EP4291468A1

EP4291468A1 - Motor vehicle floor with offset side rails for traction battery casing

Info

Publication number: EP4291468A1
Application number: EP22705419.4A
Authority: EP
Inventors: Patrick Viry; Claire Legros; Romain Grosset; Stephane Cadet
Original assignee: Stellantis Auto SAS
Current assignee: Stellantis Auto SAS
Priority date: 2021-02-10
Filing date: 2022-01-14
Publication date: 2023-12-20
Also published as: FR3119597A1; WO2022171944A1; FR3119597B1

Abstract

The invention relates to a motor vehicle structure (2) comprising a floor (4); two front beams (10.1, 10.2) extending longitudinally from the front of the floor under a front portion of the floor (4); two lateral beams (12.1, 12.2) extending longitudinally under the floor (4) from the front portion of the floor; wherein each of the two lateral beams (12.1, 12.2) has an exterior longitudinal overlap with one of the two front beams (10.1, 10.2) that is adjacent, and is secured to the front beam by a transverse casing (14.1, 14.2).

Description

DESCRIPTION

TITLE: MOTOR VEHICLE FLOOR WITH DEPORTED STRETCHERS FOR TRACTION BATTERY BOX

Technical area

The present invention claims the priority of French application 2101277 filed on February 10, 2021, the content of which (text, drawings and claims) is incorporated herein by reference.

The invention relates to the technical field of motor vehicles, more particularly to the structure of motor vehicles.

Prior technique

The development of motor vehicles with electric traction, pure or hybrid, is experiencing significant growth. This development requires the housing of electrical energy accumulators, more commonly referred to as traction batteries, on the structure of motor vehicles. It is common to house these traction batteries under the floor of the motor vehicle structure, by means of a box. The traction batteries have a significant mass to the point of modifying the behavior of the structure of the motor vehicle during shocks. In particular, the frontal impact tests, in particular against a mobile deformable barrier with partial overlap (designated by the Anglo-Saxon expression "Mobile Progressive Deformable Barrier" according to the EURO-NCAP standard), and against a rigid and fixed barrier on the the entire width of the vehicle (designated by the Anglo-Saxon expression "Full Width Rigid Barrier" according to the EURO-NCAP standard), impose significant deformation stresses at the level of the two longitudinal beams extending from the engine compartment to under the floor and commonly referred to as stretchers. The mass added by a traction battery box under the floor deteriorates behavior in the event of a frontal impact test. In addition, the position of the stretchers under the floor is not favorable to the placement of the traction batteries in that it is desirable to place the traction batteries directly under the floor.

The published patent document FR 3038574 A1 addresses the problem of frontal impact test with partial overlap corresponding to 25% of the width of the vehicle, where the stretchers participate little or not in the recovery of effort and deformation. It provides a solution to provide a reinforcement mechanically connecting each of the side rails, also referred to as sills, to the longitudinal beam or adjacent stretcher located under the floor, and this at the front of the floor. This solution is particularly interesting for impacts with 25% recovery but fails to provide a solution to frontal impacts with greater recovery involving at least one of the stretchers, in the presence of a large mass under the floor.

Disclosure of Invention

The aim of the invention is to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the object of the invention is to propose a vehicle structure which is compatible with frontal impact tests in the presence of traction batteries under the floor and which favors the placement of said batteries under the floor.

The subject of the invention is a motor vehicle structure, comprising a floor; two front beams extending longitudinally from the front of the floor under a front part of the floor; two side beams extending longitudinally under the floor from the front part of said floor; remarkable in that each of the two side beams has an outer longitudinal overlap with one of the two front beams which is adjacent, and is fixed to said front beam by a transverse box.

Outer longitudinal overlap means, in addition to the longitudinal overlap, that the side beam is located, transversely, outside the corresponding front beam.

According to an advantageous embodiment of the invention, each of the two transverse boxes comprises at least one leg and/or walls in contact with each of the corresponding side beam and front beam.

