JPH09240393A - Bumper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve shock absorbing performance by projectingly providing a plurality of cylindrical ribs independent of each other in the surface of a reinforcing member side of a resin member. SOLUTION: In a bumper structure, square cylindrical ribs 3 are projectingly provided in the rear surface of a resin member 2 so as to be independent of each other and a reinforcing member 4 is installed in the rear part of the rib 3. When a shock is received, four side walls constituting the square ribs 3 are alternately bent and thus the bumper is deformed to be snakebody-like. Thus, since a high deformation load is maintained even when the resin member is deformed by receiving a shock, the bumper having high shock absorbing performance as a whole is obtained. Also, since all the installed ribs are effectively deformed, it is not necessary to increase the sizes of the ribs more than necessary and thus resin materials are saved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bumper composed of a resin member and a reinforcing member, and provides a structure of the bumper having excellent impact absorbing performance.

[0002]

2. Description of the Related Art In recent years, there has been an ever-increasing demand for improved safety in the event of an automobile collision, and therefore, various devices have been devised. In particular, bumpers attached to the front and rear of a vehicle are required to play a large role in absorbing shock during a collision.

Many of these bumpers use a resin, but if they are roughly classified, they are disclosed in JP-A-52-5.
A combination of only a resin member as shown in Japanese Patent No. 3336 and a resin member and a reinforcing member made of a steel plate or an aluminum mold member as shown in Japanese Utility Model Laid-Open No. 55-34910. There is a structure that both absorb the shock.

Among them, in the case of a bumper structure consisting only of resin members, since it is necessary to realize high rigidity only with the resin members, the resin members are provided with thick vertical ribs or horizontal ribs to improve the rigidity. In order to realize the required high rigidity and shock absorption capacity, there is a limit when the shock velocity is high.

On the other hand, in the case of a bumper structure composed of a resin member and a reinforcing member, the reinforcing member has a higher strength than the resin member, and therefore the rigidity can be sufficiently secured by the reinforcing member. In this case, since the resin member is sandwiched between the collision object and the reinforcing member and deforms, the shock is easily absorbed. Therefore, it can be said that this bumper structure is more appropriate when the collision speed is higher.

[0006]

In a conventional bumper comprising such a resin member and a reinforcing member, the resin member has continuous ribs arranged at relatively large spaces as shown in FIG. There are two types, one protruding from the reinforcing member side and the other protruding from the reinforcing member side by arranging similarly continuous ribs in a fine mesh shape.

In the former case, since the ribs are roughly arranged at wide intervals, the connecting force between the ribs is small even if they are continuous, and the resin member is deformed due to the bending of the ribs. In the deformation of the bumper due to the bending of the rib, the bending deformation proceeds under a low load after the maximum load is reached during the initial rib buckling. Therefore, the impact load becomes very small.

In the latter case, the rib intervals are small and the ribs are densely arranged, so that the ribs are closely connected to each other and are firmly connected to each other, so that the rigidity of the entire rib is high and deformation of the rib is unlikely to occur. Therefore, the deformation of the bumper becomes almost elastic.

As described above, in the coarsely arranged ribs, the deformation amount is large but the load is small. On the other hand, in the dense rib arrangement, the deformation amount is small but the deformation amount is small. -The amount of shock absorption represented by the area of the load curve is small. Even in the case where the ribs are arranged in the middle of these arrangements, there is no change in that the amount of shock absorption is small depending on whether the ribs buckle at their roots or in any of the above deformed states.

[0010]

As a result of various studies in view of the above, the present invention has improved the shock absorbing ability of a bumper made of a resin member and a reinforcing member.

That is, the bumper of the present invention is a bumper comprising a resin member and a reinforcing member installed behind the resin member, wherein a plurality of independent cylindrical ribs are projected on the surface of the resin member on the reinforcing member side. The cylindrical rib is preferably a substantially cylindrical shape. The resin member is usually produced by injection molding a thermoplastic resin into a desired shape, and a light alloy mold material such as an aluminum alloy is preferable as the reinforcing member in consideration of impact absorption performance and weight reduction.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of a bumper according to the present invention is shown in, for example, FIGS. 1 and 2, but a cylindrical rib (1) is independently provided on one side (reinforcing member side) of a resin member (2). It has been projected. When an impact is applied to the bumper of the present invention from the front, the entire resin member first bends, and the tips of these tubular ribs come into contact with the reinforcing member. Subsequently, the tubular rib starts to deform from its tip. At this time, the tubular ribs are not connected to each other like a network like the conventional ribs, but each restrains itself so as to maintain the original tubular shape. As a result, the ribs do not fall from the base of the ribs, and the entire circumferential wall where the ribs project is deformed into a bellows shape. Then, the deformation of the reinforcing member starts after the tubular rib is sufficiently crushed.

In the resin member of the bumper shown in FIG. 1, the tubular rib has a rectangular cross-sectional shape. However, if the tubular shape is independent as described above, a bellows-like deformation can be induced. Is not necessarily rectangular and may be pentagonal, hexagonal or elliptical. Among them, the case where the cross section is circular (FIG. 2) is most preferable because the bellows-like deformation is efficiently generated in the entire rib as compared with other cross-sectional shapes. The tubular rib may be changed in taper shape such that the thickness of the rib becomes thinner toward the tip, in consideration of the ease of injection molding.

Further, since the cylindrical rib plays a role of absorbing a shock at the time of collision, it is desirable that its installation position is arranged at all positions where shock transmission is expected. However, since this resin member is used in combination with the reinforcing member, the arrangement of the tubular ribs should be determined in consideration of the performance of the reinforcing member. Therefore, in some cases, it may not be possible to arrange them in a horizontal row as shown in FIGS. 1 and 2, but such an arrangement method does not hinder the object of the present invention.

