Lower body structure

Abstract

The present invention provides a lower body structure that can efficiently transmit loads from the outside in the vehicle width direction, which are applied to the side sill, to the cross member. [Solution] The lower body structure comprises a pair of side sills, at least one cross member connecting the pair of side sills to each other, and reinforcements extending in the longitudinal direction within each side sill. The reinforcement has a first portion positioned to overlap with at least one cross member in a side view of the vehicle, and a second portion positioned not to overlap with at least one cross member in a side view of the vehicle. The rigidity of the second portion against loads from the outside in the vehicle width direction is lower than the rigidity of the first portion against loads from the outside in the vehicle width direction.

Description

Technical Field

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[0001] This disclosure relates to a lower body structure.

Background Art

[0002] Patent Document 1 describes a vehicle body structure including a pair of side sills, a cross member connecting the pair of side sills to each other, and a reinforcing member disposed inside each side sill and having a continuous cylindrical structure in which a plurality of closed cross-sections having a polygonal shape when viewed in the vehicle width direction are connected in series.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the vehicle body structure described in Patent Document 1, when an object such as a pole collides with a portion of the side sill where the cross member is not arranged, the reinforcing member may be displaced inward in the vehicle width direction, and the load may not be sufficiently transmitted to the cross member.

[0005] An object of this disclosure is to provide a lower body structure capable of efficiently transmitting a load from the outside in the vehicle width direction input to the side sill to the cross member.

Means for Solving the Problems

[0006] One aspect of this disclosure is a floor panel, a pair of side sills respectively disposed at both ends in the vehicle width direction of the floor panel and extending in the front-rear direction, at least one cross member disposed on the upper surface of the floor panel, extending in the vehicle width direction, and connecting the pair of side sills to each other Within each side sill, there is a reinforcement extending in the front-to-back direction at a given position, Equipped with, The aforementioned reinforcement is, A first portion positioned in a location overlapping with at least one cross member in a side view of the vehicle, A second portion positioned in a location that does not overlap with the at least one cross member in a side view of the vehicle, and It has, The lower body structure is provided such that the rigidity of the second portion against loads from the outside in the vehicle width direction is lower than that of the first portion against loads from the outside in the vehicle width direction.

[0007] This configuration provides a lower body structure that can efficiently transmit loads from the outside in the vehicle width direction applied to the side sill (hereinafter sometimes referred to as side impact loads) to the cross member. If the rigidity of the second part against side impact loads (hereinafter sometimes referred to simply as "rigidity" when referring to rigidity against side impact loads) is excessively high, when loads from the outside in the vehicle width direction applied to the side sill act on the second part, the second part may not be easily compressed in the vehicle width direction and may undergo bending deformation. In this case, loads from the outside in the vehicle width direction applied to the side sill may not be efficiently transmitted to the cross member via the reinforcement. In contrast, in this configuration, since the rigidity of the second part is lower than that of the first part, the second part is more easily compressed when loads from the outside in the vehicle width direction act on it, compared to a configuration where the rigidity of the second part is greater than or equal to that of the first part. As a result, bending deformation of the reinforcement is suppressed, and loads from the outside in the vehicle width direction applied to the side sill can be efficiently transmitted to the cross member via the reinforcement. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a lower body structure that can efficiently transmit loads from the outside in the vehicle width direction applied to the side sill to the cross member. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a top view of a lower vehicle body structure according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a perspective view of the lower body structure shown in Figure 1, and the side sill outer is omitted from the illustration in Figure 3. [Figure 4] Figure 4 is a perspective view of the bracket shown in Figure 2. [Figure 5] Figure 5 shows the upper surface of the lower body structure around the reinforcement shown in Figure 2, and the side sills are not shown in Figure 5. [Figure 6] Figure 6 is a perspective view of a reinforcement according to one modified example of the above embodiment. [Modes for carrying out the invention]

[0010] The lower body structure of a vehicle 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 this disclosure, its applications, or its uses.

[0011] Figure 1 is a top view of a lower body structure 1 according to one embodiment of the present disclosure. The lower body structure 1 is mounted on a vehicle such as an automobile. In this embodiment, the lower body structure 1 is mounted on an electric vehicle. In this specification, the longitudinal direction, lateral direction, and vertical direction of the vehicle on which the lower body structure 1 is mounted may be referred to as the "longitudinal direction," the "vehicle width direction," and the "vertical direction," respectively. In this specification, the side of the vehicle's centerline in the vehicle width direction may be referred to as the "inside in the vehicle width direction," and the side opposite the vehicle's centerline in the vehicle width direction may be referred to as the "outside in the vehicle width direction."

[0012] Referring to Figure 1, the lower body structure 1 comprises a floor panel 10, a pair of side sills 20A and 20B, a first cross member 30, and a second cross member 40. In the following description, when it is not necessary to distinguish between the pair of side sills 20A and 20B, one of the pair of side sills 20A and 20B may simply be referred to as the side sill 20. Also, the first cross member 30 and the second cross member 40 in this embodiment are examples of cross members according to the present disclosure.

