Motor vehicle bonnet with a rear cavity comprising transverse corrugations

Abstract

The present invention relates to a bonnet (4) for a motor vehicle, comprising: - an outer wall; - a bonnet lining (12); characterised in that, on a rear half (4.1) along a longitudinal extension (X) of the bonnet, intended to be close to a windscreen, the lining comprises a rear portion (12.1) having a cavity (14) facing the outer wall, the cavity having a curvilinear profile (24) extending in a transverse direction (Y) of the bonnet.

Description

[0001] DESCRIPTION

[0002] TITLE: MOTOR VEHICLE HOOD WITH A REAR CAVITY COMPRISING TRANSVERSE CORRUGATIONS

[0003] The present invention claims priority from French application 2307797 filed on 20.07.2023, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004] Technical field

[0005] The present invention relates to the field of motor vehicles, more particularly to the field of the structure of motor vehicles.

[0006] Prior art

[0007] Accidents involving vehicles striking pedestrians pose a significant risk to pedestrian safety. Among these accidents, there is a particularly dangerous type where the front of the vehicle flips or throws the pedestrian, causing their head to strike the hood or windshield. This impact can be fatal in the event of a head injury.

[0008] To reduce the risk of head injury to pedestrians, various regulatory bodies around the world have established standards that car manufacturers must adhere to. These standards include the ECE 127 pedestrian impact regulation and the EURONCAP standard developed by the European Union. Japan has also adopted a standard called JNCAP, and China's ChinaNCap standard, among others.

[0009] According to these standards, for example, it is required that a head injury criterion designated by: HIC (Head Injury Criteria) does not exceed 1000. The HIC depends on the force and duration of the impact suffered by the pedestrian's head against the hood of the vehicle during a collision between the pedestrian and the vehicle.

[0010] In this regard, vehicle hood structures are known with an inner hood panel joined to an outer hood panel. Sometimes, aluminum alloys are used for the outer hood panel and the inner hood panel to reduce the weight of the hood structure. In such structures, there are cases in which, from the perspective of pedestrian protection, several beads are formed parallel to each other. For example, published patent document EP 2 551 172 A1 discloses a hood structure comprising alternating concavities in its central section, which makes it possible to improve energy absorption during a simulated impact with the head of a pedestrian.

[0011] However, the ECE 127 regulation has just seen its pedestrian head impact inspection area extended with the addition of the rear windshield area, which runs from the rear edge of the hood to the bottom of the windshield, and which is currently only monitored. It will most likely be part of the areas inspected in the next evolution of the regulatory text, before 2030.

[0012] In this context, the known solutions, and in particular that presented by document EP 2 551 172 A1, have room for improvement, as they do not appear to make it possible to obtain a low HIC in the event of a collision at the rear area of ​​the bonnet. Indeed, the disclosed bonnet structure does not include any element making it possible to prevent the sphere from sinking into the rigid and incompressible areas at the bottom of the motor vehicle windscreen.

[0013] Statement of the invention

[0014] The present invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the invention aims to propose a solution making it possible to effectively improve the response of motor vehicles to collision tests comprising a simulated impact with the head of a pedestrian.

[0015] To this end, the invention relates to a hood for a motor vehicle, comprising:

[0016] - an exterior wall;

[0017] - a hood lining; remarkable in that on a rear half along a longitudinal extent of the hood, intended to be close to a windshield, the lining comprises a rear portion having a cavity facing the outer wall, said cavity having a curvilinear profile extending along a transverse direction of the hood.

[0018] Advantageously, the curvilinear profile extends transversely over a mean plane of the lining.

[0019] According to one embodiment, the cavity comprises corrugations extending over at least 80% of a total transverse extent of the cover. According to one embodiment, the cavity comprises a rear wall and a front wall extending vertically from a bottom of the cavity, said rear wall being the one having the curvilinear profile of the cavity.

[0020] Preferably, the waves are presented exclusively on the rear wall.

[0021] According to one embodiment, the cavity comprises a bottom provided with a plurality of hollows respectively having a rectangular shape extending in the longitudinal direction.

[0022] According to one embodiment, the hood further comprises a reinforcing piece mounted at the cavity and sandwiched between the lining and the outer wall.

[0023] According to one embodiment, the reinforcing piece is arranged, successively, against a bottom of the cavity and the rear wall of the cavity, as well as against an upper wall of the lining adjacent to the rear wall and close to a rear edge of the hood.

[0024] According to one embodiment, the reinforcement piece is assembled to the lining by means of clinching at the right of each of the hollows presented in the bottom of the cavity.

[0025] According to one embodiment, the reinforcement piece has at least one flat part extending over the upper face and bonded to the outer wall.

[0026] According to one embodiment, the curvilinear profile is distant from the rear edge of the hood by a distance corresponding to at most 10% of a total longitudinal extent of the hood.

[0027] The invention also relates to a motor vehicle comprising:

[0028] - a body structure;

[0029] - a hood arranged at the front of the body structure; remarkable in that the hood is according to the invention.

