Longitudinal load transfer assembly for an automotive vehicle underbody

Abstract

The invention relates to a longitudinal load transfer assembly (10) for a motor vehicle underbody, comprising: - a hollow U-shaped transverse profile (12) with flanges; - a hollow U-shaped longitudinal connecting profile (14) with flanges, the opening of which is oriented in the same direction as the opening of the hollow cross-section of the transverse profile, the rear end of the connecting profile being vertically and longitudinally fixed to the transverse profile; - at least three longitudinal spacers (16-18) disposed inside and fixed to the transverse profile (12), and positioned opposite longitudinal side walls (140, 141) of the connecting profile (14), a third spacer (18) being positioned opposite a longitudinal side wall (300) of a longeron (3) to which the assembly must be fixed.Figure to be published with the abbreviation: Fig.3.

Description

Title of the invention: Assembly for transferring longitudinal forces from a motor vehicle underbody

[0001] The present invention relates to a longitudinal load transfer assembly for a motor vehicle underbody, which can be used in particular for different types of vehicles. The invention also relates to an underbody equipped with the longitudinal load transfer assembly.

[0002] To limit the number of assembly lines and the associated costs, manufacturers use similar underpinnings for the different powertrains of a vehicle (internal combustion, electric, or hybrid). To this end, it can be advantageous to make a section of the underpinning, for example, a front section, common to the different types of vehicle. This front section of the underpinning includes side members whose forces must be able to be transmitted to a central section of the underpinning during a frontal impact. However, in the case of an electric or hybrid vehicle, the side members of this central section of the underpinning are generally more widely spaced laterally than the side members of a central section of an internal combustion vehicle, in order to accommodate the vehicle's battery packs beneath the underpinning. It also happens that the spacing of the side members differs from one electric / hybrid vehicle model to another.However, it is necessary to ensure the transmission of longitudinal forces exerted on the front side members to the side members of this central section.

[0003] The invention aims to overcome all or part of the aforementioned drawbacks by proposing an assembly for the longitudinal transfer of forces from a motor vehicle underbody, comprising:

[0004] - a transverse profile, extending in a transverse direction of the assembly in In the position of use, hollow in shape with a U-shaped cross-section and horizontal edges,

[0005] - a longitudinal connecting profile, extending perpendicularly to the profile transverse, hollow in shape with a U-shaped cross-section provided with horizontal edges, the opening of which is oriented in the same direction as the opening of the hollow shape of the transverse profile, the connecting profile having a rear end fixed to the transverse profile vertically and longitudinally, in particular via rear ends of its edges and rear fixing tabs,

[0006] - at least three longitudinal spacers arranged inside the profile transverse and integral with it, particularly longitudinally, two of the spacers being positioned opposite longitudinal lateral walls of the connecting profile, a third spacer being arranged in another position intended to be situated opposite a longitudinal side wall of a stringer to which the assembly is to be fixed.

[0007] In particular, the connecting profile is intended to be attached to a front side member, the transverse profile being intended to be attached, on a side opposite the connecting profile, to a central side member. The assembly according to the invention then allows, thanks to the specific shape of the profiles and the positions of the spacers, an efficient transfer of force between the front side member, forming for example part of a front underbody section, and a central side member, forming for example part of a central underbody section, these side members not being longitudinally aligned.

[0008] In particular, since the transverse profile extends along the transverse direction in the operating position, the assembly according to the invention makes optimal use of the space between the assembly and the central stringer, notably due to the absence of curved shapes or parts extending in a direction that is not longitudinal or transverse. This can allow for the longitudinal placement of larger battery packs.

[0009] When parts are joined vertically or longitudinally, they are joined along the vertical or longitudinal direction respectively. The parts to be assembled then have joining parts, in particular a rim and / or a fixing tab, which extend perpendicularly to the direction of joining.

[0010] Generally, the connecting profile may have at least one part, in particular a front part in the operating position, having a shape complementary to the inside of the longeron to which it is intended to be attached. This allows it to conform to the inside shape of the longeron to which it is to be secured.

