Vehicle body underbody structure and side sill structure

Abstract

The vehicle body underbody structure related to the present invention is a vehicle body underbody structure having a specific component including a side sill (1), wherein the side sill (1) has a structure in which a closed cross-sectional space (3) is divided into two closed cross-sectional spaces (3a, 3b) in the vehicle width direction by a partition member (2), and additionally, the side sill has a shock-absorbing structure (A) composed of a pair of cross-sectional groove-shaped members (4a, 4b) that are joined to the partition member (2) with the partition member (2) inserted from both sides within the closed cross-sectional spaces (3a, 3b) and form a closed cross-sectional space (5a, 5b) between the partition member (2) and the member (2), and a bulkhead (6) that divides the closed cross-sectional spaces (5a, 5b) by being formed along the vehicle width direction within each closed cross-sectional space (5a, 5b). The bulkheads (6) within the closed cross-section spaces (5a, 5b) are formed under predetermined arrangement conditions, and each bulkhead (6) is joined to at least the cross-section grooved members (4a, 4b).

Description

Technology Field

[0001] The present invention relates to a lower structure of an automotive body comprising a side sill structure on the side of the body of an automobile, and in particular, to a lower structure of an automobile suitable for having a battery module below a floor panel between two side sills. Background Technology

[0002] Generally, vehicles equipped with large-capacity batteries, such as battery electric vehicles (BEVs) or plug-in hybrid electric vehicles (PHEVs) (hereinafter collectively referred to as "battery-powered vehicles"), are equipped with a battery module located below the floor panel. The battery module consists of battery cells (battery packs) and a battery case for housing them. Generally, the battery case serves to protect the battery cells from impact loads, and therefore, members with high rigidity and high proof stress are used. Around the battery case, members are positioned to absorb energy by deforming themselves. In particular, in the case of a side impact, the side sill absorbs the impact load from the side of the vehicle body, while the remaining load is supported by the floor cross member or the battery case side member. At this time, if the amount of deformation required for energy absorption by the side sill is small, the energy absorption section can be reduced, and instead, the volume of the battery module can be expanded, which leads to an increase in cruising distance. For the above reasons, there is a demand for a lightweight side sill structure with excellent impact energy absorption properties and a vehicle body underbody structure including it.

[0003] A technology has been proposed to increase the rigidity of the side sill to improve energy absorption performance during a side collision. Specifically, Patent Document 1 discloses a technology that prevents cross-section collapse of the side sill during a side collision by forming a bulkhead along the vehicle width direction within the interior (closed sectional space) of the side sill, which is a closed cross-section structure forming the side of the vehicle. A flange portion is formed on the outer circumference of the bulkhead and is welded and fixed to the reinforcement within the side sill. In addition, Patent Documents 2 and 3 disclose a technology that prevents cross-section collapse of the side sill during a side collision in a structure in which a partition member is provided that penetrates the interior of the side sill vertically, and the closed sectional space within the side sill is divided into two closed sectional spaces in the vehicle width direction by this partition member. More specifically, these technologies form a plurality of bulkheads along the vehicle width direction within a closed cross-sectional space in the side sill, and prevent the cross-sectional collapse of the side sill during a side collision through a combination of these bulkheads and a partition member. In these technologies, the partition member is formed to prevent the side sill from spreading in the vertical direction and collapsing cross-sections during a side collision. In Patent Document 2, the bulkheads are formed only in one side of the closed cross-sectional space within the side sill, with the partition member in between. On the other hand, in Patent Document 3, the bulkheads are formed on both sides of the closed cross-sectional space within the side sill, with the partition member in between.

[0004] In addition, Patent Document 4 discloses a technology in which a partition member is provided that penetrates vertically through the interior of the side sill, and in which the closed cross-section space within the side sill is divided into two closed cross-section spaces in the vehicle width direction by the partition member, and an impact absorption member having a hat-shaped cross section is placed on both sides of the partition member (inner and outer sides of the partition member). In addition, Patent Document 5 discloses a technology in which a plurality of ridge line sections along the vehicle width direction are spaced apart from each other in the closed cross-section space within the side sill, and an impact absorption member having a wave shape that moves up and down along the front-rear direction of the vehicle body is placed therein to suppress local deformation while maintaining impact absorption capacity.

[0005] In addition, Patent Document 6 discloses a structural reinforcement system (Fig. 2) comprising a rigid carrier that provides structural reinforcement within a cavity wall by including a plurality of longitudinal ribs interconnected with a plurality of transverse ribs, an insertion member corresponding to a stiffener, and a bonding material that joins the cavity wall and the carrier, as a system for reinforcing a cavity within a vehicle frame. In addition, Patent Document 7 discloses a technology in which a hat member having a top plate, two longitudinal walls, and two flanges, and a closing plate, are provided with a side sill, wherein a plurality of grooves extending in a direction perpendicular to the longitudinal direction of the hat member are formed in the longitudinal walls of the hat member, thereby increasing the load required for deformation of the side sill during a side collision of a vehicle and obtaining high energy absorption efficiency. Prior art literature

[0006] Japanese Published Patent Application No. Hei 10-59218 Japanese Published Patent Application No. 2009-202620 Japanese Published Patent Application No. 2013-49378 Japanese Published Patent Application No. 2017-226353 Japanese Published Patent Application No. 2021-146973 Japanese Published Patent Application No. 2011-530450 Japanese Patent Application No. 6703322 The problem to be solved

[0007] The technology disclosed in Patent Document 1 has a problem in that, because the bulkhead is structured to be elongated in the vehicle width direction and prone to buckling, buckling of the bulkhead occurs easily during a side collision, and once buckling of the bulkhead begins, the cross-sectional collapse of the side sill occurs. Consequently, appropriate collision energy absorption performance is not obtained. Furthermore, as with the technology disclosed in Patent Documents 2 and 3, even when the bulkhead is formed in a closed cross-sectional space within the side sill having a partition member, sufficient collision energy absorption characteristics are not obtained. In the technology disclosed in Patent Document 2, since the bulkhead is formed in a closed cross-sectional space on one side separated by the partition member, it only has the function of maintaining the cross-sectional shape of that one closed cross-sectional space, and thus sufficient collision energy absorption characteristics are not obtained. Furthermore, as with the technology disclosed in Patent Document 3, even when the bulkhead is formed in a space on both sides separated by the partition member, the obtained collision energy absorption characteristics are not sufficient.

[0008] Furthermore, the technology disclosed in Patent Document 3 requires forming a slit in the partition member to insert the bulkhead, and when multiple bulkheads are installed along the longitudinal direction of the side sill, the spacing between the bulkheads cannot be extended to avoid a decrease in the strength of the partition member due to the slit. Consequently, there is a problem in that the number of bulkheads installed increases, leading to an increase in weight. Also, as in Patent Document 4, in a side sill having a partition member, simply placing shock-absorbing members with a hat-shaped cross-section on both sides of the partition member (inner and outer sides of the partition member) does not yield sufficient collision energy absorption characteristics. Moreover, the technology disclosed in Patent Document 5 can distribute the impact load during a side collision to a cross-section perpendicular to the vehicle width direction and transmit it uniformly, thereby yielding high collision energy absorption characteristics. However, in the case of side interior reinforcements having a uniform cross-section in the front-rear direction of the vehicle, there is a possibility of excessive weight because reinforcing members exist even in areas that do not require reinforcement.

[0009] Furthermore, regarding the thickness and spacing of the transverse ribs and longitudinal ribs in the technology disclosed in Patent Document 6, the thickness is 2 to 8 mm and the spacing is 20 to 40 mm, and since reinforcing members exist even in areas that do not require reinforcement, similar to Patent Document 5, there is a possibility of excessive weight. Also, in the technology disclosed in Patent Document 7, by forming a plurality of grooves in the longitudinal wall of the hat member, when a collision load is input from the outside of the vehicle in the vehicle width direction, the longitudinal wall is prone to deforming into a bellows-shaped form, and as a result, the amount of deformation of the side sill in the inner side of the vehicle width direction increases. Because of this, a large load is input to the battery module, causing the battery module to deform, and there are cases where the battery cannot be protected. Therefore, in the event of a side collision of a vehicle (especially an electric vehicle) equipped with a battery module below the floor panel between the two side sills, it was required to reduce the load input to the battery case due to the deformation of the side sill.

[0010] The present invention has been made to solve the above problems, and its purpose is to provide a vehicle body understructure and a side sill structure that, in a vehicle body understructure including a side sill, obtains high collision energy absorption characteristics with a small amount of collision deformation while suppressing weight increase caused by structural members. Furthermore, another objective of the present invention is to provide a vehicle body understructure and a side sill structure that can reduce the load input to the battery module due to deformation of the side sill. means of solving the problem

[0011] As a result of repeated investigations to solve the above problem, the inventors discovered that the problem can be solved by using a partition member that vertically penetrates the closed cross-sectional space within the side seal and by forming an impact absorbing structure of a specific structure within the closed cross-sectional space. Specifically, they discovered that a high energy absorption performance can be obtained while suppressing weight increase caused by the structural members by forming an impact absorbing structure composed of a pair of sectionally groove-shaped members that are joined to the partition member from both sides within the closed cross-sectional space of the side seal, and a plurality of bulkheads installed under predetermined conditions within two closed cross-sectional spaces formed between the sectionally groove-shaped members and the partition member, respectively. In addition, it was discovered that regarding the lower part of the shock-absorbing structure, one of the inner side part and the outer side part is extended downward more than the other, or a recess is formed in one of the inner side part and the outer side part facing the inner surface of the side seal, thereby reducing the load input to the battery module due to the deformation of the side seal. The present invention is made based on such findings and is summarized as follows.

[0012] The vehicle body underbody structure related to the present invention comprises side sills (1) arranged along the vehicle length direction on both sides of the vehicle body lower body, a floor cross member (8) arranged between the two side sills (1) with both sides fixed to the upper portions of the two side sills (1), and a battery case (9) arranged below the floor cross member (8) with both sides facing the lower portions of the two side sills (1). The side sills (1) have a partition member (2) that vertically penetrates a closed cross-sectional space (3) within the side sills (1), and the closed cross-sectional space (3) is divided into two closed cross-sectional spaces (3a) and (3b) in the vehicle width direction by the partition member (2). Additionally, the side sills (1) have a structure in which the partition member (2) is inserted from both sides within the closed cross-sectional spaces (3a) and (3b). The shock absorbing structure (A) comprises a pair of cross-sectional groove-shaped members (4a) and (4b) that are joined to a partition member (2) and form a closed cross-sectional space (5a) and (5b) respectively between the partition member (2), and bulkheads (6) formed at multiple points spaced apart in the front-rear direction of the vehicle within each closed cross-sectional space (5a) and (5b) as members that partition the closed cross-sectional space (5a) and (5b) by being formed along the vehicle width direction within each closed cross-sectional space (5a) and (5b); wherein, in the shock absorbing structure (A), the bulkheads (6) within the closed cross-sectional space (5a) and the bulkheads (6) within the closed cross-sectional space (5b) are formed facing each other in the vehicle width direction with the partition member (2) in between, and each bulkhead (6) is joined to at least the cross-sectional groove-shaped member (4a) or the cross-sectional groove-shaped member (4b). The upper part of the shock-absorbing structure (A) has an inner side and an outer side facing each other with a partition member (2) in between,It is located on the horizontal extension of the floor cross member (8) in the vehicle width direction.

[0013] The bulkhead (6) is formed in an area that is within the width of the floor cross member in the front-rear direction of the vehicle. x ) and a bulkhead (6) formed in an area outside the width of the floor cross member y It is composed of ), and in the front-rear direction of the vehicle, at two or more points in the area within the width of the floor cross member, bulkheads (6 x Along with the formation of ), bulkhead (6) at one or more points in the area outside the width of the floor cross member y ) is formed, and two adjacent bulkheads (6 x The spacing of ) is w1, bulkhead (6 x ) and the bulkhead adjacent to this (6 y If the interval of ) is set to w2, then w1 < w2.

[0014] At least some of the bulkheads (6 y ) may be composed of a bulkhead set consisting of two or more bulkheads formed adjacently.

[0015] Each bulkhead (6) can be joined to the cross-sectional grooved member (4a) or the cross-sectional grooved member (4b) and the partition member (2), respectively.

[0016] The lower part of the shock absorbing structure (A) has one of the inner side portion and the outer side portion separated by the partition member (2) extending downward more than the other, and at least the portion (e) extending downward among the lower part of the shock absorbing structure (A) is located on the horizontal extension of the battery case (9) in the vehicle width direction.

[0017] The lower part of the shock-absorbing structure (A) is located on the horizontal extension of the battery case (9) in the vehicle width direction, and as a lower area or an area including the lower part in the height direction of the shock-absorbing structure (A), a recessed portion (c) is formed facing the inner surface of the side sill (1) in either the inner side part or the outer side part with the partition member (2) in between.

