Construction of a motor vehicle rear end equipped with side and longitudinal elements

Description

[0001] The invention relates to a structure for the rear part of a motor vehicle body equipped with side members and longitudinal members.

[0002] Hybrid vehicles (known as HEVs or PHEVs, Plug-in Hybrid Electric Vehicles) include both a combustion engine connected to a fuel tank and a traction battery. The battery and the tank are generally located at the rear structure of the vehicle body, particularly near the rear axle of the vehicle carrying the rear wheels. Such a rear body structure usually has two side members extending in the longitudinal direction of the vehicle connected to two cross members extending in the transverse direction of the vehicle. The side members and cross members thus form a frame on which the rear axle is fixed. Both the tank and the battery may be located in the immediate vicinity of the rear axle, towards the front of the vehicle.

[0003] In the event of a longitudinal rear impact, it is necessary to ensure the integrity of the tank in order to reduce the risk of leakage and the integrity of the battery in order to reduce repair costs and the risk of fire due to the degradation of the electrical modules internal to the battery.

[0004] There are arrangements for absorbing rear impacts. In particular, document FR3050704A1 describes a rear structure comprising an energy absorption system comprising two longitudinal absorption parts each fixed to a side member, along the latter, and of shorter length than the latter, the end of which located on the rear side of the vehicle is equipped with an energy absorption box also known as a "crash box". Such an energy absorption system intervenes for high-speed impacts (80 km / h) and participates in the absorption of energy after deformation of the side members. This type of energy absorption system therefore does not allow energy to be absorbed from the start of the deformation of the side members. In addition, the use of crash boxes increases the mass and makes the production of the absorption system more complex.Document US20170183037A1 also describes a structure of the rear part of a motor vehicle body comprising two lateral side members as well as two side members extending in the longitudinal direction and each located at a distance from a side member in the transverse direction, the front and rear parts of the latter being connected respectively to front and rear transverse structural elements.

[0005] There is therefore a need for a rear part structure of a motor vehicle body which improves the absorption of rear impacts at high speed and which is simple, inexpensive to produce and without significant excess weight.

[0006] To this end, the invention relates to a structure for the rear part of a motor vehicle body having a longitudinal direction and a transverse direction perpendicular to the longitudinal direction. The structure according to the invention comprises two lateral side members extending in the longitudinal direction, each lateral side member having one end connected to a front transverse structural element and another end connected to a rear transverse structural element, each transverse structural element extending in the transverse direction. According to the invention, the structure further comprises, between the two side members, two longitudinal members extending in the longitudinal direction and each located at a distance from a longitudinal member in the transverse direction, each longitudinal member having one end connected to the front transverse structural element and another end connected to the rear transverse structural element.

[0007] In this arrangement, the side members are thus of the same length as the side members. They are also spaced from the side members in the transverse direction, in particular by a predetermined distance. In other words, the side members are not attached to the side members. The side members are also not fixed to the side members. In particular, each side member can be separated from an adjacent side member by a shorter distance than that separating it from the other side member in the transverse direction.

[0008] It will be noted that the longitudinal and transverse directions of the rear body part structure according to the invention correspond to the longitudinal and transverse directions of the vehicle when the structure is mounted on the vehicle. The front and rear directions correspond to the front and rear directions of the vehicle along this longitudinal direction.

[0009] Thanks to the arrangement according to the invention, the energy of a longitudinal rear impact suffered by a vehicle is absorbed simultaneously by the side members and by the side members, the ends of each being connected to the same transverse structural elements, thus improving the resistance of the rear structure to impacts, in particular to impacts at high speed (for example = at 51 km / h to comply with the requirements of standard NF EN 12767 - October 2011 during a rear impact of a rigid mobile barrier weighing 1100 kg - also called BMR1100 impact).

[0010] Advantageously, each side member can be a profile. It can thus be produced simply and inexpensively. Each side member can in particular have an open U-shaped or Ω-shaped cross-section for greater strength. The opening of this cross-section can in particular be directed towards the top of the vehicle when the rear part structure according to the invention is mounted in the vehicle.

[0011] Such a profile may be made of metallic material, for example steel, in particular stainless steel, aluminum, aluminum alloy or any other suitable metal or metal alloy.

[0012] Generally speaking, the side members can also be profiles, particularly metallic ones, with a similar open cross-section.

