Front structure of a motor vehicle and motor vehicle equipped with such a front structure

Abstract

Front structure of a motor vehicle and a motor vehicle equipped with such a front structure. The invention relates to a front structure (7) of a motor vehicle, comprising: - two longitudinal and parallel structural beams (13) extending on either side of a vehicle engine, - two vertical end supports (21), to which the front ends of said structural beams are fixed, and - a transverse upper cross member (47) connecting, transversely relative to the vehicle, said end supports (21) to each other. The invention is notable in that the front structure (7) includes two support pieces (29) interfacing between one of said end supports (21) and a corresponding end of said upper cross member, arranged in said front structure to transmit transverse forces from said structural beams (13) to said upper cross member during a frontal impact with an overlap of 25% or less.The invention also relates to a motor vehicle comprising such a front structure. Figure for the abstract: Figure 2.

Description

Description Title of the invention: Front structure of a motor vehicle and motor vehicle equipped with such a front structure technical field

[0001] The invention relates to the field of motor vehicles, more particularly to behavior of motor vehicles in terms of deformation in the event of a frontal collision low coverage, and concerns a front structure of a motor vehicle as well than a motor vehicle equipped with such a front structure. Previous technique

[0002] Among the plurality of tests used for the type approval of motor vehicles, a small overlap frontal crash test Anglo-Saxon minology) is applied, particularly for the American market via the IIHS protocol (Anglo-Saxon acronym for Insurance Institute for Highway Safety) and for the Chinese market via the IASI protocol (Anglo-Saxon acronym for Insurance Authorization). tomobile Safety Index).

[0003] — This test consists of propelling a motor vehicle at a speed of 64 km / h towards a rigid obstacle such as a barrier, with an overlap range between the obstacle and the front of the vehicle less than 25%. This type of test simulates impacts with a wall or post in front of and to the side of the vehicle.

[0004] Generally speaking, the front structure of a motor vehicle comprises two structural elements, typically longitudinal structural beams, commonly called "stretchers" because they can have a profile lateral, resembling the arms of a stretcher intended for transporting a person or objects. The structural beams extend longitudinally relative to the vehicle, on either side of the engine, from the passenger compartment towards the front of the vehicle.

[0005] — Conventionally, the front ends of the longitudinal structural beams are extended by deformable boxes in case of impacts, commonly called "crash- boxes”, configured to be compressed in the event of a frontal collision with the vehicle in a to absorb the efforts.

[0006] At the junction of each of the deformable boxes and each of the structural beams- corresponding longitudinal turrets is a facade support, extending vertically stability relative to the vehicle and serving in particular to support the front facade of the vehicle. The front ends of the beams are fixed to these facade supports. longitudinal structures.

