Energy absorbing member

Abstract

In an energy absorbing member (10), a basic unit (20) with a U-shaped cross-section comprising a press-molded article is formed by a first sheet section (41) and a pair of second sheet sections (42, 42). An inner surface (21) and an outer surface (22) of the basic unit (20) that has been configured having the U-shaped cross section are contours that do not have an undercut shape in a direction along a reference line (CL2). The first sheet section (41) and the pair of second sheet sections (42, 42) have imaginary parallelograms (90) that extend from a first end surface (51) to a second end surface (52) of the basic unit (20) and are respectively deviated around an axis (CL1). At least one of two diagonals (91, 92) of each imaginary parallelogram (90) is formed by a fold line.

Description

Energy absorbing material

[0001] The present invention relates to an improved technology for energy absorbing members.

[0002] In recent years, development has been progressing on energy absorbing members that can increase their ability to absorb energy by collapsing themselves. Technology for such energy absorbing members is known, for example, from Patent Document 1.

[0003] The energy absorption member known from Patent Document 1 uses an inverted spiral origami structure. The inverted spiral origami structure is a structure in which, when the side surfaces of a hexagonal prism are folded along the fold lines on the side surfaces, the upper and lower base surfaces are inverted and collapsed in a spiral shape, causing the side surfaces to be folded tightly together. This energy absorption member is said to have a large energy absorption capacity and a large reaction force.

[0004] JP 2011-058579 A

[0005] The energy absorption member known in Patent Document 1 requires the creation of multiple fold lines in a cylindrical member, forming different cross sections along the axis, so it is conceivable to process it using, for example, a hydroforming method. However, hydroforming equipment is specialized and large, and the longer the cylindrical material, the more difficult it is to control the hydraulic pressure applied inside the cylindrical material, making it more likely that pressure unevenness will occur, which in turn will lead to uneven processing and increase processing costs.

[0006] An object of the present invention is to provide a technique that enables easy mass production of energy absorbing members at relatively low cost by press molding.

[0007] After extensive research, the inventors focused on the cross-sectional shape of the energy absorption member. Specifically, they discovered that the energy absorption member can be press-formed by forming it into an inverted spiral origami structure with an open cross section, rather than a closed cross section such as a cylindrical shape. They also discovered that by forming the energy absorption member into a U-shaped cross section, even an inverted spiral origami structure can be press-formed. The present invention was completed based on this finding.

[0008] According to the present disclosure, a basic unit is a press-molded product, and is a member having a U-shaped cross section formed by a first plate portion and a pair of second plate portions extending from both edges of the first plate portion in directions facing each other; a straight line passing through a space surrounded by the first plate portion and the pair of second plate portions and extending in a direction along each plate surface of the first plate portion and the pair of second plate portions is defined as an axis of the basic unit; a straight line perpendicular to the axis and extending in a direction intersecting the plate surface of the first plate portion is defined as a reference line of the basic unit; one end face of the basic unit in a direction along the axis is defined as a first end face, and the other end face is defined as a second end face; and the inner and outer surfaces of the basic unit configured in the U-shaped cross section have contours that do not have an undercut shape in a direction along the reference line, The energy absorbing member is provided in which the first plate portion and the pair of second plate portions each have an imaginary parallelogram biased around the axis from the first end face to the second end face, and at least one of the two diagonals of the imaginary parallelogram is formed by a broken line.

[0009] The present disclosure can provide a technique that enables easy mass production of energy absorbing members with high energy absorption performance at relatively low cost through press molding.

[0010] 1 is a perspective view of an energy absorbing member according to Example 1; FIG. 2 is a perspective view of one basic unit shown in FIG. 1; FIG. 3 is an end view of a first end surface of the basic unit as viewed from the direction of arrow 3 in FIG. 2; FIG. 4 is an end view of a second end surface of the basic unit as viewed from the direction of arrow 4 in FIG. 2; FIG. 5A is a view of the energy absorbing member as viewed from the direction of arrow 5A in FIG. 1, and FIG. 5B is a view of the energy absorbing member as viewed from the direction of arrow 5B in FIG. 5A; FIG. 5B is an enlarged view of a virtual parallelogram shown in FIG. 5A; FIG. 7A is a perspective view of an energy absorbing member according to Example 2, and FIG. 7B is a view as viewed from the direction of arrow 7B in FIG. 7A; FIG. 6 is a view as viewed from the first end surface side of an energy absorbing member according to Example 3; and FIG. 7C is a view as viewed from the first end surface side of an energy absorbing member according to Example 4. FIG. 10A is a perspective view of an energy absorbing member according to Example 5, and FIG. 10B is a view as viewed from the direction of arrow 10B in FIG. 10A. Fig. 11A is a plan view of an energy absorbing member according to Example 6, and Fig. 11B is a view of the energy absorbing member as viewed from the direction of arrow 11B in Fig. 11A. Fig. 13A is a perspective view of one basic unit shown in Fig. 12, and Fig. 13B is an enlarged view of the flange shown in Fig. 13A. Fig. 14A is a view of the basic unit as viewed from the direction of arrow 14A in Fig. 13, and Fig. 14B is an end view of the second end surface of the basic unit as viewed from the direction of arrow 14B in Fig. 13. Fig. 15A is a perspective view of an energy absorbing member according to Example 8, and Fig. 15B is a view as viewed from the direction of arrow 15B in Fig. 15A. Fig. 16A is a schematic view (reproduced) of the energy absorbing member shown in Fig. 12, Fig. 16B is a view of the energy absorbing member shown in Fig. 16A with the press-molding end separated, and Fig. 16C is a view of two energy absorbing members shown in Fig. 16B superimposed on each other. Figure 17A is a perspective view of an energy absorbing member according to Example 9, Figure 17B is a view of a basic unit as viewed from the direction of arrow 17B in Figure 17A, Figure 17C is a cross-sectional view taken along line 17C-17C in Figure 17A, and Figure 17D is an enlarged view of portion 17D in Figure 17C. Figure 18A is a perspective view of an energy absorbing member according to Example 10, and Figure 18B is a cross-sectional view taken along line 18B-18B in Figure 18A. Figure 20A is a perspective view of an energy absorbing member according to Example 12, and Figure 20B is an end view of the energy absorbing member as viewed from the direction of arrow 20B in Figure 20A.FIG. 20 is a perspective view of an energy absorbing member according to a thirteenth embodiment.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. Note that the embodiments shown in the accompanying drawings are merely examples of the present invention, and the present invention is not limited to these embodiments.

[0012] First Embodiment An energy absorbing member 10 according to a first embodiment will be described with reference to FIGS. 1 to 6. FIG.

[0013] 1 shows the overall structure of an energy absorbing member 10. This energy absorbing member 10 is configured into an inverted spiral origami structure using a plurality of basic units 20 (partial structures 20) formed continuously and integrally. The inverted spiral origami structure is a structure in which, when the energy absorbing member 10 is folded along a plurality of fold lines provided on the side surfaces, both end surfaces 10a, 10b of the energy absorbing member 10 in the longitudinal direction R1 are compressed while being inverted in a spiral shape, thereby folding so that the side surfaces are tightly attached.

[0014] The energy absorbing member 10 may be made of any material that can undergo plastic deformation. For example, a steel plate, preferably a high-strength steel plate such as high-tensile steel, contributes to weight reduction. The energy absorbing member 10 may be an injection-molded or cast resin product, but may also be a press-molded product obtained by press-molding a flat plate-shaped material.

[0015] The energy absorbing member 10 will be described in more detail. As shown in Figures 1 and 2, the energy absorbing member 10 is configured such that two basic units 20, 20 form a unit group 31. At least two unit groups 31, 31 are connected together along the axis CL1 of the energy absorbing member 10 to form a single elongated object 32. Therefore, all the connected basic units 20 are integrally configured as a single elongated object 32. In this manner, the energy absorbing member 10 includes the elongated object 32 that is long in the direction of the axis CL1. When this energy absorbing member 10 receives energy (external force) in the direction of the axis CL1, it absorbs the energy by undergoing reverse spiral deformation at the bent line portions along the entire length of the elongated object 32.

[0016] For example, this elongated object 32 is composed of two unit groups 31, 31. In that case, the energy absorbing member 10 is composed of four basic units 20. The following description will be given using four basic units 20 as an example. When the four basic units 20 are to be distinguished from one another in the description, alphabets are added to the reference numerals 20, and they are referred to as a first basic unit 20A, a second basic unit 20B, a third basic unit 20C, and a fourth basic unit 20D. When the two unit groups 31 are to be distinguished from one another in the description, alphabets are added to the reference numerals 31, and they are referred to as a first unit group 31A and a second unit group 31B.

