Side sill structure of automobile

Abstract

A side sill structure 1 of an automobile according to the present invention comprises a side sill 10 provided with a reinforcement structure body 20 within a closed cross-sectional space 10a. The reinforcement structure body 20 has: a first load transmission dispersion member 21 which extends in the vehicle front-rear direction on the vehicle outer side within the closed cross-sectional space 10a, and which enhances the proof stress of the side sill 10 while transmitting, to the vehicle rear side, a front collision load inputted to the side sill 10 and dispersing, in the vehicle front-rear direction, a side collision load inputted to the side sill 10; and a collision energy absorption member 23 which is disposed in the vehicle width direction on the vehicle inner side as compared to the first load transmission dispersion member 21 within the closed cross-sectional space 10a, and which, at the time of side collision of the vehicle, transmits the side collision load dispersed by the first load transmission dispersion member 21 to the vehicle inner side and absorbs the collision energy.

Description

Automobile side sill structure

[0001] The present invention relates to a side sill structure for an automobile that improves crashworthiness in both a front crash and a side crash of the vehicle.

[0002] In general, electric vehicles have a battery module mounted below a floor panel. The battery module is composed of battery cells (also called a battery pack) and a battery case for housing the battery cells. The battery case uses high-rigidity and high-proof stress materials to protect the battery cells from impact loads applied during a collision of the electric vehicle. Furthermore, materials are arranged around the battery case to absorb crash energy by deforming due to the impact (load) applied to the vehicle during a collision.

[0003] During a side collision, the side sill deforms to absorb the impact energy from the side of the vehicle. In this application, the impact load on the side of the vehicle during a side collision is referred to as the "side crash load." The remaining impact load is then received by a floor cross member or a battery case side member, thereby protecting the battery cell. Reducing the amount of deformation required for the side sill to absorb impact energy during a side collision can reduce the impact energy absorbing portion of the side sill, enabling a more 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 same amount as the reduced side sill, thereby increasing the battery capacity and driving range. For these reasons, electric vehicles require a space-saving side sill structure that is highly effective at absorbing impact energy during a side collision.

[0004] In addition, in the case of vehicles prior to electric vehicles, a frontal collision load was transmitted from the bumper module at the front of the vehicle to the front side members, and then to the floor side members and side sills behind them. In this application, the load input to the front of the vehicle during a frontal collision is referred to as the "frontal collision load." In contrast, electric vehicles tend to reduce the size or eliminate floor side members because battery modules are mounted under the vehicle body. Therefore, in electric vehicles, the frontal collision load must be transmitted only from the front side members to the side sills, making it necessary to improve the structural strength of the side sills in the frontal collision direction (the longitudinal direction of the side sills).

[0005] Several technologies have been proposed to increase the rigidity of side sills and improve their ability to absorb collision energy during a side collision.

[0006] For example, Patent Document 1 discloses a vehicle body structure in which an energy-absorbing member (wave-shaped section part), which is a wave-shaped plate that extends in the vehicle width direction and repeatedly bends or curves up and down, is arranged and fixed within a side sill.

[0007] Patent Document 2 discloses an automobile structural member that includes a first corrugated reinforcing member inside the automobile structural member, the bottom and top of the first corrugated reinforcing member extending in a direction from the top wall portion toward the bottom wall portion, and the bottom of the first corrugated reinforcing member being joined to the inner surface of one of a pair of vertical wall portions.

[0008] Patent Document 3 discloses an automobile frame member that includes a hat-shaped section part having a plurality of grooves extending in a direction perpendicular to the longitudinal direction, and a closing plate.

[0009] Patent Documents 4 and 5 disclose a vehicle body structure that includes a reinforcing member that constitutes at least a part of a continuous cylindrical structure formed inside a side sill, the continuous cylindrical structure having a shape consisting of multiple polygonal closed cross sections connected together when viewed from the vehicle width direction.

[0010] Patent Document 6 discloses a vehicle side sill including a side sill inner panel, a side sill outer panel arranged spaced apart from the side sill inner panel, a side sill outer reinforcement joined to the side sill outer panel, a partition member arranged between the side sill inner panel and the side sill outer reinforcement, a first reinforcing member arranged between the partition member and the side sill inner panel, and a second reinforcing member arranged between the partition member and the side sill outer reinforcement.

[0011] Japanese Patent Publication No. 2021-146973 Japanese Patent No. 6733848 Japanese Patent No. 7376797 Japanese Patent No. 7181799 Japanese Patent No. 7181165 Japanese Patent Publication No. 2022-548267

[0012] As mentioned above, in electric vehicles where the battery is mounted below the floor panel, the side sills are now required to absorb not only the impact energy in a side collision but also in a frontal collision. In addition, the weight of the side sills needs to be reduced in order to achieve a long driving range.

[0013] According to Patent Documents 1 and 2, the impact load during a side collision can be distributed and transmitted uniformly across a cross section perpendicular to the vehicle width direction, resulting in high collision energy absorption characteristics. However, a side sill reinforcement member with a constant cross section in the vehicle longitudinal direction may be excessively heavy because the reinforcement member is present in areas that do not require reinforcement. Furthermore, during a frontal collision, the bent portion of the corrugated reinforcement member becomes the starting point for axial compressive deformation, resulting in little reinforcing effect.

[0014] According to Patent Document 3, forming multiple grooves in the vertical wall of the side sill makes it possible to increase the energy absorption efficiency during a side collision while suppressing weight increase. However, in the event of a frontal collision, the bent portions of the grooves formed in the vertical wall become the starting points for deformation, so the reinforcing effect is small.

[0015] According to Patent Document 4, the side impact performance can be improved by appropriately arranging the reinforcing member inside the side sill to increase the reaction force of the reinforcing member. However, because the continuous tubular structure expands and contracts in the fore-and-aft direction of the vehicle body during a side impact, it is deformed by the force that pushes it out in the fore-and-aft direction of the vehicle body. As a result, there is a risk that the expected reaction force of the reinforcing member in a side impact may not be secured.

[0016] According to Patent Document 5, by further providing a deformation control component that suppresses deformation of the continuous tubular structure in the fore-and-aft direction of the vehicle body in the vehicle body structure described in Patent Document 4, it is possible to restrict the deformation of the continuous tubular structure in the fore-and-aft direction of the vehicle body during a side collision. Furthermore, it is expected that the reaction force of the reinforcing member can be improved, thereby improving the collision energy absorption performance. However, the deformation control component in the vehicle body structure described in Patent Document 5 has an open end, which reduces the structural strength against a frontal collision, and increasing the structural strength requires an increase in the plate thickness, resulting in an increase in the weight of the component.

[0017] The technology disclosed in Patent Document 6 makes it possible to reinforce the rigidity of side sill inner panels and side sill outer panels by placing reinforcing members inside them. Furthermore, because ridges run longitudinally along the vehicle's length, it is also possible to increase structural strength in frontal collisions. However, in order to join the reinforcing members to the side sills and pillar inner panels, it is necessary to ensure the flanges and flat surfaces of the reinforcing members, which may make it difficult to place the ridges necessary for stiffening. In other words, with conventional methods, it has been difficult to simultaneously achieve the side-impact resistance, front-impact resistance, and weight reduction required for side sill components of electric vehicles.

[0018] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an automobile side sill structure that can achieve high collision energy absorption characteristics with small collision deformation in the event of a side collision, while suppressing weight increase, and can also achieve high deformation resistance (flow stress) in the event of a frontal collision.

[0019] The side sill structure for an automobile according to the present invention comprises a side sill extending in the longitudinal direction of the vehicle and having a reinforced structure provided within a closed sectional space, the reinforcement structure comprising: a first load transfer dispersion component extending in the longitudinal direction of the vehicle toward the outer side of the vehicle within the closed sectional space, increasing the strength of the side sill and transferring a frontal collision load input to the side sill toward the rear side of the vehicle and dispersing a side collision load input to the side sill in the longitudinal direction of the vehicle; and a collision energy absorption component disposed in the closed sectional space on the inner side of the vehicle than the first load transfer dispersion component in the vehicle width direction, with its outer end connected to the first load transfer dispersion component, transferring the side collision load dispersed by the first load transfer dispersion component to the inner side of the vehicle in the event of a side collision of the vehicle, and absorbing collision energy by deforming when the transferred side collision load exceeds a predetermined load.

[0020] The first load transmission distribution member has a closed cross-sectional shape in a cross section perpendicular to the fore-and-aft direction of the vehicle, or forms a closed cross-sectional shape between itself and the inner surface of the side sill on the outer side of the vehicle, and the collision energy absorption member has a closed cross-sectional shape in a cross-section perpendicular to the vehicle width direction, and is preferably provided at two or more locations spaced apart in the fore-and-aft direction of the vehicle in the area in the fore-and-aft direction of the vehicle where the floor cross member is installed.

[0021] The first load transmission distribution member has a closed cross-sectional shape in a cross section perpendicular to the vehicle's fore-and-aft direction, or forms a closed cross-sectional shape between itself and the inner surface of the side sill on the vehicle outer side, and the collision energy absorption member has a cross-sectional shape perpendicular to the vehicle width direction that has two or more rectangular closed sectional shapes in the vehicle's fore-and-aft direction, and one member is provided so as to cover the vehicle's fore-and-aft area where the floor cross member is installed.

[0022] The reinforcing structure further has a second load transfer distribution member that extends in the fore-and-aft direction of the vehicle to the inner side of the vehicle within the closed cross-sectional space, increases the strength of the side sill, and transfers a frontal impact load input to the side sill from the front of the vehicle to the rear side of the vehicle, and distributes the side impact load transferred from the collision energy absorption member in the fore-and-aft direction of the vehicle in the event of a side collision of the vehicle, and the second load transfer distribution member has a closed cross-sectional shape in a cross section perpendicular to the fore-and-aft direction of the vehicle, or forms a closed cross-sectional shape with the inner surface of the side sill on the inner side of the vehicle, and the end of the collision energy absorption member on the inner side of the vehicle is connected to the second load transfer distribution member.

[0023] The closed cross-sectional shape of the first load transfer / distribution member may be one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

[0024] The rectangular closed cross-sectional shape of the first load transfer distribution member may be two rectangular closed cross-sectional shapes that are separated by an intermediate lateral surface portion that crosses the vehicle width direction and are connected in the vehicle up-down direction.

[0025] The closed cross-sectional shapes of the first load transfer / distribution member and the second load transfer / distribution member may be one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

[0026] The rectangular closed cross-sectional shapes of the first load transfer distribution member and the second load transfer distribution member may be two rectangular closed cross-sectional shapes separated by an intermediate lateral surface portion that crosses the vehicle width direction and is connected in the vertical direction of the vehicle.

[0027] The closed cross-sectional shape of the collision energy absorbing member may be one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

[0028] The collision energy absorbing member may have a structure in which two or more adjacent rectangular closed cross-sectional shapes are connected via a connecting member.

[0029] The collision energy absorbing member may have a bead formed on its surface.

[0030] The end of the first load transmission distribution member on the vehicle outer side is preferably connected to the inner surface of the side sill opposite thereto, and the end of the collision energy absorption member on the vehicle inner side is preferably connected to the inner surface of the side sill opposite thereto.

[0031] The first load transfer dispersion member abuts against the inner surface of the side sill on the vehicle outer side or faces the inner surface at a predetermined distance, the collision energy absorption member abuts against the inner surface of the side sill on the vehicle inner side or faces the inner surface at a predetermined distance, and the reinforcing structure is installed within the closed cross-sectional space via a support part.

[0032] The vehicle outer side end of the first load transfer distribution member is preferably connected to the inner surface of the vehicle outer side of the side sill that faces it, and the vehicle inner side end of the second load transfer distribution member is preferably connected to the inner surface of the vehicle inner side of the side sill that faces it.

