VEHICLE LOWER BODY STRUCTURE

TECHNICAL FIELD

The technique disclosed herein belongs to a technical field related to a lower body structure of a vehicle.

BACKGROUND

In the case of a hybrid vehicle or an electric vehicle, generally, a battery is disposed below a floor panel. In such a vehicle, a body structure for absorbing collision energy so that a collision load during a side collision is not transmitted to the battery has been studied.

Japan Patent Document JP2022-531463A discloses a side sill component including: a first profile component that is located on a relatively outer side in a vehicle width direction and has first breakability; and a second profile component that is located on a relatively inner side in the vehicle width direction and has second breakability lower than the first breakability. In JP2022-531463A, a first profile member and a second profile member are crushed during the side collision so as to absorb the collision energy.

SUMMARY

In the configuration of JP2022-531463A, there is a possibility that the collision load that cannot be sufficiently absorbed by crushing of the first profile member is transmitted to the battery via the second profile member without crushing the second profile member. Therefore, there is room for improvement from a viewpoint of preventing the transmission of the collision load to the battery.

A technique disclosed herein has been made in view of the above point, to prevent a collision load during a side collision from being transmitted to a battery.

In order to solve the above problem, a first aspect of the technique disclosed herein is directed to a vehicle lower body structure and includes: a pair of left and right side sills, each of which has a closed cross-sectional structure extending in a vehicle front-rear direction; a floor panel fixed to the side sills and constituting a floor surface of a cabin; a battery disposed below the floor panel; a cross member that extends in a vehicle width direction, and each end portion of which in the vehicle width direction is fixed to a respective one of the side sills at a position above the floor panel.

Each side sill has: an outer wall portion that is a wall surface located on an outer side in the vehicle width direction and extending in an up-down direction and the vehicle front-rear direction; an inner wall portion that is a wall surface located on an inner side in the vehicle width direction and extending in the up-down direction and the vehicle front-rear direction; an upper wall portion extending in the vehicle width direction from an upper end portion of the outer wall portion and an upper end portion of the inner wall portion; a lower wall portion extending in the vehicle width direction from a lower end portion of the outer wall portion and a lower end portion of the inner wall portion; an outer reinforcement fixed to the outer wall portion in the closed cross-sectional structure; and an inner reinforcement fixed to the upper wall portion and the inner wall portion in the closed cross-sectional structure. The cross member is fixed to the upper wall portion, the outer reinforcement has an overlapping portion that is located on an inner side of other portions of the outer reinforcement in the vehicle width direction, and a position of which overlaps a position of the inner reinforcement in the up-down direction, the inner reinforcement has a vertical surface portion fixed to the upper wall portion and the inner wall portion and extending in the up-down direction and the vehicle width direction, and the vertical surface portion has a load transmission promoting portion, a position of which overlaps a position of the cross member in the vehicle front-rear direction, and which transmits a collision load applied via the overlapping portion during a side collision to the cross member.

In the first aspect, when the outer wall portion is displaced inward in the vehicle width direction by the side collision, the overlapping portion of the outer reinforcement abuts the inner reinforcement. Since the inner reinforcement has the vertical surface portion fixed to the upper wall portion and the inner wall portion of the side sill, and the vertical surface portion has the load transmission promoting portion, a load transmitted from the outer reinforcement to the inner reinforcement is transmitted inward in the vehicle width direction and upward via the load transmission promoting portion. Since the cross member is fixed to the portion of the side sill that is located on the inner side in the vehicle width direction and above the battery, the collision load is transmitted from the inner reinforcement to the cross member. As it has been described so far, the transmission of the collision load to the battery disposed below the floor panel is prevented.

According to a second aspect, in the first aspect, a position of an outer end portion of the load transmission promoting portion in the vehicle width direction overlaps the position of the overlapping portion in the up-down direction, and a position of an inner end portion of the load transmission promoting portion in the vehicle width direction overlaps a position of the cross member in the up-down direction.

In the second aspect, the collision load is efficiently transmitted from the outer reinforcement to the cross member via the load transmission promoting portion. Accordingly, it is possible to prevent the transmission of the collision load during the side collision to the battery.

According to a third aspect, in the second aspect, a center of the vertical surface portion in the up-down direction is located above a center of the overlapping portion in the up-down direction and below a center of the cross member in the up-down direction.

In the third aspect, the collision load is efficiently transmitted from the position on the outer side in the vehicle width direction and the lower side to the position on the inner side in the vehicle width direction and the upper side via the load transmission promoting portion.

Further, even in the case where the vertical surface portion is rotationally displaced due to the collision load when the overlapping portion of the outer reinforcement abuts the inner reinforcement, the vertical surface portion is rotationally displaced inward in the vehicle width direction and upward toward the cross member. Thus, a transmission path of the collision load from the outer reinforcement to the cross member is easily maintained.

Therefore, it is possible to prevent the transmission of the collision load during the side collision to the battery.

According to a fourth aspect, in the third aspect, the load transmission promoting portion is a portion having higher rigidity than other portions of the vertical surface portion.

In the fourth aspect, the load transmission promoting portion is more likely to transmit the collision load than other portions of the vertical surface portion. Accordingly, since the collision load is efficiently transmitted from the outer reinforcement to the cross member via the load transmission promoting portion, it is possible to prevent the transmission of the collision load during the side collision to the battery.

According to a fifth aspect, in the fourth aspect, the load transmission promoting portion is a bead portion extending continuously from an outer end portion in the vehicle width direction to an inner end portion in the vehicle width direction.

In the fifth aspect, the load transmission promoting portion can be easily configured.

According to a sixth aspect, in the first aspect, the overlapping portion has a surface extending in the vehicle front-rear direction and the up-down direction, and a position thereof overlaps the position of the cross member in the vehicle front-rear direction.

