JPH0565076A - Structure of strength member of car body - Google Patents

Abstract

PURPOSE:To suppress the initial reaction load when a member body launches a collision and increase the collisional energy absorbing amount by maintaining the mean reaction load high. CONSTITUTION:A longitudinal rib 3 and a crosswise rib 4 are formed in a single piece in the longitudinal direction within the member body 1 of a side member SM formed through extrusion process from an aluminum light alloy material in a closed square section. Arc-shaped slopes 3a, 4a are formed at the ends of the longitudinal and crosswise ribs 3, 4. The relation between length Lb of the slopes 3a, 4a and the peripheral length La of the member body 1 is 1/2La<Lb<La.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strength member structure for an automobile, and more particularly to a structure for a strength member such as a front side member and a rear side member which are arranged in the front-rear direction of the vehicle body.

[0002]

2. Description of the Related Art FIG. 13 shows a structure of a vehicle body structure of an automobile. The vehicle body structure includes a side member SM and a side sill SS, which are strength members in the longitudinal direction of the vehicle body, and a plurality of cross members, which are strength members in the vehicle width direction. CM is joined to form a skeleton base, and a front pillar AP, a center pillar BP, and a rear pillar CP are erected vertically on the skeleton base as strength members in the vertical direction of the vehicle body.

As the strength member in the front-rear direction of the vehicle body, for example, the side member SM, there is known a member formed by extruding a light aluminum alloy material into a rectangular closed cross section as shown in FIG. 64-67482). This side member SM is provided with a plurality of weld beads 2 at appropriate intervals in the longitudinal direction on the peripheral wall of the end portion of the member main body 1, and the side beads SM are knot-shaped due to the annealing effect when the weld beads 2 are formed. A rigid portion is formed so that the member body 1 can be easily buckled and deformed by the low-rigidity portion when a collision input acts in the axial direction.

In addition to this, as shown in FIG. 15, a member body 1 extruded into a rectangular closed cross section by using an aluminum light alloy material as described above is provided inside a member main body 1 having a plurality of closed cross sections. The rib 3 and the horizontal rib 4 are integrally molded in the longitudinal direction,
A member main body 1 having a lattice-shaped closed cross section may be considered.

[0005]

When a collision input acts on the side member SM in the axial direction during a vehicle collision, in the case shown in FIG. 14, a plurality of strips are longitudinally formed on the peripheral wall of the end of the member body 1. Since the welding beads 2 of _{No. 1} are formed and buckling deformation easily starts from these welding beads 2 portions, the initial reaction force load Pc ₁ can be suppressed to a relatively small value as shown by the line a in FIG. On the other hand, the average reaction force load Pm ₁ generated after the start of buckling also decreases, and the amount of collision energy absorption decreases.

In the structure shown in FIG. 15, the vertical ribs 3 and the horizontal ribs 4 form a closed cross section of the member main body 1 in a lattice shape so that the average as shown by the line b in FIG. While the reaction force load Pm ₂ can be increased to increase the collision energy absorption amount, the initial reaction force load Pc ₂ is increased and the impact force applied to the vehicle body is increased.

Therefore, according to the present invention, the initial reaction force load at the time of collision can be reduced, and the average reaction force load after the start of buckling can be increased to secure the desired amount of collision energy absorption. A vehicle body strength member structure for an automobile is provided.

[0008]

In a structure in which a rib for partitioning a plurality of closed cross sections into a member body is integrally formed in the longitudinal direction inside a member main body that is extruded to have a closed cross section and is disposed in the front-rear direction of a vehicle body, An inclined portion is formed at the end of the rib from the connection point with the peripheral edge of the member main body toward the inside of the member main body.

[0009]

When a collision input is applied to the end of the member body in the axial direction during a vehicle collision, a rib is formed on the end face of the member body, the inclined portion extending from the connecting point with the peripheral edge of the member body toward the inside of the member body. Since the rib cross-sectional area is extremely small, it is easy to buckle and deform in the axial direction.
The initial reaction force load can be kept small. Since the rib cross-sectional area gradually increases with the progress of buckling, the original reinforcing effect of the rib is obtained, the average reaction force load is increased, and the collision energy absorption amount is increased.

[0010]

Embodiments of the present invention will now be described in detail by taking the side member as an example and assigning the same reference numerals to the same parts as those of the conventional structure.

In FIGS. 1 and 2, 1 is a side member SM extruded from a light aluminum alloy material into a rectangular closed cross section.
The member main body 1 is shown in which the vertical ribs 3 and the horizontal ribs 4 that divide the closed cross section into a plurality of parts are integrally formed in the longitudinal direction. The end portions of the vertical ribs 3 and the horizontal ribs 4 are formed with inclined portions 3a and 4a extending from the connecting point with the peripheral edge portion of the member main body 1 toward the inside of the member main body 1.
In this embodiment, the inclined portions 3a and 4a are formed in an arc shape with the intersection of the vertical ribs 3 and the horizontal ribs 4 as the deepest portion, and the ribs are cut off from the end face side of the member main body 1 toward the inside. The area is gradually increased from zero so that the end portion is easily buckled and deformed when a collision input is applied in the axial direction.

