Side sill structure and undercarriage of an automobile

Abstract

This invention provides a side sill structure and an undercarriage structure for automobiles that allow for greater freedom in shaping the impact-absorbing members and achieve high resistance to side collisions. The vehicle body 1 comprises a side sill 15 and an impact absorbing member 30. The impact absorbing member 30 is formed of a plurality of members 31, 32. The impact absorbing member 30 comprises a hat-shaped portion 40 having a first top plate portion 41 and a pair of vertical wall portions 45, 46, and a second top plate portion 42 connecting the pair of vertical wall portions 45, 46. The second top plate portion 42 divides the inner space of the hat-shaped portion 40 in the width direction X, thereby forming a first closed cross section 61 including the first top plate portion 41, and a second closed cross section 62 adjacent to the first closed cross section 61 in the width direction X. The impact absorbing member 30 is either separated from the side sill outer 21, or it is in contact with the side sill outer 21 without being joined to it.

Description

Technical Field

[0001] The present disclosure relates to a side sill structure and an underbody structure of a vehicle.

Background Art

[0002] The body of a passenger car, which is a type of vehicle, usually has a center pillar arranged along the vertical direction of the body and a side sill connected to the lower part of the center pillar and arranged along the longitudinal direction of the body (see, for example, Patent Documents 1 to 3). When a passenger car is involved in a side collision, the center pillar and the side sill cooperate to receive an impact load, absorb the impact, and protect the occupants in the passenger compartment (cab).

[0003] In Patent Document 1, in order to effectively absorb the impact energy during a side collision, reinforcing members are arranged inside the side sill. This reinforcing member includes a pair of transverse walls extending in the vehicle width direction and arranged apart from each other in the vehicle vertical direction, a pair of longitudinal walls arranged apart from each other in the vehicle width direction and connected to the pair of transverse walls, and a plurality of intermediate longitudinal walls arranged between the pair of longitudinal walls in the vehicle width direction and connected to the pair of transverse walls. This reinforcing member is an integrally formed product made of an aluminum extrusion profile.

[0004] The vehicle side sill described in Patent Document 2 includes a side sill frame formed to have a hollow portion, a first reinforcing frame arranged in the hollow portion and joined to the side sill frame, and a second reinforcing frame arranged in the hollow portion and joined to the first reinforcing frame and the side sill frame. The first reinforcing frame and the second reinforcing frame are hat members, and the first reinforcing frame and the second reinforcing frame are arranged side by side in order from the inner side in the vehicle width direction. The second reinforcing frame is joined to the second side sill frame on the outer side in the vehicle width direction of the side sill frame.

[0005] The vehicle side sill described in Patent Document 3 includes a side sill inner panel, a side sill outer panel coupled to the side sill inner panel, and a first buffer member positioned between these panels and constituting a plurality of closed sections aligned in the width direction of the side sill. The first buffer member includes a main body formed by bending a single sheet of material, and at least one partition member connecting both sides of the main body. The main body is formed in a hat shape. The top plate of the main body is joined to the side sill outer panel. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-066315 [Patent Document 2] Special Publication No. 2024-524258 [Patent Document 3] Special Publication No. 2023-541988 [Overview of the project] [Problems that the invention aims to solve]

[0007] In electric vehicles (BEVs), the battery for the electric motor that drives the vehicle is sometimes located between the left and right side sills at the bottom of the vehicle body. The battery is housed in a battery box. In the event of a side collision, there is a growing demand for higher collision safety performance to protect the battery and to cope with the increased collision energy due to the recent increase in battery weight. This demand for higher collision safety performance is not limited to electric vehicles; it also applies to automobiles that transmit the output of an internal combustion engine directly to the wheels. For this reason, it is preferable that the reinforcing members (impact-absorbing members) within the side sills be shaped to be more suitable depending on the vehicle type and other factors.

[0008] However, the reinforcing member described in Patent Document 1 is a single-piece molded product by extrusion molding, so it has little freedom in shaping. Also, in Patent Documents 2 and 3, the impact absorbing members placed inside the side sill are joined to the side sill outer. As a result, in the event of a side collision, the impact absorbing member is easily deformed along with the deformation of the side sill outer. Therefore, there is a possibility that the impact absorbing member may not be able to generate the deformation intended when it was designed, and there is room for improvement in side collision resistance performance.

[0009] In view of the above-mentioned issues, one of the purposes of this disclosure is to provide a side sill structure and an undercarriage structure for an automobile that can achieve a greater degree of freedom in setting the shape of the impact absorbing member and can achieve high side impact resistance. [Means for solving the problem]

[0010] This disclosure outlines the following side sill structure and the undercarriage structure of an automobile.

[0011] (1) A side sill comprising a side sill outer and a side sill inner positioned inward in the vehicle width direction relative to the side sill outer, extending in the vehicle longitudinal direction and forming a closed cross-sectional space in a cross section perpendicular to the vehicle longitudinal direction, An impact-absorbing member formed from multiple members, Equipped with, The impact absorbing member comprises, in its cross-section, a hat-shaped portion having a first top plate portion extending in the vehicle height direction, and a pair of vertical wall portions extending from both ends of the first top plate portion in the vehicle height direction along the vehicle width direction, and a second top plate portion arranged at a distance from the first top plate portion in the vehicle width direction and connecting the pair of vertical wall portions. The second top plate portion divides the inner space of the hat-shaped portion in the vehicle width direction, thereby forming a first closed section portion including the first top plate portion and a second closed section portion adjacent to the first closed section portion in the vehicle width direction. The impact absorbing member is either separated from the side sill outer or in contact with the side sill outer without being joined to it, in a side sill structure.

[0012] (2) The impact absorbing member is formed by combining a first hat member and a second hat member, The side sill structure according to (1), wherein the top plate portion of the first hat member constitutes the first top plate portion, the top plate portion of the second hat member constitutes the second top plate portion, and a pair of first portions which are a pair of vertical wall portions of the first hat member and a pair of second portions which are a pair of vertical wall portions of the second hat member cooperate to form a pair of the vertical wall portions.

[0013] (3) The side sill structure according to (2), wherein the Vickers hardness of the first hat member is lower than that of the second hat member.

[0014] (4) The side sill structure according to (2), wherein the Vickers hardness of the first hat member is higher than that of the second hat member.

[0015] (5) The side sill structure according to any one of (2) to (4) above, wherein the thickness of the first hat member is smaller than the thickness of the second hat member.

[0016] (6) The side sill structure according to any one of (2) to (4) above, wherein the thickness of the first hat member is greater than the thickness of the second hat member.

[0017] (7) With respect to the Vickers hardness HV1 and plate thickness t1 of the first hat member and the Vickers hardness HV2 and plate thickness t2 of the second hat member, 180 ≤ HV1, HV2 ≤ 780, 0.8mm≦t1 t2≦2.3mm, HV1×t1 <HV2×t2 The side sill structure described in any one of the above paragraphs (2) to (6).

[0018] (8) The shock absorption member includes a hat member forming the hat-shaped portion and a top plate member forming the second top plate portion, and is the side sill structure according to (1) above.

[0019] (9) Regarding the Vickers hardness HV2 and plate thickness t2 of the hat member and the Vickers hardness HV1 and plate thickness t1 of the top plate member, 180 ≦ HV1, HV2 ≦ 780, 0.8 mm ≦ t1 t2 ≦ 2.3 mm, HV1 × t1 < HV2 × t2 and is the side sill structure according to (8) above.

[0020] (10) The second top plate portion of the shock absorption member has a shape that protrudes toward the first top plate portion side in the cross section, and is the side sill structure according to any one of (1) to (9) above.

[0021] (11) The shock absorption member is made of a steel plate, and is the side sill structure according to any one of (1) to (10) above.

[0022] (12) The hat-shaped portion includes a pair of flanges extending from the pair of vertical wall portions, and the pair of flanges are joined to the side sill inner, and is the side sill structure according to any one of (1) to (11) above.

[0023] (13) A bead is formed on the shock absorption member, and is the side sill structure according to any one of (1) to (12) above.

[0024] (14) The shock absorption member is supported by the side sill in the closed cross-sectional space or is arranged on the side of the side sill in the vehicle width direction, and is the side sill structure according to any one of (1) to (13) above.

[0025] (15) The first hat member includes a pair of first flanges, a pair of first vertical wall portions extending from the pair of first flanges, and a first top plate portion connecting the pair of first vertical wall portions, The side sill structure according to any one of (2) to (7) above, wherein the second hat member includes a pair of second flanges, a pair of second vertical wall portions extending from the pair of second flanges, and a second top plate portion connecting the pair of second vertical wall portions and joined to the pair of first flanges.

[0026] (16) The side sill structure according to any one of (2) to (7) and (15), wherein at least one of the hat members further comprises a reinforcing member.

[0027] (17) The impact absorbing member further comprises an nth (n is a natural number of 3 or more) hat member formed in a hat shape in the cross-section, The n-th hat member includes a pair of n-th flanges, a pair of n-th vertical wall portions extending from the pair of n-th flanges, and an n-th top plate portion connecting the pair of n-th vertical wall portions. The side sill structure according to any one of (2) to (7) and (15) to (16), wherein each of the hat members is arranged along the vehicle width direction, and in adjacent hat members, the top plate portion and a pair of flanges are joined to each other.

[0028] (18) The side sill structure according to any one of the above items (1) to (17), wherein the impact absorbing member is made of steel plate.

[0029] (19) A side sill structure as described in any one of items (1) to (18) above, The side sills are provided in pairs, spaced apart in the vehicle width direction. The vehicle further comprises a plurality of cross members positioned between a pair of side sills and extending in the vehicle width direction, An undercarriage of an automobile, wherein the impact-absorbing members are provided inside each of the pair of side sills or on the inside in the vehicle width direction.

[0030] (20) The undercarriage of an automobile according to (19), further comprising a battery case located below the cross member and housing a battery. [Effects of the Invention]

[0031] According to this disclosure, the degree of freedom in setting the shape of the impact absorbing member can be increased, and high side impact resistance can be achieved. [Brief explanation of the drawing]

[0032] [Figure 1] Figure 1 is an exploded perspective view showing a part of the body of an automobile equipped with a substructure including a side sill structure according to the first embodiment of this disclosure. [Figure 2] Figure 2 is a cross-sectional view of the substructure along the line II-II in Figure 1. [Figure 3] Figure 3 is a schematic cross-sectional view showing the main part of a first modified example of the first embodiment of the present disclosure. [Figure 4] Figure 4 is a schematic perspective view showing the main parts of a third modification of the first embodiment of the present disclosure. [Figure 5] Figure 5 is a cross-sectional view showing the main part of a fourth modified example of the first embodiment of the present disclosure. [Figure 6] Figure 6 is a cross-sectional view showing the main part of a fifth modified example of the first embodiment of the present disclosure. [Figure 7] Figure 7 is a cross-sectional view showing a major part of one of the other modifications of the first embodiment of the present disclosure. [Figure 8] Figure 8 is an exploded perspective view showing a portion of the body of an automobile equipped with a substructure including a side sill structure according to the second embodiment of this disclosure. [Figure 9] Figure 9 is a cross-sectional view of the substructure along the IX-IX line in Figure 8. [Figure 10] Figure 10 is a schematic cross-sectional view showing the main part of the first modified example of the second embodiment of the present disclosure. [Figure 11]Figure 11 is a schematic cross-sectional view showing the main part of a second modification of the second embodiment of the present disclosure. [Figure 12] Figure 12 is a schematic cross-sectional view showing the main part of a third modification of the second embodiment of the present disclosure. [Figure 13] Figure 13 is a schematic cross-sectional view showing the main part of a fourth modification of the second embodiment of the present disclosure. [Figure 14] Figure 14 is a schematic cross-sectional view showing the main part of a fifth modification of the second embodiment of the present disclosure. [Figure 15] Figure 15 is a drawing of a modified example of the fifth modified example of the second embodiment. [Figure 16] Figure 16 is a schematic cross-sectional view showing the main part of a sixth modified example of the second embodiment of the present disclosure. [Figure 17] Figure 17 shows a modified example of the sixth modified example of the second embodiment. [Figure 18] Figure 18 is a schematic cross-sectional view showing the main part of a seventh modification of the second embodiment of the present disclosure. [Figure 19] Figure 19 is a schematic cross-sectional view showing the main part of the eighth modified example of the second embodiment of the present disclosure. [Figure 20] Figure 20 is a schematic cross-sectional view showing the main part of the ninth modification of the second embodiment of the present disclosure. [Figure 21] Figure 21 is a schematic cross-sectional view showing the main part of the tenth modified example of the second embodiment of the present disclosure. [Figure 22] Figure 22 is a schematic cross-sectional view showing the main part of the 11th modified example of the second embodiment of the present disclosure. [Figure 23] Figure 23 is a diagram illustrating a modified example of the 11th modified example of the second embodiment. [Figure 24] Figure 24 is a schematic cross-sectional view showing the main part of the twelfth modification of the second embodiment of the present disclosure. [Figure 25] Figure 25 is a schematic cross-sectional view showing the main part of the 14th modified example of the second embodiment of the present disclosure. [Figure 26] Figure 26 is a schematic perspective view showing the main parts of a 14th modified example of the second embodiment of the present disclosure. [Modes for carrying out the invention]

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In this embodiment, a vehicle body structure applied to an automobile will be described.

[0034] [First Embodiment] (Vehicle body) Figure 1 is an exploded perspective view showing a part of the body 1 of an automobile equipped with a substructure 2 including a side sill structure 14 according to the first embodiment of this disclosure. Figure 2 is a cross-sectional view of the substructure 2 along the line II-II in Figure 1. Note that Figure 2 shows the battery case 100 fixed to the substructure 2, and the rear side of the cross section is omitted. In this specification, the direction along the direction of travel of the vehicle body 1 is defined as the longitudinal direction Y of the vehicle body, the direction of travel of the vehicle body is defined as the front, the opposite side as the rear, the vertical direction of the vehicle body is defined as the height direction Z, and the direction perpendicular to the longitudinal direction Y and the height direction Z is defined as the width direction X of the vehicle body. In addition, in the width direction X, the direction away from the center of the vehicle body 1 is defined as the outward direction, and the opposite direction is defined as the inward direction.

[0035] As shown in Figures 1 and 2, the vehicle body 1 is part of a vehicle, and a vehicle can be an automobile. An example of an automobile is a passenger car. Examples of passenger cars include sedan-type passenger cars, coupe-type passenger cars, hatchback-type passenger cars, minivan-type passenger cars, and SUV (Sport Utility Vehicle)-type passenger cars. Furthermore, the vehicle may be an electric vehicle (Battery Electric Vehicle) or a hybrid vehicle (HV, Hybrid Vehicle) including a plug-in hybrid vehicle, and the drive wheels can be driven by electricity from a battery 101 installed at the bottom of the vehicle body 1.

[0036] The vehicle body 1 comprises a frame 10 and a battery case 100.

[0037] The frame 10 includes a front pillar 11, a roof pillar 12, a center pillar 13, a side sill structure 14 including a side sill 15, floor cross members 16, 17, and a floor panel 18.

[0038] The front pillar 11, the roof pillar 12, the center pillar 13, and the side sill structure 14, including the side sill 15, are provided in pairs, spaced apart in the width direction X.

[0039] The front pillar 11 has a pillar upper 11a that extends upward and backward and is connected to the roof pillar 12, and a pillar lower 11b that is located below the pillar upper 11a.

[0040] The roof pillar 12 is located on the roof portion of the vehicle body 1 and extends rearward from the pillar upper 11a.

[0041] The center pillar 13 is positioned along the height direction Z and connects the roof pillar 12 and the side sill 15.

[0042] The side sill 15 is located at the lower part of the outer portion of the vehicle body 1 in the width direction X. The side sill 15 is connected to the lower part of the center pillar 13 and is positioned along the longitudinal direction Y of the vehicle body 1. The side sill 15 has a closed cross-sectional shape in a cross section perpendicular to the longitudinal direction Y.

[0043] The floor cross members 16 and 17 are members that extend in the width direction X and are positioned between a pair of left and right side sills 15 and 15, connecting these side sills 15 and 15. The floor cross members 16 and 17 are positioned on the front seat side of the passenger compartment (cabin) formed by the vehicle body 1. The floor cross members 16 and 17 are spaced apart in the longitudinal direction Y, with floor cross member 17 positioned behind floor cross member 16. The cross shape of each floor cross member 16 and 17 perpendicular to the width direction X is hat-shaped, and they work together with the floor panel 18 to form a closed cross shape. The floor panel 18 forms the bottom of the cabin of the vehicle body 1 and is fixed to the floor cross members 16 and 17.

[0044] Slide rails (not shown) are installed on floor cross members 16 and 17. The slide rails support seats (not shown) on which occupants sit.

[0045] A plate-shaped floor panel 18 is installed below the floor cross members 16 and 17. A battery case 100 is installed below the floor panel 18. The battery case 100 houses a battery 101, including a lithium-ion battery or the like.

[0046] The side sill 15 is positioned outside the battery 101 in the width direction X to protect the battery 101 from side collisions (pole side impacts) with utility poles, etc. The side sill 15 extends along the front-rear direction Y. The battery case 100 is fixed to the side sill 15. In this embodiment, the widthwise end 100a of the battery case 100 is fixed to, for example, the lower wall 224 of the side sill inner 22, which will be described later, of the side sill 15. In the middle portion of the battery case 100 in the width direction X, a side wall 100b is formed, for example, rising upward from the widthwise end 100a, as a protective wall for the battery 101. The battery 101 is positioned inside the width direction X relative to the side wall 100b. A gap A is formed between the side wall 100b and the side sill inner 22. The gap A varies depending on the vehicle model, but a value of several millimeters to several tens of millimeters can be exemplified.

