Automotive collision energy absorption parts

Abstract

Provided is a collision energy absorbing component for automobiles that reduces the maximum collision load in the early stage of a collision and sufficiently absorbs collision energy while suppressing an increase in the collision load in the later stage of the collision. [Solution] The collision energy absorption component 1 of the present invention absorbs collision energy by undergoing axial collapse when a collision load is input from the front or rear of the vehicle body, and comprises a cylindrical portion 10 having eight face portions 11 and an octagonal cross section perpendicular to the axial collapse direction, and a plurality of slits 20 formed in one of the face portions 11 in a shape extending in a direction approximately perpendicular to the axial collapse direction, The multiple slits 20 are not formed on the inclined surface portion 11d corresponding to the side with the shortest length of the octagon, but are formed in three or more equally spaced positions along the axial crushing direction on the side surface portion 11c corresponding to the side with the longest length of the octagon, the length of each slit 20 being 10% or more of the length of the side of the side surface portion 11c, and the width of each slit 20 being 1.0 times or more the plate thickness of the side surface portion 11c.

Description

[Technical Field]

[0001] The present invention relates to a collision energy absorption component for an automobile that is provided at the front or rear of a vehicle body and that absorbs collision energy by axially collapsing when a collision load is input from the front or rear of the vehicle body. [Background technology]

[0002] Automotive structural parts are required to be lighter in weight to improve fuel economy and to improve collision safety. In electric vehicles, increasing the battery load is effective in extending the driving range, but this increases the vehicle weight, which in turn increases the impact (collision energy) in the event of a vehicle collision. Therefore, electric vehicles require structural parts that can adequately absorb collision energy.

[0003] Crash boxes are automobile collision energy absorption components that absorb collision energy during a vehicle collision. They are attached to the front or rear of the vehicle and protect occupants by absorbing collision energy during a collision and suppressing deformation inside the vehicle cabin. Crash boxes are installed, for example, between the front side members and the front bumper beam at the front of the vehicle, and when compressive force acts in the fore-and-aft direction of the vehicle during a vehicle collision, they undergo axial collapse to absorb collision energy.

[0004] Many collision energy absorbing parts for automobiles have been proposed so far. For example, Patent Document 1 discloses a crash box that has a structure that allows performance such as energy absorption, maximum resistance, and residual crushing force to be set to target performance, while also allowing the box body to be easily set to a desired shape. Furthermore, Patent Document 2 discloses a crash can (corresponding to a "crash box") that can both suppress the amount of initial load transmitted to the front frame during a vehicle collision and ensure the amount of energy absorption. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-234377 [Patent Document 2] Japanese Patent Publication No. 2022-12132 Summary of the Invention [Problem to be solved by the invention]

[0006] Until now, crash boxes have been made of steel plates with a relatively low strength, around 440 MPa, to ensure sufficient compressive deformation. However, in response to demands for increased collision energy absorption in the event of an electric vehicle collision, the use of thicker steel plates with a tensile strength of 590 MPa or steel plates with a tensile strength of 980 MPa or higher is being considered.

[0007] Crash boxes made of these steel plates have a high resistance to compressive loads during a collision, so they do not collapse properly when another vehicle collides with them. This means that the collision energy is absorbed by the deformation of the other vehicle, which can increase the risk of injury to the occupants of that vehicle. Therefore, it is important that crash boxes not only reduce the amount of collision energy absorption, but also ensure that their maximum load (resistance) is not too high in order to reduce the risk of injury to the other vehicle.

[0008] However, the technology of Patent Document 1 has a structure in which reinforcement is provided to connect a pair of opposing walls of the box body of the crash box, so it is unavoidable that the maximum load increases. Furthermore, with the technology of Patent Document 1, because reinforcement is provided inside the cylindrical box body, the number of parts and weight increase compared to a crash box that only has a cylindrical box body.