According to an advantageous embodiment of the invention, each of the two transverse boxes forms, between the front beam and the corresponding side beam, a transverse profile of U-section with, at the ends of the U-section, flanges for fixing against the floor. According to an advantageous embodiment of the invention, the transverse profile of each of the transverse boxes extends along a main direction perpendicular to a longitudinal direction of the motor vehicle structure.

According to an advantageous embodiment of the invention, the U-shaped section of the profile of each of the transverse boxes has a width of at least 100 mm.

According to an advantageous embodiment of the invention, each of the two transverse boxes comprises at an inner end a wall with a stepped cross section matching the corresponding front section and ending in a wing fixed against the floor.

According to an advantageous embodiment of the invention, each of the two transverse boxes comprises at a rear end a wall with a stepped cross-section matching a rear end of the corresponding front profile and ending in a wing fixed against the floor. This wall and this wing are advantageously formed by an inward extension of the transverse profile formed by the transverse box.

According to an advantageous embodiment of the invention, each of the two transverse boxes extends between the front beam and the corresponding side beam over a length of at least 150 mm.

According to an advantageous embodiment of the invention, the motor vehicle structure further comprises, in an extension of each of the two front sections, a fixing lug for an electrical energy storage box, attached to or formed by the box corresponding transverse.

The invention also relates to a motor vehicle comprising a motor vehicle structure with a floor; and an electrical energy accumulator box arranged under the floor; remarkable in that the motor vehicle structure is according to the invention, the box extending transversely between the two side sections, directly at the rear of the two transverse boxes.

The measures of the invention are advantageous in that they allow the motor vehicle structure to house electrical energy accumulators, or traction batteries, while maintaining satisfactory behavior in the event of a frontal impact, and this in a economic. More particularly, the spacing more tall of the two side beams makes it possible to house the box in question between said two side beams, against the floor, limiting the vertical bulk and allowing the motor vehicle to retain a conventional ground clearance for motor vehicles with fossil fuel traction.

Brief description of the drawings

[Fig 1] is a schematic view from below of a motor vehicle structure, according to the invention;

[Fig 2] is a detail representation of an embodiment according to the invention of the connection between the front profile and the side profile of Figure 1;

detailed description

FIG. 1 schematically represents, in bottom view, a motor vehicle structure according to the invention.

The motor vehicle structure 2 comprises, conventionally, a floor 4 made up of a left half 4.1 and a right half 4.2, interconnected by a central tunnel 6. A lateral beam 8, also designated sill, is arranged at each of the two side edges of the floor 4.

The motor vehicle structure 2 also comprises two front beams 10.1 and 10.2 extending from the front of the floor 4 under a front part of said floor 4. These two front beams 10.1 and 10.2 are also designated front stretchers by analogy with the stretchers of a stretcher forming two generally parallel longitudinal beams and optionally profiled vertically at their ends. More specifically, the two front beams 10.1 and 10.2 extend from an engine compartment or more generally a front compartment (in the absence of an engine) where they support a front bumper crossmember via compression-deformable boxes (“crashboxes”) , these elements not being shown, however. In known manner, the front beams 10.1 and 10.2 may have a bent profile in a vertical and longitudinal plane, so as to move from a higher height in the front or engine compartment to a lower height under the floor 4. As can be seen in Figure 1, each of the two front beams 10.1 and 10.2 has a rectilinear profile in a horizontal plane parallel to the floor 4 up to its rear end 10.1.1 and 10.2.1 on a front part of the floor 4. The motor vehicle structure 2 also includes two side beams

12.1 and 12.2, also referred to as side stretchers. As can be seen in Figure 1, the two side beams 12.1 and 12.2 extend parallel under the floor 4 from the front part of said floor to a rear part (not shown). The two side beams 12.1 and 12.2 have a spacing greater than the spacing of the two front beams 10.1 and 10.2. Thus, the left side beam 12.1 is located laterally more outward than the left front beam 10.1, and similarly, the right side beam 12.2 is located laterally more outward than the right front beam 10.2. It can be observed that the side beams 12.1 and 12.2 can each have a generally rectilinear profile in a horizontal plane parallel to the floor 4. They have a longitudinal overlap with the front beams 10.1 and 10.2. More specifically, the front ends 12.1.1 and 12.2.1 of each of the two side beams 12.1 and 12.2 are further forward than the rear ends 10.1.1 and

10.2.1 of the front beams 10.1 and 10.2. The overlap is advantageously greater than 200 mm. It is also advantageously less than 500 mm.

