JPH04300716A - Automobile door reinforcing beam - Google Patents

Abstract

PURPOSE:To increase the maximum bending stress so that a thin steel pipe may be used by applying partial or continuous heat treatment to the middle portion of a reinforcing beam which is arranged in an automobile door in its longitudinal direction. CONSTITUTION:A pipe-shaped reinforcing beam 5 is arranged in a longitudinal direction, between the door outer panel and the door inner panel for setting rigidity of a door panel with its both ends supported to both sides of the door panel 1 via brackets 6, 7. The first reinforcing plate 9 reinforce a belt line portion and the second reinforcing plate 11 to reinforce the lowerside of a door handle portion are welded to the intermediate portions of the reinforcing beam 5. Only the middle portion 5a of the reinforcing beam 5 is subjected to high frequency quenching to vary its bending stress so that the maximum bending stress is increased at a position where load is concentrated. Both ends are not subjected quenching to achieve their easier welding to brackets 6, 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing beam for automobile doors.

0002

2. Description of the Related Art In the outer panel of an automobile door, since the steel plate used as the panel is thin compared to its area, as shown in FIGS. It may be reinforced by installing. In this case, door beam 10
Since both the bending stress and section modulus of 2 were constant,
The bending moment of the door beam 102 was constant over its entire length.

0003

However, when a load is applied to the door beam 102, the load tends to concentrate at the center and buckle at one location. And door beam 1
If 02 is made thicker and the section modulus is increased, since the door beam 102 has a constant cross section over its entire length, a large allowable bending moment will be applied to an unnecessary location, which will reduce the amount of bending moment necessary to absorb energy. "Bending" no longer occurs.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a reinforcing beam for an automobile door, which increases the strength of a portion where a load is concentrated while maintaining an energy absorption function.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention aims to solve the problem that loads are concentrated on reinforcing beams arranged along the front-rear direction between the door outer panel and the door inner panel of an automobile door. The reason is that the middle part is partially or continuously heat treated.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

In FIGS. 1 to 3, a door panel 1 is composed of a door outer panel 2 and a door inner panel 3.
A window glass 4 is raised and lowered between the door outer panel 2 and the door inner panel 3.

Door outer panel 2 and door inner panel 3
A pipe-shaped reinforcing beam 5 is arranged between the two in the front-rear direction, and both ends of the reinforcing beam 5 are attached to brackets 6 on both sides of the door panel 1, as shown in FIGS. 4(a) and 4(b).
7.

A first reinforcing plate 9 for reinforcing the belt line portion 8 and a second reinforcing plate 11 for reinforcing the lower side of the door handle portion 10 are welded to the middle of the reinforcing beam 5.

The reinforcing plate 9 is formed in a triangular shape, and the bottom part A is curved in an R shape and welded to the reinforcing beam 5.
The apex portion B is formed by protruding toward the belt line portion 8 side of the door outer panel 2, and a foamed sealer 13 is injected into the hole 12 formed along the edge to seal the door outer panel 2 at five locations.
is glued to.

The reinforcing plate 11 is a rectangular plate with a curved central portion and welded to the reinforcing beam 5.
Foam sealer 13 is applied to the holes 14 formed in the four corners of the plate 11.
is injected and bonded to the door outer panel 2.

An inner reinforcement 15 is spot-welded to the belt line portion of the door inner panel 3 for reinforcement.

[0013] In the reinforcing beam 5, only the intermediate portion 5a is subjected to induction hardening to change the bending stress σb. Induction hardening allows the bending stress σb to be freely controlled by partially hardening the intermediate portion 5a of the reinforcing beam 5.

Next, the effects when the reinforcing beam 5 is not hardened and when it is hardened will be explained.

When hardening is not performed, if the reinforcing beam 5 is considered as a simple beam supported at both ends as shown in FIG. 5, the moment distribution applied to the reinforcing beam 5 of length l with respect to the load P is as shown in FIG. become.

The maximum bending moment Mmax at this time is expressed as Pl/4.

The allowable bending moment M in the case of the pipe-shaped reinforcing beam 5 is as shown in FIG. 7, and is expressed by σbZ. At this time, σb is the bending stress, Z is the section modulus, and these values are constant.

When the distribution charts of FIGS. 6 and 7 are combined, the result is shown in FIG. 8, which shows that the load is concentrated at the center of the reinforcing beam 5, causing buckling as shown in FIG. The section modulus of the buckled portion decreases, and the allowable bending moment M decreases, resulting in loss of original strength.

Next, when the middle part of the reinforcing beam 5 is partially hardened to a length L as shown in FIG.
When the moment distribution diagram of and the distribution diagram of the allowable bending moment M of the reinforcing beam 5 are combined, it becomes as shown in Fig. 10,
The reinforcing beam 5 will be broken at three locations (
(See Figure 11).

[0020] Therefore, since the reinforcing beam 5 is bent at three places, the bending angle at each point becomes small, and the section modulus can be prevented from becoming extremely small. Furthermore, since the load is distributed to three locations, the allowable load of the reinforcing beam 5 is also increased.

[0021] In the above embodiment, a case has been described where two types of bending stress σb are created in the reinforcing beam 5, but three or more bending stress σb values are used to distribute different bending stress σb in stages. You can do it like this. Further, the value of the bending stress σb may be continuously changed.

[0022]

[Effects of the Invention] As described above, according to the reinforcing beam for automobile doors according to the present invention, heat treatment is applied partially or continuously to the middle part of the reinforcing beam where the load is concentrated, so that the load is reduced. It is possible to increase the maximum bending stress at the location where it is concentrated. Therefore, sufficient bending stress can be obtained even if a steel pipe with a thinner wall thickness than a conventional reinforcing beam is used. Further, since both ends of the reinforcing beam are not hardened, welding to the bracket is easy and press working is easy. Furthermore, since it is possible to use a reinforcing beam with a smaller diameter than before, even if the cross-sectional area of the door panel is limited, a reinforcing beam made of steel pipe can be used.

[Brief explanation of drawings]

FIG. 1 is a side view showing a car body including a reinforcing beam.

FIG. 2 is a front view of an automobile door equipped with a reinforcing beam.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

4(a) is a plan view showing the reinforcing beam of FIG. 2; FIG. (b) is a front view of (a).

FIG. 5 shows a simply supported beam.

FIG. 6 is a diagram showing the moment distribution due to the load of a simply supported beam.

FIG. 7 is a diagram showing the allowable bending moment applied to the beam.

FIG. 8 is a diagram combining the moment distribution due to load and the allowable bending moment distribution.

FIG. 9 is a diagram showing buckling of a reinforcing beam.

FIG. 10 is a diagram showing a hardened reinforcing beam.

FIG. 11 is a diagram showing the distribution of allowable bending moment applied to the reinforcing beam.

FIG. 12 is a diagram combining the load moment distribution and the allowable bending moment distribution.

FIG. 13 is a diagram showing buckling of a reinforcing beam.

FIG. 14 is a conceptual diagram showing an automobile door equipped with a conventional door beam.

15 is a cross-sectional view taken along the line AA in FIG. 12. FIG.

[Explanation of symbols]

1 Door panel 2 Door outer panel 3 Door inner panel 5 Reinforcement beam 5a Middle part

Claims (1)

[Claims] [Claim 1] In a reinforcing beam disposed along the front-rear direction between the door outer panel and the door inner panel of an automobile door, heat treatment is applied partially or continuously to the intermediate portion where load is concentrated. A reinforcing beam for automobile doors featuring: