JP7256445B2 - vehicle underbody structure - Google Patents

Description

The present invention relates to a lower body structure of a vehicle, and more particularly includes a battery unit disposed between a pair of floor frames and first and second cross members connecting a pair of side sills in the vehicle width direction. The present invention relates to a lower body structure of a vehicle.

Conventionally, in electric vehicles such as hybrid vehicles and electric vehicles, the battery, which is the power source of the electric motor (for example, motor generator or motor) that drives the wheels, has a large capacity, so the space below the vehicle body floor is used for the battery unit. are arranged as follows.
Generally, a battery unit is composed of a plurality of battery modules each made up of an assembly of battery cells such as lithium-ion cells, an upper cover and a lower cover for housing the plurality of battery modules, and supporting members for supporting them on the vehicle body. there is

The automobile floor structure of Patent Document 1 includes a pair of left and right side sills extending in the longitudinal direction of the vehicle body, a floor panel spanning between the pair of side sills, and a floor panel between the pair of side sills and below the floor panel. an upper cross member that includes a pair of left and right floor frames extending in the longitudinal direction of the vehicle body and a battery unit disposed between the pair of floor frames, and that connects the pair of side sills above the floor panel; and a lower cross member that connects the pair of floor frames below the upper cross member on the lower side of the floor panel and sandwiches the battery unit in cooperation with the upper cross member.
In order to suppress the deformation of the floor frame in the event of a side collision, the thickness of the portion of the upper cross member that extends between the side sill and the floor frame is the thickness of the portion that extends more inwardly than the floor frame in the vehicle width direction. It is formed thinner than the plate thickness.

Although the automobile body structure of Patent Document 2 is not a technique aimed at improving the energy absorption (EA) performance of the cross member at the time of a side collision, the front end portion of the side sill inner is provided from the upper wall portion to the inner wall portion. A front reinforcement is formed extending therethrough. This prevents the front wheels from entering the vehicle compartment during a small overlap collision.

WO2012/063393 JP 2016-153269 A

When an impact load is applied to the side sills during a side collision, the side sills are crushed and deformed inward in the vehicle width direction, and part of the input load that is not absorbed by the crushing deformation travels through multiple frame members such as cross members as load paths. distributed as
In the technique disclosed in Patent Document 1, the input load is absorbed not only by the crushing deformation of the side sill but also by the crushing deformation of the cross member extending between the side sill and the floor frame.
However, there is a possibility that the technique of Patent Document 1 cannot ensure the expected EA performance.

When an impact load is applied locally to a part of the side sill away from the cross member where the low-rigidity part is formed, the load input to the low-rigidity part is reduced, so the low-rigidity part has sufficient impact absorption function. can not be fulfilled, and the amount of displacement of the floor frame becomes large.
In other words, even if the cross member has a low-rigidity part or bead, etc., sufficient EA performance can be ensured if the load path from the impact load input position to the cross member (low-rigidity part, bead, etc.) cannot be formed. Can not do it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle lower body structure or the like that can ensure impact absorption performance regardless of the impact load input position at the time of a side collision.

A vehicle lower body structure according to claim 1 includes a pair of left and right side sills extending in the longitudinal direction of the vehicle body, a floor panel spanning between the pair of side sills, and a battery unit disposed below the floor panel. a first cross member for connecting the pair of side sills in the vehicle width direction above the battery unit via the floor panel; and the first cross member above the battery unit via the floor panel. In a vehicle lower body structure including a second cross member that connects the pair of side sills in the vehicle width direction on the rear side of the member, the second cross member is formed inside the pair of side sills along the shape of the side sills, and Reinforcing members extending substantially horizontally in the front-rear direction are respectively provided, the reinforcing members extending from at least the first cross member to the second cross member , and the side sills forming vehicle width direction outer portions. The side sill inner includes a side sill outer and a side sill inner forming a vehicle width direction inner portion, and the side sill inner includes an upper wall portion, a lower wall portion facing the upper wall portion, and a portion of the vehicle between the upper wall portion and the lower wall portion. and an inner wall connecting the widthwise inner ends, the reinforcing member is provided from the vehicle widthwise outer end of the upper wall to the inner wall, and the reinforcing member extends from the upper wall. The first cross member has an upper reinforcing portion joined so as to overlap the inner wall portion and an inner reinforcing portion joined so as to overlap the inner wall portion, and the first cross member includes a first intermediate portion extending in the vehicle width direction and a and a pair of left and right first side portions formed to have lower rigidity than the first intermediate portion and extending outward in the vehicle width direction from left and right end portions of the first intermediate portion, respectively; The member includes a second intermediate portion extending in the vehicle width direction, and a pair of left and right members extending outward in the vehicle width direction from both left and right end portions of the second intermediate portion while being formed with lower rigidity than the second intermediate portion. The upper surface portions of the first and second intermediate portions are formed so as to overlap with the reinforcing member in the height direction and extend in the vehicle width direction.

