Bumper reinforcement

Details Bumper reinforcement Bumper reinforcement

2003-05-14

2004-11-09

Morrow, Jason (Department: 3612)

Vehicle fenders

Buffer or bumper type

Composite bumper

Reexamination Certificate

active

06814380

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bumper reinforcement having an open section structure including a front face, an upper face and a lower face.
2. Description of the Related Art
A bumper belonging to the safety parts of an automobile is constructed by a bumper reinforcement as a strength member and a bumper cover as a decoration member. The bumper reinforcement can be divided into one having a closed section structure and another having an open section structure. The bumper reinforcement having the closed section structure is disclosed in JP-A-2000-334530, JP-A-2001-199292, JP-A2001-260773, JP-A-2001-227573, U.S. Pat. No. 5,080,411 and so on. On the other hand, the bumper reinforcement having the open section structure is disclosed in JP-A-09-095189, U.S. Pat. No. 4,492,398, U.S. Pat. No. 4,998,761 and so on.
The bumper reinforcement having the closed section structure is advantageous as the strength member. On the other hand, the bumper reinforcement having the open section structure is advantageous to be manufactured easier with high cost performance. In order to incorporate the superior points of these structures into each other, therefore, improvements have been proposed by attaching an auxiliary reinforcement (e.g., a cover having abridging structure in which leg portions are fixed on an upper face and a lower face and which is spaced from a front face) to the front face of the bumper reinforcement, and shown in Japanese Utility Model Registration No. 2554459, USP No. 2002/0047281, DE199 12 272 A1, JP-A-09-095189, U.S. Pat. No. 4,492,398, U.S. Pat. No. 4,998,761 and so on.
The reason why the bumper reinforcement having the open section structure is inferior in the structural strength is caused by the fact that when the front face of the bumper reinforcement receives an impact, the upper face and the lower face of the bumper reinforcement are vertically opened about their boundaries of the front face thereby to lower the modulus of section of the bumper reinforcement. When the upper face and the lower face of the bumper reinforcement are opened, more specifically, the capacity for absorbing the impact energy is reduced to lower the shock absorbing performance as the bumper reinforcement.
In order that the bumper reinforcement having the open section structure may be worth to high structural strength and shock absorbing performance of the bumper reinforcement having the closed section structure, it is then sufficient to prevent the upper face and the lower face of the bumper reinforcement from being opened when the bumper reinforcement receives an impact. Therefore, investigations have been made to develop a bumper reinforcement having the open section structure, which is enabled to exhibit such high structural strength and shock absorbing performance by preventing the upper face and the lower face of the bumper reinforcement from being opened as are not inferior to the bumper reinforcement having the closed section structure.
Here is a case in which a concave groove is formed in the front face of the bumper reinforcement so as to reinforce the bumper reinforcement. With the concave groove being merely formed, however, the rigidities of the upper face and the lower face of the bumper reinforcement are inferior to that of the front face so that the upper face or the lower face of the bumper reinforcement is easily made to buckle by the impact applied on the front face. This buckling can be avoided by increasing the thickness of the upper face or the lower face. At the same time, however, there are lost the advantages of the light weight and the reduction of the material which are owned by the bumper reinforcement having the open section structure. Therefore, the inventors of the invention have investigated to develop the bumper reinforcement having the open section structure, which is enabled to exhibit the aforementioned high structural strength and shock absorbing performance more sufficiently by preventing the buckling of the upper face and the lower face of the bumper reinforcement.
SUMMARY OF THE INVENTION
First of all, with a view to preventing the upper face and the lower face of the bumper reinforcement from being opened, the present invention has developed a bumper reinforcement comprising an outer reinforcement and an inner reinforcement housed in the outer reinforcement. The outer reinforcement is made of a channel member of an open section having a front face, an upper face and a lower face, and the inner reinforcement is made of an angle member having a vertically pair of skirt plate portions folded from an intermediate portion. And, the intermediate portion of the inner reinforcement is joined to the front face of the outer reinforcement. The upper skirt plate portions of the inner reinforcement are joined at their end portions to the upper face of the outer reinforcement, and the lower skirt plate portions are joined at their end portions to the lower face of the outer reinforcement.
The following examples can be enumerated as the preferable sectional shapes of an inner reinforcement. At the individual skirt plate portions of the inner reinforcement, more specifically, there are formed the top portions which are protruded toward the front face of the outer reinforcement to divide the upper and lower skirt plate portions are further divided into the inner skirt plate portions and the outer skirt plate portions. Then, the intermediate portion of the inner reinforcement corresponds to the portion composed of the confronting end portions of the inner skirt plate portions, and the remaining end portions of the individual inner skirt plate portions protrude as the top portions formed with the end portions of the outer skirt plate portions, toward the front face of the outer reinforcement. The outer contact face portion of the inner reinforcement, that is the remaining end portion of the aforementioned outer skirt plate portion, is joined individually to the upper face and the lower face of the outer reinforcement thereby to follow the sectional shape of the inner reinforcement.
The outer reinforcement is usually formed from a single metal plate by a roll-forming method. Unlike the auxiliary reinforcement attached to the front face of the outer reinforcement, the inner reinforcement is mounted in an inside of the outer reinforcement formed by the front face, the upper face and the lower face. The inner reinforcement can be classified into a separate type, in which the inner reinforcement divided into a pair of the vertically symmetrical members is individually provided with the inside of the front face, and the upper/lower faces of the outer reinforcement, and a single formed type, in which the inner reinforcement is integrally formed to be provided continuously with the inside of the lower face, the front face, and the upper face of the outer reinforcement.
The inner reinforcement of either type has a common structure, in which the outer contact face portions are directly joined to the upper/lower faces of the outer reinforcement through the intermediate portion joined to the front face of the outer reinforcement. When an impact applied to the front face of the outer reinforcement, therefore, the end portions of the individual skirt plate portions forming the intermediate portion of the inner reinforcement joined to the front face of the outer reinforcement, and the end portions of the skirt plate portions of the inner reinforcement forming the outer contact face portions joined individually to the upper/lower faces of the outer reinforcement, are retracted relative to the intermediate portion of the skirt plate portion so that the skirt plates are folded around the center portions of the skirt plate portions. This folding structure inclines the entire skirt plate portions inwardly when an impact applied, so that the upper face and the lower face of the outer reinforcement can be prevented from being opened.
The intermediate portions of the individual skirt plate portions of the inner reinforcement are the top

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