Vehicle underbody structure

Abstract

The reinforcement for the side sills increases the amount of energy absorbed from side impacts. [Solution] The lower body structure 1 of the vehicle 100 has a floor panel 2, a side sill 3, and a reinforcement 30 that is located inside the side sill 3 and extends in the front-rear direction. The reinforcement 30 has an upper wall 31, a lower wall 32, an outer wall 33, and an inner wall 34. The reinforcement 30 further has one or more vertical walls 35 that connect the upper wall 31 and the lower wall 32 between the outer wall 33 and the inner wall 34 and extend in the front-rear direction, and the internal space S is divided in the vehicle width direction by the vertical walls 35 to divide it into a plurality of closed cross-sectional sections S1 to S3. At least one of the upper wall 31 and the lower wall 32 has a groove 36 that extends in the front-rear direction along the entire length of the reinforcement 30 at at least one of the positions where the vertical wall 35 is connected.

Description

Technical Field

[0001] The present invention relates to a lower body structure of a vehicle.

Background Art

[0002] Patent Document 1 discloses a side sill reinforcement member (hereinafter referred to as a reinforcement) disposed within an internal space of a side sill extending in the vehicle longitudinal direction. This reinforcement extends in the vehicle longitudinal direction and has a plurality of closed cross-sectional structures that are closed in the vehicle width direction and the vehicle vertical direction and surround a plurality of closed spaces arranged in the vehicle width direction. The reinforcement acts as an energy absorption member that absorbs collision energy by collapsing in the vehicle width direction when a side impact load acts on the side sill from the outside in the vehicle width direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a lower body structure of a vehicle that can increase the amount of energy absorbed by side impact energy by a reinforcement for a side sill.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a floor panel, a pair of left and right side sills extending in the longitudinal direction along both side edges of the floor panel, a pair of left and right reinforcements disposed inside each of the pair of left and right side sills and extending in the longitudinal direction along the side sills and The aforementioned reinforcement is, It forms the top surface, and extends in the front-to-back direction, with an upper wall and It forms the lower surface, and extends in the front-to-back direction, with a lower wall and The outer edges of the upper and lower walls, respectively, in the vehicle width direction are connected, and the outer wall extends in the front-rear direction, The inner edges of the upper and lower walls, respectively, in the vehicle width direction are connected, and the inner wall extends in the front-rear direction. It has, The reinforcement further has one or more vertical walls that extend in the front-rear direction, connecting the upper wall and the lower wall between the outer wall and the inner wall, and these one or more vertical walls divide the interior space defined by the upper wall, the lower wall, the outer wall, and the inner wall into a plurality of closed cross-sectional sections in the vehicle width direction. The present invention provides a lower body structure for a vehicle, wherein at least one of the upper wall and the lower wall has a groove extending in the front-rear direction along the entire length of the reinforcement at at least one of the positions where the one or more vertical walls are connected. [Effects of the Invention]

[0006] According to the present invention, since the reinforcement has a groove in at least one of the upper wall and the lower wall, when subjected to a side impact load from the outside in the vehicle width direction, stress is concentrated in the groove, making it easy to cause valley-fold deformation in the portion of the upper wall and lower wall where the groove is formed, which is convex inward in the closed cross-section in the vertical direction.

[0007] Since a vertical wall is located inside the groove, the groove is less likely to be submerged into the interior space by valley-fold deformation. Therefore, in the closed section, deformation can occur in the upper or lower wall such that the portion continuous with the groove inclins outward, starting from the valley-fold deformation in the groove. Moreover, in the closed section, since a vertical wall, outer wall, or inner wall is located inside the end opposite to the end where the groove is formed, this opposite end is also less likely to deform inward or outward of the closed section.

[0008] As a result, in the closed section, a mountain-fold deformation can be induced on the upper or lower wall where the groove is formed, such that the middle portion in the width direction becomes convex outward from the closed section. Therefore, by inducing a mountain-fold deformation in the closed section, the reinforcement can be efficiently crushed in the width direction while suppressing incomplete crushing. Consequently, the amount of energy absorbed by the reinforcement against lateral impact loads can be increased. [Brief explanation of the drawing]

[0009] [Figure 1] A plan view of the lower body structure of a vehicle according to one embodiment of the present disclosure. [Figure 2] Cross-sectional view of the area around the side sill along line II-II in Figure 1. [Figure 3] A single perspective view of the reinforcement. [Figure 4A] A diagram illustrating the deformation behavior of reinforcement during a side impact. [Figure 4B] Following Figure 4A, this figure schematically illustrates the deformation behavior of the reinforcement during a side impact. [Modes for carrying out the invention]

[0010] The lower body structure 1 of a vehicle 100 according to one embodiment of this disclosure will be described below with reference to the attached drawings. The following description is essentially illustrative and is not intended to limit the present invention, its applications, or its uses.