[0007] — The front structure is also provided with a plurality of transverse cross members, each presenting a first end fixed on one of the two facade supports, one end of the cross members is fixed to the other of the two front supports on the other side of the vehicle. These cross members include, in particular, a lower cross member and an upper cross member, in reference to their respective positions relative to the front structure. These cross members are designed to absorb lateral forces that can occur, particularly in the event of a vehicle impact. The transmission of these lateral forces from one side of the vehicle to the other is then achieved via the upper and lower cross members of the vehicle's front structure. Figure 1 shows a facade support 1 known from prior art. The facade support 1 has a zone 3 in its upper portion 5, which is narrower than the rest of the facade support. The presence of this narrower zone 3 is necessary to allow the passage of a fastening assembly for the upper cross member of the front structure. In the case of a high-speed frontal collision against a rigid obstacle with low overlap, the vehicle is subjected, in particular, to significant transverse forces due to the offset position of the obstacle towards the outside. Due to its narrow width and shape, this reduced-width zone 3 exhibits low resistance and constitutes a structural weakness. It has been observed that the facade supports 1 undergo significant deformation in this zone 3 during a low-overlap frontal impact. This deformation is such that the facade supports | transmit poorly, or no longer transmit, the transverse forces to the upper transverse beam of the front structure. Also, during a high-speed frontal impact against a rigid obstacle with minimal overhang, the front structure of the vehicle is subjected to combined transverse and longitudinal forces due to the vehicle's forward movement against the obstacle, creating a torsional moment. Zone 3 of the front support 1 also has low resistance to this torsional moment. This poor resistance of the front support to transverse forces and torsional moment results in significant damage to the front structure of the vehicle during the impact, as well as a significant risk of intrusions into the vehicle's passenger compartment. Description of the invention The present invention aims to overcome the aforementioned drawbacks, and to this end relates to a front structure of a motor vehicle, comprising: - two longitudinal and parallel structural beams extending longitudinally relative to the vehicle, on either side of a vehicle engine, - two vertical facade supports, to which are fixed the front ends of said longitudinal structural beams, extending vertically relative to the vehicle, and - a transverse upper cross member connecting, transversely relative to the vehicle, said facade supports to each other, said front structure being remarkable in that it comprises two support pieces, each interfacing between one of said facade supports and a corresponding end of said upper transverse cross member, said support pieces being arranged in said front structure to transmit transverse forces from said longitudinal structural beams to said upper transverse cross member during a frontal impact with an overlap of less than or equal to 25%. Thus, by providing a support piece that interfaces between the facade support and the upper cross member, the stiffness of the assembly formed by the facade support and the support piece is increased. This structurally reinforces the facade support, particularly in the area where transverse forces are transmitted during a low-overlap frontal impact. Consequently, the transmission of transverse forces experienced during a low overlap frontal impact is improved from one side of the vehicle to the other, particularly via the upper cross member, compared to the previous art. According to optional features of the front structure according to the invention: - at least one of the two support pieces includes a closed hollow body extending vertically from the front ends of the longitudinal structural beams to the upper cross member; - the closed hollow body includes a hollow tube extending vertically relative to the vehicle when the support piece is mounted on said front structure; - at least one of the two support pieces has, in its lower part, a hollow compartment extending transversely relative to said hollow tube; - at least one of the support pieces includes at least one spacer mounted longitudinally in the hollow compartment; - at least one of the support pieces includes an anti-torsion bracket fixed to the front support and arranged in the front structure so as to take up torsional forces during a frontal impact with an overlap of less than or equal to 25%; - in one embodiment, the anti-torsion bracket has a vertical face, extending vertically relative to the vehicle when the support piece is mounted on said front structure, and a transverse face, extending transversely relative to said vertical face; - In one embodiment, the anti-torsion bracket is arranged at the level of an upper part of the support piece and the transverse face of the anti-torsion bracket is fixed on a transverse wing of the facade support; - at least one of the two support pieces is fixed to one of the facade supports and to the upper transverse cross member. The invention also relates to a motor vehicle comprising a front structure according to the invention. Brief description of the drawings Other features, purposes and advantages of the invention will become apparent from the detailed description that follows, for understanding of which reference should be made to the accompanying drawings in which: [Fig.1] is a perspective view of a facade support according to the prior art. [Fig.2] is a perspective view of a front structure of a motor vehicle according to the invention. [Fig.3] is a perspective view of a facade support according to the invention. [Fig.4] is a perspective view of a facade support piece according to the invention. [Fig.5] is a perspective view showing the connection obtained between the front support, the support piece and an upper cross member of the front structure of the vehicle according to the invention. [Fig.6] schematically illustrates the distribution of forces on the front structure of the vehicle according to the invention, during a low overlap frontal impact. [Fig.7] is a perspective view of the support piece obtained according to an alternative embodiment of the invention. Description of the implementation methods In the following description, elements with an identical structure or analogous functions are designated by the same reference. By convention, and without limitation, we will adopt longitudinal, vertical and transverse orientations indicated by the direct trihedron (L, V, T) designating the longitudinal, vertical and transverse axes of the vehicle. We refer to [Fig.2] showing an example of the front structure 7 of a motor vehicle according to the invention, in isometric view. The front structure 7 of the vehicle typically includes a powertrain mounted at location 9, held and protected by means of several metal beams. Note that the vehicle has a longitudinal median plane of symmetry P. From a front upright 11 of a passenger compartment part of the vehicle (not visible in these figures) and laterally to the powertrain, extend two longitudinal and parallel structural beams 13 (only one is visible in [Fig.2]), commonly called “stretchers”, A deformable box in case of impact (not shown), commonly called " "crashbox" is mounted in front of each structural beam 13. The two boxes are held together transversely by a bumper crossmember (not shown). This first assembly, consisting of the 13 longitudinal structural beams, the deformable boxes and the bumper crossmember connecting the deformable boxes, forms a first path for the reabsorption of vehicle forces during a frontal impact, generally called the "upper path" or "superior path" or even the "stretch line". Below the upper track are two longitudinal lower beams 15 (partially shown in [Fig. 2]), commonly called "extensions," positioned parallel to each other on either side of the powertrain, below the longitudinal structural beams 13. The lower beams 15 are extended forward by two lower impact-deformable box sections (not shown), joined transversely at the front by a lower bumper crossmember 17. This second assembly, consisting of the lower beams 15, the lower deformable boxes and the lower bumper crossmember 17 connecting the lower deformable boxes, forms a second path for absorbing vehicle forces during a frontal impact, generally called the "lower path" or "lower path". A third way of force recovery, represented by wing linings 19 extending longitudinally on either side of the powertrain, allows the transmission of forces from the front of the vehicle to the front pillar 11 of the passenger compartment (not visible in these figures). The front structure 7 shown in the figures has three load-bearing paths. However, the present invention can be adapted to front structures having only two load-bearing paths, namely the first path (upper path at the level of the structural beams 13) and the third path (path at the level of the wing linings 19). The transmission of forces is facilitated by the presence of front supports 21 according to the invention. For example, there are two front supports 21 per vehicle. The front supports 21 extend vertically relative to the vehicle. The longitudinal structural beams 13 are each fixed at their front ends 13a to the corresponding facade supports 21. The wing linings 19 of the third load transfer path are also each fixed at their front ends 19a to the corresponding facade supports 21 by means of a fixing means known to the person skilled in the art. Reference is made to [Fig.3] illustrating the facade support 21 according to the invention, in isometric view. The facade support 21 has a horizontal section – along the plane (L, T) – hollow, for example U-shaped. When the facade support is assembled into the structure At the front of the vehicle, the front support extends vertically relative to the vehicle. The U-shaped section of the facade support 21 comprises a front face 21A, with a rectangular profile for example, as well as lateral wings 21B, 21C and a transverse wing 21D. The two lateral wings 21B, 21C are positioned laterally on either side of the front face 21A. The transverse wing 21D extends horizontally over part of the width of the front face 21A, at the level of the upper end of the front support 21. The lateral wing 21C has a plurality of fixing holes 23 for fixing surrounding parts of the front structure. The front face 21 A also includes a fixing hole 25 for fixing the corresponding longitudinal structural beam, as well as a plurality of fixing holes 27 allowing the fixing of a support piece 29 according to the invention visible in [Fig.4] and whose realization is detailed in the rest of the description. Similarly, the transverse wing 21D has a fixing hole 31 which can be used to fix the support piece 29. The facade support 21 may, alternatively, have a horizontal section — along the plane (L, T) — other than the U-shaped one just described. In particular, the facade support may consist of only one lateral flange 21B, 21C. Reference is made to [Fig.4] illustrating the support piece 29 in isometric