In the sixth aspect, since the overlapping portion comes into contact with the vertical surface portion in the widest possible range, the collision load can be distributed and applied to the vertical surface portion. When the collision load is distributed and applied to the vertical surface portion, crushing of the vertical surface portion can be prevented as much as possible. Meanwhile, even when the collision load is distributed and applied to the vertical surface portion, the collision load is efficiently transmitted toward the cross member by the load transmission promoting portion. Further, since a position of the overlapping portion overlaps a position of the cross member in the vehicle front-rear direction, the transmission path of the collision load can be shortened as much as possible. Accordingly, it is possible to prevent the transmission of the collision load during the side collision to the battery.

According to a seventh aspect, in the sixth aspect, the outer reinforcement has: an upper surface portion extending outward in the vehicle width direction from an upper end of the overlapping portion toward the outer wall portion; and a lower surface portion extending outward in the vehicle width direction from a lower end of the overlapping portion toward the outer wall portion.

In the seventh aspect, the outer wall portion and the outer reinforcement can constitute the closed cross section, and the rigidity of the outer reinforcement is improved. Accordingly, the collision load can be efficiently transmitted from the outer reinforcement to the vertical surface portion, and the collision load during the side collision can be prevented from being transmitted to the battery.

According to an eighth aspect, in the sixth aspect, the battery is supported on a portion of the lower wall portion that is located on the inner side of the overlapping portion in the vehicle width direction, and a lower end of the overlapping portion is located above the lower wall portion. In the eighth aspect, the collision load is less likely to be transmitted directly from the overlapping portion to the battery. Accordingly, it is possible to prevent the transmission of the collision load during the side collision to the battery.

According to a ninth aspect, in the eighth aspect, the inner reinforcement has a horizontal surface portion, a position of which overlaps a position of an area where the battery is disposed in the vehicle front-rear direction, which extends in the vehicle front-rear direction and the vehicle width direction, and which is fixed to the inner wall portion, and the horizontal surface portion is located between the lower wall portion and the vertical surface portion in the up-down direction.

In the ninth aspect, even in the case where the vertical surface portion is rotationally displaced due to the collision load when the overlapping portion of the outer reinforcement abuts the inner reinforcement, it is possible to prevent the vertical surface portion from being displaced downward by the horizontal surface portion. Accordingly, it is possible to prevent the direct transmission of the collision load to the support portion of the battery.

According to a tenth aspect, in the ninth aspect, the vertical surface portion is fixed to the horizontal surface portion.

In the tenth aspect, even when a position of the side collision is a position other than the position of the vertical surface portion, the collision load is transmitted to the vertical surface portion via the horizontal surface portion. Accordingly, the collision load is efficiently transmitted from the outer reinforcement to the cross member via the horizontal surface portion and the vertical surface portion. As a result, it is possible to prevent the transmission of the collision load during the side collision to the battery.

As it has been described so far, according to the technique disclosed herein, it is possible to prevent the collision load during the side collision from being transmitted to the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a body of a vehicle having a lower body structure according to an exemplary embodiment.

FIG. 2 is a cross-sectional view taken along a plane corresponding to line II-II in FIG. 1.

FIG. 3 is a cross-sectional view taken along a plane corresponding to line III-III in FIG. 2.

FIG. 4 is a cross-sectional view taken along a plane corresponding to line IV-IV in FIG. 3.

FIG. 5 is a perspective view of a first inner reinforcement.

FIG. 6 is a perspective view of a second inner reinforcement.

FIG. 7 is a perspective view illustrating a joint portion between the second inner reinforcement and an inner panel.

FIG. 8 is a perspective view illustrating a joint portion between the first inner reinforcement and the second inner reinforcement.

FIG. 9 is a cross-sectional view taken along a plane corresponding to line IX-IX in FIG. 3.

FIG. 10 is a cross-sectional view illustrating a state where a collision body abuts a side sill during a side collision.

FIG. 11 is a cross-sectional view illustrating a state where the collision body enters vehicle interior from the state in FIG. 10.

FIG. 12 is a cross-sectional view illustrating a state where the collision body further enters the vehicle interior from the state in FIG. 11 and the second inner reinforcement is crushed.

FIG. 13 is a view corresponding to FIG. 2 illustrating a first modified example of the lower body structure.

FIG. 14 is a view corresponding to FIG. 2 illustrating a third modified example of the lower body structure.

DETAILED DESCRIPTION

Exemplary embodiments will now be described in detail with reference to the drawings. In the following description, the front, rear, left, right, up, and down of a vehicle 1 are simply referred to as the front, rear, left, right, up, and down, respectively. A left-right direction corresponds to a vehicle width direction.

Overall Configuration of Lower Body

FIG. 1 illustrates a lower body of the vehicle 1 to which a body structure according to the present embodiment is applied. The vehicle 1 is a four-door type passenger vehicle. In the present embodiment, the body structure of the vehicle 1 is configured to be bilaterally symmetrical.

The vehicle 1 includes a pair of left and right side sills 2. Each of the side sills 2 extends straight in a front-rear direction. As will be described in detail below, each of the side sills 2 has a closed cross-sectional structure, and the closed cross section extends straight in the front-rear direction.

The vehicle 1 includes a floor panel 3 that constitutes a floor surface of a cabin. A pair of the left and right floor panels 3 is provided. Each of the floor panels 3 has: a floor panel main body 3a (see FIG. 2 and the like) extending in the vehicle width direction and the front-rear direction; and a floor panel joint portion 3b (see FIG. 2 and the like) fixed to the respective side sill 2 by welding. The floor panel joint portion 3b of the left floor panel 3 is provided in a left end portion, and is fixed to a right portion of the left side sill 2 by welding. The floor panel joint portion 3b of the right floor panel 3 is provided in a right end portion, and is fixed to a left portion of the right side sill 2 by welding. A right end portion of the left floor panel 3 and a left end portion of the right floor panel 3 are coupled by a tunnel panel 4.