[0011] Figure 1 is a plan view of the lower body structure 1 of the vehicle 100 according to this embodiment. In the following description, the longitudinal direction, width direction, and vertical direction of the vehicle 100 may be referred to as the "longitudinal direction," "width direction," and "vertical direction" of the lower body structure 1 and its components, respectively. In the following description, the side of the vehicle's centerline in the width direction may be referred to as the inner side in the width direction, and the side opposite the vehicle's centerline in the width direction may be referred to as the outer side in the width direction. The width direction also coincides with the left-right direction of the vehicle.

[0012] As shown in FIG. 1, the lower body structure 1 of the vehicle 100 has a floor panel 2 that constitutes the floor surface inside the vehicle compartment, and a pair of left and right side sills 3 that extend in the front-rear direction along the left and right side edges of the floor panel 2. The vehicle 100 of the present embodiment is an electric vehicle such as an electric car and does not include an internal combustion engine and a transmission. Therefore, an exhaust pipe and a propeller shaft are not arranged below the floor panel 2, and a so-called tunnel portion that protrudes upward in the vehicle width direction and extends in the front-rear direction is not formed.

[0013] The floor panel 2 is a press-formed product made of a steel plate. The floor panel 2 has an outer flange 2a (see also FIG. 2) that extends upward from the outer end portion in the vehicle width direction. The floor panel 2 extends substantially flat in the horizontal direction. A battery case 4 (see FIG. 2) is arranged between the pair of left and right side sills 3 on the lower surface side of the floor panel 2.

[0014] On the upper surface of the floor panel 2, a first cross member 5 and a second cross member 6 that extend in the vehicle width direction are arranged. The first cross member 5 is a seat cross member to which a front seat (not shown) is attached. The second cross member 6 is located behind the first cross member 5.

[0015] The first cross member 5 and the second cross member 6 are each press-formed products made of a steel plate, and are formed in a hat-shaped cross section that opens downward, and have front flanges 5a, 6a and rear flanges 5b, 6b at the lower edge portion. The first cross member 5 and the second cross member 6 are joined to the floor panel 2 by spot welding via the front flanges 5a, 6a and the rear flanges 5b, 6b. The first cross member 5 and the second cross member 6 cooperate with the floor panel 2 to form a closed cross-section structure that extends in the vehicle width direction.

[0016] At both ends in the vehicle width direction of the first cross member 5, seat brackets 7 for fixing a front seat (not shown) are attached. The seat bracket 7 is a press-formed product made of a steel plate. The seat bracket 7 is joined to each of the first cross member 5 and the side sill 3 by spot welding. Therefore, both ends in the vehicle width direction of the first cross member 5 are connected to a pair of left and right side sills 3 via the seat brackets 7.

[0017] Similarly, gussets 8 are attached to both ends of the second cross member 6. The gusset 8 is a press-formed product made of a steel plate. The gusset 8 is joined to each of the second cross member 6 and the side sill 3 by spot welding. Therefore, both ends in the vehicle width direction of the second cross member 6 are connected to a pair of left and right side sills 3 via the gussets 8.

[0018] FIG. 2 is a longitudinal sectional view along the vehicle width direction around a portion connected to the second cross member 6 of the left side sill 3 along the line II-II in FIG. 1. As shown in FIG. 2, the side sill 3 includes a side sill inner 10 formed in a hat-shaped cross section open to the outside in the vehicle width direction and a side sill outer 20 formed in a hat-shaped cross section open to the inside in the vehicle width direction. The side sill inner 10 and the side sill outer 20 are press-formed products made of a steel plate.

[0019] The side sill inner 10 has an inner vertical wall 11 extending vertically in the vehicle width direction on the inner side, an inner upper wall 12 extending outward in the vehicle width direction from the upper end of the inner vertical wall 11, an inner lower wall 13 extending outward in the vehicle width direction from the lower end of the inner vertical wall 11, an inner upper flange 14 extending upward from the outer end in the vehicle width direction of the inner upper wall 12, and an inner lower flange 15 extending downward from the outer end in the vehicle width direction of the inner lower wall 13.

