Automobile side sill structure

Abstract

To provide an automobile side sill structure that can provide improved collision energy absorption performance at the time of side collision.SOLUTION: A side sill structure 1 according to the present invention includes: an impact absorption structure 20 arranged at a side sill 10 and having a vehicle interior-side end portion 20a in a vehicle-width direction connected to a vertical surface portion 11a of a side sill inner 11 and configured to absorb impact input to the side sill 10 at the time of side collision of a vehicle; and a recessed portion 30 disposed in the vertical surface portion 11a of the side sill 11 to restrain the vehicle interior-side end portion 20a in a vehicle vertical direction. The impact absorption structure 20 has a waveform shape in which protruded and recessed shapes are alternately continuous in a vehicle longitudinal direction and includes a pair of wave-shaped parts 21 and 23 arranged in the vehicle vertical direction. A recessed shape 21b of the upper wave-shaped part 21 and a recessed shape 23b of the lower wave-shaped part 23 are arranged to face each other, and the facing recessed shapes 21b and 23b are joined in a shifted state in the vehicle longitudinal direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a side sill structure for an automobile that improves collision performance by absorbing the impact force applied during a side collision of the vehicle. [Background technology]

[0002] In general, electric vehicles are equipped with a battery module below the floor panel between the left and right side sills in the vehicle width direction. The battery module is composed of battery cells (also called battery packs) and a battery case for storing them.

[0003] The battery case is made of high-rigidity and high-strength materials to protect the battery cells from the impact load input during a collision of an electric vehicle. In addition, materials that absorb the collision energy by deforming due to the impact (load) input to the vehicle during a collision are arranged around the battery case. In particular, during a side collision, the side sill deforms in response to the load input from the side of the vehicle to absorb the collision energy, and the remaining load that cannot be absorbed is received by the floor cross member or the battery case side member, thereby protecting the battery cells.

[0004] If the amount of deformation required for the side sill to absorb the collision energy during a side collision can be reduced, the part of the side sill that absorbs the collision energy can be reduced, making it possible to achieve a space-saving side sill structure. In an electric vehicle equipped with such a side sill structure, the volume of the battery module can be increased by the amount of the side sill reduction, which increases the amount of battery that can be installed, leading to an increase in the cruising range. For these reasons, a space-saving side sill structure that is excellent in absorbing collision energy during a side collision and also has excellent performance is required for electric vehicles.

[0005] Several technologies have been proposed to increase the rigidity of the side sill and improve its ability to absorb collision energy during a side collision. For example, Patent Document 1 discloses a side member structure (side sill) for a vehicle body which is equipped with an impact absorbing member which is arranged inside a tube extending in the fore-and-aft direction of the vehicle body, has a plurality of ridge portions spaced apart from one another along the width direction of the vehicle body, and has a wavy shape which moves up and down along the fore-and-aft direction of the vehicle body.

[0006] Patent Document 2 discloses a vehicle body side structure (side sill) equipped with an impact absorbing member having a web which is a corrugated plate that is arranged inside a cylinder extending in the fore-and-aft direction of the vehicle body and repeatedly bends alternately up and down along the fore-and-aft direction.

[0007] Patent Documents 3 and 4 disclose a vehicle body structure that includes a reinforcing member that constitutes at least a part of a continuous tubular structure formed inside a side sill, the continuous tubular structure having a shape made up of multiple connected polygonal closed cross sections when viewed from the vehicle width direction.

[0008] Patent Document 5 discloses a vehicle body structure in which an energy absorbing member, which is a corrugated plate that extends in the vehicle width direction and repeatedly bends or curves up and down, is disposed and fixed within a side sill. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2021-146973 A [Patent Document 2] Patent No. 7095821 [Patent Document 3] JP 2020-111267 A [Patent Document 4] Patent Publication No. 2021-024350 [Patent Document 5] JP 2023-056569 A Summary of the Invention [Problem to be solved by the invention]

[0010] According to Patent Document 1, even if an impact is applied in a side collision with a pole, the locally large impact energy (corresponding to the "collision energy" in this application; the same applies below) can be efficiently absorbed by the entire impact absorbing member. Also, according to Patent Document 2, even if an impact load acts in the vehicle width direction, the impact energy (corresponding to the collision energy in this application) can be efficiently absorbed, deformation toward the inside of the vehicle can be suppressed, and the battery case that houses the battery pack can be effectively protected. However, in the technologies disclosed in Patent Documents 1 and 2, the corrugated impact absorbing member is made of a single metal plate, so it has low rigidity and is prone to deformation in which the corrugated openings open in the vehicle longitudinal direction due to impact load. When deformation occurs in which the corrugated openings open, there is a problem that the collision energy absorption characteristics are reduced.

[0011] According to Patent Document 3, the side impact performance can be improved by improving the reaction force of the reinforcing member by suitably arranging the reinforcing member inside the side sill. However, since the continuous tubular structure is structured to expand and contract in the longitudinal direction of the vehicle body during a side impact, it is deformed by the force pushing it out in the longitudinal direction of the vehicle body, and there is a risk that the originally expected reaction force of the reinforcing member cannot be secured.

[0012] According to Patent Document 4, by further providing a deformation control member for suppressing deformation of the continuous tubular structure in the longitudinal direction of the vehicle body in the vehicle body structure according to Patent Document 3, it is possible to restrict deformation of the continuous tubular structure in the longitudinal direction of the vehicle body during a side collision. Furthermore, it is expected that the reaction force of the reinforcing member can be improved, and the collision energy absorption performance can be improved. However, the vehicle body structure according to Patent Document 4 has a problem that the number of parts and the weight of the parts increase due to the provision of the deformation control member.

[0013] According to Patent Document 5, when a collision load is input during a side collision, the energy absorbing member in the side sill is easily crushed, and the collision energy can be absorbed well. However, when the energy absorbing member is made by bonding two metal plates together, a polygonal shaped portion and a bonding portion are generated, and since these have different rigidities, the collision performance differs depending on the collision position. In order to reduce such a difference in collision performance, it is effective to improve the rigidity of the bonding portion, but this requires an increase in plate thickness, which leads to a problem of increased weight.

[0014] In addition, in the technology disclosed in Patent Document 5, when a polygonal shaped part is manufactured using an extruded material, a method of gradually changing the cross-sectional area in the collision direction to stabilize buckling during a collision, or a method of inducing buckling by forming a bead part perpendicular to the collision direction are adopted. However, since the cross section of the extruded material is constant in the extrusion direction, it is extremely difficult to gradually change the cross-sectional area, and forming a bead part increases the number of processes, which leads to increased manufacturing costs.

[0015] The present invention has been made to solve the above-mentioned problems, and has an object to provide an automobile side sill structure that improves collision performance in the event of a side collision without increasing weight or manufacturing costs. [Means for solving the problem]

[0016] (1) The side sill structure of the present invention for an automobile includes a side sill having a side sill inner having a groove shape extending in a vehicle longitudinal direction and opening toward the vehicle outer side in the vehicle width direction, and a side sill outer having a groove shape extending in the vehicle longitudinal direction and opening toward the vehicle inner side in the vehicle width direction, the side sill inner and the side sill outer being joined together with their opening sides facing each other, an impact absorbing structure that is disposed within the side sill, the impact absorbing structure having an end portion on an inner side of the vehicle in the vehicle width direction connected to a bottom portion of the groove shape of the side sill inner and / or an end portion on an outer side of the vehicle in the vehicle width direction connected to a bottom portion of the groove shape of the side sill outer, and that absorbs an impact input to the side sill in the event of a side collision of the vehicle; a vertical restraint structure that is provided at the bottom of the side sill inner and that restrains the end portion on the vehicle interior side in the vertical direction of the vehicle during a side collision of the vehicle, The shock absorbing structure includes: The vehicle has a wave shape in which convex shapes and concave shapes are alternately continuous in the vehicle longitudinal direction in a cross section perpendicular to the vehicle width direction, and is configured to include a pair of wave-shaped parts arranged in the vehicle up-down direction, The pair of corrugated parts are made of metal plates, and are arranged so that the concave shape of the upper corrugated part faces the concave shape of the lower corrugated part, and the opposing concave shapes are joined in a state where they are shifted in the longitudinal direction of the vehicle.

[0017] (2) In the above (1), the vertical restraint structure is a recess provided at the bottom of the groove shape of the side sill inner panel and recessed toward the vehicle inner side in the vehicle width direction, The end portion of the shock absorbing structure on the vehicle interior side is inserted into the recess.

