted so that the branches of the inverted V cooperate with the structure of the motor vehicle. The intermediate portion comprises at least two faces forming between them a certain angle, so as to form a zone of weakness.

The invention also relates to a hood of a motor vehicle, characterized in that it comprises an absorber as defined above.

A hood according to the invention may further comprise one or more of the following features. - The upper or lower part of the absorber is made of material with a lining of the hood. Note that, in the case where the absorber has a trapezoidal shape, the upper part can be indifferently the base or the top of this trapezium.

The absorber is arranged in a peripheral zone of the hood. - The absorber carries a soundproofing device.

Finally, the invention relates to a motor vehicle part, selected from a wing support, an awning, an optical system, and a technical front cross member, characterized in that it comprises an absorber as defined above.

The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which: FIGS. 1 and 2 are perspective views of an absorber, respectively according to a first and a second embodiment of the invention; - Figures 3 to 7 are sectional views of an absorber, respectively according to third to seventh embodiments of the invention. FIG. 1 shows a shock-pedestrian absorber 10, for example a stud, intended to be arranged between a part 12 of a motor vehicle, such as a cover, an optic, a wing or a bumper, and a piece of rigid structure 14 of the vehicle, such as a wing support, a canopy or a front crosshead technical, or any rigid member of the engine.

The absorber 10 comprises an upper part 16, intended to be in contact with the part 12 of a motor vehicle, and a lower part 18, intended to be in contact with the structural part 14. Either of these Upper 16 and lower 18 parts may be integral with, respectively, the workpiece 12 or the workpiece 14.

The upper 16 and lower 18 parts are interconnected by an intermediate portion 20, capable of deforming under the action of a force corresponding to pedestrian impact, so that the upper portion 16 approaches the lower part.

In the event of a pedestrian impact against the part 12, the force corresponding to the pedestrian impact is applied to the upper part 16, while the lower part 18 bears against the rigid structural part 14. The absorber 10 is then deformed by deformation of the intermediate portion 20, under the action of the force corresponding to the pedestrian impact, so as to absorb the energy of the shock.

According to the first embodiment, the upper, lower and intermediate parts comprise walls arranged to form a hollow body. In the example shown, this hollow body is generally trapezoidal. The upper part 16 forms the top of the trapezium, the lower part 18 forms the base of the trapezium, and the intermediate part 20 forms the flanks of the trapezium. However, alternatively, the trapezium could be reversed, that is to say that the upper part would form the base of the trapezium and the lower part the top of this trapezium.

So that the intermediate portion 20 deforms primarily in case of pedestrian impact, at least one of the upper portion 16 and lower 18 has a stiffness zone 22, shaped so as to be dimensionally stable under the action of the force corresponding to the shock pedestrian. In the example shown in FIG. 1, the upper part 16 comprises a form of stiffening 22, such as a groove or a rib, intended to sufficiently stiffen this upper part 16 so as to render it indeformable under the action of the 'effort corresponding to the pedestrian impact.

Furthermore, the intermediate portion 20 comprises a zone of weakness 24, for example weakened by thinning material, able to sag under the action of the force corresponding to the pedestrian impact. So, since the upper part 16 is sufficiently rigid, and that the intermediate portion 20 is weakened, it is easy to provide that the intermediate portion 20 will sag in case of pedestrian impact.

Examples of weakened zones 24 are shown in more detail in FIGS. 2 to 7. In these figures, elements similar to those of the other figures are designated by identical references.

According to the second embodiment, shown in FIG. 2, the zone of weakness 24 comprises an edge of the intermediate portion 20. Such a stop forms a preferred fold zone, allowing the intermediate portion 20 to fold in this zone comprising this stops, thus facilitating the collapse of the absorber 10. As can be seen in this figure 2, as well as on the following, the intermediate portion has several areas of weakness 24, to promote its deformation.

Preferably, the zones of weakness are arranged symmetrically to allow symmetrical deformation of the absorber. According to the third embodiment, shown in Figure 3, the zone of weakness 24 comprises a thinning material.

Note that the thinning material may be arranged symmetrically or not, the art can predict how the absorber deforms depending on the location of these thinning. Furthermore, the portion forming the base of the trapezium (here, the lower part, but it could indifferently be, in a variant, the upper part) is provided with a flange 26 favoring the support on the rigid structural part 14 (alternatively, the piece 12).

Preferably, the absorber 10 comprises, between the walls of the intermediate portion 20, a partition 27 of thin material, intended to improve the stability of the absorber 10 without stiffening it.

According to the fourth embodiment, shown in Figure 4, the absorber 10 has a generally stepped shape.

The upper part 16 forms a base of the absorber, integral with the part 12, for example a hood. The lower portion 18 forms an apex of the absorber, capable of cooperating with the structural part 14 of complementary shape.

The intermediate portion 20 comprises stages 28 comprising the zones of weakness 24, comprising in this example material thinning.

The upper 16 and lower 18 parts have walls of thickness greater than the thickness of the walls of the intermediate portion 20, thus forming the zones of rigidity 22. It will be noted that, in this case, the upper parts 16 and lower 18 are both are indeformable under the action of the force corresponding to the pedestrian impact, to ensure that only the intermediate portion 20 deforms under the action of this effort.

