Automotive collision energy absorption components

Abstract

The present invention provides an automotive collision energy absorbing component that reduces the maximum collision load in the initial stages of a collision, suppresses the increase in collision load in the later stages of a collision, and sufficiently absorbs collision energy. [Solution] The collision energy absorbing component 1 according to the present invention absorbs collision energy by axially collapsing when a collision load is applied from the front or rear of the vehicle body, and comprises a cylindrical portion 10 having eight face portions 11 and a cross-sectional shape that is octagonal perpendicular to the direction of axial collapse, and a plurality of slits 20 formed in one of the face portions 11 in a shape that extends in a direction substantially perpendicular to the direction of axial collapse, Multiple slits 20 are not formed on the inclined surface portion 11d corresponding to the shortest side of the octagon, but three or more are formed at equal intervals along the direction of axial crushing on the side portion 11c corresponding to the longest side of the octagon, the length of each slit 20 is 10% or more of the side length of the side portion 11c, and the width of each slit 20 is 1.0 times or more the plate thickness of the side portion 11c.

Description

Technical Field

[0001] The present invention relates to a collision energy absorption component for automobiles, which is provided at the front or rear of a vehicle body and axially collapses to absorb collision energy when a collision load is input from the front or rear of the vehicle body.

Background Art

[0002] Structural components of automobiles are required to be lightweight for fuel efficiency improvement and to have enhanced collision safety. In electric vehicles, increasing the battery loading capacity is effective for extending the cruising range, but this increases the vehicle body weight and becomes a factor in increasing the impact (collision energy) during vehicle collisions. Therefore, in electric vehicles, structural components capable of sufficiently absorbing collision energy are required.

[0003] As a collision energy absorption component for automobiles that absorbs collision energy during vehicle collisions, there is a crash box that is attached to the front or rear of a vehicle and suppresses deformation inside the vehicle cabin by absorbing the collision energy during a collision to protect the occupants. The crash box is provided, for example, between the front side member and the front bumper beam at the front of the vehicle, and axially collapses to absorb collision energy when a compressive force in the vehicle front-rear direction acts during a vehicle collision.

[0004] Many collision energy absorption components for automobiles have been proposed so far. For example, Patent Document 1 discloses a crash box that has a structure in which performance such as energy absorption amount, maximum resistance force, and remaining crush amount can be set to target performance, and the box body can be easily set to a desired shape. Also, Patent Document 2 discloses a crash can (corresponding to a "crash box") that enables both suppression of the amount of initial load transmitted to the front frame during vehicle collisions and ensuring of the energy absorption amount.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-234377 [Patent Document 2] Japanese Patent Publication No. 2022-12132 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Until now, crash boxes have used relatively low-strength steel plates with a tensile strength of around 440 MPa to allow for sufficient compressive deformation. However, in response to the demand for increased collision energy absorption during electric vehicle collisions, there is growing consideration to using thicker steel plates with a tensile strength of 590 MPa or higher, or even steel plates with a tensile strength of 980 MPa or higher.

[0007] These steel plates used in crash boxes have high resistance to compressive loads from collisions, preventing them from colliding excessively when another vehicle collides with them. This means that the collision energy is absorbed by the deformation of the other vehicle, potentially increasing the harm to the occupants of the other vehicle. Therefore, it is important that the crash box not only avoids compromising the amount of collision energy absorbed, but also that its maximum load (resistance) does not become too high in order to reduce the harm to the other vehicle in the collision.

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

[0009] The technology described in Patent Document 2 is designed so that when a collision load is applied in the rearward direction of the vehicle, a first weak point formed at the corner between the upper or lower surface and the side surface deforms before a second weak point provided on a pair of side surfaces. Therefore, although it is possible to reduce the collision load in the initial stages of the collision, the collision load does not decrease in the later stages of the collision without stable collapse, and the collision energy cannot be sufficiently absorbed.

