Bumper frame foot with programmed breakage.

Abstract

The invention relates to a bumper support frame (1) for a motor vehicle, comprising at least one frame foot (3) intended to support a bumper cross member, at least one frame foot (3) having a rupture zone (11) designed to undergo at least one rupture, when the frame (1) is mounted on a front face of a motor vehicle and the vehicle is subjected to a pedestrian leg impact. (Figure 2)

Description

Title of the invention: Bumper frame foot with programmed rupture.

[0001] The technical field relates to bumper frames designed to absorb part of the energy released by a collision with a pedestrian and motor vehicles equipped with such frames.

[0002] In terms of road safety, automobile manufacturers must face at least three major concerns which define constraints to be taken into account when developing new vehicles.

[0003] A first concern is to ensure the safety of the vehicle's passengers during a collision and in particular during a collision at high speed.

[0004] A second concern is to control the repair costs of vehicles when they undergo urban impacts, called repairable impacts, i.e. impacts suffered at low speeds of the order of 15 to 20 kilometers per hour.

[0005] Finally, a third concern is to ensure the safety of other road users, particularly the most vulnerable such as pedestrians. Thus, manufacturers seek to minimize the risks of injury and trauma inflicted on a pedestrian in the event of a collision with a vehicle, particularly to the pedestrian's legs.

[0006] The behavior of motor vehicles in these three situations is regulated and tested by implementing standardized test procedures. The requirements in terms of results in these tests are increasingly numerous and more difficult to meet, forcing automobile manufacturers to constantly innovate.

[0007] Standardized test procedures for simulating a collision between a pedestrian and a vehicle, known as a pedestrian impact, assess the extent to which the motor vehicles being tested protect vulnerable road users with whom they may collide and thus measure the potential risks of injury to several areas of the body, including the head and legs. To achieve this, the standardized test procedures involve projecting impact elements onto the vehicle to be tested at a predetermined relative speed, of the order of 40 kilometers per hour.The impactors have a particular shape adapted to each area of the body considered and are arranged at predefined relative positions in order to strike the vehicle, during the pedestrian impact, with predefined forces and impact directions, so as to represent the respective average positions of a head, femur or leg of a standard pedestrian standing before the impact. The standardized procedures are, for example, described by the international organization Euro NCAP. Thus, for pedestrian impacts relating to the legs (hereinafter referred to as pedestrian leg impacts), there are two tests. particular, which focus either on the lower part of the legs (hereinafter referred to as pedestrian impact lower leg) or on the upper part of the legs (hereinafter referred to as pedestrian impact femur), to analyze the risks of injuries respectively to the leg and knee or to the femur and pelvis.

[0008] The measures implemented on vehicles to minimize the risk of injuries to the head of a pedestrian generally involve active and / or passive safety means linked to the engine hood of the vehicle. As for those concerning injuries to the legs, the test procedures encourage less angular geometric shapes coupled with means of absorbing kinetic energy located on the bumper and the bodywork elements linked to it.

[0009] Some vehicles are equipped with a bumper frame to support bodywork elements such as the bumper crossmember and thus connect an outer bumper skin to the structure of the vehicle. Bumper frames must by their nature provide a certain rigidity to combat unwanted vibrations, aerodynamic deformations or to resist repairable impacts. In some cases, the bumper frame must also allow the air supply to the motor-fan unit and to do this the bumper frame is provided with structural feet at the ends of which the bumper crossmember is fixed. Such structural feet must be relatively rigid to respond to the stresses exerted on the bumper frame during normal use of the vehicle, which are essentially directed along the vertical axis of the vehicle.

[0010] Unfortunately, the stiffness of the bumper frame and the structural feet reduce the energy absorption capacities during a pedestrian impact. Thus, to guarantee good resistance to vibrations, repairable impacts and pedestrian impacts, it is known from patent document FR 3 063 698 to provide spaces allowing the deformation of bodywork elements located at the front of the bumper frame to absorb energy released during impact.

[0011] It is not always easy to provide such spaces on the front of a vehicle and these may prove insufficient to guarantee a satisfactory result in pedestrian impacts, in particular pedestrian femur impacts, relating to the upper part of the legs.

[0012] Thus, there is a need for a new bumper support frame, which makes it possible to maintain good vertical rigidity of the bumper support frame while limiting the forces received by a leg during a pedestrian impact.

[0013] The present invention aims to overcome the problems set out above. In this technical context, one aim of the present invention is to provide a bumper support frame ensuring suitable rigidity along the vertical axis of the vehicle while allowing an increased amount of energy to be dissipated during a pedestrian impact.

