JP4583214B2 - Automotive bumper structure - Google Patents

Description

  The present invention relates to a bumper structure for an automobile having a bumper reinforcement and a reinforcing member fixed to a front wall thereof.

  In the case of a light collision (16 km / h or less) of an automobile, it is required that the bumper structure substantially receives the collision energy. The performance of the bumper structure as an energy absorbing member is evaluated by the amount of deformation stroke and the maximum load when the collision energy is absorbed. The allowable stroke amount is the distance from the bumper face to the body structure that you do not want to break, and if the deformation stroke amount during a light collision is less than this allowable stroke amount, the deformation will be limited to the bumper structure. In addition, the vehicle body structure other than the bumper structure can be prevented from being damaged, and the safety of passengers can be improved.

If there is nothing between the bumper face and the front wall of the bumper reinforcement, the space from the bumper face to the front wall of the bumper reinforcement at the time of collision is the free running distance (stroke until the bumper structure begins to absorb the collision energy) Become. If this idling distance is large, the total deformation stroke at the time of collision increases. Therefore, conventionally, a foamed resin layer is generally installed between the bumper reinforcement and the bumper face (see Patent Document 1). As a result, the free running distance at the time of the collision is shortened, and a part of the impact energy is absorbed by the foamed resin layer, so that the total deformation stroke at the time of the collision is reduced.
On the other hand, Patent Documents 2 to 7 describe that a metal reinforcing member is installed on the front wall of the bumper reinforcement to reduce the free running distance at the time of collision and absorb collision energy. In Patent Documents 2 to 4, a reinforcing member is formed by stretching or drawing a metal plate. In Patent Documents 5 to 7, an aluminum alloy extruded material having a predetermined cross section is used as the reinforcing member.

JP 7-61298 A JP 2001-322517 A JP 2000-1150 A JP 2002-193054 A JP-A-6-286536 JP-A-2001-225663 Japanese Patent Laid-Open No. 2004-203066

The foamed resin can be easily molded into a three-dimensional shape along the inner surface of the bumper face by injection molding, and the free running distance from the bumper face to the foamed resin layer can be shortened. However, the rise of the load due to compression of the foamed resin layer at the time of collision is low and the amount of energy absorption is not large, so it cannot be said that it is effective in reducing the deformation stroke of the bumper structure.
In the case of a reinforcing member made of a metal plate, it is possible to obtain a three-dimensional shape along the inner surface of the bumper face by overhanging or drawing, but when drawing is performed, even if the plate is thick, about 2 mm. The plate thickness can only be about 1 mm, it is very easy to buckle at the time of collision, and is not very effective in reducing the deformation stroke of the bumper structure.

In the case of a reinforcing member made of an aluminum alloy extruded material, the thickness can be increased, and there is an advantage that a reinforcing member that is difficult to buckle can be formed. However, the conventional laterally crushed reinforcing member is three-dimensional along the inner surface of the bumper face. There is a problem that it is difficult to get the shape. This point will be described with reference to FIGS.
FIG. 5 shows a bumper stay 1 fixed to the ends of left and right side members (not shown), a bumper reinforcement 2 fixed to the bumper stay 1, a bumper face 3, and a central portion of the front wall of the bumper reinforcement 2. The bumper structure which consists of the fixed reinforcement member 4 is shown. The reinforcing member 4 is made of an aluminum alloy extruded material, and is arranged so that the extrusion direction is the vertical direction of the vehicle body. As shown in FIG. 5A, the front surface in the vehicle width direction is formed along the bumper face 3. However, as shown in FIG. 5B, in the vertical direction of the vehicle body, there is a portion that does not follow the three-dimensional shape of the bumper face 3 and the gap C1 is unevenly wide.
FIG. 6 shows a bumper structure including the same bumper stay 1, bumper reinforcement 2 and bumper face 3, and a reinforcing member 5 arranged so that the pushing direction is the vehicle width direction. Referring to FIG. 6B, the front surface of the reinforcing member 5 is formed along the bumper face 3 in the vertical direction of the vehicle body. However, as shown in FIG. 6A, in the vehicle width direction, there is a portion where the gap C2 is unevenly wide and does not follow the three-dimensional shape of the bumper face 3.

Even in such lateral crushing type reinforcing members 4 and 5 made of an aluminum alloy extruded material, the front side facing the inner surface of the bumper face 3 is cut or cut to form a three-dimensional shape of the bumper face 3. However, it is not impossible to reduce the free running distance, but there is a problem that the number of processes increases and the cost is increased, and the reinforcing effect is reduced by cutting the front side.
Further, the lateral crushing type reinforcing member has insufficient energy absorption efficiency (energy absorption amount divided by weight), and the deformation stroke amount of the bumper structure cannot be sufficiently reduced. On the other hand, if the thickness of the reinforcing member is increased to reduce the deformation stroke of the bumper structure, the weight of the bumper structure is increased.

