Automobile side sill structure

Abstract

To provide a side sill structure which attains high collision energy absorption characteristics with a small collision deformation amount while inhibiting increase of the weight by structural members, can be easily assembled with a small number of work hours, and is advantageous for space saving in a vehicle body lower part.SOLUTION: An impact absorption structure 2 is disposed in a closed cross section space 3 of a side sill 1, and the impact absorption structure 2 comprises: a cross section hollow member 4 provided along a vehicle front-back direction in the closed cross section space 3 so as to partition the closed cross section space 3 into upper and lower parts; and bulk heads 6 which are provided along a vehicle width direction in a closed cross section space 5 of the cross section hollow member 4 to partition the closed cross section space 5 and provided in multiple portions set at intervals in a vehicle longitudinal direction within the closed cross section space 5. Each bulk head 6 is joined to an inner wall of the cross section hollow member 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a side sill structure for the side of an automobile body, and particularly to a side sill structure suitable for an automobile equipped with a battery module below a floor panel between both side sills. [Background technology]

[0002] Electric vehicles typically have a battery module mounted below the floor panel. The battery module consists of battery cells (battery packs) and a battery case to house them. The battery case generally protects the battery cells from impact loads and is made of highly rigid and high-strength materials. The battery case is surrounded by components that absorb energy by deforming themselves. In particular, in the case of a side collision, the side sill absorbs the impact load from the side of the vehicle, with the remaining load supported by the floor cross member or battery case side member. If the amount of deformation required to absorb the energy in the side sill is small, the energy absorption area can be reduced, allowing the volume of the battery module to be expanded, thereby increasing the vehicle's driving range. For these reasons, a lightweight side sill structure with excellent energy absorption performance is required.

[0003] As conventional techniques for increasing the rigidity of side sills and improving energy absorption performance in the event of a side collision, for example, there are the following techniques. Patent Document 1 discloses a technology for preventing the cross-section of a side sill from collapsing during a side collision by providing a bulkhead along the vehicle width direction inside the closed cross-section space of the side sill, which has a closed cross-section structure that forms the side of an automobile. A flange is formed on the outer periphery of the bulkhead, and is fixed by welding to a reinforcement inside the side sill. Furthermore, Patent Documents 2 and 3 disclose technologies for preventing the collapse of the cross-section of the side sill during a side collision, in which a closed cross-sectional space within the side sill is partitioned in the vehicle width direction by a partition member running vertically through the side sill. The combination of the bulkheads and the partition member provides multiple bulkheads along the vehicle width direction in the closed cross-sectional space within the side sill. In these technologies, the partition member is provided to prevent the side sill from opening up and down and collapsing in the cross-sectional space during a side collision. In Patent Document 2, the bulkheads are disposed only on one side of the closed cross-sectional space within the side sill, sandwiched between the partition member. In Patent Document 3, on the other hand, bulkheads are disposed on both sides of the partition member in the closed cross-sectional space within the side sill.

[0004] Furthermore, Patent Document 4 discloses a technology in which a closed cross-sectional space within a side sill is divided into two closed cross-sectional spaces in the vehicle width direction by a partition member that runs vertically through the side sill, and in which a hat-shaped impact absorbing member is placed on both sides of the partition member (inside and outside of the partition member). Furthermore, Patent Document 5 discloses a technology that suppresses localized deformation while maintaining impact absorption capacity by arranging an impact absorbing member having multiple ridges spaced apart along the width of the vehicle body in a closed cross-sectional space within the side sill and a wave-shaped member that moves up and down along the fore-and-aft direction of the vehicle body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-59218 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-202620 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-49378 [Patent Document 4] Japanese Patent Application Publication No. 2017-226353 [Patent Document 5] Japanese Patent Publication No. 2021-146973 [Patent Document 6] Japanese Patent Publication No. 2023-78067 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology disclosed in Patent Document 1 has a bulkhead structure that is prone to buckling, which causes the bulkhead to easily buckle during a side collision, and once the bulkhead buckling begins, the cross-section of the side sill collapses, resulting in an inability to achieve adequate collision energy absorption. Furthermore, in a side sill having a partition member, as in the technologies disclosed in Patent Documents 2 and 3, when a bulkhead is disposed in a closed cross-sectional space within the side sill, sufficient collision energy absorption characteristics cannot be obtained. In particular, in the technology disclosed in Patent Document 2, the bulkhead is disposed only in one of the closed cross-sectional spaces sandwiching the partition member, so it only has the function of maintaining the cross-sectional shape of that one closed cross-sectional space, and therefore sufficient collision energy absorption characteristics cannot be obtained. Furthermore, even when bulkheads are disposed in both spaces sandwiching the partition member, as in the technology disclosed in Patent Document 3, the obtained collision energy absorption characteristics are insufficient.

[0007] Furthermore, the technology disclosed in Patent Document 3 requires the creation of slits in the partition member to allow the insertion of the bulkhead. When multiple bulkheads are installed along the length of the side sill, the spacing between the bulkheads cannot be long to avoid a decrease in the strength of the partition member due to the slits. This increases the number of bulkheads installed, which leads to an increase in weight. Furthermore, in a side sill having a partition member, as in the technology disclosed in Patent Document 4, simply placing a hat-shaped cross-section impact absorbing member on both sides of the partition member (inside and outside of the partition member) does not provide sufficient collision energy absorption characteristics. Furthermore, the technology disclosed in Patent Document 5 can distribute and transmit the impact load during a side collision uniformly across a cross section perpendicular to the vehicle width direction, thereby achieving high collision energy absorption characteristics. However, with a reinforcing member inside the side sill that has a constant cross section in the longitudinal direction of the vehicle, there is a possibility that the weight will be excessive because the reinforcing member is present in areas that do not need reinforcement.

[0008] In contrast to the above-mentioned conventional technology, Patent Document 6 discloses a technology for providing a shock absorbing structure of a specific structure within a closed cross-sectional space in a side sill using a partition member that runs vertically through the closed cross-sectional space. This shock absorbing structure is composed of a pair of grooved cross-sectional members joined to each other on both sides of the partition member, and multiple bulkheads that are provided under predetermined conditions within the two closed cross-sectional spaces formed between the grooved cross-sectional members and the partition member. This technology allows for a side sill structure that achieves high collision energy absorption characteristics with minimal collision deformation. Furthermore, because the impact absorption structure achieves high bending rigidity with fewer components, it also helps to limit the increase in vehicle weight due to the components. However, it has also been found that this side sill structure has the following drawbacks:

[0009] The bulkhead on the outer side of the vehicle and the bulkhead on the inner side of the vehicle are located opposite each other in the width direction of the vehicle, with a partition member in between. The positions of the two bulkheads must be precisely aligned, requiring strict assembly precision. This is because even slight misalignment between the two bulkheads in the fore-and-aft direction of the vehicle during assembly can reduce the amount of load transmission and prevent the desired collision energy absorption characteristics from being achieved. This makes assembly time-consuming, and coupled with the increased number of assembly steps, increases manufacturing costs. Furthermore, because the impact absorbing structure is constructed by joining a pair of grooved cross-section members that sandwich a partition member from both sides, there are restrictions on the shape of the partition member, which can sometimes hinder vehicle weight reduction. For example, while holes can be drilled in the partition member to reduce weight if the tensile load can be guaranteed, there are cases where holes cannot be drilled due to the need to join the grooved cross-section members, which restricts vehicle weight reduction. In addition, since a pair of cross-sectional groove-shaped members are joined to the partition member via flanges, it is necessary to leave a gap (space) in the vertical direction equal to the width of the flanges. This may result in a reduction in the design freedom of the impact absorption structure, such as shortening the vertical dimension of the vehicle body or restricting its vertical position within the side sill.

