FR3142737A1 - Vehicle comprising a central rear longitudinal reinforcement - Google Patents

Abstract

The invention relates to a vehicle comprising a rear chassis (1) having two side beams (2) oriented in the longitudinal direction (x) of the vehicle between which is arranged, in parallel, a central rear longitudinal reinforcement (5), extending between the rear crossmember (3) of the chassis (1) and the rear panel (4) of the vehicle. The invention consists in that the central rear longitudinal reinforcement (5) is made up of two assembled elements, the first element extending from the rear crossmember (3) of the chassis (1), having a stiffness such that it constitutes a rigid front part of said central rear longitudinal reinforcement and a second element, assembled at the end of the first element, extending from said end of the first element to the rear panel (4) of the vehicle, having a stiffness lower than that of the first element and constituting a rear deformable part of said central rear longitudinal reinforcement (5). Figure 1

Description

Vehicle including a central rear longitudinal reinforcement

The invention relates to the field of vehicle safety, more specifically during rear impacts, and more particularly concerns vehicles with restricted rear space between the seats in the last row and the rear panel.

The rear chassis of a vehicle is a lower structure that supports the rear part of the vehicle. The latter generally consists of two side beams extending in the longitudinal direction of the vehicle and connected to each other by at least one cross member and the rear panel of the vehicle. The space of the vehicle thus defined and supported by the cross members and the side beams generally corresponds to the trunk.

In the event of an impact at the rear of the vehicle, in particular an impact at high speed, the rear chassis and in particular the rear crossmember will be caused to deform in the forward direction. This deformation will cause elements to enter the passenger compartment that may injure the passengers seated in the rear. In order to limit this intrusion, a rear impact absorption device may be present at the rear chassis and comprises, in a known manner, a central beam arranged between the two side beams and connecting the rear crossmember to the rear panel. This central beam absorbs the energy of the impact by means of longitudinal deformation.

However, in the case of vehicles with row 3 or even row 2 seats, especially in small vehicles, the area that can be deformed, behind the seat mountings is very limited. As a result, a simple longitudinal reinforcement of this type does not work in the event of a high-speed rear impact.

In fact, there is no deformation of the longitudinal reinforcement while there is a significant deformation of the structure in front of the seats of row 3. This makes the vehicle not homologable. In fact, there is a displacement criterion in X (longitudinal axis of the vehicle) of the projection on the floor of the attachment point of the seats of row 3. In the event of residual displacement greater than 75 mm, homologation is not possible.

In document US-B-6 206 461, a vehicle with three rows of seats is described, the second and third rows being back to back, the passengers of row 3 are therefore facing the rear of the vehicle, their legs being housed in the space between the seats and the rear panel of the vehicle. It is therefore proposed to install an additional beam between the rear crossmember and the rear panel of the vehicle to limit the deformation at the level of the leg space of the passengers of the ^3rd row. Such a device therefore consists of a central beam whose front end gradually flares out laterally and the rear end widens in a stepped manner. The configuration of this central beam ensures good lateral support against each crossmember and panel limits the deformation zone at the level of the passengers' feet. However, in the case of a vehicle where the passengers are seated facing the front of the vehicle, the space between the seats and the rear of the vehicle is much smaller and the device described is no longer applicable.

Document US-A-2021/028441 proposes a central reinforcement beam also extending between the rear crossmember and the rear panel of a vehicle. This beam consists of two cylinders of rectangular section, one being engageable in the other with a projecting part. This beam therefore has a double-walled part corresponding to the two cylinders engaged in each other while a part consists of a single wall corresponding to the cylinder of greater length. Thus, the beam has on the double-wall side, a part more rigid than the single-wall part which can constitute a deformable energy absorption zone, fixing plates being further provided at its ends. Thus, this beam makes it possible to limit the deformation in the event of a rear impact by a programmed deformation of the rear part. However, such a beam, due to its double-cylinder structure, has a major drawback in that it increases the weight of the vehicle.

The invention therefore aims to overcome the aforementioned drawbacks of the prior art by proposing a central rear longitudinal reinforcement of the rear chassis having better control in the event of longitudinal deformation, while being of a simpler structure and of a mass which does not impact the mass of the vehicle.

For this purpose, the invention relates to a vehicle comprising a rear chassis having two lateral beams oriented in the longitudinal direction of the vehicle between which is arranged, in parallel, a central rear longitudinal reinforcement, extending between the rear crossmember of the chassis and the rear panel of the vehicle, the invention consists in that the central rear longitudinal reinforcement comprises two assembled elements, the first element extending from the rear crossmember of the chassis, having a stiffness such that it constitutes a rigid front part of said central rear longitudinal reinforcement and a second element, assembled at the end of the first element, extending from said end of the first element to the rear panel of the vehicle, having a stiffness lower than that of the first element and constituting a deformable rear part of said central rear longitudinal reinforcement.

