Motor vehicle bumper beam comprising a cross-member and a shock absorber

Abstract

According to the invention, both the cross-member and the shock absorber include an upper surface and a lower surface, and the bumper beam has an element for attaching the cross-member to the shock absorber, the attachment element including a strap connecting the lower and/or upper surfaces of the cross-member and the shock absorber.

Claims

1. A bumper beam for motor vehicle comprising a cross-member and at least one shock absorber, both the cross-member and the shock absorber having an upper surface and a lower surface, wherein the bumper beam comprises an attachment element for attaching the cross-member to the shock absorber, the attachment element comprising at least two straps connecting the upper surfaces of the cross-member and the shock absorber and/or the lower surfaces of the cross-member and the shock absorber, the at least two straps being at least partially separated from each other, and distributed in the transverse direction, each encircling the cross-member locally.

2. The bumper beam according to claim 1, wherein at least one of the at least two straps connects the lower surface and the upper surface of the shock absorber, and is in front of the cross-member.

3. The bumper beam according to claim 1, wherein the at least two straps are connected together by bridges, themselves separated from each other.

4. The bumper beam according to claim 1, wherein at least one of the at least two straps is continuous over the width of the shock absorber.

5. The bumper beam according to claim 1, wherein both the cross-member and the shock absorber have a lateral surface, the attachment element further comprising a lateral belt connecting the lateral surfaces of the cross-member and the shock absorber.

6. The bumper beam according to claim 5, wherein the lateral belt forms a lateral flank entirely covering the lateral surfaces of the cross-member and the shock absorber.

7. The bumper beam according to claim 1, wherein the shock absorber is of a substantially parallelepipedic shape, having an attachment plate, intended to rest against a longitudinal beam of the motor vehicle, the attachment element being attached to this attachment plate.

8. The bumper beam according to claim 1, wherein the attachment element is made in one piece with the shock absorber.

9. The bumper beam according to claim 1, wherein the attachment element is obtained by overmoulding the cross-member.

10. The bumper beam according to claim 1, wherein the attachment element is made of metal or metal/plastic hybrid.

11. The bumper beam according to claim 1, forming a front or rear shock module and further providing one or more of the functions chosen from the group consisting of a lower protection beam for pedestrian, an attachment for a vehicle component, a roof stiffener or a wing stiffener.

12. The bumper beam according to claim 1, wherein the cross-member is a profile having a cross-section of constant shape.

13. A method for manufacturing a bumper beam for a motor vehicle, the method comprising a step of overmolding an attachment element on a cross member and at least one shock absorber, the bumper beam having the cross-member and the at least one shock absorber, both the cross-member and the shock absorber having an upper surface and a lower surface, wherein the bumper beam has the attachment element for attaching the cross-member to the shock absorber, the attachment element comprising at least two straps connecting the upper surfaces of the cross-member and the shock absorber and/or the lower surfaces of the cross-member and the shock absorber, the at least two straps being at least partially separated from each other, and distributed in the transverse direction, each encircling the cross-member locally.

14. The bumper beam according to claim 2, wherein the strap is continuous over the width of the shock absorber.

15. The bumper beam according to claim 1 wherein the at least two straps are completely separated from each other.

16. The bumper beam according to claim 5 wherein the lateral belt covers the lateral surface of the cross-member so as to connect the lateral surface of the shock absorber and a front surface of the bumper beam.

17. The bumper beam according to claim 6 wherein a thickness of the flank is greater than 4 mm.

18. The bumper beam according to claim 7 wherein the attachment element comprises a reinforcement rib extending between the attachment plate and front of the attachment element.

19. The bumper beam according to claim 9 wherein the attachment element is obtained by overmoulding the cross-member at the same time as overmoulding the entire shock absorber.

20. The bumper according to claim 11 wherein the attachment for a vehicle component is an electrical component and the stiffener is a motor vehicle door.

