[0001] This application claims benefit under 35 USC § 119(e) of provisional application

Serial No. 61/450,852, filed March 9, 2011, entitled VEHICLE ENERGY ABSORBER FOR PEDESTRIAN'S UPPER LEG, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] The present invention relates to vehicle front ends adapted for reducing injury to a pedestrian upon impact, and more particularly relates to a vehicle energy absorber apparatus in the upper front area of a vehicle front end, where the energy absorber apparatus includes an energy absorber with crush lobes that absorb energy upon impact thus reducing injury to a pedestrian's upper leg or child's head.

[0003] Traditionally, vehicles are constructed to provide safety to vehicle occupants during a crash. Improvements are desired to maintain that objective, but also provide improved safety to a pedestrian. In particular, a pedestrian is typically struck by a front of a moving vehicle, with the vehicle bumper, front of hood, and other front end

components transmitting a relatively high force and energy into the pedestrian. This can result in significant body injury, including injury to the pedestrian's legs during initial impact, followed by upper body and head injury as the pedestrian or child tumbles toward the vehicle and onto the vehicle's hood.

SUMMARY OF THE PRESENT INVENTION

[0004] In one aspect of the present invention, an apparatus for improved pedestrian safety includes a vehicle front end including a hood, a bulkhead and structural components located generally above the bumper and near a front of the hood; and an energy absorber having at least one hollow crush lobe and an attachment flange. The energy absorber is positioned near at least one of the bulkhead and the structural components with the at least one crush lobe extending away from the bulk head in a position where, upon a pedestrian impact directed toward an upper portion of the bulkhead, sidewalls of the at least one crush lobe crumple and collapse to absorb energy.

[0005] In another aspect of the present invention, an improvement is made to a vehicle including a hood, a bulkhead and front end components located generally in an upper portion of the bulkhead near a front of the hood, the bulkhead including a top horizontal beam. The improvement includes an energy absorber having at least one hollow crush lobe and an attachment flange attached to one of the bulkhead and front end

components with the at least one crush lobe extending away from the bulk head in a position where, upon a pedestrian impact directed toward the bulkhead, sidewalls of the at least one crush lobe crumple and collapse toward the beam to absorb energy.

[0006] In another aspect of the present invention, a method of improving pedestrian safety when impacted by a vehicle, where the vehicle includes a hood, a bulkhead and structural components near a front of the hood. The method comprises steps of providing a top horizontal beam of the bulkhead; providing an energy absorber having at least one hollow crush lobe and an attachment flange; positioning the energy absorber in front of and near to the bulkhead with the at least one crush lobe extending away from the bulk head in a position where, upon a pedestrian impact directed toward the bulkhead, sidewalls of the at least one crush lobe crumple and collapse toward the beam to absorb energy.

[0007] These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0008] Fig. 1 is a side elevational view of a vehicle front end and three standardized

impactors that simulate an adult pedestrian's leg (post-like device impacting from horizontal direction), upper-leg (block-like device impacting from angle at front of hood), and head (ball-like device impacting from angle at center of hood), respectively, the testers being useful for testing for pedestrian safety.

[0009] Fig. 2 is a side elevational view of the vehicle front end and the angle-impacting upper-leg impactor, showing an angle of impact and a general direction and follow through of impact, the impactor having an adjustable mass and a relatively flat leading edge.

[0010] Figs. 3-5 are perspective views of first, second, and third energy absorbers,

respectively, each being attached to a structural component, and Fig. 5A is a vertical cross section transversely through Fig. 5.

[0011] Fig. 6 is a fragmentary perspective view showing a vehicle front end, including the energy absorber and structural components and the mid-level impactor prior to impact.

[0012] Fig. 7 is a fragmentary perspective view similar to Fig. 6 but after sufficient impact by the upper-leg impactor to contact a crush lobe of the energy absorber.

[0013] Fig. 8 is a fragmentary perspective view similar to Fig. 6, but with several

components removed to better show the energy absorber, the energy absorber having a single crush lobe positioned adjacent a hood latch of the vehicle.

[0014] Fig. 9 is a graph showing bending moment versus time for three impacts, each including a similar energy absorber but with different wall thicknesses, iterations C, D and

E having wall thicknesses of 2 mm, 1 mm and 3 mm wall thickness.