At a rear end of the floor panel 3, a kick-up portion 5 that rises upward is disposed. A rear floor panel 6 extends rearward from the kick-up portion 5. The rear floor panel 6 mainly constitutes a floor surface of a baggage compartment. A pair of left and right rear wheel houses 7 is respectively arranged on both left and right sides of the rear floor panel 6.

Two cross members 60 extending along the left-right direction are disposed on an upper side of the floor panel 3. The two cross members 60 are aligned in the front-rear direction. A position of the rear cross member 60 in the front-rear direction is the same as a position of a center pillar 9 (see FIG. 2 and the like) in the front-rear direction.

The cross member 60 includes a cross member body 61 and brackets 62. The brackets 62 are respectively fixed to both sides of the cross member body 61 in the left-right direction. The brackets 62 are fixed to the cross member body 61. The left bracket 62 is fixed to the left side sill 2 by welding, and the right bracket 62 is fixed to the right side sill 2 by welding. As a result, end portions of the cross member 60 in the left-right direction are fixed to the side sills 2. A lower end of the cross member body 61 is fixed to an upper surface of the floor panel 3 and an upper surface of the tunnel panel 4.

A pair of left and right floor frames 8 is arranged in front of the front cross member 60. The floor frames 8 each extend in the front-rear direction.

As illustrated in FIG. 2, a battery B is disposed below the floor panel 3. In a state of being accommodated in a battery case 70, the battery B is disposed below the floor panel 3.

The battery B is supported by a lower wall portion (an inner lower wall portion 22 described below) of the side sill 2 together with the battery case 70 via a support portion 80. More specifically, a bracket 71 extending outward in the vehicle width direction is fixed to an outer portion (a right portion in FIG. 2) of the battery case 70 in the vehicle width direction. A hole 71a through which a bolt 81 is inserted is formed in an outer end portion (a right end portion in FIG. 2) of the bracket 71 in the vehicle width direction. The bolt 81 is fastened to a nut 82 fixed to a portion in a closed cross section of the lower wall portion of the side sill 2. The bolt 81 is inserted into the hole 71a of the bracket 71 from below and fixed to the nut 82. Accordingly, the battery B is supported by the side sill 2 via the battery case 70 and the bracket 71. The bolt 81 and the nut 82 constitute the support portion 80. Between the bracket 71 and an inner lower wall portion 22, a bush 72 is disposed around the bolt 81. The bush 72 is formed of an elastic member. Although not illustrated in the drawing, a center portion of each of the battery cases 70 in the vehicle width direction is attached to and supported by the tunnel panel 4.

Configuration of Side Sill

Hereinafter, a configuration of the side sill 2 will be described in detail. As described above, since the body structure of the vehicle 1 is bilaterally symmetrical, the configuration of the right side sill 2 will be described in detail below, and the detailed description of the left side sill 2 will be omitted. In the description of the right side sill 2, the right side corresponds to the outer side in the vehicle width direction, and the left side corresponds to the inner side in the vehicle width direction.

Outer Panel, Inner Panel

As illustrated in FIG. 2, the side sill 2 has an outer panel 10 located on the relatively right side and an inner panel 20 located on the relatively left side.

The outer panel 10 has a hat-shaped cross-sectional shape that opens to the left. The outer panel 10 has: an outer upper wall portion 11 extending in the left-right direction and the front-rear direction; an outer lower wall portion 12 located below the outer upper wall portion 11 to oppose the outer upper wall portion 11 in an up-down direction and extending in the left-right direction and the front-rear direction; and an outer wall portion 13 connecting a right end portion of the outer upper wall portion 11 and a right end portion of the outer lower wall portion 12 in the up-down direction and extending in the up-down direction and the front-rear direction. An outer flange 14 extends in the up-down direction from a left end portion of the outer upper wall portion 11 and a left end portion of the outer lower wall portion 12. The outer upper wall portion 11 is inclined downward to the right. The outer lower wall portion 12 is inclined upward to the right. At a position of the center pillar 9 in the front-rear direction, a lower end portion of the center pillar 9 is located on the right side of the outer panel 10. The lower end portion of the center pillar 9 is fixed to the outer panel 10 by welding.

The inner panel 20 has a hat-shaped cross-sectional shape that opens to the right. The inner panel 20 has: an inner upper wall portion 21 extending in the left-right direction and the front-rear direction; the inner lower wall portion 22 located below the inner upper wall portion 21 to oppose the inner upper wall portion 21 in the up-down direction and extending in the left-right direction and the front-rear direction; and an inner wall portion 23 connecting a left end portion of the inner upper wall portion 21 and a left end portion of the inner lower wall portion 22 in the up-down direction and extending in the up-down direction and the front-rear direction. An inner flange 24 extends in the up-down direction from a right end portion of the inner upper wall portion 21 and a right end portion of the inner lower wall portion 22. The inner upper wall portion 21 is inclined downward to the left. The inner lower wall portion 22 extends straight in the left-right direction. The inner lower wall portion 22 has a hole 22a through which the bolt 81 is inserted.

In a state where the openings of the outer panel 10 and the inner panel 20 face each other in the left-right direction, the outer flange 14 and the inner flange 24 are superimposed in the left-right direction. The outer flange 14 and the inner flange 24 are joined by welding. Accordingly, the side sill 2 has a rectangular closed cross-sectional structure including the outer upper wall portion 11, the outer lower wall portion 12, the outer wall portion 13, the inner upper wall portion 21, the inner lower wall portion 22, and the inner wall portion 23.