[0013] The floor panel 10 constitutes the floor surface of the passenger compartment of the vehicle on which the lower body structure 1 is mounted. The floor panel 10 is a press-formed steel product. The floor panel 10 is a plate-like structure with its thickness in the vertical direction and extending in the longitudinal and vehicle width directions. Below the floor panel 10 is a battery case 2 (shown in Figure 2) which houses the vehicle's battery (not shown). The vehicle in this embodiment is an electric vehicle and does not have an internal combustion engine or transmission, so there is no exhaust pipe or propeller shaft below the floor panel 10, and the floor panel 10 does not have a so-called tunnel that protrudes upward from the center in the vehicle width direction and extends in the longitudinal direction.

[0014] A pair of side sills 20A and 20B are positioned at both ends of the floor panel 10 in the vehicle width direction, respectively. That is, the pair of side sills 20A and 20B are spaced apart in the vehicle width direction. The side sills 20 extend in the longitudinal direction along the outer end of the floor panel 10 in the vehicle width direction. The side sills 20 have a rectangular closed cross-section when viewed from the longitudinal direction. The side sills 20 are made of steel. The side sills 20 are also called rockers.

[0015] The first cross member 30 is disposed on the upper surface of the floor panel 10. The first cross member 30 extends in the vehicle width direction between the side sills 20A and 20B. The first cross member 30 connects the side sills 20A and 20B to each other. The first cross member 30 is a press-formed product made of a steel plate. The first cross member 30 has a hat shape that opens downward and forms a closed cross-section structure extending in the vehicle width direction together with the floor panel 10. The first cross member 30 includes a front flange 30a disposed at the front edge and a rear flange 30b disposed at the rear edge. The first cross member 30 is joined to the floor panel 10 by spot welding via the front flange 30a and the rear flange 30b. The first cross member 30 is a seat cross member to which a front seat (not shown) is attached.

[0016] At both ends of the first cross member 30 in the vehicle width direction, seat brackets 31 for fixing a front seat (not shown) are attached. The seat brackets 31 are press-formed products made of a steel plate. The seat brackets 31 are joined to the first cross member 30 and the side sill 20 respectively by spot welding. Thereby, the first cross member 30 is connected to the pair of side sills 20A and 20B via the seat brackets 31 at both ends in the vehicle width direction.

[0017] The second cross member 40 is disposed on the upper surface of the floor panel 10. The second cross member 40 is disposed behind the first cross member 30. That is, the second cross member 40 is spaced apart from the first cross member 30 in the front-rear direction. The second cross member 40 extends in the vehicle width direction between the side sills 20A and 20B. The second cross member 40 connects the side sills 20A and 20B to each other. The second cross member 40 is a press-formed product made of a steel plate. The second cross member 40 has a hat shape that opens downward and forms a closed cross-section structure extending in the vehicle width direction together with the floor panel 10. The second cross member 40 includes a front flange 40a disposed at the front edge and a rear flange 40b disposed at the rear edge. The second cross member 40 is joined to the floor panel 10 by spot welding via the front flange 40a and the rear flange 40b.

[0018] Gussets 41 are attached to both ends of the second cross member 40 in the vehicle width direction. The gussets 41 are press-formed products made of a steel plate. The gussets 41 are joined to the second cross member 40 and the side sills 20 respectively by spot welding. The second cross member 40 is connected to the pair of side sills 20 via the gussets 41 at both ends in the vehicle width direction.

[0019] The second cross member 40 has lower rigidity against loads from the outside in the vehicle width direction than the first cross member 30. Also, no seat bracket for fixing a seat (not shown) is attached to the second cross member 40. That is, the second cross member 40 does not have a function of supporting the load of the seat.

[0020] Figure 2 is a cross-sectional view taken along the line II-II of Figure 1. In Figure 2, the vicinity of the portion of the side sill 20A connected to the second cross member 40 is shown. Figure 3 is a perspective view of the lower vehicle body structure 1. In Figure 3, the illustration of the side sill 20 is omitted.

[0021] Referring to Figure 2, the side sill 20 comprises a side sill inner 21 and a side sill outer 22 positioned on the outside of the side sill inner 21 in the vehicle width direction. Both the side sill inner 21 and the side sill outer 22 are press-formed products made of steel plate.

[0022] The side sill inner 21 is a hat-shaped plate material that opens outward in the vehicle width direction. Specifically, the side sill inner 21 comprises an upper wall portion 21a extending in the vehicle width direction, a side wall portion 21b extending downward from the inner end of the upper wall portion 21a in the vehicle width direction, and a lower wall portion 21c extending outward in the vehicle width direction from the lower end of the side wall portion 21b. The side sill inner 21 comprises a flange 21d extending upward from the outer end of the upper wall portion 21a in the vehicle width direction, and a flange 21e extending downward from the outer end of the lower wall portion 21c in the vehicle width direction.

