JP2000062551A - Bumper structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage to a car body due to deformation occasioned by oblique collision of a bumper reinforcement material formed of an aluminum alloy extrusion hollow section and to protect a car body and a passenger through effective absorption of impact energy generated due to a frontal or oblique clash. SOLUTION: A bumper reinforcing material 4 is formed in a straight state, and clash boxes 50 and 51 axially regularly buckled and deformed to absorb impact energy are arranged at two ends and on two end sides and impact energy is effectively absorbed over against a frontal clash and an oblique clash. This constitution forms a bumper reinforcing material in a straight simple structure, effectively absorbs impact energy by the clash box 51 for an oblique clash against the oblique clash and prevents the damage to a car body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bumper installed at a front end portion and a rear end portion of a vehicle in order to absorb a shock applied to the vehicle body at the time of a collision to prevent the vehicle body from being damaged or to protect an occupant. .

[0002]

2. Description of the Related Art In vehicles such as automobiles, various mechanisms are applied to protect the vehicle body and occupants in case of collision or collision between other objects or vehicles while traveling. In recent years, with the development of motorization, the use of automobiles has become essential in daily life,
There is a strong demand for safety against these contacts and collisions, and on the other hand, in order to save energy and protect the environment, it is also necessary to devise ways to reduce the weight of the vehicle body structure. In order to meet the demand for improved safety against such a vehicle collision, the inventors of the present invention previously disclosed in Japanese Patent Laid-Open No. 8-310440 an extruded profile made of an aluminum alloy having a plurality of hollow portions, We have just proposed a frame material for automobiles that absorbs the impact at the time of collision by regular buckling in the direction.

This shock absorbing frame material is provided at the front and rear portions of the vehicle body frame to absorb the impact at the time of a collision, but the distribution of the impact energy absorption amount of each part of the vehicle body to the collision is to protect the occupant. This is an important requirement for vehicle safety design, and the structures in front of and behind the passenger compartment absorb these energy to the maximum extent to minimize damage to the passenger compartment and reduce the impact on the entire passenger compartment. It is necessary to reduce the shock to passengers. For example, as described in the above-mentioned publication, in the measurement results of the type of vehicle in which the engine room is arranged in front of the vehicle compartment, which is performed by the inventors, at least 70% of the collision energy is the exterior of the fender, bonnet, or the like. Parts and bumpers, engines,
It was absorbed by structural members other than the body frame such as wheels.

Of these, the bumper is important in terms of its original function of protecting the vehicle body or reducing its damage. As shown in FIG. 1, the bumper 1 is installed at the front and rear ends of the vehicle body and It also functions to protect the vehicle body from contact and collision from diagonal directions. As shown in FIG. 2, its structure generally comprises a bumper skin 2, an energy absorbing foam 3, and a bumper reinforcement body 4, and is designed to absorb a shock such as a collision against a vehicle body frame 5 through these shock absorbing structures. There is. The bumper reinforcement is made of extruded aluminum alloy with a hollow cross section, such as mouth, day, eye, or square, and is bent according to the shape of the front and rear of the car body, and then drilled for mounting on the car body. , It is fixed to the car body with mounting bolts. These aluminum alloy profiles can meet the recent demands for environmental protection such as energy saving and carbon dioxide emission reduction because they can reduce the weight of the vehicle body structure, and aluminum alloys include hollow parts as extruded profiles. Since it is possible to easily form a free cross-sectional shape, it is expected that the cross-sectional shapes have rigidity and the impact energy at the time of collision is absorbed by the deformation of the cross-sectional shape to improve safety.

However, in such a bumper structure, the impact due to the collision is transmitted to the bumper reinforcing member through the energy absorbing foam, and the load is concentrated between the bumper reinforcing member and the vehicle body frame. Buckling of the cross-sectional shape is likely to occur at points, and the bumper reinforcement easily intrudes into the vehicle body side and damages the vehicle body behind the bumper, and the impact energy absorption is small, so the vehicle body protection function is sufficient. Can not be demonstrated to. Furthermore, as shown in FIG. 3, for a collision from an oblique front,
Since the cantilever structure has no support points outside the mounting position of the body frame, the bumper tip side, which is a free end even when the contact is mild, is easily bent inward and bent. It becomes a state and it bites into the car body side, and it is difficult to achieve the protective effect. The front and rear side parts of the vehicle body are liable to come into contact with structures in addition to collision accidents, resulting in damage to expensive parts such as lamps concentrated in these parts.

