Longeron for the structure of a motor vehicle

Abstract

The invention relates to a side member (L) for the structure of a motor vehicle, comprising a hollow body comprising two side walls (11) opposite each other, and a reinforcing structure (2) housed in said hollow body (1). The invention consists in that the reinforcing structure (2) is a cellular structure comprising at least two rows of cells defined by assembled tubular elements, the longitudinal axis of the tubular elements extending perpendicular to the longitudinal axis of the hollow body and to the transverse axis of the hollow body between the two side walls (11). Figure 2

Description

Title of the invention: Longeron for the structure of a motor vehicle

[0001] The present invention relates to the field of motor vehicles, in particular with electric or hybrid engines. The invention relates more specifically to the field of regulatory and consumer passive safety, and in particular with regard to side impact, in a motor vehicle provided with a closed battery module, fixed under the underbody of the vehicle.

[0002] During a side impact of the electric vehicle, also called a pole impact, two main conditions must be respected to protect the occupants from electrical and chemical risks and against the outbreak of fires. Firstly, it is necessary to preserve the integrity of the battery to avoid any contact of the battery with its environment during the impact, then it is necessary to ensure that the acceleration of the battery cells does not exceed a limit value of 60 g.

[0003] In patent US20220315110, a device for reinforcing a body side rail is described by implementing a double composite honeycomb structure with an orientation of the honeycomb, longitudinal axis of the cells along the y or x and y axis of the vehicle. The two structures are superimposed along the y axis. However, such reinforcement has a size that cannot be used on all vehicle platforms.

[0004] The side member is a constituent element of the structure of a motor vehicle which extends on each side of the underbody between the front and the rear of this structure. During a side impact, called a post impact, the side member will undergo a deformation towards the center of the underbody and therefore of the battery module under the underbody. Also, in order to limit intrusion during a side impact, it is known to implant in a side member a deformable structure such as an extruded aluminum beam of significant stiffness and the deformation of which contributes to preserving the integrity of the battery during a collision with side impact. However, the consequence is a significant deceleration of the battery modules during the impact.

[0005] The invention therefore aims to overcome the cited drawbacks of the prior art by proposing a spar with which an optimized transmission of forces is obtained, making it possible to dissipate the impact energy and reduce the deceleration of the battery cells.

[0006] To this end, the invention relates to a side member for the structure of a motor vehicle, comprising a hollow body having two side walls opposite one another, and a reinforcing structure housed in said hollow body, characterized in that the reinforcing structure is a cellular structure comprising at least two rows of cells defined by assembled tubular elements, the longitudinal axis of the tubular elements of the structure extending perpendicular to the longitudinal axis of the hollow body and to the transverse axis of the hollow body between the two side walls.

[0007] Advantageously, the cellular structure allows optimized dissipation of impact energy by progressive deformation and a homogeneous distribution of forces due to the geometry of the tubular elements.

[0008] Preferably, the at least two rows of tubular elements are held between two plates, preferably made of sheet metal, assembled for one against the first row of tubular elements and for the other against the last row of tubular elements, by gluing or any other suitable means of fixing the plates against the walls of the tubular elements.

[0009] According to a preferred embodiment, the tubular elements are hexagonal tubular elements, assembled in at least two rows, thus forming a honeycomb cellular structure. This honeycomb cellular structure is particularly advantageous for dissipating energy by progressive deformation and for distributing forces evenly due to the hexagonal geometry of the cells.

[0010] The invention therefore also relates to a motor vehicle structure, comprising two side members according to the invention, in which each side member is installed on the motor vehicle structure, so as to extend along one side of the underbody with its longitudinal axis extending along the longitudinal axis X of the vehicle, the transverse axis between the two side walls of the side member extending along the transverse axis Y of the vehicle and the longitudinal axis of the tubular elements of the reinforcement device extending along the axis Z of the vehicle.

[0011] Advantageously, when the side members are installed on the structure, these extend along each side of the underbody with the side walls of the hollow body of the side member which are for one on the underbody side and for the other on the exterior side of the vehicle, forming the impact face of a lateral impact, extending in a plane defined by the longitudinal axis X and the axis Z of the vehicle.