[0018] (3) In the above (1) or (2), The shock absorbing structure has a vehicle outer end in the vehicle width direction that abuts against the bottom of the groove shape of the side sill outer panel.

[0019] (4) In any one of (1) to (3) above, The shift amount W2 of the opposing concave shapes in the upper and lower corrugated parts in the vehicle longitudinal direction is characterized by being 20% ​​or more and 50% or less of the center-to-center distance W1 between the convex shapes and the concave shapes adjacent in the vehicle longitudinal direction in the corrugated parts.

[0020] (5) In the above (2), The recess amount D of the recess provided in the side sill inner is characterized in being 0.8 to 1.2 times the height h of the shock absorbing structure in the vehicle vertical direction.

[0021] (6) In any one of (1) to (5) above, The corrugated part is characterized in that it is made of a metal plate having a tensile strength of 590 MPa or more. Effect of the Invention

[0022] According to the present invention, the buckling resistance against the impact load input to the side sill during a side collision can be increased, and the impact absorbing structure can be crushed while maintaining a state of high deformation resistance, thereby reducing the amount of deformation in the vehicle width direction and achieving high collision energy absorption characteristics. In addition, the concave shape of the upper corrugated part and the concave shape of the lower corrugated part in the shock absorbing structure face each other and are joined asymmetrically in the vertical direction while being shifted in the vehicle longitudinal direction, so that the positions of the ridgelines of the convex and concave shapes of each corrugated part in the vehicle longitudinal direction can be dispersed.Furthermore, the buckling load (peak load) during a side collision can be kept low, and differences (variations) in collision performance depending on the position where the impact load is input can be made less likely to occur. Furthermore, when the present invention is applied to an electric vehicle, the space required to absorb collision energy can be reduced, making it possible to increase the volume of the battery module mounted on the electric vehicle. Furthermore, since the shock absorbing structure of the present invention has high bending rigidity, it is not necessary to increase the plate thickness in order to improve rigidity, and an increase in the weight of the vehicle body can also be suppressed. [Brief description of the drawings]

[0023] [Figure 1]1A and 1B are diagrams illustrating an example of a configuration of a side sill structure according to an embodiment of the present invention ((a) is a cross-sectional view perpendicular to the vehicle longitudinal direction, and (b) is a cross-sectional view perpendicular to the vehicle width direction). [Diagram 2] FIG. 1 is a diagram for explaining an ideal load-stroke curve of a side sill structure during a side collision of a vehicle (solid line: load-stroke curve in a conventional side sill structure, dashed line: ideal load-stroke curve). [Diagram 3] 1 is a development view of a shock absorbing structure of a side sill structure according to an embodiment of the present invention; [Figure 4] 1 is a diagram illustrating the amount of shift W2 in the vehicle longitudinal direction between the upper corrugated part and the lower corrugated part of the shock absorbing structure in the side sill structure according to an embodiment of the present invention. FIG. [Diagram 5] 1 is a diagram showing an example of a vehicle side structure provided with a side sill structure according to an embodiment of the present invention; [Figure 6] 11A and 11B are diagrams showing a modified example of a vertical restraint structure that restrains the end portion of the impact absorbing structure on the vehicle interior side in the vertical direction of the vehicle in the side sill structure according to the embodiment of the present invention. [Figure 7] 1 is a diagram illustrating a support structure that supports a shock absorbing structure disposed within a side sill in a side sill structure according to an embodiment of the present invention. FIG. [Figure 8] FIG. 2 is a diagram for explaining a test specimen that was analyzed in a crash test simulating a side crash of a vehicle in Example 1. [Figure 9] FIG. 2 is a diagram showing a side sill structure that is a test subject in a crash test simulating a side crash of a vehicle in the first embodiment. [Figure 10] 1A and 1B are diagrams showing the deformation state of the impact absorbing structure in a crash analysis simulating a side crash of a vehicle in Example 1 ((a) top view of the impact absorbing structure, (b) perspective view of the impact absorbing structure from the outside of the vehicle, (c) cross-sectional view of the side sill structure). [Figure 11] 4A to 4C are diagrams illustrating the deformation behavior of the shock absorbing structure in a crash analysis simulating a side crash of a vehicle in the first embodiment. [Figure 12]4 is a graph showing the relationship between the amount of collision energy absorbed by the side sill structure and the maximum load input to the side sill structure during a side collision in a collision test in Example 1. [Figure 13] 1A to 1C are cross-sectional views of impact absorbing structures that were the subject of crash tests during a side collision in Example 2 ((a) Example 3 of the invention, (b) Comparative Examples 6 and 7, and (c) Comparative Example 8). [Figure 14] 1A and 1B are cross-sectional views showing deformation behavior of the side sill structure during a side collision in Example 2 ((a) side sill structure according to Example 3, and (b) side sill structure according to Comparative Example 6). [Figure 15] 13 is a load-stroke curve obtained by collision analysis for a side collision test of test specimens according to Example 3 and Comparative Example 6 in Example 2. [Figure 16] 13 is a graph showing (a) a load-stroke curve and (b) a transition of the collision absorbed energy obtained by collision analysis for side collision tests of test specimens according to Example 3, Comparative Example 7, and Comparative Example 8 in Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] <Background to the invention> The technologies disclosed in the above-mentioned Patent Documents 1 to 5 all involve disposing, within the side sill, a member having a wave shape in which a shape that is bent or curved in the vertical direction of the vehicle is repeated in the longitudinal direction of the vehicle (Patent Documents 1 and 2: impact absorbing member, Patent Documents 3 and 4: reinforcing member, Patent Document 5: energy absorbing member). Hereinafter, a structure in which a wave-shaped member is disposed within the side sill will be referred to as a "conventional side sill structure."

[0025] In general, a side sill structure absorbs the collision energy when a load (impact load) input to the side sill during a side collision is transmitted to a load-bearing part such as a cross member arranged on the inside of the vehicle, and the reaction force from the load-bearing part causes the side sill structure to collapse. In the process of the collapse of a conventional side sill structure, the corrugated member arranged in the side sill buckles and deforms in a bellows-like manner, corrugating to have multiple sides. In the following description, the lantern-shaped ("bellows-shaped" or "sausage-like structure") buckling deformation is also referred to as the "lantern buckling mode" or "axial crushing mode."

[0026] In the event of a side collision in which an impact object collides with the side of a vehicle equipped with a conventional side sill structure in which a corrugated member is arranged inside the side sill, the relationship between the load input to the side sill and the stroke, which is the amount of penetration of the impact object into the vehicle interior, is shown in the load-stroke curve in Figure 2.

[0027] In the graph shown in FIG. 2, the load on the vertical axis is the contact reaction force from load-bearing parts such as cross members, and the value obtained by integrating the load with respect to the stroke (the deformation amount in the vehicle width direction of the side sill structure), i.e., the area enclosed by the load-stroke curve, represents the amount of collision energy absorbed.

[0028] In the conventional side sill structure, as shown by the load-stroke curve indicated by the solid line in Figure 2, after elastic deformation, the ridges of the corrugated members buckle into a lantern shape (lantern buckling mode), and the load continues to increase as the stroke increases.

[0029] Normally, load-bearing parts such as cross members have a set allowable load (buckling strength Fa). Therefore, in order for the battery case to be protected by load-bearing parts during a side collision, the maximum load (Fmax) must be equal to or less than the allowable load (Fa), as shown by the solid line load-stroke curve in Figure 2.

[0030] Therefore, in conventional side sill structures, in order to keep the maximum load (Fmax) below the allowable load (Fa) of the load-bearing parts, it was necessary to set the thickness and material (e.g., yield stress) of the metal plates constituting the corrugated members so that the corrugated members would buckle and deform at a buckling load (Fb) lower than the maximum load (Fmax). Therefore, in side sill structures in which corrugated members are arranged, it was necessary to increase the deformation amount of the side sill (S1 in Fig. 2) so that the desired amount of collision energy absorption could be obtained during a side collision.

[0031] Meanwhile, in the case of electric vehicles, in order to increase the volume of the battery module, it has been required to reduce the amount of deformation of the side sill required for absorbing a certain amount of collision energy using the side sill structure. Therefore, the inventors thought that in order to reduce the stroke while ensuring the same amount of collision energy absorption as conventional side sill structures, it would be necessary to design a side sill structure that achieves the ideal load-stroke curve shown by the dashed line in Figure 2.

