Description:VEHICLE FRONT BUMPER HAVING ENERGY ABSORBER FOR PROTECTION OF PEDESTRIAN LEG
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to an energy absorber for vehicle, and, in particular, to an energy absorber for front bumper of the vehicle to absorb impact energy thus protecting leg of pedestrian and reducing injury to pedestrian upon impact. In more particularly, the present subject matter relates to an impact energy absorber which is optimised at selected impact zones, such as center impact zone and corner impact zone to absorbs the pedestrian impact energy and reduce injury to pedestrian leg.
BACKGROUND AND PRIOR ART:
[002] Current bumper systems are formed of plastic material to absorb impact energy during crash. Further, the bumper system has an energy absorber which absorbs energy during pedestrian impact with the vehicle. There are several zones, such as upper leg and lower leg where vehicle hit the pedestrian. The upper leg energy absorber is provided at the upper side of the bumper where upper part of radiator is mounted. Further, the lower leg energy absorber is provided at lower side where lower part of the radiator is mounted.
[003] Bumper of the vehicle makes contact with the pedestrian’s leg in the vicinity of knee while standing, walking, or running. There is a tendency for the pedestrian foot to remain placed on the ground due to inertia which forces the vehicle to the pedestrian’s leg to rotate about the foot or ankle and pedestrian falls on the bonnet of the vehicle. This impact causes severe knee injury and injury below the knee.
[004] To make the vehicle pedestrian safe, pedestrian safety requirements have to be followed. If any vehicle does not fulfill the pedestrian safety requirements, it would be dangerous for pedestrian. There are two types of pedestrian leg impactors, i.e., TRL test and Flex PLI test which can be used to evaluate the safety of pedestrian. With pedestrian safety requirements, front section of the vehicle can be qualitatively assessed according to the following criteria: 1) impact with an upper leg, 2) impact with a lower leg, 3) impact with the head on a bonnet of a motor vehicle.
[005] During the Flex PLI test, a collision speed of 40 km/h or 11.1 m/s is fixed to check whether the vehicle meets the fixed regulated criteria or not. In order to achieve the pedestrian safety requirements, different embodiments of bumper assemblies were proposed by the automobile industry for a front region of a passenger car faced with a casing. Several energy absorbers can be seen in the patent publications in FR2955302B1, JP5724769B2, and US 7163243 B2.
[006] There are two regions upper region and lower region in the vehicle front bumper which come into contact with the leg of the pedestrian during collision. The upper region consists of Femur portion of the leg and lower region consists of Knee and Tibia portion of the leg. Generally, the bumper is faced with an outer shell which amongst other things is to ensure a pleasant aesthetic external appearance and guarantee desired aerodynamics. The lower region has reinforcing element which is frequently also referred to as a so-called “lower bumper stiffener” (LBS for short) for “pedestrian-protection lower leg impact”, or can be designated as a reinforcement of the lower front bumper region for the protection of pedestrians in a leg impact. These reinforcing elements are made of foam or other highly cost materials which absorb the impact.
[007] Japanese Patent Publication JP5931518B2 discloses an impact absorbing member of the bumper which absorbs the impact energy of leg of pedestrian during collision. The energy absorber has a base plate, a longitudinal ribs and the bumper shock-absorbing member provided with transverse ribs in a lattice. Longitudinal ribs extended in the back and forth direction of a vehicle body and lateral ribs extended in a vehicle width direction are provided in a base plate in a lattice-like manner, and an interval between a first lateral rib of a forefront line in the front side of the vehicle body and a second lateral rib there behind is set larger than the interval of the longitudinal ribs, to form a lattice sectioned by the longitudinal ribs between the first lateral rib and the second lateral rib into a longitudinally long lattice. Longitudinally long holes are provided to the base plate in the longitudinally long lattice, horizontal lateral plate are formed in the front side of the first lateral rib, and reinforcing longitudinal ribs are provided to the lateral plates with an interval narrower than the interval of the longitudinal ribs between the first lateral rib and the second lateral rib. However this kind of energy absorber has considerable drawbacks due to low height of the impact region, these energy absorbers tilt the leg before hitting the upper absorber which is dangerous in lower leg impact. It breaks the bone of lower leg.