[0047] (Side sill structure) When describing the side sill structure 14, unless otherwise specified, the configuration in a cross-section perpendicular to the longitudinal direction Y will be described. The side sill structure 14 is provided in pairs, spaced apart in the width direction X.

[0048] Each side sill structure 14 includes the side sill 15 described above and the impact absorbing member 30.

[0049] The side sill 15 comprises a side sill outer 21 and a side sill inner 22 positioned inward in the width direction X relative to the side sill outer 21.

[0050] The side sill outer 21 and the side sill inner 22 are each formed in a hat shape and work together to form a closed cross-sectional space 23 in the side sill 15.

[0051] The side sill outer 21 has a shape that opens inward in the width direction X, and the side sill inner 22 has a shape that opens outward in the width direction X. The side sill outer 21 and the side sill inner 22 are fixed to each other by joining means such as welding or fastening members, with their flanges 211, 221; 215, 225 butted against each other. In this embodiment, the side sill outer 21 and the side sill inner 22 are joined to each other, for example, by welding. Various welding methods can be used, such as spot welding, TIG welding, arc welding, laser welding, and plasma welding. The same applies to the welding method when joining other parts.

[0052] More specifically, the side sill outer 21 includes an upper flange 211, an upper wall 212 extending outward from the upper flange 211 in the width direction X, a side wall 213 extending downward from the upper wall 212, a lower wall 214 extending inward from the side wall 213 in the width direction X, and a lower flange 215 extending downward from the lower wall 214.

[0053] The side sill inner 22 includes an upper flange 221, an upper wall 222 extending inward from the upper flange 221 in the width direction X, a side wall 223 extending downward from the upper wall 222 and joined to the floor cross members 16 and 17, a lower wall 224 extending outward from the side wall 223 in the width direction X, and a lower flange 225 extending downward from the lower wall 224.

[0054] The upper flanges 211 and 221 are joined to each other using the joining method described above. Similarly, the lower flanges 215 and 225 are joined to each other using the joining method described above.

[0055] The upper wall 212 and lower wall 214 of the side sill outer 21 are inclined such that the distance between them in the height direction Z decreases as they extend outward in the width direction X. In this embodiment, the inclination angles of the upper wall 212 and lower wall 214 with respect to the horizontal plane are greater than the inclination angles of the upper wall 222 and lower wall 224 of the side sill inner 22 with respect to the horizontal plane. Also in this embodiment, the length of the side sill outer 21 in the width direction X is greater than the length of the side sill inner 22 in the width direction X. With this configuration, in the closed cross-sectional space 23, the space on the side sill outer 21 side is larger than that of the side sill inner 22. Also in this embodiment, the length of the side wall 213 of the side sill outer 21 in the height direction Z is less than the length of the side wall 223 of the side sill inner 22 in the height direction Z. With this configuration, the side sill 15 forms a closed cross-sectional space 23 that protrudes outward in the width direction X.

[0056] Furthermore, the side sill 15 may have a shape that is symmetrical in the width direction X, and its specific shape is not limited.

[0057] (Main components of the shock-absorbing material) The impact absorbing member 30 absorbs the impact energy of a side collision by plastically deforming in cooperation with the side sill 15 during a side collision.

[0058] The shock-absorbing member 30 is formed of a plurality of members (in this embodiment, a first hat member 31 and a second hat member 32).

[0059] The impact-absorbing member 30 comprises a hat-shaped portion 40 having a first top plate portion 41 extending in the height direction Z, and a pair of vertical wall portions 45, 46 extending along the width direction X from both ends of the first top plate portion 41 in the height direction Z, and a second top plate portion 42 which is spaced apart from the first top plate portion 41 in the width direction X and connects the pair of vertical wall portions 45, 46.

[0060] The second top plate portion 42 divides the inner space of the hat-shaped portion 40 in the width direction X, thereby forming a first closed section portion 61 including the first top plate portion 41, and a second closed section portion 62 adjacent to the first closed section portion 61 in the width direction X. The shock-absorbing member 30 is either separated from the side sill outer 21, or it is in contact with the side sill outer 21 without being joined to it.

[0061] (Effects of the main components of the shock-absorbing material) Because the impact absorbing member 30 has the above-described configuration, the timing of deformation initiation and the manner of deformation of the first closed section 61 and the second closed section 62 can be set during a side collision. This allows the impact absorbing operation of the impact absorbing member 30 during a side collision to be set according to the characteristics of the vehicle (such as the presence or absence of the battery case 100 and the layout of the battery case 100). Therefore, a higher level of side collision resistance can be achieved for the vehicle. Moreover, since the impact absorbing member 30 is formed from multiple members (in this embodiment, the first hat member 31 and the second hat member 32), the degree of freedom in shape setting can be increased compared to when the impact absorbing member 30 is formed from a single member.

[0062] (Detailed example of shock-absorbing component configuration) The impact absorbing member 30 is provided with multiple closed sections (in this embodiment, two closed sections 61 and 62) in the width direction X, so that during a side collision the multiple closed sections 61 and 62 are crushed in stages to absorb more impact energy. The impact absorbing member 30 is also formed by combining multiple members (in this embodiment, two hat members 31 and 32). By combining the strength (tensile strength) and plate thickness of each member 31 and 32, the crushing characteristics of each closed section 61 and 62 can be set to a desired state. For example, one hat member 31 may crush relatively large during a side collision to absorb impact, while the other hat member 32 may crush relatively less during a side collision to suppress the amount of inward penetration in the width direction of the side sill 15, etc.

[0063] In this embodiment, the shock-absorbing member 30 is formed in a uniform shape in the front-rear direction Y across its entire area, but the shape may differ in different parts in the front-rear direction Y. In this embodiment, the shock-absorbing member 30 is formed in a shape that is convex outward in the width direction X, but it may also be formed in a shape that is convex inward in the width direction X (a shape symmetrical with respect to the width direction X to the shape shown in Figure 2). The shock-absorbing member 30 may be installed over the entire area where the side sill 15 is located in the front-rear direction Y, or it may be installed in only a part of it. In this embodiment, the shock-absorbing member 30 is arranged continuously from the front end 15a to the rear end 15b of the side sill 15.

[0064] Preferably, the impact absorbing member 30 is positioned at least at a location facing the floor cross members 16 and 17 in the width direction X. With this configuration, the impact from the impact absorbing member 30 can be efficiently transmitted to the floor cross members 16 and 17 during a side collision. Therefore, it is possible to suppress the impact absorbing member 30 from pressing against the battery case 100 via the side sill inner 22. Thus, the performance of protecting the battery case 100 can be improved. In this embodiment, the impact absorbing member 30 is formed in a vertically symmetrical shape, but it may also be vertically asymmetrical. Since the impact absorbing member 30 is formed from multiple members, it is possible to manufacture the impact absorbing member 30 whether it is vertically symmetrical or vertically asymmetrical.

[0065] In this embodiment, the impact absorbing member 30 is supported by the side sill 15 within the closed cross-sectional space 23 of the side sill 15. Specifically, the impact absorbing member 30 is positioned between the side wall 213 of the side sill outer 21 and the side wall 223 of the side sill inner 22. In this embodiment, the impact absorbing member 30 has a tapered shape in which the length in the height direction Z decreases as it moves outward in the width direction X. The impact absorbing member 30 is elongated in the width direction X, and its length in the width direction X is greater than its length in the height direction Z.

[0066] The first top plate portion 41 suppresses out-of-plane deformation of the pair of vertical wall portions 45 and 46 connected to the first top plate portion 41. Furthermore, the first top plate portion 41 is the part of the impact absorbing member 30 that first receives the impact load during a side collision.

[0067] In this embodiment, the first top plate portion 41 is adjacent to the side wall 213 of the side sill outer 21, but it is preferable that it is separated from the side sill outer 21.

[0068] With such a favorable configuration, the work of installing the shock-absorbing member 30 inside the side sill 15 is easier. This is because the work of joining the first top plate portion 41 to the side wall 213 of the side sill outer 21 becomes unnecessary. If the first top plate portion 41 were to be joined to the side wall 213 of the side sill outer 21 by welding, the welding machine would need to be sandwiched between the first top plate portion 41 and the side wall 213. Therefore, the work of installing the shock-absorbing member 30 inside the side sill 15 would be time-consuming. This time-consuming process exists regardless of whether the welding method is spot welding, laser welding, or adhesive bonding.

[0069] Furthermore, with such a favorable configuration, during a side collision of a vehicle, the impact absorbing member 30 can perform a two-stage crushing process by sequentially crushing the two closed cross-sections 61 and 62 while minimizing the influence of the side sill outer 21, thereby increasing the efficiency of impact energy absorption. In other words, during a side collision of a vehicle, the impact absorbing member 30 can deform and absorb the impact while being less affected by the deformation of the side sill outer 21. This allows the impact absorbing member 30 to exhibit its impact absorption performance more effectively.

[0070] Furthermore, with such a favorable configuration, when a relatively minor side collision occurs to the vehicle, deformation of the components due to the transmission of impact from the side sill outer 21 to the impact absorbing member 30 and the side sill inner 22 can be suppressed. When a relatively minor side collision occurs to the vehicle, an impact acts on the side sill outer 21, but only a small amount of this impact is transmitted from the side sill outer 21 to the impact absorbing member 30. Therefore, less impact is transmitted to the side sill inner 22 via the impact absorbing member 30. In such a case, the amount of deformation of the side sill 15 is reduced, so a decrease in the vehicle's driving performance (straight-line performance, etc.) can be suppressed. In addition, when repairing the vehicle, while the side wall 213 etc. of the side sill outer 21 need to be repaired, the impact absorbing member 30 and the side sill inner 22 do not need to be repaired, thus reducing the effort and cost of vehicle maintenance. On the other hand, when a large side collision occurs to the vehicle, the impact is transmitted from the side sill outer 21 to the side sill inner 22 via the impact absorbing member 30, enabling efficient absorption of impact energy through deformation of the impact absorbing member 30 and the side sill inner 22.

[0071] Furthermore, with such a favorable configuration, vibration noise caused by contact between the first top plate portion 41 and the side sill outer 21 can be suppressed, while the impact load from the side sill outer 21 during a side collision can be transmitted to the impact absorbing member 30 along with the crushing of the side sill outer 21. It is preferable that the first top plate portion 41 is arranged parallel to the side wall 213, as this allows the entire first top plate portion 41 to receive the impact load from the side wall 213 of the side sill outer 21.

[0072] In this embodiment, the first top plate portion 41 is the shortest portion of the impact-absorbing member 30 in the height direction Z. The boundary between the first top plate portion 41 and each of the vertical wall portions 45, 46 is formed in a curved shape.

[0073] The pair of vertical wall sections 45 and 46 are arranged along the width direction X, and the distance between the pair of vertical wall sections 45 and 46 widens as it moves toward the side sill inner 22. This layout of the pair of vertical wall sections 45 and 46 allows the impact load acting inward from the side sill outer 21 in the width direction X to be evenly distributed between the upper and lower parts of the impact absorbing member 30. Therefore, the amount of impact energy absorbed by the impact absorbing member 30 can be increased during a side collision. The pair of vertical wall sections 45 and 46 may also be arranged parallel (horizontally) to the width direction X.

[0074] The first top plate portion 41 is connected to the ends of each of the pair of vertical wall portions 45 and 46 in the width direction X, while flanges 47 and 48 are connected to the base ends of the pair of vertical wall portions 45 and 46.

[0075] The flanges 47 and 48 are provided on the hat-shaped portion 40 and extend from a pair of vertical wall portions 45 and 46. The flanges 47 and 48 are the portions that are joined to the side sill 15, and in this embodiment, they are joined to the inner surface of the side sill inner 22 by the joining method described above. The flanges 47 and 48 do not have to be directly joined to the side sill inner 22, and may be joined to the side sill inner 22 via other members.

[0076] In this configuration, the pair of flanges 47 and 48 of the hat-shaped portion 40 are joined to the side sill inner 22. With this configuration, during a side collision, the impact load acting on the first top plate portion 41 can be transmitted from the side sill inner 22 to the floor cross members 16 and 17 with high transmission efficiency. Therefore, the cooperation of the side sill 15, the impact absorbing member 30, and the floor cross members 16 and 17 allows for the absorption of more impact energy. As a result, collision of the side sill 15 with the battery case 100 during a side collision can be suppressed.

[0077] Flange 47 extends upward from the upper vertical wall portion 45, and flange 48 extends downward from the lower vertical wall portion 46. In the hat-shaped portion 40, these flanges 47 and 48 are spaced apart from each other, and the hat-shaped portion 40 has an inward shape in the width direction X that is open to the side sill inner 22 side. In this way, it is preferable that the impact absorbing member 30 is joined to the side sill 15 only by flanges 47 and 48, and that no other part of the impact absorbing member 30 is positioned between flanges 47 and 48 in the height direction Z. With such a configuration, the impact absorbing member 30 can be made lighter. Also, when spot welding the side sill inner 22 and the impact absorbing member 30, the flanges 47 and 48, which are positioned outward in the height direction Z relative to the pair of vertical wall portions 45 and 46, and the side sill inner 22 can be sandwiched between the welding machine and welded. Thus, in this embodiment, there are outward-facing flanges 47 and 48 that are positioned outward in the height direction Z relative to the pair of vertical wall portions 45 and 46.

[0078] Alternatively, instead of flanges 47 and 48, an inward-facing flange can be provided between the base ends of a pair of vertical wall sections 45 and 46, positioned inward in the height direction Z relative to the pair of vertical wall sections 45 and 46. In this case, the inward-facing flange has a portion extending downward from the base end of the vertical wall section 45 and a portion extending upward from the base end of the vertical wall section 46. These portions are integrally formed, so that a plate-like portion (a single inward-facing flange) is provided between the base ends of the vertical wall sections 45 and 46. If this plate-like portion is joined to the side sill inner 22, it is difficult to clamp the plate-like portion and the side sill inner 22 with a welding machine. Therefore, it is necessary to join the plate-like member and the side sill inner 22 with additional materials such as adhesive, which reduces the degree of freedom in setting the joining method between the shock-absorbing member and the side sill inner 22.

[0079] Furthermore, as in this embodiment, it is preferable that the flanges 47 and 48 of the impact absorbing member 30 are joined to the side wall 223 of the side sill inner 22, rather than being positioned between the flanges 211 and 221 and between the flanges 215 and 225 of the side sill 15. With this preferred configuration, it is not necessary to sandwich the flanges 47 and 48 of the impact absorbing member 30 between the flanges 211, 221; 215, and 225 of the side sill 15, and the difficult alignment work of welding three or more plate-like members is not required for joining the impact absorbing member 30. In addition, there are cases where flanges 211, 221; 215, and 225 are not provided near the front end 15a, near the center pillar 13, and near the rear end 15b of the side sill 15. Even in such cases, the flanges 47 and 48 of the impact absorbing member 30 can be joined to the side sill 15 near the front end 15a, near the center pillar 13, and near the rear end 15b of the side sill 15.

[0080] The second top plate portion 42 suppresses out-of-plane deformation such that the pair of vertical wall portions 45 and 46 connected to the second top plate portion 42 tilt inward. The second top plate portion 42 is positioned between the inner surfaces of the pair of vertical wall portions 45 and 46. The second top plate portion 42 is positioned parallel to the first top plate portion 41.

[0081] The second top plate portion 42 is positioned in the middle of the pair of vertical wall portions 45, 46 in the direction of their rise (width direction X). This configuration allows the pair of vertical wall portions 45, 46 to be separated by the second top plate portion 42. In other words, in the width direction X, the portion of each vertical wall portion 45, 46 that is on the outside of the vehicle and the portion that is on the inside of the vehicle can be shortened relative to the second top plate portion 42. As a result, out-of-plane deformation of the pair of vertical wall portions 45, 46 during a side collision can be suppressed, and the amount of energy absorbed by wall buckling can be increased.

[0082] In this embodiment, the second top plate portion 42 is positioned closer to the side sill outer 21 than the side sill inner 22. As a result, in the width direction X, the length from the first top plate portion 41 to the second top plate portion 42 is shorter than the length from the second top plate portion 42 to the side wall 223 of the side sill inner 22. In particular, in this embodiment, the second top plate portion 42 is located outside the width direction X with respect to the flanges 211, 221; 215, 225 which are the boundary between the side sill outer 21 and the side sill inner 22 in the width direction X.

[0083] Thus, the second top plate portion 42 is positioned closer to the side sill outer 21 than the side sill outer 21 and side sill inner 22. This reduces the space between the first top plate portion 41 and the second top plate portion 42 (the space within the first hat member 31). As a result, in the event of a side collision, out-of-plane deformation of the portion between the first top plate portion 41 and the second top plate portion 42 of the pair of vertical wall portions 45 and 46 (the first portions 45a and 46a of the pair of vertical wall portions 45 and 46) can be suppressed. Furthermore, in the event of a side collision, the first closed cross section portion 61 is crushed first, and then the second closed cross section portion 62 is crushed, allowing the impact load from the width direction X to be absorbed sequentially from the members positioned on the outside of the width direction X. By enabling such a smooth impact absorption operation, the efficiency of impact energy absorption by the impact absorbing member 30 can be increased.

[0084] With the above configuration, the first closed section 61 is formed of a first top plate portion 41, first portions 45a and 46a which are the tip portions of a pair of vertical wall portions 45 and 46, and a second top plate portion 42. The second closed section 62 is formed of a second top plate portion 42, second portions 45b and 46b which are the base portions of a pair of vertical wall portions 45 and 46, a pair of flanges 47 and 48, and the side wall 223 of the side sill inner 22.

[0085] In this embodiment, the impact absorbing member 30 is formed by combining a first hat member 31 and a second hat member 32.