[0010] Therefore, an object of the present invention is to solve the problems of the conventional technology as described above, and to provide a side sill structure that can achieve high collision energy absorption characteristics with a small amount of collision deformation while suppressing weight increase due to structural members, is easy to assemble with a small number of assembly steps, and is also advantageous in increasing the design freedom of the impact absorbing structure. [Means for solving the problem]

[0011] As a result of extensive research into solving the above-mentioned problems, the inventors have found that the problems can be solved by providing an impact absorbing structure with a specific structure within the closed cross-sectional space of the side sill without the need for a partition member (a member sandwiched between the side sill outer and side sill inner to divide the closed cross-sectional space of the side sill into an outer side and an inner side; the same applies below). Specifically, the inventors have found that providing an impact absorbing structure with an integrated structure consisting of a hollow cross-sectional member provided along the vehicle longitudinal direction to divide the closed cross-sectional space of the side sill into upper and lower parts, and multiple bulkheads installed under predetermined conditions within the closed cross-sectional space of this hollow cross-sectional member, which are joined together, can achieve high energy absorption performance while suppressing the weight increase due to the structural members, and also solves the problems of the prior art (particularly Patent Document 6) described above. The present invention was made based on these findings and has the following gist.

[0012] [1] A side sill structure comprising a side sill (1) extending along the vehicle longitudinal direction on both sides of the lower part of a vehicle, and an impact absorbing structure (2) disposed in a closed cross-sectional space (3) within the side sill (1), The shock absorbing structure (2) is The interior forms a closed cross-section space (5), and a hollow cross-section member (4) is provided along the longitudinal direction of the vehicle within the closed cross-section space (3) so as to partition the closed cross-section space (3) vertically. A member that partitions the closed cross-section space (5) by being provided along the vehicle width direction within the closed cross-section space (5) of the hollow cross-section member (4), and is composed of bulkheads (6) provided at a plurality of locations spaced apart in the vehicle longitudinal direction within the closed cross-section space (5). Each bulkhead (6) is joined to the inner wall of the hollow cross-section member (4), and this is the side sill structure of an automobile. [2] In the side sill structure of [1] above, the bulkhead (6) is joined to at least the inner wall of the longitudinal side surface portion (40) on the inner side of the vehicle and the inner wall of the upper lateral surface portion (41A) or / and the lower lateral surface portion (41B) among the inner walls of the hollow cross-section member (4), and this is the side sill structure of an automobile.

[0013] [3] In the side sill structure of [1] or [2] above, the bulkhead (6) is a bulkhead (6 x ) provided in a region within the width of the floor cross member in the vehicle longitudinal direction, and a bulkhead (6 y ) provided in a region outside the width of the floor cross member, and in the vehicle longitudinal direction, two or more bulkheads (6 x ) are provided in two or more locations in the region within the width of the floor cross member, and one or more bulkheads (6 y ) are provided in one or more locations in the region outside the width of the floor cross member, when the interval between two adjacent bulkheads (6 x ) is w1, and the interval between the bulkhead (6 x ) and the adjacent bulkhead (6 y ) is w2, w1 < w2, and this is the side sill structure of an automobile. [4] In the side sill structure of [3] above, at least some of the bulkheads (6 y ) are composed of a bulkhead set composed of two or more adjacent bulkheads, and this is the side sill structure of an automobile.

[0014] [5] A side sill structure for an automobile, characterized in that in the side sill structure of any one of the above [1] to [4], the vertical surface portion (40) of the cross-sectional hollow member (4) and the opposing vertical surface portion (100) of the side sill (1) are joined. [6] In the side sill structure according to any one of the above [1] to [4], the vertical surface portion (40) of the hollow cross-section member (4) and the opposing vertical surface portion (100) of the side sill (1) are in contact with each other or face each other with a predetermined gap therebetween, A side sill structure for an automobile, characterized in that a hollow cross-section member (4) is supported on a side sill (1) via a support member (15). [7] A side sill structure for an automobile, characterized in that in the side sill structure of any of the above [1] to [6], beads are formed on the lateral surface portion (41) of the cross-sectional hollow member (4) and / or on the bulkhead (6). [8] A side sill structure for an automobile according to any one of the above [1] to [7], characterized in that the tensile strength of the metal plate constituting the impact absorbing structure (2) is 590 MPa or higher. [Effects of the Invention]

[0015] The side sill structure of the present invention provides high collision energy absorption characteristics with minimal collision deformation by providing an impact absorption structure 2 with a specific structure within the closed cross-sectional space 3 of the side sill 1. Therefore, when applied to a vehicle equipped with a battery module between both side sills, such as an electric vehicle, the space required for energy absorption can be reduced, offering the advantage of allowing for increased battery module volume. Furthermore, the impact absorption structure 2 is provided within the closed cross-sectional space of the side sill without the need for a partition member, achieving high bending rigidity with a minimum number of components, thereby minimizing the increase in vehicle weight due to the components of the side sill structure, including the impact absorption structure 2. Furthermore, the impact absorption structure 2 is provided within the closed cross-sectional space 3 of the side sill 1 without the need for any partition members, and each bulkhead 6 provided within the hollow cross-sectional member 4 is a single member that is integrated in the vehicle width direction, ensuring reliable load transmission in the vehicle width direction and appropriately achieving the desired collision energy absorption characteristics. Furthermore, because the bulkhead 6 is a single member that is integrated in the vehicle width direction, there is the advantage that assembly of the impact absorption structure 2 is easy and requires fewer assembly steps. Furthermore, because the hollow cross-sectional member 4 is installed without a partition member, there is no need to provide upper and lower flanges for joining to the partition member. This eliminates the need to provide gaps (spaces) above and below the hollow cross-sectional member 4 for the flanges, which has the advantage of increasing the degree of freedom in designing the impact absorption structure 2. This makes it possible to increase the vertical dimension of the impact absorption structure 2 on the vehicle body and reduce vertical positional constraints within the side sill 1. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a longitudinal cross-sectional view of a side sill in a vehicle width direction, schematically illustrating one embodiment of a side sill structure of the present invention. [Figure 2] Cross-sectional view along line II-II in Figure 1 [Figure 3] FIG. 2 is a longitudinal cross-sectional view of a vehicle body side portion including a side sill in the vehicle width direction in the embodiment of FIG. [Figure 4] FIG. 1 is a parts exploded view of an embodiment of the side sill structure of the present invention. [Figure 5] An explanatory diagram showing the floor panel, floor cross member, and battery case arranged between both side sills of a vehicle body in an exploded view. [Figure 6] FIG. 10 is an explanatory diagram showing another example of the arrangement of the bulkhead in the side sill structure of the present invention. [Figure 7] FIG. 10 is an explanatory diagram showing another example of the arrangement of the bulkhead in the side sill structure of the present invention. [Figure 8] A drawing for explaining the width wa of the floor cross member in the present invention. [Figure 9]FIG. 2 is a diagram for explaining the width We of the impact absorbing structure in the vehicle width direction and the width Ws of the side sill in relation to the embodiment of FIG. 1 (a cross-sectional view of the side sill). [Figure 10] 1 is a longitudinal cross-sectional view of a side sill in a vehicle width direction, schematically illustrating another embodiment of the side sill structure of the present invention. [Figure 11] FIG. 1 is an explanatory diagram showing an example of a support structure for the impact absorbing structure in the side sill structure of the present invention. [Figure 12] 1 is a longitudinal cross-sectional view of a side sill in a vehicle width direction, schematically illustrating another embodiment of the side sill structure of the present invention. [Figure 13] FIG. 1 is an explanatory diagram showing an example of the structure of a hollow cross-section member that constitutes a shock absorbing structure in the side sill structure of the present invention. [Figure 14] FIG. 1 is an explanatory diagram showing the deformation of the side sill structure of the present invention in a horizontal cross section in a stepwise manner during a side pole collision. [Figure 15] Graph showing the relationship between the penetration amount of the impact body (pole) and the absorbed energy when the side sill structure of the present invention is deformed in a side pole collision. [Figure 16] FIG. 1 is an explanatory diagram showing the side sill structures of the invention example and comparative example and the test conditions in the collision test of the example. [Figure 17-1] Graph showing the relationship between the penetration amount of the impact body (punch) and the punch reaction force and absorbed energy in the impact test of the example (example of the invention) [Figure 17-2] Graph showing the relationship between the penetration amount of the impact body (punch) and the punch reaction force and absorbed energy in the impact test of the example (comparative example) [Figure 18] Graph showing the absorbed energy at maximum penetration of the impact body (punch) in impact tests of Examples (invention examples and comparative examples) DETAILED DESCRIPTION OF THE INVENTION