[0032] The ideal load-stroke curve shown in Figure 2 is one that increases the rigidity of the side sill structure to speed up the rise of the load generated on the side sill during a side collision, and increases the buckling load to approximately the maximum load (Fmax) of a conventional side sill structure, while suppressing the increase in load during the collision process after buckling deformation and maintaining the load constant. With a side sill structure that can realize such a load-stroke curve, it is thought that it will be possible to reduce the amount of deformation of the side sill (S2 in Figure 2) while ensuring the necessary amount of collision energy absorption.

[0033] Next, the inventors studied a specific configuration of a side sill structure that can realize the ideal load-stroke curve shown in FIG. The rigidity and buckling load of the side sill structure can be adjusted by appropriately selecting the thickness and material of the corrugated members arranged within the side sill. However, it was not possible to suppress the increase in load during the collision process after buckling deformation and keep it constant by simply selecting the thickness and material.

[0034] The inventor therefore conducted extensive research to solve this problem. In the research, the inventor focused on the cause of the gradual increase in load after the initial buckling deformation in the conventional side sill structure. As a result, the inventor inferred that in the process of an impact body penetrating into the vehicle interior, in the conventional side sill structure, the initial buckling deformation occurs at the vehicle exterior end of the corrugated member disposed in the side sill, and then accordion-like buckling deformation occurs one after another while waving from the vehicle exterior to the vehicle interior, resulting in an increase in load.

[0035] Therefore, in order to realize the ideal load-stroke curve shown in Fig. 2, we came up with the idea of ​​suppressing the buckling deformation that occurs continuously in a bellows-like wavy shape with multiple antinodes after the initial buckling deformation occurs in the corrugated material arranged inside the side sill.

[0036] They then discovered that by joining the corrugated members inside the side sill in an asymmetrical manner above and below while being shifted in the longitudinal direction of the vehicle, it is possible to suppress the buckling deformation that occurs continuously in an accordion-like manner, undulating with multiple antinodes, after the initial buckling deformation occurs in the corrugated member, and to maintain the buckling deformation at a constant load.

[0037] In this way, compared to conventional side sill structures, it was discovered that by appropriately selecting the plate thickness and material, the rigidity can be increased, thereby increasing the maximum load, and by keeping the load after buckling constant, it is possible to reduce the amount of deformation while ensuring the necessary amount of collision energy, thereby realizing a compact side sill structure. The present invention has been made based on the above findings, and the configuration thereof will be described below.

[0038] <Automobile side sill structure> A side sill structure 1 according to an embodiment of the present invention is provided with a side sill 10 having a side sill inner 11 and a side sill outer 13, as shown as an example in FIG. 1, and has a shock absorbing structure 20 and a recess 30. Below, we will explain each component of the side sill structure 1. In this application, terms related to directions such as "vehicle longitudinal direction," "vehicle width direction," and "vehicle up-down direction," and terms related to positions such as "vehicle exterior side," "vehicle interior side," "vehicle upper side," and "vehicle lower side," indicate directions and positions in a state in which the side sill structure 1 is actually installed on a vehicle.

[0039] <Side sill> As shown in FIG. 1, the side sill 10 is formed by joining a side sill inner 11 and a side sill outer 13 together.

[0040] The side sill inner 11 has a vertical surface portion 11a that is substantially parallel to the vehicle up-down direction, and a pair of horizontal surface portions 11b that continue from the upper and lower ends of the vertical surface portion 11a toward the outer side of the vehicle. In the side sill inner 11, a groove shape is formed by a vertical surface portion 11a and a pair of horizontal surfaces 11b, and the vertical surface portion 11a corresponds to the bottom of the groove shape. Furthermore, the side sill inner 11 has flange portions 11c extending upward and downward from the respective ends of the lateral surface portions 11b on the upper and lower sides of the vehicle.

[0041] The side sill outer 13 has a vertical surface portion 13a that is substantially parallel to the vehicle up-down direction, and a pair of horizontal surface portions 13b that continue from the upper and lower ends of the vertical surface portion 13a toward the vehicle interior side. In the side sill outer 13, a groove shape is formed by the vertical surface portion 13a and a pair of horizontal surface portions 13b, and the vertical surface portion 13a corresponds to the bottom of the groove shape. Furthermore, the side sill outer 13 has flange portions 13c extending upward and downward from the respective ends of the lateral surface portions 13b on the upper and lower sides of the vehicle.

[0042] The flange portion 11c and the flange portion 13c of the side sill inner 11 and the side sill outer 13 are joined (for example, by spot welding) to each other with the opening sides of the groove shapes of the side sill inner 11 and the side sill outer 13 facing each other, thereby forming the side sill 10 having a closed cross-sectional space 10a therein.

[0043] In addition, the vertical surface portion 11a of the side sill inner 11 and the vertical surface portion 13a of the side sill outer 13 do not have to have a planar shape parallel to the vertical direction of the vehicle, but may be inclined with respect to the vertical direction of the vehicle or may have a curved shape. Similarly, the lateral surface portion 11b of the side sill inner 11 and the lateral surface portion 13b of the side sill outer 13 do not have to have a planar shape parallel to the horizontal plane, but may be inclined with respect to the horizontal plane or have a curved shape.

[0044] <Shock absorbing structure> The shock absorbing structure 20 has an inner end 20a in the vehicle width direction connected to a vertical surface portion 11a, which is the bottom of the groove shape in the side sill inner panel 11, and absorbs the impact input to the side sill 10 in the event of a side collision of the vehicle. As shown in Figures 1 and 3, the shock absorbing structure 20 has a wave shape in which convex and concave shapes are alternately continuous in the longitudinal direction of the vehicle in a cross section perpendicular to the vehicle width direction, and is configured to include a pair of corrugated parts 21, 23 arranged in the vertical direction of the vehicle. The upper corrugated part 21 has a corrugated shape in which convex shapes 21a and concave shapes 21b are alternately continuous in the vehicle longitudinal direction in a cross section perpendicular to the vehicle width direction. Similarly, the lower corrugated part 23 has a corrugated shape in which convex shapes 23a and concave shapes 23b are alternately continuous in the vehicle longitudinal direction in a cross section perpendicular to the vehicle width direction. In addition, in the upper corrugated part 21 and the lower corrugated part 23, the convex shapes 21a, 23a are formed by a top surface and a pair of wall surfaces continuing from both ends thereof, and the concave shapes 21b, 23b are formed by a bottom surface and a pair of wall surfaces continuing from both ends thereof.

[0045] A pair of corrugated parts 21, 23 are made of metal plates. In the shock absorbing structure 20, the upper corrugated part 21 and the lower corrugated part 23 are arranged so that the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part face each other. Furthermore, the bottom surfaces of the concave shapes 21b and 23b facing each other are joined together in a state where the concave shapes 21b and 23b are shifted in the vehicle longitudinal direction. Here, "arranged so that the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part face each other" means that the upper corrugated part 21 and the lower corrugated part 23 are arranged in a state where they are upside down.

[0046] In the shock absorbing structure 20, the state in which the recessed shape 21b and the recessed shape 23b are offset in the vehicle longitudinal direction means that the center positions of the bottom surfaces of the recessed shapes 21b and 23b are offset in the vehicle longitudinal direction by a predetermined offset amount W2, as shown in Fig. 4. The bottom surfaces of the recessed shapes 21b and 23b may be joined by, for example, spot welding. As a result, the shock absorbing structure 20 is disposed in the side sill 10, and has a structure in which the pair of upper and lower corrugated parts 21 and 23 are integrated.

[0047] Furthermore, in this embodiment, the tip of the shock absorbing structure 20 on the vehicle outer side in the vehicle width direction is in contact with the vertical surface portion 13a which is the bottom portion of the groove shape of the side sill outer 13. Here, the tip of the shock absorbing structure 20 on the vehicle outer side refers to the end face of the metal plate used for the corrugated parts 21, 23.

[0048] 5, the shock absorbing structure 20 is preferably disposed within the side sill 10 so as to overlap at least the floor cross member 103 in the vertical direction of the vehicle. This makes it possible to absorb the impact input to the side sill 10 during a side collision, and to transmit the load to the floor cross member 103, thereby efficiently crushing the shock absorbing structure 20 with the reaction force, thereby increasing the amount of collision energy absorption.