[0018] The longitudinal surface (40) of each cross-sectional groove-shaped member (4a) and (4b) and the longitudinal surface (100) of the side seal (1) facing it may be (i) directly joined or in contact, (ii) joined or in contact with another member interposed, or (iii) not joined or in contact, but facing each other with a predetermined gap.

[0019] The metal plate constituting the shock-absorbing structure (A) has a yield strength less than or equal to the yield strength of the metal sheet constituting the floor cross member, and a tensile strength of 500 MPa class or higher.

[0020] A side sill structure of a vehicle related to the present invention comprises a partition member (2) that vertically penetrates a closed cross-sectional space (3) within a side sill (1), wherein the closed cross-sectional space (3) is divided into two closed cross-sectional spaces (3a) and (3b) in the vehicle width direction by the partition member (2). In the closed cross-sectional spaces (3a) and (3b), a pair of cross-sectional groove-shaped members (4a) and (4b) are joined to the partition member (2) with the partition member (2) inserted from both sides and form a closed cross-sectional space (5a) and (5b) respectively between the partition member (2), and a bulkhead formed at a plurality of points spaced apart in the vehicle front-rear direction within each closed cross-sectional space (5a) and (5b) as a member formed along the vehicle width direction within each closed cross-sectional space (5a) and (5b) to divide the closed cross-sectional space (5a) and (5b). (6) has an impact absorption structure (A) formed by, wherein in the impact absorption structure (A), the bulkhead (6) in the closed cross-section space (5a) and the bulkhead (6) in the closed cross-section space (5b) are formed facing each other in the vehicle width direction with the partition member (2) in between, and each bulkhead (6) is joined to at least the cross-section groove member (4a) or the cross-section groove member (4b).

[0021] Each bulkhead (6) can be joined to the cross-sectional grooved member (4a) or the cross-sectional grooved member (4b) and the partition member (2), respectively.

[0022] The bulkhead (6) is formed in an area that is within the width of the floor cross member in the front-rear direction of the vehicle. x ) and a bulkhead (6) formed in an area outside the width of the floor cross member y It is composed of ), and in the front-rear direction of the vehicle, at two or more points in the area within the width of the floor cross member, bulkheads (6 xAlong with the formation of ), bulkhead (6) at one or more points in the area outside the width of the floor cross member y ) is formed, and two adjacent bulkheads (6 x The spacing of ) is w1, bulkhead (6 x ) and the bulkhead adjacent to this (6 y If the interval of ) is set to w2, then w1 < w2.

[0023] At least some of the bulkheads (6 y ) may be composed of a bulkhead set consisting of two or more bulkheads formed adjacently.

[0024] The spacing (w2) should be 254 mm or less.

[0025] The longitudinal surface (40) of each cross-sectional groove-shaped member (4a) and (4b) and the longitudinal surface (100) of the side seal (1) facing it may be (i) directly joined or in contact, (ii) joined or in contact with another member interposed, or (iii) not joined or in contact, but facing each other with a predetermined gap.

[0026] The yield strength of the metal plate constituting the shock-absorbing structure (A) must be less than or equal to the yield strength of the metal plate constituting the floor cross member.

[0027] The tensile strength of the metal plate constituting the shock-absorbing structure (A) must be 500 MPa or higher.

[0028] It is sufficient if a bead (60) is formed on the bulkhead (6).

[0029] The shock-absorbing structure (A) may have one of the inner and outer parts separated by the partition member (2) extended further in the vehicle height direction than the other.

[0030] In the shock-absorbing structure (A), a recess (c) is formed facing the inner surface of the side seal (1). Effects of the invention

[0031] The vehicle body underbody structure and side sill structure of the present invention utilize a partition member (2) that vertically penetrates a closed cross-sectional space (3) within a side sill (1), and a shock-absorbing structure (A) of a specific structure is formed within the closed cross-sectional space (3), thereby obtaining high collision energy absorption characteristics with a small amount of collision deformation. Therefore, when applied to a vehicle equipped with a battery module between two side sills, such as an electric vehicle, the space required for energy absorption can be reduced, and thus there is an advantage in that the volume of the battery module can be expanded. In addition, since high bending stiffness is obtained with the minimum necessary components of the shock-absorbing structure (A), the increase in weight of the vehicle body due to the components can also be suppressed. In addition, in the vehicle body underbody structure and side sill structure of the present invention, with respect to the lower part of the shock-absorbing structure (A), one of the inner side part and the outer side part is extended downward compared to the other, or a recessed part (c) is formed in one of the inner side part and the outer side part facing the inner surface of the side sill (1), thereby reducing the load input to the battery module due to deformation of the side sill. Thus, deformation of the battery module due to a collision can be more effectively prevented. Brief explanation of the drawing

[0032] FIG. 1 schematically illustrates one embodiment of the vehicle body underbody structure of the present invention and is a longitudinal cross-sectional view in the vehicle width direction of a vehicle body underbody structure (one of the structural parts on both sides of the vehicle body underbody) including a side sill. FIG. 2 is a plan view of a vehicle body undercarriage structure (a structural part of one of the structural parts on both sides of the vehicle body undercarriage) including a side sill in the embodiment of FIG. 1. FIG. 3 partially shows only the side sill structure in the embodiment of FIG. 1, and is a longitudinal cross-sectional view of the side sill structure in the vehicle width direction. Figure 4 is a cross-sectional view along line IV-IV in Figure 3. Figure 5 is an exploded view of the side seal parts shown in Figure 3. FIG. 6 is an explanatory diagram showing a floor panel, a floor cross member, and a battery case arranged between two side sills in the vehicle body underbody structure. FIG. 7 schematically illustrates another embodiment of a side sill in the vehicle body underbody structure of the present invention, and is a longitudinal cross-sectional view of the side sill in the vehicle width direction. FIG. 8 is a drawing (cross-sectional view of the side sill) for explaining the width (We) of the shock-absorbing structure (A) in the vehicle width direction and the width (Ws) of the side sill (1) with respect to the embodiment of FIG. 1. FIG. 9 is an explanatory diagram showing an example of the arrangement of bulkheads constituting the side sill in the vehicle body underbody structure of the present invention. FIG. 10 is a drawing for explaining the width (wa) of a floor cross member in the vehicle body underbody structure of the present invention. FIG. 11 is an explanatory diagram showing another arrangement example of a bulkhead constituting a side sill in the vehicle body underbody structure of the present invention. FIG. 12 schematically illustrates another embodiment of a side sill in the vehicle body underbody structure of the present invention, and is a longitudinal cross-sectional view of the side sill in the vehicle width direction. FIG. 13 schematically illustrates another embodiment of the vehicle body underbody structure of the present invention and is a longitudinal cross-sectional view in the vehicle width direction of a vehicle body underbody structure (a structural part of one of the structural parts on both sides of the vehicle body underbody) including a side sill. FIG. 14, with respect to the embodiment of FIG. 13, shows the height (thickness) (H) in the vehicle height direction of the inner side portion and the outer side portion of the shock-absorbing structure (A). short , H long This is a drawing (cross-sectional view of the side sill) to explain ). FIG. 15 schematically illustrates another embodiment of the vehicle body underbody structure of the present invention and is a longitudinal cross-sectional view in the vehicle width direction of a vehicle body underbody structure (a structural part of one of the structural parts on both sides of the vehicle body underbody) including a side sill. FIG. 16 is a drawing (cross-sectional view of a side sill) for explaining the height (thickness) (H) in the vehicle height direction and the width (W) in the vehicle width direction of the inner side part (or outer side part) of the shock-absorbing structure (A) with respect to the embodiment of FIG. 15, and the height (h) in the vehicle height direction and the width (depth) (w) in the vehicle width direction of the recess (c) formed in the inner side part (or outer side part). FIG. 17 is an explanatory diagram showing the deformation shape during a side pole impact in a horizontal cross-section of a side sill in the vehicle body undercarriage structure of the present invention in stages. FIG. 18 is an explanatory diagram schematically showing the deformation during a side pole collision in a longitudinal section in the vehicle width direction of the side sill in the vehicle body underbody structure of the present invention. FIG. 19 is a graph showing the relationship between the impact object (pole) intrusion amount and absorbed energy when the side sill in the vehicle body underbody structure of the present invention is deformed by the side pole collision shown in FIG. 18. FIG. 20 is an explanatory diagram showing a comparison of the deformation shape and deformation distribution of the side sill during a side collision with respect to embodiment 2 and embodiment 1 of the vehicle body undercarriage structure of the present invention. FIG. 21 is a graph showing the relationship between the amount of impact (pole) penetration and the absorbed energy when deformed by the side pole impact, after conducting a side pole impact test under the conditions of FIG. 18 on the side seals of Embodiment 2 and Embodiment 1 shown in FIG. 20. FIG. 22 is a drawing for explaining the input load on the battery case and floor cross member during a side pole collision for embodiment 2 of the vehicle body undercarriage structure of the present invention. FIG. 23 is a graph showing the contact reaction force generated on the battery case side member and the contact reaction force generated on the floor cross member during a side pole collision, respectively, for Embodiment 2 and Embodiment 1 of the vehicle body undercarriage structure of the present invention. FIG. 24 is an explanatory diagram showing a comparison of the deformation shape and deformation distribution of the side sill during a side collision for Embodiment 3 and Embodiment 1 of the vehicle body undercarriage structure of the present invention. FIG. 25 is a graph showing the relationship between the amount of impact (pole) penetration and the absorbed energy when deformed by the side pole impact, after conducting a side pole impact test under the conditions of FIG. 18 on the side seals of Embodiment 3 and Embodiment 1 shown in FIG. 24. FIG. 26 is a drawing for explaining the input load on the battery case and floor cross member during a side pole collision for embodiment 3 of the vehicle body undercarriage structure of the present invention. FIG. 27 is a graph showing the contact reaction force generated on the battery case side member and the contact reaction force generated on the floor cross member during a side pole collision, for Embodiment 3 and Embodiment 1 of the vehicle body undercarriage structure of the present invention, respectively. FIG. 28 is an explanatory diagram showing the side sills of the vehicle body undercarriage structures and test conditions of the inventive example and comparative example in the crash test of Example 1. FIG. 29a is a graph showing the relationship between the impactor (punch) penetration amount, punch reaction force (reaction force from side-sill), and absorbed energy in the impact test of Example 1 (Inventive Example). FIG. 29b is a graph showing the relationship between the impactor (punch) penetration amount, punch reaction force, and absorbed energy in the impact test of Example 1 (Comparative Example). FIG. 30 is a graph showing the absorbed energy at maximum penetration of the impactor (punch) in the impact test of Example 1 (inventive example and comparative example). FIG. 31a is an explanatory diagram showing the vehicle body undercarriage structure and test conditions of the invention example including the side sill in the crash test of Example 2. FIG. 31b is an explanatory diagram showing the vehicle body undercarriage structure and test conditions of the invention example including the side sill in the crash test of Example 2. FIG. 31c is an explanatory diagram showing the vehicle body undercarriage structure and test conditions of the invention example including the side sill in the crash test of Example 2. FIG. 31d is an explanatory diagram showing the vehicle body undercarriage structure and test conditions of the invention example including the side sill in the crash test of Example 2. FIG. 32 is a graph showing the absorbed energy at the maximum penetration of the impactor in the impact test of Example 2. FIG. 33 is a graph showing the battery case contact reaction force in the crash test of Example 2. Specific details for implementing the invention

[0033] <Basic structure of the vehicle undercarriage>

[0034] FIGS. 1 to 6 schematically illustrate an embodiment of the vehicle body undercarriage structure of the present invention. Among these, FIG. 1 is a longitudinal cross-sectional view in the vehicle width direction of a vehicle body undercarriage structure including a side sill (a structural part of one of the structural parts on both sides of the vehicle body undercarriage), and FIG. 2 is a plan view of the same vehicle body undercarriage structure. FIGS. 3 to 5 partially show only a side sill structure including a side sill, FIG. 3 is a longitudinal cross-sectional view in the vehicle width direction of the side sill structure, FIG. 4 is a cross-sectional view along line IV-IV in FIG. 3, and FIG. 5 is an unfolded view of the side sill parts. FIG. 6 is an explanatory diagram showing a floor panel, a floor cross member, and a battery case arranged between the two side sills in the vehicle body undercarriage structure. This vehicle body underbody structure is equipped with side sills (1) positioned along the vehicle length direction on both sides of the vehicle body underbody, a floor cross member (8) positioned between the two side sills (1) with both sides fixed to the upper portions of the two side sills (1) (directly or via a floor panel, etc.), and a battery case (9) positioned below the floor cross member (8) with both sides facing the lower portions of the two side sills (1).