[0033] The first load transfer distribution member abuts against the inner surface of the side sill on the vehicle outer side or faces the inner surface at a predetermined distance, the second load transfer distribution member abuts against the inner surface of the side sill on the vehicle inner side or faces the inner surface at a predetermined distance, and the reinforcing structure is preferably installed within the closed cross-sectional space via a support part.

[0034] The distance W2 between the collision energy absorbing members adjacent in the vehicle longitudinal direction preferably satisfies the relationship W2≦WF with the distance WF between two floor cross members adjacent in the vehicle longitudinal direction, or W2≦254 mm.

[0035] The first load transfer dispersion member preferably has a width W1 that satisfies the relationship W1 / WS<0.4 with the width WS of the side sill, and a height H1 that satisfies the relationship H1 / HF>0.8 with the height HF of the floor cross member.

[0036] The first load transfer distribution member and the second load transfer distribution member preferably have a width W1 that satisfies the relationship W1 / WS<0.4 with the width WS of the side sill, and a height H1 that satisfies the relationship H1 / HF>0.8 with the height HF of the floor cross member.

[0037] The reinforcing structure is formed using a metal plate having a tensile strength of 590 MPa or more, and the tensile strength of the metal plate forming the collision energy absorption member is preferably lower than the tensile strength of the metal plate forming the first load transmitting and dispersing member.

[0038] According to this invention, a side impact load input to a side sill during a side collision of the vehicle is dispersed in the longitudinal direction of the vehicle by a first load transmission dispersion member provided on the outer side of the vehicle in a closed cross-sectional space inside the side sill, and the dispersed side impact load is transmitted to the inner side of the vehicle by a collision energy absorption member. When the side impact load applied to the collision energy absorption member exceeds a predetermined load, the collision energy absorption member itself deforms to absorb the collision energy. This reduces the deformation of the side sill structure in the vehicle width direction and achieves high collision energy absorption characteristics, thereby improving the side impact resistance required for vehicles equipped with a battery pack, such as electric vehicles.

[0039] Furthermore, according to the present invention, the frontal collision load input to the tip of the side sill during a frontal collision of the vehicle is transmitted to the rear of the vehicle by the side sill and the first load transmission distribution member, thereby increasing the buckling strength of the side sill, thereby protecting occupants from the impact of a frontal collision.

[0040] FIG. 1 is a cross-sectional view of a side sill structure for an automobile according to a first embodiment of the present invention. FIG. 2 is a diagram showing the internal structure of the side sill structure for an automobile according to the first embodiment. FIG. 3 is an exploded view showing the respective components of the side sill structure for an automobile according to the first embodiment. FIG. 4 is a cross-sectional view of a vehicle side structure including the side sill structure for an automobile according to the first embodiment. FIG. 5 is a diagram showing a floor panel, a floor cross member, and a battery pack disposed between side sills provided on the left and right sides in the vehicle width direction. FIG. 6 is a diagram showing a modified form of the side sill structure obtained by collision analysis of a side collision test of a vehicle including the side sill structure for an automobile according to the first embodiment. FIG. 7 is a graph showing the relationship between the intrusion amount of a collision object and the amount of collision energy absorption in a side collision test of a vehicle including the side sill structure for an automobile according to the first embodiment. FIG. 8 is a graph showing the relationship between the intrusion amount of a collision object and the frontal collision load input to the side sill in a frontal collision test of a vehicle including the side sill structure for an automobile according to the first embodiment. FIG. 9 is a diagram showing the rectangular closed cross-sectional shape of a first load transfer / dispersion member in the side sill structure for an automobile according to the first embodiment. FIG. 10 is a diagram showing another aspect of the rectangular closed cross-sectional shape of the first load transmission / distribution member in the side sill structure of an automobile according to the first embodiment. FIG. 11 is a diagram showing a plurality of rectangular closed cross-sectional shapes of the collision energy absorption member in the side sill structure of an automobile according to the first embodiment. FIG. 12 is a diagram showing variations of the reinforcing structure in the side sill structure of an automobile according to the first embodiment. FIG. 13 is a diagram showing variations of the reinforcing structure and the side sill structure of an automobile according to another aspect of the first embodiment of the present invention. FIG. 14 is a diagram showing a best mode of the side sill structure of an automobile according to the present invention. FIG. 15 is a diagram explaining a joining portion in the best side sill structure of the present invention. FIG. 16 is a diagram showing a specific example of a bead provided on the collision energy absorption member in the side sill structure of an automobile according to the first embodiment. FIG. 17 is a diagram showing an aspect of joining the reinforcing structure to the inside of the side sill in the side sill structure of an automobile according to the first embodiment. FIG. 18 is a diagram showing an aspect of supporting the reinforcing structure inside the side sill in the side sill structure of an automobile according to the first embodiment.Fig. 19 is a diagram illustrating preferred dimensions and arrangement of the first load transfer dispersion member and the collision energy absorbing member in the side sill structure of an automobile according to the first embodiment. Fig. 20 is a diagram illustrating the side sill structure of an automobile according to the second embodiment of the present invention. Fig. 21 is a developed view of the collision energy absorbing member in the side sill structure of an automobile according to the second embodiment of the present invention. Fig. 22 is a diagram illustrating the position and preferred dimensions of the collision energy absorbing member in the side sill structure of an automobile according to the second embodiment of the present invention. Fig. 23 is a diagram illustrating an analytical model of a side pole crash test for evaluating the side crash performance of the side sill structure.

[0041] [First Embodiment] A side sill structure 1 for an automobile according to the first embodiment (hereinafter simply referred to as "side sill structure 1") includes a reinforcing structure 20 provided in a closed cross-sectional space 10a inside a side sill 10 extending in the vehicle longitudinal direction, as shown in FIGS. 1 and 2 as an example. The components of the side sill structure 1 will be described in detail below. In this application, terms relating to directions such as "vehicle longitudinal direction," "vehicle width direction," and "vehicle vertical direction," as well as terms relating to positions such as "vehicle outer side," "vehicle inner side," "vehicle upper side," and "vehicle lower side," represent directions and positions when the side sill structure 1 is actually installed on a vehicle. In addition, in the specification and drawings of this application, common members and portions are designated by the same reference numerals.

[0042] <Side Sill> As shown in FIG. 1, the side sill 10 is formed by joining a side sill inner member 11 and a side sill outer member 13, and has a closed cross-sectional space 10a therein.

[0043] The side sill inner panel 11 has a vertical surface portion 11a that is substantially parallel to the vehicle vertical direction and a pair of horizontal surface portions 11b that continue from both ends of the vertical surface portion 11a toward the vehicle outer side (outside of the vehicle). The side sill inner panel 11 also has flange portions 11c that continue from the vehicle outer-side tips of the horizontal surface portions 11b toward the vehicle upper or lower side. Thus, the side sill inner panel 11 has a hat-shaped cross section that opens toward the vehicle outer side, due to the vertical surface portion 11a, the horizontal surface portions 11b, and the flange portions 11c. The vertical surface portion 11a and the pair of horizontal surface portions 11b form a groove shape in the side sill inner panel 11, with the vertical surface portion 11a corresponding to the bottom of the groove shape.

[0044] The side sill outer 13 has a vertical surface 13a that is substantially parallel to the vehicle vertical direction and a pair of horizontal surface 13b that continue from both ends of the vertical surface 13a toward the vehicle inner side (inside of the vehicle). Furthermore, the side sill outer 13 has flange 13c that continues from the vehicle inner-side tip of each horizontal surface 13b toward the vehicle upper or lower side. Thus, the side sill outer 13 has a hat-shaped cross section that opens toward the vehicle inner side, due to the vertical surface 13a, the horizontal surface 13b, and the flange 13c. Furthermore, the side sill outer 13 has a groove shape formed by the vertical surface 13a and the pair of horizontal surface 13b, with the vertical surface 13a corresponding to the bottom of the groove shape.

[0045] The side sill 10 is formed by joining (for example, by spot welding) a flange portion 11c and a flange portion 13c of a hat-shaped side sill inner 11 and a side sill outer 13 with their opening sides facing each other, thereby forming a closed cross-sectional space 10a inside the side sill 10.

[0046] 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 vehicle vertical direction, but may be inclined with respect to the vehicle vertical direction or have a curved shape. Also, the horizontal surface portion 11b of the side sill inner 11 and the horizontal 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.

[0047] <Reinforcement Structure> As shown in FIGS. 1 and 2 , the reinforcement structure 20 is provided in the closed cross-sectional space 10 a of the side sill 10 , and includes a first load transmitting / dispersing member 21 and a collision energy absorbing member 23 .

[0048] <<First Load Transfer Dispersion Member>> The first load transfer dispersion member 21 is provided to extend in the vehicle longitudinal direction on the vehicle outer side within the closed cross-sectional space 10a of the side sill 10. The first load transfer dispersion member 21 increases the strength of the side sill 10, transfers a frontal collision load input to the side sill 10 to the rear side of the vehicle, and distributes a side collision load input to the side sill 10 in the vehicle longitudinal direction.

[0049] 1 and 3, the first load transfer dispersion member 21 has a closed cross section perpendicular to the vehicle longitudinal direction. An end of the first load transfer dispersion member 21 on the vehicle outer side is connected to the inner surface of the vertical surface 13a of the side sill outer panel 13, which is the inner surface of the side sill 10, by welding (for example, spot welding), adhesive, or the like.

[0050] <Collision Energy Absorption Member> The collision energy absorption member 23 is disposed in the closed cross-sectional space 10a of the side sill 10 on the vehicle inner side of the first load transmission distribution member 21 in the vehicle width direction, and its end portion 23d1 on the vehicle outer side is connected to the first load transmission distribution member 21. In the event of a side collision of the vehicle, the collision energy absorption member 23 transmits the side impact load distributed by the first load transmission distribution member 21 to the vehicle inner side, and absorbs the collision energy by deforming when the transmitted side impact load exceeds a predetermined load.

[0051] The vehicle outer end 23d1 being connected to the first load transfer distribution member 21 means that the end 23d1 is attached to the first load transfer distribution member 21 so that the side impact load is transmitted from the first load transfer distribution member 21 to the collision energy absorbing member 23. Furthermore, the "predetermined load" refers to the buckling load of members to which the side impact load is transmitted from the side sill 10, such as a floor cross member or a battery case side member. By setting the collision energy absorbing member 23 to be equal to or less than the buckling strength of these members, it becomes possible to reliably buckle the collision energy absorbing member 23 from the side sill 10, thereby improving battery protection performance.

[0052] In the first embodiment, the collision energy absorbing member 23 has a closed cross section perpendicular to the vehicle width direction, as shown in Fig. 3. Furthermore, the collision energy absorbing members 23 are provided at two or more locations spaced apart in the vehicle longitudinal direction, as shown in Fig. 2. Each collision energy absorbing member 23 is joined at a position such that the end 23d1 on the vehicle outer side faces the first load transfer dispersion member 21. The end 23d and the first load transfer dispersion member 21 may be attached, for example, by providing an attachment flange on the end 23d1 and joining (by welding, etc.).

[0053] <Vehicle Side Structure> Fig. 4 shows an example of a vehicle side structure 100 including a side sill structure 1 according to the first embodiment. As shown in Fig. 4, the vehicle side structure 100 includes a floor panel 101, a floor cross member 103, and a battery case 105. Fig. 5 shows a specific example of the floor panel 101, the floor cross member 103, and the battery case 105 that are disposed between the left and right side sills 10 in the vehicle width direction.