[0013] Also generally, the side members, and possibly the side members, can be fixed to a structural element forming a floor on the opening side of their cross-section.

[0014] Advantageously, each side member and side member may comprise at least one member for fixing a rear axle. Such fixing members may be simple orifices for fixing a rear axle by screw, rivet or the like. In particular, each side member may be positioned at a sufficient distance from a lateral side member in the longitudinal direction in order to fix the rear axle to the side member. It is thus possible to fix the rear axle to the rear part structure according to the invention without having to provide specific fixing boxes, thus facilitating assembly and limiting the number of parts.

[0015] According to the invention, the structure comprises, on each side in the transverse direction, a device for receiving a shock absorber spring, this receiving device having one end fixed to a side member and another end fixed to the adjacent side member. The receiving device is thus embedded between a side member and an adjacent side member, which makes it possible to improve its stability by allowing a distribution of the forces exerted by the shock absorber spring between the side member and the adjacent side member. Preferably, for better stability and for simpler fixing, each receiving device can extend in the transverse direction. In particular, each receiving device can have a zone for receiving a shock absorber spring located between the side member and an adjacent side member.

[0016] Advantageously, the transverse structural elements, the side members and the longitudinal members are made of metallic material, for example steel, in particular stainless steel, aluminum, aluminum alloy or any other suitable metal or metal alloy. The longitudinal members are then secured to the transverse structural elements by welding.

[0017] The invention also relates to a motor vehicle having a rear body part structure according to the invention.

[0018] Advantageously, the vehicle comprising a heat engine connected to a fuel tank and a traction battery, the fuel tank is located between the side members and the front and rear transverse structural elements, and the traction battery is located along the front transverse structural element, on the front side of the vehicle.

[0019] A motor vehicle usually has a rear axle comprising a cross member extending in the transverse direction connecting two arms each supporting a wheel. Advantageously, the rear axle can be fixed to both the side members and the side members. This arrangement makes it possible to avoid having to provide additional specific fixings on the rear part structure.

[0020] Usually, a rear axle also has shock absorber springs connected to the rear body structure on each side thereof in the transverse direction. Advantageously, each shock absorber spring may be supported on a receiving device of the rear body structure as described above.

[0021] The invention is now described with reference to the accompanying non-limiting drawings, in which: [ Fig. 1 ] There figure 1 represents a bottom view of a rear body part structure according to an embodiment of the invention on which a rear axle, a traction battery and a fuel tank are fixed. Fig. 2 ] There figure 2 represents a bottom view of the rear part structure shown figure 1 . [ Fig. 3 ] There figure 3 represents a perspective view of a spar. Fig. 4 ] There figure 4 represents a perspective view from below of a detail of the rear part structure shown figures 1 et 2 .

[0022] In this description, the terms front, rear, upper, lower, refer to the front and rear directions of the vehicle, when the vehicle body rear part structure is mounted on the vehicle. The X, Y, Z axes, correspond respectively to the longitudinal (front to back), transverse and vertical axis of the vehicle, the latter resting on the ground. The vertical direction thus corresponds to the direction of gravity.

[0023] There figure 1 represents in a bottom view a structure 1 of the rear part of a motor vehicle on which are fixed a rear axle 2, a traction battery 3 and a fuel tank 4, the latter being intended to supply a thermal engine not shown. The traction battery 3 and the fuel tank 4 are arranged in front of the rear axle 2 in the longitudinal direction X of the vehicle.

[0024] The structure 1 of the rear part of a motor vehicle comprises a left side rail 10 and a right side rail 11 each extending in the longitudinal direction X of the vehicle. These side rails 10, 11 are connected to each other by a front transverse structural element 12 and a rear transverse structural element 13 so as to form a rigid frame. In other words, each side rail has a front end connected to the front transverse structural element and a rear end connected to the rear transverse structural element 13.

[0025] Generally, the rear transverse structural element 13 may have a closed hollow cross-section. Such an element may contribute to the torsional resistance of the rear portion structure and limit rolling vibrations. This type of rear transverse structural element is, for example, located along the rear opening of the trunk of the vehicle.