[0011] In general, also for greater robustness, the transverse profile can be closed at its transverse ends by end walls.

[0012] Advantageously, the assembly may comprise at least two reinforcing elements, each having a reinforcing wall bearing against and fixed to a bottom wall of the transverse profile. Each spacer then forms part of a reinforcing element and is connected to the reinforcing wall of a reinforcing element. This can improve the robustness of the assembly.

[0013] Advantageously, the reinforcing wall of each reinforcing element and the bottom wall of the cross profile can then be drilled with at least one through hole receiving a welded nut. This can allow the assembly according to the invention, and in particular the cross profile, to be used as a fastening interface for attaching a battery pack or a battery pack protector.

[0014] Advantageously, the rear end of the connecting profile may include rear mounting tabs and the spacers of the front mounting tabs to the transverse profile. The rear mounting tabs of the connecting profile may then be located opposite The spacer mounting brackets are located on either side of a front side wall of the cross profile. This can improve the transmission of longitudinal forces.

[0015] Advantageously, the assembly according to the invention may further comprise a first wall assembled to the edges of the transverse profile and closing it, and a second wall assembled to the edges of the connecting profile and closing it. This improves the robustness of the assembly.

[0016] Advantageously, the different elements of the assembly can be made of metal or metal alloy and be joined together by welding.

[0017] Advantageously, regardless of the embodiment, the assembly according to the invention may comprise one or more of the following features:

[0018] - the transverse profile has two lateral walls connected by a bottom wall finishing the hollow U-shaped cross-section, each side wall being provided with the horizontal transverse rim,

[0019] - the longitudinal connecting profile has two lateral walls connected by a wall of the base defining the hollow shape with a U-shaped cross-section and: - each side wall of the connecting profile is provided with the horizontal rim, the rear end of which is attached to a front transverse rim of the transverse profile, and with a rear transverse fixing tab attached to a front side wall of said transverse profile, - the bottom wall of the connecting profile is provided, on the same side as the rear fixing lugs, with a fixing lug attached to the bottom wall or the front side wall of the transverse profile,

[0020] - each spacer is fixed to the side walls of the cross profile by tabs front and rear mounting.

[0021] The invention also relates to a motor vehicle underbody comprising a front side member and a central side member that are not longitudinally aligned with each other, each side member having two lateral walls connected by a bottom wall defining a hollow U-shaped cross-section, each lateral wall being provided with a horizontal longitudinal lip in the operating position. The underbody according to the invention comprises an assembly according to the invention connecting the front side member to the central side member, the connecting profile of the assembly having a shape conforming to the inner shape of the front side member and being fixed to the front side member, inside the latter, one of the longitudinal struts of the assembly extending in line with a lateral wall of the central side member, a front end of the central side member being fixed to the transverse profile vertically and horizontally.

[0022] Thus, despite a lack of alignment of the front and central side members, the assembly according to the invention allows for an efficient transfer of longitudinal forces. The side member The front section can be part of a front subframe, for example, common to different vehicle models, while the central side member can be part of a central subframe specific to a vehicle model. It is therefore clear that it is possible to create subframes with a common, i.e., standard, front section and a specific central section, while still maintaining longitudinal load transfer.

[0023] The underbody can thus comprise a front part of the underbody including two front longitudinal members and a central part of the underbody including two central longitudinal members, each front longitudinal member being connected to the corresponding central longitudinal member by an assembly according to the invention, as previously described.

[0024] Advantageously, the front end of the central longitudinal member may have transverse fixing lugs attached to the transverse profile, in particular to its rear side wall, the front ends of the transverse edges of the central longitudinal member being attached to the rear transverse edge of the transverse profile, below it.

[0025] Advantageously, for better transmission of forces, at least one front transverse fixing bracket of the central longitudinal member can be located opposite, longitudinally, a rear transverse fixing bracket of a spacer, on either side of a rear side wall of the transverse profile.