[0015] Fig. 10 is a graph showing force output versus time for the same three impacts shown in Fig. 9, each impact including a similar energy absorber but with different wall thicknesses.

[0016] Fig. 11 is a chart showing different force and bending moments for different front end arrangements, the iterations C-E including different energy absorbers as noted above in Figs. 9-10.

DESCRIPTION OF PRIOR ART

A vehicle 100 (Figs. 1-2) includes, among other things, a bumper system 101 with reinforcement beam 102, fenders 103, hood 104, front fascia 105, grille 106, and upper front end structural components 107 generally hidden from view but constructed to support the aforementioned items. Pedestrian-simulating impactors include a leg- simulating impactor 110 for impacting the bumper system, an upper-leg-simulating impactor 111 for impacting an upper front area of a vehicle at a first angle to horizontal, and a head-simulating impactor 112 for impacting a hood area at a more-vertical steeper angle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] An apparatus 20 (Fig. ) for improved pedestrian safety during impact includes a vehicle having a bumper system 21 with reinforcement beam 21A, a hood 22, and structural components 23 located generally above the bumper 21 and in front of the hood 22. An energy absorber 24 having at least one hollow energy-absorbing crush lobe 25 is attached to one of the structural components 23, such as a latch-supporting/grille- supporting structural member 26. The energy absorber 24 is in a low-visible position when the hood 22 is closed, but with the energy absorber's crush lobe 25 positioned to crush and absorb energy to reduce injury to a pedestrian's upper leg (or child's head) when impacted by the vehicle.

Fig. 3 shows two energy absorbers 24, one adjacent each side of the hood latch.

Each energy absorber 24 has one crush lobe 25 and is attached to a top of the structural member 26, with a part of its body extending forwardly therefrom. The crush lobe 25 is generally a hollow box-shape (or cone-shape or wedge-shape) so that its sidewalls crumble and crush during an impact to absorb a maximum amount of energy. A top wall of the illustrated energy absorber fits relatively close to the upper/outer front sheet metal (or hood), such that the top wall is angled and slightly curved. By placing the top wall close to the adjacent outer surface, the energy absorber 24 begins to crush relatively soon after the initial impact, thus providing a maximum crush stoke for distributed energy absorption. The illustrated energy absorbers 24 each include aperture flanges, and are attached to the structural member 26 by a fastener, such as a screw, push-pin, rivet, snap fastener, or hook-attachment system. The illustrated energy absorbers 24 are injection molded of a non-foam polymeric material (e.g. polypropylene, polyolefin, or TPO material) that absorbs energy when crushed, such as are commercially available. However, it is contemplated that different materials can be used and that different attachment structures can be used. It is also contemplated that the energy absorbers 24 could be over-molded onto the structural member 26 or integrally formed therewith. The illustrated energy absorber has its base flange abut a top surface of the top horizontal beam of the bulkhead, and its aperture attachment flange is attached to the top of the horizontal beam by push-pin fasteners or screws. However, it is contemplated that it could be attached to other structural components of the vehicle front end. The illustrated crush lobes each include a plurality of interconnected sidewalls that extend from the base flange, and a top wall interconnecting the sidewalls and closing the hollow crush lobe. Connecting strips are formed by the base flange between adjacent crush lobes to create a unitary product that can be injection molded by a single material in a one-shot process.

[0020] Several variations are contemplated. For example, the illustrated energy absorber

24 is made of polymeric material, but it is contemplated that other materials could be used. The illustrated energy absorber 24 is a separate component mechanically attached to a structural component forming an upper front of a vehicle; however it could be adhered or overmolded onto the structural component. Also, the energy absorber (24) could be attached to and carried by fascia covering a front of the vehicle such that it is positioned in front of the top bulkhead beam, instead of being directly attached to the bulkhead. The illustrated energy absorber 24 extends onto and abuts an adjacent two orthogonal surfaces of the one structural component (i.e. it abuts a top and front surface of the top beam of the structural component). Notably, the energy absorber could be integrally molded as part of a structural component, such as by a two shot molding or overmolding process. Advantageously, the present energy absorber 24 includes a crush lobe 25 that extends/wraps onto and abuts two adjacent surfaces of the structural component, such that the energy absorber is better able to undergo a crushing collapse resulting in "good" energy absorption when impacted along an angled direction of impact, such as by an impacted pedestrian (see Fig. 1, impactor 111).

