Shock absorbing material

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

Technical Field

[0001] The present invention relates to a shock-absorbing member. This application claims priority based on Japanese Patent Application No. 2023-179418 filed in Japan on October 18, 2023, and Japanese Patent Application No. 2023-179462 filed in Japan on October 18, 2023, and incorporates the contents thereof herein.

Background Art

[0002] In recent years, fuel consumption regulations have been tightened worldwide, and automobile manufacturers are promoting the weight reduction of vehicle bodies. At the same time, the collision safety of vehicle bodies has also been tightened, so a balance between weight reduction and improvement of collision performance is required. In addition, along with the trend of fuel consumption regulations and carbon neutrality in each country, the electrification of the power source of automobiles is being promoted. Along with the electrification of the power source, changes have also occurred in the vehicle body structure, such as an increase in vehicle body weight and a reduction in the engine room compared to the vehicle body structure having a conventional internal combustion engine. As an example, there is the shortening of the short nose at the front of the vehicle body. In order to maintain high collision safety while shortening the short nose of the vehicle body, a structure that can obtain high energy absorption efficiency with a small deformation stroke is required.

[0003] In particular, for components such as front side members and rear side members that actively plastically deform during vehicle collisions to absorb collision energy, a structure that can dramatically improve energy absorption performance is required. In addition, since such components also play a role in minimizing the external force applied to the occupants during a collision, a deformation mode that can suppress rapid load fluctuations and shorten the deformation stroke is ideal.

[0004] As deformation modes of members for absorbing collision energy, there are bellows deformation and serpentine deformation (bending deformation). Bellows deformation refers to deformation in which out-of-plane deformation occurs on all of the respective side surfaces constituting the member, but the center line in the longitudinal direction of the member hardly bends. On the other hand, meandering deformation is a type of deformation in which bending occurs at multiple points along the longitudinal direction of a member, with out-of-plane deformation mainly occurring on one of the sides constituting the member, and the centerline along the longitudinal direction of the member also bending. Comparing the two deformation modes described above, if the impact force is applied from an ideal direction, bellows deformation can be said to absorb more impact energy than meandering deformation. However, the direction of impact force input is not fixed to only one direction, so for example, if the impact force is applied obliquely to the longitudinal direction of the member, the amount of energy absorbed by bellows deformation decreases significantly. In contrast, meandering deformation (folding deformation) can respond to the direction of impact force application to a certain extent, and therefore can absorb impact energy stably.

[0005] Examples of structures that absorb collision energy include those disclosed in the following Patent Documents 1 and 2. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-276031 [Patent Document 2] International Publication No. 2018 / 190312 [Overview of the project] [Problems that the invention aims to solve]

[0007] Patent Document 1 discloses a bent-formed member obtained by bending a metal plate, wherein the bent-formed member is provided with a build-up weld in the ridge of at least one bent portion and / or the area near this ridge, in order to increase both the plate thickness and strength of this area and increase the amount of impact energy absorbed. Here, "the area near the ridge" is explained as "an example being a range of 20 mm or less in a direction perpendicular to the direction in which the ridge is formed. This is because when the press-bent-formed member collapses due to impact stress caused by a collision, the highest impact stress acts in this area, and therefore it is necessary to increase the amount of impact energy absorbed in this part."

[0008] On the other hand, Patent Document 2 discloses a structural member for an automobile, comprising a press-formed product made from a single steel plate and a reinforcing member fixed to the press-formed product, wherein the press-formed product comprises two vertical wall portions and a top plate portion connecting the two vertical wall portions, and the reinforcing member is an L-shaped member with a cross-section comprising a first plate-like portion and a second plate-like portion, and the first plate-like portion is fixed to the vertical wall portion such that the second plate-like portion protrudes outward from the vertical wall portion side along the top plate portion. It is explained that this structural member for an automobile allows for "a structural member with high characteristics in a three-point bending test to be obtained."

[0009] As is clear from the description in Patent Document 1 above, the bent-formed member absorbs collision energy through bellows deformation, which is caused by the impact stress resulting from the collision. As mentioned above, while bellows deformation absorbs a large amount of energy for collision energy from an ideal direction, the amount of energy absorbed decreases significantly for collision energy from other directions. Furthermore, the structural member for automobiles described in Patent Document 2 above absorbs collision energy by bending and deforming when subjected to an external force from the side, as is evident from the description that it is a "structural member with high performance in three-point bending tests."

[0010] As mentioned above, impact absorbing members are increasingly required to not only suppress rapid load fluctuations but also to shorten the deformation stroke. Therefore, it is desirable to be able to reliably obtain a high amount of impact energy absorption with a shorter deformation stroke than the bending-formed member described in Patent Document 1, which is based on bellows deformation. Furthermore, Patent Document 2 deals with components such as side sills. Therefore, it is difficult to absorb large collision energies, such as those received by front side members or rear side members, through three-point bending deformation.

[0011] This invention has been made in view of the above circumstances, and aims to provide an impact absorbing member that can achieve a high amount of collision energy absorption with a short deformation stroke while suppressing rapid load fluctuations. [Means for solving the problem]

[0012] To solve the aforementioned problems, the present invention employs the following means. (1a) One aspect of the present invention is an impact absorbing member having a hollow tube that is long in one direction, and the hollow tube, when viewed in a cross section perpendicular to the longitudinal direction which is the one direction, has 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 member comprising: a bending starter provided on the hollow tube and configured to set a bending start point on the bent inner wall portion at an intermediate position in the longitudinal direction of the hollow tube; and a pair of reinforcing portions provided along the extending direction of each of the ridge portions and 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 bending start point. More specifically, the pair of reinforcing parts are provided in contact with each of the ridges and in positions excluding the top wall, and extend along the direction of extension of each of the ridges.

[0013] When the impact absorbing member described in (1a) above receives impact energy along its longitudinal direction, it deforms by bending at the position of the bending initiation point, with the outer surface of the inner bending wall facing inward. Each reinforcing section that absorbs impact energy during this bending deformation is positioned adjacent to each ridge and extending along the direction of extension of each ridge. These reinforcing sections can suppress the increase in the maximum load of the impact-absorbing member more effectively than reinforcing the inner wall itself. On the other hand, most of the impact energy is absorbed by each side wall buckling into an "L" shape at the bending initiation point, but the reinforced sections make it more difficult for each side wall to bend into an "L" shape. Therefore, the drop in load after the maximum load occurs in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram) can be made more gradual. As a result, the load integral value after the maximum load occurs in the FS diagram can be increased, thus increasing the amount of energy absorbed.

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

[0015] (3a) The impact absorbing member described in (1a) or (2a) above may have an average length along the extending direction of each of the reinforcing portions that is twice or more the buckling range length of each of the side walls at the position of the bending initiation 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 that has bent into an "L" shape due to buckling deformation gradually closes. Here, since the length of each reinforcing part is more than twice the length of the buckling range, when the buckling deformation progresses and the "L" shape is completely closed, the pair of ridge sections connected with the buckling range of this "L" shape in between can be reliably brought into contact with each other. This contact between the ridge sections causes the rise of the secondary peak load. Here, since each side wall is reinforced in advance by the reinforcing part, the buckling range is localized (the part that buckles into an "L" shape is smaller than in the case without the reinforcing part). Therefore, in the case of small buckling deformation, the contact between the pair of ridge sections begins earlier than in the case of large buckling deformation, so the rise of the secondary peak load is accelerated. Furthermore, since each side wall is reinforced by a reinforcement section, pairs of ridge sections continue to abut strongly against each other. 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 delayed, which increases the load integral value. Thus, energy absorption can be increased.

[0016] (4a) The impact absorbing member described in (1a) or (2a) above 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 reinforcement is applied except for the inner wall portion and the ridge portion of the bend, the amount of energy absorbed can be increased without significantly increasing the maximum load (primary peak load). Therefore, rapid load fluctuations can be suppressed most effectively.

[0017] (5a) The shock absorption member described in (4a) above may adopt the following configuration: the hollow tube includes a hat-shaped member having a top wall portion that is the bending inner wall portion and side wall portions that are connected to both sides of the top wall portion via the respective ridge lines, 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, 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 extending direction is 70 mm to 500 mm and the width dimension w of the portion overlapping the side wall portions in a cross-section perpendicular to the longitudinal direction is 10 mm to 60 mm. According to the shock absorption member described in (5a) above, the effects described in (1a) above can be obtained more reliably.

[0018] (6a) In the shock absorption member described in (1a) or (2a) above, each of the reinforcing portions may be provided only in a range overlapping from the side wall portions to the ridge lines in a cross-section perpendicular to the longitudinal direction. According to the shock absorption member described in (6a) above, since the bending inner wall portion is excluded from reinforcement, the excessive increase in the maximum load (primary peak load) can be suppressed and the energy absorption amount can be increased. Therefore, rapid load fluctuations can be reliably suppressed.

[0019] (7a) The shock absorption member described in (6a) above may adopt the following configuration: the hollow tube includes a hat-shaped member having a top wall portion that is the bending inner wall portion and side wall portions that are connected to both sides of the top wall portion via the respective ridge lines, 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, 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 extending direction is 70 mm to 500 mm and the width dimension w of the portion overlapping the side wall portions in a cross-section perpendicular to the longitudinal direction is 10 mm to 60 mm. According to the shock absorption member described in the above (7a), the effects described in the above (1a) can be obtained more reliably.

[0020] (8a) In the shock absorption member described in the above (1a) or (2a), the break trigger may include a first bead provided on the pair of ridge lines of the hollow tube and at the position of the break starting portion. According to the shock absorption member described in the above (8a), when receiving collision energy along its longitudinal direction, with the position of the first bead as the break starting portion, the bending inner wall portion is bent and deformed.

[0021] (9a) In the shock absorption member described in the above (1a) or (2a), the break trigger may include a second bead provided at the position of the break starting portion of the bending inner wall portion and long in a direction intersecting the longitudinal direction. According to the shock absorption member described in the above (9a), when receiving collision energy along its longitudinal direction, with the position of the second bead as the break starting portion, the bending inner wall portion is bent and deformed.

[0022] (10a) In the shock absorption member described in the above (1a) or (2a), the break trigger may include a through hole provided at the position of the break starting portion of the bending inner wall portion. According to the shock absorption member described in the above (10a), when receiving collision energy along its longitudinal direction, with the position of the through hole as the break starting portion, the bending inner wall portion is bent and deformed.

[0023] (11a) In the shock absorption member described in the above (1a) or (2a), when looking at the hollow tube along the longitudinal direction, taking the portion including the break starting portion as the second portion, one side of the second portion as the first portion, and the other side of the second portion as the third portion, the break trigger may include a third bead provided in each of the first portion and the third portion and long along the longitudinal direction. According to the impact-absorbing member described in (11a) above, the inner wall portion of the bend deforms by bending, with the second portion, which has relatively weaker bending strength than the first portion and the third portion reinforced by the third bead, as the starting point for the break.

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

[0025] (13a) In the impact absorbing member described in (1a) or (2a) above, the bending trigger may include a bend in the hollow tube such that the outer surface of the inner wall portion of the bend is concave at the position of the bending trigger. According to the impact-absorbing member described in (13a) above, the inner wall portion of the bend deforms by bending, with the position of the concave surface as the starting point for the bend.

[0026] (14a) In the impact absorbing member described in (1a) or (2a) above, when the hollow tube is viewed along the longitudinal direction, the portion including the bending point is designated as the second portion, one side of the second portion as the first portion, and the other side of the second portion as the third portion, the bending point may include the filler material filled in the first portion and the third portion, excluding the second portion. According to the impact-absorbing member described in (14) above, the inner wall portion of the bend deforms by bending, with the second portion, which has relatively weaker bending strength than the first and third portions reinforced with filler, serving as the starting point for the break.

[0027] (15a) The impact absorbing member described in (1a) or (2a) above may have the following configuration: the hollow tube has an opposing wall portion that is positioned opposite to the inner wall portion of the bend and is connected to the pair of side wall portions via a pair of other ridge portions; another bending point provided on the hollow tube and configured to set another bending point on the opposing wall portion at another intermediate position in the longitudinal direction of the hollow tube; and a pair of other reinforcing portions that extend along the extending direction of each of the other ridge portions and are provided on the outer surface of each of the side wall portions adjacent to each of the other ridge portions when the hollow tube is viewed in a cross section perpendicular to the longitudinal direction at the position of the other bending point. According to the impact absorbing member described in (15a) above, the bending initiation point and other bending initiation points are arranged on the opposing inner bending wall and opposing wall, and are spaced apart from each other in a line of sight along the longitudinal direction. When this impact absorbing member receives collision energy along its longitudinal direction, at the position of the bending initiation point, the outer surface of the inner bending wall becomes the inner bending surface, and at the position of the other bending initiation point, the outer surface of the opposing wall becomes the inner bending surface. As a result, the impact absorbing member deforms into a Z shape. At that time, the reinforcing part and the other reinforcing part share the absorption of collision energy, so a higher amount of collision energy absorption can be obtained.

[0028] (1b) Another aspect of the present invention is an impact absorbing member comprising a hollow tube that is long in one direction and a reinforcement fixedly disposed inside the hollow tube, wherein the hollow tube, when viewed in a cross section perpendicular to the longitudinal direction which is the one direction, has 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, wherein the reinforcement has at least one of a vertical plate joined at one end to the bent inner wall portion and a horizontal plate connecting the pair of side wall portions and a bending starter configured to set a bending start point in the bent inner wall portion of the hollow tube at an intermediate position in the longitudinal direction; and the hollow tube has a pair of reinforcing portions fixedly disposed adjacent to each of the side wall portions, extending along the extending direction of each ridge 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 deform together at the point of initiation of the fold. In other words, in a hollow tube, impact energy is absorbed by the outer surface of the inner wall portion of a bend bending into the inner surface of the bend. Here, each reinforcing portion is positioned adjacent to each ridge and extending along the direction of extension of each ridge portion. These reinforcing portions can suppress the increase in the maximum load of the impact absorbing member more effectively than when the inner wall portion of the bend is reinforced. On the other hand, most of the impact energy absorbed by the deformation of the hollow tube is absorbed by each side wall portion buckling into an "L" shape at the bending initiation point, but due to the reinforcement, each side wall portion is less likely to bend into an "L" shape. Therefore, the drop in load after the occurrence of the 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 the maximum load in the FS diagram can be increased, thus increasing the amount of energy absorbed. In addition, the reinforcement also bends and deforms in accordance with the bending deformation of the hollow tube, which further increases the amount of energy absorbed.

