BUMPER FRAME FOR MOTOR VEHICLES AND MOTOR VEHICLES INCLUDING SUCH A FRAME

Abstract

The invention relates to a bumper reinforcement (5) for a motor vehicle, said reinforcement (5) comprising at least one reinforcement foot (17) configured to support a bumper beam, characterized in that said at least one reinforcement foot (17) comprises a first part and a second part fixed to each other, said reinforcement foot (17) being configured such that, when a force applied to said reinforcement foot (17) exceeds a threshold value, its length is reduced by a relative movement of the first and second parts with respect to each other. [Fig. 2]

Description

Title of the invention: BUMPER FRAME FOR MOTOR VEHICLE AND MOTOR VEHICLE COMPRISING SUCH A FRAME

[0001] The present invention relates to the field of bumpers for motor vehicles, and more particularly to bumper frames designed to absorb part of the energy generated by a collision with a pedestrian. The invention also relates to 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: - ensure the safety of vehicle passengers in the event of a collision, particularly in the event of a collision at high speed; - control the repair costs of vehicles when they undergo urban impacts, called repairable impacts, i.e. impacts suffered at low speeds of around 15 to 20 kilometers per hour; - ensure the safety of other road users, particularly the most vulnerable such as pedestrians, with manufacturers seeking to minimise the risk of injury and trauma inflicted on a pedestrian in the event of a collision, for example head-on, with a vehicle, particularly to the pedestrian's legs.

[0003] 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.

[0004] Standardized test procedures, designed to simulate 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 do this, the standardized test procedures involve projecting impactors (or dummies) onto the vehicle to be tested at a predetermined relative speed, of the order of 40 kilometers per hour.

[0005] The striking elements 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 directions of impact, so as to represent the respective average positions of a head, a femur or a leg of a standard pedestrian standing before impact.

[0006] Standardized procedures are, for example, described by the international organization EuroNCAP. Thus, for pedestrian impacts relating to the legs (hereinafter referred to as pedestrian leg impacts), there are two specific tests, which focus either on the lower part of the legs (or pedestrian lower leg impact) or on the upper part of the legs (or pedestrian femur impact), to analyze the risks of injuries respectively to the leg and knee or to the femur and pelvis.

[0007] 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.

[0008] Indeed, generally speaking, bumpers aim, first and foremost, to absorb the energy of impacts during a collision with an obstacle, so that the actual load-bearing structure of the motor vehicle is not damaged as much as possible, but are also configured to limit the damage inflicted on pedestrians.

[0009] Some vehicles are equipped with a bumper frame to support bodywork elements, such as the bumper crossmember or beam, and thus connect an outer bumper skin to the vehicle structure. Bumper frames must by their nature provide a certain rigidity to combat unwanted vibrations, aerodynamic deformations or to resist repairable impacts.

[0010] In some cases, the bumper frame must also allow the air supply to the fan unit and to do this the bumper frame is provided with structural feet to 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.

[0011] In the case of a pedestrian impact (particularly for the EuroNcap), the upper mass of the leg rests on the frame via the top of the bumper, the "softnose" (connecting piece between the hood and the front of the bumper) and the hood. Thus, the coupling of the frame to a rigid element, such as a beam or a bumper crossmember, via the frame feet (structural and vertical) results in an increase in vertical rigidity, an increase in the moments experienced by the top of the leg during a collision, and therefore by extension an increase in the risk of serious injury for the pedestrian.

[0012] The stiffness of the bumper frame and structural legs reduces the capacities energy absorption during a pedestrian impact. Thus, to guarantee good resistance to vibrations, repairable impacts and pedestrian impacts, it is known to provide spaces allowing the deformation of bodywork elements located at the front of the bumper frame to absorb the energy released during the impact.

[0013] 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.

[0014] Furthermore, due to the increase in the number of electric vehicles, there are more and more bumper grilles as styling elements, making the bumpers increasingly rigid and / or heavy (light grille for example), particularly in the absence of a need to supply air to a thermal engine (elimination of the grilles).

[0015] Thus, in view of all of these problems, 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.

[0016] The present invention thus proposes to remedy at least one of the aforementioned drawbacks by proposing a new type of bumper frame for a motor vehicle, said frame comprising at least one frame foot configured to support a bumper beam (or crossmember), characterized in that said at least one frame foot comprises a first part and a second part fixed to each other, said frame foot being configured so that there is, when a force applied to said frame foot exceeds a threshold value, a reduction in its length, by a relative movement of the first and second parts with respect to each other.