  The present invention has been made in view of such a problem of the conventional bumper structure. In the bumper structure in which a metal reinforcing member is installed on the front wall of the bumper reinforcement, the reinforcement is made without increasing the weight. By increasing the energy absorption efficiency of the members and reducing the idling distance at the time of collision, the amount of deformation stroke at the time of collision of the bumper structure is reduced, damage to the body part of the vehicle body at the time of collision and improvement of passenger safety It aims to plan.

The present invention relates to a bumper reinforcement body of an automobile having a bumper reinforcement made of an aluminum alloy extruded material and a reinforcement member attached to a front wall of the bumper reinforcement, wherein the reinforcement member has a cylindrical shape, and an axial rear end is A flange attached to the front wall of the bumper reinforcement is integrally formed at the front end so as to expand in the outer circumferential direction, and the flange is disposed to face the inner surface of the bumper face. The reinforcing member is preferably made of an aluminum alloy extruded material.
The bumper structure is attached to the front side and / or rear side of the automobile. In the present invention, the collision surface side is the front and the opposite side is the rear.

  In this bumper structure, one or a plurality of the reinforcing members are attached at appropriate positions in the vehicle width direction such as the central portion or both end portions of the bumper reinforcement. In the case of bumper reinforcement made of an aluminum alloy extruded material, the cross section is generally a closed cross section, and the front wall thereof is arranged so as to face substantially perpendicular to the load direction in consideration of the load direction at the time of collision (generally, Therefore, it is desirable that the reinforcing member be attached with its axial direction being substantially perpendicular to the front wall. For example, when both ends of the bumper reinforcement are inclined or curved backward, if the reinforcing member is attached to both ends, the axial direction of the reinforcing member is outward when viewed from the front-rear direction of the automobile. However, it is also possible to attach the reinforcing member with the axial direction in the front-rear direction of the automobile even at the inclined or curved end portion.

According to the present invention, the reinforcing member is cylindrical, the rear end in the axial direction is attached to the front wall of the bumper reinforcement, and the flange formed at the front end is disposed to face the inner surface of the bumper face. The reinforcing member undergoes vertical crushing at the time of collision and deforms into a bellows shape, and exhibits higher energy absorption efficiency than the lateral crushing type reinforcing member. Accordingly, the amount of deformation stroke at the time of collision can be kept low without significantly increasing the weight of the bumper structure.
Further, it is easy to integrally form a flange that expands in the outer peripheral direction at the front end of the cylindrical reinforcing member by electromagnetic forming, press working, or the like. By forming the flange expanded in the outer peripheral direction, there is an advantage that the area subjected to the collision is expanded and a wider range can be covered with a lightweight reinforcing member having a small cross-sectional area of the shaft portion. Moreover, there is also an advantage that bellows-like deformation at the time of collision occurs stably by receiving an impact load with a flange that is expanded in the outer peripheral direction.
Furthermore, when forming a flange that expands in the outer circumferential direction at the front end of the cylindrical reinforcing member, it is easy to finish the flange into a three-dimensional shape along the inner surface of the bumper face, which can be implemented at low cost. Thereby, the idling distance at the time of a collision can be reduced and the deformation stroke amount of a bumper structure can be restrained low.
For these reasons, in the present invention, it is possible to prevent damage to the vehicle body portion at the time of a light collision and to improve the safety of the passenger.

Hereinafter, the bumper structure according to the present invention will be described with reference to FIGS.
The bumper structure shown in FIGS. 1 to 3 includes a bumper stay 11, a bumper reinforcement 12, a bumper face 13, and a reinforcing member 14.
The bumper stay 11 is a cylindrical member made of, for example, an aluminum alloy extruded material, and is fixed to the front ends of the left and right side members so that the axial direction (extrusion direction) is parallel to the longitudinal direction of the vehicle body. Reinforce 12 is fixed. The bumper reinforcement 12 is made of an aluminum alloy extruded material having a rectangular cross section, as shown in FIG. 5, the vehicle width direction central portion is parallel to the vehicle width direction, and both end portions are inclined rearward by bending, The front wall 12a is arranged in a vertical plane. The bumper face 13 is a plastic thin plate member having a three-dimensional shape similar to that shown in FIG.