view, obtained according to a first variant of the invention. The support piece 29 has a hollow body, which can be formed by assembling two pieces of sheet metal fixed to each other, for example by end-stamping. The hollow body extends vertically from the front ends of the longitudinal structural beams 13 to the upper cross member 47 (visible in [Fig.5]). In the illustrated embodiment, the hollow body comprises a hollow tube 33, extending vertically relative to the vehicle when the support piece is mounted on the front structure 7 of the vehicle. The tube 33 has a horizontal cross-section – along the plane (L, T) – for example rectangular. Other horizontal sections of tube 33 are conceivable, such as a circular section. In the illustrated embodiment, the tube 33 extends almost the entire length of the support piece 29. The term "length" refers to the height of the tube when the support piece 29 is installed in the vehicle. In another embodiment not shown, the tube 33 extends over the entire length of the support piece 29. The support piece 29 has in its lower part 29A a hollow, parallelepiped-shaped compartment 35 extending transversely relative to the tube 33. The tube 33 is held at its lower part by the hollow compartment 35, which increases the flexural strength of the tube 33. The compartment 35 can be formed by a front face 35A and a rear face 35B mounted opposite each other and each fixed along the tube 33. The compartment 35 also has a lateral face 35C opposite the tube 33. The front face 35A has multiple mounting holes for attaching the deformable crash box (not shown), which is intended to be connected to the deformable crash box mounted on the other side of the vehicle by the bumper crossmember (not shown). Four mounting holes 37A, 37B, 37C, 37D are shown in [Fig. 4], but a different number of mounting holes may be provided. In one embodiment, the support piece 29 has two spacers 39 mounted in the compartment 35 and extending longitudinally in the compartment 35. The spacers 39 extend between the front faces 35A and 35B of the compartment 35. According to one embodiment, the support piece 29 comprises a single spacer. According to another embodiment, the support piece 29 has more than two spacers. In the embodiment shown in the figures, the spacers 39 are positioned at the height of the fixing holes 37B and 37C (in the figure, only the upper spacer 39 is visible). The support piece 29 has, in its upper part 29B, a front face 41A and a rear face 41B mounted opposite each other and each fixed along the tube 33. When the tube 33 extends practically over the entire length of the support piece 29, as shown in the figures, the front faces 41A and rear faces 41B protrude from the hollow tube 33 at their upper ends to provide a suitable space for fixing the ends of the upper transverse cross member 47 (visible in [Fig. 5]). For this purpose, the front faces 41A and rear faces 41B have weld notches 43. According to one arrangement of the invention, the support piece 29 includes an anti-torsion bracket 45 arranged in the front structure to allow the torsional forces to be absorbed, in particular the torsional forces generated on the vertical axis of the support piece 29 and created by the input of combined transverse and longitudinal forces occurring during the unfolding of a low overlap frontal impact, as will be seen in the rest of the description. In one embodiment, the anti-torsion bracket 45 is arranged at the upper part 29B of the support piece. The anti-torsion bracket 45 has a vertical face 45A and a transverse face 45B, extending transversely relative to the vertical face 45A. The vertical face 45A is fixed on the tube 33 and the transverse face 45B extends transversely relative to the tube 33. The vertical face 45A extends in a plane (L, V) and is fixed against a lateral face of the tube 33. The front faces 41A and rear faces 41B of the upper part 29B of the support piece 29 are fixed on each side of the anti-torsion bracket 45, specifically at its transverse face 45B, in order to reinforce its torsional rigidity. To further reinforce the torsional rigidity of the support piece 29, the front faces 41A and rear faces 41B of the upper part 29B of the support piece 29 can be fixed on each side of the vertical face 45A of the anti-torsion bracket 45. We refer to [Fig.5] showing the assembly between the support piece 29, the front support 21 of the front structure of the vehicle and the upper transverse cross member 47. The support piece 29 is fixed on one side to the front support 21 and on the other side to the upper cross member 47. Thus, the ends of the upper cross member 47 connect the front supports 21, positioned on either side of the vehicle, via the corresponding support pieces 29. In other words, the connection between a front support 21 and the corresponding end of the upper cross member 47 is indirect. Alternatively, the ends of the upper cross member 47 can be mounted directly on each corresponding facade support 21, the support piece 29 being in this case only fixed on the facade support 21. In other words, the connection between a facade support 21 and the corresponding end of the upper cross member 47 is direct here, the support piece 29 reinforcing the facade support as close as possible to the fixing area between the upper cross member 47 and the facade support 21. When the support piece 29 connects the upper cross member 47 to the facade supports 21, the support piece 29 is assembled to the facade support 21 by means of the fixing of the rear face 35B of the support piece 29 on the front face 21A of the facade support 21. The fixing is carried out by welding and / or by means of rivets and screws, by means