[0026] A vehicle underbody typically comprises a floor, which may be in one or more parts, assembled to and enclosing the edges of the side members. The connecting profile of the assembly may then be closed by a first wall forming part of the floor. The transverse profile of the assembly may be closed by a second wall, either forming part of the floor or an independent wall fixed to the floor, particularly underneath it.

[0027] The invention also relates to a motor vehicle comprising a base according to the invention.

[0028] Other features and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of example but not limitation, with reference to the accompanying drawings in which:

[0029] [Fig-1] is a bottom view of a base according to an embodiment according to the invention.

[0030] [Fig.2] represents a bottom view of an assembly according to an embodiment of the invention.

[0031] [Fig.3] represents a perspective top view of an assembly according to a mode implementation of the invention connected to a front longitudinal member and a central longitudinal member.

[0032] [Fig.4] represents a perspective view of the connecting profile of the assembly re presented [Fig.3].

[0033] [Fig.5] represents a longitudinal section of the assembly of [Fig.3] according to the line AA.

[0034] [Fig.6] represents another perspective top view of the assembly of the [Fig.3].

[0035] The orientations expressed in the description of the figures are given with reference to a classic orthonormal XYZ frame of reference of a motor vehicle, the X axis representing the longitudinal direction, oriented from front to back of the vehicle, the Y axis representing the transverse direction of the vehicle, oriented from left to right, and the Z axis representing the vertical direction, oriented upwards, of the vehicle.

[0036] In the following description, the terms front and rear refer in a conventional way to the front and rear of the motor vehicle.

[0037] By substantially horizontal, longitudinal or vertical, we mean a direction / plane forming an angle of at most ±20°, or even of at most ±10° or of at most ±5°, with a horizontal, longitudinal or vertical direction / plane.

[0038] By substantially parallel, perpendicular or at a right angle, we mean a direction / angle that deviates by at most ±20°, or even by at most ±10° or by at most ±5° from a parallel, perpendicular or right-angle direction / plane.

[0039] Identical references may be used from one figure to another to designate identical or similar elements.

[0040] In the following, the description is carried out considering the base and the assembly according to the invention in their position of use inside a vehicle, the position of use of the assembly being a position assembled to the base.

[0041] Figure 1 shows, viewed from below, a vehicle underbody 1, in this case, of an electrically powered vehicle. This underbody 1 comprises two front longitudinal members 2 and two central longitudinal members 3. A battery pack 4 is also shown schematically. The front longitudinal members 2 form part of a front underbody section 1a, and the central longitudinal members 3 form part of a central underbody section 1b. The underbody also includes a rear underbody section 1a. These various sections are assembled together to form the underbody.

[0042] As can be seen, each central side member 3 is offset transversely, here towards the outside of the vehicle, from the corresponding front side member 2. In other words, each central side member 3 does not extend longitudinally in continuity with a front side member 2.

[0043] Typically, each longitudinal member 2, 3 has two side walls 200, 201; 300, 301 respectively, connected by a bottom wall 202, 302 respectively, these side and bottom walls defining a hollow shape with a U-shaped cross-section. Each side wall 200, 201; 300, 301 is provided with a horizontal longitudinal rim 203, 204; 303, 304 respectively, in the position of use of the base. The side rails are open at the top and usually closed by the vehicle floor, which may be in one or more parts.

[0044] The assembly 10 according to the invention allows these front and central side members to be connected in order to ensure the transfer of longitudinal forces. Thus, the assembly 10 is attached to a rear end of the front side member 2 and to a front end of the central side member 3.

[0045] To this end, the assembly 10 comprises a hollow U-shaped transverse profile 12 with horizontal edges, a hollow U-shaped longitudinal connecting profile 14 with horizontal edges, and longitudinal spacers 16, 17, 18 arranged inside and integral with the transverse profile 12. An embodiment of these elements is described in more detail with reference to Figures 2 to 6.

