JP4543778B2 - Shock absorbing member - Google Patents

Description

  The present invention relates to an impact absorbing member. Specifically, the present invention relates to an impact absorbing member that can absorb impact energy generated when a vehicle such as an automobile collides.

  As is well known, the body of many current automobiles is constituted by a monocoque body that supports a load by the entire body integrated with the frame in order to achieve both weight reduction and high rigidity. An automobile body must have a function of suppressing functional damage as a vehicle and protecting the lives of passengers in the cabin in the event of a vehicle collision. In order to reduce the damage of the cabin as much as possible by absorbing the collision energy at the time of the vehicle collision and reducing the impact force into the cabin, it is possible to preferentially crush spaces other than the cabin such as the engine room and the trunk room. It is valid. Because of these safety requirements, shock absorption to actively absorb collision energy by collapsing when an impact load is applied to the appropriate parts such as the front, rear, or side of the vehicle body during a collision. Members have been provided. Conventionally, as such an impact absorbing member, a front side member, a side sill, a rear side member, and the like are known.

  In recent years, by installing an impact absorbing member called a crash box at the front end of the front side member by appropriate means such as fastening or welding, the safety of the vehicle body is improved and the vehicle body damage due to a light collision is substantially eliminated. It is also becoming possible to reduce the repair costs due to The crash box is a member for absorbing much of the collision energy by preferentially collapsing in a bellows shape in the longitudinal direction by a loaded impact load.

  The shock absorbing performance required for the front side member and the like and the shock absorbing member such as the crash box will be described in detail. (A) When an impact load is applied in the axial direction, it repeatedly buckles stably in the load direction. (B) the average load when the shock absorbing member is crushed is high, and (c) the maximum reaction force generated when the shock absorbing member is crushed is near the shock absorbing member. It is three points of being restrained in the range which does not destroy the other member arrange | positioned.

  FIG. 1 shows the relationship between the axial crushing load and the axial crushing amount and the energy absorbed by the impact absorbing member among the applied impact energy with respect to the impact absorbing member loaded with an impact load in the axial direction (this specification). Then, it is a graph showing an example of the amount of “absorbed energy”. The area between the curve and the horizontal axis in the graph of FIG. 1 indicates the amount of absorbed energy.

  In order to secure a sufficient amount of absorbed energy, it is necessary to generate a stable axial crushing deformation and crush in a bellows shape. That is, as shown in the graph of FIG. 1, when the impact absorbing member at the time of the collapse cannot continue the bellows-like deformation and the bending deformation is intermittently accompanied by the bending deformation, the axial crushing load suddenly increases every time the bending deformation occurs. As a result, the amount of absorbed energy decreases. In order to prevent an abrupt decrease in the axial crushing load in the graph of FIG. 1 (in this specification, the phenomenon in which the axial crushing load decreases intermittently and rapidly is referred to as “load amplitude”), Since the thickness must be increased, this is contrary to the weight reduction that is strongly demanded of automobile bodies.

  Under such circumstances, materials and shapes for improving the shock absorbing performance of the shock absorbing member have been actively developed so far. A generally used shock absorbing member such as a front side member is a box in which a back plate is welded via a flange provided on a hat-shaped member as disclosed in Patent Document 1, for example. This is a shaped member. In the present specification, the “flange” means a portion that protrudes outward from an outline in a cross section and whose one end is not continuous with the cross section shape of the member.

  On the other hand, Patent Document 2 discloses a closed shape in which the cross-sectional shape from one end to the other end continuously changes from a polygon having a quadrangle or more to another polygon having more sides than the polygon. An invention relating to an impact absorbing member in which the amount of absorbed energy is increased while reducing the load at the initial stage of collision by using a cross-sectional structure is disclosed.

Patent Document 3 discloses an invention relating to a shock absorbing member having a polygonal closed cross-sectional shape having a partition inside.
Patent Document 4 discloses an invention relating to an impact absorbing member that secures strength by forming a substantially right-angled triangular recess toward the inside in a region including four apexes of a material having a rectangular cross section. Has been.

Further, in Patent Document 5, a bead is formed on the side surface of a front-side frame having a hat-shaped cross section having a flange toward the axial direction, whereby the front side member is bent and deformed when an impact load is applied. An invention to suppress is disclosed.
JP-A-8-128487 Japanese Patent Laid-Open No. 9-277753 JP 2003-48569 A JP 2002-284033 A JP-A-8-108863

  However, according to any of these conventional inventions, a shock absorbing member that can be easily manufactured, has a light weight, has a high average crushing load, and has a high absorption energy by being reliably deformed into a bellows shape is provided. I can't do it.

