Underbody for hybrid or electric vehicles with reinforced side rails

Abstract

The invention relates to a body underbody (2) for a hybrid or electric motor vehicle, comprising a floor (3) extending transversely between two lateral underbody rails (10) and at least one seat cross member (8, 9) fixed to the top of said floor and extending transversely between the two said lateral rails to which it is fixed; each said lateral rail comprising an elongated hollow body of closed cross section and consisting of an internal part of the rail (12) and an external part of the rail fixed to each other, each said lateral rail also comprising an internal reinforcement extending longitudinally along and inside its hollow body; characterized in that each said lateral rail further comprises an external reinforcement (15) fixedly attached to the outer face of a zone of said internal part of the rail located opposite said at least one seat cross member.Figure to be published with the abbreviation: Fig. 1.

Description

Title of the invention: Body chassis for hybrid or electric vehicles equipped with reinforced side rails technical field

[0001] The present invention relates generally to the body chassis of hybrid or electric motor vehicles equipped with a propulsion battery. It relates in particular to such a body chassis provided with reinforced side members. Previous technique

[0002] A hybrid or electric motor vehicle comprises, for its operation, an electric motor and optionally a combustion engine coupled to said electric motor. At least one propulsion battery is also provided in such a vehicle to power the electric motor.

[0003] The body underbody of such a hybrid or electric vehicle classically comprises a front floor extending longitudinally between the front apron and the rear floor, and transversely between two lateral underbody rails.

[0004] Such a lateral underbody spar generally comprises an elongated hollow body with a closed cross-section and consisting of an internal part of the spar and an external part of the spar fixed to each other.

[0005] The body underbody also includes at least one front seat cross member fixed to the top of the front floor and extending transversely between the two lateral underbody rails under the first row of seats.

[0006] The side underbody rails and the front seat crossmember(s) contribute to the rigidity of the body underbody and, in the event of a side impact, effectively limit the dynamic intrusion of the doors into the passenger compartment of the vehicle.

[0007] Indeed, when such a lateral impact occurs, a large part of the resulting forces pass through these elements which are dimensioned accordingly.

[0008] During a side impact with a pole, and more particularly when this impact occurs at the level of a propulsion battery of a hybrid or electric vehicle, even a slight dent in the corresponding side member caused by the crushing of the base crossmember(s) can lead to deformation of the propulsion battery and deterioration of some of its electrochemical cells, resulting in a risk of electrocution or chemical burns for the passengers.

[0009] In order to reduce the stresses experienced by the bearing crossmember(s) so as to limit the compression of the longeron during such a lateral impact, it is known in particular from document FR 3 081418Al, to provide, inside the hollow body of each lateral subframe rail, an internal reinforcement extending longitudinally along this hollow body.

[0010] Such an internal reinforcement is intended to crash against the internal part of the hollow body of the spar so as to absorb a significant portion of the impact energy in order to limit the forces transmitted to the seat cross members.

[0011] Unfortunately, the side impact test protocols show that this internal reinforcement only partially collapses due to the excessive deformation of the internal part of the hollow body of the longeron caused by the corresponding end(s) of the seat cross members. Description of the invention

[0012] The present invention therefore aims to improve the situation.

[0013] To this end, it proposes a body subframe for a motor vehicle of the type hybrid or electric, comprising a floor extending transversely between two lateral subframe members and at least one bearing cross member fixed on top of said floor and extending transversely between the two said lateral members to which it is fixed; each said lateral member comprising an elongated hollow body of closed cross section and consisting of an internal part of member and an external part of member fixed to each other, each said lateral member also comprising an internal reinforcement extending longitudinally along and inside its hollow body; characterized in that each said lateral stringer further comprises an external reinforcement fixedly attached to the external face of an area of ​​said internal part of stringer located opposite said at least one bearing cross member.

[0014] The addition of such an external reinforcement of the spar makes it possible, in the event of a side impact, to limit the deformation of the internal part of the hollow body of the spar caused by the corresponding end(s) of the seat cross members, so as to optimize the crushing of the internal reinforcement against this internal part and to maximize the absorption of the energy of this impact by this internal reinforcement.

[0015] The residual forces transmitted to the base crossbeam(s) are thus very clearly reduced, which makes it possible to considerably limit the crushing of this or these crossbeams and therefore the risks of deformation of the vehicle's propulsion battery.