[0046] The transverse profile 12 extends in a transverse direction of the vehicle in the position of use of the assembly 10, and here has two side walls 120, 121, namely a front side wall 120 directed towards the front of the vehicle in the position of use of the assembly 10, and a rear side wall 121 directed towards the rear of the vehicle in the position of use of the assembly 10, these side walls 120, 121 being connected by a bottom wall 122. These side walls 120, 121 and bottom wall 122 thus define a hollow shape with a U-shaped cross-section, the opening of which is directed upwards in the position of use of the assembly 10. Each front side wall 120 and rear side wall 121 is provided with a horizontal transverse rim at the front 123 and rear 124 respectively, in the position of use of the assembly 10. The bottom wall 122 typically extends horizontally.The shape of the cross-section of the transverse profile 12 (longitudinal section) is therefore similar to a Q.

[0047] Preferably, the transverse profile 12 is closed at its transverse ends by end walls 125, 126, which are rounded in the example shown. However, the invention is not limited to a particular shape of the end walls, which could be flat. These end walls 125, 126 are also provided with horizontal flanges 127, 128 respectively (see Figures 2 and 3). In particular, as shown in the example, the flanges 123, 124, 127, and 128 extend all the way around the transverse profile 12. The transverse profile 12 is typically a metal part produced by stamping.

[0048] The longitudinal connecting profile 14 extends perpendicularly to the transverse profile 12. It is fixed to the latter on the front side of the transverse profile 12. The connecting profile 14 has two lateral walls 140, 141 connected by a bottom wall 142, these walls 140-142 defining a hollow shape with a U-shaped cross-section, the opening of which is oriented in the same direction as the opening of the hollow shape of the transverse profile 12. The connecting profile advantageously has a portion of The complementary shape of the internal shape of the longeron to which it is to be attached is designed to conform to its shape during assembly. This complementary shape can advantageously extend along part of its length, with the remainder of the connecting profile then serving to attach it to the transverse profile.

[0049] The bottom wall 142 typically extends substantially horizontally.

[0050] Each side wall 140, 141 of the connecting profile is provided with a horizontal longitudinal rim 143, 144 respectively, in the position of use of the assembly, the rear end of which 143a, 144a is secured to the front horizontal transverse rim 123 of the transverse profile 12 (see [Fig.3]). Each side wall 140, 141 of the connecting profile 14 also includes a rear transverse fixing bracket 145, 146 respectively, attached to the front side wall 120 of the transverse profile 12. Finally, the bottom wall 142 of the connecting profile 14 is provided, on the same side as the rear transverse fixing brackets 145, 146, with a rear fixing bracket 147 attached to the front side wall 120 of the transverse profile 12. This rear fixing bracket 147 thus extends perpendicularly or substantially perpendicularly to the bottom wall 142 in the example shown.

[0051] In an embodiment not shown, the rear fixing bracket 147 can be secured to the bottom wall 122 of the transverse profile. The rear fixing bracket 147 then extends in line with, or substantially in line with, the bottom wall 142 of the connecting profile and is secured to the bottom wall 122, beneath the latter.

[0052] The assembly 10 according to the invention finally comprises, in the example shown, three longitudinal spacers 16, 17, 18 arranged inside the transverse profile 12, perpendicular to its front lateral walls 120 and rear 121. Each spacer 16, 17, 18 is fixed to the front lateral walls 120 and rear 121 of the transverse profile 12 by fixing tabs, two of the spacers 16, 17 being arranged opposite, and in particular in line with, the longitudinal lateral walls 140, 141 of the connecting profile, a third spacer 18 being arranged in a position opposite, and in particular in line with, the longitudinal lateral wall 300 of the central stringer 3 to which the assembly 10 is to be fixed (see [Fig.3]).

[0053] In particular, each spacer 16, 17, 18 has a front fixing tab 160, 170, 180 respectively, fixed to the front side wall 120 of the cross profile 12, and a rear fixing tab 161, 171, 181 respectively, fixed to the rear side wall 121 of the cross profile 12.

