JP2010030529A - Impact absorber and vehicular bumper device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact absorber and a vehicular bumper device capable of efficiently absorbing impact energy while suppressing an increase in mass. <P>SOLUTION: A crash box 13 has a cylindrical small diameter part 21 and a cylindrical large diameter part 23 which is expanded and connected to the small diameter part 21 via an annular stepped part 22. The impact energy is absorbed by absorbing the applied load through the plastic deformation in the mode in which the small diameter part 21 is folded back into the large diameter part 23 with the annular stepped part 22 as a starting point. A projecting part 26 projecting outwardly in the radial direction over the total length in the axial direction is provided on the small diameter part 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an impact absorber and a vehicle bumper device.

2. Description of the Related Art Conventionally, shock absorbers that absorb impact energy by absorbing an applied load in an axial direction by plastic deformation (so-called turning deformation) have been proposed. For example, Patent Document 1 describes an impact absorbing device including a metal tube in which a small diameter portion (2a) and a large diameter portion (2b) are continuous via a tapered portion (3). Further, in Patent Document 2, a small pipe body (2) having a different outer diameter, in which a straight pipe that can be plastically processed is partially reduced or expanded, and intermediate edges facing each other are connected by an annular stepped portion (4), and An impact absorber consisting of a large tube (3) is described. Further, Patent Document 3 describes a shock absorber made of a continuous polymer material having a small diameter portion (115) and a large diameter portion (114) connected by an intermediate cylinder portion (116).
Japanese Patent Laying-Open No. 2006-8088 (FIG. 1) Japanese Patent Laying-Open No. 2003-327062 (FIG. 1) Japanese translation of PCT publication No. 2008-512627 (FIG. 25A)

  By the way, in Patent Documents 1 and 3, in order to absorb a larger impact energy at the time of turning deformation, it is required to simply increase the thickness of the plate, so that an increase in mass and an increase in material consumption are forced. . On the other hand, in Patent Document 2, it is described that a larger impact energy is absorbed at the time of turning deformation by partial contraction or expansion, but the load at that time gradually changes or changes stepwise. The impact energy absorption is still estimated to be inefficient. Moreover, it is estimated that the diameter reduction part etc. which concerns on the turning of a turning deformation | transformation are exhibiting complicated shapes, and the manufacture is forced into difficulty.

  An object of the present invention is to provide an impact absorber and a vehicle bumper device that can absorb impact energy more efficiently while suppressing an increase in mass.

  In order to solve the above problems, the invention according to claim 1 includes a cylindrical small-diameter portion and a cylindrical large-diameter portion that is expanded and connected to the small-diameter portion via an annular step portion. In the shock absorber that absorbs impact energy by absorbing the applied load by plastic deformation in a manner in which the small diameter portion is folded back into the large diameter portion starting from the annular stepped portion, the small diameter portion has a full axial length. The gist of the present invention is to provide a protrusion protruding radially outward.

  According to the same configuration, when absorbing the impact energy, when the small diameter portion is folded back into the large diameter portion, the folded portion of the small diameter portion and the protrusions facing each other in the radial direction are in pressure contact with each other. Resistance force consisting of frictional force is born. At the same time, the load to be absorbed is increased by the amount of deformation of the protrusion in the folded portion. For this reason, a stable load raised by a substantially constant amount over the entire section of plastic deformation can be absorbed, and impact energy can be absorbed more efficiently. Moreover, since the load absorbed at the time of plastic deformation is increased by the increase, the plate thickness and the axial length of the shock absorber can be shortened accordingly, and the weight can be further reduced.

The gist of the invention according to claim 2 is that, in the shock absorber according to claim 1, a plurality of the protrusions are arranged at equiangular intervals on the small diameter portion.
According to the same configuration, during plastic deformation, a resistance force or the like including a frictional force generated by pressing the protruding portions facing each other in the radial direction of the folded portion of the small diameter portion and the remaining portion is applied to the shock absorber. Acts equally on equiangular intervals. Therefore, for example, it is possible to avoid the fact that a resistance force or the like biased to a predetermined angular position acts on the shock absorber and facilitates the lateral fall of the shock absorber.

  According to a third aspect of the present invention, in the shock absorber according to the first or second aspect, an attachment portion for attaching to an attachment object is provided at the distal end portion of the small diameter portion and the distal end portion of the large diameter portion. The gist is that they are integrally formed.