[0017] The frame according to the invention makes it possible to compensate for an increase in rigidity (in the upper part of the bumper) by an increase in the possible movements of said frame feet in the event of a leg impact, minimizing serious injuries inflicted on a pedestrian in the event of an impact. In addition, the frame according to the invention is simple and inexpensive to implement, easy to adapt according to the characteristics of the vehicle (weight, height, etc.), while facilitating compliance with standards and tests for leg impacts, both in homologation and in consumer use.

[0018] According to a possible characteristic, said frame comprises a fixing element which fixes the first and second parts together, said fixing element being configured to allow relative movement of said parts with respect to each other if a force applied to said frame foot exceeds a threshold value. Said fixing element fixes or secures the first and second parts of said reinforcement foot between them, preventing any relative movement of said parts with respect to each other, at least until the force applied to said foot exceeds a threshold value. Said fixing element can advantageously be adapted or adjusted, thus modifying the force threshold value according to the motor vehicle, in particular according to its weight, height, etc.

[0019] According to another possible characteristic, said first and second parts of said frame foot are configured to slide relative to each other. It is advantageous for the reduction of the length of the reinforcement foot to be carried out by sliding, because this allows better control of the kinematics of said parts during an impact. Furthermore, having a sliding movement allows a progressive reduction of the length of the reinforcement foot and therefore of the moments undergone by the leg of a pedestrian. In addition, unlike a break solution, the energy dissipation of said foot is improved, while improving its repairability (for example in the case of partial sliding).

[0020] According to another possible characteristic, said fixing element is adjustable to modify the threshold value of the force allowing relative movement of the first and second parts with respect to each other. The threshold value of force required for the relative movement of said parts in relation to each other is advantageously adjustable depending on the type of vehicle and / or regulatory developments relating to pedestrian leg impacts.

[0021] According to another possible characteristic, the fixing element is a rod, for example metallic or plastic, inserted through said first and second parts. The adjustment of the force threshold value triggering the movement of said parts of the frame foot can advantageously be achieved by the level of (mechanical) coupling between said fixing element and said first and second parts. Said fixing element is for example a screw whose fusibility adjustment is achieved by a single tightening to the torque which varies according to the vehicle.

[0022] According to another possible characteristic, at least one of said first and second parts comprises an oblong opening, the relative movement of the first and second parts with respect to each other being guided by said oblong opening. The oblong opening in cooperation with the fixing element makes it possible to guide the movement (for example by sliding) of one part of the frame foot relative to the other, while being a simple and inexpensive solution to implement, regardless of the type of motor vehicle.

[0023] According to another possible characteristic, the relative movement of the first and second parts with respect to each other is between 70 and 150 mm, and preferably between 80 and 120 mm.

[0024] According to another possible characteristic, the first and second parts extend, in the mounted position in a motor vehicle, in a substantially vertical plane. The first and second parts advantageously extend, in the mounted position, in a vertical plane, in order to limit the moments experienced by the top of a pedestrian's femur during a collision following the reduction in the length of the reinforcement foot.

[0025] The invention also relates to a bumper for a motor vehicle, characterized in that said bumper comprises a frame comprising all or part of the characteristics mentioned above.

[0026] The invention further relates to a motor vehicle, for example thermal, electric or hybrid, characterized in that said vehicle comprises a bumper as defined above.

[0027] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of a particular embodiment of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings, in which: - [Fig.l] illustrates a schematic, partial and perspective view of a bumper according to the invention; - [Fig.2] is a schematic, perspective and front view of the bumper frame of [Fig.l]; - [Fig.3] is a schematic, enlarged and partial view of a foot of the frame of [Fig.2],

[0028] In the following description, the term "comprise" is synonymous with "include" and is not limiting in that it allows the presence of other elements in the vehicle, or the structure to which it relates. It is understood that the term "comprise" includes the terms "consist of".

[0029] Similarly, the terms "lower", "upper", "front", "rear", "longitudinal" and "transverse" will be understood, unless context or otherwise indicated, in relation to the general orientation of the motor vehicle, whether it is hybrid, thermal or electric.