[0086] The first hat member 31 and the second hat member 32 are both formed in a hat shape. The first hat member 31 comprises a first top plate portion 41, a pair of vertical wall portions 45 and 46, first portions 45a and 46a of those portions, and flanges 49 and 50 formed on these first portions 45a and 46a. The second hat member 32 comprises a second top plate portion 42, a pair of vertical wall portions 45 and 46, second portions 45b and 46b of those portions, and flanges 47 and 48.

[0087] The top plate portion of the first hat member 31 forms the first top plate portion 41, and the top plate portion of the second hat member 32 forms the second top plate portion 42. A pair of first portions 45a, 46a, which are the pair of vertical wall portions of the first hat member 31, and a pair of second portions 45b, 46b, which are the pair of vertical wall portions of the second hat member, cooperate to form a pair of vertical wall portions 45, 46 of the impact absorbing member 30. That is, the vertical wall portion 45 is formed by the first portion 45a and the second portion 45b, and the vertical wall portion 46 is formed by the first portion 46a and the second portion 46b.

[0088] In this way, the impact absorbing member 30 is formed by two hat members 31 and 32. With this configuration, the impact absorbing member 30 can be formed by a relatively simple configuration of combining two hat members 31 and 32. In addition, the degree of freedom in setting the shape of each of the two hat members 31 and 32 can be increased, resulting in a high degree of freedom in setting the shape of the impact absorbing member 30. Furthermore, the deformation patterns of the first hat member 31 and the second hat member 32 during a side collision can be made different, further increasing the degree of freedom in setting the impact absorbing action of the impact absorbing member 30.

[0089] In this embodiment, each first portion 45a, 46a of the first hat member 31 is aligned linearly with the corresponding second portion 45b, 46b of the second hat member 32. In this case, "aligned linearly" means that although there is a step difference equal to the thickness of the first portion 45a, 46a due to the overlapping of each first portion 45a, 46a and the corresponding second portion 45b, 46b, they are substantially aligned in a straight line.

[0090] This linear layout allows the impact load acting from the first top plate 41 to the impact absorbing member 30 during a side collision to be transmitted with high efficiency from the side sill inner 22 to the floor cross members 16 and 17. Therefore, the cooperation of the side sill 15, the impact absorbing member 30, and the floor cross members 16 and 17 allows for the absorption of more impact energy. As a result, collision of the side sill 15 with the battery case 100 can be suppressed.

[0091] In this embodiment, the base ends of the first portions 45a and 46a in the width direction X are flanges 49 and 50, which are joined to the tip portions of the second portions 45b and 46b. In this embodiment, each of the first portions 45a and 46a, including the flanges 49 and 50, is formed in a straight line, and the inner surfaces of the flanges 49 and 50 are joined to the outer surfaces of the second portions 45b and 46b. The flanges 49 and 50 of the first portions 45a and 46a and the second portions 45b and 46b are joined so that the first hat member 31 does not detach from the second hat member 32 even when a design impact load is applied to the impact absorbing member 30.

[0092] In this way, the inner surfaces of the pair of first portions 45a and 46a of the first hat member 31 are joined to the outer surfaces of the pair of second portions 45b and 46b of the second hat member 32. This makes it possible to achieve a configuration in which each of the first portions 45a and 46a and the corresponding second portions 45b and 46b are arranged in a straight line.

[0093] The length H1 of the first closed section 61 in the width direction X is smaller than the length H2 of the second closed section 62 in the width direction X (H2 > H1). The ratio H1 / H2 of these lengths is preferably 1 / 3 to 1 / 2. Within the above range of ratio H1 / H2, an extreme bias in the impact absorption effect caused by the crushing of the first hat member 31 and the impact absorption effect caused by the crushing of the second hat member 32 will not occur during a side collision, and the overall impact absorption efficiency of the impact absorbing member 30 can be increased.

[0094] Regarding the relationship between the length H1 of the first closed section 61 in the width direction X and the plate thickness t1 of the first hat member 31, the smaller H1 / t1 is, the more effectively out-of-plane deformation of the first hat member 31 during a side collision can be suppressed. Similarly, regarding the relationship between the length H2 of the second closed section 62 in the width direction X and the plate thickness t2 of the second hat member 32, the smaller H2 / t2 is, the more effectively out-of-plane deformation of the second hat member 32 during a side collision can be suppressed.

[0095] Next, the material and other specifications of the shock-absorbing member 30 will be described.

[0096] The impact absorbing member 30 is preferably made of steel plate. If the impact absorbing member is made of aluminum, for example, when the aluminum material is installed inside the steel side sill, galvanic corrosion (galvanic corrosion) will occur due to the contact between the dissimilar metals, aluminum and iron. Therefore, measures to prevent galvanic corrosion (rust prevention treatment) are necessary. On the other hand, if the impact absorbing member 30 is made of steel, the above-mentioned measures to prevent galvanic corrosion are unnecessary, and iron, which has a relatively low unit cost compared to aluminum, can be used, thereby reducing the manufacturing cost of the vehicle body 1.

[0097] In this embodiment, the first hat member 31 and the second hat member 32 of the impact absorbing member 30 are each made of steel plate. The tensile strength of each hat member 31, 32 can be exemplified as 780 MPa to 2.5 GPa, or 590 MPa to 2.5 GPa. The lower limit of the tensile strength of each hat member 31, 32 may be 980 MPa, 1.3 GPa, 1.5 GPa, 1.7 GPa, 2.0 GPa, or 2.3 GPa. The upper limit of the tensile strength of each hat member 31, 32 may be 1.5 GPa, 1.7 GPa, 2.0 GPa, or 2.3 GPa.

[0098] The tensile strength can be evaluated in accordance with JIS Z 2241:2011. A suitable test specimen for measuring tensile strength is the No. 5 specimen specified in JIS Z 2241:2011. The sampling location for the tensile test specimen can be, for example, the central portion of the pair of vertical wall sections 45 and 46 of each hat member 31 and 32.

[0099] The Vickers hardness corresponding to the tensile strength of each of the hat members 31 and 32 can be given as the Vickers hardness of each hat member 31 and 32. Examples of Vickers hardness HV1 and HV2 for each hat member 31 and 32 include 240 to 780. The lower limit of Vickers hardness HV1 and HV2 for each hat member 31 and 32 may be 180 corresponding to 590 MPa, 240 corresponding to 780 MPa, 300 corresponding to 980 MPa, 400 corresponding to 1.3 GPa, 460 corresponding to 1.5 GPa, 520 corresponding to 1.7 GPa, 620 corresponding to 2.0 GPa, or 710 corresponding to 2.3 GPa. Furthermore, the upper limits of the Vickers hardness HV1 and HV2 of each hat member 31 and 32 may be 460 corresponding to 1.5 GPa, 520 corresponding to 1.7 GPa, 620 corresponding to 2.0 GPa, 710 corresponding to 2.3 GPa, or 780 corresponding to 2.5 GPa.

[0100] The Vickers hardness of each hat member 31, 32 can be measured as follows. Vickers hardness (HV1) "HV1" refers to the "hardness symbol" when a Vickers hardness test is performed with a test force of 1 kgf (9.807 N) (JIS Z 2244-1:2020). The Vickers hardness is measured as follows. First, a sample for measurement is cut from a flat plate-shaped part such as the first top plate part 41 of the first hat member 31 so that the cut surface (measurement surface) is parallel to the thickness direction of the flat plate-shaped part, and the sample is embedded in resin and the cut surface is polished. Then, at a position that is 1 / 4 of the plate thickness from the surface of the sample on the cut surface (measurement surface), 10 points are measured at 0.5 mm intervals with a test force of 1 kgf (9.807 N) and the average is taken.

[0101] The Vickers hardness (HV2) "HV2" is a value obtained by cutting a sample for measurement from a flat plate-like portion such as the second top plate portion 42 of the second hat member 32, instead of the first top plate portion 41, and performing the above test.

[0102] In this embodiment, the tensile strength TS1 (Vickers hardness HV1) of the first hat member 31 is set lower than the tensile strength TS2 (Vickers hardness HV2) of the second hat member 32. That is, the strength of the side sill outer 21 side of the impact absorbing member 30 is lower than the strength of the side sill inner 22 side. With this configuration, the strength of the first top plate portion 41 is set lower than the strength of the second top plate portion 42.

[0103] With this tensile strength (Vickers hardness) setting, during a side impact, the first hat member 31 can begin to deform before the second hat member 32, thereby absorbing impact energy. Within the closed cross-sectional space 23, the first hat member 31, which is located on the side of the impact absorbing member 30 furthest from the battery case 100, deforms first, delaying the deformation timing of the second hat member 32, which is closer to the battery case 100. In other words, the deformation of the second hat member 32 can be suppressed until the first hat member 31 has deformed sufficiently. As a result, the amount of impact energy absorbed by the crushing of the first hat member 31 can be increased, and the side sill inner 22, which is crushed together with the crushing of the second hat member 32, can be prevented from contacting the side wall 100b of the battery case 100. Furthermore, because the second hat member 32 has high strength, the amount of impact energy absorbed by the second hat member 32 can be increased even further.

[0104] The tensile strength TS2 (Vickers hardness HV2) of the second hat member 32 is preferably about 1.3 to 1.7 times the tensile strength TS1 (Vickers hardness HV1) of the first hat member 31, with 1.5 times being an example. With this setting, the first hat member 31 can be crushed during a side impact, and the crushing of the second hat member 32 can begin only after the first hat member 31 has been sufficiently crushed. In addition, it is possible to suppress the occurrence of cracks in the first hat member 31, which is greatly crushed during a side impact, and the reduction in impact energy absorption efficiency. As a more specific value configuration, an example can be given in which the tensile strength TS1 of the first hat member 31 is 980 MPa and the tensile strength TS2 of the second hat member 32 is 1.5 GPa. In this configuration, the impact energy absorption value can be increased compared to when the tensile strengths TS1 and TS2 of each hat member 31 and 32 are the same.

[0105] Examples of plate thicknesses t1 and t2 for each hat member 31 and 32 include 0.8 mm to 2.3 mm, and also 1.4 mm to 2.3 mm. The plate thicknesses t1 and t2 for each hat member 31 and 32 may be the same or different, but a smaller thickness is preferable in terms of weight reduction. Examples of lower limits for plate thicknesses t1 and t2 for each hat member 31 and 32 include 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, and 2.2 mm. Examples of upper limits for plate thicknesses t1 and t2 for each hat member 31 and 32 include 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, and 2.2 mm.

[0106] In this embodiment, the plate thickness t1 of the first hat member 31 is set to be smaller than the plate thickness t2 of the second hat member 32.

[0107] The plate thickness t2 of the second hat member 32 is preferably about 1.3 to 1.7 times the plate thickness t1 of the first hat member 31, with 1.5 times being an example. By setting these plate thickness ratios t2 / t1 within the above range, the crushing of the second hat member 32 can be started after the first hat member 31 has been sufficiently crushed during a side impact.

[0108] While setting the tensile strength ratio TS2 / TS1 of each hat member 31, 32 to 1.3 to 1.7 (for example, 1.5), the plate thickness ratio t2 / t1 may be set to 1, or while setting the tensile strength ratio TS2 / TS1 of each hat member 31, 32 to 1, the plate thickness ratio t2 / t1 may be set to 1.3 to 1.7 (for example, 1.5).

[0109] The combination of the plate thicknesses t1, t2 and the tensile strengths TS1, TS2 of each hat member 31, 32 may be such that the first hat member 31 starts crushing earlier than the second hat member 32 during a side collision, and the crushing of the second hat member 32 starts after the first hat member 31 has been sufficiently crushed.

[0110] Regarding the Vickers hardness HV1 and the plate thickness t1 of the first hat member 31 and the Vickers hardness HV2 and the plate thickness t2 of the second hat member 32 180 ≦ HV1 HV2 ≦ 780 0.8 mm ≦ t1 t2 ≦ 2.3 mm, and HV1 × t1 < HV2 × t2 It is preferable that this is the case.

[0111] By setting 180 ≦ HV1, the strength of the first hat member 31 can be sufficiently ensured and the impact energy absorption efficiency can be increased. Also, by setting HV2 ≦ 780, cracking during deformation of the second hat member 32 can be suppressed and the impact energy absorption efficiency can be increased. Also, by setting 0.8 mm ≦ t1, the rigidity of the first hat member 31 can be sufficiently ensured and cracking of the first hat member 31 can be suppressed. Also, by setting t2 ≦ 2.3 mm, the second hat member 32 can be made lightweight. And by setting HV1 × t1 < HV2 × t2, the operation in which the first hat member 31 starts crushing earlier than the second hat member 32 during a side collision and the crushing of the second hat member 32 starts after the first hat member 31 has been sufficiently crushed can be made more reliable.

[0112] As the impact-absorbing member 30 is formed by multiple members 31 and 32, there is a high degree of freedom in selecting the Vickers hardness HV1 and HV2 for each of the multiple members 31 and 32, and in selecting the plate thickness t1 and t2.

[0113] With the above configuration, in this embodiment, the degree of freedom in setting the shape of the impact absorbing member 30 can be increased, and a side sill structure 14 and an automobile understructure 2 that can achieve high side impact resistance can be realized.

[0114] In particular, in this embodiment, since the impact absorbing members 30 are arranged on both sides (left and right sides) in the width direction X of the vehicle body 1, the impact energy absorption effect of the impact absorbing members 30 can be exerted regardless of whether the side collision occurs on the right or left side of the vehicle body 1.

[0115] Furthermore, the impact-absorbing member 30 positioned on the side of the battery case 100 provides an impact energy absorption effect, which prevents the gap A between the side sill inner 22 and the side wall 100b of the battery case 100 from disappearing during a side collision. As a result, contact between the side sill 15 and the side wall 100b of the battery case 100 can be prevented.

[0116] Embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the embodiments described above. Various modifications are possible within the scope of the claims. In the following, configurations different from the embodiments and modifications described above will be mainly described, and similar configurations will be denoted by the same reference numerals and detailed descriptions will be omitted.

[0117] [First modified example of the first embodiment] Figure 3 is a schematic cross-sectional view showing the main part of the first modification of the first embodiment of the present disclosure. In the embodiment, the second top plate portion 42 was positioned closer to the side sill outer 21 of the side sill outer 21 and side sill inner 22. On the other hand, in the first modification of the first embodiment, the second top plate portion 42 is positioned closer to the side sill inner 22 of the side sill outer 21 and side sill inner 22.

[0118] As a result, in the width direction X, the length from the first top plate portion 41 to the second top plate portion 42 is longer than the length from the second top plate portion 42 to the side sill inner 22.

[0119] This layout of the second top plate portion 42 allows for a larger space (first hat member 31) between the first top plate portion 41 and the second top plate portion 42. As a result, during a side collision, the amount of impact energy that can be absorbed by the first portions 45a and 46a of the pair of vertical wall portions 45 and 46 through crushing can be increased. Furthermore, during a side collision, by crushing the first closed cross section portion 61 first, and then the second closed cross section portion 62, the impact load from the width direction X can be absorbed sequentially from the members located on the outside of the width direction X. By enabling such a smooth impact absorption operation, the efficiency of impact energy absorption by the impact absorbing member 30 can be increased.

[0120] [Second modified example of the first embodiment] In the embodiment, an example was described in which the tensile strength TS1 (Vickers hardness HV1) of the first hat member 31 is lower than the tensile strength TS2 (Vickers hardness HV2) of the second hat member 32. However, this is not required. The tensile strength TS1 (Vickers hardness HV1) of the first hat member 31 may be higher than the tensile strength TS2 (Vickers hardness HV1) of the second hat member 32. In this case, an example can be given in which the tensile strength TS1 (Vickers hardness HV1) of the first hat member 31 and the tensile strength TS2 (Vickers hardness HV1) of the second hat member 32 are swapped in the embodiment. With such a configuration, the strength on the side sill outer 21 side of the impact absorbing member 30 can be increased compared to the strength on the side sill inner 22 side.

[0121] This configuration allows for a larger peak impact load acting on the first hat member 31 during a side collision, enabling the first hat member 31 to absorb more impact energy.

[0122] Furthermore, in a second modification of the first embodiment, a configuration can be exemplified in which the plate thickness t1 of the first hat member 31 and the plate thickness t2 of the second hat member 32 are swapped in the first embodiment. That is, the plate thickness t1 of the first hat member 31 may be greater than the plate thickness t2 of the second hat member 32. With such a configuration, the peak of the impact load acting on the first hat member 31 during a side collision can be made larger, allowing the first hat member 31 to absorb more impact energy.

[0123] [Third modified example of the first embodiment] Figure 4 is a schematic perspective view showing the main part of a third modification of the first embodiment of the present disclosure. A bead 70 is formed on the impact absorbing member 30 shown in Figure 4. The bead 70 may be formed on the first top plate portion 41 of the impact absorbing member 30, on a pair of vertical wall portions 45, 46, or on the second top plate portion 42. In the first modification, the bead 70 is formed on a pair of vertical wall portions 45, 46.

[0124] The bead 70 includes a first bead 71 formed on the first portions 45a and 46a of the pair of vertical wall portions 45 and 46, and a second bead 72 formed on the second portions 45b and 46b of the pair of vertical wall portions 45 and 46.

[0125] The first bead 71 is provided to enhance the impact absorption effect during side collisions by increasing the resistance of the impact absorbing member 30 to bending deformation. The first bead 71 extends in the front-rear direction Y, and the first portions 45a and 46a are formed with undulations in the height direction Z. In the third modification of this first embodiment, the first portions 45a and 46a are formed by recessing them inward into the closed cross-sectional space 23. Alternatively, the first bead 71 may be formed with the first portions 45a and 46a recessed outward from the closed cross-sectional space 23. One or more (two in this third modification) first beads 71 ​​are formed in the width direction X, and all have a uniform shape in the front-rear direction Y.

