Underbody assembly comprising a discontinuous stretcher optimized for a low-overlap frontal impact and motor vehicle comprising such an assembly

Abstract

A subframe assembly comprising a discontinuous frame optimized for a low-overlap frontal impact and a motor vehicle comprising such an assembly. The invention relates to a vehicle subframe assembly (1), comprising: - a front floor (5), - a longitudinal side member (3), laterally bordering a portion of said front floor, - a frame member (7), comprising a front portion (9) and a rear portion (11) extending longitudinally opposite said longitudinal side member (3). According to the invention, the subframe assembly (1) comprises an intermediate interface piece (13) to which is fixed, on the one hand, said front portion (9) of said frame member (7) and, on the other hand, said longitudinal side member (3) and said rear portion (11) of said frame member (7), the transverse distance (D) between said longitudinal side member (3) and said rear portion (11) being less than or equal to 25% of the width (L) of said vehicle. Figure 2

Description

Title of the invention: Underbody assembly comprising a discontinuous stretcher optimized for a low-overlap frontal impact and motor vehicle comprising such an assembly technical field

[0001] The invention relates to the field of motor vehicles, in particular to the field of passive safety of the motor vehicle to ensure protection in the event of a frontal collision.

[0002] The invention relates more particularly to a motor vehicle underbody assembly and a motor vehicle comprising such an underbody assembly. Previous technique

[0003] A motor vehicle body structure comprises a set of sheet metal structural elements providing rigidity to the motor vehicle, assembled together and forming the frame of the motor vehicle.

[0004] Reference is made to [Fig.1] showing a base set 101 of the prior art.

[0005] The body structure includes, in particular, among these sheet metal elements, a left side structure and a right side structure.

[0006] Each lateral structure comprises a set of upper and lower horizontal elements, extending substantially longitudinally relative to the body, and a set of vertical elements, extending substantially vertically relative to the body.

[0007] The lower horizontal elements include longitudinal lateral stringers 103 defining a part of the perimeter of the base assembly 101 of the body.

[0008] The body structure also includes, among these structural elements, a front floor 105.

[0009] The body structure further comprises, among these structural elements, longitudinal structural beams 107 commonly called "stretchers" and extending longitudinally relative to the vehicle.

[0010] Each stretcher 107 typically comprises a front part 109, extending on either side of a powertrain (not shown) of the vehicle, extended at the rear by a rear part 111, extending behind the front part 109 and located opposite each longitudinal side member 103, towards the inside of the front floor 105 of the vehicle and under the front floor 105 of the vehicle.

[0011] The assembly formed by the front part 109 and the rear part 111 is monobloc and defines the stretcher 107.

[0012] The base assembly 1 also includes, on either side of the stretcher 107, a first interface piece 113, fixed on one side to the stretcher 107 and on the other side to a reinforcement 115 of the central tunnel 117, and a second interface piece 119, fixed on one side to the stretcher 107 and on the other side to the longitudinal lateral stringer 103.

[0013] When the vehicle is subjected to a frontal impact, the longitudinal forces circulate in the stretcher 107, first at the level of its front part 109, as represented by the arrow 121 in [Fig.1].

[0014] The efforts are then transmitted: - partly to the reinforcement 115 of the central tunnel 117 via the first interface piece 113, as represented by arrow 123, - partly to the longitudinal side member 103 via the second interface piece 119, as represented by arrow 125, - partly to the rear part 111 of the stretcher 107, as represented by arrow 127.

[0015] This type of design allows for the proper absorption of forces during frontal collisions with an overlap of between 40% and 100% of the width of the vehicle.

[0016] However, during a small overlap frontal crash test, in which the vehicle travels at a speed of approximately 64 km / h towards a rigid obstacle with an overlap range between the obstacle and the front of the vehicle of less than 25%, the offset of the impact zone leads to a reduction of the forces absorbed by the stretcher 107 and an increase of the forces in zone A between the rear part 111 of the stretcher 107 and the longitudinal side member 103.

[0017] This considerably increases the risk of crushing in area A between the rear part 111 of the stretcher 107 and the corresponding longitudinal side member 103.

[0018] This longitudinal crushing causes significant damage to the vehicle structure and can lead, during the course of the impact, to a high risk of intrusion into the vehicle's passenger compartment and therefore injury to the occupants. Description of the invention

[0019] The present invention aims to overcome the aforementioned drawbacks, and for this purpose relates to a subframe assembly for a motor vehicle, comprising: - a front floor, - a longitudinal side member, laterally bordering at least a part of said front floor. - a stretcher, comprising a front part and a rear part extending behind said front part and extending longitudinally opposite said longitudinal lateral member, remarkable in that said subframe assembly includes an intermediate interface piece to which is fixed, on the one hand, said front part of said frame and, on the other hand, said longitudinal side member and said rear part of said frame, the transverse distance between said longitudinal side member and said rear part of said frame being less than or equal to 25% of the width of said motor vehicle.

[0020] Thus, by providing a subframe assembly comprising an intermediate interface piece to which is fixed, on the one hand, the front part of the frame and, on the other hand, the longitudinal side member and the rear part of said frame, a discontinuity is created between the front and rear parts of the frame, which allows for a more homogeneous distribution of forces in the rear part of the frame and in the longitudinal side member via the intermediate interface piece.

