Shock absorption member

Abstract

This shock absorption member has a configuration in which a breaking start-point is provided in a hollow tube, or a configuration in which a breaking start-point is provided in a reinforcement. The shock absorption member further includes a pair of reinforcement parts that extend along an extension direction of each ridge section of the hollow tube, each reinforcement part being provided at a position adjacent to the ridge section on an outer surface of a side wall part when the hollow tube is viewed in a cross section perpendicular to the longitudinal direction at a position of a start point section.

Description

Impact absorbing material

[0001] The present invention relates to an impact absorbing member. This application claims priority to Japanese Patent Application No. 2023-179418 filed on October 18, 2023, and Japanese Patent Application No. 2023-179462 filed on October 18, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, fuel economy regulations have become stricter around the world, and automakers are pushing for lighter vehicle bodies. At the same time, vehicle crash safety standards have also become stricter, requiring both weight reduction and improved crash performance. Furthermore, in response to fuel economy regulations in various countries and the trend toward carbon neutrality, the electrification of vehicle power sources is progressing. Compared to conventional vehicle structures with internal combustion engines, the electrification of power sources has led to changes in vehicle structure, such as increased vehicle weight and a smaller engine compartment. One example of this is the adoption of a short nose for the front of the vehicle. To maintain high crash safety while adopting a short nose, a structure that can achieve high energy absorption efficiency even with a small deformation stroke is required.

[0003] In particular, structures that can dramatically improve energy absorption performance are required for parts such as front side members and rear side members, which actively undergo plastic deformation to absorb collision energy during a vehicle collision. Furthermore, because these parts play a role in minimizing the external forces applied to occupants during a collision, a deformation mode that can shorten the deformation stroke while suppressing sudden load fluctuations is ideal.

[0004] There are two types of deformation modes of components for absorbing impact energy: bellows deformation and serpentine deformation (folding deformation). Bellows deformation refers to a deformation in which out-of-plane deformation occurs on all side surfaces of a component, but the center line of the component in the longitudinal direction is barely bent. On the other hand, serpentine deformation refers to a deformation in which bending occurs at multiple locations along the component's longitudinal direction, with out-of-plane deformation occurring primarily on one of the side surfaces of the component, and the center line of the component in the longitudinal direction also bending. Comparing the two deformation modes, bellows deformation can absorb a greater amount of impact energy than serpentine deformation if the impact force is applied from an ideal direction. However, since the input direction of the impact force is not limited to one direction, for example, if the impact force is applied obliquely to the longitudinal direction of the component, the energy absorption capacity of bellows deformation is significantly reduced. In contrast, serpentine deformation (folding deformation) can flexibly respond to the direction of impact force application to a certain extent, allowing for stable absorption of impact energy.

[0005] Examples of structures for absorbing collision energy include those disclosed in Patent Documents 1 and 2 listed below.

[0006] Japanese Patent Application Publication No. 2004-276031 International Publication No. 2018 / 190312

[0007] Patent Document 1 discloses a bent member obtained by bending a metal plate, in which a ridgeline portion of at least one bent portion formed by bending the bent member and / or a region near the ridgeline portion are provided with an overlay weld for increasing the thickness and strength of the portion and increasing the amount of collision energy absorption. Here, the "near the ridgeline portion" is explained as "an area within 20 mm in a direction perpendicular to the direction in which the ridgeline portion is formed. This is because, when a press-bent member is crushed by impact stress due to a collision, the highest impact stress acts in this area, and therefore it is necessary to increase the amount of collision energy absorption in this area."

[0008] On the other hand, Patent Document 2 discloses an automotive structural component including a press-formed component made of a single steel plate and a reinforcing member fixed to the press-formed component, the press-formed component including two vertical wall portions and a top plate portion connecting the two vertical wall portions, the reinforcing member being an L-shaped member including a first plate-shaped portion and a second plate-shaped portion, the first plate-shaped portion being fixed to the vertical wall portions so that the second plate-shaped portion protrudes outward from the vertical wall portions along the top plate portion, and it is described that this automotive structural component "provides a structural component with excellent characteristics in a three-point bending test."

[0009] The bent member described in Patent Document 1 absorbs collision energy by collapsing into a bellows shape, as is clear from the description that "the press-bent member is crushed by impact stress caused by a collision." As described above, bellows deformation absorbs a large amount of energy for collision energy from an ideal direction, but the absorption amount is significantly reduced for collision energy from other directions. Furthermore, the automotive structural member described in Patent Document 2 absorbs collision energy by bending and deforming in response to external forces from the side, as is clear from the description that "a structural member has excellent characteristics in a three-point bending test."

[0010] As mentioned above, impact absorbing components are increasingly required to not only suppress sudden load fluctuations but also to shorten their deformation stroke. Therefore, it is desirable to reliably achieve a high amount of collision energy absorption with a shorter deformation stroke than the bent-shaped component of Patent Document 1, which is based on bellows deformation. Furthermore, Patent Document 2 targets components such as side sills. Therefore, it is difficult for three-point bending deformation to absorb the large collision energy experienced by front side members and rear side members.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an impact absorbing member that can obtain a high amount of collision energy absorption with a short deformation stroke while suppressing sudden load fluctuations.

[0012] To solve the above problems, the present invention employs the following measures. (1a) One aspect of the present invention is an impact-absorbing component having a hollow tube that is long along one direction, and that, when viewed in a cross section perpendicular to the longitudinal direction, has a bent inner wall portion and a pair of side wall portions that are connected to the bent inner wall portion via a pair of ridge lines, the impact-absorbing component comprising: a folding trigger provided in the hollow tube and configured to set a folding start point on the bent inner wall portion at a midpoint in the longitudinal direction of the hollow tube; and a pair of reinforcing portions that extend along the extension direction of the ridge lines and are provided adjacent to the ridge lines on the outer surfaces of each of the side wall portions when viewed in a cross section of the hollow tube perpendicular to the longitudinal direction at the folding start point. More specifically, the pair of reinforcing portions are provided in positions that are in contact with the ridge lines and excluding the top wall portion, and extend along the extension direction of the ridge lines.

[0013] When the impact absorbing member described in (1a) above receives collision energy along its longitudinal direction, it bends and deforms at the position of the bending origin, with the outer surface of the bending inner wall portion facing inward. Each reinforcing portion, which absorbs collision energy as a result of this bending deformation, is positioned adjacent to each ridge line and extends along the extension direction of each ridge line. These reinforcing portions can suppress the increase in maximum load of the impact absorbing member compared to when the bending inner wall portion itself is reinforced. Meanwhile, most of the collision energy is absorbed by each side wall portion buckling and deforming into an "L" shape at the position of the bending origin. However, the reinforcement makes each side wall portion less likely to bend into an "L" shape. This allows for a gradual drop in load after the occurrence of maximum load in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram). As a result, the load integral value after the occurrence of maximum load in the FS diagram can be increased, thereby increasing the amount of energy absorption.

[0014] (2a) In the impact absorbing member described in (1a) above, each of the reinforcing portions may be a strip-shaped plate material that is joined to at least the outer surface of each of the side wall portions and that is long along the extending direction. According to the impact absorbing member described in (2a) above, by adjusting the length and width of the plate material, the reinforcement range and the reinforcement degree in the pair of side wall portions can be easily and accurately adjusted.

[0015] (3a) In the impact absorbing member described in (1a) or (2a) above, the average length of each of the reinforcing portions along the extension direction may be at least twice the buckling range length of each of the side wall portions at the position of the folding start point. According to the impact absorbing member described in (3a) above, the rise of the secondary peak load in the FS diagram can be accelerated. To explain this, first, the portion of each side wall portion that is bent into an "L" shape due to buckling deformation gradually closes. Here, since the length of each reinforcing portion is at least twice the buckling range length, when the buckling deformation progresses and the "L" shape is completely closed, a pair of ridge portions that are connected across the "L" buckling range can be reliably abutted against each other. This abutment of the ridge portions causes the rise of the secondary peak load. Here, since each side wall portion is pre-reinforced by a reinforcing portion, the buckling range is localized (the area that buckles and displaces into an "L" shape is smaller than when there is no reinforcing portion). Therefore, in the case of small buckling deformation, the pair of ridges begins to collide with each other earlier than in the case of large buckling deformation, and the rise time of the secondary peak load is accelerated. Furthermore, because each side wall portion is reinforced by a reinforcing portion, the pair of ridges continues to collide with each other strongly. As a result, the drop in the secondary peak load can be delayed. Therefore, the rise of the secondary peak load in the FS diagram can be accelerated and its drop can be delayed, making it possible to increase the load integral value. This results in increased energy absorption.

[0016] (4a) In the impact absorbing member described in (1a) or (2a) above, each of the reinforcing portions may be provided only on each of the side wall portions when viewed in a cross section perpendicular to the longitudinal direction. According to the impact absorbing member described in (4a) above, since the reinforcement is performed excluding the inner wall portion and the ridge portion, the energy absorption amount can be increased without significantly increasing the maximum load (primary peak load). Therefore, sudden load fluctuations can be most effectively suppressed.

[0017] (5a) The impact absorbing member described in (4a) above may have the following configuration: the hollow tube includes a hat-shaped member having a top wall portion that is the bent inner wall portion and side wall portions that are connected to both sides of the top wall portion via the ridge portions, and a plate-shaped member joined to the hat-shaped member to form a closed cross section; the height dimension H between the top wall portion and the plate-shaped member is 50 mm to 200 mm, the width dimension W of the top wall portion is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-shaped member is 0.8 mm to 3.2 mm; and the length L along the extension direction of each of the reinforcing portions is 70 mm to 500 mm, and the width dimension w in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. The impact absorbing member described in (5a) above can more reliably achieve the effects described in (1a) above.

[0018] (6a) In the impact absorbing member described in (1a) or (2a) above, each of the reinforcing portions may be provided only in an area from each of the side wall portions to each of the ridge portions when viewed in a cross section perpendicular to the longitudinal direction. According to the impact absorbing member described in (6a) above, since the reinforcement is performed excluding the inner wall portion of the bend, the amount of energy absorption can be increased while suppressing an excessive increase in the maximum load (primary peak load). Therefore, sudden load fluctuations can be reliably suppressed.

[0019] (7a) The impact absorbing member described in (6a) above may have the following configuration: the hollow tube includes a hat-shaped member having a top wall portion that is the bent inner wall portion and side wall portions that are connected to both sides of the top wall portion via the ridge portions, and a plate-shaped member joined to the hat-shaped member to form a closed cross section; the height dimension H between the top wall portion and the plate-shaped member is 50 mm to 200 mm, the width dimension W of the top wall portion is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-shaped member is 0.8 mm to 3.2 mm; the length L of each of the reinforcing portions along the extension direction is 70 mm to 500 mm, and the width dimension w of the portion that overlaps with each of the side wall portions as viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. The impact absorbing member described in (7a) above more reliably achieves the effects described in (1a) above.

[0020] (8a) In the impact absorbing member described in (1a) or (2a) above, the bending trigger may include a first bead provided on the pair of ridges of the hollow tube at the position of the bending start point. According to the impact absorbing member described in (8a) above, when impact energy is received along the longitudinal direction, the bending inner wall portion is bent and deformed with the position of the first bead as the bending start point.

[0021] (9a) In the impact absorbing member described in (1a) or (2a) above, the folding trigger may include a second bead provided at the position of the folding origin of the bending inner wall portion and extending in a direction intersecting the longitudinal direction. According to the impact absorbing member described in (9a) above, when collision energy is received along the longitudinal direction, the bending inner wall portion is folded and deformed with the position of the second bead as the folding origin.

[0022] (10a) In the impact absorbing member described in (1a) or (2a) above, the folding trigger may include a through hole provided at the position of the folding origin of the bending inner wall portion. According to the impact absorbing member described in (10a) above, when collision energy is received along the longitudinal direction, the bending inner wall portion is folded and deformed with the position of the through hole as the folding origin.

[0023] (11a) In the impact absorbing member described in (1a) or (2a) above, when the hollow tube is viewed along the longitudinal direction, a portion including the break origin portion may be defined as a second portion, one side of the second portion as a first portion, and the other side of the second portion as a third portion, the break trigger may be provided in each of the first portion and the third portion and may include a third bead that is long along the longitudinal direction. According to the impact absorbing member described in (11a) above, the bending inner wall portion bends and deforms with the second portion as the break origin portion, the second portion having a bending strength relatively weaker than the first portion and the third portion reinforced by the third bead.

[0024] (12a) In the impact absorbing member described in (1a) or (2a) above, when the hollow tube is viewed along the longitudinal direction, a portion including the break origin portion may be defined as a second portion, one side of the second portion as a first portion, and the other side of the second portion as a third portion, the break trigger may include at least one of a difference in plate thickness and a difference in material strength between the second portion and the first portion and the third portion. According to the impact absorbing member described in (12a) above, the bending inner wall portion is bent and deformed at the break origin portion at the second portion, which has a bending strength relatively weaker than the first portion and the third portion due to at least one of the difference in plate thickness and the difference in material strength.

[0025] (13a) In the impact absorbing member described in (1a) or (2a) above, the bending trigger may include a bending shape of the hollow tube in which the outer surface of the bending inner wall portion is concave at the position of the bending start point. According to the impact absorbing member described in (13a) above, the bending inner wall portion is bent and deformed with the position of the concave surface as the bending start point.

[0026] (14a) In the impact absorbing member described in (1a) or (2a) above, when the hollow tube is viewed along the longitudinal direction, a portion including the break origin portion may be defined as a second portion, one side of the second portion as a first portion, and the other side of the second portion as a third portion, the break trigger may include a filler filled in each of the first portion and the third portion excluding the second portion. According to the impact absorbing member described in (14) above, the bending inner wall portion is bent and deformed with the second portion as the break origin portion, the second portion having a bending strength relatively weaker than the first portion and the third portion reinforced with the filler.

[0027] (15a) The impact absorbing member described in (1a) or (2a) above may have the following configuration: the hollow tube has opposing wall portions disposed opposite the bent inner wall portion and connected to the pair of side wall portions via a pair of other ridge portions; and further includes other folding triggers provided on the hollow tube and configured to set other folding start points on the opposing wall portions at other intermediate positions in the longitudinal direction of the hollow tube, and a pair of other reinforcing portions extending along the extension direction of the other ridge portions and provided at positions adjacent to the other ridge portions on the outer surfaces of the side wall portions when the hollow tube is viewed in a cross section perpendicular to the longitudinal direction at the positions of the other folding start points. According to the impact absorbing member described in (15a) above, the folding start point and the other folding start point are disposed on the bent inner wall portion and the opposing wall portion facing each other, and are disposed so as to be spaced apart when viewed in the longitudinal direction. When this impact absorbing member receives collision energy along its longitudinal direction, it bends with the outer surface of the inner wall portion bent on the inside at the positions of the folding start points, and with the outer surface of the opposing wall portion bent on the inside at the positions of the other folding start points. As a result, the impact absorbing member bends in a Z-shape. At this time, the reinforcing portion and the other reinforcing portion share the burden of absorbing the collision energy, resulting in a higher amount of collision energy absorption.

[0028] (1b) Another aspect of the present invention is an impact absorbing component comprising a hollow tube that is long in one direction and a reinforcement fixedly disposed inside the hollow tube, wherein the hollow tube has, when viewed in a cross section perpendicular to the longitudinal direction, a bending inner wall portion and a pair of side wall portions that are connected to the bending inner wall portion via a pair of ridge lines, wherein the reinforcement has at least one of a vertical plate that has one end joined to the bending inner wall portion and a horizontal plate that connects the pair of side wall portions, and a folding trigger configured to set a folding start portion on the bending inner wall portion of the hollow tube at a midpoint in the longitudinal direction; and the hollow tube has a pair of reinforcing portions on each of the side wall portions that extend along the extension direction of each ridge line portion and are fixedly disposed adjacent to each ridge line portion.

[0029] When the impact absorbing member described in (1b) above receives impact energy along its longitudinal direction, both the hollow tube and the reinforcement bend and deform integrally at the position of the break point. That is, the hollow tube absorbs impact energy by bending and deforming with the outer surface of the bent inner wall portion facing inward. Here, each reinforcing portion is arranged adjacent to each ridge line portion and extends along the extension direction of each ridge line portion. These reinforcing portions can suppress the increase in maximum load of the impact absorbing member compared to when the bent inner wall portion is reinforced. Meanwhile, most of the impact energy absorbed by the deformation of the hollow tube is absorbed by the buckling deformation of each side wall portion into an "L" shape at the position of the bent inner wall portion. However, the reinforcement makes each side wall portion less likely to bend into an "L" shape. Therefore, the drop in load after the occurrence of maximum load in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram) can be made gentler. As a result, the load integral value after the occurrence of maximum load in the FS diagram can be increased, thereby increasing the amount of energy absorption. In addition, the reinforcement also bends and deforms in response to the bending deformation of the hollow tube, further increasing the amount of energy absorption.

[0030] (2b) In the impact absorbing member described in (1b) above, the reinforcing portions may be long strip-shaped plate members joined to at least the outer surfaces of the side wall portions, respectively, along the extending direction. According to the impact absorbing member described in (2b) above, by adjusting the length and width of the plate members, the reinforcement range and the reinforcement degree in the pair of side wall portions can be easily and accurately adjusted.

[0031] (3b) In the impact absorbing member described in (1b) or (2b) above, the average length of each of the reinforcing portions along the extension direction may be at least twice the buckling range length of each of the side wall portions at the position of the folding start point. According to the impact absorbing member described in (3b) above, the rise of the secondary peak load in the FS diagram can be accelerated. To explain this, first, the portion of each side wall portion that is bent into an "L" shape due to buckling deformation gradually closes. Here, since the length of each reinforcing portion is at least twice the buckling range length, when the buckling deformation progresses and the "L" shape is completely closed, a pair of ridge portions that are connected across the buckling range of this "L" shape can reliably butt against each other. This butting of the ridge portions causes the rise of the secondary peak load. Here, since each side wall portion is pre-reinforced by a reinforcing portion, the buckling range is localized (the area that buckles and displaces into an "L" shape is smaller than when there is no reinforcing portion). Therefore, in the case of small buckling deformation, the pair of ridges begins to collide with each other earlier than in the case of large buckling deformation, and the rise time of the secondary peak load is therefore accelerated. Furthermore, because each side wall portion is reinforced by a reinforcing portion, the pair of ridges continues to collide with each other strongly. As a result, the drop in the secondary peak load can be delayed. Therefore, the rise of the secondary peak load in the FS diagram can be accelerated and its drop can be delayed, making it possible to increase the load integral value. This results in increased energy absorption.