[0054] The floor cross member 103 is a body frame structural member disposed above the floor panel 101 and extending in the vehicle width direction. Multiple floor cross members 103 are provided at predetermined intervals (e.g., about 300 mm) in the vehicle longitudinal direction, and as shown in Figure 4, the end 103a in the vehicle width direction is joined (e.g., spot welded) to the vertical surface 11a of the side sill inner 11 via the floor panel 101.

[0055] The battery case 105 is disposed below the floor panel 101 and houses a battery pack 107 therein. The battery case 105 has an upper battery case 105a, a lower battery case 105b, and a battery case cross 105c.

[0056] The battery case 105 is disposed so that its side surface 105d in the vehicle width direction faces, with a predetermined gap between it and the lower part of the vertical surface portion 11a of the side sill inner panel 11. Furthermore, the battery case 105 is provided with a mounting flange 105f that protrudes from a bottom plate 105e toward the side sill 10. The mounting flange 105f and the horizontal surface portion 11b of the lower part of the side sill inner panel 11 are fastened together with fixing bolts 109, thereby supporting the battery case 105 on the side sill 10.

[0057] The side sill structure 1 is arranged so that the reinforcing structure 20 (the first load transmission / distribution member 21 and the collision energy absorption member 23) is at the same position as the floor cross member 103 in the vehicle height direction.

[0058] <Operation and Effect of Side Sill Structure 1> The operation and effect of the side sill structure 1 according to the first embodiment will be described below for both a side collision and a frontal collision of the vehicle.

[0059] <<Side Collision>> Figure 6 shows the deformation of the first load transmission / dispersion member 21 and the collision energy absorption member 23 obtained by collision analysis of a side pole collision test in which a collision object was collided with the side of the side sill 10 of a vehicle equipped with the side sill structure 1 shown in Figure 1. In this collision analysis, the collision object was a rigid pole with a radius of 127 mm (equivalent to a diameter of 254 mm), the collision speed was 30.9 km / h, and the collision energy was 32 kJ. Note that Figure 6 is a contour diagram of equivalent plastic strain at each elapsed time t (seconds) from the start of the collision, and also shows two floor cross members 103-1 and 103-2 provided on the inner side of the vehicle of the side sill 10, spaced apart in the fore-and-aft direction of the vehicle.

[0060] When an impact object strikes the side surface of the side sill 10 (the longitudinal surface portion 13a of the side sill outer panel 13), the side impact load input to the side sill 10 is dispersed in the vehicle longitudinal direction by the first load transmission and dispersion member 21. The side impact load dispersed by the first load transmission and dispersion member 21 is then transmitted to the collision energy absorption member 23-1, which is located close to the impact object in the vehicle longitudinal direction. As a result, the collision energy absorption member 23-1 transmits the side impact load to the floor cross member 103-1 on the vehicle inner side and begins to deform (from t=0.002 sec).

[0061] As the side collision progresses, the first load transmission distribution member 21 penetrates into the vehicle inner side, and the side impact load dispersed by the first load transmission distribution member 21 is transferred to the collision energy absorption member 23-2, which is positioned offset in the vehicle longitudinal direction from the collision position. As a result, the collision energy absorption member 23-2 deforms while transferring the side impact load to the floor cross member 103-2, which is offset in the vehicle longitudinal direction from the collision body (from t = 0.004 sec). This shows that the side impact load input to the side sill 10 is dispersed in the vehicle longitudinal direction by the first load transmission distribution member 21 and transferred to the multiple collision energy absorption members 23-1, 23-2.

[0062] In particular, in the side sill structure 1, the vehicle-outer-side end 23d1 of the collision energy absorbing member 23 is connected to the first load transfer dispersion member 21 (see FIG. 1). The reinforcing structure 20, in which the first load transfer dispersion member 21 and the collision energy absorbing member 23 are integrated in this manner, has high deformation resistance against a side impact load, and therefore, as shown in FIG. 6, the reinforcing structure 20 deforms as a unit without localized deformation (e.g., without bending at the impact position) in response to the side impact load. Therefore, the reinforcing structure 20 functions as a reinforcing structure that increases the resistance of the side sill 10 to a side impact load.

[0063] Figure 7 shows the relationship between the penetration depth of the impactor and the amount of absorbed collision energy, as determined by crash analysis of a side face pole crash. Figure 7 shows that the first load transmitting / dispersing member 21 and the collision energy absorbing member 23 are primarily deformed, absorbing almost all of the 32 kJ of collision energy held by the impactor within a penetration depth of 90 mm.

[0064] In this way, in the side sill structure 1 according to the first embodiment, the side impact load input to the side sill 10 during a side impact is dispersed in the longitudinal direction of the vehicle by the first load transmission dispersion member 21, and the dispersed side impact load is transmitted to the inner side of the vehicle by the collision energy absorption member 23, which deforms and absorbs the collision energy. As a result, in the event of a side impact of a vehicle equipped with a battery pack 107 as shown in FIG. 4, the side impact load transmitted to the battery pack 107 is suppressed and the collision energy absorption performance is improved, thereby protecting the battery pack 107 from the impact of the side impact.

[0065] Furthermore, in the side sill structure 1 shown in Fig. 1, the first load transmission / distribution member 21 has a closed cross-section perpendicular to the vehicle longitudinal direction (see Figs. 1 and 3), which provides high bending rigidity against a side impact load. Furthermore, the collision energy absorbing member 23 has a closed cross-section perpendicular to the vehicle width direction, which provides high resistance to buckling due to a side impact load. Furthermore, the collision energy absorbing member 23 is provided in two or more locations spaced apart in the vehicle longitudinal direction in the region where the floor cross member 103 is installed (see Fig. 6).

[0066] This makes it possible for the side sill structure 1 to reduce differences (variations) in collision performance depending on the impact position of the impacting object during a side collision, and therefore satisfies the strict requirement to protect the battery pack 107 regardless of the impact position of the pole (impacting object) in a side impact test (side pole impact test specified by Euro NCAP) for an electric vehicle equipped with a battery pack 107 under the vehicle.

[0067] In addition, by providing the multiple collision energy absorption members 23 in two or more locations spaced apart in the fore-and-aft direction of the vehicle in the area in the fore-and-aft direction of the vehicle where the floor cross member 103 is installed, the increase in vehicle weight can be suppressed, and weight reduction can be achieved.

[0068] The collision energy absorbing member 23 shown in Fig. 2 is provided in the area in the vehicle longitudinal direction where the floor cross member 103 (Fig. 6) is installed. However, the collision energy absorbing member 23 may be provided in an area other than the area of ​​the floor cross member 103 in the vehicle longitudinal direction.

[0069] Furthermore, because the side sill structure 1 has the collision energy absorbing member 23 disposed within the closed cross-sectional space 10a of the side sill 10, it is possible to reduce the amount of deformation required to absorb collision energy. This reduces the space required for the side sill 10 to absorb collision energy. As a result, when the side sill structure 1 is applied to an electric vehicle, it is possible to increase the volume of the battery case 105 disposed between the side sills 10 on both sides in the vehicle width direction, thereby increasing the capacity of the battery pack 107.

[0070] <<Frontal Collision>> Figure 8 shows the relationship between the frontal collision load and the amount of collision energy absorption obtained by collision analysis of a frontal collision test in which a collision object (a rigid flat plate) is collided with the front of the side sill 10 of a vehicle equipped with the side sill structure 1. In this collision analysis, the collision object was a rigid flat plate (weight 677 kg), and the collision speed was 30.9 km / h.

[0071] Unlike in a side collision, the crashworthiness required of the side sill 10 in a frontal collision is to minimize deformation of the side sill 10 and prevent vehicle body parts from entering the vehicle interior and coming into contact with occupants. Therefore, in a frontal collision test, it is important to increase the maximum value of the frontal impact load generated in the early stage of the collision, because the greater the maximum value of the frontal impact load, the less likely buckling will occur.

[0072] In a frontal collision test conducted on the side sill structure 1 according to the first embodiment, it was confirmed that the frontal collision load increased immediately after the start of the collision, reached a maximum load (1078 kN) when the side sill 10 buckled, and then decreased, as shown in Fig. 8. This result shows that the side sill structure 1 transmits the frontal collision load input to the tip of the side sill 10 during a frontal collision of the vehicle to the rear of the vehicle via the side sill 10 and the first load transfer dispersion member 21, thereby increasing the buckling strength of the side sill 10 and making it possible to protect occupants from the impact of a frontal collision.

[0073] In particular, as described above, the first load transmission distribution member 21 has a closed cross section perpendicular to the vehicle longitudinal direction (see FIGS. 1 and 3). This allows the first load transmission distribution member 21 to increase the resistance to buckling of the side sill 10, increase the maximum load generated in the early stage of a collision, and function as a reinforcing structure that increases the strength of the side sill 10. As a result, in vehicles such as electric vehicles that have a battery pack mounted between the side sills, there is the advantage that the space required to sufficiently absorb collision energy can be reduced, allowing the volume of the battery pack to be increased.

[0074] The closed cross-sectional shape of the first load transfer / dispersion member 21 is preferably one or more rectangular closed cross-sectional shapes formed by a single or multiple parts, as exemplified in FIGS.

[0075] 9(a) to 9(e) show first load transfer dispersion members 21 each having a rectangular closed cross-sectional shape made of a single part. The first load transfer dispersion member 21 shown in FIG. 9(a) is made of a single pipe part. The first load transfer dispersion members 21 shown in FIGS. 9(b) and 9(c) are made of a roll-formed product. These first load transfer dispersion members have a rectangular closed cross-sectional shape formed from a single steel plate.

[0076] The first load transfer dispersion member 21 shown in Fig. 9(d) has a rectangular closed cross-sectional shape formed by joining two groove-shaped components. The first load transfer dispersion member 21 shown in Fig. 9(e) has a rectangular closed cross-sectional shape formed by joining two hat-shaped components. In addition to the configurations shown in Figs. 9(d) and 9(e), the closed cross-sectional shape may also be formed by joining a groove-shaped component and a closing plate (not shown).

[0077] 9( a) to 9(e), the first load transfer dispersion member 21 has a rectangular closed cross section and includes a pair of opposing longitudinal surfaces 21a and a pair of lateral surfaces 21b, the longitudinal surfaces 21a and the lateral surfaces 21b being connected via a ridge portion 21c (bend portion) extending along the vehicle longitudinal direction. This type of first load transfer dispersion member 21 is preferable because it can improve the strength (rigidity) of the side sill 10 against a frontal collision load input to the tip of the first load transfer dispersion member 21 along the vehicle longitudinal direction.

[0078] FIG. 10 shows a first load transfer / distribution member 21A having two rectangular closed cross-sectional shapes formed by a single or multiple parts.

[0079] Fig. 10(a) shows a first load transfer dispersion member 21A formed by arranging two pipe parts, each having a rectangular closed cross-sectional shape when viewed from the front-rear direction of the vehicle, one above the other, with an intermediate horizontal surface 21d provided between the upper and lower horizontal surfaces 21b, 21b. Fig. 10(b) shows a first load transfer dispersion member 21A formed by bending a single metal plate to form a pair of opposing vertical surfaces 21a and horizontal surfaces 21b, and an intermediate horizontal surface 21d, so that two rectangular closed cross-sectional shapes are connected in the vertical direction of the vehicle.

[0080] The first load transfer dispersion member 21A shown in FIG. 10 can increase the area (pressure-receiving area) of the portion where the collision load is applied by contact with the impact body when a side impact load is applied to a localized position in the fore-and-aft direction of the vehicle during a side impact test (a side pole impact test specified by Euro NCAP). Furthermore, the first load transfer dispersion member 21A shown in FIG. 10 can increase the bending rigidity against the side impact load by providing the intermediate lateral surface portion 21d. As a result, the strength of the side sill 10 against the side impact load can be improved.