The motor vehicle structure 2 further comprises two transverse boxes 14.1 and 14.2 providing a rigid connection between, on the one hand, the front beams 10.1 10.2 and, on the other hand, the side beams 12.1 and 12.2, respectively. The left 14.1 and right 14.2 transverse boxes are shown schematically in Figure 1, it being understood that many implementations are possible. Each of the two transverse boxes 14.1 and 14.2 extends between the front beam 10.1 and 10.2 and the corresponding side beam 12.1 or 12.2 over a length of at least 150 mm. Each of the transverse boxes 14.1 and 14.2 comprises lugs and/or walls in contact with each of the corresponding side beam and front beam, so as to ensure a sufficiently rigid connection. Each of the transverse boxes 14.1 and 14.2 is also fixed directly to the floor 4. Each of the transverse boxes 14.1 and 14.2 forms a short transverse beam having a quadratic bending moment in a horizontal plane parallel to the floor which is advantageously greater than or equal to each of the moments quadratics in bending in the same plane of the front beams 10.1 and 10.2 and the side beams 12.1 and 12.2. The transverse boxes

14.1 and 14.2 extend in a transverse direction advantageously perpendicular to the longitudinal direction or forming with the perpendicular direction an angle of less than 30°, preferably 20°, more preferably 10°.

The construction of the front and side beams and of the transverse boxes which has just been described provides a space 16 of generally rectangular shape particularly suitable for receiving a traction battery box (not shown as such but corresponding to the space 16). This space 16 can extend laterally as far as the side beams 12.1 and 12.2, these then being able to serve as anchoring zones for the traction battery box. However, depending on the construction of the traction battery box and the height of the side beams 12.1 and 12.2, it is possible that the box in question extends laterally beyond the side beams 12.1 and 12.2.

The transverse boxes 14.1 and 14.2 can also form a zone for fixing the traction battery box or form a zone for anchoring such a fixing.

The construction of the front and side beams and of the transverse boxes which has just been described thus allows good recovery by the side beams 12.1 and 12.2 of the essentially longitudinal compression forces, in the event of a frontal impact, and thus to preserve the space 16 located directly aft of the front beams 10.1 and 10.2.

Figure 2 is a detail view of the left transverse box 14.1 and portions of the front beam 10.1 and the side beam 10.2 in contact with the box in question. The transverse box 14.1 is advantageously formed by a cut and stamped sheet metal.

The transverse box 14.1 may comprise a central part forming a transverse section 14.1.1 extending transversely between the front beam 10.1 and the side beam 12.1, in this case of U-section with, at the ends of the U-section, wings 14.1.2 fixed against the floor 4, more precisely the left half 4.1 of the floor 4. The U-shaped section advantageously has a width of at least 100 mm.

The transverse box 14.1 may also include a tab 14.1.3 covering the side beam 12.1. This leg 14.1.3 is in this case in the extension of the central part of the U-section of the main portion 14.1.1. It can be observed that this tab 14.1.3 transversely covers at least 80% of the adjacent face of the side beam 12.1 and extends longitudinally over at least 80% of the extent of the central part of the U-section of the transverse profile 14.1.1.

The transverse box 14.1 may also include at an inner end a wall with a stepped cross section 14.1.4 marrying the corresponding front section 10.1 and ending in a wing 14.1.5 fixed against the floor 4, more precisely the left half 4.1 of the floor 4. The stepped wall 14.1.4 can extend longitudinally beyond the transverse profile 14.1.1, in particular forwards. For this purpose, this extension may have a U-section with a flange 14.1.6 opposite the flange 14.1.5 at the end of the stepped section at the level of the transverse section 14.1.1. This construction allows a particularly rigid and efficient connection in bending in a plane parallel to the floor comprising the front and side beams and the transverse box.