[0032] (4b) In the impact absorbing member described in (1b) or (2b) above, each of the reinforcing portions may be provided only on each of the side wall portions when viewed in a cross section perpendicular to the longitudinal direction. According to the impact absorbing member described in (4b) above, the hollow tube is reinforced except for the inner wall portion and the ridge portion of the bent portion, so that the energy absorption amount can be increased without significantly increasing the maximum load (primary peak load). Therefore, sudden load fluctuations can be most effectively suppressed.

[0033] (5b) The impact absorbing member described in (4b) above may have the following configuration: the hollow tube includes a hat-shaped member having a top wall portion that is the bent inner wall portion and side wall portions that are connected to both sides of the top wall portion via the ridge portions, and a plate-shaped member joined to the hat-shaped member to form a closed cross section; the height dimension H between the top wall portion and the plate-shaped member is 50 mm to 200 mm, the width dimension W of the top wall portion is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-shaped member is 0.8 mm to 3.2 mm; and the length L along the extension direction of each of the reinforcing portions is 70 mm to 500 mm, and the width dimension w in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. The impact absorbing member described in (5b) above can more reliably achieve the effects described in (1b) above.

[0034] (6b) In the impact absorbing member described in (1b) or (2b) above, each of the reinforcing portions may be provided only in an area overlapping from each of the side wall portions to each of the ridge portions when viewed in a cross section perpendicular to the longitudinal direction. According to the impact absorbing member described in (6b) above, since the hollow tube is reinforced except for the inner wall portion of the bent portion, the amount of energy absorption can be increased while suppressing an excessive increase in the maximum load (primary peak load). Therefore, sudden load fluctuations can be reliably suppressed.

[0035] (7b) The impact absorbing member described in (6b) above may have the following configuration: the hollow tube includes a hat-shaped member having a top wall portion that is the bent inner wall portion and side wall portions that are connected to both sides of the top wall portion via the ridge portions, and a plate-shaped member joined to the hat-shaped member to form a closed cross section; the height dimension H between the top wall portion and the plate-shaped member is 50 mm to 200 mm, the width dimension W of the top wall portion is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-shaped member is 0.8 mm to 3.2 mm; the length L along the extension direction of each of the reinforcing portions is 70 mm to 500 mm, and the width dimension w of the portion that overlaps with each of the side wall portions as viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. The impact absorbing member described in (7b) above can more reliably achieve the effects described in (1b) above.

[0036] (8b) The impact absorbing member described in (1b) or (2b) above may employ the following configuration: the reinforcement has a first portion, a second portion, and a third portion aligned in order along the longitudinal direction; and the folding trigger has at least one of a through-hole provided in the second portion or a bead formed long in a direction intersecting the longitudinal direction, and a rigid portion disposed in each of the first portion and the third portion and long in the longitudinal direction. According to the impact absorbing member described in (8b) above, the relative bending strength of the second portion with respect to the first portion and the third portion of the reinforcement can be reduced, so that the impact absorbing member can be reliably folded and deformed at the position of the folding trigger portion.

[0037] (9b) The impact absorbing member described in (1b) or (2b) above may have the following configuration: the reinforce has a first portion, a second portion, and a third portion aligned in order along the longitudinal direction; and the folding trigger is formed in the second portion of the reinforce including a connection position with the hollow tube, and has at least one of a thickness thinner than both the first portion and the third portion and a tensile strength lower than both the first portion and the third portion. According to the impact absorbing member described in (9b) above, the relative bending strength of the second portion with respect to the first portion and the third portion of the reinforce can be reduced, so that the impact absorbing member can be reliably folded and deformed at the folding trigger position.

[0038] (10b) The impact absorbing member described in (1b) or (2b) above may employ the following configuration: the hollow tube has a first portion, a second portion, and a third portion aligned in order along the longitudinal direction; and the folding trigger portion has the reinforcement disposed in at least the second portion, and a filler disposed inside the first portion and inside the third portion. According to the impact absorbing member described in (10b) above, the relative bending strength of the second portion with respect to the first portion and the third portion of the reinforcement can be reduced, so that the impact absorbing member can be reliably folded and deformed at the position of the folding trigger portion.

[0039] According to the impact absorbing member according to each of the above aspects of the present invention, a high amount of collision energy absorption can be obtained with a short deformation stroke while suppressing sudden load fluctuations.

[0040] 4 is a perspective view of a vehicle body in which the impact absorbing member according to the first embodiment of the present invention is applied to a front side member and a rear side member. FIG. 1 is a perspective view of the impact absorbing member, in which a bead is formed on each of a pair of ridge lines as a folding trigger. FIG. 2 is a partially enlarged longitudinal sectional view of a main part of the impact absorbing member, taken along the line A-A in FIG. 2. FIG. 2 is a view showing a modified example of the main part. FIG. 1 is a perspective view of the process in which the impact absorbing member is subjected to an axial compressive bending load and is a perspective view showing the state after the maximum load has occurred. FIG. 2 is a perspective view showing a continuation of the folding deformation process and is a perspective view showing the state at the time when the rise of the secondary peak load occurs. FIG. 1 is a schematic front view of part B in FIG. 4, illustrating the folding deformation process. FIG. 1 is a perspective view of another embodiment of the impact absorbing member, in which a long bead is formed in the top wall portion in a direction perpendicular to the longitudinal direction as a folding trigger. FIG. 2 is a perspective view of yet another embodiment of the impact absorbing member, in which a through-hole is formed in the top wall portion as a folding trigger. 13A , 13B, 13C, 13D, 13E, 13F, 13G, 13H ... 14 is a cross-sectional view of the shock absorbing member taken along the line E-E in FIG. 14, showing yet another embodiment of the shock absorbing member, in which a filler is used as a breakage trigger.1 is a perspective view illustrating an example, where (a) shows the shock absorbing member before an axial compressive bending load is applied, and (b) shows the shock absorbing member after an axial compressive bending load is applied. This is a graph showing the load-deformation stroke curve (hereinafter referred to as FS curve) when the length of the reinforcement portion is changed in the same example. This is a graph showing the FS curve when the width and position of the reinforcement portion are changed in the same example. This is a comparison diagram of the maximum load and energy absorption amount when the length of the reinforcement portion is changed in the same example. (a) is a perspective view of the shock absorbing member when the length of the reinforcement portion arranged adjacent to the ridge line portion is 260 mm, (b) is a perspective view when the length of the reinforcement portion arranged adjacent to the ridge line portion is 180 mm, and (c) is a perspective view of the shock absorbing member when the length of the reinforcement portion arranged adjacent to the ridge line portion is 90 mm. (d) is a bar graph comparing the maximum load, (e) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 50 mm, and (f) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 100 mm. This is a comparison diagram of the maximum load and energy absorption amount when the width and position of the reinforcement part are changed in the same example. (a) is a perspective view of the impact absorbing member when the width of the reinforcement part arranged adjacent to the ridge line part is 20 mm, (b) is a perspective view of the impact absorbing member when the width of the reinforcement part arranged adjacent to the ridge line part is 10 mm, and (c) is a perspective view of the impact absorbing member when the width of the reinforcement part is 10 mm and the reinforcement part is arranged 10 mm below the ridge line part. (d) is a bar graph comparing the maximum load, (e) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 50 mm, and (f) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 100 mm. This is a comparison diagram of the maximum load and energy absorption amount when the width and position of the reinforcement part are changed in the same example. (a) is an oblique view of the impact absorbing member showing a case where a reinforcing portion having a width of 20 mm and a length of 260 mm is arranged on each side wall portion and adjacent to the ridge portion, (b) is a case where two reinforcing portions having a width of 20 mm and a length of 260 mm are arranged near the ridge portion of the top wall portion, and (c) is a case where one reinforcing portion having a width of 40 mm and a length of 260 mm is arranged in the center of the top wall portion.(d) is a bar graph comparing the maximum load, (e) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 50 mm, and (f) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 100 mm. In the same example, a comparison diagram of the maximum load and energy absorption amount when the reinforcement portion is arranged so as to overlap the ridge portion is shown. (a) is a perspective view of the impact absorbing member showing the case where the reinforcement portion is arranged only on the ridge portion, (b) is a case where the reinforcement portion of (a) is further extended by 10 mm toward the top wall portion, (c) is a case where the reinforcement portion of (a) is further extended by 10 mm toward the side wall portion, and (d) is a perspective view of the impact absorbing member showing the case where the reinforcement portion of (a) is further extended by 10 mm toward both the top wall portion and the side wall portion. (e) is a bar graph comparing the maximum load, (f) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 50 mm, and (g) is a bar graph comparing the energy absorption amount when the deformation stroke is between 0 and 100 mm. 25. FIG. 26 is a perspective view of a shock absorbing member according to a second embodiment of the present invention. FIG. 27 is a partially enlarged longitudinal sectional view of a main part of the shock absorbing member taken along the F-F cross section of FIG. 23. FIG. 28 is a view showing a modified example of the main part. FIG. 29 is a perspective view showing the process of the shock absorbing member undergoing bending deformation when subjected to an axial compressive bending load, and is a perspective view showing the state after the maximum load has occurred. FIG. 29 is a perspective view showing a continuation of the bending deformation process, and is a perspective view showing the state at the time when the rise of the secondary peak load occurs. FIG. 29 is a schematic plan view of part G of FIG. 25 explaining the bending deformation process. FIG. 26 is a perspective view showing an example of a bending trigger point of a reinforcement provided in the shock absorbing member. FIG. 27 is a perspective view showing another example of a bending trigger point of a reinforcement provided in the shock absorbing member. FIG. 28 is a perspective view showing yet another example of a bending trigger point of a reinforcement provided in the shock absorbing member. FIG. 29 is a perspective view showing yet another example of a bending trigger point of a reinforcement provided in the shock absorbing member. 10 is a perspective view showing still another example of the breakage trigger of the reinforcement provided in the impact absorbing member, and FIG. 11 is a perspective view showing still another example of the breakage trigger of the reinforcement provided in the impact absorbing member.It is a perspective view showing still another example of the breakage trigger of the reinforcement provided in the same impact absorbing member. It is a perspective view showing still another example of the breakage trigger of the reinforcement provided in the same impact absorbing member. It is a view showing still another example of the breakage trigger of the reinforcement provided in the same impact absorbing member, and is a cross-sectional view seen in a longitudinal section including a center line. It is a view showing the impact absorbing member of FIG. 38, and is a cross-sectional view taken along the line H-H of FIG. 38. It is a view showing the impact absorbing member of FIG. 38, and is a cross-sectional view taken along the line I-I of FIG. 38. It is a view showing still another example of the breakage trigger of the reinforcement provided in the same impact absorbing member, and is a cross-sectional view seen in a longitudinal section including a center line. It is a view showing the impact absorbing member of FIG. 41, and is a cross-sectional view taken along the line J-J of FIG. 41. It is a view showing the impact absorbing member used in the same embodiment, and is a cross-sectional view taken along the line F-F of FIG. 23. Among these, Case000,005 is a comparative example. On the other hand, Case001 to Case004 are inventive examples provided with a reinforcing portion. It is a view for explaining an embodiment, and is a perspective view showing how an axial compressive bending load is applied to an impact absorbing member. (a) shows before applying the axial compressive bending load, and (b) shows after applying the axial compressive bending load and being bent and deformed. It is a bar graph comparing the maximum loads in the same embodiment, where the horizontal axis indicates each case number and the vertical axis indicates the maximum load (kN). It is a bar graph comparing the energy absorption amounts in the same embodiment, where the horizontal axis indicates each case number and the vertical axis indicates the energy absorption amount (kJ).

[0041] [First Embodiment] Hereinafter, an impact absorbing member according to the first embodiment of the present invention and various modified examples thereof will be described with reference to the drawings. As shown in FIG. 1, the impact absorbing member of the present embodiment can be used as a front side member FM or a rear side member RM which are skeletal members of an automobile. When the impact absorbing member is used as the front side member FM, it is arranged on the vehicle front FW side with respect to the passenger compartment Ca. On the other hand, when the impact absorbing member is used as the rear side member RM, it is arranged on the vehicle rear RW side with respect to the passenger compartment Ca. The impact absorbing member is a hollow tube that is long along one direction, and in both the case of being used as the front side member FM and the case of being used as the rear side member RM, one end side in the longitudinal direction faces the vehicle front and the other end side in the longitudinal direction faces the vehicle rear side.

[0042] As will be described in detail later, the impact absorbing member has a rectangular cross section perpendicular to its longitudinal direction and comprises a hat-shaped member and a plate-shaped member. The hat-shaped member has a hat top portion whose cross section perpendicular to the longitudinal direction is a top wall portion, and a pair of side walls continuing on both sides of the hat top portion. The plate-shaped member is joined to the hat-shaped member and faces the hat top portion. The impact absorbing member absorbs impact force by bending deformation rather than bellows deformation. Hereinafter, the bending deformation range shown in Figure 1 is designated by the reference numeral 1, and this will be described as the impact absorbing member 1.

[0043] As shown in Figure 2, the impact absorbing member 1 of this embodiment is a hollow tube 30 that is long in the longitudinal direction along its center line CL. This hollow tube 30 has a rectangular cross section perpendicular to the center line CL and includes a hat-shaped member 10 and a plate-shaped member 20. In Figure 2, the X direction indicates the longitudinal direction of the vehicle, the Y direction indicates the width direction of the vehicle, and the Z direction indicates the height direction of the vehicle. For ease of explanation, the following description may refer to the X direction in Figure 2 as the longitudinal direction of the impact absorbing member 1, the Y direction as the height direction of the impact absorbing member 1, and the Z direction as the width direction of the impact absorbing member 1.

[0044] The hat-shaped component 10 has a top wall 11, a pair of side walls 12, and a pair of flanges 13. The top wall 11 forms the hat top of the hat-shaped component 10, which is hat-shaped when viewed along the center line CL. The top wall 11 is a long plate having a substantially constant width W and a substantially constant thickness T1, and is elongated along the center line CL. The top wall 11 has a flat upper surface and a flat lower surface. The width W can be exemplified as 30 mm to 100 mm. The thickness T1 can be exemplified as 0.8 mm to 3.2 mm. The values ​​for the thickness T1 exemplified here are for a case in which steel is used as the material for the impact absorbing component 1. If the impact absorbing component 1 is manufactured from an aluminum extrusion, the upper limit of the thickness T1 can be exemplified as 4.0 mm. The width W and thickness T1 of the top wall 11 do not necessarily have to be constant at each position on the center line CL, and may be changed at each position along the center line CL as required for the part design. Similarly, the upper and lower surfaces of the top wall 11 do not necessarily have to be flat, and may have some unevenness as required for the part design.

[0045] The pair of side walls 12 includes a left side wall 12a and a right side wall 12b. The left side wall 12a is a vertical wall integrally connected to one of the side edges of the top wall 11. In a cross section perpendicular to the center line CL, the angle formed between the left side wall 12a and the top wall 11 may be 90° or slightly larger than 90°. The left side wall 12a is an elongated plate having a substantially constant width and thickness and extending in the direction along the center line CL. The left side wall 12a has a flat outer surface and a flat inner surface. The right side wall 12b is a vertical wall integrally connected to the other of the side edges of the top wall 11. In a cross section perpendicular to the center line CL, the angle formed between the right side wall 12b and the top wall 11 may be 90° or slightly larger than 90°. The right side wall portion 12b is a long plate having a substantially constant width and a substantially constant thickness, and is elongated in the direction along the center line CL. The right side wall portion 12b has a flat outer surface and a flat inner surface. Note that the width and thickness of the left side wall portion 12a and the right side wall portion 12b do not necessarily have to be constant at each position along the center line CL, and may vary at each position along the center line CL as required for the component design. Similarly, the outer and inner surfaces of the right side wall portion 12b and the left side wall portion 12a do not necessarily have to be flat, and may have some unevenness as required for the component design.

[0046] The pair of flange portions 13 includes a left flange portion 13a and a right flange portion 13b. The left flange portion 13a is integrally connected to the lower edge of the left side wall portion 12a. The left flange portion 13a is a strip-shaped plate having a substantially constant width and thickness and is elongated in the direction along the center line CL. The left flange portion 13a has a flat upper surface and a flat lower surface. The right flange portion 13b is integrally connected to the lower edge of the right side wall portion 12b. The right flange portion 13b is a strip-shaped plate having a substantially constant width and thickness and is elongated in the direction along the center line CL. The right flange portion 13b has a flat upper surface and a flat lower surface. Note that the width and thickness of the left flange portion 13a and the right flange portion 13b do not necessarily have to be constant at each position along the center line CL and may vary at each position along the center line CL as required for part design. Similarly, the upper and lower surfaces of the left flange portion 13 a and the right flange portion 13 b do not necessarily have to be flat, and may have some irregularities depending on the shape of the plate-like member 20 .

[0047] A ridgeline EL parallel to the center line CL is formed between the top wall 11 and the left side wall 12a. This ridgeline EL is a curved portion formed between the side edge of the flat outer surface of the top wall 11 and the side edge of the flat outer surface of the left side wall 12a, and has an arc-shaped outer surface with a predetermined width when viewed along the center line CL. A ridgeline EL parallel to the center line CL is also formed between the top wall 11 and the right side wall 12b. This ridgeline EL is also a curved portion formed between the side edge of the flat outer surface of the top wall 11 and the side edge of the flat outer surface of the right side wall 12b, and has an arc-shaped outer surface with a predetermined width when viewed along the center line CL.

[0048] As shown in Figure 2, each ridge line EL has a substantially constant width, and its cross section perpendicular to the longitudinal direction has an arc-shaped cross section across its entire width. Each ridge line EL has one side edge ELa that connects to the top wall 11 and the other side edge ELb that connects to the left side wall 12a or the right side wall 12b. While each ridge line EL has an arc-shaped cross section, the top wall 11, the left side wall 12a, and the right side wall 12b each have a flat cross section. Therefore, when viewed from each ridge line EL, the one side edge ELa and the other side edge ELb are boundaries (radii) where the cross section changes from an arc cross section to a flat cross section.

[0049] The combination of the top wall 11, left side wall 12a, and right side wall 12b forms a generally trapezoidal shape in a cross section perpendicular to the centerline CL. Furthermore, by combining this combination with the left flange 13a and right flange 13b, the hat-shaped member 10 is formed, which has a hat-shaped cross section perpendicular to the longitudinal direction. The hat-shaped member 10 is obtained by press-forming a stamped plate material. The material of the hat-shaped member 10 is metal, and a high-strength steel plate with a tensile strength of 590 MPa or more can be preferably used.

[0050] The plate-shaped member 20 is a long metal plate extending along the center line CL, and a high-strength steel plate having a tensile strength of 590 MPa or more can be suitably used. The plate-shaped member 20 has a flat upper surface and a flat lower surface. The plate-shaped member 20 is welded to the left flange portion 13a and the right flange portion 13b at both side edges thereof. This forms a closed cross section between the hat-shaped member 10 and the plate-shaped member 20. Note that the width and thickness of the plate-shaped member 20 do not necessarily have to be constant at each position along the center line CL, and may vary at each position along the center line CL as required for the part design. Similarly, the upper and lower surfaces of the plate-shaped member 20 do not necessarily have to be flat, and may have some irregularities as required for the part design.