[0009] The technology of Patent Document 2 is configured so that when a collision load directed toward the rear of the vehicle is input, the first weak parts formed in the corners located between the upper or lower surface part and the side surface parts deform before the second weak parts provided on the pair of side surface parts. Therefore, although it is possible to reduce the collision load at the early stage of the collision, the collision load decreases without stable collapse at the later stage of the collision, and it is not possible to sufficiently absorb the collision energy.

[0010] The present invention has been made to solve the above-mentioned problems, and has an object to provide a collision energy absorption component for an automobile that can keep the collision load low in the early stages of a collision when a collision load is input from the front or rear of the vehicle, and can obtain a sufficient collision energy absorption effect in the later stages of the collision. [Means for solving the problem]

[0011] (1) The automobile collision energy absorption component according to the present invention is provided at the front or rear of a vehicle body, extends in the fore-and-aft direction of the vehicle body, and absorbs collision energy by axial crushing when a collision load is input from the front or rear of the vehicle body, It has a cylindrical portion with four or more faces, and the cross-sectional shape of the cylindrical portion perpendicular to the axial collapse direction when it is axially collapsed is a polygon with four or more sides, A plurality of slits are formed on any one of the surfaces so as to extend in a direction substantially perpendicular to the axial collapse direction, The plurality of slits are not formed on the surface portion corresponding to the side with the shortest length of the polygon, but are formed in three or more equally spaced positions in the axial crushing direction on the surface portion corresponding to the side with the longest length of the polygon, the length of each of the slits is 10% or more of the length of a side of the polygon corresponding to the surface portion on which the slit is formed; The width of each of the slits is at least 1.0 times the plate thickness of the surface portion in which the slit is formed.

[0012] (2) In the above (1), the length of the slit is 85% or less of the length of a side of the polygon corresponding to the surface portion on which the slit is formed, The width of the slit is characterized by being 5.0 times or less the thickness of the surface portion in which the slit is formed.

[0013] (3) In the above (1) or (2), The spacing between the plurality of slits is between 1.0 and 1.5 times the minimum length of the side of the polygon. [Effects of the Invention]

[0014] According to the present invention, when a collision load is input from the front or rear of the vehicle body, the collision load can be kept low in the early stage of the collision, and the collision energy can be sufficiently absorbed by stable axial crushing deformation in the later stage of the collision, thereby improving the collision performance of the vehicle and contributing to improving the marketability of the automobile. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an automobile collision energy absorbing component according to an embodiment of the present invention; [Figure 2] 1A and 1B are diagrams illustrating the lengths and widths of multiple slits formed on the surface constituting the cylindrical portion, and the spacing between the slits, in an automobile collision energy absorption component according to this embodiment ((a) rectangular slits, (b) elliptical slits). [Figure 3] 3A and 3B are diagrams showing specific cross-sectional shapes of a cylindrical portion in the automobile collision energy absorption component according to the present invention. [Figure 4] FIG. 2 is a diagram illustrating a collision energy absorbing component for an automobile as a comparative example in the examples. [Figure 5] 1A and 1B are diagrams showing deformation of an automobile collision energy absorption part after the start of a collision, as determined by a collision simulation in an example ((a) multiple slits formed in the side surface corresponding to the longest side of the cylindrical part, (b) no slits formed). DETAILED DESCRIPTION OF THE INVENTION

[0016] [Background to the invention] An example of a collision energy absorption component that absorbs collision energy by axial crushing is a collision energy absorption component 3 having eight face portions 11 and a cylindrical portion 10 with an octagonal cross section perpendicular to the axial crushing direction, as shown in FIG. 4.

[0017] As described above, such a collision energy absorbing component 3 is required to suppress the collision load at an early stage of the collision to a low level, and to obtain a sufficient collision energy absorption effect at a later stage of the collision.