[0054] In the example, the front mounting tabs 160, 170 and rear mounting tabs 161, 171 of the spacers 16, 17 define a U-shape with the spacer, while the front mounting tabs 180 and rear mounting tabs 181 of the spacer 18 define an S-shape with the spacer. However, the invention is not limited to this embodiment and any Which spacer could define a U or S shape with its mounting brackets?

[0055] In the example shown, three spacers 16-18 are provided. The invention is not limited, however, by the number of spacers used, although three spacers are sufficient for the transfer of longitudinal forces and the robustness of the assembly. In particular, it would be possible to position more than three spacers inside the transverse profile, depending on its transverse length. For example, a fourth spacer could be provided and positioned opposite the other longitudinal side wall 301 of the central stringer 3 to which the assembly is to be attached. It would also be possible to replace the end walls 125, 126 with spacers.

[0056] Whatever the shape of the cross profile, when only three spacers are provided, for greater robustness, the third spacer 18 can advantageously be positioned opposite the side wall 300 of the central longitudinal member 3 located closest laterally to the front longitudinal member 2, in other words, closest laterally to the other spacers.

[0057] In the example shown, the assembly 10 further comprises two reinforcing elements 19, 21, each having a reinforcing wall 190, 210 bearing against and fixed to the bottom wall 122 of the transverse profile 12. Each spacer 16-18 is part of a reinforcing element and is connected to the reinforcing wall 190, 210 of a reinforcing element. In particular, in this example, a first reinforcing element 19 is formed by the reinforcing wall 190 connected to the spacers 16, 17. The reinforcing wall 190 also extends up the rear side wall 121 of the transverse profile to which it is fixed (see [Fig. 3]), but could extend only against the bottom wall. This first reinforcement element 19 is here made in one piece with the spacers 16, 17. The second reinforcement element 21 is formed by the reinforcement wall 210 connected to the spacer 18.The reinforcing wall 210 also extends up the rear side wall 121 of the transverse profile to which it is attached, but could extend only against the bottom wall. This second reinforcing element 21 is here made in one piece with the spacer 18. The invention is not, however, limited to this particular arrangement of the reinforcing elements, which may consist solely of the spacers and reinforcing walls. Furthermore, other ways of connecting the spacers by the reinforcing elements are conceivable. For example, one reinforcing element could be connected to the spacers 17 and 18 and another to the spacer 16, or three reinforcing elements could be provided, each connected to a spacer. The embodiment described with reference to the figures is, however, advantageous when the longerons are relatively close laterally.

[0058] These reinforcing elements 19, 21 can be used to reinforce the mounting interfaces for a battery pack or for a protective battery pack case These are made at the level of the transverse profile. To this end, the bottom wall 122 of the transverse profile is pierced with through holes 129, 130 ([Fig. 2]) which correspond to through holes (not visible in the figures) in the reinforcing wall 190, 210 of each reinforcing element 19, 21. These corresponding through holes each receive a welded nut 131, 132 respectively, located inside the transverse profile. In the example, each reinforcing element 19, 21 is pierced with a single hole provided with a welded nut 131, 132. The invention is not, however, limited to this embodiment and more holes can be provided depending on the desired objective and the dimensions of the reinforcing elements, and in particular the reinforcing walls.

[0059] For optimal transmission of longitudinal forces, the rear transverse fixing lugs 145, 146 of the connecting profile 14 can be positioned opposite (longitudinally) the front fixing lugs 160, 170 respectively of the spacers 16, 17 on either side of the front side wall 120 of the transverse profile.

[0060] Also for optimal transmission of longitudinal forces, the assembly 10 can include a first wall assembled to the edges of the transverse profile and closing it and a second wall assembled to the edges of the connecting profile and closing it.