[0021] Fig. 4 is a view similar to Fig. 3, but in Fig. 4 the energy absorber 24A has two crush lobes 25A that extend generally forwardly and that are positioned generally in front of the top beam of the structural member 26A. The energy absorber 24A may or may not have a crush lobe positioned on top of the top wall of the structural member 26A. This depends on functional requirements of the vehicle. For example, in some trucks and other vehicles having a relatively high front end and relatively squared-off, front end the positions of crush lobes may be considerably different than in other vehicles that have a lower front end and more aerodynamic shape (see Figs. 1-2).

[0022] Fig. 5 is a view similar to Figs. 3-4, but in Fig. 5 the energy absorber 24B is a single molding with five crush lobes 25B, the center crush lobe 25B being located generally inline with a center of the vehicle and with the vehicle's hood latch (not shown). Each crush lobe 25B has a rear portion positioned on the top of the structural member 26B, and has a forwardly-extending portion that extends forward of the structural member

26B. As shown in Fig. 5A, a top wall of each crush lobe 25B is curved forwardly and downwardly to match an aerodynamic shape of a front of the vehicle. About a front third of the crush lobe 25B forms a wedge shape with a relatively pointed front edge. It is noted that the crush lobes 25B are relatively uniformly spaced and extend vertically and are forwardly elongated, such that they provide particularly good impact absorbing characteristics for a child's head.

[0023] Fig. 6 is a fragmentary perspective view showing a computer generated image of a vehicle front end, including the energy absorber 24C and structural components 26C and the upper-leg impactor 111 prior to impact, and Fig. 7 is after impact but prior to completed impact. The stroke of impact depends of course on numerous variables related to vehicle speed, the pedestrian's positions and reaction to impending impact, and the vehicle and pedestrian general characteristics.

[0024] Fig. 8 illustrates an energy absorber 24C positioned on a front surface of a top beam of a structural member 26C. The crush lobe 25C of the energy absorber 24C is configured to collapse and absorb energy during a pedestrian impact.

[0025] Fig. 9 is a graph showing bending moment versus time for three impacts by a mid- level impactor that impacts at an angled direction, each including an energy absorber (24) of similar material, shape and size, but with different wall thicknesses. Specifically, iteration C includes a 2 mm wall thickness, iteration D includes a 1 mm wall thickness, and iteration E includes a 3 mm wall thickness. As shown in the Fig. 9, the iteration D (1 mm wall thickness) has a lesser energy absorption of about 300 kN/mm at 10 ms (millisecond) intrusion, while the iteration C (2 mm wall thickness) has a mid-amount energy absorption of about 370 kN/mm at 10 ms, and the iteration E (3 mm thickness) has a greater energy absorption of about 460 kN/mm at 10 ms. However, this reverses at 18.75 ms, with iteration D being about 475 kN/mm, iteration C being about 380 kN/mm and iteration E being about 350 kN/mm.

[0026] Fig. 10 is a graph showing force output moment versus time for three impacts by a mid-level impactor that impacts at an angled direction, each including an energy absorber (24) of similar material, shape and size, but with different wall thicknesses. Specifically, like in Fig. 9, iteration C includes a 2 mm wall thickness, iteration D includes a 1 mm wall thickness, and iteration E includes a 3 mm wall thickness. As shown in the Fig. 10, the iteration D (1 mm wall thickness) has a lesser force of about 625 kN at 10 ms (millisecond) intrusion, while the iteration C (2 mm wall thickness) has a mid-amount force of about 725 kN at 10 ms, and the iteration E (3 mm thickness) has a greater force of about 850 kN at 10 ms. However, this reverses at 18.75 ms, with iteration D being about 975 kN, iteration C being about 800 kN and iteration E being about 700 kN.

[0027] Fig. 11 is a chart illustrating a sum force and sum bending moment (kN/mm) for each of iterations C, D and E. As shown, the sum force for iterations C (2 mm wall thickness), D (1 mm wall thickness), and E (3 mm wall thickness) are 9.04 kN, 9.90 kN, and 9.08 kN, respectively. Similarly, the sum bending moment for iterations C, D, and E are 460.75 kN/mm, 489.69 kN/mm and 502.43 kN/mm.

[0028] It is to be understood that variations and modifications can be made on the

aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.