[0030] The term "lower" will designate a greater proximity to the ground than "upper" along the vertical axis. Furthermore, it will be noted that in the different figures, the same references designate identical or similar elements.

[0031] [Fig.l] illustrates a schematic, partial, three-quarter perspective and front view of a bumper 1 intended to be mounted in a motor vehicle, for example thermal, electric or hybrid.

[0032] Said bumper 1, for example for the front of a motor vehicle, comprises among other things: - a 3-part shock absorption system configured to absorb and dissipate energy during shocks; - a bumper frame 5 resting on one or more sub-elements of said absorption system 3 and on an upper front cross member 6.

[0033] It will be noted that such a frame 5 is for example configured to support in the upper part the constituent elements of the bumper 1, and among other things certain elements of the absorption system 3. Said shock absorption system 3 and the frame 5 are for example intended to be mounted between a structural element of the vehicle, such as a stretcher (not shown), the bumper skin (not shown) and various fairing elements (not shown), such as a deflector, the hood, etc.

[0034] The shock absorption system 1 comprises: - at least one hollow beam 7, or crosspiece, forming an absorber; - at least one fixing plate 9 on the one hand, connected to said beam 7, and on the other hand, configured to allow the securing of said absorption system 3 to a structural element of a motor vehicle, such as a stretcher (not shown) of a motor vehicle; - at least one shock absorption box 11 fixed, on the one hand, to said plate 9, and on the other hand, to said beam 7 (box 11 also referred to in English as a “crashbox”).

[0035] It will be noted that the number of beams 7, plates 9 and boxes 11 can be variable, and that the number of plates 9 and boxes 11 is for example a function of the length of the beam 7 and / or its weight.

[0036] Said beam 7 generally has an elongated shape and is formed from a metal plate folded on itself to have a closed section (for example in an S). Said metal plate forming the beam 7 is advantageously made of steel, aluminum, or an aluminum alloy.

[0037] The bumper frame 5 comprises, for its part, a main body 5a, acting as the upper part of said frame 5, designed to be fixed to the body of the vehicle, as well as frame feet 15 and 17 which, in the mounted position, come to bear on the beam 7 of the absorption system 3. Said frame feet 15 and 17 being fixed, for example by means of a plate, screws or bolts, etc. to said beam 7.

[0038] The upper part 5a has a longitudinal extension at the ends of which extend reinforcement feet 15, called lateral reinforcement feet. Said frame 5 also comprises a frame foot 17 located substantially in the middle of the upper part 5a, called the central frame foot.

[0039] Each lateral frame foot 15 extends in a transverse direction relative to the upper part 5a. The lateral frame feet 15 are for example spaced from each other so as to extend on each side of a cooling radiator. development (not shown) of the vehicle equipped with said frame 5.

[0040] The spaces delimited by the lateral feet 15, the central foot 17 and the beam 7 are for example intended to ensure the air supply to a motor-driven fan unit (not shown) of the vehicle.

[0041] The frame 5 is, for its part, advantageously made entirely of a plastic material, such as polypropylene, etc., the main body 5a being for example a single-piece part.

[0042] [Fig.2] illustrates a very schematic, enlarged, partial and front view of the central frame foot 17 of the frame 5. Said central foot 17 comprises among other things two branches 17a and 17b which extend from the upper part 5a of the frame 5 in the direction of a fixing plate 18 configured to be fixed to the beam 7 (and support the latter), said branches 17a and 17b converging towards said plate 18, the assembly 17a-b and 18 having a substantially V shape.

[0043] [Fig. 3] is a schematic, enlarged and partial view of the central frame foot 17 of the frame 5. Each of the two branches 17a and 17b of the central foot 17 thus comprises a first part 19 and a second part 20 fixed to each other by means of a fixing element 22. It will be noted that the first and second parts 19 and 20 extend, in the mounted position in a motor vehicle, in a substantially vertical plane.

[0044] Said central armature foot 17 is thus configured so that there is, when a force applied to said armature foot 17, and more generally to the main body 5a of the armature 5, exceeds a threshold value, a reduction in its length, by a relative movement of the first 19 and second 20 parts of said branches 17a and 17b relative to each other.