[0051] In addition to the above configuration, the impact absorbing member 1 of this embodiment further includes a reinforcing element 40 and a folding trigger. The reinforcing element 40 includes a left reinforcing element 40a and a right reinforcing element 40b. As shown in FIGS. 2 and 3A, the left reinforcing element 40a is a long, strip-shaped metal plate extending along the center line CL. A high-strength steel plate having a tensile strength of 590 MPa or greater can be suitably used as its material. The left reinforcing element 40a is fixed by welding to the longitudinal center of the left side wall portion 12a and adjacent to the ridge line EL. As shown in FIG. 3A, the left reinforcing element 40a is positioned so as not to overlap the ridge line EL. The left reinforcing element 40a has a length L along the center line CL of 70 mm to 500 mm, a width w in a cross section perpendicular to the center line CL of 10 mm to 60 mm, and a thickness of 0.8 mm to 3.2 mm. The thickness values ​​exemplified here are for a case in which the impact absorbing member 1 is made of steel. When the impact absorbing member 1 including the left reinforcing portion 40a is manufactured from an extruded aluminum material, the upper limit of the plate thickness of the left reinforcing portion 40a can be set to 4.0 mm, for example.

[0052] Similarly, the right reinforcing portion 40b is a long, strip-shaped metal plate extending along the center line CL. Its material is preferably a high-strength steel plate with a tensile strength of 590 MPa or greater. The right reinforcing portion 40b is fixed by welding to the longitudinal center of the right side wall portion 12b, adjacent to the ridge line EL. The right reinforcing portion 40b is also positioned so as not to overlap the ridge line EL. The right reinforcing portion 40b has the same shape as the left reinforcing portion 40a. That is, the right reinforcing portion 40b has a length L along the center line CL of 70 mm to 500 mm, a width w in a cross section perpendicular to the center line CL of 10 mm to 60 mm, and a thickness of 0.8 mm to 3.2 mm. The thickness values ​​exemplified here are for the case where steel is used as the material for the impact absorbing member 1. If the impact absorbing member 1, including the right reinforcing portion 40b, is manufactured from an aluminum extrusion, the upper limit of the thickness of the right reinforcing portion 40b can be, for example, 4.0 mm.

[0053] Although high-strength steel plate has been exemplified above as the material for the reinforcing portion 40 (left reinforcing portion 40a and right reinforcing portion 40b), other materials such as SUS430, SUS304, SUS316, SUS304N1, SUS316N, or an Fe-Mn-Si shape memory alloy (such as an Fe-28Mn-6Si-5Cr alloy or an Fe-15Mn-4Si-10Cr-8Ni alloy) may also be used.

[0054] The left reinforcing portion 40a reinforces only the portion of the left side wall 12a adjacent to the ridge line EL. Similarly, the right reinforcing portion 40b reinforces only the portion of the right side wall 12b adjacent to the ridge line EL. Therefore, the upper surfaces of the ridge lines EL and the upper surface of the ceiling wall 11 are not reinforced. In other words, the left reinforcing portion 40a and the right reinforcing portion 40b reinforce only the portions of the left side wall 12a and the right side wall 12b adjacent to the ridge line EL, respectively, while avoiding the upper surface of the ceiling wall 11 and the upper surfaces of the pair of ridge lines EL.

[0055] As shown in FIG. 3B , the left reinforcing portion 40a and the right reinforcing portion 40b may reinforce the hat-shaped member 10, including the ridgeline EL, while avoiding the upper surface of the top wall portion 11. That is, the left reinforcing portion 40a may be joined by welding or the like to both the left sidewall portion 12a near the ridgeline EL and a position overlapping the ridgeline EL. Similarly, the right reinforcing portion 40b may be joined by welding or the like to both the right sidewall portion 12b near the ridgeline EL and a position overlapping the ridgeline EL. In this modification, as shown in FIG. 3B , the shape of the left reinforcing portion 40a in a cross section perpendicular to the center line CL is bent so that its upper end is in close contact with the upper surface of the ridgeline EL. In the modification shown in FIG. 3B , as in the configuration shown in FIG. 3A , the length L of both the left reinforcing portion 40a and the right reinforcing portion 40b can be 70 mm to 500 mm. On the other hand, the width dimensions (total width dimensions) of the left reinforcing portion 40a and the right reinforcing portion 40b need only be such that the width dimension w (partial width dimension) of the flat portions overlapping the left sidewall portion 12a and the right sidewall portion 12b is 10 mm to 60 mm, and the width dimension (partial width dimension) of the overlapping portions with the ridge line portion EL is arbitrary. However, it is necessary to set these left reinforcing portion 40a and right reinforcing portion 40b so that they do not overlap the top wall portion 11.

[0056] One of the pair of ridge lines EL is a corner connecting the top wall 11 and the left sidewall 12 a, and has a predetermined radius of curvature in the cross section shown in Figures 3A and 3B . The other of the pair of ridge lines EL is a corner connecting the top wall 11 and the right sidewall 12 b, and also has a predetermined radius of curvature.

[0057] The bending trigger is a bending point BP set midway along the longitudinal direction of the outer surface of the top wall 11, which is the inner wall of the hollow tube 30. In other words, the bending trigger is a configuration for bending the hollow tube 30 at the bending point BP of the top wall 11 so that the outer surface of the top wall 11 forms a concave surface, and various configurations are possible.

[0058] For example, in the embodiment shown in FIG. 2 , a pair of left and right beads Ba and Bb (first beads) are provided as bending triggers on each ridgeline EL of the hollow tube 30 at positions corresponding to the bending starting points BP in the longitudinal direction. That is, as shown in FIG. 2 , the right bead Bb is formed at a single location on the ridgeline EL connecting the top wall 11 and the right sidewall 12b. The right bead Bb crosses the boundary between the top wall 11 and the ridgeline EL (where the radius ends). That is, the right bead Bb is formed by extending from the ridgeline EL toward the top wall 11. Furthermore, the right bead Bb is formed by extending from the ridgeline EL toward the right sidewall 12b. Therefore, the right bead Bb is formed to extend from the top wall 11 to the right sidewall 12b via the ridgeline EL.

[0059] Similarly, one left bead Ba is formed on the ridge line EL connecting the top wall 11 and the left side wall 12a. The left bead Ba crosses the boundary (where the radius ends) between the top wall 11 and the ridge line EL. That is, the left bead Ba is formed to protrude from the ridge line EL toward the top wall 11. Furthermore, the left bead Ba is formed to protrude from the ridge line EL toward the left side wall 12a. Therefore, the left bead Ba is formed to extend from the top wall 11 to the left side wall 12a via the ridge line EL.

[0060] The left bead Ba and the right bead Bb are each diamond-shaped when viewed from the front, and the diagonal length can be, for example, 11 mm to 23 mm. The depth of the outer surface of the left bead Ba and the right bead Bb can be, for example, 7 mm to 15 mm. The left bead Ba and the right bead Bb may be formed simultaneously with the press working to form the hat-shaped member 10 from a metal plate, or they may be formed by post-processing on the hat-shaped member 10 after press forming. When the left bead Ba and the right bead Bb are formed by press working, their plate thickness is slightly thinner than the surrounding plate thickness and is work-hardened. Just as the outer surfaces of the left bead Ba and the right bead Bb are concave, the inner surfaces are also concave toward the inside of the hollow tube 30.

[0061] The shape of the left bead Ba and the right bead Bb in a front view is not limited to a diamond shape, but may also be a circle, an ellipse, a rectangle, or a polygon. It is preferable that the shape and dimensions of the left bead Ba and the right bead Bb are the same, but they may differ slightly as long as their function is not impaired. The left bead Ba and the right bead Bb are formed at approximately the same position in the longitudinal direction of the hat-shaped member 10. The presence of this pair of left beads Ba and right beads Bb forms a folding start point BP on the outer surface of the top wall portion 11. The left reinforcing portion 40a is not joined to the left bead Ba, and there is a gap between it and the left bead Ba. Similarly, the right reinforcing portion 40b is not joined to the right bead Bb, and there is a gap between it and the right bead Bb.

[0062] As shown in FIG. 2 , the fold origin BP is a localized portion set within the outer surface of the top wall portion 11, where buckling deformation occurs and the impact absorbing member 1 breaks when subjected to impact energy in the −X direction. This fold origin BP is a portion that is set in advance during the design stage and actively induces bending deformation. In the impact absorbing member 1 of this embodiment, the fold origin BP is located midway along the length of the reinforcement portion 40. Specifically, the left reinforcement portion 40a is located on the left sidewall portion 12a so that the fold origin BP is located midway along the length. Similarly, the right reinforcement portion 40b is located on the right sidewall portion 12b so that the fold origin BP is located midway along the length. It is preferable that the fold origin BP be located at a central position along the length of the left reinforcement portion 40a and the right reinforcement portion 40b. 2, the length L of each of the left and right reinforcing portions 40a, 40b along their extension direction is at least twice the buckling range length LB at the position of the folding start point BP of the left and right sidewall portions 12a, 12b. This allows for a high degree of collision energy absorption with a short deformation stroke while suppressing sudden load fluctuations. The mechanism behind this is explained below with reference to FIGS. 4 to 6.

[0063] FIG. 4 is a diagram showing the process of bending deformation of the impact absorbing member 1 under an axial compressive bending load, and is a perspective view showing the state after the maximum load occurs. FIG. 5 is a diagram continuing the bending deformation process of FIG. 4 , showing the state at the time when the rise of the secondary peak load occurs. As shown in FIG. 4 , when the impact absorbing member 1 receives collision energy along its longitudinal direction, it bends at the bending point BP, with the outer surface (top surface) of the top wall portion 11 facing inward. The absorption of the collision energy during this bending deformation occurs at the bending point BP through the following three deformations: a depression of the top surface of the top wall portion 11; an L-shaped bending of the left side wall portion 12a and the right side wall portion 12b toward the direction of separation; and an L-shaped bending of the left reinforcing portion 40a and the right reinforcing portion 40b toward the direction of separation. At this time, compressive deformation occurs primarily at the bending point BP at the top wall portion 11, the left side wall portion 12a, and the right side wall portion 12b. On the other hand, tensile deformation occurs in the left reinforcing portion 40a and the right reinforcing portion 40b. Collision energy is absorbed by these compressive and tensile deformations.

[0064] The higher the structural strength of the top wall portion 11, the higher the maximum load of the impact absorbing member 1 when collision energy is applied. If the maximum load is too high, the load that drops due to bending deformation after the maximum load occurs will also drop rapidly. In a vehicle equipped with the impact absorbing member 1, it is preferable to avoid such large load fluctuations being applied to occupants during a collision. In the impact absorbing member 1 of this embodiment, the left reinforcing portion 40a and the right reinforcing portion 40b are arranged adjacent to each ridge line portion EL and extend along the extension direction of each ridge line portion EL. In other words, these left reinforcing portion 40a and right reinforcing portion 40b do not reinforce the top wall portion 11, so the maximum load of the impact absorbing member 1 does not need to be excessively increased.

[0065] On the other hand, as described above, collision energy is absorbed by the folding deformation of the top wall portion 11 as well as the buckling deformation of the left and right side walls 12a and 12b into an "L" shape at the folding start point BP. At this time, the left and right side walls 12a and 12b are reinforced by the left and right reinforcing portions 40a and 40b, making them less likely to bend into an "L" shape. This allows for a gentler drop in load after the occurrence of maximum load in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram). As a result, the maximum load value in the FS diagram can be suppressed while the load integral value after the occurrence of maximum load can be increased. This allows for a greater amount of energy absorption.

[0066] Furthermore, the rise time of the secondary peak load in the FS diagram can also be accelerated. To explain this, first, the "L"-shaped portions of the left reinforcing portion 40a and the right reinforcing portion 40b that are bent due to buckling deformation gradually close. Then, as a result of the "L" being completely closed, the two straight portions of the ridgeline portion EL on either side of the "L" portion butt against each other, resulting in the state shown in FIG. 5. This butting of the two straight portions of the ridgeline portion EL causes the rise of the secondary peak load.

[0067] The deformation of the ridgeline portion EL during the above-described bending deformation process is shown in Figure 6. This Figure 6 is a diagram for explaining the bending deformation process, and is a schematic diagram showing the bending starting point BP and its surrounding area of ​​the ridgeline portion EL of the impact absorbing member 1 in Figure 4, viewed from the front. In Figure 6, the solid line indicates the ridgeline portion EL in the impact absorbing member 1 of this embodiment, and the imaginary line indicates the ridgeline portion EL' in a conventional structure that does not have the reinforcing portion 40.

[0068] At the ridgeline portion EL' shown by the imaginary line, the sidewall portion 12 (left sidewall portion 12a and right sidewall portion 12b) is not reinforced by the reinforcing portion 40 (left reinforcing portion 40a and right reinforcing portion 40b), so the "L" shape that occurs in the buckling range is larger. On the other hand, in the impact-absorbing member 1 of this embodiment, the upper edge of the left sidewall portion 12a is reinforced by the left reinforcing portion 40a, and the upper edge of the right sidewall portion 12b is reinforced by the right reinforcing portion 40b. Therefore, in the hat-shaped member 10, each corner corresponding to each of the pair of ridgeline portions EL is substantially reinforced. Therefore, as shown in FIG. 6 , the deformation area of ​​the ridgeline portion EL is localized compared to the ridgeline portion EL', resulting in a smaller "L" shape. As a result, interference between the pair of straight portions of the ridgeline portion EL begins earlier. Therefore, the rise of the secondary peak load is earlier.

[0069] Furthermore, in the impact absorbing member 1 of this embodiment, the side wall portions 12 (left side wall portion 12a and right side wall portion 12b) are reinforced with the reinforcing portions 40 (left reinforcing portion 40a and right reinforcing portion 40b), so the two straight portions of the ridge line EL can continue to strongly butt against each other while suppressing bending. As a result, the period during which the secondary peak load is applied can be extended. Therefore, the load integral value after the rise of the secondary peak load in the FS diagram can also be increased, thereby increasing the amount of energy absorption.

[0070] As described above, in the impact absorbing member 1 of this embodiment, the length of each of the left reinforcing portion 40a and the right reinforcing portion 40b is set to be at least twice the buckling range length LB shown in Fig. 2. The buckling range length LB here refers to the maximum length dimension along the center line CL of the range that buckles during bending deformation. This maximum value can be determined by performing numerical calculations at the design stage, or by manufacturing a sample material and performing a load test, for example.

[0071] Alternatively, the buckling range length LB can be predicted based on the shape and dimensions of the impact absorbing member 1. For example, if the height dimension from the outer surface of the plate-like member 20 illustrated in Fig. 2 to the outer surface of the top wall portion 11 is H (mm), the maximum value, i.e., the buckling range length LB, can be predicted to be the same H (mm). Therefore, it is preferable to set the length of each of the left reinforcing portion 40a and the right reinforcing portion 40b to 2 x H (mm) or more (twice the buckling range length LB).

[0072] 2 illustrates an example in which the height dimension H at the left side wall 12a and the height dimension H at the right side wall 12b are equal. However, if they are not equal, i.e., if the height dimension at the left side wall 12a is H1 and the height dimension at the right side wall 12b is H2 (H1≠H2), the buckling range length LB can be predicted using their average. That is, in this case, the buckling range length LB can be predicted to be (H1+H2) / 2. It is preferable to set the lengths of the left reinforcing portion 40a and the right reinforcing portion 40b so that they are equal to or greater than (H1+H2), which is twice (H1+H2) / 2. In this way, the buckling range length LB can be determined even when the height dimension H (H1) at the left side wall 12a and the height dimension H (H2) at the right side wall 12b are not equal to each other, and therefore, it can be said that the buckling range length LB is essentially the average value of the buckling range length LB based on the height dimension H1 and the buckling range length LB based on the height dimension H2. Therefore, it can be said that the buckling range length LB is a value based on the average value of the height dimension H.

[0073] By making the length L of the left reinforcing portion 40a and the right reinforcing portion 40b at least twice the buckling range length LB, when the buckling range is completely buckled as shown in Figure 5, a pair of straight line portions of each ridge line EL that are connected across the buckling range can be more reliably abutted against each other. Therefore, it is preferable to make the length L at least twice the length LB.

[0074] 2, a configuration including a left bead Ba and a right bead Bb is used as the breaking trigger. However, the breaking trigger is not limited to this configuration, and other configurations such as those described below can also be used. Furthermore, each of the breaking trigger configurations exemplified here can be used alone, or multiple configurations can be selected and combined as needed.

[0075] In the embodiment shown in Figure 7, a horizontally elongated bead (second bead) Bc is formed at the position of the folding starting point BP of the top wall portion 11 as a folding trigger. This horizontally elongated bead Bc is a single recess formed in the top wall portion 11, and is elongated in a direction perpendicular to (intersecting) the longitudinal direction of the impact absorbing member 1. The horizontally elongated bead Bc is formed along the width direction of the top wall portion 11, between a pair of ridge portions EL that form both side edges of the top wall portion 11. Therefore, the horizontally elongated bead Bc is formed only on the top wall portion 11, which is a flat portion, and does not overlap each of the ridge portions EL.

[0076] The oblong bead Bc has a rectangular central portion in the longitudinal direction and semicircular ends. The width of the oblong bead Bc can be 20 mm to 40 mm. The length of the oblong bead Bc can be 50 mm to 80 mm. The depth of the oblong bead Bc can be 4 mm to 15 mm. The oblong bead Bc may be formed simultaneously with the press working used to form the hat-shaped member 10 from a metal plate, or may be formed by post-pressing the hat-shaped member 10. When the oblong bead Bc is formed by press working, its thickness is slightly thinner than the surrounding plate thickness and is work-hardened. The oblong bead Bc has a concave outer surface and an inner surface that is concave toward the interior of the hollow tube 30. The number of oblong beads Bc is not limited to one, but may be two or more. Also, in FIG. 7, the longitudinal direction of the horizontally elongated bead Bc is shown as being perpendicular to the longitudinal direction of the impact absorbing member 1, but it may be at a slight angle to the perpendicular direction.

[0077] In this embodiment, the portion of the breaking point that includes the oblong bead Bc forms the second portion R2 that undergoes buckling deformation. The first portion R1 is located on one longitudinal side of the second portion R2, and the third portion R3 is located on the other longitudinal side. Therefore, when a load is applied to the impact absorbing member 1 along the center line CL, the impact absorbing member 1 bends with the oblong bead Bc of the second portion R2 as the bending point BP. This bending absorbs the impact energy.

