JP4918464B2 - Impact energy absorber - Google Patents

Description

  The present invention relates to an impact energy absorber that absorbs an impact load by deformation, for example, in the event of a car collision.

  In recent years, in order to improve the safety of the vehicle body and reduce the repair cost by eliminating the damage of the vehicle body at the time of a light collision, an impact absorbing member called a crash box has been attached to the front end of the frant side member. It became so.

  The crash box is generally a cylindrical member that buckles in the axial direction due to an impact load applied in the axial direction. However, in order to absorb larger energy, the techniques shown in Patent Documents 1 to 3 are disclosed. ing.

  In Patent Literature 1, when an impact load is applied in the axial direction in a steel hollow box having a substantially polygonal closed cross section, it is repeatedly buckled in the axial direction to deform into an accordion-like shape and an average load at the time of collapse is obtained. A member that absorbs high collision energy is disclosed.

  Patent Document 2 discloses an energy absorbing element covered with a housing configured as a molded aluminum plate part for attaching a foam metal, in particular, foam aluminum, to a vehicle as a filler.

  In Patent Document 3, a hollow metal sphere is applied as a filler to a hollow portion in a reinforcement (outer frame) extending in the vehicle width direction of a front bumper, and an impact load is applied by compression deformation of the reinforcement and the filler. Absorbing techniques are disclosed.

JP 2007-17003 A JP-A-11-59298 JP 2004-142607 A

  The load-stroke curve of the conventional crash box is shown in No. A typical example is shown in the A curve. It consists of a region where a relatively plateau load is generated with respect to the stroke when an impact load is applied, and a region where the load increases to the right. The impact energy must be absorbed in a plateau region below a load that does not damage the vehicle body, and the plateau region must have a large stroke. However, the crash box described in the patent document has a problem that the stroke is not sufficient.

  An object of the present invention is to provide an impact energy absorber having a large stroke in the plateau region and excellent impact absorption energy.

  As a result of intensive investigations to solve the above problems, the inventors have found that the plateau region cannot be expanded because the metal is densely packed in the compression and axial directions. Therefore, it was found that the problem can be solved by spreading in the radial direction, and the present invention was completed.

  Based on these knowledge, this invention takes the following structures, in order to solve the subject.

1st invention consists of the aggregate | assembly of several hollow metal spheres which the adjacent hollow metal spheres adhere | attached or joined , At least side surface of the said aggregate | assembly of said hollow metal sphere has a some slit part or a hole, and is a metal thin plate It is an impact energy absorber excellent in the stroke characteristics of the plateau region characterized by being covered with.

The second invention comprises an assembly of a plurality of hollow metal spheres in which adjacent hollow metal spheres are bonded or joined together , and at least a side surface of the assembly of the hollow metal spheres is covered with a metal thin plate having a plurality of thin portions. It is an impact energy absorber excellent in the stroke characteristics of the plateau region characterized by the above.

  According to the present invention, an impact energy absorber having a large compression stroke and a large energy absorption amount can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  The hollow metal sphere used is determined by the load required for the impact energy absorber and is not particularly limited, but iron or an iron-based alloy with low cost and high strength is more suitable. The dimensions are more preferably a diameter of 1 to 10 mm and a wall thickness of 0.05 to 0.2 mm.

  For bonding or joining the hollow metal spheres, a resin adhesive, a low-melting-point adhesive, or a solid phase diffusion bonding technique is more suitable, but is not limited thereto. The resin adhesive is typified by an epoxy resin or an acrylic resin, and is generally cured at a temperature of about 100 ° C. after coating and molding on the surface of a hollow metal sphere.

  The low melting point adhesive is formed by forming a low melting point alloy typified by a solder alloy on the surface in a powder or film state, raising the temperature to about 300 ° C., and bonding the hollow metal spheres together. In solid phase diffusion bonding, hollow metal spheres are bonded at a high temperature of about 1000 ° C.

  As shown in FIG. 1, when using without an outer cylinder can, the stroke of a plateau part can be extended rather than the case with an outer cylinder can, but a load resistance falls. In order to further increase the impact absorption energy, it is more preferable to use the outer can of the present invention, and the details will be described below.

  Resin, paper, and cloth can be used as the outer cylinder can. Resin, paper, and cloth having a strength that can be broken in the middle of compression so as to spread in the radial direction during compression by impact load are suitable. In the case of resin, it is also preferable to use an elastic body such as a comb extending in the radial direction.