[0061] In the example shown, the first wall is an independent wall 22, while the second wall is a front portion 5a of a subframe floor. This arrangement is particularly advantageous when the front lateral walls 120 and rear lateral walls 121 of the cross-section 12 are of different heights, as in the example shown (see, for example, [Fig. 5]). The vehicle floor then does not extend in the same horizontal plane over the entire surface of the subframe, the front portion 5a of the floor being lower than the central portion 5b of the floor. In this example, the front portion 5a and central portion 5b of the floor are fixed to the first wall 22, above it.

[0062] The invention is not, however, limited to this embodiment, and the front lateral walls 120 and rear 121 of the transverse profile may be of the same height. This is generally the case when the floor extends in a single horizontal plane over the entire surface of the underbody 1. In this case, the first and second walls closing the transverse profile and the connecting profile may be formed from the vehicle floor.

[0063] Preferably, regardless of the embodiment, the spacers 16-18 extend over the entire height of the transverse profile 12. When the front and rear side walls of the transverse profile 12 are of different heights, these spacers can thus have a general shape similar to an L, as seen [Fig. 5]. Other shapes are, however, possible depending on the shape of the wall 22 and the difference in height of the side walls.

[0064] The various elements of the assembly 10 are typically made of metal or alloy The components are typically made of metal or a metal alloy, preferably steel, and joined together by welding, for example by spot welding. The underbody rails are also typically made of metal or a metal alloy, preferably steel, allowing the assembly according to the invention to be welded to these rails.

[0065] The assembly 10 according to the invention is mounted on the base in the manner described below, the various elements 12, 14, 16-18 of this assembly 10 being previously assembled to each other.

[0066] The connecting profile 14 is inserted inside the front side member 2, at its rear end. In particular, the connecting profile 14 conforms to the shape of the rear end of the front side member. In the example shown, the connecting profile 14 protrudes slightly from the front longitudinal member 2 towards the rear, here only along the length of the rear end 143a, 144a of the horizontal longitudinal edges 143, 144. It should also be noted that these rear ends 143a, 144a are located in a horizontal plane slightly below, vertically, the rest of the edge 143, 144, for example the thickness of the front transverse edge 123 of the transverse profile: in this way, this front transverse edge 123 and the horizontal longitudinal edges 143, 144 are substantially in the same horizontal plane.

[0067] The connecting profile 14 can thus be assembled to the front side member 2, typically by welding. It should be noted that the longitudinal edges 203, 204 of the front side member 2 may have a rear end 203a, 204a located in a horizontal plane slightly below, vertically, the rest of the edge 203, 204, for example, by the thickness of the horizontal longitudinal edges 143, 144, so that the longitudinal edges 203, 204 of the front side member extend substantially in the same horizontal plane as the horizontal longitudinal edges 143, 144 of the connecting profile and the front transverse edge 123 of the transverse profile. This can, in particular, facilitate the closing of the front side member, the connecting profile, and the transverse profile and avoids excess thickness.

[0068] Next, the cross profile 12 is fixed to the central longitudinal member 3. For this purpose, the front end of the central longitudinal member has transverse fixing tabs 305, 306 attached to the assembly 10. The front ends 303a, 304a of the horizontal longitudinal edges 303, 304 of the central longitudinal member are also attached to the rear transverse edge 124 of the cross profile 12, in particular under the latter. These ends 303a, 304a may also be located in a horizontal plane slightly below, vertically, the rest of the rim 303, 304, for example the thickness of the rear transverse rim 124 of the transverse profile 12: in this way, this rear transverse rim 124 and the horizontal longitudinal rims 303, 304 of the central stringer are substantially in the same horizontal plane.

[0069] When the assembly 10 is secured to the front longitudinal member 2 and the central longitudinal member 3, The transverse profile 12 is then closed by the independent wall 22, then the front longitudinal member 2 and the connecting profile 14 are closed by the installation of the front floor section 5a, and the central longitudinal member is closed by the installation of the central floor section 5b. The order in which the front and central longitudinal members are closed is, of course, irrelevant.

