Reinforced motor vehicle side member and underbody assembly including such a side member

Abstract

Reinforced motor vehicle side member and underbody assembly comprising such a side member. The invention relates to a longitudinal side member (7d) of a vehicle underbody assembly, comprising a longitudinal hollow body and a reinforcement device comprising a honeycomb structure (19) comprising a plurality of tubes (21), said honeycomb structure being arranged transversely relative to said longitudinal hollow body. According to the invention, at least two of said tubes (21) each have an attachment interface, said attachment interfaces being adapted to cooperate with each other. Figure 9

Description

Title of the invention: Reinforced motor vehicle side member and underbody assembly comprising such a side member. 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 side impact and frontal impact.

[0002] The invention relates more particularly to a longitudinal side member of a motor vehicle underbody assembly and an underbody assembly comprising such a side member. 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] The body structure includes, in particular, among these sheet metal elements, a left side structure and a right side structure. Each side structure includes 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.

[0005] The lower horizontal elements include lateral longitudinal stringers defining part of the perimeter of the body underbody.

[0006] The left and right side structures are connected to each other in the lower part of the vehicle by a floor, belonging to a vehicle underbody assembly and bordered laterally by the right and left longitudinal side members.

[0007] The underbody assembly defines a vehicle base which is used to receive vehicle design elements, called "silhouettes", which vary according to the dimensions of the vehicle.

[0008] Among the plurality of tests used for the homologation of motor vehicles, a side impact test is carried out, in particular in order to reveal performance criteria relating to the protection of occupants.

[0009] Among the different types of side impacts, a so-called "pole" impact consists of projecting the motor vehicle at a speed of approximately 30 km / h laterally against a rigid pole, so that the vehicle defines an angle of approximately 75° relative to the pole.

[0010] During a side impact, the post becomes embedded in the motor vehicle, at the level of the front door, driver's side or passenger's side.

[0011] The impact absorption capacities at the level of the vehicle's entire underbody are, in part, conferred by the longitudinal side members, which take up part of the forces occurring when the vehicle is subjected to such a side impact.

[0012] Similarly, when the vehicle is subjected to a frontal impact, the impact absorption capacities at the level of the entire underbody are partly conferred by the lateral longitudinal members.

[0013] A recurring problem is therefore to increase the capacity of longitudinal stringers to absorb the forces.

[0014] Also, when the vehicle is a battery electric vehicle (BEV), the vehicle includes a traction battery that powers the electric motor. The traction battery comprises a set of battery modules mounted in a battery tray. The battery tray is mounted under the floor of the underbody assembly. The battery tray defines one of the silhouettes integrated into the underbody assembly when the vehicle is an electric vehicle. The dimensions of the battery tray vary depending on the dimensions of the vehicle.

[0015] When the motor vehicle is subjected to a side impact, the electric battery must be protected in order to prevent damage to the battery and to limit the risk of fire.

[0016] Therefore, there is a need to reinforce the lateral longitudinal stringers, particularly when the vehicle is an electric motor vehicle with a battery.

[0017] Also, when the motor vehicle is electric, the absorption capacities of the longitudinal side members must be further increased, the mass of an electric vehicle being much greater than that of a thermal vehicle.

[0018] A known prior art solution consists of using an extruded aluminum alloy reinforcement element, which connects the battery to the longitudinal side rails.

[0019] However, machining such a solid aluminum reinforcement element is complex and generates material loss.

[0020] Therefore, a solution using longitudinal aluminum and steel side members is not satisfactory. Indeed, such a solution would add mass to the vehicle, which would run counter to the general and recurring problem of reducing the mass of a motor vehicle.

[0021] We also know of document EP 3 747 736 A1 which discloses a longitudinal side member reinforcement device for a motor vehicle underbody assembly, the reinforcement device comprising a set of profiles in honeycomb structures stacked transversely throughout the volume of the spar.

[0022] The presence of the honeycomb profiles makes it possible to structurally reinforce the longeron, while limiting its mass.

[0023] However, the honeycomb profiles are stacked throughout the volume of the spar, that is to say over the entire length and height of the spar.

[0024] Thus, the reinforcement device is bulky and is identical regardless of the silhouette carried by the base assembly.

[0025] Consequently, the arrangement of the reinforcement device in the longitudinal side member is not optimized according to the type of silhouette. Description of the invention

[0026] The present invention aims to overcome the aforementioned drawbacks, and for this purpose relates to a longitudinal side member of a motor vehicle underbody assembly, said side member comprising a longitudinal hollow body and a reinforcement device for said longitudinal hollow body, said reinforcement device comprising a honeycomb structure comprising a plurality of tubes, said honeycomb structure being arranged transversely relative to said longitudinal hollow body, said side member being notable in that at least two of said tubes of said honeycomb structure each have an attachment interface, said attachment interfaces being adapted to cooperate with each other.