[0020] The inner vertical wall 11 extends vertically from the lower surface side to the upper surface side of the floor panel 2. The outer flange 2a of the floor panel 2 is joined to the inner side wall 11 by spot welding.

[0021] The side sill outer 20 includes an outer vertical wall 21 extending vertically on the outer side in the vehicle width direction, an outer upper wall 22 extending outward in the vehicle width direction from the upper end of the outer vertical wall 21, an outer lower wall 23 extending outward in the vehicle width direction from the lower end of the outer vertical wall 21, an outer upper flange 24 extending upward from the outer end in the vehicle width direction of the outer upper wall 22, and an outer lower flange 25 extending downward from the outer end in the vehicle width direction of the outer lower wall 23.

[0022] The side sill 3 is constructed as a closed cross-sectional structure extending in the front-rear direction by joining the side sill inner 10 and the side sill outer 20 to each other by spot welding at their respective upper flanges 14, 24 and lower flanges 15, 25.

[0023] Inside the side sill 3 are a reinforcement 30 and a rain bracket 40 that secures the reinforcement 30 to the side sill 3. As shown in Figure 1, the reinforcement 30 extends in the front-rear direction along approximately the entire length of the side sill 3. In this embodiment, the reinforcement 30 extends forward beyond the front end of the side sill 3, with its front end located inside the lower part of the hinge pillar 9 (only the inner pillar is shown in Figure 1).

[0024] The rain bracket 40 is a press-formed product made of steel plate. The rain bracket 40 is provided at multiple locations on the inside of the side sill 3 that are spaced apart in the front-rear direction. For example, the rain bracket 40 may be provided on the lower part of the hinge pillar 9 and the B pillar (not shown) that extends in the front-rear direction so as to connect to the side sill 3.

[0025] The rain bracket 40 has a first bracket wall portion 41 that extends vertically on the inside in the vehicle width direction, a second bracket wall portion 42 that extends outward in the vehicle width direction from the upper end of the first bracket wall portion 41, and a third bracket wall portion 43 that extends downward from the outer end of the second bracket wall portion 42 in the vehicle width direction, and is formed in an inverted U shape when viewed from the front or rear direction. The first bracket wall portion 41 of the rain bracket 40 is joined to the inner vertical wall 11 from the inside in the vehicle width direction by spot welding, and the lower end of the third bracket wall portion 43 is sandwiched between the inner lower flange 15 and the outer lower flange 25, and these three pieces are joined together by spot welding.

[0026] The reinforcement 30 will now be described with reference to Figures 2 and 3. The reinforcement 30 has the cross-sectional shape shown in Figure 2 and extends in the front-rear direction along its entire length. In this embodiment, the reinforcement 30 is an extruded profile made of aluminum alloy. The reinforcement 30 is fixed to the side sill 3 by being bolted to the inner vertical wall 11 in the vehicle width direction and by being bolted to the second bracket wall portion 42 of the rain bracket 40 in the vertical direction.

[0027] The reinforcement 30 has a rectangular cross-sectional shape, as shown in Figure 2, which is elongated in the vehicle width direction. It has an upper wall 31 that forms the upper surface and extends in the front-rear direction, a lower wall 32 that forms the lower surface and extends in the front-rear direction, an outer wall 33 that connects the outer edges of the upper wall 31 and the lower wall 32 in the vehicle width direction and extends in the front-rear direction, and an inner wall 34 that connects the inner edges of the upper wall 31 and the lower wall 32 in the vehicle width direction and extends in the front-rear direction. In other words, the upper wall 31 and the lower wall 32 extend generally horizontally and face each other in the vertical direction. The outer wall 33 and the inner wall 34 extend in the front-rear and vertical directions and face the vehicle width direction, respectively.

[0028] The reinforcement 30 has an internal space S with a rectangular cross-section defined on its interior by an upper wall 31, a lower wall 32, an outer wall 33, and an inner wall 34.