  According to this configuration, when attaching the shock absorber to the mounting object, there is no need to separately attach a mounting plate (bracket) to each end of the shock absorber by welding or the like. Can be reduced.

  According to a fourth aspect of the present invention, a pair of bumper in hoses extending in the width direction of the vehicle is interposed between the bumper in hoses and the pair of side members extending in the front-rear direction of the vehicle. The vehicle bumper device provided with the crash box is characterized in that the impact absorber for vehicle according to any one of claims 1 to 3 is provided as the crash box.

According to this configuration, it is possible to provide a vehicle bumper device including a crash box that can absorb impact energy more efficiently while suppressing an increase in mass.
According to a fifth aspect of the present invention, in the vehicle bumper device according to the fourth aspect, the bumper inhose is attached to the front end of the small-diameter portion by closing the front end of the small diameter portion, and extends in the vehicle width direction. A main body wall and a pair of opposing walls that are bent toward the large diameter portion in the vehicle front-rear direction continuously to the upper end and the lower end of the main body wall portion and sandwich the large diameter portion during plastic deformation of the crash box And having a part.

  According to the same configuration, when the crash box is plastically deformed, the large diameter portion is supported by being sandwiched between the pair of opposing wall portions, and the crash box (large diameter portion) is prevented from falling, The plastic deformation of the crash box can be performed stably.

  According to the present invention, it is possible to provide an impact absorber and a vehicle bumper device capable of more efficiently absorbing impact energy while suppressing an increase in mass.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a vehicle bumper device according to this embodiment applied to a front portion of a vehicle such as an automobile, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. Since this vehicular bumper device is symmetric (left-right symmetric) in the vehicle width direction, the structure on one side (right half toward the front of the vehicle) is omitted.

  As shown in the figure, on both sides in the vehicle width direction, a pair of side members 11 made of, for example, a metal plate and having a hollow structure with a substantially square cross section and extending in the vehicle front-rear direction are disposed. These side members 11 constitute a part of the body. A bracket 12 as a substantially rectangular attachment object made of, for example, a metal plate is fixed to the front end of each side member 11 by welding in such a manner as to close the opening of the side member 11.

  The vehicular bumper device includes, for example, a crash box 13 that is made of an extruded material of an aluminum alloy, extends in the vehicle front-rear direction, and is attached to the front surface of each bracket 12 as an impact absorber. Each crush box 13 is integrally provided with a cylindrical small-diameter portion 21 and a cylindrical large-diameter portion 23 that is expanded and connected to the small-diameter portion 21 via a tapered annular step portion 22. The center line of the vehicle front-rear direction is arranged so as to coincide with the center line of the side member 11 in the vehicle front-rear direction. The small diameter portion 21 and the large diameter portion 23 have an outer diameter R1 and an outer diameter R2 (> R1), respectively, and are arranged on concentric circles. Further, the half length (= L1 / 2) of the axial length L1 of the small diameter portion 21 is set longer than the axial length L2 of the large diameter portion 23 (L1 / 2> L2). . At the front end of the small-diameter portion 21, a plurality (for example, two) of plate-like shapes extending outward in the radial direction at predetermined angular positions (for example, two angular positions on both sides in the vehicle width direction in the present embodiment). The mounting portion 24 is integrally formed. In addition, at the rear end of the large diameter portion 23, a plurality of (for example, two) plates extending radially outward at predetermined angular positions (for example, two angular positions on both sides in the vehicle width direction in the present embodiment). A mounting portion 25 is integrally formed. Each crash box 13 is fixed to the bracket 12 by tightening a nut to a threaded portion of the bolt B1 that penetrates the bracket 12 together with the mounting portion 25.

  The vehicle bumper device is made of, for example, a metal plate, extends in the vehicle width direction, and is attached to the front ends of the crash boxes 13 at both ends in the vehicle width direction as bumpy ins as attachment objects. A hose 16 is provided. The bumper-in hose 16 has a long main body wall 31 that extends in the vehicle width direction and has a width in the vehicle vertical direction that is larger than the outer diameter R2 of the large-diameter portion 23, and the main body. It has a pair of opposing wall parts 32 and 33 bent to the said large diameter part 23 side in the front-back direction of a vehicle continuously at the upper end and lower end of the wall part 31, respectively. That is, the main body wall 31 has a substantially U-shaped constant cross-sectional shape (open cross-sectional shape) opened to the crash box 13 side. And the front-end | tip of the opposing wall parts 32 and 33 is bent by the upper side and the lower side, respectively, and forms the flanges 32a and 33a. The bumper-in hose 16 closes the front end of the small-diameter portion 21 at the vehicle vertical direction center portion of the main body wall portion 31, and the main body wall portion 31 also has a nut on the screw portion of the bolt B <b> 2 that penetrates the plurality of attachment portions 25. Is fixed to the mounting portion 25 (crash box 13).