[0035] The specific structure thereof will be explained below based on FIGS. 1 and FIGS. 2. The side sill (1) is a frame structure member positioned on both sides of the lower body, and a floor panel (7) is positioned between the two side sills (1). The floor panel (7) is joined to both side sills (1) (in FIG. 1, the upper portion of the longitudinal surface (100) of the side sill inner (1b)) via its two flange portions (70). Additionally, a floor cross member (8), which is a frame structure member along the vehicle width direction, is positioned on the floor panel (7), and both ends thereof are joined (fixed) to both side sills (1) (in FIG. 1, the upper portion of the longitudinal surface (100) of the side sill inner (1b)) via the floor panel (7) (flange portion (70)). The floor cross members (8) are formed at multiple points spaced apart (e.g., about 300 mm) in the front-rear direction of the vehicle. Additionally, the joining (fixing) of the floor panel (7) or floor cross members (8) described above and the side sill (1) is typically done by spot welding.

[0036] A battery case (9) containing a battery pack (10) is placed below the floor panel (7) and floor cross member (8), and the side of the battery case (9) (battery case side member (90)) faces the lower part of the side seal (1) (the lower part of the longitudinal surface (100) of the side seal inner (1b)) at a predetermined distance. A mounting flange (92) is formed in succession on the bottom of the battery case (9) (battery case bottom plate (91)) so as to protrude toward the side seal. By fastening the mounting flange (92) and the lower end of the side seal (1) (the lower transverse surface (101B) of the side seal inner (1b)) with a fixing bolt (11), the battery case (9) is held in the side seal (1). Due to this structure, the load applied to the side sill (1) during a side collision is applied to both the floor cross member (8) and the battery case (9). Accordingly, it becomes possible to handle the load over a wide range, and the load is applied to the floor cross member (8) before the battery case (9), thereby reducing the load applied to the battery case (9).

[0037] <Basic structure of the side sill and its periphery>

[0038] The side sill (1) is constructed by joining a side sill outer (1a) and a side sill inner (1b) with a cross-sectional groove shape and a partition member (2) inserted between them. Accordingly, this side sill structure is such that the partition member (2) penetrates vertically through the closed cross-sectional space (3) within the side sill (1), and the closed cross-sectional space (3) is divided into two closed cross-sectional spaces (3a, 3b) in the vehicle width direction by the partition member (2). The side sill outer (1a) and the side sill inner (1b) constituting the side sill (1) are constructed by forming a metal plate. The side sill outer (1a) and the side sill inner (1b) each have a main body portion with a cross-sectional groove shape formed by a longitudinal surface portion (100) and transverse surface portions (101A, 101B) connected to the upper and lower ends thereof, and flange portions (102) connected to both ends thereof (ends of the transverse surface portions (101A, 101B)). The longitudinal surface portion (100) does not have to be vertical and may have a suitable slope or curve. Also, the transverse surface portions (101A, 101B) do not have to be horizontal and may have a suitable slope or curve. The partition member (2) is also composed of a metal plate, and instead of a perfect flat plate, a flat plate that has been bent-formed may be used.

[0039] The side sill outer (1a) and the side sill inner (1b) are joined (usually joined by spot welding) by overlapping their flange portions (102) to form a side sill (1) in which the interior becomes a closed cross-section space (3). In this case, a partition member (2) is interposed (inserted) between the side sill outer (1a) and the side sill inner (1b), and the flange portions (102) of the side sill outer (1a) and the side sill inner (1b) are joined together with the upper and lower ends of the partition member (2) inserted between them. Accordingly, the partition member (2) penetrates the closed cross-section space (3) within the side sill (1) vertically, and the closed cross-section space (3) is divided into two closed cross-section spaces (3a, 3b) in the vehicle width direction by this partition member (2). The upper and lower ends of the partition member (2) are joined to the upper and lower ends of the side sill body (the flange portion (102) of the side sill outer (1a) and side sill inner (1b)). Thus, a high load-bearing capacity is obtained to suppress the cross-section of the side sill (1) from spreading up and down and collapsing (suppression of cross-section collapse) during a side collision, which contributes to increasing crash worthiness.

[0040] <Shock absorbing structure (A) provided by the side seal structure>

[0041] In the above-described side seal structure, the present invention is characterized by using a partition member (2) that vertically penetrates a closed cross-sectional space (3) within the side seal (1) and forming a shock-absorbing structure (A) of a specific structure within the closed cross-sectional space (3). That is, the present invention is characterized by forming a "shock-absorbing structure (A) composed of a pair of cross-sectional groove-shaped members (4a, 4b) that are fitted and joined to the partition member (2) from both sides, and a plurality of bulkheads (6) formed under predetermined conditions within two closed cross-sectional spaces (5a, 5b) formed between the cross-sectional groove-shaped members (4a, 4b) and the partition member (2), wherein the structures are structurally integrated." Accordingly, a side seal structure can be made that obtains high collision energy absorption characteristics with a small amount of collision deformation. In addition, since high bending rigidity is obtained with the minimum necessary components (especially the minimum number of bulkheads installed) of the shock-absorbing structure (A), the increase in weight of the vehicle body due to the components can also be suppressed. This shock-absorbing structure (A) is formed in the front-rear direction of the vehicle along at least the battery case side member (90) of the side sill. The upper part of the shock-absorbing structure (A) is located on the horizontal extension of the floor cross member (8) (at least a part of the height direction of the floor cross member (8)) in the vehicle width direction, with the inner side and the outer side facing each other with the partition member (2) in between. That is, the upper part of the shock-absorbing structure (A) is aligned with the floor cross member (8) in the vehicle width direction through the side sill (side sill inner (1b)).

[0042] The cross-sectional grooved members (4a, 4b) are formed by bending a metal plate. Each cross-sectional grooved member (4a, 4b) has a main body portion having a cross-sectional grooved shape, which is composed of a longitudinal surface portion (40) and transverse surface portions (41A, 41B) connected to the upper and lower ends thereof, and a flange portion (42) connected to both ends thereof (ends of the transverse surface portions (41A, 41B)). The cross-sectional grooved members (4a, 4b) have a pressure receiving surface portion where the longitudinal surface portion (40) receives a lateral impact load, and an energy absorbing surface portion where the transverse surface portions (41A, 41B) are deformed by the lateral impact load to absorb impact energy. The flange portion (42) may be formed only in a portion of the longitudinal direction of the cross-sectional grooved member (4a, 4b) (e.g., formed intermittently at predetermined intervals). The cross-sectional grooved member (4a, 4b) is arranged along the vehicle's front-rear direction (side sill length direction) within the closed cross-sectional space (3a, 3b). The cross-sectional grooved member (4a, 4b) is joined to the partition member (2) (usually joined by spot welding) with the partition member (2) inserted from both sides, with each flange portion (42) interposed, and each closed cross-sectional space (5a, 5b) is formed between the partition member (2).

[0043] The bulkhead (6) is a member that partitions the closed cross-section space (5a, 5b) by being formed along the vehicle width direction within each closed cross-section space (5a, 5b), and is formed at multiple points spaced apart in the vehicle front-rear direction within the closed cross-section space (5a, 5b). The bulkhead (6) is preferably formed to partition the entire cross-section in the vehicle width direction of the closed cross-section space (5a, 5b). The bulkhead (6) acts together with the partition member (2) during a side collision to suppress the collapse of the cross-section of the cross-section groove member (4a, 4b), and the bulkhead (6) itself buckles and undergoes bending collapse, thereby absorbing impact energy. The bulkhead (6) in the closed cross-section space (5a) and the bulkhead (6) in the closed cross-section space (5b) are formed facing each other in the vehicle width direction with the partition member (2) in between (i.e., at the same position in the vehicle front-rear direction). Accordingly, the function of maintaining the cross-sectional shape of the outer side and inner side parts of the shock-absorbing structure (A) can be properly performed, and high collision energy absorption characteristics can be obtained.

[0044] Each bulkhead (6) is formed by forming a metal plate, and its outer periphery is joined to at least the cross-sectional grooved member (4a) or the cross-sectional grooved member (4b), and more preferably to the partition member (2). In this embodiment, a flange portion (61) is formed on the outer periphery of the main body (bulkhead portion) of the bulkhead (6), and is joined to the cross-sectional grooved member (4a) or the cross-sectional grooved member (4b) and the partition member (2) through the flange portion (61). Typically, this joining is performed by spot welding. The flange portion (61) may be formed only on a part of the outer periphery of the main body (bulkhead portion) (for example, formed intermittently at predetermined intervals). The bulkheads (6) may be formed at equal intervals in the vehicle's front-rear direction within the closed cross-sectional space (5a, 5b), or, for example, may be formed with alternating wide and narrow intervals as shown in FIG. 4. In the present invention, as described below, the bulkheads (6) are formed at different intervals in specific areas in the vehicle's front-rear direction.

[0045] As described above, the shock absorbing structure (A) is installed within a closed cross-sectional space (3) inside a side seal (1) using a partition member (2). The shock absorbing structure (A) has a structure in which a pair of cross-sectional groove-shaped members (4a, 4b) joined by inserting the partition member (2) from both sides, and a bulkhead (6) formed under certain conditions in a closed cross-sectional space (5a, 5b) formed inside the cross-sectional groove-shaped members (4a, 4b) are integrated together with the partition member (2). In other words, the cross-sectional groove-shaped members (4a, 4b) formed via the partition member (2) contain bulkheads (6) arranged at a distance from each other in the front-rear direction of the vehicle, and these become an integrated structure. Accordingly, it has a high impact energy absorption property as described below.

[0046] It is preferable that the yield strength of the metal plate constituting the shock-absorbing structure (A) (cross-sectional grooved member (4a, 4b) and bulkhead (6)) be less than or equal to the yield strength of the metal plate constituting the floor cross member (8). This is to ensure that, in the event of a side collision, the shock-absorbing structure (A) deforms before the floor cross member (8) to absorb collision energy, thereby suppressing the deformation of the floor cross member (8). Therefore, if the yield strength of the metal plate constituting the shock-absorbing structure (A) is the same as the yield strength of the metal plate constituting the floor cross member (8), it is preferable to apply a bead (60) (crash bead) as shown in FIG. 12(b) described later to the bulkhead (6) constituting the shock-absorbing structure (A) so that the buckling strength of the shock-absorbing structure (A) (= load at which the member itself initiates buckling deformation. The same applies hereinafter) is lower than the buckling strength of the floor cross member (8).

[0047] In addition, the metal plate used for the shock-absorbing structure (A) (cross-sectional grooved member (4a, 4b) and bulkhead (6)) is preferably 500 MPa or higher in tensile strength, and more preferably 590 MPa or higher. As for the impact characteristics of the shock-absorbing structure (A), the higher the load (hereinafter referred to as "impact strength") when the shock-absorbing structure (A) transitions from elastic deformation immediately after the onset of deformation to plastic deformation during a side impact, the less deformation occurs during the impact, and the better the impact characteristics become. Since the impact strength increases as the tensile strength of the metal plate used for the shock-absorbing structure (A) increases, it is preferable to use a metal plate with a tensile strength of 500 MPa or higher (more preferably 590 MPa or higher), which is higher than that of common steel. In addition, from the perspective of weight reduction, in order to apply a metal plate with a thickness of less than 2 mm to the shock-absorbing structure (A), it is preferable to use a metal plate of 1180 MPa grade or higher. Also, if a high-tensile steel sheet is used as the material for the shock-absorbing structure (A) and the partition member (2), the shock-absorbing structure (A) and the partition member (2) placed inside the side seal (1) also function as reinforcement of the side seal. Therefore, it is particularly preferable to use a high-tensile steel sheet of 1180 MPa grade or higher as the metal plate used for the shock-absorbing structure (A) and the partition member (2).

[0048] <Function and Effect of Shock Absorbing Structure (A)>

[0049] In the vehicle body underbody structure of the present invention, the shock-absorbing structure (A) provided by the side sill has a structure in which a cross-sectional grooved member (4a, 4b) joined by inserting a partition member (2) from both sides, and a bulkhead (6) formed in a closed cross-sectional space (5a, 5b) inside the cross-sectional grooved member (4a, 4b) are integrated together with the partition member (2). In other words, the cross-sectional grooved member (4a, 4b) formed by interposing the partition member (2) contains the bulkhead (6), and these have an integrated structure. Due to such a structure, the entire shock-absorbing structure (A) has high bending rigidity (bending deformation resistance against a side impact load). Therefore, local deformation around the point of input of the side collision load is suppressed, and by deforming the entire shock-absorbing structure (A) during a side collision, the collision energy absorption (EA) can be increased. In addition, the upper part of the shock-absorbing structure (A) is located on the horizontal extension of the floor cross member (8) (at least a part of the height direction of the floor cross member (8)) with the side sill inner (1b) interposed in the vehicle width direction (i.e., aligned with the floor cross member (8) in the vehicle width direction). Thus, the side collision load input to the side sill outer (1a) is transmitted to the floor cross member (8) via the upper part of the shock-absorbing structure (A) and the side sill inner (1b). The shock-absorbing structure (A) receives a reaction force from the floor cross member (8) and is compressed and deformed from the outer part of the shock-absorbing structure (A), thereby efficiently absorbing collision energy.