[0017] Referring also to Figure 3, the energy absorbing member 10 (each basic unit 20) has a U-shaped cross section and is composed of a first plate portion 41 and a pair of second plate portions 42, 42 extending toward each other from both edges 41a, 41a of the first plate portion 41. The ends 42a, 42a of the second plate portions 42, 42 opposite the both edges 41a, 41a of the first plate portion 41 are referred to as "open-side ends 42a, 42a." Furthermore, the energy absorbing member 10 (each basic unit 20) has a space 43 (internal space 43) surrounded by the first plate portion 41 and the pair of second plate portions 42, 42. The open-side ends 42a, 42a of the pair of second plate portions 42, 42 define an open end 44 that communicates with the internal space 43.

[0018] Here, the energy absorbing member 10 (each basic unit 20) is defined as follows: The axis CL1 of the energy absorbing member 10 (each basic unit 20) is a straight line that passes through an internal space 43 surrounded by the first plate portion 41 and the pair of second plate portions 42, 42 and extends in the longitudinal direction R1 of the energy absorbing member 10 (the direction of arrow R1 in FIG. 2 ). In other words, this axis CL1 extends along the plate surface 41 b of the first plate portion 41 and the plate surfaces 42 b, 42 b of the pair of second plate portions 42, 42. Note that "the axis CL1 extending along each plate surface 41 b, 42 b, 42 b" does not necessarily mean that the axis CL1 is completely parallel to the plate surfaces 41 b, 42 b, 42 b, as long as the axis CL1 is a straight line that extends in the longitudinal direction R1 of the energy absorbing member 10. For example, as shown in Figure 1, even if at least a portion of each plate surface 41b, 42b, 42b is inclined from one end surface 10a of the energy absorbing member 10 toward the other end surface 10b, this is also included in the configuration in which the axis CL1 extends along each plate surface 41b, 42b, 42b.

[0019] A straight line CL2 that is perpendicular to the axis CL1 and extends in a direction (the direction of arrow R2) that intersects with the plate surface 41 b of the first plate portion 41 is defined as the “reference line CL2 of the energy absorbing member 10 (each basic unit 20).” It is preferable that this reference line CL2 be perpendicular to the imaginary flat plate surface of the first plate portion 41.

[0020] 2, one end face 51 of one basic unit 20 in direction R1 (the direction of arrow R1) along axis CL1 is referred to as the "first end face 51," and the other end face 52 is referred to as the "second end face 52." For example, the contour of the first end face 51 and the contour of the second end face 52 are different, but are each symmetrical with respect to the reference line CL2. Therefore, the contour of the basic unit 20 is symmetrical with respect to the reference line CL2.

[0021] 1, the direction of action of energy (external force) on the energy absorbing member 10 is Er (the direction of the white arrow Er). Of the four basic units 20A to 20D, the first basic unit 20A is the one on which the energy acts first. The remaining three basic units 20B to 20D are arranged in a row relative to the first basic unit 20A in the energy acting direction Er, in the order of the second basic unit 20B, the third basic unit 20C, and the fourth basic unit 20D. The lengths L1 in the direction of the axis CL1 of each of the basic units 20A to 20D are, for example, all the same. When the energy absorbing member 10 is gradually deformed from the tip to gradually absorb energy, the lengths L1 in the direction of the axis CL1 of each of the basic units 20A to 20D can also be gradually increased in the order of the basic units 20A to 20D.

[0022] The first basic unit 20A and the second basic unit 20B adjacent to this first basic unit 20A constitute a first unit group 31A on the energy input side (energy action side) where energy first acts from the outside. The third basic unit 20C and the fourth basic unit 20D adjacent to this third basic unit 20C constitute a second unit group 31B on the non-energy input side where energy acts via the first and second basic units 20A and 20B.

[0023] The first and second basic units 20A and 20B are sometimes referred to as "basic units 20A and 20B on the energy input side" because energy is first applied from the outside. The third and fourth basic units 20C and 20D are sometimes referred to as "basic units 20C and 20D on the non-energy input side" because energy is applied from the outside via the first and second basic units 20A and 20B.

[0024] Among the basic units 20A to 20D, adjacent basic units 20A and 20B, and adjacent basic units 20C and 20D, are arranged in opposite directions in the direction R1 along the axis CL1. That is, the second end face 52 of the first basic unit 20A faces the second end face 52 of the second basic unit 20B. The first end face 51 of the second basic unit 20B faces the first end face 51 of the third basic unit 20C. The second end face 52 of the third basic unit 20C faces the second end face 52 of the fourth basic unit 20D.

[0025] The energy absorbing member 10 (each basic unit 20) has flanges 45, 45 at the open-side ends 42a, 42a of a pair of second plate portions 42, 42, that can be clamped into a press die. Each flange 45, 45 is integrally formed by a flat plate extending from the open-side ends 42a, 42a in a direction R3 away from each other. Each flange 45, 45 constitutes a press-molding end portion 46, 46 that can be clamped into a press die. In other words, the pair of press-molding end portions 46, 46 are integrally formed with the ends 42a, 42a, and have a pair of flanges 45, 45.

[0026] Next, the first basic unit 20A will be described in detail as a representative of the plurality of basic units 20A to 20D.

[0027] As shown in Figures 2 to 4, in the first basic unit 20A, at least portions 61, 61 (inclined surfaces 61, 61) of the pair of second plate portions 42, 42 extending from the opposite edges 41 a, 41 a of the first plate portion 41 to the open-side ends 42 a, 42 a of the pair of second plate portions 42, 42 are inclined in a direction R3 away from each other. The width between the opposite edges 41 a, 41 a of the first plate portion 41 is W1 (see Figure 3). The width between the open-side ends 42 a, 42 a of the pair of second plate portions 42, 42 is W2, which is larger than the width W1 between the opposite edges 41 a, 41 a. Thus, the pair of second plate portions 42, 42 have a pair of inclined surfaces 61, 61 that are wider than the width W1 between the opposite edges 41 a, 41 a of the first plate portion 41.

[0028] More specifically, the pair of second plate portions 42, 42 are composed at the first end face 51 of a pair of first inclined portions 62, 62 that are inclined so as to become wider from both edges 41a, 41a of the first plate portion 41 toward the open side end portions 42a, 42a, and first straight portions 63, 63 that are parallel to the reference line CL2 and extend from these first inclined portions 62, 62 to the open side end portions 42a, 42a.

[0029] On the other hand, the pair of second plate portions 42, 42 are composed, on the opposite second end face 52, of second straight portions 64, 64 that are parallel to the reference line CL2 from both edges 41a, 41a of the first plate portion 41 toward the open side ends 42a, 42a, and a pair of second inclined portions 65, 65 that incline so as to become wider from these second straight portions 64, 64 toward the open side ends 42a, 42a.

[0030] As a result, the pair of inclined surfaces 61, 61 are formed between the first inclined portions 62, 62 and the second inclined portions 65, 65 of the pair of second plate portions 42, 42.

[0031] As shown in Figures 2 and 3, the first end surface 51 of the first basic unit 20A has at least one first convex bent portion 71 protruding into the space 47 (external space 47) opposite the internal space 43, and at least one first concave bent portion 72 recessed toward the internal space 43 beyond the tip 71a of the first convex bent portion 71.

[0032] For example, two first convex bending portions 71 and three first concave bending portions 72 are integrally formed on the first end surface 51 of the first plate portion 41. The central first concave bending portion 72 is located on the reference line CL2 of the first basic unit 20A. The two first convex bending portions 71 are located between the first concave bending portion 72 and both edges 41 a of the first plate portion 41, respectively. The remaining two first concave bending portions 72 are located between the two first convex bending portions 71 and both edges 41 a of the first plate portion 41, respectively. The arrangement pitch of the two first convex bending portions 71 and the three first concave bending portions 72 is Pi. The height from the open-side ends 42 a of the second plate portions 42 to the tip 71 a of the first convex bending portion 71 is Hi.

[0033] Furthermore, for example, each of the second plate portions 42 has one first convex bent portion 71 and one first concave bent portion 72 integrally formed on the first end face 51. The first convex bent portion 71 is located at the boundary between the first inclined portions 62 and the first straight portions 63. The first concave bent portion 72 is located at the edge 41 a of the first plate portion 41.

[0034] As shown in Figures 2 and 4, the second end surface 52 of the first basic unit 20A has at least one second convex bent portion 81 protruding into the external space 47 and one second concave bent portion 82 recessed toward the internal space 43 beyond the tip 81a of the second convex bent portion 81.

