A subframe assembly incorporating a dual-function load-bearing structure under the floor in the event of a side collision, and a motor vehicle incorporating such an assembly.

Abstract

A subframe assembly comprising a dual-function load-bearing structure under the floor in the event of a side collision, and a motor vehicle comprising such an assembly. The invention relates to a subframe assembly (1) of a motor vehicle, comprising: - a front floor (5), comprising a front portion (7) and a central portion (9), said front and central portions being connected by welding, - a longitudinal side member (3), bordering a portion of said front floor, - a rear frame member (15), opposite said longitudinal side member, - a set of transverse stiffeners (25) connecting said longitudinal side member to said rear frame member, - a longitudinal reinforcement piece (17) extending longitudinally over the front portion (7) of said front floor.According to the invention, the base assembly (1) comprises a transverse reinforcement piece (27), extending transversely over the front part (7) of said front floor, connecting said rear frame (15) to said longitudinal reinforcement piece. Figure 2.

Description

Title of the invention: A subframe assembly comprising a dual-function load-bearing track under the floor in case of a side collision, and a 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 side impact.

[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 comprising a front part 107 and a central part 109 assembled together by welding.

[0009] The body structure further comprises, among these structural elements, longitudinal structural beams 111 commonly called "frame members" and extending longitudinally relative to the vehicle. The frame members 111 typically comprise two front frame members 113, extending on either side of a powertrain (not shown) of the vehicle, and two rear frame members 115, extending behind the front frame members 113 and located opposite the longitudinal side members 103, towards the inside of the front floor 105 of the vehicle and under the front floor of the vehicle.

[0010] The front part 107 of the front floor 105 is longitudinally reinforced by means of longitudinal reinforcement pieces 117 of the front floor 105, arranged longitudinally on the front part 107 of the front floor 105.

[0011] A first interface piece, called the outer interface piece 119, provides the connection between the longitudinal side member 103 and the corresponding front frame member 113. A second interface piece, called the inner interface piece 120, provides the connection between the first interface piece 119, a central tunnel 121 of the vehicle, and the vehicle's bulkhead (not shown).

[0012] The longitudinal reinforcement piece 117 is fixed to the inner interface piece 120 and to the central tunnel 121 and extends longitudinally over the front part 107 of the front floor 105.

[0013] When the vehicle is a battery electric motor vehicle (BEV, an Anglo-Saxon acronym for "Battery Electric Vehicle"), or when the vehicle is 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 (PHEV, an English acronym for "Plug-in Hybrid Electric Vehicle"), the vehicle includes a traction battery 123 fixed under the front floor 105 of the underbody assembly 101, supplying the electric motor of the vehicle.

[0014] Among the plurality of tests used for the homologation of motor vehicles, a so-called "pole" impact, also called "side impact", is carried out, in particular in order to reveal performance criteria relating to the protection of occupants.

[0015] This test consists of projecting the motor vehicle at a speed of approximately 32 km / h laterally against a rigid post, so that the vehicle defines an angle of approximately 75° relative to the post.

[0016] During a side impact, the post becomes embedded in the motor vehicle at the front door on the driver's or passenger's side.

[0017] When the motor vehicle is subjected to such a side impact, the traction battery 123 must be protected in order to prevent damage to it and limit the risk of fire.

[0018] For this purpose, the underbody assembly 101 includes transverse stiffeners 125 of the front floor 105, extending transversely relative to the vehicle and connecting the longitudinal side members 103 to the corresponding rear frame members 115.

[0019] Thus, in the event of a pole impact at zone A of the vehicle, the transverse stiffeners 125 of the front floor 105 transmit the forces from the longitudinal side member 103 to the corresponding rear frame member 115, making it possible to ensure the protection of occupants and limiting the risks of damage to the traction battery 123.