  That is, the cross-sectional shape of the impact absorbing member used in the car body of an automobile is almost flat such as a rectangle. For this reason, it is difficult to use a shock absorbing member having a polygonal cross-sectional shape such as a simple regular polygon as disclosed in Patent Document 2. Further, in the invention disclosed in Patent Document 2, since the cross-sectional shape gradually changes over substantially the entire length of the shock absorbing member, the cross-section is unavoidably suitable for stable buckling depending on the position in the axial direction. It becomes a shape. Therefore, when an impact load is applied in the axial direction, the impact absorbing member cannot be repeatedly buckled stably in the load direction of the impact load and may not be deformed into a bellows shape.

  In the invention disclosed by patent document 3, there exists a possibility that the intensity | strength of the part provided with the partition may rise excessively. For this reason, in this invention, buckling may become unstable and the amount of absorbed energy may be insufficient, and the maximum reaction force generated in the shock absorbing member particularly in the initial stage of crushing exceeds the strength of other members, There is also a possibility that other members may be crushed before the shock absorbing member is crushed. In the present invention, the weight of the shock absorbing member inevitably increases by the amount of the partition provided inside. Therefore, the present invention goes against the weight reduction of the vehicle body, which has been particularly strongly demanded in recent years.

  In the invention disclosed in Patent Document 4, since the corner portion having high strength is further processed to provide the recess portion, the strength of the recess portion may be excessively increased. For this reason, in this invention, similarly to the invention disclosed in Patent Document 3, the amount of absorbed energy may be insufficient, and other members may be crushed before the shock absorbing member is crushed. There is a risk that.

  Furthermore, in the invention disclosed by Patent Document 5, the shock absorbing member has a hat-shaped cross-sectional shape having a flange. For this reason, according to the present invention, it is considered that it is possible to suppress the bending deformation due to the applied impact load. However, according to the present invention, even if an impact load is applied, it cannot be stably collapsed in the shape of a bellows in the axial direction.

   An object of the present invention is to provide an impact-absorbing member that can be easily manufactured, has a light weight, has a high average crushing load, and has a high absorption energy by being reliably deformed into a bellows shape.

The present invention relates to a shock absorbing member having a tubular body which absorbs impact energy by deforming by impact load applied in the axial direction in the axial direction like bellows, the cylindrical body is, units having a cross section open A plurality of unit members having at least a member and another unit member having an open cross-sectional shape or a closed cross-sectional shape are arranged in parallel to provide a cross-section with a closed contour, and the cylindrical body has an open cross-sectional shape. The portion to be joined provided at the edge of the unit member having and the portion to be joined provided on the curved surface or plane constituting the cross section of another unit member having an open sectional shape or a closed sectional shape overlap. A joint portion joined together is provided on the inner side of the contour, and the cylindrical body is provided with a concave portion formed toward the inside of the contour by a part of a curved surface or a plane. A shock absorbing member for the.

  The impact-absorbing member according to the present invention has, in the cross section, (i) the length (L1) of the long side of the virtual maximum contour for the contour and the maximum of one unit member in the length direction of the long side. The length (W1) satisfies the relationship of W1 ≦ L1 × (2/3), or (ii) the junction and the plane or curved tangent adjacent to the junction are It is desirable that the joint internal angle (α), which is an angle formed at the end, is at least one of 180 ° or less.

  Further, in these impact absorbing members according to the present invention, in the cross section, the height (H), which is the length in the direction perpendicular to the joining direction of the unit members, of the unit members in the region where the recessed portions are formed, It is desirable that the width (Wu), which is the maximum length of the unit member in the joining direction of the unit member, in the region where the recess is formed satisfies the relationship of H ≧ 0.05 × Wu.

The shock absorbing member according to the present invention includes a unit member having an open cross-sectional shape composed of at least one of a curved surface and a flat surface, and another unit having an open cross-sectional shape composed of at least one of a curved surface and a flat surface. A plurality of unit members having at least a member are provided in a state of being arranged in parallel, and have a closed contour having a recessed portion formed inwardly by at least one part of the curved surface or flat surface. It is possible to reduce the number of wrinkles generated at the initial stage of deformation into a small amount and to increase the number of wrinkles.

Further, the impact absorbing member according to the present invention includes a portion to be joined provided at an edge of a unit member having an open cross-sectional shape, and a cross section of another unit member having an open cross-sectional shape or a closed cross-sectional shape. Since the portions to be joined provided on the curved surface or plane constituting are overlapped and joined, the axial crushing deformation can be maintained without causing bending deformation, so that the material is reliably crushed in a bellows shape.