According to this vehicle lower body structure, since reinforcing members extending substantially horizontally are provided in the pair of side sills, the rigidity in the vehicle width direction of the side sills can be increased with a minimum number of reinforcing members. Since the reinforcing member extends from at least the first cross member to the second cross member, the load path leading to the first and second cross members is formed by the reinforcing member regardless of the impact load input position. The frame structure of the vehicle body can be used to distribute the load during a side collision.
In addition, it is possible to prevent the buckling deformation of the side sill and prevent the side sill from collapsing in cross section while dispersing the load in the event of a side collision.

The invention of claim 2 is the invention of claim 1, further comprising a pair of left and right floor frames extending in the longitudinal direction of the vehicle body between the pair of side sills and below the floor panel,
The first cross member is configured such that the rigidity of the first side portion located outside the floor frame in the vehicle width direction is lower than the rigidity of the first intermediate portion located inside the floor frame in the vehicle width direction. In addition, the rigidity of the second cross member located outside the floor frame in the vehicle width direction is lower than that of the second intermediate portion located inside the floor frame in the vehicle width direction. It is characterized by being configured to be According to this configuration, the outer portions of the first and second cross members on the outer side in the vehicle width direction of the floor frame can be crushed and deformed inward in the vehicle width direction, and the impact absorption performance at the time of a side collision can be improved. can.

The invention of claim 3 is characterized in that in the invention of claim 1 or 2 , the reinforcing member is provided from the front end to the rear end of the side sill inner.
With this configuration, even if the impact load input position is far from the first and second cross members, a load path reaching the first and second cross members can be formed.

The invention of claim 4 is the invention of any one of claims 1 to 3, wherein the upper wall portion and the flange portion of the side sill inner are connected across the side of the second cross member so as to prevent a side collision. It has a stopper bracket that suppresses the intrusion of the side door into the vehicle interior,
The pair of floor frames are arranged so as to shift outward in the vehicle width direction toward the rear in the vehicle longitudinal direction, and the inner end positions of the first side portions are set at the same positions as the floor frames, and the second The inner end position of the side portion is set to the inner side of the floor frame in the vehicle width direction.
According to this configuration, the stopper bracket suppresses the amount of side door intrusion in the event of a side collision, while the lowering of the impact absorption amount of the side sill due to the installation of the stopper bracket can be compensated for by the crushing of the low-rigidity portion and the floor frame.
The invention of claim 5 is the invention of any one of claims 1 to 4 , wherein the upper surface of the second intermediate portion is positioned lower than the upper surface of the first intermediate portion and lower than the lower end of the inner reinforcing portion. It is characterized in that the second intermediate portion extends in the vehicle width direction at a high position and is formed of a member having a thicker plate thickness than the first intermediate portion.

According to the vehicle lower body structure of the present invention, in the event of a side collision, the reinforcing member of the side sill can be used to ensure impact absorption performance regardless of the impact load input position.

1 is an upper perspective view of a lower vehicle body of a vehicle according to Embodiment 1. FIG. It is a top view. It is a rear view. It is a partially exploded perspective view. 3 is a cross-sectional view taken along the line V-V of FIG. 2; FIG. FIG. 3 is a sectional view taken along the line VI-VI of FIG. 2; FIG. 3 is a cross-sectional view taken along line VII-VII of FIG. 2; 3 is a cross-sectional view taken along line VIII-VIII of FIG. 2; FIG. FIG. 2 is an enlarged view of a main portion of FIG. 1; FIG. 6 is a diagram in which a seat bracket is omitted from FIG. 5; FIG. 8 is a cross-sectional view taken along line XI-XI of FIG. 7; 9 is a cross-sectional view taken along line XII-XII of FIG. 8; FIG. 8 is a cross-sectional view taken along the line XIII-XIII of FIG. 7; FIG.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or uses.

