Side member reinforcement for motor vehicles comprising frangible ceramic elements.

Abstract

The invention relates to a side member reinforcement (1) forming a profile designed to extend in a longitudinal direction along at least a portion of a side member (2) of the underbody of a motor vehicle (3), the reinforcement (1) being designed to absorb, when it extends along the side member (2), a portion of the energy of a lateral impact suffered by the vehicle (3) during bending of the side member (2), the reinforcement (1) being characterized in that it comprises at least one frangible element (11) made of ceramic, the rupture of each frangible element (11) making it possible to absorb a portion of the energy of the lateral impact. The invention also relates to a side member structure (5) reinforced by a reinforcement (1) according to the invention. (Figure 2)

Description

Title of the invention: Side member reinforcement for a motor vehicle comprising frangible ceramic elements.

[0001] The technical field concerns side member reinforcements designed to absorb the energy of a side impact, underbody structures comprising at least one side member reinforcement and motor vehicles equipped with at least one underbody structure.

[0002] Electric vehicles are experiencing growing interest from customers while their autonomy is constantly being improved by car manufacturers. To achieve this, the industrial players involved have invested heavily in the development of new technologies to offer ever more efficient batteries, i.e. batteries offering increased charging speeds, constantly increasing capacities and high energy densities.

[0003] In parallel with the improvement of technologies, automobile manufacturers are also focusing on increasing the volume dedicated to batteries in their electric motor vehicles. However, current batteries suffer from disadvantages inherent to the technologies used and in particular their instability in the event of an impact: a battery cell damaged following an impact can in fact undergo runaway and cause a fire to start. Also, due to the risk of fire, certain areas of a vehicle are considered as exclusion zones in which the installation of batteries is excluded due to the high probability of undergoing deformation in the event of an impact.

[0004] In order to guarantee the safety of users, restrictive standards impose certain behaviors of the vehicle during impacts, in particular during a side impact consisting of projecting the vehicle against a post of a predefined diameter (25.4 mm) so that the latter hits the vehicle on its side, at a predefined relative speed (33 km / h). In the following, a side impact refers in particular to such an impact. Thus, during a side impact, current standards stipulate, on the one hand, that the deceleration at the level of an electric module must not exceed a predetermined threshold value (currently 60 g) and, on the other hand, that the side member must not generate an intrusion into the volume occupied by a battery.These two restrictions require car manufacturers to provide particularly strong rigid structures in which a side member is reinforced by extruded reinforcement devices arranged in the side member designed to dissipate energy by deforming during an impact.

[0005] Conventionally, some of the battery packs are screwed onto the side members which are obviously particularly reinforced as indicated previously. The packs The batteries are also reinforced using a reinforced frame that at least partially surrounds the batteries.

[0006] Consequently, the dimensions of the side members, the reinforcement devices and the reinforced frames constitute significant exclusion zones, greatly reducing the volumes that can be dedicated to the batteries.

[0007] Thus, there is a need for an optimized solution making it possible to reduce exclusion zones and facilitating the installation of electrical energy storage modules along the side members of a vehicle.

[0008] The present invention aims to overcome the problems set out above. In this technical context, one aim of the present invention is to provide a rocker panel reinforcement making it possible to reduce the dimensions of the rocker panel and reduce the exclusion zones.

[0009] For this purpose, the present invention relates to a side member reinforcement forming a profile designed to extend in a longitudinal direction along at least a portion of a side member of the underbody of a motor vehicle, the reinforcement being designed to absorb, when it extends along the side member, a portion of the energy of a lateral impact suffered by the vehicle during bending of the side member, the reinforcement being characterized in that it comprises at least one frangible ceramic element, the rupture of each frangible element making it possible to absorb at least a portion of the energy of the lateral impact.

[0010] The invention also relates to a rocker structure of a motor vehicle comprising a rocker side member reinforced by at least one side member reinforcement according to the invention.