[0027] Thus, by providing a longitudinal side stringer comprising a reinforcement device comprising a honeycomb structure comprising a plurality of tubes among which at least two of said tubes each have an attachment interface, said attachment interfaces being adapted to cooperate with each other, the tubes of the honeycomb structure can be attached relative to each other.

[0028] In this way, the tubes can be integrated in a modular way into the longitudinal side member.

[0029] The reinforcement of the longitudinal lateral stringer is thus managed in a personalized manner, unlike the prior art where the reinforcement of the longitudinal lateral stringer is carried out regardless of the silhouette retained.

[0030] This prevents the honeycomb structure from occupying the entire length and height of the longitudinal side member, as is the case in the prior art.

[0031] It is thus possible to limit the volume of the longitudinal member, in particular in a transverse direction, which makes it possible to gain battery volume when the motor vehicle is electric, and therefore to optimize the vehicle's range.

[0032] According to optional features of the longeron according to the invention: - each of said tubes comprises a peripheral wall defining a tubular hollow body, and each of said attachment interfaces is arranged outside said peripheral wall of said tubes; - at least one of the said tubes of the said honeycomb structure is filled at least in part with aluminum foam; - several of the said tubes of the said honeycomb structure are filled at least in part with aluminium foams of different densities; - said attachment interfaces cooperate with each other by interlocking; - the longeron includes an outer closing envelope, contained within said longitudinal hollow body, said outer closing envelope enclosing said reinforcement device; - the set of said tubes of said honeycomb structure extends over a length equal to the thickness of said stringer; - at least one of said tubes of said honeycomb structure extends over a length less than the thickness of said stringer; - said plurality of tubes of said honeycomb structure defines a plurality of levels, each of said levels comprising at least one of said tubes.

[0033] The invention also relates to a motor vehicle underbody assembly, comprising: - a floor, - lateral longitudinal stringers, laterally bordering said floor, said substructure being remarkable in that at least one of said lateral longitudinal stringers is according to the invention. Brief description of the drawings

[0034] 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:

[0035] [Fig-1] shows a subframe assembly of a motor vehicle according to The invention, seen in perspective from below.

[0036] [Fig.2] is a cutaway view in partial perspective of a long lateral spar gitudinal of the entire substructure of the invention.

[0037] [Fig.3] shows a front view of the longitudinal side member, the hollow body of said longeron having been obscured.

[0038] [Fig.4] is a perspective view of one of the tubes of the honeycomb structure of the longitudinal side member reinforcement device.

[0039] [Fig. 5] is a perspective view of an example of an assembly of several tubes between them, forming one layer of the honeycomb structure.

[0040] [Fig.6] shows a first example of the embodiment of the longitudinal side member seen at zone A of [Fig.2], a portion of the outer closure envelope is obscured for better visibility.

[0041] [Fig.7] is a view similar to [Fig.6], the longitudinal side member being according to a second example of implementation.

[0042] [Fig.8] is a view similar to [Fig.6], the longitudinal side member being according to a third example of implementation.

[0043] [Fig.9] is a cross-sectional view along line BB of [Fig.3], the long side member gitudinal being according to a fourth example of realization.

[0044] [Fig. 10] is a view similar to [Fig. 9], the longitudinal side member being according to a fifth example of implementation.

[0045] [Fig. 11] shows, in top view and in section, an example of integration of the longitudinal side member in a motor vehicle underbody assembly. Description of the implementation methods

[0046] In the following description, elements having an identical structure or analogous functions are designated by the same reference.

[0047] 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.

[0048] In what follows, the terms "left", "right", "lower" and "upper" are understood in relation to the vehicle.

[0049] 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.

[0050] Reference is made to [Fig.1] showing a subframe assembly 1 of a motor vehicle 3, seen in perspective from below.

[0051] The underbody assembly 1 belongs to a body structure comprising a set of sheet metal structural elements providing rigidity to the motor vehicle 3, assembled together and forming the framework of the motor vehicle.

[0052] Among these sheet metal elements, the body structure comprises a left side structure 5g and a right side structure 5d.

[0053] The box structure admits a longitudinal median plane of symmetry. Thus, the description made for the left lateral structure 5g applies by analogy to the right lateral structure of the box structure.