Preferably, at least the lower portion 18 comprises at least one stiffening rib 30. Such a stepped-form absorber is particularly advantageous for allowing the collapse of the absorber 10 over a relatively large height. Of course, alternatively, the absorber 10 could comprise more than one stage 28.

According to the fifth embodiment, shown in Figure 5, the absorber 10 has a general shape H whose branches diverged. In this case, the ends of the branches of the H form the upper parts 16 and lower 18, and the central part of the H forms the intermediate part 20.

In this example shown, the zones of weakness comprise recesses of material 32, forming rupture primers.

Such an H-shaped absorber with diverging branches is particularly advantageous to allow the collapse of the absorber 10 over a relatively large height, since it collapses easily on itself. Moreover, since such an absorber collapses on itself without extending in width, it is possible to arrange several H absorbers side by side, which can each be deformed without being hindered by the deformation of others. According to the fifth embodiment, shown in Figure 6, the absorber 10 has a general S shape promoting its collapse. In this example, the zones of weakness 24 comprise under thicknesses. Such an absorber 10 S is able to collapse on itself without extending in width, as an absorber in H as described above. According to the sixth embodiment, shown in FIG. 7, the upper part 16 is flanged, the intermediate part 20 is in V, diverging towards the upper part 16 and converging towards the lower part 18, and the lower part 18 is in V inverted, converging towards the intermediate portion 20, and adapted so that the branches of the inverted V cooperate with the structural part 14 of the motor vehicle, thus promoting the wedging of the lower portion 18 on the structural part 14. Alternatively, it it is possible to fix the lower part 18 to the structural part 14, for example by snapping.

The zone towards which the intermediate and lower intermediate portions 18 converge forms a flexible node 36, able to keep the upper part 16 relatively parallel to a surface for applying forces in the event of a pedestrian impact, thus ensuring The smooth operation of the absorber 20 in particular with regard to its substantially symmetrical deformation.

Finally, note that the invention is not limited to the embodiments described above. In particular, the different parts and zones of the absorbers can be adapted to the different embodiments.

Claims

1. Absorber (10) shock-pedestrian for a motor vehicle, capable of deforming under the action of a force corresponding to a pedestrian impact, of the type comprising: - an upper part (16), on which is likely to the force corresponding to the pedestrian impact is applied, a lower part (18) capable of bearing against a rigid structure of the motor vehicle during the pedestrian impact, an intermediate part (20) liable to deform under the action of the force corresponding to the pedestrian impact so that the upper part approaches the lower part, characterized in that: at least one of the upper and lower parts comprises a stiffness zone (22), shaped so as to be dimensionally stable under the action of the force corresponding to the pedestrian impact, the intermediate portion comprises a zone of weakness (24), able to sag under the action of the force corresponding to the pedestrian impact.

2. Absorber according to claim 1, wherein the upper and lower parts are both undeformable under the action of the force corresponding to the pedestrian impact.

3. Absorber according to claim 1 or 2, wherein the stiffening zone (22) comprises at least one form of stiffening (30), for example a groove or a rib.

4. Absorber according to claim 1 or 2, wherein the stiffness zone (22) has a wall thicker than the wall thickness of the intermediate portion.

5. Absorber according to any one of the preceding claims, wherein the zone of weakness (24) comprises a recess material (32) or a ridge forming a preferred fold zone.

6. Absorber according to any preceding claim, wherein the lower (18), upper (16) and intermediate (20) comprise walls arranged to form a hollow body.

7. Absorber according to any one of the preceding claims, wherein the upper, lower and intermediate parts are made of different materials, the material forming the weakened zone being the most fragile material.

8. Absorber according to any one of claims 1 to 7, of trapezoidal general shape, a first portion of the upper and lower parts forming the top of the trapezium, a second part of these upper and lower parts forms the base of the trapezium, and the intermediate part forms the flanks of the trapezium.

9. Absorber according to claim 8, wherein the portion forming the base of the trapezoid comprises a support flange.

10. Absorber according to any one of claims 1 to 7, of staggered general shape, at least one bearing (28) comprises the embrittled zone.

1 1. Absorber according to any one of claims 1 to 7, of generally H-shaped whose branches diverge and whose central portion forms the intermediate portion.

12. Absorber according to any one of claims 1 to 7, of general S-shape.

13. Absorber according to any one of claims 1 to 7, including: - the upper part (16) is flanged, the intermediate portion (20) is V, diverging towards the upper part and converging towards the lower part, the lower part (18) is inverted V, converging towards the intermediate part, and adapted so that the branches of the inverted V cooperate with the structure (14) of the motor vehicle.

14. Absorber according to claims 1 to 13, wherein the intermediate portion comprises at least two faces forming between them a certain angle, so as to form a zone of weakness.

Motor vehicle hood, characterized in that it comprises an absorber according to any one of claims 1 to 14.

The hood of claim 15, wherein the upper portion of the absorber is integral with a hood liner.

17. Hood according to claim 15 or 16, wherein the absorber is arranged in a peripheral zone of the hood.

18. Hood according to any one of claims 15 to 17, wherein the absorber carries a soundproofing device.

19. Part of a motor vehicle, selected from a wing support, awning, optics, and a technical front cross member, characterized in that it comprises an absorber according to any one of claims 1 to 14.