  3A is a perspective view showing the crash box 13, and FIGS. 3B and 3C are cross-sectional views taken along lines BB and CC in FIG. As shown in the figure, the small diameter portion 21 of the crash box 13 has a cylindrical shape at predetermined angular positions (for example, four angular positions on both sides in the vehicle width direction and both sides in the vehicle vertical direction in this embodiment). A plurality of (for example, four) protrusions 26 are provided that are formed in such a manner that the inner peripheral surface and the outer peripheral surface protrude in an arc shape radially outward. Each protrusion 26 extends over the entire axial length of the small diameter portion 21. On the other hand, the circumferential length (circumferential length) of the large-diameter portion 23 having a cylindrical shape is equal to the circumferential length of the small-diameter portion 21 including the protrusion 26.

  Next, the operation of this embodiment will be described. When an impact is applied from the front due to a vehicle collision or the like, the impact is transmitted to both side members 11 (body) via the bumper inn hose 16 and both crash boxes 13. At this time, both the crash boxes 13 together with the bumper inhose 16 are plastically deformed, so that the shock transmitted to the body and the occupant is buffered.

  At this time, as shown in FIGS. 4 (a) and 4 (b), each crush box 13 has an applied load (axial compression load) as a starting point of the annular step portion 22 and a small diameter portion 21 in the large diameter portion 23. The impact energy is absorbed by absorbing plastic deformation (so-called turning deformation). That is, the annular step portion 22 forms a stress concentration portion that becomes a starting point of turning deformation, and the large diameter portion 23 forms a space S that allows the small diameter portion 21 to be folded back in the axial direction. To do. At this time, of the entire protrusion 26, the protrusion 26a in the folded portion 21a of the small-diameter portion 21 and the protrusion 26b in the remaining portion 21b are opposed to each other in the radial direction and a resistance force including a frictional force is generated. . At the same time, the load to be absorbed is increased by the deformation of the protrusion 26 (26a) in the folded portion 21a. As described above, the crash box 13 absorbs larger impact energy with the turning deformation. Note that the above-described relationship between the lengths L1 and L2 (L1 / 2> L2) takes into account the remaining deformation of the turning deformation.

  When the crash box 13 is turned, the bumper inhose 16 sandwiches the large-diameter portion 23 between the opposing wall portions 32 and 33. Thereby, it is supported by both opposing wall parts 32 and 33 at the time of turning deformation of the crash box 13, and the fall of the crash box 13 (large diameter part 23) is suppressed. In addition, at the time of turning deformation of the crash box 13, the bumper rein hose 16 is prevented from interfering with the crash box 13 by accommodating the crash box 13 (large diameter portion 23) between the opposing wall portions 32 and 33. The

  FIG. 5 is a graph showing the transition of the load with respect to the deformation amount (stroke) in the single crash box 13 when absorbing the impact energy. In the figure, the transition of a conventional crash box having the same structure except that it includes a cylindrical small-diameter portion that omits the protrusion 26 is also drawn with a broken line. As is clear from the figure, even in the conventional crash box, the impact energy is absorbed with the load stabilized in accordance with the turning deformation. The crash box 13 of the present embodiment absorbs a stable load raised by a substantially constant amount over the entire section of the turning deformation (plastic deformation) with respect to the conventional crash box, making the impact energy more efficient. It can be confirmed that it can be absorbed. The inventor has confirmed that the increased load corresponds to about 20% of the conventional load. It goes without saying that this stable load absorption is continued until there is no remaining crush on the front side of the large-diameter portion 23 (annular stepped portion 22), that is, until the deformation amount reaches the length L1.

  Next, the manufacturing method of the crash box 13 of this embodiment is demonstrated. As shown in FIGS. 6 (a) and 6 (b), the material W of the crash box 13 is formed by extrusion molding of an aluminum alloy and has a constant cross-sectional shape equivalent to the small diameter portion 21 provided with the protrusions 26 (FIG. 3 (b)). A plurality of projecting pieces Wa that are relatively protruded by intermittently cutting out the front end portion thereof at equal angular intervals (for example, 180 ° intervals in the present embodiment). On the other hand, a plurality of (for example, two) projecting pieces Wb that are relatively projected by intermittently notching the rear end portion are provided at equiangular intervals (for example, 180 ° intervals in this embodiment). ) Prepare.