[0018] Each surface portion 11 of the cylindrical portion 10 corresponds to each side of an octagon in the cross-sectional shape of the cylindrical portion 10, but the lengths of all sides of the octagon are not necessarily equal in the cylindrical portion 10. For example, in the cylindrical portion 10 shown in Fig. 4, the inclined surface portion 11d corresponds to the side with the shortest length of the octagon, the side surface portion 11c corresponds to the side with the longest length of the octagon, and the upper surface portion 11a and the lower surface portion 11b correspond to the sides of the octagon with lengths between the shortest and longest sides.

[0019] When a collision load is applied to a collision energy absorption component 3 having such a tubular portion 10, the tubular portion 10 undergoes axial collapse due to buckling of each surface portion 11, thereby absorbing the collision energy. However, the buckling period of the inclined surface portion 11d corresponding to the side with the shortest length of the octagon is shorter than the buckling period of the side portion 11c corresponding to the side with the longest length. Therefore, the collision energy absorption component 3 exhibits unstable buckling behavior due to non-uniform buckling of each surface portion 11 during the axial collapse process of the tubular portion 10, resulting in a decrease in the collision load in the later stages of the collision and insufficient absorption of the collision energy.

[0020] The inventors have conducted extensive research into this issue and have come up with the idea of ​​forming slits (holes) in the side surface portion 11c corresponding to the longest side, which will serve as the breakage starting points during the axial crushing process, and not forming slits in the inclined surface portion 11d corresponding to the shortest side. This idea is intended to make the buckling period of each surface portion 11 closer to, or more preferably to match, the buckling period of the inclined surface portion 11d corresponding to the shortest side.

[0021] The inventors have found that a cylindrical portion with slits formed in this way undergoes stable axial crushing deformation in the later stages of a collision, deforming into an accordion-like shape, and is able to sufficiently absorb the collision energy while suppressing a decrease in the collision load. In particular, by aligning the buckling of each surface portion with the surface portion corresponding to the side with the shortest length, the period of the accordion-like buckling deformation can be shortened, making it possible to absorb more collision energy. Furthermore, it was also found that by forming a slit in the side surface portion 11c, it is possible to reduce the collision load at the initial stage of a collision.

[0022] The present invention has been made based on these findings, and the specific configuration thereof will be described below.

[0023] [Embodiment Mode] FIG. 1 shows an example of a collision energy absorbing component for an automobile (hereinafter referred to as a "collision energy absorbing component 1") according to an embodiment of the present invention. The collision energy absorption component 1 is provided at the front or rear of the vehicle body and extends in the fore-and-aft direction of the vehicle body, and absorbs collision energy by axial crushing when a collision load is input from the front or rear of the vehicle body. As shown in Fig. 1, the collision energy absorption component 1 has a tubular portion 10 and a plurality of slits 20. The collision energy absorption component 1 according to this embodiment will be described below. In the following description, the relative positions and directions of the components are expressed based on the assumption that the collision energy absorption component 1 is mounted on the vehicle body so that the direction in which the collision energy absorption component 1 axially collapses (axial collapse direction) coincides with the front-to-rear direction of the vehicle.

[0024] 1, the cylindrical portion 10 has eight surfaces 11: an upper surface 11a, a lower surface 11b, a pair of side surfaces 11c, and an inclined surface 11d connecting the upper surface 11a or the lower surface 11b to the side surface 11c. When the collision energy absorption component 1 is mounted on the vehicle body, the upper surface 11a and the lower surface 11b face each other in the vertical direction of the vehicle, and the pair of side surfaces 11c face each other in the left-right direction of the vehicle.

[0025] The cylindrical portion 10 has an octagonal cross section perpendicular to the axial collapse direction, and has a ridgeline R portion 13 connecting the side ends of each face portion 11 in the direction perpendicular to the axial collapse direction. In the cross-sectional shape of the cylindrical portion 10 perpendicular to the axial collapse direction, each face portion 11 corresponds to each side of the octagon, and each ridge line R portion 13 corresponds to each corner of the octagon. In this embodiment, the inclined surface portion 11d corresponds to the side with the shortest length of the octagonal cross-sectional shape of the cylindrical portion 10, and the side surface portion 11c corresponds to the side with the longest length of the octagon.