[0050] In the event of a side collision, the longitudinal surface (40) (pressure surface) of the outer cross-sectional grooved member (4a) receives the collision load through the side sill outer (1a), and the transverse surface (41A) (energy-absorbing surface) first bends and crushes to absorb the collision energy. After that, the transverse surface (41B) (energy-absorbing surface) of the inner cross-sectional grooved member (4b) bends and crushes to absorb the collision energy. At that time, the bulkhead (6) integrated with the cross-sectional grooved members (4a, 4b) acts together with the partition member (2) to suppress the cross-sectional collapse of the cross-sectional grooved members (4a, 4b), and the bulkhead (6) itself buckles (axial collapse) to absorb the collision energy. Additionally, the partition member (2) integrated with the cross-sectional grooved members (4a, 4b) also bends and deforms to absorb the collision energy. Also, in this shock-absorbing structure (A), since the bulkheads (6) are installed individually with the partition members (2) in between (i.e., the bulkheads (6) are divided by the partition members (2) in the vehicle width direction), the wavelength of buckling is shortened, and the load-carrying capacity of the bulkheads (6) can be improved.

[0051] <Another embodiment of shock-absorbing structure (A)>

[0052] In the side sill of the vehicle body underbody structure of the present invention, the cross-sectional grooved member (4a, 4b) (longitudinal surface portion (40)) may have a suitable gap (space) between the side sill outer (1a) and the side sill inner (1b) (longitudinal surface portion (100)) as shown in FIG. 1. In addition, the cross-sectional grooved member (4a, 4b) may be in contact with or joined to the inner surface of the side sill outer (1a) and the side sill inner (1b) (longitudinal surface portion (100)) mainly to prevent vibration. Accordingly, specific embodiments may include cross-sectional grooved members (4a, 4b) (longitudinal surface portion (40)) and side sill outer (1a) and side sill inner (1b) (longitudinal surface portion (100)), (i) being directly joined or in contact, (ii) being joined or in contact with another member (e.g., a vibration damping member), or (iii) not being joined or in contact, but facing each other with a predetermined gap. Furthermore, since shock absorption performance is improved by ensuring that the lateral collision load is transmitted to the floor cross member from the initial collision, structurally, the closer the width of the shock-absorbing structure (A) (EA member) is to the total width of the side sill, the higher the shock absorption performance. Therefore, in this regard, the structure of (i) or (ii) is preferred.

[0053] FIG. 7 is a schematic representation of an embodiment having the structure of (i) and (ii) above, and is a longitudinal cross-sectional view of the side sill in the vehicle width direction. FIG. 7(a) shows an example (in the drawing, 12 is the joint) in which each longitudinal surface (40) of the cross-sectional groove member (4a) and the cross-sectional groove member (4b) is joined by welding (typically spot welding) to the inner surface of each longitudinal surface (100) of the side sill outer (1a) and the side sill inner (1b). FIG. 7(b) also shows an example in which each longitudinal surface (40) of the cross-sectional groove member (4a) and the cross-sectional groove member (4b) is joined by an adhesive (13) (adhesive layer) to the inner surface of each longitudinal surface (100) of the side sill outer (1a) and the side sill inner (1b). In this way, when bonding with an adhesive (13), the adhesive may be applied only to a part of the bonding surface. This adhesive (13) (adhesive layer) may function as a vibration damping member to dampen vibrations.

[0054] In the case of the structure of (iii) above, if the gap between the cross-sectional grooved members (4a, 4b) (longitudinal surface portion (40)) and the side sill outer (1a) and side sill inner (1b) (longitudinal surface portion (100)) is too narrow, the two members may come into contact due to vibrations during driving, and noise or additional vibrations may become a problem. Therefore, it is desirable for the two members to face each other with a gap so that they do not come into contact due to vibrations during driving. Meanwhile, as described above, the closer the width of the shock-absorbing structure (A) (EA member) is to the total width of the side sill, the higher the shock-absorbing performance. Therefore, it is preferable that the width (We) of the shock-absorbing structure (A) in the vehicle width direction (the gap between the longitudinal face portions (40) of the two cross-sectional grooved members (4a, 4b)) be at least 60% of the width (Ws) of the side sill (1) (the gap between the longitudinal face portions (100) of the side sill outer (1a) and side sill inner (1b). FIG. 8 shows the width (We) of the shock-absorbing structure (A) and the width (Ws) of the side sill (1). If the width (We) of the shock-absorbing structure (A) or the width (Ws) of the side sill (1) differs depending on the position in the vehicle height direction, the width at the widest height position is set as Ws and We. The spacing (space) between each transverse face (41A, 41B) of the cross-sectional grooved member (4a) and the cross-sectional grooved member (4b) and the side sill (1) (each transverse face (101A, 101B) of the side sill outer (1a) and the side sill inner (1b)) can be adjusted by adjusting the overlap value in the height direction of the longitudinal face (40), the floor cross member (8), and the battery case (9), and adjusting the load input to 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 properly balanced.

[0055] FIG. 9 illustrates an example of a different arrangement of bulkheads (6) in the vehicle front-rear direction in the shock-absorbing structure (A) of the vehicle body underbody structure of the present invention, wherein the bulkheads (6) are formed at different intervals in each area in the vehicle front-rear direction. In this arrangement, the bulkheads (6) formed at multiple points spaced apart in the vehicle front-rear direction are bulkheads (6) formed in an area within the width (wa) of the floor cross member (8) in the vehicle front-rear direction. x ) and a bulkhead (6) formed in the area other than the area (an area outside the width of the floor cross member (8)). y It is composed of ). And, in the front and rear directions of the vehicle, at two or more points (two points in the embodiment of FIG. 9) in an area within the width (wa) of the floor cross member (8), bulkheads (6 x Along with the formation of ), at one or more points in the area outside the width of the floor cross member (8), a bulkhead (6) y ) is formed. Also, two adjacent bulkheads (6 x The spacing between ) is w1, bulkhead (6 x ) and the bulkhead adjacent to this (6 y When the spacing of ) is set to w2, w1 < w2. The arrangement of bulkheads (6) as described above is such that in the area within the width (wa) of the floor cross member (8), there are at least two points of bulkheads (6 x ) forms a bulkhead (6 x By reducing the spacing between ) to enhance collision characteristics, along with the bulkhead (6 in the other area) y ) and bulkhead (6 x The purpose is to reduce weight by increasing the spacing of the bulkheads (6) to suppress the number of installations. Bulkheads (6) at two or more points in the area outside the width of the floor cross member (8).y In the case of forming ), two adjacent bulkheads (6 y For the interval (w3) between ), it is desirable to make w1 < w3.

[0056] The width (wa) of the floor cross member (8) is defined as the width of the portion between the two side walls in the width direction of the floor cross member. FIG. 10 schematically shows a cross-section in the width direction of a general floor cross member (8). In the case of a floor cross member (8) having flange portions at both edges as shown in FIG. 10, the width (wa) of the floor cross member (8) is defined as 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 frame member), that is, the width between the point where the R of the flange portion begins (the boundary between a curve and a straight line). Bulkheads (6) at multiple points within the width (wa) of the floor cross member (8). x When placing ), 2 adjacent bulkheads (6 x If the gap (w1) between them is excessively small, the effect of increasing collision characteristics within the width (wa) of the floor cross member (8) is reduced, or the bulkhead (6 x It is undesirable because it leads to an unnecessary increase in the number of installed ). Therefore, bulkhead (6 x It is preferable to arrange the spacing (w1) and the width (wa) of the floor cross member (4) such that the ratio (w1 / wa) is 0.4 or greater and 1.0 or less.

[0057] Meanwhile, neighboring bulkhead (6 x ) and bulkhead (6 y ) spacing (w2) or bulkhead (6 yThe spacing (w3) between the ) is better the wider it is from the perspective of lightweighting the impact absorption structure (A), but it is desirable to make it 254 mm or less in order to secure the bending stiffness of the impact absorption structure (A) during a side collision. This 254 mm is the diameter of the impact body (pole) used in the side impact test (side pole test specified by Euro NCAP). By making the spacing (w2, w3) less than or equal to the diameter of the impact body (pole) of this test, the bending stiffness of the impact absorption structure (A) during a side collision can be secured more appropriately. Also, from the same perspective, adjacent bulkheads (6 x ) and bulkhead (6 y ) spacing (w2) or bulkhead (6 y The spacing (w3) between them is preferably about 1 / 4 to 1 / 2 of the installation spacing of the floor cross members (8) (the spacing (wb) between adjacent floor cross members (8)). For example, if the installation spacing (wb) of the floor cross members (8) is 260 mm, it is preferable that the spacing (w2) or the spacing (w3) be about 65 mm to 130 mm. Also, from the perspective of reducing the weight of the shock-absorbing structure (A), it is preferable that the spacing (w2) or the spacing (w3) be 50 mm or more. The arrangement of FIG. 9(a) is such that at one point in the area between adjacent floor cross members (8) that is outside the width of the floor cross members (8), a bulkhead (6 y This is an example of forming ), and bulkhead (6 x , 6 y ) is formed under the condition that w1 < w2. Also, the arrangement of FIG. 9(b) and FIG. 9(c) is formed by bulkheads (6) at 2 to 3 points in the area between adjacent floor cross members (8) that is outside the width of the floor cross member (8). yThis is an example of forming ), and bulkhead (6 x , 6 y ) is formed under conditions satisfying w1 < w2 and w1 < w3.

[0058] FIG. 11 shows an example of a different arrangement of bulkheads (6) in the vehicle's front-rear direction. In this embodiment of FIG. 11, similar to the embodiment of FIG. 9, bulkheads (6) are formed at different intervals in each area in the vehicle's front-rear direction. In this embodiment, in order to further increase the bending rigidity of the shock-absorbing structure (A) between the floor cross members (8), bulkheads (6) formed in an area outside the width of the floor cross members (8) are formed. y ) is configured as a bulkhead set consisting of two or more adjacent bulkheads (two bulkheads in the embodiment of FIG. 11). Accordingly, each bulkhead (6) of the embodiment of FIG. 11 y ) is composed of a bulkhead set consisting of 2 sheets of bulkhead as a set. The size of the spacing (w4) between the bulkheads constituting this bulkhead set is arbitrary, but since it is basically determined from almost the same perspective as the spacing (w1), it is sufficient to use the same conditions as the spacing (w1) described above. In this way, the bulkhead (6 y Configuring ) into a bulkhead set consisting of two or more bulkheads is, all bulkheads (6 y It may target ) or some bulkheads (6 y It is acceptable to target only ).

[0059] The arrangement of FIG. 11(a) is such that a bulkhead (6) is placed at one point in the area between adjacent floor cross members (8) that is outside the width of the floor cross member (8). y ) This is an example of forming a bulkhead set (consisting of 2 bulkheads as one set), and the bulkhead (6 x , 6 y) is formed under the condition that w1 < w2. Also, the arrangement of FIG. 11(b) and FIG. 11(c) is formed by 2 to 3 points in the area between adjacent floor cross members (8) that is outside the width of the floor cross member (8), with bulkheads (6 y ) This is an example of forming a bulkhead set (consisting of 2 bulkheads as one set), and the bulkhead (6 x , 6 y ) is formed under conditions satisfying w1 < w2 and w1 < w3.

[0060] Additionally, a bead (60) may be formed on the main body (bulkhead) of the bulkhead (6) to increase its buckling resistance (stiffness) or to decrease its buckling resistance (stiffness). FIG. 12 is a schematic representation of an embodiment in that case, showing a longitudinal cross-sectional view of the side sill in the vehicle width direction. FIG. 12(a) shows a bead (60) formed along the vehicle width direction on the main body (bulkhead) of the bulkhead (6) to increase its buckling resistance. On the other hand, FIG. 12(b) shows a bead (60) (crash bead) formed along the vertical direction on the main body (bulkhead) of the bulkhead (6) to decrease its buckling resistance. The reason for forming a bead (60) like FIG. 12(b) is as previously explained.