FIG. 4 shows a damaged state of the bumper reinforcing member which has received such a collision. The bumper reinforcing member 4 made of an aluminum alloy hollow extruded shape buckles at the mounting portion of the vehicle body frame where the load is concentrated as described above, is crushed as seen in the wrinkle B, and is further bent to the end portion side. There is.
As a result, the strength against impact and load cannot be sufficiently maintained, and the section where the bending load is concentrated causes buckling and easily crushes the cross section, so that the effect of absorbing impact energy cannot be sufficiently exerted. Becomes Although contact in a diagonal direction or slight impact is likely to occur frequently, as described above, since the bumper reinforcing member has a cantilever structure on both end sides, the vehicle body side is damaged each time.

Further, since the bumper reinforcement is a member that is bent at both ends along the shape of the front and rear ends of the vehicle body, the processing cost is high, and such a bumper reinforcement is damaged at the time of repair. Since the entire reinforcing material must be replaced, maintenance costs will increase. On the other hand, measures such as increasing the strength of the bumper reinforcing material or providing a reinforcing member at the points where these loads are concentrated can be considered, but increasing the overall strength directly increases the weight because the load is large. As a result, there was no room in the partial reinforcing structure, and the structure was complicated, so it was difficult to adopt.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and is directed to the manufacturing cost of a bumper reinforcing member made of an aluminum alloy extruded hollow shape member and the light damage to these. Reduce maintenance costs,
Sufficient strength is provided to the bumper from front and diagonal fronts, and a large impact energy absorption effect is exerted, and bending deformation is prevented especially against contact and collision from diagonal front and the body and passengers are protected. It is an object to provide a simple and lightweight structure that effectively protects.

[0009]

SUMMARY OF THE INVENTION In order to achieve the object, the present invention has a bumper structure in which a bumper and a vehicle body frame are connected diagonally to the side of a bumper reinforcement made of a straight aluminum alloy extruded shape. It is a car bumper equipped with a crash box for collision,
A straight bumper reinforcement made of extruded aluminum alloy is provided inside and on the side thereof with a crash box that is combined with a vehicle body frame to absorb collision energy. Furthermore, the crash box is made of an aluminum alloy. It is connected to the vehicle body frame via a bracket made of wrought material or cast aluminum alloy. Further, the energy absorbed by the crash box at the time of collision is calculated by the following equations (1) and (2) to facilitate the design work. In the case of an energy absorption profile having a rectangular hollow section: U _S = {4.72 × (B + H) ^0.30 × t ^1.81 × E ^0.15 × ((σ _B + σ _0.2 ) / 2) / 1000} × m × n × L ( KN · mm) (1) In the case of an energy absorption profile having a circular hollow cross section: U _c = {4.19 × D ^0.45 × t ^1.7 × E ^0.15 × ((σ _B + σ _0.2 ) / 2) / 1 000} × n × L (KN · mm) (2) where, U _S : Absorbed energy amount of rectangular hollow cross section (KN · m
m) U _c : Absorbed energy amount of circular hollow section (KN · m
m) D: outer diameter (mm) B: Length of the long sides (mm) H: the length of the short side (mm) E: Young's modulus (GP _a) σ _B: tensile strength of the material (MPa) σ _0.2 : 0.2% proof stress of the material (MP _a) m: number of the hollow portion of the polygonal or circular cross-section n: number of energy absorbing profile L: vehicle body design deformable region (mm)

[0010]

The present inventors have found that the crushing due to the buckling of the bumper reinforcing material occurs at a location where a load or a shock is concentrated, and also serves as a location where a shock energy is concentrated. The impact energy absorption characteristics of the hollow structure of the impact absorbing frame that is regularly buckled and deformed, and the fact that the structure is compact and the cross-sectional structure can be easily formed as an extruded aluminum alloy profile, By substituting the shock absorbing function on both ends of the bumper reinforcement with a member having a deformable hollow structure, the problem of the cantilever structure of the bumper reinforcement can be solved and the structure can be simplified, and the hollow structure By arranging these members by using, the bumper reinforcement is given great strength and the excellent impact energy absorption characteristics are effectively provided. It is those that have completed the present invention as those that can be volatilized.

