JP2007261557A - Impact absorbing device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact absorbing device capable of sufficiently and efficiently absorbing impact energy in collision of a vehicle. <P>SOLUTION: In the impact absorbing device 1 for the vehicle comprising a cylinder body having a helical stepped part 3 and having a diameter gradually varied in an axial direction, a bottom part 10 is integrally formed on a small diameter end. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an apparatus for absorbing impact energy at the time of a vehicle collision.

  In order to mitigate the impact on the passenger at the time of the vehicle collision, for example, an impact absorbing device (crash box) is interposed between the bumper reinforcement of the vehicle and the body frame (side member), and the impact energy is reduced by the plastic deformation. There is known a technique of absorbing by converting into deformation energy. The present applicant, as an impact absorbing device excellent in impact energy absorption performance, is composed of a cylindrical body having a stepped portion whose diameter gradually changes in the axial direction, and the stepped portion is formed in a spiral shape around the cylindrical body. Japanese Patent Application Laid-Open No. H10-228707 proposes a shock absorbing device.

International Publication Number WO05 / 075254

As shown in FIG. 6, the characteristics required for the shock absorbing device having excellent shock absorbing performance are shown in FIG. 6 without exceeding the proof strength F ₀ of the vehicle body frame in the load characteristic graph with respect to the displacement (the shock absorbing device is more advanced than the vehicle frame). 6), and a diagram in which the load suddenly rises with respect to the initial deformation and maintains a high load with respect to the subsequent increase in displacement, that is, the area of the hatched portion in FIG. It is to increase the amount of absorption.

  The impact absorbing device disclosed in Patent Document 1 can basically satisfy the above characteristics, but as shown in FIG. 9, the ends of the shock absorbing device 70 are open end portions 71 and 72 having no lid (bottom). In this case, before the impact absorbing device begins to plastically deform (crush) in the axial direction at the initial stage when the impact load is applied, as shown in FIG. 10, the opening end 71 itself having relatively low rigidity causes mouth deformation. In some cases, the initial peak in FIG. 6 (I) may drop to the position b.

  Therefore, as a structure capable of suppressing the mouth deformation of the opening end portions 71 and 72, as shown in FIG. 11, a lid member 73 (separate bottom portion) which is a separate member is externally fitted to the opening end portion 71. Patent Document 1 discloses an impact absorbing device 80 fixed by welding. However, in this structure, since the rigidity in the fitting lap portion 74 between the opening end portion 71 and the lid member 73 is high, and the hardness of the weld bead 75 itself is also high, the fitting lap portion 74 and the weld bead 75 are in the axial direction. The dead space 76 is difficult to be plastically deformed, and the deformation stroke is substantially reduced. Although not shown, the same applies to a non-fitting type fixed structure in which a plate-like lid member is brought into contact with and welded to the plate thickness end surface of the opening end portion 71.

  Accordingly, the present invention provides a vehicle impact absorbing device that solves the above problems.

  In order to solve the above-described problem, the invention according to claim 1 is a vehicle impact absorbing device including a cylindrical body having a spiral step portion and a diameter gradually changing in the axial direction. An impact absorbing device for a vehicle, wherein a bottom portion is integrally formed at an end portion.

  According to the first aspect of the present invention, the plastic deformation (collapse) in the axial direction of the shock absorbing device is gradually and continuously progressed spirally from the small diameter side to the large diameter side of the cylindrical body due to the presence of the spiral stepped portion. However, the load diagram with respect to the displacement is a stable diagram with gentle undulations, and the bottom of the shock absorber is formed integrally with the small-diameter end so that the mouth does not deform easily and plastic deformation occurs. It is possible to provide an impact absorbing device for a vehicle having an excellent impact energy absorbing characteristic by efficiently plastically deforming the impact absorbing device without waste without having a difficult dead space.

  The best mode for carrying out the present invention will be described based on the embodiment shown in FIGS.