[0081] In particular, the first load transfer dispersion member 21A shown in FIG. 10 has a longitudinal surface portion 21 a and a lateral surface portion 21 b, and a longitudinal surface portion 21 a and an intermediate lateral surface portion 21 d, each of which is formed continuously via a ridge portion 21 c, resulting in a plurality of (eight) ridge portions 21 c extending along the vehicle longitudinal direction. Furthermore, the first load transfer dispersion member 21 has a plurality of transverse surfaces (lateral surface portions 21 b, intermediate lateral surface portions 21 d) extending in a direction perpendicular to the vehicle longitudinal direction (vehicle width direction). Because the first load transfer dispersion member 21 has eight ridge portions 21 c and three transverse surfaces (lateral surface portions 21 b, intermediate lateral surface portions 21 d), it can increase bending rigidity against a side impact load (side impact load) input from the vehicle width direction during a side collision.

[0082] Furthermore, the first load transfer distribution member 21 provided with the intermediate lateral surface portion 21d has an increased load transfer path in the fore-and-aft direction of the vehicle (lateral surface portion 21b, intermediate lateral surface portion 21d), and therefore can further distribute the side impact load in the fore-and-aft direction of the vehicle, thereby further increasing the buckling resistance of the side sill 10 against a side impact.

[0083] 10 can be formed by continuously joining the ridges 21c1 between the vertical surface 21a and the intermediate horizontal surface 21d along the vehicle longitudinal direction by welding (laser welding, arc welding, etc.). This allows the vertical surface 21a and the intermediate horizontal surface 21d to deform together during a side collision, thereby increasing the buckling strength against a side impact load and facilitating the distribution of the side impact load in the vehicle longitudinal direction.

[0084] Furthermore, the first load transfer dispersion member 21A shown in Fig. 10 has eight ridges 21c extending along the vehicle longitudinal direction, which is twice the number (four) of ridges 21c of the single rectangular closed cross-sectional shape (Fig. 9). This further improves the strength (rigidity) of the first load transfer dispersion member 21 against a load (frontal collision load) input to the tip of the first load transfer dispersion member 21 in the vehicle longitudinal direction.

[0085] Furthermore, the provision of the intermediate lateral surface portion 21d increases the number of load transfer paths (lateral surface portion 21b, intermediate lateral surface portion 21d) that transmit the frontal impact load in the fore-and-aft direction of the vehicle during a frontal collision, allowing the frontal impact load to be transmitted through more load transfer paths, thereby further increasing the buckling resistance of the side sill 10 against the frontal impact load.

[0086] The closed cross-sectional shape of the collision energy absorption member 23 is preferably one or more rectangular closed cross-sectional shapes formed by a single or multiple parts, similar to the first load transmission / distribution member 21 shown in Figures 9 and 10. Figures 9 and 10 illustrate the cross-sectional shape perpendicular to the vehicle front-rear direction of the first load transmission / distribution member 21, but the cross-sectional shape perpendicular to the vehicle width direction of the collision energy absorption member 23 is similar, so will be referred to in the following description of the collision energy absorption member 23.

[0087] The collision energy absorption member 23 (see FIG. 3) according to the first embodiment is a steel plate structure having a rectangular closed cross-sectional shape formed by a pair of vertical surface portions and a pair of horizontal surface portions, and the vertical surface portions and the horizontal surface portions are formed continuously via ridge portions.

[0088] In this way, the collision energy absorption member 23 has ridge portions extending along the longitudinal direction (vehicle width direction) at the four corners of the rectangular closed cross-sectional shape, thereby improving the rigidity (strength) against the side collision load input from the first load transmission distribution member 21.

[0089] The collision energy absorption member 23 having a rectangular closed cross-sectional shape may be formed from a single part such as a pipe or a roll-formed product, or may be formed from multiple parts such as grooved parts, similar to the first load transmission / distribution member 21 shown in Figure 9.

[0090] Furthermore, the collision energy absorbing member 23 may have multiple rectangular closed cross-sectional shapes formed by a single or multiple parts, similar to the first load transfer dispersion member 21 shown in Fig. 10. An example of such a collision energy absorbing member 23 is one in which, similar to the first load transfer dispersion member 21 shown in Fig. 10, an intermediate lateral surface portion is provided between upper and lower lateral surfaces, and two rectangular closed cross-sectional shapes are connected in the vertical direction of the vehicle.

[0091] The collision energy absorption member 23 having two rectangular closed cross-sectional shapes has twice the number of ridges (8) extending along the longitudinal direction (vehicle width direction) compared to the number of ridges (4) of a single rectangular closed cross-sectional shape. This increases the buckling resistance against a side collision load input to the end portion 23d1 of the collision energy absorption member 23, and improves the load transmission performance to the floor cross member 103 (FIG. 4) disposed on the vehicle inner side.

[0092] Furthermore, the collision energy absorption member 23 provided with an intermediate lateral surface portion can improve the amount of collision energy absorption by deforming (axial crushing) itself when the side collision load dispersed by the first load transmission dispersion member 21 and transmitted to the vehicle inner side exceeds a predetermined load.

[0093] Furthermore, the collision energy absorbing member 23 having two rectangular closed cross-sectional shapes may be formed by connecting two rectangular closed cross-sectional shapes adjacent to each other in the vehicle longitudinal direction, as shown in FIG.

[0094] 11(a) and 11(b) , similarly to Fig. 10 , the collision energy absorption member 23 shown in Fig. 11(a) and 11(b) has twice the number of ridge portions 23c extending along its longitudinal direction (vehicle width direction) (from four to eight) compared to the collision energy absorption member 23 having a single rectangular closed cross-sectional shape (see Fig. 9) Therefore, it is possible to increase the buckling resistance against a side collision load input to the end portion 23d1 of the collision energy absorption member 23, and improve the load transmission performance to the floor cross member 103 on the vehicle inner side.

[0095] Furthermore, in the collision energy absorbing member 23 provided with the intermediate vertical surface portion 23e, not only is the amount of collision energy absorbed improved by deformation (axial crush) of the collision energy absorbing member 23 itself, but deformation that would open up the closed cross-sectional shape in the vertical direction of the vehicle due to a side impact load can be suppressed, making it possible to suppress a sudden drop in load after buckling occurs.

[0096] The collision energy absorption member 23A shown in FIG. 11( c) has a structure in which two adjacent rectangular closed cross-sectional shapes are connected via a connecting member, and is formed by joining two grooved components 231, 231 formed by bending a single metal plate into a generally M-shaped cross section. Each grooved component 231 has a first vertical wall portion 231a, a first top plate portion 231b, a second vertical wall portion 231c, and a second top plate portion 231d. The ends of the first vertical wall portion 231a of the grooved component 231 are joined to the surfaces of the second top plate portion 231d. This results in a structure in which the two rectangular closed cross-sectional shapes are connected via the second top plate portion 231d.

[0097] 11(c) is obtained by increasing the number of ridges 23c by forming recesses on the upper and lower lateral surfaces of the collision energy absorption member 23 (see FIG. 3) having a single rectangular closed cross section. This allows the collision energy absorption member 23A to have improved buckling strength without increasing its weight.

[0098] Furthermore, the collision energy absorption member 23A can be deformed as a single unit by joining the second top plate portions 231d together with the opening sides of the channel-shaped components 231 facing each other and overlapping and joining portions of the first vertical wall portions 231a. When joining the two channel-shaped components 231, continuous welding along the longitudinal direction can suppress cross-sectional collapse during axial crushing deformation that occurs during a side collision, thereby improving collision energy absorption performance. When joining the first vertical wall portions 231a to form the collision energy absorption member 23A, lap fillet welding can be performed by arc welding, with an overlap of approximately 5 mm.

[0099] 12A and 12B show variations of the reinforcing structure 20 in the side sill structure 1. In Fig. 12A, the cross-sectional area of ​​the collision energy absorbing member 23 increases toward the vehicle inner side in the vehicle width direction. In this case, during a side collision, the collision energy absorbing member deforms first at a location with a small cross-sectional area, making it possible to control the buckling start position.

[0100] 12(b) shows the side sill structure 1 having a hat-shaped first load transfer dispersion member 21. The first load transfer dispersion member 21 is not limited to having the closed cross-sectional shape described above, but may also form a closed cross-sectional shape between itself and the inner surface of the side sill 10 on the vehicle outer side (for example, the inner surface of the vertical surface portion 13a of the side sill outer panel 13), as shown in FIG.

[0101] Even in the side sill structure 1 equipped with the first load transmission and distribution member 21 having such a hat cross section, when a side impact load is input from the side of the vehicle, the side impact load can be distributed and transmitted to the collision energy absorbing members 23 that are spaced apart in the front-rear direction of the vehicle from the position where the side impact load is input. Therefore, even in the side sill structure 1 in which multiple collision energy absorbing members 23 are arranged spaced apart in the front-rear direction of the vehicle, the side sill structure 1 can ensure side impact resistance characteristics and suppress an increase in the weight of the vehicle body, thereby achieving the weight reduction required for electric vehicles.

[0102] 12(c) shows a side sill structure 1 in which a mounting flange 23f is provided at the vehicle inner end of the collision energy absorbing member 23 to join with the vertical surface 11a of the side sill inner panel 11. This side sill structure 1 has the effect of suppressing displacement of the first load transmitting / dispersing member 21 or the collision energy absorbing member 23 in the vertical direction of the vehicle during a side collision, thereby improving the efficiency of absorbing collision energy, and also has the effect of reducing manufacturing costs by eliminating a joining structure.

[0103] Figure 12 (d) shows a side sill structure in which the first load transmission dispersion member 21 has multiple rectangular cross-sectional shapes. As mentioned above, this has the effect of improving the strength of the side sill 10 by increasing the bending rigidity against side impact loads during a side collision, and improving the strength of the side sill against frontal impact loads during a frontal collision.

[0104] [Other Aspects of First Embodiment] In the side sill structure 1 according to the first embodiment of the present invention, the first load transmission / dispersion member 21 is extended to the vehicle outer side within the closed cross-sectional space 10a of the side sill 10. However, another aspect of the first embodiment is a side sill structure 3 shown in FIG.

[0105] The side sill structure 3 includes a reinforcing structure 30 that further includes a second load transmitting / dispersing member 31 in addition to the first load transmitting / dispersing member 21 and the collision energy absorbing member 23 described above.

[0106] <<Second Load Transfer Dispersion Member>> The second load transfer dispersion member 31 is provided extending in the vehicle longitudinal direction on the vehicle inner side within the closed cross-sectional space 10a of the side sill 10. The second load transfer dispersion member 31 increases the strength of the side sill 10 and transfers a frontal collision load input from the front of the vehicle to the side sill 10 to the rear of the vehicle. Furthermore, in the event of a side collision of the vehicle, the second load transfer dispersion member 31 distributes the side collision load transferred from the collision energy absorption member 23 in the vehicle longitudinal direction.

[0107] 13A, the second load transfer dispersion member 31 has a closed cross section perpendicular to the vehicle longitudinal direction. The end of the second load transfer dispersion member 31 on the vehicle inner side is connected to the inner surface of the vertical surface 11a of the side sill inner panel 11, which is the inner surface of the side sill 10, by welding (e.g., spot welding), adhesive, or the like.

[0108] <Collision Energy Absorption Member> In the side sill structure 3, the vehicle inner side end 23d2 of the collision energy absorbing member 23 is connected to the second load transfer dispersion member 31. "The vehicle inner side end 23d2 of the collision energy absorbing member 23 is connected to the second load transfer dispersion member 31" means that the end 23d2 is attached to the second load transfer dispersion member 31 so that the side collision load is transmitted from the collision energy absorbing member 23 to the second load transfer dispersion member 31.