[0030] (2b) The impact absorbing member described in (1b) above may be a long, strip-shaped plate material in which each reinforcing portion is joined to at least the outer surface of each of the side wall portions, and which extends in the direction of extension. According to the impact-absorbing member described in (2b) above, the reinforcement range and degree of reinforcement in a pair of side walls can be easily and accurately adjusted by adjusting the length and width dimensions of the plate material.

[0031] (3b) The impact absorbing member described in (1b) or (2b) above may have an average length along the extending direction of each of the reinforcing portions that is twice or more the buckling range length of each of the side walls at the position of the bending initiation 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 that has bent into an "L" shape due to buckling deformation gradually closes. Here, since the length of each reinforcing part is more than twice the length of the buckling range, when the buckling deformation progresses and the "L" shape is completely closed, the pair of ridge sections connected with the buckling range of this "L" shape in between can be reliably brought into contact with each other. This contact between the ridge sections causes the rise of the secondary peak load. Here, since each side wall is reinforced in advance by the reinforcing part, the buckling range is localized (the part that buckles into an "L" shape is smaller than in the case without the reinforcing part). Therefore, in the case of small buckling deformation, the contact between the pair of ridge sections begins earlier than in the case of large buckling deformation, so the rise of the secondary peak load is accelerated. Furthermore, because each side wall is reinforced by a reinforcement section, pairs of ridge sections continue to abut strongly against each other. 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 delayed, which increases the load integral value. Thus, energy absorption can be increased.

[0032] (4b) The impact absorbing member described in (1b) or (2b) above 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, since the hollow tube is reinforced except for the inner wall and ridge sections of the bend, the amount of energy absorbed can be increased without significantly increasing the maximum load (primary peak load). Therefore, sudden load fluctuations can be suppressed most effectively.

[0033] (5b) The impact absorbing member described in (4b) above may have the following configuration: the hollow tube comprises a hat-shaped member having a top wall portion which is the inner wall portion of the bend and side wall portions connected to both sides of the top wall portion via the respective 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 each of the reinforcing portions has a length L along the extending direction of 70 mm to 500 mm and a width dimension w in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. According to the impact absorbing member described in (5b) above, the effects described in (1b) above can be obtained more reliably.

[0034] (6b) The impact absorbing member described in (1b) or (2b) above may be provided only in the area where each of the reinforcing portions overlaps with each of the side wall portions and 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 bend, the amount of energy absorbed can be increased while suppressing an excessive rise 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 comprises a hat-shaped member having a top wall portion which is the inner wall portion of the bend and side wall portions connected to both sides of the top wall portion via the respective 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 extending direction is 70 mm to 500 mm, and the width dimension w of the portion overlapping each of the side wall portions when viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. According to the impact absorbing member described in (7b) above, the effects described in (1b) above can be obtained more reliably.

[0036] (8b) The impact absorbing member described in (1b) or (2b) above may have the following configuration: the reinforcement has a first portion, a second portion, and a third portion arranged in order along the longitudinal direction; the break point has at least one of a through portion provided in the second portion or a bead formed to be long in a direction intersecting the longitudinal direction, and a rigid portion arranged in 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 and third portions of the reinforcement can be reduced, so that the impact absorbing member can be reliably deformed by bending at the bending initiation point.

[0037] (9b) The impact absorbing member described in (1b) or (2b) above may have the following configuration: the reinforcement has a first portion, a second portion, and a third portion arranged in order along the longitudinal direction; the flex point is formed in the second portion of the reinforcement including a connection point with the hollow tube, and has at least one of the following: a plate 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 to the first and third portions of the reinforcement can be reduced, so that the impact absorbing member can be reliably deformed by bending at the bending initiation point.

[0038] (10b) The shock-absorbing member described in (1b) or (2b) above may have the following configuration: the hollow tube has a first portion, a second portion, and a third portion arranged in order along the longitudinal direction; and the bending point has a reinforcement positioned at least in the second portion and a filler positioned 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 and third portions of the reinforcement can be reduced, so that the impact absorbing member can be reliably deformed by bending at the bending initiation point. [Effects of the Invention]

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

[0040] [Figure 1] This 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 the front side member and the rear side member. [Figure 2] This is a perspective view of the impact-absorbing member, in which beads are formed on each of a pair of ridges as a trigger point for bending. [Figure 3A] This is a partially enlarged longitudinal cross-sectional view of the main part of the impact-absorbing member, as seen in section AA of Figure 2. [Figure 3B] This figure shows a modified example of the same main part. [Figure 4] This diagram shows the process by which the shock-absorbing member undergoes bending deformation under axial compressive bending load, and is a perspective view showing the state after the maximum load has been applied. [Figure 5] This diagram shows the continuation of the bending deformation process, and is a perspective view showing the state at the point when the secondary peak load rises. [Figure 6] This diagram illustrates the process of the same bending deformation, and is a schematic view of section B in Figure 4 from the front. [Figure 7] This figure shows another form of the shock-absorbing member, a perspective view of which a long bead perpendicular to the longitudinal direction is formed on the top wall as a trigger for bending. [Figure 8] This figure shows yet another form of the same shock-absorbing member, a perspective view in which a through hole is formed in the top wall as a trigger for bending. [Figure 9]This figure shows yet another form of the same shock-absorbing member, a perspective view in which a pair of long beads are formed on the top wall portion along the longitudinal direction, sandwiching the bending point between them, as a bending trigger. [Figure 10] This figure shows yet another form of the same shock-absorbing member, in which a pair of long beads are formed along the longitudinal direction on each side wall portion, with the position of the bending initiation point in the longitudinal direction sandwiched between them, as a bending trigger. [Figure 11] This figure shows yet another form of the same impact-absorbing member, in which, as a trigger for breaking, at least one of the plate thickness / material strength of the central portion in the longitudinal direction is made thinner / lower than the adjacent portions in the longitudinal direction. This is a perspective view of the form. [Figure 12] This figure shows yet another form of the same shock-absorbing member, a perspective view of a form in which the member is bent and deformed into a Z shape by providing two bending points in the longitudinal direction. [Figure 13A] Figure 12 is a plan view showing the impact-absorbing member. [Figure 13B] Figure 12 shows an impact-absorbing member, and is a cross-sectional view of CC shown in Figure 13A. [Figure 13C] Figure 12 shows the impact absorbing member, and is a cross-sectional view of Figure 13A. [Figure 14] This figure shows yet another form of the same shock-absorbing member, a plan cross-sectional view of a form in which a filler material is used as a trigger for bending. [Figure 15] This is a diagram showing the same shock-absorbing member, and is a cross-sectional view of EE in Figure 14. [Figure 16] This is a perspective view illustrating an embodiment, 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. [Figure 17] This graph shows the load-deformation stroke curve (hereinafter referred to as the FS curve) when the length of the reinforcement part is changed in the same embodiment. [Figure 18] This graph shows the FS curve when the width and position of the reinforcement are changed in the same embodiment. [Figure 19]This diagram compares the maximum load and energy absorption when the length of the reinforcing section is changed in the same embodiment. (a) is a perspective view of the impact absorbing member showing the case where the length of the reinforcing section adjacent to the ridge is 260 mm, (b) is the case where the length of the reinforcing section adjacent to the ridge is 180 mm, and (c) is the case where the length of the reinforcing section adjacent to the ridge 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. [Figure 20] This diagram compares the maximum load and energy absorption when the width and position of the reinforcing portion are changed in the same embodiment. (a) is a perspective view of the impact absorbing member showing the case where the width of the reinforcing portion adjacent to the ridge is 20 mm, (b) is the case where the width of the reinforcing portion adjacent to the ridge is 10 mm, and (c) is the case where the width of the reinforcing portion is 10 mm and the reinforcing portion is positioned 10 mm below the end of the ridge. (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. [Figure 21] This diagram compares the maximum load and energy absorption when the width and position of the reinforcing part are changed in the same embodiment. (a) is a perspective view of the impact absorbing member showing the case where a reinforcing part with a width of 20 mm and a length of 260 mm is placed adjacent to the edge of each side wall, (b) is a case where two reinforcing parts with a width of 20 mm and a length of 260 mm are placed near the edge of the top wall, and (c) is a case where one reinforcing part with a width of 40 mm and a length of 260 mm is placed in the center of the top wall. (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. [Figure 22]This is a comparative diagram of the maximum load and energy absorption in the same embodiment when the reinforcing part is arranged to overlap the ridge line. (a) is a perspective view of the impact absorbing member showing the case where the reinforcing part is arranged only on the ridge line, (b) is a case where the reinforcing part of (a) is further extended toward the top wall by a width of 10 mm, (c) is a case where the reinforcing part of (a) is further extended toward the side wall by a width of 10 mm, and (d) is a case where the reinforcing part of (a) is further extended toward both the top wall and the side wall by a width of 10 mm each. (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. [Figure 23] This is a perspective view of an impact absorbing member according to a second embodiment of the present invention. [Figure 24A] Figure 23 is a partially enlarged longitudinal cross-sectional view of the main part of the impact-absorbing member, as seen in the FF section. [Figure 24B] This figure shows a modified example of the same main part. [Figure 25] This diagram shows the process by which the shock-absorbing member undergoes bending deformation under axial compressive bending load, and is a perspective view showing the state after the maximum load has been applied. [Figure 26] This diagram shows the continuation of the bending deformation process, and is a perspective view showing the state at the point when the secondary peak load rises. [Figure 27] This diagram illustrates the process of the same bending deformation, and is a schematic view of section G in Figure 25 from a plan view. [Figure 28] This is a perspective view showing an example of the trigger point for the breakage of the reinforcement in the impact-absorbing member. [Figure 29] This perspective view shows another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 30] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 31] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 32]This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 33] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 34] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 35] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 36] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 37] This perspective view shows yet another example of the trigger point for the breakage of the reinforcement in the same shock-absorbing member. [Figure 38] This figure shows yet another example of the trigger point for the reinforcing element in the same shock-absorbing member, and is a cross-sectional view taken in a longitudinal section including the center line. [Figure 39] Figure 38 shows a shock-absorbing member, and is a cross-sectional view of HH in Figure 38. [Figure 40] Figure 38 shows a shock-absorbing member, and is a cross-sectional view II of Figure 38. [Figure 41] This figure shows yet another example of the trigger point for the reinforcing element in the same shock-absorbing member, and is a cross-sectional view taken in a longitudinal section including the center line. [Figure 42] Figure 41 shows a shock-absorbing member, and is a cross-sectional view of JJ in Figure 41. [Figure 43] This figure shows the impact-absorbing member used in the same embodiment, and is a cross-sectional view of FF in Figure 23. Of these, Case 000 and 005 are comparative examples. On the other hand, Case 001 to Case 004 are examples of inventions that include a reinforcing part. [Figure 44] This diagram illustrates an embodiment and is a perspective view showing how an axial compressive bending load is applied to the shock-absorbing member. (a) shows the member before the axial compressive bending load is applied, and (b) shows the member after the axial compressive bending load is applied and the member has been deformed. [Figure 45]This bar graph compares the maximum loads in the same embodiment, with the horizontal axis representing the case number and the vertical axis representing the maximum load (kN). [Figure 46] This bar graph compares the energy absorption amounts in the same embodiment, with the horizontal axis representing the case number and the vertical axis representing the energy absorption amount (kJ). [Modes for carrying out the invention]

[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 Figure 1, the impact-absorbing member of this embodiment can be used as a front side member FM or a rear side member RM, which are structural members of an automobile. When the impact-absorbing member is used as a front side member FM, it is positioned on the vehicle forward side FW from the passenger compartment Ca. On the other hand, when the impact-absorbing member is used as a rear side member RM, it is positioned on the vehicle rear side RW from the passenger compartment Ca. The impact-absorbing member is a long hollow tube in one direction, and in both cases, whether used as a front side member FM or a rear side member RM, it is positioned so that one end in the longitudinal direction faces the front of the vehicle and the other end in the longitudinal direction faces the rear of the vehicle.

[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 apex, which is the top wall portion with a cross-section perpendicular to its longitudinal direction, and a pair of side walls connected to both sides of this hat apex. The plate-shaped member is joined to the hat-shaped member and faces the hat apex. The impact-absorbing member absorbs impact force through folding deformation rather than bellows deformation. Hereafter, the folding deformation range shown in Figure 1 will be denoted by reference numeral 1 and will be illustrated and described as 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 has a hat-shaped member 10 and a plate-shaped member 20. In Figure 2, 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. For the sake of explanation, in the following, the X direction in Figure 2 may be described 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 member 10 has a single top wall portion 11, a pair of side wall portions 12, and a pair of flange portions 13. The top wall portion 11 forms the apex of the hat of the hat-shaped member 10, which is hat-shaped when viewed along the center line CL. The top wall portion 11 is a long plate having a substantially constant width dimension W and a substantially constant plate thickness T1, and is long along the center line CL. The top wall portion 11 has a flat top surface and a flat bottom surface. The width dimension W can be exemplified as 30 mm to 100 mm. The plate thickness T1 can be exemplified as 0.8 mm to 3.2 mm. The plate thickness T1 values ​​exemplified here are for when steel is used as the material for the shock-absorbing member 1. When the shock-absorbing member 1 is manufactured from an aluminum extruded material, the upper limit of the plate thickness T1 can be exemplified as 4.0 mm. Furthermore, the width W and thickness T1 of the top wall 11 do not necessarily have to be constant at each position along the center line CL, and may be changed at each position along the center line CL as required by the component design. Similarly, the upper and lower surfaces of the top wall 11 do not necessarily have to be flat, and may have some irregularities as required by the component design.

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

[0046] The pair of flange portions 13 have 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 wall portion 12a. The left flange portion 13a is a strip-shaped plate having a substantially constant width and substantially constant 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 substantially constant 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. Furthermore, 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 be changed at each position along the center line CL as necessary for the part design. Similarly, the upper and lower surfaces of the left flange portion 13a and the right flange portion 13b do not necessarily have to be flat, and may have some irregularities depending on the shape of the plate-like member 20.

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

[0048] As shown in Figure 2, each ridge section EL has a substantially constant width dimension, and its cross-section perpendicular to its longitudinal direction is curved in an arc shape across its entire width. Each ridge section EL has one side edge ELa connected to the top wall section 11 and the other side edge ELb connected to the left wall section 12a or the right wall section 12b. While each ridge section EL has an arc-shaped cross-section, the top wall section 11, the left wall section 12a, and the right wall section 12b each have a flat cross-sectional shape. Therefore, from the perspective of each ridge section EL, one side edge ELa and the other side edge ELb are the boundaries (end of the arc) where the cross-sectional shape changes from an arc to a flat cross-section.