[0126] The second bead 72 is provided to suppress out-of-plane deformation in each vertical wall portion 45, 46 during a side collision. The second bead 72 extends in the width direction X, and the second portions 45b, 46b are formed by undulating in the height direction Z. In the first modified example, the second portions 45b, 46b are formed by recessing them inward into the closed cross-sectional space 23. Alternatively, the second bead 72 may be formed by recessing the second portions 45b, 46b outward into the closed cross-sectional space 23. Multiple second beads 72 are formed spaced apart in the front-rear direction Y.

[0127] The first bead 71 may be formed on the first top plate portion 41. Alternatively, a second bead 72 may be formed on the first portions 45a and 46a of the pair of vertical wall portions 45 and 46, or the first bead 71 may be formed on the second portions 45b and 46b. Furthermore, the bead 70 may be formed over the entire area of ​​the impact absorbing member 30 in the front-rear direction Y, or it may be formed only in the areas where the floor cross members 16 and 17 are located.

[0128] In this way, the formation of the bead 70 on the impact absorbing member 30 suppresses buckling of the impact absorbing member 30 during a side impact, resulting in the absorption of more impact energy.

[0129] Furthermore, a configuration in which multiple second beads 72 are formed spaced apart in the front-rear direction Y is difficult to achieve when manufacturing the impact absorbing member 30 by extrusion molding of an aluminum alloy. However, if the impact absorbing member 30 is made of steel plate, such second beads 72 can be formed.

[0130] [Fourth modified example of the first embodiment] Figure 5 is a cross-sectional view showing the main part of a fourth modification of the first embodiment of the present disclosure. In the above-described embodiment, the shock-absorbing member 30 was described as being formed by two hat members 31 and 32, but this is not required. In the fourth modification of the first embodiment, the shock-absorbing member 30 is formed by a hat member 35 and a second top plate member 36 as a top plate member installed inside the hat member 35.

[0131] The hat member 35 is formed in a hat shape and comprises a first top plate portion 41, a pair of vertical wall portions 45, 46, and flanges 47, 48. The hat member 35 forms the hat-shaped portion 40. In the fourth modification of this first embodiment, the pair of vertical wall portions 45, 46 are arranged in a tapered shape, with the distance between them narrowing as they move outward in the width direction X.

[0132] The second top plate member 36 is positioned between the inner surfaces of the pair of vertical wall portions 45 and 46. In this fourth modified example, the second top plate member 36 has a shape that is convex toward the first top plate portion 41.

[0133] The shape of the second top plate member 36 allows for increased efficiency in transmitting impact energy during a side collision, and also enhances the effect of suppressing out-of-plane deformation of the hat member 35.

[0134] More specifically, the second top plate member 36 comprises a second top plate portion 42 parallel to the first top plate portion 41, and flanges 37 and 38 provided at both ends of the second top plate portion 42 in the height direction Z and joined to the inner surfaces of a pair of vertical wall portions 45 and 46. The upper flange 37 is curved so as it approaches the upper vertical wall portion 45, it moves away from the first top plate portion 41. The lower flange 38 is curved so as it approaches the lower vertical wall portion 46, it moves away from the first top plate portion 41.

[0135] The tensile strength and thickness of the hat member 35 may be set in the same way as the tensile strength TS1 and thickness t1 of the first hat member 31 in the embodiment. The tensile strength and thickness of the second top plate member 36 may be set in the same way as the tensile strength TS2 and thickness t2 of the second hat member 32 in the embodiment.

[0136] Furthermore, regarding the Vickers hardness HV2 and plate thickness t2 of the hat member 35, and the Vickers hardness HV1 and plate thickness t1 of the second top plate member 36, 180 ≤ HV1, HV2 ≤ 780, 0.8mm≦t1 t2≦2.3mm, HV1×t1 <HV2×t2 It is preferable that this is the case. The meaning of each numerical value is the same as in the first embodiment. When these conditions are met, it is possible to more reliably ensure that the first closed section 61 starts to collapse before the second closed section 62 during a side collision, and that the second closed section 62 starts to collapse only after the first closed section 61 has been sufficiently collapsed.

[0137] [Fifth modified example of the first embodiment] Figure 6 is a cross-sectional view showing the main part of a fifth modification of the first embodiment of the present disclosure. In the embodiment, two closed sections 61 and 62 were formed by two hat members 31 and 32. However, the impact absorbing member 30 may have three or more closed sections formed by three or more n members, and in this fifth modification, three closed sections 61, 62, and 63 are formed by three hat members 31, 32, and 33.

[0138] The impact absorbing member 30 may include the three hat members 31, 32, and 33 described above. The first hat member 31 includes a first top plate portion 41 and first portions 45a and 46a which are part of a pair of vertical wall portions 45 and 46. The second hat member 32 includes a second top plate portion 42 and second portions 45b and 46b which are part of a pair of vertical wall portions 45 and 46. The third hat member 33 includes a third top plate portion 43, third portions 45c and 46c which are part of a pair of vertical wall portions 45 and 46, and a pair of flanges 47 and 48. The third top plate portion 43 connects the pair of third portions 45c and 46c. The vertical wall portion 45 is formed by the first portion 45a, the second portion 45b, and the third portion 45c. Similarly, the vertical wall portion 46 is formed by the first portion 46a, the second portion 46b, and the third portion 46c.

[0139] A bead 71 is formed on the first top plate portion 41 of the first hat member 31, extending uniformly in the front-rear direction Y, but this bead 71 is optional. The inner surfaces of the flanges 49 and 50, which are the base ends of the first portions 45a and 46a of the first hat member 31, are joined to the outer surfaces of the second portions 45b and 46b of the second hat member 32. The inner surfaces of the flanges 79 and 80, which are the base ends of the second portions 45b and 46b of the second hat member 32, are joined to the outer surfaces of the third portions 45c and 46c of the third hat member 33.

[0140] The first closed section 61 is formed by the first hat member 31 and the second top plate portion 42. Similarly, the second closed section 62 is formed by the second hat member 32 and the third top plate portion 43. Furthermore, the third closed section 63 is formed by the third hat member 33 and the side wall 223 of the side sill inner 22.

[0141] In this fifth modified example, the lengths of the closed sections 61, 62, and 63 in the width direction X are generally the same, but may be different from each other. For example, in the width direction X, the length of the third closed section 63 may be greater than the length of the second closed section 62, or the length of the third closed section 63 may be less than the length of the second closed section 62, or the length of the first closed section 61 may be less than the length of the second closed section 62.

[0142] As described above, even when three or more closed sections are formed, the order in which each closed section 61, 62, and 63 begins to collapse during a side impact, as well as the ease of collapse, can be set to a desired state by adjusting the strength and thickness of each closed section 61, 62, and 63.

[0143] [Other variations of the first embodiment] In the first embodiment and its various modifications described above, a reinforcing member may be interposed between the impact absorbing member 30 and the floor cross members 16 and 17. In the presence of this reinforcing member, it is possible to suppress the bending of the floor cross members 16 and 17 due to the impact load transmitted from the impact absorbing member 30 to the floor cross members 16 and 17 via the side sill 15.

[0144] Furthermore, the impact-absorbing member 30 in the first embodiment and each of its modifications described above may be made of an aluminum alloy or a composite material such as CFRP (Carbon Fiber Reinforced Plastics).

[0145] Furthermore, in the first embodiment and its various modifications described above, a configuration was explained in which the impact load during a side collision is transmitted to the floor cross members 16 and 17, but not to the battery case 100. However, this configuration is not required, and a configuration in which the impact load during a side collision is transmitted to the battery case 100 for impact absorption is also possible.

[0146] Furthermore, in the first embodiment and its various modifications described above, the first top plate portion 41 was described as being separated from the side sill outer 21. However, this is not required, and for example, as shown in Figure 7, the first top plate portion 41 may be in contact with the side wall 213 of the side sill outer 21 without being joined to it. Even in such a configuration, during a side collision of a vehicle, the impact absorbing member 30 can perform a two-stage crushing by sequentially crushing the two closed cross-section portions 61 and 62 while minimizing the influence of the deformation of the side sill outer 21. Therefore, the efficiency of absorbing impact energy can be increased. In other words, during a side collision of a vehicle, the impact absorbing member 30 can deform and absorb the impact while being less affected by the deformation of the side sill outer 21. As a result, the impact absorption performance of the impact absorbing member 30 can be demonstrated more effectively.

[0147] [Second Embodiment] (Vehicle body) Figure 8 is an exploded perspective view showing a part of the body 1 of an automobile equipped with a substructure 502 including a side sill structure 514 according to the second embodiment of this disclosure. Figure 9 is a cross-sectional view of the substructure 502 along the line IX-IX in Figure 8. Note that Figure 9 shows the battery case 600 fixed to the substructure 502, and the rear side of the cross section is omitted. In this specification, the direction along the direction of travel of the vehicle body 501 is defined as the longitudinal direction Y of the vehicle body, the direction of travel of the vehicle body is defined as the front, the opposite side as the rear, the vertical direction of the vehicle body is defined as the height direction Z, and the direction perpendicular to the longitudinal direction Y and the height direction Z is defined as the width direction X of the vehicle body. In the width direction X, the direction away from the center of the vehicle body 501 is defined as the outward direction, and the opposite direction is defined as the inward direction. In this specification, unless otherwise specified, the cross section perpendicular to the longitudinal direction Y is simply referred to as the "cross section".

[0148] As shown in Figures 8 and 9, the vehicle body 501 is part of the vehicle, and the vehicle can be an automobile. An example of an automobile is a passenger car. Examples of passenger cars include sedan-type passenger cars, coupe-type passenger cars, hatchback-type passenger cars, minivan-type passenger cars, and SUV (Sport Utility Vehicle)-type passenger cars. The vehicle can also be an electric vehicle (Battery Electric Vehicle) or a hybrid vehicle (HV, Hybrid Vehicle) including a plug-in hybrid vehicle, and the drive wheels can be driven by electricity from a battery 601 installed at the bottom of the vehicle body 501.

[0149] The vehicle body 501 comprises a frame 510 and a battery case 600.

[0150] The frame 510 includes a front pillar 511, a roof pillar 512, a center pillar 513, a side sill structure 514 including a side sill 515, floor cross members 516, 517, and a floor panel 518.

[0151] The front pillar 511, the roof pillar 512, the center pillar 513, and the side sill structure 514, including the side sill 515, are provided in pairs, spaced apart in the width direction X.

[0152] The front pillar 511 has a pillar upper 511a that extends upward and backward and is connected to the roof pillar 512, and a pillar lower 511b located below the pillar upper 511a.

[0153] The roof pillar 512 is located on the roof portion of the vehicle body 501 and extends rearward from the pillar upper 511a.

[0154] The center pillar 513 is positioned along the height direction Z and connects the roof pillar 512 and the side sill 515.

[0155] The side sill 515 is an example of a "structural member" in this disclosure. The side sill 515 is located at the lower part of the outer portion of the vehicle body 501 in the width direction X. The side sill 515 is connected to the lower part of the center pillar 513 and is positioned along the longitudinal direction Y of the vehicle body 501. The side sill 515 has a closed cross-sectional shape in a cross section perpendicular to the longitudinal direction Y.

[0156] The floor cross members 516 and 517 are members that extend in the width direction X and are positioned between a pair of left and right side sills 515 and 515, connecting these side sills 515 and 515. The floor cross members 516 and 517 are positioned on the front seat side of the passenger compartment (cabin) formed by the vehicle body 501. The floor cross members 516 and 517 are spaced apart in the longitudinal direction Y, with floor cross member 17 positioned behind floor cross member 16. Each of the floor cross members 516 and 517 has a hat-shaped cross section perpendicular to the width direction X, and works in cooperation with the floor panel 518 to form a closed cross section. The floor panel 518 forms the bottom of the cabin of the vehicle body 501 and is fixed to the floor cross members 516 and 517.

[0157] Slide rails (not shown) are installed on floor cross members 516 and 517. The slide rails support seats (not shown) on which occupants sit.

[0158] A plate-shaped floor panel 518 is installed below the floor cross members 516 and 517. A battery case 600 is installed below the floor panel 518. The battery case 600 houses a battery 601, which includes a lithium-ion battery or the like.

[0159] The side sill 515 is positioned outside the battery 601 in the width direction X in order to protect the battery 601 from side collisions (pole collisions) with utility poles and the like. Hereafter, a side collision of a vehicle will also be simply referred to as a "side collision". The side sill 515 extends along the longitudinal direction Y. The battery case 600 may be fixed to the side sill 515. In this second embodiment, the widthwise end 600a of the battery case 600 is fixed to, for example, the lower wall 724 of the side sill inner 522, which will be described later, of the side sill 515. In the middle portion of the battery case 600 in the width direction X, a side wall 600b is formed, for example, rising upward from the widthwise end 600a, as a protective wall for the battery 601. The battery 601 is positioned inside the width direction X relative to the side wall 600b. A gap 500A is formed between the side wall 600b and the side sill inner 522. The gap 500A varies depending on the vehicle model, but values ​​ranging from a few millimeters to several hundred millimeters can be exemplified. Note that the configuration of the battery case 600 described in this embodiment is just one example, and the specific shape and arrangement are not limited as long as the battery case 600 is positioned on the inside of the side sill 515 in the width direction X.

[0160] (Side sill structure) In the following description of the side sill structure 514, unless otherwise specified, the configuration in a cross-section perpendicular to the longitudinal direction Y will be described. The side sill structures 514 are provided in pairs, spaced apart in the width direction X. The lower structure 502 of the vehicle body 501 comprises each side sill structure 514 and a battery case 600.

[0161] Each side sill structure 514 includes the side sill 515 described above and the impact absorbing member 530.

[0162] The side sill 515 comprises a side sill outer 521 and a side sill inner 522 positioned inward in the width direction X relative to the side sill outer 521.

[0163] The side sill outer 521 and the side sill inner 522 each have a hat-shaped cross-section, and work together to form a closed cross-sectional space 523 in the side sill 515.

[0164] The side sill outer 521 has a shape that opens inward in the width direction X, and the side sill inner 522 has a shape that opens outward in the width direction X. The side sill outer 521 and the side sill inner 522 are fixed to each other by joining means such as welding or fastening members, with their flanges 711, 721; 715, 725 butted against each other. In this embodiment, the side sill outer 521 and the side sill inner 522 are joined to each other, for example, by welding. Various welding methods can be used, such as spot welding, TIG welding, arc welding, laser welding, and plasma welding. The fastening members may be structural adhesives, rivets, belts and nuts, and various materials can be used. The joining method when joining other parts of the vehicle body 501 is the same as described above.

[0165] The side sill outer 521 includes an upper flange 711, an upper wall 712 extending outward from the upper flange 711 in the width direction X, a side wall 713 extending downward from the upper wall 712, a lower wall 714 extending inward from the side wall 713 in the width direction X, and a lower flange 715 extending downward from the lower wall 714.

[0166] The side sill inner 522 includes an upper flange 721, an upper wall 722 extending inward from the upper flange 721 in the width direction X, a side wall 723 extending downward from the upper wall 722 and joined to the floor cross members 516, 517, a lower wall 724 extending outward from the side wall 723 in the width direction X, and a lower flange 725 extending downward from the lower wall 724.

[0167] The upper flanges 711 and 721 are joined to each other using the joining method described above. Similarly, the lower flanges 715 and 725 are joined to each other using the joining method described above.

[0168] The upper wall 712 and lower wall 714 of the side sill outer 521 may be parallel to each other along the width direction X, or they may be inclined such that the distance between them in the height direction Z changes as they extend outward along the width direction X. Similarly, the upper wall 722 and lower wall 724 of the side sill inner 522 may be parallel to each other along the width direction X, or they may be inclined such that the distance between them in the height direction Z changes as they extend inward along the width direction X.

[0169] Furthermore, the side sill 515 may have a shape that is symmetrical in the width direction X or asymmetrical in the width direction X, and its specific shape is not limited.

[0170] (Main components of the shock-absorbing material) The impact absorbing member 530 absorbs the impact energy of a side collision by plastically deforming in cooperation with the side sill 515 during a side collision.

[0171] The impact absorbing member 530 is formed of multiple members (in this embodiment, a first hat member 31 and a second hat member 32) and is supported by the side sill 515 within the closed cross-sectional space 523 of the side sill 515. That is, the impact absorbing member 530 has a second hat member 532 and a first hat member 531, which are formed in a hat shape in a cross section perpendicular to the front-rear direction Y and are aligned in the width direction X. The impact absorbing member 530 is formed by combining the second hat member 532 and the first hat member 531.

[0172] The impact-absorbing member 530 includes a hat-shaped portion 540 having a first top plate portion 531e extending in the height direction Z, and a pair of vertical wall portions 545, 546 extending along the width direction X from both ends of the first top plate portion 531e in the height direction Z, and a second top plate portion 532e which is spaced apart from the first top plate portion 531e in the width direction X and connects the pair of vertical wall portions 545, 546.

[0173] The second top plate portion 532e divides the inner space of the hat-shaped portion 540 in the width direction X, thereby forming a first closed section portion 561 including the first top plate portion 531e, and a second closed section portion 562 adjacent to the first closed section portion 561 in the width direction X. The shock absorbing member 530 is either separated from the side sill outer 521, or it is in contact with the side sill outer 521 without being joined to it.

[0174] The first hat member 531 includes a pair of first flanges 531a, 531b joined to the second top plate portion 532e, a pair of first vertical wall portions 531c, 531d extending from the pair of first flanges 531a, 531b, and a first top plate portion 531e connecting the pair of first vertical wall portions 531c, 531d.

[0175] The second hat member 532 comprises a pair of second flanges 532a, 532b supported by the side sill 515, a pair of second vertical wall portions 532c, 532d extending from the pair of second flanges 532a, 532b, and a second top plate portion 532e connecting the pair of second vertical wall portions 532c, 532d.