[0023] The side sill outer 22 is a hat-shaped plate material that opens inward in the vehicle width direction. Specifically, the side sill outer 22 comprises an upper wall portion 22a extending in the vehicle width direction, a side wall portion 22b extending downward from the outer end of the upper wall portion 22a in the vehicle width direction, and a lower wall portion 22c extending inward in the vehicle width direction from the lower end of the side wall portion 22b. The side sill outer 22 comprises a flange 22d extending upward from the inner end of the upper wall portion 22a in the vehicle width direction, and a flange 22e extending downward from the inner end of the lower wall portion 22c in the vehicle width direction.

[0024] The side sill inner 21 and the side sill outer 22 are joined together by spot welding, with a space defined between them. Specifically, the flange 21d of the side sill inner 21 and the flange 22d of the side sill outer 22 are joined to each other by spot welding, and the flange 21e of the side sill inner 21 and the flange 22e of the side sill outer 22 are joined to each other by spot welding. As a result, the side sill 20 is configured as a closed cross-sectional structure extending in the front-rear direction.

[0025] The lower body structure 1 includes a reinforcement 50 positioned inside each side sill 20 and a bracket 60 that secures the reinforcement 50 to the side sill 20. Figure 2 shows only one of the pair of side sills 20A, 20B, side sill 20A, but the other side sill 20B also has a reinforcement 50 and bracket 60 positioned inside it.

[0026] The reinforcement 50 is located inside the side sill 20. The reinforcement 50 extends in the longitudinal direction along the entire length of the side sill 20. In this embodiment, as shown in Figure 3, the reinforcement 50 extends forward beyond the front end of the side sill 20 (only the side sill inner 21 is shown in Figure 3). The front end of the reinforcement 50 is located below the hinge pillar 3 (only the inner pillar is shown in Figure 3).

[0027] As shown in Figure 2, the reinforcement 50 is aligned with the first cross member 30 and the second cross member 40 in the vertical direction (Figure 2 only shows the positional relationship with the second cross member 40). The reinforcement 50 is an extruded aluminum material. The reinforcement 50 has a longitudinal direction extending in the front-rear direction. In the cross section shown in Figure 2, the reinforcement 50 has a narrow rectangular closed cross section shape in the vehicle width direction. The reinforcement 50 has a generally uniform cross section shape along its entire length in the longitudinal direction. The reinforcement 50 comprises a first vertical wall 51, a second vertical wall 52, a first horizontal wall 53, a second horizontal wall 54, a first inner wall 55, and a second inner wall 56.

[0028] The first vertical wall 51 is plate-shaped with its longitudinal direction in the front-rear direction, its transverse direction in the up-down direction, and its thickness direction in the vehicle width direction. In the cross-section shown in Figure 2, the first vertical wall 51 extends vertically as a whole. The first vertical wall 51 constitutes a part of the outer shape of the reinforcement 50. Specifically, the first vertical wall 51 constitutes the outer side wall of the reinforcement 50 in the vehicle width direction.

[0029] The second vertical wall 52 is plate-shaped with its longitudinal direction in the front-rear direction, its transverse direction in the up-down direction, and its thickness direction in the vehicle width direction. In the cross-section shown in Figure 2, the second vertical wall 52 extends vertically as a whole. The second vertical wall 52 constitutes a part of the outer shape of the reinforcement 50. Specifically, the second vertical wall 52 constitutes the inner side wall of the reinforcement 50 in the vehicle width direction. The second vertical wall 52 is positioned inward in the vehicle width direction relative to the first vertical wall 51. The second vertical wall 52 is positioned at a distance from the first vertical wall 51 in the vehicle width direction.

[0030] The first lateral wall 53 is plate-shaped with its longitudinal direction in the front-rear direction, its transverse direction in the vehicle width direction, and its thickness direction in the vertical direction. In the cross-section shown in Figure 2, the first lateral wall 53 extends in the vehicle width direction so as to connect the upper end of the first vertical wall 51 and the upper end of the second vertical wall 52 to each other. The first lateral wall 53 constitutes a part of the outer shape of the reinforcement 50. Specifically, the first lateral wall 53 constitutes the upper wall of the reinforcement 50.

[0031] The second lateral wall 54 is plate-shaped with its longitudinal direction in the front-rear direction, its transverse direction in the vehicle width direction, and its thickness direction in the vertical direction. In the cross-section shown in Figure 2, the second lateral wall 54 extends in the vehicle width direction so as to connect the lower end of the first longitudinal wall 51 and the lower end of the second longitudinal wall 52 to each other. The second lateral wall 54 constitutes a part of the outer shape of the reinforcement 50. Specifically, the second lateral wall 54 constitutes the lower wall of the reinforcement 50. The second lateral wall 54 is positioned below the first lateral wall 53. The second lateral wall 54 is positioned at a distance from the first lateral wall 53 in the vertical direction.