Here, the length of the long side of the member body 1 is L
a and the length from the end surface of the member main body 1 of the inclined portions 3a and 4a to the deepest portion is Lb, considering the change of the initial reaction force load with respect to the collision input, as shown in FIG.
Although the initial reaction force load decreases as b increases, Lb becomes La
When the value exceeds the value of, the initial reaction force load is obtained as a value equivalent to the initial reaction force load Pc ₁ in the member main body 1 (see FIG. 14) having a simple rectangular closed cross section with no rib inside, and becomes substantially constant. Further, in the vicinity of the dimension where Lb is 1 / 2La, the initial reaction force load comes to approach Pc ₁ .

On the other hand, considering the buckling load-displacement characteristics of the member body 1 when the dimension of Lb is set to be La or more, the initial reaction force load at the time of collision is Pc ₁ as shown in FIG. However, after that, the reaction force load suddenly decreases, and then rises again, and the inclined portions 3a of the vertical ribs 3 and the horizontal ribs 4,
When the intersection point of 4a is exceeded, the reaction force load is obtained as Pm ₂ and becomes substantially constant. However, in this case, since the reaction force load sharply drops at the initial stage of buckling deformation at the time of collision of the member main body 1, since the vertical ribs 3 and the horizontal ribs 4 are provided, a large amount of collision energy is absorbed. You can't expect the increase.

Therefore, the dimension L of the above-mentioned inclined portions 3a and 4a
b is 1 in consideration of the initial reaction force load, the amount of collision energy absorption, the bellows-like buckling deformation pitch of the member body 1, and the like.
It is set in the range of / 2La <Lb <La.

According to the structure of the above embodiment, when a collision input is applied to the end portion of the member main body 1 at the time of vehicle collision, the member main body 1 buckles and collapses together with the internal vertical ribs 3 and the horizontal ribs 4 and collides with the collision energy. Although absorbed, the buckling of only the peripheral wall of the member main body 1 occurs due to the formation of the arc-shaped inclined portions 3a and 4a of the vertical ribs 3 and the horizontal ribs 4 in the initial stage of the collision, and C in FIG.
As shown by the line, the initial reaction force load is obtained as Pc ₁ and can be kept low. When the buckling deformation progresses from the A position to the B position shown in FIG. 2, the cross-sectional areas of the vertical ribs 3 and the horizontal ribs 4 gradually increase, and the vertical ribs 3 and the horizontal ribs 4 also buckle, so that the reaction load A sudden drop is avoided, and the buckling deformation progresses after the intersection of the inclined portions 3a, 4a of the vertical ribs 3, horizontal ribs 4, so that the reaction force load becomes Pm ₂ and becomes substantially constant. Become. Therefore, it is possible to reduce the initial reaction force load at the time of a vehicle collision to reduce the impact force, and increase the average reaction force load after the initial stage of the collision to realize an increase in the amount of collision energy absorption. it can.

In the embodiment described above, the ribs in the member main body 1 are arranged so as to intersect the vertical ribs 3 and the horizontal ribs 4, but in addition to this, as shown in FIG. The intended purpose can also be achieved by providing a plurality of lateral ribs 4 and forming the inclined portions 4a at the ends of the lateral ribs 4 in the same manner as described above.

6 and 7 show the side member SM having the above-mentioned structure.
Is used as the front side member SM ₁ by arranging the end portions on the side where the inclined portions 3a and 4a are formed as the front portion of the vehicle body, the front bumper 5 is attached to the front end portion of the front side member SM ₁ via the bumper stay 6. .. The bumper stay 6 is formed by forming notches 8 on the upper and lower edges and bending-shaped a bumper attaching portion 9 in one direction on the upper and lower edges of the front end portion, and a bent portion on the rear portion of the stay body 7. Pressure receiving portion 1 that engages with the front end surface of the member body 1.
0, and the bracket 11 bent and formed rearward from the side edge of the pressure receiving portion 10 is inscribed in the side wall surface on one side of the member main body 1 to fix the bolt and nut. The bumper mounting portion 9 is reinforced by a stay funner 12 which is joined to substantially the rear half of the peripheral edge and is laid across in the vertical direction. Bolts and nuts are fixed.