[0070] The assembly 10 according to the invention allows for an efficient transfer of longitudinal forces despite the offset between the longitudinal members. It will be understood that the assembly according to the invention can easily be adapted to different central sections of the subframe: it is sufficient, for example, to position the third spacer in the appropriate position according to the transverse spacing between the longitudinal members.

Claims

Demands

1. Assembly (10) for transferring longitudinal forces from a motor vehicle underbody, characterized in that it comprises: - a transverse profile (12), extending in a transverse direction of the assembly in its operating position, of a hollow U-shaped cross-section with horizontal edges (123, 124) in its operating position, - a longitudinal connecting profile (14), extending perpendicularly to the transverse profile (12), of a hollow U-shaped cross-section with horizontal edges (143, 144), the opening of which is oriented in the same direction as the opening of the hollow shape of the transverse profile, the connecting profile having a rear end fixed vertically and longitudinally to the transverse profile, - at least three longitudinal spacers (16-18) disposed inside the transverse profile (12) and fixed to this one, two of the spacers (16,17) being arranged opposite longitudinal side walls (140, 141) of the connecting profile (14), a third spacer (18) being arranged in another position intended to be situated opposite a longitudinal side wall (300) of a stringer (3) to which the assembly is to be fixed.

2. Assembly (10) according to claim 1, characterized in that it comprises at least two reinforcement elements (19, 21) each having a reinforcement wall (190, 210) bearing against a bottom wall (122) of the transverse profile and secured thereto, and in that each spacer (16-18) is part of a reinforcement element (19, 21) and is connected to the reinforcement wall (190, 210) of a reinforcement element.

3. Assembly (10) according to claim 2, characterized in that the reinforcing wall of each reinforcing element and the bottom wall of the cross profile are pierced with at least one through hole each receiving a welded nut (131, 132).

4. Assembly (10) according to any one of claims 1 to 3, characterized in that the rear end of the connecting profile has rear fixing lugs (145, 146), in that the spacers have front fixing lugs to the cross profile and in that the rear fixing lugs of the connecting profile (14) are located opposite the front fixing lugs of the spacers, on either side of a front side wall (120) of the cross profile.

5. Assembly (10) according to any one of claims 1 to 4, characterized in that it further comprises a first wall (22) assembled to the edges (123, 124) of the transverse profile (12) and closing it and a second wall (5a) assembled to the edges (143, 144) of the connecting profile (14) and closing it.

6. Assembly (10) according to any one of claims 1 to 5, characterized in that the different elements of the assembly are made of metal or metal alloy and are joined together by welding.

7. Underbody (1) of a motor vehicle comprising a front side member (2) and a central side member (3) which are not located in longitudinal extension of each other, each side member (2, 3) having two side walls (200, 201; 300, 301) connected by a bottom wall (202, 302) defining a hollow shape with a U-shaped cross-section, each side wall (200, 201; 301, 302) being provided with a horizontal longitudinal rim (203, 204; 303;304) in operating position, characterized in that it comprises an assembly (10) according to any one of claims 1 to 6 connecting the front spar (2) to the central spar (3), the connecting profile of the assembly having a shape conforming to the internal shape of the front spar (2) and being fixed to the front spar (2), inside the latter, one of the longitudinal spacers (18) of the assembly (10) extending in line with a lateral wall (300) of the central spar (3), a front end of the central spar being fixed to the transverse profile vertically and horizontally.;

8. Base (1) according to claim 7, characterized in that at least one front transverse fixing lug (305, 306) of the central longitudinal member (3) is located opposite, longitudinally, a rear transverse fixing lug (180) of a spacer (18), on either side of a rear side wall (121) of the transverse profile.

9. Base (1) according to claim 7 or 8, having a floor assembled to the edges of the stringers and closing them, characterized in that the connecting profile (14) is closed by a first wall (5a) forming part of the floor and in that the transverse profile (12) is closed by a second wall (22) which is part of the floor or which is an independent wall (22) fixed to the floor.

10. Motor vehicle comprising a subframe (1) according to any one of claims 7 to 9.

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