  Next, as shown in FIG. 2, a thin metal plate with a slit can be used as an outer cylinder can. Although it does not specifically limit as a metal thin plate material, From the point of economical efficiency, the steel plate for cans with a general thickness of about 0.2-0.3 mm is suitable.

  The slits are inserted in two or more in the longitudinal direction so that the axial direction is the longitudinal direction in about 3 to 10 locations in the circumferential direction, and the ratio of the slit length to the total length is 0.4 or more. It is more preferable to divide.

  At this time, the divided slits may be arranged in a straight line or in a staggered arrangement. This is because the effect of spreading in the radial direction is impaired unless the ratio of the slit length to the total length is less than 0.25. Examples of the respective slit patterns are shown in side development views in FIGS. FIG. 4 shows an example of a linear arrangement, and FIG. 5 shows an example of a staggered arrangement.

  6 and 7 show the effect of the slit. As shown in FIG. A is a comparative example in which the outer cylinder can has no slit in FIG. No. B is a case where three-stage slits are arranged in a staggered manner. C is also an example having a three-stage slit, but offsetting the pressing direction by 10 degrees.

  The stroke of the plateau is No. Whereas A is 20 mm, no. B is 92 mm, no. C is greatly improved by providing a slit of 100 mm.

  8 shows a compression test specimen No. B, No. It is the photograph which showed the condition before and behind compression of C. It turns out that it is compressed neatly in the direction of the compression axis.

  Next, a case where a thin plate whose part is thin instead of the slit is used as an outer cylinder can be described. This is a thin portion of the slit portion of the above-mentioned thin plate with slits. The position of the thin portion is preferably the same position as the slit. The thickness of the thin portion is preferably 1/2 or less of the base body. This is because when the ratio exceeds 1/2, the effect of spreading in the radial direction becomes small.

  In the following, a specific method for producing the hollow metal sphere will be described by taking the case of iron as an example, but the present invention is not limited to this.

  On the surface of a polystyrene foam sphere having an average particle diameter of 5 mm, a slurry of about 30% by mass of iron oxide and several mass% of PVA (polyvinyl alcohol) was sprayed on water to form a 200 μm thick film. A hollow iron ball is obtained by sintering the obtained foamed polystyrene with a film | membrane at 1000-1100 degreeC in air | atmosphere, and then sintering at 1000-1300 degreeC in hydrogen gas.

A slurry in which iron oxide (Fe ₂ O ₃ ) having an average particle diameter of 0.7 μm: 30% by mass, Cu ₂ O: 0.5% by mass, and PVA: 2% by mass was prepared, and sprayed with dry air to have a diameter of 5 mm. This was applied to the surface of polystyrene foam. Subsequently, sintering was performed in air at 1000 ° C. and reduction sintering in hydrogen at 1100 ° C. to produce a hollow iron sphere having a diameter of about 3 mm. The test results are summarized in Table 1.

  A hollow iron ball was filled into an outer can shown in Table 1 together with an epoxy resin having a mass ratio of 10%, and then thermally cured at 100 ° C. for 1 hour to produce an impact energy absorbing can. The number of slits and thin parts was 8 in the circumferential direction. In the case without an outer cylinder can, it was prepared by filling a 0.2 mm-thick can (no processing), thermosetting, and then peeling off the can. The outer shape of the can is 90 mm in diameter and 150 mm in length. The obtained impact energy absorption can was subjected to a compression test at a speed of 20 mm / min to obtain a stroke-load curve. The energy absorption amount was defined as the absorption amount at a maximum load of 100 kN or less.

It is the figure which showed the example of only a hollow metal sphere. It is a figure which shows the example which covered the side surface with the metal thin plate with a slit. It is a figure which shows the example which covered the side surface with the metal thin plate. It is a figure explaining the slit pattern of straight arrangement | positioning. It is a figure explaining the slit pattern of zigzag arrangement. It is a figure explaining the effect of a slit. It is a figure explaining a stroke and a load diagram. It is a figure explaining the condition of the specimen before and after a test.

Claims (2)

It is composed of an assembly of a plurality of hollow metal spheres in which adjacent hollow metal spheres are bonded or bonded, and at least a side surface of the assembly of the hollow metal spheres is covered with a thin metal plate having a plurality of slit portions or hole portions. Impact energy absorber with excellent plateau stroke characteristics . It is composed of an aggregate of a plurality of hollow metal spheres in which adjacent hollow metal spheres are bonded or bonded, and at least a side surface of the aggregate of the hollow metal spheres is covered with a metal thin plate having a plurality of thin portions. Impact energy absorber with excellent stroke characteristics in the plateau region .