[0021] Also, the fact that the transverse distance between the longitudinal side member and the rear part of the stretcher is less than or equal to 25% of the width of the motor vehicle makes it possible to stiffen the area between the rear part of the stretcher and the longitudinal side member, which makes it possible to considerably limit the risk of crushing in this area.

[0022] This reduces the risk of damage to the vehicle's structure and therefore of intrusion into the vehicle's passenger compartment. In this way, the protection of the vehicle's occupants is enhanced.

[0023] According to optional features of the base assembly according to the invention: - said front part of said stretcher includes a rear end fixed to said intermediate interface piece; - said rear part of said stretcher includes a front end fixed to said intermediate interface piece; - the fixing of said front part and / or said rear part of said stretcher on said intermediate interface piece is carried out by welding; -said intermediate interface piece comprises an outer interface piece, on which is fixed said front part of said stretcher and said longitudinal lateral spar, and an inner interface piece, fixed to said outer interface piece, on which is fixed said rear part of said stretcher; - the underbody assembly includes a traction battery fixed under said front floor and adapted to power an electric motor of said motor vehicle, said traction battery having at least one lateral edge fixed on said rear part of said stretcher; - the underbody assembly includes at least one longitudinal reinforcement piece attached to said intermediate interface piece and to a central tunnel of said vehicle, said traction battery having a front edge attached to said at least one longitudinal reinforcement piece.

[0024] The invention also relates to a motor vehicle comprising a subframe assembly, remarkable in that said subframe assembly is according to the invention. Brief description of the drawings

[0025] Other features, purposes and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference should be made to the accompanying drawings in which:

[0026] [Fig-1] shows a subframe assembly of a motor vehicle of the art anterior view, seen from below.

[0027] [Fig.2] is a bottom view of a vehicle underbody assembly automobile according to the invention.

[0028] [Fig.3] is an enlargement of zone III of [Fig.2].

[0029] [Fig.4] is a bottom view of the substructure assembly according to a variant of realization.

[0030] [Fig.5] schematically shows the path of forces when the vehicle is subjected to a low overlap frontal impact. Description of the implementation methods

[0031] In the following description, elements having an identical structure or analogous functions are designated by the same reference.

[0032] By convention, and without limitation, longitudinal, vertical and transverse orientations will be adopted as indicated by the direct trihedron (L, V, T) designating the longitudinal, vertical and transverse axes of the vehicle.

[0033] In what follows, the terms "left", "right", "lower" and "upper" are understood in relation to the vehicle.

[0034] Similarly, the terms "front" and "rear" are understood in relation to the general orientation of the vehicle as taken in its normal direction of travel.

[0035] Reference is made to [Fig.2] showing a subframe assembly 1 of a motor vehicle according to the invention, seen from below, and to [Fig.3] showing an enlargement of zone III of [Fig.2].

[0036] The subframe assembly 1 includes longitudinal side rails 3 defining a part of the perimeter of the subframe assembly 1 of the body.

[0037] The base assembly 1 includes a front floor 5 defining a part of the platform of the passenger compartment of the motor vehicle.

[0038] The base assembly 1 further comprises stretchers 7 extending longitudinally relative to the vehicle.

[0039] Each stretcher 7 typically comprises a front part 9 extending on either side of a powertrain (not shown) of the vehicle, and a rear part 11 extending behind the front part 9 and extending longitudinally relative to the vehicle, opposite the longitudinal side member 3, towards the inside of the front floor 5 and under the front floor 5 of the vehicle.

[0040] According to the invention, the base assembly 1 comprises an intermediate interface piece 13 on which is fixed, on the one hand, the front part 9 of the stretcher 7 and, on the other hand, the longitudinal lateral stringer 3 and the rear part 11 of the stretcher 7.

[0041] Thus, the stretcher 7, formed by the front part 9 and the rear part 11, defines a discontinuous assembly, the front part 9 and the rear part 11 being physically separated by the intermediate interface piece 13.

[0042] Also, according to the invention, the transverse distance D between the longitudinal side member 3 and the rear part 11 of the frame 7 is less than or equal to 25% of the width L of said motor vehicle.

[0043] In the embodiment illustrated in the figures, the intermediate interface piece 13 comprises an outer interface piece 15 and an inner interface piece 17 fixed to the outer interface piece 15.

[0044] At a front end 19 of the external interface piece 15 is fixed a rear end 21 of the front part 9 of the stretcher 7.

[0045] At an outer lateral edge 23 of the outer interface piece 15 is fixed a front end 25 of the longitudinal lateral spar 3.

[0046] Thus, the arrangement of the external interface piece 15, the front part 9 of the stretcher 7 and the longitudinal lateral member 3 is such that a connection between the front part 9 of the stretcher 7 and the corresponding longitudinal lateral member 3 is ensured by the external interface piece 15.

[0047] On the inner interface piece 17, fixed to the outer interface piece 13, is fixed a front end 27 of the rear part 11 of the stretcher 7.