[0078] Furthermore, in the embodiment shown in FIG. 8 , a through hole Ta is formed at the folding point BP of the top wall portion 11 as a folding trigger. The through hole Ta is circular, and its inner diameter can be exemplified as 20 mm to 40 mm. The through hole Ta is formed only in the top wall portion 11 of the hat-shaped member 10 and does not overlap with the pair of ridges EL. In this folding trigger, the portion including the through hole Ta forms the second region R2 that undergoes buckling deformation. The first region R1 is disposed on one longitudinal side of the second region R2, and the third region R3 is disposed on the other longitudinal side. Therefore, when a load is applied to the impact absorbing member 1 along the center line CL, the through hole Ta in the second region R2 bends at the folding point BP. This bending absorbs the impact energy. Note that the shape of the through hole Ta is not limited to a circle, and other shapes, such as an ellipse, may also be used. Furthermore, the number of through holes Ta in the ceiling wall portion 11 may be plural.

[0079] 9, vertically elongated beads (third beads) Bd, Be are provided in the first region R1 and the third region R3, respectively, as bending triggers, and are formed on the top wall 11 along the longitudinal direction of the hollow tube 30. Except for the portions of the vertically elongated beads Bd and Be, the top wall 11 has a flat upper surface and a flat lower surface.

[0080] The vertically elongated bead Bd is formed to pass through the widthwise center of the top wall portion 11 when viewed from the front and to one side of the longitudinal center of the top wall portion 11. In other words, the vertically elongated bead Bd is positioned on the one side of the longitudinal center of the top wall portion 11, avoiding the longitudinal center of the top wall portion 11. The vertically elongated bead Bd is linearly elongated along the longitudinal direction of the top wall portion 11 and parallel to the center line CL. The vertically elongated bead Bd has a constant width at each position in the longitudinal direction, except for both ends. An example of this width is 20 mm to 40 mm. The vertically elongated bead Bd also has a constant depth at each position in the longitudinal direction. An example of this depth is 4 mm to 15 mm, based on the circumference of the vertically elongated bead Bd. Both longitudinal ends of the vertically elongated bead Bd have a semicircular shape when viewed from the front.

[0081] The vertically elongated bead Be is formed on the other side of the longitudinal center of the top wall portion 11, passing through the widthwise center of the top wall portion 11 when viewed from the front. In other words, the vertically elongated bead Be is positioned on the other side of the longitudinal center of the top wall portion 11, avoiding the longitudinal center of the top wall portion 11. The vertically elongated bead Be has the same shape and dimensions as the vertically elongated bead Bd. That is, the vertically elongated bead Be is linearly elongated along the longitudinal direction of the top wall portion 11 and parallel to the center line CL. The vertically elongated bead Be has a constant width at all positions along its longitudinal direction, except for both ends. Furthermore, the vertically elongated bead Be has a constant depth at all positions along its longitudinal direction. Both longitudinal ends of the vertically elongated bead Be have a semicircular shape when viewed from the front.

[0082] The vertically elongated beads Bd and Be are arranged side by side on the same straight line when the top wall portion 11 is viewed from the front. A gap is provided between the vertically elongated beads Bd and Be. That is, no recess is formed between the end of the vertically elongated bead Bd and the end of the vertically elongated bead Be, and the area is flat and flush with the periphery of the vertically elongated beads Bd and Be. The minimum dimension of the gap can be 15 mm to 30 mm. The gap is the folding start point BP and is located at the center of the width of the top wall portion 11. The vertically elongated beads Bd and Be may be formed simultaneously during press working to form the hat-shaped member 10 from a metal plate, or may be formed by post-processing of the hat-shaped member 10 after press working. When the vertically elongated beads Bd and Be are formed by press working, their plate thickness is slightly thinner than the surrounding plate thickness and is work-hardened. The vertically elongated beads Bd and Be have concave outer surfaces, and the inner surfaces are also concave toward the inside of the hat-shaped member 10. When a load is applied to the impact absorbing member 1 along the center line CL, the top wall portion 11 in the second region R2 bends at a bending point BP. This bending absorbs the impact energy.

[0083] 10, elongated beads (third beads) Bf, Bg are provided in the first region R1 and the third region R3 as bending triggers and are formed on each side wall portion 12 along the longitudinal direction of the hollow tube 30. Except for the portions of the elongated beads Bf and Bg, each side wall portion 12 has a flat outer surface and a flat inner surface.

[0084] The vertically elongated bead Bf is formed to pass through the widthwise center of the right side wall portion 12b when viewed from the front, and to one side of the longitudinal center of the right side wall portion 12b. In other words, the vertically elongated bead Bf is disposed on the one side, avoiding the longitudinal center of the right side wall portion 12b. The vertically elongated bead Bf is linearly elongated along the longitudinal direction of the right side wall portion 12b and parallel to the center line CL. The vertically elongated bead Bf has a constant width at all positions in its longitudinal direction, except for both ends. An example of this width is the same as the width of the vertically elongated bead Bd described above. Furthermore, the vertically elongated bead Bf has a constant depth at all positions in its longitudinal direction. An example of this depth is the same as the depth of the vertically elongated bead Bd described above. Both longitudinal ends of the vertically elongated bead Bf have a semicircular shape when viewed from the front.

[0085] The vertical bead Bg is formed on the other side of the longitudinal center of the right side wall portion 12b, passing through the widthwise center of the right side wall portion 12b when viewed from the front. In other words, the vertical bead Bg is positioned on the other side of the longitudinal center of the right side wall portion 12b, avoiding the longitudinal center of the right side wall portion 12b. The vertical bead Bg has the same shape and dimensions as the vertical bead Bf. That is, the vertical bead Bg is linearly elongated along the longitudinal direction of the right side wall portion 12b and parallel to the center line CL. The width of the vertical bead Bg is constant at all positions along its length, except for both ends. The depth of the vertical bead Bg is also constant at all positions along its length. Both longitudinal ends of the vertical bead Bg have a semicircular shape when viewed from the front.

[0086] The vertically elongated beads Bf and Bg are aligned on the same straight line when the right side wall portion 12b is viewed from the front. A gap is provided between the vertically elongated beads Bf and Bg. That is, no recess is formed between the end of the vertically elongated bead Bf and the end of the vertically elongated bead Bg, forming a flat surface flush with the peripheries of the vertically elongated beads Bf and Bg. The minimum dimension of the gap can be the same as the gap between the vertically elongated beads Bd and Be described above. This gap is the folding start point BP and is located at the center of the right side wall portion 12b in the width direction. The vertically elongated beads Bf and Bg may be formed simultaneously during press working to form the hat-shaped member 10 from a metal plate, or they may be formed by post-processing the hat-shaped member 10 after press working. When the longitudinal beads Bf and Bg are formed by press working, their thickness is slightly thinner than the surrounding plate thickness and is work-hardened. The longitudinal beads Bf and Bg have concave outer surfaces and also concave inner surfaces toward the inside of the hat-shaped member 10. The right side wall portion 12b has a flat outer surface and a flat inner surface except for the portions of the longitudinal beads Bf and Bg.

[0087] The left side wall 12a also has vertically elongated beads Bf and Bg formed thereon, but their arrangement and dimensions are similar, so a repeated description will be omitted. When viewed along the longitudinal direction of the impact absorbing member 1, the vertically elongated beads Bf formed on the left side wall 12a and the vertically elongated beads Bf formed on the right side wall 12b are formed in the same positions. When viewed along the longitudinal direction of the impact absorbing member 1, the vertically elongated beads Bg formed on the right side wall 12b and the vertically elongated beads Bg formed on the left side wall 12a are also formed in the same positions. The gaps formed in the left side wall 12a and the right side wall 12b are also formed in the same positions in the longitudinal direction of the impact absorbing member 1.

[0088] In the impact absorbing member 1 of this embodiment, the portion where the vertically elongated bead Bf is formed is the first portion R1, the portion where the vertically elongated bead Bg is formed is the third portion R3, and the gap between them is the second portion R2. Therefore, when a load is applied to this impact absorbing member 1 along the center line CL, the top wall portion 11 in the second portion R2, which is not reinforced by a bead, bends from the bending point BP. This bending then absorbs the impact energy.

[0089] Furthermore, in the embodiment shown in FIG. 11 , a break trigger point is formed due to the difference in material strength between the second region R2 and the first and third regions R1 and R3. Specifically, the material tensile strength ratio, calculated by dividing the material tensile strength of the second region R2 by the average material tensile strength of the first and third regions R1 and R3, is 0.5 to 0.9. By setting the material tensile strength ratio within this range, the bending strength of the second region R2 can be made lower than the bending strengths of the first and third regions R1 and R3. Therefore, the impact absorbing member 1 can be reliably bent and deformed smoothly with the second region R2 of the hollow tube 30 as the break trigger point. The above-mentioned material tensile strength ratio can be obtained by using a tailored blank, which involves preparing a pair of flat plate materials, one with a relatively low tensile strength and the other with a relatively high tensile strength, and then welding the flat plate material with the relatively low tensile strength between the flat plate materials with the relatively high tensile strength.

[0090] In the embodiment shown in FIG. 11 , the break trigger is formed by a difference in material strength. However, instead, the break trigger may be formed by a difference in plate thickness (plate thickness ratio). Specifically, the plate thickness ratio obtained by dividing the plate thickness of the second region R2 by the average plate thickness of the first region R1 and the third region R3 is set to 0.5 to 0.9. By setting the plate thickness ratio within this range, the plate thickness of the second region R2 is made thinner than the average plate thickness of the first region R1 and the third region R3. As a result, the bending strength of the second region R2 can be made lower than the bending strength of the first region R1 and the third region R3. Therefore, the impact absorbing member 1 can be reliably bent and deformed smoothly with the second region R2 of the hollow tube 30 as the break trigger. The above-mentioned plate thickness ratio can be obtained by preparing a relatively thin plate material and a pair of relatively thick plate materials, and then welding the relatively thin plate material between the relatively thick plate materials.

[0091] 12 to 13C, two bends in opposite directions are pre-formed in the hollow tube 30 along its length to act as folding triggers. As a result, the hollow tube 30 is generally linear in side view but S-shaped in plan view. At one of the two bends, the outer surface of the top wall 11 is concave, forming the first folding point BP. At the other of the two bends, the outer surface of the plate-like member (opposing wall) 20 is concave, forming the second folding point BP. The two folding points BP are spaced apart from each other along the length of the hollow tube 30 and are oriented in opposite directions. At the first folding point BP, reinforcing portions 40 (left reinforcing portion 40a, right reinforcing portion 40b) are disposed adjacent to and along a pair of ridge lines EL that connect the top wall portion 11 and each side wall portion 12. Thus, both the left reinforcing portion 40a and the right reinforcing portion 40b have pre-curved shapes that match the curved shape of the ridge lines EL.

[0092] Meanwhile, at the second folding point BP, other reinforcing portions 40 (left reinforcing portion 40a, right reinforcing portion 40b) are formed adjacent to and along a pair of ridge lines ELx connecting the plate-like member (opposing wall portion) 20 and each side wall portion 12. Therefore, these left reinforcing portion 40a and right reinforcing portion 40b also have pre-defined curved shapes that match the curved shape of the ridge line ELx. The bending direction of the reinforcing portion 40 (left reinforcing portion 40a, right reinforcing portion 40b) at the first folding point BP is opposite to the bending direction of the reinforcing portion 40 (left reinforcing portion 40a, right reinforcing portion 40b) at the second folding point BP. In this embodiment, when a load is applied to the impact absorbing member 1 along the center line CL, the impact absorbing member 1 bends in opposite directions at the two bending origins BP, and absorbs the collision energy by bending and deforming from an S-shape to a Z-shape.

[0093] 14 and 15 , when viewed along the longitudinal direction of the hollow tube 30, the region including the break point BP is designated as the second region R2, one side of the second region R2 as the first region R1, and the other side of the second region R2 as the third region R3. Furthermore, the first region R1 and the third region R3, excluding the second region R2, are filled with filler 50 to act as break triggers. Meanwhile, the second region R2 remains hollow. Therefore, when viewed along the longitudinal direction of the hollow tube 30, the bending strength of the second region R2 is relatively lower than that of the first region R1 and the third region R3, which are reinforced with filler 50. Meanwhile, the shape and arrangement of the reinforcing portions 40 (left reinforcing portion 40a and right reinforcing portion 40b) are the same as those described in FIG. 2 . In this embodiment, when a load is applied to the impact absorbing member 1 along the center line CL, the impact absorbing member 1 absorbs the collision energy by bending from the top wall portion 11 at the second portion R2, which has relatively weak bending strength, as the bending starting point BP.

[0094] Another possible mode for determining the breakage trigger is to position the impact absorbing member 1 so that the impact energy is input from a height position offset from the center line CL. That is, for example, as shown in Figure 16 (described later), the center line CL of the impact absorbing member 1 and the position where the impact energy is input may be offset by a predetermined height. In the example shown in Figure 16, the center line CL of the impact absorbing member 1 is lower than the center of the retaining member that applies the impact energy to the impact absorbing member 1. Therefore, the impact energy can be absorbed by bending and deforming at the longitudinal center of the top wall portion 11, with the breakage trigger point BP being the breakage trigger point.

[0095] The essential features of the impact absorbing member 1 of the first embodiment described above are summarized below. (1) As shown in Figure 2 and other figures, the impact absorbing member 1 of this embodiment has a long hollow tube 30 extending in one direction. When viewed in a cross section perpendicular to the longitudinal direction, the hollow tube 30 has a top wall portion (bending inner wall portion) 11 and a pair of side wall portions 12 connected to the top wall portion 11 via a pair of ridge lines EL. The impact absorbing member 1 also includes a folding trigger provided on the hollow tube 30 and configured to set a folding start point BP in the top wall portion 11 midway along the length of the hollow tube 30; and a pair of reinforcing portions 40 extending along the extension direction of each ridge line EL and provided adjacent to each ridge line EL on the outer surface of each side wall portion 12 when viewed in a cross section perpendicular to the longitudinal direction of the hollow tube 30 at the folding start point BP. 3A and 3B, the pair of reinforcing portions 40 are disposed on the outer surface of the left reinforcing portion 40a or the right reinforcing portion 40b, and are in contact with or overlap with the respective ridge line portions EL, but are not overlapped with the upper surface of the top wall portion 11. When comparing Figures 3A and 3B, Figure 3A is more preferable because it can more reliably suppress the increase in maximum load of the impact absorbing member 1.

[0096] (2) As shown in Figure 2 etc., in the impact absorbing member 1 described in (1) above, each reinforcing portion 40 may be a strip-shaped plate material that is joined to at least the outer surface of each side wall portion 12 and is long along the extension direction. (3) As shown in Figure 2 etc., in the impact absorbing member 1 described in (1) or (2) above, the average length L along the extension direction of each reinforcing portion 40 may be two or more times the buckling range length LB of each side wall portion 12 at the position of the folding start point BP.

[0097] (4) As shown in Figure 3A, etc., in the impact absorbing member 1 described in any one of (1) to (3) above, each reinforcing portion 40 may be provided only on each side wall portion 12 when viewed in a cross section perpendicular to the longitudinal direction. (5) As shown in Figure 2 etc., the impact absorbing member described in (4) above may have the following configuration: a hollow tube 30 includes a hat-shaped member 10 having a top wall portion 11 that is a bending inner wall portion and side wall portions 12 that are connected to both sides of the top wall portion 11 via each ridge portion EL, and a plate-like member 20 that is joined to the hat-shaped member 10 to form a closed cross section; the height dimension H between the top wall portion 11 and the plate-like member 20 is 50 mm to 200 mm, the width dimension W of the top wall portion 11 is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member 10 is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-like member 20 is 0.8 mm to 3.2 mm; and the length L along the extension direction of each reinforcing portion 40 is 70 mm to 500 mm, and the width dimension w in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm.

[0098] (6) As shown in Figure 3B, etc., the impact absorbing member 1 described in any one of (1) to (3) above may have each reinforcing portion 40 provided only in the range from each side wall portion 12 to each ridge portion EL when viewed in a cross section perpendicular to the longitudinal direction. (7) As shown in Figure 2 etc., the impact absorbing member 1 described in (6) above may have the following configuration: a hollow tube 30 includes a hat-shaped member 10 having a top wall portion 11 that is a bending inner wall portion and side wall portions 12 that are connected to both sides of the top wall portion 11 via the respective ridge portions EL, and a plate-like member 20 that is joined to the hat-shaped member 10 to form a closed cross section; the height dimension H between the top wall portion 11 and the plate-like member 20 is 50 mm to 200 mm, the width dimension W of the top wall portion 11 is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member 10 is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-like member 20 is 0.8 mm to 3.2 mm; and the length L of each reinforcing portion 40 along the extension direction is 70 mm to 500 mm, and the width dimension w of the portion that overlaps with each side wall portion 12 when viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm.

[0099] (8) As shown in Fig. 2, in the impact absorbing member 1 described in any one of (1) to (7) above, the folding trigger may include a left bead Ba and a right bead Bb (first beads) provided on a pair of ridges EL of the hollow tube 30 and at the folding start point BP. (9) As shown in Fig. 7, in the impact absorbing member 1 described in any one of (1) to (8) above, the folding trigger may include a horizontally elongated bead (second bead) Bc provided at the folding start point BP of the top wall portion 11 and elongated in a direction intersecting the longitudinal direction. (10) As shown in Fig. 8, in the impact absorbing member 1 described in any one of (1) to (9) above, the folding trigger may include a through hole Ta provided at the folding start point BP of the top wall portion 11.

[0100] (11) As shown in Figure 9, in the impact absorbing member 1 described in any one of (1) to (10) above, when the hollow tube 30 is viewed along the longitudinal direction, the portion including the break origin portion BP is defined as the second portion R2, one side of the second portion R2 is defined as the first portion R1, and the other side of the second portion R2 is defined as the third portion R3, a break trigger may be provided in each of the first portion R1 and the third portion R3 and may include long vertical beads (third beads) Bd, Be along the longitudinal direction. (12) As shown in FIG. 11, in the impact absorbing member 1 described in any one of (1) to (11) above, when the hollow tube 30 is viewed along the longitudinal direction, the portion including the break starting point BP is defined as the second portion R2, one side of the second portion R2 is defined as the first portion R1, and the other side of the second portion R2 is defined as the third portion R3, the break trigger may include at least one of a difference in plate thickness and a difference in material strength between the second portion R2 and the first portion R1 and the third portion R3.

[0101] (13) As shown in Figure 12 etc., in the impact absorbing member 1 described in any one of (1) to (12) above, the folding trigger may include a bent shape of the hollow tube 30 that makes the outer surface of the top wall portion 11 concave at the position of the folding trigger portion BP. (14) As shown in Figures 13A to 13C etc., in the impact absorbing member 1 described in any one of (1) to (13) above, when the hollow tube 30 is viewed along the longitudinal direction, and the portion including the folding trigger portion BP is defined as the second portion R2, one side of the second portion R2 is defined as the first portion R1, and the other side of the second portion R2 is defined as the third portion R3, the folding trigger may include filler 50 filled in each of the first portion R1 and the third portion R3 excluding the second portion R2.