According to the first aspect of the present invention, the bumper reinforcing member is made of a straight aluminum alloy extruded shape with both ends omitted, and the bumper is directly supported by the crash box to eliminate the cantilever structure. The impact energy absorption capacity of the crash box effectively absorbs impact from an oblique direction. With this structure, the bumper reinforcement has a simple shape of extruded shape, does not require bending work, and does not require expensive bumper reinforcement even in the case of relatively frequent contact or collision from an oblique direction. Does not require replacement. Moreover, since the crash box has a compact structure as described above, by arranging it in the hollow portion of the straight bumper reinforcement at the same time, the cross section from the inside of the hollow portion to the buckling etc. even in the case of a collision from the front side. It is possible to prevent deformation and effectively exert the strength of the hollow structure, and it is possible to mitigate the impact applied to the vehicle body due to the large energy absorption capability when the device itself regularly buckles and is crushed.

Further, the bumper reinforcing material in which the crash box is arranged in the hollow portion, the crash box provided for oblique collision, and the vehicle body frame are connected by an aluminum alloy wrought material or a bracket made of an aluminum alloy casting to reduce the weight. can do. If conditions such as the allowable deformation range for the design of the bumper reinforcement are determined, (1),
By introducing the data specifications of the energy absorption profile into the equation (2), the shape, size, etc. of the crush box for the required energy absorption amount can be easily obtained, which is troublesome and costly. Predetermined design work can be carried out before the bulky destructive test.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the bumper reinforcing material of the present invention will be described below with reference to the drawings. In FIG. 5, the reinforcing member 4 of the bumper 1 is connected to the vehicle body frame 5 via the bracket 6 with the crash box 50 disposed inside the hollow portion. Further, as shown in FIG. 6, the bumper reinforcing member 4 is made of a straight extruded shape member that is not bent, and the crash boxes 50 are arranged in both ends thereof.
Brackets 6 on both ends of the bumper in the diagonal collision direction
Crash box 5 connected to the body frame by
Place 1 to support the bumper directly.

FIGS. 7 (a) and 7 (b) show the structure of the crash box 50 for front collision arranged at the end of the bumper reinforcing member 4 and the manner of mounting the crash box 51 for oblique collision on the bracket 6 in case of oblique collision. . As shown in the figure, the crush box has a hollow cross-section structure made of extruded aluminum alloy, and is formed by cutting the profile according to the height of the hollow portion of the bumper reinforcement or the distance between the bumper and the bracket. The mechanism for crashing and absorbing energy at the time of impact is the same as that of the impact energy absorbing vehicle body frame material previously proposed by the present inventors, and its axial direction is arranged parallel to the impact direction. By
When a load over a certain level is applied, the side walls and bulkheads alternately project outward or fold inwardly between adjacent walls, so to speak, they are repeatedly crushed by repeating regular buckling in the axial direction like an accordion. , This deformation absorbs large impact energy.

FIG. 8 shows the deformed state of the bumper and the crash box in the case of an oblique collision. The crush box 51 for oblique collision receives a shock in a substantially vertical direction with respect to the impacted object 10 in an oblique direction and is regularly buckled to be crushed.
Although the crash box 50 for front collision is impacted and is slightly deformed together with the bumper reinforcing material, it has not been significantly deformed and the bumper does not enter the vehicle body side.

Further, FIGS. 9A and 9B show two examples in the case of a frontal collision. In the case of (a), since the collided body 10 is relatively small, the central portion of the bumper reinforcement member 4 is deformed, but the bumper reinforcement member is not a cantilever structure but is supported at both ends. Is sufficiently exerted, and the collision energy is dispersed and absorbed by the bumper reinforcing material, the support portions at both ends thereof, and the crash box 50, so that the crash box for frontal collision does not collapse, and it is a relatively small scale. It has sufficient strength against a collision.
(B) shows the case where a relatively large impact is received by the barrier-like collided body 10 over the entire surface. The front crash box 50 is almost completely crushed due to regular buckling, and a large impact energy is absorbed during that time to prevent damage to the body frame and other members.