  Furthermore, in the impact absorbing member according to the present invention, if at least one of the plate thicknesses or strengths of the plurality of unit members is individually set so as to satisfy a predetermined absorbed energy required for the impact absorbing member, the impact absorbing member While keeping the contour size within the design target value and minimizing weight increase due to increase in plate thickness, it is possible to obtain the desired absorbed energy and attach it obliquely with respect to the load direction. Even in this case, the balance between strength and rigidity can be easily set to maintain the bellows-like deformation.

  Thus, according to the present invention, it is possible to provide a shock absorbing member that can be easily manufactured, has a light weight, has a high average crushing load, and has a high absorption energy by being reliably deformed into a bellows shape. it can.

Hereinafter, the best mode for carrying out an impact absorbing member according to the present invention will be described in detail with reference to the accompanying drawings.
First, the principle of the shock absorbing member according to the present invention will be briefly described.

  A bellows-shaped deformation by suppressing the width of the load amplitude generated when an impact load is applied to an impact absorbing member having a polygonal cross section, for example, as much as possible, and repeatedly buckling stably in the direction of the impact load. In order to promote absorption and increase absorbed energy, it is necessary to reduce each wrinkle generated at the initial stage of crushing as a starting point of deformation into a bellows shape and to increase the number of wrinkles generated.

  In order to achieve only the generation of a large amount of wrinkles, it seems that it is only necessary to reduce the plate thickness of the impact absorbing member and set the length of each side of the impact absorbing member to be small. However, if the plate thickness of the shock absorbing member is reduced and the length of each side is shortened, it is necessary to secure a large cross-sectional area of the shock absorbing member because it is necessary to secure the desired strength and the like. Since it is arranged in a narrow part such as an engine compartment, it becomes difficult to put it into practical use as an impact absorbing member in which severe restrictions are imposed on the size of the contour.

  In contrast, a plurality of unit members having an open shape or a closed shape made of at least one of a curved surface and a flat surface are provided in a state of being arranged in parallel, and are directed to the inside by at least one part of the curved surface or the flat surface. If the shock absorbing member is configured so as to have a closed contour having a formed recess, each wrinkle generated at the initial stage of deformation into the bellows shape is reduced and the number of occurrences of this wrinkle is increased. Can do. For this reason, it is possible to prevent the impact absorbing member from increasing in size, and while making the cross-sectional area as small as possible, it is possible to easily finely adjust the strength and the like, and to suppress the increase in weight due to the increase in the plate thickness to a minimum. Can be crushed into a bellows shape.

  However, when unit members constituting such an impact absorbing member are joined to each other through a flange that protrudes outward from the end, the flange partially opens when an impact load is applied. Deformation (hereinafter referred to as “opening deformation”) occurs, and the axial crushing deformation that deforms in a bellows shape cannot be continued, and the bending deformation occurs intermittently, resulting in a decrease in the axial crushing load, that is, the absorbed energy. .

  FIG. 2 shows a case where an impact load in the axial direction is applied to an impact absorbing member obtained by joining hat members having outward flanges with each other by spot welding at an appropriate inter-spot distance through the flange. It is explanatory drawing which shows the mode of axial crushing, and a load response condition (a relationship between the amount of axial crushing and a load / average load).

  As shown in FIG. 2, when the hat members are overlapped with the outward flanges and spot-welded at a fixed spot-to-spot distance, the opening shown in FIG. Deformation occurs and the amount of absorbed energy is reduced.

  On the other hand, if the flanges are provided so that they point inward, and the hat members are overlapped with the inward flanges and spot-welded at a fixed distance between the hit points, the mouth between the spot hit points during crushing due to impact load Since the occurrence of the opening deformation is eliminated and the axial crushing deformation can be continued and reliably crushed into a bellows shape, a decrease in absorbed energy can be suppressed.

  Briefly described, the present invention can realize the axial crushing deformation into the bellows shape by suppressing the above-described opening deformation at the time of crushing by impact load, and increase the absorbed energy. It is. Next, features of the impact absorbing member of the present embodiment will be described.

  The impact absorbing member of the present embodiment includes a plurality of unit members having an open shape or a closed shape, which are at least one of a curved surface and a flat surface, arranged in parallel, and a part of the curved surface and / or the flat surface. Has a closed contour with a recess formed inwardly. FIG. 3 is an explanatory diagram showing the cross-sectional shapes of examples O1 to O13 and C1 to C11 of various unit members.

