JP7366342B2 - Lower body structure of electric vehicle - Google Patents

Description

The present invention relates to a lower body structure of an electric vehicle in which a battery unit is disposed between a pair of floor frames.

Conventionally, in electric vehicles such as hybrid cars and electric cars, the battery that is the power source for the electric motor (e.g. motor generator or motor) that drives the wheels has a large capacity, so the space below the car body floor is used to store the battery unit. It is arranged as follows.
Typically, a battery unit includes a plurality of battery modules made up of a collection of battery cells such as lithium ion, a battery frame that forms the skeleton of the battery unit, an upper cover and a lower cover that accommodate the plurality of battery modules, and a vehicle body. It is composed of a support member, etc. that supports the

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 section between the pair of side sills and the lower side of the floor panel. An upper cross member 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 connects a pair of side sills above the floor panel. and a lower cross member that connects the pair of floor frames at a position below the upper cross member on the lower side of the floor panel and works with the upper cross member to sandwich the battery unit, and a lower cross member that is disposed between the side sill and the floor frame. A first outrigger having a substantially U-shaped cross section is provided.

This first outrigger is formed to match the height of the inner wall of the side sill and the height of the outer wall of the floor frame, and is joined to the inner wall of the side sill and the outer wall of the floor frame. It functions as an energy absorbing member that can be crushed by the impact energy input into it.

WO2012/063393 publication

The automobile floor structure disclosed in Patent Document 1 actively plastically deforms a first outrigger disposed between a side sill and a floor frame in the event of a side collision. The safety of the battery unit is ensured.
However, in the technology of Patent Document 1, if impact energy exceeding the energy absorption (EA) performance of the first outrigger is input to the side sill, the impact energy exceeding the allowable amount of the first outrigger will cause the floor frame to move toward the inside of the vehicle width. There are concerns about movement in this direction.

If the impact energy that cannot be absorbed due to the deformation of the first outrigger moves the floor frame toward the inside of the vehicle width, this may cause interference between the battery unit (battery module) and the floor frame or other vehicle body parts, causing damage to the battery unit. There is a possibility that
That is, when the impact energy at the time of a side collision is large, it is not easy to ensure the safety of the battery unit.

An object of the present invention is to provide a lower body structure of an electric vehicle that can ensure the safety of a battery unit regardless of the degree of impact energy.

The lower body structure of an electric vehicle according to a first aspect of the present invention includes: a pair of left and right side sills extending in the longitudinal direction of the vehicle; a floor panel spanning between the pair of side sills; The electric vehicle is equipped with a pair of left and right floor frames extending in the longitudinal direction of the vehicle body on the lower side thereof, and a battery unit including a battery frame that supports a battery module, and the battery unit is disposed between the pair of floor frames. In the lower body structure of the vehicle, the battery frame includes at least a pair of front and rear first frame members extending in the vehicle width direction, and a pair of left and right frame members connecting the pair of first frame members and extending in the vehicle front and rear direction. a gusset member having a second frame member and connecting an inner end in the vehicle width direction of the side sill and an outer end in the vehicle width direction of the second frame member; a third frame member that extends in the vehicle width direction between the first frame members and connects the pair of second frame members; the gusset member corresponds to an outer end of the third frame member in the vehicle width direction; The gusset member is fastened to the side sill at a plurality of fastening portions arranged in the longitudinal direction of the vehicle body, and has a convex bead portion protruding outward between the adjacent fastening portions. It is characterized by having the following.

In this lower body structure of an electric vehicle, the battery frame of the battery unit disposed between the pair of floor frames includes at least a pair of front and rear first frame members extending in the vehicle width direction and a pair of first frame members extending in the vehicle width direction. Since it has a pair of left and right second frame members that connect one frame member and extend in the longitudinal direction of the vehicle body, the battery unit can be firmly disposed between the pair of floor frames. Since a gusset member is provided that connects the inner end of the side sill in the vehicle width direction and the outer end of the second frame member in the vehicle width direction, if impact energy that is less than the EA performance of the gusset member is input, it will not affect the battery unit. Impact energy can be absorbed through plastic deformation between the side sill and floor frame without causing any damage. Additionally, since the side sill and battery frame are directly connected via the gusset member, if impact energy exceeding the EA performance of the gusset member is input, the impact energy that is not absorbed by the gusset member will be dispersed via the battery frame. By suppressing movement of the floor frame in the vehicle width inward direction, damage to the battery unit can be avoided.

The battery frame includes a third frame member that extends in the vehicle width direction between the pair of first frame members and connects the pair of second frame members, and the gusset member includes a third frame member that extends between the pair of first frame members and connects the pair of second frame members. Since the gusset member is disposed at a position that includes a position in the longitudinal direction of the vehicle body corresponding to the outer end portion of the three frame members in the vehicle width direction, it is possible to increase the dispersion efficiency of impact energy that is not absorbed by the gusset member.

Furthermore , the gusset member is fastened to the side sill at a plurality of fastening portions arranged in the longitudinal direction of the vehicle body, and has a convex bead portion protruding outward between the adjacent fastening portions, so that the gusset member has a bead effect. EA performance can be increased .