[0109] In the side sill structure 3, the collision energy absorbing member 23 is attached at a position where the end 23d2 on the vehicle inner side faces the second load transmission and dispersion member 31. The end 23d2 of the collision energy absorbing member 23 is attached to the second load transmission and dispersion member 31 by providing an attachment flange on the end 23d2 and joining (welding, etc.).

[0110] <Operations and Effects of Side Sill Structure 3> The side sill structure 3 according to another aspect of the first embodiment provides the following operations and effects in the event of a side collision and a frontal collision of the vehicle.

[0111] <<Side Collision>> In the event of a side collision, the side sill structure 3, like the side sill structure 1 described above, distributes the side impact load in the fore-and-aft direction of the vehicle using the first load transmission and distribution member 21, and transmits the side impact load to the vehicle inner side and absorbs the collision energy using the collision energy absorption member 23. Furthermore, the side sill structure 3 distributes the side impact load transmitted to the vehicle inner side by the collision energy absorption member 23 shown in Figures 9 and 10 in the fore-and-aft direction of the vehicle using the second load transmission and distribution member 31. This allows the side impact load transmitted to the multiple floor cross members 103 to be distributed in the fore-and-aft direction of the vehicle, thereby reducing the side impact load input to the battery pack 107 and further improving collision resistance.

[0112] <<Frontal Collision>> Furthermore, in the event of a frontal collision of a vehicle equipped with the side sill structure 3, the first load transmission distribution member 21 and the second load transmission distribution member 31 can further improve the strength of the side sill 10, making buckling less likely to occur. This increases the maximum value of the frontal collision load generated in the early stage of the collision, thereby improving frontal collision resistance.

[0113] In the side sill structure 3, it is preferable that the closed cross-sectional shape of the first load transfer dispersion member 21 be one or more rectangular closed cross-sectional shapes formed by a single or multiple parts, as in the side sill structure 1 described above (Figures 9 and 10).

[0114] Furthermore, similar to the first load transfer dispersion member 21, the closed cross-sectional shape of the second load transfer dispersion member 31 is preferably one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

[0115] In the side sill structure 3, the first load transmission dispersion member 21, the collision energy absorption member 23 and the second load transmission dispersion member 31 that form the reinforcing structure 30 are not limited to the shape shown in Figure 13(a) described above, but may also have shapes such as those shown in Figures 13(b) to (f).

[0116] In Fig. 13(b), the cross-sectional area of ​​the collision energy absorption member 23 increases toward the vehicle inner side along the vehicle width direction. This type of collision energy absorption member 23 has the advantage of being able to control the buckling initiation position because it deforms first at the location with the smallest cross-sectional area during a collision. In Fig. 13(c), the cross-sectional areas of the first load transfer dispersion member 21 and the second load transfer dispersion member 31 are different. By increasing the cross-sectional area of ​​the second load transfer dispersion member 31 on the vehicle inner side, the side collision load transmitted from the collision energy absorption member 23 can be more effectively dispersed in the vehicle longitudinal direction, which is preferable.

[0117] 13(d)(i) and (ii) show a hat-shaped second load transfer dispersion member 31 provided with a flange 31f for attachment to the vertical surface 11a of the side sill inner panel 11, forming a closed cross-sectional shape between the second load transfer dispersion member 31 and the vertical surface 11a of the side sill inner panel 11, which is the inner surface of the vehicle inner side of the side sill 10. Such a hat-shaped second load transfer dispersion member 31 can suppress displacement in the vertical direction of the vehicle during a side collision and improve the efficiency of absorbing collision energy. Furthermore, manufacturing costs can be reduced by omitting a joining structure for joining the second load transfer dispersion member 31 to the side sill inner panel 11.

[0118] 13(e)(i) and (ii) show reinforcing members 31e joined to the ridges and interior of the hat-shaped second load transfer dispersion member 31. This allows for improved rigidity (strength) without increasing the overall plate thickness of the second load transfer dispersion member 31, making it possible to suppress excessive weight increases for improved side collision resistance.

[0119] 13(a) to 13(e) show a single rectangular closed cross-sectional shape formed from a single part. However, the second load transfer dispersion member 31 may also have multiple rectangular closed cross-sectional shapes formed from multiple parts, similar to the first load transfer dispersion member 21 described above (see FIG. 10).

[0120] Figure 13(f) shows a side sill structure 3 in which a second load transfer distribution member 31A having two rectangular closed cross-sectional shapes connected in the vertical direction of the vehicle is provided, separated by an intermediate horizontal surface portion 31d arranged across the vehicle width direction, similar to the first load transfer distribution member 21A shown in Figures 10 and 12(d) described above.

[0121] The second load transmission distribution member 31A can deform the vertical surface portion 31a and the intermediate horizontal surface portion 31d as a single unit. Therefore, the second load transmission distribution member 31A can increase the buckling resistance against the side impact load transmitted from the collision energy absorbing member 23 and promote the load transmission in the longitudinal direction of the vehicle. Furthermore, the second load transmission distribution member 31A can also improve the buckling resistance in the event of a frontal collision because the number of paths for transmitting the front impact load to the rear of the vehicle is increased.

[0122] 13(f), when the second load transfer dispersion member 31 has a plurality of rectangular closed cross-sectional shapes, the longitudinal surface portions 31a and the intermediate horizontal surface portions 31d may be continuously joined by arc welding or laser welding. However, similar to the first load transfer dispersion member 21 shown in FIG. 10(b), the second load transfer dispersion member 31 is preferably formed by bending a single metal plate to form a pair of opposing longitudinal surface portions 31a and horizontal surface portions 31b, as well as the intermediate horizontal surface portion 31d, so that the rectangular closed cross-sectional shapes are continuous in the vertical direction of the vehicle.

[0123] 14 and 15 show the best mode of a side sill structure 3A according to the present invention. The side sill structure 3A has a reinforcing structure 30A provided within the closed cross-sectional space 10a of the side sill 10. Fig. 14 is an exploded view of the side sill structure 3A, with each component part shown, and Fig. 15 is an enlarged view of the joint between the reinforcing structure 30A and the inner surface of the side sill 10 on the vehicle inner side.

[0124] The reinforcing structure 30A includes a first load transmitting / dispersing member 21A, a second load transmitting / dispersing member 31A, and a collision energy absorbing member 23A.

[0125] As shown in Figure 10(b) above, the first load transfer distribution member 21A and the second load transfer distribution member 31A have two rectangular closed cross-sectional shapes whose cross-sectional shapes perpendicular to the fore-and-aft direction of the vehicle are connected in the vertical direction of the vehicle.

[0126] 11(c) , the collision energy absorbing member 23A is formed by joining two grooved components 231, 231 formed by bending a single metal plate into a generally M-shaped cross section. The collision energy absorbing member 23A further includes a first joining flange 23i that protrudes from the first top plate portion 231b toward the vehicle outer side at the vehicle outer side end, and a second joining flange 23j that protrudes from the first top plate portion 231b toward the vehicle inner side at the vehicle inner side end. The second joining flange 23j has a surface portion 23j1 that extends in the vehicle width direction, and a surface portion 23j2 that bends and extends in the vehicle upward direction from the vehicle inner side tip of the surface portion 23j1.

[0127] At the end on the vehicle outer side, the first joining flange 23i is joined (by arc welding or the like) to the lateral surface 21b of the first load transfer distribution member 21. At the end on the vehicle inner side, the surface 23j1 of the second joining flange 23j is joined (by electric arc welding or the like) to the lateral surface 31b of the second load transfer distribution member 31. Furthermore, the surface 23j2 of the second joining flange 23j is connected (by spot welding or the like) to the inner surface of the side sill 10 (the inner surface of the vertical surface 11a of the side sill inner panel 11).

[0128] This side sill structure 3A facilitates the transfer of a side impact load from the first load transfer / distribution member 21A to the second load transfer / distribution member 31A via the collision energy absorbing member 23A, thereby improving the buckling strength of the first load transfer / distribution member 21A and the second load transfer / distribution member 31A, thereby enabling the collision energy to be sufficiently absorbed during a side impact.

[0129] Furthermore, in the side sill structure 3A, the surface 23j2 of the second joining flange 23j of the collision energy absorption member 23A is joined to the inner surface of the side sill 10 (the vertical surface 11a of the side sill inner panel 11), and the vehicle-outer side end of the first load transfer dispersion member 21A abuts against the inner surface of the side sill 10. This enables the side sill structure 3A to omit support parts for supporting the reinforcing structure 30A within the closed cross-sectional space 10a of the side sill 10, thereby reducing manufacturing and assembly costs.

[0130] In the side sill structure according to the present invention, if the yield strength of the metal plate forming the collision energy absorbing member is set to be approximately the same as the yield strength of the metal plate forming the floor cross member, it is preferable to provide beads (crash beads) or the like on the vertical or horizontal surfaces of the collision energy absorbing member. This is because by allowing the collision energy absorbing member to buckle from the bead, the buckling strength of the collision energy absorbing member (i.e., the load at which the member itself begins to buckle) can be made lower than the buckling strength of the floor cross member, which is preferable.

[0131] Furthermore, the collision energy absorbing member may have beads on its surface in order to increase or decrease its buckling strength (rigidity).

[0132] 16A and 16B are cross-sectional views of the side sill 10 taken perpendicular to the vehicle longitudinal direction, and schematically illustrate the collision energy absorbing member 23 having beads 23g and 23h formed thereon. The bead 23g shown in Fig. 16A is provided on the vertical surface 23a of the collision energy absorbing member 23 along the vehicle width direction in order to increase the buckling strength. In contrast, the bead 23h shown in Fig. 16B is provided on the vertical surface 23a of the collision energy absorbing member 23 along the vehicle up-down direction as a crash bead to reduce the buckling strength.

[0133] Although FIG. 16 shows beads 23g and 23h provided on the vertical surface 23a of the collision energy absorbing member 23, beads may be provided on the upper and lower horizontal surface 23b of the vehicle that forms a rectangular closed cross section.

[0134] In the above description, the vehicle-outer-side end of the first load transfer dispersion member 21 is connected to the opposing inner surface of the side sill 10 (the inner surface of the vertical surface 13a of the side sill outer panel 13) mainly to prevent vibration. The connection between the vehicle-outer-side end of the first load transfer dispersion member 21 and the vertical surface 13a is not limited to welding (spot welding, etc.), but may also be by bonding (adhesive layer 15) as shown in FIG. 17(b). Similarly, in the side sill structure 1 shown in FIG. 1, the vehicle-inner-side end of the collision energy absorption member 23 is connected (spot welding, bonding, etc.) to the opposing inner surface of the vertical surface 11a of the side sill inner panel 11, which is the inner surface of the side sill 10.

[0135] In this way, in the side sill structure 1, by connecting the vehicle outer side end of the first load transmission dispersion member 21 and the vehicle inner side end of the collision energy absorption member 23 to the inner surface of the side sill 10, vibration is mainly prevented and the reinforcing structure 20 can be installed within the closed cross-sectional space 10a.

[0136] However, the first load transfer dispersion member 21 may abut against the inner surface of the vehicle outer side of the side sill 10 (the inner surface of the vertical surface portion 13a of the side sill outer 13), or may face the inner surface of the vertical surface portion 13a of the side sill outer 13 with a predetermined gap therebetween, as shown in Figure 17 (a).

[0137] In addition, as shown in Figure 17 (a), the collision energy absorption member 23 may be in contact with or facing the inner surface of the vehicle inner side of the side sill 10 (the inner surface of the vertical surface portion 11a of the side sill inner 11) with a predetermined gap therebetween.