[0017] Figures 1 to 3 are schematic diagrams showing an embodiment of the side sill structure of the present invention, with Figure 1 being a longitudinal cross-sectional view in the vehicle width direction of the side sill structure, Figure 2 being a cross-sectional view taken along line II-II in Figure 1, and Figure 3 being a longitudinal cross-sectional view in the vehicle width direction of a vehicle body side structure including a side sill. Also, Figure 4 is an exploded view of parts of an embodiment of the side sill structure of the present invention, and Figure 5 is an explanatory view showing an exploded view of a floor panel, floor cross member, and battery case arranged between both side sills. The side sill structure of the present invention will be described below using the embodiment shown in FIGS. 1 to 3 as an example.

[0018] <Basic structure of side sill and surrounding area> The side sill 1 is constructed by joining a side sill outer 1a and a side sill inner 1b, each having a groove-shaped cross section, and a closed cross-sectional space 3 is formed within the side sill 1. Details of this side sill structure will be described later. Here, an automobile underbody structure including side sills will be described with reference to FIG. 3. The side sills 1 are skeletal structural members disposed on both sides of the lower part of the vehicle body. A floor panel 7 is disposed between the two side sills 1, and this floor panel 7 is joined to both side sills 1 (in FIG. 3, the upper parts of the vertical surface portions 100 of the side sill inner panels 1b) via their respective flange portions 70. Furthermore, a floor cross member 8, which is a skeletal structural member extending along the width direction of the vehicle, is disposed on the floor panel 7, and both ends of the floor cross member 8 are joined to both side sills 1 (in FIG. 3, the upper parts of the vertical surface portions 100 of the side sill inner panels 1b) via the floor panel 7 (flange portions 70). The floor cross member 8 is provided at multiple locations spaced at predetermined intervals (for example, approximately 300 mm) in the fore-and-aft direction of the vehicle. The joining of the floor panel 7 or floor cross member 8 to the side sills 1 is typically performed by spot welding.

[0019] A battery case 9 containing a battery pack 10 is disposed below the floor panel 7. The side of the battery case 9 (battery case side member 90) faces the lower part of the side sill 1 (the lower part of the vertical surface 100 of the side sill inner panel 1b) at a predetermined distance. A mounting flange 92 is connected to the bottom of the battery case 9 (battery case bottom plate 91) so as to protrude toward the side sill. The battery case 9 is held to the side sill 1 by fastening the mounting flange 92 to the lower end of the side sill 1 (the lower horizontal surface 101B of the side sill inner panel 1b) with fixing bolts 11. With this structure, the load input to the side sill 1 during a side collision is input to both the floor cross member 8 and the battery case 9, allowing the load to be borne over a wide area. Furthermore, the load during a side collision is input to the floor cross member 8 before the battery case 9, thereby reducing the load input to the battery case 9.

[0020] The side sill outer 1a and side sill inner 1b that make up the side sill 1 are formed by molding metal plates. These members 1a and 1b each have a main body portion with a groove-shaped cross section, consisting of a vertical surface portion 100 and horizontal surface portions 101A and 101B connected to the upper and lower ends thereof, and flange portions 102 connected to both ends (the ends of the horizontal surface portions 101A and 101B). The vertical surface portion 100 does not have to be vertical and may have an appropriate inclination or curved surface. The horizontal surface portions 101A and 101B do not have to be horizontal and may have an appropriate inclination or curved surface. The side sill outer 1a and the side sill inner 1b are joined (usually by spot welding) with their flange portions 102 overlapping each other to form the side sill 1 which defines a closed cross-sectional space 3 therein.

[0021] <Impact absorption structure 2 provided in the side sill structure> The side sill structure described above is characterized in that the present invention provides an impact absorption structure 2 with a specific structure within the closed cross-sectional space 3 within the side sill 1. Specifically, the impact absorption structure 2 is provided within the closed cross-sectional space 3 of the side sill 1. The impact absorption structure 2 is comprised of a hollow cross-sectional member 4 arranged along the vehicle longitudinal direction to divide the closed cross-sectional space 3 into upper and lower sections, and multiple bulkheads 6 with a specific structure and arrangement that are provided within the closed cross-sectional space 5 of the hollow cross-sectional member 4, and is structurally integrated into the closed cross-sectional space 5. This allows for a side sill structure that achieves high impact energy absorption characteristics with minimal impact deformation. Furthermore, the impact absorption structure 2 is provided within the closed cross-sectional space 3 of the side sill 1 without the need for a partition member, achieving high bending rigidity with the minimum number of components required (especially the minimum number of bulkheads). This also minimizes the increase in vehicle weight due to the components of the side sill structure, including the impact absorption structure 2. The impact absorbing structure 2 is provided at least in a portion of the side sill along the battery case side member 90 in the vehicle longitudinal direction.

[0022] The hollow cross-section member 4 defines a closed cross-section space 5 therein, and is provided in the closed cross-section space 3 of the side sill 1 along the vehicle longitudinal direction (side sill longitudinal direction) so as to separate the closed cross-section space 3 into upper and lower sections. The hollow cross-section member 4 of this embodiment is composed of a groove-shaped cross-section member 4a that opens (opens) downward, and a plate-shaped cover member 4b that closes the downward opening (open portion) of the groove-shaped cross-section member 4a. The members that make up the hollow cross-section member 4 (the groove-shaped cross-section member 4a and the cover member 4b) are formed by bending a metal plate. Joining flanges 42 are formed on both widthwise ends of the cover member 4b. The cover member 4b is fitted into the opening of the grooved cross-section member 4a so that both flanges 42 are in close contact with the inside of the opening of the grooved cross-section member 4a (i.e., the inside of the tips of both flanges of the grooved cross-section member 4a), and both flanges 42 are joined to the grooved cross-section member 4a. This joining is usually achieved by spot welding. However, the flanges 42 may be formed only on a portion of the length of the cover member 4b (for example, formed intermittently at predetermined intervals).

[0023] The hollow cross-section member 4 configured as described above is a member having a substantially horizontally elongated rectangular cross section in the vehicle width direction, which is made up of upper and lower horizontal surface portions 41A, 41B and both vehicle outer-side and vehicle inner-side vertical surface portions 40, and the interior thereof defines a closed cross-sectional space 5. That is, in this substantially horizontally elongated rectangular cross-section member, the upper and lower horizontal surface portions 41A, 41B are the upper surface and the lower surface, respectively, and the both vehicle outer-side and vehicle inner-side vertical surface portions 40 are the side surface portions. Here, because the hollow cross-section member 4 has a substantially horizontally elongated rectangular cross section in the vehicle width direction as described above, the load during a side collision is efficiently transmitted to the floor cross member 8 and the battery case 9. The hollow cross-section member 4 is disposed at a heightwise intermediate position within the closed cross-section space 3 of the side sill 1 so as to separate the closed cross-section space 3 into upper and lower sections. As shown in FIG. 3, the hollow cross-section member 4 is preferably disposed so that the heightwise position of the vertical surface portion 40 of the hollow cross-section member 4 overlaps with at least one (preferably both) of the floor cross-member 8 and the battery case 9. In this case, it is preferable to adjust the heightwise overlap between the vertical surface portion 40 and the floor cross-member 8 and the battery case 9 so that the load input to the floor cross-member 8 and the battery case 9 is appropriately balanced. In addition, it is preferable to adjust the distance (space) between the upper and lower horizontal surface portions 41A, 41B of the hollow cross-section member 4 and the side sill (the upper and lower horizontal surface portions 101A, 101B of the side sill outer 1a and the side sill inner 1b) from the same perspective.