[0035] For example, the first plate portion 41 has three second convex bent portions 81 and two second concave bent portions 82 integrally formed on the second end surface 52. The central second convex bent portion 81 is located on the reference line CL2 of the first basic unit 20A. The remaining two second convex bent portions 81 are located between the central second convex bent portion 81 and both edges 41 a, 41 a of the first plate portion 41 (see FIG. 2 ). Two second concave bent portions 82 are located individually between the three second convex bent portions 81. The arrangement pitch of the three second convex bent portions 81 and the two second concave bent portions 82 is Pi, the same as on the first end surface 51 side. The height from the open-side ends 42 a, 42 a of the second plate portions 42, 42 to the tips 81 a of the second convex bent portions 81 is Hi, the same as on the first end surface 51 side.

[0036] Furthermore, for example, each of the second plate portions 42 has one second convex bent portion 81 and one second concave bent portion 82 integrally formed on the second end face 52. The second convex bent portion 81 is located at the boundary between the open-side end portion 42 a of the second plate portion 42 and the second inclined portion 65. The second concave bent portion 82 is located at the boundary between the second straight portion 64 and the second inclined portion 65.

[0037] Figures 2 and 5A show the positional relationship between the two first convex bending portions 71 and three first concave bending portions 72 on the first end face 51 of the first plate portion 41, and the three second convex bending portions 81 and two second concave bending portions 82 on the second end face 52 of the first plate portion 41.

[0038] The second convex bent portions 81 on the second end face 52 are all biased by a pitch Pi around the axis CL1 relative to the first convex bent portion 71 on the first end face 51 in the clockwise direction R4 (the direction of the arrow R4) as viewed from the first end face 51. Furthermore, the second concave bent portions 82 on the second end face 52 are all biased by a pitch Pi around the axis CL1 relative to the first concave bent portion 72 on the first end face 51 in the clockwise direction R4 as viewed from the first end face 51. To summarize the above explanation, as shown in Figures 2 to 4, 5 and 5B, in the first basic unit 20A, the bent portions 81 and 82 on the first plate portion 41 are biased relative to the bent portions 71 and 72, for example, along the first plate portion 41. In the second plate portions 42, 42, the bent portions 81, 82 are biased relative to the bent portions 71, 72, for example, along the second plate portions 42, 42. The bias directions of all the bent portions 81, 82 relative to all the bent portions 71, 72 are the same.

[0039] Therefore, the second convex bent portion 81 and the second concave bent portion 82 are biased around the axis CL1 relative to the first convex bent portion 71 and the first concave bent portion 72. These adjacent bent portions 71, 72, 81, and 82 can be said to form the vertices of a parallelogram. Because the four bent portions (vertices) 71, 72, 81, and 82 are not located on the same plane, the quadrangle 90 connecting the bent portions 71, 72, 81, and 82 is sometimes referred to as a "virtual parallelogram 90." This virtual parallelogram 90 is biased around the axis CL1 by a pitch Pi. It is preferable that all virtual parallelograms 90 have the same shape, size, and inclination.

[0040] The imaginary parallelograms 90 formed on the pair of second plate portions 42 are arranged along the open end portions 42a of the pair of second plate portions 42, 42, over the entire surface of the pair of inclined surfaces 61, 61. The imaginary parallelograms 90 may be arranged only on a portion of the pair of second plate portions 42, 42. The imaginary parallelograms 90 may also be arranged over the entire surface of only one of the pair of inclined surfaces 61, 61.

[0041] 6 , one of two diagonals 91, 92 of the imaginary parallelogram 90 is referred to as the first diagonal 91 and the other as the second diagonal 92. The first diagonal 91 connects the first concave bent portion 72 on the first end face 51 with the second convex bent portion 81 on the second end face 52, and is inclined around the axis CL1 in the clockwise direction R4 when viewed from the first end face 51 side. The second diagonal 92 connects the first convex bent portion 71 on the first end face 51 with the second concave bent portion 82 on the second end face 52, and is aligned with the axis CL1.

[0042] At least a portion of the imaginary parallelogram 90 and the two diagonals 91, 92 of this imaginary parallelogram 90 are formed as mountain folds or valley folds. Of the two diagonals 91, 92, at least one diagonal 91 is preferably formed as a folded line. More specifically, the first convex bent portion 71 and the second convex bent portion 81 are connected by a mountain fold. The first concave bent portion 72 and the second concave bent portion 82 are connected by a valley fold. In Example 1, the second diagonal 92 is formed as, for example, a valley fold.

[0043] 2 to 4, when the first basic unit 20A is viewed from the direction along the axis CL1, it is preferable that each of the bent portions 71, 72, 81, and 82 has a V-shape. It is also preferable that each of the diagonal lines 91 and 92 has a V-shaped cross section. This is because such a shape makes the positions of the bent lines clearer, thereby improving the energy absorption performance of the energy absorbing member 10.

[0044] 2 and 3, the boundaries between both edges 41 a, 41 a of the first plate portion 41 and the pair of second plate portions 42, 42 are preferably configured as bent portions 101, 101 bent toward the open end 44 between the open end portions 42 a, 42 a of the second plate portions 42, 42. The bent portions 101, 101 serve as reference points when forming the convex bent portions 71, 81 and the concave bent portions 72, 82 in the first plate portion 41 and the pair of second plate portions 42, 42 by press molding.

[0045] As shown in Figures 3 and 4, it is preferable that the circumferential length (developed length) of the U-shaped cross section at the first end surface 51 and the circumferential length (developed length) of the U-shaped cross section at the second end surface 52 are the same.

[0046] As shown in Figures 1, 3 and 4, the energy absorbing member 10 (elongated object 32), i.e., the inner surface 21 and outer surface 22 of the first basic unit 20A, have each convex bend 71, 81 and each concave bend 72, 82, but are formed into a contour that does not have an undercut shape (negative angle shape) when press-molding the energy absorbing member 10.

[0047] In other words, the press molding die, which is composed of an upper die and a lower die, moves along the reference line CL2 in the direction of the outline arrow Ma (see FIGS. 3 and 4 ), and then moves in the opposite direction to remove the die (withdraw the die). If the die had an undercut shape (negative angle shape), it would not be possible to withdraw the die when removing it from the first basic unit 20A (energy absorbing member 10) after molding. By adopting the above-described configuration, the present invention achieves a contour that does not have an undercut shape.

[0048] Specifically, the inner surface 21 of the first basic unit 20A (including the bent portions 71, 72, 81, and 82) is composed of an orthogonal surface perpendicular to the reference line CL2, a flat surface facing the open end 44, or a sloped surface facing the open end 44. Moreover, the outer surface 22 of the first basic unit 20A (including the bent portions 71, 72, 81, and 82) is composed of an orthogonal surface perpendicular to the reference line CL2, a flat surface facing the opposite side of the open end 44, or a sloped surface facing the opposite side. Therefore, the contours of both the inner surface 21 and the outer surface 22 of the first basic unit 20A (energy absorbing member 10) do not have an undercut shape (negative angle shape).

[0049] 2, the inclined surfaces 61 of each second plate portion 42 are inclined so that the width between the open end portions 42a of the second plate portion 42 is wider than the width between the both edges 41a of the first plate portion 41. Moreover, the imaginary parallelogram 90 formed on each second plate portion 42 is disposed on each inclined surface 61 along the open end portions 42a of the second plate portion 42.

[0050] Furthermore, as shown in Figures 1, 3 and 4, the orientation of the energy absorbing member 10, which has a U-shaped cross section, the size, material, and plate thickness of the energy absorbing member 10, the ratio of the widths W1 and W2 to the height Hi, the size, number, and arrangement of the bent portions 71, 72, 81, and 82, the arrangement pitch Pi, and the width Wd of each flange 45, 45 are set to optimal conditions in consideration of the direction, point of action, and magnitude of the energy (external force) acting on the energy absorbing member 10.

[0051] To summarize Example 1, as shown in Figures 2 and 5, the basic unit 20 is a press-formed product. The inner surface 21 and outer surface 22 of the basic unit 20, which are configured with a U-shaped cross section, have contours that do not have undercut shapes in the direction along the reference line CL2 (i.e., contours that allow movement of the press-forming die). The first plate portion 41 and the pair of second plate portions 42, 42 each have an imaginary parallelogram 90 that is biased about the axis CL1 from the first end face 51 to the second end face 52. At least one of the two diagonals 91, 92 of the imaginary parallelogram 90 is formed by a broken line.

[0052] Next, the operation of the energy absorbing member 10 will be described. As shown in FIGS. 1 and 2, adjacent basic units 20A and 20B, and adjacent basic units 20C and 20D, are arranged in opposite directions in a direction R1 (indicated by arrow R1) along the axis CL1. For example, the second convex bent portions 81 of the first and second basic units 20A and 20B face each other in the direction of the axis CL1. The first convex bent portions 71 of the second and third basic units 20B and 20C face each other in the direction of the axis CL1. The second convex bent portions 81 of the third and fourth basic units 20C and 20D face each other in the direction of the axis CL1. The imaginary parallelograms 90 and second diagonals 92 arranged in each of the basic units 20A to 20D are formed as broken lines. The imaginary parallelograms 90 are biased around the axis CL1.