[008] Fig. 1a illustrates the placement of the energy absorber in the lower front region for absorbing the impact energy of lower leg. Fig. 1b illustrates the energy absorber made of foam and metal which can be mounted in the lower region of the front bumper to absorb the impact energy. In the Fig. 1a, the front bumper 102 is mounted on the front side of the vehicle. The front bumper 102 is mounted on beams which run in the upper and the lower region to hold the radiator. Further, the energy absorber 106 is mounted in between the front bumper 102 and the lower beam 104 of the chassis.
[009] In order to improve the energy absorbing efficiency of the front bumper, sometime foam based absorbers are position in between the bumper and the vehicle mounting rails. Adding of these absorbers results in the cost and weight of the bumper assembly of the vehicle which reduces the overall efficiency of the vehicle. Further, the lower leg energy absorbers are not efficient which can protect the lower leg from the impact. The existing energy absorbers try to tilt the body upon impact which is dangerous in the lower leg impact. Further, the existing energy absorbers are expensive and complex in designing and manufacturing. Therefore, there is a need in the art to provide an energy absorber that can be more simple and inexpensive, and which is optimized as per the impact zones to absorb the impact energy based on the location and force of impact imparted to the pedestrian's lower leg.
OBJECTS OF THE INVENTION:
[0010] The principal objective of the present invention is to provide an energy absorber which prevents the bending of pedestrian leg by absorbing impact energy in the event of pedestrian collision with vehicle front end.
[0011] Another object of the present subject matter is to provide an energy absorber to absorb lower leg impact energy during collision of vehicle with pedestrian from front side.
[0012] Another object of the present subject matter is to provide an optimized energy absorber which provides required stiffness to the front bumper assembly of the vehicle.
[0013] Yet another object of the present invention is to provide an energy absorber which is simple and inexpensive, and efficiently absorbs the impact energy without major injury to lower leg of the pedestrian.
SUMMARY OF THE INVENTION:
[0014] The subject matter disclosed herein relates to an energy absorber which is positioned in between the front bumper and lower beam of the vehicle. The energy absorber is mounted on the lower front longitudinal beam where lower part of radiator is mounted. The energy absorber is made of single sheet metal. The present energy absorber is optimized to achieve high energy absorbing capabilities. The energy absorber is concave in shape and mounted on the front side of the vehicle behind the front bumper. The present energy absorber is divided into three zone, i.e., center zone, middle zone, and corner zone.
[0015] On the present energy absorber, a plurality of beads is provided on the complete surface of the energy absorber at equal distance along the length. Each of the beads from the plurality of beads is provided at equal distance from each other. There flanged and non-flanged holes in the energy absorber are provided to optimize the stiffness of the energy absorber. The flanged and non-flanged holes are provided in between two consecutive beads. The holes are provided on the surface of lower absorber to control the deformation such that the Tibia injuries are within specified regulatory limits. Further, no hole is provided in the corner zone which requires higher stiffness compared to the center zone. During the impact the corner zone requires less energy absorbing capabilities as compared to the central and middle zone as it is important to prevent the hitting of pedestrian leg with hard structural members at the corners.
[0016] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0018] Fig. 1a illustrates placement of energy absorber for lower leg in the front bumper of the vehicle;
[0019] Fig. 1b illustrates foam based energy absorber as known in the art;
[0020] Fig. 2 illustrates impact points for upper knee and lower knee with the front bumper of the vehicle, in accordance with an embodiment of the present subject matter;