  As shown in FIG. 3, in the present embodiment, for example, unit members C1 and C2 made of curved surfaces, unit members C3, C4, C6, C7, C8, O2 to O4, O7 to O9 made of a plurality of planes, Furthermore, unit members C5, C9, C10, C11, O1, O5, O6, and O10 to O13 having one or two or more curved surfaces and planes can be used.

  Moreover, in this Embodiment, the unit member C1-C11 of the closed shape in which the edge part does not exist in the circumferential direction can be used, or the unit of the open shape in which the edge part exists in the circumferential direction Members O1 to O13 can be used. Furthermore, the shape which combined suitably the unit members C1-C11 of the closed shape and the unit members O1-O13 of the open shape may be sufficient.

  Further, only one type of unit member having the same cross-sectional shape may be used, or a plurality of types of unit members having different cross-sectional shapes may be used in combination. In this case, the unit thickness of the unit members to be combined need not be the same, and may be set as appropriate. Examples of the material of the unit member include steel, aluminum alloy, and magnesium alloy.

  Such a unit member molding method may be a known appropriate means and is not limited to a specific means. For example, what was obtained by press-molding a thin plate having a predetermined plate thickness may be used, or a tube or a tube that has been cut and further hydroformed may be used.

  In addition, the inventors of the present invention have also described the impact axial crush when an impact load in the axial direction is applied to an impact absorbing member having various cross-sectional shapes obtained by combining unit members having various cross-sectional shapes. As a result of analyzing the characteristics using dynamic explicit finite element method software, an impact having a closed contour having a concave portion formed inward by at least one of a curved surface or a flat surface provided in the unit member It has been found that the absorbing member is stable in deformation at the time of axial crushing and has increased buckling proof strength due to corners and curved surfaces forming the contour thereof, thereby ensuring high absorbed energy.

  Therefore, in the present embodiment, the shock absorbing member is configured by joining the plurality of unit members described above in a state where the respective joint portions are overlapped and arranged in parallel. The impact absorbing member of the present embodiment has a concave cross section formed toward the inside of the impact absorbing member by a part of at least one of a curved surface or a flat surface formed on the unit member, and has a closed cross-sectional shape. .

  The shock absorbing member of the present embodiment is a parallel arrangement of the above-described plurality of unit members formed into a desired cross-sectional shape by press molding, for example, with the joint portions formed in a planar shape or curved shape being overlapped. In this state, it is manufactured by temporarily fixing with an adhesive, a jig or the like and then assembling, and then joining by performing spot welding or the like at the joint located inside.

  When spot welding is performed with a portable spot welder, the joint is present inside the shock absorbing member. A work hole for penetrating the tip of the portable spot welder may be provided.

  In addition to the spot welding described above, laser welding, arc welding, and the like are also exemplified as the unit member joining means. Furthermore, when the cross-sectional dimension of the impact absorbing member is small and it is not easy to use a portable spot welder, the unit members may be joined by performing brazing welding or the like from the outside of the impact absorbing member, for example. .

  The number of unit members to be combined may be set as appropriate depending on the cross-sectional dimensions of the shock absorbing member, and is not particularly limited, but is preferably about 2 to 10. If the number of unit members to be combined is too large, the manufacturing cost increases, and the size of each unit member is set to reduce the cross-sectional area of each unit member in order to prevent the outer method of the shock absorbing member from becoming excessive. This is because it becomes too small and the impact absorbing member is easily bent and deformed when an impact load is applied.

  In addition, the unit members to be combined do not have to have the same length in the axial direction. For example, when three unit members are assembled side by side, the total length of the middle unit member is greater than the total length of the unit members at both ends. If the initial impact load is received only by the two unit members located at both ends, the initial peak load can be reduced.

  Further, the cross-sectional shape of the unit member used and the cross-sectional shape of the shock absorbing member constituted by the unit member may not be constant in the axial direction. For example, in order to reduce the initial peak load and promote bellows-like deformation, the cross-sectional area may be gradually enlarged from the impact load input surface side.

  Furthermore, in order to reduce the initial peak load and promote bellows-like deformation, a crushing bead or a notch may be provided as appropriate. In order to improve the absorbed energy, quenching or nitriding treatment by high frequency heating may be performed after the unit members are joined, or the inside of the unit member may be filled with foamed resin or the like.

  In the present embodiment, the joint portion described above is formed in a flat surface or a curved surface on the curved surface and / or plane of each of the plurality of unit members, and faces the inside of the closed shape of the shock absorbing member. It is arranged with. The plurality of unit members are joined by overlapping the joining portions.