[0176] (Effects of the main components of the shock-absorbing material) Because the impact absorbing member 530 has the above-described configuration, numerous ridge portions 532f, 532g, 532h, 532i, 531f, 531g, 531h, and 531i are formed on the impact absorbing member 530. As a result, during a side collision, the action of the numerous ridge portions 532f, 532g, 532h, 532i, 531f, 531g, 531h, and 531i on the impact absorbing member 530 can increase the efficiency of absorbing impact energy when the closed cross-sectional shape of the second hat member 532 and the first hat member 531 deforms. In particular, since numerous ridge portions 531f, 531g, 531h, and 531i are formed on the first hat member 531, which is the first to receive the impact load in the impact absorbing member 530, the amount of impact energy absorbed when the first hat member 531 is crushed can be increased. As a result, the efficiency of impact energy absorption by the impact absorbing member 530 can be increased. This makes the impact absorbing member 530 lighter while increasing the amount of impact energy absorbed by the impact absorbing member 530, thereby improving the weight efficiency of impact energy absorption. Furthermore, by adjusting the shape of the second hat member 532 and the first hat member 531, the timing of deformation initiation and the manner of deformation of the second hat member 532 and the first hat member 531 can be set during a side collision. This allows the impact absorption operation of the impact absorbing member 530 during a side collision to be set according to the characteristics of the vehicle (such as the presence or absence of the battery case 600 and the layout of the battery case 600). Therefore, a higher side collision resistance performance can be achieved for the vehicle. Moreover, since the impact absorbing member 530 is formed from multiple members (in this embodiment, the second hat member 532 and the first hat member 531), the degree of freedom in shape setting is greater compared to when the impact absorbing member 530 is formed from a single member.

[0177] (Detailed example of shock-absorbing component configuration) The impact absorbing member 530 absorbs more impact energy by gradually crushing the multiple closed sections 561, 562 during a side collision, by forming a plurality of closed sections (in this embodiment, the side sill 515, the second hat member 532, and two closed sections 561, 562 formed by the first hat member 531) in the width direction X. Furthermore, the impact absorbing member 530 is formed of multiple members (in this embodiment, two hat members 531, 532). This allows the crushing characteristics of each closed section 561, 562 to be set to a desired state by combining the strength (tensile strength) and plate thickness of each hat member 531, 532. For example, the first hat member 531 may crush relatively large during a side collision (at the initial stage of a side collision) to absorb impact, while the second hat member 532 may crush relatively small during a side collision to suppress the amount of inward penetration in the width direction of the side sill 515, etc.

[0178] In this embodiment, the shock-absorbing member 530 is formed with a uniform cross-sectional shape throughout its entire surface, but its shape may differ in different parts in the front-rear direction Y. In this embodiment, the shock-absorbing member 530 is formed with a shape that is convex outward in the width direction X, but it may also be formed with a shape that is convex inward in the width direction X (a shape symmetrical with respect to the width direction X to the shape shown in Figure 9). The shock-absorbing member 530 may be installed over the entire area where the side sill 515 is located in the front-rear direction Y, or it may be installed only in a part of it. In this embodiment, the shock-absorbing member 530 is arranged continuously from the front end 515a to the rear end 515b of the side sill 515.

[0179] In this embodiment, the shock-absorbing member 530 is formed in a vertically symmetrical shape, but it may also be vertically asymmetrical. Because the shock-absorbing member 530 is formed from multiple members, it is easy to manufacture the shock-absorbing member 530 whether it is vertically symmetrical or vertically asymmetrical.

[0180] In the second embodiment, the shock-absorbing member 530 is positioned between the side wall 713 of the side sill outer 521 and the side wall 723 of the side sill inner 522. In this second embodiment, the shock-absorbing member 530 has a tapered shape in which the length in the height direction Z decreases as it moves outward in the width direction X. The shock-absorbing member 530 is elongated in the width direction X, and its length in the width direction X is greater than its length in the height direction Z.

[0181] (Detailed example of the configuration of the second hat member) The second hat member 532 is positioned adjacent to the side sill inner 522.

[0182] The second hat member 532 comprises a pair of second flanges 532a, 532b, a pair of base-side second ridge portions 532f, 532g, a pair of second vertical wall portions 532c, 532d, a pair of tip-side second ridge portions 532h, 532i, and a second top plate portion 532e.

[0183] The pair of second flanges 532a and 532b of the second hat member 532 are the parts that are joined to the side sill 515, and in this embodiment, they are joined to the inner surface of the side wall 723 of the side sill inner 522 by the joining method described above. The second flanges 532a and 532b do not have to be directly joined to the side sill inner 522, but may be joined to the side sill inner 522 via other members such as patches (reinforcement members).

[0184] As described above, the second flanges 532a and 532b of the impact absorbing member 530 are joined to the side sill inner 522. With this configuration, during a side collision, the impact load acting on the first top plate portion 531e can be transmitted from the side sill inner 522 to the floor cross members 516 and 517 with high transmission efficiency. Therefore, the cooperation of the side sill 515, the impact absorbing member 530, and the floor cross members 516 and 517 allows for the absorption of more impact energy. As a result, collision of the side sill 515 with the battery case 600 during a side collision can be suppressed.

[0185] The lengths of the second flanges 532a and 532b are not particularly limited, but if they are shorter than the length of the second top plate portion 532e, the overall length of the second hat member 532 in the height direction Z can be shortened. On the other hand, if the lengths of the second flanges 532a and 532b are longer than the length of the second top plate portion 532e, the bonding strength between the second hat member 532 and the side sill 515 in the height direction Z can be increased.

[0186] The upper second flange 532a extends upward from the upper second vertical wall portion 532c, and the lower second flange 532b extends downward from the lower second vertical wall portion 532d. These second flanges 532a and 532b are spaced apart from each other, and the second hat member 532 has a shape in which the inner side in the width direction X is open to the side sill inner 522 side. In this way, it is preferable that the impact absorbing member 530 is joined to the side sill inner 522 only by the second flanges 532a and 532b, and that no other part of the impact absorbing member 530 is positioned between the second flanges 532a and 532b in the height direction Z. With such a configuration, the impact absorbing member 530 can be made lighter. Furthermore, when spot welding the side sill inner 522 and the impact absorbing member 530, the side sill inner 522 can be welded by sandwiching it with a welding machine between the second flanges 532a and 532b, which are positioned outward in the height direction Z relative to the pair of second vertical wall portions 532c and 532d. Thus, in this embodiment, there are outward-facing second flanges 532a and 532b that are positioned outward in the height direction Z relative to the pair of second vertical wall portions 532c and 532d. The lower end of the upper second flange 532a and the upper end of the lower second flange 532b are connected to the second vertical wall portions 532c and 532d via the base-side second ridge portions 532f and 532g.

[0187] The second ridge sections 532f and 532g on the base side are curved in an arc shape in cross-section and have the function of increasing the amount of impact energy absorbed by the second hat member 532 during impact absorption. The radius of curvature of the second ridge sections 532f and 532g on the base side in cross-section is approximately a few millimeters to several tens of millimeters.

[0188] The pair of second vertical wall sections 532c and 532d of the second hat member 532 are arranged along the width direction X, and the distance between the pair of second vertical wall sections 532c and 532d widens as it moves toward the side sill inner 522 side. This layout of the pair of second vertical wall sections 532c and 532d allows the second hat member 532 to evenly receive the impact load acting inward from the side sill outer 521 in the width direction X. Therefore, the amount of impact energy absorbed by the impact absorbing member 530 can be increased during a side collision. The pair of second vertical wall sections 532c and 532d may also be arranged parallel (horizontally) to the width direction X, or the distance between the pair of second vertical wall sections 532c and 532d may narrow as it moves toward the side sill inner 522 side.

[0189] The tip of the upper second vertical wall section 532c and the tip of the lower second vertical wall section 532d are connected to the second top plate section 532e via the tip-side second ridge sections 532h and 532i.

[0190] The second ridge sections 532h and 532i on the tip side are curved in an arc shape in cross-section and have the function of increasing the amount of impact energy absorbed by the second hat member 532 during impact absorption. The radius of curvature of the second ridge sections 532h and 532i on the tip side in cross-section is approximately a few millimeters to several tens of millimeters.

[0191] The second top plate portion 532e suppresses out-of-plane deformation such that the pair of second vertical wall portions 532c and 532d connected to the second top plate portion 532e tilt inward. In this embodiment, the second top plate portion 532e is arranged parallel to the first top plate portion 531e of the first hat member 531. The second top plate portion 532e connects the pair of second vertical wall portions 532c and 532d. Furthermore, the second top plate portion 532e is joined to the pair of first flanges 531a and 531b by the joining method described above.

[0192] Furthermore, in this embodiment, the second top plate portion 532e is parallel to the height direction Z. With this configuration, during a side collision, the horizontal load acting on the second top plate portion 532e via the side wall 713 of the side sill outer 521 and the first hat member 531 can be evenly distributed in the height direction Z at the second top plate portion 532e. Therefore, the amount of crushing at the second hat member 532 can be increased, and more impact energy can be absorbed.

[0193] The second top plate portion 532e is positioned in the middle of the impact absorbing member 530 in the rising direction (width direction X) of the pair of second vertical wall portions 532c and 532d. The presence of the second top plate portion 532e allows the outer and inner portions of the impact absorbing member 530 to be shortened in the width direction X. As a result, out-of-plane deformation of the pair of second vertical wall portions 532c and 532d and the pair of first vertical wall portions 531c and 531d of the first hat member 531, described later, can be suppressed during a side collision, and the amount of energy absorbed by wall buckling motion can be increased.

[0194] The second top plate portion 532e is positioned closer to the side sill inner portion 522 of the side sill outer portion 521 and the side sill inner portion 522. This allows the length (height H531) of the first hat member 531 to be increased. As a result, the length (impact absorption stroke) over which the first hat member 531 can be compressed in the width direction X to absorb impact during a side collision can be increased. Furthermore, the space inside the second hat member 532 can be reduced. As a result, out-of-plane deformation of the pair of second vertical wall portions 532c and 532d of the second hat member 532 can be suppressed during a side collision. Moreover, during a side collision, by compressing the first hat member 531 first, and then the second hat member 532, the impact load from the width direction X can be absorbed sequentially from the members positioned on the outside of the width direction X. By enabling such a smooth impact absorption operation, the efficiency of impact energy absorption by the impact absorbing member 530 can be increased.

[0195] (Detailed example of the configuration of the first hat member) The first hat member 531 is positioned closer to the side sill outer 521 than the side sill inner 522. This arrangement of the second hat member 532 and the first hat member 531 allows the first hat member 531 to be crushed first during a side collision, thereby absorbing the impact energy.

[0196] The first hat member 531 comprises a pair of first flanges 531a, 531b, a pair of base-side first ridge portions 531f, 531g, a pair of first vertical wall portions 531c, 531d, a pair of tip-side first ridge portions 531h, 531i, and a first top plate portion 531e.

[0197] The pair of first flanges 531a and 531b of the first hat member 531 are joined to the outer surface of the second top plate portion 532e of the second hat member 532 by the joining method described above. The first flanges 531a and 531b do not necessarily have to be joined directly to the second top plate portion 532e, but may be joined to the second top plate portion 532e via a patch (reinforcement member).

[0198] The lengths of the first flanges 531a and 531b are not particularly limited, but it is preferable that they do not protrude from the second top plate portion 532e in the height direction Z, as this allows for a lighter first hat member 531. Also, the end faces 531j and 531k of the first flanges 531a and 531b face the height direction Z and do not face the second hat member 532 in the height direction Z. The first flanges 531a and 531b may contact the second top plate portion 532e of the second hat member 532, but do not need to contact the second ridge portions 532h and 532i on the tip side. With the first flanges 531a and 531b arranged as described above, the vertical wall portions 531c and 531d of the first hat member 531 are positioned such that the vertical wall portions 532c and 532d of the second hat member 532 are excluded from the region extending in the longitudinal direction of the vertical wall portions 532c and 532d. With this layout of the first hat member 531, when an impact load is applied to the first hat member 531, the first flanges 531a and 531b can firmly support the vertical wall portions 531c and 531d, and as a result, more impact energy can be absorbed by promoting the deformation of the vertical wall portions 531c and 531d between the base-side first ridge portions 531f and 531g and the tip-side first ridge portions 531h and 531i.

[0199] The upper first flange 531a extends upward from the upper first vertical wall portion 531c, and the lower first flange 531b extends downward from the lower first vertical wall portion 531d. These first flanges 531a and 531b are spaced apart from each other, and the second hat member 532 has a shape in which the inner side in the width direction X is open to the side sill inner 522 side. In this way, the first hat member 531 is joined only at the second top plate portion 532e of the second hat member 532, and it is preferable that no other part of the impact absorbing member 530 is positioned between the first flanges 531a and 531b in the height direction Z. With such a configuration, the impact absorbing member 530 can be made lighter. Furthermore, when spot welding the second hat member 532 and the first hat member 531, the first flanges 531a and 531b, which are positioned outward in the height direction Z relative to the pair of first vertical wall portions 531c and 531d, and the second top plate portion 532e can be clamped together with a welding machine and welded. Thus, in this embodiment, there are outward-facing first flanges 531a and 531b that are positioned outward in the height direction Z relative to the pair of first vertical wall portions 531c and 531d. The lower end of the upper first flange 531a and the upper end of the lower first flange 531b are connected to the first vertical wall portions 531c and 531d via the base-side first ridge portions 531f and 531g.

[0200] The first ridge sections 531f and 531g on the base side are curved in an arc shape in cross-section and have the function of increasing the amount of impact energy absorbed by the first hat member 531 during impact absorption. The radius of curvature of the first ridge sections 531f and 531g on the base side in cross-section is about a few millimeters to several tens of millimeters. The radius of curvature of the first ridge sections 531f and 531g on the base side may be the same as the radius of curvature of the second ridge sections 532f and 532g on the base side of the second hat member 532, it may be less than the radius of curvature of the second ridge sections 532f and 532g on the base side, or it may be greater than the radius of curvature of the second ridge sections 532f and 532g on the base side.

[0201] The pair of first vertical wall sections 531c and 531d of the first hat member 531 are arranged along the width direction X, and the distance between the pair of first vertical wall sections 531c and 531d widens as they move toward the side sill inner 522 side. This layout of the pair of first vertical wall sections 531c and 531d allows impact loads acting inward from the side sill outer 521 in the width direction X to be transmitted in a balanced manner from the first hat member 531 to the second hat member 532. Therefore, the amount of impact energy absorbed by the impact absorbing member 530 can be increased during a side collision. The pair of first vertical wall sections 531c and 531d may also be arranged parallel (horizontally) to the width direction X, or the distance between the pair of first vertical wall sections 531c and 531d may narrow as they move toward the side sill inner 522 side.

[0202] The tip of the upper first vertical wall section 531c and the tip of the lower first vertical wall section 531d are connected to the first top plate section 531e via the tip-side first ridge sections 531h and 531i.

[0203] The first ridge sections 531h and 531i on the tip side are curved in an arc shape in cross-section and have the function of increasing the amount of impact energy absorbed by the first hat member 531 during impact absorption. The radius of curvature of the first ridge sections 531h and 531i on the tip side in cross-section is approximately a few millimeters to several tens of millimeters.

[0204] The first top plate portion 531e and the first vertical wall portions 531c, 531d of the first hat member 531 are the parts of the impact absorbing member 530 that first receive the impact load during a side collision.

[0205] In this embodiment, the first top plate portion 531e is positioned closer to the side sill outer 521 than the side sill outer 521 and side sill inner 522. This ensures that the length of the impact absorbing member 530 is sufficiently secured in the width direction X. As a result, in the event of a side collision, the length (impact absorption stroke) over which the impact absorbing member 530 can be compressed in the width direction X to absorb impact can be increased.

[0206] In this embodiment, the first top plate portion 531e is in contact with the side wall 713 of the side sill outer 521, but is not joined to the side wall 713 of the side sill outer 21.

[0207] With such a favorable configuration, it is easier to install the shock-absorbing member 530 inside the side sill 515. This is because it eliminates the need to join the first top plate portion 531e to the side wall 713 of the side sill outer 521. If the first top plate portion 531e were to be joined to the side wall 713 of the side sill outer 521 by welding, the welding machine would need to be sandwiched between the first top plate portion 531e and the side wall 713. This would make the process of installing the shock-absorbing member 530 inside the side sill 515 more time-consuming. This cumbersome process would be the same regardless of whether the welding method is spot welding, laser welding, or adhesive bonding.

[0208] Furthermore, with such a favorable configuration, during a side collision of a vehicle, the impact absorbing member 530 can perform a two-stage crushing by sequentially crushing the two closed cross-sections 561 and 562 while minimizing the deformation of the side sill outer 521, thereby increasing the efficiency of impact energy absorption. In other words, during a side collision of a vehicle, the impact absorbing member 530 can deform and absorb the impact while being less affected by the deformation of the side sill outer 521. This allows the impact absorbing member 530 to exhibit its impact absorption performance more effectively.