[0049] <Concave> The recess 30 is provided on the vertical surface 11a, which is the bottom of the groove shape of the side sill inner panel 11, as a vertical restraining structure that restrains the end 20a on the vehicle interior side of the shock absorbing structure 20 in the vehicle vertical direction. The end 20a on the vehicle interior side of the shock absorbing structure 20 is inserted into the recess 30, and by pressing the end 20a from the vehicle vertical direction during a side collision, the recess 30 resists displacement of the end 20a in the vehicle vertical direction. The end 20a on the vehicle interior side of the shock absorbing structure 20 inserted into the recess 30 is joined to the bottom 31 of the recess 30.

[0050] An example of a method for joining the end portion 20a of the shock absorbing structure 20 on the vehicle interior side to the vertical surface portion 11a of the side sill inner panel 11 will be described with reference to Figs. 1(a) and 3.

[0051] The shock absorbing structure 20 has an end 20a on the vehicle interior side in the vehicle width direction inserted into a recess 30 provided in the vertical surface portion 11a of the side sill inner panel 11. The end 20a is joined (by spot welding or the like) to a bottom portion 31 of the recess 30 via a flange portion 25 provided at the tip of the end 20a. The flange portion 25 may be provided over the entire length of the vehicle in the longitudinal direction, or may be provided intermittently in the longitudinal direction of the vehicle.

[0052] The effects of the side sill structure 1 according to the embodiment of the present invention will be described below with reference to a vehicle side structure 100 shown in FIG.

[0053] ≪Vehicle side structure≫ The floor cross member 103 is a body frame structural member disposed above the floor panel 101 and extending in the vehicle width direction, and each end portion 103a in the vehicle width direction is joined (e.g., by spot welding) to the vertical surface portion 11a, which is the bottom of the groove shape of the side sill inner 11. A plurality of floor cross members 103 are provided at predetermined intervals (for example, about 300 mm) in the vehicle longitudinal direction.

[0054] The battery case 105 is disposed below the floor panel 101, and houses a battery pack 107 inside. Each side surface portion 105a of the battery case 105 in the vehicle width direction faces the side sill inner panel 11 at a predetermined interval. In the vehicle side structure 100, the side surface portion 105a of the battery case 105 faces a lower portion of the vertical surface portion 11a of the side sill inner panel 11.

[0055] A mounting flange 105c is connected to a bottom plate 105b, which is the bottom portion of the battery case 105, so as to protrude toward the side sill 10. The mounting flange 105c and the lower lateral surface portion 11b of the side sill inner panel 11 are fastened with fixing bolts 109, so that the battery case 105 is held to the side sill 10.

[0056] The shock absorbing structure 20 disposed inside the side sill structure 1 is disposed so as to overlap with the floor cross member 103 in the vehicle height direction when viewed from the side in the vehicle width direction.

[0057] <Effects of side sill structure 1> In the side sill structure 1 of this embodiment, the shock absorbing structure 20 arranged within the side sill 10 has the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part 23 offset in the longitudinal direction of the vehicle, with their bottom surfaces joined together in a state where they face each other asymmetrically above and below.

[0058] In the cross-sectional view of the shock absorbing structure 20 perpendicular to the vehicle width direction shown in Fig. 1(b), the ridgelines (corners) of the convex shapes 21a, 23a and the concave shapes 21b, 23b have high deformation resistance against a collision load from the vehicle exterior in the vehicle width direction. The top surface (the area indicated by the dashed ellipse in Fig. 1(b)) sandwiched between the ridgelines of the convex shapes 21a, 23a and having a long distance between the ridgelines has relatively low deformation resistance compared to the wall surfaces (the area indicated by the solid ellipse in Fig. 1(b)) having a short distance between the ridgelines. Furthermore, because the upper corrugated part 21 and the lower corrugated part 23 in the shock absorbing structure 20 are joined relative to each other in the longitudinal direction of the vehicle, as shown in Figure 1 (b), in a cross section perpendicular to the vehicle width direction, areas with relatively high deformation resistance (solid ellipse) and areas with relatively low deformation resistance (dashed ellipse) face each other above and below in the longitudinal direction of the vehicle, and areas where the deformation resistance of the upper corrugated part 21 and the lower corrugated part 23 differs between the top and bottom are intermittently generated in the longitudinal direction of the vehicle.

[0059] Therefore, in the case of a side collision of a vehicle equipped with the side sill structure 1, as shown in FIG. 10(c) described later, due to the difference in deformation resistance between the upper corrugated part 21 and the lower corrugated part 23 at the position in the vehicle longitudinal direction where the collision object strikes the vehicle from the side, a rotational moment is generated around the axis in the vehicle longitudinal direction, and the initial buckling deformation occurs at both ends of the vehicle inner side and the vehicle outer side, bending out of the plane in the rotational direction. Then, since the shock absorbing structure 20 is inclined with respect to the horizontal plane in the vehicle width direction, after the initial buckling deformation, the buckled parts at both ends of the corrugated parts 21 and 23 continue to bend further. In this way, according to the side sill structure 1 of this embodiment, it is possible to suppress the increase in load accompanying the increase in stroke (deformation amount) as shown in FIG. 2 described above, and to keep the load at a level substantially equal to the maximum load.

[0060] The shock absorbing structure 20 is disposed within the side sill 10, and has a structure in which the corrugated part 21 and the corrugated part 23 are integrated together. Therefore, in the shock absorbing structure 20, closed cross-sectional spaces formed by the convex shape 21a of the upper corrugated part 21 and the convex shape 23a of the lower corrugated part 23 are continuously arranged at regular intervals in the vehicle longitudinal direction. Therefore, the entire shock absorbing structure 20 has high bending rigidity (resistance to bending deformation against a side collision load). This suppresses local deformation of the impact absorbing structure 20 around the area of ​​the side sill where the impact load is input, and also causes buckling deformation around the area where the collision load is input, thereby increasing the amount of collision energy absorption.

[0061] Furthermore, in the side sill structure 1, a recess 30 is provided in the vertical surface portion 11a, which is the bottom portion of the groove shape in the side sill inner panel 11, and the vehicle-interior end portion 20a of the shock absorbing structure 20 is inserted into the recess 30 to restrain it in the vertical direction of the vehicle. This prevents the end 20a on the vehicle interior side of the shock absorbing structure 20 from shifting in the vertical direction of the vehicle, causing the shock absorbing structure 20 to tip over, or the end 20a to be significantly deformed in the out-of-plane direction, during a side collision of the vehicle. As a result, it is possible to prevent the shock absorbing structure 20 from tipping over or the end 20a from being significantly deformed in the out-of-plane direction, causing a decrease in the amount of collision energy absorption.

[0062] The shock absorbing structure 20 is disposed so as to overlap with the floor cross member 103 in the vehicle height direction in a side view from the vehicle width direction. As a result, a collision load input from the side sill outer 13 from outside the vehicle is transmitted to rigid parts such as the floor cross member via the shock absorbing structure 20, and a reaction force from the rigid parts is transmitted to the shock absorbing structure 20 via the side sill inner 11. This allows the shock absorbing structure 20 to be efficiently crushed, making it possible to improve the collision energy absorption performance.

[0063] As described above, in the side sill structure 1 of this embodiment, the buckling resistance against the impact load input to the side sill 10 during a side collision is increased, and the shock absorbing structure 20 can be crushed while maintaining a state of high deformation resistance, thereby obtaining high collision energy absorption performance.

[0064] In addition, the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part 23 in the shock absorbing structure 20 are arranged to face each other, and the facing concave shapes 21b and 23b are joined in a state of being shifted in the vehicle longitudinal direction. This distributes the positions of the ridge lines of the convex shapes 21a, 23a and the ridge lines of the concave shapes 21b, 23b in the vehicle longitudinal direction, making it possible to make it difficult for differences (variations) in collision performance to occur depending on the position where the impact load is input.

[0065] Furthermore, when the side sill structure 1 is applied to an electric vehicle, it is possible to reduce the space required to absorb collision energy in the side sill structure 1. This also makes it possible to increase the volume of the battery module disposed between the side sills 10 on both sides in the vehicle width direction.

[0066] Furthermore, in the side sill structure 1 of this embodiment, since the shock absorbing structure 20 has high bending rigidity, there is no need to increase the thickness of the metal plate used in the side sill structure 1 in order to improve rigidity, and the increase in weight of the vehicle body can also be suppressed.

[0067] In addition, the side sill structure 1 in this embodiment has a recess 30 provided in the vertical surface portion 11a of the side sill inner 11 as a vertical restraint structure that restrains the vehicle-interior end portion 20a of the shock absorbing structure 20 in the vertical direction of the vehicle.