  4A and 4B are explanatory views showing an example of the impact absorbing member 1 of the present embodiment, in which FIG. 4A is a cross-sectional view, and FIG. 4B is an example of the relationship between the crushing amount and the axial crushing load. It is a graph which shows. In addition, the part which attached | subjected the broken-line circle | round | yen mark in Fig.4 (a) has shown the junction part of each unit member O1, O1, O6, O6, and in this example, it is a suitable dot in the axial direction at this junction part. Spot welding was performed so that the distance was between.

  This shock absorbing member 1 shows a case where the above-described unit members O1 and O6 in FIG. 3 are used. In this example, the joint portion is formed as a plane toward the tangential direction at the arc ends of the unit members O1 and O6 having arc-shaped contours.

  The shock absorbing member 1 of this example is provided with unit members O1, O1, O6, and O6 having an open shape composed of a curved surface and a flat surface arranged in parallel, and is formed inward by a part of the curved surface. It has a closed contour with only eight recesses 24. The unit members O 1, O 1, O 6, and O 6 are formed in a flat shape at the end of the curved surface, and are disposed in the closed shape of the shock absorbing member 1 so as to face the inner side. 22 and 23 are overlapped and joined.

  When an impact load in the axial direction is applied to the shock absorbing member 1 of this example, the arc portions of the unit members O1 and O6 form small wrinkles, and further through four sets of joint portions 22 and 23. Thus, wrinkles can be generated alternately in the axial direction. For this reason, the stable axial crushing deformation is shown as a whole. For this reason, a load response with a small amplitude is shown in FIG. Further, the four sets of joint portions 22 and 23 can not only achieve wrinkle alignment, but also improve the bending rigidity of the shock absorbing member 1, and thus contribute to stable deformation even against an oblique impact load.

  On the other hand, FIG. 5 is explanatory drawing which shows an example of the other impact-absorbing member 2 of this Embodiment, Comprising: Fig.5 (a) is a cross-sectional view, FIG.5 (b) is a crushing amount and an axial crushing load. It is a graph which shows the relationship. In addition, the part which attached | subjected the broken-line circle | round | yen mark in Fig.5 (a) has shown the junction part of each unit member O3, O3, O8, O8, and also in this example, it is a suitable dot in the axial direction at a junction part. Spot welding was performed so that the distance was between.

  This shock absorbing member 2 shows a case where the above-described unit members O3 and O8 in FIG. 3 are used. In this example, the four sets of joint portions 22 and 23 are formed as flat surfaces toward the tangential direction at the arc ends of the unit members O3 and O8 having arcuate contours.

  The shock absorbing member 2 of this example is provided with unit members O3, O3, O8, and O8 having an open shape made of a plane arranged in parallel, and is formed inward by a part of this plane. It has a closed contour with two recesses 25. The unit members O3, O3, O8, and O8 are formed in a flat shape at the end of the flat surface, and the four sets of joint portions that are arranged facing the inner side inside the closed shape of the shock absorbing member 2 22 and 23 are overlapped and joined.

  Also in this example, the flat portions having the corners of the unit members O3 and O8 can form small wrinkles, and the wrinkles are alternately generated in the axial direction via the four sets of joint portions 22 and 23. Therefore, stable axial crushing deformation is shown as a whole, and a load response with a small amplitude is shown as shown in the graph in FIG. Further, the four sets of joint portions 22 and 23 not only aim at wrinkle alignment, but also improve the bending rigidity of the shock absorbing member 2, and thus contribute to stable deformation even against an oblique impact load.

  FIG. 6 is an explanatory view showing a cross section of still other shock absorbing members 3 to 13 of the present embodiment. In addition, the part which attached | subjected the broken-line circle | round | yen mark in FIG. 6 has shown the junction part of each unit member, and also in this example, spot welding is performed so that it may become a suitable inter-spot distance in the axial direction at this junction part. went.

  The shock absorbing member 3 shows the case where the unit member O6 in FIG. 3 is used, the shock absorbing member 4 shows the case where the unit members O1 and O12 are used, and the shock absorbing member 5 uses the unit members O2 and O7. The shock absorbing member 6 shows the case where the unit members O1 and O6 are used, the shock absorbing member 7 shows the case where the unit members O1 and O11 are used, and the shock absorbing member 8 shows the case where the unit member O11 is used The shock absorbing member 9 shows the case where the unit members O1 and O6 are used, the shock absorbing member 10 shows the case where the unit members O2, O6 and O8 are used, and the shock absorbing member 11 shows the unit members C11 and O6. The shock absorbing member 12 uses the unit members O1 and O5, and the shock absorbing member 13 uses the unit members C2 and O13. It shows the case.