[0053] Energy (external force) acting on the energy absorbing member 10 in the direction of action Er is transmitted in the order of the first basic unit 20A, the second basic unit 20B, the third basic unit 20C, and the fourth basic unit 20D. Each of the basic units 20A to 20D is folded along multiple fold lines. As a result, each of the basic units 20A to 20D is folded spirally around the axis CL1 while inverting relative to each other, using each fold line as a reference. As a result, the energy absorbing member 10 is crushed between both end faces 10a, 10b in the longitudinal direction R1 (direction along the axis CL1) while inverting spirally, and is folded so that the side surfaces are in close contact with each other, thereby absorbing energy.

[0054] Furthermore, the energy absorbing member 10 (each basic unit 20) is configured to have a hat-shaped cross section by integrating the flanges 45, 45 of the press-molding ends 46, 46 with the open ends (ends 42 a, 42 a) of the U-shaped cross section. By supplementing the rigidity of the open ends of the energy absorbing member 10, which has a U-shaped cross section, with the flanges 45, 45, it is possible to make the energy absorption of the energy absorbing member 10 uniform.

[0055] Next, Examples 2 to 12 will be described. The basic configurations of Examples 2 to 13 are common to the energy absorbing member 10 of Example 1. The same reference numerals will be used for the parts common to the energy absorbing member 10 of Example 1, and detailed descriptions thereof will be omitted.

[0056] Example 2 An energy absorbing member 200 of Example 2 will be described with reference to Figures 7A and 7B. Figure 7A corresponds to Figure 1. Figure 7B corresponds to Figures 3 and 4. The energy absorbing member 200 of Example 2 is characterized by being configured by stacking two elongated objects 32 of Example 1 face to face to form a cylindrical shape. Specifically, the energy absorbing member 200 is configured as a cylindrical member by overlapping two elongated objects 32, 32 with U-shaped cross sections, i.e., the open ends 44, 44 (openings 44, 44) of two basic units 20, 20. The flanges 45, 45 are joined to each other by multiple spot welds 201. As a result, the open end portions 42a, 42a of a pair of second plate portions 42, 42 of the two basic units 20, 20 are joined to each other between the first end surface 51 and the second end surface 52. The position of the spot weld 201 is preferably set, for example, at a midpoint between the first end surface 51 and the second end surface 52 .

[0057] The energy absorbing member 200 according to the second embodiment is configured as a cylindrical member, and therefore can efficiently absorb a larger amount of energy. Furthermore, the energy absorbing member 200 can exhibit the same effects as the energy absorbing member 10 according to the first embodiment, in addition to the effects of the second embodiment.

[0058] <Example 3> An energy absorbing member 300 of Example 3 will be described with reference to Figure 8. Figure 8 corresponds to Figure 7B. The energy absorbing member 300 of Example 3 is characterized in that the energy absorbing member 200 of Example 2, i.e., a cylindrical member formed of two elongated objects 32, 32, is incorporated inside an outer cylinder 310. The outer cylinder 310 is configured, for example, by joining a pair of split outer cylinder halves 311, 312 together by a plurality of spot welds 313. The cross-sectional shape of the outer cylinder 310 is arbitrary, and may be, for example, rectangular.

[0059] The energy absorbing member 300 according to the third embodiment can absorb even greater energy by reinforcing the tubular member made up of the two elongated objects 32 with the outer cylinder 310. Furthermore, the energy absorbing member 300 may have a gap between the tubular member made up of the two elongated objects 32 and the outer cylinder 310 in order to promote deformation of the tubular member. Furthermore, in addition to the effects of the third embodiment, the energy absorbing member 300 can exhibit the same effects as the energy absorbing members 10 and 200 according to the first and second embodiments.

[0060] <Embodiment 4> An energy absorbing member 400 of embodiment 4 will be described with reference to Fig. 9. Fig. 9 corresponds to Figs. 2 to 4. The energy absorbing member 400 of embodiment 4 is characterized in that the press-molding end portions 46, 46 having flanges 45, 45 of the basic unit 20 of the elongated object 32 of embodiment 1 shown in Figs. 1 to 4 are eliminated (removed).

[0061] The energy absorbing member 400 according to the fourth embodiment can reduce the rigidity of the open end 42a of the second plate portion 42 by the amount corresponding to the absence of the flange 45. This makes it possible to achieve uniform energy absorption performance across the entire cross section of the energy absorbing member 400. Furthermore, in addition to the effects of the fourth embodiment, the energy absorbing member 400 can also achieve the same effects as the energy absorbing member 10 according to the first embodiment.

[0062] <Example 5> An energy absorbing member 500 of Example 5 will be described with reference to Figures 10A and 10B. Figure 10 corresponds to Figure 7A. Figure 10B corresponds to Figure 7B. The energy absorbing member 500 of Example 5 is characterized by being configured by stacking two elongated objects 32 of Example 4 face to face to form a cylindrical shape. Specifically, the energy absorbing member 500 is configured by overlapping the open ends 44 (openings 44) of two elongated objects 32, 32 with U-shaped cross sections, i.e., the two basic units 20, 20 shown in Figure 7B, with each other. The open end portions 42a, 42a of the second plate portions 42, 42 are joined to each other by a plurality of spot welds 511 between the first end face 51 and the second end face 52. The spot welds 511 are preferably positioned, for example, midway between the first end face 51 and the second end face 52. The ends 42a, 42a may be joined together by rivets, laser welding, or other known joining techniques instead of spot welding.

[0063] The energy absorbing member 500 according to the fifth embodiment is configured as a cylindrical member, and therefore can absorb a larger amount of energy. Furthermore, the energy absorbing member 500 can exhibit the same effects as the energy absorbing member 400 according to the fourth embodiment, in addition to the effects of the fifth embodiment.

[0064] Sixth Embodiment An energy absorbing member 600 of a sixth embodiment will be described with reference to Figures 11A and 11B. Figure 11A corresponds to Figure 5A. Figure 11B corresponds to Figure 5B. The energy absorbing member 600 of the sixth embodiment is characterized by the bent lines of two diagonals 91 and 92 of the imaginary parallelogram 90 of the first embodiment.

[0065] The first and second basic units 20A, 20B located on the energy input side of the elongated object 32 are formed as a bent line along a first diagonal line 91 inclined about the axis line CL1. The third and fourth basic units 20C, 20D located on the non-energy input side of the elongated object 32 opposite the energy input side are formed as a bent line along a second diagonal line 92 extending along the axis line CL1.

[0066] The energy absorbing member 600 according to the sixth embodiment can change the energy absorption characteristics between the energy input side and the non-energy input side. Furthermore, the energy absorbing member 600 can achieve the same effects as the energy absorbing member 10 according to the first embodiment, in addition to the effects of the fifth embodiment.

[0067] Seventh Embodiment An energy absorbing member 700 of a seventh embodiment will be described with reference to Fig. 12 to Fig. 14B. Fig. 12 corresponds to Fig. 1. Fig. 13A corresponds to Fig. 2. Fig. 14A corresponds to Fig. 3. Fig. 14B corresponds to Fig. 4.

[0068] The energy absorbing member 700 of Example 7 is characterized by the following two changes compared to the energy absorbing member 10 of Example 1 (see FIGS. 1 and 2 ). The first change is that the imaginary parallelogram 90 of Example 1 is changed to an imaginary parallelogram 790. The second change is that the press-molding end portions 46, 46 of Example 1 are changed to press-molding end portions 746, 746.

[0069] 12 and 13A, the energy absorbing member 700 of Example 7 has an imaginary parallelogram 790 in the first plate portion 41 and the second plate portions 42, 42, but does not have an imaginary parallelogram 790 in the press-molding end portions 746, 746. Therefore, it is easy to manufacture a mold for molding the energy absorbing member 700. In addition, the configuration of the energy absorbing member 700 of Example 7 is the same as that of the energy absorbing member 10 of Example 1 (see FIG. 1), and is configured into an inverted spiral origami structure by a plurality of basic units 20 (partial structures 20) formed continuously and integrally.

[0070] More specifically, the energy absorbing member 700 is made of a press-formed plate material, similar to the energy absorbing member 10. The energy absorbing member 700 uses, as a "basic unit 20," one member 20 having a U-shaped cross section, which is made up of a first plate portion 41 and a pair of second plate portions 42 extending in directions facing each other from both edges 41 a of the first plate portion 41. When the energy absorbing member 700 is viewed from the longitudinal direction R1, the pair of second plate portions 42 are formed in a so-called tapered shape that widens from both edges 41 a of the first plate portion 41 toward both open end portions 42 a. The inner surface 21 and outer surface 22 (see Figures 14A and 14B) of the basic unit 20, which is configured with a U-shaped cross section, have a contour that does not have an undercut shape (negative angle shape) in the direction along the reference line CL2, as in Example 1 above, that is, a contour that can be pulled out by moving the press molding die along the reference line CL2.