[0029] The reinforcement 30 further includes a plurality of vertical walls 35 that extend in the front-rear direction, connecting the upper wall 31 and the lower wall 32 between the outer wall 33 and the inner wall 34. In this embodiment, the reinforcement 30 has two vertical walls 35, including a first vertical wall 35A located on the outside in the vehicle width direction and a second vertical wall 35B located on the inside in the vehicle width direction. The reinforcement 30 is partitioned in the vehicle width direction by the plurality of vertical walls 35 such that the internal space S is divided into a plurality of first closed section sections S1, a second closed section section S2, and a third closed section section S3, which are arranged from the outside in the vehicle width direction.

[0030] As shown in Figure 3, the upper wall 31 is divided in the vehicle width direction by a plurality of vertical walls 35 into a first upper wall 31a, a second upper wall 31b, and a third upper wall 31c, which are arranged from the outside in the vehicle width direction. Similarly, the lower wall 32 is divided in the vehicle width direction by a plurality of vertical walls 35 into a first lower wall 32a, a second lower wall 32b, and a third lower wall 33c, which are arranged from the outside in the vehicle width direction.

[0031] The first closed section S1 is divided into a rectangular closed section by the first upper wall 31a, the first lower wall 32a, the outer wall 33, and the first vertical wall 35A. The second closed section S2 is divided into a rectangular closed section by the second upper wall 31b, the second lower wall 32b, the first vertical wall 35A, and the second vertical wall 35B. The third closed section S3 is divided into a rectangular closed section by the third upper wall 31c, the third lower wall 32c, the second vertical wall 35B, and the inner wall 34.

[0032] In this embodiment, as shown in Figure 2, the reinforcement 30 is bolted to the side sill inner 10 and the rain bracket 40 in the third closed section S3. Specifically, in the third closed section S3, the inner wall 34 is provided with a female threaded portion 34a that penetrates in the vehicle width direction, and the third lower wall 32c (see Figure 3) is provided with a female threaded portion 32d that penetrates in the vertical direction. In this embodiment, by configuring the female threaded portions 32d and 34a with blind nuts, the female threaded portions 32d and 34a can be provided in the middle of the reinforcement 30, which is an extruded profile, in the front-rear direction.

[0033] The reinforcement 30 is fixed to the inner vertical wall 11 by fastening a fastening bolt 45 through the inner vertical wall 11 from the inside in the vehicle width direction, with the inner wall 34 abutting the inner vertical wall 11 from the outside in the vehicle width direction, and fastening it to the female threaded portion 34a. The reinforcement 30 is also fixed to the rain bracket 40 by fastening a fastening bolt 45 through the second bracket wall 42 from the bottom side, with the lower wall 32 abutting the second bracket wall 42 of the rain bracket 40 from above, and fastening it to the female threaded portion 32d.

[0034] The reinforcement 30 is positioned inside the side sill 3, spaced apart from the side sill inner 10 inward in the internal space S with respect to the portion excluding the inner vertical wall 11, and spaced apart from the side sill outer 20 inward in the internal space S.

[0035] In this embodiment, grooves 36 are formed in the upper wall 31 and the lower wall 32 at the locations where the vertical walls 35 are formed, recessing into the interior space S. The grooves 36 extend in the front-rear direction along the entire length of the reinforcement 30. The grooves 36 include first grooves 36A and second grooves 36B formed in the upper wall 31 at the locations where the first vertical wall 35A and the second vertical wall 35B are connected, and third grooves 36C and fourth grooves 36D formed in the lower wall 32 at the locations where the first vertical wall 35A and the second vertical wall 35B are connected.

[0036] The first groove 36A will be described in more detail below, but the same applies to the second groove 36B, the third groove 36C, and the fourth groove 36D, so their descriptions will be omitted. As shown in the enlarged view of section A in Figure 3, in the first closed section S1, a first corner radius 37A is formed at the connection between the first vertical wall 35A and the first upper wall 31a on the inner surface, and a first radius chamfer 38A is formed at the corner between the first upper wall 31a and the first vertical wall 35A on the outer surface. The first corner radius 37A and the first radius chamfer 38A extend parallel to each other, and their centers of curvature coincide.

[0037] Similarly, in the second closed section S2, a second corner radius 37B is formed at the connection point between the first vertical wall 35A and the second upper wall 31b on the inner surface, and a second radius chamfer 38B is formed at the corner between the second upper wall 31b and the first vertical wall 35A on the outer surface. The second corner radius 37B and the second radius chamfer 38B extend parallel to each other, and their centers of curvature coincide.