The floor panel 3 and the cross member 60 are fixed to the inner panel 20. More specifically, as illustrated in FIG. 2, the floor panel joint portion 3b of the floor panel 3 is configured by bending the right end portion of the floor panel main body 3a upward, extends along the inner wall portion 23, and is joined to a left surface of the inner wall portion 23. The bracket 62 of the cross member 60 is disposed to cover a corner portion between the inner upper wall portion 21 and the inner wall portion 23. The bracket 62 has a welding margin 63 extending continuously along the inner upper wall portion 21 and the inner wall portion 23. A portion of the welding margin 63 along the inner upper wall portion 21 is joined to the inner upper wall portion 21. A portion of the welding margin 63 along the inner wall portion 23 is superimposed on the right end portion of the floor panel 3 in the left-right direction, and is joined to the inner wall portion 23 via the floor panel 3. FIG. 2 illustrates a fixing structure of the rear cross member 60 and the inner panel 20. The structure of the front cross member 60 and the inner panel 20 is the same as the fixing structure of the rear cross member 60 and the inner panel 20.

Outer Reinforcement

An outer reinforcement 30 is fixed to the outer panel 10 in the closed cross-sectional structure of the side sill 2. The outer reinforcement 30 is formed by bending a single plate. Material strength of the outer reinforcement 30 is lower than material strength of the cross member body 61. Here, the material strength means strength of the plate itself constituting the member. The material strength is a parameter determined by, for example, tensile strength and thickness of the plate. The material strength is increased as the tensile strength is increased, and is increased as the thickness is increased.

The outer reinforcement 30 has a hat-shaped cross-sectional shape that opens to the right. The outer reinforcement 30 has: an upper surface portion 31 extending in the left-right direction and the front-rear direction; a lower surface portion 32 located below the upper surface portion 31 to oppose the upper surface portion 31 and extending in the left-right direction and the front-rear direction; and a connection surface portion 33 connecting a left end portion of the upper surface portion 31 and a left end portion of the lower surface portion 32 in the up-down direction and extending in the up-down direction and the front-rear direction. The outer reinforcement 30 also has: an upper flange 34 that extends upward from a right end portion of the upper surface portion 31 along the outer wall portion 13 and is fixed to the outer wall portion 13 by welding; and a lower flange 35 that extends downward from a right end portion of the lower surface portion 32 along the outer wall portion 13 and is fixed to the outer wall portion 13 by welding. When the upper flange 34 and the lower flange 35 are fixed to the outer wall portion 13, the outer wall portion 13, the upper surface portion 31, the lower surface portion 32, and the connection surface portion 33 form a rectangular closed cross section.

The upper surface portion 31 is inclined upward to the right from an upper end portion of the connection surface portion 33. The lower surface portion 32 is inclined downward to the left from a lower end portion of the connection surface portion 33. The connection surface portion 33 is a vertical surface extending straight in the up-down direction and the front-rear direction. The upper surface portion 31 is located at the same position as the floor panel main body 3a in the up-down direction. The connection surface portion 33 is spaced apart from the outer wall portion 13 in the left-right direction and is located on the left side of other portions of the outer reinforcement 30. A lower end of the connection surface portion 33 is located above the outer lower wall portion 12 and the inner lower wall portion 22. The lower end of the connection surface portion 33 is located above a tip of the bolt 81 of the support portion 80. The connection surface portion 33 corresponds to an overlapping portion, a position of which overlaps a position of an inner reinforcement 40 described below in the up-down direction.

As illustrated in FIG. 3, the outer reinforcement 30 extends straight in the front-rear direction. A front end of the outer reinforcement 30 is located in front of the front cross member 60, and a rear end of the outer reinforcement 30 is located behind the rear cross member 60. That is, a position of the outer reinforcement 30 overlaps a position of the cross member 60 in the front-rear direction. In addition, the outer reinforcement 30 overlaps an area where the battery B is disposed in the front-rear direction.

As illustrated in FIG. 4, a corner portion between the lower surface portion 32 and the lower flange 35 has a deformation promoting portion 36. The deformation promoting portion 36 promotes upward displacement of the lower surface portion 32 around the corner portion. The deformation promoting portion 36 is a bead formed by protruding the corner portion leftward and downward. A bottom surface of the deformation promoting portion 36 has an inclined surface shape that connects the right end portion of the lower surface portion 32 and an upper end portion of the lower flange 35. A deformation promoting portion as described above is not provided in a corner portion between the upper surface portion 31 and the upper flange 34. A position of the deformation promoting portion 36 overlaps a position of a lateral surface portion 44 of a second inner reinforcement 42, which will be described below, in the front-rear direction. The bottom surface of the deformation promoting portion 36 may have a curved shape having a larger radius of curvature than a radius of curvature of a portion other than the deformation promoting portion 36 in the corner portion. In addition, the deformation promoting portion 36 may be formed by cutting out a part of the corner portion between the lower surface portion 32 and the lower flange 35.

Inner Reinforcement

In the closed cross section of the side sill 2, the inner reinforcement 40 is fixed to the inner panel 20. As illustrated in FIG. 3, the position of the inner reinforcement 40 overlaps the position of the outer reinforcement 30 in the front-rear direction. That is, the position of the connection surface portion 33 of the outer reinforcement 30 overlaps the position of the inner reinforcement 40 in the front-rear direction. The inner reinforcement 40 has a first inner reinforcement 41 and the second inner reinforcement 42.

As illustrated in FIG. 4, the first inner reinforcement 41 is formed of a single plate. Material strength of the first inner reinforcement 41 is lower than the material strength of the outer reinforcement 30.

As illustrated in FIGS. 4 and 5, the first inner reinforcement 41 has a U-shaped cross-sectional shape that opens upward. The first inner reinforcement 41 has: a horizontal surface portion 41a extending in the left-right direction and the front-rear direction; an inner bent portion 41b bent upward from a left end portion of the horizontal surface portion 41a and extending in the up-down direction and the front-rear direction; and an outer bent portion 41c bent upward from a right end portion of the horizontal surface portion 41a and extending in the up-down direction and the front-rear direction.