The reinforcing member 14 is made of an aluminum alloy extruded material having a circular cross section, and a flat flange 14b expanded in the outer peripheral direction is formed at the rear end of the shaft portion 14a so as to be perpendicular to the axial direction (extrusion direction). A flange 14c that is expanded in the outer peripheral direction and has a three-dimensional curved surface is integrally formed at the front end. The flange 14b at the rear end is fixed to the front wall 12a by welding at both ends of the bumper reinforcement 12, so that the axial direction of the shaft portion 14a is perpendicular to the front wall 12a. The front end flange 14c opposes the bumper face 13 in close proximity, has a shape along the three-dimensional shape of the inner surface thereof, and the distance between the front surface of the flange 14 and the inner surface of the bumper face 13 is substantially equal over the entire surface. Yes.
Therefore, at the time of a collision from diagonally forward, wherever the collision partner enters the contour of the flange 14c, the impact member hits the reinforcement member 14 with a small free running distance, and the reinforcement member 14 is deformed into a bellows shape, so that all of the impact energy is obtained. Or absorb a part.

  In this example, the reinforcing members 14 are attached to both ends of the bumper reinforcement 12 in order to cope with a collision from obliquely forward. However, when dealing with a collision from the front, one or a plurality of reinforcement members 14 are provided in the central portion of the bumper reinforcement 12. A piece will be attached. Further, in this example, the reinforcing member 14 is mounted so that the axial direction of the reinforcing member 14 is perpendicular to the front wall of the bumper reinforcement 12 (outward when viewed from the front-rear direction of the automobile). Depending on the form, the axial direction of the reinforcing member can be attached parallel to the longitudinal direction of the automobile.

FIG. 4 schematically shows various forms of the flange formed at the front end of the reinforcing member.
4 (a) shows a cylinder with a widened flange formed at the front end of the cylinder, (b) shows a flared flange, and (c) shows a widened and inverted flange. These flanges (curling) are formed, and these correspond to the flanges expanded in the outer peripheral direction in the present invention. By forming such a flange that expands in the outer circumferential direction at the front end of the reinforcing member, the area that receives a collision is enlarged even with a cylindrical shape with a small cross-sectional area, and the deformation of the shaft portion at the time of the collision is stable It occurs as a result.
The reinforcing member is preferably an aluminum alloy extruded material, but an iron member such as a welded tube or an electric resistance welded tube can be used. Since the cross-sectional shape is easy to form a flange, a circular shape is desirable, but an elliptical or polygonal cross-section may be used.

As a means for forming a flange that is expanded in the outer peripheral direction at the end of the reinforcing member, it is desirable to use electromagnetic forming (see, for example, Japanese Patent Application Laid-Open Nos. 2004-42066 and 2004-189062). According to electromagnetic forming, the end of the cylindrical body is protruded from the end surface of the mold, and the protruding portion is expanded to form a flange along the shape (planar or curved surface) of the end surface. Even a flange can be easily formed. However, in the case of curling, it is necessary to invert the flange by press molding after molding the flange expanded by electromagnetic forming. Electromagnetic forming can be suitably used for an aluminum alloy extruded material.
In addition to electromagnetic forming, known press forming or the like can be used.

1 is a plan view of a bumper structure according to the present invention (a bumper face is partially cut away). FIG. It is the perspective view which looked at the bumper structure from the front lower side. It is a principal part enlarged plan view of the bumper structure (a bumper face is notched partially). It is sectional drawing which shows typically the form from which the reinforcement member which concerns on this invention differs. It is the top view (a) of the conventional bumper reinforcement material, and its AA sectional drawing (b). It is the top view (a) of the conventional bumper reinforcement material, and its BB sectional drawing (b).

Explanation of symbols

11 Bumper stay 12 Bumper reinforcement 13 Bumper face 14 Reinforcement member

Claims (3)

In a bumper structure of an automobile having a bumper reinforcement 12 made of an aluminum alloy extruded material and a reinforcing member 14 attached to a front wall 12a of the bumper reinforcement 12 , the reinforcing member 14 is made of a tubular aluminum alloy extruded material , the rear end of the axial direction is attached to the front wall 12a of the bumper reinforcement 12, the flange 14c that flares in the outer circumferential direction at the front end is formed integrally with the flange 14c is arranged to face the inner surface of the bumper face 13 A bumper structure for an automobile. The reinforcing member 14, the automobile bumper structure according to claim 1, characterized in that towards vertically axially against the front wall 12a of the bumper reinforcement 12. The bumper structure for an automobile according to claim 1 or 2, wherein both end portions of the bumper reinforcement 12 are inclined or curved rearward, and the reinforcing member 14 is attached to both end portions. .

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