Vehicle fenders – Buffer or bumper type – Composite bumper
Reexamination Certificate
2000-01-14
2001-09-18
Dayoan, D. Glenn (Department: 3612)
Vehicle fenders
Buffer or bumper type
Composite bumper
C293S102000, C293S132000, C293S133000, C293S146000, C296S182100
Reexamination Certificate
active
06290272
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an energy absorber for motor vehicle bumpers with a number of stiffening elements arranged between a bumper bracket and a bumper shell of a bumper, wherein the stiffening elements have free-standing front sides facing away from a rear mounting structure that is capable of being fastened to the bumper bracket, and whose centers are also laterally offset from one another in the longitudinal direction.
DESCRIPTION OF THE RELATED ART
Such an energy absorber for motor vehicle bumpers is known from U.S. Pat. No. 3,506,295. The known energy absorber is stamped out of flat stock and has raised portions projecting on both sides relative to a reference plane at regular intervals, which are offset relative to one another in the longitudinal direction of the bumper. The side edges of the raised portions are joined to one another at their points of intersection, while the crests of the raised portions are flattened and intended for attachment to a bumper shell and a bumper bracket. Attachment to the bumper bracket and bumper shell is accomplished such that the energy absorber can extend in a longitudinal direction in the event of a collision, wherein the energy is distributed very effectively over the entire length of the energy absorber by means of the joining points. While the known energy absorber does have the advantage that the energy is transmitted effectively to the energy absorber, especially in the case of a severe collision with a relatively large object, this does, however, have the effect in collisions with objects that are relatively small in the energy absorber's transverse direction, as for example a human leg, of causing high accelerations on the relatively small object because of the relatively great stiffness of the energy absorber. This is particularly disadvantageous with regard to the greatest possible protection of pedestrians.
Another energy absorber is known from U.S. Pat. No. 3,843,182. This energy absorber has as stiffening elements a number of ribs that are oriented transverse to the longitudinal direction of a bumper bracket of a motor vehicle bumper. The ribs are joined together at their front ends facing away from the bumper bracket, and also at their edge sides, by means of a bumper shell which is manufactured as a single piece with the ribs, and are spaced away from the bumper bracket. Inserted between the ribs are block-like damping bodies. Although it is true that the connection of the ribs to one another prevents the bumper shell from buckling in a collision with a relatively small object because of the stabilization provided by a number of adjacent ribs in addition to the ribs located in the collision area, the amount of energy absorbed by the energy absorber is relatively small.
Known from DE 44 01 874 C1 is a damping element that can be placed between a bumper shell and a bumper bracket of a motor vehicle bumper and that has a rib structure, formed by two spring legs and a web connecting the spring legs, consisting of a longitudinal rib that extends in the bumper bracket's longitudinal direction and a number of transverse ribs oriented perpendicular to the longitudinal rib. While this gridlike rib structure does have elastic deformability even at high collision speeds, the amount of energy absorbed in a collision with a relatively small object is very low as a result of the compound structure of longitudinal rib and transverse ribs.
The object of the invention is to specify an energy absorber of the type mentioned at the outset that is characterized, firstly, by high energy absorption in collisions with objects the size of a human leg of standard dimensions, and secondly, by great stiffness in collisions with objects that are relatively large in comparison thereto.
SUMMARY OF THE INVENTION
This object is achieved in an energy absorber of the aforementioned type in accordance with the invention in that the lateral center-to-center distance corresponds to the standard dimensions of a human leg, in that the stiffening elements deform in the event of collision with an object the size of a human leg of standard dimensions with essentially unimpeded and mutually independent energy-absorbing deformation of side faces which face one another, and in that the stiffening elements engage one another at their side faces in a manner hindering deformation with an abrupt increase in the stiffness of the energy absorber in the event of collision with an object larger than the standard dimensions of a human leg.
The fact that the stiffening elements are arranged with a lateral separation from one another that is adapted to the dimensions of a human leg has the result that, when a collision with a human leg occurs, because of the essentially unimpeded energy-absorbing deformation of the adjacent side faces of independently acting stiffening elements that are plastically or elastically deformable at relatively low energy, the leg is braked with relatively low deceleration, so that the leg is subjected to relatively low acceleration as compared to energy absorbers of conventional design, and the risk of severe injury, especially to the knee area, is reduced. In collisions with relatively large objects, however, the stiffening interaction among the side faces of many stiffening elements causes an abrupt increase in stiffness in order to avoid damage to the vehicle.
In one embodiment, provision is made for the stiffening elements to be rib-like stiffening lamellae that extend over essentially the entire height and width of a bumper bracket and that have flat side surfaces as side faces. This embodiment is characterized by its ease of manufacture and light weight.
In a refinement thereof, provision is made for the stiffening lamellae to have corrugated side faces. In this way, predetermined bending lines are prepared at the corrugated areas of the side faces, which bring about controlled deformation of the stiffening lamellae.
In another embodiment, provision is made for the stiffening elements to be stiffening loops with a flattened, elongated front side and with loop edges joined at the transverse portions of the front side as side faces, wherein the loop edges are capable of connection to the bumper bracket by means of rear sections as a mounting structure, and loop edges of stiffening loops that are adjacent in the longitudinal direction are in contact with one another in a contact section. This embodiment achieves a relatively large support area for the bumper shell through the relatively large area of the front sides, wherein the stiffening loops possess a relatively high elastic deformability and a defined deformation behavior in the event of collision with a relatively large object.
In a further refinement of this last embodiment, provision is made for the stiffening loops to be arranged in two outer rows and one inner row located between the outer rows, wherein the stiffening loops of the outer rows are located opposite one another in pairs and the stiffening loops of the inner row are located midway between opposing pairs of outer-row stiffening loops. As a result of the offset arrangement of the stiffening loops, the areal support of the bumper shell is further improved.
Additional useful embodiments of the invention are the object of the following description of exemplary embodiments with reference to the Figures.
REFERENCES:
patent: 3506295 (1970-04-01), Yancey
patent: 3843182 (1974-10-01), Walls et al.
patent: 3871636 (1975-03-01), Boyle
patent: 3995901 (1976-12-01), Filbert, Jr. et al.
patent: 4105236 (1978-08-01), Haar
patent: 5425561 (1995-06-01), Morgan
patent: 5507540 (1996-04-01), Pernot
patent: 6082792 (2000-07-01), Evans et al.
patent: 6099055 (2000-08-01), Hirota et al.
patent: 44 01 874 C 1 (1995-07-01), None
Coletta Lori L.
Dayoan D. Glenn
Oppedahl & Larson LLP
Peguform GmbH
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