[0010] The present invention was made to solve the above-mentioned problems, and aims to provide an automotive collision energy absorbing component that can suppress the collision load in the initial stages of a collision when a collision load is input from the front or rear of the vehicle, and can also obtain a sufficient collision energy absorption effect in the later stages of the collision. [Means for solving the problem]

[0011] (1) The collision energy absorbing component for automobiles according to the present invention is provided at the front or rear of the vehicle body and extends in the longitudinal direction of the vehicle body, and absorbs collision energy by axial crushing when a collision load is applied from the front or rear of the vehicle body, It has a cylindrical portion having four or more surfaces, and the cross-sectional shape of the cylindrical portion perpendicular to the direction of axial crushing is a polygon with four or more sides, One of the aforementioned surfaces has a plurality of slits formed in a shape that extends in a direction substantially perpendicular to the axial crushing direction, The multiple slits are not formed on the surface portion corresponding to the shortest side of the polygon, but are formed in portions of the surface portion corresponding to the longest side of the polygon, with three or more slits spaced equally apart in the direction of axial crushing. The length of each slit is 10% or more of the length of the side of the polygon corresponding to the surface portion on which the slit is formed. The width of each slit is characterized by being at least 1.0 times the thickness of the plate portion on which the slit is formed.

[0012] (2) In the items described in (1) above, The length of the slit is 85% or less of the length of the 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 plate portion on which the slit is formed.

[0013] (3) In the case of the items described in (1) or (2) above, The aforementioned plurality of slits are characterized in that the spacing between them is 1.0 times or more and 1.5 times or less the minimum side length of the polygon. [Effects of the Invention]

[0014] According to the present invention, when a collision load is applied from the front or rear of the vehicle body, the collision load in the initial stages of the collision is kept low, and the collision energy can be sufficiently absorbed by undergoing stable axial crushing deformation in the later stages of the collision. This improves the collision performance of the vehicle and contributes to improving the marketability of the automobile. [Brief explanation of the drawing]

[0015] [Figure 1] This figure illustrates an automobile collision energy absorbing component according to an embodiment of the present invention. [Figure 2] This figure illustrates the length and width of multiple slits formed on the surface constituting the cylindrical portion of the automotive collision energy absorbing component according to this embodiment, as well as the spacing between the slits ((a) rectangular slit, (b) elliptical slit). [Figure 3] This figure shows the specific cross-sectional shape of the cylindrical portion in the automotive collision energy absorbing component according to the present invention. [Figure 4] This figure illustrates an automotive collision energy absorbing component used as a comparative example in the examples. [Figure 5] The figure shows the deformation after the start of a collision, as determined by collision simulation of an automotive collision energy absorbing component in the embodiment ((a) multiple slits formed on the side corresponding to the longest side of the cylindrical portion, (b) no slits formed).

Mode for Carrying Out the Invention

[0016] [Background of the Invention] As a collision energy absorbing component that collapses axially to absorb collision energy, as shown as an example in FIG. 4, there is a collision energy absorbing component 3 having eight surface portions 11 and having a cylindrical portion 10 with an octagonal cross-sectional shape orthogonal to the axial collapse direction.

[0017] In such a collision energy absorbing component 3, as described above, it is required to keep the collision load at the initial stage of the collision low and to obtain a sufficient collision energy absorption effect in the latter stage of the collision.

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

[0019] When a collision load is input to the collision energy absorbing component 3 having such a cylindrical portion 10, the cylindrical portion 10 collapses axially due to buckling occurring in each surface portion 11 and absorbs the collision energy. However, the buckling period of the inclined surface portion 11d corresponding to the side with the minimum length of the octagon is shorter than the buckling period of the side surface portion 11c corresponding to the side with the maximum length. Therefore, the collision energy absorbing component 3 shows an unstable buckling behavior in which the buckling of each surface portion 11 is not synchronized during the axial collapse process of the cylindrical portion 10, the collision load decreases in the latter stage of the collision, and the collision energy cannot be sufficiently absorbed.

[0020] The inventors diligently considered these problems. As a result, they conceived the idea of ​​forming a slit (hole) in the side portion 11c corresponding to the longest side, which serves as the starting point for bending during the axial crushing process, while not forming a slit in the inclined surface portion 11d corresponding to the shortest side. This idea aims to bring the buckling period of each surface portion 11 closer to, or more preferably to, the buckling period of the inclined surface portion 11d corresponding to the shortest side.