[0024] In this embodiment, both vertical surface portions 40 of the hollow cross-section member 4 and both vertical surface portions 100 of the opposing side sill 1 face each other with a predetermined gap between them, and therefore the hollow cross-section member 4 is supported on the side sill 1 by a separately installed support member (not shown). This structure will be described in detail later. The hollow cross-section member 4 has a vertical surface 40 on the vehicle outer side that forms a pressure-receiving surface that receives a side impact load, and upper and lower horizontal surfaces 41A, 41B that form energy-absorbing surfaces that deform due to the side impact load and absorb collision energy. Here, because the hollow cross-sectional member 4 is installed without a partition member, there is no need to provide upper and lower flanges for joining to the partition member. This eliminates the need to provide gaps (spaces) above and below the hollow cross-sectional member 4 for the flanges, which offers advantages such as increasing the vertical dimension of the impact absorption structure 2 and reducing vertical positional constraints within the side sill 1.

[0025] The bulkheads 6 are members that divide the closed cross-sectional space 5 by being provided along the vehicle width direction within the closed cross-sectional space 5 of the hollow cross-sectional member 4, and are provided at multiple locations spaced apart in the vehicle front-rear direction within the closed cross-sectional space 5. The bulkheads 6 are preferably provided so as to divide the entire cross section of the closed cross-sectional space 5 in the vehicle width direction. The bulkhead 6 prevents the cross-sectional collapse of the hollow cross-section member 4, and absorbs collision energy by buckling and undergoing bending crushing itself. In the impact absorption structure 2 of the present invention, the bulkhead 6, which is provided along the vehicle width direction within the closed cross-sectional space 5, is a single member that is integrated in the vehicle width direction, so load transmission in the vehicle width direction is ensured and the desired collision energy absorption characteristics are obtained. Furthermore, because the bulkhead 6 is a single member that is integrated in the vehicle width direction, there are advantages in that the impact absorption structure 2 is easy to assemble and requires fewer assembly steps.

[0026] Each bulkhead 6 is formed by forming a metal plate, and its outer peripheral edge is joined to the inner wall of the hollow cross-sectional member 4 (the peripheral wall of the closed cross-sectional space 5). Here, each bulkhead 6 is preferably joined to at least the inner wall of the vehicle-inner-side vertical surface 40, which is significantly deformed by a side collision load, and at least one of the inner walls of the upper horizontal surface 41A and the lower horizontal surface 41B, among the inner walls of the hollow cross-sectional member 4 that form the closed cross-sectional space 5. In this case, it is more preferable that the bulkhead 6 be joined to the inner walls of both the upper horizontal surface 41A and the lower horizontal surface 41B. Furthermore, the bulkhead 6 may also be joined to the vehicle-outer-side vertical surface 40, so that it is joined to all four inner walls of the hollow cross-sectional member 4. In this embodiment, a flange portion 61 is formed on the outer peripheral edge of the main body (partition portion) of the bulkhead 6 (see FIG. 4), and the bulkhead 6 is joined to the inner wall of the hollow cross-section member 4 via this flange portion 61. This joining is usually performed by spot welding. Note that the flange portion 61 may be formed only on a part of the outer peripheral edge of the main body (partition portion) that is joined to the inner wall of the hollow cross-section member 4. The bulkheads 6 may be provided at equal intervals in the fore-and-aft direction of the vehicle within the closed cross-sectional space 5, or may be provided so that wide intervals and narrow intervals alternate as shown in Figure 2, or may be provided at different intervals in different regions in the fore-and-aft direction of the vehicle, as will be described later.

[0027] As described above, the impact absorption structure 2 is comprised of a hollow cross-sectional member 4 arranged in the closed cross-sectional space 3 of the side sill 1 along the vehicle longitudinal direction so as to divide the closed cross-sectional space 3 into upper and lower sections, and a plurality of bulkheads 6 of a specific structure and arrangement arranged in the closed cross-sectional space 5 of this hollow cross-sectional member 4, with these being an integrated structure. In other words, the hollow cross-sectional member 4 contains the bulkheads 6 of a specific structure that are arranged at intervals in the vehicle longitudinal direction, forming an integrated structure. This results in high impact energy absorption characteristics as described below.

[0028] The yield strength of the metal plates constituting the impact absorption structure 2 (the hollow cross-section member 4 and the bulkhead 6) is preferably equal to or lower than the yield strength of the metal plates constituting the floor cross-member 8. This is to ensure that, in the event of a side collision, the impact absorption structure 2 deforms before the floor cross-member 8 to absorb the impact energy, thereby minimizing deformation of the floor cross-member 8. For this reason, if the yield strength of the metal plates of the impact absorption structure 2 is equivalent to that of the metal plates of the floor cross-member 8, it is preferable to provide a crash bead in part of the impact absorption structure 2 so that its buckling strength (the load at which the member itself begins to buckle; the same applies below) is lower than that of the floor cross-member 8. Specifically, it is preferable to provide a bead 60 (crash bead) or the like, as shown in FIG. 12(A) described later, on the lateral surface portions 41 (41A, 41B) of the bulkhead 6 and / or hollow cross-section member 4 constituting the impact absorption structure 2.

[0029] Furthermore, the metal plates used for the impact absorption structure 2 (hollow cross-section member 4 and bulkhead 6) preferably have a tensile strength of 590 MPa or higher. In terms of the collision characteristics of the impact absorption structure 2, the higher the load at which the impact absorption structure 2 changes from elastic deformation immediately after deformation starts to plastic deformation during a side collision (hereinafter referred to as "yield strength"), the less likely it is to deform during a collision, and the better the collision characteristics. Since the higher the tensile strength of the metal plates used for the impact absorption structure 2, the higher the yield strength, so it is preferable to use metal plates of 590 MPa or higher, which have a tensile strength higher than that of ordinary steel. Furthermore, if high-tensile steel plates are used as the metal plates (material) used for the impact absorption structure 2, the impact absorption structure 2 disposed inside the side sill 1 also functions as a reinforcement for the side sill. Therefore, it is particularly preferable that the metal plates used for the impact absorption structure 2 be high-tensile steel plates of 1180 MPa class or higher.

[0030] <Functions and effects of impact absorption structure 2> The impact absorption structure 2 provided in the side sill structure of the present invention has a structure in which a hollow cross-section member 4 is provided under predetermined conditions within the closed cross-sectional space 3 of the side sill 1, and multiple bulkheads 6 are provided under predetermined conditions within the closed cross-sectional space 5 of this hollow cross-section member 4, integrated together. In other words, the hollow cross-section member 4 contains the bulkheads 6, which are arranged at intervals in the vehicle's fore-and-aft direction, and these are integrated into a structure. Due to this structure, the entire impact absorption structure 2 has high bending rigidity (resistance to bending deformation against a side collision load). This suppresses local deformation around the input point of the side collision load, and by deforming the entire impact absorption structure 2 during a side collision, collision energy absorption (EA) can be improved.