[0032] The first inner wall 55 is plate-shaped with its longitudinal direction in the front-rear direction, its transverse direction in the up-down direction, and its thickness direction in the vehicle width direction. In the cross-section shown in Figure 2, the first inner wall 55 extends vertically so as to connect the first transverse wall 53 and the second transverse wall 54 to each other. The first inner wall 55 is positioned between the first longitudinal wall 51 and the second longitudinal wall 52 in the vehicle width direction.

[0033] The second inner wall 56 is plate-shaped with its longitudinal direction in the front-rear direction, its transverse direction in the up-down direction, and its thickness direction in the vehicle width direction. In the cross-section shown in Figure 2, the second inner wall 56 extends vertically so as to connect the first transverse wall 53 and the second transverse wall 54 to each other. The second inner wall 56 is positioned between the second longitudinal wall 52 and the first inner wall 55 in the vehicle width direction. In other words, the second inner wall 56 is positioned inward in the vehicle width direction relative to the first inner wall 55.

[0034] Inside the reinforcement 50, a rectangular cross-sectional interior space is defined by the first vertical wall 51, the second vertical wall 52, the first horizontal wall 53, and the second horizontal wall 54. This interior space is divided into three closed cross-sectional spaces by the first inner wall 55 and the second inner wall 56.

[0035] The reinforcement 50 is divided into three regions in the vehicle width direction. Specifically, the reinforcement 50 is divided into three parts having an outer region R1, an intermediate region R2, and an inner region R3.

[0036] The outer region R1 is the region of the reinforcement 50 located between the first longitudinal wall 51 and the first inner wall 55 in the vehicle width direction. The outer region R1 includes the portion of the first transverse wall 53 and the second transverse wall 54 that extends in the vehicle width direction between the first longitudinal wall 51 and the second inner wall 56.

[0037] The intermediate region R2 is the region of the reinforcement 50 located between the first inner wall 55 and the second inner wall 56 in the vehicle width direction. The intermediate region R2 includes the portion of the first lateral wall 53 and the second lateral wall 54 that extends in the vehicle width direction between the first inner wall 55 and the second inner wall 56.

[0038] The inner region R3 is the area of ​​the reinforcement 50 located between the second longitudinal wall 52 and the second inner wall 56 in the vehicle width direction. The inner region R3 includes the portion of the first transverse wall 53 and the second transverse wall 54 that extends in the vehicle width direction between the second longitudinal wall 52 and the second inner wall 56.

[0039] The reinforcement 50 is fastened to the side sill inner 21. The second vertical wall 52 of the reinforcement 50 is bolted to the side wall portion 21b of the side sill inner 21 in the vehicle width direction.

[0040] The bracket 60 is located inside the side sill 20. The bracket 60 is located below the reinforcement 50 inside the side sill 20. The bracket 60 is made of steel. As shown in Figure 3, the bracket 60 is provided at multiple locations (two locations in this embodiment) located inside the side sill 20, spaced apart from each other in the longitudinal direction. At least a portion of the bracket 60 is positioned to overlap with the hinge pillar 3 or center pillar 4 extending upward from the side sill 20 in a vehicle side view. Specifically, the two brackets 60 are provided so as to partially overlap with the lower portion 3a of the hinge pillar 3 that extends in the longitudinal direction to connect to the side sill 20, and the lower portion 4a of the center pillar 4 that extends in the longitudinal direction to connect to the side sill 20, respectively, in a vehicle side view.

[0041] As shown in Figure 2, the bracket 60 is U-shaped when viewed in the front-to-back direction. The bracket 60 comprises an upper wall 60a, an inner wall 60b, and an outer wall 60c.

[0042] The upper wall 60a is plate-shaped, with its thickness oriented vertically and extending in the front-rear and vehicle width directions. The upper wall 60a is positioned facing the second side wall 54 of the reinforcement 50 in the vertical direction. The upper wall 60a is fixed to the lower surface of the reinforcement 50.

[0043] The inner wall 60b extends downward from the inner end of the upper wall 60a in the vehicle width direction. The inner wall 60b is positioned facing the side wall portion 21b of the side sill inner 21. The inner wall 60b is fixed to the side sill inner 21.

[0044] The outer wall 60c extends downward from the outer end of the upper wall 60a in the vehicle width direction. The outer wall 60c faces the inner wall 60b and is positioned with a gap in the vehicle width direction. The outer wall 60c is fixed to the side sill inner 21 and the side sill outer 22.

[0045] Bracket 60 is fastened to reinforcement 50. The upper wall 60a of bracket 60 is bolted to the second lateral wall 54 in the inner region R3 of reinforcement 50. That is, the fixing portion, i.e., the fastening point, between the upper wall 60a and reinforcement 50 is located inward in the vehicle width direction from the center of reinforcement 50 in the vehicle width direction.

[0046] The bracket 60 is joined to the side sill 20 by spot welding. The inner wall 60b of the bracket 60 is joined to the side wall portion 21b of the side sill inner 21 in the vehicle width direction by spot welding. The outer wall 60c of the bracket 60 is sandwiched between the flange 21e of the side sill inner 21 and the flange 22e of the side sill outer 22 at its lower end, and is joined to the side sill inner 21 and the side sill outer 22 in a triple-layered spot welding configuration.