[0061] In the embodiments described above, such as FIG. 1, the outer side portion (cross-sectional grooved member (4a)) and the inner side portion (cross-sectional grooved member (4b)) of the shock-absorbing structure (A) have almost the same height (thickness) in the vehicle height direction and face each other with the partition member (2) in between. In particular, in these embodiments, the inner side portion and the outer side portion of the shock-absorbing structure (A) have an almost symmetrical shape with the partition member (2) in between in the vehicle width direction. In this case, the lower part of the shock-absorbing structure (A) can be formed such that one of the inner side portion and the outer side portion extends downward more than the other (i.e., a structure formed longer in the downward direction). In this case, among the lower part of the shock-absorbing structure (A), at least the portion (e) extended downward is located on the horizontal extension of the battery case (9) (at least a part of the battery case (9) in the height direction) in the vehicle width direction. That is, at least part (e) of the lower portion of the shock-absorbing structure (A) is aligned with the battery case (9) (at least a part of the battery case (9) in the height direction) in the vehicle width direction through the side sill (1). And, in the portion facing part (e) with the partition member (2) in between, a hollow space (s) is formed that is not occupied by the shock-absorbing structure (A). FIG. 13 schematically illustrates an embodiment of the vehicle body underbody structure of the present invention having such a structure, and is a longitudinal cross-sectional view in the vehicle width direction of the vehicle body underbody structure (a structural part of one of the structural parts on both sides of the vehicle body underbody) including the side sill.

[0062] The embodiment of FIG. 13(a) is such that the lower part of the shock-absorbing structure (A) is structured such that the outer side portion extends downward more than the inner side portion (i.e., a structure formed longer in the downward direction). The upper part of the shock-absorbing structure (A) is positioned on the horizontal extension of the floor cross member (8) (at least a part of the thickness (height) direction of the floor cross member (8)) in the vehicle width direction, with the outer side portion and the inner side portion facing each other with a partition member (2) in between. That is, the upper part of the shock-absorbing structure (A) is aligned with the floor cross member (8) in the vehicle width direction through the side sill (1) (side sill inner (1b)). Meanwhile, the lower part of the shock-absorbing structure (A) has an outer portion that extends downward compared to the inner portion, and this downwardly extended portion (e) is located on the horizontal extension of the battery case (9) (at least a portion of the height direction of the battery case (9)) in the vehicle width direction. That is, the downwardly extended portion (e) is aligned with the battery case (9) in the vehicle width direction through the side sill (1) (side sill inner (1b)). And, in the inner portion facing the portion (e) with the partition member (2) in between, a space portion (s) (a space portion within the closed cross-section space (3b)) that is not occupied by the shock-absorbing structure (A) is formed.

[0063] The embodiment of FIG. 13(b) has a structure in which the lower part of the shock-absorbing structure (A) is extended downwards more than the inner part (i.e., a structure formed longer in the downward direction). In the same manner as the embodiment of FIG. 13(a), the upper part of the shock-absorbing structure (A) is positioned on the horizontal extension of the floor cross member (8) (at least a part of the thickness (height) direction of the floor cross member (8)) in the vehicle width direction, with the outer part and the inner part facing each other with a partition member (2) in between. That is, the upper part of the shock-absorbing structure (A) is aligned with the floor cross member (8) in the vehicle width direction through the side sill (1) (side sill inner (1b)). Meanwhile, the lower part of the shock-absorbing structure (A) has an inner portion that extends downward compared to the outer portion, and this downwardly extended portion (e) is located on the horizontal extension of the battery case (9) (at least a portion of the height direction of the battery case (9)) in the vehicle width direction. That is, the downwardly extended portion (e) is aligned with the battery case (9) in the vehicle width direction through the side sill (1) (side sill inner (1b)). And, in the outer portion facing the portion (e) with the partition member (2) in between, a space portion (s) (a space portion within the closed cross-section space (3a)) that is not occupied by the shock-absorbing structure (A) is formed.

[0064] In the structure of the shock-absorbing structure (A) as shown in FIG. 13, collision energy absorption performance is secured by the buckling induction effect caused by the structure around the space (s). Therefore, the shock-absorbing structure (A) (inner side part or outer side part) can be made lighter by the amount of the space (s) without reducing the collision energy absorption performance of the shock-absorbing structure (A) compared to the structure of FIG. 1. To explain more specifically, for example, in the case of FIG. 13(a), the “corner R portion (f) formed by the transverse surface portion (41B) and flange portion (42) of the cross-sectional groove-shaped member (4b) in the inner part of the shock-absorbing structure (A)” and the “corner portion of the bulkhead (6) in contact with this corner R portion (f)” are in contact with the bulkhead (6) in the outer part through the partition member (2). Therefore, when a side collision occurs, buckling is induced from the area around the contact portion of the bulkhead (6) in the outer part (buckling-inducing effect), so even if the shock-absorbing structure (A) has a structure like FIG. 13(a), the collision energy absorption performance does not decrease compared to the structure of FIG. 1. Meanwhile, the shock-absorbing structure (A) (inner side part) can be made lighter by the amount of space part (s). Also, the same applies to FIG. 13(b), where the “corner R part (f) formed by the transverse surface part (41B) of the cross-sectional groove-shaped member (4a) and the flange part (42)” and the “corner part of the bulkhead (6) that contacts this corner R part (f)” in the outer side part of the shock-absorbing structure (A) are in contact with the bulkhead (6) in the inner side part through the partition member (2).Therefore, in the event of a side collision, buckling is induced even around the contact area of ​​the bulkhead (6) of the inner side part, so even if the shock absorbing structure (A) has a structure like that of FIG. 13(b), the collision energy absorption performance is not lower than that of the structure of FIG. 1. Meanwhile, the shock absorbing structure (A) (outer side part) can be made lighter by the amount of space part (s).

[0065] In the structure of the shock-absorbing structure (A) as shown in FIG. 13, if the height of the portion with the smaller height between the outer portion (cross-sectional groove-shaped member (4a)) and the inner portion (cross-sectional groove-shaped member (4b)), for example, the height of the inner portion in FIG. 13(a), is made excessively small, the plane stiffness of the bulkhead (6) within the closed cross-sectional space (5b) is reduced during a side collision, and the function of maintaining the cross-sectional shape of the inner portion of the shock-absorbing structure (A) is reduced, thereby reducing the collision energy absorption performance. Therefore, the height (H of the portion with the smaller height) shown in FIG. 14 short ) is the height (H) of the “higher side part” having a part (e) extended downward. long It is desirable not to make ) excessively small, and specifically, H short is H long It is desirable to make the size at least 40%, preferably at least 50%. Meanwhile, the difference in height (H) between the outer side part (cross-sectional grooved member (4a)) and the inner side part (cross-sectional grooved member (4b)) short and H longIf the difference (of) is excessively small, the buckling-inducing effect of the bulkhead (6) described above is relatively reduced. In short, the buckling-inducing effect and the weight reduction effect resulting from having the structure of the shock-absorbing structure (A) as in FIG. 13 are relatively reduced. Therefore, in order to fully exert the effect, the height (H of the part with the smaller height) of the “part with the smaller height” shown in FIG. 14 short ) and the height of the "higher part" (H long ) It is desirable not to make the difference of excessively small, and specifically, H short is H long It is desirable to make the size 80% or less, preferably 65% ​​or less. As shown in FIG. 14, if the height of the outer side part (cross-sectional grooved member (4a)) or the inner side part (cross-sectional grooved member (4b)) of the shock-absorbing structure (A) differs depending on the position in the vehicle width direction, the height at the position with the greatest height is the height (H of the "part with the smaller height"). short ), height of the "higher part" (H long ) .

[0066] In the embodiments described above, such as FIG. 1, the outer side portion (cross-sectional grooved member (4a)) and the inner side portion (cross-sectional grooved member (4b)) of the shock-absorbing structure (A) have a cross-sectional shape in the vehicle width direction that is rectangular (trapezoidal shape, etc.) and face each other with the partition member (2) in between. In particular, in these embodiments, the inner side portion and the outer side portion of the shock-absorbing structure (A) have a shape that is nearly symmetrical with the partition member (2) in between in the vehicle width direction. In contrast, as a lower region or a region including the lower part in the height direction of the shock-absorbing structure (A), a structure can be formed in which a recess (c) is formed facing the inner surface of the side sill (1) (side sill inner (1b) or side sill outer (1a)) in either the inner side portion or the outer side portion with the partition member (2) in between. In this case, a space (a space created by the recess (c)) is secured in the vehicle width direction between the lower part of the shock absorbing structure (A) and the side sill (1), and the lower part of the shock absorbing structure (A) where the recess (c) exists is located on the horizontal extension of the battery case (9) (at least a part of the height direction of the battery case (9)) in the vehicle width direction. That is, the lower part of the shock absorbing structure (A) where the recess (c) exists is aligned with the battery case (9) (at least a part of the height direction of the battery case (9)) in the vehicle width direction. The recess (c) can be formed to include not only the lower region in the height direction of the shock absorbing structure (A) but also the region above it (i.e., formed in the region including the lower part in the height direction of the shock absorbing structure (A)).

[0067] FIG. 15 schematically illustrates an embodiment of the vehicle body underbody structure of the present invention having such a structure, and is a longitudinal cross-sectional view in the vehicle width direction of a vehicle body underbody structure (a structural part of one of the structural parts on both sides of the vehicle body underbody). In the embodiment of FIG. 15, a recess (c) is formed in the lower region of the inner side part of the shock-absorbing structure (A), facing the inner surface of the side sill (1) (side sill inner (1b)). This recess (c) is formed by making the lower region of the inner side part (cross-sectional groove-shaped member (4b)) of the shock-absorbing structure (A) facing the side sill inner (1b) (longitudinal surface part (100) and transverse surface part (101B)) concave in a stepped shape so that a space (space created by the recess (c)) is secured in the vehicle width direction between the shock-absorbing structure (A) and the side sill (1) (side sill inner (1b)) within the closed cross-sectional space (3b). That is, this recess (c) is formed in the lower region of the inner side part of the shock-absorbing structure (A), facing the longitudinal surface part (100) and the transverse surface part (101B) of the side sill inner (1b). The lower region of the shock-absorbing structure (A) including the recess (c) is located on the horizontal extension of the battery case (9) (at least a part of the height direction of the battery case (9)) in the vehicle width direction. That is, the lower region of the shock-absorbing structure (A) including the recess (c) is aligned with the battery case (9) (at least a part of the height direction of the battery case (9)) in the vehicle width direction. In the same manner as the embodiment of FIG. 13, the upper part of the shock-absorbing structure (A) is located on the horizontal extension of the floor cross member (8) (at least a part of the thickness direction of the floor cross member (8)) in the vehicle width direction, with the outer side part and the inner side part facing each other with the partition member (2) in between.That is, the upper part of the shock-absorbing structure (A) is arranged in the vehicle width direction with the floor cross member (8) through the side sill (1) (side sill inner (1b)). The bulkhead (6) of the inner side part is configured to match the cross-sectional shape of the inner side part (cross-sectional groove-shaped member (4b)) in which the recess (c) is formed.

[0068] The recess (c) may be formed facing the inner surface of the side sill (1) (side sill outer (1a)) in the lower region or the lower region in the height direction of the outer part of the shock absorbing structure (A). For example, when the recess (c) of the shape according to FIG. 15 is formed in the lower region of the outer part of the shock absorbing structure (A), the recess (c) is formed by making the lower region of the outer part of the shock absorbing structure (A) (cross-sectional groove-shaped member (4a)) facing the side sill outer (1a) (longitudinal surface (100) and transverse surface (101B)) concave in a single shape so that a space (space created by the recess (c)) is secured in the vehicle width direction between the shock absorbing structure (A) and the side sill (1) (side sill outer (1a)) within the closed cross-sectional space (3a). That is, this recess (c) is formed in the lower region of the outer side portion of the shock absorbing structure (A), facing the longitudinal surface portion (100) and the transverse surface portion (101B) of the side sill outer (1a). The lower region of the shock absorbing structure (A) including this recess (c) is located on the horizontal extension of the battery case (9) (at least a portion of the height direction of the battery case (9)) in the vehicle width direction. That is, the lower region of the shock absorbing structure (A) including the recess (c) is aligned with the battery case (9) (at least a portion of the height direction of the battery case (9)) in the vehicle width direction.

[0069] In the structure of the shock-absorbing structure (A) as shown in FIG. 15, the impact energy absorption performance is secured by the buckling-inducing effect in which the structure around the depression (c) buckles. Therefore, the impact energy absorption performance of the shock-absorbing structure (A) can be reduced by the amount of the depression (c) without lowering the impact energy absorption performance of the shock-absorbing structure (A) compared to the structure of FIG. 1. This is explained more specifically by taking the case of FIG. 15, where the depression (c) is formed in the inner part of the shock-absorbing structure (A), as an example. Due to the formation of the depression (c), a notch following the concave shape of the depression (c) is also formed in the bulkhead (6) within the closed cross-section space (5b). For this reason, when a side collision occurs, the corner R portion (g) of the corresponding cut section of the bulkhead (6) is buckled and bent, and buckling is induced in the surrounding part of the corner R portion (g) of the cut section to absorb the collision load (buckling-inducing effect). Therefore, even if the shock-absorbing structure (A) has a structure like that of FIG. 15, the collision energy absorption performance is not lower than that of FIG. 1, and on the other hand, the shock-absorbing structure (A) (inner side part) can be made lighter by the amount of the recess (c). Also, the same applies when the recess (c) is formed in the outer side part of the shock-absorbing structure (A), and due to the formation of the recess (c), a cut section following the concave shape of the recess (c) is formed in the bulkhead (6) within the closed cross-section space (5a), and when a side collision occurs, buckling is induced from the corner R portion (g) of the corresponding cut section of the bulkhead (6). Therefore, even if the shock-absorbing structure (A) has a depression (c) formed therein, the collision energy absorption performance is not lower than that of the structure of FIG. 1, and on the other hand, the shock-absorbing structure (A) (outer side part) can be made lighter by the amount of the depression (c).