[0209] Furthermore, the first top plate portion 531e may be separated from the side wall 713 of the side sill outer 521 to such an extent that it does not come into contact with it even during vibrations while the vehicle is in motion. In this way, if the first top plate portion 531e is separated from the side sill outer 521, deformation of the members due to the transmission of impact from the side sill outer 521 to the impact absorbing member 530 and the side sill inner 522 can be suppressed when a relatively minor side collision occurs to the vehicle. When a relatively minor side collision occurs to the vehicle, an impact acts on the side sill outer 521, but this impact is not transmitted from the side sill outer 521 to the impact absorbing member 530. Therefore, the transmission of impact to the side sill inner 522 via the impact absorbing member 530 is avoided. In such a case, the amount of deformation of the side sill 515 is small, so a decrease in the vehicle's driving performance (straight-line performance, etc.) can be suppressed. Furthermore, when repairing the vehicle, while the side wall 713 of the side sill outer 521 needs to be repaired, the impact absorbing member 530 and the side sill inner 522 do not need to be repaired, thus reducing the effort and cost of vehicle maintenance. On the other hand, when a large side collision occurs to the vehicle, the impact is transmitted from the side sill outer 521 to the side sill inner 522 via the impact absorbing member 530, enabling efficient absorption of impact energy through the deformation of the impact absorbing member 530 and the side sill inner 522.

[0210] It is preferable that the first top plate portion 531e is arranged parallel to the side wall 713, in that the entire first top plate portion 531e receives the impact load from the side wall 713 of the side sill outer 521. The first top plate portion 531e connects the pair of first vertical wall portions 531c and 531d. The first top plate portion 531e is the shortest portion in the height direction Z among the impact absorbing members 530. It is preferable that the first top plate portion 531e is arranged parallel to the second top plate portion 532e, in that it can increase the efficiency of absorbing impact energy acting in the width direction X during a side collision.

[0211] With the above configuration, the pair of vertical wall portions 531c, 531d (a pair of first portions) of the first hat member 531 and the pair of vertical wall portions 532c, 532d (a pair of second portions) of the second hat member 532 cooperate to form the pair of vertical wall portions 545, 546 in the hat-shaped portion 540 of the impact absorbing member 530.

[0212] (Example of configuration of the first closed section and the second closed section) With the above configuration, the second closed section 562 is formed by a second top plate 532e, a pair of front-end second ridge sections 532h, 532i, a pair of second vertical wall sections 532c, 532d, a pair of base-end second ridge sections 532f, 532g, a pair of second flanges 532a, 532b, and the side wall 723 of the side sill inner 522. The first closed section 561 is formed by a first top plate 531e, a pair of front-end first ridge sections 531h, 531i, a pair of first vertical wall sections 531c, 531d, a pair of base-end first ridge sections 531f, 531g, a pair of first flanges 531a, 531b, and the second top plate 532e.

[0213] In this second embodiment, the second vertical wall portions 532c and 532d of the second hat member 532 are not aligned in a straight line with the corresponding first vertical wall portions 531c and 531d of the first hat member 531. This stepped, linear layout allows the impact load acting from the first top plate portion 531e to the impact absorbing member 530 during a side collision to be absorbed by many of the ridge portions 531f to 531i and 532f to 532i.

[0214] (Examples of materials for impact-absorbing components) Next, the material and other specifications of the shock-absorbing member 530 will be described.

[0215] If the shock-absorbing member 530 is made of steel plate, iron, which has a relatively low unit cost compared to aluminum, can be used, thereby reducing the manufacturing cost of the vehicle body 501.

[0216] In this second embodiment, the second hat member 532 and the first hat member 531 of the impact absorbing member 530 are each formed from steel plates. The tensile strength of each hat member 531, 532 can be exemplified as 590 MPa to 2.5 GPa. More specifically, the lower limit of the tensile strength of each hat member 531, 532 may be 780 MPa, 980 MPa, 1.3 GPa, 1.5 GPa, 1.7 GPa, 2.0 GPa, or 2.3 GPa. The upper limit of the tensile strength of each hat member 31, 32 may be 1.5 GPa, 1.7 GPa, 2.0 GPa, or 2.3 GPa.

[0217] Tensile strength can be evaluated in accordance with JIS Z 2241:2011. A suitable test specimen for measuring tensile strength is the No. 5 specimen specified in JIS Z 2241:2011. Examples of sample locations for the tensile test specimen include the central portion of the pair of second vertical wall sections 532c and 532d of the second hat member 532, and the central portion of the pair of first vertical wall sections 531c and 531d of the first hat member 531.

[0218] The Vickers hardness HV1 and HV2 of each hat member 531 and 532 can be given as corresponding to the tensile strength of each hat member 531 and 532. Examples of Vickers hardness HV1 and HV2 for each hat member 531 and 532 include 240 to 780. The lower limit of Vickers hardness HV1 and HV2 for each hat member 531 and 532 may be 180 corresponding to 590 MPa, 240 corresponding to 780 MPa, 300 HV corresponding to 980 MPa, 400 corresponding to 1.3 GPa, 460 corresponding to 1.5 GPa, 520 corresponding to 1.7 GPa, 620 corresponding to 2.0 GPa, or 710 corresponding to 2.3 GPa. Furthermore, the upper limits of the Vickers hardness HV1 and HV2 of each hat member 531 and 532 may be 460 corresponding to 1.5 GPa, 520 corresponding to 1.7 GPa, 620 corresponding to 2.0 GPa, 710 corresponding to 2.3 GPa, or 780 corresponding to 2.5 GPa.

[0219] The Vickers hardness of each hat member 531, 532 can be measured as follows. Vickers hardness (HV1) "HV1" refers to the "hardness symbol" when a Vickers hardness test is performed with a test force of 1 kgf (9.807 N) (JIS Z 2244-1:2020). The Vickers hardness is measured as follows. First, a sample for measurement is cut from a flat plate-like part such as the first top plate portion 531e of the first hat member 531 so that the cut surface (measurement surface) is parallel to the thickness direction of the flat plate-like part, and the sample is embedded in resin and the cut surface is polished. Then, at a position 1 / 4 of the plate thickness from the surface of the sample on the cut surface (measurement surface), 10 points are measured at 0.5 mm intervals with a test force of 1 kgf (9.807 N), and the average is taken.

[0220] The Vickers hardness (HV2) "HV2" is a value obtained by cutting a sample for measurement from a flat plate-like portion such as the second top plate portion 532e of the second hat member 532, instead of the first top plate portion 531e, and performing the above test.

[0221] In the second embodiment, the tensile strength TS1 (Vickers hardness HV1) of the first hat member 531 is set lower than the tensile strength TS2 (Vickers hardness HV2) of the second hat member 532 (TS1 < TS2). That is, the strength on the side of the side sill outer 521 in the shock absorbing member 530 is made lower than the strength on the side of the side sill inner 522.

[0222] With such a setting of the tensile strength, at the time of a side collision, the first hat member 531 can start to deform earlier than the second hat member 532 and absorb shock energy. In the closed cross-section space 523, the first hat member 531 disposed on the side farther from the battery case 600 in the shock absorbing member 530 deforms first, so that the deformation timing of the second hat member 532 on the side closer to the battery case 600 can be delayed. In other words, the deformation of the second hat member 532 can be suppressed until the first hat member 531 is sufficiently deformed. Thereby, by the crushing of the first hat member 531, the amount of shock energy absorbed can be increased, and it is possible to suppress the side sill inner 522 that crushes together with the crushing of the second hat member 532 from contacting the side wall 600b of the battery case 600. Furthermore, since the second hat member 532 has a high strength, the amount of shock energy absorbed by the second hat member 532 can be made larger.

[0223] The tensile strength TS2 (Vickers hardness HV2) of the second hat member 532 is preferably about 1.3 to 1.7 times the tensile strength TS1 (Vickers hardness HV1) of the first hat member 531, with 1.5 times being an example. With this setting, the first hat member 531 can be crushed during a side impact, and the crushing of the second hat member 532 can begin only after the first hat member 531 has been sufficiently crushed. In addition, it is possible to suppress the occurrence of cracks in the first hat member 531, which is greatly crushed during a side impact, and the reduction in impact energy absorption efficiency. As a more specific value configuration, an example can be given in which the tensile strength TS1 of the first hat member 531 is 980 MPa and the tensile strength TS2 of the second hat member 532 is 1.5 GPa. In this configuration, the impact energy absorption value can be increased compared to when the tensile strengths TS1 and TS2 of each hat member 531 and 532 are the same.

[0224] (Examples of plate thickness for shock-absorbing members) Examples of plate thickness for each hat member 531, 532 include 0.8 mm to 2.3 mm. The plate thicknesses of each hat member 531, 532 may be the same or different, but a smaller thickness is preferable in terms of weight reduction. In this second embodiment, the plate thickness t1 of the first hat member 531 is set to be smaller than the plate thickness t2 of the second hat member 532. The plate thickness t2 of the second hat member 532 is preferably about 1.3 to 1.7 times the plate thickness t1 of the first hat member 531, and about 1.5 times is an example. By setting these plate thickness ratios t2 / t1 within the above range, the crushing of the second hat member 532 can be started after the first hat member 531 has been sufficiently crushed during a side collision. Examples of lower limits for the plate thickness t1 and t2 of the hat members 531 and 532 include 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, and 2.2 mm. Examples of upper limits for the plate thickness t1 and t2 of each hat member 531 and 532 include 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, and 2.2 mm.

[0225] (An example of strength ratio and plate thickness ratio for a hat-shaped component) While setting the tensile strength ratio TS2 / TS1 of each hat member 531, 532 to 1.3 to 1.7 (for example, 1.5), the plate thickness ratio t2 / t1 may be set to 1, or while setting the tensile strength ratio TS2 / TS1 of each hat member 531, 532 to 1, the plate thickness ratio t2 / t1 may be set to 1.3 to 1.7 (for example, 1.5).

[0226] Regarding the combination of the plate thicknesses t1, t2 and the tensile strengths TS1, TS2 of each hat member 531, 532, it is preferable that the first hat member 531 starts to crush earlier than the second hat member 532 during a side collision, and the second hat member 532 starts to crush after the first hat member 531 is sufficiently crushed.

[0227] Regarding the Vickers hardness HV1 and the plate thickness t1 of the first hat member 531 and the Vickers hardness HV2 and the plate thickness t2 of the second hat member 532, 180 ≤ HV1, HV2 ≤ 780, 0.8 mm ≤ t1 t2 ≤ 2.3 mm, and, HV1 × t1 < HV2 × t2 it is preferable that this is the case.

[0228] By setting 180 ≤ HV1, the strength of the first hat member 531 can be sufficiently ensured and the impact energy absorption efficiency can be increased. Also, by setting HV2 ≤ 780, cracking during deformation of the second hat member 532 can be suppressed and the impact energy absorption efficiency can be increased. Also, by setting 0.8 mm ≤ t1, the rigidity of the first hat member 531 can be sufficiently ensured and cracking of the first hat member 531 can be suppressed. Also, by setting t2 ≤ 2.3 mm, the second hat member 532 can be made lightweight. And by setting HV1 × t1 < HV2 × t2, the operation in which the first hat member 531 starts to crush earlier than the second hat member 532 during a side collision and the second hat member 532 starts to crush after the first hat member 531 is sufficiently crushed can be made to occur more reliably.

[0229] As the impact-absorbing member 530 is formed by multiple hat members 531 and 532, there is a high degree of freedom in selecting the Vickers hardness HV1 and HV2 for each of the multiple hat members 531 and 532, and in selecting the plate thickness t1 and t2.

[0230] (An example of the effect in the second embodiment) With the above configuration, in this second embodiment, the degree of freedom in setting the shape of the impact absorbing member 530 can be increased, and a side sill structure 514 and an automobile understructure 502 that can achieve high side impact resistance can be realized.

[0231] In particular, in this embodiment, since the impact absorbing members 530 are arranged on both sides (left and right sides) in the width direction X of the vehicle body 501, the impact energy absorption effect of the impact absorbing members 530 can be exerted regardless of whether the side collision occurs on the right or left side of the vehicle body 501.

[0232] Furthermore, the impact-absorbing members 530 positioned on the sides of the battery case 600 provide an impact energy absorption effect, thereby protecting the battery case 600 and the battery 601 inside it.

[0233] [First modified example of the second embodiment] Figure 10 is a schematic cross-sectional view showing the main part of the first modification of the second embodiment of the present disclosure. In the embodiment, the second top plate portion 532e was positioned closer to the side sill inner 522 of the side sill outer 521 and side sill inner 522. On the other hand, as shown in Figure 10, in the first modification of the second embodiment, the second top plate portion 532e is positioned closer to the side wall 713 of the side sill outer 521 and side sill inner 522.

[0234] As a result, in the width direction X, the height H531 of the first hat member 531 is shorter than the height H532 of the second hat member 532.

[0235] In particular, in the first modification of the second embodiment, the second top plate portion 532e is located outside the width direction X with respect to the flanges 711, 721; 715, 725 which are the boundary between the side sill outer 521 and the side sill inner 522 in the width direction X.

[0236] This layout allows for a larger space between the second top plate portion 532e and the side sill inner 522 (the space within the second hat member 532). As a result, the amount of impact energy that can be absorbed by the pair of second vertical wall portions 532c and 532d during a side collision can be increased. Furthermore, during a side collision, the first hat member 531 is crushed first, followed by the second hat member 532, allowing the impact load from the width direction X to be absorbed sequentially from the members located on the outside of the width direction X. This smooth impact absorption operation increases the efficiency of impact energy absorption by the impact absorbing member 530.

[0237] [Second modified example of the second embodiment] Figure 11 is a schematic cross-sectional view showing the main part of a second modification of the second embodiment of the present disclosure. In the second embodiment, a configuration in which the first top plate portion 531e is in contact with the side sill 515 has been mainly described. On the other hand, as shown in the second modification of Figure 11, the first top plate portion 531e may be sufficiently separated from the side sill 515. More specifically, the first top plate portion 531e is adjacent to the side wall 713 of the side sill outer 521, but is separated from this side wall 713.

[0238] With this configuration, vibration noise caused by contact between the first top plate portion 531e and the side sill outer 521 can be suppressed, while the impact load from the side sill outer 521 during a side collision can be transmitted to the impact absorbing member 530 along with the crushing of the side sill outer 521. In addition, it is not necessary to join the impact absorbing member 530 to both the side sill inner 522 and the side sill outer 521, and the number of steps required to attach the impact absorbing member 530 to the side sill 515 can be reduced.

[0239] It is preferable that the first top plate portion 531e is arranged parallel to the side wall 713, in that the impact load from the side wall 713 of the side sill outer 521 is received by the entire first top plate portion 531e.

[0240] [Third modified example of the second embodiment] Figure 12 is a schematic cross-sectional view showing the main part of a third modification of the second embodiment of the present disclosure. In the second embodiment, an example was described in which the second flanges 532a and 532b are joined only to the side wall 723 of the side sill inner 522. On the other hand, as shown in the third modification in Figure 12, the second flanges 532a and 532b may also be joined to locations other than the side wall 723 of the side sill 515.

[0241] In the third modified example of the second embodiment, the pair of second flanges 532a and 532b are joined to the side wall 723 of the side sill inner 522 and to the upper wall 722 and lower wall 724, which form a pair of walls, by the joining method described above.

[0242] The second flanges 532a and 532b are each formed in a shape that follows the portion of the side sill inner 522 where the second flanges 532a and 532b face each other. In the third modified example of the second embodiment, each of the second flanges 532a and 532b has a curved (bent) shape in the middle portion in the height direction Z. The second flanges 532a and 532b only need to be joined to at least a portion of the side wall 723, the upper wall 722, and the lower wall 724, and do not need to be joined to, for example, the connection portion (ridge portion) between the side wall 723 and the upper wall 722, or the connection portion (ridge portion) between the side wall 723 and the lower wall 724.

[0243] According to the configuration of the third modified example of the second embodiment, the second flanges 532a and 532b are joined to the upper wall 722 and the lower wall 724 of the side sill inner 522, in addition to the side wall 723. This increases the bonding strength between the second hat member 532 and the side sill 515. As a result, even when a strong impact acts on the side sill 515 during a side collision, the second hat member 532 is prevented from detaching from the side sill 515, and the impact absorption effect of the impact absorbing member 530 can be more reliably demonstrated.

[0244] [Fourth modified example of the second embodiment] Figure 13 is a schematic cross-sectional view showing the main part of a fourth modification of the second embodiment of the present disclosure. In the embodiment, a configuration in which the second top plate portion 532e is parallel to the height direction Z (side walls 713, 723 of the side sill 515) was described as an example. On the other hand, as shown in Figure 13, the second top plate portion 532e may be arranged at an inclination with respect to the height direction Z (side walls 713, 723 of the side sill 515).

[0245] The second top plate portion 532e may be inclined such that it moves outward in the width direction X as it moves downward, as shown in Figure 13, or it may be inclined such that it moves inward in the width direction X as it moves downward. The inclination angle θ of the second top plate portion 532e with respect to the height direction Z is not particularly limited, but it is preferable if it is 45 degrees or less in that the second top plate portion 532e can more reliably receive the impact during a side collision. The inclination angle θ may be 30 degrees or less, or 15 degrees or less. In this case, as shown in Figure 13, the first top plate portion 531e may be arranged parallel to the second top plate portion 532e, or it may be inclined relative to the second top plate portion 532e, or it may be parallel to the side walls 713, 723 of the side sill 515.

[0246] As described above, in the fourth modification of the second embodiment, the second top plate portion 532e is inclined with respect to the height direction. With such a configuration, for example, even when the side sill 515 collides obliquely with a pole fixed to the ground, the impact from this pole can be more reliably received by the second hat member. Further, the height position of the first hat member 531 can be changed without changing the fixing positions of the second flanges 532a and 532b and the side sill 515. Therefore, by making a slight design change, the layout of the first hat member 531 can be changed, and the freedom in designing the impact absorbing member 530 can be increased.

[0247] [Fifth Modification of the Second Embodiment] FIG. 14 is a schematic cross-sectional view showing a main part of a fifth modification of the second embodiment of the present disclosure. In the embodiment, a form in which the second top plate portion 532e has a flat shape in cross section has been described as an example. On the other hand, as shown in FIG. 14, in cross section, the second top plate portion 532e may have a plurality of ridge lines 541a, 541b, 541c, and 541d formed by a change in the position in the width direction X in the middle part in the height direction Z.