[0047] Figure 4 is a perspective view of the bracket 60. Referring to Figure 4, the bracket 60 of this embodiment has a divided structure comprising a first part 61 and a second part 62 that is separate from the first part 61.

[0048] The first part 61 is a press-formed product made of steel plate. The first part 61 is L-shaped when viewed in the front-to-back direction. The first part 61 comprises a first vertical plate 61a and a first horizontal plate 61b. The first vertical plate 61a is a plate shape with the vehicle width direction as the plate thickness direction and extending in the vertical and front-to-back directions. The first vertical plate 61a constitutes the inner wall 60b of the bracket 60. The first horizontal plate 61b is a plate shape with the vertical direction as the plate thickness direction and extending in the vehicle width direction and front-to-back directions. The first horizontal plate 61b extends outward in the vehicle width direction from the upper end of the first vertical plate 61a.

[0049] The second part 62 is a press-formed product made of steel plate. The second part 62 is L-shaped when viewed in the front-to-back direction. The second part 62 comprises a second vertical plate 62a and a second horizontal plate 62b. The second vertical plate 62a is plate-shaped with the vehicle width direction as the plate thickness direction and extending in the vertical and front-to-back directions. The second vertical plate 62a faces the first vertical plate 61a in the vehicle width direction and is positioned on the outside of the first vertical plate 61a in the vehicle width direction. The second vertical plate 62a constitutes the outer wall 60c of the bracket 60. The second horizontal plate 62b is plate-shaped with the vertical direction as the plate thickness direction and extending in the vehicle width direction and front-to-back directions. The second horizontal plate 62b extends inward in the vehicle width direction from the upper end of the second vertical plate 62a.

[0050] The first horizontal plate 61b of the first component 61 and the second horizontal plate 62b of the second component 62 are superimposed in the vertical direction. The first horizontal plate 61b and the second horizontal plate 62b are joined by welding while superimposed in the vertical direction. The second horizontal plate 62b, together with the first horizontal plate 61b, constitutes the upper wall 60a of the bracket 60.

[0051] In this embodiment, the inner wall 60b and the outer wall 60c are connected in the vehicle width direction only via the upper wall 60a. In other words, the bracket 60 does not have any members connecting the inner wall 60b and the outer wall 60c except for the upper wall 60a.

[0052] Figure 5 is a top view of the lower body structure 1 showing the area around the reinforcement 50, and the side sill 20 is not shown in Figure 5. Referring to Figure 5, the reinforcement 50 comprises a first part 57, a second part 58, and a third part 59.

[0053] The first part 57 is positioned to overlap with the first cross member 30 when viewed from the side of the vehicle. In other words, the first part 57 is the portion that overlaps with the first cross member 30 when viewed from the outside in the width direction of the vehicle. The first part 57 is aligned with the first cross member 30 in the longitudinal direction.

[0054] The second portion 58 is positioned so as not to overlap with either the first cross member 30 or the second cross member 40 when viewed from the side of the vehicle. In other words, the second portion 58 is a portion that does not overlap with either the first cross member 30 or the second cross member 40 when viewed from the inside in the vehicle width direction. The second portion 58 is positioned offset from the first cross member 30 and the second cross member 40 in the longitudinal direction. In this embodiment, the second portion 58 is divided into three sections, including a section 58a located in front of the first cross member 30, a section 58b located behind the first cross member 30 and in front of the second cross member 40, and a section 58c located behind the second cross member 40.

[0055] The third section 59 is positioned to overlap with the second cross member 40 when viewed from the side of the vehicle. In other words, when viewed from the outside in the width direction of the vehicle, the third section 59 and the second cross member 40 are aligned with the second cross member 40 in the longitudinal direction.

[0056] The rigidity of the second part 58 is lower than that of the first part 57. In this embodiment, a plurality of holes 70 are formed in the second part 58, and each hole 70 penetrates the first lateral wall 53 and the second lateral wall 54 in the vertical direction. When a load is applied to the reinforcement 50 from the outside in the vehicle width direction, stress concentration occurs around the plurality of holes 70 formed in the second part 58, making the plurality of holes 70 likely to become the starting point of deformation. As a result, the rigidity of the second part 58, in which the plurality of holes 70 are formed, is lower than that of the first part 57, in which no holes are formed.

[0057] In this embodiment, the plurality of holes 70 include a plurality of holes 70A formed in the outer region R1 and a plurality of holes 70B formed in the intermediate region R2. The plurality of holes 70A are arranged in a line in the front-to-back direction with spacing between them in the front-to-back direction. The plurality of holes 70B are arranged in a line in the front-to-back direction with spacing between them in the front-to-back direction.