Embodiment 1 of the present invention will be described below with reference to FIGS. 1 to 13. FIG.
A vehicle V according to the first embodiment is a hybrid vehicle that uses an internal combustion engine (not shown) such as a gasoline engine or a diesel engine and an electric motor (motor generator) (not shown) for driving the vehicle as drive sources.

As shown in FIGS. 1 to 4, a vehicle V includes a pair of left and right side sills 1, a floor panel 2, a pair of left and right floor frames 3, a battery unit 4, first and second cross members 5, It has 6th class. Further, the vehicle V is provided with seat brackets 7 for supporting the front seats at both left and right end portions of the first cross member 5, respectively.
Hereinafter, in the drawings, the direction of arrow F is defined as the front in the longitudinal direction of the vehicle body, the direction of arrow L is defined as the left in the vehicle width direction, and the direction of arrow U is defined as the upper direction in the vertical direction of the vehicle. Further, since the vehicle V has a bilaterally symmetrical structure, the right side member and the right side portion will be mainly described below unless otherwise specified.

First, a pair of side sills 1 will be described.
The right side sill 1 has an outer panel 11 forming a right side wall portion and an inner panel 12 forming a left side wall portion. are doing. A vertically extending hinge pillar 8 is connected to the front end portion of the side sill 1 , and a vertically extending rear pillar 9 is connected to the rear end portion of the side sill 1 .
The vehicle V has a so-called double door structure in which the front door opens and closes around a hinge formed at the front end, and the rear door opens and closes around a hinge formed at the rear end. omitted.

As shown in FIGS. 5 to 8, the outer panel 11 includes an outer wall portion 11a orthogonal to the vehicle width direction, an upper wall portion 11b extending leftward from the upper end of the outer wall portion 11a, and an outer wall portion 11a. A lower wall portion 11c extending leftward from the lower end portion, an upper flange portion 11d extending upward from the left end portion of the upper wall portion 11b, and a lower flange portion 11e extending downward from the left end portion of the lower wall portion 11c. It is configured in a substantially hat shape.

The outer panel 11 is provided with a skin member 13 arranged on the right side of the outer panel 11 and an outer rain 14 arranged on the left side of the outer panel 11 .
As shown in FIGS. 5 to 8 and 13, the outer plate member 13 is configured to cover the upper flange portion 11d, the upper wall portion 11b, and the upper portion of the outer wall portion 11a from the right side (outside). ing.
Thus, the outer plate member 13 cooperates with the outer panel 11 to form a closed cross section extending from the front end to the rear end of the outer panel 11 .
The outer rain 14 is disposed on the right side of the second cross member 6 in a plan view, and has a substantially U-shaped cross section. The outer rain 14 has upper and lower ends connected to the upper flange portion 11d and lower flange portion 11e, respectively, and a front end portion and a rear end portion of the middle stage portion connected to the outer wall portion 11a.
As a result, the support rigidity of the rear end portion of the front door and the front end portion of the rear door is increased, thereby securing the vertical rigidity of the intermediate portion of the vehicle body in cooperation with the front door and the rear door.

As shown in FIGS. 5 to 8, the inner panel 12 includes an inner wall portion 12a orthogonal to the vehicle width direction, an upper wall portion 12b extending rightward from the upper end of the inner wall portion 12a, and an inner wall portion 12a. A lower wall portion 12c extending rightward from the lower end of the upper wall portion 12c, an upper flange portion 12d extending upward from the right end portion of the upper wall portion 12b, and a lower flange portion 12e extending downward from the right end portion of the lower wall portion 12c, It has a substantially hat-shaped cross section. The upper flange portion 12d and the lower flange portion 12e are joined to the upper flange portion 11d and the lower flange portion 11e by spot welding, respectively.

The inner panel 12 is provided with a first inner rain 15 (reinforcing member) arranged on the right side of the inner panel 12 and a plurality of second inner rains 16 .
The first inner rain 15 is made of, for example, an ultra-high-tensile steel plate with a thickness of 2.0 mm, and has a substantially L-shaped cross section.
As shown in FIGS. 4 to 8, the first inner rain 15 is formed from the left end (vehicle width direction inner end) to the right end (vehicle width direction outer end) of the inner panel 12 in the left-right direction. It is formed from the front end to the rear end of the inner panel 12 .
The first inner rain 15 includes an upper reinforcing portion 15a extending substantially horizontally and an inner reinforcing portion 15b extending substantially vertically.
The upper reinforcing portion 15a overlaps substantially the entire upper wall portion 12b in close contact, and the inner reinforcing portion 15b overlaps and partially overlaps the upper portion of the inner wall portion 12a in close contact.