  1 is a perspective view showing an impact absorbing device of the present invention, FIG. 2 is a longitudinal sectional view taken along line AA in FIG. 1, and FIGS. 3 and 4 are corresponding A showing another embodiment with respect to the embodiment in FIG. FIG. 5 is a perspective view showing another embodiment of the impact absorbing device according to the present invention, FIG. 6 is a characteristic diagram showing experimental results in the impact absorbing device, and FIGS. 7 and 8 are the impact absorbing devices of FIG. It is a figure which shows the example of attachment of an apparatus.

  As shown in FIGS. 1 and 2, the shock absorbing device 1 includes a small-diameter end portion 2 a and a medium-diameter portion whose diameter (width when cut at a plane 5 orthogonal to the shaft 4) gradually changes in the direction of the shaft 4. 2b and a large-diameter portion 2c are coaxial pyramid-shaped cylinders, and a spiral step 3 composed of a single continuous surface is provided around the axis 4 of the cylinder. Are integrally formed. In addition, the helical pitch and the number of strips of the step part 3 are arbitrary.

  And the step part 3 is formed on the inclined surface 6 which has inclination | tilt angle (theta) with respect to the orthogonal surface 5 with respect to the axis | shaft 4 of a cylinder as shown in FIG. 2, ie, is formed in the taper shape. . The inclination angle θ, the height H of the stepped portion 3, and the width W of the stepped portion 3 are arbitrary, and the inclination angle θ, not only in the vertical cross section along the line AA in FIG. The height H and the width W are constant. Alternatively, the inclination angle θ, the height H, and the width W may be continuously increased or decreased from one end 7 to the other end 8 of the step 3 shown in FIG.

  A bottom portion 10 is integrally formed with the small diameter end portion 2a. In the illustrated embodiment, the bottom portion 10 is a flat surface orthogonal to the cylindrical axis 4, but is not limited to this. For example, the bottom portion 10 is an inclined surface according to the shape of the bumper reinforcement that is the attachment object. Alternatively, it may be a dome shape that bulges outward from the cylinder, or may be a shape that is recessed toward the inside of the cylinder. Further, when it is necessary to form a through hole in the bottom 10 for design or manufacturing reasons in the shock absorbing device 1, the through hole may be formed in a range that does not hinder the impact energy absorbing performance. Further, by forming the one end portion 7 of the step portion 3 up to the edge portion 10a of the bottom portion 10, dead space in plastic deformation can be further reduced.

  On the other hand, a flange 11 is integrally formed at the end portion on the large diameter portion 2c side. An attachment hole 12 is formed in the flange 11 and is firmly fixed to the vehicle body frame, which will be described later, by bolts and nuts through the attachment hole 12. Further, by forming the other end portion 8 of the step portion 3 up to the root 11a of the flange 11, a dead space in plastic deformation can be further reduced.

  In the illustrated embodiment, the bottom portion 10 is integrally formed only on the small diameter end portion 2a, but the bottom portion 10 may be integrally formed on the large diameter portion 2c side end portion. That is, it is only necessary that the bottom part is integrally formed with the small diameter end part which is at least the deformation starting point side of the shock absorber.

  In the illustrated embodiment, the shock absorbing device 1 is a quadrangular pyramid-shaped cylinder, but may be another polygonal pyramid, such as a cone as shown in FIG. It may be conical. Alternatively, a cylindrical body whose shape gradually changes from a polygonal pyramid shape to a substantially conical shape from one end portion to the other end portion of the cylindrical body may be used.

  The material of the shock absorber 1 is, for example, Japanese Industrial Standard (JIS) SPH270C, STKM11A, high-tensile steel (commonly known as high-tensile material), or aluminum material for weight reduction. The plate thickness is 2 mm, for example.

  As a manufacturing method of the impact absorbing device 1 having a spiral step portion and a bottom portion integrally formed, for example, a bottomed cylindrical body is formed by a known press deep drawing process using a punch and a die in advance of a metal plate, for example. A method of forming a spiral step by pressing the bottomed cylindrical body in the axial direction using another punch and die, and a spiral by pressing a rolling tool (roll) on the outer periphery of the bottomed cylindrical body There is a method of forming a stepped portion. In addition to these manufacturing methods, it may be manufactured by a known spinning process or a hydraulic bulge process (hydroforming). Note that when the metal plate material is a material that is difficult to process, such as high-strength steel, the workability is improved by performing a heat treatment (annealing, warm pressing, etc.) before or during the processing.