[0248] In the fifth modification of the second embodiment, the second top plate portion 532e has a shape that is concave toward the inside in the width direction X (concave so as to be separated from the first top plate portion 531e) due to the formation of the bead 541. The depth H541 of the bead 541 is not particularly limited, but may be, for example, 1 / 2 or less, 1 / 3 or less, or 1 / 4 or less of the height H532 of the second hat member 532.

[0249] The bead 541 is disposed, for example, at the center of the second top plate portion 532e in the height direction Z. The bead 541 forms a concave portion (hat-shaped portion) in cross section. The bead 541 may have a shape that is symmetric with respect to the height direction Z or an asymmetric shape. The bead 541 has a plurality (four in the fifth modification) of ridge lines 541a, 541b, 541c, and 541d formed.

[0250] Each ridge line portion 541a, 541b, 541c, 541d is a portion that is curved in an arc shape in cross-section, and has a function of increasing the amount of impact energy absorbed by the second hat member 532 during impact absorption. The radius of curvature of each ridge line portion 541a, 541b, 541c, 541d in cross-section is about several millimeters to several tens of millimeters.

[0251] As described above, according to the configuration of the fifth modification of the second embodiment, in the second hat member 532, in addition to the second ridge line portions 532f, 532g, 532h, 532i, there are ridge line portions 541a, 541b, 541c, 541d formed by the bead 541. As a result, there are more ridge line portions in the second hat member 532, and during a side collision, due to the action of the numerous ridge line portions 532f to 532i, 541a to 541d in the impact absorption member 530, the absorption efficiency of the impact energy when the second hat member 532 is deformed can be made higher.

[0252] In the fifth modification of the second embodiment, the form in which the bead 541 that is recessed in the second top plate portion 532e is provided has been described as an example. However, it does not have to be like this. The bead may be, for example, a shape that protrudes toward the side sill outer 521 side in the second top plate portion 532e. Also, the bead may be formed in a shape that protrudes upward or downward in the pair of second vertical wall portions 532c, 532d. Further, the bead may be a shape that is formed in the first hat member 531 in the first top plate portion 531e and protrudes toward the inside or outside in the width direction X.

[0253] Furthermore, the beads may be formed in a shape that is convex upward or downward on a pair of first vertical wall portions 531c, 531d. More specifically, as shown in Figure 15, which is a drawing of a modification of a fifth modification of the second embodiment, a plurality of concave beads 542 extending from the base end to the tip end of the first hat member 531 may be intermittently formed in the front-rear direction Y on the first vertical wall portions 531c, 531d. Each bead 542 extends from the first top plate portion 531e to the corresponding first flanges 531a, 531b. Each bead 542 is formed in a concave shape when viewed from the width direction X and has a plurality (e.g., four) of ridge portions 542a, 542b, 542c, 542d. The provision of such ridges 542a, 542b, 542c, and 542d allows for a higher efficiency in absorbing impact energy until the first hat member 531 is crushed during a side impact. Note that beads similar to those of the second hat member 532 may also be formed on the pair of second vertical wall portions 532c and 532d of the second hat member 532.

[0254] [Sixth variation of the second embodiment] Figure 16 is a schematic cross-sectional view showing the main part of a sixth modification of the second embodiment of the present disclosure. In the sixth modification of the second embodiment, in addition to the configuration of the second embodiment, a second reinforcing member 552 is provided to the impact absorbing member 530.

[0255] The second reinforcing member 552 is also called a patch, and may be made of the same material as the second hat member 532 or the first hat member 531, or it may be made of a different material than these hat members 531 and 532.

[0256] In the sixth modified example of this second embodiment, the second reinforcing member 552 is a plate-shaped member and is joined to the second hat member 532. The second reinforcing member 552 may be formed over the entire area where the second hat member 532 is present in the front-rear direction Y, or it may be formed only in part of it. The second reinforcing member 552 is arranged so as to be surrounded by the second hat member 532. The second reinforcing member 552 includes a second base 552a which is joined along the inner surface of the second top plate portion 532e, and a pair of second flanges 552b, 552c which extend from both ends of the second base 552a in cross-section and are aligned along the inner surfaces of a pair of second vertical wall portions 532c, 532d. The second flanges 552b, 552c may be joined to the inner surfaces of the pair of second vertical wall portions 532c, 532d. The method of joining the second reinforcing member 552 to the second hat member 532 is the same as the joining method described above.

[0257] As described above, the provision of the second reinforcing member 552 allows the second top plate portion 532e to be reinforced. This enables the second top plate portion 532e and the second reinforcing member 552 to work together to suppress out-of-plane deformation of the pair of second vertical wall portions 532c and 532d. This allows the impact energy absorption effect of the second hat member 532 to be more reliably achieved during a side collision. In the sixth modification of this second embodiment, the second reinforcing member 552 was described as being positioned along the inside of the second top plate portion 532e in the width direction X, but this is not required. The second reinforcing member 552 may be positioned along the outside of the second top plate portion 532e in the width direction X. Alternatively, a plate-shaped reinforcing member similar to the second reinforcing member 552 may be positioned along the upper or lower surface of at least one of the second vertical wall portions 532c and 532d.

[0258] As shown in Figure 17, which is a modification of the sixth modification of the second embodiment, the first reinforcing member 551 may be arranged on the first hat member 531. The first reinforcing member 551 is also called a patch and may be made of the same material as the second hat member 532 or the first hat member 531, or it may be made of a different material than these hat members 531 and 532. The first reinforcing member 551 is a plate-shaped member and is joined to the first hat member 531. The first reinforcing member 551 may be formed over the entire area where the first hat member 531 is located in the front-rear direction Y, or it may be formed only in a part of it. The first reinforcing member 551 is arranged so as to surround the first hat member 531. The first reinforcing member 551 comprises a first base 551a joined to the inner surface of the first top plate portion 531e, and a pair of first flanges 551b, 551c extending from both ends of the first base 551a in cross-section and along the inner surfaces of a pair of first vertical wall portions 531c, 531d. The first flanges 551b, 551c may be joined to the inner surfaces of the pair of first vertical wall portions 531c, 531d. The method of joining the first reinforcing member 551 to the first hat member 531 is the same as the joining method described above. In this modified example, the first reinforcing member 551 has been described as being aligned to the inside of the first top plate portion 531e in the width direction X, but this is not required. The first reinforcing member 551 may be aligned to the outside of the first top plate portion 531e in the width direction X. Alternatively, a plate-shaped reinforcing member similar to the first reinforcing member 551 may be placed along the upper or lower surface of at least one of the first vertical wall portions 531c and 531d.

[0259] As described above, the first reinforcing member 551 reinforces the first top plate portion 531e. This allows the first top plate portion 531e and the first reinforcing member 551 to work together to suppress out-of-plane deformation of the pair of first vertical wall portions 531c and 531d. As a result, the impact energy absorption effect of the first hat member 531 can be more reliably achieved during a side collision.

[0260] Furthermore, either the first reinforcing member 551 or the second reinforcing member 552 may be omitted. Also, the second reinforcing member 552 may be separated from the second top plate portion 532e. In this case, the second hat member 532 will have two closed cross-sections separated by the second reinforcing member 551, which will allow for a higher efficiency in absorbing impact energy during a side collision. Also, the first reinforcing member 551 may be separated from the first top plate portion 531e. In this case, the first hat member 531 will have two closed cross-sections separated by the first reinforcing member 551, which will allow for a higher efficiency in absorbing impact energy during a side collision.

[0261] [Seventh variation of the second embodiment] Figure 18 is a schematic cross-sectional view showing the main part of the seventh modification of the second embodiment of the present disclosure. In the embodiment, the first vertical wall portions 531c, 531d of the first hat member 531 are configured such that the distance between the first vertical wall portions 531c, 531d narrows continuously as they extend outward in the width direction X. On the other hand, in the seventh modification of the second embodiment, the first vertical wall portions 531c, 531d of the first hat member 531 are formed in a constricted shape overall in cross-section.

[0262] Each pair of first vertical wall sections 531c, 531d comprises a base end section 531c1, 531d1, a ridge section 531c2, 531d2 connected to the base end section 531c1, 531d1, and an end end section 531c3, 531d3 connected to the base end section 531c1, 531d1 via the ridge section 531c2, 531d2.

[0263] The base side portions 531c1 and 531d1 are spaced closer together as they extend outward in the width direction X. The ridge portions 531c2 and 531d2 are curved portions located midway along the first hat member 531 in the width direction X. The tip side portions 531c3 and 531d3 are spaced further apart as they extend outward in the width direction X.

[0264] As described above, according to the seventh modification of the second embodiment, the first hat member 531 has ridges 531c2 and 531d2 in addition to the first ridges 531f, 531g, 531h, and 531i. As a result, the first hat member 531 has many ridges, and during a side collision, the action of the numerous ridges in the impact absorbing member 530 can increase the efficiency of absorbing impact energy when the first hat member 531 deforms. Furthermore, when the first hat member 531 is crushed during a side collision, deformation occurs such that the ridges 531c2 and 531d2 come into contact with each other, forming two closed cross-sections in the first hat member 531, separated by the contact between the ridges 531c2 and 531d2. As a result, the number of closed cross-sections in the first hat member 531 increases, and as a result, the efficiency of absorbing impact energy can be increased. Furthermore, by changing the positions of the ridges 531c2 and 531d2 in the width direction X, the deformation pattern of the first hat member 531 during a side collision can be adjusted.

[0265] [Eighth variation of the second embodiment] Figure 19 is a schematic cross-sectional view showing the main part of the eighth modification of the second embodiment of the present disclosure. In the embodiment, a configuration in which the second flanges 532a, 532b and the first flanges 531a, 531b extend outward in the height direction Z with respect to the corresponding closed sections 562, 561 has been described as an example. However, this is not the case. As shown in Figure 19, for example, the second flanges 532a, 532b may be positioned toward the inside of the second closed section 562. Also, the first flanges 531a, 531b may be positioned toward the inside of the first closed section 561.

[0266] [Ninth Modification of the Second Embodiment] Figure 20 is a schematic cross-sectional view showing the main part of the ninth modification of the second embodiment of the present disclosure. In the embodiment, a configuration in which the shock-absorbing member 530 is formed using two hat members 531 and 532 has been described as an example. However, this is not the case. For example, the shock-absorbing member 530 may be formed of n (where n is a natural number of 3 or more) hat members.

[0267] In the ninth modification of the second embodiment, a form in which the shock absorbing member 530 is formed by three hat members 531, 532, and 533 will be described as an example. That is, in the ninth modification of the second embodiment, the shock absorbing member 530 is provided with a third hat member 533 (nth hat member) in addition to the second hat member 532 and the first hat member 531.

[0268] The first top plate portion 531e of the first hat member 531 is separated from the side sill outer 521 in the width direction X. The height H533 (the length of the third hat member 533 in the width direction X) of the third hat member 533 is not particularly limited and is appropriately set according to the height H532 of the second hat member 532 and the height H531 of the first hat member 531.

[0269] The third hat member 533 includes a pair of third flanges 533a, 533b joined to the first top plate portion 531e, a pair of third vertical wall portions 533c, 533d extending from the pair of third flanges 533a, 533b, and a third top plate portion 533e connecting between the pair of third vertical wall portions 533c, 533d.

[0270] Furthermore, in this modification, the third hat member 533 includes a pair of base end side third ridge line portions 533f, 533g and a pair of tip end side third ridge line portions 533h, 533i.

[0271] The pair of third flanges 533a, 533b are joined to the first top plate portion 531e of the first hat member 531 by the above-described joining method. The third flanges 533a, 533b may not be directly joined to the first top plate portion 531e and may be joined to the first top plate portion 531e via a patch (reinforcing member).

[0272] The lengths of the third flanges 533a and 533b are not particularly limited, but it is preferable that they do not protrude from the first top plate portion 531e in the height direction Z, as this allows for a lighter third hat member 533. Also, the end faces 533j and 531k of the third flanges 533a and 533b face the height direction Z and do not face the first hat member 531 in the height direction Z. The third flanges 533a and 533b may contact the first top plate portion 531e of the first hat member 531, but do not need to contact the first ridge portions 531h and 531i on the tip side. With the third flanges 533a and 533b arranged as described above, the vertical wall portions 533c and 533d of the third hat member 533 are positioned so that they are outside the region extending in the longitudinal direction of the vertical wall portions 531c and 531d of the first hat member 531. With this layout of the third hat member 533, when an impact load is applied to the third hat member 533, the third flanges 533a and 533b can firmly support the vertical wall portions 533c and 533d, and as a result, more impact energy can be absorbed by promoting the deformation of the vertical wall portions 533c and 533d between the base-side third ridge portions 533f and 533g and the tip-side third ridge portions 533h and 533i.

[0273] The upper third flange 533a extends upward from the upper third vertical wall portion 533c, and the lower third flange 533b extends downward from the lower third vertical wall portion 533d. These third flanges 533a and 533b are spaced apart from each other, and the third hat member 533 has a shape in which the inner side in the width direction X is open to the side sill inner 522. In this way, it is preferable that the third hat member 533 is joined only at the first top plate portion 531e of the first hat member 531, and that no other part of the impact absorbing member 530 is positioned between the third flanges 533a and 533b in the height direction Z. With such a configuration, the impact absorbing member 530 can be made lighter. Furthermore, when spot welding the first hat member 531 and the third hat member 533, the third flanges 533a and 533b, which are positioned outward in the height direction Z relative to the pair of third vertical wall portions 533c and 533d, and the first top plate portion 531e can be clamped together with a welding machine and welded. Thus, in the ninth modified example of this second embodiment, there are outward-facing third flanges 533a and 533b, which are positioned outward in the height direction Z relative to the pair of third vertical wall portions 533c and 533d. The lower end of the upper third flange 533a and the upper end of the lower third flange 533b are connected to the third vertical wall portions 533c and 533d via the base-side third ridge portions 533f and 533g.

[0274] The third ridge sections 533f and 533g on the base side are curved in an arc shape in cross-section and have the function of increasing the amount of impact energy absorbed by the third hat member 533 during impact absorption. The radius of curvature of the third ridge sections 533f and 533g on the base side in cross-section is about a few millimeters to several tens of millimeters. The radius of curvature of the third ridge sections 533f and 533g on the base side may be the same as the radius of curvature of the first ridge sections 531f and 531g on the base side of the first hat member 531, it may be less than the radius of curvature of the first ridge sections 531f and 531g on the base side, or it may be greater than the radius of curvature of the first ridge sections 531f and 531g on the base side.

[0275] The pair of third vertical wall sections 533c and 533d of the third hat member 533 are arranged along the width direction X, and the distance between the pair of third vertical wall sections 533c and 533d widens as it moves toward the side sill inner 522 side. This layout of the pair of third vertical wall sections 533c and 533d allows the third hat member 533 to evenly receive the impact load acting inward from the side sill outer 521 in the width direction X. Therefore, the amount of impact energy absorbed by the impact absorbing member 530 can be increased during a side collision. The pair of third vertical wall sections 533c and 533d may also be arranged parallel (horizontally) to the width direction X, or the distance between the pair of third vertical wall sections 533c and 533d may narrow as it moves toward the side sill inner 522 side.

[0276] The upper third vertical wall section 533c and the lower third vertical wall section 533d are connected to the third top plate section 533e via the tip-side third ridge sections 533h and 533i.

[0277] The third ridge sections 533h and 533i on the tip side are curved in an arc shape in cross-section and have the function of increasing the amount of impact energy absorbed by the third hat member 533 during impact absorption. The radius of curvature of the third ridge sections 533h and 533i on the tip side in cross-section is approximately a few millimeters to several tens of millimeters.

[0278] The third top plate portion 533e is the part of the impact absorbing member 530 that first receives the impact load during a side collision. The third top plate portion 533e suppresses out-of-plane deformation that would cause the pair of third vertical wall portions 533c and 533d connected to the third top plate portion 533e to tilt inward.

[0279] In this embodiment, the third top plate portion 533e is in contact with the side wall 713 of the side sill outer 521, but is not joined to the side wall 713 of the side sill outer 521.

[0280] With such a favorable configuration, it is easier to install the shock-absorbing member 530 inside the side sill 515. This is because it eliminates the need to join the third top plate 533e to the side wall 713 of the side sill outer 521. If the third top plate 533e were to be joined to the side wall 713 of the side sill outer 521 by welding, the welding machine would need to be sandwiched between the third top plate 533e and the side wall 713. This would make the process of installing the shock-absorbing member 530 inside the side sill 515 more time-consuming. This cumbersome process would be the same regardless of whether the welding method used was spot welding or laser welding.

[0281] Furthermore, with such a favorable configuration, during a side collision of a vehicle, the impact absorbing member 530 can perform a three-stage crushing process by sequentially crushing its three closed cross-sections 563, 561, and 562 while minimizing the influence of deformation of the side sill outer 521, thereby increasing the efficiency of impact energy absorption. In other words, during a side collision of a vehicle, the impact absorbing member 530 can deform and absorb the impact while being less affected by the deformation of the side sill outer 521. This allows the impact absorbing member 530 to exhibit its impact absorption performance more effectively.

[0282] Furthermore, the third top plate portion 533e may be separated from the side wall 713 of the side sill outer 521 to such an extent that it does not come into contact with the side wall 713 even with vibrations during vehicle operation, or to a sufficiently large extent.

