Vehicle fenders – Buffer or bumper type – Composite bumper
Reexamination Certificate
1999-06-21
2001-11-20
Pape, Joseph D. (Department: 3612)
Vehicle fenders
Buffer or bumper type
Composite bumper
C293S132000, C293S154000
Reexamination Certificate
active
06318775
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
The present invention relates to a composite bumper system including a reinforcement beam with molded components that optimize energy absorption of the bumper system.
It is known to roll-form or stamp a high strength beam as an initial step in constructing a vehicle bumper. For example see U.S. Pat. Nos. 5,092,512 and 5,454,504. A problem is that, after roll forming, several additional secondary processes must be performed before the beam can be used as a vehicle bumper. For example, mounting bracketry must be attached to the beam to provide for attachment of the beam to a vehicle. The mounting bracketry is usually attached by a secondary process, such as welding, which requires significant investment in welding equipment and also requires close process control. Additional secondary processes and/or metal end attached parts are often used to shape ends of the bumper to meet design demands, such as to provide an aerodynamically styled bumper that sweeps at the front corners of the vehicle. However, these metal end-attached parts and end-forming processes are often expensive and add considerable cost to a bumper system. Sometimes, flexible plastic end caps are used to trim out ends of the bumper. However, flexible plastic end caps do not provide corner impact strength, but instead are designed to flex out of the way while other structure provides impact resistance. It is desirable to provide a mounting arrangement that simplifies or eliminates much of the secondary processing and that reduces the number and cost of the secondary processes, but that provides structure to ends of the bumper for corner impact strength and for styling. Another problem is that bumper beams must be made very strong to withstand the high impact forces generated in a vehicle crash. A bumper beam that collapses prematurely or inconsistently will not pass government tests. However, it is also undesirable to have a beam that is so stiff that it absorbs very little energy during impact, because the unabsorbed energy is transferred directly to the vehicle and results in damage to other vehicle components. Optimally, the beam should flex in a manner absorbing a maximum amount of energy over a given stroke during the impact, so that crash forces are optimally spread out over the bumper stroke during impact in a manner minimizing damage to the vehicle. Improvements are desired that utilize the flexibility and moldability of plastics, but in a way that does not make the bumper sensitive to premature or inconsistent failure due to a low impact strength and crack sensitivity of structural plastics or their sensitivity to cold (or hot) environments.
Accordingly, a bumper construction solving the aforementioned problems and having the aforementioned advantages is desired.
SUMMARY OF THE PRESENT INVENTION
We have conceived of mounting a beam, such as a roll-formed swept beam having a constant cross section, to a vehicle frame by using polymeric structural end pieces. The structural end pieces each optimally include one or more of the following features: 1) an inboard wall with a recess for mateably receiving an end of the beam to both hold and stabilize the beam; 2) a rear wall or stay forming an attachment structure for attachment to a vehicle frame mounting tower; 3) a front wall angled at an outer end to form a rearwardly angled, aerodynamically shaped front surface with the beam; and 4) an outer end constructed for optimal corner impact strength. The result are surprisingly and unexpectedly low cost bumper systems having excellent front and comer impact resistance properties, and yet that are easily assembled, require fewer pieces, are low cost to produce, are made using existing processes, and that require low capital investment, The systems further are flexible, such that they permit adjustments and customization to deal with specific problems, even late in a bumper development program.
We further have conceived of using structural molded pieces to stabilize key impact-resisting flanges of a metal bumper beam, thus leading to an improved bumper construction with increased energy-absorbing characteristics. Advantageously, the components of the bumper construction facilitate assembly by telescoping together or by being co-extruded or insert molded.
In one aspect of the present invention, a bumper construction for vehicles includes an elongated high strength beam having opposing end sections, and a pair of structural molded end pieces made of polymeric material attached to and supporting the opposing end sections. The end pieces include attachment structure constructed to securely mount the bumper construction to a vehicle frame.
In another aspect of the present invention, a bumper construction for vehicles includes an elongated beam having end sections with first front walls, and polymeric structural end pieces attached to the beam. The structural end pieces include second front walls forming a longitudinally extending extension of the first front walls. The structural end pieces further each include marginal material defining a recess for closely receiving an associated one of the end sections, with the marginal material stabilizing a cross-sectional shape of the associated one end section. The structural end pieces characteristically provide structure to the bumper construction to pass industry corner impact testing of vehicle bumpers.
In another aspect of the present invention, a bumper construction for vehicles includes an elongated reinforcement beam including a planar impact-resisting flange that extends generally in a horizontal direction when in a vehicle-mounted position. The horizontal direction is parallel a direction where high impact strength is desired. At least one structural molded member has a stabilizing wall extending parallel the impact-resisting flange. The stabilizing wall engages an outer surface of the impact-resisting flange to stabilize the stiffening flange so that the impact-resisting flange does not unstably bend and prematurely lose its impact-resisting strength upon a vehicle impact. The at least one structural molded member thus forms a high strength vehicle bumper construction with the beam that is capable of withstanding substantial impact forces generated when the bumper construction is impacted in a vehicle crash.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.
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Heatherington David W.
Lewis Les
Lupone James
Morrow Jason
Pape Joseph D.
Price Heneveld Cooper DeWitt & Litton
Shape Corporation
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