[0020] However, in the event of a pole impact at the level of zone B of the vehicle, i.e. at the level of a front part of the front floor 105 behind the apron of the vehicle and in the immediate vicinity of the apron, the forces pass from the longitudinal side member 103 to the corresponding rear frame member 115 via the transverse stiffeners 125.

[0021] The forces then pass transversely from the rear stretcher 115 into the front part 107 of the front floor 105.

[0022] Such efforts taken up by the front part 107 of the front floor 105 can cause a rupture of the weld points between the front part 107 and the central part 109 of the front floor 105, which can lead to a separation between the front part 107 and the central part 109 of the front floor 105.

[0023] Such a separation results in a high risk of intrusion into the vehicle, which could injure the occupants.

[0024] This also entails a high risk of contact with the traction battery 123, thus considerably increasing the risk of vehicle fire. Description of the invention

[0025] The present invention aims to overcome the aforementioned drawbacks, and to this end relates to a motor vehicle underbody assembly, comprising: - a front floor, comprising a front portion and, behind said front portion, a central portion, said front and central portions being connected to each other by welding, - a longitudinal side member, laterally bordering at least a portion of said front floor, - a rear frame member, extending longitudinally opposite said longitudinal side member, - a set of transverse front floor stiffeners, extending transversely so as to connect said longitudinal side member to said rear frame member, - a longitudinal reinforcement piece for said front floor, extending longitudinally over the front portion of said front floor, said assembly being remarkable in that it comprises a transverse reinforcement piece,extending transversely across the front part of said front floor, connecting said rear stretcher to said longitudinal reinforcement piece of said front floor.

[0026] Thus, in the event of a pole impact at a front area of ​​the front floor, behind the vehicle's bulkhead and in the immediate vicinity of the bulkhead, the forces are transmitted through a first stage of the longitudinal side member to the rear frame, via the transverse stiffeners.

[0027] By providing for equipping the entire underbody with a transverse reinforcement piece for the front floor, extending transversely over the front part of the front floor and connecting the rear frame to the longitudinal reinforcement piece for the front floor, a path of forces is defined allowing the forces to be transmitted between the rear frame and the longitudinal reinforcement piece for the front floor.

[0028] Thus, the forces are subsequently transmitted from the rear stretcher to the longitudinal reinforcement piece of the front floor, via the transverse reinforcement piece.

[0029] The compressive strength of the transverse reinforcement piece helps to reduce the intrusion of the post.

[0030] In this way, the risk of breakage of the weld points between the front part of the front floor and the central part of the front floor is limited, and therefore the risk of separation between the front and central parts of the front floor is reduced. This relieves stress on the assembly area between the front and central parts of the front floor.

[0031] Thus, thanks to the present invention, the protection of the occupants on board the vehicle is increased.

[0032] Also, the risk of contact with the traction battery is reduced, thus limiting the risk of vehicle fire.

[0033] According to optional features of the base assembly according to the invention: - the base assembly includes a welding area comprising at least two weld points, each ensuring the connection between said transverse reinforcement piece, the front part of said front floor and the central part of said front floor; - said transverse reinforcement piece is fixed by welding to said front part of said front floor; - said transverse reinforcement piece is fixed by welding to said rear stretcher and to said longitudinal reinforcement piece to said front floor; - said transverse reinforcement piece comprises a front vertical wall and a rear vertical wall connected to said front vertical wall by a horizontal wall, said front and rear vertical walls and said horizontal wall defining a U-shaped cross-section; - the underbody assembly includes a traction battery fixed under said front floor and adapted to power an electric motor of said motor vehicle, and the distance between said rear vertical wall of said transverse reinforcement piece and said traction battery is between approximately 40mm and approximately 60mm; - the maximum height between the front part of said front floor and said horizontal wall of said transverse reinforcement piece is between approximately 25mm and approximately 40mm; - said front vertical wall of said transverse reinforcement piece is extended by a front fixing bracket extending towards the front of said subframe assembly and said rear vertical wall of said transverse reinforcement piece is extended by a rear fixing bracket extending towards the rear of said subframe assembly; - said weld area, comprising at least two weld points ensuring the connection between said transverse reinforcement piece, the front part of said front floor and the central part of said front floor, includes said rear fixing bracket of said transverse reinforcement piece.