[0049] The combination of the top wall portion 11, the left wall portion 12a, and the right wall portion 12b results in a roughly trapezoidal shape in the cross-section perpendicular to the center line CL. Furthermore, by combining the left flange portion 13a and the right flange portion 13b with this combination, a hat-shaped member 10 is constructed in which the cross-section perpendicular to the longitudinal direction is hat-shaped. This hat-shaped member 10 is obtained by press-forming a die-cut sheet metal. The material of the hat-shaped member 10 is metal, and high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used.

[0050] The plate-shaped member 20 is a long metal plate along the center line CL, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used. The plate-shaped member 20 has a flat top surface and a flat bottom surface. The plate-shaped member 20 is welded to the left flange portion 13a and the right flange portion 13b at both side edges. This forms a closed cross-section between the hat-shaped member 10 and the plate-shaped member 20. Furthermore, the width and thickness of the plate-like member 20 do not necessarily have to be constant at each position along 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 plate-like 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 bending trigger. The reinforcing portion 40 has a left reinforcing portion 40a and a right reinforcing portion 40b. As shown in Figures 2 and 3A, the left reinforcing section 40a is a long, strip-shaped metal plate along the center line CL, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used as its material. The left reinforcing section 40a is fixed by welding to the left wall section 12a at its longitudinal center and adjacent to the ridge line EL. Here, as shown in Figure 3A, the left reinforcing section 40a is positioned so as not to overlap with the ridge line EL. The left reinforcing section 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 plate thickness of 0.8 mm to 3.2 mm. The plate thickness values ​​exemplified here are for the case where steel is used as the material for the impact absorbing member 1. When the impact absorbing member 1, including the left reinforcing section 40a, is manufactured from an aluminum extruded material, 4.0 mm can be exemplified as the upper limit of the plate thickness of the left reinforcing section 40a.

[0052] Similarly, the right reinforcing section 40b is a long, strip-shaped metal plate along the center line CL, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used as its material. The right reinforcing section 40b is fixed by welding to the right wall section 12b at its longitudinal center and adjacent to the ridge line EL. Here, the right reinforcing section 40b is also positioned so as not to overlap with the ridge line EL. The right reinforcing section 40b has the same shape as the left reinforcing section 40a. That is, the right reinforcing section 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 plate thickness of 0.8 mm to 3.2 mm. The plate thickness values ​​exemplified here are for the case where steel is used as the material for the impact absorbing member 1. When the impact absorbing member 1, including the right reinforcing section 40b, is manufactured from an aluminum extruded material, 4.0 mm can be exemplified as the upper limit of the plate thickness of the right reinforcing section 40b.

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

[0054] The left reinforcement section 40a reinforces only the area near the ridge section EL of the left wall section 12a. Similarly, the right reinforcement section 40b reinforces only the area near the ridge section EL of the right wall section 12b. Therefore, the upper surfaces of each ridge section EL and the upper surface of the top wall section 11 are not reinforced. In other words, while avoiding the upper surface of the top wall section 11 and the upper surfaces of the pair of ridge sections EL, only the portions of the left wall section 12a and the right wall section 12b near the ridge sections EL are reinforced by the left reinforcement section 40a and the right reinforcement section 40b, respectively.

[0055] Furthermore, as shown in Figure 3B, the left reinforcing portion 40a and the right reinforcing portion 40b may reinforce the hat-shaped member 10, including the ridge portion 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 position near the ridge portion EL of the left wall portion 12a and the position overlapping the ridge portion EL. Similarly, the right reinforcing portion 40b may be joined by welding or the like to both the position near the ridge portion EL of the right wall portion 12b and the position overlapping the ridge portion EL. In this modified example, as shown in Figure 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 ridge portion EL. In the modified form of Figure 3B, similar to the configuration in Figure 3A, the lengths L of the left reinforcement section 40a and the right reinforcement section 40b can both be set to 70mm to 500mm. On the other hand, the width dimension (total width dimension) of the left reinforcement section 40a and the right reinforcement section 40b only needs to be such that the width dimension w (partial width dimension) of the flat portion overlapping the left wall section 12a and the right wall section 12b is 10mm to 60mm, and the width dimension (partial width dimension) of the portion overlapping with the ridge section EL is arbitrary. However, it is necessary to set these left reinforcement sections 40a and the right reinforcement section 40b so that they do not overlap the top wall section 11.

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

[0057] The aforementioned bending trigger involves setting a bending initiation point BP midway along the longitudinal direction of the outer surface of the top wall portion 11, which is the inner wall portion of the hollow tube 30. In other words, the bending trigger is a configuration that causes the hollow tube 30 to bend and deform at the bending initiation point BP of the top wall portion 11 so that the outer surface of the top wall portion 11 becomes concave, and various forms of this configuration are conceivable.

[0058] For example, in the embodiment shown in Figure 2, a pair of left beads Ba and right beads Bb (first beads) are provided on each ridge portion EL of the hollow tube 30 and at positions corresponding to the bending initiation point BP in the longitudinal direction, as a bending trigger. In other words, as shown in Figure 2, a right bead Bb is formed at one point on the ridge line EL connecting the top wall section 11 and the right side wall section 12b. The right bead Bb crosses the boundary (end of the curve) between the top wall section 11 and the ridge line EL. That is, the right bead Bb is formed to protrude outwards from the ridge line EL toward the top wall section 11. Furthermore, the right bead Bb is formed to protrude outwards from the ridge line EL toward the right side wall section 12b. Therefore, the right bead Bb is formed to extend from the top wall section 11 through the ridge line EL toward the right side wall section 12b.

[0059] Similarly, a left bead Ba is formed on the ridge EL connecting the top wall 11 and the left side wall 12a. The left bead Ba crosses the boundary (end of the curve) between the top wall 11 and the ridge EL. In other words, the left bead Ba is formed to protrude from the ridge EL toward the top wall 11. Furthermore, the left bead Ba is formed to protrude from the ridge EL toward the left side wall 12a. Therefore, the left bead Ba is formed to extend from the top wall 11 through the ridge EL toward the left side wall 12a.

[0060] The left bead Ba and the right bead Bb are rhombic in front view, and their diagonal length can be exemplified as 11 mm to 23 mm. The outer surface depth of the left bead Ba and the right bead Bb can be exemplified as 7 mm to 15 mm. The left bead Ba and the right bead Bb may be formed simultaneously during press working when forming the hat-shaped member 10 from a metal sheet, or they may be formed as a post-processing step 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 thickness is slightly thinner than the surrounding thickness and they are work-hardened. The inner surfaces of the left bead Ba and the right bead Bb are concave, just as their outer surfaces are concave, and they are also concave towards the inside of the hollow tube 30.

[0061] The front view shapes of the left bead Ba and the right bead Bb are not limited to rhombuses; they may also be circular, elliptical, rectangular, or polygonal. While it is preferable that the shapes and dimensions of the left bead Ba and the right bead Bb are the same, 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 bending 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 them. 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 Figure 2, the bending initiation point BP is a localized area set within the outer surface of the top wall portion 11, where the impact absorbing member 1 undergoes buckling deformation and breaks when subjected to impact energy in the -X direction. This bending initiation point BP is a part that is pre-set during the design phase to actively induce bending deformation. In this embodiment, the impact-absorbing member 1 has a bending point BP positioned midway along the longitudinal direction of the reinforcing portion 40. Specifically, the left reinforcing portion 40a is positioned on the left side wall portion 12a such that the bending point BP is located midway along its longitudinal direction. Similarly, the right reinforcing portion 40b is positioned on the right side wall portion 12b such that the bending point BP is located midway along its longitudinal direction. It is preferable that the bending point BP be positioned at the center along the longitudinal direction of the left reinforcing portion 40a and the right reinforcing portion 40b. Furthermore, as shown in Figure 2, the length L along the extension direction of the left reinforcement section 40a and the right reinforcement section 40b is more than twice the buckling range length LB at the bending initiation point BP of the left wall section 12a and the right wall section 12b. This allows for high collision energy absorption with a short deformation stroke while suppressing rapid load fluctuations. The mechanism is explained below using Figures 4 to 6.

[0063] Figure 4 shows the process by which the impact absorbing member 1 undergoes bending deformation under axial compressive bending load, and is a perspective view showing the bent state after the maximum load has occurred. Figure 5 shows a continuation of the bending deformation process in Figure 4, and is a perspective view showing the state at the point when the secondary peak load rises. As shown in Figure 4, when the impact absorbing member 1 receives impact energy along its longitudinal direction, it deforms at the bending initiation point BP, bending inward with the outer surface (upper surface) of the top wall portion 11. The absorption of impact energy during this bending deformation is achieved at the bending initiation point BP by the deformation of the upper surface of the top wall portion 11 concave, the deformation of the left wall portion 12a and the right wall portion 12b bending in an "L" shape in a direction that separates them from each other, and the deformation of the left reinforcing portion 40a and the right reinforcing portion 40b bending in an "L" shape in a direction that separates them from each other. At the bending initiation point BP at this time, mainly compressive deformation occurs at the positions of the top wall portion 11, the left wall portion 12a, and the right wall portion 12b. On the other hand, tensile deformation occurs at the left reinforcing portion 40a and the right reinforcing portion 40b. The impact energy is absorbed by these compressive and tensile deformations.

[0064] The maximum load on the impact absorbing member 1 when collision energy is applied increases with the structural strength of the top wall portion 11. If the maximum load is too high, the rate at which the load drops due to bending deformation after the maximum load occurs will also be abrupt. In a vehicle equipped with the impact absorbing member 1, it is preferable to avoid such large load fluctuations being applied to the 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 portion EL and extending along the direction of extension of each ridge portion EL. In other words, since these left reinforcing portions 40a and the right reinforcing portion 40b do not reinforce the top wall portion 11, the maximum load of the impact-absorbing member 1 does not need to be excessively increased.

[0065] On the other hand, as described above, the collision energy is absorbed not only by the bending deformation of the top wall 11, but also by the buckling deformation of the left wall 12a and the right wall 12b into an "L" shape at the bending initiation point BP. At this time, the left wall 12a and the right wall 12b are less likely to bend into an "L" shape due to the reinforcement by the left reinforcing part 40a and the right reinforcing part 40b. Therefore, the drop in load after the occurrence of the maximum load in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram) can be made gentler. As a result, the maximum load value in the FS diagram can be suppressed while increasing the load integral value after the occurrence of the maximum load. Thus, the amount of energy absorbed can be increased.

[0066] Furthermore, it is possible to accelerate the rise time of the secondary peak load in the FS diagram. To explain this, first, the parts of the left reinforcement section 40a and the right reinforcement section 40b that were bent into an "L" shape due to buckling deformation gradually close. As a result of the "L" shape being completely closed, the two straight sections on either side of the "L" shape in the ridge section EL come into contact with each other, resulting in the state shown in Figure 5. This contact between the two straight sections in the ridge section EL causes the rise of the secondary peak load.

[0067] Figure 6 shows the deformation of the ridge portion EL during the bending deformation process described above. Figure 6 is a diagram illustrating the bending deformation process and is a schematic front view of the bending initiation point BP and its surrounding portion of the ridge portion EL of the impact absorbing member 1 in Figure 4. In Figure 6, the solid line represents the ridge portion EL of the impact absorbing member 1 of this embodiment, and the dashed line represents the ridge portion EL' in a conventional structure without the reinforcing portion 40.

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

[0069] Furthermore, in the impact absorbing member 1 of this embodiment, the side walls 12 (left wall 12a and right wall 12b) are reinforced by the reinforcing parts 40 (left reinforcing part 40a and right reinforcing part 40b), so that the two straight sections of the ridge line EL can continue to strongly abut 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, thus increasing the amount of energy absorbed.

[0070] As described above, in the impact absorbing member 1 of this embodiment, the lengths of the left reinforcing portion 40a and the right reinforcing portion 40b are set to be at least twice the buckling range length LB shown in Figure 2. The buckling range length LB here refers to the maximum length dimension in the direction along the center line CL of the range in which buckling deformation occurs during bending deformation. This maximum value can be determined by performing numerical calculations during the design stage, or by manufacturing sample materials and conducting load tests.

[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-shaped member 20 to the outer surface of the top wall portion 11, as illustrated in Figure 2, is H (mm), then the maximum value, i.e., the buckling range length LB, can also be predicted to be H (mm). Therefore, it is preferable to set the lengths of the left reinforcement portion 40a and the right reinforcement portion 40b to 2 × H (mm) (twice the buckling range length LB) or more.

[0072] Here, Figure 2 illustrates the case where the height dimension H at the left wall section 12a and the height dimension H at the right wall section 12b are equal. However, if they are not equal, and the height dimension at the left wall section 12a is H1 and the height dimension at the right wall section 12b is H2 (H1 ≠ H2), the buckling range length LB can be predicted using the average of these values. 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 reinforcement section 40a and the right reinforcement section 40b so that they are equal to or greater than (H1 + H2), which is twice (H1 + H2) / 2. Thus, the buckling range length LB can be defined even when the height dimension H(H1) at the left wall section 12a and the height dimension H(H2) at the right wall section 12b are not equal. In effect, it can be said that the buckling range length LB is the average of the buckling range length LB based on height dimension H1 and the buckling range length LB based on 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 reinforcement section 40a and the right reinforcement section 40b at least twice the length LB of the buckling range, as shown in Figure 5, when the buckling range is completely buckled, a pair of straight sections of each ridge section EL that are connected with the buckling range in between can more reliably abut against each other. Therefore, it is preferable to make the length L at least twice the length LB.

[0074] Incidentally, in the embodiment shown in Figure 2, a configuration is adopted in which the left bead Ba and the right bead Bb are provided as the break-in triggers. However, the break-in triggers are not limited to this embodiment, and other embodiments such as the following can also be adopted. Furthermore, each of the break-in trigger embodiments exemplified here may be used individually, but multiple types may be appropriately selected and combined as needed.

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

[0076] The elongated bead Bc has a rectangular shape in its longitudinal center and semicircular shapes at both ends. The width of the elongated bead Bc can be 20mm to 40mm. The length of the elongated bead Bc can be 50mm to 80mm. The depth of the elongated bead Bc can be 4mm to 15mm. The elongated bead Bc may be formed simultaneously during the press working process when forming the hat-shaped member 10 from the metal sheet, or it may be formed by post-processing by pressing the hat-shaped member 10. When the elongated bead Bc is formed by press working, its thickness is slightly thinner than the surrounding sheet thickness and it is work-hardened. Similar to the concave outer surface of the elongated bead Bc, its inner surface is also concave towards the inside of the hollow tube 30. The number of elongated beads Bc is not limited to one; there may be two or more. Furthermore, while Figure 7 illustrates a configuration where the longitudinal direction of the horizontally elongated bead Bc is perpendicular to the longitudinal direction of the impact absorbing member 1, it may also have a slight angle with respect to the perpendicular direction.