[0011] Finally, the invention also relates to a motor vehicle comprising at least one underbody structure according to the invention.

[0012] Thus, a spar reinforcement according to the invention makes it possible to reinforce a spar and to prevent the intrusion of the spar into the space dedicated to the battery. The presence of at least one frangible ceramic element makes it possible to control the absorption of energy from an impact and makes it possible to limit the deformations undergone by the spar during a lateral impact. The frangible ceramic element has a very high modulus of elasticity with a zone of almost zero plastic deformation.

[0013] The rupture of at least one frangible element makes it possible to absorb a greater quantity of energy released by a lateral impact than a conventional reinforcement device not having a frangible element. Thanks to the use of at least one frangible element, the dimensions of the spar reinforcement according to the invention can be reduced compared to the dimensions of a conventional reinforcement device, thus freeing up areas usable by electrical energy storage modules.

[0014] According to one embodiment of the invention, the spar reinforcement comprises a plurality of juxtaposed cells extending in the longitudinal direction, at least one frangible element consisting of a cylindrical ceramic bar housed in a cell. Such a spar reinforcement is thus simple and inexpensive to produce.

[0015] According to one possibility, the reinforcement comprises a plurality of cylindrical bars having predefined cross-sectional areas, the cylindrical bars being distributed in the cells according to a predefined distribution. Such a distribution makes it possible to control the rapid deceleration of the post impacting the vehicle after the impact and makes it possible to avoid the intrusion of the side member reinforcement into the space dedicated to the batteries.

[0016] Advantageously, at least one frangible element is surrounded by a foam material. The use of foam material makes it possible to avoid vibrations of the frangible element thus surrounded and the associated noises.

[0017] According to one embodiment of the invention, the vehicle comprises an electrical energy storage module arranged near the side rail of the underbody.

[0018] The invention will be better understood on reading the detailed description which follows, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0019] [Fig-1] [Fig.l], represents a perspective view of a low structure of body of a vehicle according to the invention showing an exploded view of the side member according to the invention;

[0020] [Fig.2] [Fig.2] represents a schematic view of a cross-section of the spar of [Fig.l].

[0021] In these figures, the same references are used to designate the same elements.

[0022] A side member reinforcement 1, illustrated in the figures, forms a profile, for example made of extruded aluminum, designed to extend along a longitudinal direction illustrated by the axis AA of [Fig.l]. The reinforcement 1 is designed to extend along at least a portion of a side member 2 of the underbody, illustrated in [Fig.l], a portion of which has been removed for understanding the figure, equipping a motor vehicle 3, partially illustrated in [Fig.l]. To this end, the side member 2 has a cavity 4 extending along the axis AA of [Fig.l], sized to accommodate at least one side member reinforcement 1.

[0023] The side member 2 thus reinforced by at least one side member reinforcement 1 forms a rocker panel structure 5 according to the invention. The vehicle 3 thus equipped with the structure 5 forms a vehicle according to the invention. It comprises for example an electrical energy storage module 6 arranged along the side member 2. The module 6 comprises a battery 7 surrounded by a frame 8 formed by extruded aluminum, illustrated in [Fig.l].

[0024] The reinforcement 1 is designed to absorb, when it extends along the side member 2 in the cavity 4, at least part of the energy of a lateral impact suffered by the vehicle 3 during bending of the side member 2. The bending of the side member 2 in fact causes the reinforcement 1 to deform, thus absorbing at least part of the energy of the impact. For this purpose, the reinforcement 1 has a structure adapted to such absorption and comprises, for example, a plurality of juxtaposed cells 9 which extend in the longitudinal direction of the axis AA, illustrated in FIGS. 1 and 2. A cross-section of the reinforcement 1 along a plane normal to the axis AA shows cells 9 having a rectangular or square section. Certain cells 9 delimited by an outer face 10 of the reinforcement 1, however, have a complex-shaped section linked to the shape of the outer face 10. As illustrated in [Fig.2], the cells 9 have a width which varies from one cell 9 to another adjacent cell along a transverse axis BB, illustrated in [Fig.2]: the cells 9 have a width measured along the transverse axis BB which decreases all the more as the cell 9 is located close to the outer face 10 of the spar 2, the outer face 10 constituting the surface undergoing the impact during a lateral impact.