[0068] However, in the present invention, the vertical restraint structure is not limited to the recess 30. Fig. 6 shows a modified example of the vertical restraint structure. The side sill structure 1 shown in Fig. 6 has L-shaped brackets 35 provided on both the upper and lower sides of the end 20a on the vehicle interior side of the shock absorbing structure 20 as a top and bottom restraint structure. The upper L-shaped bracket 35 is joined to the top surface of the upper corrugated part 21 and the vertical surface portion 11a of the side sill inner panel 11, and the lower L-shaped bracket 35 is joined to the lower surface of the lower corrugated part 23 and the vertical surface portion 11a of the side sill inner panel 11. The L-shaped bracket 35 may be joined to the corrugated parts 21, 23, and the vertical surface portion 11a by spot welding or the like.

[0069] In this way, even during a side collision of the side sill structure 1 provided with the L-shaped bracket 35 as a vertical restraint structure, the end 20a on the vehicle interior side of the impact absorbing structure 20 can be restrained in the vehicle vertical direction.

[0070] In addition, the L-shaped bracket 35 is not limited to being provided over the entire length of the vehicle in the longitudinal direction, as long as it is capable of restraining the end portion 20a on the vehicle interior side in the vertical direction of the vehicle during a side collision, but may be provided intermittently in the longitudinal direction of the vehicle.

[0071] 1 or 6, the present invention is not limited to the structure in which the end 20a on the vehicle interior side of the shock absorbing structure 20 is joined to the vertical surface portion 11a of the side sill inner panel 11. In other words, the present invention does not require a flange portion to be provided at the end portion on the vehicle interior side of the shock absorbing structure, and the tip on the vehicle interior side may be an end face of a metal plate constituting a corrugated part, and may abut against the vertical surface portion of the side sill inner panel.

[0072] However, as shown in FIG. 1, the end portion 20a of the shock absorbing structure 20 on the vehicle interior side is connected to the vertical surface portion 11a of the side sill inner panel 11, which is preferable since it provides good collision energy absorption performance in the event of a side collision.

[0073] In the present invention, the end 20 b on the vehicle exterior side of the shock absorbing structure 20 may be connected to the vertical surface portion 13 a of the side sill outer panel 13 . As an example of a manner in which the outer-vehicle end 20b of the shock absorbing structure 20 is connected to the vertical surface portion 13a of the side sill outer 13, a flange portion bent from the tip of the outer-vehicle end and joined (by spot welding, etc.) to the vertical surface portion of the side sill outer may be provided.

[0074] However, if the end of the shock absorbing structure on the vehicle exterior side is provided with a flange portion that is connected to the side sill outer via a bent portion that is bent in the vehicle vertical direction with a predetermined curvature radius, the rigidity against the load input during a side collision may be reduced. Therefore, as shown in Fig. 1, it is preferable that the shock absorbing structure 20 does not have a flange on the end on the vehicle exterior side, and the tip of the shock absorbing structure on the vehicle exterior side is abutted against the vertical surface portion 13a of the side sill outer 13. This allows the shock absorbing structure 20 to receive the load input to the side sill 10 without reducing its rigidity, so that the load can be increased quickly at the beginning of the collision, and the amount of collision energy absorption can be increased.

[0075] In addition, the shock absorbing structure 20 may be one in which both the upper corrugated part 21 and the lower corrugated part 23, or either the upper or lower corrugated part 21 or 23, abut against the vertical surface portion 11a of the side sill inner 11 and / or the vertical surface portion 13a of the side sill outer 13.

[0076] The present invention does not exclude a case where a gap is provided between the outer end 20b of the shock absorbing structure 20 and the side sill outer 13, or a case where a gap is provided between the inner end 20a and the side sill inner 11. In other words, it is sufficient that the inner end 20a of the shock absorbing structure 20 is connected to the vertical surface 11a of the side sill inner 11, or the outer end 20b is connected to the vertical surface 13a of the side sill outer 13, so that the shock absorbing structure 20 is supported within the side sill 10.

[0077] In the side sill structure 1 according to the present embodiment, as described above, the upper corrugated part 21 and the lower corrugated part 23 are joined at their bottom surfaces in a state in which the opposing concave shapes 21b and 23b are shifted in the vehicle longitudinal direction. The shift amount of the concave shapes 21b and 23b in the vehicle longitudinal direction may be determined so that the bottom surfaces can be joined together.

[0078] FIG. 4 shows the amount of shift between the concave shape 21b of the upper corrugated part and the concave shape 23b of the lower corrugated part . In the corrugated part 21, the center-to-center distance between adjacent convex shapes 21a and concave shapes 21b in the vehicle longitudinal direction (the distance between the dashed lines passing through ● in FIG. 4) is defined as W1. When the shift amount (center-to-center distance between the concave shapes) between the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part 23 is defined as W2, it is preferable that the shift amount W2 is 20% or more and 50% or less of W1 (0.2×W1≦W2≦0.5×W1).

[0079] If the shift amount W2 is less than 20% of W1 (W2<0.2×W1), buckling deformation occurs almost simultaneously at the ridge lines of the upper corrugated part 21 and the lower corrugated part 23, resulting in an axial crushing mode in which accordion-like buckling deformation occurs in the corrugated parts 21 and 23, and the effect of suppressing the increase in load during the collision process after buckling deformation is small. Furthermore, if the shift amount W2 is more than 50% of W1 (W1>0.5×W1), the area where the bottom surfaces of the recessed shape 21b and the recessed shape 23b overlap is narrow, making joining by spot welding or the like difficult.

[0080] The recess 30 has a function of suppressing displacement of the end 20a on the vehicle interior side in the vertical direction of the vehicle during the deformation process of the impact absorption structure 20 at the time of a side collision. Therefore, the recess amount D of the recess 30 toward the vehicle interior side may be set so as to achieve this function. Therefore, the recess amount D of the recess 30 is preferably 0.8 to 1.2 times the vehicle vertical height h of the shock absorbing structure 20. Here, the vehicle vertical height h of the shock absorbing structure 20 is the height of the pair of corrugated parts 21, 23 arranged side by side in the vehicle vertical direction.

[0081] If the amount of depression D of the recess 30 is less than 0.8 times the height h of the impact absorbing structure 20, the cross section of the side sill 10 will open up and down and collapse during a side collision, and the recess 30 will also deform and open up and down, causing the inside end 20a of the impact absorbing structure 20 to come off the recess 30. Furthermore, if the recess amount D of the recess 30 exceeds 1.2 times the height h, the recess 30 may interfere with the floor cross member, battery pack, etc., which are located inside the vehicle body relative to the side sill inner panel 11, which may require significant changes to the structure of the floor cross member or battery pack.

[0082] In addition, when a flange portion 25 is provided at the end portion 20a on the vehicle interior side of the shock absorbing structure 20 and the flange portion 25 is spot welded to the bottom 31 of the recess 30, the height of the recess 30 in the vertical direction of the vehicle should be sufficient to ensure working space for welding the flange portion 25. In view of the above, it is preferable that the height H of the recess 30 in the vehicle vertical direction is 1.3 to 1.4 times the height h of the shock absorbing structure 20 (see FIG. 1(a)).

[0083] The metal plate used in the shock absorbing structure 20 preferably has a tensile strength of 590 MPa or more. In terms of the collision characteristics of the shock absorbing structure 20, the higher the load (buckling strength) when the shock absorbing structure 20 changes from elastic deformation immediately after the start of deformation to plastic deformation during a side collision, the less likely buckling deformation occurs and the better the collision characteristics. The higher the tensile strength (yield strength) of the metal plate used in the shock absorbing structure 20, the higher the buckling strength, so it is preferable to use a metal plate of 590 MNPa or more, which has a tensile strength higher than that of ordinary steel.

[0084] Furthermore, when a high tensile steel plate is used for the shock absorbing structure 20, the shock absorbing structure 20 disposed within the side sill 10 also functions as a reinforcement for the side sill 10. Therefore, it is particularly preferable that the metal plate used for the shock absorbing structure 20 be a high tensile steel plate of 980 MPa class or higher.

[0085] Furthermore, it is preferable that the metal plates used for the corrugated parts 21, 23 of the shock absorbing structure 20 have a yield strength equal to or lower than the yield strength of the metal plate used for the floor cross member 103 (FIG. 5). This is to ensure that, during a side collision, the shock absorbing structure 20 buckles and deforms before the floor cross member 103 does, sufficiently absorbing the collision energy and suppressing the deformation of the floor cross member 103.