[0016] Furthermore, the fact that this external reinforcement extends only over a portion of the inner part of the side member helps to limit the increase in mass of the lateral side member. The invention also makes it possible to maintain the same part number for the inner and outer parts of the side member for all versions of the same vehicle model, whether or not equipped with a propulsion battery (the side members). (non-hybrid or electric versions lack the interior and exterior reinforcements).

[0017] According to preferred characteristics of said body subframe according to the invention: - the internal part of each said lateral side member has in cross-section a horizontal U-shaped profile and comprises a lateral web as well as two upper and lower flanges extending opposite said floor from this lateral web, said external reinforcement of each said lateral side member having in cross-section an inverted L-shaped profile and comprising a lateral flange affixed against the outer face of said lateral web and an upper flange extending opposite said floor from this lateral web by being affixed against the outer face of said upper flange; - each lateral end of said at least one seat cross member is fixed to the corresponding lateral side member by means of tabs projecting transversely from said end and welded to the upper flange of the external reinforcement of this side member;- the lateral wing of each of said external reinforcements extends vertically on either side of said floor over at least the greater part of the height of the lateral web of the internal part of the corresponding longeron; - the external reinforcement of each said lateral stringer has cutouts made at certain respective areas of the internal part of this stringer provided with fixing holes; - the external reinforcement of each said lateral stringer is obtained from a sheet of double-phase steel metal sheet with a thickness between 1.5 and 2.5 millimeters; - the internal reinforcement of each said lateral stringer is made up of a metal profile obtained by extrusion; - the internal reinforcement of each said lateral longitudinal member has a honeycomb structure composed of an outer shell and a network of internal partitions dividing the internal volume of this shell; and / or - said base comprises two said foundation crossbeams spaced longitudinally apart from each other.

[0018] The invention also relates, in a second aspect, to a motor vehicle comprising such a body underbody. Brief description of the drawings

[0019] The description of the invention will now be continued by a detailed description of an example embodiment, given below by way of illustration but not limitation, with reference to the accompanying drawings, on which: - [Fig.1] represents a partial perspective view of a body structure of a hybrid or electric type vehicle comprising a body underbody according to the invention equipped with two lateral longitudinal members bordering laterally a front floor; - [Fig.2] is an exploded perspective view of one of the two side rails of the body underbody of [Fig.1]; - [Fig. 3] shows a perspective view from another angle of the side member of [Fig. 2] in its assembled configuration; and - [Fig.4] is a perspective view of the external reinforcement of one of the two lateral longitudinal members of the body underbody of [Fig.1]. Description of the implementation methods

[0020] Fig. 1 is a partial view of a body structure 1 of a hybrid or electric type motor vehicle.

[0021] A direct orthogonal frame of reference XYZ is defined with respect to this vehicle, comprising three axes perpendicular in pairs, namely: - a horizontal longitudinal axis X, parallel to the ground and oriented according to the general direction of movement of the vehicle; - a horizontal transverse axis Y, also parallel to the ground and perpendicular to the X axis; and - a vertical axis Z, perpendicular to the ground as well as to the horizontal XY plane.

[0022] In the following description, and by convention, the terms "lower," "upper," "front," and "rear" shall be understood in relation to the overall orientation of the vehicle. The terms "lower" and "low" shall indicate a closer proximity to the ground in the vertical direction than the terms "upper" or "high." The term "front" shall indicate a forward-facing position of a vehicle in the horizontal direction, and the term "rear" shall indicate a rear-facing position of a vehicle in the same horizontal direction.

[0023] The terms "external" and "internal" will be used to define the relative position of an element with reference to the longitudinal median axis of the vehicle. The element closest to this axis will thus be described as internal, as opposed to the other element further from this same axis, which will be described as external.

[0024] Furthermore, the term "substantially" will be used to indicate that a slight deviation is permitted from a predetermined nominal position or arrangement, while remaining within the scope of the invention. For example, "substantially vertical" will indicate that a deviation of approximately 20° from a strictly perpendicular orientation is permitted within the scope of the invention.

[0025] With reference to [Fig. 1], the body structure 1 comprises a body underframe 2 according to the invention including a front floor 3 extending longitudinally t between the front apron 4 and the rear floor 5 intended to support the rear seats (e.g., "second row seats"), and transversely between two lateral underbody rails 10 (only the left lateral rail 10 being visible on this [Fig.1]).