[0283] Thus, if the top plate portion 533e is separated from the side sill outer 521, deformation of the members due to the transmission of impact from the side sill outer 521 to the impact absorbing member 530 and the side sill inner 522 can be suppressed when a relatively minor side collision occurs to the vehicle. When a relatively minor side collision occurs to the vehicle, an impact acts on the side sill outer 521, but only a small amount of this impact is transmitted from the side sill outer 521 to the impact absorbing member 530. Therefore, less impact is transmitted to the side sill inner 522 via the impact absorbing member 530. In such a case, the amount of deformation of the side sill 515 is reduced, so a decrease in the vehicle's driving performance (straight-line performance, etc.) can be suppressed. In addition, when repairing the vehicle, while the side wall 713 of the side sill outer 521 needs to be repaired, the impact absorbing member 530 and the side sill inner 522 do not need to be repaired, thus reducing the effort and cost of vehicle maintenance. On the other hand, when a large side collision occurs to the vehicle, the impact is transmitted from the side sill outer 521 to the side sill inner 522 via the impact absorbing member 530, enabling efficient absorption of impact energy through deformation of the impact absorbing member 530 and the side sill inner 522.

[0284] It is preferable that the third top plate portion 533e is arranged parallel to the side wall 713, in that the impact load from the side wall 713 of the side sill outer 521 is received by the entire third top plate portion 533e. The third top plate portion 533e connects the pair of third vertical wall portions 533c and 533d. It is preferable that the third top plate portion 533e is arranged parallel to the second top plate portion 532e and the first top plate portion 531e, in that it can increase the efficiency of absorbing impact energy acting in the width direction X during a side collision.

[0285] With the above configuration, the pair of vertical wall portions 531c, 531d (a pair of first portions) of the first hat member 531, the pair of vertical wall portions 532c, 532d (a pair of second portions) of the second hat member 532, and the pair of vertical wall portions 533c, 533d (a pair of third portions) of the third hat member 533 cooperate to form the pair of vertical wall portions 545, 546 in the hat-shaped portion 540 of the impact-absorbing member 530.

[0286] Thus, in the ninth modified example of this second embodiment, the impact absorbing member 530 has an nth (n is a natural number of 3 or more) hat member formed in a hat shape in cross-section. The nth hat member (third hat member 533) includes a pair of nth flanges (third flanges 533a, 533b), a pair of nth vertical wall portions (third vertical wall portions 533c, 533d) extending from the pair of nth flanges, and an nth top plate portion (third top plate portion 533e) connecting the pair of nth vertical wall portions. Furthermore, each hat member (hat members 531 to 533) is arranged along the width direction X, and in adjacent hat members (second hat member 532 and first hat member 531; first hat member 531 and third hat member 533), the top plate portion and the pair of flanges are joined to each other.

[0287] As described above, since the impact absorbing member 530 is formed from three or more hat members, more ridges can be provided in the impact absorbing member 530. This increases the efficiency of impact energy absorption when the closed cross-sectional shapes of the second hat member 532, the first hat member 531, and the third hat member 533 deform due to the action of the numerous ridges in the impact absorbing member 530 during a side collision. In particular, since the third hat member 533, which is the first to receive the impact load in the impact absorbing member 530, has many ridges, the amount of impact energy absorbed when the third hat member 533 is crushed can be increased. As a result, the efficiency of impact energy absorption by the impact absorbing member 530 can be increased. This makes the impact absorbing member 530 lighter while increasing the amount of impact energy absorbed by the impact absorbing member 530, thus increasing the weight efficiency of impact energy absorption. Furthermore, by adjusting the shape of each hat member 531 to 533, the timing of deformation initiation and the manner of deformation of each hat member 531 to 533 can be set during a side collision. This allows the impact absorption operation of the impact absorbing member 530 during a side collision to be set according to the characteristics of the vehicle (such as the presence or absence of the battery case 600 and the layout of the battery case 600). Therefore, the vehicle can achieve higher side collision resistance. Moreover, since the impact absorbing member 530 is formed from multiple members (in this embodiment, the second hat member 532, the first hat member 531, and the third hat member 533), the degree of freedom in setting the shape is greater compared to when the impact absorbing member 530 is formed from a single member.

[0288] In the ninth modification of this second embodiment, the impact absorbing member 530 was described as being formed of three hat members 531, 532, and 533, but the impact absorbing member 530 may be formed of four or more hat members. In this case as well, the multiple hat members are arranged along the width direction X, and the top plate portion and a pair of flanges are joined to each other in adjacent hat members. In this case as well, it is preferable that the length in the height direction Z of the impact absorbing member 530 decreases in stages as it moves outward in the width direction X. This allows the impact energy caused by the crushing of the impact absorbing member 530 to be absorbed efficiently.

[0289] [Tenth variation of the second embodiment] Figure 21 is a schematic cross-sectional view showing the main part of the tenth modification of the second embodiment of the present disclosure. In the second embodiment, a pair of second flanges 532a and 532b of the impact absorbing member 530 were joined to the side sill inner 522. On the other hand, in the tenth modification of the second embodiment shown in Figure 21, the first top plate portion 531e is joined to the side sill inner 522 by the joining method described above. That is, in the tenth modification of the second embodiment, the impact absorbing member 530 is arranged in a shape symmetrical to the impact absorbing member 530 in the embodiment in the width direction X. Furthermore, a pair of second flanges 532a and 532b of the second hat member 532 are joined to the reinforcing plate 580 by the joining method described above. The reinforcing plate 580 is formed of the same material as the first hat member 531 or the second hat member 532, and joins the second flanges 532a and 532b to each other.

[0290] In the tenth modified example of the second embodiment, the second hat member 532 is positioned adjacent to the side sill outer 521, and the first hat member 531 is positioned closer to the side sill inner 522 than the side sill outer 521.

[0291] Thus, by joining the first hat member 531 of the impact absorbing member 530 to the side sill inner 522, the efficiency of absorbing impact energy during a side collision can be increased.

[0292] Furthermore, by positioning the second hat member 532 adjacent to the side sill outer 521 and the first hat member 531 closer to the side sill inner 522, the efficiency of absorbing impact energy during a side collision can also be increased.

[0293] [11th Modification of the Second Embodiment] Figure 22 is a schematic cross-sectional view showing the main part of an eleventh modification of the second embodiment of the present disclosure. In the embodiment, a configuration in which the impact absorbing member 530 is located within the side sill 515 has been described as an example. However, this is not the case. For example, the impact absorbing member 530 may be located laterally to the side of the side sill 515 in the width direction X.

[0294] In this modified example, the impact absorbing member 530 is positioned on the vehicle side relative to the side sill 515 in the width direction X. The impact absorbing member 530 may have its second flanges 532a and 532b joined to the side wall 600b of the battery case 600, etc., by the joining method described above, or its first top plate portion 531e may be joined to the side wall 723 of the side sill inner 522, etc., by the joining method described above. In the impact absorbing member 530, it is sufficient that at least one of the first top plate portion 531e and the second flanges 532a and 532b is joined to the corresponding battery case 600 and side sill inner 522. In this way, even when the impact absorbing member 530 is positioned between the side sill 515 and the battery case 600 on the side of the side sill 515, the impact absorbing member 530 can absorb impact energy by being crushed during a side collision. In this modified example, the widthwise end 600a of the battery case 600 is located at the top of the battery case 600, but it may also be located at the bottom of the battery case 600. In this modified example, the impact absorbing member 530 is described as being located between the side sill 515 and the battery case 600, but this is not required. The impact absorbing member 530 may be located near the side sill 515, for example, below the side sill 515.

[0295] In this modified example, a configuration similar to that of the impact-absorbing member 530 in the second embodiment was described as an example, but instead, the impact-absorbing member 530 described in each modified example may be used. In this case as well, the second flanges 532a, 532b and the first top plate portion 531e of the impact-absorbing member 530 are joined to the side sill 515, the battery case 600, or the members surrounding the impact-absorbing member 530.

[0296] Furthermore, as shown in Figure 23, which illustrates a modified example of the 11th modified example of the second embodiment, the impact absorbing member 530 may be separated from the side sill 515.

[0297] [Twelfth variation of the second embodiment] Figure 24 is a schematic cross-sectional view showing the main part of the twelfth modification of the second embodiment of the present disclosure. In the second embodiment and each of the above modifications, a configuration in which the battery case 600 is positioned in contact with the floor panel 518 has been described as an example. However, this is not required. For example, the battery case 600 may be positioned at a distance from the floor panel 518.

[0298] [13th variation of the second embodiment] In the second embodiment, an example was described in which the tensile strength TS1 (Vickers hardness HV1) of the first hat member 531 is lower than the tensile strength TS2 (Vickers hardness HV2) of the second hat member 532. However, this is not required. The tensile strength TS1 (Vickers hardness HV1) of the first hat member 531 may be higher than the tensile strength TS2 (Vickers hardness HV1) of the second hat member 532 (TS1 > TS2). That is, the strength on the side sill outer 521 side of the impact absorbing member 530 may be higher than the strength on the side sill inner 522 side. In this case, an example can be given in which the tensile strength TS1 of the first hat member 531 and the tensile strength TS2 of the second hat member 532 are swapped in the embodiment.

[0299] This configuration allows for a larger peak impact load acting on the first hat member 531 during a side collision, enabling the first hat member 531 to absorb more impact energy.

[0300] Furthermore, an example can be given of a configuration in which the plate thickness t2 of the second hat member 532 and the plate thickness t1 of the first hat member 531 are swapped (t1>t2) in the second embodiment. With such a configuration, the peak of the impact load acting on the first hat member 531 during a side collision can be made larger, allowing the first hat member 531 to absorb more impact energy.

[0301] [14th Modification of the Second Embodiment] Figure 25 is a schematic cross-sectional view showing the main part of the 14th modification of the second embodiment of this disclosure. Figure 26 is a schematic perspective view showing the main part of the 14th modification of the second embodiment of this disclosure. In the second embodiment and each modification, the first flanges 531a and 531b of the first hat member 531 are joined to the second top plate portion 532e of the second hat member 532, but not to the tip-side second ridge portions 532h and 532i or the vertical wall portions 532c and 532d. In contrast, as shown in the 14th modification of the second embodiment, the first flanges 531a and 531b of the first hat member 531 may also be joined to the tip-side second ridge portions 532h and 532i and the vertical wall portions 532c and 532d of the second hat member 532. In this case as well, the first flanges 531a and 531b are also joined to the second top plate portion 532e.

[0302] In this 14th modification, beads 570 (571, 572) may be formed on the impact absorbing member 530. In this 14th modification, the beads 571, 572 are provided to increase the rigidity (at least one of bending rigidity and torsional rigidity) of the first hat member 531. Bead 571 is formed on one vertical wall portion 531c of the first hat member 531, and bead 572 is formed on the other vertical wall portion 531d of the first hat member 531. Preferably, the pair of beads 571, 572 are aligned in the front-rear direction Y. The beads 571, 572 are formed by recessing the corresponding vertical wall portions 531c, 531d of the first hat member 531. The beads 571, 572 may also be formed by making the corresponding vertical wall portions 531c, 531d of the first hat member 531 convex in the height direction Z. The dimensions of each bead 571, 572 in the width direction X, the front-to-back direction Y, and the height direction Z are not particularly limited, and it is sufficient that at least one of the bending rigidity and torsional rigidity of the first hat member 531 is improved.

[0303] [Other variations of the second embodiment] In each of the embodiments and modifications described above, a reinforcing member may be interposed between the impact absorbing member 530 and the floor cross members 516 and 517. This reinforcing member is positioned to prevent the floor cross members 516 and 517 from breaking due to the impact load transmitted from the impact absorbing member 530 to the floor cross members 516 and 517 via the side sill 515.

[0304] Furthermore, the impact-absorbing member 530 in the above-described embodiments and each of its modifications may be made of an aluminum alloy or a composite material such as CFRP (Carbon Fiber Reinforced Plastics).

[0305] Furthermore, although the embodiments and modifications described above have mainly described a monocoque body structure, this is not required. For example, this disclosure may be applied to a ladder frame body structure. [Industrial applicability]

[0306] This disclosure can be broadly applied to side sill structures and undercarriage structures of automobiles. [Explanation of symbols]

[0307] 14. Side sill structure 15 Side sill 16,17 Floor cross member 21 Side sill outer 22 Side sill inner 23 Closed section space 30 Impact absorbing material 31 First hat member 32 Second hat member 40 Hat-shaped section 41. First top panel 42. Second top panel 45, 46 Pair of vertical wall sections 45a, 46a A pair of first parts 45b, 46b A pair of second parts 47, 48 Pair of flanges 61 1st closed section 62 Second closed section 70 Bead 100 Battery Case 101 Battery 514 Side sill structure 515 Side Sill 516, 517 Floor cross member 530 Shock-absorbing material 521 Side sill outer 522 Side Sill Inner 523 Closed section space 531 First hat member 532 Second hat member 540 Hat-shaped section 531e First top panel 532e Second top panel 545,546 Pair of vertical wall sections 531c, 531d Vertical wall section (a pair of first sections) 532c, 532d Vertical wall section (a pair of second parts) 532a, 532b Pair of flanges 561 1st closed section 562 Second closed section 570 bead 600 Battery Case 601 Battery X Width direction Y (forward / backward direction) Z (height direction)

Claims

1. A side sill comprising a side sill outer and a side sill inner positioned inward in the vehicle width direction relative to the side sill outer, extending in the vehicle longitudinal direction and forming a closed cross-sectional space in a cross section perpendicular to the vehicle longitudinal direction, An impact-absorbing member formed from multiple members, Equipped with, The impact absorbing member comprises, in its cross-section, a hat-shaped portion having a first top plate portion extending in the vehicle height direction, and a pair of vertical wall portions extending from both ends of the first top plate portion in the vehicle height direction along the vehicle width direction, and a second top plate portion arranged at a distance from the first top plate portion in the vehicle width direction and connecting the pair of vertical wall portions. The second top plate portion divides the inner space of the hat-shaped portion in the vehicle width direction, thereby forming a first closed cross-section portion including the first top plate portion and a second closed cross-section portion adjacent to the first closed cross-section portion in the vehicle width direction. The impact absorbing member is either separated from the side sill outer or in contact with the side sill outer without being joined to it, in a side sill structure.

2. The aforementioned shock-absorbing member is formed by combining a first hat member and a second hat member. The side sill structure according to claim 1, wherein the top plate portion of the first hat member constitutes the first top plate portion, the top plate portion of the second hat member constitutes the second top plate portion, and a pair of first portions which are a pair of vertical wall portions of the first hat member and a pair of second portions which are a pair of vertical wall portions of the second hat member cooperate to form a pair of the vertical wall portions.

3. The side sill structure according to claim 2, wherein the Vickers hardness of the first hat member is lower than that of the second hat member.

4. The side sill structure according to claim 2, wherein the Vickers hardness of the first hat member is higher than that of the second hat member.

5. The side sill structure according to claim 2, wherein the thickness of the first hat member is smaller than the thickness of the second hat member.

6. The side sill structure according to claim 2, wherein the thickness of the first hat member is greater than the thickness of the second hat member.

7. Regarding the Vickers hardness HV1 and plate thickness t1 of the first hat member, and the Vickers hardness HV2 and plate thickness t2 of the second hat member, 180 ≤ HV1, HV2 ≤ 780, 0.8 mm ≤ t1 t2 ≤ 2.3 mm, HV1 × t1 < HV2 × t2 The side sill structure according to claim 2.

8. The side sill structure according to claim 2, wherein the impact absorbing member comprises a hat member that forms the hat-shaped portion and a top plate member that forms the second top plate portion.

9. Regarding the Vickers hardness HV2 and plate thickness t2 of the hat member, and the Vickers hardness HV1 and plate thickness t1 of the top plate member, 180 ≤ HV1, HV2 ≤ 780, 0.8 mm ≤ t1 t2 ≤ 2.3 mm, HV1 × t1 < HV2 × t2 The side sill structure according to claim 8.

10. The side sill structure according to claim 1, wherein the second top plate portion of the impact absorbing member has a shape that is convex toward the first top plate portion in the cross-section.

11. The side sill structure according to claim 1, wherein the impact absorbing member is made of steel plate.

12. The hat-shaped portion comprises a pair of flanges extending from the pair of vertical wall portions, The side sill structure according to claim 1, wherein the pair of flanges are joined to the side sill inner.

13. The side sill structure according to claim 1, wherein a bead is formed on the impact absorbing member.

14. The side sill structure according to claim 1, wherein the impact absorbing member is supported by the side sill within the closed cross-sectional space, or is positioned laterally to the side of the side sill in the vehicle width direction.

15. The first hat member includes a pair of first flanges, a pair of first vertical wall portions extending from the pair of first flanges, and a first top plate portion connecting the pair of first vertical wall portions. The side sill structure according to claim 2, wherein the second hat member includes a pair of second flanges, a pair of second vertical wall portions extending from the pair of second flanges, and a second top plate portion connecting the pair of second vertical wall portions and joined to the pair of first flanges.

16. The side sill structure according to claim 2, wherein at least one of the hat members further comprises a reinforcing member.

17. The impact absorbing member further comprises an nth (n is a natural number of 3 or more) hat member formed in a hat shape in its cross-section, The nth hat member includes a pair of nth flanges, a pair of nth vertical wall portions extending from the pair of nth flanges, and an nth top plate portion connecting the pair of nth vertical wall portions. The side sill structure according to claim 2, wherein each of the hat members is arranged along the vehicle width direction, and in adjacent hat members, the top plate portion and a pair of flanges are joined to each other.

18. The side sill structure according to claim 1, wherein the impact absorbing member is made of steel plate.

19. A side sill structure according to any one of claims 1 to 18, The side sills are provided in pairs, spaced apart in the vehicle width direction. The vehicle further comprises a plurality of cross members positioned between a pair of side sills and extending in the vehicle width direction, An undercarriage of an automobile, wherein the impact-absorbing members are provided inside each of the pair of side sills or on the inside in the vehicle width direction.

20. The undercarriage structure of an automobile according to claim 19, further comprising a battery case disposed below the cross member and housing a battery.