21. The bumper beam according to claim 12 wherein the constant shape is an omega (), U or W shape.

22. The bumper beam according to claim 12 wherein the cross-member is made of metal or composite material.

23. The method of claim 13 wherein the overmolding step is used to manufacture the shock absorber and the attachment element simultaneously.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood on reading the accompanying figures, which are given solely by way of example and not limiting in any way, in which:

(2) FIG. 1 is a diagrammatic cross-section in a plane XZ of the vehicle of a bumper beam comprising a cross-member and a shock absorber according to a first embodiment,

(3) FIG. 2 is a cross-section similar to FIG. 1 of a bumper beam according to a second embodiment,

(4) FIG. 3 is a cross-section similar to FIG. 1 of a bumper beam according to a third embodiment,

(5) FIG. 4 is a partial diagrammatic front view of a bumper beam according to a fourth embodiment,

(6) FIG. 5 shows diagrammatic cross-sections in the transverse direction illustrating the mode of deformation of the bumper beam of FIG. 4 before and after a Danner type shock, and

(7) FIG. 6 shows cross-sections similar to FIG. 5 illustrating the mode of deformation of the bumper beam of FIG. 4 before, during and after a Bumper test type shock.

DETAILED DESCRIPTION OF THE INVENTION

(8) We now refer to FIG. 1, which shows a bumper beam 10 comprising a cross-member 1 and a shock absorber 2 for motor vehicle.

(9) In the case of FIG. 1, the cross-member 1 is a profile of general shape curved towards the front X of the vehicle, but which may be straight, elongated in a longitudinal direction of the profile which corresponds to the transverse direction Y of the vehicle when the beam is mounted on the vehicle. The profile has a cross-section of constant shape, U-shaped in this example, and is made by pultrusion, extrusion (e.g. of aluminum), injection (e.g. an HTPC type beam) or by compression (e.g. a C-SMC type beam) or by folding and stamping sheet metal. The cross-member 1 is preferably made of metal or composite material, or comprises an insert made of metal or composite material which may also be overmolded. The shock absorber 2 has a substantially parallelepipedic shape, comprising an attachment plate or support plate 21 intended to rest against a longitudinal member of the motor vehicle. Both the cross-member 1 and the shock absorber 2 have an upper surface 1s, 2s, facing towards the top of the vehicle, and a lower surface 1i, 2i, facing the road.

(10) The bumper beam 10 further comprises an element 3 for attaching the cross-member 1 to the shock absorber 2, in order to form a stronger connection between the cross-member 1 and the shock absorber 2. The attachment element 3 comprises an upper strap 3s connecting the upper surfaces 1s and 2s of the cross-member 1 and the shock absorber 2. It is understood that the attachment element 3 can alternatively or in combination comprise a lower strap 3i connecting the lower surfaces 1i and 2i of the cross-member 1 and the shock absorber 2. It is also understood that the attachment element 3 may take any form such as a single strap, several straps separated or partially separated in the transverse direction Y, or a surface covering the entire upper or lower junction line of the cross-member 1 and the shock absorber 2.

(11) The attachment element 3 shown on the embodiment of FIG. 2 has a more advantageous configuration. In this example, the attachment element 3 partially encircles the front face of the cross-member 1, extending over the entire length of the lower 1i and upper 1s surfaces of the cross-member 1 to a part of a front surface 1a of the cross-member 1, so as to have a lower strap 3i and an upper strap 3s each having a substantially L-shaped (angle) cross-section according to a plane Y of the vehicle. This L shape is advantageous, firstly since it increases the contact surface between the three elements, i.e. the cross-member 1, the shock absorber 2 and the attachment element 3, so as to strengthen the connection between them and increase the compressive strength, and secondly since the extension of the attachment element 3 on the front surface 1a of the cross-member 1 provides a hooking effect hooking the cross-member 1 to the shock absorber 2, preventing the cross-member 1 from detaching from the shock absorber 2 in case of tensile stress. It is understood that the cross-section of the attachment element 3 may take other shapes, the hooking effect on the front surface 1a being particularly interesting.

(12) The embodiment of FIG. 3 shows an attachment element 3 with a preferred configuration. In this example, the cross-member 1 preferably has a W-shaped or -shaped (omega-shaped) cross-section and the attachment element 3 has a strap 31 which completely encircles the cross-member 1, connecting the lower surface 2i and the upper surface 2s of the shock absorber 2, going continuously in front of the front face of the cross-member 1, i.e. the strap 31 goes continuously in front of the front face and preferably takes the shape or is pressed against the entire shape/the sections of this front face. Furthermore in this example, the strap 31 in addition to encircling the surfaces 1s, 1a and 1i of the bumper beam also extends along the entire length of the lower 2i and upper 2s surfaces of the shock absorber 2 up to the attachment plate 21, to which it is attached or with which it is made in one piece. This shape of the attachment element 3 is highly advantageous since the assembly of the cross-member 1 and of the shock absorber 2 is completely encircled, like the strapping of a barrel, according to a transverse plane (in the Y direction) of the cross-member 1. More specifically, the attachment element 3 and the attachment plate 21 form a closed cross-section around the cross-member 1 and the shock absorber 2.