[0026] Generally, whatever the embodiment, the rear portion structure 1 may further have a rear end cross member 20, located behind the rear transverse structural element 13 and intended to receive and absorb impacts at low speed (for example less than 10 km / h to meet the impact protocols prescribed by the Euro NCAP (European New Car Assessment Program) and RCAR (Research Council for Automobile Repairs) organizations, as shown in the example. This rear end cross member 20 is connected in the usual manner to the side rails 10, 11, here by connecting elements 20a, 20b each extending in the extension of a side rail.

[0027] According to the invention, the structure 1 of the rear part of a motor vehicle comprises two side members 14, 15 each extending in the longitudinal direction of the vehicle near a side member 10, 11. Thus, the structure 1 of the rear part has a left side member 14 and a right side member 15. These side members are located at a distance from the side members in the transverse direction. This distance may be determined by a person skilled in the art as a function of the distance separating the side members, the position of the rear axle attachments as described below, and / or the technical elements to be housed possibly between the side members and / or between a side member and an adjacent side member. Advantageously, for better distribution of shock absorption, each of the side members may be located at the same distance from the transversely adjacent side member.

[0028] Each longitudinal member 14, 15 further extends between the front 12 and rear 13 transverse structural elements and is connected to them. Thus, each longitudinal member 14, 15 has a front end connected to the front transverse structural element 12 and a rear end connected to the rear transverse structural element 13. The longitudinal members 14, 15 are therefore of the same length as the longitudinal members 10, 11.

[0029] In the example, each longitudinal member is located between the middle of the rear part structure 1 and a lateral longitudinal member along the transverse direction Y. Preferably, each of the longitudinal members is closer to a lateral longitudinal member than to the other longitudinal member and in particular than to the center of the rear part structure 1 along the transverse direction Y. This makes it possible to provide a space between the longitudinal members 14, 15 large enough to accommodate one or more technical elements, such as the fuel tank 4 in the example described.

[0030] In the embodiment described, each spar 14, 15 is a metal profile having an open U-shaped or Ω-shaped cross-section, here in Ω, as can be seen more clearly figure 3 . It will be noted that the opening of this cross-section is directed towards the top of the vehicle. In the example, this opening is closed by a structural element forming a floor 5 extending above the side members and side members and shown figure 4 .

[0031] Advantageously, the side members 10, 11 are also metal profiles having, for example, an open cross-section similar to that of the side members 14, 15, also closed by the structural element forming the floor 5.

[0032] In the example, each side member 10, 11 and each side member 14, 15 also has at least one member for fixing a rear axle. Here, each side member 10, 11 has two fixing members 101, 102, 111, 112 and each side member 14, 15 has a fixing member 141, 151 respectively. These fixing members 101, 102, 111, 112, 141, 145 are here simple orifices allowing the passage of screws, rivets, or the like. Of course, the invention is not limited by the number of fixings provided on the side members and side members to ensure the fixing of the rear axle.

[0033] According to the invention, the rear part structure 1 also has, on each side, a receiving device 16, 17 for a shock absorber spring, each of the receiving devices 16, 17 having one end fixed to a side member and another end fixed to the adjacent side member. Such an arrangement of the receiving devices 16, 17 allows them to participate in maintaining the geometry of the side members. In addition, the forces undergone by each of the receiving devices 16, 17 are distributed between the side member and the adjacent side member to which these devices are fixed. These receiving devices 16, 17 are here in the form of profiles with an open cross-section in the shape of an Ω whose opening is also directed towards the top of the vehicle (and can also be closed by the structural element forming the floor 5). The bottom of each profile 16, 17 has a zone 161, 171 for supporting a shock absorber spring ( figure 4 ). These zones 161, 171 extend here in the same horizontal plane as the surfaces of the side members and longitudinal members.

[0034] Advantageously, the transverse structural elements, the side members and the side members of the rear part structure 1 are made of metallic material, as are the receiving devices 16, 17. These different elements can thus be secured to each other by welding, which makes it possible to simplify the production of the rear part structure 1 according to the invention.

[0035] Depending on requirements, it will be noted that the longitudinal members 14, 15 can be extended at one of their ends or at each of their ends, by a section of profile of the same shape. It is thus possible to produce rear part structures 1 of different lengths by using longitudinal members of fixed length produced in series, the length of each longitudinal member being adapted to the length of the structure 1 by adding one or more sections of profiles of adapted length. In the example, each longitudinal member 14, 15 is extended on the side of its rear end by a section of profile. A section of profile 142 is visible figure 3 for the side member 14. It will be noted that the section of profile 142 can also be used to fix the side member to the rear transverse structural element 13.