  And this raw material W is penetrated by the cyclic | annular 1st metal mold | die M1 according to the range RA of the axial direction processed into the annular level | step-difference part 22 and the large diameter part 23. FIG. The first mold M1 has inner peripheral surfaces equivalent to the outer peripheral surfaces of the annular step portion 22 and the large diameter portion 23, and the material W is disposed and supported so as to be concentric with the first mold M1. Is done.

  Then, as shown in FIG. 4 (b), with respect to the material W arranged in this manner, a truncated cone-shaped second having an outer peripheral surface equivalent to the inner peripheral surface of the annular step portion 22 and the large diameter portion 23, respectively. Two molds M2 are press-fitted concentrically. Thereby, the annular stepped portion 22 and the large diameter portion 23 are easily formed in a manner in which the portion corresponding to the protrusion 26 of the material W is expanded.

  The second mold M2 is provided with an outer flange F in accordance with the rear end of the large-diameter portion 23, and the projecting piece is pressed by pressing the projecting piece Wb with the outer flange F during press-fitting into the material W. Wb is bent radially outward to form the mounting portion 25 simultaneously. Similarly, the mounting portion 24 is formed by pressing the protruding piece Wa with a mold (not shown).

As described above in detail, according to the present embodiment, the following effects can be obtained.
(1) In this embodiment, when impact energy is absorbed by the crash box 13, when the small diameter portion 21 is folded back into the large diameter portion 23, the folded portion 21a and the remaining portion 21b of the small diameter portion 21 face each other in the radial direction. When the protrusions 26a and 26b are in pressure contact with each other, a resistance force including a frictional force is generated. At the same time, the load to be absorbed is increased by the deformation of the protrusion 26 (26a) in the folded portion 21a. For this reason, a stable load raised by a substantially constant amount over the entire section of plastic deformation can be absorbed, and impact energy can be absorbed more efficiently. Moreover, since the load absorbed at the time of plastic deformation of the crash box 13 is increased by an increase, the plate thickness and the axial length of the crash box 13 can be reduced accordingly, and the weight can be further reduced. . In particular, when the axial length of the crash box 13 is shortened, the overall length of the vehicle can be shortened.

  (2) In the present embodiment, the plurality of protrusions 26 are arranged at equal angular intervals on the small diameter portion 21, so that at the time of plastic deformation, in the radial direction of the folded portion 21 a and the remaining portion 21 b of the small diameter portion 21. A resistance force or the like, which is a frictional force generated when the protruding portions 26 a and 26 b facing each other are pressed against each other, acts on the crash box 13 at equal angular intervals. Therefore, for example, it is possible to avoid the side wall of the crash box 13 from being promoted by a resistance force or the like biased to a predetermined angular position with respect to the crash box 13.

  (3) In this embodiment, the attachment parts 24 and 25 for attaching to an attachment target object (bumper-in hose 16 or bracket 12) are attached to the front end part of the small diameter part 21 and the rear end part of the large diameter part 23. Since they are integrally formed, it is not necessary to separately attach a mounting plate (bracket) to the front end portion and the rear end portion of the crash box 13 by welding or the like. For this reason, the number of parts can be reduced, and the cost can be reduced.

  (4) In the present embodiment, it is possible to provide a vehicle bumper device including a crash box 13 that can absorb impact energy more efficiently while suppressing an increase in mass.

  (5) In this embodiment, when the crush box 13 is plastically deformed, the crush box 13 (large diameter portion 23) falls down because the large diameter portion 23 is sandwiched between the pair of opposing wall portions 32 and 33. Thus, the plastic deformation of the crash box 13 can be performed smoothly and stably. Further, when the crash box 13 is plastically deformed, the bumper-in hose 16 suppresses interference with the crash box 13 by accommodating the crash box 13 (large diameter portion 23) between the opposing wall portions 32 and 33. Thus, the deformable amount (stroke) of the crash box 13 can be used effectively.

  (6) In the present embodiment, the annular stepped portion 22 and the large diameter portion 23 of the crash box 13 can be easily formed in such a manner that the portion corresponding to the protrusion 26 of the material W made of the extruded material is expanded. Further, the material W having a hollow structure can be easily manufactured by extrusion molding, and the material W (crash box 13) can be easily designed and deformed only by changing the extrusion mold.