[0070] In the structure of the shock absorbing structure (A) as in FIG. 15, if the height (width) of the recess (c) in the vehicle height direction (height direction of the shock absorbing structure (A)) is excessively large, the hydraulic surface portion (longitudinal surface portion (40) of the cross-sectional grooved member (4b)) of the inner side facing the floor cross member (8) becomes narrow, and the collision characteristics on the upper part of the shock absorbing structure (A) are reduced. Therefore, it is desirable that the height (h) of the recess (c) shown in FIG. 16 in the vehicle height direction not be excessively large compared to the height (thickness) (H) of the inner side (or outer side) of the shock absorbing structure (A) in the vehicle height direction, and specifically, it is desirable that it be 90% or less, preferably 75% or less, of the height (thickness) (H) of the inner side (or outer side) of the shock absorbing structure (A) in the vehicle height direction. On the other hand, if the height (width) of the recess (c) in the vehicle height direction is excessively small, the hydraulic surface (longitudinal surface (40) of the cross-sectional groove-shaped member (4b)) of the inner side facing the floor cross member (8) widens, and the collision load is dispersed. Accordingly, since buckling is less likely to occur in the corner R portion (g) of the cutout of the bulkhead (6) corresponding to the depression (c), it becomes difficult to obtain the effect of improving collision energy absorption performance by forming the depression (c). In short, the buckling-inducing effect and the weight reduction effect resulting from having the structure of the shock-absorbing structure (A) as in FIG. 15 are relatively reduced.Therefore, in order to fully exert the effect, it is desirable that the height (h) of the recess (c) shown in FIG. 16 in the vehicle height direction not be excessively small compared to the height (thickness) (H) of the inner side (or outer side) of the shock absorbing structure (A) in the vehicle height direction, and specifically, it is desirable that it be at least 20%, preferably at least 50%, of the height (thickness) (H) of the inner side (or outer side) of the shock absorbing structure (A) in the vehicle height direction.

[0071] In addition, in the structure of the shock-absorbing structure (A) as shown in FIG. 15, if the width (depth) of the recess (c) in the vehicle width direction is excessively large, the corner R portion (g) of the cutout of the bulkhead (6) corresponding to the recess (c) becomes closer to the partition member (2), and thus it becomes difficult for buckling to occur in the surrounding part of the corner R portion (g), thereby reducing the collision energy absorption performance. Therefore, it is desirable that the width (w) of the recess (c) in the vehicle width direction shown in FIG. 16 is not excessively large compared to the width (W) in the vehicle width direction of the inner side part (or outer side part) of the shock-absorbing structure (A), and specifically, it is desirable that it be about 90% or less of the width (W) in the vehicle width direction of the inner side part (or outer side part) of the shock-absorbing structure (A). Meanwhile, if the width (depth) of the recess (c) in the vehicle width direction is made too small, the recess (c) will buckle and bend, blocking the space between the shock absorbing structure (A) and the side sill (1) and coming into contact with the side sill (1), so the contact reaction force generated on the battery case side member (90) cannot be suppressed to a low level. Therefore, it is desirable not to make the width (w) of the recess (c) in the vehicle width direction too small compared to the width (W) of the inner side part (or outer side part) of the shock absorbing structure (A) in the vehicle width direction, and specifically, it is desirable to make it at least 20% of the width (W) of the inner side part (or outer side part) of the shock absorbing structure (A) in the vehicle width direction. As shown in FIG. 16, if the height of the outer side part (cross-sectional grooved member (4a)) or the inner side part (cross-sectional grooved member (4b)) of the shock-absorbing structure (A) varies depending on the position in the vehicle width direction, the height at the position with the greatest height is set as the height (H).Also, if the width of the outer side part (cross-sectional grooved member (4a)) or the inner side part (cross-sectional grooved member (4b)) varies depending on the position in the vehicle height direction, the width at the position with the largest width is defined as the width (W). Also, if the height of the recessed part (c) varies depending on the position in the vehicle width direction, the height at the position with the largest height is defined as the height (h) of the recessed part (c). Also, if the width of the recessed part (c) varies depending on the position in the vehicle height direction, the width at the position with the largest width is defined as the width (w) of the recessed part (c).

[0072] <Impact Deformation Shape of Side Sill During Side Collision>

[0073] Based on FIG. 17, the deformation shape of the side sill during a side collision in the vehicle body undercarriage structure of the present invention is described. FIG. 17 shows the deformation shape during a side collision in a horizontal cross-section of the side sill (structure of FIG. 1) in the vehicle body undercarriage structure of the present invention in stages, where t represents the time (in seconds) from the start of the collision. First, to explain the deformation shape of the cross-section of the side sill (1) itself, at the very beginning, the upper and lower transverse surface portions (101A, 101B) (energy absorbing portion) of the side sill outer (1a) are bent and crushed to spread outward and absorb collision energy (0.002 sec ~). During the process of this side sill outer (1a) being crushed, the cross-section of the side sill (1) is prevented from spreading up and down and collapsing (cross-section collapse) by the partition member (2). Accordingly, the transverse surface portions (101A, 101B) (energy absorbing portions) of the side seal outer (1a) continue to undergo bending deformation for 0.006 to 0.014 sec and continue to absorb collision energy until they are completely crushed.

[0074] Due to the crushing and deformation of the side seal outer (1a) as described above, an impact load is transmitted to the side seal inner (1b) through the flange portion (102) of the side seal (1). Accordingly, the cross-section is not spread out in the vertical direction by the partition member (2) and collapses, and after 0.004 sec, the flange portion side of the transverse surface portion (101A, 101B) (energy absorption portion) of the side seal inner (1b) is bent and crushed in a convex shape toward the inside of the closed cross-section of the side seal (1). Due to this cross-sectional deformation of the side seal (1) itself, the impact absorption structure (A) undergoes cross-sectional deformation as follows. The longitudinal surface portion (40) of the dented side seal outer (1a) and the cross-sectional grooved member (4a) comes into contact, and a collision load is transmitted to the shock-absorbing structure (A), and a crushing (axial crushing) is initiated in which the outer portion (cross-sectional grooved member (4a) and bulkhead (6)) is deformed into a bellows shape (0.002 sec ~). As the outer portion of the shock-absorbing structure (A) (cross-sectional grooved member (4a) and bulkhead (6)) is crushed, the inner portion of the shock-absorbing structure (A) (cross-sectional grooved member (4b) and bulkhead (6)) which is continuous with the partition member (2) is pushed toward the battery case (9) side with the side seal inner (1b) (0.004 to 0.006 sec), and the inner portion of the shock-absorbing structure (A) (cross-sectional grooved member (4b) and bulkhead (6)) also begins to be crushed (0.008 to 0.018 sec).

[0075] FIG. 18 schematically shows the deformation in the longitudinal section in the vehicle width direction when a side pole collision test is performed on the side sill (structure of FIG. 1) of the vehicle body undercarriage structure of the present invention under the following conditions. FIG. 19 shows the relationship between the impact body intrusion amount and absorbed energy when deformed during this side pole collision. The test specimen has a bulkhead (6) arranged in the form shown in FIG. 9(a). In this test, it is disclosed that the outer part of the impact absorption structure (A) (cross-sectional groove-shaped member (4a) and bulkhead (6)) is mainly deformed, thereby enabling the absorption of 32 kJ of collision energy within 100 mm of the impact body intrusion amount.

[0076] Collider: R127 mm (equivalent to a diameter of 254 mm) rigid pole

[0077] Collision speed: 30.9 km / h

[0078] Collision energy: 32 kJ

[0079] In the cross-sectional deformation of the side seal structure during a side collision as described above, the shock-absorbing structure (A), which is installed within the side seal (1) via a partition member (2) and has a structure in which the cross-sectional grooved member (4a, 4b) and the bulkhead (6) are integrated together with the partition member (2), has high deformation resistance. Therefore, the side seal (1) is not locally deformed by the input load (e.g., is not deformed to bend away from the collision part), but is deformed as a whole, so the collision energy is effectively and appropriately absorbed. Accordingly, in the side sill of the vehicle body undercarriage structure of the present invention, as shown in FIG. 1, in a vehicle (especially an electric vehicle) having a battery module below the floor panel (7) between the two side sills (1), the shock-absorbing structure (A) is compressed by a load input from the vehicle width direction during a side collision and absorbs energy, thereby transferring the load to the floor cross member (8) or battery case (9), so that the load is not transferred to the battery pack (10), thereby protecting it from the impact of the collision.

[0080] <Function and effect of the shock-absorbing structure (A) in the side seal of Fig. 13>

[0081] Among the side sills of the vehicle body underbody structure of the present invention, an embodiment having a basic structure as shown in FIG. 1 is designated as “Embodiment 1,” and an embodiment having a structure as shown in FIG. 13(a) is designated as “Embodiment 2.” The results of comparing the function and operating effects of “Embodiment 2” with those of “Embodiment 1” are shown below. In both cases, the test specimens had bulkheads (6) arranged in the configuration as shown in FIG. 9(a). Furthermore, the results shown below are the same when an embodiment having a structure as shown in FIG. 13(b) is designated as “Embodiment 2,” and the “inner side” and “outer side” in the description can be understood by reversing them.

[0082] · Regarding absorbed energy

[0083] FIG. 20 shows a comparison of the deformation shape and deformation distribution during a side collision for the side seals of Embodiment 2 and Embodiment 1, where FIG. 20(a) shows Embodiment 2 and FIG. 20(b) shows Embodiment 1. When comparing Embodiment 2 of FIG. 20(a) and Embodiment 1 of FIG. 20(b), the area where buckling of the bulkhead (6) occurs and the area where the deformation is 0.09 or more (dark colored area) are at the same level.

[0084] FIG. 21 shows a comparison of the relationship between the impact body (pole) penetration amount and absorbed energy when deformed during the side pole impact, by conducting a side pole impact test on the side seals of Embodiment 2 and Embodiment 1 under the conditions of FIG. 18. According to this, the absorbed energy of both embodiments is 32.0 kJ, and the impact body penetration amount is nearly equivalent (91 mm for Embodiment 2 and 89 mm for Embodiment 1), and it is disclosed that Embodiment 2 has impact characteristics at a level equivalent to Embodiment 1. The reason for this is that although the size of the inner side part of the impact absorption structure (A) in Embodiment 2 is smaller than that of Embodiment 1, a buckling-inducing effect of the bulkhead is obtained by the specific structure (space part (s) in FIG. 13(a)) as described above. Therefore, the impact energy absorption performance is not reduced compared to Embodiment 1 (structure of FIG. 1) but is maintained at a high level.

[0085] · Regarding the effect of reducing the input load on the battery case

[0086] In the event of a side pole collision with the side sill of Embodiment 2, when a collision load is applied to the battery case (9) side and the floor cross member (8) side as shown in FIG. 22, the contact reaction force generated on the battery case side member (90) and the contact reaction force generated on the floor cross member (8) during the collision process were calculated. Also, the same contact reaction force was calculated for Embodiment 1. FIG. 23(a) shows the contact reaction force generated on the battery case side member (90), and FIG. 23(b) shows the contact reaction force generated on the floor cross member (8). As shown in FIG. 23(a), the contact reaction force generated on the battery case side member (90) rises more slowly in Embodiment 2 than in Embodiment 1, and is also 21% lower in Embodiment 2 than in Embodiment 1 (Embodiment 2: 155 kN, Embodiment 1: 195 kN). Meanwhile, as shown in FIG. 23(b), the contact reaction force generated on the floor cross member (8) rises faster in Embodiment 2 than in Embodiment 1, and is also 15% higher in Embodiment 2 than in Embodiment 1 (Embodiment 2: 261 kN, Embodiment 1: 227 kN). The result of FIG. 23 indicates that in Embodiment 2, a reduction effect on the input load to the battery case is obtained.