[0058] The rigidity of the third section 59 is lower than that of the first section 57 and higher than that of the second section 58. In this embodiment, a plurality of holes 71 are formed in the third section 59, and each hole 71 penetrates the first lateral wall 53 and the second lateral wall 54 in the vertical direction. When a load is applied to the reinforcement 50 from the outside in the vehicle width direction, stress concentration occurs around the plurality of holes 71 formed in the third section 59, making the plurality of holes 71 likely to become the starting point of deformation. As a result, the rigidity of the second section 58, in which the plurality of holes 71 are formed, is lower than that of the first section 57, in which no holes are formed. Furthermore, the number, size, shape, and arrangement of the plurality of holes 71 formed in the third section 59 are set so that the rigidity of the third section 59 is higher than that of the second section. In this embodiment, the opening area of ​​each hole 71 formed in the third section 59 is smaller than the opening area of ​​each hole 71 formed in the second section 58.

[0059] The second portion 58 has a shape in which its rigidity increases toward the inside in the vehicle width direction. In this embodiment, the number, size, shape, and arrangement of the multiple holes 70 formed in the second portion 58 are set so that the rigidity of the second portion 58 increases toward the inside in the vehicle width direction. In this embodiment, no holes are formed in the inner region R3 of the second portion 58, and the opening area of ​​each hole 70B formed in the intermediate region R2 is smaller than the opening area of ​​each hole 70A formed in the outer region R1. As a result, the rigidity of the second portion 58 tends to increase in stages toward the inside in the vehicle width direction. Specifically, in the second portion 58, the rigidity of the inner region R3 is higher than the rigidity of the intermediate region R2, and the rigidity of the intermediate region R2 is higher than the rigidity of the outer region R1.

[0060] The second portion 58 has a shape in which its rigidity increases as it approaches that of the first portion 57 or the third portion 59. In this embodiment, the number, size, shape, and arrangement of the multiple holes 70 formed in the second portion 58 are set such that the rigidity of the second portion 58 increases as it approaches that of the first portion 57 or the third portion 59. In this embodiment, in section 58a, the opening area of ​​the hole 70 closer to the first portion 57 of two adjacent holes 70 in the front-rear direction is smaller than the opening area of ​​the hole 70 further from the first portion 57. Also, in section 58b, the opening area of ​​the hole 70 closer to the center of section 58b in the front-rear direction is larger than the opening area of ​​the hole 70 further from the center of section 58b in the front-rear direction. In section 58c, the opening area of ​​the hole 70 closer to the third portion 59 of two adjacent holes 70 in the front-rear direction is smaller than the opening area of ​​the hole 70 further from the first portion 57. As a result, in each section 58a to 58c, the rigidity of the second section 58 tends to increase as it approaches that of the first section 57 or the third section 59.

[0061] The lower body structure 1 according to this embodiment provides the following effects.

[0062] (1) The lower body structure 1 according to this embodiment is Floor panel 10 and A pair of side sills 20 are positioned at both ends of the floor panel 10 in the vehicle width direction and extend in the front-rear direction, At least one cross member (in this embodiment, a first cross member 30 and a second cross member 40) is positioned on the upper surface of the floor panel 10, extends in the vehicle width direction, and connects a pair of side sills 20 to each other. Inside each side sill 20, a reinforcement 50 extending in the front-rear direction, Equipped with, Reinforcement 50 is The first part 57 is positioned in a location that overlaps with the first cross member 30 when viewed from the side of the vehicle, The second part 58 is positioned in a location that does not overlap with the first cross member 30 when viewed from the side of the vehicle. It has, The rigidity of the second part 58 against loads from the outside in the vehicle width direction is lower than that of the first part 57 against loads from the outside in the vehicle width direction.

[0063] According to the lower body structure 1 of this embodiment, the load from the outside in the vehicle width direction input to the side sill 20 can be efficiently transmitted to the first cross member 30. If the rigidity of the second part 58 is excessively high, when the load from the outside in the vehicle width direction input to the side sill 20 acts on the second part 58, the second part 58 may not be easily compressed in the vehicle width direction and may undergo bending deformation. In this case, the load from the outside in the vehicle width direction input to the side sill 20 cannot be efficiently transmitted to the first cross member 30 via the reinforcement 50. In contrast, in this configuration, since the rigidity of the second part 58 is lower than that of the first part 57, the second part 58 is more susceptible to compressive deformation when the load from the outside in the vehicle width direction acts on it, compared to a configuration in which the rigidity of the second part 58 is greater than or equal to that of the first part 57. As a result, the bending and deformation of the reinforcement 50 is suppressed, and the load from the outside in the vehicle width direction applied to the side sill 20 can be efficiently transmitted to the first cross member 30 via the reinforcement 50.