[0036] As can be seen on the figure 1 , the rear part structure 1 receives a rear axle 2 for attachment. This has a cross member 21 extending in the transverse direction connecting two arms 22, 23 each supporting a wheel 24, 25. A shock absorber spring 26, 27 extends between the rear axle and the rear part structure (only the lower receiving areas of the shock absorber springs are visible). figure 1 ), on each side transversely of the rear axle 2.

[0037] The arms 22, 23 of the rear axle 2 are fixed to the side members 14, 15 and to the side members 10, 11 by the fixing members thereof. The rear axle 2 is thus fixed to the structure 1 only via the side members and side members so that it is not necessary to provide separate specific fixing devices to fix it to the structure.

[0038] Each shock absorber spring also rests on a receiving device 16, 17 of the rear part structure.

[0039] In the event of a rear impact, the rear end cross member 20 will first deform. If the rear impact is at low speed (for example <10 km / h), only the rear end cross member deforms and must be replaced for repair. If the rear impact is at high speed (for example =51 km / h), the rear end cross member continues to deform until it comes to bear against the rear transverse structural element 13. From then on, the side members 10, 11 and the side members 14, 15 deform simultaneously and absorb the energy of the impact. For repair, it will then be necessary to replace each of the elements deformed by the impact.

[0040] Of course, the invention is not limited to the embodiment described. In particular, although this is less advantageous for limiting repair costs, the rear transverse structural element could form a rear end cross member. The deformation of the side members and longitudinal members then occurs from the start of a low-speed impact.

Claims

1. Motor vehicle body rear part structure (1) having a longitudinal direction and a transverse direction perpendicular to the longitudinal direction, said structure comprising two lateral spars (10, 11) extending in the longitudinal direction, each lateral spar having one end connected to a front transverse structural element (12) and another end connected to a rear transverse structural element (13), each transverse structural element (12, 13) extending in the transverse direction, the structure (1) comprising, between the two spars (10, 11), two auxiliary spars (14, 15) extending in the longitudinal direction and each located at a distance from a spar (10, 11) in the transverse direction, each auxiliary spar (14, 15) having one end connected to the front transverse structural element (12) and another end connected to the rear transverse structural element (13), the structure being characterized in that the auxiliary spars are of the same length as the lateral spars, and in that the structure has, on each side in the transverse direction, a device (16, 17) for receiving a shock absorber spring having one end attached to a spar (10, 11) and another end attached to the adjacent auxiliary spar (14, 15).

2. Rear part structure (1) according to Claim 1, characterized in that each auxiliary spar (14, 15) is a section.

3. Rear part structure (1) according to Claim 2, characterized in that each auxiliary spar (14, 15) is a section having an open, U- or Q-shaped cross section.

4. Rear part structure (1) according to any one of Claims 1 to 3, characterized in that each spar (10, 11) and each auxiliary spar (14, 15) has at least one attachment member (101, 102, 111, 112, 141, 151) for a rear axle assembly.

5. Rear part structure (1) according to any one of Claims 1 to 4, characterized in that each receiving device (16, 17) extends in the transverse direction.

6. Rear part structure (1) according to any one of Claims 1 to 6, characterized in that the transverse structural elements (12, 13), the spars (10, 11) and the auxiliary spars (14, 15) are made of metallic material and in that the auxiliary spars are secured to the transverse structural elements by welding.

7. Motor vehicle having a body rear part structure (1) according to any one of Claims 1 to 6.

8. Motor vehicle according to Claim 7, comprising a heat engine connected to a fuel tank (4) and a traction battery (3), characterized in that the fuel tank (4) is located between the auxiliary spars (14, 15) and the front and rear transverse structural elements, and the traction battery is located along the front transverse structural element, on the front side of the vehicle.

9. Motor vehicle according to Claim 7 or 8, comprising a vehicle rear axle assembly (2) having a crossmember (21) extending in the transverse direction and connecting two arms (22, 23) each supporting a wheel (24, 25) and a shock absorber spring (26, 27) connected to the rear part structure, characterized in that the rear axle assembly is attached to the auxiliary spars (14, 15) and to the spars (10, 11) and, optionally, each shock absorber spring (26, 27) is supported on a receiving device (16, 17) of the rear part structure (1).