JP2006347265A - Vehicular impact absorbing member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular impact absorbing member capable of making F-S characteristic close to the characteristic of a rectangular shape which is ideal characteristic. <P>SOLUTION: A notch portion 38 is formed at a rear end portion (a part having strong cross section binding force) of a middle rib 23 of a crash box 10 of a flange portion 30 formed in an 8-shape in front view. Therefore, load durability in shaft compressing second half is reduced, and the reminder of crushing can be eliminated. Consequently, the F-S characteristic can be made close to the ideal rectangular characteristic. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shock absorbing member for a vehicle, which is interposed between a load input portion to which a collision load is input and a load transmission portion to which the collision load is transmitted and absorbs energy at the time of collision by compressing and deforming in an axial direction. About.

  Conventionally, a crash box as an impact absorbing member has been set between a front end portion of a front side member and a front bumper reinforcement.

  This type of crash box has a cylindrical crash box main body, a body side mounting bracket that is fixed to the rear end of the crash box main body and is used as a mounting portion to the body, and a front end of the crash box main body. It is often configured by three parts of a bumper reinforcement side mounting bracket that is fixed and used as a mounting portion to the front bumper reinforcement.

  However, if the crash box is composed of three parts, the number of parts increases and the number of assembling steps also increases. Therefore, either the front or rear mounting bracket is integrally formed on the crash box main body. Further, in order to further reduce the number of parts, there is also one in which a crash box is configured by one part by deep drawing a steel plate (see Patent Documents 1 and 2 below).

  Briefly explaining the structures disclosed in these patent documents, the entire crash box is formed into a cross-sectional hat shape by deep drawing of a steel plate. A weld nut is fixed in advance to the bottom (front end) of the crash box serving as a closed end, and is fixed to the front bumper reinforcement by bolt fastening. Further, a flange portion is integrally formed at the rear end portion of the crash box serving as an open end, and the flange portion is fixed to the front end portion of the front side member by bolt fastening.

Further, in the above crash box, a folded portion is set between the crash box main body portion and the flange portion, and the folded portion is fitted into the front end portion of the crash box so as to be attached, and the crash box main body at the time of a frontal collision. The rear end of each part is pushed inwardly of the front end of the front side member while being part of the folded portion.
JP 2003-312400 A Japanese Patent Laid-Open No. 2003-312401

  However, in the shaft compression member with a flange as described above, the restraining force of the cross section of the shaft compression member increases as the position near the flange portion. For this reason, even if the longitudinal cross-sectional shape of the axial compression member is the same in the entire region in the longitudinal direction, the proof stress increases in the latter half of the compression in which the compression portion is in the vicinity of the flange portion. As a result, the FS characteristic is not an ideal rectangular characteristic (that is, a characteristic in which the proof stress is constant over the entire compression range), and there is a problem that the load increases in the latter half of the compression.

  Further, since the yield strength of the shaft compression member in the latter half of the shaft compression increases, the yield strength in the latter half of the shaft compression exceeds the body strength on the rear end side of the shaft compression member, and a crushing residue is generated. As a result, there exists a problem that the energy absorption efficiency of a shaft compression member falls.

  An object of the present invention is to obtain a shock absorbing member for a vehicle that can bring the FS characteristic closer to a rectangular characteristic that is an ideal characteristic in consideration of the above facts.

  The impact absorbing member for a vehicle according to the first aspect of the present invention is interposed between a load input portion to which a collision load is input and a load transmission portion to which the collision load is transmitted, and is compressed and deformed in the axial direction. A shock absorbing member for a vehicle that absorbs energy at the time of a collision, wherein the shock absorbing member is integrally provided with the main body portion that is compressively deformed in the axial direction when a collision load is input, and the load transmitting portion. It is configured as a vehicle body skeleton member including a flange portion provided for attachment to the body, and the main body portion partially weakens the cross section near the flange portion having a strong cross-sectional binding force that deforms in the latter half of the axial compression. It is characterized by that.

  According to a second aspect of the present invention, there is provided a shock absorbing member for a vehicle according to the first aspect of the present invention, wherein the main body of the shock absorbing member is formed by forging.

  According to the first aspect of the present invention, when a collision occurs, the collision load is input to the load input unit. The input collision load is transmitted to the load transmission unit via the impact absorbing member. At this time, the main body portion of the impact absorbing member is compressed and deformed in the axial direction, so that energy at the time of collision is absorbed.