[0064] (2) At least one cross member is A first cross member 30 to which a seat bracket 31 for securing the seat is attached, The first cross member 30 and the second cross member 40 are positioned at different locations in the front-rear direction. Equipped with, The first part 57 is positioned in a location that overlaps with the first cross member 30 when viewed from the side of the vehicle. The second part 58 is a portion that does not overlap with both the first cross member 30 and the second cross member 40 when viewed from the side of the vehicle. The reinforcement 50 has a third portion 59 that overlaps with the second cross member 40 in a side view of the vehicle. The rigidity of the third section 59 against loads from the outside in the vehicle width direction is lower than that of the first section 57 against loads from the outside in the vehicle width direction, but higher than that of the second section 58 against loads from the outside in the vehicle width direction.

[0065] According to the lower body structure 1 of this embodiment, the load from the outside in the vehicle width direction input to the side sill 20 can be efficiently transmitted to the first cross member 30 and the second cross member 40. Generally, the rigidity of the cross member to which the seat is attached is higher than the rigidity of other cross members. If the rigidity of the third portion 59 is excessively high, when a load from the outside in the vehicle width direction acts on the third portion 59 of the reinforcement 50, a sufficient reaction force in the vehicle width direction to the load cannot be obtained from the second cross member 40, making it difficult for the third portion 59 to be compressed and potentially causing it to bend. In this case, the load from the outside in the vehicle width direction input to the side sill 20 cannot be efficiently transmitted to the first cross member 30 and the second cross member 40 via the reinforcement 50. In contrast, in this configuration, the rigidity of the third section 59 is lower than that of the first section 57. Therefore, compared to a configuration where the rigidity of the third section 59 is greater than or equal to that of the first section 57, the third section 59 is more susceptible to compressive deformation when a load is applied to it from the outside in the vehicle width direction. As a result, bending deformation of the reinforcement 50 is suppressed, and the load applied to the side sill 20 from the outside in the vehicle width direction can be efficiently transmitted to the first cross member 30 and the second cross member 40 via the reinforcement 50.

[0066] (3) The second part 58 has a shape in which the rigidity against loads from the outside in the vehicle width direction increases toward the inside in the vehicle width direction.

[0067] According to the lower body structure 1 of this embodiment, the load from the outside in the vehicle width direction input to the side sill 20 can be efficiently transmitted to the first cross member 30. Since the second portion 58 has a shape in which its rigidity against loads from the outside in the vehicle width direction increases toward the inside in the vehicle width direction, the second portion 58 is easily compressed in the initial stages of a side collision when an object such as a pole collides with the second portion 58 from the outside in the vehicle width direction. Therefore, by compressing the second portion 58 in the initial stages of a side collision, the second portion 58 effectively absorbs impact energy, and in the later stages of the collision, the inner portion of the second portion 58 in the vehicle width direction withstands the collision, thereby efficiently transmitting the load from the outside in the vehicle width direction input to the side sill 20 to the first cross member 30 and the second cross member 40 via the reinforcement 50.

[0068] (4) The first part 57 and the second part 58 are arranged adjacent to each other in the longitudinal direction, and the second part 58 has a shape in which its rigidity against loads from the outside in the vehicle width direction increases as it approaches the first part 57 in the longitudinal direction.

[0069] According to this embodiment, the load from the outside in the vehicle width direction applied to the side sill 20 can be efficiently transmitted to the first cross member 30. Since the rigidity of the second portion 58 gradually increases as it approaches the first portion 57 in the longitudinal direction, abrupt changes in rigidity between the first portion 57 and the second portion 58 can be suppressed. As a result, the required rigidity of the reinforcement 50 as a whole can be ensured while the load from the outside in the vehicle width direction applied to the side sill 20 can be efficiently transmitted to the first cross member 30.

[0070] (5) The second part 58 has a hole 70 that penetrates in the vertical direction.

[0071] According to this embodiment, a lower body structure 1 can be easily manufactured that can efficiently transmit the load from the outside in the vehicle width direction input to the side sill 20 to the first cross member 30.

[0072] (modified version) This disclosure is not limited to the configurations described in the embodiments above, and various modifications are possible.

[0073] In the above embodiment, the rigidity of the second portion 58 was made lower than that of the first portion 57 by forming a hole 70 in the second portion 58. However, the rigidity of the second portion 58 may be made lower than that of the first portion 57 by other features formed on the second portion 58, such as a bead, groove, or thin-walled portion. The number, size, shape, and arrangement of features for making the rigidity of the second portion 58 lower than that of the first portion 57 can be changed as appropriate. Similarly, the rigidity of the third portion 59 may be made lower than that of the first portion 57 and higher than that of the second portion 58 by other features formed on the third portion 59, such as a bead, groove, or thin-walled portion.

[0074] In the above embodiment, no holes are formed in the first portion 57, but holes may be formed in the first portion 57.

[0075] In the above embodiment, hole 70A was formed in the outer region R1 and hole 70B was formed in the intermediate region R2. However, as shown in the modified example in Figure 5, hole 70 may be formed spanning both the outer region R1 and the intermediate region R2. Alternatively, hole 70 may be formed in the inner region R3.

[0076] [Note] The lower body structure relating to this disclosure provides the following embodiments.