[0021] Fig. 3 illustrates structure of energy absorber during impact of pedestrian with the front bumper of vehicle, in accordance with an embodiment of the present subject matter;
[0022] Fig. 4 illustrates the energy absorber, in accordance with an embodiment of the present subject matter;
[0023] Fig. 5(a) illustrates various optimized zones of the energy absorber, in accordance with an embodiment of the present subject matter;
[0024] Fig. 5(b) illustrates center zone of the energy absorber, in accordance with an embodiment of the present subject matter;
[0025] Fig. 5(c) illustrates middle zone between the center zone and corner zone of the energy absorber, in accordance with an embodiment of the present subject matter;
[0026] Fig. 5(d) illustrates corner zone of the energy absorber, in accordance with an embodiment of the present subject matter;
[0027] Fig. 6 illustrates mounting of the energy absorber at the lower front beam of the vehicle, in accordance with an embodiment of the present subject matter;
[0028] Fig. 7 illustrates the cross section A-A view of the mounted energy absorber with the front beam of the vehicle, in accordance with an embodiment of the present subject matter;
[0029] Fig. 8 illustrates a graph showing effect of the energy absorber on the knee ligament elongation during collision of pedestrian with the front side of the vehicle, in accordance with an embodiment of the present subject matter; and
[0030] Fig. 9 illustrates a graph showing effect of the energy absorber on tibia bending moment during collision of pedestrian with the front side of the vehicle, in accordance with an embodiment of the present subject matter.
[0031] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0032] The subject matter disclosed herein relates to an energy absorber which is positioned in between the front bumper and lower beam of the vehicle. The energy absorber is mounted on the lower front longitudinal beam where lower part of radiator is mounted. The energy absorber is made of single sheet metal. The present energy absorber is optimized to achieve high energy absorbing capabilities. The energy absorber is concave in shape and mounted on the front side of the vehicle behind the front bumper. The present energy absorber is divided into three zones, i.e., center zone, middle zone, and corner zone.
[0033] On the present energy absorber, a plurality of beads is provided on the complete surface of the energy absorber at equal distance along the length. Each of the beads from the plurality of beads is provided at equal distance from each other. There flanged and non-flanged holes in the energy absorber are provided to optimize the stiffness of the energy absorber. The flanged and non-flanged holes are provided to achieve required stiffness as absence of these holes will offer high stiffness which may lead to high tibia injuries. Further, no hole is provided in the corner zone which gives highest stiffness to this zone. During the impact the corner zone requires higher stiffness compared to the central and middle zone so that pedestrian leg does not come in contact with hard structural members at corners.
[0034] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0035] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0036] Fig. 3 illustrates safety regulations for the pedestrian impact with front side of the vehicle. There are two types of pedestrian leg impactors, i.e., TRL and Flexi PLI which can be used to evaluate vehicle for pedestrian leg impact performance assessment before manufacturing of the final product. To make the vehicle pedestrian safe, pedestrian safety requirements has to be followed. If any vehicle does not fulfill pedestrian safety requirements, it would be dangerous for pedestrian. From these tests front section of the vehicle can be qualitatively assessed according to the following criteria: 1) impact with an upper leg, 2) impact with a lower leg, and 3) impact with the head on a bonnet of a motor vehicle.
[0037] During the Flex PLI test as per pedestrian safety requirements, a collision speed of 40 km/h or 11.1 m/s is fixed to check whether vehicle meets the desired regulated criteria or not. Table 1 gives injury parameters for desired pedestrian safety limits:
Table 1:
Sl. No Injury Location Evaluation Parameter Type of injury
1 Knee MCL [mm] Knee ligaments elongation
2 ACL [mm]
3 PCL [mm]
4 Tibia Tibia-1 [Nm] Tibia bone bending moment
5 Tibia-2 [Nm]
6 Tibia-3 [Nm]
7 Tibia-4 [Nm]