(13) On the embodiment of FIG. 4, the attachment element 3 comprises several straps 31 substantially parallel to each other, more precisely three, distributed in the transverse direction Y of the vehicle and completely separated from each other. This optimizes the quantity of material and the reinforcement effect of the mechanical connection and of the attachment.

(14) Furthermore, the attachment element 3 comprises in this example a lateral belt comprising in this example a lateral strap 33 and a lateral flank 34, and connecting the lateral surfaces of the cross-member 1 and the shock absorber 2. More specifically in this case, the lateral belt 33, 34 fully covers the lateral surfaces of the cross-member 1 and the shock absorber 2, as shown on FIG. 4. The presence of this lateral belt is particularly advantageous. Firstly, it forms a lateral frame favoring adhesion by encapsulating the lateral surfaces of the cross-member 1 and the shock absorber 2. Secondly, the lateral belt compensates for the geometric dispersions of the cross-member 1, generally made in the form of an insert to which the attachment element 3 is overmolded, as well as the centering dispersions of the cross-member 1 in the injection mold. The thickness of the flank 33 is preferably greater than 4 mm.

(15) It is understood that the lateral belt can take different forms, in particular either the strap 33 or the straps 31, or the lateral flank 34 can be thin or have a flat surface. Preferably, the strap 33 will be wider than the straps 31, and the straps less and less wide going towards the centre in Y0 of the beam, this configuration corresponding to the levels of mechanical stress to which the beam is subjected, higher at the ends.

(16) According to one embodiment, the attachment element can be a separate part of the shock absorber 2, being overmolded thereon. Thus, the attachment element forms a frame added on top of the shock absorber.

(17) On the embodiment of FIG. 4, the attachment element 3 is made in one piece with the shock absorber 2. This considerably reinforces the mechanical connection between the cross-member 1 and the shock absorber 2. Thus, according to a particularly interesting application, the shock absorber 2 is overmolded directly behind the cross-member 1, at the same time as overmolding the attachment element 3. This means that in a single overmolding step, both the absorber 2 and the attachment element 3 can be manufactured around the cross-member 1.

(18) Advantageously, the attachment element 3 comprises a reinforcement rib 4 extending between the attachment plate 21 and the front of the attachment element 3, as shown on FIGS. 1 to 4.

(19) Preferably, the bumper beam 10 comprising the cross-member 1 and the shock absorber 2 forms a front or rear shock module and further provides one or more of the functions chosen from the group comprising a lower protection beam for pedestrian, an attachment for a vehicle component such as an electrical component, a stiffener such as a motor vehicle door, roof or wing stiffener.

(20) It is understood that the method for manufacturing the bumper beam 10 comprises a step of overmolding the attachment element 3 on the cross-member 1 and the shock absorber 2, this overmolding operation possibly being used to manufacture the shock absorber 2 and the attachment element 3 simultaneously.

(21) As can be seen on the drawing at the bottom of FIG. 5, in case of a Danner type shock with an obstacle 5 having an impact on the side of the vehicle, the cross-member 1 deforms, thereby absorbing some of the energy of the shock and one of the lateral absorbers 2 works in compression. The drawing at the top of FIG. 5 shows the elements before the shock. The attachment element 3 contributes to the energy absorption by increasing the contact area between the beam and the absorber 2.

(22) Furthermore, in case of a Bumper test type shock, shown on FIG. 6, during a head-on impact with an obstacle 5, the cross-member 1 which was initially curved before the shock (top drawing) starts to deform by losing its curve (middle drawing), which exerts a tensile force on the lateral absorbers 2, then at the end of the shock (bottom drawing), exerts a pressure on the absorbers by compressing them. The attachment element 3 maintains in particular a strong connection between the cross-member 1 and the absorbers 2 during these two steps. This also applies in case of a straight bumper beam.

(23) The invention is not limited to the embodiments described above and other embodiments will be clearly apparent to those skilled in the art.