[0014] For this purpose, the present invention relates to a bumper support frame for a motor vehicle, comprising at least one frame foot intended to support a bumper crossmember, at least one frame foot having a rupture zone designed to undergo at least one rupture, when the frame is mounted on a front face of a motor vehicle and the vehicle is subjected to a pedestrian leg impact.

[0015] The invention also relates to a vehicle comprising a bumper support frame according to the invention, mounted on its front face to support a bumper.

[0016] Thus, the bumper support frame, provided with a rupture zone, makes it possible to guarantee a programmed rupture during the implementation of a standardized test procedure called pedestrian leg impact. The bumper support frame offers normal rigidity along the vertical axis of the vehicle and makes it possible to support the pedestrian crossbar. In the event of a simulated collision with the legs of a pedestrian, the direction and force of the impact with at least one of the striking elements used in the pedestrian leg impact test procedure causes the total or partial rupture of at least one frame foot, which makes it possible to absorb part of the energy released by the impact. The total or partial rupture of the frame foot of a vehicle according to the invention also causes the displacement of the bumper crossbar of the vehicle and thus contributes to reducing the risk of injury.

[0017] According to one embodiment of the invention, the rupture zone is designed to undergo at least one rupture during a pedestrian femur impact.

[0018] According to one possibility, the rupture zone comprises a predefined direction, each rupture suffered propagating at least partly in the reinforcement along a rupture line perpendicular to this predefined direction.

[0019] Advantageously, the predefined direction is parallel to the direction of impact with a striking element.

[0020] According to one embodiment, the rupture zone comprises at least one notch or at least one orifice for initiating a rupture undergone by the rupture zone. Such a notch makes it possible to define a point of initiation of a rupture which will then propagate in the rupture zone.

[0021] According to one possibility of the invention, the rupture zone comprises at least one zone of reduced thickness. A zone of thickness constitutes a simple means of producing part or all of a rupture zone.

[0022] Advantageously, the rupture zone comprises at least one shear step designed to break by shearing upon rupture. A shear step makes it possible to control the location of the rupture while controlling the relative movement of the reinforcement foot portions after the total rupture of the rupture zone concerned.

[0023] According to one embodiment of the invention, the rupture zone is made of plastic.

[0024] The invention will be better understood on reading the detailed description which follows, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0025] [fig.l] [fig.l] represents a perspective and front view of a bumper support frame according to the invention;

[0026] [fig.2] [fig.2] represents a detailed view of a frame foot of the frame of [fig.l] showing the rupture zone;

[0027] [fig.3] [fig.3] represents a perspective view from behind of the frame foot of [fig.2];

[0028] [fig-4] [fig.4] represents a perspective view of the frame of [fig.l] with the rupture zone that has undergone a rupture.

[0029] In these figures, the same references are used to designate the same elements.

[0030] A bumper support frame 1 according to the invention, shown in Figures 1 to 4, is intended to be mounted on a vehicle according to the invention, not shown in the figures, in order to support a bumper crossmember also not shown in the figures. The frame 1 comprises an upper part 2 designed to be fixed to the body of the vehicle. The upper part 2 has a longitudinal extension at the ends of which extend two frame feet 3. Each frame foot 3 extends in an oblique direction relative to the upper part 2. The frame feet 3 are spaced from each other so as to extend on each side of a cooling radiator of the vehicle equipped with the frame 1. The ends of the frame feet 3 opposite the upper part 2 are connected to each other by a transverse profile 4 forming a support and fixing surface for the bumper crossmember.The transverse profile 4 is connected to the upper part 2 by a central rib 5. The frame 1 has two recesses 6, each delimited by a frame foot 3, the transverse profile 4, the rib 5 and the upper part 2. Each recess 6 is designed to ensure the air supply to the motor-fan unit of the vehicle.

[0031] As shown in Figures 2, 3 and 4, each frame foot 3 has a rear face 7 extended at right angles by two lateral reinforcements 8, 9 arranged opposite one another. The rear face 7 extends to a substantially horizontal plate 10 when the frame 1 is mounted on the vehicle. The transverse profile 4 extends from each plate 10 of each frame foot 3.

[0032] Each reinforcement foot 3 has at least one rupture zone 11. In the example illustrated in the figures, each rupture zone 11 is made of plastic. preferably, the frame 1 is made entirely of plastic. Each rupture zone 11 is designed to undergo at least one rupture 12, shown in [fig.4], when the frame 1 is mounted on a front face of a motor vehicle and the vehicle is subjected to a pedestrian leg impact. Preferably, each rupture zone 11 is designed to undergo a rupture during a pedestrian femur impact. For this purpose, each rupture zone 11 extends over the rear face 7 as well as over the lateral reinforcements 8, 9. On the rear face 7, the rupture zone 11 has at least one zone of reduced thickness 13 in which the thickness of the material constituting the frame foot 3 is reduced compared to the thickness of the material forming the frame foot 3 outside the zone of reduced thickness 13.Said zone of reduced thickness 13 forms, for example, a groove 14 extending transversely on the rear face 7, in a horizontal direction when the frame 1 is mounted on the vehicle.