Advantageously, the transverse box 14.1 comprises at a rear end a wall with a stepped cross section matching the rear end of the corresponding front section 10.1 and ending in a wing fixed against the floor 4. This wall and this wing are in the occurrence in the inward extension of the rear part of the U-section of the transverse profile 14.1.1. This wall and this wing thus form a retainer for the corresponding front profile 10.1.

A fixing lug 18 of the traction battery box can be formed by or on the transverse box 14.1. In the case of Figure 2, this fixing lug 18 is formed by a stamping attached to the transverse box 14.1.

It is understood that what has just been described in relation to FIG. 2, corresponding to the left side of the motor vehicle structure, applies identically by symmetry to the right side.

Claims

[Claim 1.] Motor vehicle structure (2), comprising:

- a floor (4);

- two front beams (10.1, 10.2) extending longitudinally from the front of the floor under a front part of the floor (4);

- two side beams (12.1, 12.2) extending longitudinally under the floor (4) from the front part of said floor; characterized in that each of the two side beams (12.1, 12.2) has an outer longitudinal overlap with one of the two front beams (10.1, 10.2) which is adjacent, and is fixed to the said front beam by a transverse box (14.1,

14.2).

[Claim 2.] Motor vehicle structure (2), according to claim 1, in which each of the two transverse boxes (14.1,

14.2) comprises at least one leg (14.1.3) and/or walls (14.1.4) in contact with each of the corresponding side beam (12.1, 12.2) and front beam (10.1, 10.2).

[Claim 3.] Motor vehicle structure (2), according to one of claims 1 and 2, in which each of the two transverse boxes (14.1, 14.2) forms between the front beam (10.1, 10.2) and the side beam ( 12.1,

12.2) corresponding to a transverse profile (14.1.1) of U-section with, at the ends of the U-section, fixing flanges (14.1.2) against the floor (4).

[Claim 4.] Motor vehicle structure (2), according to claim 3, in which the transverse profile (14.1.1) of each of the transverse boxes (14.1, 14.2) extends in a main direction perpendicular to a longitudinal direction of the motor vehicle structure.

[Claim 5.] Motor vehicle structure (2), according to one of Claims 3 and 4, in which the U-shaped section of the transverse section (14.1.1) of each of the transverse boxes (14.1, 14.2) has a width at least 100 mm. [Claim 6.] Motor vehicle structure (2), according to one of claims 1 to 5, in which each of the two transverse boxes (14.1, 14.2) comprises at an inner end a wall with a stepped cross section (14.1 .4) marrying the corresponding front profile (10.1, 10.2) and ending in a wing (14.1.5) fixed against the floor (4).

[Claim 7.] Motor vehicle structure (2), according to one of claims 1 to 6, in which each of the two transverse boxes (14.1, 14.2) comprises at a rear end a wall with a stepped cross-section matching a rear end of the corresponding front profile and ending in a wing (14.1.2) fixed against the floor (4).

[Claim 8.] Motor vehicle structure (2), according to one of claims 1 to 7, in which each of the two transverse boxes (14.1, 14.2) extends between the front beam (10.1, 10.2) and the beam side (12.1, 12.2) corresponding over a length of at least 150 mm.

[Claim 9.] Motor vehicle structure (2), according to one of claims 1 to 8, further comprising, in an extension of each of the two front sections (10.1, 10.2) a fixing lug (18) for a box of electrical energy accumulators, attached to or formed by the corresponding transverse box (14.1, 14.2).

[Claim 10.] Motor vehicle comprising:

- a motor vehicle structure (2) with a floor (4); and

- an electrical energy accumulator box arranged under the floor (4); characterized in that the motor vehicle structure (2) is according to one of claims 1 to 9, the box extending transversely between the two side sections (12.1, 12.2), directly at the rear of the two transverse boxes ( 14.1, 14.2).