JP3370295B2 - Car body structure - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, in order to enhance the effect of protecting passengers at the time of a collision, a deformation mode at the time of a collision 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 vehicle body structures have been proposed so that the living space is not deformed (Japanese Patent Laid-Open No. 101351/1995).
(See the bulletin, etc.)

On the other hand, the deceleration of the occupant connected to the seat via the seat belt rises only when the forward inertial force acting on the occupant during a vehicle collision is received by the seat belt. Since the spring action of the seat belt cannot be completely eliminated here, the occupant moves forward due to inertial force, and the occupant deceleration reaches its peak when the seat belt reaches the maximum extension, 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 generally becomes higher than the average deceleration of the vehicle body. Therefore, in order to reduce the impact on 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, when the inventors of the present application performed a simulation, when the vehicle body deformation strokes for absorbing the impact of the collision were made the same, the deceleration was increased sharply immediately after the collision. It is better to decrease it rapidly after raising it so that it converges to a constant value, rather than to make the deceleration constant from the beginning of the collision constant, or to make it gradually higher. It was confirmed that the value could be lowered.

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

[0006]

In order to achieve such an object, according to the present invention, a reaction force generating member (side member 1 in the embodiment) that receives a compressive load along the direction of action of deceleration at the time of collision. Is a first portion (a crushing portion 8 in the embodiment) that makes a small stroke by compression deformation, and a bending portion that starts bending deformation at a value higher than the deformation start load of the first portion.
(6, 11) have a, and the average continuous and a second portion to increase stroke while generating a lower average reaction force loads than the reaction force load (bending portion 6, 11 in the embodiment) of the first portion It is supposed to be provided. According to this, the reaction force generation pattern can be adjusted by sequentially shifting the deformation mode of the reaction force generation member from compression to bending, and the reaction force generation pattern sharply rises in the initial stage of the collision and then rapidly decreases. A constant vehicle deceleration can be realized. In particular, if the stress concentrating portion 9 for making the deformation start load close to the average reaction force load is provided in the first portion, the deformation start load becomes low, and a substantially constant reaction force load is generated over the entire stroke. You can In addition, the second part is bent downward
It should be easy to deform.

[0007]

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

FIG. 1 shows an outline of a side member of an automobile to which the present invention is applied. This side member 1 is
For example, it is made of extruded aluminum alloy,
It extends in the front-rear direction of the vehicle from both sides of the engine room 2 to the lower part of the passenger compartment floor 3. The side member 1 and the other members are not limited to the extruded material of the aluminum alloy, and may be formed of other materials and other processing methods.

First, a first embodiment according to the present invention will be shown. As shown in FIG. 2 and FIG. 3, the vehicle front end portion of the side member 1 is a hollow rod-shaped member whose cross-sectional shape is a letter-like shape.
An initial shape in which a horizontal rib 4 provided at an intermediate position in the vertical direction is cut in half from a plate thickness center to form a slit 5 having an appropriate length in the front-rear direction, and an intermediate portion in the front-rear direction of the slit 5 is slightly opened. And a comparatively short crushed portion 8 connected to the tip of the bent portion 6 via a thrust plate 7.

The crushed portion 8 is provided with a bead, a notch, or a similar stress concentration portion 9 in order to reduce the starting load of compressive deformation (yield point stress) to near the average reaction force load (plastic deformation stress). It is provided. A bumper beam 10 extending in the vehicle width direction is joined to the front end of the crushed portion 8.

The average reaction force load generated during plastic deformation of the crushed portion 8 is set to be slightly lower than the load at which the bending portion 6 of the side member 1 receives a compressive load and starts bending deformation, and the bending portion 6 has a bending force. The average reaction force load generated after the start of deformation is set sufficiently lower than the average reaction force load of the crushed portion 8.

The bent portion 6 is not limited to the bifurcated beam configuration in which two beams are arranged symmetrically in the vertical direction as in the present embodiment. For example, a single beam which does not functionally change is provided. However, in order to stabilize the mode of bending deformation due to a horizontal load from the front, it is preferable to use two. Further, depending on the overall configuration of the vehicle, the vehicle may be bent and deformed on a horizontal plane.