  Similarly to the shock absorbing members 1 and 2 described above, these shock absorbing members 3 to 13 are in a state where a plurality of unit members having an open shape or a closed shape made of at least one of a curved surface or a flat surface are arranged in parallel. And having a closed contour having a recess formed inwardly by a part of at least one of the curved surface or the flat surface. The plurality of unit members are formed in a flat shape or a curved shape on at least one of a curved surface or a flat surface, and a joint portion disposed facing the inside is overlapped inside the closed shape of the shock absorbing member. Are to be joined.

  Here, the reason why it is “planar or curved” with respect to the form of the joint is that if it is “planar” like the shock absorbing members 1 to 12, the joint is easy and the rigidity of the joint is sufficient. This is because is not excessively strong and can contribute to stable deformation. Moreover, when using the unit member C2 which consists only of a curved surface like the impact-absorbing member 13, if a joining part shape is made into the curved surface shape which follows the joining surface of the unit member C2 like the joining part of the unit member O13. Alignment of the wrinkles between the unit member C2 and the unit member O13 can be obtained, and the joint rigidity can be prevented from becoming excessively strong. As a result, each of the shock absorbing members 3 to 13 has at least one of a curved surface or a flat surface portion formed on each of the unit members O1, O2, O5, O6, O7, O8, O11, O12, O13, C2, and C11. Small wrinkles can be formed, and furthermore, wrinkles can be generated alternately through the joints which are flat portions or curved portions formed in the axial direction, so that stable axial crushing deformation is shown as a whole. A load response with a small amplitude can be shown. Further, the joint portion contributes not only to wrinkle alignment but also to stable deformation even against an oblique impact load in order to improve the bending rigidity of the member.

Further, the impact absorbing members 1 to 13 of the present embodiment are in a cross section,
(I) The length (L1) of the long side of the virtual maximum contour for the contour and the maximum length (W1) of one unit member in the length direction of the long side are W1 ≦ L1 × Satisfying the relationship (2/3),
(Ii) The joint interior angle (α), which is an angle formed by the joint and the flat or curved tangent adjacent to the joint, at the end of the joint is 180 ° or less, or (iii) a dent The height (H), which is the length of the unit member in the region where the portion is formed, in the direction perpendicular to the joining direction of the unit member, and the unit member in the joining direction of the unit member in the region where the recessed portion is formed Since it is desirable that the width (Wu) which is the maximum length satisfies at least one of satisfying the relationship of H ≧ 0.05 × Wu, this point will be described.

Regarding Item (i) FIG. 7 shows a virtual maximum contour 14 having side lengths L1 and L2 (L1 ≧ L2), which is a rectangular design region of the shock absorbing members 1 to 13 of the present embodiment. It is explanatory drawing shown. FIG. 8 is an explanatory view showing the shock absorbing members 1 and 8 existing in the imaginary maximum contour 14, and the lengths of the sides of the unit region 15 constituted by one unit member are W1 and W2. (W1 ≦ W2).

  7 and 8, when the relationship of W1> L1 × (2/3) is established, the wavelength of wrinkles formed at the time of axial crushing is increased and the load amplitude is increased, resulting in a decrease in absorbed energy. For this reason, it is desirable that the relationship of W1 ≦ L1 × (2/3) holds. If this relationship is established, the deformation follows the long side direction of the length L1 even if W2 = L2, so that there is no particular limitation.

Regarding Item (ii) FIG. 9 shows an extracted joint portion between adjacent unit members of the shock absorbing member 16 made of a flat unit member or the shock absorbing member 17 made of a flat and curved unit member. It is explanatory drawing.

  As shown in FIG. 9, in the impact absorbing member 16, in the cross section, the joint 18 and the plane 20 adjacent to the joint 18 are angles formed at the end 18 a of the joint 18. On the other hand, in the shock absorbing member 17, the angle formed by the joint 19 and the tangent line 26 of the curved surface 21 adjacent to the joint 19 at the end 19 a of the joint 19 in the shock absorbing member 17. When it is satisfied that the joint internal angle α is 180 ° or less, the occurrence of opening deformation of the joints 18 and 20 during crushing with an impact load is effectively suppressed. For this reason, the shock absorbing members 16 and 17 are desirable because they can maintain stable axial crushing deformation as a whole and are surely crushed in a bellows shape.