[0102] (15) As shown in Figures 13A to 13C, etc., the impact absorbing member 1 described in any one of (1) to (14) above may have the following configuration: the hollow tube 30 has a plate-like member (opposing wall portion) 20 arranged opposite the top wall portion 11 and connected to the pair of side wall portions 12 via a pair of other ridge portions ELx; and further includes another folding trigger provided on the hollow tube 30 and configured to set another folding origin portion BP on the plate-like member 20 at another intermediate position in the longitudinal direction of the hollow tube 30, and a pair of other reinforcing portions 40 extending along the extension direction of each other ridge portion ELx and provided at a position adjacent to each other ridge portion ELx on each outer surface of each side wall portion 12 when the hollow tube 30 is viewed in a cross section perpendicular to the longitudinal direction at the position of the other folding origin portion BP.

[0103] The above-described embodiment and various modifications are merely examples of the present invention, and various modifications and combinations may be made without departing from the spirit and scope of the present invention. For example, the left reinforcing portion 40a and the right reinforcing portion 40b are configured from strip-shaped plate material, but this configuration is not limited thereto. The reinforcing portion 40 may be configured to partially reinforce the same position and shape range as the left reinforcing portion 40a and the right reinforcing portion 40b. Examples of such reinforcement methods include patchwork, tailored weld blanks, beads, and heat treatment. [Example]

[0104] This example corresponds to the first embodiment. In this example, the increase or decrease in maximum load and energy absorption when the presence or absence of a reinforcing portion 40, the length L of the reinforcing portion 40, the width w of the reinforcing portion 40, and the arrangement of the reinforcing portion 40 were varied were calculated and compared. Specifically, the calculation models shown in FIGS. 19(a) to 19(c), 20(a) to 20(c), 21(a) to 21(c), and 22(a) to 22(d) were prepared. Of these calculation models, the one shown in FIG. 21(c) is a model in which a reinforcing portion with a width of 40 mm is attached to the center of the upper plane of the top wall portion 11 along the longitudinal direction of the top wall portion 11 for reinforcement. Hereinafter, the calculation model shown in FIG. 21(c) will be described as a reference model (a conventional example for comparison).

[0105] The maximum load and energy absorption amount were calculated by numerical calculation when each of the above calculation models was subjected to bending deformation under load as shown in FIGS. 16(a) and 16(b). For example, FIG. 17 shows the results of calculations of load fluctuations per deformation stroke for the calculation models shown in FIGS. 19(a) to 19(c) and the reference model shown in FIG. 21(c). In FIG. 17, the horizontal axis represents the deformation stroke (unit: mm), and the vertical axis represents the load (unit: kN). In FIG. 17, the integral of the load values ​​over the deformation stroke range of 0 to 50 mm represents the energy absorption amount (unit: kJ) at a deformation stroke of 50 mm. In FIG. 17, the integral of the load values ​​over the deformation stroke range of 0 to 100 mm represents the energy absorption amount (unit: kJ) at a deformation stroke of 100 mm.

[0106] In each calculation model in Figure 17, the maximum load is the peak value of the largest load that first appears as the deformation stroke increases from 0 mm. From the viewpoint of suppressing the load fluctuations described above, it is preferable to prevent this maximum load from increasing excessively. In addition, from the viewpoint of increasing the amount of energy absorption, it is preferable to suppress the drop in the load value after the maximum load occurs. In other words, by gradually decreasing the drop in the load value, it is possible to increase the load integral value (amount of energy absorption) after the maximum load occurs.

[0107] As shown in Figure 17, the load value of each calculation model drops once, then rises and reaches a secondary peak. Here, it is preferable to accelerate the rise time of the load toward the secondary peak from the viewpoint of increasing the amount of energy absorption. In other words, by accelerating the rise time of the load toward the secondary peak, it is possible to increase the load integral value (amount of energy absorption) after the rise.

[0108] Incidentally, the graph in Figure 18 shows the results of calculating the load variation per deformation stroke for each of the calculation models shown in Figures 20(a) to 20(c). Similar trends are also seen in Figure 18. Furthermore, the load variation per deformation stroke was calculated for each of the calculation models shown in Figures 21(a) and 21(b) and Figures 22(a) to 22(d). The maximum load and the energy absorption amount at the same deformation stroke were then calculated for each case. The energy absorption amount was calculated for a deformation stroke of 50 mm (EA[0,50]) and a deformation stroke of 100 mm (EA[0,100]). The results of each calculation model were compared with the results of the reference model, as described below.

[0109] First, Table 1 shows the results of the maximum load and energy absorption (0-50 mm deformation stroke, 0-100 mm deformation stroke) for each of the cases in FIGS. 19(a) to (c) and the reference model. Similarly, Table 2 shows the results of the maximum load and energy absorption (0-50 mm deformation stroke, 0-100 mm deformation stroke) for each of the cases in FIGS. 20(a) to (c) and the reference model. Similarly, Table 3 shows the results of the maximum load and energy absorption (0-50 mm deformation stroke, 0-100 mm deformation stroke) for each of the cases in FIGS. 21(a) to (c) ((c) is the reference model). Similarly, Table 4 shows the results of the maximum load and energy absorption (0-50 mm deformation stroke, 0-100 mm deformation stroke) for each of the cases in FIGS. 22(a) to (d) and the reference model.

[0110]

[0111]

[0112]

[0113]

[0114] The results of Table 1 are shown in bar graphs in Figures 19(d) to (f). Specifically, Figure 19(d) is a comparison diagram of the maximum load when the length L of the reinforcement portion 40 is changed. Figures 19(e) and 19(f) are comparison diagrams of the amount of energy absorption when the length L of the reinforcement portion 40 is changed. Here, Figure 19(e) shows the amount of energy absorption when the deformation stroke is 0-50 mm, and Figure 19(f) shows the amount of energy absorption when the deformation stroke is 0-100 mm. The calculation models used, from the leftmost bar graph to the rightmost bar graph in each of Figures 19(d) to 19(f), are the reference model in which the reinforcement portion 40 is positioned at the center of the width of the top wall portion 11; a calculation model in which the length L of the reinforcement portion 40 is 260 mm (side wall L260); a calculation model in which the length L of the reinforcement portion 40 is 180 mm (side wall L180); and a calculation model in which the length L of the reinforcement portion 40 is 90 mm (side wall L90).

[0115] Similarly, Figures 20(d) to (f) show bar graphs comparing the results of Table 2. That is, Figure 20(d) is a comparison diagram of the maximum load when the width dimension w and position of the reinforcing part 40 are changed. Also, Figures 20(e) and (f) are comparison diagrams of the energy absorption amount when the width dimension w and position of the reinforcing part 40 are changed. Here, Figure 20(e) shows the energy absorption amount when the deformation stroke is between 0 and 50 mm, and Figure 20(f) shows the energy absorption amount when the deformation stroke is between 0 and 100 mm. The calculation models used, from the leftmost bar graph to the rightmost bar graph in each of Figures 20(d) to (f), are the reference model in which the reinforcing portion 40 is positioned at the center of the width of the ceiling wall portion 11, a calculation model in which the width dimension w of the reinforcing portion 40 is 20 mm (side wall w20), a calculation model in which the width dimension w of the reinforcing portion 40 is 10 mm (side wall w10), and a calculation model in which the width dimension w of the reinforcing portion 40 is 10 mm and is positioned 10 mm below the ridge line (side wall w10-2).

[0116] Similarly, Figures 21(d) to (f) show bar graphs comparing the results of Table 3. That is, Figure 21(d) is a comparison diagram of the maximum load when the width dimension w and position of the reinforcing part 40 are changed. Also, Figures 21(e) and (f) are comparison diagrams of the energy absorption amount when the width dimension w and position of the reinforcing part 40 are changed. Here, Figure 21(e) shows the energy absorption amount when the deformation stroke is between 0 and 50 mm, and Figure 21(f) shows the energy absorption amount when the deformation stroke is between 0 and 100 mm. 21(d) to 21(f), the calculation models used, from the leftmost bar graph to the rightmost bar graph, were the reference model in which reinforcing portion 40 was located at the width center of top wall portion 11, a calculation model (side wall L260) in which reinforcing portion 40 having a width dimension w of 20 mm and a length of 260 mm was located on each side wall portion 12, and a calculation model (ceiling wall ridge portion side w20) in which two reinforcing portions 40 having a width dimension w of 20 mm and a length L of 260 mm were located near ridge portion EL of top wall portion 11. The dashed lines in FIGS. 19(d) to 19(f), 20(d) to 20(f), 21(d) to 21(f), and 22(e) to 22(g) indicate the numerical values ​​of the reference model used for comparison.

[0117] Finally, Figures 22(e) to (g) show bar graphs comparing the results of Table 4. That is, Figure 22(e) is a comparison diagram of the maximum load when the reinforcing portion 40 is arranged so as to overlap the ridge line portion EL. Figures 22(f) and (g) are comparison diagrams of the amount of energy absorption when the reinforcing portion 40 is arranged so as to overlap the ridge line portion EL. Here, Figure 22(f) shows the amount of energy absorption when the deformation stroke is between 0 and 50 mm, and Figure 22(g) shows the amount of energy absorption when the deformation stroke is between 0 and 100 mm. The calculation models used, from the leftmost bar graph to the rightmost bar graph in each of Figures 22(e) to (g), are the reference model in which the reinforcing portion 40 is positioned at the center of the width of the ceiling wall portion 11, a calculation model in which the reinforcing portion 40 is positioned only at the ridge portion EL (ridge portion R), a calculation model in which the reinforcing portion 40 at the ridge portion R is further extended by 10 mm in width toward the ceiling wall portion 11 (ridge portion + ceiling wall), a calculation model in which the reinforcing portion 40 at the ridge portion R is further extended by 10 mm in width toward the side wall portion 12 (ridge portion + side wall), and a calculation model in which the reinforcing portion 40 at the ridge portion R is further extended by 10 mm in width toward both the ceiling wall portion 11 and the side wall portion 12 (ceiling wall ridge portion side + side wall ridge portion side w10mm).

[0118] The comparison results for each calculation model are described below. First, in Figures 19(d) to (f), the calculation models other than the reference model correspond to examples of the invention. As shown in each bar graph, all of the bar graphs corresponding to examples of the invention succeed in achieving a higher energy absorption amount than the reference model, while keeping the maximum load lower than the comparison model. Therefore, these examples of the invention can achieve a high collision energy absorption amount with a short deformation stroke while suppressing sudden load fluctuations.

[0119] In the following Figures 20(d)-(f), two comparative examples are the reference model and a calculation model (side wall w10-2) in which the reinforcing portion 40 has a width dimension w of 10 mm and is positioned 10 mm below the ridgeline. The other two cases correspond to inventive examples. As shown in the bar graphs, all of the inventive examples successfully achieved higher energy absorption than the reference model while maintaining a lower maximum load than the comparison model. Therefore, these inventive examples achieve high collision energy absorption with a short deformation stroke while suppressing sudden load fluctuations. On the other hand, the comparative calculation model shown in the bar graphs at the right end of Figures 20(e) and (f) achieved higher energy absorption than the reference model at long deformation strokes (100 mm deformation strokes), but did not achieve much change in energy absorption compared to the reference model at short deformation strokes. These results confirm that positioning the reinforcing portion 40 adjacent to the ridgeline EL without being too far away is effective in achieving high energy absorption with a short deformation stroke.

[0120] 21(d) to (f), only the calculation model for "side wall L260" corresponds to an example of the invention. As shown in each bar graph, only the calculation model for "side wall L260" succeeded in achieving a higher energy absorption amount than the "standard" while suppressing the maximum load below that of the standard model. Therefore, according to this example of the invention, a high collision energy absorption amount can be obtained with a short deformation stroke while suppressing sudden load fluctuations.

[0121] In the following Figures 22(e) to (g), only the "ridgeline + sidewall" calculation model (calculation model in Figure 22(c)) corresponds to an example of the invention. When the maximum load is kept approximately constant as shown in Figure 22(e), the highest energy absorption amount is successfully obtained, as shown in Figures 22(f) and (g). Therefore, according to this example of the invention, a high collision energy absorption amount can be obtained with a short deformation stroke while suppressing sudden load fluctuations.

[0122] In the above-described embodiment, the folding deformation is exemplified with the top wall 11 side being the inside of the bending, but the present invention is not limited to this, and by appropriately adjusting the position of the folding start point, it is also possible to adopt a folding deformation with the plate-like member 20 side being the inside of the bending. This also applies to all the embodiments described below.

[0123] Second Embodiment The shock absorbing member absorbs impact force by bending deformation rather than bellows deformation. Hereinafter, the bending deformation range shown in FIG. 1 is designated by reference numeral 101, and this will be described as the shock absorbing member 101. That is, in this second embodiment, to distinguish it from the configuration of the first embodiment, the reference numerals of the shock absorbing member will be changed from 1 to 101 in the following description. In this second embodiment, a case will be described in which a bending start point 100BP of the bending deformation is set in the top wall portion 111.

[0124] As shown in Figure 23 , the impact absorbing member 101 of the second embodiment includes a hollow tube 130 that is long in the longitudinal direction along its center line CL, and a reinforcement 140 fixedly disposed within the hollow tube 130. The hollow tube 130 has a rectangular cross section perpendicular to the center line CL and includes a hat-shaped member 110, a plate-shaped member 120, and a reinforcing portion 240. In Figure 23 , the X direction indicates the vehicle's longitudinal direction, the Y direction indicates the vehicle's width direction, and the Z direction indicates the vehicle's height direction. Note that, for convenience of explanation, the following description may refer to the X direction in Figure 23 as the longitudinal direction of the impact absorbing member 101, the Y direction as the height direction of the impact absorbing member 101, and the Z direction as the width direction of the impact absorbing member 101.

[0125] The hat-shaped component 110 has a top wall 111, a pair of side walls 112, and a pair of flanges 113. The top wall 111 forms the hat top of the hat-shaped component 110 when viewed along the center line CL. The top wall 111 is a long plate having a substantially constant width W and a substantially constant thickness T1, and extends along the center line CL. The top wall 111 has a flat upper surface and a flat lower surface. The width W can be exemplified as 30 mm to 100 mm. The thickness T1 can be exemplified as 0.8 mm to 3.2 mm. The values ​​for the thickness T1 exemplified here are for the case where the impact absorbing component 101 is made of steel. If the impact absorbing component 101 is manufactured using extruded aluminum, the upper limit of the thickness T1 can be exemplified as 4.0 mm. The width W and thickness T1 of the top wall 111 do not necessarily have to be constant at each position on the center line CL, and may be changed at each position along the center line CL as required for the part design. Similarly, the upper and lower surfaces of the top wall 111 do not necessarily have to be flat, and may have some unevenness as required for the part design.

[0126] The pair of side walls 112 includes a left side wall 112a and a right side wall 112b. The left side wall 112a is a vertical wall integrally connected to one of the side edges of the top wall 111. In a cross section perpendicular to the center line CL, the angle formed between the left side wall 112a and the top wall 111 may be 90° or slightly larger than 90°. The left side wall 112a is an elongated plate having a substantially constant width and thickness and extending in the direction along the center line CL. The left side wall 112a has a flat outer surface and a flat inner surface. The right side wall 112b is a vertical wall integrally connected to the other of the side edges of the top wall 111. In a cross section perpendicular to the center line CL, the angle formed between the right side wall 112b and the top wall 111 may be 90° or slightly larger than 90°. The right side wall portion 112b is a long plate having a substantially constant width and a substantially constant thickness, and is elongated in the direction along the center line CL. The right side wall portion 112b has a flat outer surface and a flat inner surface. Note that the width and thickness of the left side wall portion 112a and the right side wall portion 112b do not necessarily have to be constant at each position along the center line CL, and may vary at each position along the center line CL as required by the component design. Similarly, the outer and inner surfaces of the right side wall portion 112b and the left side wall portion 112a do not necessarily have to be flat, and may have some unevenness as required by the component design.

[0127] The pair of flange portions 113 includes a left flange portion 113a and a right flange portion 113b. The left flange portion 113a is integrally connected to the lower edge of the left side wall portion 112a. The left flange portion 113a is a strip-shaped plate having a substantially constant width and thickness and is elongated in the direction along the center line CL. The left flange portion 113a has a flat upper surface and a flat lower surface. The right flange portion 113b is integrally connected to the lower edge of the right side wall portion 112b. The right flange portion 113b is a strip-shaped plate having a substantially constant width and thickness and is elongated in the direction along the center line CL. The right flange portion 113b also has a flat upper surface and a flat lower surface. Note that the width and thickness of the left flange portion 113a and the right flange portion 113b do not necessarily have to be constant at each position along the center line CL and may vary at each position along the center line CL as required by the component design. Similarly, the upper and lower surfaces of the left flange portion 113 a and the right flange portion 113 b do not necessarily have to be flat, and may have some irregularities depending on the shape of the plate-like member 120 .

[0128] A ridgeline 100EL parallel to the center line CL is formed between the top wall 111 and the left side wall 112a. This ridgeline 100EL is a curved portion formed between the side edge of the flat outer surface of the top wall 111 and the side edge of the flat outer surface of the left side wall 112a, and has an arc-shaped outer surface with a predetermined width when viewed along the center line CL. A ridgeline 100EL parallel to the center line CL is also formed between the top wall 111 and the right side wall 112b. This ridgeline 100EL is also a curved portion formed between the side edge of the flat outer surface of the top wall 111 and the side edge of the flat outer surface of the right side wall 112b, and has an arc-shaped outer surface with a predetermined width when viewed along the center line CL.

[0129] The combination of the top wall 111, left side wall 112a, and right side wall 112b forms a generally trapezoidal shape in a cross section perpendicular to the center line CL. Furthermore, by combining this combination with the left flange 113a and right flange 113b, the hat-shaped member 110 is formed, whose cross section perpendicular to the longitudinal direction is hat-shaped. The hat-shaped member 110 is obtained by pressing a stamped plate material. The material of the hat-shaped member 110 is metal, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used.

[0130] The plate-shaped member 120 is a long metal plate extending along the center line CL, and is preferably made of a high-strength steel plate with a tensile strength of 590 MPa or greater. The plate-shaped member 120 has a flat upper surface and a flat lower surface. The plate-shaped member 120 is welded to the left flange portion 113a and the right flange portion 113b at both side edges thereof. This forms a closed cross section between the hat-shaped member 110 and the plate-shaped member 120. The width and thickness of the plate-shaped member 120 do not necessarily have to be constant at each position along the center line CL, and may vary at each position along the center line CL as required by the component design. Similarly, the upper and lower surfaces of the plate-shaped member 120 do not necessarily have to be flat, and may have some irregularities as required by the component design.