[0071] In other words, the press molding die consisting of the upper and lower dies moves along the reference line CL2 in the direction of the outline arrow Ma (see FIGS. 14A and 14B ), and then removes the die in the opposite direction. If the die had an undercut shape, it would be difficult to pull out the die when removing each basic unit 20 (energy absorbing member 10) after molding. The energy absorbing member 700 has the above-described configuration, resulting in a contour that does not have an undercut shape.

[0072] The energy absorbing member 700 (each basic unit 20) is provided with cuttable press-molding end portions 746, 746 at the open end portions 42 a, 42 a of the pair of second plate portions 42, 42. The pair of press-molding end portions 746, 746 are portions that can be clamped in a press mold when the energy absorbing member 700 (each basic unit 20) is press-molded using a plate material, and are continuous in the longitudinal direction R1 of the energy absorbing member 10 from the first end face 51 to the second end face 52 of the basic unit 20.

[0073] The pair of press-molding end portions 746, 746 are composed of a pair of extension portions 747, 747 extending from the open-side end portions 42 a, 42 a of the second plate portions 42, 42 toward the opposite side from the first plate portion 41, and a pair of flanges 45, 45 provided on the open-side end portions 747 a, 747 a of these extension portions 747, 747. The pair of extension portions 747, 747 (straight portions 747, 747) are flat plate-like portions formed integrally with the pair of second plate portions 42, 42, facing each other and parallel to the reference line CL2. The pair of flanges 748, 748 are flat plates formed integrally with the pair of extension portions 747, 747, and extend from the open-side end portions 747 a, 747 a of each extension portion 747 in a direction R3 away from each other.

[0074] 13B, the flange 748 is set to a size that allows it to be sandwiched between at least a press die. For example, the width Wd of the flange 748 (the length Wd from the open end 747a to the tip 748a of the flange 748) is a size that allows it to be sandwiched between the blank holder Mh and the die Md.

[0075] In this way, the energy absorption member 700 (each basic unit 20) is configured with a hat-shaped cross section by having press-molding end portions 746, 746 at the open end portions 42a, 42a of a pair of second plate portions 42, 42, which have at least a pair of flanges 748, 748 that can be clamped into a press mold.

[0076] Between the open ends 747a, 747a of the pair of extensions 747, 747 is an open end 44 that communicates with the internal space 43. This open end 44 plays the same role as the open end 44 of the first embodiment shown in FIG.

[0077] The width between the edges 41 a, 41 a of the first plate portion 41 is W1. The width between the open-side ends 42 a, 42 a of the pair of second plate portions 42, 42 is W2, which is larger than the width W1 between the edges 41 a, 41 a of the first plate portion 41. The width between the open-side ends 747 a, 747 a of the pair of extension portions 747, 747 is the same as the width W2 between the open-side ends 42 a, 42 a of the pair of second plate portions 42, 42. Note that the width W2 between the ends 747 a, 747 a may be set slightly larger in consideration of the demoldability of the mold.

[0078] Next, the first basic unit 20A will be described in detail as a representative of the plurality of basic units 20 (basic units 20A to 20D) that constitute the energy absorbing member 700.

[0079] The first plate portion 41 and the pair of second plate portions 42, 42 are biased about the axis CL1 from the first end face 51 toward the second end face 52. For example, the first plate portion 41 is biased about the axis CL1 in the direction of arrow R74 (counterclockwise direction R74 as viewed from the first end face 51 side). This direction of arrow R74 may be referred to as the "bias direction R74" as appropriate. For example, in the first end face 51 shown in FIG. 14A , the plate surface 41b of the first plate portion 41 is parallel to the surfaces (flange surfaces) of the pair of horizontal flanges 748, 748. In contrast, in the second end face 52 shown in FIG. 14B , the plate surface 41b of the first plate portion 41 is not parallel to the surfaces of the pair of flanges 748, 748. The pair of second plate portions 42, 42 are biased around the axis line CL1 in accordance with the bias of the first plate portion 41.

[0080] The width W1 between the edges 41 a, 41 a of the first plate portion 41 at the second end face 52 is, for example, the same as the width W1 between the edges 41 a, 41 a at the first end face 51. In other words, the width W1 of the first plate portion 41 is uniform from the first end face 51 to the second end face 52. The length L2 (see FIG. 13A ) from the edges 41 a, 41 a of the first plate portion 41 to both ends 42 a, 42 a on the open side of the second plate portions 42, 42 is uniform from the first end face 51 to the second end face 52. It is preferable that this length L2 be the same as the width W1 of the first plate portion 41.

[0081] The first plate portion 41 and the pair of second plate portions 42, 42 each have three "imaginary parallelograms 790" biased in a bias direction R74 about the axis CL1 from the first end face 51 to the second end face 52. One of the imaginary parallelograms 790 is located over the entire surface of the first plate portion 41. The remaining two imaginary parallelograms 790 are located over the entire surface of each of the second plate portions 42, 42.

[0082] 13A , 14A, and 14B, an example of a virtual parallelogram 790 on the first plate portion 41 will be described. Of the four vertices P1 to P4 of the virtual parallelogram 790, the first vertex P1 and the second vertex P2 are located on the first end face 51, and the third vertex P3 and the fourth vertex P4 are located on the second end face 52. On the second end face 52, the third vertex P3 is located on the front side in the deflection direction R74, and the fourth vertex P4 is located on the rear side. Therefore, the third vertex P3 is lower than the fourth vertex P4.

[0083] As described above, the parallelogram 790 has four vertices P1 to P4 that are not located on the same plane, and is therefore referred to as a virtual parallelogram 790. The four vertices P1 to P4 of the virtual parallelogram 790 in the first plate portion 41 are located at the four corners of the first plate portion 41. The virtual parallelogram 790 in the first plate portion 41 has a pair of virtual opposite sides consisting of the side between the first and second vertices P1, P2 and the side between the third and fourth vertices P3, P4, and a pair of virtual opposite sides consisting of the side between the first and fourth vertices P1, P4 and the side between the second and third vertices P2, P3.

[0084] Of the two diagonals 791, 792 of the imaginary parallelogram 790, one is referred to as the first diagonal 791 and the other is referred to as the second diagonal 792. The first diagonal 791 connects the first vertex P1 and the third vertex P3. The second diagonal 792 connects the second vertex P2 and the fourth vertex P4. For this reason, it can be considered that each of the diagonals 791, 792 is biased in the same direction as the bias direction R74 (direction of arrow R74) of the imaginary parallelogram 790 from the first end face 51 to the second end face 52.

[0085] The imaginary parallelograms 790, 790 of the pair of second plate portions 42, 42 are similar to the imaginary parallelogram 790 of the first plate portion 41, and therefore a description thereof will be omitted.

[0086] At least one of the two diagonals 791, 792 of the imaginary parallelogram 790 is formed by a broken line (a valley broken line or a mountain broken line). For example, of the two diagonals 791, 792, the first diagonal 791 is formed by a broken line consisting of a valley broken line. In other words, the second vertex P2 and the fourth vertex P4 are positioned higher than the first vertex P1 and the third vertex P3, so that the first diagonal 791 is formed as a valley broken line. Note that, to make the first diagonal 791 a mountain broken line, the hierarchical relationship of the first vertex P1 and the third vertex P3 with respect to the second vertex P2 and the fourth vertex P4 can be reversed.

[0087] Next, the operation of the energy absorbing member 700 will be described. As shown in Figures 12 and 13A, adjacent basic units 20A and 20B, and adjacent basic units 20C and 20D, are arranged in opposite directions in a direction R1 (indicated by arrow R1) along the axis CL1. For example, the imaginary parallelograms 790 of the first and second basic units 20A and 20B face each other in the direction of the axis CL1. The imaginary parallelograms 790 of the second and third basic units 20B and 20C face each other in the direction of the axis CL1. The imaginary parallelograms 790 of the third and fourth basic units 20C and 20D face each other in the direction of the axis CL1. The first diagonal 791 of each imaginary parallelogram 790 arranged in each of the basic units 20A to 20D is formed as a broken line. The imaginary parallelogram 790 is biased about the axis CL1.

[0088] Energy (external force) acting on the energy absorbing member 700 in the direction of action Er is transmitted in the order of the first basic unit 20A, the second basic unit 20B, the third basic unit 20C, and the fourth basic unit 20D. Each of the basic units 20A to 20D is folded along multiple folding lines (first diagonal line 791). As a result, each of the basic units 20A to 20D is folded spirally around the axis CL1 while inverting relative to each other, using each folding line as a reference. As a result, the energy absorbing member 700 is compressed between both end faces 10a, 10b in the longitudinal direction R1 (direction along the axis CL1) while inverting spirally, and is folded so that the side surfaces are in close contact with each other, thereby absorbing energy.