[0038] The first groove 36A is composed of a first R chamfer 38A in its outer portion in the vehicle width direction, a second R chamfer 38B in its inner portion in the vehicle width direction, and a groove bottom corner R portion 36a connecting the first R chamfer 38A and the second R chamfer 38B in its central portion in the vehicle width direction. The groove bottom corner R portion 36a is located on the center line in the thickness direction of the first vertical wall 35A. By composing the groove 36 with a chamfer 38 parallel to the corner R portion 37, the thickness of the reinforcement 30 is configured to be approximately constant. The dimensions of the groove 36 in the vehicle width direction decrease toward the inside of the internal space S.

[0039] The lower body structure 1 of the vehicle 100 according to this disclosure provides the following effects.

[0040] (1) The lower body structure 1 of the vehicle 100 is Floor panel 2 and A pair of left and right side sills 3 extend in the front-to-back direction along the left and right edges of the floor panel 2, A pair of left and right reinforcements 30 are positioned on the inside of each of the left and right side sills 3, and extend in the front-to-back direction along the side sills 3. It has, Reinforcement 30 is The upper surface consists of an upper wall 31 that extends in the front-to-back direction, It constitutes the lower surface, and extends in the front-to-back direction, with a lower wall 32, The outer edges of the upper wall 31 and the lower wall 32 in the vehicle width direction are connected, and the outer wall 33 extends in the front-rear direction, The inner edges of the upper wall 31 and the lower wall 32 in the vehicle width direction are connected, and the inner wall 34 extends in the front-rear direction. It has, The reinforcement 30 further has a vertical wall 35 that extends in the front-rear direction, connecting the upper wall 31 and the lower wall 32 between the outer wall 33 and the inner wall 34, and the vertical wall 35 divides the internal space S defined by the upper wall 31, the lower wall 32, the outer wall 33, and the inner wall 34 into first to third closed section sections S1 to S3 in the vehicle width direction. At least one of the upper wall 31 and the lower wall 32 has a groove 36 that extends in the front-rear direction along the entire length of the reinforcement 30 at the location where the vertical wall 35 is connected.

[0041] Figures 4A and 4B schematically illustrate the deformation behavior of the reinforcement 30 when subjected to a side impact load F from the outside in the vehicle width direction. Note that in Figures 4A and 4B, the reinforcement 30 is shown in a simplified diagram. As shown in Figure 4A, since the reinforcement 30 has grooves 36 in the upper wall 31 and the lower wall 32, when subjected to a side impact load F from the outside in the vehicle width direction, stress is concentrated in the grooves 36, making it easy for the upper wall 31 and the lower wall 32 to undergo valley-fold deformation in the portion where the grooves 36 are formed, causing them to convex inward in the first to third closed cross sections S1 to S3 in the vertical direction.

[0042] Since the vertical wall 35 is located inside the groove 36, the groove 36 is less likely to be submerged into the interior space S by valley-fold deformation. Therefore, in each closed section S1 to S3, deformation can occur in the upper wall 31 or lower wall 32 such that the portion continuous with the groove 36 inclins outward, starting from the valley-fold deformation in the groove 36. Moreover, in each closed section S1 to S3, the end opposite to the end where the groove 36 is formed is less likely to deform inward or outward of the closed section because the vertical wall 35, outer wall 33, or inner wall 34 is located inside.

[0043] As a result, in each closed section S1 to S3, a mountain-fold deformation can be generated such that the intermediate portion in the width direction becomes convex outward from each closed section S1 to S3 on the side of the upper wall 31 or lower wall 32 where the groove 36 is formed. Therefore, by generating a mountain-fold deformation in each closed section S1 to S3, the reinforcement 30 can be efficiently crushed in the vehicle width direction while suppressing remaining crushed, as shown in Figure 4B. Consequently, the amount of energy absorbed by the reinforcement 30 against the side impact load F can be increased.

[0044] As in this embodiment, even when the floor panel 2 does not have a tunnel section and therefore the energy absorption effect of the tunnel section against the side impact load F is not exerted, the amount of energy absorbed by the reinforcement 30 can be increased to more effectively resist the side impact load F. As a result, the amount by which the side sill 3 indents in the vehicle width direction during a side impact is reduced, so interference of the side sill 3 with the battery case 4, which is located between the pair of side sills 3 below the floor panel 2, is suppressed. Therefore, the protective performance against the battery case 4 can be improved.

