JP6372048B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber. More specifically, the present invention relates to a shock absorber excellent in shock absorption characteristics while maintaining rigidity.

  In general, a hollow structure made of a resin material is characterized by higher rigidity than a solid structure made of the same resin material and having the same thickness. However, on the other hand, when a force from a collision is applied from the outside, there is a problem that deformation hardly occurs and impact absorption characteristics are low. For this reason, various attempts have been made to improve the impact absorption characteristics.

  In Patent Document 1, an impact energy absorber is disclosed in which the periphery of an assembly of a plurality of hollow metal spheres to which adjacent hollow metal spheres are bonded or bonded is covered with a metal or resin thin plate having a plurality of slits or holes. ing. When a load is applied to this shock energy absorber from the outside, the stroke in the area where the plateau load is relatively generated (plateau area) can be increased, and the shock absorption energy is increased. It is. The impact absorption characteristics of the impact energy absorber are mainly due to the deformation of the hollow metal sphere, and the metal or resin thin plate that serves as a cover serves as a support for the deformation of the hollow metal.

Japanese Patent No. 4918464

  The impact energy absorber described in Patent Document 1 is composed of a hollow metal sphere and a covering cylinder, and even if they are the same material, the hollow metal spheres or the hollow metal sphere and a covering cylinder Adhesion or bonding is required in many places. Since many of these adhesion points and joint points are the starting points of destruction against external force, there is a problem that the rigidity is inferior when compared with a solid structure made of the same material and with the same thickness.

  Further, the impact energy absorber of this Patent Document 1 is mainly responsible for energy absorption by the hollow metal sphere, and the hollow metal sphere is not suitable as a substitute for resin parts for automobile interior and exterior where lightness is important. There was a problem.

  Then, an object of this invention is to provide the impact-absorbing body excellent in the impact-absorbing characteristic, maintaining rigidity.

The inventors of the present invention have made extensive studies in view of the above problems. As a result, it is composed of a pair of surface layer portions and a plurality of columnar portions having outer peripheral surfaces spaced apart from each other and supporting the surface layer portions, and at least one of the pair of surface layer portions , depth have a plurality of recesses extending linearly from the small-plane direction of the surface layer portion thickness of the surface layer portion, the concave portion is provided so as to cut the cross, the shock absorber solving the above problems I found out that I can do it.

  By providing a slit or a hole in at least one surface layer portion of the pair of surface layer portions, it is possible to guide the direction of destruction when receiving an external force. As a result, the external force is not received locally, but the external force can be received by deformation of the entire structure, and the impact absorption energy can be increased.

It is a schematic diagram which shows an example of the structure of a hollow structure. It is a schematic diagram which shows another example of the structure of a hollow structure. It is a schematic diagram which shows another example of the structure of a hollow structure. It is a schematic diagram which shows an example of the method of installation of a slit. It is a schematic diagram which shows another example of the installation method of a slit. It is a schematic diagram which shows an example of the positional relationship of a slit and a columnar part. It is a schematic diagram which shows an example of the shape of the front-end | tip of a slit. It is a schematic diagram which shows another example of how to install the slit. It is a schematic diagram showing the direction of the load of Example 16 and Example 17.

  Hereinafter, the configuration of the shock absorber will be described in more detail.

  The shock absorber includes a pair of surface layer portions and a columnar portion that supports the surface layer portion apart, and has a plurality of slits or holes in at least one of the surface layer portions. Hereinafter, a structure including a pair of surface layer portions and a columnar portion that supports the surface layer portions apart from each other is referred to as a “hollow structure”.

  For hollow structures that do not have slits or holes in the surface layer, the columnar part is locally deformed from the site where the external force is applied, and the impact energy from the external force is applied to the member behind the hollow structure made of resin material at an early stage. Transmission to the end (the end) occurs. Therefore, since it behaves as a rigid body that does not absorb energy, the shock absorption energy does not increase and it is difficult to use as a shock absorber.

  On the other hand, in the shock absorber made of a hollow structure having a slit or a hole in the surface layer portion, when an external force is applied, first, the columnar portion is locally deformed. However, before the so-called abutment occurs, warping or breakage occurs starting from the slit, external force is continuously transmitted to the columnar part behind the slit, and the shock absorber is continuously deformed. Therefore, an external force can be received by deformation of the entire shock absorber, and shock absorption energy can be increased without using an additional material.

[Material of hollow structure]
The material for the hollow structure is not particularly limited, and examples thereof include a resin material and a metal material.