FIG. 10 shows a state in which the crash boxes 50, 51 are deformed and crushed by regular buckling. As described above, the crush box of the present invention does not buckle in the axial direction for a moment even when subjected to a large load or impact, and is crushed sequentially in the hollow axial direction while maintaining a constant load load, so that the crush box is large in impact. To absorb the impact energy to protect the vehicle body and passengers, reduce the cost by using a bumper reinforcement as a simple structure, and effectively protect the vehicle body and passengers from contact or collision from an oblique direction. You can

The distribution of the impact energy absorption amount of each part of the vehicle body with respect to a collision is an important requirement in the vehicle safety design as described above. Therefore, various attempts have been made to integrate the impact energy absorption amount of each part of the vehicle body. It is being done. For example, J
FMVSS-204 adopted by IS D1060
The energy calculated from this and the total weight of the vehicle is calculated on the basis of 50 km / hour that complies with the (US automobile safety standard), and the distribution that can be absorbed by the structure of each part of the vehicle body is calculated. Structures other than the body frame cannot be unconditionally calculated because they are determined by various factors other than strength.
For this reason, it is measured by a destructive test using an actual vehicle model, but it is time-consuming, costly, and difficult to carry out.For a shock absorbing member such as a bumper reinforcement, a destructive test is actually required. Practically desired is a method for easily calculating the amount of impact energy absorption without performing it.

The present inventors have previously proposed a method for calculating the amount of impact energy absorbed due to the continuous buckling of a structural member having a hollow structure in the direction of the hollow axis thereof (Japanese Patent Laid-Open No. 8-
However, since the impact energy absorption mechanism by the continuous buckling deformation of the crash box of the present invention is common to the above, it can be easily calculated by the calculation method proposed above.

That is, according to the above method, in the case of a crush box having a rectangular hollow section: U _S = {4.72 × (B + H) ^0.30 × t ^1.81 × E ^0.15 × ((σ _B + σ _0.2 ) / 2 ) / 1000} × m × n × L (KN · mm) (1) where, U _S : Absorbed energy amount of square hollow section (KN · m)
m) B: Length of the long sides (mm) H: the length of the short side (mm) E: Young's modulus (GP _a) σ _B: tensile strength of the material (MPa) σ _{0.2: 0.2%} of the material strength (MP _a) m: polygonal or the number of the hollow portion of circular cross-section n: number of crush boxes L: vehicle body design deformable region (mm)

Further, in the case of a crush box having a circular hollow cross section, a preliminary deformation portion or a softening region for regularly inducing buckling deformation is formed in the direction of 120 degrees to
Folded inward at regular intervals of 20 degrees, replacing B (width in cross section of each hollow part) and H (height in cross section of each hollow part) with outer diameter D, m
When the coefficient is obtained from the experimental value with (the number of hollow portions) = 1, the absorbed energy amount of the circular hollow section (KN · mm)
U _c is obtained by the following equation. U _c = {4.19 × D ^0.45 × t ^1.7 × E ^0.15 × ((σ _B + σ _0.2 ) / 2) / 1000} × n × L (KN · mm) (2)

Further, as described above, it is necessary for the energy absorbing profile to increase the impact energy absorption amount at the time of a collision and to reduce the impact applied to the entire passenger compartment to reduce the shock to the passengers. In the energy-absorbing profile of the present invention, a regular buckling is induced by forming a constant deformed portion or a softened portion whose strength is reduced by a weld bead or the like in advance at the buckling deformation start position. Thus, the buckling deformation can be continuously progressed, whereby the energy absorption amount can be increased and the impact transmitted to the vehicle interior side at the time of starting the buckling deformation can be mitigated.

That is, the buckling deformation of the energy absorbing profile of the present invention, in the case of adjacent sides or cylinders, alternately bulges and folds inward and outward at a constant circumferential interval and is folded in an accordion shape. By regularly buckling into a curved shape, the number of times of buckling is increased to increase the amount of energy absorbed, and when a load above a certain level is reached, buckling deformation is promptly induced to reduce the impact on the vehicle interior. can do. For this reason, such regular buckling can be induced by forming convex portions or concave portions along the respective sides or at regular intervals on the circumference in the deformation direction at the buckling start position. it can. Further, by forming the weld bead, it is possible to similarly induce a fold-in to the inside or a bulge-out deformation to the outside.