[0026] As shown in FIG. 1, the multiple slits 20 are not formed on the inclined surface portion 11d of the surface portion 11, which corresponds to the side with the shortest length of the octagon, but are formed at equal intervals in the axial collapse direction on the side surface portion 11c, which corresponds to the side with the longest length of the octagon.

[0027] The direction in which the multiple slits 20 extend is set to a direction approximately perpendicular to the axial direction in order to allow for manufacturing errors and variations, but it is preferable that the direction be perpendicular to the axial collapse direction. The range of allowable extension direction of the slits 20 due to manufacturing errors and variations is preferably within ±5° of the direction perpendicular to the axial collapse direction.

[0028] The length of each slit 20 is 10% or more of the length of the side of the octagon corresponding to the side surface 11c on which the slit 20 is formed. The width of each slit 20 is 1.0 times or more the thickness of the side surface portion 11c in which the slit 20 is formed.

[0029] As described above, the collision energy absorption component 1 according to this embodiment has a plurality of slits 20 formed at equal intervals in the axial crushing direction in the side surface portion 11c of the surface portion 11, the side portion 11c corresponding to the longest side of the octagonal cross-sectional shape of the tubular portion 10. As a result, when a collision load is input to the tip of the collision energy absorption component 1 in the vehicle body longitudinal direction, the slits 20 act as effective starting points for bending deformation in the early stages of the collision, thereby keeping the maximum collision load in the early stages of the collision low and reducing the damage to the other side in the collision.

[0030] Furthermore, the collision energy absorption component 1 can make the buckling period of each surface portion 11 of the tubular portion 10 approach, or more preferably match, the inclined surface portion 11d corresponding to the side with the shortest length and having the shortest buckling period. This allows the tubular portion 10 to undergo stable axial collapse and deform into an accordion-like shape in the later stages of the collision while suppressing a decrease in the collision load, allowing the collision energy absorption component 1 to sufficiently absorb the collision energy.

[0031] As described above, the collision energy absorption component 1 according to this embodiment can reduce the collision load in the early stages of a collision and sufficiently absorb the collision energy while suppressing a decrease in the collision load in the later stages of the collision, thereby improving the collision performance of automobiles and contributing to improved marketability.

[0032] The present invention achieves the above-mentioned effects by allowing the slits formed in the surface of the tubular portion to become the starting points for folding, and the role of such slits is particularly pronounced in the early stages of a collision. That is, in the early stages of a collision or in the middle stages of a collision when the tubular portion is axially crushed and deformed, stress concentrates at the ends of the slits due to the collision load, causing them to buckle. After the ends of the slits buckle and become starting points for folding in the tubular portion, the areas around the slits on the surface where the slits are formed deform out-of-plane, becoming new starting points for folding.

[0033] In order for the slit to function as a starting point for folding, the size of the slit is important. As mentioned above, the length of the slit is at least 10% of the length of the side of the polygon corresponding to the surface portion in which the slit is formed, but it is preferable that the upper limit be 85% or less of the length of the side of the polygon corresponding to the surface portion in which the slit is formed. Furthermore, as mentioned above, the width of each slit is at least 1.0 times the thickness of the surface portion in which the slit is formed, but it is preferable that the upper limit be no more than 5.0 times the thickness of the surface portion in which the slit is formed. If the length and width of the slit exceed these upper limits, the collision load in the early stage of the collision will be lower, but the collision load in the later stage of the collision will also be lower, reducing the effect of improving the amount of collision energy absorption.

[0034] The slit interval is preferably in the range of 1.0 to 1.5 times the minimum length of a side of the polygonal cross section of the cylindrical portion. Here, the slit interval is defined as the distance between the tips of the slits 20 in the axial collapse direction, as shown in Figure 2(a).