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

[0078] Furthermore, in the embodiment shown in Figure 8, a through hole Ta is formed at the position of the bending point BP of the top wall portion 11, serving as a bending trigger. The through-hole Ta is circular, and its inner diameter can be exemplified as 20mm to 40mm. 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 ridge portions EL. In the bending initiation point of this embodiment, the portion including the through-hole Ta forms the second portion R2 that undergoes buckling deformation. The first portion R1 is located on one side of the second portion R2 in the longitudinal direction, and the third portion R3 is located on the other side. Therefore, when a load along the center line CL is applied to this impact absorbing member 1, the through-hole Ta of the second portion R2 bends with the bending initiation point BP. This bending absorbs the impact energy. Furthermore, the shape of the through-hole Ta is not limited to a circular shape; other shapes such as an ellipse may also be used. Additionally, the number of through-holes Ta in the top wall section 11 may be multiple.

[0079] Furthermore, in the embodiment shown in Figure 9, elongated vertical beads (third beads) Bd and Be are provided at the first section R1 and the third section R3, respectively, and are formed on the top wall 11 along the longitudinal direction of the hollow tube 30, serving as bending points. Except for these elongated beads Bd and Be, the top wall 11 has a flat top surface and a flat bottom surface.

[0080] The elongated bead Bd is formed on one side of the center in the width direction of the top wall 11 when viewed from the front, and is located on one side of the center in the longitudinal direction of the top wall 11. In other words, the elongated bead Bd is positioned on the one side of the top wall 11, avoiding the center in the longitudinal direction. The elongated bead Bd is long and straight along the longitudinal direction of the top wall 11 and is parallel to the center line CL. Except for both ends, the width dimension of the elongated bead Bd is constant at each position in its longitudinal direction. Examples of this width dimension include 20 mm to 40 mm. The depth dimension of the elongated bead Bd is also constant at each position in its longitudinal direction. Examples of this depth dimension include 4 mm to 15 mm when the circumference of the elongated bead Bd is used as the reference point. Both ends of the elongated bead Bd in the longitudinal direction have a semicircular shape when viewed from the front.

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

[0082] The elongated beads Bd and Be are arranged in the same straight line when viewed from the front of the top wall portion 11. A gap is provided between these elongated beads Bd and Be. That is, there is no recess between the end of the elongated bead Bd and the end of the elongated bead Be, and it is a flat surface flush with the periphery of the elongated beads Bd and Be. The minimum dimension of the gap can be exemplified as 15 mm to 30 mm. The gap is the bending point BP, and is located at the center of the width direction of the top wall portion 11. The elongated beads Bd and Be may be formed simultaneously during press working when forming the hat-shaped member 10 from a metal sheet, or they may be formed as a post-processing step on the hat-shaped member 10 after press forming. When the elongated beads Bd and Be are formed by press working, their thickness is slightly thinner than the surrounding thickness and they are work-hardened. The elongated beads Bd and Be are concave on the outside, and their inner surfaces are also concave towards the inside of the hat-shaped member 10. When a load is applied to this impact-absorbing member 1 along the center line CL, the top wall portion 11 at the second portion R2 bends, with the bending point BP acting as the bending initiation point. This bending then absorbs the impact energy.

[0083] Furthermore, in the embodiment shown in Figure 10, long, elongated beads (third beads) Bf and Bg are provided at the first section R1 and the third section R3, respectively, as bending points, and are formed on each side wall 12 along the longitudinal direction of the hollow tube 30. Except for these elongated beads Bf and Bg, each side wall 12 has a flat outer surface and a flat inner surface.

[0084] The elongated bead Bf is formed on the right side of the wall portion 12b, passing through its widthwise center when viewed from the front, and on one side of the longitudinal center of the right side of the wall portion 12b. In other words, the elongated bead Bf is positioned on the one side avoiding the longitudinal center of the right side of the wall portion 12b. The elongated bead Bf is long and straight along the longitudinal direction of the right side of the wall portion 12b and is parallel to the center line CL. The elongated bead Bf has a constant width dimension at each position along its longitudinal direction, except for both ends. This width dimension can be exemplified by the same width dimension as the elongated bead Bd described above. The elongated bead Bf has a constant depth dimension at each position along its longitudinal direction. This depth dimension can be exemplified by the same depth dimension as the elongated bead Bd described above. Both ends of the elongated bead Bf in the longitudinal direction have a semicircular shape when viewed from the front.

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

[0086] The elongated beads Bf and Bg are arranged in the same straight line when viewed from the front of the right wall portion 12b. A gap is provided between these elongated beads Bf and Bg. That is, there is no recess between the end of elongated bead Bf and the end of elongated bead Bg, and the space between them is a flat surface flush with the periphery of elongated beads Bf and Bg. The minimum dimension of this gap can be exemplified by the same dimension as the gap between elongated beads Bd and Be described above. This gap is the bending point BP and is located at the center of the width direction of the right wall portion 12b. The elongated beads Bf and Bg may be formed simultaneously during press working when forming the hat-shaped member 10 from a metal sheet, or they may be formed as a post-processing step on the hat-shaped member 10 after press forming. When the elongated beads Bf and Bg are formed by press working, their thickness is slightly thinner than the surrounding thickness and they are work-hardened. The elongated beads Bf and Bg have concave outer surfaces, and their inner surfaces are also concave toward the interior of the hat-shaped member 10. The right side wall portion 12b has a flat outer surface and a flat inner surface, excluding the portions of the elongated beads Bf and Bg.

[0087] The left wall portion 12a also has elongated beads Bf and Bg, but their arrangement and dimensions are the same, so a redundant explanation is omitted. When viewed along the longitudinal direction of the shock-absorbing member 1, the elongated beads Bf formed on the left wall portion 12a and the elongated beads Bf formed on the right wall portion 12b are formed at the same position. Also, when viewed along the longitudinal direction of the shock-absorbing member 1, the elongated beads Bg formed on the right wall portion 12b and the elongated beads Bg formed on the left wall portion 12a are also formed at the same position. Furthermore, the gap formed on the left wall portion 12a and the gap formed on the right wall portion 12b are also formed at the same position along the longitudinal direction of the shock-absorbing member 1.

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

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

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

[0091] Furthermore, in the configuration shown in Figures 12 to 13C, two opposite bends are pre-applied to the hollow tube 30 along its longitudinal direction as a starting point for bending. As a result, the hollow tube 30 is straight in a side view but S-shaped in a plan view. One of the two bends is on the outer surface of the top wall portion 11, which is the first bending point BP. The other of the two bends is on the outer surface of the plate-like member (opposing wall portion) 20, which is the second bending point BP. The two bending points BP are spaced apart from each other in the longitudinal direction of the hollow tube 30, and their directions are opposite to each other. Furthermore, at the first bending point BP, reinforcing sections 40 (left reinforcing section 40a, right reinforcing section 40b) are positioned adjacent to and along the pair of ridge sections EL that connect the top wall section 11 and each side wall section 12. Therefore, both the left reinforcing section 40a and the right reinforcing section 40b have pre-defined curved shapes that match the curved shape of the ridge section EL.

[0092] On the other hand, at the second bending point BP, other reinforcing parts 40 (left reinforcing part 40a, right reinforcing part 40b) are formed adjacent to and along the pair of ridge lines ELx that connect the plate-like member (opposing wall part) 20 and each side wall part 12. Therefore, these left reinforcing parts 40a and right reinforcing parts 40b also have a curved shape that matches the curved shape of the ridge line ELx. The bending direction of the reinforcing parts 40 (left reinforcing part 40a, right reinforcing part 40b) at the first bending point BP and the bending direction of the reinforcing parts 40 (left reinforcing part 40a, right reinforcing part 40b) at the second bending point BP are opposite to each other. In this embodiment, when a load along the center line CL is applied to the impact absorbing member 1, the impact absorbing member 1 absorbs the impact energy while bending and deforming from an S-shape to a Z-shape, as the two bending points BP bend in opposite directions.

[0093] Furthermore, in the embodiments shown in Figures 14 and 15, when viewing the hollow tube 30 along its longitudinal direction, the portion including the bending point BP is designated as the second portion R2, one side of the second portion R2 is designated as the first portion R1, and the other side of the second portion R2 is designated as the third portion R3. Then, as a starting point for bending, the first portion R1 and the third portion R3, excluding the second portion R2, are filled with filler material 50. On the other hand, the second portion R2 remains hollow. Therefore, when viewing the hollow tube 30 along its longitudinal direction, the bending strength of the second portion R2 is relatively lower than that of the first portion R1 and the third portion R3, which are reinforced with filler material 50. On the other hand, the shape and arrangement of the reinforcing parts 40 (left reinforcing part 40a and right reinforcing part 40b) are the same as those described in Figure 2. In this embodiment, when a load along the center line CL is applied to the impact absorbing member 1, the impact absorbing member 1 absorbs the impact energy by bending, with 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 configuration for initiating the break is to set the arrangement of the impact absorbing member 1 so that the collision energy is input from a height 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 input position of the collision energy can be offset by a predetermined height dimension. In the case of Figure 16, the center line CL of the impact absorbing member 1 is lower than the center of the holding member that applies collision energy to the impact absorbing member 1. Therefore, the impact energy can be absorbed while the member deforms by breaking with the longitudinal center position of the top wall portion 11 as the break initiation point BP.

[0095] The basic structure of the impact-absorbing member 1 of the first embodiment described above is summarized below. (1) As shown in Figure 2, etc., the impact absorbing member 1 of this embodiment has a hollow tube 30 that is long in one direction, and when viewed in a cross section perpendicular to the longitudinal direction which is the one direction, the hollow tube 30 has a top wall portion (bent inner wall portion) 11 and a pair of side wall portions 12 that are connected to the top wall portion 11 via a pair of ridge portions EL. The impact absorbing member 1 is provided on the hollow tube 30 and is configured to set a bending point BP on the top wall portion 11 at an intermediate position in the longitudinal direction of the hollow tube 30; and a pair of reinforcing portions 40 that extend along the extending direction of each ridge portion EL and are provided at positions adjacent to each ridge portion EL 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 bending point BP. Here, the pair of reinforcing parts 40 are arranged on the outer surface of the left reinforcing part 40a or the right reinforcing part 40b, as shown in the cross-sectional views of Figures 3A and 3B, and are in contact with or overlapping each ridge section EL, but not overlapping the upper surface of the top wall section 11. Comparing Figures 3A and 3B, Figure 3A is more preferable because it can more reliably suppress the increase in the 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 joined to at least the outer surface of each side wall portion 12 and may be a long strip-shaped plate material along the extending direction. (3) As shown in Figure 2, etc., in the impact absorbing member 1 described in (1) or (2) above, the average length L of each reinforcing portion 40 along its extending direction may be twice or more the buckling range length LB of each side wall portion 12 at the position of the bending initiation portion BP.

[0097] (4) As shown in Figure 3A, etc., in the impact absorbing member 1 described in any one of the above items (1) to (3), each of the reinforcing parts 40 may be provided only on each side wall part 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 adopt the following configuration: the hollow tube 30 comprises a hat-shaped member 10 having a top wall portion 11 which is the inner wall portion of the bend and side wall portions 12 connected to both sides of the top wall portion 11 via each ridge portion EL, and a plate-shaped member 20 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-shaped 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-shaped member 20 is 0.8 mm to 3.2 mm; and each of the reinforcing portions 40 has a length L along the extending direction of 70 mm to 500 mm and a width dimension w in a cross section perpendicular to the longitudinal direction of 10 mm to 60 mm.

[0098] (6) As shown in Figure 3B, etc., the impact absorbing member 1 described in any one of the above items (1) to (3) may be provided with each reinforcing portion 40 only in the range that overlaps each side wall portion 12 with 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 adopt the following configuration: the hollow tube 30 comprises a hat-shaped member 10 having a top wall portion 11 which is the inner wall portion of the bend and side wall portions 12 connected to both sides of the top wall portion 11 via the respective ridge portions EL, and a plate-shaped member 20 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-shaped 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-shaped member 20 is 0.8 mm to 3.2 mm; the length L of each reinforcing portion 40 along the extending 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 Figure 2, in the impact absorbing member 1 described in any one of the above items (1) to (7), the break-starting point may include a left bead Ba and a right bead Bb (first bead) provided on a pair of ridge portions EL of the hollow tube 30 and at the position of the break-starting point BP. (9) As shown in Figure 7, in the impact absorbing member 1 described in any one of the above items (1) to (8), the bending trigger may include a horizontally elongated bead (second bead) Bc that is provided at the bending starting point BP of the top wall portion 11 and is long in the direction intersecting the longitudinal direction. (10) As shown in Figure 8, in the impact absorbing member 1 described in any one of the above items (1) to (9), the trigger point for bending may include a through hole Ta provided at the position of the bending starting 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 the above items (1) to (10), when the hollow tube 30 is viewed along the longitudinal direction, the portion including the bending initiation point BP is designated as the second portion R2, one side of the second portion R2 as the first portion R1, and the other side of the second portion R2 as the third portion R3, the bending initiation points may be provided in the first portion R1 and the third portion R3 respectively, and may also include long vertical beads (third beads) Bd,Be along the longitudinal direction. (12) As shown in Figure 11, the shock absorbing member 1 described in any one of the above items (1) to (11) may include, when the hollow tube 30 is viewed along the longitudinal direction, the portion including the bending initiation point BP is designated as the second portion R2, one side of the second portion R2 as the first portion R1, and the other side of the second portion R2 as the third portion R3, and the bending initiation point may include at least one of the difference in plate thickness and the difference in material strength provided 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 the above items (1) to (12), the bending trigger may include a bent shape of the hollow tube 30 that makes the outer surface of the top wall portion 11 a concave surface at the position of the bending trigger portion BP. (14) As shown in Figures 13A to 13C, etc., in the impact absorbing member 1 described in any one of the above items (1) to (13), when viewing the hollow tube 30 along the longitudinal direction, the portion including the bending point BP is designated as the second portion R2, one side of the second portion R2 as the first portion R1, and the other side of the second portion R2 as the third portion R3, the bending point may include the filler material 50 filled in the first portion R1 and the third portion R3, respectively, 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 the above items (1) to (14) may have the following configuration: The hollow tube 30 has a plate-like member (opposing wall portion) 20 that is positioned opposite the top wall portion 11 and connected to a pair of side wall portions 12 via a pair of other ridge portions ELx; the hollow tube 30 is provided with other bending points that are configured to set other bending points BP on the plate-like member 20 at other intermediate positions in the longitudinal direction of the hollow tube 30; and the hollow tube 30 is further provided with a pair of other reinforcing portions 40 that extend along the extending direction of each other ridge portion ELx and are provided on each outer surface of each side wall portion 12 adjacent to each other ridge portion ELx when the hollow tube 30 is viewed in a cross section perpendicular to the longitudinal direction at the position of the other bending points BP.