In addition, you may change the said embodiment as follows.
In the embodiment, a blind nut may be adopted instead of any of the bolts B1 and B2 related to fastening of each member and the nut combined with the bolt. In this case, unlike the combination of bolts and nuts, it is not necessary to set the mounting direction in two directions, and the mounting direction may be only one direction, so that the mounting performance can be improved.

  In the embodiment, the bumper-in hose 16 may be formed of a light metal extruded material such as an aluminum alloy. In this case, the cross-sectional shape of the bumper inhose may be a mouth shape, a date shape, an eye shape, a rice field shape, or the like.

  In the above-described embodiment, the crash box 13 that is plastically deformed by the opposing wall portions 32 and 33 is supported above and below, but instead of or in addition to this, for example, a pair of juxtaposed in the vehicle width direction. You may change so that the crush box 13 which plastically deforms may be supported by right and left with an opposing wall part.

In the embodiment described above, the plurality of protrusions 26 may not be arranged at equiangular intervals on the small diameter portion 21. Further, the number of the protrusions 26 may be 3 or less or 5 or more.
In the embodiment, the crash box 13 may be manufactured by pressing a metal plate (steel plate) or a metal pipe (iron pipe).

-In the said embodiment, the cylindrical shape of the small diameter part 21 or the large diameter part 23 is a concept containing the cylindrical shape (elliptical cylinder shape, flat cylindrical shape) which has some flatness.
The shock absorber according to the present invention may be applied to other shock absorbing frames such as the side member 11.

The present invention may be applied to the rear portion of the vehicle.
Even if the large-diameter portion 23 of the crash box 13 is provided with a projecting portion formed in such a manner that the cylindrical inner peripheral surface and the outer peripheral surface are formed in an arc shape radially inward at the predetermined angular position, the plastic deformation It is thought that sometimes the same resistance force is born and efficient absorption of impact energy becomes possible. However, in this case, when the large-diameter portion 23 is formed by expanding the material W made of the extruded material, it is difficult to control the protrusion length of the protrusion, which is not practical in terms of quality control.

The top view which shows one Embodiment of this invention. Sectional drawing along the AA line of FIG. (A) is a perspective view which shows a crush box, (b) (c) is sectional drawing along the BB line and CC line of FIG. (A) (b) is sectional drawing which shows operation | movement of the embodiment. The graph which shows the relationship between the deformation of the same embodiment, and a load. (A) (b) is a schematic diagram which shows the manufacture aspect of the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Side member, 13 ... Crash box (shock absorber), 16 ... Bumper inhose, 21 ... Small diameter part, 22 ... Annular level | step-difference part, 23 ... Large diameter part, 24, 25 ... Mounting part, 26, 26a, 26b ... projecting portion, 31 ... main body wall portion, 32, 33 ... opposing wall portion.

Claims (5)

A cylindrical small-diameter portion and a cylindrical large-diameter portion that is expanded and connected to the small-diameter portion via an annular step portion, and the applied load starts from the annular step portion and the small-diameter portion is the large-diameter portion. In the shock absorber that absorbs the impact energy by absorbing the plastic deformation in the form of folding back into the diameter part,
A shock absorber, wherein the small-diameter portion is provided with a protrusion protruding outward in the radial direction over the entire axial length. The shock absorber according to claim 1, wherein
A plurality of the protrusions are arranged at equiangular intervals on the small diameter portion. The shock absorber according to claim 1 or 2,
An impact absorber, wherein an attachment portion for attaching to an attachment object is integrally formed at the distal end portion of the small diameter portion and the distal end portion of the large diameter portion. Bumper device for vehicle comprising a pair of crash boxes respectively interposed between the bumper inhose and a pair of side members extending in the front-rear direction of the vehicle at both ends of the bumper inhose extending in the width direction of the vehicle In
A vehicular bumper device comprising the vehicular shock absorber according to any one of claims 1 to 3 as the crash box. The vehicle bumper device according to claim 4,
The bumper in horse is
A main body wall portion which is attached to the front end by closing the front end of the small diameter portion and extending in the width direction of the vehicle;
A pair of opposing wall portions that are bent toward the large-diameter portion in the longitudinal direction of the vehicle continuously to the upper end and the lower end of the main body wall portion and sandwich the large-diameter portion when the crash box is plastically deformed. A bumper device for vehicles.

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