As shown in FIGS. 4, 7, 8, and 13, a plurality (for example, four) of second inner rains 16 are formed so as to be perpendicular to the front-rear direction.
Each of the second inner rains 16 is joined to the inner wall portion 12a, the upper wall portion 12b, and the lower wall portion 12c, and constitutes a node on the vehicle width direction inner side that partially blocks the closed cross section of the side sill 1. As shown in FIG.
The second inner rain 16 on the frontmost side in a plan view is arranged so as to overlap the hinge pillar 8 in the left-right direction, and the second inner rain 16 on the rear side is arranged slightly forward of the first cross member 5. . The two rear second inner rains 16 are arranged to sandwich the second cross member 6 in the front and rear, and the front second inner rain 16 of the two rear second inner rains 16 overlaps the outer rain 14 in the left-right direction. are arranged to

Next, the floor panel 2 and the pair of floor frames 3 will be described.
The floor panel 2 is formed to span between a pair of side sills 1. - 特許庁
The left and right end portions of the floor panel 2 are joined to the inner side wall portions 12a of the pair of side sills 1, respectively, to constitute the floor surface of the vehicle V compartment. A rear floor panel forming a rear upwardly inclined kick-up portion is connected to the rear end portion of the floor panel 2 .

As shown in FIGS. 3 to 8, the pair of floor frames 3 are formed to have a substantially hat-shaped cross section, and the distance between the pair of floor frames 3 increases toward the rear. Therefore, the distance between the side sill 1 and the adjacent floor frame 3 becomes closer toward the rear.
The floor frame 3 cooperates with the lower surface of the floor panel 2 to form a closed cross-section with a rectangular cross-section that extends forward and backward.

Next, the battery unit 4 will be explained.
As shown in FIGS. 3 and 4, the battery unit 4 is laid out in the space below the floor panel 2 while accommodating a high-voltage battery in which a plurality of battery modules are connected in series. Therefore, the battery unit 4 is configured to ensure vibration resistance and water resistance.
A battery module that supplies electric power to a vehicle-driving motor is a rectangular parallelepiped battery assembly in which a plurality of rectangular parallelepiped battery cells having a standard voltage are arranged in a stack.
A battery cell is, for example, a lithium ion battery, which is a type of secondary battery.
This battery unit 4 has a frame-shaped frame 21, a bottom plate 22, an upper cover 23, and a plurality of support members 24 as main components.

The frame-shaped frame 21 forms a substantially square-shaped closed cross-section structure with a crank-shaped upper frame and a crank-shaped lower frame (see FIGS. 5 and 6).
The bottom plate 22 is made of a metal having excellent thermal conductivity, such as an aluminum alloy. Edge portions of the bottom plate 22 are supported by the upper wall portion and the flange portion of the frame-like frame 21 .
Frame-shaped frame 21 and bottom plate 22 correspond to a lower cover of battery unit 4 .
The upper cover 23 is tightly fixed to the inner edge of the upper wall portion of the frame 21 via a sealing gasket (not shown).
Four support members 24 protrude outward in the vehicle width direction from the left and right portions of the frame 21 . These support members 24 are fastened and fixed to the lower wall portions of the pair of floor frames 3 via fastening members. As described above, the battery unit 4 is arranged below the floor panel 2 and between the pair of floor frames 3 .

Next, the first cross member 5 will be explained.
As shown in FIGS. 1, 2, 5, 7, 9 to 11, and 13, the first cross member 5 connects between the front portions of the pair of side sills 1 and the floor panel 2. A first closed cross section C1 having a rectangular cross section extending left and right is formed in cooperation with the upper surface of the .
The first cross member 5 includes a first intermediate portion 31 and a pair of left and right first side portions 32 extending outward in the vehicle width direction from both left and right end portions of the first intermediate portion 31 .
The first intermediate portion 31 is made of, for example, an ultra-high-tensile steel plate with a thickness of 1.8 mm, and has a substantially hat-shaped cross section. A flange portion formed at the lower end portion of the first intermediate portion 31 is welded to the upper surface of the floor panel 2 .