[0054] 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 cash register.

[0055] The lower horizontal elements comprise lateral longitudinal stringers 7g, 7d extending substantially longitudinally relative to the motor vehicle 3.

[0056] At the front, the longitudinal side members 7g, 7d are connected to a front block 9 of the motor vehicle 3. At the rear, the longitudinal side members 7g, 7d are connected to the rear axle 11 of the motor vehicle 3.

[0057] The left and right lateral structures 5g, 5d are connected to each other in the lower part of the motor vehicle 3 by a floor 13.

[0058] In the embodiment illustrated in the figures, the motor vehicle 3 is a battery electric vehicle (BEV, an acronym for "Battery Electric Vehicle"). To this end, the motor vehicle 3 includes a traction battery (not shown) powering the electric motor (not shown) of the motor vehicle 3.

[0059] The traction battery comprises a set of battery modules, mounted in a battery tray mounted under the floor 13.

[0060] Reference is made to [Fig.2], which is a cutaway view in partial perspective of the longitudinal lateral spar 7d.

[0061] The longitudinal side member 7d includes a longitudinal hollow body 15 extending substantially longitudinally relative to the motor vehicle 3 when the longitudinal side member 7d is mounted in the motor vehicle 3.

[0062] The longitudinal side member 7d further includes a reinforcement device 17 for the longitudinal hollow body 15, comprising a honeycomb structure 19 comprising a plurality of tubes 21.

[0063] The honeycomb structure 19 is arranged transversely relative to the longitudinal hollow body 15.

[0064] In other words, the tubes 21 extend transversely relative to the longitudinal hollow body 15, that is to say they extend transversely relative to the motor vehicle 3 when the longitudinal side member 7d is mounted in the motor vehicle 3.

[0065] In the embodiment illustrated in the figures, the longitudinal side member 7d has an outer closing envelope 23, contained inside the longitudinal hollow body 15 and enclosing the reinforcement device 17, and whose function is explained in the rest of the description.

[0066] Reference is made to [Fig.3] showing a front view of the longitudinal side member 7d, the hollow body 15 having been obscured.

[0067] The outer closing envelope 23 comprises an outer closing half-envelope 23a and an outer closing half-envelope 23b which can by for example, it can be made of aluminum sheet metal.

[0068] The fixing between the outer closing half-shells 23a, 23b can, for example, be carried out at the fixing points 22, 24 by means of weld beads and / or by gluing and / or by electric welding points and / or by screws, etc.

[0069] In an embodiment not shown in the figures, the longitudinal side member 7d does not have any external closing envelope 23, the reinforcement device 17 then being contained directly in the longitudinal hollow body 15.

[0070] Reference is made to [Fig.4] showing in perspective one of the tubes 21 of the honeycomb structure 19 of the reinforcement device 17.

[0071] The tube 21 constitutes a primary element of the honeycomb structure 19. The tube 21 has a peripheral wall 25, defining a tubular hollow body.

[0072] The primary element of the honeycomb structure 19 defined by the tube 21 can, for example, be made of metallic material such as aluminium.

[0073] The tube 21 can, for example, be manufactured by extruding aluminum, then by cutting according to the need, in order to allow modularity of the tubes in terms of height.

[0074] The characteristics of the tubes 21 are configurable according to the vehicle in which they are mounted. For example, the wall thickness of the tube 21 is adjustable, as is the width of the tube 21.

[0075] Also, the shape of each tube 21 is adapted to give stiffness to the whole honeycomb structure 19.

[0076] In the embodiment illustrated in the figures, the tubes 21 have a substantially hexagonal geometric shape, in the shape of a honeycomb.

[0077] According to an alternative embodiment not shown, the tubes 21 have a different geometric shape, for example circular, polygonal, for example rectangular, etc.

[0078] Also, not all the tubes 21 of the honeycomb structure 19 are necessarily identical. For example, some tubes 21 may be hexagonal in shape with a certain thickness and width while other tubes 21 of the same honeycomb structure 19 may have a different geometric shape, with a thickness and / or width that may be different, etc.

[0079] According to the invention, at least two of the tubes 21 of the honeycomb structure 19 each have an attachment interface 27.

[0080] The attachment interfaces 27 are adapted to cooperate with each other, so as to allow two tubes 21 to be attached to each other.

[0081] Thus, thanks to the present invention, the tubes 21 of the honeycomb structure 19 can be attached relative to each other.

[0082] In this way, the tubes 21 can be integrated in a modular way into the longitudinal side member.