[0035] The spacing between the multiple slits 20 is set within the above range in order to make the buckling period of the face portion corresponding to the longest side of the polygon closer to or match the buckling period of the face portion corresponding to the shortest side of the polygon, which has a shorter buckling period. As a result, the collision energy absorption component according to the present invention collapses (buckles) stably in the later stages of a collision, thereby achieving a stable and high collision energy absorption effect. Furthermore, by making the buckling period of each surface portion closer to, or more preferably matching, the buckling period of the surface portion corresponding to the side with the shortest length, it is possible to suppress fluctuations in collision load during the axial collapse process and reduce the decrease in collision load.

[0036] 1, seven slits are formed in the side surface portion 11c, but in the present invention, it is sufficient if three or more slits are formed in the surface portion corresponding to the longest side (each side surface portion 11c in FIG. 1). This serves as the starting point for buckling of the tubular portion, promoting axial collapse, and in the later stages of the collision, the tubular portion can be deformed into an accordion-like shape by stably collapsing axially while suppressing a decrease in the collision load.

[0037] In the present invention, the slits function to act as starting points for buckling and promote axial collapse of the tubular portion 10. Therefore, the present invention is not limited to the rectangular slits 20 shown in Figures 1 and 2(a), and may also be, for example, elliptical slits 20A as shown in Figure 2(b). In the case of such non-rectangular slits, the length of the slit should be the maximum length in the direction perpendicular to the axial collapse direction, and the width of the slit should be the maximum length in the axial collapse direction, as shown in Figure 2(b).

[0038] Furthermore, the present invention only requires that the multiple slits are not formed in the surface portion corresponding to the side with the shortest length of the polygonal cross-sectional shape of the cylindrical portion (inclined surface portion 11d shown in FIG. 1), but are formed at least in the surface portion corresponding to the side with the shortest length of the polygon (side surface portion 11c shown in FIG. 1). Therefore, the present invention also includes those in which multiple slits are formed in surface portions that do not correspond to either the longest side or the shortest side, such as upper surface portion 11a and lower surface portion 11b shown in FIG. 1.

[0039] When slits are formed on a surface portion other than the surface portion corresponding to the side with the longest length or the side with the shortest length (the upper surface portion 11a or the lower surface portion 11b in FIG. 1), the length and width of each slit and the spacing between the slits may be the same as those of the slits formed on the surface portion corresponding to the side with the longest length (the side surface portion 11c in FIG. 1).

[0040] Furthermore, the method for forming the slits in these surfaces may be, for example, punching by shearing or laser processing, and may be either before, after, or during the process of forming the cylindrical portion.

[0041] In the present invention, the tubular portion 10 is not limited to an octagonal cross-sectional shape formed by joining (e.g., arc welding) two press-formed metal plate parts 10A together with their opening sides facing each other, as shown in FIG. 3(a). FIG. 3(b) shows a cylindrical part 10 formed by roll-forming a single metal plate and joining (for example, by laser welding) the end parts 17 to form an octagonal cross-sectional shape.

[0042] The cylindrical portion 10 shown in Fig. 1 has eight face portions 11 and an octagonal cross-sectional shape. However, the present invention is not limited to this, and it may have four or more face portions and a cross-sectional shape that is a polygon with four or more sides. Figure 3(c) shows a cylindrical portion 10 having four face portions and a rectangular cross-sectional shape, formed by joining two U-shaped cross-section shaped parts 10B, each made by pressing a metal plate into a U-shaped cross-section, with the opening sides facing each other. [Example]

[0043] An analysis was carried out to confirm the effects of the automobile collision energy absorbing component according to the present invention, and the results are described below.

[0044] The analysis was performed using the collision energy absorption component 1 (Fig. 1) described in the embodiment as an example of the invention as the analysis target, and a collision simulation was performed in which a punch was struck on one end side in the axial crushing direction to input a collision load. The collision simulation then determined the deformation state of the collision energy absorption component 1 during the axial crushing process, and the relationship between the collision load input to the collision energy absorption component 1 and the amount of deformation in the axial crushing direction (load-stroke curve).