  As another example of the step portion 3, as shown in FIG. 3, a cross-sectional shape including the shaft 14 of the step portion 13 may be formed so as to be orthogonal to the shaft 14. The height H of the stepped portion 13 is arbitrary, and the height H is constant in any longitudinal section including the shaft 14 as well as the section corresponding to the longitudinal section taken along line AA in FIG. Alternatively, the height H may be continuously increased or decreased from one end of the step portion 13 (corresponding to the one end 7 in FIG. 1) to the other end (corresponding to the other end 8 in FIG. 1). Good. According to the present embodiment, the plastic deformation of the stepped portion 13 easily occurs reliably. Also in this embodiment, the bottom 16 is integrally formed at the end of the shock absorbing device.

  As still another embodiment of the stepped portion 3, as shown in FIG. 4, the cross-sectional shape including the shaft 24 of the stepped portion 23 may be formed into a U-shaped folded shape. The height H of the stepped portion 23 and the width W of the stepped portion 23 are arbitrary. The height of the stepped portion 23 is not limited to the cross section corresponding to the vertical section taken along line AA in FIG. The shape is constant. Alternatively, the height H of the step 23 and the width of the step 23 from one end of the step 23 (corresponding to the one end 7 in FIG. 1) to the other end (corresponding to the other end 8 in FIG. 1). W may be continuously increased or decreased. According to this embodiment, the plastic deformation of the stepped portion 23 is more likely to occur. Also in this embodiment, the bottom 20 is integrally formed at the end of the shock absorbing device.

  Further, as yet another embodiment of the stepped portion 3, although not shown, the stepped portion is formed in a spiral groove that protrudes into the inside of the shock absorbing device (cylinder) or a spiral protrusion that bulges outside. It may be formed. The shape of the groove and the ridge is not particularly limited.

  As another embodiment of the impact absorbing device according to the present invention, as shown in FIG. 5, an impact comprising a conical cylindrical body in which a small diameter end portion 32a, a medium diameter portion 32b, and a large diameter portion 32c are coaxially continuous. The absorber 31 may be used. The shock absorbing device 31 is formed with a single continuous spiral step 33. The spiral pitch and the number of strips of the stepped portion 33 are arbitrary. According to the present embodiment, as the cylindrical body has a conical shape, the stepped portion 33 has a concentric and smoothly continuous spiral shape. In the characteristic diagram shown in FIG. The resulting diagram is Also in this embodiment, the bottom 30 is integrally formed with the small diameter end 32 a of the shock absorbing device 31.

The experimental result (load diagram with respect to displacement) of the shock absorber 1 shown in FIG. 1 is shown in (II) of FIG. End deformation of the end portion is less likely by the bottom to the small diameter end portion which is a variation start point of the shock absorbing device is integrally formed, high load without exceeding the yield strength F ₀ of the body frame at the deformation starting point (initial displacement) In the subsequent increase in displacement, the stepped portion has a spiral shape, so that although some undulations occur, it becomes a substantially horizontal diagram, and an impact absorbing device with excellent impact energy absorption characteristics was gotten. Further, since there is no dead space that is difficult to be plastically deformed at the end of the shock absorbing device 1, the shock absorbing device is efficiently plastically deformed without waste over the entire length in the axial direction. Compared to the diagram (I), the amount of shock energy absorbed can be increased by α (lattice hatching region in the figure) in the figure.

  The shock absorbing device 1 shown in FIG. 1 is a quadrangular pyramid, and there are four ridge line portions 9 on the circumference that are higher in rigidity than the general part (surface). Therefore, when the ridge line part 9 is deformed, Some undulations will occur in the load diagram. Therefore, with the conical impact absorbing device as shown in FIG. 5, as described above, this undulation can be eliminated or alleviated.