[0030] The measures of the invention are advantageous in that the local rigidity of the hood is considerably improved thanks to the geometry of the rear portion of the lining comprising a cavity provided with corrugations extending transversely in line with the rear wall, as well as the hollows arranged at the bottom. Thus, during a simulated collision with a pedestrian, the deceleration of a sphere (representing the pedestrian's head) is advantageously increased upon impact in order to maximize energy absorption, which makes it possible to reduce the resulting HIC.

[0031] Furthermore, the invention makes it possible to avoid the need for an active system (active hood, awning airbag, etc.). It is therefore very economical in view of the complex solutions that it makes it possible to avoid.

[0032] Brief description of the drawings

[0033] [Fig 1] represents a perspective view of a motor vehicle comprising a hood arranged at the front of a body structure, said hood being according to the invention;

[0034] [Fig 2] represents a longitudinal sectional view along the axis AA of the hood of figure 1, said hood being here according to a first embodiment of the invention in which the hood comprises a lining provided with a cavity on a rear half of said hood;

[0035] [Fig 3] represents a longitudinal sectional view along the axis AA of the cover of figure 1, said cover being here according to a second embodiment of the invention in which a reinforcing piece is mounted at the level of the cavity;

[0036] [Fig 4] represents a front view of the hood lining according to the first embodiment of the invention;

[0037] [Fig 5] represents a perspective view of the hood lining according to the second embodiment of the invention.

[0038] Detailed description

[0039] Figure 1 represents a perspective view of a motor vehicle 2 comprising a hood 4 arranged at the front of a body structure 6.

[0040] The hood 4, 104 comprises an outer wall 8 commonly referred to as a hood skin 8, which is attached to a lining by crimping.

[0041] A rear half 4.1 can be seen along a longitudinal extent of the hood 4, 104 (along the X axis), intended to be close to a windshield 10, the lining comprises a rear portion having a cavity visible in the following figures. Figure 2 represents a longitudinal sectional view along the AA axis of the hood 4 of Figure 1. Here, the hood 4 is according to a first embodiment of the invention in which the lining 12 is provided with a cavity 14 at a rear portion 12.1 of the lining opposite the outer wall 8 on the rear half 4.1 of said hood 4.

[0042] The cavity 14 comprises a rear wall 16 and a front wall 18 which extend vertically from a bottom 20 of the cavity 14. Preferably, the cavity 14 and its walls 16, 18 and 20 are all formed by stamping with the liner 12.

[0043] Advantageously, the rear wall 16 has a curvilinear profile comprising undulations visible on a medium plane (corresponding to the XY plane), and which will be detailed later in this description.

[0044] Preferably, the cavity 14 is arranged adjacent to the rear edge 4.2 of the hood 4, close to a cowl of the motor vehicle 2. More preferably, the rear wall 16 of the cavity 14 is arranged at most 20% of the longitudinal extent of the hood 4 from the rear edge 4.2, and even more preferably arranged at most 10% of said extent.

[0045] Figure 3 represents a longitudinal sectional view along the axis AA of the cover 104 of Figure 1. Here, the cover 104 is according to a second embodiment of the invention in which a reinforcing piece 22 is mounted at the cavity 14 and is sandwiched between the lining 12 and the outer wall 18.

[0046] In this second embodiment, the cavity 14 as well as the dimensions and architecture of the entire cover 104 remain unchanged compared to those of the cover 4 according to the first embodiment. Indeed, the only difference between the two embodiments lies in the presence of the reinforcement piece 22 at the right of the cavity 14, which makes it possible to provide greater rigidity to the rear part 4.1. This will be detailed further in this description.

[0047] Figure 4 shows a front view of the lining 12 of the hood according to the first embodiment of the invention.

[0048] Here we can observe the curvilinear profile 24 visible on the mean plane (XY) of the lining 12, this comprises undulations having a wave shape extending preferentially over at least 80% of a total transverse extent of the lining 12. Advantageously, the curvilinear profile 24 is configured to provide rigidity to the rear half of the hood close to the rear edge, in order to counteract the rotation of said hood around a transverse axis (Y), during a simulated impact of the head (sphere) of a pedestrian against the outer wall of the hood.

[0049] Indeed, in the absence of the curvilinear profile 24, a rear wall 16 devoid of undulations could have a tendency to crush upon impact, resulting in a low deceleration of the sphere and a significant depression of the latter which then impacts rigid and incompressible zones in the lower part of the windshield, and a high HIC “Head Injury Criteria” not allowing approval of the motor vehicle.

[0050] Advantageously, the cavity 14 comprising the transverse undulations on its rear wall 16, makes it possible to optimize the geometry of the lining 12 in order to take advantage of the first millimeters of the sinking stroke of the sphere (pedestrian's head), to effectively absorb the energy of the impact and slow down said sphere during the impact.

[0051] The bottom 20 is preferably provided with a plurality of hollows 26 respectively having a rectangular shape extending in the longitudinal direction.