[0086] When the yield strength of the metal plates constituting the shock absorbing structure 20 is approximately the same as the yield strength of the metal plates constituting the floor cross member 103, it is preferable to make the buckling strength of the shock absorbing structure 20 (= the load at which the component itself begins to buckle) lower than the buckling strength of the floor cross member 103 by adding beads (crash beats) or the like to the corrugated parts constituting the shock absorbing structure 20, thereby enabling buckling deformation to occur starting from the beads.

[0087] In the side sill structure 1 shown in Fig. 1, the shock absorbing structure 20 is supported within the side sill 10 by having the end portion 20a on the vehicle interior side joined (welded or bonded) to the bottom portion 31 of the recessed portion 30 in the vertical surface portion 11a of the side sill inner panel 11. However, the shock absorbing structure 20 may also be supported within the side sill 10 via a supporting structure 37 as shown in Fig. 7.

[0088] 7(a), the upper end of the support structure 37 is joined to the lower surface of the shock absorbing structure 20, and the lower end is joined to the flange portions 11c, 13c of the side sill . 7(b), one end of the support structure 37 is joined to the lower surface of the shock absorbing structure 20, and the other end is joined to the vertical surface portion 13a of the side sill outer 13. In FIG. FIG. 7( c ) shows the shock absorbing structure 20 supported by supporting structures 37 arranged both above and below the shock absorbing structure 20 . The manner in which the shock absorbing structure 20 is supported by the supporting structure 37 is not limited to those shown in Figures 7(a) to (c). For example, the shock absorbing structure 20 may be supported only by the supporting structure 37 arranged above the shock absorbing structure 20 in the side sill structure 1 shown in Figure 7(c).

[0089] The support structure 37 may be joined to the shock absorbing structure 20 and the side sill 10 by at least one of welding such as spot welding, mechanical fastening with bolts or rivets, or adhesion.

[0090] The corrugated parts 21, 23 of the side sill structure 1 according to the present embodiment described above have the same corrugated shape in a cross section perpendicular to the vehicle width direction, except that they are arranged upside down. It is preferable that the convex shapes 21a, 23a and the concave shapes 21b, 23b in each corrugated part 21, 23 have a height or depth of 15 mm to 100 mm, the width of the top surface of the convex shape 21a and the bottom surface of the concave shape 21b is 15 mm to 150 mm, and the inclination angle of the wall surface of each of the convex shapes 21a and the concave shapes 21b (the acute angle formed between the wall portion and a vertical line horizontal to the vertical direction of the vehicle) is 1° to 30°. This allows the bottom surfaces of the concave shapes to be joined in a shifted state, and the ridges of the convex and concave shapes to be crushed during a side collision, thereby improving collision performance.

[0091] In addition, the convex and concave shapes of the corrugated parts are not limited to being the same in a cross section perpendicular to the vehicle width direction, but may be different. For example, in order to make it easier to join the bottom surfaces of the opposing concave shapes in a pair of corrugated parts, the width of the bottom surface of the concave shape may be wider than the width of the upper surface of the convex shape. EXAMPLES

[0092] An analysis was carried out to verify the effect of the automobile side sill structure according to the present invention, and this will be described below.

[0093] In Example 1, for the purpose of evaluating the collision characteristics of the side sill structure during a side collision of a vehicle, a collision analysis was performed in a collision test in which an impact body 210 was collided with the side of a side sill 10 in a test body 200 equipped with a side sill structure 1, as shown in FIG. 8.

[0094] The test specimen 200 simulates the vehicle side structure 100 described above, and on the opposite side of the impact body 210 in the side sill 10, it has a floor cross member simulation portion 201 corresponding to the floor cross member 103, a battery case wall portion 203 corresponding to the side portion 105a of the battery case 105, and a battery case bottom plate portion (not shown) corresponding to the bottom plate 105b of the battery case 105. In the test specimen 200, the bottom plate of the battery case is fixed to the side sill inner panel 11 by fixing bolts. The length of the floor cross member simulation portion 201 in the longitudinal direction of the vehicle is 160 mm.

[0095] In the collision analysis, a collision body 210 was collided with the test body 200 in the vehicle width direction as shown in Fig. 8. Here, the collision body 210 was a rigid pole with a radius R of 127 mm (equivalent to a diameter of 254 mm), an initial speed of 35.0 km / h, and a maximum penetration of 80 mm. The load capacity (allowable load) of the floor cross member simulation part 201 was set to 500 kN or less, and the target value for the amount of collision energy absorption by the side sill structure was set to 27 kJ (equivalent to 90% of the collision energy by the collision body 210).

[0096] In the collision analysis, as shown in Fig. 8, the deformation behavior of the side sill 10 was obtained during the collision process in which a collision object 210 that collided with the side surface of the side sill 10 penetrates into the side sill 10. From the deformation behavior of the side sill 10, the relationship between the load and stroke input to the side sill 10, and the amount of collision energy absorption from the start of the collision to the maximum penetration amount were obtained. Note that the load input to the test body 200 was the load transmitted to the rigid jig used to fix the test body 200.

[0097] FIG. 9 shows the side sill structure that was tested in the examples. In FIG. 9, (a) and (b) show a side sill structure 1 according to the present invention (Invention Examples 1 and 2), and (c) to (g) show a side sill structure 3 used for comparison (Comparative Examples 1 to 3). In addition, in each of Figures 9(a) to (g), the left-hand diagram is a cross-sectional view of the side sill 10 perpendicular to the vehicle longitudinal direction, and the right-hand diagram is a cross-sectional view of the shock absorbing structure 20 within the side sill 10 perpendicular to the vehicle width direction.

[0098] The side sill structure 1 of Example 1 of the invention shown in Figure 9(a) is an impact absorbing structure 20 within a side sill 10, in which the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part are arranged opposite each other, and the bottom surfaces are joined together while being shifted in the longitudinal direction of the vehicle. In the side sill structure 1, the offset amount between the concave shapes 21b and 23b is W2 = 0.5 x W1 (the center-to-center distance between the concave shapes 21b and 23b), and the recess amount D of the recess 30 provided in the side sill inner 11 is 35 mm (1.0 times the height h of the shock absorbing structure 20).

[0099] A side sill structure 1 according to Example 2 of the invention shown in FIG. 9(b) is obtained by changing the shift amount between the concave shape 21b and the concave shape 23b in Example 1 of the invention to W2=0.2×W1.

[0100] The side sill structure 3 of comparative example 1 shown in Figure 9 (c) is provided with a side sill 40 having a side sill inner 41 with a flattened vertical surface portion 41a obtained by removing the recess 30 of the side sill inner 11 in invention example 1. In addition, the shock absorbing structure 20 has a shift amount W2 between the concave shape 21b and the concave shape 23b of W2 = 0.5 × W1, similar to the invention example 1. Note that, in the shock absorbing structure 20, the vertical surface portion 41a of the side sill inner panel 41 is flattened, so that the length in the vehicle width direction is shorter than that of the invention example 1.

[0101] The side sill structure 3 of comparative example 2 shown in Figure 9 (d) is, like comparative example 1, a side sill inner 41 having a flattened vertical surface portion 41a obtained by removing the recess 30 of the side sill inner 11 in invention example 2. In addition, the shift amount W2 between the concave shape 21b and the concave shape 23b in the shock absorbing structure 20 is W2 = 0.0 × W1, that is, the bottom surfaces of the concave shape 21b and the concave shape 23b are joined together without being shifted in the vehicle longitudinal direction. Note that, since the vertical surface portion 41a of the side sill inner 41 of the shock absorbing structure 20 is flattened, the vehicle width direction length is shorter than that of the second invention example.

[0102] In the side sill structure 3 according to Comparative Example 3 shown in Fig. 9(e) and Comparative Example 4 shown in Fig. 9(f), a shock absorbing structure 50 obtained by removing the lower corrugated part 23 from the shock absorbing structure 20 in Comparative Example 2 is disposed within the side sill 40. Comparative Example 3 and Comparative Example 4 differ in the plate thickness of the metal plate used as the material for the shock absorbing structure 50, with Comparative Example 3 having a plate thickness of 2.2 mm, the same as Invention Examples 1 and 2 and Comparative Examples 1 and 2, and Comparative Example 4 having a plate thickness of 3.2 mm, which is thicker than Comparative Example 3.

[0103] The side sill structure 3 according to the comparative example 5 shown in FIG. 9(g) does not include a shock absorbing structure within the side sill 40, and only the side sill 40 is provided.