[0021] Furthermore, it was found that the cylindrical section with the slit formed in this way undergoes stable axial crushing deformation in the later stages of impact, deforming into a bellows-like shape, thereby suppressing the reduction in impact load and absorbing sufficient impact energy. In particular, by aligning the buckling of each surface with the surface corresponding to the shortest length side, the period of bellows-like buckling deformation can be shortened, making it possible to absorb more impact energy. Furthermore, it was discovered that forming slits in the side portion 11c makes it possible to keep the collision load low during the initial stages of impact.

[0022] This invention is based on these findings, and its specific configuration is described below.

[0023] [Embodiment] Figure 1 shows, as an example, an automobile collision energy absorbing component (hereinafter referred to as "collision energy absorbing component 1") according to an embodiment of the present invention. The collision energy absorbing component 1 is provided at the front or rear of the vehicle body and extends in the longitudinal direction of the vehicle body. When a collision load is applied from the front or rear of the vehicle body, it axially collapses to absorb the collision energy. As shown in Figure 1, the collision energy absorbing component 1 has a cylindrical portion 10 and a plurality of slits 20. The collision energy absorbing component 1 according to this embodiment will be described below. In the following description, the relative position and direction of each component will be described based on the assumption that the collision energy absorbing component 1 is installed on the vehicle body such that the direction in which the collision energy absorbing component 1 axially collapses (axial collapse direction) coincides with the longitudinal direction of the vehicle.

[0024] As shown in Figure 1, the cylindrical portion 10 comprises eight surfaces 11, including an upper surface 11a and a lower surface 11b, a pair of side surfaces 11c, and an inclined surface 11d connecting the upper surface 11a or lower surface 11b to the side surfaces 11c. When the collision energy absorbing component 1 is installed 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-sectional shape perpendicular to the axial crushing direction, and has a ridge line R portion 13 connecting the side ends of each surface portion 11 in a direction perpendicular to the axial crushing direction. Furthermore, in the cross-sectional shape of the cylindrical portion 10 perpendicular to the direction of axial crushing, each surface portion 11 corresponds to each side of the octagon, and each edge radius 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 portion 11c corresponds to the side with the longest length of the octagonal cross-sectional shape.

[0026] As shown in Figure 1, the multiple slits 20 are not formed on the inclined surface portion 11d corresponding to the shortest side of the octagon, but are formed at equal intervals in the axial crushing direction on the side portion 11c corresponding to the longest side of the octagon.

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

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

[0029] As described above, in the collision energy absorbing component 1 according to this embodiment, a plurality of slits 20 are formed at equal intervals in the axial crushing direction on the side portion 11c of the surface portion 11, which corresponds to the longest side of the octagonal cross-sectional shape of the cylindrical portion 10. As a result, when a collision load is applied to the front end of the collision energy absorbing component 1 in the longitudinal direction of the vehicle body, the slits 20 act as effective starting points for bending deformation in the initial stages of the collision, thereby keeping the maximum collision load in the initial stages of the collision low and reducing the potential harm to the other party in the collision.

[0030] Furthermore, the collision energy absorbing component 1 can more preferably adjust the buckling period of each surface portion 11 in the cylindrical portion 10 to be closer to that of the inclined surface portion 11d corresponding to the side with the shortest buckling period. As a result, in the later stages of the collision, the cylindrical portion 10 deforms into a bellows shape by stable axial crushing while suppressing the decrease in collision load, and the collision energy absorbing component 1 can sufficiently absorb collision energy.

[0031] As described above, the collision energy absorbing component 1 according to this embodiment can suppress the collision load to a low level in the initial stages of a collision and suppress the decrease in the collision load in the later stages of the collision while sufficiently absorbing collision energy. Therefore, it can improve the collision performance of an automobile and contribute to improving its marketability.

[0032] The present invention achieves the above effect by having a slit formed on the surface of the cylindrical part act as the starting point for bending, and the role of such a slit is particularly pronounced in the initial stages of impact. That is, in the initial stages of impact or in the mid-stage of impact when the cylindrical part undergoes axial crush deformation, stress concentrates at the end of the slit due to the impact load, causing it to buckle. After the end of the slit buckles and becomes the starting point for bending in the cylindrical part, the surrounding portion of the surface where the slit was formed deforms out of the plane, becoming a new starting point for bending.