[0138] If the first load transmission dispersion member 21 and the collision energy absorption member 23 are not connected to the inner surface of the side sill 10 as shown in Figure 17(a), the reinforcing structure 20 can be installed within the closed cross-sectional space 10a of the side sill 10 using a support part 17 as shown in Figure 18.

[0139] In Figure 18(a), the reinforcing structure 20 is supported by a support part 17 whose lower end is joined to the lower flange parts 11c, 13c that join the side sill inner part 11 and the side sill outer part 13. In Figure 18(b), the reinforcing structure 20 is supported by a support part 17 joined to the inner surface of the vertical surface part 13a of the side sill outer part 13. In both Figures 18(a) and (b), the reinforcing structure 20 is supported by a support part 17 provided below the reinforcing structure 20.

[0140] Figure 18(c) shows a support part 17-1 whose lower end is joined to the lower flange portions 11c, 13c of the side sill 10, and a support part 17-2 whose upper end is joined to the upper flange portions 11c, 13c, which are provided both above and below the reinforcing structure 20 to support it.

[0141] Even when the reinforcing structure 20 is installed via a support part 17 as shown in Figure 18, in the event of a side collision, the side impact load distributed by the first load transfer distribution member 21 can be transmitted to the second load transfer distribution member 31 via the collision energy absorption member 23.

[0142] In addition, in the description of the side sill structure 3 (see FIG. 13(a)) equipped with the above-mentioned reinforcing structure 30, the vehicle inner side end of the second load transfer distribution member 31 is connected to the inner surface of the side sill 10 by welding (spot welding, etc.) or adhesive. However, in the present invention, the second load transfer distribution member 31 may be in contact with the inner surface of the vehicle inner side of the side sill 10 (the vertical surface portion 11a of the side sill inner member 11) or may face the inner surface with a predetermined gap therebetween, similar to the first load transfer distribution member 21 shown in FIG.

[0143] In this way, when the first load transfer distribution member 21 and the second load transfer distribution member 31 of the reinforcing structure 30 are not connected to the inner surface of the side sill 10, it is preferable to install them within the closed cross-sectional space 10a of the side sill 10 via a support part 17, as with the reinforcing structure 20 shown in Figure 18.

[0144] When installing multiple collision energy absorbing members 23 in the closed cross-sectional space 10a of the side sill 10, it is preferable that the spacing W2 (see FIG. 19 ) between adjacent collision energy absorbing members 23 be equal to or less than the spacing WF (W2≦WF) between the floor cross members 103. This ensures that the side collision load can be transmitted reliably to the floor cross members 103 via the collision energy absorbing members 23.

[0145] Alternatively, to ensure the bending rigidity of the side sill 10 during a side collision, it is preferable that the distance W2 be 254 mm or less (W2≦254 mm). The value 254 mm is the diameter of the impact body (pole) used in the side pole impact test specified by Euro NCAP. By setting the distance W2 to be equal to or less than the diameter of the impact body used in the side pole impact test, the bending rigidity of the side sill 10 during a side collision can be more appropriately ensured.

[0146] From the viewpoint of ensuring the bending rigidity of the side sill 10 in the event of a side collision, it is more preferable to set the spacing W2 between adjacent collision energy absorption members 23 in the range of 1 / 4 to 1 / 2 of the spacing WF between adjacent floor cross members 103.

[0147] It is preferable that the width W1 (length in the vehicle width direction) of the first load transfer distribution member 21 satisfies W1 / WS < 0.4 in relation to the width WS (length in the vehicle width direction) of the side sill 10, and that the height H1 (length in the vehicle vertical direction) satisfies H1 / HF > 0.8 in relation to the height HF (height in the vehicle vertical direction) of the floor cross member 103.

[0148] This is because, during a side collision, the side impact load is transmitted through the lateral surface portion 21b and the intermediate lateral surface portion 21d of the first load transmission dispersion member 21. However, if the width W1 is large, the surface rigidity decreases, and the buckling strength decreases, which could lead to a decrease in load transmission performance. Therefore, the first load transmission dispersion member 21 preferably satisfies W1 / WS<0.4, and more preferably W1 / WS<0.3. This ensures the buckling strength against the side impact load and prevents a decrease in load transmission performance during a side collision.

[0149] Furthermore, in the event of a side collision, the side impact load is transmitted to the floor cross member 103 via the first load transmission / dispersion member 21 and the collision energy absorption member 23. If H1 is small relative to HF, the side impact load will be concentrated on one part of the floor cross member 103, which could cause the floor cross member 103 to buckle and deform, reducing its collision energy absorption performance. Therefore, by satisfying H1 / HF > 0.8, or more preferably H1 / HF > 0.85, it is possible to ensure load transmission performance to the floor cross member 103.

[0150] Furthermore, similar to the first load transfer dispersion member 21, the width W1 of the second load transfer dispersion member 31 preferably satisfies the relationship W1 / WS<0.4 with respect to the width WS of the side sill, and the height H1 of the second load transfer dispersion member 31 preferably satisfies the relationship H1 / HF>0.8 with respect to the height HF of the floor cross member 103, more preferably W1 / WS<0.3 and H1 / HF>0.85. This ensures the buckling strength of the second load transfer dispersion member 31 against a side impact load, and prevents a decrease in load transfer performance.

[0151] The higher the load at which the reinforcing structure 20 (first load transmitting / dispersing member 21 and collision energy absorbing member 23) changes from elastic deformation immediately after deformation starts to plastic deformation (hereinafter referred to as "yield strength"), the less likely it is to deform during a collision, and the better the collision performance. Furthermore, the higher the tensile strength of the metal plate, the higher the yield strength. Therefore, it is preferable that the reinforcing structure be formed using metal plate with a tensile strength of 590 MPa or higher, and that the tensile strength of the metal plate forming the collision energy absorbing member 23 be lower than the tensile strength of the metal plate forming the first load transmitting / dispersing member 21.

[0152] When a high-tensile steel plate is used for the first load transmission / distribution member 21, the buckling resistance against bending deformation due to a side collision is improved, and the side collision load is more effectively distributed and transmitted in the longitudinal direction of the vehicle. Therefore, it is particularly preferable that the metal plate used for the first load transmission / distribution member 21 be a high-tensile steel plate of 1180 MPa class or higher.

[0153] Using a high-tensile steel plate for the collision energy absorption member 23 improves buckling resistance and increases the effectiveness of transmitting a side impact load in the vehicle width direction during a side collision. On the other hand, since the collision energy absorption member 23 must also deform itself to absorb collision energy, it is preferable that the strength of the collision energy absorption member 23 be lower than that of the first load-transmitting / dispersing member 21. Therefore, it is particularly preferable that the metal plate used for the collision energy absorption member 23 be a high-tensile steel plate with a tensile strength of 980 MPa or higher and lower in strength than the first load-transmitting / dispersing member 21.

[0154] Furthermore, the buckling strength of the collision energy absorbing member 23 is preferably lower than the buckling strength of the first load transmitting / dispersing member 21. This is because, if a side impact load is input during a side collision and the first load transmitting / dispersing member 21 buckles before the collision energy absorbing member 23, causing the collision energy absorbing member 23 to bend in a V-shape in top view, deformation will be concentrated at the V-shaped bent portion, reducing the amount of load transmitted in the longitudinal direction (vehicle width direction) of the collision energy absorbing member 23 and reducing collision performance.

[0155] Furthermore, it is preferable that the yield strength of the metal plate used for the collision energy absorbing member 23 is equal to or less than the yield strength of the metal plate used for the floor cross member 103 (FIG. 4). This ensures that, in the event of a side collision, the collision energy absorbing member 23 buckles and deforms before the floor cross member 103 does, thereby sufficiently absorbing the collision energy and suppressing deformation of the floor cross member 103.

[0156] It is also preferable that the reinforcing structure 30 further including the second load transfer dispersion member 31 as shown in Figure 13 (a) is formed using a metal plate having a tensile strength of 590 MPa or more, and that the tensile strength of the metal plate forming the collision energy absorption member 23 is lower than the tensile strength of the metal plates forming the first load transfer dispersion member and the second load transfer dispersion member 31.

[0157] When a side impact load is input to a side sill structure 3 including a reinforcement structure 30 having a second load transfer distribution member 31, and the first load transfer distribution member 21 and the second load transfer distribution member 31 fold in a V-shape in top view, deformation concentrates at the folded location, reducing the amount of load transmitted in the vehicle width direction and degrading collision performance. Therefore, it is preferable to make the buckling strength of the collision energy absorption member 23 lower than the buckling strength (buckling resistance) of the first load transfer distribution member 21 and the second load transfer distribution member 31. This allows the collision energy absorption member 23 to buckle before the first load transfer distribution member 21 and / or the second load transfer distribution member 31 deform into a V-shape, thereby increasing the amount of load transmitted until the end of the collision.

[0158] The closer the front end position of the first load transmission dispersion member 21 is to the front end of the side sill 10, the shorter the time from immediately after a collision until load transmission begins. Therefore, from the perspective of improving collision resistance performance in frontal collisions, it is preferable to position the front end position of the first load transmission dispersion member 21 closer to the tip of the side sill 10.

[0159] More preferably, the length of the first load transfer dispersion member 21 (total length in the vehicle's longitudinal direction) is set to be equal to or greater than the length from the front end of the side sill 10 to the rear end of the battery case 105. In this case, load transfer can be initiated more quickly in a frontal collision, and load distribution performance (load transfer performance) can be exhibited in a side collision regardless of the position where the side impact load is input (collision position). This makes it possible to protect the battery pack 107 in both frontal and side collisions.

[0160] As with the first load transmission distribution member 21 , it is preferable that the position of the front end of the second load transmission distribution member 31 be close to the front end of the side sill 10 .

[0161] More preferably, by making the length of the second load transfer dispersion member 31 equal to or greater than the length from the front end of the side sill 10 to the rear end of the battery case 105, it is possible to hasten the start of load transfer in a frontal collision and to protect the battery pack 107 by keeping the load transfer performance in a side collision constant regardless of the collision position.

[0162] The position of the reinforcing structure 20 in the vertical direction of the vehicle can be adjusted so that the vertical surface portion 21a of the first load transfer distribution member 21 overlaps with the floor cross member 103 and the battery case 105 in the vertical direction of the vehicle, and so that the side impact load input to the floor cross member 103 and the battery case 105 is appropriately balanced.

[0163] [Embodiment 2] As shown in Figure 20, a side sill structure 5 according to embodiment 2 of the present invention includes a reinforcing structure 40 having a first load transfer dispersion member 21A, a collision energy absorption member 41, and a second load transfer dispersion member 31A.

[0164] The first load transmitting and dispersing member 21A and the second load transmitting and dispersing member 31A are the same as those in the first embodiment, and therefore, only the collision energy absorbing member 41 will be described below.

[0165] Collision Energy Absorption Member The collision energy absorption member 41 has an end on the vehicle outer side connected to the first load transmission and distribution member 21A and an end on the vehicle inner side connected to the second load transmission and distribution member 31A. In the event of a side collision of the vehicle, the collision energy absorption member 41 transmits the side impact load distributed by the first load transmission and distribution member 21A to the vehicle inner side, and when the transmitted side impact load exceeds a predetermined load, the collision energy is absorbed by deforming.

[0166] 21 is an exploded view of each component constituting the collision energy absorbing member 41. The collision energy absorbing member 41 includes a corrugated part 411 and a corrugated part 413 made of a metal plate, which have a corrugated shape in which convex shapes 411 a, 413 a and concave shapes 411 b, 413 b are alternately continuous in the vehicle longitudinal direction in a cross section perpendicular to the vehicle width direction.