As illustrated in FIG. 4, the horizontal surface portion 41a is located above the inner lower wall portion 22 and is spaced apart from the inner lower wall portion 22 in the up-down direction. The horizontal surface portion 41a is located above the tip of the bolt 81. The horizontal surface portion 41a is located below the second inner reinforcement 42. That is, the horizontal surface portion 41a is located between the inner lower wall portion 22 and the second inner reinforcement 42 in the up-down direction. The horizontal surface portion 41a is located below the lower end of the connection surface portion 33. A position of the horizontal surface portion 41a overlaps a position of the area where the battery B is provided in the front-rear direction.

A length of the inner bent portion 41b in the up-down direction is longer than a length of the outer bent portion 41c in the up-down direction. A position of the inner bent portion 41b overlaps the position of the connection surface portion 33 in the up-down direction. The inner bent portion 41b is fixed to a right side surface of the inner wall portion 23 by welding. Thus, the horizontal surface portion 41a is fixed to the inner wall portion 23.

As illustrated in FIG. 5, the outer bent portion 41c has a plurality of (five in FIG. 5) protruding portions 41d protruding upward. The protruding portions 41d are spaced apart from each other in the front-rear direction. An upper end portion of each of the protruding portions 41d is located below an upper end portion of the inner bent portion 41b. As illustrated in FIG. 4, a position of each of the protruding portions 41d overlaps the position of the connection surface portion 33 in the up-down direction. As illustrated in FIG. 2, a portion of the outer bent portion 41c other than the protruding portions 41d is located below the connection surface portion 33.

As illustrated in FIG. 3, a plurality of (here, five) second inner reinforcements 42 are provided. The second inner reinforcements 42 are spaced apart from each other in the front-rear direction. The protruding portions 41d of the first inner reinforcement 41 are respectively disposed in a manner to correspond to the positions of the second inner reinforcements 42. A position of one of the second inner reinforcements 42 overlaps a position of the front cross member 60 in the front-rear direction. A position of the other one of the second inner reinforcements 42 overlaps the position of the rear cross member 60 in the front-rear direction. The position of each of the second inner reinforcements 42 overlaps the position of the connection surface portion 33 in the front-rear direction.

As illustrated in FIG. 6, the second inner reinforcement 42 is formed of a single plate. Material strength of the second inner reinforcement 42 is the same as the material strength of the first inner reinforcement 41 and is lower than the material strength of the outer reinforcement 30.

The second inner reinforcement 42 has: a pair of vertical surface portions 43 opposing each other in the front-rear direction and extending in the up-down direction and the left-right direction; and the lateral surface portion 44 extending in the front-rear direction and the up-down direction so as to connect right end portions of the paired vertical surface portions 43. The lateral surface portion 44 is provided at a center of the right end portion of the vertical surface portion 43. In the right end portion of the vertical surface portion 43, the lateral surface portion 44 is not connected to an upper end portion and a lower end portion thereof. A distance between the paired vertical surface portions 43 in the front-rear direction is shorter than a width of the cross member 60 in the front-rear direction. In the second inner reinforcement 42 whose position overlaps the position of the cross member 60 in the front-rear direction, positions of both of the paired vertical surface portions 43 overlap the position of the cross member 60 in the vehicle front-rear direction.

As illustrated in FIG. 4, the vertical surface portion 43 has a rectangular shape. The position of the vertical surface portion 43 overlaps the position of the connection surface portion 33 in the up-down direction. A center C2 of the vertical surface portion 43 in the up-down direction is located above a center C1 of the connection surface portion 33 in the up-down direction. The center C2 of the vertical surface portion 43 in the up-down direction is located below a center C3 of the cross member 60 in the up-down direction.

The vertical surface portion 43 has a bead 43a that extends while being inclined upward to the left from the right side. As illustrated in FIGS. 2 and 4, a position of a right end portion of the bead 43a overlaps the position of the connection surface portion 33 of the outer reinforcement 30 in the up-down direction. A left end portion of the bead 43a is located above the floor panel 3, and a position thereof overlaps the position of the cross member 60 in the up-down direction. The left end portion of the bead 43a is located below the center C3 of the cross member 60 in the up-down direction. The portion of the bead 43a has higher rigidity than the other portions of the vertical surface portion 43. The vertical surface portion 43 has through holes 43b on an upper right side and a lower left side of the bead 43a. The bead 43a corresponds to a load transmission promoting portion.

As illustrated in FIG. 6, the vertical surface portion 43 has a first upper joint portion 45 and a second upper joint portion 46 in an upper end portion thereof. The first upper joint portion 45 is located on the right side of the second upper joint portion 46. The vertical surface portion 43 has a first inner joint portion 47 and a second inner joint portion 48 in a left end portion thereof. The first inner joint portion 47 is located above the second inner joint portion 48. The vertical surface portion 43 has a lower joint portion 49 in a lower end portion thereof. The first upper joint portion 45, the second upper joint portion 46, the first inner joint portion 47, the second inner joint portion 48, and the lower joint portion 49 extend forward in the front vertical surface portion 43 while extending rearward in the rear vertical surface portion 43.

As illustrated in FIGS. 7 and 9, the first upper joint portion 45 and the second upper joint portion 46 are joined to a lower surface of the inner upper wall portion 21. As illustrated in FIG. 9, the first upper joint portion 45 and the second upper joint portion 46 are located above the connection surface portion 33. The second upper joint portion 46 is superimposed on and joined to the inner upper wall portion 21 and the welding margin 63 of the bracket 62 in the up-down direction. That is, at a position of the second upper joint portion 46, three of the second upper joint portion 46, the inner upper wall portion 21, and the welding margin 63 of the bracket 62 are joined.

As illustrated in FIGS. 7 and 9, the first inner joint portion 47 is joined to the right side surface of the inner wall portion 23. As illustrated in FIG. 9, the first inner joint portion 47 is superimposed on and joined to the inner wall portion 23 and the floor panel joint portion 3b in the left-right direction. That is, at a position of the first inner joint portion 47, three of the first inner joint portion 47, the inner wall portion 23, and the floor panel joint portion 3b are joined. The position of the first inner joint portion 47 overlaps a position of an upper end portion of the bead 43a in the up-down direction.