  Specific examples of the resin material include, for example, ABS resin, AES resin, styrene resin, (meth) acrylic resin, organic acid vinyl ester resin or derivatives thereof, vinyl ether resin, halogen-containing resin, olefin resin (polyethylene resin, polypropylene). Resin, cyclic olefin resin, etc.), polycarbonate resin, polyester resin (saturated polyester resin, etc.), polyamide resin, thermoplastic polyurethane resin, polysulfone resin (polyethersulfone, polysulfone, etc.), polyphenylene ether resin (2,6-xylenol heavy) Coal derivatives), cellulose derivatives (cellulose esters, cellulose carbamates, cellulose ethers, etc.), silicone resins (polydimethylsiloxane, polymethylphenylsiloxane, etc.), etc. It is. These resin materials can be used singly or in combination of two or more.

  Examples of the metal material include iron, stainless steel, aluminum, titanium, magnesium, and the like. These metal materials can be used alone or in combination of two or more.

  Among these resins, from the viewpoint of weight reduction, a resin material is preferable, and an olefin resin, an ABS resin, a polycarbonate resin, and a polyamide resin are more preferable.

The hollow structure has a structure including a pair of surface layer portions and a columnar object that supports the pair of surface layer portions apart from each other. Examples of such a structure include, for example, a hollow air cap structure (see FIG. 1) in which a plurality of columnar objects are independent from each other and have a columnar structure, and a corrugated cardboard in which the columnar objects have a linear or corrugated structure. Examples thereof include a hollow structure (see FIG. 2) and a honeycomb hollow structure (see FIG. 3) having a hexagonal columnar structure. These hollow structures are lighter and more rigid when compared to a solid structure made of the same material and having the same thickness.

  As the hollow structure, those produced by various molding methods such as extrusion molding and injection molding may be used, or commercially available products may be used. Examples of commercially available products include, for example, Plastic Pearl (registered trademark) manufactured by Kawakami Sangyo Co., Ltd., Dunplate (trade name) manufactured by Ube Nitto Kasei Co., Ltd., and Texel (registered trademark) manufactured by Gifu Plastic Industry Co., Ltd. It is done.

  The slit or hole may be provided in at least one of the pair of surface layer bodies, but is preferably provided in both of the pair of surface layer bodies. By adopting such a configuration, the above effect can be obtained more efficiently. When the surface layer does not have a slit or a hole, the impact absorption energy is not improved. The number of the slits or the hole portions can be arbitrarily set according to the size of the hollow structure to be used, the impact absorption characteristics required for the components to be applied, and the like. Further, the plurality of slits or hole portions provided in one surface layer portion may be only slits, only hole portions, or a combination of slits and hole portions.

  The shape of the slit or hole is not particularly limited. For example, the shape of the slit can be not only a simple cut but also a triangular shape, a wedge shape, or the like. Moreover, the shape of a hole part can be formed in various shapes, such as a substantially circular shape, a substantially elliptical shape, polygons, such as a square and a hexagon, and a star shape. Note that the shapes of the plurality of slits or holes may be the same or different.

  The depth of the slit or the hole is preferably equal to or less than the thickness of the surface layer. In the hollow structure, a pair of surface layer portions and a columnar object that supports the pair of surface layer portions apart from each other are integrated to disperse the external force as a whole while maintaining a balance. Therefore, when there is a slit or a hole that penetrates the surface layer part and reaches the columnar object that is supported separately, there is a possibility that the balance is lost and the rigidity is remarkably lowered.

  The R value (curvature radius) indicating the sharpness of the tip of the slit or the hole is preferably 5 or more. If the R value is less than 5, destruction proceeds significantly from the slits or holes, and there is a risk that the shock absorption characteristics will deteriorate.

  The installation direction of the slit or the hole may be regular or irregular, but is preferably provided in a direction orthogonal to the direction of the external force. This is because the impact absorption characteristics are less likely to appear when parallel to the direction of the external force, and the direction perpendicular to the direction of the external force improves the shock absorption characteristics most. Note that “the holes are provided in a direction perpendicular to the direction of the external force” means that the plurality of holes are provided so as to be arranged in a direction orthogonal to the direction of the external force. However, since it is assumed that the external force is applied from various directions in normal use, it is more preferable to put slits or holes in various directions in the shock absorber.

[Method of manufacturing shock absorber]
The method for producing the impact absorber is not particularly limited, and examples thereof include a method of providing a slit or a hole using a mold for a hollow structure produced by various molding methods or a commercially available hollow structure. .

