JP5167823B2 - Shock absorbing member - Google Patents

Description

  The present invention relates to an impact absorbing member for absorbing an impact load input to a vehicle at the time of a vehicle collision, for example.

As a conventional shock absorbing member, for example, as described in Patent Document 1, a flat and substantially octagonal member cross section is provided, and a trapezoidal groove is formed in a part of two long sides facing each other. The provided crash box is known.
Patent No. 3912422

  However, in the impact absorbing member of the above prior art, since the length and shape of each side of the ridge line forming the member cross section are not constant, the crushing situation when receiving an impact load due to a collision is different on each surface, Crushing interference between surfaces occurs. Therefore, stable load characteristics cannot be obtained, leading to deterioration of shock absorption.

  An object of the present invention is to provide an impact absorbing member capable of improving impact absorbability at the time of collision.

The present invention, in the impact absorbing member for absorbing the impact load generated at the time of the collision, has a member cross section formed in a concavo-convex shape, all the ridge lines forming the member cross section are formed in a straight line, all the length of each side of the ridge is substantially equal Kuna', it is characterized in that the angle of the convex corner portions of the ridge are all an acute angle.

  In such an impact-absorbing member of the present invention, in addition to forming all the ridge lines forming the member cross section in a straight line, the length of each side of the ridge line is substantially equal to each other, so that the impact is caused by a collision. Since the crushing behavior when receiving a load becomes equal on each surface, the occurrence of crushing interference between the surfaces is prevented. Moreover, since the length of each side of the ridgeline forming the member cross section is shortened by making the shape of the member cross section uneven, the buckling wavelength due to one crushing is shortened. As described above, since the stability of the load characteristics of the shock absorbing member is improved, the shock absorbing property of the shock absorbing member at the time of collision can be improved.

In addition, since all the convex corner portions of the ridge line are acute angles, the crushing load of the shock absorbing member is sufficiently high, so that the stability of the load characteristics of the shock absorbing member is further improved. Thereby, the shock absorption property of the shock absorbing member at the time of collision can be further improved.

Good Mashiku is member cross section is formed in an uneven shape throughout. In this case, since the local rigidity of the shock absorbing member is increased, the shock absorbing member is hardly broken.
Preferably, the shape of the member cross section is a star shape.

  According to the impact absorbing member of the present invention, it is possible to improve impact absorbability at the time of collision and efficiently absorb impact energy.

  Hereinafter, a preferred embodiment of an impact absorbing member according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view (including a partial cross section) showing an embodiment of an impact absorbing member according to the present invention, and FIG. 2 is a transverse sectional view of the impact absorbing member shown in FIG. In the figure, an impact absorbing member 1 of the present embodiment is a member for absorbing an impact load generated in a vehicle at the time of a vehicle collision, and is used, for example, as a crash box for a bumper provided at the front of the vehicle. It is. In this case, the shock absorbing member 1 is joined to the front end surface of the front side member of the vehicle.

  The shock absorbing member 1 is a hollow member having both ends opened, and is formed of iron, aluminum, or the like. The shock absorbing member 1 can be formed by, for example, integral molding by extrusion or welding a plurality of flat plates.

  The shape of the cross section of the shock absorbing member 1 (the cross section perpendicular to the longitudinal direction of the shock absorbing member 1) is substantially a double cross. That is, the cross section of the shock absorbing member 1 has an uneven shape in which a plurality of rectangular protrusions 2 are formed in both the vertical and horizontal directions. Thus, by making the shape of the cross section of the shock absorbing member 1 uneven as a whole, the local rigidity of the shock absorbing member 1 is increased and the shock absorbing member 1 is not easily broken.

  The ridgelines 3 that form the cross section of the shock absorbing member 1 (hereinafter also referred to as “member cross section”) are all formed in a straight line. The term “straight line” as used herein means a straight line in appearance, and for example, minute unevenness and curves that cannot be seen with the naked eye are regarded as straight lines.

  The lengths of the outer sides (outer sides) 3a and the inner sides (inner sides) 3b of the ridgeline 3 forming the member cross section are all substantially equal. The term “substantially equal” as used herein is not necessarily limited to a completely equal one, but includes a slight error (for example, an error of about several mm).