[0087] That is, in the event of a side collision in which a collision load is input to the side sill (1) from the outer side of the vehicle in the vehicle width direction, the following effects are obtained in the side sill of Embodiment 2. In the lower part of the shock-absorbing structure (A) of Embodiment 2, a space (s) is formed in the vehicle width direction between the outer side part and the battery case side member (90) (i.e., in the vehicle width direction, the space (s) and the lower part of the outer side part of the shock-absorbing structure (A) are located on the horizontal extension of the battery case side member (90)). Thus, the increase in contact reaction force generated on the battery case side member (90) can be slowed down. Meanwhile, the upper part of the shock-absorbing structure (A) of embodiment 2 is aligned with the floor cross member (8) in the vehicle width direction via the side sill (1), with the inner side and the outer side facing each other with the partition member (2) in between (i.e., located on the horizontal extension of the floor cross member (8) in the vehicle width direction). Thus, a load transfer path is formed to directly transfer the collision load input to the side sill (1) to the floor cross member (8), and the contact reaction force generated on the floor cross member (8) increases rapidly. Then, due to the contact reaction force generated on the floor cross member (8), the upper side, particularly the outer side, of the shock-absorbing structure (A) located on the horizontal extension of the floor cross member (8) via the side sill (1) in the vehicle width direction is efficiently compressed for the first time (see FIG. 20(a)), and absorbs the side collision load. After that, as the side collision progresses and the side seal (1) (the upper side of the shock-absorbing structure (A)) is deformed, the contact reaction force generated on the battery case side member (90) begins to increase, thereby reducing the peak load input to the battery case (9) and suppressing the deformation of the battery case (9).

[0088] <Function and effect of the shock-absorbing structure (A) in the side seal of Fig. 15>

[0089] Among the side sills of the vehicle body undercarriage structure of the present invention, an embodiment having a basic structure as shown in FIG. 1 is designated as “Embodiment 1,” and an embodiment having a structure as shown in FIG. 15 is designated as “Embodiment 3.” The results of comparing the function and operating effects of “Embodiment 3” with those of “Embodiment 1” are shown below. In both cases, the test specimens had bulkheads (6) arranged in the configuration shown in FIG. 9(a). The results shown below are the same when an embodiment having a recess (c) formed in the outer side is designated as “Embodiment 3,” and the “inner side” and “outer side” in the description can be understood by reversing them.

[0090] · Regarding absorbed energy

[0091] FIG. 24 shows a comparison of the deformation shape and deformation distribution during a side collision for the side seals of Embodiment 3 and Embodiment 1 (the same embodiment as FIG. 20(b)), where FIG. 24(a) shows Embodiment 3 and FIG. 24(b) shows Embodiment 1. When comparing Embodiment 3 of FIG. 24(a) and Embodiment 1 of FIG. 24(b), the area where buckling of the bulkhead (6) occurs and the area where the deformation is 0.09 or more (dark colored area) are at the same level.

[0092] FIG. 25 shows a comparison of the relationship between the impactor (pole) penetration amount and absorbed energy when deformed during the side pole impact, by conducting a side pole impact test on the side seals of Embodiment 3 and Embodiment 1 under the conditions of FIG. 18. According to this, although the impactor penetration amount of Embodiment 3 is slightly longer (96 mm for Embodiment 3 and 89 mm for Embodiment 1), the absorbed energy of both is 32.0 kJ, and it is disclosed that Embodiment 3 has impact characteristics at a level equivalent to that of Embodiment 1. This is because, in Embodiment 3, the buckling-inducing effect of the bulkhead is obtained by the specific structure (the depression (c) in FIG. 15) as described above, so the impact energy absorption performance is not reduced compared to Embodiment 1 (structure of FIG. 1) but is maintained at a high level.

[0093] · Regarding the effect of reducing the input load on the battery case

[0094] In the event of a side pole collision with the side sill of Embodiment 3, when a collision load is applied to the battery case (9) side and the floor cross member (8) side as shown in FIG. 26, the contact reaction force generated on the battery case side member (90) and the contact reaction force generated on the floor cross member (8) during the collision process were calculated. In addition, the same contact reaction force was calculated for Embodiment 1. FIG. 27(a) shows the contact reaction force generated on the battery case side member (90), and FIG. 27(b) shows the contact reaction force generated on the floor cross member (8). As shown in FIG. 27(a), the contact reaction force generated on the battery case side member (90) rises more slowly in Embodiment 3 than in Embodiment 1, and is 66% lower in Embodiment 3 than in Embodiment 1 (Embodiment 3: 67 kN, Embodiment 1: 195 kN). Meanwhile, as shown in FIG. 27(b), the contact reaction force generated on the floor cross member (8) is 16% higher in Embodiment 3 than in Embodiment 1 (Embodiment 3: 264 kN, Embodiment 1: 227 kN), but is almost the same up to the impactor penetration amount of about 80 mm. The result of FIG. 27 indicates that in Embodiment 3, a reduction effect of the input load on the battery case is obtained.

[0095] That is, in the event of a side collision in which a collision load is input to the side sill (1) from the outer side of the vehicle in the width direction, the side sill of Embodiment 3 provides the following effects. Since the lower part of the shock-absorbing structure (A) of Embodiment 3 has a recessed portion (c) formed in its inner side, the increase in contact reaction force generated on the battery case side member (90) can be slowed down. In addition, the corner R portion (g) of the cutout of the bulkhead (6) corresponding to the recessed portion (c) is buckled and bent, and buckling is induced in the surrounding part of the corner R portion (g) to continue absorbing the collision load. Accordingly, even if the side collision progresses and the side sill (1) is deformed, the contact reaction force generated on the battery case side member (90) can be kept low, and the load input to the battery case (9) can be significantly reduced. Thus, deformation of the battery case (9) can be suppressed.

[0096] Examples

[0097] To verify the effect of the side sill structure in the vehicle body underbody structure of the present invention, a crash test was conducted using FEM analysis as follows.

[0098] [Example 1]

[0099] FIGS. 28(a) to 28(e) show the test specimens and test conditions of the inventive example and comparative example. In each of FIGS. 28(a) to 28(e), the left drawing is a cross-sectional view of the side sill in the vehicle width direction, and the right drawing is a horizontal cross-sectional view of the side sill, showing the collision position of the impactor (pol) against the side sill and the position of the floor cross member. In this collision test, the side sill and the impact absorbing member (in the inventive example, the impact absorbing structure (A)) among the vehicle side structures were selected as test specimens, and the collision energy absorption characteristics were evaluated. In addition, the floor cross member or battery case side member adjacent to the side sill was used as a rigid jig for fixing the test specimen, and the load transmitted to the jig was evaluated by the contact reaction force.

[0100] In the crash test, as shown in FIG. 28, a crasher (pole) with a curvature radius R127 mm perpendicular to the longitudinal direction of the test specimen was crashed at an initial speed of 30.9 km / h and a maximum intrusion amount of 100 mm. The crash energy at this time was 32 kJ. The fixing jig for the side sill on the opposite side of the crasher is composed of a floor cross member mock part (corresponding to the floor cross member (8)) simulating the vehicle body undercarriage structure shown in FIG. 1, a battery case wall part (corresponding to the battery case side member (90)), and a battery case bottom (corresponding to the battery case bottom plate (91) and mounting flange (92)), and the battery case bottom is fixed to the side sill inner by a fixing bolt (corresponding to the fixing bolt (11)). The width (wa) of the floor cross member mock part in the vehicle front-rear direction was set to 80 mm.

[0101] Table 1 shows the strength level and plate thickness of the steel plate used for each member of the test specimens of the inventive example and comparative example.

[0102]

[0103] The test specimen of Invention Example 1 shown in FIG. 28(a) has, in the shock-absorbing structure (A), bulkheads (6) at two points in an area within the width of a floor cross member mock part (corresponding to the floor cross member (8)). x A bulkhead (6) formed by a bulkhead set consisting of two or more bulkheads formed adjacently in an area outside the width of the floor cross member mock part on both sides thereof, along with forming a ) y It formed ). Two adjacent bulkheads (6 x The spacing (w1) between them was set to 35 mm, and the ratio (w1 / wa) of the spacing (w1) to the width (wa) of the floor cross member was set to 0.44. Also, the bulkhead (6 x ) and the bulkhead adjacent to this (6 y The spacing (w2) of ) is greater than w1 and is 254 mm or less, and was set to 125 mm, which is about half of the assumed installation spacing of floor cross members (spacing between adjacent floor cross members (wb)) of 260 mm. In addition, bulkhead (6 y The spacing (w4) between the bulkheads constituting the bulkhead set was set to 35 mm, which is the same as the spacing (w1).

[0104] The test specimen of Invention Example 2 shown in FIG. 28(b) is the bulkhead (6) of Invention Example 1. yBy removing the ) in the shock-absorbing structure (A), bulkheads (6) are formed only at two points within the width of the floor cross member mock part (equivalent to the floor cross member (8)). The test specimen of Comparative Example 1 shown in FIG. 28(c) is a test specimen in which bulkheads (6) are removed from the structure of the shock-absorbing structure (A) of Invention Example 2. The test specimen of Comparative Example 2 shown in FIG. 28(d) is a test specimen in which only bulkheads are formed inside the side seal, and bulkheads are formed at two points within the width of the floor cross member mock part. The test specimen of Comparative Example 3 shown in FIG. 28(e) is a test specimen in which partition members or shock-absorbing members are not placed inside the side seal, and only the side seal is used.

[0105] FIGS. 29a(a) to 29b(e) illustrate the relationship between the amount of penetration of the impactor (punch) into the side seal during a collision test and the force (punch reaction force) received by the impactor (punch), as well as the trend of absorbed energy with respect to the amount of penetration of the impactor (punch), for the inventive example and comparative example. The punch refers to the rigid pole, which is the impactor in the side pole collision test (Fig. 18) described earlier. In addition, the absorbed energy was calculated by subtracting the kinetic energy calculated from the velocity of the impactor from the collision energy (32 kJ). Since the stroke of the impactor is a maximum of 100 mm, in Inventive Example 1 shown in FIG. 29a(a), the impactor stops before reaching the maximum penetration amount of 100 mm (96 mm), and the absorbed energy due to the side seal structure of Inventive Example 1 was 32.0 kJ. On the other hand, Invention Example 2 and Comparative Examples 1 to 3 shown in FIGS. 29a(b) to 29b(e) all reached a maximum stroke of 100 mm of the impactor before reaching an absorbed energy of 32.0 kJ (the absorbed energy of Invention Example 1).

[0106] Figure 30 shows a comparison of the absorbed energy at the maximum penetration of the impactor for the inventive example and the comparative example. The maximum penetration amount was 96 mm for Inventive Example 1, and 100 mm for Inventive Example 2 and Comparative Examples 1 to 3 (maximum penetration amount of the impactor). The absorbed energy of Inventive Example 1 was 6.7 times that of Comparative Example 3 with only a side seal, 3.0 times that of Comparative Example 1 without a bulkhead, 3.4 times that of Comparative Example 2 with only a bulkhead, and approximately 1.6 times that of the total of Comparative Examples 1 and 2, which was 20.1 kJ. Also, since Invention Example 2 has fewer bulkheads installed in the front-rear direction of the vehicle than Invention Example 1, the absorbed energy is lower (19% lower) than Invention Example 1, but it is 6.0 times that of Comparative Example 3, 2.4 times that of Comparative Example 1, 2.7 times that of Comparative Example 2, and about 1.3 times the sum of Comparative Example 1 and Comparative Example 2.

[0107] From the results of the above Inventive Examples 1 and 2 and Comparative Examples 1 to 3, it was confirmed that the side sill structure (vehicle body underbody structure) of the present invention provides excellent collision characteristics that exceed the effect of simply summing the collision energy absorption performance of Comparative Example 1 (a side sill structure in which a partition member is joined from both sides using a pair of cross-sectional groove-shaped members) and Comparative Example 2 (a side sill structure in which a bulkhead is installed within the side sill). Furthermore, from the results of Inventive Examples 1 and 2, it was confirmed that collision characteristics are 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 front-rear direction of the vehicle.

[0108] [Example 2]

[0109] Among the side sills of the vehicle body underbody structure of the present invention, an embodiment having a basic structure as shown in FIG. 1 was designated as “Embodiment 1,” an embodiment having a structure as shown in FIG. 13(a) as “Embodiment 2,” and an embodiment having a structure as shown in FIG. 15 as “Embodiment 3,” and the following crash tests were performed on these. In all cases, the test specimen had a bulkhead (6) arranged in the form shown in FIG. 9(a). As the test specimen, the shape of the longitudinal cross-section in the vehicle width direction of the shock-absorbing structure (A) of the test specimen of [Embodiment 1] described above was changed to the shape shown in FIG. 31a(a) to FIG. 31d(k) (Invention Examples 3 to 13). The test conditions were the same as in [Example 1], and the collision absorption energy (Fig. 32) at a collision body intrusion amount (stroke) of 0–100 mm and the contact reaction force generated on the battery case side member (90) (Fig. 33) of the collision test specimen were evaluated. The test specimens of Invention Examples 3–5 related to Example 1, shown in Figs. 31a(a)–(c), are designed such that, unlike the test specimen of Invention Example 1 in [Example 1] where the partition member (2) is vertical, the partition member (2) is inclined in the vehicle height direction. In addition, the test specimens of Invention Example 4 and Invention Example 5 have a reduced height of the shock-absorbing structure (A) compared to the test specimen of Invention Example 3, with the height set to 75% (Invention Example 4, FIG. 31(b)) and 50% (Invention Example 5, FIG. 31a(c)) of the height of Invention Example 3, respectively.