[0031] During a side collision, the vertical surface 40 (pressure-receiving surface) on the vehicle outer side of the hollow cross-section member 4 receives the collision load through the side sill outer panel 1a, and the upper and lower horizontal surfaces 41A, 41B (energy-absorbing surfaces) bend and collapse, absorbing the collision energy. At this time, the bulkhead 6 integrated with the hollow cross-section member 4 prevents the cross-section of the hollow cross-section member 4 from collapsing, and the bulkhead 6 itself buckles (axially collapses) to absorb the collision energy. In this case, because the bulkhead 6, which is provided along the vehicle width direction within the closed cross-section space 5, is a single member integrated in the vehicle width direction, load is reliably transmitted in the vehicle width direction, and the impact absorption structure 2 collapses under reaction forces from the floor cross-member 8 and the battery case 9, thereby achieving the desired collision energy absorption characteristics.

[0032] <Another embodiment of the shock absorbing structure 2> FIG. 6 shows another example of the arrangement of the bulkheads 6 in the longitudinal direction of the vehicle, in which the bulkheads 6 are provided at different intervals in different regions in the longitudinal direction of the vehicle. The bulkheads 6 in these arrangements are provided in an area within the width wa of the floor cross member 8 in the vehicle longitudinal direction. x and bulkhead 6 provided in the other area (area outside the width of floor cross member 8). yIt consists of. And in the longitudinal direction of the vehicle, the bulkhead 6 is provided at two or more locations (two locations in the embodiment of FIG. 6) within the width wa of the floor cross member 8 x and the bulkhead 6 is provided at one or more locations outside the width of the floor cross member 8 y is provided. Further, when the distance between two adjacent bulkheads 6 x is w1 and the distance between this bulkhead 6 x and the adjacent bulkhead 6 y is w2, w1 < w2. Such an arrangement form of the bulkhead 6 is for the following reasons. That is, within the region within the width wa of the floor cross member 8, the bulkhead 6 is provided at two or more locations x to reduce the distance between the bulkheads 6 x to improve the collision characteristics. On the other hand, by increasing the distance between the bulkheads 6 in other regions y and the bulkhead 6 x the number of installed bulkheads 6 is suppressed and weight reduction is achieved. In addition, when the bulkhead 6 is provided at two or more locations outside the width of the floor cross member 8 y it is preferable that w1 < w3 for the distance w3 between two adjacent bulkheads 6 y as well.

[0033] Here, the width wa of the floor cross member 8 may be the width of the portion between the two side walls in the width direction of the floor cross member. FIG. 8 schematically shows a cross section in the width direction of a general floor cross member 8, which has flange portions at both edges. In this case, the width wa of the floor cross member 8 may be the width of the portion excluding the flange portions at both edges in the width direction of the floor cross member (the width of the main portion functioning as a skeletal member), that is, the width between the locations where the R of the flange portion starts. When arranging the bulkhead 6 at a plurality of locations within the width wa of the floor cross member 4 x the distance between two adjacent bulkheads 6 xIf the distance w1 between the throats is too small, the effect of enhancing the collision characteristics within the width wa of the floor cross member 8 is reduced. Also, the number of installations of the bulkhead 6 x tends to increase unnecessarily. Therefore, the bulkhead 6 x is preferably arranged such that the ratio w1 / wa of the distance w1 to the width wa of the floor cross member 4 is 0.4 or more and 1.0 or less.

[0034] On the other hand, the distance w2 between adjacent bulkheads 6 x and the bulkhead 6 y and the distance w3 between the bulkheads 6 y are preferably set to 254 mm or less in order to ensure the bending rigidity of the shock absorbing structure 2 during a side collision. This 254 mm is the diameter of the collision body (pole) used in the side collision test (side pole collision test defined by Euro NCAP). By setting the distances w2 and w3 to be less than or equal to the diameter of the collision body (pole) of this test, the bending rigidity of the shock absorbing structure 2 during a side collision can be more appropriately ensured. Also, from the same viewpoint, the distance w2 between adjacent bulkheads 6 x and the bulkhead 6 y and the distance w3 between the bulkheads 6 y are preferably set to about 1 / 4 to 1 / 2 of the installation interval of the floor cross member 8 (the distance wb between adjacent floor cross members 8).

[0035] The arrangement form in Fig. 6(a) is an example in which a bulkhead 6 y is provided at one location in the region outside the width of the floor cross member 8 between adjacent floor cross members 8, and the bulkheads 6 x , 6 y are provided under the condition that w1 < w2 is satisfied. Also, the arrangement forms in Fig. 6(b) and (c) are examples in which a bulkhead 6 y is provided at two to three locations in the region outside the width of the floor cross member 8 between adjacent floor cross members 8, and the bulkheads 6 x , 6 y are provided under the condition that w1 < w2 and w1 < w3 are satisfied.

[0036] FIG. 7 shows another example of the arrangement of the bulkhead 6 in the vehicle longitudinal direction. In this arrangement, similar to the embodiment of FIG. 6, the bulkhead 6 is provided at different intervals for each region in the vehicle longitudinal direction. However, in order to increase the bending rigidity of the shock absorber structure 2 between the floor cross members 8, the method of providing the bulkhead 6 y is different. That is, the bulkhead 6 y provided in the region outside the width of the floor cross member 8 is constituted by a bulkhead set composed of two or more adjacent bulkheads (two bulkheads in the embodiment of FIG. 7). Therefore, each bulkhead 6 in the embodiment of FIG. 7 y is constituted by a bulkhead set with two bulkheads as one set. The size of the interval w4 between the bulkheads constituting this bulkhead set is arbitrary, but basically it will be determined from a viewpoint similar to the interval w1, so the same conditions as the above-mentioned interval w1 may be set. Note that configuring the bulkhead 6 y with a bulkhead set composed of two or more bulkheads may be applicable to all the bulkheads 6 y [[ID=!2]]or only to some of the bulkheads 6 y [[ID=!4]].

[0037] The arrangement in FIG. 7(A) is an example in which a bulkhead 6 y (a bulkhead set with two bulkheads as one set) is provided at one location in the region outside the width of the floor cross member 8 between adjacent floor cross members 8. The bulkhead 6 x , 6 y is provided under the condition that w1 < w2 is satisfied. Also, the arrangements in FIGS. 7(B) and 7(C) are examples in which a bulkhead 6 y (a bulkhead set with two bulkheads as one set) is provided at two to three locations in the region outside the width of the floor cross member 8 between adjacent floor cross members 8. The bulkhead 6 x , 6 y is provided under the conditions that w1 < w2 and w1 < w3 are satisfied.

[0038] In the side sill structure of the present invention, the shock absorbing structure 2 (hollow cross-section member 4) may have an appropriate gap (space) between it and the side sill outer 1a and side sill inner 1b (their respective vertical surface portions 100) as shown in Fig. 1 (Mode 1). On the other hand, the shock absorbing structure 2 (hollow cross-section member 4) may be in contact with or joined to the inner surfaces of the side sill outer 1a and side sill inner 1b (their respective vertical surface portions 100) mainly to prevent vibration (Mode 2). In the above-described first embodiment, if the gap between the impact absorption structure 2 (hollow cross-section member 4) and the side sill outer 1a and side sill inner 1b is too narrow, the two components may come into contact due to vibrations during driving, resulting in noise and further vibration problems. Therefore, it is preferable to have the two components facing each other with a gap that prevents them from coming into contact due to vibrations during driving. On the other hand, since impact absorption performance is improved by ensuring that side impact loads are transmitted to the floor cross member from the early stage of a collision, the closer the width of the impact absorption structure 2 is to the overall width of the side sill, the higher the impact absorption performance becomes. For this reason, the width We of the impact absorption structure 2 (hollow cross-section member 4) in the vehicle width direction is preferably at least 60% of the width Ws of the side sill 1 (the distance between the vertical surface portions 100 of the side sill outer 1a and side sill inner 1b). Figure 9 shows the width We of the impact absorption structure 2 and the width Ws of the side sill 1. Here, if the width We of the impact absorption structure 2 and the width Ws of the side sill 1 vary depending on the position in the vehicle height direction, Ws and We are defined as the widths at the widest height positions.