The pair of first side portions 32 is made of, for example, a cold-rolled steel plate having a thickness of 1.0 mm, which has lower toughness and rigidity than the first intermediate portion 31, and each has a substantially hat-shaped cross section.
The right first side portion 32 includes a front wall portion 32a orthogonal to the front-rear direction, a rear wall portion 32b facing the front wall portion 32a with a predetermined distance therebetween, and upper ends of the front wall portion 32a and the rear wall portion 32b. An upper wall portion 32c and the like are provided to connect them.
The flange portions formed at the lower ends of the front wall portion 32a and the rear wall portion 32b are welded to the upper surface of the floor panel 2, and the flange portion formed at the right (vehicle width direction outer) end is attached to the inner side. It is joined to the wall portion 12a by welding.

As shown in FIGS. 5, 10, and 11, the upper wall portion 32c is welded to the lower surface of the right end of the upper wall portion of the first intermediate portion 31 at the upper surface of the left (vehicle width direction inner) end. The lower surface of the right (vehicle width direction outer) end portion is joined to the upper surface of the upper wall portion 12b of the inner panel 12 by welding.
The upper wall portion 32c includes bead portions 32s and 32t that are recessed downward and extend forward and backward, and an opening portion 32u that communicates vertically.
The bead portion 32s is formed on the right side (outside in the vehicle width direction) of the floor frame 3, and the bead portion 32t is formed on the right side of the bead portion 32s. The opening 32u is formed in a substantially elliptical shape and is formed so as to overlap with the bead 32t.

Next, the second cross member 6 will be explained.
As shown in FIGS. 1, 2, 6, 8 to 10, 12, and 13, the second cross member 6 is positioned at the rear of the first cross member 5 and between the pair of side sills 1. While being connected, they cooperate with the upper surface of the floor panel 2 to form a second closed cross section C2 having a rectangular cross section extending left and right.
The cross-sectional area of the second closed cross-section C2 is set to be smaller than that of the first closed cross-section C1. It is set to be smaller than the next moment.

The second cross member 6 includes a second intermediate portion 41 and a pair of left and right second side portions 42 extending outward in the vehicle width direction from both left and right end portions of the second intermediate portion 41 .
The second intermediate portion 41 is made of, for example, an ultra-high-tensile steel plate with a thickness of 2.3 mm, and has a substantially hat-shaped cross section. A flange portion formed at the lower end portion of the second intermediate portion 41 is welded to the upper surface of the floor panel 2 .

The pair of second side portions 42 is made of, for example, a cold-rolled steel plate having a thickness of 2.3 mm, which has lower toughness and rigidity than the second intermediate portion 41, and each has a substantially hat-shaped cross section.
The right second side portion 42 includes a front wall portion 42a orthogonal to the front-rear direction, a rear wall portion 42b facing the front wall portion 42a with a predetermined distance therebetween, and upper ends of the front wall portion 42a and the rear wall portion 42b. An upper wall portion 42c and the like are provided to connect them. Further, the second side portion 42 is formed with a stepped portion 42q in which the height position of the right side portion is higher than the height position of the left side portion. The step portion 42q is a portion extending between the inner panel 12 and the floor frame 3. As shown in FIG.
In this embodiment, the separation distance from the inner wall portion 12a of the inner panel 12 to the stepped portion 42q and the separation distance from the inner wall portion 12a of the inner panel 12 to the bead portion 32s are set to be substantially equal.

The front wall portion 42a and the rear wall portion 42b are each formed with a linear ridgeline portion 42r projecting in the opposite direction to the second closed cross-section C2.
As shown in FIGS. 8 to 10, 12, and 13, the upper ends of these ridges 42r are set at positions corresponding to the steps 42q, and are formed so as to shift rightward toward the bottom.
The flanges formed at the lower ends of the front wall 42a and the rear wall 42b are welded to the upper surface of the floor panel 2, and the flange formed at the right end is welded to the inner wall 12a. are joined together.

As shown in FIGS. 6 and 8 to 10, the upper wall portion 42c has the upper surface of the left end portion welded to the lower surface of the right end portion of the upper wall portion of the second intermediate portion 41. is joined to the upper surface of the upper wall portion 12b of the inner panel 12 by welding.
The upper wall portion 42c includes a bead portion 42s that is recessed downward and extends in the front-rear direction.
The bead portion 42s is formed on the left side of the stepped portion 42q and at a position corresponding to between the left and right vertical wall portions of the floor frame 3. As shown in FIG.