Regarding Item (iii) FIG. 10 is an explanatory drawing showing the region of the end of the unit member. In the same figure, the symbol H indicates the height which is the length in the direction orthogonal to the joining direction of the unit members (the left-right direction in the drawing) in the region where the recess is formed, and the symbol Wu indicates that the recess is formed. The width which is the maximum length of the unit member in the joining direction of the unit member in the region is shown.

  In the present embodiment, when the height H is in a relationship of H <0.05 × Wu with respect to the width Wu, the bending rigidity of the cross section is lowered, and unstable buckling deformation at the time of axial crushing deformation may be exhibited. As a result, the absorbed energy decreases. Therefore, in the present embodiment, it is desirable to satisfy the relationship of H ≧ 0.05 × Wu.

  Furthermore, in the present embodiment, at least one of the plate thicknesses or strengths of the plurality of unit members may be individually set to values that can satisfy the predetermined absorbed energy required for the shock absorbing member. desirable. This makes it possible to obtain the desired absorbed energy while minimizing the increase in the weight of the shock absorbing member, and to set a balance between strength and rigidity even when mounted obliquely with respect to the load direction of the impact load. It becomes easy to do.

  As described above, the shock absorbing member of the present embodiment includes a plurality of unit members having an open shape or a closed shape formed of at least one of a curved surface and a flat surface arranged in parallel. Since it has a closed contour with a recess formed inwardly by at least one part, it reduces each wrinkle generated at the initial stage of deformation into a bellows shape and increases the number of wrinkles generated. can do.

  Further, in the impact absorbing member of the present embodiment, the plurality of unit members are formed on at least one of the curved surface and the flat surface in a flat shape or a curved shape, and face the inside of the closed shape of the impact absorbing member. Since the joints arranged in (1) are overlapped and joined, the size of the shock absorbing member can be prevented from expanding, and the axial crushing deformation is maintained and the bellows is destroyed.

  Further, in the impact absorbing member of the present embodiment, if at least one of the thickness or strength of the plurality of unit members is individually set so as to satisfy a predetermined absorbed energy required for the impact absorbing member, the impact absorbing member Without modifying the shape of the member, while minimizing the weight increase due to the increase in plate thickness, the desired axial crushing load level, that is, the absorbed energy can be obtained, and the strength and rigidity for the diagonally mounted member The balance of the difference can be easily set.

  Thus, according to the present invention, it is possible to provide a shock absorbing member that can be easily manufactured, has a light weight, has a high average crushing load, and has a high absorption energy by being reliably deformed into a bellows shape. it can.

Furthermore, the present invention will be described more specifically with reference to examples.
A cross-sectional shape is designed based on the above-described embodiment within the imaginary maximum contour of a rectangle of 120 × 60 (mm) shown in FIG. 7, and the impact axis using dynamic explicit finite element method software is used. The crushing performance was investigated. The impact speed was 64 km / h, the member length was 200 mm, and the crushing amount was set to 150 mm. In addition, assuming that it is used in a real vehicle, a notch for stabilizing the initial deformation and reducing one peak load is introduced on the impact surface side. The material was unified with a high-tensile steel plate of 590 MPa class (considering strain dependence according to the Cowper-Symonds law).

FIG. 11 shows the cross-sectional shape and plate thickness of the impact-absorbing member evaluated. In addition, FIG.11 (c) shows what is called a one-hat member conventionally well-known.
11 (a), FIG. 11 (b), FIG. 11 (d) , FIG. 11 (g) to FIG. 11 (i), and the comparative example shown in FIG. Table 1 shows a comparison of absorbed energy. In consideration of the weight difference due to the cross-sectional circumference, the value obtained by dividing the absorbed energy by the weight is also shown.

  Moreover, the load displacement diagram at the time of axial crushing is shown with a graph in FIG. In the graph shown in FIG. 12, since the load level is different between the invention example and the comparative example, comparison is made by a graph divided by the average load.

As can be seen from Table 1, Examples 1 , 2 , 3 , and 6 to 8 of the present invention are lighter than the comparative example, and the amount of absorbed energy and the amount of absorbed energy per unit weight are larger than those of Comparative Example 3. It can be seen that the impact characteristics are good.

  As is apparent from the graph in FIG. 12, the waveform of the present invention example is smaller than that of the comparative example. This is because each unit member forms small wrinkles, the plastic buckling period is short, and even if the plate thickness is smaller than the comparative example, it is possible to suppress the drop of the load. As a result, the load is stabilized at a high level and absorbed. The amount of energy is increased.