[0024]

As described above, according to the present invention, the problem of the cantilever structure of the bumper reinforcing member made of the extruded aluminum alloy profile to be incorporated in the bumper of the vehicle is solved and the bumper due to the oblique collision is solved. In addition to preventing the reinforcement material from entering the vehicle body side, its structure is straight and simple to facilitate manufacturing and maintenance, and the vehicle body is effectively and effectively protected against collision from the front and diagonal directions. It is also possible to protect passengers and ensure their safety.

[Brief description of drawings]

FIG. 1 is a schematic front view of a vehicle having a bumper.

FIG. 2 is a sectional view of the same.

FIG. 3 is a diagram showing a relationship between a bumper and an oblique collision.

FIG. 4 is a diagram showing a bumper reinforcement member crushed by a collision.

FIG. 5 is a bumper in which the crash box of the present invention is arranged.

FIG. 6 shows an example in which crash boxes are arranged at both ends of the bumper reinforcement and on the sides thereof.

FIG. 7 is a view showing a mounting mode of the crash box: a state (a) arranged inside a hollow portion of a bumper reinforcing member, and a state (b) mounted on a bracket in preparation for an oblique collision.

FIG. 8 shows a state where the crash box is deformed due to an oblique collision.

FIG. 9 shows a state in which the bumper is deformed due to a collision from the front surface: an example in which the bumper is deformed due to a relatively small impact (a), and an example in which the bumper is deformed due to a relatively large impact (b).

FIG. 10 shows a state in which the crash box of the present invention is regularly buckled and deformed by impact.

[Explanation of reference numerals] 1: Bumper 2: Bumper skin 3: Energy absorbing foam 4: Bumper reinforcement 5: Body frame 6: Bracket 10: Collision object 50: Crash box (for frontal collision) 51: Crash box (oblique collision) 52, 62: Screw holes for mounting the crash box 60: Crash box mounting portion for front collision 6
1: Crash box mounting part for oblique collision 63: Screw hole for fixing bumper reinforcement B: Wrinkle caused by buckling

Continued front page    (72) Inventor Kaoru Ishido             1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture             Nippon Light Metal Co., Ltd. Group Technology Center             Within (72) Inventor Takashi Sasamoto             1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture             Nippon Light Metal Co., Ltd. Group Technology Center             Within

Claims (4)

[Claims] 1. A bumper structure for a vehicle, comprising a straight bumper reinforcement made of extruded aluminum alloy and laterally provided with a crash box for connecting the bumper and the vehicle body frame to prevent an oblique collision. 2. A bumper structure comprising a straight bumper reinforcement made of an extruded aluminum alloy and a crash box for absorbing impact energy, which is connected to a vehicle body frame inside and at the side thereof. 3. The automobile bumper according to claim 1, wherein the crash box is connected to a vehicle body frame through a bracket made of an aluminum alloy wrought material or an aluminum alloy casting. 4. The vehicle body bumper according to claim 1, wherein the energy absorbed by the crash box at the time of collision is calculated by the following formula. In the case of an energy absorption profile having a rectangular hollow section: U _S = {4.72 × (B + H) ^0.30 × t ^1.81 × E ^0.15 × ((σ _B + σ _0.2 ) / 2) / 1000} × m × n × L ( KN · mm) (1) In the case of an energy absorption profile having a circular hollow cross section: U _c = {4.19 × D ^0.45 × t ^1.7 × E ^0.15 × ((σ _B + σ _0.2 ) / 2) / 1 000} × n × L (KN · mm) (2) where, U _S : Absorbed energy amount of rectangular hollow cross section (KN · m
m) U _c : Absorbed energy amount of circular hollow section (KN · m
m) D: outer diameter (mm) B: Length of the long sides (mm) H: the length of the short side (mm) E: Young's modulus (GP _a) σ _B: tensile strength of the material (MPa) σ _0.2 : 0.2% proof stress of the material (MP _a) m: number of the hollow portion of the polygonal or circular cross-section n: number of energy absorbing profile L: vehicle body design deformable region (mm)