[0048] In the embodiment illustrated in the figures, a longitudinal reinforcement piece 31 is also fixed to a front edge 29 of the inner interface piece 17. The longitudinal reinforcement piece 31 is also fixed to a central tunnel 33 of the vehicle.

[0049] The attachment of the front part 9 and / or the rear part 11 of the stretcher 7 to the intermediate interface piece 13 can, for example, be carried out by welding.

[0050] Reference is made to [Fig.4] showing the base assembly 1 according to an alternative embodiment, seen from below.

[0051] The vehicle may be electric with a battery (so-called "BEV" motor vehicle, an Anglo-Saxon acronym for "Battery Electric Vehicle"), or of the hybrid type comprising a thermal engine and an electric motor which operate simultaneously or alternately in such a way as to reduce the power consumed by the motor vehicle, for example a plug-in hybrid vehicle (so-called "PHEV" motor vehicle, an English acronym for "Plug-in Hybrid Electric Vehicle").

[0052] The vehicle includes a traction battery 35 fixed under the front floor 5 of the underbody assembly 1, powering the vehicle's electric motor.

[0053] In the illustrated embodiment, the traction battery 35 has a front edge 37 fixed to the longitudinal reinforcement pieces 31.

[0054] Advantageously, the traction battery 35 has lateral edges 39, each being fixed to the corresponding rear part 11 of the stretcher 7. Thus, the rear part 11 of the stretcher 7 provides the function of lateral support for fixing the traction battery 35, which makes it possible to avoid the transmission of forces on the traction battery 35 in the event of a low overlap frontal impact, thereby limiting electrical risks and consequently the risks of fire of the traction battery 35.

[0055] The attachment of the traction battery 35 to the longitudinal reinforcement parts 31 and / or to the rear parts 11 of the shafts 7 can for example be carried out by screwing.

[0056] Reference is made to [Fig.5] which schematically shows the path of forces when the vehicle is subjected to a low overlap frontal impact.

[0057] When the vehicle is subjected to a low-overlap frontal impact against an obstacle 40, the longitudinal forces circulate in the front part 9 of the frame 7, as represented by the arrows 4L

[0058] The forces are then transmitted from the front part 9 of the stretcher 7, in a substantially uniform manner, to the longitudinal side member 3 and to the rear part 11 of the stretcher 7, via the outer interface piece 15 and via the inner interface piece 17 of the intermediate interface piece 13, as represented by the arrows 43.

[0059] Another part of the forces is also transmitted from the front part 9 of the stretcher 7 to the longitudinal reinforcement piece 31, via the inner interface piece 17 of the intermediate interface piece 13, as represented by the arrows 45.

[0060] As will be understood, the present invention is not limited to the embodiments of this motor vehicle underbody assembly and of this motor vehicle comprising such an underbody assembly, described above solely by way of illustrative examples, but on the contrary it encompasses 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. Underbody assembly (1) of a motor vehicle, comprising: - a front floor (5), - a longitudinal side member (3), laterally bordering at least a portion of said front floor (5), - a frame (7), comprising a front portion (9) and a rear portion (11) extending behind said front portion (9) and extending longitudinally opposite said longitudinal side member (3), characterized in that said underbody assembly (1) comprises an intermediate interface piece (13) on which is fixed, on the one hand, said front portion (9) of said frame (7) and, on the other hand, said longitudinal side member (3) and said rear portion (11) of said frame (7), the transverse distance (D) between said longitudinal side member (3) and said rear portion (11) of said frame (7) being less than or equal to 25% of the width (L) of said motor vehicle.

2. Base assembly (1) according to claim 1, characterized in that said front part (9) of said stretcher (7) has a rear end (21) fixed to said intermediate interface piece (13).

3. Base assembly (1) according to any one of claims 1 or 2, characterized in that said rear part (11) of said stretcher (7) has a front end (27) fixed to said intermediate interface piece (13).

4. Base assembly (1) according to any one of claims 1 to 3, characterized in that the attachment of said front part (9) and / or said rear part (11) of said stretcher (7) on said intermediate interface piece (13) is carried out by welding.

5. Base assembly (1) according to any one of claims 1 to 4, characterized in that said intermediate interface piece (13) comprises: - an external interface piece (15), on which is fixed said front part (9) of said stretcher (7) and said longitudinal lateral side member (3), - an inner interface piece (17), fixed to said outer interface piece (15), on which said rear part (11) of said stretcher (7) is fixed.

6. Underbody assembly (1) according to any one of claims 1 to 5, comprising a traction battery (35) fixed under said front floor (5) and adapted to power an electric motor of said motor vehicle, characterized in that said traction battery (35) comprises at least one lateral edge (39) fixed on said rear part (11) of said stretcher (7).

7. Underbody assembly (1) according to claim 6, characterized in that it comprises at least one longitudinal reinforcement piece (31) attached to said intermediate interface piece (13) and to a central tunnel (33) of said vehicle, and in that said traction battery (35) comprises a front edge (37) attached to said at least one longitudinal reinforcement piece (31).

8. Motor vehicle comprising a subframe assembly (1), characterized in that said subframe assembly (1) is according to any one of claims 1 to 7.

Images