  Furthermore, in Invention Example 2, one of the unit members of Invention Example 1 is increased to a plate thickness of 1.2 t, but the absorbed energy amount is improved as shown in Table 1 without destroying the load response characteristics. ing. In this way, adjusting the plate thickness and material for each unit contributes to the control of the axial crush load level, that is, the absorbed energy, without modifying the shape and minimizing the weight increase due to the increase in plate thickness. it can.

A graph showing an example of the relationship between the axial crushing load and the axial crushing amount and the amount of energy absorbed by the impact absorbing member among the applied impact energy for the impact absorbing member loaded with an impact load in the axial direction. It is. The axial crush when an impact load in the axial direction is applied to an impact absorbing member obtained by joining hat members having outward flanges with each other by spot welding at an appropriate inter-spot distance through this flange. It is explanatory drawing which shows a mode and a load response condition (a relationship between an axial crush amount and a load / average load). It is explanatory drawing which shows the cross-sectional shape of the example of various unit members. It is explanatory drawing which shows an example of the impact-absorbing member of embodiment, Comprising: Fig.4 (a) is a cross-sectional view, FIG.4 (b) is a graph which shows an example of the relationship between a crushing amount and an axial crushing load. It is explanatory drawing which shows an example of the other impact-absorbing member of embodiment, Comprising: Fig.5 (a) is a cross-sectional view, FIG.5 (b) is a graph which shows the relationship between a crushing amount and an axial crushing load. It is explanatory drawing which shows the cross section of the further another impact-absorbing member of embodiment. It is explanatory drawing which shows the virtual largest outline whose side length is L1 and L2, which is a rectangular design area of the shock absorbing member of the embodiment. It is explanatory drawing which shows the impact-absorbing member which exists in the virtual largest outline, The length of the side of the unit area | region comprised by one unit member is W1 and W2. It is explanatory drawing which extracts and shows the junction part of adjacent unit members about the impact-absorbing member which consists of a unit member which consists of a plane, or the impact-absorbing member which consists of a unit member which consists of a plane and a curved surface. It is description which extracts and shows the area | region of the edge part of a unit member. It is explanatory drawing which shows collectively the cross-sectional shape and board thickness of the impact-absorbing member which evaluated. 3 is a graph showing a load displacement diagram at the time of shaft crushing in Example 1. FIG.

Explanation of symbols

1-13 Shock Absorbing Member 14 Virtual Maximum Contour 15 Unit Region 16, 17 Shock Absorbing Member 18, 19 Joint 18a, 19a End 20 Plane 21 Curved Surface 22, 23 Joint 24, 25 Recess 26 Tangent α Joint Inner corners C1 to C11 Closed shape unit members O1 to O13 Open shape unit members

Claims (6)

An impact absorbing member having a cylindrical body that absorbs collision energy by being deformed into an accordion shape in the axial direction by an impact load applied in the axial direction,
The cylindrical body has a cross-section with a closed contour by arranging in parallel a plurality of unit members having at least a unit member having an open cross-sectional shape and another unit member having an open cross-sectional shape or a closed cross-sectional shape. Preparing,
The cylindrical body is a curved surface constituting a cross-section of a portion to be joined provided at an edge of the unit member having the open cross-sectional shape and another unit member having the open cross-sectional shape or the closed cross-sectional shape, or A joining portion formed by overlapping and joining a portion to be joined provided on a plane is provided on the inner side of the contour, and the cylindrical body is formed toward the inside of the contour by a part of the curved surface or the plane. The impact-absorbing member characterized by including the recessed part made.   In the cross section, the length (L1) of the long side of the virtual maximum contour with respect to the contour and the maximum length (W1) of one unit member in the length direction of the long side are W1. The impact-absorbing member according to claim 1, satisfying a relationship of ≦ L1 × (2/3).   2. A junction internal angle (α), which is an angle formed by an end portion of the joined portion and the tangent line of the flat surface or the curved surface adjacent to the joined portion in a cross section, is 180 ° or less. The impact absorbing member according to claim 1 or 2.   In the cross section, the height (H) of the unit member in the region where the recess is formed, the height (H) which is the length in the direction perpendicular to the joining direction of the unit member, and the region in which the recess is formed The width (Wu) which is the maximum length of the unit member in the joining direction of the unit member satisfies the relationship of H ≧ 0.05 × Wu. Shock absorbing member. The impact absorbing member according to any one of claims 1 to 4, wherein the impact absorbing member is a crash box or a side member. The impact-absorbing member according to any one of claims 1 to 5, wherein the unit member is made of steel, an aluminum alloy, or a magnesium alloy.

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