[0039] Various embodiments can also be employed in the case of the above-mentioned second embodiment. Fig. 10 is a schematic diagram of the embodiment, showing a longitudinal cross section of the side sill in the vehicle width direction. Fig. 10(A) shows an example in which the vertical surface portions 40 of the hollow cross-sectional member 4 are joined by welding (usually spot welding) to the inner surfaces of the vertical surface portions 100 of the side sill outer panel 1a and the side sill inner panel 1b (in the figure, reference numeral 12 denotes the joint portion). Note that in the embodiment shown in Fig. 10(A), the vertical surface portions 40 may simply be in contact with the vertical surface portions 100 rather than being joined thereto. 10(A) shows an example in which the vertical surface portions 40 of the hollow cross-section member 4 are bonded to the inner surfaces of the vertical surface portions 100 of the side sill outer panel 1a and the side sill inner panel 1b with adhesive 13 (adhesive layer). When bonding with adhesive 13 in this way, the adhesive may be applied to only a portion of the bonding surface. This adhesive 13 (adhesive layer) may also function as a vibration-damping member that attenuates vibration.

[0040] As shown in Figure 1, when the shock absorbing structure 2 (cross-sectional hollow member 4) is not joined to the side sill outer 1a and the side sill inner 1b (their respective vertical surface portions 100), the shock absorbing structure 2 is supported on the side sill 1 by a separately provided support member. 11(a) to 11(c) are explanatory diagrams showing examples of the support structure of the shock absorbing structure 2 (hollow cross-section member 4) using such a support member 15. In FIG. 11(A) shows an example in which a support member 15 made of an L-shaped angle member (a member with a mountain-shaped cross section) is used. The L-shaped angle member constituting the support member 15 has its wide side portion 150 sandwiched at its widthwise end between the lower flanges 102 of the side sill outer member 1a and the side sill inner member 1b and joined to the side sill 1. The narrow side portion 151 of the L-shaped angle member abuts against and is joined to the lower lateral surface portion 41B of the hollow cross section member 4, so that the shock absorbing structure 2 (hollow cross section member 4) is supported by the side sill 1 via the support member 15. 11(A) shows an example in which a support member 15 made of a grooved cross-section member is used. One inclined surface portion 152 of the grooved cross-section member constituting the support member 15 abuts against and is joined to the inner surface of the lower part of the side sill outer panel 1a. The other inclined surface portion 152 of the grooved cross-section member abuts against and is joined to the lower lateral surface portion 41B of the hollow cross-section member 4, so that the impact absorbing structure 2 (hollow cross-section member 4) is supported on the side sill 1 via the support member 15.

[0041] 11(C) shows an example in which the shock absorbing structure 2 (hollow cross-section member 4) is supported by two support members 15A, 15B sandwiching it from above and below, using the same support member 15 made of an L-shaped angle bar as in FIG. 11(A). The L-shaped angle bar constituting the upper support member 15A has its wide side portion 150 sandwiched between the upper flanges 102 of the side sill outer member 1a and the side sill inner member 1b and joined to the side sill 1. The narrow side portion 151 of the L-shaped angle bar abuts and is joined to the upper lateral surface 41A of the hollow cross-section member 4. The L-shaped angle bar constituting the lower support member 15B has its wide side portion 150 sandwiched between the lower flanges 102 of the side sill outer member 1a and the side sill inner member 1b and joined to the side sill 1. The narrow side portion 151 of the L-shaped angle member is abutted against and joined to the lower lateral surface portion 41A of the hollow cross-section member 4. As a result, the shock absorbing structure 2 (hollow cross-section member 4) is supported by the side sill 1 via the two upper and lower support members 15A, 15B. The support member 15 in each of the above-described embodiments shown in FIG. 11 is formed by bending a metal plate.

[0042] As another example of a support structure for the shock absorbing structure 2, a structure in which the shock absorbing structure 2 (hollow cross-section member 4) is supported only by the upper support member 15A in FIG. 11(c) can also be used. The support member 15 is joined to the impact absorbing structure 2 (hollow cross-section member 4) or the side sill 1 by at least one of welding (usually spot welding), mechanical fastening using bolts or rivets, and adhesive bonding. The support members 15 may be provided along the longitudinal direction of the vehicle so as to support the shock absorbing structure 2 over its entire length, or may be provided intermittently in the longitudinal direction of the vehicle so as to support the shock absorbing structure 2 at intervals in the longitudinal direction. In addition, even when the impact absorbing structure 2 (cross-sectional hollow member 4) is joined to the side sill outer 1a and the side sill inner 1b (their respective vertical surface portions 100) as shown in Figure 10, a support structure using a support member 15 as shown in Figure 11 may be used in combination for reinforcement, etc.

[0043] In addition, the bulkhead 6 and / or the lateral surface portion 41 (41A, 41B) of the cross-sectional hollow member 4 may have beads on its main body (partition portion in the case of a bulkhead) to increase or decrease its buckling strength (rigidity). Figure 12 is a longitudinal cross-sectional view of a side sill in the vehicle width direction, schematically illustrating an embodiment in which a bead is provided on the bulkhead 6. In Figure 12(A), a bead 60 is provided on the main body (partition) of the bulkhead 6 along the vehicle width direction in order to increase the buckling strength. On the other hand, in Figure 12(B), a bead 60 (crash bead) is provided on the main body (partition) of the bulkhead 6 along the vertical direction in order to decrease the buckling strength. The reason for providing the bead 60 as shown in Figure 12(B) has been explained above. In addition, beads similar to those shown in Figures 12(a) and (b) can be provided on the lateral surface 41 (lateral surface 41A and / or lateral surface 41B) of the cross-sectional hollow member 4 for the same purpose as above.

[0044] The structure of the hollow cross section member 4 that constitutes the shock absorbing structure 2 is not limited to the embodiment shown in FIGS. 1 to 3, but may be various other embodiments such as those shown in FIG. 13(a) to 13(f) are explanatory diagrams showing examples of the structure of the hollow cross-section member 4 that constitutes the shock absorbing structure 2. FIG. FIG. 13(A) shows the cross-sectional hollow member 4 of the embodiment of FIGS. 13(a) and 13(e) show a hollow cross-section member 4 having a substantially horizontally elongated rectangular cross section in the vehicle width direction, which is constructed by combining two angled cross-section members 4c (L-shaped angle members). A joining flange portion 42 is formed on the end of the wide side portion 43 of each angled cross-section member 4c, and this flange portion 42 abuts against and is joined to the inner surface of the end side of the narrow side portion 44 of the mating angled cross-section member 4c. 13(c) shows a hollow cross-section member 4 having a substantially horizontally elongated rectangular cross section in the vehicle width direction, which is made up of a grooved cross-section member 4d that opens (opens) laterally toward the vehicle inner side and a plate-like lid member 4e that closes the lateral opening (opening) of this grooved cross-section member 4d. Joining flange portions 42 are formed on the tips of both flange portions that form the opening (opening) of the grooved cross-section member 4d, facing outward, and these flange portions 42 are joined by abutting against the surfaces on both ends of the lid member 4e in the width direction.