[0131] As shown in Figures 23 to 24B, the reinforcement 140 has a vertical plate 141, a horizontal plate 142, and a folding trigger. The folding trigger will be described later with reference to Figures 28 to 42. The vertical plate 141 is a single strip-shaped plate having a substantially constant width and a substantially constant thickness, and is elongated in the direction along the center line CL. The vertical plate 141 has a flat left side surface and a flat right side surface. Although the vertical plate 141 forms a single strip-shaped plate, when viewed in a cross section perpendicular to the longitudinal direction of the impact absorbing member 101, it is apparently divided into two by the horizontal plate 142, which intersects with the vertical plate 141 at the center position in the height direction. The upper and lower portions of this divided vertical plate 141 have the same height and length dimensions.

[0132] The horizontal plate 142 is a single strip-shaped plate having a substantially constant width and thickness, and is long in the direction along the center line CL. The horizontal plate 142 has a flat upper surface and a flat lower surface. Although the horizontal plate 142 is a single strip-shaped plate, when viewed in a cross section perpendicular to the longitudinal direction of the impact absorbing member 101, it is apparently divided into two by the vertical plate 141 that intersects at the center position in the width direction. The left and right portions of this divided horizontal plate 142 have the same width, thickness, and length.

[0133] The reinforcement 140 has a "+" shape when viewed in a cross section perpendicular to the longitudinal direction of the impact absorbing member 101. The center line CL of the impact absorbing member 101 passes through the intersection between the vertical plate 141 and the horizontal plate 142. The vertical plate 141 and the horizontal plate 142 can be joined by welding, for example. When viewed in a cross section perpendicular to the longitudinal direction of the impact absorbing member 101, the vertical plate 141 has an upper end (one end) joined to the lower surface of the top wall portion 111 at the center in the width direction, and a lower end joined to the upper surface of the plate-like member 120 at the center in the width direction. In this way, the top wall portion 111 is supported mainly by the vertical plate 141 and the plate-like member 120.

[0134] The horizontal plate 142 has its left end (one end) joined to the center of the height direction of the inner surface of the left side wall portion 112a and its right end (the other end) joined to the center of the height direction of the inner surface of the right side wall portion 112b when viewed in a cross section perpendicular to the longitudinal direction of the impact absorbing member 101. In this way, the horizontal plate 142 restrains the left side wall portion 112a and the right side wall portion 112b so that the distance between them is kept constant.

[0135] A high-strength steel plate having a tensile strength of 590 MPa or more can be suitably used as the reinforcement 140. That is, the reinforcement 140 can be manufactured by intersecting a vertical plate 141 and a horizontal plate 142 made of the high-strength steel plate with each other and then welding them together. The reinforcement 140 is then fixed inside the hollow tube 130 by welding. Note that, although the reinforcement 140 having a "+" shape is used in this embodiment, it is not limited to this and reinforcements having other configurations may also be used.

[0136] As shown in FIG. 23 , the reinforcing portion 240 includes a left reinforcing portion 240a and a right reinforcing portion 240b. As shown in FIGS. 23 and 24A , the left reinforcing portion 240a is a long, strip-shaped metal plate extending along the center line CL. Its material is preferably a high-strength steel plate with a tensile strength of 590 MPa or greater. The left reinforcing portion 240a is fixed by welding to the longitudinal center of the left side wall portion 112a, adjacent to the ridge line portion 100EL. The left reinforcing portion 240a has a length L along the center line CL of 70 mm to 500 mm, a width w in a cross section perpendicular to the center line CL of 10 mm to 60 mm, and a thickness of 0.8 mm to 3.2 mm. The thickness values ​​exemplified here are for a case in which the impact absorbing member 101 is made of steel. When the impact absorbing member 101 including the left reinforcing portion 240a is manufactured from an aluminum extrusion material, the upper limit of the plate thickness of the left reinforcing portion 240a can be set to 4.0 mm, for example.

[0137] Similarly, the right reinforcing portion 240b is a long, strip-shaped metal plate extending along the center line CL, and is preferably made of a high-strength steel plate with a tensile strength of 590 MPa or greater. The right reinforcing portion 240b is fixed by welding to the longitudinal center of the right side wall portion 112b, adjacent to the ridge line portion 100EL. The right reinforcing portion 240b has the same shape as the left reinforcing portion 240a. That is, the right reinforcing portion 240b has a length L along the center line CL of 70 mm to 500 mm, a width dimension w in a cross section perpendicular to the center line CL of 10 mm to 60 mm, and a thickness of 0.8 mm to 3.2 mm. The thickness values ​​exemplified here are for the case where steel is used as the material for the impact absorbing member 101. If the impact absorbing member 101, including the right reinforcing portion 240b, is manufactured from an aluminum extrusion, an example upper limit for the thickness of the right reinforcing portion 240b is 4.0 mm. The length L of the left reinforcing portion 240a and the length L of the right reinforcing portion 240b are the same. The width w of the left reinforcing portion 240a and the width w of the right reinforcing portion 240b are also the same. The plate thickness of the left reinforcing portion 240a and the plate thickness of the right reinforcing portion 240b are also the same. The left reinforcing portion 240a reinforces only the portion of the left side wall portion 112a near the ridge line 100EL. Similarly, the right reinforcing portion 240b reinforces only the portion of the right side wall portion 112b near the ridge line 100EL. Therefore, the upper surface of the ceiling wall portion 111 and the upper surfaces of the ridge lines 100EL are not reinforced. In other words, the left reinforcing portion 240a and the right reinforcing portion 240b reinforce only the portions of the left side wall portion 112a and the right side wall portion 112b near the ridge line 100EL, avoiding the upper surface of the ceiling wall portion 111 and the pair of ridge lines 100EL.

[0138] As shown in FIG. 24B , the left reinforcing portion 240a and the right reinforcing portion 240b may reinforce the hat-shaped member 110, including the upper surface of the ridge portion 100EL, while avoiding the upper surface of the top wall portion 111. That is, the left reinforcing portion 240a may be joined by welding or the like to both a position on the left side wall portion 112a near the ridge portion 100EL and a position overlapping the ridge portion 100EL. Similarly, the right reinforcing portion 240b may be joined by welding or the like to both a position on the right side wall portion 112b near the ridge portion 100EL and a position overlapping the ridge portion 100EL. In this modification, as shown in FIG. 24B , the shape of the left reinforcing portion 240a in a cross section perpendicular to the center line CL is bent so that its upper end is in close contact with the upper surface of the ridge portion 100EL.

[0139] 24B , the length L of both the left reinforcing portion 240a and the right reinforcing portion 240b can be 70 mm to 500 mm. Meanwhile, the width (total width) of the left reinforcing portion 240a and the right reinforcing portion 240b needs only to ensure a width w (partial width) of 10 mm to 60 mm for the flat portions that overlap the left sidewall portion 112a and the right sidewall portion 112b, and the width (partial width) of the portions that overlap the ridge line portion 100EL can be any value. However, it is necessary to set the left reinforcing portion 240a and the right reinforcing portion 240b so that they do not overlap the top wall portion 111.

[0140] Although high-strength steel plate has been exemplified above as the material for the reinforcing portion 240 (left reinforcing portion 240a and right reinforcing portion 240b), other materials such as SUS430, SUS304, SUS316, SUS304N1, SUS316N, or an Fe-Mn-Si shape memory alloy (such as an Fe-28Mn-6Si-5Cr alloy or an Fe-15Mn-4Si-10Cr-8Ni alloy) may also be used.

[0141] One of the pair of ridge lines 100EL is a corner connecting the top wall 111 and the left side wall 112a, and has a predetermined radius of curvature in the cross section shown in Figures 24A and 24B. The other of the pair of ridge lines 100EL is a corner connecting the top wall 111 and the right side wall 112b, and also has a predetermined radius of curvature.

[0142] The folding trigger is a folding start point 100BP set in the top wall portion 111 of the hollow tube 130 at one position midway along the longitudinal direction of the impact absorbing member 101. In other words, the folding start point is a configuration for folding the hollow tube 130 so that the outer surface of the top wall portion 111 forms a locally concave surface at the folding start point 100BP of the top wall portion 111, and various configurations are possible. The folding start point is provided not in the hollow tube 130 but in the reinforcement 140, the details of which will be described in detail in the description of Figures 28 to 42. When the impact absorbing member 101 is folded at the folding start point 100BP, the energy of the collision is absorbed by the folding deformation of the hollow tube 130 and the folding deformation of the reinforcement 140. First, the energy absorption caused by the folding deformation of the hollow tube 130 at the folding start point 100BP will be described.

[0143] The fold initiation point 100BP in the hollow tube 130 is indicated by hatching in FIG. 23 and is included in the area where the impact absorbing member 101 will buckle and break when subjected to impact energy in the -X direction. This fold initiation point 100BP is a portion that was preset during the design phase and actively initiates the start of the fold deformation. In the impact absorbing member 101 of this embodiment, the fold initiation point 100BP is positioned at a longitudinal midpoint of the reinforcement portion 240. In other words, the left reinforcement portion 240a is positioned on the left sidewall portion 112a so that the fold initiation point 100BP is located midpoint along its length. Similarly, the right reinforcement portion 240b is positioned on the right sidewall portion 112b so that the fold initiation point 100BP is located midpoint along its length. The fold initiation point 100BP is preferably positioned at a longitudinal center position of the left reinforcement portion 240a and the right reinforcement portion 240b. Furthermore, the length L of each of the left and right reinforcing portions 240a and 240b along their extension direction is at least twice the buckling range length LB at the position of the folding start point 100BP of the left and right sidewall portions 112a and 112b. This allows for a high degree of collision energy absorption with a short deformation stroke while suppressing sudden load fluctuations. The mechanism behind this is explained below with reference to Figures 25 to 27.

[0144] FIG. 25 is a diagram showing the process of bending deformation of the impact absorbing member 101 under an axial compressive bending load, and is a perspective view showing the bent state after the maximum load occurs. FIG. 26 is a diagram continuing the bending deformation process of FIG. 25 , and is a perspective view showing the state at the time when the rise of the secondary peak load occurs. As shown in FIG. 25 , when the impact absorbing member 101 receives collision energy along its longitudinal direction, it bends at the position of the bending origin 100BP, with the outer surface (top surface) of the top wall portion 111 bent inward. The absorption of collision energy during this bending deformation is achieved by the deformation at the bending origin 100BP, in which the top surface of the top wall portion 111 is recessed, the deformation of the left side wall portion 112a and the right side wall portion 112b in an "L" shape as they move away from each other, and the deformation of the left reinforcing portion 240a and the right reinforcing portion 240b in an "L" shape as they move away from each other. At this time, compressive deformation occurs mainly at the top wall 111, left side wall 112a, and right side wall 112b of the folding start point 100BP. Meanwhile, tensile deformation occurs at the left reinforcing portion 240a and the right reinforcing portion 240b. These compressive and tensile deformations absorb the collision energy.

[0145] The greater the structural strength of the top wall portion 111, the higher the maximum load of the impact absorbing member 101 when impact energy is applied. If the maximum load is too high, the load drop due to bending deformation after the maximum load occurs will also be rapid. In a vehicle equipped with the impact absorbing member 101, it is preferable to avoid such large load fluctuations being applied to the occupants during a collision. In the impact absorbing member 101 of this embodiment, the left reinforcing portion 240a and the right reinforcing portion 240b are arranged adjacent to each ridge line portion 100EL and extend along the extension direction of each ridge line portion 100EL. In other words, these left reinforcing portion 240a and right reinforcing portion 240b do not reinforce the top wall portion 111, so the maximum load of the impact absorbing member 101 does not need to be excessively increased.

[0146] On the other hand, as described above, collision energy is absorbed by the folding deformation of the top wall portion 111 and the buckling deformation of the left and right side walls 112a and 112b into an "L" shape at the folding start point 100BP. At this time, the left and right side walls 112a and 112b are reinforced by the left and right reinforcing portions 240a and 240b, making them less likely to bend into an "L" shape. This allows for a gentler drop in load after the occurrence of maximum load in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram). As a result, the maximum load value in the FS diagram can be suppressed while the load integral value after the occurrence of maximum load can be increased. This allows for a greater amount of energy absorption.

[0147] Furthermore, the rise time of the secondary peak load in the FS diagram can be advanced. To explain this, first, the "L"-shaped portions of the left reinforcing portion 240a and the right reinforcing portion 240b that are bent due to buckling deformation gradually close. Then, as a result of the "L" being completely closed, the two straight portions of the ridgeline portion 100EL on either side of the "L" portion butt against each other, resulting in the state shown in FIG. 26 . This butting of the two straight portions of the ridgeline portion 100EL causes the rise of the secondary peak load.

[0148] The deformation of the ridgeline portion 100EL during the above-described bending deformation process is shown in Figure 27. This Figure 27 is a diagram for explaining the bending deformation process, and is a schematic diagram showing a plan view of part B of the ridgeline portion 100EL of the impact absorbing member 101 in Figure 25, which includes the bending starting point 100BP and its surrounding area. In this Figure 27, the solid line indicates the ridgeline portion 100EL in the impact absorbing member 101 of this embodiment, and the imaginary line indicates the ridgeline portion 100EL' in a conventional structure that does not have the reinforcing portion 240.

[0149] At the ridgeline portion 100EL' shown by the imaginary line, the sidewall portions 112 (left sidewall portion 112a and right sidewall portion 112b) are not reinforced by the reinforcing portions 240 (left reinforcing portion 240a and right reinforcing portion 240b), so the "L" shape that occurs in the buckling range is larger. On the other hand, in the impact absorbing member 101 of this embodiment, the upper edge of the left sidewall portion 112a is reinforced by the left reinforcing portion 240a, and the upper edge of the right sidewall portion 112b is reinforced by the right reinforcing portion 240b. In other words, each corner of the hat-shaped member 110 corresponding to each of the pair of ridgeline portions 100EL is essentially reinforced. Therefore, as shown in FIG. 27 , the deformation area of ​​the ridgeline portion 100EL is localized compared to the ridgeline portion 100EL', resulting in a smaller "L" shape. As a result, interference between the pair of straight portions of the ridgeline portion 100EL begins earlier. This accelerates the rise of the secondary peak load.

[0150] Furthermore, in the impact absorbing member 101 of this embodiment, each side wall 112 (left side wall 112a and right side wall 112b) is reinforced with each reinforcing portion 240 (left reinforcing portion 240a and right reinforcing portion 240b), so the two straight line portions of the ridgeline 100EL can continue to butt against each other strongly while being prevented from bending. As a result, the period during which the secondary peak load is applied can be extended. Therefore, the load integral value after the rise of the secondary peak load in the FS diagram can also be increased, thereby increasing the amount of energy absorption.

[0151] As described above, in the impact absorbing member 101 of this embodiment, the length L of each of the left reinforcing portion 240a and the right reinforcing portion 240b is at least twice the buckling range length LB shown in FIG. 23 . The buckling range length LB here refers to the maximum length dimension along the center line CL of the range that buckles during bending deformation. This maximum value can be set in advance by performing numerical calculations during the design stage or by manufacturing a sample material and conducting a load test. By making the length L of the left reinforcing portion 240a and the right reinforcing portion 240b at least twice the buckling range length LB, when the buckling range is completely buckled as shown in FIG. 26 , a pair of linear portions of each ridge portion 100EL that are connected across the buckling range can more reliably butt against each other. Therefore, it is preferable that the length L be at least twice the length LB.

[0152] Next, with reference to FIGS. 28 to 42 , the following describes the folding trigger provided in the reinforce 140 and the energy absorption due to folding deformation at the folding starting point 100BP set by this folding trigger. FIG. 28 is a perspective view showing an example of a folding trigger provided in the reinforce 140, with the hollow tube 130 omitted from the illustration. In this example, the reinforce 140 has one through-hole 251 formed at the longitudinal center and at the upper height position of the vertical plate 141. More specifically, the through-hole 251 is formed at a position between the vertical center and the upper end of the vertical plate 141. In this example, the through-hole 251 is a circular through-hole, but it is not limited to a circle. Alternatively, an elliptical, rectangular, polygonal, or other shape may be used. Furthermore, although one through-hole 251 is formed, two or more through-holes may be formed. Furthermore, if multiple through-holes are formed, their shapes and sizes may differ from each other.

[0153] The through-holes 251 may be formed in the horizontal plate 142 instead of the vertical plate 141. In this case, the through-holes 251 are preferably formed at the longitudinal center of the horizontal plate 142, one on each of the left and right portions of the horizontal plate 142, with the vertical plate 141 sandwiched between them. Furthermore, the through-holes 251 in the left portion and the right portion preferably have the same shape and size. This allows the bending strength on the left and right sides of the center line CL of the impact absorbing member 101 to be equal, thereby enabling precise control of the bending direction with the upper surface of the top wall portion 111 on the inside of the bending. While the number of through-holes 251 formed in the horizontal plate 142 is two, an even number of two or more may be formed. In this case, it is also preferable that the through-holes 251 in the left portion and the through-holes 251 in the right portion be the same size and number. Furthermore, the through-holes 251 may be formed in both the vertical plate 141 and the horizontal plate 142, as described above.

[0154] FIG. 29 is a perspective view showing another example of a folding trigger provided in the reinforcement 140, with the hollow tube 130 not shown. In this example, the reinforcement 140 has one through-hole 252 formed in the longitudinal center of the vertical plate 141 and at the top end position in the height direction. More specifically, the through-hole 252 is a semicircular notch formed in the upper edge of the vertical plate 141. The shape of the through-hole 252 is not limited to a semicircular shape, and may alternatively be a semi-ellipse, a rectangle, a polygon, or the like. Furthermore, although one through-hole 252 is formed in the above example, two or more through-holes 252 may be formed. Furthermore, when a plurality of through-holes 252 are formed, the shapes and sizes of the through-holes 252 may be different from each other.

[0155] The through-holes 252 may be formed in the horizontal plate 142 instead of the vertical plate 141. In this case, the through-holes 252 are preferably formed at the longitudinal center of the horizontal plate 142, one on each of the left and right portions of the horizontal plate 142, with the vertical plate 141 sandwiched between them. Furthermore, the through-holes 252 in the left portion and the right portion preferably have the same shape and size. In this case, as in the example shown in FIG. 28 , the bending strengths on the left and right sides of the center line CL of the impact absorbing member 101 can be equalized, thereby enabling precise control of the bending direction with the upper surface of the top wall portion 111 on the inside of the bending. While the number of through-holes 252 formed in the horizontal plate 142 is two, an even number of two or more may be used. In this case, it is also preferable that the through-holes 252 in the left portion and the right portion be the same size and number. Furthermore, the through-holes 252 may be formed in both the vertical plate 141 and the horizontal plate 142, as described above.