[0089] Furthermore, the energy absorbing member 700 (each basic unit 20) is configured to have a hat-shaped cross section by integrally configuring press-molded end portions 746, 746 with the open ends 42 a, 42 a of the U-shaped cross section (open end portions 42 a, 42 a of the second plate portions 42, 42). By supplementing the rigidity of the open ends 42 a, 42 a of the energy absorbing member 700, which has a U-shaped cross section, with the press-molded end portions 746, 746, it is possible to achieve uniform energy absorption of the energy absorbing member 700. Furthermore, in addition to the effects of Example 7, the energy absorbing member 700 can exhibit effects similar to those of the energy absorbing member 10 of Example 1 above.

[0090] Example 8 An energy absorbing member 800 of Example 8 will be described with reference to Figures 15A and 15B. Figure 15A corresponds to Figure 12. Figure 15B corresponds to Figure 14A. The energy absorbing member 800 of Example 8 is characterized by being configured by stacking two elongated objects 32 of Example 7 facing each other to form a cylindrical shape. Specifically, the energy absorbing member 800 is configured as a cylindrical member by overlapping two elongated objects 32, 32 with U-shaped cross sections, i.e., the open ends 44, 44 (openings 44, 44) of two basic units 20, 20. The flanges 748, 748 are joined to each other by multiple spot welding. As a result, the open end portions 747a, 747a of a pair of extension portions 747, 747 of the two basic units 20, 20 are joined to each other between the first end surface 51 and the second end surface 52. The position of the spot weld 801 is preferably set, for example, at a midpoint between the first end surface 51 and the second end surface 52 .

[0091] The energy absorbing member 800 of Example 8 is configured as a cylindrical member, and therefore can efficiently absorb larger amounts of energy. Furthermore, in addition to the effects of Example 8, the energy absorbing member 800 can also exhibit the same effects as the energy absorbing member 700 of Example 7.

[0092] 16A to 17D, an energy absorbing member 900 of Example 9 will be described. The energy absorbing member 900 of Example 9 is characterized in that it is configured into a cylindrical shape by stacking two energy absorbing members 700, 700 (Example 7) from which the press-molding end portions 746 shown in Figure 12 have been separated, facing each other.

[0093] Example 9 will be described in detail below. Fig. 16A shows the energy absorbing member 700 of Example 7 shown in Fig. 12 again. First, a manufacturing method for manufacturing the energy absorbing member 900 of Example 9 (see Fig. 17A) from the energy absorbing member 700 of Example 7 will be described.

[0094] First, as shown in FIG. 16A , a press-formed energy absorbing member 700 of Example 7 is prepared. This energy absorbing member 700 has press-formed end portions 746 that can be separated from the open-side end portions 42 a of the second plate portions 42 of each basic unit 20. Next, the press-formed end portions 746 are separated (cut away) from the open-side end portions 42 a of the second plate portions 42 of the energy absorbing member 700. As a result, as shown in FIG. 16B , the extension portions 747 can be separated from the end portions 42 a. Next, as shown in FIG. 16C , two energy absorbing members 700 are prepared, with the extension portions 747 separated from the end portions 42 a. Next, the open end portions 42 a of the second plate portions 42 of each energy absorbing member 700 are overlapped and joined together so as to face each other, resulting in a cylindrical energy absorbing member 900 as shown in Figures 17A to 17C.

[0095] As shown in FIGS. 17A to 17C, the end portions 42a, 42a are joined together to form an energy absorbing member 900 (tubular member 900) with a regular hexagonal cross section.

[0096] 17D , the joint structure between the end portions 42 a, 42 a is a joint structure using molten metal 901, for example, a joint structure using welding. The molten metal 901 is formed by melting and solidifying the end portions 42 a, 42 a, which are base materials (welding materials), and the weld metal.

[0097] The energy absorbing member 900 of Example 9 can be summarized as follows: In the energy absorbing member 900 of Example 9, the energy absorbing member 700 shown in Fig. 16A is used as the "energy absorbing half body 700," and a cylindrical member is formed by two energy absorbing half bodies 700, 700 shown in Fig. 16C. As shown in Fig. 16C and Fig. 17A, the two energy absorbing half bodies 700, 700 are configured such that press-molding end portions 746, 746 are separated from the pair of second plate portions 42, 42, and the openings (open end portions 42 a, 42 a) overlap and are joined together.

[0098] The energy absorbing member 900 of Example 9 is configured as a cylindrical member, and therefore can absorb a larger amount of energy. Furthermore, in addition to the effects of Example 9, the energy absorbing member 900 can also exhibit the same effects as the energy absorbing member 700 of Example 7.

[0099] Example 10 An energy absorbing member 1000 of Example 10 will be described with reference to Figures 18A and 18B. Figure 18A corresponds to Figure 17A. Figure 18B corresponds to Figure 17D. The energy absorbing member 1000 (tubular member 1000) of Example 10 is characterized in that the open-side ends 42a of the second plate portions 42 are joined together via metal strips 1001. For example, the metal strips 1001 are placed on the outer surfaces of the overlapping end portions 42a facing each other. The end portions 42a are joined to the strips 1001 by multiple spot welding. The other configurations are the same as those of the energy absorbing member 900 of Example 9 shown in Figures 16A to 17D, and therefore will not be described again. The energy absorbing member 1000 can exert the same effects as the energy absorbing member 900 of the ninth embodiment.

[0100] <Example 11> An energy absorbing member 1100 of Example 11 will be described with reference to Fig. 19. The basic structure of the energy absorbing member 1100 of Example 11 is the same as the energy absorbing member 900 (cylindrical member 900) shown in Fig. 17A and the energy absorbing member 1000 (cylindrical member 1000) shown in Fig. 18A. This energy absorbing member 1100 is characterized in that it constitutes a crash box 1120 for a vehicle.

[0101] More specifically, the energy absorbing member 1100 includes a crash box 1120 and a flange 1121 provided at the rear end of the crash box 1120. The crash box 1120 absorbs impact energy acting from the front of the vehicle body 1110.

[0102] The vehicle body 1110 includes a front side frame 1111 and a front bumper beam 1112 (bumper reinforcement 1112) located in front of the front side frame 1111. The crash box 1120 is interposed between the front bumper beam 1112 and a connecting plate 1111b at the tip 1111a of the front side frame 1111. The energy absorbing member 1100 can be attached to the front side frame 1111 by bolting a flange 1121 to the connecting plate 1111b at the tip 1111a of the front side frame 1111.

[0103] When an impact load acts on the front bumper beam 1112 from the front of the vehicle, the impact load acts from the front bumper beam 1112 to the crash boxes 1120. The crash boxes 1120 can absorb the impact energy by crushing themselves. Furthermore, in addition to the effects of Example 11, the energy absorbing member 1100 can also exhibit the same effects as the energy absorbing member 900 of Example 9 and the energy absorbing member 1000 of Example 10.

[0104] The configuration of the energy absorbing member 1100 of Example 11 can also be applied to the energy absorbing members 10, 200 to 1000 of Examples 1 to 10. In other words, the energy absorbing members 10, 200 to 1000 can be used as crash boxes for a vehicle.

[0105] 20A and 20B , an energy absorbing member 1200 according to a twelfth embodiment will be described. The energy absorbing member 1200 according to the twelfth embodiment is characterized in that it is housed in an outer tube 1210 extending in the same direction R1 (the direction of the arrow R1; the longitudinal direction R1 of the energy absorbing member 1200) as the energy absorbing member 1200, and is reinforced by the outer tube 1210. The outer tube 1210 is configured, for example, by joining a pair of split outer tube halves 1211 and 1212 together by multiple spot welding. The cross-sectional shape of the outer tube 1210 is arbitrary, for example, rectangular. This energy absorbing member 1200 can be used to form a crash box 1120, similar to the energy absorbing member 1100 according to the eleventh embodiment shown in FIG. 19 .

[0106] The energy absorbing member 1200 of Example 12 can absorb even greater energy by being reinforced with the outer tube 1210. Furthermore, in addition to the effects of Example 12, the energy absorbing member 1200 can also exhibit the same effects as the energy absorbing member 1100 of Example 11.

[0107] <Example 13> An energy absorbing member 1300 of Example 13 will be described with reference to Figure 21. Figure 21 corresponds to Figure 17A. The basic structure of the energy absorbing member 1300 of Example 13 is the same as that of the energy absorbing member 900 (cylindrical member 900) shown in Figure 17A and the energy absorbing member 1000 (cylindrical member 1000) shown in Figure 18A. The energy absorbing member 1300 (cylindrical member 1300) of Example 13 is characterized in that cylindrical bodies 1310, 1320 are provided on both end faces 10a, 10b of the cylindrical member 900 or the cylindrical member 1000 in the longitudinal direction R1.