[0077] [Aspect 1] Floor panel and A pair of side sills are positioned at both ends of the floor panel in the vehicle width direction and extend in the front-rear direction, Displaced on the upper surface of the floor panel, extending in the vehicle width direction, and comprising at least one cross member connecting the pair of side sills to each other Inside each side sill, there is a reinforcement extending in the front-to-back direction, Equipped with, The aforementioned reinforcement is A first portion positioned in a location overlapping with at least one cross member in a side view of the vehicle, A second portion positioned in a location that does not overlap with the at least one cross member in a side view of the vehicle and It has, A lower body structure in which the rigidity of the second portion against loads from the outside in the width direction of the vehicle is lower than the rigidity of the first portion against loads from the outside in the width direction of the vehicle.

[0078] [Aspect 2] The aforementioned at least one cross member is The first cross member to which the seat bracket to which the seat is attached, The first cross member and the second cross member are positioned at different locations in the front-rear direction. Equipped with, The first portion is positioned in a location that overlaps with the first cross member when viewed from the side of the vehicle. The second portion is a part that does not overlap with both the first cross member and the second cross member when viewed from the side of the vehicle. The reinforcement has a third portion that overlaps with the second cross member when viewed from the side of the vehicle. The lower body structure according to embodiment 1, wherein the rigidity of the third portion against loads from the outside in the vehicle width direction is lower than that of the first portion against loads from the outside in the vehicle width direction, and higher than that of the second portion against loads from the outside in the vehicle width direction.

[0079] [Aspect 3] The lower body structure according to embodiment 1 or 2, wherein the second part has a shape in which the rigidity against loads from the outside in the vehicle width direction increases toward the inside in the vehicle width direction.

[0080] [Aspect 4] The first part and the second part are arranged adjacent to each other in the front-to-back direction. The lower body structure according to any one of embodiments 1 to 3, wherein the second portion has a shape in which the rigidity against loads from the outside in the width direction increases as it approaches the first portion in the longitudinal direction.

[0081] [Aspect 5] The lower body structure according to any one of embodiments 1 to 4, wherein the second portion has a hole formed therethrough in the vertical direction. [Explanation of Symbols]

[0082] 1. Lower body structure 2 Battery Cases 3. Hinged pillar 10 Floor Panels 20 Side sill 21 Side sill inner 21a Upper wall part 21b Side wall part 21c Lower wall part 21d flange 22e flange 22 Side sill outer 22a Upper wall part 22b Side wall part 22c Lower wall part 22d flange 22e flange 30. First cross member (cross member) 31 Seat Bracket 40. Second cross member (cross member) 41 gusset 50 Reinforcement 51. First vertical wall 52 Second Vertical Wall 53. First side wall 54 Second side wall 55 First Inner Wall 56 Second Inner Wall 57 Part 1 58 Part 2 59 Part 3 60 bracket 60a Upper wall 60b inner wall 60c exterior wall 61 Part 1 61a First vertical board 61b 1st horizontal board 62 Part 2 62a Second vertical plate 62b 2nd horizontal board 70 holes 71 holes

Claims

1. Floor panel and A pair of side sills are positioned at both ends of the floor panel in the vehicle width direction and extend in the front-rear direction, Displaced on the upper surface of the floor panel, extending in the vehicle width direction, and comprising at least one cross member connecting the pair of side sills to each other Inside each side sill, there is a reinforcement extending in the front-to-back direction, Equipped with, The aforementioned reinforcement is A first portion positioned in a location overlapping with at least one cross member in a side view of the vehicle, A second portion positioned in a location that does not overlap with the at least one cross member when viewed from the side of the vehicle, and It has, A lower body structure in which the rigidity of the second portion against loads from the outside in the width direction of the vehicle is lower than the rigidity of the first portion against loads from the outside in the width direction of the vehicle.

2. The aforementioned at least one cross member is A first cross member to which a seat bracket for securing the seat is attached, The first cross member and the second cross member are positioned at different locations in the front-rear direction. Equipped with, The first portion is positioned in a location that overlaps with the first cross member when viewed from the side of the vehicle. The second portion is a part that does not overlap with both the first cross member and the second cross member when viewed from the side of the vehicle. The reinforcement has a third portion that overlaps with the second cross member when viewed from the side of the vehicle. The lower body structure according to claim 1, wherein the rigidity of the third portion against loads from the outside in the width direction is lower than that of the first portion against loads from the outside in the width direction, and higher than that of the second portion against loads from the outside in the width direction.

3. The lower body structure according to claim 1 or 2, wherein the second part has a shape in which the rigidity against loads from the outside in the vehicle width direction increases toward the inside in the vehicle width direction.

4. The first part and the second part are arranged adjacent to each other in the front-to-back direction. The lower body structure according to claim 1 or 2, wherein the second portion has a shape in which the rigidity against loads from the outside in the width direction increases as it approaches the first portion in the front-rear direction.

5. The lower body structure according to claim 1 or 2, wherein the second portion has a hole formed therethrough in the vertical direction.

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