[0052] The hollows 26 on the bottom 20 make it possible to create a non-planar cross-section of said bottom 20. This makes it possible, in combination with the curvilinear profile 24 on the rear wall 16, to improve the resistance to rotation of the lining 12 around the Y axis at the rear portion 12.1 in the event of an impact. To this end, the resulting HICs are significantly improved and allow possible approval of the motor vehicle with or without the presence of the reinforcement piece 22, depending on the dispersions between the theoretical calculations and the physical tests.

[0053] Figure 5 shows a perspective view of the hood lining according to the second embodiment of the invention.

[0054] The reinforcing piece 22 is arranged, successively, against the bottom 20, the rear wall 16 and against an upper wall 13 of the lining 12 which is adjacent to the rear wall 16 of the cavity 14 and close to the rear edge 4.2 of the hood.

[0055] In this configuration, the reinforcement 22 has flat upper parts 22.1 configured to be glued to the outer wall of the hood, in order to improve the hold of said reinforcement 22. Preferably, the reinforcement 22 is assembled to the lining 12 by means of clinching at the right of each of the hollows 26.

[0056] The reinforcement 22 has a mass of approximately 100 g, and therefore does not weigh down the hood 104 of the motor vehicle.

[0057] Advantageously, the reinforcement 22 makes it possible to improve the rigidity of the rear half of the hood, and makes it possible to reduce the force at which the pedestrian's head contacts the hood, thereby reducing damage to the hood and injuries to the pedestrian. The reinforcement 22 therefore makes it possible to further improve the resulting HIC in the event of a collision.

[0058] In addition, the vibration behavior of the assembled hood is also improved, thus reducing the noise that can be caused during driving conditions of the motor vehicle.

[0059] Advantageously, the hood of the motor vehicle according to at least one of the two embodiments of the invention makes it possible to avoid the use of an active system of the "active hood" type, in which the hood hinges comprise a pyrotechnic system making it possible, upon detection of the impact of a pedestrian, to eject the hood upwards, to increase the distance from the hard points in the rear part of the hood. The cost of such a solution is several tens of euros per vehicle.

[0060] The invention also makes it possible to avoid the need for an active system such as a "canopy airbag", in which an inflatable cushion deploys after the hood is ejected, in the windshield bay area. The cost of such a solution is also several tens of euros and is systematically associated with an active hood.

[0061] To this end, the present invention has a cost of zero, a few euro cents (cost of reinforcement 22). It is therefore very economical in view of the complex solutions that it allows to avoid.

Claims

CLAIMS [Claim 1.] Hood (4; 104) for a motor vehicle (2), comprising: - an outer wall (8); - a hood lining (12); characterized in that on a rear half (4.1) along a longitudinal extent (X) of the hood (4; 104), intended to be close to a windshield (10), the lining (12) comprises a rear portion (12.1) having a cavity (14) facing the outer wall (8), said cavity (14) having a curvilinear profile (24) extending along a transverse direction (Y) of the hood (4; 104). [Claim 2.] A cover (4; 104) according to claim 1, wherein the cavity (14) comprises corrugations extending over at least 80% of a total transverse extent of the cover (4; 104). [Claim 3.] Cover (4; 104) according to one of claims 1 or 2, in which the cavity (14) comprises a rear wall (16) and a front wall (18) extending vertically from a bottom (20) of the cavity (14), said rear wall (16) being that having the curvilinear profile (24) of the cavity (14). [Claim 4.] Cover (4; 104) according to one of claims 1 to 3, in which the cavity (14) comprises a bottom (20) provided with a plurality of hollows (26) respectively having a rectangular shape extending in the longitudinal direction (X). [Claim 5.] Hood (4; 104) according to one of claims 1 to 4, in which the hood (104) further comprises a reinforcing piece (22) mounted at the cavity (14) and sandwiched between the lining (12) and the outer wall (8). [Claim 6.] Hood (4; 104) according to claims 3 to 5, in which the reinforcing piece (22) is arranged, successively, against a bottom (20) of the cavity (14) and the rear wall (16) of the cavity (14), as well as against an upper wall (13) of the lining (12) adjacent to the rear wall (16) and close to a rear edge (4.2) of the hood (4). [Claim 7.] Hood (4; 104) according to claims 4 to 6, in which the reinforcing piece (22) is assembled to the lining (12) by means of clinching at right angles to each of the hollows (26) presented in the bottom (20) of the cavity (14). [Claim 8.] Hood (4; 104) according to claims 6 and 7, in which the reinforcing piece (22) has at least one flat part (22.1) extending on the upper face (13) and glued to the outer wall (8). [Claim 9.] Hood (4; 104) according to one of claims 1 to 8, wherein the curvilinear profile (24) is distant from the rear edge (4.2) of the hood (4; 104) by a distance corresponding to at most 10% of a total longitudinal extent of the hood (4; 104). [Claim 10.] Motor vehicle (2) comprising: - a body structure (6); - a hood (4; 104) arranged at the front of the bodywork structure (6); characterized in that the hood (4; 104) being according to one of claims 1

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