As shown in FIGS. 9 and 10, a stopper bracket 51 is provided on the side of the second cross member 6 and connects the upper wall portion 12b and the upper flange portion 12d of the inner panel 12 across the upper wall portion 12b and the upper flange portion 12d. A pair of floor frames 3 are arranged so as to shift to the right as they go rearward, the inner end position of the first side portion 32 of the first cross member 5 is set at the same position as the floor frame 3, and the second cross member 5 is positioned at the same position as the floor frame 3. Since the inner end position of the second side portion 42 of the member 6 is set on the left side of the floor frame 3, the stopper bracket 51 suppresses the amount of intrusion of the side door (not shown) in the event of a side collision. The crushing of the first and second side portions 32 and 42 and the floor frame 3 compensates for the decrease in the impact absorption capacity of the side sill 1 due to the installation of the bracket 51 .

Next, a pair of seat brackets 7 will be described.
A pair of seat brackets 7 are composed of a seat bracket 7 that supports the vehicle width direction outer front portion of the driver seat on which the driver seat occupant sits, and a seat that supports the vehicle width direction outer front portion of the passenger seat on which the front passenger seat occupant sits. Bracket 7 is targeted. The seat brackets for supporting the inner front portions of the driver's seat and the front passenger's seat in the vehicle width direction are arranged in the left and right intermediate portions of the first cross member 5, respectively.

As shown in FIGS. 1 , 2 , 5 , 7 , 9 and 11 , the right seat bracket 7 is provided to cover the upper half of the right first side portion 32 .
The seat bracket 7 is made of, for example, a cold-rolled steel plate with a thickness of 2.3 mm, and has a substantially U-shaped cross section. The seat bracket 7 connects a front wall portion 7a orthogonal to the front-rear direction, a rear wall portion 7b facing the front wall portion 7a with a predetermined distance, and upper ends of the front wall portion 7a and the rear wall portion 7b. The upper wall portion 7c and the like are provided.

Further, the seat bracket 7 is formed with a bulging portion 7e that is spaced upward from the upper wall portion 32c of the first cross member 5 (first side portion 32). The bulging portion 7e is a portion extending between the inner panel 12 and the floor frame 3, and is formed in a trapezoidal shape when viewed from the front.
Here, of the first cross member 5, the upper wall portion of the first intermediate portion 31 and the upper wall portion 32c of the pair of first side portions 32 correspond to the upper surface portion. A portion of the bulge 32c covered with the bulging portion 7e corresponds to the first cross member portion.

The front wall portion 7a and the rear wall portion 7b are formed with bead portions 7s that protrude in opposite directions to the bulging portion 7e and extend vertically.
As shown in FIGS. 7, 9, and 11, these bead portions 7s are arranged on the right side of the bead portion 32t, and are formed such that the lateral dimension increases downward from the upper end portion of the front wall portion 7a. there is
The flange portions formed at the lower ends of the front wall portion 7a and the rear wall portion 7b move the bead portion 7s left and right with respect to the front wall portion 32a and the rear wall portion 32b of the first cross member 5 (first side portion 32). are welded at positions where they are sandwiched between the two.

As shown in FIGS. 5, 7, and 9, the upper wall portion 7c has a left end extending to the inner panel 12 (inner wall portion 12a), and a lower surface of the right end extending above the first intermediate portion 31. It is welded to the upper surface of the right end of the wall. The right end portion of the upper wall portion of the first intermediate portion 31 is sandwiched between the upper wall portion 32c and the upper wall portion 7c of the first side portion 32 and joined by triple welding.

Next, the mechanism of impact absorption at the time of side collision of the vehicle V will be described.
At the initial stage of a side collision, an impact load is applied locally to the side sill 1 in the longitudinal direction.
Since the rains 14 to 16 are installed inside the side sill 1, the side sill 1 is prevented from collapsing in cross section. In particular, since the first inner rain 15 is formed over the entire length of the side sill 1, even if an input load is input to a specific portion of the outer panel 11, the input load is dispersed over the entire first inner rain 15, , second cross members 5 and 6, etc. are used as load paths.

Deformation of the side sill 1 and the first and second cross members 5 and 6 occurs in the middle stage of the side collision.
In the side sill 1, the input load causes the side sill 1 to be crushed and deformed inward in the vehicle width direction, and rotates upward around the joint with the floor panel 2 as the center of rotation.
Substantially simultaneously, in the first cross member 5, the input load causes bending deformation of the front wall portion 7a and the rear wall portion 7b starting from the bead portion 7s of the seat bracket 7, and then the bead portion 32s of the upper wall portion 32c. , 32t and the opening 32u, the crushing deformation of the first side portion 32 is performed.
Since the first side portion 32 is formed to have lower toughness than the first intermediate portion 31, sufficient crushing deformation is performed even when the seat bracket 7 is attached.