[0033] Each rupture zone 11 also extends over each lateral reinforcement 8, 9 as illustrated in the figures. On one 8 of the lateral reinforcements 8, 9, the rupture zone 11 has a zone of reduced thickness 15 formed by a groove 16. On the other lateral reinforcement 9, the rupture zone 11 has a zone of reduced thickness 17 formed by a shear step 18, particularly visible in [fig.3]. The shear step 18 is formed by two portions 19, 20 of the lateral reinforcement 9, parallel to each other, and connected by a wall 21 forming the reduced thickness zone 17, perpendicular to each of the portions 19, 20. The wall 21 extends along a rupture line 22 symbolized by the axis AA, visible in Figures 2 and 3. When the rupture 12 propagates in the reduced thickness zone 17, the rupture 12 then propagates along the rupture line 22.Thus, the rupture zone 11 has a predefined direction for which each rupture 12 suffered propagates at least partly in the reinforcement 1 along the rupture line 22 perpendicular to this predefined direction. The predefined direction in fact corresponds to a direction parallel to the direction of the impact between a striking element, not shown, and the reinforcement 1 during a pedestrian leg impact, preferably during a pedestrian femur impact.

[0034] The lateral reinforcements 8, 9 each comprise at least one notch 23 arranged on the edge of each lateral reinforcement 8, 9 to initiate the rupture 12 undergone by the rupture zone 11 by forming an initiation point of said rupture 12 from which the rupture 12 propagates in the rupture zone 11. Alternatively, one or more notches 23 can be supplemented and / or replaced by at least one orifice provided in the rupture zone 11.

[0035] During a pedestrian leg impact, more particularly a pedestrian femur impact, the fracture 12 propagates partly or completely in the fracture zone 11. If the propagation of the fracture 12 is total, then the reinforcement foot 3 concerned is cut into two foot parts 24, 25, as illustrated in [fig.4]. The propagation of the fracture 12 in the rupture zone 11 absorbs part of the energy while the movement of each foot portion 24, 25 allows a movement of the bumper crossmember, thus absorbing some of the energy released by the pedestrian impact. During the movement of each foot portion 24, 25, the two portions 19, 20 can slide on each other facilitating the movement of the foot portions 24, 25.

[0036] Thus, the bumper support frame 1 according to the invention makes it possible to obtain a vehicle according to the invention which is particularly effective in absorbing at least part of the energy of a pedestrian leg impact and thus minimizing the risks of injuries inflicted on a pedestrian in the event of a collision. Indeed, during a pedestrian leg impact, the impact caused by at least one striking element used during the test is directed in the predefined direction which causes the rupture zone 11 of each frame foot 3 to break.

[0037] The invention is not limited to the embodiment of the frame described above, only by way of example, but other embodiments can be designed by those skilled in the art without departing from the scope and scope of the present invention.

Claims

Claims

1. Frame (1) bumper support for a motor vehicle, comprising at least one frame foot (3) intended to support a bumper cross member, at least one frame foot (3) having a rupture zone (11) designed to undergo at least one rupture (12), when the frame (1) is mounted on a front face of a motor vehicle and the vehicle is subjected to a pedestrian leg impact.

2. Frame (1) according to claim 1, characterized in that the rupture zone (11) is designed to undergo at least one rupture during a pedestrian femur impact.

3. Reinforcement (1) according to claim 1 or 2, characterized in that the rupture zone (11) comprises a predefined direction, each rupture (12) undergone propagating at least partly in the reinforcement (1) along a rupture line (22) perpendicular to this predefined direction.

4. Armature (1) according to claim 3, characterized in that the predefined direction is parallel to the direction of impact with a striking element.

5. Reinforcement (1) according to one of claims 1 to 4, characterized in that the rupture zone (11) comprises at least one notch (23) or at least one orifice for initiating a rupture (12) undergone by the rupture zone (11).

6. Reinforcement (1) according to one of claims 1 to 5, characterized in that the rupture zone (11) comprises at least one zone of reduced thickness (13, 15, 17).

7. Reinforcement according to one of claims 1 to 6, characterized in that the rupture zone (11) comprises at least one shear step (18) designed to break by shearing upon rupture (12).

8. Armature (1) according to one of claims 1 to 7, characterized in that the rupture zone (11) is made of plastic.

9. Vehicle characterized in that it comprises a bumper support frame (1) according to one of claims 1 to 8, mounted on its front face to support a bumper.

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