  More specifically, for example, two stainless steel flat plates of 200 mm × 200 mm × thickness 3 mm are prepared, the height of the stainless steel flat plate is 0.1 mm, and the R value of the tip is 5. Prepare a mold with cut protrusions. Then, a shock absorber with slits can be obtained by sandwiching the two molds and a hollow structure made of a resin material of 200 mm × 200 mm, which has been preheated in advance, and performing hot pressing. When a hollow structure made of a resin material is used, the temperature of the hot press may be around the melting point of the resin. For example, in the case of a hollow structure made of a polypropylene resin, it is preferably performed between 165 and 175 ° C.

  The impact absorber can be used as a substitute for an existing general energy absorber. In particular, since the impact absorber has light weight, rigidity, and impact absorption energy characteristics, it is preferable to use it in combination with automobile parts such as automobile interior parts and automobile exterior parts. For example, automobile parts such as bumper fascia, front fender, door panel, rear fender, trunk lid, roof, sill spoiler, rear spoiler, lip spoiler, under diffuser, engine under cover, inner fender, over fender, mudguard, etc. Exterior parts for automobiles: Automotive interior parts such as instrument panels, cluster lids, glove box lids, knee bolsters, center consoles, headlinings, assist grips, door trims, pillar trims, tailgate panels, occupant seats, and battery housings.

  Among these, an engine under cover, a glove box lid, a head lining, and a glove box lid, which have few alternative means for weight reduction, are more preferable.

  Hereinafter, although the said impact absorber is demonstrated in detail through an Example, it is not limited to the following Example at all.

(Measurement method of flexural modulus)
JIS K7017: 1999 Fiber reinforced plastics Measured and calculated according to the method for obtaining bending properties.

Test method: 4-point bending Test piece: Test piece length 80 mm, distance between outer fulcrums 66 mm, distance between inner indenters 22 mm, width 10 mm, thickness 5 mm
Test conditions: Test temperature 23 ° C
Test speed: 2 mm / min.

(Measurement method of shock absorption energy)
Using an Instron universal testing machine, obtain a curve of F (load) -S (stroke amount) in a static compression test. With reference to the inflection point of the curve, the stroke amount at which the test piece bottoms out (the position at which the deformation ends) was determined, and the integrated load from the start of the test to the stroke at which the test piece bottomed out was defined as shock absorption energy (J).

Test method: Compression test Test conditions: Indenter diameter 150 mm, measurement temperature 23 ° C.
Test speed: 100 mm / min
Test piece: 60 mm × 60 mm × thickness 5 mm.

(Examples 1-5, Comparative Example 1)
As a hollow structure made of a resin material, Plastic Pearl (registered trademark) (product number: ED-PPZ) manufactured by Kawakami Sangyo Co., Ltd. was prepared. This hollow structure is a structure in which a polypropylene sheet is arranged as a surface layer part above and below a columnar part (columnar shape) made of polypropylene resin (see FIG. 1). The thickness of the hollow structure is 5 mm, and this structure is generally called an air cap structure.

  For this hollow structure, 1 to 24 slits were inserted into both of the pair of surface layers (see FIGS. 4 and 5). The slit was not overlapped on the columnar part (see FIG. 6), the R value at the tip of the slit was 5 and the depth was 0.1 mm (see FIG. 7). Further, Comparative Example 1 was obtained by not inserting a slit in this hollow structure.

  Table 1 below shows the results of measuring the impact absorption energy and the flexural modulus for the impact absorbers of Examples 1 to 5 and the structure of Comparative Example 1. In addition, a measured value is a relative value which set the measured value in the comparative example 1 to 1 with respect to both the impact absorption energy and the bending elastic modulus.

  As is apparent from Table 1 above, the impact absorbers of Examples 1 to 5 having slits improved the impact absorption energy without lowering the flexural modulus. On the other hand, since the structure of Comparative Example 1 has no slit, the impact absorption energy is not improved.

(Examples 6 to 10, Comparative Example 2)
As a hollow structure made of a resin material, a Udan Nitto Kasei Co., Ltd. damper plate (trade name) (product number: A-5-100) was prepared. This hollow structure is a structure in which a polypropylene resin sheet is arranged as a surface layer part above and below a linear columnar part made of polypropylene resin (see FIG. 2). The thickness of the hollow structure is 5 mm, and this structure is generally called a cardboard structure.

  For this hollow structure, 1 to 24 slits were inserted into both of the pair of surface layers (see FIGS. 4 and 5). The slit was not overlapped on the columnar part (see FIG. 6), the R value at the tip of the slit was 5 and the depth was 0.1 mm (see FIG. 7). Further, a hollow structure having no slits was designated as Comparative Example 2.

