JP2000053020A - Automobile body structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automobile body structure capable of realizing a deformation mode compatible of compacting the body dimensions and reducing crew deceleration to a still more high level. SOLUTION: A reaction producing member 1 receiving compression load parallel with the deceleration actuating direction at the time of collision is to include a part 4 contracting the longitudinal dimension by bending deformation and a bending deformation checking means 6 for checking the generation of bending deformation and the bending deformation starting point of the part 4 is set by strength setting of the bending deformation checking means 6. Thus a body deceleration pattern of compression deformation higher in the initial stage of collision than after the middle stage of collision can be realized because the lead in the initial stage of collision is received with compression deformation of relatively high stress, the load after the middle stags of collision is received with bending deformation of relatively law stress, and the bend starting load can be regulated by the bending deformation checking means 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body structure, and more particularly to a vehicle body structure capable of reducing a deceleration acting on an occupant in a collision.

[0002]

2. Description of the Related Art In recent years, in order to enhance the occupant protection effect at the time of a collision, a deformation mode at the time of collision of a portion other than the living space of the vehicle body is appropriately set to reduce the deceleration of the living space portion of the vehicle body. Various body structures have been proposed in which deformation is prevented from reaching the living space (Japanese Patent Laid-Open No. 7-101354).
No., etc.).

[0003] On the other hand, the deceleration of the occupant connected to the seat via the seatbelt rises only when a forward inertial force acting on the occupant during a vehicle collision is received by the seatbelt. Here, since the spring action of the seat belt cannot be completely eliminated, the occupant moves forward due to inertial force, and the occupant deceleration reaches a peak when the seat belt elongation reaches a maximum, It is said that the peak value of the occupant deceleration increases as the amount of movement of the occupant due to inertial force increases, and is generally higher than the average deceleration of the vehicle body. Therefore, in order to reduce damage to the occupant during a collision, it is necessary to adjust the vehicle body deceleration so that the time delay of the rise of the occupant deceleration with respect to the vehicle body deceleration is as small as possible.

[0004]

Therefore, the inventors of the present application performed a simulation and found that when the vehicle body deformation stroke for absorbing the collision impact was the same, the vehicle body deceleration was increased from the middle of the initial stage of the collision. It was confirmed that the lower the vehicle speed, the lower the peak value of the occupant deceleration than the case where the deceleration from the beginning of the collision is kept constant or gradually increased.

The present invention has been devised based on such knowledge, and an object of the present invention is to provide a deformation mode capable of achieving both higher compactness and a reduction in the occupant deceleration. An object of the present invention is to provide a feasible vehicle body structure.

[0006]

In order to achieve the above object, in the present invention, a reaction force generating member (side member 1 in the embodiment) which receives a compressive load along a direction of action of deceleration at the time of a collision. Has a portion (bending portion 4 in the embodiment) for reducing its longitudinal dimension by bending deformation, and a bending deformation preventing means (vertical member 6 in the embodiment) for preventing occurrence of bending deformation. The starting point of the bending deformation of the portion is set by setting the strength of the bending deformation preventing means. According to this, the load at the initial stage of the collision is received by the compressive deformation with relatively high stress, the load after the middle stage of the collision is received by the bending deformation with relatively low stress, and the bending start load is defined by the bending deformation preventing means. Therefore, it is possible to realize a vehicle body deceleration pattern in which the initial stage of the collision is higher than that after the middle stage of the collision.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 schematically shows a side member of an automobile to which the present invention is applied. This side member 1
For example, it is formed by combining extruded materials of an aluminum alloy, and is formed from both sides of the engine room 2 to the vehicle floor 3.
Extends downward in the front-rear direction of the vehicle.

Engine room 2 in side member 1
Are formed as bent portions 4 having a shallow angle bending shape in advance so that the intermediate portion bends downward when a rearward horizontal load is applied. Thereby, when the vehicle has a head-on collision, the bending portion 4 bends and deforms while generating a certain reaction force due to the compressive load at that time, thereby contracting its front-rear dimension and suppressing the deceleration of the living space portion to a certain range. I do.

The center of the bent portion 4 of the side member 1 is provided with a cantilever 5 having a sufficiently higher bending strength than the bent portion 4.
Is connected via a vertical member 6 which receives a load in the extension direction. Thus, the bending portion 4 is configured such that the bending deformation start stress is sufficiently higher than the plastic deformation stress.