[0103] The embodiments and various modifications described above are examples of the present invention, and various changes and combinations may be made without departing from the spirit of the invention. For example, the left reinforcing section 40a and the right reinforcing section 40b are constructed from strip-shaped plate material, but the configuration is not limited to this. The reinforcing section 40 only needs to partially reinforce the same position and shape range as the left reinforcing section 40a and the right reinforcing section 40b. Examples of means of this reinforcement include patchwork, tailored weld blanks, weld beads, and heat treatment. [Examples]

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

[0105] For each of the above calculation models, the maximum load and energy absorption were numerically calculated when a load was applied and the model was deformed by bending, as shown in Figures 16(a) and (b). For example, Figure 17 shows the results of calculating the load fluctuation for each deformation stroke for the calculation models shown in Figures 19(a) to (c) and the reference model in Figure 21(c). In Figure 17, the horizontal axis is the deformation stroke (unit: mm), and the vertical axis is the load (unit: kN). In Figure 17, the integral of the load values ​​in the deformation stroke range from 0 to 50 mm gives the energy absorption amount (unit: kJ) at a deformation stroke of 50 mm. Also, in Figure 17, the integral of the load values ​​in the deformation stroke range from 0 to 100 mm gives 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 first peak load value that appears when the deformation stroke increases from 0 mm. From the viewpoint of suppressing load fluctuations as described above, it is preferable to prevent this maximum load from becoming excessively high. In addition, suppressing the drop in load value after the maximum load occurs is preferable from the viewpoint of increasing energy absorption. That is, by making the drop in load value gradual, the load integral value (energy absorption) after the maximum load occurs can be increased.

[0107] As shown in Figure 17, the load values ​​in each calculation model initially drop, then rise, reaching a secondary peak. Here, it is preferable to accelerate the rise time of the load towards the secondary peak from the viewpoint of increasing energy absorption. In other words, by accelerating the rise time of the load towards the secondary peak, the load integral value (energy absorption) after the rise can be increased.

[0108] Incidentally, Figure 18 shows the graphs of the load fluctuations for each deformation stroke for each of the calculation models shown in Figures 20(a) to (c). Figure 18 also shows a similar trend to that in Figure 17. Furthermore, the load fluctuations for each deformation stroke were similarly calculated for each of the calculation models shown in Figures 21(a) and (b), and Figures 22(a) to (d). Then, for each case, the maximum load and the amount of energy absorbed at the same deformation stroke were determined. When calculating the amount of energy absorbed, the calculations were performed for both the case where the deformation stroke is 50 mm (EA[0,50]) and the case where it is 100 mm (EA[0,100]). Then, as will be described later, the results of each calculation model were compared with the results of the aforementioned standard model.

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

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3]

[0113] [Table 4]

[0114] Figures 19(d) to (f) show a comparison of the results in Table 1 as bar graphs. Specifically, Figure 19(d) is a comparison chart of the maximum load when the length L of the reinforcement part 40 is changed. Figures 19(e) and (f) are comparison charts of the amount of energy absorbed when the length L of the reinforcement part 40 is changed. Here, Figure 19(e) shows the amount of energy absorbed when the deformation stroke is between 0 and 50 mm, and Figure 19(f) shows the amount of energy absorbed when the deformation stroke is between 0 and 100 mm. The calculation models used in Figures 19(d) to (f) are, in order from the leftmost bar graph to the rightmost bar graph, the standard model in which the reinforcing part 40 is positioned at the center of the width of the top wall 11; a calculation model in which the length L of the reinforcing part 40 is 260 mm (side wall L260); a calculation model in which the length L of the reinforcing part 40 is 180 mm (side wall L180); and a calculation model in which the length L of the reinforcing part 40 is 90 mm (side wall L90).

[0115] Similarly, Figures 20(d) to (f) show a comparison of the results in Table 2 as bar graphs. Specifically, Figure 20(d) is a comparison chart of the maximum load when the width dimension w and position of the reinforcement part 40 are changed. Figures 20(e) and (f) are comparison charts of the energy absorption amount when the width dimension w and position of the reinforcement 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 in Figures 20(d) to (f) are, in order from the leftmost bar graph to the rightmost bar graph, the standard model in which the reinforcing part 40 is positioned at the center of the width of the top wall 11; a calculation model in which the width dimension w of the reinforcing part 40 is 20 mm (side wall w20); a calculation model in which the width dimension w of the reinforcing part 40 is 10 mm (side wall w10); and a calculation model in which the width dimension w of the reinforcing part 40 is 10 mm and it is positioned 10 mm below the end of the ridge (side wall w10-2).

[0116] Similarly, Figures 21(d) to (f) show a comparison of the results in Table 3 as bar graphs. Specifically, Figure 21(d) is a comparison chart of the maximum load when the width dimension w and position of the reinforcement part 40 are changed. Figures 21(e) and (f) are comparison charts of the energy absorption amount when the width dimension w and position of the reinforcement 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. The calculation models used are, in each of Figures 21(d) to (f), the standard model in which the reinforcing part 40 is placed at the center of the width of the top wall section 11, from the leftmost bar graph to the rightmost bar graph; the calculation model in which a reinforcing part 40 with a width w of 20 mm and a length of 260 mm is placed on each side wall section 12 (side wall L260); and the calculation model in which two reinforcing parts 40 with a width w of 20 mm and a length L of 260 mm are placed near the ridge section EL of the top wall section 11 (top wall ridge section side w20). The dashed lines in Figures 19(d)-(f), 20(d)-(f), 21(d)-(f), and 22(e)-(g) indicate the numerical values ​​of the aforementioned reference model used for comparison.

[0117] Finally, Figures 22(e) to (g) show a comparison of the results in Table 4 as bar graphs. Specifically, Figure 22(e) is a comparison of the maximum load when the reinforcing section 40 is positioned to overlap the ridge section EL. Figures 22(f) and (g) are comparison of the energy absorption when the reinforcing section 40 is positioned to overlap the ridge section EL. Here, Figure 22(f) shows the energy absorption when the deformation stroke is between 0 and 50 mm, and Figure 22(g) shows the energy absorption when the deformation stroke is between 0 and 100 mm. The calculation models used in Figures 22(e) to (g) are, in order from the leftmost bar graph to the rightmost bar graph, the standard model in which the reinforcing part 40 is placed at the center of the width of the top wall section 11; a calculation model in which the reinforcing part 40 is placed only on the ridge section EL (ridge section R section); a calculation model in which the reinforcing part 40 of the ridge section R section is further extended toward the top wall section 11 by a width of 10 mm (ridge section + top wall); a calculation model in which the reinforcing part 40 of the ridge section R section is further extended toward the side wall section 12 by a width of 10 mm (ridge section + side wall); and a calculation model in which the reinforcing part 40 of the ridge section R section is further extended toward both the top wall section 11 and the side wall section 12 by a width of 10 mm each (top wall ridge section side + side wall ridge section side w10mm).

[0118] The comparison results of each calculation model are described below. First, in Figures 19(d) to (f), calculation models other than the aforementioned standard model are considered examples of inventions. As shown in each bar graph, in all of the bar graphs corresponding to examples of inventions, the maximum load is kept lower than that of the comparison target, while still achieving a higher energy absorption amount than the standard model. Therefore, according to these examples of inventions, a high amount of collision energy absorption can be obtained with a short deformation stroke while suppressing rapid load fluctuations.

[0119] Figures 20(d) to (f) show two comparative examples: the standard model and a calculation model (side wall w10-2) in which the width dimension w of the reinforcing part 40 is 10 mm and it is positioned 10 mm below the end of the ridge. The other two cases are examples of inventions. As shown in each bar graph, in all of the examples of inventions, the maximum load is kept lower than that of the comparative examples, and a higher energy absorption amount than that of the standard model is achieved. Therefore, according to these examples of inventions, a high collision energy absorption amount can be obtained with a short deformation stroke while suppressing rapid load fluctuations. On the other hand, in the calculation models of the comparative examples shown in the bar graphs at the right end of Figures 20(e) and (f), a higher energy absorption amount is obtained with a long deformation stroke (deformation stroke of 100 mm) than that of the standard model, but with a short deformation stroke, the energy absorption amount is not much different from that of the standard model. From this result, it was confirmed that in order to obtain a high energy absorption amount with a short deformation stroke, it is effective to position the reinforcing part 40 adjacent to the ridge EL without moving it too far away.

[0120] In Figures 21(d) to (f) that follow, only the calculation model for "side wall L260" corresponds to the inventive example. As shown in each bar graph, only the calculation model for "side wall L260" succeeds in obtaining a higher energy absorption amount than the "standard" while keeping the maximum load lower than that of the standard model. Therefore, according to this inventive example, a high collision energy absorption amount can be obtained with a short deformation stroke while suppressing rapid load fluctuations.

[0121] In Figures 22(e) to (g) that follow, only the calculation model for the "ridge line + side wall" (the calculation model in Figure 22(c)) corresponds to the inventive example. As shown in Figure 22(e), when the maximum load is kept approximately constant, the highest energy absorption amount is successfully obtained, as shown in Figures 22(f) and (g). Therefore, according to this inventive example, a high collision energy absorption amount can be obtained with a short deformation stroke while suppressing rapid load fluctuations.

[0122] In the embodiment described above, we have illustrated a configuration in which the top wall portion 11 is bent inward as the bending deformation. However, the embodiment is not limited to this configuration. By appropriately adjusting the position of the bending starting point, a configuration in which the plate-like member 20 is bent inward as the bending deformation can also be adopted. This is also true for all embodiments described thereafter.

[0123] [Second Embodiment] The impact absorbing member absorbs impact force through folding deformation rather than bellows deformation. Hereafter, the area that undergoes folding deformation shown in Figure 1 will be denoted by reference numeral 101 and will be illustrated and described as the impact absorbing member 101. That is, in this second embodiment, in order to distinguish it from the configuration of the first embodiment described above, the reference numerals of the impact absorbing member will be changed from 1 to 101 and described thereafter. In this second embodiment, the case in which the folding initiation point 100BP of the folding deformation is set on the top wall portion 111 will be described as an example.

[0124] As shown in Figure 23, the impact absorbing member 101 of this second embodiment comprises a hollow tube 130 that is long in the longitudinal direction along its center line CL, and a reinforcement 140 fixedly arranged inside 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. For convenience of explanation, in the following description, the X direction in Figure 23 may be described 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 member 110 has a single top wall portion 111, a pair of side wall portions 112, and a pair of flange portions 113. The top wall portion 111 forms the hat apex of the hat-shaped member 110, which is hat-shaped when viewed along the center line CL. The top wall portion 111 is a long plate having a substantially constant width W and a substantially constant plate thickness T1, and is long along the center line CL. The top wall portion 111 has a flat top surface and a flat bottom surface. The width W can be exemplified as 30 mm to 100 mm. The plate thickness T1 can be exemplified as 0.8 mm to 3.2 mm. The plate thickness T1 values ​​exemplified here are for the case where steel is used as the material for the shock-absorbing member 101. When the shock-absorbing member 101 is manufactured from an aluminum extruded material, the upper limit of the plate thickness T1 can be exemplified as 4.0 mm. Furthermore, the width W and thickness T1 of the top wall portion 111 do not necessarily have to be constant at each position along the center line CL, and may be changed at each position along the center line CL as required for the component design. Similarly, the upper and lower surfaces of the top wall portion 111 do not necessarily have to be flat, and may have some irregularities as required for the component design.

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

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

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

[0129] The combination of the top wall portion 111, the left wall portion 112a, and the right wall portion 112b results in a roughly trapezoidal shape in the cross-section perpendicular to the center line CL. Furthermore, by combining the left flange portion 113a and the right flange portion 113b with this combination, a hat-shaped member 110 is constructed, in which the cross-section perpendicular to the longitudinal direction is hat-shaped. This hat-shaped member 110 is obtained by press-forming a die-cut sheet metal. The material of the hat-shaped member 110 is metal, and 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 along the center line CL, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used. The plate-shaped member 120 has a flat top surface and a flat bottom surface. The plate-shaped member 120 is welded to the left flange portion 113a and the right flange portion 113b at both side edges. This forms a closed cross section between the hat-shaped member 110 and the plate-shaped member 120. Furthermore, the width and thickness of the plate-like member 120 do not necessarily have to be constant at each position along 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 plate-like member 120 do not necessarily have to be flat, and may have some irregularities as required for the part design.

[0131] As shown in Figures 23 to 24B, the reinforcement 140 has a vertical plate 141, a horizontal plate 142, and a folding starter. The folding starter will be explained later using Figures 28 to 42. The vertical plate 141 is a single strip-shaped plate having a substantially constant width and substantially constant thickness, and is elongated in the direction along the center line CL. The vertical plate 141 has a flat left side and a flat right side. Although the vertical plate 141 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 a horizontal plate 142 that intersects it at the center position in the height direction. The upper and lower parts 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 substantially constant thickness, and is elongated in the direction along the center line CL. The horizontal plate 142 has a flat top surface and a flat bottom 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 appears to be divided into two by a vertical plate 141 that intersects it at the center 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 joining of the vertical plate 141 and the horizontal plate 142 can be done, for example, by welding. When viewed in a cross-section perpendicular to the longitudinal direction of the impact-absorbing member 101, the upper end (one end) of the vertical plate 141 is joined to the center of the width direction of the lower surface of the top wall portion 111, and the lower end is joined to the center of the width direction of the upper surface of the plate-shaped member 120. In this way, the top wall portion 111 is supported mainly by the vertical plate 141 and the plate-shaped member 120.

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

[0135] For the reinforcement 140, a high-strength steel plate with a tensile strength of 590 MPa or higher can be suitably used. That is, the reinforcement 140 can be manufactured by arranging vertical plates 141 and horizontal plates 142 made of the high-strength steel plate in a crisscross pattern and then welding them together. This reinforcement 140 is then fixed inside the hollow tube 130 by welding. In this embodiment, a reinforcement 140 with a "+" shape is used, but the reinforcement is not limited to this and other configurations may be used.