  Moreover, all the angles of the corners (convex corners) 4 on both sides of the convex part 2 in the ridgeline 3 forming the member cross section are 90 degrees.

  When the vehicle collides, an impact load is input to the vehicle. The impact absorbing member 1 receives the impact load as an axial crushing load (axial compressive load), and the impact absorbing member 1 is buckled and deformed by the axial compressive load. This will alleviate the impact energy.

  At this time, as the performance required for the shock absorbing member 1, it is important to earn the shock absorbing amount as much as possible within the limited space and the upper limit of the load. For this purpose, it is necessary to improve the load characteristics (see FIGS. 3 and 4) of the shock absorbing member 1 by obtaining a crushing load with high mass efficiency in the shock absorbing member 1.

In order to obtain a mass-efficient crushing load, first, it is necessary to increase the average crushing load by reducing the level difference between peaks and valleys in the crushing load waveform. For example, in the load characteristics shown in FIG. 3, the crush load A waveform (see broken line) and the crush load B waveform (see solid line) have a constant peak (load peak). Therefore, the average value A _ave of the crushing load A is higher than the average value B _ave of the crushing load B.

  Secondly, it is necessary to stably cause axial crushing (axial compression) throughout the shock absorbing member 1. Specifically, as shown in FIG. 3, the peak (load peak) in the waveform of the crush load is made substantially constant, and the wavelength (buckling wavelength) in the waveform of the crush load is made almost constant. Like that. For example, as shown in FIG. 4, when the load peak and buckling wavelength in the waveform of the crushing load become unstable during the crushing of the shock absorbing member 1, the average crushing load is lowered accordingly, and the mass efficiency is deteriorated. End up.

  Moreover, the crushing load of the impact absorbing member 1 changes according to the angle of the convex corner 4 of the ridgeline 3 that forms the member cross section.

  Here, as shown in FIG. 5, the fracture load when the bending angle θ of the plate member 6 having a cross-sectional mountain shape was changed within a range of 90 to 150 degrees was evaluated by CAE analysis. The evaluation results are shown in FIG. As can be seen from FIG. 6, the breaking load increases as the folding angle θ of the plate 6 decreases. Thereby, it can be said that the crushing load of the shock absorbing member 1 increases as the angle of the convex corner 4 of the ridgeline 3 forming the cross section of the shock absorbing member 1 decreases.

  By the way, if the shock absorbing member has a curved surface portion, that is, if the curved line is included in the ridge line forming the cross section of the shock absorbing member, the following problems occur. That is, the crushing load at the curved surface portion is lower than the crushing load at the flat surface portion. For this reason, compared with a plane part, the mass for taking out the target crushing load will be applied in a curved surface part, and mass efficiency will deteriorate. In addition, if the shock absorbing member has both a flat surface portion and a curved surface portion, the crushing situation at the flat surface portion and the curved surface portion is different, so that the crushing interference occurs, and the distance between the peaks and valleys in the waveform of the crushing load is long. turn into. Furthermore, for inputs other than axial crushing (bending, etc.), the local rigidity of the curved surface portion becomes weaker than the local rigidity of the flat surface portion.

  Even if the length of each side of the ridge line forming the cross section of the shock absorbing member is different, crushing interference occurs due to the difference in the crushing situation. Problem arises.

  On the other hand, in the impact absorbing member 1 of the present embodiment, the sides 3a and 3b of the ridge line 3 forming the member cross section are all formed in a straight line, and the lengths of the sides 3a are substantially all. The length of each side 3b is substantially equal. For this reason, since the axial crushing behavior on each surface of the shock absorbing member 1 becomes equal, the occurrence of crushing interference between the surfaces is prevented. Therefore, since the distance between the peaks and valleys in the waveform of the crushing load is shortened, the average crushing load is increased. In addition, since the buckling wavelength in the waveform of the crushing load tends to be constant, axial crushing occurs stably.