[0045] (2) The reinforcement 30 has a plurality of vertical walls 35 spaced apart in the vehicle width direction in the internal space S, The upper wall 31 and the lower wall 32 have grooves 36 at each of the multiple positions where each of the multiple vertical walls 35 is connected.

[0046] As a result, grooves 36 are formed in the upper wall 31 and lower wall 32 of the reinforcement 30, between the first to third closed cross-sectional sections S1 to S3, respectively. Consequently, grooves 36 are formed at both ends of the upper wall 31 and lower wall 32 in the vehicle width direction in each of the first to third closed cross-sectional sections S1 to S3. Therefore, when the first to third closed cross-sectional sections S1 to S3 are subjected to a side impact load from the outside in the vehicle width direction, they are more reliably deformed into a mountain shape. Thus, the reinforcement 30 can be crushed more efficiently in the vehicle width direction while further suppressing the amount of remaining crushed, and the amount of energy absorbed by the reinforcement 30 in response to the side impact load F can be further increased.

[0047] (3) Each of the first to third closed sections S1 to S3 has a rectangular cross-sectional shape perpendicular to the front-to-back direction.

[0048] As a result, since the upper wall 31 and lower wall 32 of the first to third closed sections S1 to S3 extend in a straight line, the amount of energy absorbed when deforming them into a mountain fold can be increased compared to cases where they are not straight (for example, curved or bent).

[0049] (4) Corner radius portions 37 are formed at the connection points between the vertical wall 35 and the upper wall 31 and the lower wall 32. The groove 36 extends in an R-shape along the corner R portion 37.

[0050] As a result, it is easier to maintain a constant wall thickness while forming grooves 36 in the reinforcement 30. Consequently, the reinforcement 30 can be stably formed, for example, by extrusion molding.

[0051] The lower body structure 1 of the vehicle relating to this disclosure is not limited to the configuration described in the above embodiment, and various modifications are possible.

[0052] In the above embodiment, the groove 36 is formed at the positions where the vertical wall 35 is connected to the upper wall 31 and the lower wall 32, but it is not limited to this. The groove 36 may be formed in only one of the upper wall 31 and the lower wall 32, or it may be formed in at least one of the multiple connection positions where multiple vertical walls 35 are connected.

[0053] In the above embodiment, the groove 36 is formed using two chamfered R portions 38 such that its dimension in the vehicle width direction decreases toward the inside of the internal space S, but it is not limited to this. The groove 36 may be made of any shape, such as rectangular, semicircular, or triangular. When the reinforcement 30 is formed from an extruded profile, it is preferable to form the groove 36 so that the wall thickness is constant.

[0054] In the above embodiment, the reinforcement 30 was formed from an extruded profile, but it is not limited to this. The reinforcement 30 may be formed by any method, such as casting, machining, and sheet metal welding.

[0055] In the above embodiment, the first to third upper walls 31a to 31c and the first to third lower walls 32a to 32c are configured in a straight line, but the embodiment is not limited to this. The first to third upper walls 31a to 31c and the first to third lower walls 32a to 32c may be formed to curve vertically in the direction of vehicle width, or they may be configured to have corners that bend vertically in the direction of vehicle width. Even in this case, however, it is desirable that the first to third upper walls 31a to 31c and the first to third lower walls 32a to 32c be configured to be convex outward from the internal space S in order to prevent valley-fold deformation that would cause them to be convex inward from the internal space S, from the viewpoint of suppressing remaining crushed material.

[0056] In the above embodiment, the first to third upper walls 31a to 31c and the first to third lower walls 32a to 32c are configured to extend substantially parallel to each other in the horizontal direction, but the embodiment is not limited to this. The first to third upper walls 31a to 31c and the first to third lower walls 32a to 32c may be configured to incline outward or inward of the internal space S toward one side in the vehicle width direction. In this case, each closed section S1 to S3 will be divided into a trapezoidal section. Of the first to third upper walls 31a to 31c and the first to third lower walls 32a to 32c, the portion that inclines inward of the internal space S toward the position where the vertical wall 35 is connected is prone to valley fold deformation that is convex inward of the internal space S, while the remaining portion is prone to mountain fold deformation.

[0057] In the above embodiment, the case where there are two vertical walls 35 was described as an example, but it is not limited to this. There may be one vertical wall 35, or there may be three or more.