[0108] These cylindrical bodies 1310, 1320 are located on the center line CL11 of the energy absorbing member 1300 in the longitudinal direction R1 and are joined to both end surfaces 10a, 10b. When viewed from the longitudinal direction R1, the cylindrical bodies 1310, 1320 are rectangular or circular. The cylindrical bodies 1310, 1320 can be attached to any position (e.g., a front side frame) of a vehicle frame (not shown) where impact acting in the axial direction (direction along the center line CL11) needs to be absorbed. For example, the energy absorbing member 1300 can be integrally provided midway through the front side frame to form a frame structure that forms part of the front side frame and absorb impact loads in the fore-and-aft direction of the vehicle body.

[0109] Furthermore, in addition to the effects of the thirteenth embodiment, the energy absorbing member 1300 can exhibit the same effects as the energy absorbing member 900 of the ninth embodiment and the energy absorbing member 1000 of the tenth embodiment.

[0110] The energy absorbing members 10, 200 to 1300 of the above-described embodiments will be summarized below.

[0111] 1 to 21. First, the energy absorbing members 10, 200 to 1300 use a single member 20, which is a press-formed "basic unit 20," as a U-shaped cross section, configured by a first plate portion 41 and a pair of second plate portions 42, 42 extending in directions facing each other from both edges 41 a, 41 a of the first plate portion 41.

[0112] Furthermore, the energy absorption members 10, 200 to 1300 have a straight line CL1 that passes through a space 43 (internal space 43) surrounded by the first plate portion 41 and the pair of second plate portions 42, 42 and extends in a direction along each plate surface 41b, 42b, 42b of the first plate portion 41 and the pair of second plate portions 42, 42 (in the direction of arrow R1), which is defined as the "axis CL1 of the basic unit 20," and a straight line CL2 that is perpendicular to this axis CL1 and extends in a direction that intersects with the plate surface 41b of the first plate portion 41 (in the direction of arrow R2), which is defined as the "reference line CL2 of the basic unit 20."

[0113] Furthermore, in the energy absorbing members 10, 200 to 1300, one end face 51 of the basic unit 20 in the direction along the axis CL1 (direction of arrow R1) is referred to as the "first end face 51," and the other end face 52 is referred to as the "second end face 52."

[0114] The inner surface 21 and the outer surface 22 (including the broken lines) of the basic unit 20, which is configured with a U-shaped cross section, have contours that do not have undercut shapes in the direction along the reference line CL2, i.e., contours that can be pushed out and pulled out of a press-molding die. The first plate portion 41 and the pair of second plate portions 42, 42 each have an imaginary parallelogram 90 (see FIGS. 2 and 6 ); 790 (see FIG. 12 ) that is biased about the axis CL1 from the first end face 51 to the second end face 52. At least one of the two diagonals 91, 92; 791, 792 of the imaginary parallelogram 90; 790 is configured by a broken line.

[0115] In this way, the basic unit 20 with a U-shaped cross section has imaginary parallelograms 90, 790 that are biased around the axis CL1 from the first end face 51 to the second end face 52 on the first plate portion 41 and the pair of second plate portions 42, 42, respectively, thereby constituting an inverted spiral energy absorption member 10, 200 to 1300 with good energy absorption performance. Moreover, both the inner surface 21 and the outer surface 22 of the basic unit 20 have contours that do not have an undercut shape (negative angle shape). Therefore, the energy absorption members 10, 200 to 1300 can be easily mass-produced by relatively low-cost press molding.

[0116] See Figures 1, 11A, 12, and 13B. Secondly, in the energy absorbing member 10, 600, 700 described above first, the basic unit 20 has press-molding end portions 46, 46; 746, 746 equipped with a pair of flanges 45, 45; 748, 748 that can be clamped between at least a press die (for example, a blank holder Mh and a die Md shown in Figure 13B) at open-side end portions 42a, 42a of a pair of second plate portions 42, 42, thereby being configured to have a hat-shaped cross section.

[0117] The flanges 45, 45; 748, 748 supplement the rigidity of the open end 44 of the energy absorbing member 10, 600, 700, which has a U-shaped cross section, thereby making it possible to uniformize the energy absorption properties of the energy absorbing member 10, 600, 700. Furthermore, the basic unit 20 is provided with a pair of flanges 45, 45; 748, 748 that can be clamped in a press die at least at the open end portions 42a, 42a of the pair of second plate portions 42, 42, so that the basic unit 20 can be easily mass-produced by press molding.

[0118] Please refer to Figures 5A, 5B, 6, 11A, 11B, and 12. Thirdly, in the energy absorbing members 10, 200 to 600 described above in the first and second aspects, the folded lines are valley folded lines or mountain folded lines.

[0119] Since the bent lines are valley bent lines or mountain bent lines, the energy absorbing members 10, 200 to 600 can be easily mass-produced by press molding at a relatively low cost.

[0120] See Figures 1, 5A, 5B, 11A, 11B, and 12. Fourth, in the energy absorbing members 10, 600, 700 described above in the first to third aspects, a pair of basic units 20 constitutes a unit group 31, and at least two sets of unit groups 31, 31 constitute a continuous elongated object 32 along the axis CL1. As shown in Figures 1 and 12, adjacent basic units 20, 20 have virtual parallelograms 90, 90 (see Figures 2 and 6); 790, 790 (see Figure 12) biased about the axis CL1 that are inclined in opposite directions.

[0121] Therefore, the energy absorbing member 10 can undergo reverse spiral deformation along the entire length of the elongated object 32 due to the bend lines, thereby increasing the amount of energy absorption.

[0122] See Figures 11A and 11B. A fifth example is the energy absorbing member 600 described above in the first example, in which one of the two diagonals 91, 92 of an imaginary parallelogram 90 is designated as a first diagonal 91 and the other as a second diagonal 92. The first diagonal 91 is easier to fold than the second diagonal 92 and is inclined about the axis CL1. See also Figure 1. Of the two unit groups 31A, 31B (elongated objects 32), the basic units 20A, 20B of the unit group 31A (first unit group 31A) located on the energy input side (the side indicated by the hollow arrow Er) are formed with the first diagonal 91 as a bent line. Of the two unit groups 31A, 31B (long objects 32), the basic units 20C, 20D of the unit group 31B (second unit group 31B) on the non-energy input side, which is located on the opposite side from the energy input side, are formed with the second diagonal line 92 as a broken line.

[0123] The first diagonal line 91, which is inclined about the axis CL1, is more easily folded than the second diagonal line 92, which is aligned with the axis CL1. Therefore, the energy absorption amount of the basic units 20A, 20B on the energy input side (the side in the energy acting direction Er) can be set smaller than the energy absorption amount of the basic units 20C, 20DB on the non-energy input side. Therefore, the energy absorbing member 600 that receives input energy from the energy input side gradually deforms from the tip (end face 10a) and can absorb energy while undergoing reverse spiral deformation at the folded line portion along its entire length.

[0124] See Figures 7A, 7B, 8, 10A, 15A, 17A, and 18A to 20B. Sixth, in the energy absorbing members 200, 300, 500, 800 to 1200 described above in the first to fifth sections, the openings 44 of two basic units 20, 20 with U-shaped cross sections overlap each other to form a cylindrical member. The open end portions 42a, 42a (see Figure 1) of a pair of second plate portions 42, 42 of the two basic units 20, 20 are joined to each other between a first end surface 51 and a second end surface 52.

[0125] Since the energy absorbing members 200, 300, 500, 800 to 1200 are cylindrical members, they can absorb sufficient energy even if the input energy (external force) is large. Moreover, since they are joined between the first end face 51 and the second end face 52 along the axis CL1, they can fully achieve the reverse spiral deformation effect.

[0126] See Figures 7A, 8, and 15A. Seventh, in the energy absorbing member 200, 300, 800 described in the sixth aspect, each basic unit 20 has a press-molding end portion 46, 46; 746, 746 equipped with a pair of flanges 45, 45; 748, 748 that can be clamped in a press mold, at the open end portion 42a, 42a of the pair of second plate portions 42, 42, thereby forming a hat-shaped cross section. The cylindrical member (energy absorbing member 200, 300, 800) is configured such that the flanges 45, 45; 748, 748 of the two basic units 20, 20 overlap and are joined to each other.

[0127] The two basic units 20, 20 are each configured with a hat-shaped cross section by including flanges 45, 45; 748, 748. By joining the flanges 45, 45; 748, 748 together, the energy absorbing members 200, 300, 800 are made into cylindrical members, which can adequately absorb larger input energy (external force).