Next, the above-described deformation process of the side member 1 will be described with reference to FIGS. 2 and 3 assuming a case where a vehicle collides head-on with a road structure.

In the initial stage of the collision, a rearward load is applied to the bumper beam 7 fixed to the front end of the side member 1 due to the inertial weight of the vehicle body. Thereby, elastic region stress in the bending direction is generated in the bending portion 4 together with the compressive stress,
As a result, elastic region stress in the tensile direction is generated in the vertical member 6, and the vehicle body deceleration rises sharply (region a in FIG. 3).

After passing through a plastic region (region b in FIG. 3) where the tensile stress of the vertical member 6 is substantially constant, the breaking load (c in FIG. 3)
When the point () is reached, the vertical member 6 is broken, and the bending deformation preventing force exerted on the bent portion 4 by the vertical member 6 disappears. Then, the compressive stress generated in the bent portion 4 immediately reaches the yield point and the bent portion 4 starts bending deformation.
Of the vehicle body rapidly decreases, and the vehicle deceleration rapidly decreases accordingly (region d in FIG. 3). If the elongation of the seat belt reaches a peak in the region where the vehicle body deceleration decreases, the occupant deceleration can be significantly reduced. Thereafter, since the bending deformation of the bent portion 4 proceeds while generating a substantially constant reaction force (plastic region stress) (see FIG. 2), a certain constant deceleration is maintained in the middle stage of the collision over the entire stroke (see FIG. 2). 3A).

The peak value of the deceleration in the initial stage of the collision is determined by the breaking load of the vertical member 6, and the constant deceleration value in the middle of the collision is determined by the stress in the plastic region of the bent portion 4.

At the end of the collision, the reaction force generated by the bottom of the deformation of the engine room 2 is added, so that the vehicle deceleration increases. However, in this region, the occupant's inertial force is almost completely eliminated. Therefore, since the deceleration difference between the vehicle body and the occupant is small, the influence on the occupant deceleration is very small.

In the above embodiment, as the bending deformation preventing means for setting the bending deformation starting load of the bending portion 4, the vertical member 6 which is broken by a predetermined tensile load is used. This is shown in FIG. The mechanical connection between the vertical member 46 and the bent portion 44 is released by the actuator 8 which operates according to the output of the deceleration sensor (not shown), or as shown in FIG. The vertical member 56 may be forcibly broken using the explosive 9 ignited in accordance with the output of the notch (not shown), so that the bent portions 44 and 54 may be deformed like an avalanche.

Further, as shown in FIG. 6, a pair of longitudinal members 10 having the same initial bending shape are arranged symmetrically in the vertical direction to form a bent portion 64. A pantograph shape in which the center is connected by a vertical member 66 can also be used.

[0018]

As described above, according to the present invention, the collision impact is absorbed by the buckling deformation in which the difference between the yield point stress and the plastic deformation stress is relatively large, and the average deceleration is set by the bending stress. Since the peak value of the deceleration is set by setting the starting point of the bending deformation by the strength of the deformation preventing means, the deceleration pattern of the living space portion of the vehicle body is high in the early stage of the collision and low in the middle stage and thereafter. And it can be set so as to be substantially constant. As a result, the peak value of the occupant deceleration can be reduced with a small deformation stroke compared to the conventional structure, and if the same deformation stroke as the conventional one is obtained, the occupant deceleration peak value can be significantly reduced. obtain. Moreover, since the amount of movement of the occupant with respect to the vehicle body in the room can be suppressed to a small value, the possibility of a secondary collision in which the occupant hits a structure in the room and is injured can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a vehicle body to which the present invention is applied.

FIG. 2 is an explanatory view showing a deformation process of a side member at the time of a collision.

FIG. 3 is a deceleration waveform diagram at the time of a collision.

FIG. 4 is a partial perspective view of the second embodiment.

FIG. 5 is a partial perspective view of a third embodiment.

FIG. 6 is a partial perspective view of a fourth embodiment.

[Explanation of symbols]

 Reference Signs List 1 side member (reaction force generating member) 4 bent part (part) 6 vertical member (bending deformation preventing means)

Claims (1)

[Claims] 1. A vehicle body structure comprising a reaction force generating member which receives a compressive load along a direction of action of deceleration at the time of a collision, wherein the reaction force generating member has a portion whose longitudinal dimension shrinks by bending deformation. And a bending deformation preventing means for preventing the occurrence of the bending deformation, wherein a bending deformation starting point of the portion is set by setting the strength of the bending deformation preventing means.