[0025] The reinforcement 1 according to the invention comprises at least one frangible element 11 made of ceramic, the rupture of each frangible element 11 making it possible to absorb part of the energy of the lateral impact. Each frangible element 11 has a predefined cross-sectional area 12. In the embodiment illustrated in the figures, the reinforcement 1 comprises a plurality of frangible elements 11 each consisting of a cylindrical bar 13. Each cylindrical bar 13 is housed in a separate cell 9. Each cylindrical bar 13 has, for example, a circular base section 14 whose diameter varies according to the width of the cell 9 which accommodates the cylindrical bar 13. The greater the width of the cell 9, the greater the diameter of the circular base 14. For example, the diameter of the circular base 14 represents at least 80% of the width of the cell 9 which accommodates it.Thus, the distribution of the cylindrical bars 13 forms a predefined distribution chosen so that the thinnest cylindrical bars 13 are located closest to the impact and are broken first during a lateral impact. The cylindrical bars 13 break all the more easily as the diameter of their circular base 14 is small. Conversely, the cylindrical bars 13 located near the frame 8 have a larger diameter than the cylindrical bars 13 placed closer to the outer face 10, their breaking making it possible to absorb an increased quantity of energy in order to avoid the intrusion of the spar 2 by deformation of the reinforcement 1 in the . frame 8 and in battery 7. The chosen distribution makes it possible to absorb the energy of the impact while controlling the deceleration of the post used to simulate the side impact.

[0026] In order to perfectly immobilize each cylindrical bar 13 in its cell 9, each cylindrical bar 13 is surrounded by a foam material, not shown in the figures, intended to fill at least in part the space between the cylindrical bar 13 and the walls of its cell 9.

[0027] Thus, the spar reinforcement 1, thanks to the frangible elements 11, has an increased capacity for absorbing energy from a lateral impact and makes it possible to free up space usable by the electrical energy storage module 6. The predefined distribution of the cylindrical bars 13 makes it possible to control the deceleration after the impact and makes it possible to avoid intrusion into the volume dedicated to the module 6.

[0028] The invention is not limited to the embodiment of the spar reinforcement described above, only by way of example, but other embodiments can be designed by those skilled in the art without departing from the scope and scope of the present invention.

Claims

Claims

1. A side member reinforcement (1) forming a profile designed to extend in a longitudinal direction (AA) along at least a portion of a side member (2) of the underbody of a motor vehicle (3), the reinforcement (1) being designed to absorb, when it extends along the side member (2), a portion of the energy of a lateral impact suffered by the vehicle (3) during bending of the side member (2), the reinforcement (1) being characterized in that it comprises a plurality of juxtaposed cells (9) extending in the longitudinal direction (AA), at least one frangible element (11) consisting of a cylindrical ceramic bar (13) housed in a cell (9), the rupture of each frangible element (11) making it possible to absorb at least a portion of the energy of the lateral impact.

2. Reinforcement (1) of a spar according to claim 1, characterized in that it comprises a plurality of cylindrical bars (13) having predefined cross-sectional surfaces (12), the cylindrical bars (13) being distributed in the cells (9) according to a predefined distribution.

3. A spar reinforcement (1) according to one of claims 1 to 2, characterized in that at least one frangible element (11) is surrounded by a foam material.

4. Underbody structure (5) of a motor vehicle (3) comprising an underbody side member (2) reinforced by at least one side member reinforcement (1) according to one of claims 1 to 3.

5. Motor vehicle (3) comprising at least one underbody structure (5) according to claim 4.

6. Vehicle (3) according to claim 5, comprising an electrical energy storage module (6) arranged near the side member (2) of the underbody.

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