Vehicle fenders – Buffer or bumper type – Having fluid means within impact means to absorb energy
Reexamination Certificate
1998-07-21
2001-10-30
Dayoan, D. Glenn (Department: 3612)
Vehicle fenders
Buffer or bumper type
Having fluid means within impact means to absorb energy
C293S120000, C293S132000
Reexamination Certificate
active
06308999
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a bumper for motor vehicles in which an energy absorbing subsystem is incorporated into the bumper. More particularly, the invention relates to metal bumpers having an energy absorbing subsystem incorporated into the bumper.
BACKGROUND ART
Vehicle bumper systems are generally designed to serve two functions. The first function is to minimize visible permanent damage in the vehicle from low speed contacts with obtacles. Low speed collisions are generally defined as collisions at 5 miles per hour or less. The bumper system should withstand these low speed collisions without visible permanent damage, either to the vehicle bumper system or to the vehicle. Another function of a vehicle bumper system is to manage kinetic energy in a higher speed collision to avoid or reduce injury to the vehicle passengers. High speed collisions are those greater than 5 miles per hour. High speed collisions will likely result in visible permanent damage to either the vehicle bumper system or the vehicle. The way in which kinetic energy from the collision is managed through the bumper system and the vehicle is by providing a known and repeatable collapse of the energy absorbing subsystem.
It is desirable to manufacture a bumper that is both lightweight and have desired strength characteristics. Some current lightweight bumpers are manufactured with injection molded plastic material. Several U.S. patents have published designs for blow molded automotive bumper systems having an integral attaching bracket. The attaching bracket is generally made of metal and serves to attach the bumper system to the vehicle. Two brackets secure the bumper system to the vehicle. Each bracket is generally mounted near the outer edge of the bumper system and serve to transmit collision energy repeatably through the bumper system to the vehicle.
It is useful to provide a vehicle bumper system that has the required stiffness, yet is strong enough to minimize visible permanent damage in low speed collisions. Making bumpers sufficiently rigid to withstand both low speed collisions without visible permanent damage on the outside and higher speed collisions with proper kinetic energy management requires the use of thick blow molded wall sections and thereby increasing material cost and bumper systems' weight.
It has also been known to add foam within a vehicle bumper. Foam energy absorbers have been pre-molded and then assembled in place within the bumper. Use of such pre-molded foam blocks requires the use of adhesives or fasteners and large access holes to attach the foam to the bumper system. It is desirable to place foam within a bumper system without the need for adhesives, fasteners or large access holes.
Accordingly, it would be advantageous to provide a vehicle bumper system that is capable of withstanding low speed collisions without visible permanent damage, while providing an adequately rigid and strong cross-frontal area to controllably transmit kinetic energy from high speed collisions to the vehicle.
The primary object of the present invention is to provide a lightweight bumper for vehicles which avoids the shortcomings of the prior art.
Another objective of the present invention is to provide a bumper system for vehicles which is characterized by a relatively simple manufacture enabling relatively low assembly costs.
Yet another object of the present invention is to provide a bumper for vehicles which lends itself to mass production.
Still another object of the present invention is to provide a bumper for vehicles that is capable of withstanding low speed collisions without visible permanent damage, while fitting in limited packaging space allotted by the car designer.
These and other objects and advantages of the present invention will be more fully understood and appreciated with reference to the following description.
SUMMARY OF THE INVENTION
The foregoing problems are overcome by providing a vehicle bumper system having an elongated reinforcing member extending substantially across the width of the vehicle. The reinforcing member can be made from metal or fiber reinforced plastic and has a generally &Sgr;-shaped cross section which is filled with energy absorbing foam. The &Sgr;-shaped cross section is preferably formed by extrusion. Preferred compositions of the reinforcing member is an aluminum alloy selected from the group of 5XXX, 6XXX and 7XXX alloys. During impact, the foam absorbs some impact energy and distributes the forces of impact to the &Sgr;-shaped cross section of the reinforcement beam so that free ends each rotate in opposite directions inwardly about its center longitudinal axis.
The foregoing vehicle bumper system is manufactured by extruding an aluminum alloy, and then filling the &Sgr;-shaped cross section with an energy absorbing foam. The foam may be injected into the mold containing the &Sgr;-shaped extrusion. The foam material solidifies to the reinforcement beam to form a hybrid bumper assembly.
The present invention allows the hybrid bumper assembly to absorb low speed collisions without visible permanent damage. The foam material in the space/cavity of the &Sgr;-shaped extrusion
provides resistance to compression and rebound at low speed impact, and
distributes the forces of impact along the width of the &Sgr;-shaped extrusion.
The invention is suitable for front and rear bumper systems as well as side bumper systems.
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Seksaria Dinesh C.
Tan Soo A.
Alcoa Inc.
Dayoan D. Glenn
Engle Patricia
Pearce-Smith David W.
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