[0026] A middle pillar 6 separating the front and rear side doors connects each side rail 10 to a corresponding side roof frame 7 of the vehicle (only the left middle pillar 6 and a portion of the left side roof frame 7 are shown in [Fig.1]).

[0027] A propulsion battery not visible on this [Fig.1] is further located under the front floor 3 of the vehicle between the two lateral underbody rails 10.

[0028] The body base 2 also includes two metal seat cross members 8, 9 spaced longitudinally apart from each other and fixed to the top of the front floor 3 extending transversely between the two lateral side rails of the base 10 to which they are also fixed.

[0029] The first seat crossbeam 8 is located directly above the two middle feet 6 while the second 9 is located in front of the latter.

[0030] Having an inverted U-shaped section (i.e. open downwards), these front seat cross members 8, 9 constitute anchoring supports for the seat frames of the front seats by means of two pairs of slides not shown, each comprising, in a conventional manner, a lower rail whose two ends are respectively fixed on one and the other of these cross members 8, 9 and an upper rail mounted to slide on the lower rail and rigidly linked to a corresponding lower lateral part of the seat frame of a corresponding seat.

[0031] With reference to [Fig.2], each lateral base rail 10 has an elongated hollow body 11 with a closed cross-section delimiting an interior cavity with a substantially square cross-section, this hollow body being made up of an internal part of rail 12 and an external part of rail 13.

[0032] These internal 12 and external 13 parts forming the hollow body 11 are each obtained by stamping from one or more sheets of metal sheet, preferably in double-phase steel and advantageously having a thickness between 1.2 and 1.4 millimeters.

[0033] The inner portion 12 of each longitudinal member 10 has a substantially U-shaped cross-section, the opening of which is turned away from the front floor 3 of the vehicle to which it is attached. This inner portion 12 comprises a substantially vertical lateral web 12A and two upper flanges 12B and lower flanges 12C extending substantially horizontally away from the front floor 3 from this lateral web 12A. The upper flange 12B and lower flange 12C each extend away from the lateral web 12A by means of a rebate. upper junction 12D and by a lower junction rebate 12E folded outwards from the U.

[0034] Similar in construction to the inner part, the outer part 13 of each longitudinal member 10 has a cross-section that is substantially in the shape of a horizontal U, the opening of which is directed towards the front floor 3 of the vehicle. This outer part 13 comprises a substantially vertical lateral web 13A and two upper flanges 13B and lower flanges 13C extending substantially horizontally towards the front floor 3 from this lateral web 13A. The upper flanges 13B and lower flanges 13C each extend on the opposite side of the lateral web 13A, respectively, by means of an upper joining rebate 13D and a lower joining rebate 13E, folded outwards towards the outside of the U.

[0035] The internal 12 and external 13 parts of each longitudinal member 10 are fixed to each other by welding their upper joining rebates 12D, 13D and by welding their lower joining rebates 12E, 13E.

[0036] Each longitudinal member 10 also includes an internal reinforcement 14 extending longitudinally along and inside said hollow body 11 to which it is rigidly fixed.

[0037] This internal reinforcement of the longitudinal member 14 is in this case made up of a metal profile preferably obtained by extrusion and advantageously made of aluminum or an aluminum alloy.

[0038] Having a cross-section of substantially rectangular or square shape and occupying most of the internal volume of the hollow body 11, the internal reinforcement of the stringer 14 has a honeycomb structure composed of an outer envelope 14A of rectangular section and a network of internal partitions 14B gridding the internal volume of this envelope 14A.

[0039] Each longeron 10 further includes an external reinforcement 15 fixedly attached to the outer face of a central area of ​​the internal part 12 of the hollow body 11 of the longeron 10, located opposite the corresponding lateral ends of the two front seat cross members 8, 9.

[0040] The external reinforcement 15 of each longitudinal member 10 is obtained by cold stamping from a sheet of metal preferably made of double-phase steel (for example, DP 780) and advantageously having a thickness between 1.5 and 2.5 millimeters.

[0041] Having in cross-section an inverted L-shaped transverse profile, each external reinforcement 15 comprises a substantially vertical lateral wing 15A affixed against the outer face of the lateral web 12A of the inner part 12 of the hollow body 11 of the corresponding longeron 10, as well as an upper wing 15B extending substantially horizontally opposite the front floor 3 from this lateral web 15A and being affixed against the outer face of the upper sole 12B of this internal part 12.