Thus, advantageously, the reinforcement being made up of two elements assembled in the extension of one another, a precise function is simply defined on each element, that is to say that the first element is given a stiffness allowing it to resist deformation under the effect of a rear impact, and for the second element a controlled deformability under the effect of a rear impact. Thus advantageously, the junction zone between these two elements makes it possible to determine a deformation zone of the reinforcement at the rear of the vehicle following the rear impact, while limiting the compression during the impact in this zone or space which can be restricted, to prevent deformation beyond a certain distance inside the passenger compartment and thus protect the passengers in the passenger compartment.

Advantageously, the reinforcement according to the invention can be used in vehicles having a small space between the last row of seats (row 2 or 3 seat) and the rear panel of said vehicle, the first element constituting the rigid front part of said reinforcement then preferably extending from the rear crossmember to the level of the seat attachment point and the second element then extending from the end of the first element to the rear panel of the vehicle, defining the rear deformable part of the reinforcement between the seats of the last row and the rear panel. In this way, the compression deformation linked to a rear impact is allowed on the area defined between the seats and the rear panel and this deformation is blocked beyond (towards the front of the vehicle) the seats, thus limiting the deformation of the passenger compartment.

Preferably, the central rear longitudinal reinforcement has the shape of a U-shaped profile, comprising at least one wall constituting the web of the U and two side walls, this U-shaped profile being made up of a first U-shaped profile constituting the first element of the reinforcement and a second U-shaped profile constituting the second element of the reinforcement.

The first U-shaped profile has one end shaped for attachment to the rear cross member of the vehicle chassis and the second U-shaped profile has one end shaped for attachment to the rear panel of the vehicle, the other end of each U-shaped profile being of complementary shape to allow assembly by overlapping said ends and attachment, for example by spot welding.

Preferably, these two U-shaped profile elements are produced by stamping.

According to a preferred embodiment, they are made of the same stamped material, the first element having a thickness greater than that of the second element. Thus, the stiffness of these two elements is worked and stepped to obtain the target behavior of either rigidity or deformability. The first element constituting the rigid front part of the reinforcement has for example a thickness of 1.3 mm, while the second element has a lesser thickness of 1 mm.

Furthermore, even more preferably, the first element comprises a stamping of the wall constituting the core of the U-shaped profile, produced at the end of attachment of said first element to the rear crossmember, extending axially and forming a stiffening rib reinforcing the stiffness of the rigid front part of the reinforcement, attached to said crossmember.

The second element comprises, arranged transversely on the wall constituting the core of the U, at least one stamping, preferably three, facilitating the axial deformation of the deformable rear part of the reinforcement.

In fact, despite the two-element design of the reinforcement, it is not more expensive in terms of mass than a single-piece solution thanks to the staging of the stiffness between the elements, which results in a significant gain in mass (more than 20%) on the deformable element.

The invention also relates to a central rear longitudinal reinforcement intended to be mounted in a vehicle according to the invention, consisting of a reinforcement comprising two assembled elements, the first element having a stiffness such that it constitutes a rigid front part of said central rear longitudinal reinforcement and a second element, assembled at the end of the first element, extending from said end of the first element, having a stiffness lower than that of the first element and constituting a rear deformable part of said central rear longitudinal reinforcement.

The invention will be well understood and other aspects and advantages will appear clearly on reading the following description, given by way of example with reference to the attached drawing plate in which the figures represent:

a bottom view of the rear of a vehicle according to the invention comprising a central longitudinal reinforcement;

a top view of the rear of a vehicle according to the invention;

a view from below the ;

a simplified side perspective view of the rear of a vehicle according to the invention;

an enlarged view of the ;

a view of the reinforcement alone of the ;

a top view of the reinforcement of the ;

a view according to the before a rear-end collision;

a view according to the at the start of the rear impact;

a view according to the during rear-end collision;

a view according to the at the end of the shock and

a cross-section of the reinforcement mounted on the chassis.

In the following description, the terms "front" and "rear" as well as the directions "longitudinal" and "transverse" will be understood in relation to the general orientation of the vehicle. The terms "low" and "lower" indicate a greater proximity to the ground than the terms "high" and "upper" respectively. In the various figures, the same references designate identical or similar elements. In the x, y and z coordinate system, the x axis represents the longitudinal axis of the vehicle, y the transverse axis of the vehicle and z the height of the vehicle.