  Moreover, since the cross-sectional shape of the shock absorbing member 1 is generally uneven, the length of one side of the ridge line 3 that forms the cross section of the shock absorbing member 1 is shortened. For this reason, since the whole line length of the ridgeline 3 increases within a limited cross-sectional size (see the broken line in FIG. 2), the average crushing load increases. In addition, since the length of one side of the ridgeline 3 that forms the member cross section is shortened, the crushing behavior at one time becomes compact, so that the buckling wavelength in the waveform of the crushing load is shortened. Get up.

  Moreover, since all the angles of the convex corners 4 of the ridgeline 3 forming the cross section of the shock absorbing member 1 are 90 degrees, the crushing load itself of the shock absorbing member 1 is increased, and as a result, the average crushing load is increased. Becomes higher.

  As described above, the average crushing load of the shock absorbing member 1 is increased and the axial crushing of the shock absorbing member 1 occurs stably, so that a sufficient crushing load with high mass efficiency can be obtained. As a result, it is possible to improve the shock absorbing capability required for the shock absorbing member 1 in the event of a vehicle collision.

  FIG. 7 is a perspective view (including a partial cross section) showing a modification of the shock absorbing member 1 shown in FIG. The shape of the cross section of the shock absorbing member 11 in this modification is a star shape. That is, the cross section of the shock absorbing member 11 has an uneven shape in which a plurality of mountain-shaped convex portions 12 are formed on all sides.

  The ridge lines 13 that form the transverse section of the shock absorbing member 11 (hereinafter also referred to as “member transverse section”) are all formed in a straight line. Further, the lengths of the outer sides 13a and the inner sides 13b of the ridge line 13 forming the member cross section are all substantially equal. Furthermore, the angles of the convex corners 14 of the ridgeline 13 forming the member cross section are all acute angles.

  In this way, the ridge lines 13 forming the member cross section are all formed in a straight line, and the lengths of the sides 13a and 13b of the ridge line 13 are all substantially equal. The axial crushing behavior at the same is equalized, and crushing interference between the surfaces is prevented. Therefore, since the distance between the peaks and valleys in the waveform of the crushing load is shortened, the average crushing load is increased and the axial crushing occurs stably.

  In addition, since the cross section of the shock absorbing member 11 has an uneven shape as a whole, the length of one side of the ridge line 13 forming the member cross section is shortened. For this reason, the buckling wavelength in the waveform of the crushing load is shortened, and the local rigidity of the shock absorbing member 11 is increased.

  Furthermore, since the angles of the convex corner portions 14 of the ridge line 13 forming the member cross section are all acute, the crushing load of the shock absorbing member 11 is sufficiently high.

  The present invention is not limited to the above embodiment. For example, the cross-sectional shape of the impact absorbing member is not limited to the substantially double cross shape and the star shape, and can be variously modified. At this time, it is preferable that the angle of the convex corner is 90 degrees or less in at least a part of the ridgeline forming the cross section of the shock absorbing member.

1 is a perspective view (including a partial cross section) illustrating an embodiment of an impact absorbing member according to the present invention. It is a cross-sectional view of the impact absorbing member shown in FIG. It is a graph which shows an example of the load characteristic of an impact-absorbing member. It is a graph which shows the other example of the load characteristic of an impact-absorbing member. It is a figure which shows the evaluation method of the breaking load when changing the bending angle of the board | plate material of a cross-sectional mountain shape. It is a graph which shows the result of having evaluated the fracture load by the evaluation method shown in FIG. FIG. 6 is a perspective view (including a partial cross section) showing a modification of the shock absorbing member shown in FIG. 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Shock absorption member, 3 ... Edge line, 3a ... Outer side, 3b ... Inner side, 4 ... Convex-shaped corner, 11 ... Impact absorption member, 13 ... Edge line, 13a ... Outer side, 13b ... Inner side, 14 ... Convex Corner.

Claims (3)

In the shock absorbing member to absorb the impact load generated at the time of collision,
It has a member cross section formed in an uneven shape,
Wherein with ridge forming the member cross-section is formed on all straight, have all substantially equal Kuna' length of each side of the ridge,
The impact absorbing member, wherein all the angles of the convex corners of the ridge line are acute angles . 2. The impact absorbing member according to claim 1, wherein the member cross section is formed in an uneven shape throughout . The impact absorbing member according to claim 1 or 2, wherein the shape of the member cross section is a star shape .

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