Therefore, in this embodiment, in the case of a frontal collision of the vehicle, at the time of a light collision, only the stay main body 7 is bent and deformed to one side from the notch 8 forming portion as a starting point, as shown in FIG. While absorbing energy to prevent deformation and damage on the vehicle body side, if the degree of collision is large, the stay body 7
The bumper mounting portion 9 abuts the pressure receiving portion 10 due to the bending deformation of the member, and the collision input is evenly applied to the end portion of the member main body 1 via the pressure receiving portion 10 to cause the member main body 1 to buckle and deform as described above. Absorb the collision energy.

FIG. 9 shows a different example of the bumper stay 6, in which the stay body 7 has a bellows portion 7a formed in the middle thereof, and a wedge which is inscribed in one side wall of the member body 1 on one side thereof. The parts 14 are arranged so as to be joined. Brackets 11a, 11a are provided on the upper and lower edges of the rear end of the stay body 7.
Are bent and formed, and the bracket 11a is attached to the upper wall of the member main body 1 and the bracket 11b is attached to the side wall of the member main body 1 by fixing the bolts and nuts 15.

In the case of this embodiment, when the rear surface of the vehicle collides, as shown in FIG.
And plastically deforms and moves backward into the member main body 1. Along with this, one side wall of the member main body 1 is deformed inward by the wedge portion 14 to serve as a trigger for buckling deformation of the member main body 1, and the member main body 1 is buckled and deformed in the same manner as described above to reduce collision energy. Absorb.

FIG. 11 shows the side member SM with the inclined portion 3a,
It shows a case where the end portion on the formation side of 4a is arranged at the rear portion of the vehicle body and used as the rear side member SM ₂ . Even in this embodiment, the member main body 1 does not cause an increase in the initial reaction force load due to the formation of the inclined portions 3a and 4a (see FIG. 1) of the vertical ribs 3 and the horizontal ribs 4 at the time of a rear surface collision of the vehicle. Then, the buckling deformation is started, and gradually the buckling deformation is carried out in an orderly manner in a bellows shape together with the internal vertical ribs 3 and the horizontal ribs 4, so that the collision energy can be efficiently absorbed. In the case of the rear side member SM ₂ , FIG.
In order to avoid interference with a suspension member or the like (not shown) on the rear side portion thereof, as shown in FIG. 5, since the arch portion MA that curves upward is formed, it is considered that the initial reaction force load at the time of a rear surface collision is high. It is conceivable that stress concentrates on the arch portion MA and the arch portion MA breaks as shown by the chain line in the figure, making it impossible to absorb collision energy well. However, as in this embodiment, the initial reaction force load at the time of collision is By suppressing the force to be small, the bellows-like plastic deformation of the rear end portion of the member main body 1 can be gradually propagated to the front of the vehicle body, and effective collision energy absorption can be performed without causing breakage of the arch portion MA. be able to.

Although the side member SM has been described in the above embodiment, the same effect as described above can be obtained by applying the side member SM to the side sill SS arranged in the longitudinal direction of the vehicle body.

[0023]

As described above, according to the present invention, the end portion of the rib integrally formed in the closed cross section of the member main body is formed with the inclined portion, and the cross sectional area of the rib from the end face side of the member main body is formed. The initial reaction force load can be kept small and the average reaction force load can be kept high when a collision input is applied to the end of the member main body. It has a practically great effect that the energy absorption amount can be remarkably increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side view of the embodiment.

FIG. 3 is a characteristic diagram showing a relationship between a length of an inclined portion of a rib and a buckling load in the example.

FIG. 4 is a buckling load of the member main body when the length of the inclined portion of the rib of the embodiment is made larger than the long side length of the member main body;
Displacement characteristic diagram.

FIG. 5 is a perspective view showing another example of the present invention.

FIG. 6 is an exploded perspective view showing an example in which the member main body of FIG. 1 is applied to a front side member.

FIG. 7 is a view on arrow C of FIG.

FIG. 8 is a plan view showing a deformed state of the bumper stay shown in FIGS.

FIG. 9 is a perspective view showing another example of the bumper stay.

10 is a plan view showing a deformed state of the bumper stay of FIG.

11 is a side view showing an example in which the member main body of FIG. 1 is applied to a rear side member.

FIG. 12 is a buckling load-displacement characteristic diagram of the member main body.

FIG. 13 is a perspective view showing a vehicle body frame structure of an automobile.

FIG. 14 is a perspective view showing a structure of a conventional member main body.

FIG. 15 is a perspective view showing a different example of a conventional member main body.

[Explanation of symbols]

 1 ... Member main body, 3, 4 ... Ribs, 3a, 4a ... Inclined portion.

Claims (1)

[Claims] 1. A structure in which a rib that divides the closed cross section into a plurality of pieces is integrally formed in the longitudinal direction inside a member main body that is extruded into the closed cross section and is arranged in the vehicle front-rear direction, has an end of the rib. A vehicle body strength member structure for an automobile, characterized in that an inclined portion is formed in the member from a connection point with a peripheral portion of the member body toward the inside of the member body.