In the second cross member 6, the input load causes bending deformation of the front wall portion 42a and the rear wall portion 42b starting from the ridgeline portion 42r and crushing deformation of the second side portion 42 starting from the bead portion 42s.
The second cross member 6 has a smaller (shorter) portion extending between the side sill 1 and the floor frame 3 than the first cross member 5, but the area of the first closed cross section C1 of the first cross member 5 is larger than the area of the first closed cross section C1. Also, by reducing the area of the second closed cross-section C2, the crushing deformation tendencies of the first and second cross members 5 and 6 with respect to the floor frame 3 are made uniform.

After the side collision, the floor frame 3 deforms inward in the vehicle width direction due to the impact load remaining inward in the vehicle width direction without being absorbed by the crushing deformation of the first side portion 32 and the like.
Of the loads initially input, some of the loads are absorbed by the crushing deformation of the first and second side portions 32 and 42 and the bending deformation of the seat bracket 7. The deformation of the floor frame 3 is suppressed because it is distributed to other frame members (eg, the opposite side sill 1, the hinge pillar 8, the rear pillar 9, etc.) via the two cross members 5 and 6.
As a result, damage to the battery unit 4 can be minimized.

Next, the operation and effects of the lower vehicle body structure will be described.
According to the lower vehicle body structure according to the first embodiment, since the first inner rains 15 extending substantially horizontally are provided in the pair of side sills 1, respectively, the rigidity of the side sills 1 in the vehicle width direction is increased with a minimum number of reinforcing members. can do. Since the first inner rain 15 extends from at least the first cross member 5 to the second cross member 6, the load reaching the first and second cross members 5 and 6 is controlled regardless of the impact load input position. A path can be formed through the first inner rain 15, and the load at the time of a side collision can be distributed using the frame structure of the vehicle body.

It has a pair of floor frames 3 extending longitudinally between the pair of side sills 1 and below the floor panel 2, and the first and second cross members 5 and 6 are arranged outside the floor frames 3 in the vehicle width direction. The rigidity of the corresponding outer portion is configured to be lower than the rigidity of the inner portion corresponding to the inner side of the floor frame 3 in the vehicle width direction. As a result, the outer portions of the first and second cross members 5 and 6, which are outside the floor frame 3 in the vehicle width direction, can be crushed and deformed inward in the vehicle width direction, thereby improving the impact absorption performance in the event of a side collision. can be done.

A side sill 1 includes a side sill outer 11 forming a vehicle width direction outer portion and a side sill inner 12 forming a vehicle width direction inner portion. Since it is provided over the edge, it is possible to prevent buckling deformation of the side sill 1 and distribute the load at the time of a side collision.

The side sill inner 12 has an upper wall portion 12b, a lower wall portion 12c facing the upper wall portion 12b, and an inner wall portion 12a connecting inner ends of the upper wall portion 12b and the lower wall portion 12c in the vehicle width direction, Since the first inner rain 15 is provided from the upper wall portion 12b to the inner wall portion 12a, it is possible to prevent the side sill 1 from collapsing and distribute the load in the event of a side collision.

Since the first inner rain 15 is provided from the front end to the rear end of the side sill inner 12, even if the impact load input position is far from the first and second cross members 5, 6, the first and second cross members It is possible to form a load path up to 5, 6

A stopper bracket 51 is provided on the side of the second cross member 5 and connected across the upper wall portion 12b and the upper flange portion 12d of the side sill inner 12 to prevent the side door from intruding into the vehicle interior in the event of a side collision. , a pair of floor frames 3 are arranged so as to move outward in the vehicle width direction toward the rear, and the inner end position of the first side portion 32 of the first cross member 5 is set at the same position as the floor frames 3. In addition, the inner end position of the second side portion 42 of the second cross member 6 is set inside the floor frame 3 in the vehicle width direction. As a result, the amount of intrusion of the side door in the event of a side collision is suppressed by the stopper bracket 51, while the decrease in the impact absorption amount of the side sill 1 due to the installation of the stopper bracket 51 is prevented by the first and second side portions 32 and 42 and the floor frame 3. It can be supplemented by crushing.