[0128] 16A to 18B. Eighth, in the energy absorbing member 900, 1000 described in the sixth aspect, each basic unit 20 has press-molding end portions 746, 746 equipped with a pair of flanges 748, 748 that can be clamped in a press die, at the open-side end portions 42 a, 42 a of the pair of second plate portions 42, 42, thereby forming a hat-shaped cross section. The tubular member (energy absorbing member 900, 1000) is configured such that the press-molding end portions 746, 746 are separated from the open-side end portions 42 a, 42 a of the second plate portions 42, 42 of the two basic units 20, 20, and the open-side end portions 42 a, 42 a are joined together.

[0129] Because the energy absorbing members 900, 1000 are cylindrical members, they can absorb sufficient energy even if the input energy (external force) is large. Moreover, the press-molding end portions 746, 746 for easily press-molding the basic units 20, 20 are separated from each other, and the open end portions 42 a, 42 a are joined together, so that the energy absorbing members 900, 1000 made of cylindrical members can be easily obtained.

[0130] Please refer to Figures 17A to 18D. Ninth, in the energy absorbing members 900, 1000 described in the eighth aspect, the cylindrical member has a regular hexagonal cross section.

[0131] The energy absorbing members 900, 1000 are configured in a cylindrical shape with a regular hexagonal cross section by combining two basic units 20, 20 configured with a U-shaped cross section, which allows the energy absorbing members 900, 1000 to achieve both improved press formability and improved energy absorption performance.

[0132] 17A to 18B. A tenth aspect is the energy absorbing member 900, 1000 described in the eighth and ninth aspects, in which the end portions 42 a, 42 a on the open sides of the second plate portions 42, 42 are joined together by a molten metal 901 (see FIG. 17D) or by a metal strip 1001 (see FIG. 18B).

[0133] The open end portions 42 a of the second plate portions 42 can be joined together by joining with molten metal 901 or by joining via a metal strip 1001. Therefore, by combining two basic units 20, 20 made of press-formed products with a U-shaped cross section, cylindrical energy absorbing members 900, 1000 can be obtained relatively easily.

[0134] See Figures 1 to 18, 19, 20A and 20B. Eleventhly, the energy absorbing members 1100, 1200 (including the energy absorbing members 10, 200 to 1000) described above in the first to tenth aspects constitute a crash box 1120 that can be attached to a tip 1111a of a front side frame 1111 of a vehicle body 1110 (see Figure 19).

[0135] The crash box 1120 can be easily formed by the energy absorbing members 1100, 1200 (including the energy absorbing members 10, 200 to 1000) made of press-molded products.

[0136] See Figures 8, 20A and 20B. Twelfthly, the energy absorbing members 1100, 1200 (including the energy absorbing members 10, 200 to 1000) described above in the first to eleventh sections are housed in an outer cylinder 1210 (including the outer cylinder 310 in Figure 8) that extends in the same direction R1 (the direction of arrow R1) as the energy absorbing members 1100, 1200, and are thereby reinforced by the outer cylinder 1210.

[0137] By reinforcing the energy absorbing members 1100 and 1200 (including the energy absorbing members 10, 200 to 1000) made of press-molded products with an outer cylinder 1210 (including the outer cylinder 310 in FIG. 8), it is possible to absorb even greater energy.

[0138] It should be noted that the present invention is not limited to the examples as long as the functions and effects of the present invention are achieved. For example, any two or more of the examples may be arbitrarily combined.

[0139] The energy absorbing members 10, 200 to 1300 of the present invention are suitable for use in the side sills of a vehicle body, the battery housing of an electric vehicle, the crash box at the front of the vehicle body, and the front side frame.

[0140] 10,200,300,400,500,600,700,800,900,1000,1100,1200,1300...Energy absorbing member, 10a, 10b...Longitudinal end face of energy absorbing member, 20...Basic unit, 20A, 20B...Basic unit on energy input side, 20C, 20D...Basic unit on non-energy input side, 21...Inner surface of first basic unit, 22...Outer surface of first basic unit, 32...Long object, 41...First plate portion, 41a...Edge of first plate portion, 41b...Plate surface of first plate portion, 42...Second plate portion, 42a...Open side end, 42b...Plate surface of second plate portion, 43...Space (internal space), 44...Open end, 45...Flange, 46...External space (opposite to internal space 43), 51...First end surface, 52...Second end surface, 61...Inclined surface (at least a part of the second plate portion), 90...Imaginary parallelogram, 91...First diagonal, 92...Second diagonal, 101...Bent portion, 201...Spot welded portion, 310...Outer cylinder, 511...Spot welded portion, 790...Imaginary parallelogram, 791...First diagonal, 792...Second diagonal, 801...Spot welded portion, 901...Molten metal, 1001...Metal strip plate, 1111...Front side frame, 1111a...Tip, 1120...Crash box, 1210...Outer cylinder, CL1...Axis, CL2...Reference line, Er...Direction of action of energy (external force), R1...Longitudinal direction of energy absorbing member, R2...direction intersecting the plate surface of the first plate portion, R3...direction moving away from each other, R4, R74...direction along the plate surface of the first plate portion when viewed from the first end face side, W1...width between both edges of the first plate portion, W2...width between the ends on the open side of the second plate portion, Wd...width of the flange.

Claims

1. A basic unit is a press-molded product consisting of a member having a U-shaped cross section formed by a first plate portion and a pair of second plate portions extending from both edges of the first plate portion in a direction facing each other, a straight line passing through a space surrounded by the first plate portion and the pair of second plate portions and extending in a direction along each plate surface of the first plate portion and the pair of second plate portions is defined as the axis of the basic unit, a straight line perpendicular to the axis and extending in a direction intersecting the plate surface of the first plate portion is defined as the reference line of the basic unit, one end surface of the basic unit in the direction along the axis is defined as a first end surface, and the other end surface is defined as a second end surface, and the inner and outer surfaces of the basic unit formed in the U-shaped cross section have a contour that does not have an undercut shape in the direction along the reference line, an energy absorbing member, wherein the first plate portion and the pair of second plate portions each have an imaginary parallelogram biased around the axis from the first end face to the second end face, and at least one of two diagonals of the imaginary parallelogram is formed by a broken line.

2. An energy absorbing member as described in claim 1, wherein the basic unit is configured with a hat-shaped cross section by having a press-molding end portion at the open end of the pair of second plate portions, the press-molding end portion having at least a pair of flanges that can be clamped into a press mold.

3. The energy absorbing member according to claim 2, wherein the fold lines are valley fold lines or mountain fold lines.

4. An energy absorbing member as described in claim 3, wherein a unit group is formed by a pair of said basic units, at least two of said unit groups form a long object that is continuous along said axis, and adjacent said basic units have virtual parallelograms that are biased around said axis with their inclination directions opposite to each other.

5. An energy absorbing member as described in claim 4, wherein one of the two diagonals of the virtual parallelogram is a first diagonal and the other is a second diagonal, the first diagonal is inclined around the axis so as to be easier to fold than the second diagonal, the basic units of the unit groups located on the energy input side of the two unit groups are formed with the first diagonal as the folded line, and the basic units of the unit groups on the non-energy input side of the two unit groups are formed with the second diagonal as the folded line.

6. An energy absorbing member as described in claim 1, wherein openings of two of the basic units having a U-shaped cross section overlap each other to form a tubular member, and the open ends of the pair of second plate portions of the two basic units are joined to each other between the first end face and the second end face.

7. An energy absorbing member as described in claim 6, wherein the basic unit is configured with a hat-shaped cross section by having a press molding end portion at the open end of the pair of second plate portions, the end portion having at least a pair of flanges that can be clamped into a press mold, and the tubular member is configured such that the flanges of each of the two basic units overlap and are joined to each other.

8. The energy absorbing member described in claim 6, wherein the basic unit is configured with a hat-shaped cross section by having a press-molding end portion at the open end of the pair of second plate portions, the press-molding end portion having at least a pair of flanges that can be clamped into a press die, and the tubular member is configured such that each of the press-molding ends is separated from the open end portion of each of the second plate portions of the two basic units, and the open end portions are joined together.

9. The energy absorbing member of claim 8, wherein said tubular member has a regular hexagonal cross-sectional shape.

10. An energy absorbing member as described in claim 8, wherein the joint structure between the open ends of each of the second plate portions is a joint structure using molten metal or a joint structure using a metal strip.

11. The energy absorbing member according to claim 6, wherein the energy absorbing member constitutes a crash box that can be attached to a tip of a front side frame of a vehicle body.

12. An energy absorbing member according to claim 11, wherein the energy absorbing member is housed in an external cylinder extending in the same direction as the energy absorbing member, and is reinforced by the external cylinder.

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