[0104] Table 1 summarizes the tensile strength and plate thickness of the metal plate used in the side sill 10 in Examples 1 and 2 and Comparative Examples 1 to 5, the material (tensile strength), plate thickness, and number of corrugated parts that make up the shock absorbing structures 20 and 50, the coefficient α that determines the shift amount W2 of the concave shape, and the concave amount D of the recess 30 provided in the vertical surface portion 11a of the side sill inner 11.

[0105] [Table 1]

[0106] FIG. 10 shows modified forms of the impact absorbing structure 20 in a crash test of a test body 200 having the side sill structure 1 according to the first example of the invention. Figure 10(a) is a perspective view of the shock absorbing structure 20 in the side sill 10 seen from above, Figure 10(b) is an oblique view of the shock absorbing structure 20, and Figure 10(c) shows a cross-sectional view in the vertical direction of the vehicle passing through the center line of the impact body 210.

[0107] In a collision test in which a collision body 210 is collided with a side surface of a test body 200, the collision body 210 collides with the shock absorbing structure 20 at a position where the center line of the collision body 210 and the shock absorbing structure 20 intersect as shown in FIG. 10(a). As shown in FIG. 10(a), the center line of the collision body 210 intersects with the top surface of the convex shape 23a of the lower corrugated part 23, and intersects with the bottom surface of the concave shape 21b between the joint with the lower corrugated part 23 (marked with ● in FIG. 10(a)) and the ridge line of the convex shape 21a of the upper corrugated part 21. Here, the bottom surface of the concave shape 23b in the lower corrugated part 23 has a low deformation resistance, whereas the bottom surface of the concave shape 21b in the upper corrugated part 21 has a relatively high deformation resistance. Therefore, in the shock absorbing structure 20, the out-of-plane deformation of the convex shape 23a of the lower corrugated part 23 is large.

[0108] 10(c), in the shock absorbing structure 20, a rotational moment is generated that rotates the outer end 20b downward and the inner end 20a upward about the axis in the vehicle longitudinal direction due to the difference in deformation resistance between the upper corrugated part 21 and the lower corrugated part 23. Then, in each of the corrugated parts 21, 23 around the collision position of the collision body 210, buckling deformation occurs such that both end portions on the inner and outer sides are bent out of the plane in the rotational direction, and the shock absorbing structure 20 is inclined with respect to the horizontal plane along the vehicle width direction.

[0109] Therefore, in the shock absorbing structure 20, after the initial buckling deformation, bellows-like buckling deformation does not occur, and the buckled portions at both ends of the corrugated parts 21, 23 continue to bend. As a result, the side sill structure 1 according to the first example of the invention can suppress the load fluctuation after the shock absorbing structure 20 buckles during the collision process, and can achieve the ideal load-stroke curve shown in FIG.

[0110] Fig. 11 shows the deformation behavior of the impact absorbing structure 20 in a crash test of a test body 200 having the side sill structure 1 according to Example 1. Fig. 11 is a contour diagram showing the equivalent plastic strain distribution of the impact absorbing structure from the start of collision of the colliding body, where t is the elapsed time (s) from the start of the collision.

[0111] Immediately after the start of a collision, the shock absorbing structure 20 deforms at the end 20b on the vehicle exterior side, which is the side (collision end side) where the collision body 210 collides, and at the R portion (bent portion) of the flange joined to the side sill outer panel 13 (t~0.002 sec).

[0112] As the deformation progresses, the tip on the collision end side deforms along the shape of the collision body 210, but at the end 20a on the side of the side sill inner panel 11 opposite the collision end, the strain expands in the longitudinal direction of the vehicle, and deformation occurs over an area larger than the diameter of the collision body (t~0.006 sec).

[0113] Thereafter, the lateral surface portion 11b of the side sill inner panel 11 and the convex ridge of the shock absorbing structure 20 buckle, and strain is concentrated at the buckled points, while new buckled points propagate in the vehicle longitudinal direction.

[0114] Table 1 shown above shows a comparison of the collision energy absorption amounts at the maximum penetration of the collision body 210 in the invention examples 1 and 2 and the comparative examples 1 to 5. The maximum penetration amount of the impactor 210 was 79.9 mm in Example 1, and 80 mm in Example 2 and Comparative Examples 1 to 5.

[0115] The maximum loads (maximum contact reaction force) in Examples 1 and 2 were 465kN and 469kN, respectively, both of which were less than the allowable load of 500kN for the floor cross member, which is a load-bearing part. Furthermore, the collision energy absorption amounts were 30.0kN and 27.9kN, respectively, which exceeded the target collision energy absorption amount (=27.0kN).

[0116] In contrast, in Comparative Example 1 in which the recess 30 was removed from the side sill structure 1 of Invention Example 1, the end 20a on the vehicle interior side of the impact absorbing structure 20 was significantly displaced toward the upper side of the vehicle during the collapse of the side sill structure 3, and the collapse of the impact absorbing structure 20 did not progress sufficiently. As a result, the maximum load was 403 kN, which was lower than the maximum load (= 465 kN) of Invention Example 1. Furthermore, the amount of collision absorbed energy at the maximum stroke amount of 80 mm was 403 kN, which was 13% lower than the amount of collision absorbed energy (= 465 kJ) of Invention Example 1.

[0117] In Comparative Example 2, in which the bottom surfaces of the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part 23 are joined together without shifting them in the vehicle longitudinal direction, the ridges of the upper and lower corrugated parts 21, 23 are concentrated in the vehicle longitudinal direction. Therefore, in Comparative Example 2, the maximum load was increased to 514 kN compared to Comparative Example 1, exceeding the load capacity (= 500 kN) of the floor cross member. Furthermore, since the maximum load was higher than in Comparative Example 1, the collision energy absorption amount was 25.8 kJ, which was an increase compared to Comparative Example 1, but the target collision energy amount (27.0 kJ) could not be achieved.

[0118] In Comparative Example 3, in which a shock absorbing structure 50 was provided in which the lower corrugated part was removed from the shock absorbing structure 20 in Comparative Example 2, the maximum load was 348 kN, which was significantly lower than those of Invention Examples 1 and 2. Furthermore, in accordance with the decrease in maximum load, the collision energy absorption amount also decreased to 17.4 kJ, which was significantly below the target collision energy absorption amount.

[0119] In Comparative Example 4, the plate thickness of the shock absorbing structure 50 of Comparative Example 3 was increased (from 2.2 to 3.2 mm), and the collision energy absorption amount was 29.3 kJ, achieving the target collision energy absorption amount. However, the maximum load was 526 kN, which significantly exceeded the load capacity of the floor cross member of 500 kN.

[0120] The results of Comparative Example 5 show the collision characteristics of the side sill 40 itself, with the collision energy absorption amount remaining at 1.3 kJ.

[0121] FIG. 12 shows the relationship between the amount of collision energy absorbed by the side sill structure and the maximum load input to the side sill structure during a side collision in the collision test in Example 1. As shown in FIG. 12, in Examples 1 and 2, a higher collision energy absorption amount was achieved than in Comparative Examples 1 to 5, and further, the maximum load during a side collision could be suppressed below the allowable load of the load-bearing parts. EXAMPLES

[0122] In Example 2, the effect on the amount of collision energy absorption during a side collision was examined by changing the amount of shift between the concave shape of the upper corrugated part and the concave shape of the lower corrugated part in an impact absorbing structure arranged within a side sill.

[0123] In Example 2, similarly to Example 1 described above, a collision analysis was performed on a collision test in which a collision body 210 was collided with a side surface of a side sill 10 in a test body 200 having a side sill structure 1 shown in FIG. 8. As in Example 1 described above, in the collision analysis, as shown in FIG. 8, the collision body 210 was collided with the test body 200 in a direction perpendicular to the vehicle longitudinal direction at an initial speed of 35.0 km / h and a maximum penetration of 80 mm. Here, the collision body 210 was assumed to be a rigid pole with a radius R of 127 mm (equivalent to a diameter of 254 mm). In addition, the load capacity of the floor cross member simulation part 201 was set to 500 kN or less, and the target value of the amount of collision energy absorption by the side sill structure 1 was set to 27 kJ (equivalent to 90% of the collision energy by the collision body 210).

[0124] In Example 2, a test specimen 200 in which the shock absorbing structure 20 shown in Fig. 13(a) was disposed within the side sill 10 was used as Example 3 of the invention. In the shock absorbing structure 20 according to Example 3 of the invention, the shift amount W2 between the concave shape 21b of the upper corrugated part 21 and the concave shape 23b of the lower corrugated part 23 was set to 50% (50% shift) of the center-to-center distance W1 between the adjacent convex shape 21a and concave shape 21b.