As illustrated in FIGS. 7 and 9, the second inner joint portion 48 is joined to a right side surface of the inner bent portion 41b. As illustrated in FIG. 9, the second inner joint portion 48 is superimposed on and joined to the inner bent portion 41b and the inner wall portion 23 in the left-right direction. That is, at a position of the second inner joint portion 48, three of the second inner joint portion 48, the inner bent portion 41b, and the inner wall portion 23 are joined. The position of the second inner joint portion 48 overlaps the position of the connection surface portion 33 in the up-down direction.

As illustrated in FIGS. 8 and 9, the lower joint portion 49 is joined to an upper surface of the horizontal surface portion 41a. The lower joint portion 49 has a wider joint width than the first upper joint portion 45, the second upper joint portion 46, the first inner joint portion 47, and the second inner joint portion 48. As illustrated in FIG. 9, the lower joint portion 49 is located below the connection surface portion 33.

As described above, the vertical surface portion 43 is joined and fixed to the horizontal surface portion 41a, the inner bent portion 41b, the inner upper wall portion 21, and the inner wall portion 23. Since three sides of the upper end portion, the left end portion, and the lower end portion of the vertical surface portion 43 are fixed, it is easy to maintain a shape thereof even when a load is applied thereto from the right side.

As illustrated in FIG. 6, the lateral surface portion 44 is located below the first upper joint portion 45 and the second upper joint portion 46 and above the lower joint portion 49. The lateral surface portion 44 has a recessed portion 44a, which is recessed downward, at a center in the front-rear direction. As illustrated in FIG. 4, a position of the lateral surface portion 44 overlaps the position of the connection surface portion 33 in the up-down direction. The lateral surface portion 44 is spaced apart from the connection surface portion 33 in the left-right direction. The lateral surface portion 44 is located on the right side of the protruding portion 41d and overlaps the protruding portion 41d in the left-right direction. The lateral surface portion 44 is fixed to the protruding portion 41d by welding.

Operation of Side Sill During Side Collision

Here, in the structure in which the battery B is disposed under the floor panel 3, it is required to prevent application of a collision load during a side collision to the battery B as much as possible. Therefore, in the present embodiment, as described above, the outer reinforcement 30 and the inner reinforcement 40 are arranged so that the collision load during the side collision is transmitted to the floor panel 3 and the cross member 60. Hereinafter, operation of the side sill during the side collision will be described with reference to FIGS. 10 to 12. FIGS. 10 to 12 each illustrate a case where a collision body M collides with a position near the center pillar 9 from the right side.

As illustrated in FIG. 10, it is assumed that the collision body M is advanced to the left and abuts the side sill 2. At this time, the outer panel 10 is deformed, and the outer reinforcement 30 is displaced to the left side. As a result, the connection surface portion 33 of the outer reinforcement 30 and the second inner reinforcement 42 abut each other. The connection surface portion 33 abuts a portion of the second inner reinforcement 42 located below the first upper joint portion 45 and the second upper joint portion 46 and above the lower joint portion 49, in particular, the lateral surface portion 44.

When the connection surface portion 33 and the second inner reinforcement 42 abut each other, the collision load is transmitted from the outer reinforcement 30 to the second inner reinforcement 42. Since the second inner reinforcement 42 has the vertical surface portion 43 fixed to the inner upper wall portion 21 and the inner wall portion 23 and the vertical surface portion 43 has the bead 43a, the collision load is transmitted leftward and upward via the bead 43a. Since the floor panel 3 and the cross member 60 are fixed to the left and upper portions of the side sill 2, the collision load is transmitted from the second inner reinforcement 42 to the floor panel 3 and the cross member 60.

From the state in FIG. 10, as illustrated in FIG. 11, when the collision body M enters the left side, the outer reinforcement 30 is deformed by a repulsive load from the vertical surface portion 43. The lower surface portion 32 of the outer reinforcement 30 has the deformation promoting portion 36 in the corner portion between the lower surface portion 32 and the lower flange 35, and thus is easily displaced when compared to the upper surface portion 31. Therefore, when the repulsive load is applied, the lower surface portion 32 is rotationally displaced upward with the corner portion being a fulcrum. Along with the displacement of the lower surface portion 32, the upper surface portion 31 and the connection surface portion 33 are displaced upward. Accordingly, the second inner reinforcement 42 is pushed upward to the left. As a result, the collision load is efficiently transmitted from the outer reinforcement 30 to the floor panel 3 and the cross member 60.

The second inner reinforcement 42 is rotationally displaced by the collision load. Since the center C2 of the vertical surface portion 43 in the up-down direction is located above the center C1 of the connection surface portion 33 in the up-down direction, the second inner reinforcement 42 is rotationally displaced upward to the left. Therefore, even when the second inner reinforcement 42 is rotationally displaced, the collision load is efficiently transmitted from the outer reinforcement 30 to the floor panel 3 and the cross member 60.

In addition, the left end portion of the bead 43a is located below the center C3 of the cross member 60 in the up-down direction. Thus, even when the second inner reinforcement 42 is rotationally displaced upward, the bead 43a and the cross member 60 tend to remain overlapping each other in the up-down direction. Accordingly, the collision load is efficiently transmitted from the outer reinforcement 30 to the cross member 60.

From the state in FIG. 11, as illustrated in FIG. 12, when the collision body M enters the left side, the second inner reinforcement 42 is crushed. Since the material strength of the second inner reinforcement 42 is lower than the material strength of the outer reinforcement 30, the second inner reinforcement 42 is crushed before the outer reinforcement 30. Crushing of the second inner reinforcement 42 absorbs a part of the collision load. Since the connection surface portion 33 abuts a portion of the second inner reinforcement 42 that is located below the first upper joint portion 45 and the second upper joint portion 46 and above the lower joint portion 49, the shapes of the upper end portion, the left end portion, and the lower end portion are easily maintained. Thus, the absorption of the collision load due to crushing of the second inner reinforcement 42 and the transmission of the load via the second inner reinforcement 42 can be performed simultaneously.