[0136] As shown in Figure 23, the reinforcing portion 240 has a left reinforcing portion 240a and a right reinforcing portion 240b. As shown in Figures 23 and 24A, the left reinforcing section 240a is a long, strip-shaped metal plate along the center line CL, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used as its material. The left reinforcing section 240a is fixed by welding at the longitudinal center of the left wall section 112a and adjacent to the ridge line section 100EL. The left reinforcing section 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 plate thickness of 0.8 mm to 3.2 mm. The plate thickness values ​​exemplified here are for the case where steel is used as the material for the impact absorbing member 101. When the impact absorbing member 101, including the left reinforcing section 240a, is manufactured from an aluminum extruded material, 4.0 mm can be exemplified as the upper limit of the plate thickness of the left reinforcing section 240a.

[0137] Similarly, the right reinforcing section 240b is a long, strip-shaped metal plate along the center line CL, and a high-strength steel plate with a tensile strength of 590 MPa or more can be suitably used as its material. The right reinforcing section 240b is fixed by welding at the longitudinal center of the right side wall section 112b and adjacent to the ridge line section 100EL. The right reinforcing section 240b has the same shape as the left reinforcing section 240a. That is, the right reinforcing section 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 plate thickness of 0.8 mm to 3.2 mm. The plate thickness values ​​exemplified here are for the case where steel is used as the material for the impact absorbing member 101. When the impact absorbing member 101, including the right reinforcing section 240b, is manufactured from an aluminum extruded material, 4.0 mm can be exemplified as the upper limit of the plate thickness of the right reinforcing section 240b. The length L of the left reinforcement section 240a and the length L of the right reinforcement section 240b are the same. The width w of the left reinforcement section 240a and the width w of the right reinforcement section 240b are also the same. The plate thickness of the left reinforcement section 240a and the plate thickness of the right reinforcement section 240b are also the same. The left reinforcement section 240a reinforces only the area near the ridge section 100EL of the left wall section 112a. Similarly, the right reinforcement section 240b reinforces only the area near the ridge section 100EL of the right wall section 112b. Therefore, the upper surface of the top wall section 111 and the upper surfaces of each ridge section 100EL are not reinforced. In other words, the left reinforcement section 240a and the right reinforcement section 240b reinforce only the areas near the ridge sections 100EL of the left wall section 112a and the right wall section 112b, avoiding the upper surface of the top wall section 111 and the pair of ridge sections 100EL.

[0138] Furthermore, as shown in Figure 24B, the left reinforcing portion 240a and the right reinforcing portion 240b may reinforce the hat-shaped member 110 while avoiding the upper surface of the top wall portion 111, and including the upper surface of the ridge portion 100EL. That is, the left reinforcing portion 240a may be joined by welding or the like to both the position near the ridge portion 100EL of the left wall portion 112a and the position overlapping the ridge portion 100EL. Similarly, the right reinforcing portion 240b may be joined by welding or the like to both the position near the ridge portion 100EL of the right wall portion 112b and the position overlapping the ridge portion 100EL. In this modified example, as shown in Figure 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] In the configuration shown in Figure 24B, the lengths L of the left reinforcement section 240a and the right reinforcement section 240b can both be set to 70mm to 500mm. On the other hand, the width dimension (total width dimension) of the left reinforcement section 240a and the right reinforcement section 240b only needs to be such that the width dimension w (partial width dimension) of the flat portion overlapping the left wall section 112a and the right wall section 112b is 10mm to 60mm, and the width dimension (partial width dimension) of the portion overlapping with the ridge section 100EL is arbitrary. However, it is necessary to set these left reinforcement section 240a and the right reinforcement section 240b so as not to overlap the top wall section 111.

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

[0141] One of the pair of ridge sections 100EL is a corner connecting the top wall section 111 and the left side wall section 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 sections 100EL is a corner connecting the top wall section 111 and the right side wall section 112b, and similarly has a predetermined radius of curvature.

[0142] The aforementioned bending trigger is configured to set a bending initiation point 100BP on the top wall portion 111 of the hollow tube 130 at one location along the longitudinal direction of the impact absorbing member 101. In other words, the bending trigger is configured to deform the hollow tube 130 so that the outer surface of the top wall portion 111 becomes locally concave at the bending initiation point 100BP of the top wall portion 111, and various configurations are possible. The bending trigger is provided on the reinforcement 140 rather than the hollow tube 130, and its details will be described in the explanation of Figures 28 to 42. When the impact absorbing member 101 deforms by bending at the bending initiation point 100BP, the absorption of impact energy is performed by energy absorption due to the bending deformation of the hollow tube 130 and energy absorption due to the bending deformation of the reinforcement 140. First, we will explain the energy absorption due to the bending deformation of the hollow tube 130 at the bending initiation point 100BP.

[0143] The bending initiation point 100BP in the hollow tube 130 is the area shown by hatching in Figure 23, and is included in the area where the impact absorbing member 101 undergoes buckling deformation and breaks when it receives impact energy in the -X direction. This bending initiation point 100BP is a part that is pre-set during the design phase to actively cause the start of bending deformation. In this embodiment, the impact absorbing member 101 is positioned such that the bending point 100BP is located midway along the longitudinal direction of the reinforcing portion 240. In other words, the left reinforcing portion 240a is positioned on the left side wall portion 112a such that the bending point 100BP is located midway along its longitudinal direction. Similarly, the right reinforcing portion 240b is positioned on the right side wall portion 112b such that the bending point 100BP is located midway along its longitudinal direction. It is preferable that the bending point 100BP be positioned at the center along the longitudinal direction of the left reinforcing portion 240a and the right reinforcing portion 240b. Furthermore, the length L of the left reinforcement section 240a and the right reinforcement section 240b along their respective extension directions is more than twice the buckling range length LB at the bending initiation point 100BP of the left wall section 112a and the right wall section 112b. This allows for high collision energy absorption with a short deformation stroke while suppressing rapid load fluctuations. The mechanism is explained below with reference to Figures 25 to 27.

[0144] Figure 25 is a diagram showing the process of the impact absorbing member 101 undergoing bending deformation under axial compressive bending load, and is a perspective view showing the bent state after the maximum load has occurred. Figure 26 is a diagram showing a continuation of the bending deformation process in Figure 25, and is a perspective view showing the state at the point when the secondary peak load rises. As shown in Figure 25, when the impact absorbing member 101 receives impact energy along its longitudinal direction, it deforms at the position of the bending initiation point 100BP, bending inward with the outer surface (upper surface) of the top wall portion 111. The absorption of impact energy during this bending deformation is performed at the bending initiation point 100BP by the deformation of the upper surface of the top wall portion 111 to indent, the deformation of the left wall portion 112a and the right wall portion 112b bending in an "L" shape toward each other, and the deformation of the left reinforcing portion 240a and the right reinforcing portion 240b bending in an "L" shape toward each other. At the bending initiation point 100BP at this time, mainly compressive deformation occurs at the positions of the top wall portion 111, the left wall portion 112a, and the right wall portion 112b. On the other hand, tensile deformation occurs at the left reinforcing portion 240a and the right reinforcing portion 240b. Impact energy is absorbed by these compressive and tensile deformations.

[0145] The maximum load on the impact absorbing member 101 when collision energy is applied increases with the structural strength of the top wall portion 111. If the maximum load is too high, the rate at which the load drops due to bending deformation after the maximum load occurs will also be abrupt. In vehicles 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 portion 100EL and extending along the direction of extension of each ridge portion 100EL. In other words, since these left reinforcing portions 240a and the right reinforcing portion 240b do not reinforce the top wall portion 111, the maximum load of the impact-absorbing member 101 does not need to be excessively increased.

[0146] On the other hand, as described above, the collision energy is absorbed not only by the bending deformation of the top wall 111, but also by the buckling deformation of the left wall 112a and the right wall 112b into an "L" shape at the bending initiation point 100BP. At this time, the left wall 112a and the right wall 112b are less likely to bend into an "L" shape due to the reinforcement by the left reinforcing part 240a and the right reinforcing part 240b. Therefore, the drop in load after the occurrence of the maximum load in the maximum load-deformation stroke diagram (hereinafter referred to as the FS diagram) can be made gentler. As a result, the maximum load value in the FS diagram can be suppressed while increasing the load integral value after the occurrence of the maximum load. Thus, the amount of energy absorbed can be increased.

[0147] Furthermore, it is possible to accelerate the rise time of the secondary peak load in the FS diagram. To explain this, first, the parts of the left reinforcement section 240a and the right reinforcement section 240b that were bent into an "L" shape due to buckling deformation gradually close. As a result of the "L" shape being completely closed, the two straight sections on either side of the "L" shape in the ridge section 100EL come into contact with each other, resulting in the state shown in Figure 26. This contact between the two straight sections in the ridge section 100EL causes the rise of the secondary peak load.

[0148] Figure 27 shows the deformation of the ridge portion 100EL during the bending deformation process described above. Figure 27 is a diagram illustrating the bending deformation process and is a schematic plan view of portion B of the ridge portion 100EL of the impact absorbing member 101 in Figure 25, including the bending initiation point 100BP and its surrounding portion. In Figure 27, the solid line shows the ridge portion 100EL of the impact absorbing member 101 of this embodiment, and the dashed line shows the ridge portion 100EL' in a conventional structure without the reinforcing portion 240.

[0149] In the ridge section 100EL' shown by the dashed line, the side wall section 112 (left wall section 112a and right wall section 112b) is not reinforced by the reinforcing section 240 (left reinforcing section 240a and right reinforcing section 240b), so the "L" shape that occurs in the buckling range is also larger. On the other hand, in the impact-absorbing member 101 of this embodiment, the upper edge of the left wall portion 112a is reinforced by the left reinforcing portion 240a, and the upper edge of the right wall 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 ridge portions 100EL is substantially reinforced. Therefore, as shown in Figure 27, the deformation area of ​​the ridge portion 100EL is localized compared to the ridge portion 100EL', and the "L" shape becomes smaller. As a result, interference between the pair of straight portions of the ridge portion 100EL begins earlier. Thus, the rise of the secondary peak load is accelerated.

[0150] Furthermore, in the impact absorbing member 101 of this embodiment, each side wall portion 112 (left wall portion 112a and right wall portion 112b) is reinforced by each reinforcing portion 240 (left reinforcing portion 240a and right reinforcing portion 240b), so that the two straight portions of the ridge portion 100EL can continue to strongly abut 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, thus increasing the amount of energy absorbed.

[0151] As described above, in the impact absorbing member 101 of this embodiment, the lengths L of the left reinforcing portion 240a and the right reinforcing portion 240b are set to be at least twice the buckling range length LB shown in Figure 23. The buckling range length LB here refers to the maximum length dimension in the direction along the center line CL of the range in which buckling deformation occurs during bending deformation. This maximum value can be set in advance by performing numerical calculations during the design stage, or by manufacturing sample materials and conducting load tests. By making the length L of the left reinforcement section 240a and the right reinforcement section 240b at least twice the length LB of the buckling range, as shown in Figure 26, when the buckling range is completely buckled, a pair of straight sections of each ridge section 100EL that are connected with the buckling range in between can more reliably abut against each other. Therefore, it is preferable to make the length L at least twice the length LB.

[0152] Next, referring to Figures 28 to 42, the bending trigger provided in the reinforcement 140 and the energy absorption due to bending deformation at the bending initiation point 100BP set by this bending trigger will be explained below. Figure 28 is a perspective view showing an example of a bending point provided in the reinforcement 140, with the hollow tube 130 not shown. In this example of the reinforcement 140, one through-hole 251 is formed at the center of the longitudinal direction of the vertical plate 141 and at the upper part in the height direction. More specifically, the through-hole 251 is formed at a position between the center in the height direction 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; an ellipse, square, polygon, or other shape may be used instead. Also, although only one through-hole 251 is formed, there may be two or three or more. Furthermore, if multiple through-holes are used, their shapes and sizes may be different from each other.

[0153] The through-hole 251 may be formed on the horizontal plate 142 instead of the vertical plate 141. In this case, it is preferable that the through-hole 251 be formed at the center of the horizontal plate 142 in the longitudinal direction, with one on each side of the vertical plate 141, on the left and right sides. Furthermore, it is preferable that the through-hole 251 on the left side and the through-hole 251 on the right side have the same shape and size. This makes the bending strength on the left and right sides of the center line CL of the impact absorbing member 101 equal, allowing for precise control of the bending direction so that the upper surface of the top wall portion 111 is on the inside of the bend. In the case where the through-holes 251 are formed on the horizontal plate 142, two are formed, but an even number of two or more may also be formed. In this case as well, it is preferable that the through-holes 251 on the left portion and the through-holes 251 on the right portion are the same size and number. Furthermore, through-holes 251 may be formed in both the vertical plate 141 and the horizontal plate 142, as described above.

[0154] Figure 29 is a perspective view showing another example of a bending point provided in the reinforcement 140, with the hollow tube 130 not shown. In this example of the reinforcement 140, one through-hole 252 is formed at the center of the longitudinal direction of the vertical plate 141 and at the upper end in the height direction. More specifically, the through-hole 252 is a notch formed in the upper edge of the vertical plate 141 and has a semicircular shape. The shape of the through-hole 252 is not limited to a semicircle; a semi-ellipse, square, polygon, or other shape may be used instead. Furthermore, although only one through-hole 252 is formed, two or three or more may be used. Also, if multiple through-holes 252 are formed, their shapes and sizes may differ from each other.

[0155] The through-hole 252 may be formed on the horizontal plate 142 instead of the vertical plate 141. In this case, it is preferable that the through-hole 252 be formed at the center of the longitudinal direction of the horizontal plate 142, with one on the left and one on the right side, with the vertical plate 141 in between. It is also preferable that the through-hole 252 on the left side and the through-hole 252 on the right side have the same shape and size. In this case, as in the example shown in Figure 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, so the bending direction can be controlled with precision so that the upper surface of the top wall portion 111 is on the inside of the bend. In the case where the through-holes 252 are formed on the horizontal plate 142, two are formed, but an even number of two or more may be formed. In this case as well, it is preferable that the through-holes 252 on the left and the through-holes 252 on the right are the same size and number. Furthermore, through-holes 252 may be formed in both the vertical plate 141 and the horizontal plate 142, as described above.

[0156] Next, Figure 30 is a perspective view showing yet another example of the reinforcement 140 provided on the impact absorbing member 101. In the reinforcement 140 of this example, a long bead 253 is formed along a direction intersecting the longitudinal direction of the impact absorbing member 101 (the direction in which the center line CL extends) at the longitudinal center of the vertical plate 141 and at the upper part in the height direction. More specifically, the bead 253 is formed in a straight line from the height center of the vertical plate 141 to the upper end of the vertical plate 141. When viewing the side of the vertical plate 141 from the front, the intersection angle of the bead 253 with respect to the center line CL is preferably a right angle, but it may be slightly inclined. Also, although the number of beads 253 is shown as one, there may be two or more. Furthermore, when there are multiple beads 253, their thickness and length may be different from each other. Also, when there are multiple beads 253, it is preferable to arrange them in close proximity to each other.