  FIG. 7 is a side view of an example in which an impact absorbing device 41 constituted by a surface in which the bottom 10 of the impact absorbing device 1 shown in FIGS. 1 and 2 is inclined with respect to the shaft 4 is attached to a vehicle body without using bumper reinforcement. The figure is shown.

  In FIG. 7, an inclined bottom 40 is integrally formed at one end of the shock absorber 41 having a stepped portion 43, and a flange 42 is integrally formed at the other end. A mounting hole 44 is formed in the flange 42. For attachment to the vehicle body, for example, the flange 42 is firmly fixed to the flange 52 of the vehicle body frame (front side member or the like) 51 by the bolt 53 and the nut 54 through the attachment hole 44.

  The bottom part 40 is formed in the inclined surface, and the protrusion 45 which protrudes outward is formed. Immediately after the protrusion 45, one end 46 of the step 43 is continuously formed. With this configuration, when the vehicle collides with an object in front, the projection 45 first hits the collision surface (inner side of the bumper) 55, and the impact load concentrates on the one end 46 of the stepped portion 43 as it is. Therefore, the plastic deformation of the step portion starts with the one end portion 46 as the starting point of the plastic deformation, and the deformation of the step portion 43 is likely to proceed sequentially thereafter.

  FIG. 8 shows a side view of an example in which the shock absorbing device 41 is attached to a vehicle body using bumper reinforcement. In the embodiment shown in FIG. 8, the rear end of the shock absorbing device 41 having the stepped portion 43 is firmly attached to the flange 52 of the frame 51 by bolts 53 and nuts 54 as in the case of FIG. Further, the embodiment shown in FIG. 8 is a case where the bumper reinforcement 60 is used, and the bottom 40 of the shock absorbing device 41 is fixed to the bumper reinforcement 60 by welding or the like. Further, the bumper reinforcement 60 has a layout in which the inner side of the bumper contacts the outer peripheral surface 61 of the bumper reinforcement 60.

  For example, when the shock absorbing device of the present invention is interposed between a bumper reinforcement of a vehicle and a vehicle body frame (side member), the small-diameter end portions 2a and 32a that are deformed first are connected to the bumper reinforcement, and later Connecting the deformed large-diameter portions 2c and 32c to the vehicle body frame is effective in reducing the impact on the passenger, but there is no particular problem even if it is connected in the opposite direction.

  The present invention described above can be widely applied to a vehicle impact absorbing device, and is also suitable for, for example, a propeller shaft for an automobile.

The perspective view which shows one Example of the shock absorber of this invention AA line sectional view in FIG. 1 is a cross-sectional view taken along line AA in FIG. 1 according to another embodiment of the present invention. 1 is a cross-sectional view taken along line AA in FIG. 1 according to another embodiment of the present invention. The perspective view which shows the other Example of the impact-absorbing device by this invention. Characteristic diagram showing experimental results of shock absorber including the embodiment in FIG. Side view showing an installation example of the shock absorbing device shown in FIG. 1 and FIG. The side view which shows the other example of attachment of the impact-absorbing device shown in FIG.1 and FIG.2. A perspective view showing a conventional shock absorbing device Schematic showing a deformation image of a conventional shock absorber The perspective view which shows the conventional impact-absorbing device which has a cover member

Explanation of symbols

1, 31, 41 Shock absorbers 2a, 32a, small-diameter end portions 2b, 32b, medium-diameter portions 2c, 32c, large-diameter portions 3, 13, 23, 33 stepped portions 4, 14, 24 shafts 5, 15 orthogonal plane 6 Inclined surface 7 One end portion of step portion 8 Other end portion of step portion 9 Ridge portion 10, 16, 20, 30, 40 Bottom portion 11, 42 Flange

Claims (1)

  An impact absorber for a vehicle comprising a cylindrical body having a spiral step portion whose diameter gradually changes in the axial direction, wherein a bottom portion is integrally formed at a small-diameter end of the cylindrical body. Absorber.

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