of fixing holes (not visible in the figures) made on the rear face 35B of the support piece 29 and coinciding with the fixing holes 27 provided on the front face 21A of the facade support. The support piece 29 is also assembled to the support of the facade 21 by means of the fixing of the transverse face 45B of the anti-torsion bracket 45 on the transverse wing 21D of the facade support 21. For this purpose, the transverse face 45B of the anti-torsion bracket 45 has a fixing hole 49 which, when the support piece 29 is mounted on the facade support 21, coincides with the fixing hole 31 of the transverse wing 21D of the facade support 21. Alternatively, the transverse face 45B of the anti-torsion bracket 45 is welded onto the transverse wing 21D of the facade support 21. Each end of the upper transverse cross member 47 is fixed to the corresponding support piece 29, for example by means of weld points made at the weld notches 43. When the upper transverse cross member 47 is fixed to the corresponding support piece 29, the upper end of the tube 33 of the support piece 29 defines a vertical support for the upper cross member 47. Similarly, when the upper transverse cross member 47 is fixed to the corresponding support piece 29, the front faces 41A and rear faces 41B of the support piece 29 longitudinally block the upper transverse cross member 47. We now refer to [Fig.6] schematically illustrating the distribution of forces on the front structure 7 of the vehicle during a low overlap frontal impact. When a low overlap frontal impact occurs, for example on the left side of the vehicle, the vehicle experiences longitudinal forces represented by arrow 51, and transverse forces, represented by arrows 53, 55, 57. The forces represented by arrows 51, 53, 55, 57 described for the left side of the vehicle can be found symmetrically on the right side of the vehicle in the event of a low overlap frontal impact occurring on the right side of the vehicle. The longitudinal forces 51 are transmitted to the deformable boxes mounted on the front face 35A of compartment 35 of the support piece 29, which can be crushed. A portion of the longitudinal forces is transmitted to the front face 35A of compartment 35 of the support piece 29. The support piece 29, whose front face 35A of compartment 35 is separated from the rear face 35B by the spacers 39, ensures good resistance to forces during longitudinal loading. The transverse forces 53, experienced by the front structure 7 at the level of the lower beams 15, are transmitted to the other side of the vehicle via the lower bumper crossmember 17. The transverse forces 55, suffered by the front structure at the level of the upper track, are taken up by the support piece 29, which structurally reinforces the facade support 21, so that the structural deformation of the facade support 21 is consequently reduced compared to the deformations observed in the prior art. In particular, the hollow body of the support piece 29, formed here by the hollow tube 33, allows reinforcement against torsion compared to open profiles of the U-section type, and in bending, for the transmission of forces to the upper cross member 47. Also, the hollow body allows the transmission of transverse forces to the upper cross member 47. The support piece 29 thus ensures an efficient transmission of transverse forces from the point of entry of the forces, located at the level of the longitudinal structural beam 13, to the upper transverse cross member 47, as represented by the arrow 57. The transverse forces 55, 57 are thus efficiently transmitted to the other side of the vehicle, via the upper transverse cross member 47. Also, the torsional moment, created by the entry of combined transverse and longitudinal forces occurring during the unfolding of the impact due to the advance of the vehicle against the obstacle, is taken up by the support piece 29, thanks to the connection made between the transverse face 45B of the anti-torsion bracket 45 and the transverse wing 21D of the front support 21. In general, all beams, crossbeams and facade supports are made of metallic materials, particularly steel or aluminum. The support piece 29 of the invention can be made of steel. Reference is made to [Fig.7] illustrating a support piece 290 in isometric view, obtained according to a second embodiment of the invention. In this variant, the support piece 290 consists of an aluminum profile, allowing the mass impact of the support piece to be limited. In this embodiment, the support piece 290 has a parallelepiped compartment 350 in its lower part 290A. The compartment 350 has a front face 350A with a plurality of mounting holes 370A, 370B, 370C, 370D for attaching the deformable housing in case of impact (not shown). The support piece 290 has in its upper part 290B a fixing plate 291 allowing the fixing of one end of the upper transverse cross member 47. The upper transverse cross member 47 has fixing tips (not shown), mounted at its ends and adapted to allow the fixing of the upper cross member 47 onto the fixing plate 291 of the support piece 290. Thanks to the present invention, increased structural reinforcement is provided between the facade support and the upper cross member, which makes it possible to considerably improve the resistance to frontal impact at low overlap compared to the prior art. As will be understood, the present invention is not limited to the forms of realization of this front structure of a motor vehicle and of this motor vehicle equipped with such a front structure, described above only as illustrative examples, but on the contrary it embraces all variants involving the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