[0038] Fig. 2 illustrates the comparison of the impactor with the human model. In the fig. 2, 202 is the flex impactor model and 204 is human model. The flex impactor 202 and human model 204 shows the hitting point of vehicle to the leg of the human. In this front face bumper test zone, knee measurement (MCL elongation 206 and Tibia measurement (tibia bending moment) 208 shows various impact zones. Table 1 illustrates various evaluation parameters for both the zones. To make a vehicle safe for the pedestrian, the vehicle has to meet these pedestrian safety requirements. The present subject matter impact both the knee and tibia region of the leg.
[0039] Fig. 3 illustrates the energy absorber, in accordance with an embodiment of the present subject matter. In the present energy absorber 300 has center zone 304, middle zone 306 and corner zone 302 with variable energy absorbing capacity. The complete energy absorber 300 is in concave shape. The energy absorber 300 is made of single material, such as sheet metal, specifically, JAC270CN-45/45. The thickness of the sheet material is 0.7mm. Further, the center zone 304 has more width as compared to middle zone 306 and the corner zone 302. The corner zone 302 has smallest width as compare to the center zone 304 and the middle zone 306. The middle zone 306 has width in between the center zone and the corner zone. The width of the energy absorber 300 decreases gradually from the center zone 304 to the corner zone 302. The front face of the energy absorber 300 is bent in downward direction. The energy absorber 300 is provided in between the front bumper and lower beam of the vehicle. The energy absorber 300 is mounted on the vehicle beam at plurality of locations, such as at center and at corners. The energy absorber 300 extends in forward direction from the mounting points. The energy absorber 300 a plurality of beads on the complete surface of the energy absorber at equal distance from each other to provide necessary stiffness to the energy absorber 300.
[0040] Fig. 4 and 5(a) illustrate cross section view of the energy absorber, in accordance with an embodiment of the present subject matter. The present cross section view clearly illustrates the center zone 304, the middle zone 306, and the corner zone 302. Fig. 5(b) illustrates the cross section view of the center zone 304 of the energy absorber 300, in accordance with the present subject matter. The energy absorber 300 has a plurality of beads 507 on the complete surface of the energy absorber 300. Each of the beads 507 from the plurality of beads 507 is provided at equal distance from each other. The plurality of beads 507 provides necessary stiffness and strength to the energy absorber 300. In the center zone 304, a plurality of non-flanged holes 508 are provide to give stiffness. Each of the non-flanged holes 508 is provided in between the two beads at equal distance from each other. In between the beads, a flat surface 509 is provided. The plurality of non-flanged holes 508 provides high absorbing capabilities to the center zone 304. Further, the front width of the center zone 304 is higher than the middle zone 306 and the corner zone 302.
[0041] Fig. 5(c) illustrates the cross section view of the middle zone 304 of the energy absorber 300, in accordance with the present subject matter. The middle zone 306 is provided in between the center zone 304 and the corner zone 302 of the energy absorber 300 at both sides. The middle zone 306 has plurality of beads 507 which are provided at equal distance from each other. The middle zone 306 has plurality of flanged holes 510 to optimize stiffness as compared to the center zone 304. The flanges of the flanged holes 510 give strength and stiffness to the middle zone 306. Each of the flanged holes from the plurality of the flanged holes 510 are placed at equal distance from each other. Based on the width of the middle zone 306, the shape and size of the flanged holes 510 are different from each other. The shape and size of the flanged holes are optimized to achieve the better results. The stiffness of different zones are optimized so as to achieve required performance level. Holes are provided to control the deformation of lower absorber whereas beads are added at locations where it was required to prevent deformation of absorber so that impactor doesn’t come in contact with hard structural members.
[0042] Fig. 5(c) illustrates the cross section view of the corner zone 302 of the energy absorber 300, in accordance with the present subject matter. The corner zone 302 is provided at both ends of the energy absorber 300. Further, the corner zone 302 has no hole which gives highest stiffness compared to other zones. The corner zone 302 has flat surface along with plurality of beads 507 which gives the highest stiffness to the corner zone 302. The corner zone 302 extends at an angle from the middle zone 306 which is 20o approx. The corner zone 302 is mounted on the vehicle beam at both ends.
[0043] Fig. 6 illustrates mounting of the energy absorber 300 on lower front longitudinal beam of the vehicle, in accordance with the present subject matter. The energy absorber 600 (300 in the figure 3) is mounted on the lower front longitudinal beam 602 at several points. Specifically, the energy absorber 600 is mounted at corner and at center location with the lower front longitudinal beam 602.
[0044] Fig. 7 illustrates the cross sectional view of the mounted energy absorber 600 on the lower front longitudinal beam 602, in accordance with the present subject matter. The cross sectional view 700 illustrates the mounting of the energy absorber 700 on the lower front longitudinal beam 700b (602 as shown in the figure 6). The energy absorber 600 is provided in between the front bumper 700a and the lower front longitudinal beam 700b. The front face 702 of the energy absorber 600 is bent in angular downward direction from the front. First contact point 702 of the energy absorber 700 is bent in downward angular direction to distribute the impact force on the complete energy absorber. There is a small gap 714 in between the energy absorber 700 and the front bumper 700a. The gap 714 is range of 2 to 20 mm, specifically 5-10mm. The energy absorber 700 is bent in downward direction from the rear side and formed a rear bent flange 710. The energy absorber 700 is mounted on the lower front longitudinal beam 700b with rear bent flange 710. The energy absorber 700 is mounted on the lower front longitudinal beam 700b with the help of screw. The energy absorber 700 can be mounted on the lower front longitudinal beam 700 by any other means, such as welding, snap fitting, and rivet fitting. The flat surface 706 of the energy absorber has plurality of beads (as shown in figure 3-5) and plurality of holes with flange and without flange. There is a small gap 708 between the lower front longitudinal beam 700b and the energy absorber 700. The small gap 708 is in range 4 to 20 mm, specifically 5-10mm. The gap 708 and the gap 714 can be optimized as per the requirement of the vehicle and vehicle layout. During the impact of the pedestrian on the front side of the vehicle, the energy absorber 700 absorbs the energy and bends in the downward direction along with the angular bent 702 of the energy absorber 700. By bending in the downward direction, the energy absorber 700 absorbs the impact energy and protects the pedestrian leg from injury.
[0045] Fig. 8 illustrates a graph showing effect of addition of the energy absorber on the knee ligament elongation during collision of pedestrian with the front side of the vehicle, in accordance with an embodiment of the present subject matter. In the figure 8, the graph shows the comparison of knee ligament elongation in the vehicle having absorber and vehicle having no absorber.
[0046] Fig. 9 illustrates a graph showing effect of addition of the energy absorber on the Tibia bending moment during collision of pedestrian with the front side of the vehicle, in accordance with an embodiment of the present subject matter. In the figure 9, the graph shows the comparison of tibia bending moment during impact of the pedestrian with the vehicle.
[0047] Due to optimization of the plurality of beads and shape of the holes on the energy absorber, it becomes possible to achieve high energy absorbing capabilities from the single molded piece of the sheet metal. The hole with and without flanges give the necessary weak zones at the required locations. The present energy absorber is simple and inexpensive.
[0048] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