[0012] The axes of the cells formed from the tubular elements which make up the cellular reinforcement structure are thus positioned normal to the ground, oriented along the Z axis of the vehicle.

[0013] In the event of a collision with a post, the reinforcement device according to the invention and more particularly the honeycomb cellular structure allows: - optimized dissipation of impact energy by progressive deformation of the rows of tubular elements, and - a homogeneous distribution of forces along the walls of the tubular elements by the geometry of the cells or alveoli, particularly advantageous when the shape of the tubular elements is hexagonal.

[0014] The invention also relates to a motor vehicle comprising a structure provided with side members according to the invention and which also comprises an electric battery module comprising a protective housing containing the electric batteries. Preferably, the vehicle has an electric or hybrid engine. Of course, a side member according to the invention can be used for a vehicle with a thermal engine.

[0015] The invention will be well understood and other aspects and advantages will appear clearly on reading the following description, given by way of example with reference to the attached drawing sheet in which the figures represent:

[0016] [Fig-1] a cross-sectional view of a vehicle structure equipped with side members according to the invention;

[0017] [Fig.2] an enlarged view of detail D of [Fig.l];

[0018] [Fig.3] a view along section AA of [Fig.2];

[0019] [Fig.4] a perspective view from above of a spar reinforcement device according to the invention;

[0020] [Fig.5] a top view of a vehicle provided with a structure having side members according to the invention in a side post impact test situation;

[0021] [Fig.6] a schematic view of the reinforcement device at the time of impact during the side impact test;

[0022] [Fig.7] a schematic view of the deformation of the reinforcement device at the time of impact during the side impact test;

[0023] [Fig.8] a schematic view of the deformation of the reinforcement device in the middle of the impact during the side impact test and

[0024] [Fig.9] a view of the deformation of the reinforcement device at the end of the deformation of the reinforcement device.

[0025] Thus, as can be seen in [Fig.l], the structure S of a motor vehicle V comprises a base SB and on either side of the base SB, a side member L comprising a hollow body 1 in which a reinforcement device 2 is arranged.

[0026] The motor vehicle V is of the electric or hybrid motor type and comprises electric batteries BE enclosed in a protective casing BP housed under the underbody SB of the structure S, substantially between the side members L. The vehicle V has a longitudinal axis X from front to rear, a transverse axis Y extending between the lateral sides of the vehicle and an axis Z corresponding to the height of the vehicle along an axis normal to the ground on which the vehicle is.

[0027] As can be seen in [Fig.2], the spar L comprises a hollow body 1 having two side walls 11. These two side walls 11 extend opposite from each other.

[0028] This side member L therefore has a longitudinal axis x, and between the two side walls 11 a transverse axis y. This side member L is intended to extend between the front end and the rear end of the structure S of the vehicle V on each side of the base SB, so that its longitudinal axis x extends along the longitudinal axis X of the vehicle and one of its side walls 11 is positioned on the base side and the other side wall 11 on the outside of the structure S, the transverse axis y of the hollow body extending between the side walls 11 along the transverse axis Y of the vehicle V.

[0029] In this hollow body 1 is placed a reinforcing device 2 comprising a cellular structure and preferably a honeycomb structure 21. In the example shown in [Fig. 3], the honeycomb structure 21 comprises three rows 21a, 21b and 21c of superimposed cells or cells 210. These cells are made up of tubular elements 210 of hexagonal shape. Two plates 22, preferably made of sheet metal, are fixed, one against the first row of cells 21a and the other against the last row of cells 21c, for example by gluing or any other suitable means of fixing the plates against the walls of the cells.

[0030] The reinforcing device 2 is mounted in the hollow body 1 of the spar L so that the longitudinal axis z of the cells or alveoli formed by the hexagonal tubular elements 210 of the honeycomb structure 21 is perpendicular to the longitudinal axis x of the hollow body 1 and to the transverse axis y of the hollow body 1.