Claims

Demands

1. Front structure (7) of a motor vehicle, comprising: - two longitudinal and parallel structural beams (13) extending longitudinally relative to the vehicle, on either side of a vehicle engine, - two vertical facade supports (21), on which are fixed ex- openings before said longitudinal structural beams (13), extending vertically relative to the vehicle, and - a transverse upper cross member (47) connecting transversely rela- attached to the vehicle, the said facade supports (21) between each other, said structure before (7) being characterized in that it comprises two support pieces (29, 290), each interfacing between one of said facade supports (21) and a corresponding end of said cross member upper transverse (47), said support pieces (29, 290) being arranged in said structure before (7) to transmit efforts transverse from the said longitudinal structural beams (13) towards said upper cross member (47) transverse during a frontal impact coverage less than or equal to 25%.

2. Front structure (7) according to claim 1, characterized in that at less than one of the two support pieces (29) comprises a hollow body closed, extending vertically from the front ends of the beams longitudinal structural members (13) up to the upper cross member (47).

3. Front structure (7) according to claim 2, characterized in that the closed hollow body comprises a hollow tube (33) extending vertically relative to the vehicle when the support piece (29) is mounted on said structure before (7).

4. Front structure (7) according to claim 3, characterized in that at at least one of the two support pieces (29) comprises, in its in- lower, a hollow compartment (35) extending transversely rela- tivement audit tube (33) hollow.

5. Front structure (7) according to claim 4, characterized in that at at least one of the support pieces (29) has at least one spacer (39) mounted longitudinally in the hollow compartment (35).

6. Front structure (7) according to any one of claims 1 to 5, ca- characterized in that at least one of the support pieces (29) comprises an anti-torsion bracket (45) fixed to the facade support (21) and arranged in the front structure (7) so as to take up the torsional forces during of a frontal impact with an overlap of 25% or less.

7. Front structure (7) according to claim 6, characterized in that The anti-torsion bracket (45) has a vertical face (45A), extending vertically relative to the vehicle when the support part (29) is mounted on said front structure (7), and a transverse face (45B), extending transversely relative to said vertical face (45A).

8. Front structure (7) according to claim 7, characterized in that the anti-torsion bracket (45) is arranged at the level of an upper part (29B) of the support piece (29) and in that the transverse face (45B) the anti-torsion bracket (45) is fixed to a transverse wing (21D) of the facade support (21).

9. Front structure (7) according to any one of claims 1 to 8, ca- characterized in that at least one of the two support pieces (29, 290) is fixed to one of the facade supports (21) and to the upper cross member {47) transverse.

10. A motor vehicle comprising a front structure (7) according to one any of the claims | to 9.