[0034] 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

[0035] 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:

[0036] [Fig-1] shows a subframe assembly of a motor vehicle of the art anterior view, seen from below.

[0037] [Fig.2] is a bottom view of a subframe assembly of a motor vehicle according to the invention.

[0038] [Fig.3] is an enlargement of zone III of [Fig.2].

[0039] [Fig.4] is an enlargement of zone IV of [Fig.3].

[0040] [Fig.5] is a cross-sectional view along line VV of [Fig.4].

[0041] [Fig.6] schematically shows the path of forces when the vehicle is subjected to a lateral post impact.

[0042] [Fig.7] shows the entire base of the invention after the lateral post impact. Description of the implementation methods

[0043] In the following description, elements having an identical structure or analogous functions are designated by the same reference.

[0044] 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.

[0045] In what follows, the terms "left", "right", "lower" and "upper" are understood in relation to the vehicle.

[0046] 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.

[0047] 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].

[0048] The subframe assembly 1 includes longitudinal side rails 3, defining a part of the perimeter of the subframe assembly 1 of the body.

[0049] The underbody assembly 1 comprises a front floor 5, defining a part of the passenger compartment platform of the motor vehicle. The front floor 5 comprises a front portion 7 and a central portion 9 behind the front portion 7, joined together by welding.

[0050] The base assembly 1 further comprises stretchers 11, extending longitudinally relative to the vehicle.

[0051] The stretchers 11 typically comprise two front stretchers 13, extending on either side of a powertrain (not shown) of the vehicle, and two rear stretchers 15, extending behind the front stretchers 13 and located opposite the longitudinal side rails 3, towards the inside of the front floor 5 of the vehicle and under the front floor 5 of the vehicle.

[0052] The front part 7 of the front floor 5 is longitudinally reinforced by means of longitudinal reinforcement pieces 17 of the front floor 5, arranged longitudinally on the front part 7 of the front floor 5.

[0053] A first interface piece, called the outer interface piece 19, provides the connection between the longitudinal side member 3 and the corresponding front frame member 13. A second interface piece, called the inner interface piece 20, provides the connection between the first interface piece 19, a central tunnel 21 of the vehicle and the vehicle's bulkhead (not shown).

[0054] The longitudinal reinforcement piece 17 is fixed to the inner interface piece 20 and to the central tunnel 21 and extends longitudinally over the front part 7 of the front floor 5.

[0055] The subframe assembly 1 further comprises a set of transverse stiffeners 25 of the front floor 5, extending transversely relative to the vehicle and connecting the longitudinal side members 3 to the corresponding rear beams 15.

[0056] According to the invention, the base assembly 1 comprises transverse reinforcement pieces 27, extending transversely over the front part 7 of the front floor 5, connecting each rear stretcher 15 to the corresponding longitudinal reinforcement piece 17 of the front floor 5.

[0057] The stiffness of the transverse reinforcement piece 27 is adapted to allow the transmission of forces between the rear frame 15 and the longitudinal reinforcement piece 17 of the corresponding front floor 5 while maintaining the integrity of the transverse reinforcement piece 27.

[0058] Reference is made to [Fig.4], which is an enlargement of zone IV of [Fig.3], as well as to [Fig.5], which schematically shows the assembly formed by the front 7 and central 9 parts of the front floor 5 and by the transverse reinforcement piece 27, seen in cross-section along the line VV of [Fig.4].

[0059] In one embodiment, the base assembly 1 includes a weld zone 29 comprising weld points, each of which provides a triple connection between the transverse reinforcement piece 27, the front part 7 of the front floor 5 and the central part 9 of the front floor 5.