[0031] Consequently, once the side member L has been formed, it is mounted in a structure S of the vehicle V so that the side member L extends with its longitudinal axis x along the axis X of the vehicle V, its transverse axis y between the side walls 11 along the transverse axis Y of the vehicle V, so that the longitudinal axis z of the cells extends nor along the axis Z of the vehicle V comprising such a structure S and therefore normal to the ground on which the vehicle V rests.

[0032] A vehicle V comprising side members according to the invention allows better protection of the electric batteries BE mounted under the underbody SB. During a side impact known as a pole impact as shown schematically in [Fig.5] with a TCL test device, the vehicle V and more precisely, the side member L must allow the protection box BP which contains the electric batteries BE to be preserved.

[0033] As can be seen in [Fig.5], the impact of the post P generates a force more or less perpendicular to the vehicle V (between 75° and 90°) and to the side member L. [Fig.6] represents the impact when the post P comes into contact with the reinforcement device 2. As represented by the arrows, the energy of the impact propagates along the walls of the cells or alveoli from the first row 21a with maximum energy, then in the second row 21b with reduced energy on each alveolus by the distribution of the energy over more alveoli and similarly on the third row 21c. The hexagonal shape of the tubular elements 210 allows for optimal transmission of forces (represented by the arrows in [Fig.6]). The reduction in the force level is progressive, and a function of the level of intrusion of the post P.

[0034] Thus, as can be seen in [Fig.7], the resistance R of the reinforcement device 2 is symbolized by an arrow, then this resistance R decreases as the post P penetrates into the honeycomb structure 21 and the cells 210 of the honeycomb structure 21 are crushed, which dissipates the energy of the impact ([Fig.8]), until the honeycomb structure 21 is completely crushed ([Fig.9]).

[0035] This crushing of the cells allows a local deformation of the reinforcement device 2 linked in particular to the orientation of the honeycomb structure 21. The stiffness of the honeycomb structure 21 is adjustable with the number of rows of superimposed cells. By allowing the diffusion of the impact energy and by promoting local deformation, a rotational deformation of the reinforcement device 2 is avoided.

[0036] The deformation of the cells or cells and the optimized transmission of forces make it possible to dissipate the shock energy and reduce the deceleration of the BE electric batteries.

[0037] The invention advantageously makes it possible to: - reduce electrical risks resulting from battery deceleration in the event of a side collision; - control the compression of the spar; - meet security delivery objectives; and - ensure the robustness of the shock scenario.

Claims

Claims

1. Side member (L) for the structure (S) of a motor vehicle (V), comprising a hollow body (1) comprising two side walls (11) opposite each other, and a reinforcing structure (2) housed in said hollow body (1), characterized in that the reinforcing structure (2) is a cellular structure comprising at least two rows of cells defined by assembled tubular elements (210), the longitudinal axis of the tubular elements (210) extending perpendicular to the longitudinal axis of the hollow body and to the transverse axis of the hollow body between the two side walls (11).

2. Longeron (L) according to claim 1, characterized in that the tubular elements (210) are tubular elements of hexagonal shape, assembled in at least two rows (21a, 21b, 21c) to form a cellular honeycomb structure.

3. Longeron (L) according to one of claims 1 or 2, characterized in that the at least two rows of tubular elements (21a, 21b, 21c) are held between two plates (22), preferably made of sheet metal, assembled for one against the first row (21a) of tubular elements (210) and for the other against the last row (21c) of tubular elements (210).

4. Structure (S) of a motor vehicle (V), comprising two side members (L) according to one of claims 1 to 3, characterized in that each side member (L) is installed on the structure (S) of the motor vehicle (V) so as to extend along one side of the underbody (SB) with its longitudinal axis (x) extending along the longitudinal axis (X) of the vehicle, the transverse axis (y) between the two side walls (11) of the side member (L) extending along the transverse axis Y of the motor vehicle (V) and the longitudinal axis (z) of the tubular elements (210) of the reinforcement device (2) extending along the axis (Z) of the motor vehicle (V).

5. Motor vehicle (V) comprising the structure (S) according to claim 4.

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