Claims:We claim:
1. An energy absorber (300, 600) for front bumper of vehicle to protect pedestrian leg during impact of the vehicle with pedestrian, the energy absorber (300, 600) comprising:
corner zone (302);
middle zone (306); and
center zone (304), wherein the center zone (304) is wider than the middle zone (306) and the corner zone (302), and center zone (304) has a plurality of non-flanged holes (508) to provide energy absorbing capabilities to protect the pedestrian leg during impact.

2. The energy absorber (300, 600) as claimed in claim 1, wherein the corner zone (306) is positioned at left and right side of the center zone (304) and middle zone (306).

3. The energy absorber (300, 600) as claimed in claim 1, wherein the corner zone (306) is mounted on lower front longitudinal beam (700b) of the vehicle at both sides.

4. The energy absorber (300, 600) as claimed in claim 1, wherein the energy absorber (300, 600) has a plurality of beads (507) across length of the energy absorber (300, 600) to provide adequate stiffness.

5. The energy absorber (300, 600) as claimed in claim 1, wherein the middle zone (306) has a plurality of flanged holes (510) to provide energy absorbing capabilities to the energy absorber (300, 600).

6. The energy absorber (300, 600) as claimed in claim 1, wherein the energy absorber (300, 600) is bent in angular downward direction from front side.
7. The energy absorber (300, 600) as claimed in claim 1, wherein the energy absorber (300, 600) is made of single sheet metal.

8. The energy absorber (300, 600) as claimed in claim 1, wherein the energy absorber (300, 600) is mounted at plurality of positions on lower front longitudinal beam (700b).

9. The energy absorber (300, 600) as claimed in claim 1, wherein the energy absorber (300, 600) is in concave shape and mounted on the lower area of front side of the vehicle, wherein the energy absorber (300, 600) is provided in between vehicle front bumper and lower front longitudinal beam (700b), wherein a gap (714) is provided in between the energy absorber (300, 600) and the vehicle bumper (700a), wherein a gap (708) is provided in between the energy absorber (300, 600) and the lower front longitudinal beam (700b).