[0060] Two or more weld points may be provided in the weld area 29.

[0061] In this way, the entire subframe 1 is further reinforced at the level of the assembly area between the front part 7 of the front floor 5 and the central part 9 of the front floor 5, which further limits the risk of separation between the front part 7 and the central part 9 of the front floor 5.

[0062] The weld area 29 is arranged in the rear part of the transverse reinforcement piece 27.

[0063] At its front part, the transverse reinforcement piece 27 is also fixed by welding to the front part 7 of the front floor 5, at the level of a weld zone 31.

[0064] The transverse reinforcement piece 27 is further fixed, at its lateral ends 33, 35, respectively to the rear stretcher 15 and to the longitudinal reinforcement piece 17.

[0065] The transverse reinforcement piece 27 comprises a front vertical wall 37 and a rear vertical wall 39, extending substantially vertically relative to the vehicle, connected to each other by a horizontal wall 41, extending substantially horizontally relative to the vehicle.

[0066] The front vertical wall 37, the horizontal wall 41 and the rear vertical wall 39 define a U-shaped cross-section.

[0067] When the transverse reinforcement piece 27 is mounted on the front floor 5, the assembly thus formed by the front parts 7 and central part 9 of the front floor 5 and by the transverse reinforcement piece 27 defines a hollow body.

[0068] The front vertical wall 37 of the transverse reinforcement piece 27 is extended at the front by a front fixing tab 43 extending towards the front of the base assembly 1.

[0069] The front mounting bracket 43 is welded to the front part 7 of the front floor 5, at the weld area 31.

[0070] The front vertical wall 37 of the transverse reinforcement piece 27 is extended at the rear by a rear fixing tab 45 extending towards the rear of the base assembly 1.

[0071] At the weld area 31, the rear fixing bracket 45 is welded to the front part 7 and to the rear part 9 of the front floor 5.

[0072] The rear part 9 of the front floor 5 is then sandwiched between the rear fixing bracket 45 of the transverse reinforcement piece 27 and the front part 7 of the front floor 5.

[0073] In one embodiment, the maximum height H, between the front part 7 of the front floor 5 and the horizontal wall 41 of the transverse reinforcement piece 27, is between approximately 25mm and approximately 40mm.

[0074] The vehicle may be electric with a battery (a 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 (a so-called "PHEV" motor vehicle, an English acronym for "Plug-in Hybrid Electric Vehicle").

[0075] The vehicle includes a traction battery (not shown) fixed under the front floor 5 of the underbody assembly 1, powering the vehicle's electric motor.

[0076] In one embodiment, the distance D between the rear vertical wall 39 of the transverse reinforcement piece 27 and the traction battery (the location of the front lateral edge of which is shown in dotted lines in [Fig.4]) is between approximately 40mm and approximately 60mm.

[0077] Thus, during a pole impact suffered by the vehicle, the distance D is such that contact between the traction battery and the transverse reinforcement piece 27 is advantageously avoided. In this way, the risk of fire of the traction battery is further limited.

[0078] Reference is made to [Fig.6] showing schematically the path of forces when the vehicle is subjected to a lateral pole impact.

[0079] When a post 47 laterally impacts the vehicle at the level of the vehicle zone B, i.e. at the level of the front part 7 of the front floor 5, behind the apron and in the immediate vicinity of the apron, part of the forces passes from the longitudinal side member 3 into the outer interface piece 19 and into the inner interface piece 20, as shown by arrows 49, 51, 53. Part of the forces arrives in the rear frame 15, as shown by arrow 55.

[0080] Similarly, when the post 47 impacts the vehicle, another part of the forces is transmitted by the longitudinal side member 3 to the rear frame 15, via the transverse stiffeners 25, as represented by arrows 57, 59.

[0081] The rear stretcher 15 transmits the forces to the longitudinal reinforcement piece 17 of the front floor 5, via the transverse reinforcement piece 27, as represented by the arrow 61.