[0033] Furthermore, the dimensions of the slit are crucial for it to function as the starting point for a fold. As mentioned above, the length of the slit is 10% or more of the side length of the polygon corresponding to the surface on which the slit is formed, but preferably the upper limit is 85% or less of the side length of the polygon corresponding to the surface on 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 on which the slit is formed, but preferably the upper limit is 5.0 times or less the thickness of the surface on which the slit is formed. If the length and width of the slit exceed these upper limits, the collision load in the initial stages of the collision will be lower, but the collision load in the later stages of the collision will also be lower, reducing the effectiveness of improving the amount of collision energy absorbed.

[0034] The spacing between the slits is preferably in the range of 1.0 to 1.5 times the minimum side length of the polygon in the cross-sectional shape of the cylindrical part. Here, the spacing between the slits is the distance between the tips of each slit 20 in the direction of axial crushing, as shown in Figure 2(a).

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

[0036] In Figure 1, seven slits are formed on the side portion 11c, but in the present invention, it is sufficient to have three or more slits formed on the surface portion corresponding to the longest side (each side portion 11c in Figure 1). This promotes axial crushing by acting as the starting point for buckling of the cylindrical portion, thereby allowing for stable axial crushing and deformation of the cylindrical portion into a bellows shape while suppressing the decrease in impact load in the later stages of impact.

[0037] In the present invention, the slit serves as the starting point for buckling and promotes axial crushing of the cylindrical portion 10. Therefore, the present invention is not limited to the rectangular slit 20 shown in Figures 1 and 2(a), but may also be an elliptical slit 20A, as shown in Figure 2(b). In the case of a slit other than a rectangular shape, as shown in Figure 2(b), the length of the slit should be the maximum length in the direction perpendicular to the axial crushing direction, and the width of the slit should be the maximum length in the axial crushing direction.

[0038] Furthermore, the present invention is sufficient if the multiple slits are not formed on the surface portion corresponding to the shortest length side of the polygonal cross-sectional shape of the cylindrical portion (the inclined surface portion 11d shown in Figure 1), but at least on the surface portion corresponding to the shortest length side of the polygon (the side portion 11c shown in Figure 1). For this reason, the present invention includes cases in which the multiple slits are formed on a surface portion that does not correspond to either the longest length side or the shortest length side, such as the upper surface portion 11a and lower surface portion 11b shown in Figure 1.

[0039] Furthermore, when forming slits on surfaces other than those corresponding to the longest or shortest side (such as the top surface 11a and bottom surface 11b in Figure 1), the length and width of each slit, as well as the spacing between slits, should be the same as those formed on the surface corresponding to the longest side (such as the side surface 11c in Figure 1).

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

[0041] In the present invention, the cylindrical portion 10 is not limited to one formed by joining two parts 10A, which are press-formed from metal plates, with their openings facing each other (for example, by arc welding), as shown in Figure 3(a), to form an octagonal cross-sectional shape. Figure 3(b) shows a cylindrical part 10 formed by roll-forming a single metal plate and joining its ends 17 (for example, by laser welding) to create an octagonal cross-sectional shape.

[0042] The cylindrical portion 10 shown in Figure 1 had eight facets 11 and an octagonal cross-sectional shape. However, the present invention is not limited to this, and any portion having four or more facets and a cross-sectional shape of a quadrilateral or polygon is acceptable. Figure 3(c) shows a cylindrical part 10 formed by joining two U-shaped cross-sectional parts 10B, each made by press-forming a metal plate into a U-shaped cross-section, with their openings facing each other, and having four face surfaces, thus forming a rectangular cross-sectional shape. [Examples]

[0043] We conducted an analysis to confirm the effects of the collision energy absorbing component for automobiles according to the present invention, and the results are described below.

[0044] The analysis, as an example of the invention, uses the collision energy absorbing component 1 (Figure 1) described in the embodiment as the subject of analysis, and performs a collision simulation in which a punch is struck against one end in the direction of axial crushing to input a collision load. Through the collision simulation, the deformation state of the collision energy absorbing component 1 during the axial crushing process and the relationship between the collision load input to the collision energy absorbing component 1 and the amount of deformation in the direction of axial crushing (load-stroke curve) were determined.