[0156] Next, FIG. 30 is a perspective view showing yet another example of the reinforcement 140 provided in the impact absorbing member 101. In the reinforcement 140 of this example, a single long bead 253 is formed in a direction intersecting the longitudinal direction of the impact absorbing member 101 (the extension direction of the center line CL) at a position in the longitudinal center and at the upper position in the height direction of the vertical plate 141. More specifically, the bead 253 is formed in a straight line from the center position in the height direction of the vertical plate 141 to the upper end position of the vertical plate 141. When the side surface of the vertical plate 141 is viewed from the front, the intersecting angle of the bead 253 with respect to the center line CL is preferably a right angle, but may be slightly inclined. Furthermore, although the number of beads 253 is one in the above embodiment, two or more beads may be used. Furthermore, when multiple beads 253 are used, the beads may have different thicknesses and lengths. Furthermore, when multiple beads 253 are used, it is preferable to arrange them closely to each other.

[0157] The beads 253 may be formed on the horizontal plate 142 instead of the vertical plate 141. In this case, they are preferably formed at the longitudinal center of the horizontal plate 142, one on each of the left and right portions of the horizontal plate 142, with the vertical plate 141 sandwiched between them. The beads 253 on the left and right portions are preferably coaxial and formed along a direction intersecting the longitudinal direction of the impact absorbing member 101 (the direction of extension of the center line CL). The beads 253 on the left and right portions preferably have the same length and thickness. In this case, as in the example shown in FIG. 28 , the bending strength on the left and right sides of the center line CL of the impact absorbing member 101 can be made equal, thereby enabling precise control of the bending direction with the upper surface of the top wall portion 111 on the inside of the bending. Although the number of beads 253 is one pair (two), more than two may be used. Furthermore, when a plurality of beads 253 are used, the beads may have different thicknesses or lengths. However, when a plurality of beads 253 are used, it is preferable to arrange them symmetrically with respect to the center line CL.

[0158] 28 to 30, the bending strength of the second portion 100R2 is set lower than the bending strength of the first portion 100R1 and the bending strength of the third portion 100R3 by forming any one of the through portion 251, the through portion 252, and the bead 253 in the second portion 100R2. In other words, a relative bending strength difference is provided so that the bending strength of the second portion 100R2 is lower than the bending strength of the first portion 100R1 and the third portion 100R3. Such a bending strength difference can also be set by the examples shown in FIGS. 31 to 33.

[0159] FIG. 31 is a perspective view showing yet another example of the reinforcement 140 provided in the impact absorbing member 101. In the reinforcement 140 of this example, a single long bead (rigid portion) 254 is formed in a first portion 100R1 of the upper portion of the vertical plate 141 along the longitudinal direction of the impact absorbing member 101 (extension direction of the center line CL). Similarly, a single long bead (rigid portion) 254 is also formed in a second portion 100R2 of the upper portion of the vertical plate 141 along the longitudinal direction of the impact absorbing member 101 (extension direction of the center line CL). This pair of beads 254 are arranged at the same height and on the same straight line. On the other hand, no bead 254 is formed in the second portion 100R2 of the upper portion of the vertical plate 141, and the second portion 100R2 remains flat. Therefore, the upper portion of the vertical plate 141 is reinforced in the first portion 100R1, the second portion 100R2, and the third portion 100R3, except for the second portion 100R2 located in the center. Although the number of beads 254 is one pair (two), it may be two or more. Furthermore, when multiple beads 254 are used, the beads may have different thicknesses or lengths. However, when multiple beads 254 are used, it is preferable to arrange them symmetrically between the first portion 100R1 and the third portion 100R3.

[0160] The beads 254 may be formed on the horizontal plate 142 instead of the vertical plate 141. In this case, the beads are formed on both the first portion 100R1 and the third portion 100R3 of the horizontal plate 142. Specifically, one bead 254 is formed on each of the left and right portions of the first portion 100R1 of the horizontal plate 142, with the vertical plate 141 sandwiched therebetween. In addition, one bead 254 is formed on each of the left and right portions of the third portion 100R3 of the horizontal plate 142, with the vertical plate 141 sandwiched therebetween. On the left side of the horizontal plate 142, the beads 254 on the first portion 100R1 and the beads 254 on the third portion 100R3 are preferably coaxial with each other and formed along the longitudinal direction of the impact absorbing member 101 (the extension direction of the center line CL). Similarly, on the right side of the horizontal plate 142, it is preferable that the bead 254 at the first portion 100R1 and the bead 254 at the third portion 100R3 are coaxial with each other and are formed along the longitudinal direction of the impact absorbing member 101 (the extension direction of the center line CL).

[0161] Furthermore, in both the first portion 100R1 and the third portion 100R3, the beads 254 in the left and right portions preferably have the same length and thickness. In this case, similar to the example shown in FIG. 28 , the bending strength can be equalized on both sides of the center line CL of the impact absorbing member 101, allowing for precise control of the bending direction with the upper surface of the top wall portion 111 on the inside of the bending. While the number of beads 254 is one pair (two) in both the first portion 100R1 and the third portion 100R3, two or more pairs may be provided for each. Furthermore, when multiple beads 254 are provided, their thicknesses and lengths may differ. However, when multiple beads 254 are provided, it is preferable to arrange them symmetrically across the center line CL. On the other hand, the second portion 100R2 of the horizontal plate 142 does not have any beads 254 and remains flat. Therefore, the horizontal plate 142 is reinforced in the first portion 100R1, the second portion 100R2, and the third portion 100R3, except for the second portion 100R2 located in the center. The unreinforced second portion 100R2 of the reinforcement 140 functions as a breakage trigger.

[0162] FIG. 32 is a perspective view showing yet another example of a reinforcement 140 provided in the impact absorbing member 101. In this example, a single long angle iron 255 is welded to a first portion 100R1 of the upper portion of the vertical plate 141, extending along the longitudinal direction of the impact absorbing member 101 (the direction of extension of the center line CL). Similarly, a single long angle iron 255 is welded to a third portion 100R3 of the upper portion of the vertical plate 141, extending along the longitudinal direction of the impact absorbing member 101 (the direction of extension of the center line CL). This pair of angle irons 255 are arranged at the same height and on the same straight line. Each angle iron 255 is welded so that its flat surface (outer surface) is surface-joined to the side surface of the upper portion of the vertical plate 141. On the other hand, no angle iron 255 is fixed to a second portion 100R2 of the upper portion of the vertical plate 141, and the second portion 100R2 remains flat. Therefore, the upper portion of the vertical plate 141 is reinforced in the first portion 100R1, the second portion 100R2, and the third portion 100R3, except for the second portion 100R2 located in the center. Although the number of angle irons 255 is one pair (two), it may be two or more. Furthermore, when using multiple angle irons 255, the thicknesses and lengths of the angle irons may be different. However, when using multiple angle irons 255, it is preferable to arrange them symmetrically between the first portion 100R1 and the third portion 100R3.

[0163] As shown in FIG. 33 , the angle iron 255 may be fixed to the horizontal plate 142 instead of the vertical plate 141. In this case, the angle irons 255 are fixed to both the first portion 100R1 and the third portion 100R3 of the horizontal plate 142. Specifically, at the first portion 100R1 of the horizontal plate 142, one angle iron 255 is fixed by welding to each of the left and right portions, with the vertical plate 141 sandwiched therebetween. In addition, at the third portion 100R3 of the horizontal plate 142, one angle iron 255 is fixed by welding to each of the left and right portions, with the vertical plate 141 sandwiched therebetween. On the left side of the horizontal plate 142, the angle iron 255 at the first portion 100R1 and the angle iron 255 at the third portion 100R3 are preferably coaxial with each other and arranged along the longitudinal direction of the impact absorbing member 101 (the extension direction of the center line CL). Similarly, on the right side of the horizontal plate 142, it is preferable that the angle iron 255 at the first portion 100R1 and the angle iron 255 at the third portion 100R3 are coaxial with each other and arranged along the longitudinal direction of the impact absorbing member 101 (the extension direction of the center line CL).

[0164] Furthermore, in both the first section 100R1 and the third section 100R3, the angle irons 255 in the left and right sections preferably have the same length and thickness. In this case, as in the example shown in FIG. 28 , the bending strength can be equalized on both sides of the center line CL of the impact absorbing member 101, allowing for precise control of the bending direction with the top surface of the top wall 111 on the inside of the bending. While the number of angle irons 255 is one pair (two) in both the first section 100R1 and the third section 100R3, two or more pairs may be used. Furthermore, when multiple angle irons 255 are used, their thicknesses and lengths may differ. However, when multiple angle irons 255 are used, it is preferable to arrange them symmetrically across the center line CL. On the other hand, no angle iron 255 is fixed to the second section 100R2 of the horizontal plate 142, leaving it flat. Therefore, the horizontal plate 142 is reinforced in the first portion 100R1, the second portion 100R2, and the third portion 100R3, except for the second portion 100R2 located in the center. The unreinforced second portion 100R2 of the reinforcement 140 functions as a breakage trigger.

[0165] Figure 34 is a perspective view showing yet another example of the reinforcement 140 provided in the impact absorbing member 101, with the hatched portion indicating the breakage trigger. In the reinforcement 140 of this example, the lower portion of the vertical plate 141 shown in Figure 34 has the same plate thickness at each position in the longitudinal direction. On the other hand, in the upper portion of the vertical plate 141, the plate thickness of at least a part of the second portion 100R2 is thinner than the plate thicknesses of the first portion 100R1 and the third portion 100R3. In other words, in the upper portion of the vertical plate 141, a rectangular region in the second portion 100R2 serves as a breakage trigger where the plate thickness is thinner than the surrounding region. This breakage trigger can be formed, for example, by a tailor welded blank (TWB) in which a plate material having a recess formed in the upper center portion so as to form a substantially U-shape in a side view and a plate material to be joined within this recess and having a thickness thinner than the other plate material are prepared, and these are then joined by welding to form a single vertical plate 141. Alternatively, the vertical plate 141 having the breakage starting point 100BP can also be formed by a tailor rolled blank (TRB).

[0166] In the configuration shown in FIG. 34 , the width dimension Wr1 of the folding trigger is equal to the height dimension of the upper portion of the vertical plate 141. That is, the entire width dimension Wr2 of the vertical plate 141 between the widthwise center position, where the center line CL of the reinforcement 140 passes, and the upper edge position, where the vertical plate 141 is connected to the top wall portion 111, is a folding trigger with a thin plate thickness. However, this is not limited to this configuration. As shown in FIG. 35 , the folding trigger may be formed at a hatched position that is 1 / 3 of the width of the upper portion of the vertical plate 141 and includes the upper edge of the vertical plate 141. More specifically, the width dimension Wr1 and the width dimension Wr2 may satisfy Wr2≧Wr1>(1 / 3)×Wr2. In both the cases shown in FIG. 34 and FIG. 35 , it is preferable to include the upper edge portion of the vertical plate 141 so that the folding trigger divides the upper edge portion of the vertical plate 141 at the position of the second portion 100R2.

[0167] FIG. 36 is a perspective view showing yet another example of the reinforcement 140 provided in the impact absorbing member 101. As in this example, the folding triggers may be formed on the horizontal plate 142 instead of the vertical plate 141. In this case, as indicated by hatching, the folding triggers are preferably formed at the longitudinal center of the horizontal plate 142, one on each of the left and right portions of the horizontal plate 142, sandwiching the vertical plate 141 between them. Furthermore, the folding triggers on the left and right portions preferably have the same shape and size (same width, length, and thickness). This allows the bending strengths on the left and right sides of the center line CL of the impact absorbing member 101 to be equal, thereby enabling precise control of the bending direction with the top surface of the top wall portion 111 on the inside of the bending. In this example, two folding triggers are formed on the horizontal plate 142, but the total number may be an even number of two or more. In this case, it is also preferable that the folding triggers on the left and right portions be the same size and number. Furthermore, both the vertical plate 141 and the horizontal plate 142 may be formed with folding triggers as described above.

[0168] In the configuration shown in FIG. 36 , the width dimension Wr1 of the folding trigger is set equal to the width dimension of the left or right portion of the horizontal plate 142. That is, the entire width dimension Wr2 of the horizontal plate 142 between the widthwise center position, where the center line CL of the reinforcement 140 passes, and the side edge position, where the horizontal plate 142 is connected to the left side wall portion 112a or the right side wall portion 112b, is set to be a folding trigger with a thin plate thickness. However, this is not the only possible configuration. For example, as shown in the hatched portion of FIG. 37 , the folding trigger may be formed at a position that is 1 / 3 of the width of the left or right portion of the horizontal plate 142 and that includes the side edge of the horizontal plate 142. More specifically, the width dimension Wr1 (mm) and the width dimension Wr2 (mm) may satisfy the relationship Wr2≧Wr1>(1 / 3)×Wr2. In both cases of Figures 36 and 37, it is preferable to include both side edge portions of the horizontal plate 142 so that each folding trigger is positioned so that it divides both side edge portions of the horizontal plate 142 at the position of the second portion 100R2.

[0169] 34 or 35 and the configuration of Fig. 36 or 37 described above may be combined. That is, a folding trigger may be formed at the position of the second portion 100R2 for both the vertical plate 141 and the horizontal plate 142. In this case, the width dimension Wr1 of the folding trigger formed on the vertical plate 141 may be equal to the width dimension Wr1 of the folding trigger formed on the horizontal plate 142, or may be different from each other.

[0170] In the above example, the breakage trigger is formed by reducing the plate thickness. However, instead, the breakage trigger may be formed by partially reducing the tensile strength. That is, the plate thickness t2 of the second portion 100R2 (the total plate thickness if there are multiple vertical plates 141) and the average plate thickness ta3, which is the average of the plate thickness t3 of the first portion 100R1 (the total plate thickness if there are multiple vertical plates 141) and the plate thickness t3 of the third portion 100R3 (the total plate thickness if there are multiple vertical plates 141), may be equal to each other. In addition, the tensile strength E1 (MPa) of the second portion 100R2 may be lower than the average tensile strength Ea2 (MPa), which is the average of the tensile strengths of the first portion 100R1 and the third portion 100R3. Such a difference in tensile strength can be obtained by manufacturing a separate part made of a material with a relatively low tensile strength and joining this separate part by TWB as the second portion 100R2 of the vertical plate 141 or the horizontal plate 142. Furthermore, a bending trigger with a relatively low tensile strength may be provided in both the vertical plate 141 and the horizontal plate 142 in the second portion 100R2.

[0171] 22 to 37 described above show examples of reinforcements whose cross-sectional shape perpendicular to the longitudinal direction resembles the letter "+", but reinforcements having shapes shown in Case 001, Case 002, and Case 004 in Fig. 43 described below may also be used. For example, the reinforcement shown in Case 004 has a cross-sectional shape in which a single vertical plate 141 half the height is joined between the center position in the width direction of a single horizontal plate 142 and the top wall portion 111. These vertical plate 141 and horizontal plate 142 have folding triggers at the position of the second portion 100R2 shown in Fig. 23.

[0172] 38 to 40 are diagrams showing yet another example of the reinforcement 140 provided in the impact absorbing member 101. In this example, the reinforcement 140 is provided only in the second section 100R2, and a filler 256 is provided in each of the first section 100R1 and the third section 100R3. As shown in FIGS. 38 and 40 , the filler 256 fills the internal space of the first section 100R1 without any gaps. Similarly, another filler 256 fills the internal space of the third section 100R3 without any gaps. Therefore, the pair of fillers 256 are arranged with the reinforcement 140 sandwiched between them. In other words, one of the pair of fillers 256, the reinforcement 140, and the other of the pair of fillers 256 are fixedly arranged in this order along the longitudinal direction of the hollow tube 130. Therefore, in the hollow tube 130, only the filler 256 is provided inside the first portion 100R1 and the third portion 100R3, and only the reinforcement 140 is provided inside the second portion 100R2.

[0173] The filler 256 is a resin material, and specific examples of the material include epoxy and urethane. Because the filler 256 is a resin material, its shape can be adapted to the internal shape of the hollow tube 130. That is, the filler 256 can be adapted to the shape of the space defined by the top wall 111, the pair of side walls 112, and the plate-like member 120. Therefore, the filler 256 can be flexibly arranged according to the internal shape of the hollow tube. In the present example, the hollow tube 130 has a trapezoidal cross section perpendicular to its length, and therefore the filler 256 also has a trapezoidal cross section. While it is most preferable for each filler 256 to fill the entire internal space of the first portion 100R1 and the entire internal space of the third portion 100R3, as in this example, it is sufficient that the filler 256 fills at least the upper internal space, including the inner surface (lower surface) of the top wall 111; the lower space does not have to be filled with each filler 256. A specific example will be given in the description of FIGS. 41 and 42 below.

[0174] In this way, by reinforcing the upper internal space, including at least the inner surface (lower surface) of the top wall portion 111, with the filler 256, out-of-plane deformation of the first portion 100R1 and the third portion 100R3, particularly the top wall portion 111, is suppressed. Because the bending origin 100BP of the hollow tube 130 is located on the outer surface of the top wall portion 111, reinforcing only the first portion 100R1 and the third portion 100R3 with the filler 256 while not reinforcing the second portion 100R2 with the filler 256 effectively creates a relative strength difference against bending deformation. Therefore, the hollow tube 130 can be bent smoothly at the position of the second portion 100R2. Alternatively, a pair of preformed fillers 256 may be prepared and inserted, one into the first portion 100R1 and one into the third portion 100R3, and then adhesively fixed thereto. Alternatively, the filler 256 may be formed by filling each of the first portion 100R1 and the third portion 100R3 with a resin material in a fluid state and then hardening it.

[0175] In this example, the reinforcement 140 is sandwiched between the pair of fillers 256 described above, thereby setting the folding trigger at the second portion 100R2 where the reinforcement 140 is located. The impact absorbing member 101 is set so that the upper surface of the top wall portion 111 is on the inner side of the bending at the second portion 100R2, which is the center position in the longitudinal direction of the impact absorbing member 101. This setting is mainly determined by the manner in which the impact absorbing member 101 is arranged within the vehicle. The manner in which the impact absorbing member 101 is arranged within the vehicle can be achieved by shifting the point of application of the impact load closer to the top wall portion 111 than the center line CL.

[0176] As a configuration in which the filler 256 is used in combination with the reinforcement 140, for example, a modified example shown in Figures 41 and 42 can be adopted instead of the configuration described above. In this modified example, the configurations of the reinforcement 140 and the filler 256 are particularly different from those in the above example, so the differences will be mainly described below, and other configurations are similar, so description thereof will be omitted.