[0167] The corrugated parts 411 and 413 are arranged in the vehicle vertical direction in an inverted state with the openings of the convex shapes 411 a and 413 a facing each other, and the bottoms of the concave shapes 411 b and 413 b are joined together. In this way, the collision energy absorbing member 41 has a structure in which two or more rectangular closed cross-sectional shapes 41 a are formed by the convex shapes 411 a and the convex shapes 413 a, and adjacent rectangular closed cross-sectional shapes 41 a are connected by the bottoms of the concave shapes 411 b and 413 b.

[0168] 22 is a plan view of the side sill structure 5, omitting the side sill inner panel 11 and the side sill outer panel 13. In the side sill structure 5, as shown in FIG. 22, one collision energy absorbing member 41 is provided so as to cover the area in the vehicle longitudinal direction where the floor cross members 103-1, 103-2 are installed. The collision energy absorbing member 41 is disposed in a position where its vehicle outer side end faces the first load transfer dispersion member 21. The vehicle outer side end of the collision energy absorbing member 41 and the first load transfer dispersion member 21 may be attached, for example, by providing a flange 41b at the vehicle outer side end and joining (welding, etc.).

[0169] The collision energy absorbing member 41 is disposed such that its vehicle-inner-side end faces the second load transfer dispersion member 31. The vehicle-inner-side end of the collision energy absorbing member 41 and the second load transfer dispersion member 31 may be attached, for example, by providing a flange 41c at the vehicle-inner-side end of the collision energy absorbing member 41 and joining (by welding, etc.) to the second load transfer dispersion member 31. Furthermore, the collision energy absorbing member 41 may be provided with a flange 41d extending upward from the vehicle-inner-side tip of the flange 41c and joined to the inner surface of the side sill inner panel 11.

[0170] <Function and Effect of Side Sill Structure 5> In the event of a side collision of the vehicle, the side sill structure 5 according to the second embodiment distributes the side collision load in the fore-and-aft direction of the vehicle using the first load transmission / distribution member 21, as does the side sill structure 1 according to the first embodiment. Furthermore, the side sill structure 5 transmits the side collision load to the inner side of the vehicle and absorbs the collision energy using the collision energy absorption member 23.

[0171] Furthermore, in the side sill structure 5, similar to the side sill structure 3 according to the other aspects of the first embodiment described above, in the event of a side collision of the vehicle, the side collision load transmitted by the collision energy absorbing member 41 to the inner side of the vehicle is distributed in the longitudinal direction of the vehicle by the second load transmission distribution member 31. This allows the side collision load transmitted to the multiple floor cross members 103 to be distributed in the longitudinal direction of the vehicle, thereby reducing the side collision load input to the battery pack 107 and further improving collision resistance.

[0172] Furthermore, in the side sill structure 5, one collision energy absorbing member 41 is provided so as to cover the area in the fore-and-aft direction of the vehicle where the floor cross members 103-1 and 103-2 are installed, thereby improving side collision resistance and reducing the number of parts constituting the side sill structure.

[0173] As shown in Figure 22, side sill structure 5 has a collision energy absorbing member 41 also present in the area between the two floor cross members 103-1, 103-2, so there is a concern that the weight may increase compared to, for example, the side sill structure 1 and side sill structure 3 described above.

[0174] However, since the cross section of the collision energy absorption member 41 perpendicular to the vehicle width direction has two or more rectangular closed cross-sectional shapes in the vehicle longitudinal direction, the collision energy absorption member 41 has an increased number of ridges compared to, for example, the collision energy absorption member 23 shown in Fig. 3, which has a single rectangular closed cross-sectional shape. As a result, even if a side impact load is input to the collision energy absorption member 41 during a side impact of the vehicle, it is less likely to become a starting point for axial compressive deformation, and buckling resistance can be increased. Therefore, by reducing the plate thickness of the collision energy absorption member 41, it is possible to suppress an increase in weight while ensuring sufficient side impact resistance performance.

[0175] The dimensions and placement of the collision energy absorbing member 41 may be determined as follows: When two floor cross members 103-1, 103-2 are installed, for example, as shown in Figure 22, the overall length Lwave of the collision energy absorbing member 41 in the vehicle's fore-and-aft direction may be set to be equal to or greater than the distance WF between the floor cross members 103-1, 103-2. This allows the collision energy absorbing member 41 to be provided so as to cover the area in the vehicle's fore-and-aft direction where the two floor cross members 103-1, 103-2 are installed.

[0176] The width (length in the vehicle's fore-and-aft direction) of the rectangular closed cross-sectional shape 41a of the collision energy absorbing member 41 should be equal to or less than the smaller of the width Wa of the installed floor cross member 103-1 and the width Wb of the floor cross member 103-2. This allows the side collision load to be effectively transmitted from the collision energy absorbing member 41 to the floor cross members 103-1 and 103-2 in the event of a side collision of the vehicle.

[0177] The collision energy absorption member 41 does not need to have adjacent rectangular closed cross-sectional shapes 41a spaced equally apart, but the spacing between the rectangular closed cross-sectional shapes can be appropriately determined so that there is one or more rectangular closed cross-sectional shapes 41a in the fore-and-aft area of ​​the vehicle where each floor cross member is installed.

[0178] The reinforcement structure 40 of the side sill structure 5 shown in Fig. 20 is provided with the second load transmission / distribution member 31. However, the reinforcement structure provided with the collision energy absorption member 41 as shown in Fig. 20 does not necessarily have to be provided with the second load transmission / distribution member, as with the reinforcement structure 20 of the side sill structure 1 described above.

[0179] If a side sill structure equipped with a collision energy absorption member 41 does not have a second load transmission dispersion member, the vehicle inner side end of the collision energy absorption member 41 should be connected to the inner surface of the opposing side sill 10 (side sill inner 11).

[0180] As described above, the collision energy absorbing member 41 and the inner surface of the side sill 10 may be connected by providing a flange on the vehicle-inner-side end of the collision energy absorbing member 41 and joining (by welding, etc.). However, the collision energy absorbing member 41 may also be in contact with the vehicle-inner-side inner surface of the side sill 10 or may face the inner surface at a predetermined distance from the inner surface. In this case, the reinforcing structure 40 may be installed within the closed cross-sectional space of the side sill 10 via a support part, as in the case of FIG. 18 described above.

[0181] In the side sill structure 5 including the second load transfer dispersion member 31, the second load transfer dispersion member 31 may be in contact with the inner surface of the vehicle inner side of the side sill (the inner surface of the side sill inner panel 11) or may face the inner surface at a predetermined distance. In this case, the reinforcing structure including the second load transfer dispersion member 31 may be installed within the closed cross-sectional space of the side sill 10 via a support part.

[0182] 20 has a cross section perpendicular to the vehicle width direction that has two or more rectangular closed cross-sectional shapes in the vehicle longitudinal direction, due to the corrugated part 411 and the corrugated part 413 being joined in an upside-down state. However, in the side sill structure 5 according to the second embodiment, the collision energy absorption member may have a structure in which two or more adjacent rectangular closed cross-sectional shapes are connected via a connecting member.

[0183] Furthermore, the collision energy absorbing member 41 may have a bead formed on its surface, similar to the collision energy absorbing member 23 according to the first embodiment. This makes it possible to make the buckling strength of the collision energy absorbing member lower than the buckling strength of the floor cross member during a side collision of the vehicle.

[0184] The beads formed on the collision energy absorbing member 41 are not limited to those for reducing the buckling strength, but may be those for increasing the buckling strength.

[0185] Furthermore, in the side sill structure 5, it is preferable that the reinforcing structure 40 is formed using a metal plate having a tensile strength of 590 MPa or more, and that the tensile strength of the metal plate forming the collision energy absorption member 41 is lower than the tensile strength of the metal plate forming the first load transfer dispersion member 21.

[0186] As described in the first embodiment, it is particularly preferable that the metal plate used for the first load transmission / dispersion member 21 be a steel plate of 1180 MPa class or higher. Furthermore, it is particularly preferable that the metal plate used for the collision energy absorbing member 41 be a high-tensile steel plate with a tensile strength of 980 MPa class or higher, which is lower in strength than the first load transmission / dispersion member 21.

[0187] Furthermore, it is preferable that the second load transfer dispersion member 31 is also formed using a metal plate with a tensile strength of 590 MPa or more, and that the tensile strength of the metal plate forming the collision energy absorption member 41 is lower than the tensile strength of the metal plates forming the first load transfer dispersion member 21 and the second load transfer dispersion member 31.

[0188] By setting the tensile strength of the metal plate used in the reinforcing structure in this manner, the collision energy absorption member 41 can be caused to buckle before the first load transfer distribution member 21 and / or the second load transfer distribution member 31 deform into a V shape, thereby increasing the amount of load transmitted until the end of the collision.

[0189] In order to verify the effects of the automobile side sill structure according to the present invention, a crash test was conducted using finite element method (FEM) analysis, which will be described below.

[0190] In the collision test, a test specimen 111 shown in FIG. 23 was used to evaluate the collision energy absorption characteristics during a side collision and the maximum frontal impact load during a frontal collision. The test specimen 111 was equipped with the side sill structure according to the present invention described above and was fixed using fixing jigs (floor cross member simulation portion 113-1, floor cross member simulation portion 113-2, battery case wall portion 115, and lower battery portion) corresponding to a floor cross member and a battery case side member. The lower battery case portion was fixed to the side sill inner 11 using fixing bolts (corresponding to fixing bolts 109). The width Wa of the floor cross member simulation portion 113-1 in the vehicle longitudinal direction was 160 mm, and the width Wb of the floor cross member simulation portion 113-2 in the vehicle longitudinal direction was 200 mm.

[0191] In the collision test, as shown in Fig. 23, a collision body (pole 121) with a curvature R of 127 mm was collided perpendicularly with the longitudinal direction of the test body 111 at an initial speed of 30.9 km / h and a maximum penetration of 96 mm. The collision energy was 32 kJ.

[0192] Table 1 shows the strength level and thickness of the steel plates used for each member constituting the test specimen 111.

[0193]

[0194] Figure 19 shows the definitions of the dimensions of the first load transfer distribution member 21 and the collision energy absorption member 23. In Figure 19, W1 is the width of the first load transfer distribution member 21, WS is the width of the side sill 10, H1 is the height of the first load transfer distribution member 21, and HF is the height of the floor cross member simulation portions 113-1 and 113-2. Furthermore, W2 is the distance between adjacent collision energy absorption members 23 in the vehicle's fore-and-aft direction, and WF is the distance between the floor cross member simulation portions 113-1 and 113-2, which are adjacent in the vehicle's fore-and-aft direction.

[0195] The test specimen 111 of Example 1 of the present invention was equipped with the side sill structure 1 according to the first embodiment of the present invention, and had a first load-transmitting / dispersing member 21 and a collision energy absorbing member 23. In Example 1 of the present invention, the shapes and dimensions of the first load-transmitting / dispersing member 21 and the collision energy absorbing member 23 were W1 / WS = 0.2, H1 / HF = 0.9, and W2 / WF = 0.5, all of which were within the preferred ranges of the present invention.

[0196] The test specimen 111 of Example 2 of the invention is equipped with a side sill structure 3 relating to another aspect of embodiment 1, and in addition to a first load transfer dispersion member 21 and a collision energy absorption member 23 of the same dimensions as those of Example 1 of the invention, a second load transfer dispersion member 31 of the same dimensions as the first load transfer dispersion member 21 is provided.

[0197] The test specimen 111 of invention example 3 was equipped with a reinforcement structure 20 having a first load transmission dispersion member 21 and a collision energy absorption member 23, and W1 / WS was set to 0.4, which is outside the preferred range of the present invention.

