JP2003072588A - Hollow member for car body frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow member for a car body frame capable of heightening the energy absorbing efficiency to a higher degree. SOLUTION: The hollow member for the car body has a polygonal profile in the section shape and is furnished with ribs tying the apices to the center shaft, wherein the inside of the intersection part of two plates constituting the peripheral circumferential wall with the ribs is shaped rounded, and the distance (h) from the virtual top point of the inside circumferential walls of the two plates lower than the top point of the peripheral circumferential wall in the intersection part in an amount corresponding to the plate thickness to the rib side end point of the rounded part is made over 13% of the distance L between the roundness end points of the two plate ends constituting the peripheral circumferential wall, which allows enlargement of the section area of that apex part of the whole section exhibiting a large plastic deformation amount to lead to enlargement of the plastic deformation region, so that the anti- buckling load can be heightened to a higher degree. This constitution allows exerting a large effect for increasing the energy absorbing amount to a higher degree without bringing about a substantial increase of the outside dimensions.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow member for a vehicle body frame for absorbing impact energy caused by a collision of a vehicle by compressive deformation. [0002] The same applicant as the present invention discloses a hollow extruded material having a polygonal cross-sectional shape, and having a rib extending in the axial direction connecting each apex angle and a central axis. Japanese Patent Application No. 10-10294 (Japanese Patent Application Laid-Open No. 11-104) discloses a vehicle body frame structure that absorbs impact energy at the time of collision by compressive buckling deformation caused by the hollow extruded member receiving a collision load. 208519). [0003] According to this, a cross-sectional area where an appropriate buckling strength can be obtained can be set by setting the relationship between the length of one side of the polygon and the thickness thereof, so that the desired impact can be obtained without excessively increasing the external dimensions. Energy absorption characteristics can be obtained. [0004] However, it is preferable that the energy absorption with respect to the sectional area of the member is as large as possible. In the case of a vehicle in which it is difficult to set a sufficient crushable zone, the energy absorption efficiency of the member is high. There is a demand for a further increase in. The present invention has been made in view of such findings, and a main object of the present invention is to provide a hollow member for a vehicle body frame capable of further increasing the energy absorption efficiency. The present inventor has proposed that the cross-sectional shape of the outer contour is a substantially regular polygon, that the rib has a connection between the apex angle of each apex and the central axis, and that the intersection between the two plates and the rib that constitute the outer peripheral wall is provided. In the hollow member for a vehicle body frame in which the inner part of the circle has a round shape, the virtual vertex of the inner peripheral wall shifted by the thickness of the plate from the vertex of the outer peripheral wall at the intersection toward the center of the regular polygon and the above-mentioned radius Distance h in the extending direction of the rib from the rib side end point
And the distance L between the radius end points of both ends of the plate constituting the outer peripheral wall have a significant influence on the energy absorption efficiency. In order to achieve the above-mentioned object, according to the present invention, the cross-sectional shape of the outer contour is polygonal, and connects the apex angle of each apex corner 3 to the central axis. In the hollow member for a vehicle body frame provided with the ribs 2, an inner portion of an intersection between the two plates constituting the outer peripheral wall and the rib is formed in a round shape, and the top of the outer peripheral wall at the intersection has The distance h in the extending direction of the rib between the virtual vertex of the inner peripheral wall shifted by the thickness of the plate toward the center of the square and the end point on the rib side of the radius is the distance between both ends of the plate constituting the outer peripheral wall. The length is 13% or more of the distance L between the plate-side end points constituting the outer peripheral wall of the radius. In this way, it is possible to efficiently increase the cross-sectional area of the vertex having a large amount of plastic deformation in the entire cross section, and as shown in FIG. 4, the energy absorption efficiency is significantly improved. The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a basic sectional shape of a hollow member for a body frame to which the present invention is applied in a first embodiment. This hollow member for a body frame is made of an extruded material of an aluminum alloy, and has an outer contour of a regular hexagonal cross section perpendicular to the central axis O by six plates 1 constituting an outer peripheral wall. , A rib 2 connecting each vertex 3 and the central axis O is provided. The ribs 2 can increase the relative cross-sectional area without increasing the external dimensions of the cross-section and without increasing the thickness of the cross-section unnecessarily, so that appropriate buckling strength can be obtained without impairing the bending rigidity of the frame. , The stability of the compressive stress over the entire stroke can be increased. As shown in FIG. 2 in an enlarged manner, at each apex corner 3 where the edges of three plates comprising two plates 1 and one rib 2 constituting the outer peripheral wall intersect each other. Two boards 1