Effects of the Embodiment

As it has been described so far, in the present embodiment, the side sill 2 has: the outer wall portion 13 that is the wall surface located on the outer side in the vehicle width direction and extending in the up-down direction and the front-rear direction; the inner wall portion 23 that is the wall surface located on the inner side in the vehicle width direction and extending in the up-down direction and the front-rear direction; the outer upper wall portion 11 that extends in the vehicle width direction from the upper end portion of the outer wall portion 13; the inner upper wall portion 21 that extends in the vehicle width direction from the upper end portion of the inner wall portion 23; the outer lower wall portion 12 that extends in the vehicle width direction from the lower end portion of the outer wall portion 13; the inner lower wall portion 22 that extends in the vehicle width direction from the lower end portion of the inner wall portion 23; the outer reinforcement 30 that is fixed to the outer wall portion 13 in the closed cross-sectional structure; and the inner reinforcement 40 that is fixed to the inner upper wall portion 21 and the inner wall portion 23 in the closed cross-sectional structure. The cross member 60 is fixed to the inner upper wall portion 21, the battery B is supported by the inner lower wall portion 22, the outer reinforcement 30 has the connection surface portion 33 that is located on the inner side of the other portions of the outer reinforcement 30 in the vehicle width direction and the position of which overlaps the position of the inner reinforcement 40 in the up-down direction, the inner reinforcement 40 has the vertical surface portion 43 fixed to the inner upper wall portion 21 and the inner wall portion 23 and extending in the up-down direction and the vehicle width direction, and the vertical surface portion 43 has the bead 43a, the position of which overlaps the position of the cross member 60 in the vehicle front-rear direction, and which transmits the collision load applied via the connection surface portion 33 during the side collision to the cross member 60. As a result, when the outer wall portion 13 is displaced inward in the vehicle width direction by the side collision, the connection surface portion 33 abuts the inner reinforcement 40. Since the inner reinforcement 40 has the vertical surface portion 43 fixed to the inner upper wall portion 21 and the inner wall portion 23 and the vertical surface portion 43 has the bead 43a, the load transmitted from the outer reinforcement 30 to the inner reinforcement 40 is transmitted inward in the vehicle width direction and upward via the bead 43a. Since the cross member 60 is fixed to the portion of the side sill 2 located on the inner side in the vehicle width direction and above the battery B, the collision load is transmitted from the inner reinforcement 40 to the cross member 60. As described above, the transmission of the collision load to the battery B, which is disposed below the floor panel 3, is prevented.

In addition, since the bead 43a has the higher rigidity than the other portions of the vertical surface portion 43, the collision load is more easily transmitted than the other portions of the vertical surface portion 43. Accordingly, since the collision load is efficiently transmitted from the outer reinforcement 30 to the cross member 60 via the bead 43a, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

In addition, since the bead 43a can be easily formed, the load transmission promoting portion can be easily provided.

In the present embodiment, an outer end portion of the bead 43a in the vehicle width direction overlaps the position of the connection surface portion 33 in the up-down direction, and an inner end portion of the bead 43a in the vehicle width direction overlaps the cross member 60 in the up-down direction. Accordingly, the collision load is efficiently transmitted from the outer reinforcement 30 to the cross member 60 via the bead 43a. As a result, it is possible to prevent the transmission of the collision load during the side collision to the battery.

In the present embodiment, the center C2 of the vertical surface portion 43 in the up-down direction is located above the center C1 of the connection surface portion 33 in the up-down direction and below the center C3 of the cross member 60 in the up-down direction. Accordingly, the collision load is efficiently transmitted from the position on the outer side in the vehicle width direction and the lower side to the position on the inner side in the vehicle width direction and the upper side via the bead 43a. Further, even in the case where the vertical surface portion 43 is rotationally displaced due to the collision load when the connection surface portion 33 abuts the inner reinforcement 40, the vertical surface portion 43 is rotationally displaced inward in the vehicle width direction and upward toward the cross member 60. Therefore, the transmission path of the collision load from the outer reinforcement 30 to the cross member 60 is easily maintained. Therefore, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

In the present embodiment, the connection surface portion 33 has the surface extending in the vehicle front-rear direction and the up-down direction, and the position thereof overlaps the position of the cross member 60 in the vehicle front-rear direction. In this way, since the connection surface portion 33 contacts the vertical surface portion 43 in the widest possible range, the collision load can be distributed and applied to the vertical surface portion 43. When the collision load is distributed and applied to the vertical surface portion 43, crushing of the vertical surface portion 43 can be prevented as much as possible. Meanwhile, even when the collision load is distributed and applied to the vertical surface portion 43, the collision load is efficiently transmitted toward the cross member 60 by the bead 43a. In addition, since the position of the connection surface portion 33 overlaps the position of the cross member 60 in the vehicle front-rear direction, the transmission path of the collision load can be shortened as much as possible. Accordingly, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

In the present embodiment, the outer reinforcement 30 has: the upper surface portion 31 extending outward in the vehicle width direction from the upper end of the connection surface portion 33 toward the outer wall portion 13; and the lower surface portion 32 extending outward in the vehicle width direction from the lower end of the connection surface portion 33 toward the outer wall portion 13. The outer wall portion 13 and the outer reinforcement 30 can form the closed cross section, and thus the rigidity of the outer reinforcement 30 is improved. Accordingly, the collision load can be efficiently transmitted from the outer reinforcement 30 to the vertical surface portion 43, and the collision load during the side collision can be prevented from being transmitted to the battery B.