[0045] Said fixing element 22 is thus configured to fix and / or secure said parts 19 and 20 together, and therefore prevent any relative movement of the parts 19 and 20 with respect to each other, until a force applied to said frame foot 17 (or indirectly to the main body 5a) exceeds a predetermined threshold value. It will be noted that the threshold force value triggering the reduction in length of the central foot 17 is predetermined to be greater than the forces experienced by the frame during nominal operation of the vehicle, but less than the orders of magnitude of the forces corresponding to a collision.

[0046] Said first and second parts 19 and 20 of each branch 17a, 17b are for example profiles in at least one of which an oblong opening 24 is arranged. In the embodiment presently described, the oblong opening 24 is arranged in the second part 20 of each of the branches 17a and 17b, and said opening 24 extends longitudinally in said second part 20.

[0047] While the fixing element 22 is for example a rod, metallic or in plastic material, such as a screw, a bolt, etc. inserted through said first and second parts, and in particular through the oblong opening of the second part 20.

[0048] Thus, the value of the force necessary to overcome the friction varies according to the mechanical coupling of said rod 22 with the first and second parts of each of the branches 17a and 17b, and more particularly with the walls of the second part 20 delimiting the oblong opening 24.

[0049] Said fixing element 22 can therefore be adjusted (for example by adjusting the coupling level) to modify the threshold value of the force allowing relative movement of the first and second parts 19 and 20 relative to each other.

[0050] Consequently, when the force applied to the armature foot 17, for example via the main body 5a of the armature 5, exceeds the predetermined threshold value, the fixing element 22 then moves into the oblong opening 24 of the second part 20 (the opening 24 acting as a guide for the rod 22), thus causing a displacement, by sliding, of the first part 19 in the second part 20. This displacement of the first and second parts 19 and 20 relative to each other thus causes a reduction in the length of the armature foot 17.

[0051] It will be noted that the movement of the first part 19 relative to the second part 20 is limited by the length of the oblong opening 24 provided in the second part 20, this oblong opening 24 advantageously having a length of between 70 and 150 mm, and preferably of between 80 and 120 mm.

[0052] In an alternative embodiment not shown, the oblong opening 24 is provided in the first part 19 of each of the branches 17a and 17b of said frame foot 17.

[0053] In another variant embodiment not shown, said lateral frame feet 15 comprise first and second parts 19 and 20, as well as a fixing element 22 as described above.

[0054] In another variant embodiment not shown, said central frame foot 17 comprises a single branch comprising one or more first and second parts 19 and 20, and fixing elements 22.

Claims

Claims

1. Bumper frame (5) for a motor vehicle, said frame (5) comprising at least one frame foot (17) configured to support a bumper beam (7), characterized in that said at least one frame foot (17) comprises a first part (19) and a second part (20) fixed to each other, said frame foot (17) being configured so that there is, when a force applied to said frame foot (17) exceeds a threshold value, a reduction in its length, by a relative movement of the first and second parts (19, 20) with respect to each other.

2. Frame (5) according to the preceding claim, characterized in that said frame (5) comprises a fixing element (22) which fixes the first and second parts (19, 20) together, said fixing element (22) being configured to allow relative movement of said parts (19, 20) relative to each other if a force applied to said frame foot (17) exceeds a threshold value.

3. Frame (5) according to any one of the preceding claims, characterized in that said first and second parts (19, 20) of said frame foot (17) are configured to slide relative to each other.

4. Armature (5) according to any one of the preceding claims, characterized in that said fixing element (20) is adjustable to modify the threshold value of the force allowing relative movement of the first and second parts (19, 20) relative to each other.

5. Armature (5) according to any one of the preceding claims, characterized in that the fixing element (20) is a rod inserted through said first and second parts (19, 20).

6. Armature (5) according to any one of the preceding claims, characterized in that at least one of said first and second parts (19, 20) comprises an oblong opening (24), the relative movement of the first and second parts (19, 20) with respect to each other being guided by said oblong opening.

7. Armature (5) according to any one of the preceding claims, characterized in that the relative movement of the first and second parts (10, 20) with respect to each other is between 70 and 150 mm.

8. Armature (5) according to any one of the preceding claims,

9. characterized in that the first and second parts (19, 20) extend, in the mounted position in a motor vehicle, in a substantially vertical plane. Bumper (1) for a motor vehicle, characterized in that said bumper (1) comprises a frame (5) according to any one of claims 1 to 8.

10. Motor vehicle, characterized in that said vehicle comprises a bumper (1) according to the preceding claim.

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