[0082] Reference is made to [Fig.7] showing the base assembly 1 after the lateral post impact illustrated in [Fig.6].

[0083] As shown, the presence of the transverse reinforcement piece 27 has made it possible to reduce the intrusion of the post into the vehicle, which makes it possible to limit the risk of breakage of the weld points between the front part 7 of the front floor 5 and the central part 9 of the front floor 5, and therefore of separation between the front part 7 and the central part 9 of the front floor 5.

[0084] Thus, the protection of the occupants on board the vehicle is increased and the risk of contact with the traction battery 23 is limited, thereby reducing the risk of vehicle fire.

[0085] 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. A motor vehicle underbody assembly (1), comprising: - a front floor (5), comprising a front portion (7) and, behind said front portion (7), a central portion (9), said front (7) and central (9) portions being joined together by welding, - a longitudinal side member (3), laterally bordering at least a portion of said front floor (5), - a rear frame member (15), extending longitudinally opposite said longitudinal side member (3), - a set of transverse stiffeners (25) of the front floor, extending transversely so as to connect said longitudinal side member (3) to said rear frame member (15), - a longitudinal reinforcement piece (17) of said front floor (5), extending longitudinally over the front portion (7) of said front floor (5), said underbody assembly (1) being characterized in that it comprises a transverse reinforcement piece (27),extending transversely over the front part (7) of said front floor (5), connecting said rear stretcher (15) to said longitudinal reinforcement piece (17) of said front floor (5).

2. Base assembly (1) according to claim 1, characterized in that it comprises a weld zone (31) having at least two weld points each ensuring the connection between: - said transverse reinforcement piece (27), - the front part (7) of said front floor (5), - the central part (9) of said front floor (5).

3. Underbody assembly (1) according to any one of claims 1 or 2, characterized in that said transverse reinforcement piece (27) is fixed by welding to said front part (7) of said front floor (5).

4. Underbody assembly (1) according to any one of claims 1 to 3, characterized in that said transverse reinforcement piece (27) is fixed by welding to said rear frame (15) and to said longitudinal reinforcement piece (17) of said front floor (5).

5. A base assembly (1) according to any one of claims 1 to 4, characterized in that said transverse reinforcement piece (27) comprises a front vertical wall (37) and a wall rear vertical wall (39) connected to said front vertical wall (37) by a horizontal wall (41), said front vertical walls (37) and rear vertical walls (39) and said horizontal wall (41) defining a U-shaped cross-section.

6. Underbody assembly (1) according to claim 5, comprising a traction battery (23) fixed under said front floor (5) and adapted to power an electric motor of said motor vehicle, characterized in that the distance (D) between said rear vertical wall (39) of said transverse reinforcement piece (27) and said traction battery (23) is between about 40mm and about 60mm.

7. Base assembly (1) according to any one of claims 5 or 6, characterized in that the maximum height (H) between the front part (7) of said front floor (5) and said horizontal wall (41) of said transverse reinforcement piece (27) is between about 25mm and about 40mm.

8. Base assembly (1) according to any one of claims 5 to 7, characterized in that said front vertical wall (37) of said transverse reinforcement piece (27) is extended by a front fixing tab (43) extending towards the front of said base assembly (1) and in that said rear vertical wall (39) of said transverse reinforcement piece (27) is extended by a rear fixing tab (45) extending towards the rear of said base assembly (1).

9. Underbody assembly (1) according to claims 2 and 8, characterized in that said weld zone (31), comprising at least two weld points ensuring the connection between said transverse reinforcement piece (27), the front part (7) of said front floor (5) and the central part (9) of said front floor (5), comprises said rear fixing tab (45) of said transverse reinforcement piece (27).

10. Motor vehicle comprising a subframe assembly (1), characterized in that said subframe assembly (1) is according to any one of claims 1 to 9.

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