[0198] The test specimen 111 of invention example 4 was equipped with a reinforcing structure 20 having a first load transmission dispersion member 21 and a collision energy absorption member 23, and H1 / HF was set to 0.7, which is outside the preferred range of the present invention.

[0199] The test specimen 111 of invention example 5 was equipped with a reinforcement structure 20 having a first load transmission dispersion member 21 and a collision energy absorption member 23, and W2 / WF was set to 1.0, which is outside the preferred range of the present invention.

[0200] For comparison, a test specimen 111 consisting only of the side sill inner 11 and the side sill outer 13 was used as Comparative Example 1, and a test specimen 111 in which a corrugated reinforcing member having a continuous corrugated shape in the longitudinal direction of the vehicle was provided as a reinforcing structure in the closed cross-sectional space 10a of the side sill 10 was used as Comparative Example 2. Then, similar to Invention Examples 1 to 5, collision tests were also conducted on Comparative Example 1 and Comparative Example 2.

[0201] Table 2 shows the dimensions of the test specimens for Examples 1 to 5 and Comparative Examples 1 and 2, the amount of collision energy absorption (EA) during a side collision, and the maximum value of the contact reaction force (maximum load) generated during a frontal collision.

[0202]

[0203] In terms of side collision performance, invention examples 1 and 2 were able to absorb 32 kJ of collision energy before reaching the maximum penetration of the impacting object (96 mm). Furthermore, when comparing the maximum penetration, invention example 1 was 90 mm, while invention example 2 was 80 mm, thereby reducing the penetration more than invention example 1. invention examples 3 to 5 absorbed 31.1 kJ, 31.0 kJ, and 23.9 kJ of collision energy, respectively, which was less than invention examples 1 and 2.

[0204] With regard to frontal collision performance, the maximum load for Example 1 was 967 kN, while that for Example 2 was 1,078 kN, with Example 2 being higher. Examples 3 to 5 were similar to Example 1, which is thought to be because they have the same number of ridges, which serve as paths for transmitting impact loads from the front of the vehicle to the rear. Comparative Example 1 (without reinforcing structure) was 726 kN, and Comparative Example 2 (with corrugated reinforcing member) was 716 kN, both of which were lower than Examples 1 to 5. In Comparative Example 2, the use of a corrugated reinforcing member not according to the present invention improved the amount of collision energy absorption in a side collision, but did not result in an increase in the maximum load in a frontal collision, and so frontal collision performance was not improved.

[0205] The above results demonstrate that the present invention can achieve high side collision performance and front collision performance.

[0206] According to the present invention, it is possible to provide an automobile side sill structure that can achieve high collision energy absorption characteristics with small collision deformation in the event of a side collision while suppressing weight increase, and that can achieve high deformation resistance (yield strength) in the event of a frontal collision.

[0207] DESCRIPTION OF SYMBOLS 1 Side sill structure 3 Side sill structure 3A Side sill structure 5 Side sill structure 10 Side sill 10a Closed cross-sectional space 11 Side sill inner 11a Vertical surface portion 11b Horizontal surface portion 11c Flange portion 13 Side sill outer 13a Vertical surface portion 13b Horizontal surface portion 13c Flange portion 15 Adhesive layer 17 Support part 17A Support part 17B Support part 20 Reinforcement structure 21 First load transfer dispersion member 21A First load transfer dispersion member 21a Vertical surface portion 21b Horizontal surface portion 21c Ridge portion 21c1 Ridge portion 21d Intermediate horizontal surface portion 23 Collision energy absorption member 23-1 Collision energy absorption member 23-2 Collision energy absorption member 23A Collision energy absorption member 23a Vertical surface portion 23b Horizontal surface portion 23c Ridge line portion 23d1 End portion 23d2 End portion 23e Intermediate vertical surface portion 23f Mounting flange 23g Bead 23h Bead 23i First joining flange 23j Second joining flange 23j1 Surface portion 23j2 Surface portion 231 Grooved part 231a First vertical wall portion 231b First top plate portion 231c Second vertical wall portion 231d Second top plate portion 30 Reinforcement structure 31 Second load transmitting / dispersing member 31a Vertical surface portion 31b Horizontal surface portion 31d Intermediate horizontal surface portion 31e Reinforcement member 31f Flange portion 40 Reinforcement structure 41 Collision energy absorbing member 41a Rectangular closed cross-sectional shape 41b, 41c, 41d Flange 411 Corrugated part 411a Convex shape 411b Concave shape 413 Corrugated part 413a Convex shape 413b Concave shape 100 Vehicle side structure 101 Floor panel 103 Floor cross member 103-1 Floor cross member 103-2 Floor cross member 103a End 105 Battery case 105a Battery case upper 105b Battery case lower 105c Battery case cross 105d Side 105e Bottom plate 105f Mounting flange 107 Battery pack 109 Fixing bolt 111 Test piece 113-1 Floor cross member simulation part113-2 Floor cross member simulation part 115 Battery case wall part 121 Pole

Claims

1. A side sill structure for an automobile equipped with a side sill extending in the longitudinal direction of the vehicle and having a reinforcing structure provided within a closed cross-sectional space, wherein the reinforcing structure comprises: a first load transfer dispersion member extending in the longitudinal direction of the vehicle on the outer side of the vehicle within the closed cross-sectional space, increasing the strength of the side sill and transferring a frontal impact load input to the side sill to the rear side of the vehicle and distributing a side impact load input to the side sill in the longitudinal direction of the vehicle; and a collision energy absorbing member disposed in the closed cross-sectional space on the inner side of the vehicle than the first load transfer dispersion member in the vehicle width direction, with its outer end connected to the first load transfer dispersion member, transferring the side impact load distributed by the first load transfer dispersion member to the inner side of the vehicle in the event of a side collision of the vehicle, and absorbing the collision energy by deforming when the transmitted side impact load exceeds a predetermined load.

2. The automobile side sill structure described in claim 1, wherein the first load transmission distribution member has a closed cross-sectional shape in a cross section perpendicular to the vehicle's fore-and-aft direction, or forms a closed cross-sectional shape between itself and the inner surface of the vehicle's outer side, and the collision energy absorption member has a closed cross-sectional shape in a cross-section perpendicular to the vehicle's width direction, and is provided at two or more locations spaced apart in the vehicle's fore-and-aft direction in the region in the vehicle's fore-and-aft direction where the floor cross member is installed.

3. The automobile side sill structure described in claim 1, wherein the first load transmission distribution member has a closed cross-sectional shape in a cross section perpendicular to the vehicle's fore-and-aft direction, or forms a closed cross-sectional shape between itself and the inner surface of the vehicle's outer side, and the collision energy absorption member has two or more rectangular closed cross-sectional shapes in a cross-section perpendicular to the vehicle width direction in the vehicle's fore-and-aft direction, and one member is provided so as to cover the vehicle's fore-and-aft area where the floor cross member is installed.

4. The automobile side sill structure according to claim 2 or 3, wherein the reinforcing structure further comprises a second load transfer dispersion member that extends in the vehicle longitudinal direction to the vehicle inner side within the closed cross-sectional space, increases the strength of the side sill, transfers a frontal impact load input to the side sill from the front of the vehicle to the rear side of the vehicle, and distributes the side impact load transferred from the collision energy absorbing member in the vehicle longitudinal direction in the event of a side collision of the vehicle, wherein the second load transfer dispersion member has a closed cross-sectional shape in a cross section perpendicular to the vehicle longitudinal direction, or forms a closed cross-sectional shape with the inner surface of the vehicle inner side of the side sill, and the vehicle inner side end of the collision energy absorbing member is connected to the second load transfer dispersion member.

5. A side sill structure for an automobile as set forth in claim 2 or 3, wherein the closed cross-sectional shape of the first load transfer / distribution member is one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

6. A side sill structure for an automobile as described in claim 5, wherein the rectangular closed cross-sectional shape of the first load transfer dispersion member is two rectangular closed cross-sectional shapes separated by an intermediate lateral surface portion that crosses the vehicle width direction and is connected in the vertical direction of the vehicle.

7. The automobile side sill structure described in claim 4, wherein the closed cross-sectional shapes of the first load transfer dispersion member and the second load transfer dispersion member are one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

8. A side sill structure for an automobile as described in claim 7, wherein the rectangular closed cross-sectional shapes of the first load transfer distribution member and the second load transfer distribution member are two rectangular closed cross-sectional shapes separated by an intermediate lateral surface portion that crosses the vehicle width direction and is connected in the vertical direction of the vehicle.

9. The automobile side sill structure according to claim 2, wherein the closed cross-sectional shape of the collision energy absorbing member is one or more rectangular closed cross-sectional shapes formed by a single or multiple parts.

10. The automobile side sill structure according to claim 3 or 9, wherein the collision energy absorbing member has a structure in which two or more adjacent rectangular closed cross-sectional shapes are connected via a connecting member.

11. A side sill structure for an automobile according to any one of claims 1 to 10, wherein the collision energy absorbing member has a bead formed on its surface.

12. A side sill structure for an automobile as set forth in any one of claims 2, 3, 5, 6, 9 to 11, wherein the end of the first load transfer dispersion member on the vehicle outer side is connected to the inner surface of the side sill opposite thereto, and the end of the collision energy absorption member on the vehicle inner side is connected to the inner surface of the side sill opposite thereto.

13. A side sill structure for an automobile as described in any one of claims 2, 3, 5, 6, 9 to 11, wherein the first load transfer dispersion member abuts against the inner surface of the vehicle outer side of the side sill or faces said inner surface at a predetermined distance, the collision energy absorption member abuts against the inner surface of the vehicle inner side of the side sill or faces said inner surface at a predetermined distance, and the reinforcing structure is installed within the closed cross-sectional space via a support part.

14. A side sill structure for an automobile as described in any one of claims 4, 7, and 8, wherein the vehicle outer side end of the first load transfer distribution member is connected to the inner surface of the vehicle outer side of the side sill that faces it, and the vehicle inner side end of the second load transfer distribution member is connected to the inner surface of the vehicle inner side of the side sill that faces it.

15. A side sill structure for an automobile as described in any one of claims 4, 7 and 8, wherein the first load transfer dispersion member abuts against the inner surface of the vehicle outer side of the side sill or faces said inner surface at a predetermined distance, the second load transfer dispersion member abuts against the inner surface of the vehicle inner side of the side sill or faces said inner surface at a predetermined distance, and the reinforcing structure is installed within the closed cross-sectional space via a support part.

16. A side sill structure for an automobile as described in claim 2 or 9, wherein the distance W2 between adjacent collision energy absorption members in the fore-and-aft direction of the vehicle satisfies the relationship W2≦WF with the distance WF between two adjacent floor cross members in the fore-and-aft direction of the vehicle, or W2≦254 mm.

17. A side sill structure for an automobile as set forth in any one of claims 1 to 16, wherein the width W1 of the first load transfer dispersion member satisfies the relationship W1 / WS<0.4 with the width WS of the side sill, and the height H1 of the first load transfer dispersion member satisfies the relationship H1 / HF>0.8 with the height HF of the floor cross member.

18. A side sill structure for an automobile as set forth in any one of claims 4, 7, 8, 14, and 15, wherein the width W1 of the first load transfer dispersion member and the second load transfer dispersion member satisfies the relationship W1 / WS<0.4 with the width WS of the side sill, and the height H1 of the first load transfer dispersion member satisfies the relationship H1 / HF>0.8 with the height HF of the floor cross member.

19. A side sill structure for an automobile described in any one of claims 1 to 18, wherein the reinforcing structure is formed using a metal plate having a tensile strength of 590 MPa or more, and the tensile strength of the metal plate forming the collision energy absorption member is lower than the tensile strength of the metal plate forming the first load transfer dispersion member.

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