  Here, in this invention, since the flange part provided for attachment to a load transmission part is integrally provided in the main-body part of the impact-absorbing member, it is close to the flange part which deform | transforms into the latter half of axial compression in a main-body part. The cross-section restraining force becomes stronger as the portion becomes larger. Therefore, although the part near the flange part in the main body part is difficult to be crushed, in the present invention, the part where the cross-sectional restraining force in the main body part becomes strong is partially weakened, so the yield strength in the latter half of the axial compression is moderately reduced. The crushing residue can be reduced (the crushing rate can be improved).

  According to the second aspect of the present invention, since the main body portion of the impact absorbing member is formed by forging, the fragile portion can be reduced by reducing the material input amount or deliberately reducing the press capacity. It can be made simultaneously in the molding process. That is, post-processing for setting the fragile portion is unnecessary, and thus productivity is improved.

  In addition, the advantage that the amount of material input can be reduced and the pressing ability can be reduced also brings a production advantage that the impact absorbing member can be easily manufactured by forging.

  As described above, the impact absorbing member for a vehicle according to claim 1 is provided with a main body portion that is compressively deformed in the axial direction when a collision load is input, and is provided integrally with the main body portion and is attached to the load transmitting portion. And a flange portion provided to the body, and the cross section in the vicinity of the flange portion having a strong cross-sectional binding force that deforms in the latter half of the axial compression in the main body portion is partially weakened. It is possible to reduce the crushed residue (improve the crush rate) by moderately reducing the yield strength at the end, and as a result, it is possible to bring the FS characteristics closer to the ideal rectangular characteristics It has the effect.

  The impact absorbing member for a vehicle according to the second aspect of the present invention is the invention according to the first aspect, wherein the body portion of the impact absorbing member is formed by forging, so that the fragile portion can be simultaneously formed in the molding process. As a result, it has an excellent effect that productivity and yield can be improved.

  Hereinafter, an embodiment of an impact absorbing member for a vehicle according to the present invention will be described with reference to FIGS. It should be noted that an arrow FR appropriately shown in these drawings indicates a vehicle front side, an arrow UP indicates a vehicle upper side, an arrow IN indicates a vehicle width direction inner side, and an arrow OUT indicates a vehicle width direction outer side. Is shown.

  FIG. 6 is a plan view of the front portion of the vehicle body in which the crash box 10 as an impact absorbing member according to the present embodiment is employed. As shown in this figure, a long front bumper reinforcement 12 as a load input portion formed in a substantially U shape in plan view is disposed at the front end portion of the vehicle body in the vehicle width direction in the longitudinal direction. Has been. The front bumper reinforcement 12 is a high-strength member, and a front bumper cover (not shown) is attached to the front side thereof.

  On the other hand, inside the front wheel house 16 where the front wheels 14 are arranged, a high-strength front side member 18 as a load transmitting portion formed in a long shape is arranged with the vehicle longitudinal direction as the longitudinal direction. The rear end portion of the front side member 18 is coupled to the front surface of the front cross member 20. Further, the front end portion of the front side member 18 is disposed at a position (offset position) separated from the front bumper reinforcement 12 by a predetermined distance toward the vehicle rear side. A long crash box 10 is interposed between the front end portion of the front side member 18 and the rear end surface of the front bumper reinforcement 12. The crash box 10 is continuously arranged in the vehicle front-rear direction with respect to the front side member 18.

  FIG. 1 is an overall perspective view of the crash box 10. 2 to 5 are sectional views of the crash box 10 as appropriate.

  As shown in these drawings, in the crash box 10 of the present embodiment, the upper and lower upper cylindrical portions 22 and 24 are arranged in parallel in the direction perpendicular to the axis (the vehicle vertical direction). It is comprised as a composite of a cylindrical part. As shown in FIGS. 2 and 3, the upper cylindrical portion 22 and the lower cylindrical portion 24 are each formed in a regular octagon, and share high energy absorption performance as a whole by sharing the bottom wall and the top wall. It is formed in the shape of the substantially 8 character which exhibits.

  Further, the left and right upper walls 22A and side walls 22C of the upper cylindrical portion 22 and the left and right lower walls 24A and side walls 24C of the lower cylindrical portion 24 have beads (for identifying compression buckling starting points). (Fragile portions) 26 are formed at predetermined intervals. The beads 26 formed on the upper wall 22A and the beads 26 formed on the side wall 22C are alternately arranged. Similarly, the beads 26 formed on the lower wall 24C and the beads 26 formed on the side wall 24C are alternately arranged.