In the present embodiment, the battery B is supported by the inner lower wall portion 22, and the lower end of the connection surface portion 33 is located above the inner lower wall portion 22. In this way, the collision load is less likely to be transmitted directly from the connection surface portion 33 to the battery B. Accordingly, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

In the present embodiment, the inner reinforcement 40 has the horizontal surface portion 41a, the position of which overlaps the position of the area where the battery B is disposed in the vehicle front-rear direction, which extends in the vehicle front-rear direction and the vehicle width direction, and which is fixed to the inner wall portion 23, and the horizontal surface portion 41a is located between the inner lower wall portion 22 and the vertical surface portion 43 in the up-down direction. In this way, even in the case where the vertical surface portion 43 is rotationally displaced due to the collision load when the connection surface portion 33 abuts the inner reinforcement 40, it is possible to prevent the vertical surface portion 43 from being displaced downward by the horizontal surface portion 41a. Accordingly, it is possible to prevent the direct transmission of the collision load to the support portion of the battery B.

In the present embodiment, the vertical surface portion 43 is fixed to the horizontal surface portion 41a. In this way, even when the position of the side collision is the position other than the position of the vertical surface portion 43, the collision load is transmitted to the vertical surface portion 43 via the horizontal surface portion 41a. Accordingly, the collision load is efficiently transmitted from the outer reinforcement 30 to the cross member 60 via the horizontal surface portion 41a and the vertical surface portion 43. As a result, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

First Modified Example

FIG. 13 illustrates a first modified example of the lower body structure. In this modified example, a bead is not provided in a vertical surface portion 143, and instead, a portion of the vertical surface portion 143 is a thick portion 143a that is thicker than the other portions, thereby constituting the load transmission promoting portion.

The thick portion 143a is formed by affixing a patch material thereto. The patch material has an elongated rectangular shape. The patch material is a plate material having the same thickness as the vertical surface portion 143. The patch material is affixed onto a diagonal line of the vertical surface portion 143 so as to be inclined upward from the right side toward the left side.

A position of a right end portion of the thick portion 143a overlaps the position of the connection surface portion 33 of the outer reinforcement 30 in the up-down direction. A left end portion of the thick portion 143a is located above the floor panel 3, and a position thereof overlaps the position of the cross member 60 in the up-down direction.

The thick portion 143a has higher rigidity than the other portions of the vertical surface portion 143. As a result, the collision load, which is applied to the thick portion 143a via the connection surface portion 33 during the side collision, is easily transmitted.

In this first modified example, when the connection surface portion 33 abuts the inner reinforcement 40 during the side collision, the collision load is transmitted inward in the vehicle width direction and upward via the thick portion 143a. Thereafter, the collision load is transmitted from the inner reinforcement 40 to the cross member 60. As described above, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

Second Modified Example

FIG. 14 illustrates a second modified example of the lower body structure. In this modified example, a bead is not provided in a vertical surface portion 243, and instead, a portion of the vertical surface portion 243 is formed of another material, thereby constituting a load transmission promoting portion 243a.

The load transmission promoting portion 243a is formed of a metal plate having higher material strength than the other portions of the vertical surface portion 243. A position of a right end portion of the load transmission promoting portion 243a overlaps the position of the connection surface portion 33 of the outer reinforcement 30 in the up-down direction. A left end portion of the load transmission promoting portion 243a is located above the floor panel 3, and a position thereof overlaps the cross member 60 in the up-down direction.

The load transmission promoting portion 243a has higher rigidity than the other portions of the vertical surface portion 143. As a result, the collision load, which is applied to the load transmission promoting portion 243a via the connection surface portion 33 during the side collision, is easily transmitted.

In this second modified example, when the connection surface portion 33 abuts the inner reinforcement 40 during the side collision, the collision load is transmitted inward in the vehicle width direction and upward via the load transmission promoting portion 243a. Thereafter, the collision load is transmitted from the inner reinforcement 40 to the cross member 60. As described above, it is possible to prevent the transmission of the collision load during the side collision to the battery B.

Other Embodiments

The technique disclosed herein is not limited to the above-described embodiment, and can be substituted without departing from the spirit of the claims.

In the above embodiment, the center C2 of the vertical surface portion 43 in the up-down direction is located above the center of the connection surface portion 33 in the up-down direction. The present disclosure is not limited thereto, and the center C2 of the vertical surface portion 43 in the up-down direction may be located at the same position in the up-down direction as the center C1 of the connection surface portion 33 in the up-down direction.

In the above embodiment, the inner reinforcement 40 includes the first inner reinforcement 41 and the second inner reinforcement. The present disclosure is not limited thereto, and the inner reinforcement 40 may only include the second inner reinforcement.

In the above embodiment, the vertical surface portion 43 is fixed to the horizontal surface portion 41a. The present disclosure is not limited thereto, and the vertical surface portion 43 may not be fixed to the horizontal surface portion 41a.

In the above embodiment, the lower end of the connection surface portion 33 is located above the horizontal surface portion 41a. The present disclosure is not limited to this, and the lower end of the connection surface portion 33 may be located below the horizontal surface portion 41a as long as being located above the support portion 80. In particular, the position of the connection surface portion 33 may overlap the position of the horizontal surface portion 41a in the up-down direction.

In the above embodiment, the second inner reinforcement 42 has the lateral surface portion 44, but the lateral surface portion 44 is not an essential component and may be omitted. In the above embodiment, the corner portion between the lower surface portion 32 and the lower flange 35 has the deformation promoting portion 36, but the deformation promoting portion 36 is not an essential component and may be omitted.

The above-described embodiments are merely illustrative, and should not be construed as limiting the scope of the present disclosure. The scope of the present disclosure is defined by the claims, and all changes and modifications that fall within the scope of the claims are intended to be within the scope of the present disclosure.

VEHICLE LOWER BODY STRUCTURE

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Priority Claims (1)