[0042] Advantageously and as illustrated by [Fig.3], the lateral wing 15A of each said external reinforcement 15 extends vertically on either side of the front floor 3 over at least the greater part of the height of the lateral web 12A of the internal part 12 of the corresponding longeron 10.

[0043] Its upper wing 15B extends transversely over at least the greater part of the upper flange width 12B of the inner part 12 of the corresponding spar 10.

[0044] As illustrated by [Fig.1], each lateral end of the seat cross members 8, 9 is fixed to the corresponding lateral stringer 10 by means of tabs 8A, 9A projecting transversely from said end and welded to the upper flange 15B of the outer reinforcement 15 of this lateral stringer 10.

[0045] As illustrated by figures 3 and 4, the external reinforcement 15 of each side member 10 advantageously has a number of cutouts 16 made at certain respective areas of the internal part 12 of this side member 10 provided with holes 17 for the attachment by clipping of electrical harness fastener clips not shown.

[0046] According to alternative embodiments not shown, the body base can be shaped differently and may, for example, include only one cross member.

[0047] Many other variants are also possible and it should be recalled in this regard that the invention is not limited to the embodiments described and represented, but also encompasses all the variants of execution within the reach of a person skilled in the art.

Claims

Demands

1. Body underbody (2) for a hybrid or electric motor vehicle, comprising a floor (3) extending transversely between two side underbody members (10) and at least one seat cross member (8, 9) fixed to the top of said floor (3) and extending transversely between the two said side members (10) to which it is fixed; each said side member (10) comprising an elongated hollow body (11) of closed cross-section and consisting of an inner part of a member (12) and an outer part of a member (12) fixed to each other, each said side member (10) also comprising an internal reinforcement (14) extending longitudinally along and inside its hollow body (11);characterized in that each said lateral stringer (10) further comprises an external reinforcement (15) fixedly attached against the external face of an area of ​​said internal part of stringer (12) located opposite said at least one seat cross member (8, 9); and in that the internal part (12) of each said lateral stringer (10) has in section a horizontal U-shaped profile and comprises a lateral web (12A) as well as two upper (12B) and lower (12C) flanges extending opposite said floor (3) from this lateral web (12A), said external reinforcement (15) of each said lateral stringer (10) having in section an inverted L-shaped profile and comprising a lateral wing (15A) affixed against the external face of said lateral web (12A) as well as an upper wing (15B) extending opposite said floor (3) from this lateral web (15A) by being affixed against the external face of said upper flange (12B).;

2. Body underbody (2) according to claim 1, characterized in that each lateral end of said at least one seat cross member (8, 9) is fixed to the corresponding lateral side member (10) by means of tabs (8A, 9A) projecting transversely from said end and welded to the upper flange (15B) of the external reinforcement (15) of this side member (10).

3. Body underbody (2) according to claim 1 or 2, characterized in that the lateral wing (15A) of each said external reinforcement (15) extends vertically from paH and other of said floor (3) over at least most of the height of the lateral web (12A) of the inner part (12) of the corresponding spar (10).

4. Body underbody (2) according to any one of claims 1 to 3, characterized in that the external reinforcement (15) of each said side member (10) has cutouts (16) made at certain respective areas of the internal part (12) of this side member (10) provided with fixing holes (17).

5. Body underbody according to (2) any one of claims 1 to 4, characterized in that the external reinforcement (15) of each said side member (10) is obtained from a sheet of double-phase steel metal sheet having a thickness between 1.5 and 2.5 millimeters.

6. Body base (2) according to any one of claims 1 to 5, characterized in that the internal reinforcement (14) of each said side member (10) is made up of a metal profile obtained by extrusion.

7. Body base (2) according to any one of claims 1 to 6, characterized in that the internal reinforcement (14) of each said side member (10) has a honeycomb structure composed of an outer envelope (14A) and a network of internal partitions (14B) dividing the internal volume of this envelope (14A).

8. Body base (2) according to any one of claims 1 to 7, characterized in that it comprises two said seat cross members (8, 9) spaced longitudinally apart from each other.

9. Motor vehicle comprising a body underbody (2) according to any one of claims 1 to 8.

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