  One end portion (front end portion) of the crash box 10 in the axial direction is closed and serves as a bottom portion 28 coupled to the front bumper reinforcement 12. In addition, the front end surface (front end surface) of the bottom portion 28 is an inclined surface having a predetermined angle according to the curved shape of the front bumper reinforcement 12 (see FIG. 5). On the other hand, the other end portion (rear end portion) in the axial direction of the crash box 10 is open, and a rectangular flat plate flange portion 30 coupled to the front end portion of the front side member 18 is integrally formed around the periphery. . Bolt insertion holes 32 are formed at the four corners of the flange portion 30. The plate thickness of the flange portion 30 is set to be thicker than the plate thicknesses of the upper cylindrical portion 22 and the lower cylindrical portion 24 in order to ensure the coupling rigidity to the front end portion of the front side member 18.

  The bottom portion 28 of the crush box 10 described above has a pair of vertically long thick portions 28A formed in a substantially 8-shape and a pair of left and right sides of the middle portion in the height direction of the thick portion 28A. And the thin portion 28B.

  The thin-walled portion 28B includes three parts: a lower wall 22B of the upper cylindrical portion 22, an upper wall 24B of the lower cylindrical portion 24, and an intermediate rib (shared wall) 23 of the upper cylindrical portion 22 and the lower cylindrical portion 24. It is set to the range surrounding the part where the walls intersect. On the other hand, the thick portion 28 </ b> A is set in a range obtained by removing the pair of left and right thin portions 28 </ b> B from the 8-shaped outer shape of the crash box 10. A step 34 is formed between the thick portion 28A and the thin portion 28B, and the height of the step 34 is set to a predetermined height (about several millimeters) corresponding to the stroke at which the peak load at the initial stage of the collision occurs. Has been.

  Furthermore, the upper and lower four portions of the thick portion 28A (two locations on the middle side of the upper cylindrical portion 22 and two locations on the middle side of the lower cylindrical portion 24) are attachment portions to the front bumper reinforcement 12. A mounting hole 36 is formed. A female screw is formed on the inner peripheral surface of the mounting hole 36, and a bolt (not shown) is screwed from the front bumper reinforcement 12 side. Note that the fastening direction to the front bumper reinforcement 12 side of the crash box 10 and the fastening direction to the front end portion side of the front side member 18 are both the vehicle front-rear direction.

  Here, as shown in FIG. 1 and FIGS. 3 to 5, in the vicinity of the flange portion 30 of the middle rib 23 that separates the upper cylindrical portion 22 and the lower cylindrical portion 24 of the crash box 10 described above ( At the rear end portion of the middle rib 23, a cutout portion 38 is formed as a rectangular weak portion in plan view. By forming this notch portion 38, the vicinity of the flange portion 30 of the upper cylindrical portion 22 and the lower cylindrical portion 24 which are the main body portions is weakened.

  Further, the crash box 10 having the above-described configuration is constituted by one part and is manufactured by forging an aluminum alloy. Schematically, the crash box 10 is manufactured by forging an aluminum alloy utilizing (combining) two steps of a front extrusion method and a rear extrusion method.

(Action / Effect)
Next, the operation and effect of this embodiment will be described.

  The crash box 10 according to the present embodiment is assembled between the front bumper reinforcement 12 and the front end portion of the front side member 18. When this vehicle collides head-on, the collision load at that time is input to the front bumper reinforcement 12. The input collision load is transmitted to the front side member 18 via the crash box 10. At this time, the upper cylindrical portion 22 and the lower cylindrical portion 24 of the crash box 10 are compressed in the axial direction and sequentially deformed (collapsed) in a bellows shape starting from each bead 26, whereby predetermined energy absorption is performed. The

  Here, in the crash box 10 according to the present embodiment, the rectangular plate-like flange portion 30 is integrally formed at the rear end portions of the upper cylindrical portion 22 and the lower cylindrical portion 24, and the flange portion 30 is used as the load transmitting portion. Since it is attached to the front end portion of the front side member 20, the cross-section restraining force becomes stronger in the upper cylindrical portion 22 and the lower cylindrical portion 24 closer to the flange portion 30 that is deformed in the latter half of the axial compression. Therefore, although the site | part of the vicinity of the flange part 30 in the upper side cylindrical part 22 and the lower side cylindrical part 24 becomes difficult to be crushed, in the crash box 10 which concerns on this embodiment, the upper side cylindrical part 22 and the lower side cylindrical part 24 are used. Since the notch portion 38 is provided at the rear end portion of the middle rib 23 in which the cross-sectional restraining force becomes strong, the yield strength in the latter half of the axial compression can be appropriately reduced, and the remaining crushing can be reduced (the crushing rate can be improved). . As a result, according to the present embodiment, the amount of energy absorption in the latter half of the axial compression is increased, and the FS characteristic can be brought close to a rectangular characteristic which is an ideal characteristic.