There represents a bottom view of the rear of a vehicle according to the invention which shows a rear chassis 1 comprising two side beams 2 oriented in the longitudinal direction x of the vehicle. These two beams 2 are connected to each other by a cross member hereinafter called rear cross member 3 of the chassis 1 extending transversely to the side beams 2, along the axis y of the vehicle, and by the rear panel 4 of the vehicle. In the example shown, the space defined and supported by the two side beams 2 and the two cross members 3, 4 usually corresponds to the trunk area of the vehicle but which, in the example shown, corresponds to the area in which row 3 seats are fixed.

As can be seen in Figures 2 and 4, the seats of row 3 are represented by the support element 6 of the seat backrest consisting of a rigid tubular frame 61 mounted on the chassis 1 with supports 62, carried by the side beams 2 and a central support 63 carried by the floor (not shown). Once the seats are thus fixed, the distance d, between the rear of the seats, and the rear panel 4 of the vehicle is restricted and can in particular be 150 mm.

Therefore, in the event of a high-speed rear-end collision, which is a regulatory collision for which a vehicle must be approved, there is, in the rear-end collision regulation text, a criterion of maximum x-axis displacement of the projection of point R of the seats of each row, of 75 mm. This point R is the seating reference point, a point defined for each seating position on the vehicle plans and identified in relation to a three-dimensional reference system.

To meet this criterion in the case of the vehicle in the example shown, it is therefore necessary to perfectly control the possible deformation in this small space between the rear panel 4 and the seats of row 3, this deformation having to stop before the seats of row 3 and therefore occur within the distance d.

For this purpose, a central longitudinal reinforcement 5 is installed at the rear part of the vehicle, which extends between the rear cross member 3 and the rear panel 4. This central longitudinal reinforcement 5 has a rigid front part and a deformable rear part.

In order to produce this reinforcement 5, it is made up of two elements 51, 52 respectively forming the rigid front part and the deformable rear part of said reinforcement 5.

The first element 51 extends from the rear crossmember 3, substantially up to the level of the central support 63 of the row 3 seats, while the second element 52 extends from the end of said first element 51 to the rear panel 4.

The first element 51 is shaped so as not to deform and therefore has an appropriate stiffness while the second element must deform as much as possible, or even completely during a high-speed rear impact, but only in the area behind the seats. The transition zone or junction between the rigid front part and the deformable rear part of the central longitudinal reinforcement 5 is therefore advantageously positioned at the level of the fixing of the seats of row 3, cf. .

In this way, the second element 52 is located in the space between the seats and the rear panel 4, the compression of said reinforcement 5 occurring automatically in this area during a high-speed rear impact.

The reinforcement 5 is preferably in the form of a hollow profile having a U-shaped cross-section and with ends shaped to be fixed, embedded on the rear crossmember 3 on the one hand and the rear panel 4 on the other hand. Thus, the reinforcement 5 has a wall constituting the core of the U 5a, two side walls 5b comprising edges 5c, the ends of the reinforcement 5 being shaped to allow the fixing of said reinforcement 5 on the chassis of the crossmember 3 and the rear panel 4. This wall 5a forming the core of the U is a wall at the bottom of the chassis 1, therefore a lower wall of the U-shaped profile extending parallel to the floor P, the side walls 5b extending upwards with the edges pressed against the floor P (cf. ).

The reinforcement 5 is made up of two elements 51, 52, each element 51, 52 is made up of a hollow profile having a U-shaped cross-section comprising a bottom wall 51a, 52a, two side walls 51b, 52b, the side walls 51b, 52b respectively having a rim 51c, 52c extending towards the outside of the profile in a projecting orthogonal manner to the side walls 51b, 52b. The elements 51 and 52 have ends whose edges of complementary shape can overlap, for example, and are fixed by welding points, to form a junction zone 53 for assembling the two elements 51, 52.

In order to have sufficient stiffness, the first element 51 has a thickness greater than that of the second element 52. For example, it can be provided that the first element forming the front part 51 is 1.3 mm thick, while the second element forming the rear part has a smaller thickness, i.e. a thickness of 1 mm. To promote the deformation by compression of the rear part formed by the second element 52, the latter preferably has transverse grooves 54 formed by stampings made at the level of the bottom wall 52a, projecting towards the inside of the U.

Advantageously, the end of said first element 51 intended to be fixed on the rear crossmember 3 has a tab 55 in the extension of the bottom wall 51a to be fixed against a lower wall of the crossmember 3, edges 56 being formed between the tab 55 and the side walls 51b to also be fixed to the crossmember 3 along a side wall thereof.

In order to reinforce the stiffness of the element 51, a stamped portion is formed at the level of the bottom wall 51a and the tongue 55, forming a groove 57 extending axially to stiffen this first element 51 and prevent deformation of the reinforcement 5 at the level of the fixing on the crosspiece 3. This stamped portion is arranged to project towards the outside of the profile.