[0045] The collision energy absorption component 1 was made using a steel plate with a tensile strength of 980 MPa and a thickness of 1.2 mm. As shown in Fig. 3(a), the cylindrical portion 10 was formed into an octagonal cross-sectional shape by arc welding two parts 10A that were press-formed from steel plate. In the octagonal cross-sectional shape of the cylindrical portion 10, the lengths of the sides corresponding to the upper surface portion 11a and the lower surface portion 11b are 42 mm, the length of the side corresponding to the side surface portion 11c is 66 mm, and the length of the side corresponding to the inclined surface portion 11d is 22 mm. In other words, the side corresponding to the inclined surface portion 11d is the shortest length, and the side corresponding to the side surface portion 11c is the longest length.

[0046] In the collision energy absorbing component 1, no slits 20 were formed on the inclined surface portion 11d corresponding to the side with the shortest length, but seven slits 20 were formed at equal intervals in the axial crushing direction on the side surface portion 11c corresponding to the side with the longest length. Then, a collision simulation was performed for each of the collision energy absorbing components 1 in which the length, width and interval of the slits 20 were variously changed, as shown in No. 2 to No. 12 in Table 1 below. As a comparison, a collision simulation was also performed on a collision energy absorbing component 3 in which no slits were formed on any of the surface portions 11 that constitute the cylindrical portion 10, as shown in FIG. 4 (No. 1 in Table 1).

[0047] [Table 1]

[0048] Figure 5 shows the deformation after the start of a collision obtained by performing a collision simulation on a collision energy absorbing component 1 (an example of the invention) in which multiple slits 20 having the length, width and spacing shown in No. 2 of Table 1 are formed in the side portion 11c, and a collision energy absorbing component 3 (a comparative example) in which no slits are formed as shown in No. 1 of Table 1.

[0049] 5(a), in the collision energy absorption component 1 according to the example of the invention, the inclined surface portion 11d corresponding to the side with the longest length buckles from the slit 20, which occurs at approximately the same position in the axial crushing direction as the buckling of the inclined surface portion 11d corresponding to the side with the shortest length. This shows that the buckling deformation of the tubular portion 10 progresses in a bellows-like manner.

[0050] In contrast, in the collision energy absorption component 3 without slits, the buckling of the inclined surface portion 11d and the buckling of the side surface portion 11c are not aligned in the axial crushing direction, as shown in Figure 5(b), so the deformation of the cylindrical portion continues while buckling at an unintended position. It is thought that such unstable buckling behavior leads to fracture of the welded portion and base material, thereby reducing the absorbed energy.

[0051] For each of the conditions No. 1 to No. 2 in Table 1, the maximum value of the collision load at the beginning of the collision (hereinafter referred to as "initial maximum load") was determined from the load-stroke curve obtained by the collision simulation as the initial maximum load that indicates the performance of the collision energy absorption part 1. Furthermore, the amount of collision energy absorption (hereinafter referred to as "absorbed energy") was calculated from the integrated value of the collision load up to a deformation amount (stroke) of 130 mm in the axial crushing direction. The initial maximum load and absorbed energy obtained for each of No. 1 to No. 12 are shown in Table 1 above.

[0052] No. 1 is a comparative example in which no slits are formed on any of the surface portions 11 as shown in FIG. 4, and the initial maximum load was 366 kN and the absorbed energy was 7.4 kJ.