  In the present embodiment, since the crush box 10 is formed by forging, the notch 38 can be simultaneously formed in the molding process by reducing the amount of material input or deliberately reducing the press capacity. it can. That is, post-processing for setting the notch 38 is not necessary, and productivity is improved. Furthermore, the advantage that the amount of material input can be reduced or the press capacity can be reduced also brings a production advantage that the crash box 10 can be easily manufactured by forging. As a result, according to this embodiment, productivity and yield can be improved.

[Supplementary explanation of the embodiment]
In the above-described embodiment, the crash box 10 has been described as an example of the impact absorbing member of the vehicle. However, the present invention is not limited to this, and the compressive plastic deformation is sequentially performed from the end on the load input side in response to an axial compression load at the time of collision. Accordingly, any body frame member (shaft compression member) in which the cross-sectional restraining force in the latter half of the shaft compression becomes strong can be applied. For example, the present invention may be applied to a case where the front end portion of the front side member is directly subjected to axial compression plastic deformation without setting a crash box.

  Moreover, in this embodiment mentioned above, although the notch part 38 was set as a weak part, it is not restricted to this, What is necessary is just a structure which can suppress the load increase in the second half of axial compression, for example, a thin part is set. You may take the structure to do.

  Further, in the above-described embodiment, the notch 38 is set at the rear end of the middle rib 23. However, since there is a weld by arc welding, spot welding or the like as an element that increases the cross-sectional restraining force, the weld Is set at a position corresponding to the latter half of the axial compression, the same effect can be obtained by setting a weak part such as the notch 38 near the welded part.

  Moreover, in this embodiment mentioned above, although the crash box 10 was manufactured by the forging shaping | molding of aluminum alloy, you may manufacture a crash box not only by this but by extrusion molding. In this case, the notch (fragile part) is set by cutting as a post process.

  Further, in the present embodiment described above, the crash box 10 is made of an aluminum alloy material. However, the present invention is not limited to this, and various materials such as iron, carbon, resin, and glass fiber can be applied.

  Moreover, in this embodiment mentioned above, although the main-body part of the crash box 10 was formed in the substantially 8-character shape which consists of the upper cylindrical part 22 and the lower cylindrical part 24 which are excellent in axial crushing performance, it is not restricted to this, You may form in the shape of a "day". Further, the number of cylindrical portions is not limited to two, and may be three or more.

It is a perspective view which shows the crash box concerning this embodiment alone. FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1 showing a vertical cross-sectional structure (a state cut in the vehicle width direction) of the crash box shown in FIG. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1 showing a vertical cross-sectional structure (a state cut in the vehicle width direction) of the crash box shown in FIG. 1. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 showing a vertical cross-sectional structure (a state cut in the vehicle longitudinal direction) of the crash box shown in FIG. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 1 showing a cross-sectional structure of the crash box shown in FIG. It is a top view which shows the structure of the vehicle body front part by which the crash box which concerns on this embodiment was employ | adopted.

Explanation of symbols

10 Crash box (shock absorbing member)
12 Front bumper reinforcement (load input section)
18 Front side member (load transmission part)
22 Upper cylindrical part (main part)
23 Middle rib 24 Lower cylindrical part (main part)
30 Flange part 38 Notch part (fragile part)

Claims (2)

An impact absorbing member for a vehicle that absorbs energy at the time of collision by being compressed and deformed in an axial direction interposed between a load input portion to which a collision load is input and a load transmission portion to which the collision load is transmitted,
The shock absorbing member includes a body portion that compresses and deforms in the axial direction when a collision load is input, and a flange portion that is provided integrally with the body portion and is used for attachment to the load transmission portion. Configured as a member,
In the main body part, the cross section in the vicinity of the flange part having a strong cross-sectional binding force that deforms in the latter half of the axial compression is partially weakened.
A shock absorbing member for a vehicle characterized by the above. The body portion of the impact absorbing member is formed by forging,
The impact absorbing member for a vehicle according to claim 1.

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