Next, a modified example in which the above embodiment is partially changed will be described.
1) In the above embodiment, an example of a hybrid vehicle provided with an internal combustion engine such as an engine and an electric motor has been described, but it is sufficient that at least a battery unit is provided, and the electric vehicle may be provided with only an electric motor. .
Further, the double door structure without the center pillar is not essential, and can be applied to a two-door type vehicle without the rear door.

2) In the above embodiment, an example of the substantially L-shaped first inner rain joined to the upper wall portion and the inner wall portion of the inner panel has been described. A substantially U-shaped first inner rain may be joined to the upper wall, the lower wall and the inner wall.

3) In the above embodiment, an example in which four second inner rains are provided has been described, but the number may be three or less, or may be five or more.

4) In addition, without departing from the spirit of the present invention, a person skilled in the art can implement the above-described embodiment in a form in which various modifications are added or in a form in which each embodiment is combined. Any modifications are also included.

1 side sill 2 floor panel 3 floor frame 4 battery unit 5 first cross member 6 second cross member 11 outer panel 12 inner panel 12a inner wall portion 12b upper wall portion 12c lower wall portion 15 first inner rain 15a upper reinforcement portion 15b lower reinforcement Part 51 Stopper bracket V Vehicle

Claims (5)

A pair of left and right side sills extending in the longitudinal direction of the vehicle body, a floor panel spanning between the pair of side sills, a battery unit disposed below the floor panel, and the battery unit via the floor panel. a first cross member for connecting the pair of side sills in the vehicle width direction above the pair of side sills; In a vehicle lower body structure including a second cross member that connects in the vehicle width direction,
reinforcing members formed along the shape of the side sills in the pair of side sills and extending substantially horizontally in the front-rear direction of the vehicle body ;
the reinforcing member extends from at least the first cross member to the second cross member ;
The side sill is composed of a side sill outer forming a vehicle width direction outer portion and a side sill inner forming a vehicle width direction inner portion,
The side sill inner has an upper wall portion, a lower wall portion facing the upper wall portion, and an inner wall portion connecting inner ends of the upper wall portion and the lower wall portion in the vehicle width direction,
The reinforcing member is provided from the outer end of the upper wall in the vehicle width direction to the inner wall,
The reinforcing member has an upper reinforcing portion that is joined so as to overlap with the upper wall portion and an inner reinforcing portion that is joined so as to overlap with the inner wall portion,
The first cross member is formed with a first intermediate portion extending in the vehicle width direction and having lower rigidity than the first intermediate portion, and extends outward in the vehicle width direction from both left and right end portions of the first intermediate portion. a pair of left and right first side portions;
The second cross member is formed with a second intermediate portion extending in the vehicle width direction and having lower rigidity than the second intermediate portion, and extends outward in the vehicle width direction from both left and right end portions of the second intermediate portion. a pair of left and right second side portions;
The upper surface portions of the first and second intermediate portions are formed so as to overlap with the reinforcing member in the height direction and extend in the vehicle width direction.
A lower body structure of a vehicle, characterized by: a pair of left and right floor frames extending in the longitudinal direction of the vehicle body between the pair of side sills and below the floor panel;
The first cross member is configured such that the rigidity of the first side portion located outside the floor frame in the vehicle width direction is lower than the rigidity of the first intermediate portion located inside the floor frame in the vehicle width direction. In addition, the rigidity of the second cross member located outside the floor frame in the vehicle width direction is lower than that of the second intermediate portion located inside the floor frame in the vehicle width direction. 2. The lower vehicle body structure for a vehicle according to claim 1, wherein the lower body structure of the vehicle is configured to: 3. The vehicle lower body structure according to claim 1, wherein the reinforcing member is provided from the front end to the rear end of the side sill inner. a stopper bracket that is connected across the upper wall portion and the flange portion of the side sill inner on the side of the second cross member to prevent the side door from intruding into the vehicle interior in the event of a side collision;
the pair of floor frames are arranged so as to shift outward in the vehicle width direction as they go rearward in the vehicle longitudinal direction;
The inner end position of the first side portion is set at the same position as the floor frame, and the inner end position of the second side portion is set inside the floor frame in the vehicle width direction. 4. A vehicle lower body structure according to any one of items 1 to 3. The upper surface portion of the second intermediate portion extends in the vehicle width direction at a position lower than the upper surface portion of the first intermediate portion and higher than the lower end of the inner reinforcing portion, and the second intermediate portion is higher than the first intermediate portion. 5. The lower vehicle body structure for a vehicle according to claim 1, wherein the lower body structure of a vehicle is formed of a member having a large plate thickness .

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