Further, the height and wall thickness of the tubular rib and the material of the resin member are major factors that determine the amount of shock absorption, but the space that the bumper can occupy in the vehicle body and the allowable amount of deformation differ depending on the vehicle model. Therefore, it is necessary to properly select appropriate dimensions and appropriate materials depending on the conditions.

[0016]

EXAMPLES The present invention will be further described below based on examples. The resin member was produced by injection-molding polypropylene into a shape having the following tubular rib. For comparison, the height and the volume of the rib were the same in both the present invention and the conventional example. The material of the reinforcing member is A6063S in both the present invention and the conventional example.
An aluminum alloy (T5 material) was used, and its extruded shape material was used to form a cross section with a "day" shape. The bumper used for the impact test has a structure in which the resin member is fixed in front of the reinforcing member.

FIG. 3 shows a bumper structure of the first example of the present invention. Square tubular ribs (3) are independently projected on the rear surface of the resin member (2), and the ribs (3) are provided behind the ribs (3). The reinforcing member (4) is installed. FIG. 4 shows a bumper structure of Example 2 of the present invention, in which a cylindrical rib (5) is provided in place of the rectangular cylindrical rib. Further, FIG. 5 shows a bumper structure of roughly arranged ribs of Conventional Example 1, in which two flat ribs (6) are provided in the horizontal direction and a plurality of flat ribs (6) are provided at intervals in the vertical direction between them. Further, FIG. 6 shows a bumper structure of densely arranged ribs of Conventional Example 2, in which three flat ribs (6) are arranged in the horizontal direction and the distance between them is made narrower in the vertical direction.

The following impact tests were carried out on these bumpers. That is, as shown in FIG. 7, the reinforcing member (4) was attached to the vehicle body (7) through the stay, and the resin members (2) were attached to the front surface of the vehicle body (7), and the pendulum (8) was collided. Then, the impact load is measured by the load cell attached to the pendulum (8), the displacement amount of the resin member and the reinforcing member is measured by the laser displacement meter attached between the bumper and the vehicle body, and the displacement of the resin member at that time is measured. -The load curve is shown in FIG. Further, the deformed states of the rib portions of Examples 1 and 2 of the present invention and Conventional Examples 1 and 2 at this time were visually inspected and shown in FIGS. 9 to 12.

As shown in FIG. 9, in the bumper of the first example of the present invention, four side walls forming the rectangular tubular rib (3) are alternately bent to form a bellows-like deformation. Further, as shown in FIG. 10, in the bumper of the second aspect of the present invention, it is found that the cylindrical rib (5) is deformed over the entire height direction and the rib is effectively working. On the other hand, as shown in FIG. 11, in the bumper of Conventional Example 1, the base portion is largely bent and deformed. Further, in the bumper of Conventional Example 2, since the impact is distributed to a large number of closely arranged ribs, no bending occurs in each rib, and the initial shape is almost maintained after the test. In this case, the ribs are only elastically deformed in the vertical direction.

Next, the displacement-load curves of FIG. 8 will be compared. The impact absorption performance of the resin member is how the impact energy can be absorbed by the deformation of the resin member. The energy absorption amount is represented by the area surrounded by the displacement-load curve of the resin member. Therefore, the displacement of
Considering the load curve, the load of the conventional example 1 (curve C) is large but the load is small, and the load of the conventional example 2 (curve D) is large but the deformation is small.
On the other hand, since the deformation amount and the load are large in the example 1 of the present invention (curve A) and in the example 2 of the present invention (curve B), the energy absorption is larger than that of the conventional examples 1 and 2. It can be seen that the quantity increases.

[0021]

As described above, according to the present invention, a high deformation load can be maintained even during the deformation of the resin member at the time of impact, so that a bumper having a high impact absorption performance as a whole can be obtained. Further, since the entire ribs installed can be effectively deformed, it is not necessary to make the ribs larger than necessary, and the effect of saving the resin material can be expected.

[Brief description of drawings]

FIG. 1 is a perspective view of a resin member of Example 1 of the present invention.

FIG. 2 is a perspective view of a resin member of Example 2 of the present invention.

3A and 3B are explanatory views showing a bumper configuration of Example 1 of the present invention.

4 (a) and 4 (b) are explanatory views showing a bumper configuration of Example 2 of the present invention.

5 (a) and 5 (b) are explanatory views showing a bumper configuration of Conventional Example 1. FIG.

6A and 6B are explanatory views showing a bumper configuration of Conventional Example 2 in both FIGS.

FIG. 7 is an explanatory diagram showing an impact test.

FIG. 8 is a diagram showing a displacement-load curve of an impact test result.

FIG. 9 is an explanatory diagram showing a deformed state of the rectangular tubular rib of Example 1 of the present invention.

FIG. 10 is an explanatory diagram showing a deformed state of the cylindrical rib of Example 2 of the present invention.

FIG. 11 is an explanatory diagram showing a deformed state of a rib of Conventional Example 1.

FIG. 12 is an explanatory view showing a conventional bumper structure.

[Explanation of Codes] 1 tubular rib 2 resin member 3 square tubular rib 4 reinforcing member 5 cylindrical rib 6 flat rib 7 vehicle body 8 pendulum

Claims (2)

[Claims] 1. A bumper comprising a resin member and a reinforcing member installed behind the resin member, wherein a plurality of cylindrical ribs independent from each other are provided on a surface of the resin member on the reinforcing member side. . 2. The bumper according to claim 1, wherein the tubular rib has a substantially cylindrical shape.