[0083] The reinforcement of the longitudinal lateral stringer is thus managed in a personalized manner, unlike the prior art where the reinforcement of the longitudinal lateral stringer is carried out regardless of the silhouette retained.

[0084] This prevents the honeycomb structure from occupying the entire length and height of the longitudinal side member, as is the case in the prior art.

[0085] It is thus possible to limit the volume of the side member, in particular in a transverse direction, which makes it possible to save battery volume when the motor vehicle is electric, and therefore to optimize the vehicle's range.

[0086] In the embodiment illustrated in the figures, each of the attachment interfaces 27 is arranged outside the peripheral wall 25 of the tube 21, which makes the attachment interfaces 27 easily manipulable.

[0087] In the embodiment illustrated in the figures, the attachment interfaces 27 cooperate with each other by interlocking, or by clipping.

[0088] However, according to an alternative embodiment not shown in the figures, the attachment interfaces 27 can cooperate with each other by any other type of connection, for example by means of glue, welding, etc.

[0089] When the attachment interfaces 27 cooperate with each other by interlocking, the attachment interfaces 27 may, for example, include a male attachment interface 29 and a female attachment interface 31.

[0090] The male attachment interfaces 29 and / or the female attachment interfaces 31 can be obtained during the extrusion of the tube 21.

[0091] In the embodiment illustrated in the figures, the tube 21 has three male attachment interfaces 29 and three female attachment interfaces 31.

[0092] As shown in [Fig.5], several tubes 21 are nested together so that the male attachment interface 29 of one of the tubes 21 cooperates with the female attachment interface 31 of another of the tubes 21. This gives a stage 33 of the honeycomb structure 19.

[0093] Reference is made to [Fig.6] showing a first example of the realization of the longitudinal side member 7d seen at the level of zone A of [Fig.2], the outer closing half-envelope 23b having been obscured for better visibility.

[0094] In the embodiment example given in [Fig.6], some tubes 21 of the honeycomb structure 19 are filled with an aluminum foam 35.

[0095] The tubes 21 into which the aluminum foam 35 is introduced are chosen according to the required stiffness of the area of ​​the vehicle considered. In this way, the reaction of the longitudinal side member to an impact is controlled as precisely as possible.

[0096] Due to the presence of pores, aluminum foam is lighter than aluminum, which makes it possible to give stiffness to the longitudinal side member while limiting the mass of the side member, and therefore of the motor vehicle, which makes it possible to optimize the vehicle's range, in particular when the vehicle is electric.

[0097] The tubes 21 containing aluminum foam 35 can be filled completely or only partially by the aluminum foam 35.

[0098] Also, depending on the stiffness requirement, it is envisaged within the framework of the invention to use aluminium foams 35 of identical or different densities to fill the tubes 21 of the honeycomb structure 19.

[0099] The aluminum foam used in the context of the present invention may be recyclable and / or derived from recycling.

[0100] The aluminum foam expands when the body structure undergoes a curing phase, subsequent to a phase of application of a cataphoresis treatment used to combat corrosion.

[0101] In this regard, the cataphoresis step involves immersing the vehicle body structure in a bath used to combat corrosion. This treatment ensures a uniform coating over the entire vehicle body structure.

[0102] When exiting this bath, the cataphoresis is evacuated by gravity.

[0103] The presence of the outer closing envelope 23, contained inside the longitudinal hollow body 15 and enclosing the reinforcement device 17, prevents the cataphoresis from entering the tubes 21 of the honeycomb structure 19. In this way, the cataphoresis is prevented from remaining trapped in the pores of the aluminum foam 35 when the box structure comes out of the cataphoresis bath.

[0104] The fixing of the honeycomb structure 19 onto the outer closing envelope 23 can, for example, be carried out by gluing or by welding.

[0105] Reference is made to [Fig.7] showing a second example of embodiment of the longitudinal side member 7d seen at the level of zone A of [Fig.2], the outer closing half-envelope 23b being obscured for better visibility.

[0106] In the embodiment illustrated in [Fig. 7], all the tubes 21 of the honeycomb structure 19 extend over a length Li equal to the thickness E (shown in Figures 2 and 11) of the longitudinal side member 7d. The thickness E of the longitudinal side member 7d is defined by the width of the longitudinal side member 7d in the transverse direction.

[0107] Reference is made to [Fig.8] showing a third example of embodiment of the longitudinal side member 7d seen at the level of zone A of [Fig.2], the outer closing half-envelope 23b being obscured for better visibility.

[0108] According to the embodiment illustrated in [Fig. 8], several of the tubes 21 of the honeycomb structure 19 extend over a length L2 less than the thickness E of the longitudinal side beam 7d.

[0109] Alternatively, only one of the tubes 21 of the honeycomb structure 19 can extend over a length L2 less than the thickness E of the longitudinal lateral stringer 7d.

[0110] Reference is made to [Fig.9], which is a cross-sectional view along line BB of [Fig.3], showing a fourth example of the embodiment of the longitudinal lateral stringer 7d.

[0111] In the embodiment illustrated in [Fig.9], the tubes 21 of the honeycomb structure 19 define three stages 33, each stage 33 comprising several tubes 21. The number of stages 33 can be adapted at will, in particular according to the need in terms of stiffness.

[0112] In [Fig.9], the floors 33 are joined together. However, in an alternative embodiment illustrated in [Fig. 10], which is a cross-sectional view along line BB of [Fig.3], the floors can be separated, i.e., in this case there is no direct connection between the floors 33.

[0113] Reference is made to [Fig.1 1] showing an example of integration of the longitudinal side member 7d, in top view and in section, in a subframe assembly 1 of a motor vehicle comprising a sliding side door (not shown).

[0114] The sliding side door moves along a slide 37. The slide 37 is fixed to the longitudinal side member 7d by means of a fixing plate 39 mounted inside the longitudinal side member 7d.

[0115] To do this, the tubes 21 of the honeycomb structure 19 extend, at the location intended to receive the fixing plate 39 of the slide 37, over a length L3 less than the thickness E of the longitudinal lateral stringer 7d.

[0116] Thus, thanks to the present invention, it is possible to easily manage areas of the motor vehicle where it is necessary to integrate elements on the longitudinal side member 7d.

[0117] As will be understood, the present invention is not limited to the embodiments of this longitudinal member and subframe assembly described above solely as illustrative examples, but on the contrary encompasses all variants involving the technical equivalents of the means described and their combinations if these fall within the scope of the invention.

Claims

Demands

1. Longitudinal side member (7d, 7g) of a motor vehicle (3) underbody assembly (1), said side member (7d, 7g) comprising a longitudinal hollow body (15) and a reinforcement device (17) of said longitudinal hollow body (15), said reinforcement device (17) comprising a honeycomb structure (19) comprising a plurality of tubes (21), said honeycomb structure (19) being arranged transversely relative to said longitudinal hollow body (15), said side member (7d, 7g) being characterized in that at least two of said tubes (21) of said honeycomb structure (19) each have an attachment interface (27), said attachment interfaces (27) being adapted to cooperate with each other.

2. Longeron (7d, 7g) according to claim 1, in which each of said tubes (21) comprises a peripheral wall (25) defining a tubular hollow body, characterized in that each of said attachment interfaces (27) is arranged outside said peripheral wall (25) of said tubes (21).

3. Longeron (7d, 7g) according to any one of claims 1 or 2, characterized in that at least one of said tubes (21) of said honeycomb structure (19) is filled at least in part with an aluminium foam (35).

4. Longeron (7d, 7g) according to claim 3, characterized in that several of said tubes (21) of said honeycomb structure (19) are filled at least in part with aluminium foams (35) of distinct densities.

5. Longeron (7d, 7g) according to any one of claims 1 to 4, characterized in that said attachment interfaces (27) cooperate with each other by interlocking.

6. Longeron (7d, 7g) according to any one of claims 1 to 5, characterized in that it comprises an outer closing envelope (23), contained within said longitudinal hollow body (15), said outer closing envelope (23) enclosing said reinforcement device (17).

7. Spar (7d, 7g) according to any one of claims 1 to 6, characterized in that the set of said tubes (21) of said honeycomb structure (19) extends over a length (LJ) equal to the thickness of said spar (7d, 7g).

8. Spar (7d, 7g) according to any one of claims 1 to 6, characterized in that at least one of said tubes (21) of said honeycomb structure (19) extends over a length (L2, L3) less than the thickness of said spar (7d, 7g).

9. Longeron (7d, 7g) according to any one of claims 1 to 8, characterized in that said plurality of tubes (21) of said honeycomb structure (19) defines a plurality of stages (33), each of said stages (33) comprising at least one of said tubes (21).

10. Underbody assembly (1) of a motor vehicle (3), comprising: - a floor (13), - longitudinal side members (7g, 7d), laterally bordering said floor (13), said underbody assembly (1) being characterized in that at least one of said longitudinal side members (7d, 7g) is according to any one of claims 1 to 9.

Images