Next, the deformation process of the side member 1 will be described with reference to FIGS. 4 and 5 on the assumption that the vehicle collides head-on with the road structure.

At the initial stage of the collision, the backward reaction force load due to the inertial weight of the vehicle body causes the crushed portion 8 at the front end of the side member 1.
Act on. As a result, first, elastic region stress is generated in the crushed portion 8, and the deceleration sharply rises until the deformation start load (yield point stress) is reached (region a in FIG. 5). Here, the crushed portion 8 has a stress concentration portion 9 for reducing the deformation start load.
Is provided, and a compressive deformation occurs while generating a substantially constant reaction force load (plastic region stress) over the entire stroke (Fig. 4-
A), a certain deceleration is maintained (Fig. 5).
Area b). During this time, the bending portion 6 receives the same load, but since the average reaction force load of the crushing portion 8 is set lower than the deformation start load of the bending portion 6, the bending portion 6 continues to be deformed. Does not deform.

When the deformation stroke of the crushing portion 8 bottoms out in the middle of the collision, the reaction force load increases until it reaches the yield point of the bending portion 6 due to work hardening, so the deceleration also momentarily increases (point c in FIG. 5). ). Then, when the bent portion 6 starts bending deformation (see FIG. 4-B), the reaction force load rapidly decreases to the bending stress in the plastic region of the bent portion 6, and the deceleration also decreases rapidly (d in FIG. 5). Area). If the elongation of the seat belt reaches a peak in the region where the vehicle body deceleration rapidly decreases, the occupant deceleration can be significantly reduced. Then, while the bending angle of the bent portion 6 increases, the deformation of the side member 1 progresses (see FIG. 4-C), and during this period, a substantially constant reaction force load is continuously generated, that is, the deceleration also becomes constant (see FIG. E). region).

The ratio of the deformation start load of the bent portion 6 to the average reaction force load can be set to an appropriate value by setting the initial shape.

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 deceleration of the vehicle body increases. However, since the deceleration difference between the vehicle body and the occupant is small, the influence on the occupant deceleration is minimal.

Next, a second embodiment according to the present invention will be described below with reference to FIGS. 6 and 7. The same parts as those in the illustrated example are designated by the same reference numerals, and detailed description thereof will be omitted.

In this second embodiment, as shown in FIG. 6, the bent portion 11 forming the second portion extending in the engine room of the side member 1 has no slit 1 It is formed as a book beam. Therefore, the cross-sectional shape of the main bent portion 11 is in the shape of a cross as shown in FIG. 7, and the horizontal rib 4 thereof is not divided.

In the frame structure of the present embodiment, the side member 1 is provided between the engine room and the vehicle compartment.
From the vertical member 12, an upper horizontal member 13 extending shortly from the upper end of the vertical member 12 toward the front of the vehicle, and an extending end of the upper horizontal member 13 and a bend. An upper member 14 is provided so as to extend obliquely between the upper surface of the front end of the portion 11 and the upper surface. The joining of the members may be welding.

By doing so, the bent portion 1 is formed.
1 and the upper member 14 can produce the same effect as that of the bifurcated beam 6 in the first embodiment. By making the plate thickness of the side member 1 relatively thick, the deformation start load of the bent portion 11 can be increased, and the crushed portion 8 can be deformed before the bent portion 11.

Next, the deformation process of the side member 1 according to the second embodiment will be described with reference to FIG. 8 corresponding to FIG. 4 and FIG. 9 corresponding to FIG. The areas a, b, c, d, and e in FIG. 8 correspond to those in FIG. 5, respectively.

In the regions a and b shown in FIG. 8, the vehicle body deceleration change similar to that in the regions a and b of FIG. 5 is shown by the deformation of the crushing portion 8 shown in FIG. The work hardening of 8 causes the deceleration to increase for a moment. Next, as shown in FIG. 10, the bending deformation of the bending portion 11 starts with the end of the crushing of the crushing portion 8, and as shown in the area d of FIG. To do. In the second embodiment, by providing the upper member 14, the vehicle front side of the side member 1 is easily bent and deformed downward as shown in FIG. When the engine is mounted on the bent portion 11, the bending of the bent portion 11 downward in the vehicle is likely to occur due to its mass, and in that case, the upper member 14 may not be provided.

Then, as shown in FIG. 11, the bent portion 1
When No. 1 is bent and deformed, and bending stress in the plastic region begins,
The vehicle body deceleration is higher than the level at the bottom of the area d as shown in the area e. In the present embodiment, the crushed portion 8
The average reaction force load of is set lower than the deformation start load of the bent portion 11 (adjustable by the plate thickness of the side member 1)
In addition, the deceleration and the bending portion 1 when the crushed portion 8 is compressed and deformed.
The ratio with the deceleration when 1 is bent and deformed is maximized,
The vehicle body deceleration at the time of bending deformation of the bent portion 11 is greatly reduced with respect to the vehicle body deceleration at the time of crushing of the crushing portion 8 as shown in a region e of FIG. As a result, the maximum value of the occupant deceleration can be brought to the latter half of the area e (see FIG. 8).
Imaginary line), and its maximum value can be kept low.

[0025]

As described above, according to the present invention, the reaction force generation pattern is adjusted by sequentially shifting the deformation mode of the reaction force generation member from compression to bending, and the deceleration of the living space portion of the vehicle body collides. It is possible to make it steep in the initial stage, then rapidly lower it, and to make it constant after the middle stage. In particular, if a stress concentration portion for making the deformation start load closer to the average reaction force load is provided in the first portion, the deformation start load can be lowered, which can contribute to the constant reaction force load over the entire stroke. As a result, the peak value of the occupant deceleration can be reduced with a smaller deformation stroke than the conventional structure, and if the same deformation stroke as the conventional one can be obtained,
A significant reduction in the occupant deceleration peak value can be achieved. Moreover, since the amount of movement of the occupant with respect to the vehicle body can be suppressed to be small, the possibility of a secondary collision in which the occupant bumps into a structure inside the vehicle and is injured can be reduced.

[Brief description of drawings]

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

FIG. 2 is a side view of a main part of a side member according to the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an explanatory view showing a deformation process of the side member at the time of collision.

[Fig. 5] Deceleration waveform diagram at the time of collision

FIG. 6 is a side view of a main portion of a side member showing a second embodiment.

7 is a sectional view taken along the line VII-VII in FIG.

FIG. 8 is a deceleration waveform diagram at the time of a collision in the second embodiment.

FIG. 9 is an explanatory diagram showing a deformation process of the side member in the initial stage at the time of collision.

FIG. 10 is an explanatory view showing a deformation process of the side member in the middle stage of a collision.

FIG. 11 is an explanatory view showing the deformation process of the side member in the latter stage of the collision.

[Explanation of symbols]

1 Side member (reaction force generating member) 6 Bent part (2nd part) 8 Crushing part (first part) 9 Stress concentration part 11 Bent part (2nd part)

Continued front page       (56) Reference JP-A-7-101354 (JP, A)                 JP-A-8-216917 (JP, A)                 German patent application publication 4401865 (DE, A               1)

Claims (3)

(57) [Claims] 1. A vehicle body structure for an automobile, comprising a reaction force generating member that receives a compressive load along the direction of deceleration at the time of a collision, wherein the member has a first portion that makes a small stroke due to compressive deformation, and the first portion. It has a bent portion initiates bending deformation at a higher value than the deformation starting load of the portion, and a second portion to increase stroke while generating a lower average reaction force loads than the average reaction force load of the first portion A vehicle body structure characterized by being continuously provided. 2. The vehicle body structure according to claim 1, wherein the first portion has a stress concentrating portion for making the deformation start load closer to the average reaction force load. 3. The vehicle body structure according to claim 1, wherein the second portion is easily bent and deformed downward.