[0110] The test specimens of Invention Examples 6 to 8 regarding Embodiment 2 shown in FIGS. 31b(d) to (f) have a reduced height of the inner or outer portion of the shock-absorbing structure (A) of the test specimen of Invention Example 3. That is, in the lower part of the shock-absorbing structure (A), one of the inner portion and the outer portion separated by the partition member (2) is extended downward more than the other. The test specimens of Invention Examples 6 and 7 have a reduced height of the inner portion of the shock-absorbing structure (A) compared to the test specimen of Invention Example 3, with the height set to 75% (Invention Example 6, FIG. 31b(d)) and 50% (Invention Example 7, FIG. 31b(e)), respectively, of the height of Invention Example 3. In addition, the test specimen of Invention Example 8 has a smaller height of the outer side portion of the shock-absorbing structure (A) compared to the test specimen of Invention Example 3, and is set to 50% of the height of Invention Example 3 (Fig. 31b(f)).

[0111] The test specimens of Invention Examples 9 to 13 relating to Embodiment 3, shown in FIG. 31c(g) to FIG. 31d(k), are formed with a recess (c) facing the inner surface of the side seal (1) in the lower region or the lower region in the height direction of the inner region of the shock-absorbing structure (A) so as to secure a space in the vehicle width direction between the inner region of the shock-absorbing structure (A) and the side seal (1) for the test specimen of Invention Example 3. Among these, the test specimens of Invention Examples 9 to 11 had the width (depth) of the recessed portion (c) in the vehicle width direction set to 23% of the width of the inner part of the shock absorbing structure (A) in the vehicle width direction, and the height of the recessed portion (c) set to 34% to 66% of the height (thickness) of the inner part of the shock absorbing structure (A) in the vehicle height direction. In addition, the test specimens of Invention Examples 12 and 13 had the width (depth) of the recessed portion (c) in the vehicle width direction set to 41% of the width of the inner part of the shock absorbing structure (A) in the vehicle width direction, and the height of the recessed portion (c) set to 34% and 43% of the height (thickness) of the inner part of the shock absorbing structure (A) in the vehicle height direction.

[0112] FIG. 32 shows the collision absorption energy in Invention Examples 3 to 13. For comparison, the collision absorption energy of Invention Example 1 and Comparative Examples 1 to 3 of [Example 1] is also shown. From the results in FIG. 32, it was confirmed that the collision characteristics of Invention Examples 3 to 13 were improved compared to Comparative Examples 1 to 3. The average of Embodiment 1 (Invention Examples 1, 3 to 5) was 31.8 kJ, the average of Embodiment 2 (Invention Examples 6 to 8) was 31.1 kJ, and the average of Embodiment 3 (Invention Examples 9 to 13) was 31.9 kJ, and the collision energy absorption amount was at an equivalent level in all embodiments. FIG. 33 shows the magnitude of the contact reaction force generated on the battery case side member (90) in Invention Examples 3 to 13. For comparison, the contact reaction force of Invention Example 1 and Comparative Examples 1 to 3 of [Example 1] is also shown. From the results of FIG. 33, it was confirmed that all Invention Examples 3 to 13 can significantly reduce the contact reaction force generated on the battery case (9) compared to Comparative Examples 1 to 3. In addition, the average of Embodiment 1 (Invention Examples 1, 3 to 5) is 181 kN, the average of Embodiment 2 (Invention Examples 6 to 8) is 131 kN, and the average of Embodiment 3 (Invention Examples 9 to 13) is 69 kN, and it was confirmed that Embodiment 2 can reduce the contact reaction force generated on the battery case (9) by about 30% compared to Embodiment 1, and Embodiment 3 can further reduce it by more than 39% compared to Embodiment 2.

[0113] Industrial applicability

[0114] According to the present invention, in a vehicle body understructure including a side sill, it is possible to provide a vehicle body understructure and a side sill structure that obtain high collision energy absorption characteristics with a small amount of collision deformation while suppressing weight increase caused by structural members. Furthermore, according to the present invention, it is possible to provide a vehicle body understructure and a side sill structure that can reduce the load input to a battery module due to deformation of the side sill. Explanation of the symbols

[0115] 1 : Side sill 1a : Side sill outer 1b: Side sill inner 2 : Partition member 3, 3a, 3b: Closed section space 4a, 4b: Cross-sectional grooved member 5a, 5b: 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: Glue 40 : Longitudinal surface 41A, 41B: Transverse surface 42 : Flange section 60 : Bead 61 : Flange section 70 : Flange section 90: Battery case side member 91 : Battery case bottom plate 92 : Mounting flange 100 : Longitudinal surface 101A, 101B: Transverse surface 102 : Flange section A: Shock-absorbing structure e : Part extended downwards c : depression s : space f, g : Corner R part

Claims

Claim 1 A vehicle body underbody structure comprising: side sills (1) arranged along the vehicle length direction on both sides of the lower body; a floor cross member (8) arranged between the two side sills (1) with both sides fixed to the upper portions of the two side sills (1); and a battery case (9) arranged below the floor cross member (8) with both sides facing the lower portions of the two side sills (1). The side sills (1) have a structure in which a partition member (2) vertically penetrates a closed cross-sectional space (3) within the side sills (1), and the closed cross-sectional space (3) is divided into two closed cross-sectional spaces (3a) and (3b) in the vehicle width direction by the partition member (2). Additionally, the side sills (1) are joined to the partition member (2) in a state where the partition member (2) is fitted from both sides within the closed cross-sectional spaces (3a) and (3b), and the partition member (2) The shock absorbing structure (A) comprises a pair of cross-sectional groove-shaped members (4a) and (4b) that each form a closed cross-sectional space (5a) and (5b) between them, and bulkheads (6) formed at multiple points spaced apart in the front-rear direction of the vehicle within each closed cross-sectional space (5a) and (5b) as members that partition the closed cross-sectional space (5a) and (5b) by being formed along the vehicle width direction within each closed cross-sectional space (5a) and (5b); wherein, in the shock absorbing structure (A), the bulkheads (6) within the closed cross-sectional space (5a) and the bulkheads (6) within the closed cross-sectional space (5b) are formed facing each other in the vehicle width direction with a partition member (2) in between, and each bulkhead (6) is joined to at least the cross-sectional groove-shaped member (4a) or the cross-sectional groove-shaped member (4b); and the upper part of the shock absorbing structure (A) is an inner side part and The outer side portion faces each other with the partition member (2) in between, and is located on the horizontal extension of the floor cross member (8) in the vehicle width direction, and the bulkhead (6) is,A bulkhead (6) formed in an area that is the width of the floor cross member in the front-rear direction of the vehicle. x ) and a bulkhead (6) formed in an area outside the width of the floor cross member y It is composed of ), and in the front-rear direction of the vehicle, at two or more points in the area within the width of the floor cross member, bulkheads (6 x Along with the formation of ), bulkhead (6) at one or more points in the area outside the width of the floor cross member y ) is formed, and two neighboring bulkheads (6 x The spacing of ) is w1, bulkhead (6 x ) and the bulkhead adjacent to this (6 y A vehicle body undercarriage structure in which, when the spacing of ) is w2, w1 < w2. Claim 2 delete Claim 3 In claim 1, at least a portion of the bulkhead (6 y A vehicle body underbody structure comprising a bulkhead set consisting of two or more bulkheads formed adjacently. Claim 4 In claim 1, each bulkhead (6) is joined to a cross-sectional grooved member (4a) or a cross-sectional grooved member (4b) and a partition member (2), respectively, of the vehicle body undercarriage structure. Claim 5 In claim 1, the lower part of the shock-absorbing structure (A) has one of the inner side portion and the outer side portion extending downward more than the other, with the partition member (2) in between, and at least the portion (e) extending downward among the lower part of the shock-absorbing structure (A) is located on the horizontal extension of the battery case (9) in the vehicle width direction, the lower body structure of the vehicle. Claim 6 In claim 1, the lower part of the shock-absorbing structure (A) is located on the horizontal extension of the battery case (9) in the vehicle width direction, and a recess (c) is formed facing the inner surface of the side sill (1) in either the inner side part or the outer side part separated by the partition member (2) as a lower area or an area including the lower part in the height direction of the shock-absorbing structure (A). Claim 7 A vehicle body understructure according to any one of claims 1 and 3 to 5, wherein the longitudinal surface portion (40) of each cross-sectional groove-shaped member (4a), (4b) and the longitudinal surface portion (100) of the side sill (1) facing it are (i) directly joined or in contact, (ii) joined or in contact with another member interposed therebetween, or (iii) not joined or in contact but facing each other with a predetermined gap. Claim 8 A vehicle body underbody structure according to any one of claims 1 and 3 to 6, wherein the metal plate constituting the shock-absorbing structure (A) has a yield strength less than or equal to the yield strength of the metal plate constituting the floor cross member and a tensile strength of 500 MPa or higher. Claim 9 In claim 7, the metal plate constituting the shock-absorbing structure (A) has a yield strength less than or equal to the yield strength of the metal plate constituting the floor cross member and a tensile strength of 500 MPa or higher, in the underbody structure of a vehicle. Claim 10 A side sill structure of a vehicle having a partition member (2) that vertically penetrates a closed cross-sectional space (3) within a side sill (1), wherein the closed cross-sectional space (3) is divided into two closed cross-sectional spaces (3a), (3b) in the vehicle width direction by the partition member (2), wherein the shock absorbing structure comprises: a pair of cross-sectional groove-shaped members (4a), (4b) that are joined to the partition member (2) with the partition member (2) inserted from both sides within the closed cross-sectional spaces (3a), (3b) and form a closed cross-sectional space (5a), (5b) respectively between the partition member (2); and bulkheads (6) formed at multiple points spaced apart in the vehicle front-rear direction within each closed cross-sectional space (5a), (5b) as members that divide the closed cross-sectional spaces (5a), (5b) by being formed along the vehicle width direction within each closed cross-sectional space (5a), (5b). (A) having, in the shock-absorbing structure (A), the bulkhead (6) in the closed cross-section space (5a) and the bulkhead (6) in the closed cross-section space (5b) are formed facing each other in the vehicle width direction with the partition member (2) in between, and each bulkhead (6) is joined to at least the cross-section groove member (4a) or the cross-section groove member (4b), and the bulkhead (6) is formed in an area within the width of the floor cross member in the vehicle front-rear direction. x ) and a bulkhead (6) formed in an area outside the width of the floor cross member y It is composed of ), and in the front-rear direction of the vehicle, at two or more points in the area within the width of the floor cross member, bulkheads (6 x Along with the formation of ), bulkhead (6) at one or more points in the area outside the width of the floor cross member y ) is formed, and two neighboring bulkheads (6 x The spacing of ) is w1, bulkhead (6 x ) and the bulkhead adjacent to this (6 y A side sill structure of a vehicle in which, when the spacing of ) is w2, w1 < w2. Claim 11 In claim 10, each bulkhead (6) is joined to a cross-sectional grooved member (4a) or a cross-sectional grooved member (4b) and a partition member (2), respectively, in a side sill structure of a vehicle. Claim 12 delete Claim 13 A side sill structure of an automobile according to claim 10, wherein at least some of the bulkheads (6y) are composed of a bulkhead set consisting of two or more bulkheads formed adjacently. Claim 14 A side sill structure of an automobile according to claim 10, wherein the gap (w2) is 254 mm or less. Claim 15 In claim 10, the longitudinal surface portion (40) of each cross-sectional groove-shaped member (4a) and (4b) and the longitudinal surface portion (100) of the side sill (1) facing it are any of the following: (i) directly joined or in contact, (ii) joined or in contact with another member interposed, or (iii) not joined or in contact, but facing each other with a predetermined gap. Claim 16 In claim 10, the metal plate constituting the shock-absorbing structure (A) has a yield strength less than or equal to the yield strength of the metal plate constituting the floor cross member and a tensile strength of 500 MPa or higher, in a side sill structure of an automobile. Claim 17 In claim 10, a side sill structure of a vehicle in which a bead (60) is formed on a bulkhead (6). Claim 18 In any one of claims 10, 11 and 13 to 17, the shock-absorbing structure (A) is a side sill structure of a vehicle in which one of the inner side portion and the outer side portion separated by a partition member (2) extends further in the vehicle height direction than the other. Claim 19 A side sill structure of an automobile according to any one of claims 10, 11 and 13 to 17, wherein a recess (c) is formed in the shock-absorbing structure (A) facing the inner surface of the side sill (1).

Images