[0045] 13(d) shows a hollow cross-section member 4 having a substantially horizontally elongated rectangular cross section in the vehicle width direction, which is made up of an upwardly opening (open) grooved cross-section member 4a and a plate-like cover member 4b that closes the upward opening (open portion) of the grooved cross-section member 4a. Joining flange portions 42 are formed continuously at both widthwise ends of the cover member 4b. The cover member 4b is fitted into the opening of the grooved cross-section member 4a so that both flange portions 42 are in close contact with the inside of the opening of the grooved cross-section member 4a (i.e., the inside of the tips of both flanges of the grooved cross-section member 4a), and both flange portions 42 are joined to the grooved cross-section member 4a. 13(f) shows a hollow cross-section member 4 having a substantially horizontally elongated rectangular cross section in the vehicle width direction, which is made up of a grooved cross-section member 4d that opens (opens) laterally toward the outer side of the vehicle and a plate-like lid member 4e that closes the lateral opening (opening) of this grooved cross-section member 4d. As in FIG. 13(c), joining flanges 42 are formed on the tips of both flanges that form the opening (opening) of the grooved cross-section member 4d, facing outward, and these flanges 42 are joined by abutting against the surfaces on both ends of the lid member 4e in the width direction. In each of the embodiments shown in Fig. 13 described above, each of the members constituting the hollow cross-sectional member 4 is formed by bending a metal plate. The members constituting the hollow cross-sectional member 4 are usually joined together by spot welding. The flange portions 42 may be formed only on a portion of the longitudinal direction of each member having the flange portion 42 (for example, formed intermittently at a predetermined interval).

[0046] <Crash deformation of side sill structure during a side collision> The deformation of the side sill structure of the present invention during a side collision will be described with reference to Figure 14. Figure 14 shows the step-by-step deformation of the side sill structure of the present invention during a side pole collision in a horizontal cross section (cross section taken along line II-II in Figure 1), where t indicates the time (in seconds) from the start of the collision. First, the cross-sectional deformation of the side sill 1 itself will be described. First, the upper and lower lateral surface portions 101A, 101B (energy absorption portions) of the side sill outer 1a bend and collapse outward, absorbing the collision energy (from 0.002 sec). During this process of the side sill outer 1a collapsing, the lateral surface portions 101A, 101B (energy absorption portions) of the side sill outer 1a continue to bend and deform until 0.014 sec, and continue to absorb the collision energy until they are completely collapsed. As the side sill outer 1a is crushed and deformed as described above, the collision load is transmitted to the side sill inner 1b via the flange 102 of the side sill 1. Then, after 0.004 seconds, the flange sides of the lateral surfaces 101A, 101B (energy absorption parts) of the side sill inner 1b are bent in a convex shape toward the inside of the closed cross section of the side sill 1 and crushed.

[0047] As the cross-sectional deformation of the side sill 1 itself occurs, the impact absorption structure 2 also undergoes cross-sectional deformation as follows: The crushed side sill outer 1a comes into contact with the vehicle outer-side vertical surface 40 of the hollow cross-section member 4, transmitting the collision load to the impact absorption structure 2. The upper and lower horizontal surfaces 41A, 41B (energy absorption surfaces) of the hollow cross-section member 4 and the bulkhead 6 begin to bend and deform like bellows (axial collapse) (from 0.002 sec). The impact absorption structure 2, which extends along the vehicle's fore-and-aft direction, is pressed as a whole against the floor cross member 8 and battery case 9 via the side sill inner 1b. Therefore, the collision load transmitted to the impact absorption structure 2 is distributed and transmitted to the floor cross member 8 and battery case 9. Then, the reaction force from the floor cross member 8 and battery case 9 is transmitted to the impact absorption structure 2 (lateral surface portions 41A, 41B and bulkhead 6) at a position adjacent in the longitudinal direction of the vehicle to the side pole collision position (0.004 to 0.006 s). After that, deformation of the impact absorption structure 2 at the side pole collision position is promoted, and bending deformation of the lateral surface portions 41A, 41B (energy absorption surface portions) adjacent in the longitudinal direction of the vehicle is also promoted (0.008 to 0.012 s). Furthermore, the bulkhead 6 adjacent to the side pole collision position also bends (0.012 sec or more).

[0048] FIG. 15 shows the relationship between the amount of penetration of the impacting object and the absorbed energy when the impactor is deformed during a side pole collision. Collision body: Rigid pole with radius 127 mm (equivalent to a diameter of 254 mm) Collision speed: 30.9km / h Collision energy: 25kJ This test shows that the impact absorption structure 2 is mainly deformed, and is therefore capable of absorbing impact energy of 25 kJ when the impact object penetration amount is within 100 mm.

[0049] In the cross-sectional deformation of the side sill structure during a side collision as described above, the impact absorption structure 2, which is installed inside the side sill 1 and has a structure in which the hollow cross-sectional member 4 and the bulkhead 6 are integrated, has high deformation resistance. As a result, the impact absorption structure 2 does not deform locally in response to the input load (for example, it does not deform in a bending manner from the impact area), but rather deforms as a whole, thereby absorbing the collision energy effectively and appropriately. Therefore, the side sill structure of the present invention functions as follows in an automobile (particularly an electric automobile) equipped with a battery module below the floor panel 7 between both side sills 1 as shown in Figure 3. That is, the impact absorbing structure 2 collapses under the load input from the vehicle width direction during a side collision, absorbing energy, while transmitting the load to the floor cross member 8 and the battery case 9, thereby preventing the load from being transmitted to the battery pack 10 and providing protection from the impact of the collision. [Example]

[0050] In order to confirm the effect of the side sill structure according to the present invention, a collision test was carried out using the following FEM analysis. Figures 16(a) to 16(e) show the test specimens and test conditions for the invention example and comparative example. In each of Figures 16(a) to 16(e), the left-hand side is a cross-sectional view of the side sill in the vehicle width direction, and the right-hand side is a horizontal cross-sectional view of the side sill, showing the collision position of the collision object (pole) against the side sill and the position of the floor cross member. In this crash test, the side sill and impact absorbing member (impact absorbing structure 2 in the example) of the vehicle side structure were used as test specimens to evaluate the impact energy absorption characteristics. In addition, the floor cross member and battery case side member adjacent to the side sill were used as rigid jigs for fixing the test specimen, and the load transmitted to the jigs was evaluated by contact reaction force.

[0051] In the collision test, as shown in Figure 16, a collision object (pole) with a curvature radius of 127 mm was collided perpendicular to the longitudinal direction of the test object with an initial speed of 30.9 km / h and a maximum penetration of 100 mm. The collision energy was 25 kJ. The fixing jig for the side sill on the opposite side of the collision object consisted of a floor cross member imitation (equivalent to floor cross member 8), a battery case wall (equivalent to battery case side member 90), and a battery case lower part (equivalent to battery case bottom plate 91 and mounting flange 92), which simulated the vehicle body side structure shown in Figure 3. The battery case lower part was fixed to the side sill inner panel with fixing bolts (equivalent to fixing bolt 11). The width (wa) of the floor cross member imitation part in the vehicle longitudinal direction was 80 mm. Table 1 shows the strength levels and thicknesses of the steel plates used for each member of the test specimens of the invention examples and comparative examples.

[0052] [Table 1]

[0053] In the test specimen of the invention example 1 shown in FIG. 16(a), the impact absorbing structure 2 has bulkheads 6 at two locations in the area within the width of the floor cross member simulation part (corresponding to the floor cross member 8). x In the area outside the width of the floor cross member simulation section on both sides, there is a bulkhead set consisting of two adjacent bulkheads. y In addition, two adjacent bulkheads 6 x The spacing w1 is 35 mm, and the ratio w1 / wa of the spacing w1 to the width wa of the floor cross member is 0.44. x and the adjacent bulkhead 6 y The distance w2 between the floor cross members is larger than w1, but is 254 mm or less, and is set at 125 mm, which is about half of the assumed floor cross member installation distance (the distance between adjacent floor cross members wb) of 260 mm. yThe spacing w4 between the bulkheads that make up the bulkhead set is set to 35 mm, the same as spacing w1.