[0058] [Note] The front structure of the vehicle relating to this disclosure provides the following aspects.

[0059] [Aspect 1] Floor panel and A pair of left and right side sills extending in the front-rear direction along both side edges of the floor panel, A pair of left and right reinforcements are positioned inside each of the left and right side sills and extend in the front-rear direction along the side sills. It has, The aforementioned reinforcement is, It forms the top surface, and extends in the front-to-back direction, with an upper wall and It forms the lower surface, and extends in the front-to-back direction, with a lower wall and The outer edges of the upper and lower walls, respectively, in the vehicle width direction are connected, and the outer wall extends in the front-rear direction, The inner edges of the upper and lower walls, respectively, in the vehicle width direction are connected, and the inner wall extends in the front-rear direction. It has, The reinforcement further has one or more vertical walls that extend in the front-rear direction, connecting the upper wall and the lower wall between the outer wall and the inner wall, and these one or more vertical walls divide the interior space defined by the upper wall, the lower wall, the outer wall, and the inner wall into a plurality of closed cross-sectional sections in the vehicle width direction. A lower body structure for a vehicle, wherein at least one of the upper wall and the lower wall has a groove extending in the front-rear direction along the entire length of the reinforcement at at least one of the positions where the one or more vertical walls are connected.

[0060] [Aspect 2] The reinforcement has a plurality of vertical walls spaced apart in the vehicle width direction within the internal space, The upper wall and the lower wall each have the groove portion at each of the multiple positions where each of the multiple vertical walls is connected. The lower body structure of the vehicle described in Embodiment 1.

[0061] [Aspect 3] Each of the aforementioned multiple closed cross-sections has a rectangular cross-sectional shape perpendicular to the front-to-back direction. The lower body structure of the vehicle according to embodiment 1 or 2.

[0062] [Aspect 4] Corner radius portions are formed at the connection points between the vertical wall, the upper wall, and the lower wall. The groove extends in an R-shape along the corner R portion. The lower body structure of a vehicle described in any one of the embodiments 1 to 3. [Explanation of symbols]

[0063] 1. Lower body structure 2 floor panels 3 Side sills 4 Battery Case 10 Side sill inner 20 Side sill outer 30 Reinforcement 31 Upper wall 32 Lower wall 33 Exterior Wall 34 Inner wall 35 Vertical wall 36 Groove 37. Corner radius 38 Chamfered section 40 Rain Bracket 45 fastening bolts 100 vehicles S interior space S1 1st closed section S2 Second closed section S3 Third closed section

Claims

1. Floor panel and A pair of left and right side sills extending in the front-rear direction along both side edges of the floor panel, A pair of left and right reinforcements are positioned inside each of the left and right side sills and extend in the front-rear direction along the side sills. It has, The aforementioned reinforcement is, It forms the top surface, and extends in the front-to-back direction, with an upper wall and It forms the lower surface, and extends in the front-to-back direction, with a lower wall and The outer edges of the upper and lower walls, respectively, in the vehicle width direction are connected, and the outer wall extends in the front-rear direction, The inner edges of the upper and lower walls, respectively, in the vehicle width direction are connected, and the inner wall extends in the front-rear direction. It has, The reinforcement further has one or more vertical walls that extend in the front-rear direction, connecting the upper wall and the lower wall between the outer wall and the inner wall, and these one or more vertical walls divide the interior space defined by the upper wall, the lower wall, the outer wall, and the inner wall into a plurality of closed cross-sectional sections in the vehicle width direction. A lower body structure for a vehicle, wherein at least one of the upper wall and the lower wall has a groove extending in the front-rear direction along the entire length of the reinforcement at at least one of the positions where the one or more vertical walls are connected.

2. The reinforcement has a plurality of vertical walls spaced apart in the vehicle width direction within the internal space, The upper wall and the lower wall each have the groove portion at each of the multiple positions where each of the multiple vertical walls is connected. The lower body structure of the vehicle according to claim 1.

3. Each of the aforementioned multiple closed cross-sections has a rectangular cross-sectional shape perpendicular to the front-to-back direction. The lower body structure of a vehicle according to claim 1 or 2.

4. A corner radius (R) is formed at the connection point between the vertical wall, the upper wall, and the lower wall. The groove extends in an R-shape along the corner R portion. The lower body structure of a vehicle according to claim 1 or 2.

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