[0125] In addition, in Example 2, as comparison objects, a test specimen 200 in which the shock absorbing structure 20 shown in Figure 13(b) is arranged in the side sill 10 is used as Comparative Example 6, and a test specimen in which the shock absorbing structure 50 shown in Figure 13(c) is arranged within the side sill is used as Comparative Example 7.

[0126] The shock absorbing structures 20 of Comparative Examples 6 and 7 have their bottom surfaces joined together without shifting the center-to-center positions of the concave shapes 21b of the upper corrugated part 21 and the concave shapes 23b of the lower corrugated part 23 in the longitudinal direction of the vehicle (0% shift). In addition, the shock absorbing structure 50 of Comparative Example 8 is configured by removing the lower corrugated part 23 from the shock absorbing structure 20 of Comparative Example 2 and only comprising the upper corrugated part 21 (one corrugated part).

[0127] In Example 3, Comparative Example 7, and Comparative Example 8, metal plates having the thickness and tensile strength shown in Table 1 were used so that the maximum load during a side collision would be equal to or less than the allowable load of 500 kN. Comparative Example 6 is an example in which the shift amount W2 of Example 3 is changed from 50% to 0%, and was produced using metal plates having the same thickness and tensile strength as Example 3.

[0128] FIG. 14 shows a cross-sectional view of the side sill structure 1 illustrating the deformation process of the shock absorbing structure 20 disposed within the side sill 10. In FIG. Fig. 14(a) is a cross-sectional view of the side sill structure according to Example 3, and Fig. 14(b) is a cross-sectional view of the side sill structure 1 according to Comparative Example 6. In Example 3, the concave shape of the upper corrugated part and the concave shape of the lower corrugated part in the shock absorbing structure face each other and are joined in a vertically asymmetrical manner while being shifted in the longitudinal direction of the vehicle, so that a rotational moment is generated that rotates around an axis in the longitudinal direction of the vehicle, and buckling deformation occurs such that the end portions on the inside and outside of the vehicle are bent out of the plane in the rotational direction.

[0129] On the other hand, in Comparative Example 6, after the initial buckling deformation occurs at the end on the vehicle exterior side, buckling deformation occurs successively in a bellows-like manner, undulating with multiple antinodes, from the vehicle exterior side to the vehicle interior side.

[0130] FIG. 15 shows load-stroke curves obtained by crash analysis for side crash tests of the test bodies 200 according to the invention example 3 and the comparative example 6. In Example 3, the load fluctuation after the initial buckling deformation was suppressed and a constant load below the withstand load (allowable load = 500 kN) was maintained. In contrast, in Comparative Example 6, the load continued to increase after the initial buckling deformation and reached the maximum load (= 624 kN > 500 kN) that exceeded the withstand load.

[0131] FIG. 16 shows (a) the load-stroke curve and (b) the transition of the amount of collision energy absorption obtained by collision analysis for the side collision tests of the test bodies 200 according to the invention example 3 and the comparative examples 7 and 8. Table 2 shows the collision energy absorption amount, maximum load, and maximum penetration amount of the colliding body at a stroke amount of 80 mm, which were obtained by collision analysis for each of Example 3, Comparative Example 7, and Comparative Example 8.

[0132] [Table 2]

[0133] In Example 3, as shown in Fig. 16(a), the load rise (rigidity) is fast at the beginning of the collision, and the load fluctuation after buckling is suppressed to maintain a constant load. As shown in Fig. 16(b), the target amount of collision absorbed energy of 30 kJ is reached at a stroke of 80 mm.

[0134] In contrast, in Comparative Example 7, as shown in Fig. 16(a), the load rise (rigidity) was slow in the early stage of the collision, and the load continued to increase even after buckling occurred. The maximum load at a stroke of 80 mm or less was 475 kN, which was lower than that of Example 6. 16(b), the collision energy absorption amount during the collision process remained at a lower value than in Example 3, and the collision energy amount at a stroke amount of 80 mm was 26.7 kJ. The maximum penetration amount of the impact body required to achieve the target collision energy absorption amount of 30 kJ was 87.3 mm, which was larger than that of Example 3.

[0135] In Comparative Example 8, as shown in Fig. 16(a), the load rise (rigidity) at the beginning of the collision was slower than in Comparative Example 7, and the load continued to increase even after buckling occurred. And, although the maximum load at a stroke amount of 80 mm or less was 479 kN, which was similar to that of Comparative Example 7, the collision energy absorption amount during the collision process remained at a lower value than in Comparative Example 6, and the collision energy amount at a stroke amount of 80 mm was 24.2 kJ. And, the maximum penetration amount of the impact body required to achieve the target collision energy absorption amount of 30 kJ was 93.2 mm, which was larger than that of Comparative Example 7. [Explanation of symbols]

[0136] 1. Side sill structure (example of invention) 3 Side sill structure (comparison example) 10 Side sill 11 Side sill inner 11a Vertical side 11b Lateral side 11c Flange part 13 Side sill outer 13a Vertical side 13b Lateral side 13c Flange 20. Shock Absorption Structure 20a Inner end of the vehicle 20b Outside end of the vehicle 21 Upper corrugated part 21a Convex shape 21b Concave shape 23 Lower corrugated part 23a Convex shape 23b concave shape 25 Flange 30 Recess 31 Bottom 33 Wall section 35 L-shaped bracket 37 Supporting structure 40 Side sill 41 Side sill inner 41a Vertical side 50 Shock absorbing structure 100 Vehicle side structure 101 Floor Panel 101a Flange part 103 Floor cross member 103a Vehicle width direction end 105 Battery Case 105a Side part 105b Bottom plate 105c mounting flange 107 Battery Pack 109 Fixing bolt 200 test specimens 201 Floor cross member simulation section 203 Battery case wall 210 Collider

Claims

1. A side sill structure for an automobile, comprising: a side sill inner having a groove shape extending in a vehicle longitudinal direction and opening toward an outer side of the vehicle in a vehicle width direction; and a side sill outer having a groove shape extending in the vehicle longitudinal direction and opening toward an inner side of the vehicle in the vehicle width direction, the side sill inner and the side sill outer being joined together with their opening sides facing each other, an impact absorbing structure that is disposed within the side sill, the impact absorbing structure having an end portion on an inner side of the vehicle in the vehicle width direction connected to a bottom portion of the groove shape of the side sill inner and / or an end portion on an outer side of the vehicle in the vehicle width direction connected to a bottom portion of the groove shape of the side sill outer, and that absorbs an impact input to the side sill in the event of a side collision of the vehicle; a vertical restraint structure that is provided at the bottom of the side sill inner and that restrains the end portion on the vehicle interior side in the vertical direction of the vehicle during a side collision of the vehicle, The shock absorbing structure includes: The vehicle has a wave shape in which convex shapes and concave shapes are alternately continuous in the vehicle longitudinal direction in a cross section perpendicular to the vehicle width direction, and is configured to include a pair of wave-shaped parts arranged in the vehicle up-down direction, A side sill structure for an automobile, characterized in that the pair of corrugated parts are made of metal plates, the concave shape of the upper corrugated part and the concave shape of the lower corrugated part are arranged so as to face each other, and the opposing concave shapes are joined in a state where they are offset in the longitudinal direction of the vehicle.

2. the vertical restraint structure is a recess provided at the bottom of the groove shape of the side sill inner panel and recessed toward the vehicle inner side in the vehicle width direction, 2. The side sill structure of an automobile according to claim 1, wherein the end portion of the shock absorbing structure on the vehicle interior side is inserted into the recess.

3. 2. The automobile side sill structure according to claim 1, wherein a leading end of the shock absorbing structure on an outer side of the vehicle in a vehicle width direction is in contact with the bottom of the groove shape of the side sill outer so as to abut against the bottom.

4. The side sill structure of an automobile as described in claim 1, characterized in that the shift amount W2 of the opposing concave shapes in the upper and lower corrugated parts in the vehicle longitudinal direction is 20% or more and 50% or less of the center-to-center distance W1 of the convex shape and the concave shape adjacent in the vehicle longitudinal direction in the corrugated parts.

5. 3. The automobile side sill structure according to claim 2, characterized in that the recess amount D of the recess provided in the side sill inner is 0.8 to 1.2 times the vehicle vertical height h of the shock absorbing structure.

6. 2. The automobile side sill structure according to claim 1, wherein the corrugated part is made of a metal plate having a tensile strength of 590 MPa or more.

Images