[0157] The bead 253 may be formed on the horizontal plate 142 instead of the vertical plate 141. In this case, it is preferable that the bead 253 be formed at the center of the horizontal plate 142 in the longitudinal direction, with one bead each on the left and right sides, with the vertical plate 141 in between. Furthermore, it is preferable that the left bead 253 and the right bead 253 are coaxial with each other and formed along a direction intersecting the longitudinal direction of the shock absorbing member 101 (the direction in which the center line CL extends). It is also preferable that the left bead 253 and the right bead 253 have the same length and thickness. In this case, similar to the example shown in Figure 28, the bending strength on the left and right sides of the shock absorbing member 101 with respect to the center line CL can be made equal, so that the bending direction with respect to the upper surface of the top wall portion 111 on the inside of the bend can be controlled with precision. The number of beads 253 is set to one pair (2), but there may be more than two. Also, if there are multiple beads 253, their thickness and length may be different from each other. However, if there are multiple beads 253, it is preferable to arrange them symmetrically on both sides of the center line CL.

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

[0159] Figure 31 is a perspective view showing yet another example of a reinforcement 140 provided on the impact absorbing member 101. In this example of the reinforcement 140, a long bead (rigid portion) 254 is formed on the first portion 100R1 of the upper part of the vertical plate 141, along the longitudinal direction of the impact absorbing member 101 (the direction in which the center line CL extends). Similarly, a long bead (rigid portion) 254 is also formed on the second portion 100R2 of the upper part of the vertical plate 141, along the longitudinal direction of the impact absorbing member 101 (the direction in which the center line CL extends). These pairs of beads 254 are positioned at the same height and along the same straight line. On the other hand, the second section 100R2 of the upper part of the vertical plate 141 does not have a bead 254 formed on it and remains flat. Therefore, of the first section 100R1, second section 100R2, and third section 100R3, the upper part of the vertical plate 141 is reinforced except for the second section 100R2 which is in the center. The number of beads 254 is set to one pair (2), but there may be more than two. Also, if there are multiple beads 254, their thickness and length may be different from each other. However, if there are multiple beads 254, it is preferable to arrange them symmetrically between the first part 100R1 and the third part 100R3.

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

[0161] Furthermore, in both the first section 100R1 and the third section 100R3, it is preferable that the left bead 254 and the right bead 254 have the same length and thickness. In this case, similar to the example shown in Figure 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, so that the bending direction with the upper surface of the top wall section 111 facing inward can be controlled with high precision. The number of beads 254 is set to one pair (2 beads) in both the first section 100R1 and the third section 100R3, but it may be two pairs or more in each section. Also, when there are multiple beads 254, their thickness and length may be different from each other. However, when there are multiple beads 254, it is preferable to arrange them symmetrically on both sides with respect to the center line CL. On the other hand, the second section 100R2 of the transverse plate 142 does not have a bead 254 formed on it and remains flat. Therefore, of the first section 100R1, second section 100R2, and third section 100R3, the transverse plate 142 is reinforced except for the second section 100R2 in the center. And of the reinforcement 140, the unreinforced second section 100R2 functions as the trigger for breaking.

[0162] Figure 32 is a perspective view showing yet another example of a reinforcement 140 provided on the impact absorbing member 101. In this example of the reinforcement 140, a long angle member 255 is welded to a first portion 100R1 of the upper part of the vertical plate 141, along the longitudinal direction of the impact absorbing member 101 (the direction in which the center line CL extends). Similarly, a long angle member 255 is welded to a third portion 100R3 of the upper part of the vertical plate 141, along the longitudinal direction of the impact absorbing member 101 (the direction in which the center line CL extends). These pairs of angle members 255 are positioned at the same height and along the same straight line. Each angle member 255 is welded so that its flat surface (outer surface) is face-jointed to the upper side surface of the vertical plate 141. On the other hand, the angle material 255 is not fixed to the second section 100R2 of the upper part of the vertical plate 141, and it remains flat. Therefore, of the first section 100R1, second section 100R2, and third section 100R3, the upper part of the vertical plate 141 is reinforced except for the second section 100R2 which is in the center. The number of angle members 255 is set to one pair (2 pieces), but more than two pieces may be used. Also, when using multiple angle members 255, their thickness and length may be different from each other. However, when using multiple angle members 255, it is preferable to arrange them symmetrically between the first section 100R1 and the third section 100R3.

[0163] As shown in Figure 33, the angle members 255 may be fixed to the horizontal plate 142 instead of the vertical plate 141. In that case, the fixing positions will be 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 member 255 is welded to each of the left and right portions, with the vertical plate 141 in between. In addition, at the third portion 100R3 of the horizontal plate 142, one angle member 255 is welded to each of the left and right portions, with the vertical plate 141 in between. On the left side of the horizontal plate 142, it is preferable that the angle members 255 at the first portion 100R1 and the angle members 255 at the third portion 100R3 are coaxial with each other and arranged along the longitudinal direction of the impact absorbing member 101 (the direction of extension of the center line CL). Similarly, in the right portion of the horizontal plate 142, it is preferable that the angle material 255 at the first portion 100R1 and the angle material 255 at the third portion 100R3 are coaxial with each other and arranged along the longitudinal direction of the impact absorbing member 101 (the direction of extension of the center line CL).

[0164] Furthermore, in both the first section 100R1 and the third section 100R3, it is preferable that the angle material 255 on the left and the angle material 255 on the right have the same length and thickness. In this case, as in the example shown in Figure 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, so that the bending direction with the upper surface of the top wall section 111 on the inside of the bend can be controlled with precision. The number of angle members 255 is set to one pair (2 pieces) in both the first section 100R1 and the third section 100R3, but it may be two pairs or more in each section. Also, when using multiple angle members 255, their thickness and length may be different from each other. However, when using multiple angle members 255, it is preferable to arrange them symmetrically on both sides with respect to the center line CL. On the other hand, the angle material 255 is not fixed to the second section 100R2 of the horizontal plate 142, and it remains in a flat shape. Therefore, of the first section 100R1, second section 100R2, and third section 100R3, the horizontal plate 142 is reinforced except for the second section 100R2 in the center. And of the reinforcement 140, the unreinforced second section 100R2 functions as the trigger for breaking.

[0165] Figure 34 is a perspective view showing yet another example of the reinforcement 140 provided on the impact absorbing member 101, with the hatched area indicating the point of fold. In this example, the lower portion of the vertical plate 141 shown in Figure 34 has the same plate thickness at each position along its longitudinal direction. On the other hand, in the upper portion of the vertical plate 141, at least a part of the thickness of the second portion 100R2 is thinner than the thickness of the first portion 100R1 and the third portion 100R3. That is, in the upper portion of the vertical plate 141, the rectangular region in the second portion 100R2 has a thinner plate thickness than the surrounding region, which serves as the point of fold. This bending point can be formed, for example, by using a tailor-welded blank (TWB), which consists of a plate material with a recess formed in the center of its upper end so that it is roughly U-shaped when viewed from the side, and a plate material that is joined within this recess and has a thinner thickness than the one it is joined to, and then joining these by welding to form a single vertical plate 141. In addition, a vertical plate 141 having a bending point 100BP can also be formed using a tailor-rolled blank (TRB).

[0166] In the configuration shown in Figure 34 above, the width dimension Wr1 of the folding starter was made equal to the height dimension of the upper part of the vertical plate 141. That is, the entire width dimension Wr2 of the vertical plate 141 between the center position in the width direction through which the center line CL of the reinforcement 140 passes and the upper edge position which is the connection position with the top wall 111 was made into a folding starter with a thin plate thickness. However, the configuration is not limited to this form, and as shown in the present example in Figure 35, the folding starter may be formed at a hatched position that includes the upper edge of the vertical plate 141 and is 1 / 3 of the width of the upper part of the vertical plate 141. More specifically, the width dimensions Wr1 and Wr2 may satisfy Wr2≧Wr1>(1 / 3)×Wr2. In both Figure 34 and Figure 35, it is preferable that the folding starter is positioned so that it divides the upper edge of the vertical plate 141 at the position of the second part 100R2 by including the upper edge of the vertical plate 141.

[0167] Figure 36 is a perspective view showing yet another example of the reinforcement 140 provided on the impact absorbing member 101. As in this example, the formation position of the bending point may be on the horizontal plate 142 instead of the vertical plate 141. In that case, as shown by the hatching, it is preferable that one bending point is formed in the center of the longitudinal direction of the horizontal plate 142, with the vertical plate 141 in between, on both the left and right sides. Furthermore, it is preferable that the bending points on the left and right sides are the same shape and size (same width, same length, same plate thickness). This makes the bending strength on the left and right sides of the center line CL of the impact absorbing member 101 equal, so that the bending direction with the upper surface of the top wall portion 111 on the inside of the bend can be controlled with precision. In this example, two fold markers are formed on the horizontal plate 142, but the total number may be two or more, or an even number. In this case as well, it is preferable that the fold markers on the left and right portions are the same size and number. Furthermore, as described above, folding points may be formed on both the vertical plate 141 and the horizontal plate 142.

[0168] In the configuration shown in Figure 36 above, the width dimension Wr1 of the folding starter was made 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 central position through which the center line CL of the reinforcement 140 passes and the side edge position which is the connection point with the left wall portion 112a or the right wall portion 112b was made into a thin folding starter. However, the configuration is not limited to this form, and for example, as shown in the hatched area of ​​Figure 37, the folding starter 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 includes the side edge of the horizontal plate 142. More specifically, the width dimension Wr1 (mm) and the width dimension Wr2 (mm) may satisfy Wr2 ≥ Wr1 > (1 / 3) × Wr2. In both Figure 36 and Figure 37, it is preferable that each folding starter is positioned such that it divides the side edges of the horizontal plate 142 at the position of the second portion 100R2, by including the side edges of the horizontal plate 142.

[0169] The configurations shown in Figure 34 or 35 described above may be combined with the configurations shown in Figure 36 or 37. That is, a folding starter may be formed at the position of the second part 100R2 on both the vertical plate 141 and the horizontal plate 142. In this case, the width dimension Wr1 of the folding starter formed on the vertical plate 141 may be equal to the width dimension Wr1 of the folding starter formed on the horizontal plate 142, or they may be different.

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

[0171] Furthermore, while Figures 22 to 37, described above, illustrate reinforcements with a cross-sectional shape perpendicular to the longitudinal direction resembling a "+" sign, other reinforcements with shapes like those shown in Case 001, Case 002, and Case 004 of Figure 43, which will be described later, may also be used. For example, the reinforcement shown in Case 004 has a cross-sectional shape in which one vertical plate 141, half the height of one horizontal plate 142, is joined between the center of the horizontal plate 142 in the width direction and the top wall portion 111. These vertical plate 141 and horizontal plate 142 are provided with a bending point at the position of the second portion 100R2 shown in Figure 23.

[0172] Figures 38 to 40 show yet another example of the reinforcement 140 provided on the impact absorbing member 101. In this example, the reinforcement 140 is provided only on the second part 100R2, and a filler material 256 is provided on the first part 100R1 and the third part 100R3, respectively. As shown in Figures 38 and 40, the filler material 256 completely fills the internal space of the first section 100R1 without any gaps. The other filler material 256 also completely fills the internal space of the third section 100R3 without any gaps. Therefore, these pair of filler materials 256 are arranged with the reinforcement 140 in between them. That is, inside the hollow tube 130, along its longitudinal direction, one of the pair of filler materials 256, the reinforcement 140, and the other of the pair of filler materials 256 are fixedly arranged in this order without any gaps. Therefore, only the filler material 256 is provided inside the first section 100R1 and the third section 100R3 of the hollow tube 130, and only the reinforcement 140 is provided inside the second section 100R2.

[0173] The filler 256 is a resin material, and specific examples of materials include epoxy or urethane. Since 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 partitioned by the top wall portion 111, the pair of side wall portions 112, and the plate-like member 120. Therefore, the filler 256 can be flexibly positioned according to the internal shape of the hollow tube. In this example, the hollow tube 130 has a trapezoidal internal space with a cross-section perpendicular to its length, so the filler 256 also has a trapezoidal cross-sectional shape. While it is most preferable for each filler material 256 to fill the entire internal space of the first section 100R1 and the entire internal space of the third section 100R3, as in this example, it is sufficient for at least the upper internal space, including the inner surface (bottom surface) of the top wall section 111, to be filled, and the lower space does not need to be filled with each filler material 256. Specific examples will be given in the explanation of Figures 41 and 42 later.

[0174] In this way, by reinforcing the upper internal space, including at least the inner surface (bottom surface) of the top wall portion 111, with the filler material 256, out-of-plane deformation of the first portion 100R1 and the third portion 100R3, particularly the top wall portion 111, is suppressed. Since the bending initiation point 100BP when the hollow tube 130 bends is set on the outer surface of the top wall portion 111, reinforcing only the first portion 100R1 and the third portion 100R3 with the filler material 256 and not reinforcing the second portion 100R2 with the filler material 256 effectively provides 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, the filler material 256 may be prepared in pairs by being pre-molded and then placed one in each of the first part 100R1 and the third part 100R3 and bonded together. Or, the filler material 256 may be formed by filling each of the first part 100R1 and the third part 100R3 with a fluid resin material and allowing it to harden.

[0175] In this example, the reinforcement 140 is sandwiched between the pair of fillers 256 described above, thereby setting a bending point at the second section 100R2 where the reinforcement 140 is located. In this impact absorbing member 101, the upper surface of the top wall 111 is set to be on the inside of the bend when it breaks at the second section 100R2, which is the center position in the longitudinal direction. This setting is mainly achieved by the way the impact absorbing member 101 is arranged inside the vehicle. The way the impact absorbing member 101 is arranged inside the vehicle can be achieved by shifting the point of application of the impact load to a side closer to the top wall 111 than the center line CL.

[0176] As a configuration in which the filler 256 is used in combination with the reinforcement 140, the modified configurations shown in Figures 41 and 42 can also be adopted instead of the configuration described above. In these modified configurations, the configurations of the reinforcement 140 and the filler 256 differ particularly from the example above, so the differences will be explained below, while other configurations are the same and will not be explained.