[0053] In No. 2, the length of the slits 20 (= 35 mm) is 53% of the width of the side surface portion 11c (= 66 mm, the length of the side of the side surface portion 11c), and the width of the slits 20 (= 4.0 mm) is 3.3 times the plate thickness of the side surface portion 11c (1.2 mm), both of which are within the range of the present invention. Furthermore, in No. 2, the spacing between the slits 20 (= 28 mm) is 1.3 times the minimum length of the side of the octagonal cross-sectional shape of the tubular portion 10 (= 22 mm, the length of the side corresponding to the inclined surface portion 11d), which is within the preferred range of the present invention. In No. 2, the initial maximum load was 272 kN, which was significantly lower than that of No. 1, which had no slits. In addition, the absorbed energy was 15.7 kJ, which was significantly higher than that of No. 1. The reason why the collision load in No. 2 decreased in the early stage of the collision is thought to be that first, the vicinity of the slit 20 buckled in the early stage of the collision, and then the ridge R portion in the vicinity of the slit 20 buckled.

[0054] In No. 3, the length of the slit 20 was 59 mm, which was 89% of the width of the side surface portion 11c and larger than the preferred range of the present invention (85% or less of the side length of the side surface portion 11c, 66 mm). The initial maximum load was 206 kN, which was significantly lower than No. 1 because the slit 20 was longer than in No. 2. The absorbed energy was 11.7 kJ, which was lower than No. 2 but higher than No. 1. The reason that the absorbed energy was lower than No. 2 is thought to be because the ratio of the opening area of ​​the slit 20 to the area of ​​the side surface portion 11c increased, thereby reducing the collision load during deformation.

[0055] In No. 4, the width of the slit 20 was 2.0 mm, and the plate thickness of the side portion 11c was greater than or equal to 1.2 mm, which is within the range of the present invention. The initial maximum load was 272 kN, similar to No. 2, and lower than No. 1. The absorbed energy was 13.7 kJ, lower than No. 2 but higher than No. 1.

[0056] In No. 5, the length of the slit 20 was set to 7 mm, which is within the range of the present invention (10% or more of the 66 mm length of the side of the side portion 11c). The initial maximum load was 296 kN, which was increased compared to No. 2 by shortening the length of the slit 20, but was lower than No. 1. The absorbed energy was 13.4 kJ, which was lower than No. 2 but higher than No. 1.

[0057] In No. 6, the length of the slit 20 was 3 mm, which is outside the scope of the present invention (less than 10% of the width of the side surface portion 11c, 66 mm). The initial maximum load was 362 KN, which was similar to that of No. 1, in which no slit was formed. This is thought to be because when the length of the slit 20 was less than 10%, sufficient out-of-plane deformation did not occur at the end of the slit 20, and was insufficient to induce buckling of the ridge R portion 13 of the tubular portion 10. The absorbed energy was also 7.2 kJ, which was similar to that of No. 1. This is thought to be because if the length of the slit 20 is too short, it will not be effective as a starting point for buckling, and the tubular portion 10 will not deform stably into an accordion shape during the collision process.

[0058] Nos. 7 to 10 have slit 20 with widths of 0.8 mm, 1.2 mm, 6.0 mm, and 8.0 mm. No. 7, in which the width of the slit 20 was outside the range of the present invention (less than 1.0 times the plate thickness of the side surface portion 11c, 1.2 mm), had an initial maximum load of 363 kN and absorbed energy of 7.8 kN, both of which were similar to No. 1. This is thought to be because the opening width of the slit 20 was too narrow, so that the opening edge of the slit 20 abutted in the axial crushing direction during a collision, and it was no longer effective as a starting point for buckling. Nos. 8 to 10, in which the width of the slit 20 is within the range of the present invention (1.0 times or more the plate thickness of the side surface portion 11c, 1.2 mm), had initial maximum loads of 297 kN, 264 kN, and 221 kN, all of which were lower than No. 1, in which no slit was formed. In addition, Nos. 8 to 10 had absorbed energy of 13.6 kJ, 14.0 kJ, and 11.5 kJ, all of which were higher than No. 1, in which no slit was formed. No. 10, in which the width of the slit 20 was outside the preferred range of the present invention (more than 5.0 times the plate thickness of the side surface portion 11c, 1.2 mm), had lower initial maximum load and absorbed energy than No. 2. The decrease in initial maximum load is thought to be due to the wider width of the slit 20, which reduced the cross-sectional area subjected to the collision load.