[0045] The collision energy absorbing 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 Figure 3(a), the cylindrical portion 10 was formed by arc welding two press-formed steel plate components 10A together to create an octagonal cross-sectional shape. In the octagonal cross-sectional shape of the cylindrical portion 10, the lengths of the sides corresponding to the upper surface 11a and the lower surface 11b were 42 mm, the lengths of the sides corresponding to the side surface 11c were 66 mm, and the lengths of the sides corresponding to the inclined surface 11d were 22 mm. In other words, the side corresponding to the inclined surface 11d was the shortest length, and the side corresponding to the side surface 11c was the longest length.

[0046] In the collision energy absorbing component 1, the slits 20 were not formed on the inclined surface portion 11d corresponding to the shortest side, but seven slits were formed at equal intervals in the axial crushing direction on the side portion 11c corresponding to the longest side. Then, collision simulations were performed for each of the collision energy absorbing components 1 with various changes in the length, width, and spacing of the slits 20, as shown in Table 1 below (Nos. 2 to 12). Furthermore, as shown in Figure 4, a collision simulation was also performed on a collision energy absorbing component 3 in which no slits are formed on any of the surface portions 11 constituting the cylindrical portion 10, for comparison purposes (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 for a collision energy absorbing component 1 (example of invention) having multiple slits 20 of the length, width, and spacing shown in No. 2 of Table 1 formed on the side portion 11c, and a collision energy absorbing component 3 (comparative example) without slits, as shown in No. 1 of Table 1.

[0049] As shown in Figure 5(a), in the collision energy absorbing component 1 according to the example of the invention, the inclined surface portion 11d corresponding to the longest side buckles starting from the slit 20, and this buckling occurs at approximately the same position in the direction of axial collapse as the buckling of the inclined surface portion 11d corresponding to the shortest side. This shows that the buckling deformation of the cylindrical portion 10 is progressing in a bellows-like manner.

[0050] In contrast, in the impact energy absorbing component 3, which does not have a slit, as shown in Figure 5(b), the buckling of the inclined surface portion 11d and the buckling of the side portion 11c do not align in the direction of axial crushing. As a result, deformation of the cylindrical portion progresses while buckling occurs at an unintended position. Such unstable buckling behavior is thought to lead to fracture of the welded joint or base material, resulting in a decrease in 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 collision simulation, as the initial maximum load indicating the performance of collision energy absorption component 1. Furthermore, the amount of collision energy absorbed (hereinafter referred to as "absorbed energy") was determined by the cumulative 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 surfaces 11, as shown in Figure 4. The initial maximum load was 366 kN and the absorbed energy was 7.4 kJ.

[0053] In No. 2, the length of the slit 20 (=35 mm) is 53% of the width of the side portion 11c (=66 mm, the length of the side portion 11c), and the width of the slit 20 (=4.0 mm) is 3.3 times the plate thickness of the side portion 11c (1.2 mm), both of which are within the scope of the present invention. Furthermore, in No. 2, the spacing of the slits 20 (=28 mm) is 1.3 times the minimum side length of the octagonal cross-sectional shape of the cylindrical 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 in No. 1, which did not have a slit. Furthermore, the absorbed energy was 15.7 kJ, a significant increase compared to No. 1. The reason why the impact load decreased in the initial stages of the collision in No. 2 is thought to be that the area near the slit 20 buckled in the initial stages of the collision, followed by the buckling of the R-shaped ridge near the slit 20.

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

[0055] No. 4 has a slit 20 width of 2.0 mm and a plate thickness of the side portion 11c (1.2 mm) that is within the scope 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, which was 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 scope of the present invention (more than 10% of the side length of the side portion 11c, which is 66 mm). The initial maximum load was 296 kN, which increased compared to No. 2 due to the shorter length of the slit 20, but was lower than that of No. 1. The absorbed energy was 13.4 kJ, which was lower than that of No. 2, but increased compared to No. 1.