[0177] The reinforcement 140 in this modified example does not have the vertical plate 141 described above, but is composed of only one horizontal plate 142. Moreover, this horizontal plate 142 has a length that extends not only to the second portion 100R2 but also to the first portion 100R1 and the third portion 100R3. In addition, flanges are formed on both side edges of the horizontal plate 142, one of which is welded to the inner surface of the left wall portion 112a, and the other is welded to the inner surface of the right wall portion 112b. The horizontal plate 142 is positioned at the same height as the center line CL of the hollow tube 130 and is arranged coaxially with the center line CL. In this configuration, the distance between the pair of side wall sections 112 is constrained by the horizontal plate 142. This constraint prevents the top wall section 111 from sinking in a way that pushes the space between the pair of side wall sections 112 apart, thus indirectly supporting the top wall section 111. Therefore, in this case as well, the second portion 100R2 of the hollow tube 130 is supported from the inside by the reinforcement 140.

[0178] Furthermore, in this modified example, although the filler material 256 is placed in the first section 100R1 and the third section 100R3, when viewed in a cross section perpendicular to the longitudinal direction of the hollow tube 130 (Figure 42), it is placed only above the horizontal plate 142. That is, in each of the first section 100R1 and the third section 100R3, the filler material 256 is placed in a closed space partitioned by the top wall section 111, a pair of side wall sections 112, and the horizontal plate 142. On the other hand, in the second section 100R2, the filler material 256 is not placed in a closed space partitioned by the pair of side wall sections 112, the horizontal plate 142, and the plate-like member 120, and the space remains open. In this configuration as well, it is possible to suppress out-of-plane deformation of the top wall portion 111, particularly at the first section 100R1 and the third section 100R3. Furthermore, by the presence or absence of the filler material 256, the degree of reinforcement against bending deformation of the impact absorbing member 101 is made relatively higher at the first section 100R1 and the third section 100R3 than at the second section 100R2. As a result, the top wall portion 111 of the second section 100R2 can be bent smoothly starting from the outer surface.

[0179] The embodiments and their modifications described above may be modified in various ways without departing from the spirit of the present invention. For example, the left reinforcement section 240a and the right reinforcement section 240b are constructed from strip-shaped plate material, but the configuration is not limited to this. The reinforcement section 240 only needs to partially reinforce the same position and shape range as the left reinforcement section 240a and the right reinforcement section 240b. Examples of means of this reinforcement include patchwork, tailored weld blanks, weld beads, and heat treatment. Furthermore, each of the configurations described using Figures 28 to 42 may be adopted individually or in combination. For example, the through-hole 251, the through-hole 252, the bead 253, the bead 254, and the angle material 255 may be combined, as long as they do not interfere with each other in terms of arrangement.

[0180] The main features of the impact-absorbing member 101 of the second embodiment described above are summarized below. (1) As shown in Figure 23, etc., one aspect of the present invention comprises a hollow tube 130 that is long in one direction and a reinforcement 140 fixedly arranged inside the hollow tube 130, wherein the hollow tube 130, when viewed in a cross section perpendicular to the longitudinal direction which is the one direction, has a top wall portion (bent inner wall portion) 111 and a pair of side wall portions 112 connected to the top wall portion 111 via a pair of ridge portions 100EL, in an impact absorbing member 101, the reinforcement 140 is located on the top wall portion 111 The hollow tube 130 has at least one of a vertical plate 141 joined at one end and a horizontal plate 142 connecting a pair of side wall portions 112, and a bending starter configured to set a bending start point 100BP on the top wall portion 111 of the hollow tube 130 at an intermediate position in the longitudinal direction; the hollow tube 130 has a pair of reinforcing portions 240 fixedly positioned adjacent to each side wall portion 112, extending along the extending direction of each ridge portion 100EL.

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

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

[0183] (6) As shown in Figure 24B, the impact absorbing member 101 described in any one of the above items (1) to (3) may be provided only in the area where each reinforcing portion 240 overlaps with each side wall portion 112 to each ridge portion 100EL when viewed in a cross section perpendicular to the longitudinal direction. (7) As shown in Figure 23, the shock-absorbing member 101 described in (6) above may have the following configuration: a hollow tube 130 comprising a hat-shaped member 110 having a top wall portion 111 which is the inner wall portion of the bend and side wall portions 112 connected to both sides of the top wall portion 111 via each ridge portion 100EL, and a plate-shaped member 120 joined to the hat-shaped member 110 to form a closed cross section; and a height dimension H between the top wall portion 111 and the plate-shaped member 120 is 50m The length is m to 200 mm, the width 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 w of the portion that overlaps with 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 items (1) to (7) above may adopt 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; the bending starter has at least one of a through portion 251 provided in the second portion 100R2 or a bead 253 formed to be long in a direction intersecting the longitudinal direction, and a bead 254 arranged in the first portion 100R1 and the third portion 100R3 respectively 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 the above items (1) to (7) may adopt 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; the bending point is formed in the second portion 100R2 of the reinforcement 140 including the connection point with the hollow tube 130, and has a plate 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, at least one of these.

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

[0187] An embodiment corresponding to the second embodiment described above will be explained below using Figures 43 to 46. In this embodiment, the maximum load and energy absorption amount were determined by numerical calculation when collision energy was applied to multiple impact absorbing members with different reinforcement conditions.

[0188] Specifically, six types of impact-absorbing members having various cross-sectional shapes as shown in Figure 43 were prepared. Figure 43 is a cross-sectional view of the impact-absorbing member along the FF line in Figure 23. Of these, Case 000 shows a comparative example consisting only of a hollow tube 130 without the reinforcement 140 and reinforcing part 240. Case 005 also shows a comparative example that lacks the reinforcement 140 and reinforcing part 240 and has a different method of reinforcement. Case 001 shows an example of the invention in which only one horizontal plate 142 is provided as the reinforcement 140. This horizontal plate 142 is provided with a bending point at the position of the second part 100R2 shown in Figure 23. Case 002 shows an example of the invention in which only one vertical plate 141 is provided as the reinforcement 140. This vertical plate 141 is provided with a bending point at the position of the second part 100R2 shown in Figure 23. Case 003 is an example of the invention in which one horizontal plate 142 and one vertical plate 141 intersect in a "+" shape as the reinforcement 140, and is the same configuration as illustrated in Figure 23. These vertical plate 141 and horizontal plate 142 are provided with a bending point at the position of the second part 100R2 shown in Figure 23. Case 004 is an example of the invention in which a vertical plate 141, half the height of a horizontal plate 142, is joined between the center of the horizontal plate 142 in the width direction and the top wall portion 111. These vertical plates 141 and horizontal plates 142 are provided with a folding starter at the position of the second portion 100R2 shown in Figure 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, as shown in Figure 44(a), both ends were held to rotate freely around the horizontal axis, 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. The displacement of the applied load F was then measured. At this time, the impact energy was applied after offsetting the position of the center line of the impact absorbing member in the height direction relative to the input position of the impact energy. More specifically, the application position of the load F was shifted 23 mm from the center line of the impact absorbing member towards the top wall portion 111 and applied horizontally. As a result, the member was deformed from the state shown in Figure 44(a), before bending deformation, to the state shown in Figure 44(b), after bending deformation, with the top wall portion 111 as the bending initiation point.

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

[0191] [Table 5]

[0192] As shown in Fig. 46, in Case001 to Case004 belonging to the inventive examples, higher energy absorption amounts were obtained compared to Case000 without reinforcement. The same is true for Case005 which is a comparative example. However, as shown in Table 5, there was a significant increase in weight compared to Case000. On the other hand, in Case001 to Case004 belonging to the inventive examples, the weight increase relative to Case000 was suppressed to a small value. Therefore, in Case001 to Case004 belonging to the inventive examples, it is possible to reduce the weight of the entire part by thinning the plate thickness or shortening the deformation stroke until the same energy absorption amount as Case000 is achieved. Thus, it was confirmed that with the configuration of the inventive example, it is lightweight and can be bent and deformed at joints to exhibit high energy absorption efficiency.

Industrial Applicability

[0193] According to the impact absorbing member according to each of the above aspects of the present invention, while suppressing rapid load fluctuations, a high impact energy absorption amount can be obtained with a short deformation stroke. Therefore, the industrial applicability is great.

Explanation of Signs

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

Claims

1. It has a long hollow tube running in one direction, The hollow tube, when viewed in a cross-section perpendicular to the longitudinal direction which is one direction, has 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. In impact absorbing members, A bending starter is provided in the hollow tube and configured to set a bending start point on the inner wall of the bend at an intermediate position in the longitudinal direction of the hollow tube; The hollow tube extends along the direction of extension of each of the aforementioned ridges, and is provided with a pair of reinforcing parts adjacent to each of the aforementioned ridges on the outer surface of each of the aforementioned side walls when viewed in a cross section perpendicular to the longitudinal direction at the position of the bending point; Equipped with A shock-absorbing member characterized by the following features.

2. It comprises a long hollow tube running in one direction, and a reinforcement fixedly positioned inside the hollow tube, The hollow tube, when viewed in a cross-section perpendicular to the longitudinal direction which is one direction, has 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. In impact absorbing members, The aforementioned reinforcement, At least one of the vertical plate, one end of which is joined to the inner wall portion of the bend, and the horizontal plate connecting the pair of side wall portions, A bending point is configured to set a bending starting point on the inner wall of the hollow tube at an intermediate position in the longitudinal direction. Having; The hollow tube has a pair of reinforcing portions fixedly positioned adjacent to each of the side walls, extending along the direction of extension of each of the ridge portions; A shock-absorbing member characterized by the following features.

3. Each of the reinforcing parts is joined to at least each of the side walls and is a long, strip-shaped plate material along the extending direction. The impact absorbing member according to feature 1 or 2.

4. The average length of each reinforcing portion along its extending direction is at least twice the buckling range length of each side wall portion at the location of the bending point. The impact absorbing member according to feature 1 or 2.

5. Each of the aforementioned reinforcing portions is provided only on the respective side wall portions when viewed in a cross section perpendicular to the longitudinal direction. The impact absorbing member according to feature 1 or 2.

6. The aforementioned hollow tube A hat-shaped member having a top wall portion which is the inner wall portion of the bend and the side wall portions which are connected to both sides of the top wall portion via the respective ridge portions, A plate-shaped member joined to the hat-shaped member to form a closed cross-section, Equipped with; The height dimension H between the top wall and the plate-like member is 50 mm to 200 mm, the width dimension W of the top wall 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; Each of the aforementioned reinforcing portions has a length L along the extending direction of 70 mm to 500 mm, and a width w in a cross-section perpendicular to the longitudinal direction of 10 mm to 60 mm. The impact absorbing member according to feature 4.

7. Each of the aforementioned reinforcing portions is provided only in the area that overlaps with each of the side walls and each of the ridges when viewed in a cross section perpendicular to the longitudinal direction. The impact absorbing member according to feature 1 or 2.

8. The aforementioned hollow tube A hat-shaped member having a top wall portion which is the inner wall portion of the bend and the side wall portions which are connected to both sides of the top wall portion via the respective ridge portions, A plate-shaped member joined to the hat-shaped member to form a closed cross-section, Equipped with; The height dimension H between the top wall and the plate-like member is 50 mm to 200 mm, the width dimension W of the top wall 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; Each of the aforementioned reinforcing portions has a length L along the extending direction of 70 mm to 500 mm, and the width dimension w of the portion overlapping each side wall when viewed in a cross section perpendicular to the longitudinal direction is 10 mm to 60 mm. The shock-absorbing member according to feature 7.

9. The aforementioned break starter includes a first bead provided on the pair of ridges of the hollow tube and at the position of the break start point. The impact absorbing member according to feature 1.

10. The aforementioned bending trigger is provided at the position of the bending initiation point on the inner wall portion of the bend and includes a second bead that is elongated in a direction intersecting the longitudinal direction. The impact absorbing member according to feature 1.

11. The aforementioned bending trigger includes a through hole provided at the position of the bending initiation point of the inner wall portion of the bend. The impact absorbing member according to feature 1.

12. When the hollow tube is viewed along its longitudinal direction, and the portion including the bending point is designated as the second portion, one side of the second portion as the first portion, and the other side of the second portion as the third portion, The aforementioned break starter is provided in each of the first and third portions and includes a third bead that is long along the longitudinal direction. The impact absorbing member according to feature 1.

13. When the hollow tube is viewed along its longitudinal direction, and the portion including the bending point is designated as the second portion, one side of the second portion as the first portion, and the other side of the second portion as the third portion, The aforementioned fracture trigger includes at least one of the difference in plate thickness and the difference in material strength provided between the second portion and the first and third portions. The impact absorbing member according to feature 1.

14. The aforementioned bending point includes a bend in the hollow tube such that the outer surface of the inner wall portion of the bend is concave at the position of the bending initiation point. The impact absorbing member according to feature 1.

15. When the hollow tube is viewed along its longitudinal direction, and the portion including the bending point is designated as the second portion, one side of the second portion as the first portion, and the other side of the second portion as the third portion, The aforementioned break-starting point includes filler material filled in the first and third portions, excluding the second portion. The impact absorbing member according to feature 1.

16. The hollow tube has opposing wall portions that are positioned opposite the inner wall portion of the bend and are connected to the pair of side wall portions via a pair of other ridge portions; An additional bending point is provided in the hollow tube and configured to set another bending point on the opposing wall at another intermediate position in the longitudinal direction of the hollow tube, The present invention further comprises a pair of additional reinforcing portions that extend along the extending direction of each of the other ridge portions and are provided on the outer surface of each of the side walls adjacent to each of the other ridge portions when the hollow tube is viewed in a cross section perpendicular to the longitudinal direction at the location of the other bending point; The impact absorbing member according to feature 1.

17. The reinforcement has a first portion, a second portion, and a third portion arranged in order along the longitudinal direction; The aforementioned trigger for the break was, A through portion provided in the second portion or a bead formed to be long in a direction intersecting the longitudinal direction, A rigid portion that is long in the longitudinal direction is arranged in the first portion and the third portion, Having at least one of the following: The impact absorbing member according to feature 2.

18. The reinforcement has a first portion, a second portion, and a third portion arranged in order along the longitudinal direction; The aforementioned bending point is formed in the second portion of the reinforcement, including the connection point with the hollow tube. A plate thickness thinner than both the first and third portions, Lower tensile strength than both the first and third parts, Having at least one of the The impact absorbing member according to feature 2.

19. The hollow tube has a first portion, a second portion, and a third portion arranged sequentially along the longitudinal direction; The aforementioned trigger for the break was, The reinforcement positioned at least at the second portion, Filling material disposed inside the first part and inside the third part, has The impact absorbing member according to feature 2.

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