The fixing end of the second element 52 has a rim 58 surrounding the U-shaped profile, in the form of a collar, and allowing it to be fixed against the rear panel 4.

Once the reinforcement 5 thus formed is placed between the cross member 3, the rear panel 4 and under the floor P, a closed box is thus formed, the deformable rear part of which acts as a shock absorber box, commonly known by the English term "crash box" and the rigid front part limits the deformation of the passenger compartment.

As can be seen in the , the vehicle according to the invention comprises a central longitudinal reinforcement 5, extending from the rear crossmember 3 and the rear panel 4, parallel to the side beams 2. This central longitudinal reinforcement 5 consists of a first rigid element 51, forming the front part of said reinforcement 5 and a second deformable element 52 forming the rear part of said reinforcement 5, the deformable rear part thus extending in the space between the seats of row 3 and the rear panel 4. The rear impact obstacle, in the test carried out an impact barrier, is symbolized by the line B, the arrow indicating the direction of the impact occurring from the rear to the front of the vehicle.

During the collision, the impact between barrier B and the rear of the vehicle causes the deformation of the rear part 52 of the reinforcement 5 (see ).

Then, during the impact, the rear part of the reinforcement 5 is compressed according to the three initial deformations formed by the stampings 54 while the rigid front part does not deform (see ).

As can be seen in the , at the end of the impact, the rear part of the reinforcement 5 is completely compressed while the deformation of the rigid front part of the reinforcement 5 is controlled thanks to the fixing by embedding in the crossmember 3 and the longitudinal stiffening rib 57, so that the area of the seats of row 3 is preserved.

Claims (8)

Vehicle comprising a rear chassis (1) having two lateral beams (2) oriented in the longitudinal direction (x) of the vehicle between which is arranged, in parallel, a central rear longitudinal reinforcement (5), extending between the rear crossmember (3) of the chassis (1) and the rear panel (4) of the vehicle, characterized in that the central rear longitudinal reinforcement (5) is made up of two assembled elements (51, 52), the first element (51) extending from the rear crossmember (3) of the chassis (1), having a stiffness such that it constitutes a rigid front part of said central rear longitudinal reinforcement (5) and a second element (52), assembled at the end of the first element (51), extending from said end of the first element (51) to the rear panel (4) of the vehicle, having a stiffness lower than that of the first element (51) and constituting a rear deformable part of said central rear longitudinal reinforcement (5). Vehicle according to claim 1, characterized in that the first element (51) constituting the rigid front part of said central rear longitudinal reinforcement (5) extends from the rear crossmember (3) to the point of attachment of the seats of the last row of the vehicle and the second element (52) then extending from the first element (51) to the rear panel (4) of the vehicle, defining the rear deformable part of the central rear longitudinal reinforcement (5) between the seats of the last row and the rear panel (4). Vehicle according to claim 1 or 2, characterized in that the central rear longitudinal reinforcement (5) has the shape of a U-shaped profile, comprising at least one wall (5a) constituting the web of the U and two side walls (5b), this U-shaped profile being made up of a first U-shaped profile constituting the first element (51) of the central rear longitudinal reinforcement (5) and a second U-shaped profile constituting the second element (52) of the central rear longitudinal reinforcement (5), Vehicle according to claim 3, characterized in that the first U-shaped profile has one end shaped for attachment to the rear cross member (3) of the vehicle chassis (1) and the second U-shaped profile has one end shaped for attachment to the rear panel (4) of the vehicle, the other end of each U-shaped profile being of complementary shape to allow assembly by overlapping of said ends and attachment such as by welding, preferably by spots. Vehicle according to one of claims 3 and 4, characterized in that the two elements (51, 52) in the form of a U-shaped profile are produced by stamping, preferably from the same material, the first element (51) having a thickness greater than that of the second element (52). Vehicle according to one of claims 3 to 5, characterized in that the first element (51) comprises at its end of attachment to the crossmember (3), a stiffening rib (57) reinforcing the stiffness of the rigid front part of the central rear longitudinal reinforcement (5). Vehicle according to one of claims 3 to 6, characterized in that the second element (52) comprises, arranged transversely on the wall constituting the core of the U, at least one stamping (54), preferably three, facilitating the axial deformation of the deformable rear part of the central rear longitudinal reinforcement (5). Central rear longitudinal reinforcement (5) intended to be mounted in a vehicle according to one of claims 1 to 7, characterized in that it is made up of two assembled elements (51, 52), the first element (51) having a stiffness such that it constitutes a rigid front part (51) of said central rear longitudinal reinforcement and a second element (52), assembled at the end of the first element (51) and extending from said end of the first element (51), having a stiffness lower than that of the first element and constituting a deformable rear part of said central rear longitudinal reinforcement (5).