[0054] The specimen of the invention example 2 shown in FIG. 16(b) is the bulkhead 6 of the invention example 1. y In the impact absorbing structure 2, bulkheads 6 are provided only at two locations within the width of the floor cross member simulation part (corresponding to the floor cross member 8). The test specimen of Comparative Example 1 shown in FIG. 16(c) is the same as the shock absorbing structure 2 of Invention Example 2 except that the bulkhead 6 is removed. The test specimen of Comparative Example 2 shown in Figure 16(d) has only a bulkhead installed inside the side sill. Bulkheads are installed in two locations within the width of the floor cross member simulation section. In addition, a bulkhead set consisting of two adjacent bulkheads is installed in the areas on both sides outside the width of the floor cross member simulation section. The test specimen of Comparative Example 3 shown in FIG. 16(e) was a test specimen consisting of only the side sill, without any impact absorbing member disposed inside the side sill.

[0055] 17(a) to 17(e) show the relationship between the penetration amount of the impacting object (punch) into the side sill and the force (punch reaction force) received from the impacting object during the collision test for the above-mentioned example and comparative example, as well as the transition of absorbed energy relative to the penetration amount of the impacting object (punch). The absorbed energy was calculated by subtracting the kinetic energy calculated from the speed of the impacting object from the collision energy (25 kJ). The maximum stroke of the impact body is 100 mm, and in Example 1 of the invention shown in Figure 17(a), the impact body stopped (99 mm) before reaching the maximum penetration of 100 mm, and the energy absorbed by the side sill structure of Example 1 of the invention was 25.0 kJ. In contrast, in all of Example 2 and Comparative Examples 1 to 3 shown in Figures 17(b) to 17(e), the impactor reached a maximum stroke of 100 mm before reaching the absorbed energy of 25.0 kJ (the absorbed energy of Example 1).

[0056] Figure 18 shows a comparison of the absorbed energy at maximum penetration of the impacting object between the above-mentioned invention examples and comparative examples. The maximum penetration amount was 99 mm for invention example 1, and 100 mm (maximum penetration amount of the impacting object) for invention example 2 and comparative examples 1 to 3. The absorbed energy of Example 1 of the invention was 5.8 times that of Comparative Example 3, which had only a side sill, and 2.6 times that of Comparative Example 1, which had no bulkhead, and Comparative Example 2, which had only a bulkhead.The absorbed energy of Example 1 of the invention was approximately 1.3 times the total of 19.0 kJ for Comparative Examples 1 and 2. Furthermore, since Example 2 had fewer bulkheads installed in the longitudinal direction of the vehicle than Example 1, the absorbed energy was lower than that of Example 1 (down 17%), but it was 4.8 times that of Comparative Example 3 and 2.2 times that of Comparative Examples 1 and 2. It was also approximately 1.1 times the combined total of Comparative Examples 1 and 2.

[0057] From the results of the above-mentioned examples and comparative examples, it was confirmed that the side sill structure of the present invention provides extremely excellent collision characteristics that exceed the effect of simply adding together the collision energy absorption performance of Comparative Example 1 (a side sill structure in which only a cross-sectional hollow member is provided within the side sill) and Comparative Example 2 (a side sill structure in which only a bulkhead is provided within the side sill). Furthermore, the results of Invention Examples 1 and 2 confirmed that collision characteristics can be further improved by arranging multiple bulkheads not only in the area within the width of the floor cross member but also in other areas in the fore-and-aft direction of the vehicle. [Explanation of symbols]

[0058] 1 Side sill 1a Side sill outer 1b Side sill inner 2. Impact absorption structure 3 Closed section space 4-section hollow member 4a Cross-sectional channel member 4b Lid member 4c cross-section angle member 4d cross-section channel member 4e Lid member 5 Closed section space 6,6 x ,6 y bulkhead 7 Floor Panel 8 Floor cross member 9 Battery Case 10 Battery Pack 11 Fixing bolt 12 Joint 13 Adhesive 15, 15A, 15B Support members 40 Vertical surface 41,41A,41B Lateral side 42 Flange 43 Wide side 44 Narrow Side 60 beads 61 Flange 70 Flange 90 Battery case side member 91 Battery case bottom plate 92 Mounting flange 100 Vertical surface 101A,101B Lateral surface section 102 flange 150 wide side 151 Narrow side 152 Slope section

Claims

1. A side sill structure comprising side sills (1) extending along the longitudinal direction of the vehicle on both sides of the lower part of the vehicle, and an impact absorbing structure (2) arranged in a closed cross-sectional space (3) within the side sill (1) (however, this excludes side sill structures comprising a partition member that passes vertically through the closed cross-sectional space (3) within the side sill (1), and in which the impact absorbing structure (2) is provided with the partition member interposed therebetween), The shock absorbing structure (2) a hollow cross-sectional member (4) arranged in the closed cross-sectional space (3) along the vehicle longitudinal direction so as to form a closed cross-sectional space (5) inside and divide the closed cross-sectional space (3) into upper and lower sections; and bulkheads (6) which are members arranged in the closed cross-sectional space (5) of the hollow cross-section member (4) along the vehicle width direction to partition the closed cross-sectional space (5), and which are arranged at a plurality of locations in the closed cross-sectional space (5) at intervals in the vehicle longitudinal direction, A side sill structure for an automobile, characterized in that each bulkhead (6) is joined to the inner wall of a cross-sectional hollow member (4).

2. The side sill structure of an automobile as described in claim 1, characterized in that the bulkhead (6) is joined to at least the inner wall of the vertical surface portion (40) on the vehicle inner side and the inner wall of the upper horizontal surface portion (41A) or / and the lower horizontal surface portion (41B) of the inner wall of the cross-sectional hollow member (4).

3. The bulkhead (6) is a bulkhead (6) provided in an area within the width of the floor cross member in the vehicle longitudinal direction. ｘ ) and a bulkhead (6) provided in the area outside the width of the floor cross member ｙ ) and In the front-to-rear direction of the vehicle, Bulkheads (6) are installed at two or more locations within the width of the floor cross member. ｘ ) is provided, and a bulkhead (6) is provided at one or more locations in the area outside the width of the floor cross member. ｙ ) was established, Two adjacent bulkheads (6 ｘ ) spacing is w1, bulkhead (6 ｘ ) and the adjacent bulkhead (6 ｙ 2. The automobile side sill structure according to claim 1, wherein when the distance between the side sill and the base is w2, w1 < w2.

4. At least some of the bulkheads (6 ｙ 4. The side sill structure of an automobile according to claim 3, wherein the first bulkhead comprises a bulkhead set consisting of two or more adjacent bulkheads.

5. 2. The side sill structure of an automobile according to claim 1, wherein a longitudinal surface portion (40) of the hollow cross-section member (4) and a longitudinal surface portion (100) of the side sill (1) facing the longitudinal surface portion (40) are joined together.

6. The vertical surface portion (40) of the hollow cross-section member (4) and the vertical surface portion (100) of the side sill (1) facing each other are in contact with each other or face each other with a predetermined gap therebetween, 2. The side sill structure of an automobile according to claim 1, wherein the hollow cross-sectional member (4) is supported on the side sill (1) via a support member (15).

7. 2. The side sill structure of an automobile according to claim 1, wherein beads are formed on the lateral surfaces (41) of the cross-sectional hollow member (4) and / or on the bulkhead (6).

8. 8. The automobile side sill structure according to claim 1, wherein the metal plate constituting the impact absorbing structure (2) has a tensile strength of 590 MPa or more.

Images