  The results of measuring the flexural modulus and impact absorption energy for the impact absorbers of Examples 6 to 10 and the structure of Comparative Example 2 are shown in Table 2 below. In addition, a measured value is a relative value which set the measured value of the comparative example 1 to 1 with respect to both a bending elastic modulus and impact absorption energy.

  As apparent from Table 2 above, the impact absorbers of Examples 6 to 10 having the slits improved the impact absorption energy without lowering the flexural modulus. On the other hand, since the structure of Comparative Example 2 has no slit, the impact absorption energy is not improved.

(Examples 11 to 15, Comparative Example 3)
A texel (registered trademark) (product number: T5-1300) manufactured by Gifu Plastic Industry Co., Ltd. was prepared as a hollow structure made of a resin material. This hollow structure is a structure in which polypropylene resin sheets are arranged in the surface layer portion above and below a hexagonal columnar body made of polypropylene resin (see FIG. 3). The thickness of the hollow structure is 5 mm, and this structure is generally called a honeycomb structure.

  For this structure, 1 to 24 slits were inserted into both of the pair of surface layers (see FIGS. 4 and 5). The slit was not overlapped on the columnar part (see FIG. 6), the R value at the tip of the slit was 5 and the depth was 0.1 mm (see FIG. 7). In addition, a hollow structure having no slit was designated as Comparative Example 3.

  The results of measuring the flexural modulus and impact absorption energy for the structures of Examples 11 to 15 and Comparative Example 3 are shown in Table 3 below. In addition, a measured value is a relative value which set the measured value of the comparative example 1 to 1 with respect to both a bending elastic modulus and impact absorption energy.

  As is clear from Table 3 above, the impact absorbers of Examples 11 to 15 having slits improved the impact absorption energy without lowering the flexural modulus. On the other hand, since the structure of Comparative Example 3 has no slit, the impact absorption energy is not improved.

(Examples 16 to 17)
As a hollow structure made of a resin material, Plastic Pearl (registered trademark) (ED-PPZ) manufactured by Kawakami Sangyo Co., Ltd. was prepared. This hollow structure was provided on both of the pair of surface layers so that eight slits were cut into a cross (see FIG. 8). The R value at the tip of the slit was 5 and the depth was 0.1 mm. The load direction was changed between Example 16 and Example 17 (see FIG. 9) . Further, as shown in FIG. 9, in each of Examples 16 and 17, the direction in which the slit is provided and the direction of the load are perpendicular to a two-dimensional plane (paper surface) parallel to both directions. Seen from the direction, they are orthogonal.
The results of measuring the flexural modulus and impact absorption energy for the structures of Examples 16 to 17 are shown in Table 4 below. In addition, a measured value is a relative value which set the measured value of the comparative example 1 to 1 with respect to both a bending elastic modulus and impact absorption energy.

  As is clear from Table 4, the shock absorption energy against the force from two directions was improved by providing the slit in the surface layer so as to be cut in a cross shape.

(Examples 18 to 20)
As a hollow structure made of a resin material, Plastic Pearl (registered trademark) (product number: ED-PPZ) manufactured by Kawakami Sangyo Co., Ltd. was prepared. 2, 8, and 16 slits were inserted into only one of the pair of surface layer portions. The slit was not overlapped on the columnar part (see FIG. 6), the R value at the tip of the slit was 5 and the depth was 0.1 mm (see FIG. 7).

  The results of measuring the flexural modulus and impact absorption energy for the structures of Examples 18 to 20 are shown in Table 5 below. In addition, a measured value is a relative value which set the measured value of the comparative example 1 to 1 with respect to both a bending elastic modulus and impact absorption energy.

  As is clear from Table 5 above, the impact absorbers of Examples 18 to 20 having slits only on one surface layer have improved impact absorption energy without lowering the flexural modulus.

Claims (4)

A pair of surface layer portions and a plurality of columnar portions having outer peripheral surfaces spaced apart and supported around the entire circumference , which support the surface layer portions apart, and at least one of the pair of surface layer portions has a depth. Impact having excellent characteristics of continuously deforming against external force, having a plurality of recesses linearly extending in the surface direction of the surface layer portion smaller than the thickness of the surface layer portion , and the recesses being provided in a cross shape. Absorber. The shock absorber according to claim 1, wherein the concave portion is provided in both of the pair of surface layer portions. The shock absorber according to claim 1, wherein the direction in which the concave portion is provided and the direction of the external force are orthogonal to each other when viewed from a direction perpendicular to a two-dimensional plane parallel to both the directions . The shock absorber according to any one of claims 1 to 3, which is used for an automobile interior part or an automobile exterior part .

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