The inner portion 4 of the intersection between the rib and the rib 2 is formed in a round shape. Here, the virtual vertex of the inner peripheral wall shifted by the thickness of the plate 1 from the vertex of the outer peripheral wall at each vertex 3 of the two plates 1 constituting the outer peripheral wall toward the center of the regular polygon. The distance h (hereinafter referred to as the height of the apex portion 3) h between T and the end point S1 of the inner portion 4 on the rib 2 side of the radius is the distance between the radius end points S2 at both ends of the plate 1 (hereinafter, referred to as the height). (Referred to as the length of plate 1)
L is 13% or more of L. As shown in FIG. 4, the buckling wavelength S is determined by the height h of the vertex 3, and the height h of the vertex 3 and the buckling wavelength S are substantially proportional. The buckling wavelength S is the width at the time of buckling in the vertical direction in FIG. 3, that is, the left and right length in the figure. However, as shown in FIG. 5, regarding the relationship between the length L of the plate 1 and the height h of the apex 3, the height h of the apex 3 is larger than the length L of the plate 1. Is 13% or more (h / L ≧
0.13), the energy absorption efficiency sharply improves. Here, dimensions that can be changed to satisfy the h / L ≧ 0.13 include the length L of the plate 1, the thickness of the plate 1, the thickness of the inner portion 4 at each vertex 3. And the outer wall side shape of the two plates 1 at each apex 3 (this is not necessarily a radius). By appropriately setting these, h / L ≧ 0 .13 may be satisfied. As described above in detail, according to the present invention, there is provided a hollow member for a vehicle body frame having a rib having a cross section of a substantially regular polygon and connecting each apex angle with a central axis. ,
The inner portion of the intersection of the two plates and the ribs forming the outer peripheral wall has a round shape, and the inner portion shifted from the vertex of the outer peripheral wall at the intersection toward the center of the regular polygon by the thickness of the plate. The distance h between the imaginary vertex of the peripheral wall and the end point on the rib side of the radius is 13% or more of the distance L between the radius end points at both ends of the plate constituting the outer peripheral wall, so that the entire length is increased. Since the cross-sectional area of the apex portion having a large plastic deformation amount in the cross section can be increased and the plastic deformation region can be expanded, the buckling load can be further increased. Therefore, according to the present invention, the amount of energy absorption can be further increased without causing a substantial increase in external dimensions, and a great effect can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a basic cross-sectional shape of a hollow member for a vehicle body frame to which the present invention is applied. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a longitudinal sectional view of a hollow member for a vehicle body frame showing a buckling deformed body for explaining a buckling wavelength S. FIG. 4 is a diagram showing the relationship between the virtual vertex of the inner peripheral wall closer to the center of the member by the thickness of the plate than the vertex of the outer peripheral wall at the intersection of the rib and the plate constituting the outer peripheral wall, and the rib side end point of the radius. 9 is a graph showing a relationship between an extension direction distance (height of a vertex) h and a buckling wavelength S. FIG. 5 is a graph showing a relationship between a ratio of a distance L between ends of both ends of a plate constituting an outer peripheral wall having a height h of a vertex to an energy absorption efficiency. [Description of Signs] 1 Plate 2 constituting peripheral wall 2 Rib 3 Apex corner portion 4 Inner part of intersection of two plates 1 and rib 2

Continuation of front page    (72) Inventor Yuta Urushiyama             1-4-1 Chuo, Wako-shi, Saitama Stock Association             Inside the Honda Research Laboratory

Claims (1)

Claims: 1. A hollow member for a vehicle body frame having a cross-sectional shape of an outer contour substantially in the shape of a regular polygon and having a rib connecting each apex angle and a central axis, wherein the outer peripheral wall is formed. The inner part of the intersection between the two plates and the ribs has a round shape, and the inner peripheral wall shifted from the vertex of the outer peripheral wall at the intersection toward the center of the regular polygon by the thickness of the plate. The distance h in the extending direction of the rib between the imaginary vertex and the end point on the rib side of the round is 13 times the distance L between the plate side end points forming the outer peripheral wall of the round at both ends of the plate forming the outer peripheral wall. % Of the hollow member for a body frame.