[0059] Nos. 11 and 12 have the length and width of the slits 20 within the preferred range of the present invention, but the spacing between the slits 20 is outside the preferred range of the present invention (less than 1.0 times or more than 1.5 times the length 22m of the side of the inclined surface portion 11d corresponding to the side with the shortest length). Nos. 11 and 12 had initial maximum loads of 287 kN and 288 kN, which were lower than No. 1, which had no slits, but were not significantly different from Nos. 2 and 4. The absorbed energy was 12.1 kJ and 12.2 kJ, which was slightly lower than that of Nos. 2, 4, 5, 8, and 9, which had the length, width, and spacing of the slits 20 within the preferred range of the present invention. This indicates that by setting the spacing of the slits 20 within the preferred range of the present invention based on the length of the shortest side, it is possible to match the buckling wavelength of the side surface portion 11c to the inclined surface portion 11d, which has a short buckling period, and to obtain more stable bellows deformation.

[0060] As described above, it has been shown that the collision energy absorption component according to the present invention reduces the collision load in the early stage of a collision and improves the collision energy by stably buckling and deforming like an accordion in the later stage of the collision. [Explanation of symbols]

[0061] 1. Collision energy absorption parts 3. Collision energy absorption parts 10 Cylindrical part 10A parts 10B U-shaped cross-section parts 11 area 11a Top part 11b Bottom part 11c Side part 11d Slope section 13 Ridgeline R 15 Surface 17 End 19 Flange 20, 20A slit

Claims

1. A collision energy absorption component for an automobile is provided at a front or rear of a vehicle body, extends in a longitudinal direction of the vehicle body, and absorbs collision energy by axial crushing when a collision load is input from the front or rear of the vehicle body, A cylindrical portion has four or more faces, and the cross-sectional shape of the cylindrical portion perpendicular to the axial collapse direction when the cylindrical portion is axially collapsed is a polygon with four or more sides, A plurality of slits are formed on any one of the surfaces so as to extend in a direction substantially perpendicular to the axial collapse direction, the plurality of slits are not formed on the surface portion corresponding to the side with the shortest length of the polygon, but are formed in three or more areas at equal intervals in the axial crushing direction on the surface portion corresponding to the side with the longest length of the polygon, the length of each of the slits is 10% or more and 85% or less of the length of a side of the polygon corresponding to the surface portion on which the slit is formed; A collision energy absorption component for an automobile, characterized in that the width of each of the slits is 1.0 to 5.0 times the plate thickness of the surface portion in which the slit is formed.

2. 2. The automobile collision energy absorbing component according to claim 1, wherein the interval between the plurality of slits is 1.0 to 1.5 times the minimum length of a side of the polygon.

3. A collision energy absorption component for an automobile is provided at a front or rear of a vehicle body, extends in a longitudinal direction of the vehicle body, and absorbs collision energy by axial crushing when a collision load is input from the front or rear of the vehicle body, A cylindrical portion has four or more faces, and the cross-sectional shape of the cylindrical portion perpendicular to the axial collapse direction when the cylindrical portion is axially collapsed is a polygon with four or more sides, A plurality of slits are formed on any one of the surfaces so as to extend in a direction substantially perpendicular to the axial collapse direction, the plurality of slits are not formed on the surface portion corresponding to the side with the shortest length of the polygon, but are formed in three or more areas at equal intervals in the axial crushing direction on the surface portion corresponding to the side with the longest length of the polygon, the length of each of the slits is 10% or more of the length of a side of the polygon corresponding to the surface portion on which the slit is formed; The width of each slit is 1.0 times or more the plate thickness of the surface portion in which the slit is formed, A collision energy absorption component for an automobile, characterized in that the spacing between the multiple slits is between 1.0 and 1.5 times the minimum length of a side of the polygon.

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