[0057] In No. 6, the length of the slit 20 was set to 3 mm, which is outside the scope of the present invention (less than 10% of the width of the side portion 11c, which is 66 mm). The initial maximum load was 362 KN, which was about the same as in No. 1, where no slit was formed. This is thought to be because, with a slit length of less than 10%, sufficient out-of-plane deformation occurred at the end of the slit 20, and was insufficient to induce buckling of the ridge radius portion 13 of the cylindrical portion 10. Furthermore, the absorbed energy was also similar to that of No. 1, at 7.2 kJ. This is thought to be because if the length of the slit 20 is too short, it does not have the effect of being the starting point for buckling, and the cylindrical part 10 does not stably deform into a bellows shape during the collision process.

[0058] Numbers 7 through 10 have slit widths of 0.8 mm, 1.2 mm, 6.0 mm, and 8.0 mm, respectively. In No. 7, where the width of the slit 20 was outside the scope of the present invention (less than 1.0 times the plate thickness of the side portion 11c, which is 1.2 mm), the initial maximum load was 363 kN and the absorbed energy was 7.8 kN, both of which were about the same as in No. 1. This is thought to be because the opening width of the slit 20 was too narrow, causing the opening edge of the slit 20 to abut in the direction of axial crushing during impact, thus preventing it from acting as a starting point for buckling. For No. 8 to No. 10, where 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 portion 11c, which is 1.2 mm), the initial maximum loads were 297 kN, 264 kN, and 221 kN, respectively, all of which were lower than No. 1, which does not have a slit. Also, for No. 8 to No. 10, the absorbed energy was 13.6 kJ, 14.0 kJ, and 11.5 kJ, respectively, all of which were higher than No. 1, which does not have a slit. In No. 10, where 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 portion 11c, which is 1.2 mm), the initial maximum load and absorbed energy decreased compared to No. 2. The decrease in the initial maximum load is thought to be due to the wider width of the slit 20, which reduced the cross-sectional area receiving the impact load.

[0059] In No. 11 and No. 12, the length and width of the slit 20 are within the preferred range of the present invention, while 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 of the shortest side). For No. 11 and No. 12, the initial maximum loads were 287kN and 288kN, respectively, which were lower than No. 1, which did not have a slit, and there was no significant difference compared to No. 2 and No. 4. The absorbed energies were 12.1 kJ and 12.2 kJ, which were slightly lower than those in No. 2, No. 4, No. 5, No. 8, and No. 9, where the length, width, and spacing of the slits 20 were 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, the buckling wavelength of the side portion 11c can be matched to the inclined surface portion 11d, which has a short buckling period, resulting in more stable bellows deformation.

[0060] In summary, the collision energy absorbing component according to the present invention reduces the collision load in the initial stages of a collision and improves collision energy by causing stable buckling deformation in a bellows-like manner in the later stages of the collision. [Explanation of symbols]

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

Claims

1. An automotive collision energy absorbing component that is installed at the front or rear of the vehicle body and extends in the longitudinal direction of the vehicle body, and absorbs collision energy by axially collapsing when a collision load is applied from the front or rear of the vehicle body, It has a cylindrical portion having four or more surfaces, and the cross-sectional shape of the cylindrical portion perpendicular to the direction of axial crushing is a polygon with four or more sides, One of the aforementioned surfaces has a plurality of slits formed in a shape that extends in a direction substantially perpendicular to the axial crushing direction, The multiple slits are not formed on the surface portion corresponding to the shortest side of the polygon, but are formed in portions of the surface portion corresponding to the longest side of the polygon, with three or more slits spaced equally apart in the direction of axial crushing. The length of each slit is 10% or more of the length of the side of the polygon corresponding to the surface portion on which the slit is formed. An automotive collision energy absorbing component characterized in that the width of each slit is 1.0 times or more the thickness of the surface portion on which the slit is formed.

2. The length of the slit is 85% or less of the length of the side of the polygon corresponding to the surface portion on which the slit is formed. The collision energy absorbing component for automobiles according to claim 1, characterized in that the width of the slit is 5.0 times or less the thickness of the plate portion of the surface on which the slit is formed.

3. The collision energy absorbing component for automobiles according to claim 1 or 2, characterized in that the spacing between the plurality of slits is 1.0 times or more and 1.5 times or less the minimum side length of the polygon.

Images