[0177] The reinforcement 140 of this modified example does not include the vertical plate 141 and is composed of only one horizontal plate 142. Furthermore, this horizontal plate 142 has a length that extends not only into the second region 100R2 but also into the first region 100R1 and the third region 100R3. In addition, flanges are formed on both side edges of the horizontal plate 142, one of which is fixed to the inner surface of the left side wall portion 112a by welding, and the other is fixed to the inner surface of the right side wall portion 112b by welding. The horizontal plate 142 is disposed at the same height as the center line CL of the hollow tube 130 and is coaxial with the center line CL. With this configuration, the horizontal plate 142 restricts the spacing between the pair of side wall portions 112. This restriction prevents the top wall portion 111 from sinking in and widening the gap between the pair of side wall portions 112, thereby indirectly supporting the top wall portion 111. Therefore, in this case as well, the second portion 100R2 of the hollow tube 130 is supported by the reinforcement 140 from the inside thereof.

[0178] Furthermore, in this modification, although the filler 256 is disposed in the first portion 100R1 and the third portion 100R3, when viewed in a cross section perpendicular to the longitudinal direction of the hollow tube 130 ( FIG. 42 ), it is disposed only above the horizontal plate 142. That is, in each of the first portion 100R1 and the third portion 100R3, the filler 256 is disposed within a closed space defined by the top wall 111, the pair of side walls 112, and the horizontal plate 142. On the other hand, in the second portion 100R2, the filler 256 is not disposed within the closed space defined by the pair of side walls 112, the horizontal plate 142, and the plate-like member 120, leaving an empty space. This configuration also makes it possible to suppress out-of-plane deformation of the top wall 111, particularly in the first portion 100R1 and the third portion 100R3. The degree of reinforcement against bending deformation of the impact absorbing member 101 is set to be relatively higher in the first portion 100R1 and the third portion 100R3 than in the second portion 100R2 depending on the presence or absence of the filler 256. Therefore, bending deformation can be smoothly performed starting from the outer surface of the top wall portion 111 of the second portion 100R2.

[0179] The above-described embodiment and its modified examples may be modified in various ways without departing from the spirit and scope of the present invention. For example, while the left reinforcing portion 240a and the right reinforcing portion 240b are configured using strip-shaped plate material, this configuration is not limited thereto. The reinforcing portion 240 may be configured to partially reinforce the same position and shape range as the left reinforcing portion 240a and the right reinforcing portion 240b. Examples of such reinforcement methods include patchwork, tailored weld blanks, beads, and heat treatment. Furthermore, the configurations described using Figures 28 to 42 may be used individually or in combination. For example, the through-holes 251, 252, beads 253, 254, and angle irons 255 may be combined as long as they do not interfere with each other in terms of their placement.

[0180] The gist of the impact absorbing member 101 of the second embodiment described above will be summarized below. (1) As shown in Figure 23 etc., one aspect of the present invention is an impact absorbing member 101 including a hollow tube 130 that is long along one direction and a reinforcement 140 fixedly disposed inside the hollow tube 130, wherein the hollow tube 130 has, as seen in a cross section perpendicular to the longitudinal direction, which is the one direction, a top wall portion (bending inner wall portion) 111 and a pair of side wall portions 112 that are continuous with the top wall portion 111 via a pair of ridge portions 100EL. The hollow tube 130 has a vertical plate 141 with one end joined, at least one of horizontal plates 142 connecting a pair of side wall portions 112, and a folding trigger configured to set a folding starting point 100BP in the top wall portion 111 of the hollow tube 130 at a midpoint in the longitudinal direction; and the hollow tube 130 has a pair of reinforcing portions 240 on each of the side wall portions 112, extending along the extension direction of each ridge portion 100EL and fixedly positioned adjacent to each ridge portion 100EL.

[0181] (2) As shown in Figure 23 etc., in the impact absorbing member 101 described in (1) above, each reinforcing portion 240 may be a strip-shaped plate material that is long along the extension direction and is joined to at least each outer surface of each side wall portion 112. (3) As shown in Figure 23, in the impact absorbing member 101 described in (1) or (2) above, the average length L along the extension direction of each reinforcing portion 240 may be two or more times the buckling range length LB of each side wall portion 112 at the position of the folding start point 100BP.

[0182] (4) As shown in Figure 24A, in the impact absorbing member 101 described in any one of (1) to (3) above, each of the reinforcing portions 240 may be provided only on each of the side wall portions 112 when viewed in a cross section perpendicular to the longitudinal direction. (5) As shown in Figure 23, the impact absorbing member 101 described in (4) above may employ the following configuration: a hollow tube 130 includes a hat-shaped member 110 having a top wall portion 111 that is a bending inner wall portion and side wall portions 112 that are connected to both sides of the top wall portion 111 via each ridge portion 100EL, and a plate-like member 120 that is joined to the hat-shaped member 110 to form a closed cross section; The height dimension H is 50 mm to 200 mm, the width dimension W of the top wall portion 111 is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member 110 is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-shaped member 120 is 0.8 mm to 3.2 mm; the length L of each reinforcing portion 240 along the extension direction is 70 mm to 500 mm, and the width dimension w in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm.

[0183] (6) As shown in Figure 24B, in the impact absorbing member 101 described in any one of (1) to (3) above, each reinforcing portion 240 may be provided only in an area overlapping each side wall portion 112 and each ridge portion 100EL when viewed in a cross section perpendicular to the longitudinal direction. (7) As shown in Figure 23, the impact absorbing member 101 described in (6) above may employ the following configuration: a hollow tube 130 includes a hat-shaped member 110 having a top wall portion 111 that is a bending inner wall portion and side wall portions 112 that are connected to both sides of the top wall portion 111 via each ridge portion 100EL, and a plate-like member 120 that is joined to the hat-shaped member 110 to form a closed cross section; The width dimension W of the top wall portion 111 is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member 110 is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-like member 120 is 0.8 mm to 3.2 mm; the length L of each reinforcing portion 240 along the extension direction is 70 mm to 500 mm, and the width dimension w of the portion overlapping each side wall portion 112 when viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm.

[0184] (8) As shown in Figures 28 to 33, the impact absorbing member 101 described in any one of (1) to (7) above may have the following configuration: the reinforcement 140 has a first portion 100R1, a second portion 100R2, and a third portion 100R3 arranged in order along the longitudinal direction; and the bending trigger has at least one of a through portion 251 provided in the second portion 100R2 or a bead 253 formed long in a direction intersecting the longitudinal direction, and a bead 254 arranged in each of the first portion 100R1 and the third portion 100R3 and long in the longitudinal direction.

[0185] (9) As shown in Figures 34 to 37, the impact absorbing member 101 described in any one of (1) to (7) above may have the following configuration: the reinforcement 140 has a first portion 100R1, a second portion 100R2, and a third portion 100R3 arranged in order along the longitudinal direction; and the bending trigger is formed in the second portion 100R2 of the reinforcement 140, including the connection position with the hollow tube 130, and has at least one of a thickness thinner than both the first portion 100R1 and the third portion 100R3, and a tensile strength lower than both the first portion 100R1 and the third portion 100R3.

[0186] (10) As shown in Figures 38 to 41, the impact absorbing member 101 described in any one of (1) to (7) above may have the following configuration: a hollow tube 130 has a first portion 100R1, a second portion 100R2, and a third portion 100R3 arranged in this order along the longitudinal direction; and has, as the folding trigger, a reinforcement 140 arranged at least in the second portion 100R2, and a filler 256 arranged inside the first portion 100R1 and inside the third portion 100R3. [Example]

[0187] An example corresponding to the second embodiment will be described below using Figures 43 to 46. In this example, the maximum load and energy absorption amount when collision energy is applied to multiple impact absorbing members with different reinforcement conditions are calculated.

[0188] That is, first, six types of impact absorbing members having various cross-sectional shapes shown in FIG. 43 were prepared. FIG. 43 is a cross-sectional view of the impact absorbing member taken along line F-F in FIG. 23. Of these, Case 000 shows a comparative example consisting only of a hollow tube 130 without a reinforcement 140 or a reinforcing portion 240. Case 005 also shows a comparative example that does not include a reinforcement 140 or a reinforcing portion 240 and has a different reinforcement method. Case 001 shows an example of the invention in which only one horizontal plate 142 is included as the reinforcement 140. This horizontal plate 142 has a folding trigger at the position of the second portion 100R2 shown in FIG. 23. Case 002 shows an example of the invention in which only one vertical plate 141 is included as the reinforcement 140. This vertical plate 141 has a folding trigger at the position of the second portion 100R2 shown in FIG. 23. Case 003 is an example of the invention in which one horizontal plate 142 and one vertical plate 141 are crossed in a "+" shape as the reinforcement 140, and is the same as the configuration illustrated in FIG. 23 . These vertical plate 141 and horizontal plate 142 have folding triggers at the second portion 100R2 shown in FIG. 23 . Case 004 is an example of the invention in which one vertical plate 141 with a height half the height of one horizontal plate 142 is joined between the center of the width direction of the horizontal plate 142 and the top wall portion 111. These vertical plate 141 and horizontal plate 142 have folding triggers at the second portion 100R2 shown in FIG. 23 . Case 005 is a comparative example in which a U-shaped reinforcing member 10A whose cross section is similar to that of the hat-shaped member 110 is joined to the inner circumferential surface of the hat-shaped member 110.

[0189] For each of the impact absorbing members shown in Cases 000 to 005 above, both ends were held rotatably around horizontal axes as shown in FIG. 44(a), and a forced displacement was applied to the impact absorbing member at a constant speed of 1 mm / s along a direction parallel to its longitudinal direction, and the displacement of the load F applied at that time was measured. The impact energy was applied after the center line of the impact absorbing member was offset in the height direction from the input position of the impact energy. More specifically, the load F was applied horizontally at a position shifted by 23 mm in a direction closer to the top wall portion 111 than the center line of the impact absorbing member. This caused the impact absorbing member to bend from the state shown in FIG. 44(a), which shows the pre-bending deformation, to the state shown in FIG. 44(b), which shows the post-bending deformation, with the top wall portion 111 as the bending origin.

[0190] The results of the maximum load for each case are shown in Table 5 below and Figure 45. In Figure 45, the horizontal axis indicates each case number, and the vertical axis indicates the maximum load (kN). Similarly, the results of the energy absorption for each case are shown in Table 5 below and Figure 46. In Figure 46, the horizontal axis indicates each case number, and the vertical axis indicates the energy absorption (kJ).

[0191]

[0192] As shown in Figure 46, Cases 001 to 004, which belong to the invention examples, all achieved higher energy absorption than Case 000, which had no reinforcement. The same was true for Case 005, a comparative example, but as shown in Table 5, it was significantly heavier than Case 000. On the other hand, Cases 001 to 004, which belong to the invention examples, all showed a slight increase in weight compared to Case 000. Therefore, for Cases 001 to 004, which belong to the invention examples, it is possible to reduce the overall weight of the part by thinning the plate thickness until it achieves the same energy absorption as Case 000 or shortening the deformation stroke. Therefore, it was confirmed that the configuration of the invention examples can exhibit high energy absorption efficiency by bending and deforming at smooth joints despite its light weight.

[0193] The impact absorbing members according to the above aspects of the present invention can suppress sudden load fluctuations and achieve a high amount of collision energy absorption with a short deformation stroke, and therefore have great industrial applicability.

[0194] 1 Impact absorbing member 10 Hat-shaped member 11 Top wall portion, hat top portion 12 Side wall portion 20 Plate-shaped member (opposing wall portion) 30 Hollow tube 40 Reinforcement portion 50 Filler 101 Impact absorbing member 110 Hat-shaped member 111 Top wall portion (bent inner wall portion) 112 Side wall portion 120 Plate-shaped member 130 Hollow tube 140 Reinforcement 141 Vertical plate 142 Horizontal plate 200EL Ridge line portion 200R1 First portion 200R2 Second portion 200R3 Third portion 240 Reinforcement portion 253 Bead 254 Bead (rigid portion) 255 Angle member (rigid portion) 256 Filler Ba Left bead (first bead) Bb Right bead (first bead) Bc Horizontally elongated bead (second bead) Bd, Be, Bf, Bg Vertically elongated bead (third bead) BP Folding start point EL Ridge line ELx Other ridge line L Length of reinforcement part LB Buckling range length Ta Through hole

Claims

1. An impact absorbing component having a hollow tube that is long along one direction, the hollow tube having, when viewed in a cross section perpendicular to the longitudinal direction, a bent inner wall portion and a pair of side wall portions connected to the bent inner wall portion via a pair of ridge portions, the impact absorbing component comprising: a folding trigger provided on the hollow tube and configured to set a folding start portion on the bent inner wall portion at a midway position in the longitudinal direction of the hollow tube; and a pair of reinforcing portions extending in the extension direction of the ridge portions and provided at positions adjacent to each of the ridge portions on the outer surfaces of each of the side wall portions when the hollow tube is viewed in a cross section perpendicular to the longitudinal direction at the position of the folding start portion.

2. An impact absorbing component comprising a hollow tube that is long along one direction and a reinforcement fixedly disposed inside the hollow tube, wherein the hollow tube has, when viewed in a cross section perpendicular to the longitudinal direction, a bent inner wall portion and a pair of side wall portions connected to the bent inner wall portion via a pair of ridge lines, wherein the reinforcement has at least one of a vertical plate having one end joined to the bent inner wall portion and a horizontal plate connecting the pair of side wall portions, and a folding trigger configured to set a folding start portion on the bent inner wall portion of the hollow tube at a midpoint in the longitudinal direction; and wherein the hollow tube has a pair of reinforcing portions on each of the side wall portions, extending along the extension direction of each of the ridge lines and fixedly disposed adjacent to each of the ridge lines.

3. The impact absorbing member according to claim 1 or 2, characterized in that each of the reinforcing parts is joined to at least each of the outer surfaces of each of the side wall parts and is a long strip-shaped plate material extending along the extension direction.

4. The impact absorbing member according to claim 1 or 2, characterized in that the average length of each of the reinforcing parts along the extension direction is at least twice the buckling range length of each of the side wall parts at the position of the folding start point.

5. The impact absorbing member according to claim 1 or 2, characterized in that each of the reinforcing parts is provided only on each of the side wall parts when viewed in a cross section perpendicular to the longitudinal direction.

6. The impact absorbing component according to claim 4, wherein the hollow tube comprises: a hat-shaped member having a top wall portion which is the bent inner wall portion, and each of the side wall portions which are connected to both sides of the top wall portion via each of the ridge portions; and a plate-like member which is joined to the hat-shaped member to form a closed cross section; the height dimension H between the top wall portion and the plate-like member is 50 mm to 200 mm, the width dimension W of the top wall portion is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-like member is 0.8 mm to 3.2 mm; and the length L of each of the reinforcing portions in the extension direction is 70 mm to 500 mm, and the width dimension w in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm.

7. The impact absorbing member according to claim 1 or 2, characterized in that each of the reinforcing portions is provided only in the range from each of the side wall portions to each of the ridge portions when viewed in a cross section perpendicular to the longitudinal direction.

8. The impact absorbing component according to claim 7, wherein the hollow tube comprises: a hat-shaped member having a top wall portion which is the bent inner wall portion, and each of the side wall portions which are connected to both sides of the top wall portion via each of the ridge portions; and a plate-like member which is joined to the hat-shaped member to form a closed cross section; the height dimension H between the top wall portion and the plate-like member is 50 mm to 200 mm, the width dimension W of the top wall portion is 30 mm to 100 mm, the plate thickness T1 of the hat-shaped member is 0.8 mm to 3.2 mm, and the plate thickness T2 of the plate-like member is 0.8 mm to 3.2 mm; the length L of each of the reinforcing portions along the extending direction is 70 mm to 500 mm, and the width dimension w of the portions which overlap each of the side wall portions when viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm.

9. The shock absorbing member according to claim 1, characterized in that the bending trigger includes a first bead provided on the pair of ridges of the hollow tube and at the position of the bending starting point.

10. The shock absorbing member according to claim 1, characterized in that the folding trigger includes a second bead provided at the position of the folding start point of the bent inner wall portion and extending in a direction intersecting the longitudinal direction.

11. The shock absorbing member according to claim 1, characterized in that the folding trigger includes a through hole provided at the position of the folding starting point of the bent inner wall portion.

12. The impact absorbing member according to claim 1, characterized in that, when the hollow tube is viewed along the longitudinal direction, a portion including the break origin is defined as a second portion, one side of the second portion is defined as a first portion, and the other side of the second portion is defined as a third portion, the break origin is provided at each of the first portion and the third portion and includes a third bead that is long along the longitudinal direction.

13. The impact absorbing member according to claim 1, characterized in that, when the hollow tube is viewed along the longitudinal direction, a portion including the break origin is defined as a second portion, one side of the second portion is defined as a first portion, and the other side of the second portion is defined as a third portion, the break trigger includes at least one of a plate thickness difference and a material strength difference provided between the second portion and the first portion and between the second portion and the first portion and the third portion.

14. The impact absorbing member according to claim 1, characterized in that the bending trigger includes a bending shape of the hollow tube in which the outer surface of the bent inner wall portion is concave at the position of the bending trigger portion.

15. The impact absorbing member according to claim 1, characterized in that, when the hollow tube is viewed along the longitudinal direction, a portion including the break origin is defined as a second portion, one side of the second portion is defined as a first portion, and the other side of the second portion is defined as a third portion, the break origin includes a filler material filled in each of the first portion and the third portion excluding the second portion.

16. The impact absorbing member according to claim 1, characterized in that the hollow tube has an opposing wall portion disposed opposite the bent inner wall portion and connected to the pair of side wall portions via a pair of other ridge portions; further comprising: another folding trigger provided on the hollow tube and configured to set another folding point portion on the opposing wall portion at another intermediate position in the longitudinal direction of the hollow tube; and a pair of other reinforcing portions extending along the extension direction of each of the other ridge portions and provided at positions adjacent to each of the other ridge portions on each outer surface of each of the side wall portions when the hollow tube is viewed in a cross section perpendicular to the longitudinal direction at the position of each of the other folding point portions.

17. The impact absorbing member according to claim 2, characterized in that the reinforcement has a first portion, a second portion, and a third portion aligned in sequence along the longitudinal direction; and the folding trigger has at least one of: a through-hole provided in the second portion or a bead formed long in a direction intersecting the longitudinal direction, and a rigid portion disposed in each of the first portion and the third portion and long in the longitudinal direction.

18. The impact absorbing member according to claim 2, characterized in that the reinforcement has a first portion, a second portion, and a third portion aligned in sequence along the longitudinal direction; the bending trigger is formed in the second portion of the reinforcement including a connection position with the hollow tube; the impact absorbing member has at least one of: a plate thickness thinner than both of the first portion and the third portion; and a tensile strength lower than both of the first portion and the third portion.

19. The impact absorbing member according to claim 2, characterized in that the hollow tube has a first portion, a second portion, and a third portion aligned in sequence along the longitudinal direction; and the folding trigger has: the reinforcement disposed in at least the second portion; and a filler disposed inside the first portion and inside the third portion.

Images