The lower body structure of an electric vehicle according to a second aspect of the present invention 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 portion between the pair of side sills and the floor panel. The electric vehicle is equipped with a pair of left and right floor frames extending in the longitudinal direction of the vehicle body on the lower side thereof, and a battery unit including a battery frame that supports a battery module, and the battery unit is disposed between the pair of floor frames. In the lower body structure of the vehicle, the battery frame includes at least a pair of front and rear first frame members extending in the vehicle width direction, and a pair of left and right frame members connecting the pair of first frame members and extending in the vehicle front and rear direction. a second frame member, and a gusset member that connects an inner end of the side sill in the vehicle width direction and an outer end of the second frame member in the vehicle width direction; a third frame member extending in the vehicle width direction between the frame members and connecting the pair of second frame members, the gusset member corresponding to an outer end in the vehicle width direction of the third frame member; a first cross member member disposed at a position including a longitudinal direction of the vehicle body, forming a closed cross section extending in the vehicle width direction in cooperation with the floor panel on the upper surface of the floor panel, and connecting the pair of side sills; , a second cross member member that cooperates with the floor panel to form a closed cross section extending in the vehicle width direction on the upper surface of the floor panel behind the first cross member member and connects the pair of side sills; The gusset member has a front end portion disposed at a position corresponding to an outer end portion in the vehicle width direction of the first cross member member, and a rear end portion located at a position corresponding to an outer end portion in the vehicle width direction of the second cross member member. The pair of side sills are disposed at positions corresponding to the end portions, and the pair of side sills each constitute a closed cross section extending in the longitudinal direction of the vehicle body, and the side sills are disposed in the longitudinal direction region of the vehicle body corresponding to the region between the front and rear end portions of the gusset member. It is characterized by having knot members that partition the closed cross section into front and rear sections.
According to this configuration, the same operation and effect as in paragraph [0010] and paragraph [0012] are achieved, and in addition, impact energy that is not absorbed by the gusset member is applied to the battery frame, and the impact energy is applied to the first and second cross member members on the vehicle body side. can be dispersed into

The pair of side sills each constitute a closed cross section extending in the longitudinal direction of the vehicle body, and a joint member is provided in a region in the longitudinal direction of the vehicle body corresponding to an area between both front and rear ends of the gusset member to partition the closed cross section into front and rear parts. Therefore, in the event of a side collision, the impact energy input to the side sill can be reliably transmitted to the gusset member and the first and second cross member members.

The lower body structure of an electric vehicle according to claim 3 is characterized in that, in the invention according to claim 2 , the third frame member is disposed at a position in the longitudinal direction of the vehicle body between the first and second cross member members. It is said that
According to this configuration, impact energy input to the side sill can be efficiently dispersed using a plurality of load paths extending in the vehicle width direction.

According to the lower body structure of an electric vehicle of the present invention, the safety of the battery unit can be ensured regardless of the degree of impact energy, mainly by directly connecting the side sill and the battery frame.

1 is a plan view of a lower body structure of an electric vehicle according to Example 1. FIG. FIG. 3 is a bottom view of the lower vehicle body structure. FIG. 3 is a perspective view of the lower vehicle body structure viewed from the lower front side. 3 is a sectional view taken along the line IV-IV in FIG. 2. FIG. 3 is a sectional view taken along the line V-V in FIG. 2. FIG. It is a side view with an outer panel omitted from the side sill. FIG. 3 is an exploded perspective view of the battery unit. It is a perspective view of a gusset member.

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 its uses.

Embodiment 1 of the present invention will be described below based on FIGS. 1 to 8.
The vehicle V according to the first embodiment is a hybrid vehicle whose driving sources include an internal combustion engine (not shown) such as a gasoline engine or a diesel engine, and a vehicle driving electric motor (motor generator) (not shown).

As shown in FIGS. 1 to 3, the 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, and first and second cross members 4 and 5 (first and second cross members 4 and 5). (second cross member member), a battery unit 6, etc. Furthermore, this vehicle V is provided with a pair of left and right gussets 7 (gusset members) for directly connecting the pair of side sills 1 and the battery unit 6 (battery frame 30).
Hereinafter, in the drawings, the direction of arrow F is assumed to be forward in the longitudinal direction of the vehicle body, the direction of arrow L is assumed to be the left side in the width direction of the vehicle, and the direction of arrow U is assumed to be upward in the vertical direction of the vehicle body. Further, since this vehicle V has a bilaterally symmetrical structure, the right side member and right side portion will mainly be described below unless otherwise specified.

First, the pair of side sills 1 will be explained.
As shown in FIGS. 4 and 5, the right side sill 1 includes an outer panel 11 constituting the right side wall and an inner panel 12 constituting the left side wall. It forms a substantially rectangular closed cross section extending to . A vertically extending hinge pillar 8 is connected to the front end of the side sill 1, and a vertically extending rear pillar 9 is connected to the rear end of the side sill 1 (see FIGS. 1, 3, and 6). This 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.

The outer panel 11 includes an outer wall portion 11a that is perpendicular to the vehicle width direction, an upper wall portion 11b that extends to the left from the upper end of the outer wall portion 11a, and a lower wall portion that extends to the left from the lower end of the outer wall portion 11a. 11c, an upper flange extending upward from the left end of the upper wall 11b, and a lower flange extending downward from the left end of the lower wall 11c, and has a substantially hat-shaped cross section. The outer panel 11 is provided with an outer panel member 13 disposed on the right side of the outer panel 11.

The inner panel 12 includes an inner wall 12a orthogonal to the vehicle width direction, an upper wall 12b extending rightward from the upper end of the inner wall 12a, and a lower wall extending rightward from the lower end of the inner wall 12a. 12c, an upper flange extending upward from the right end of the upper wall 12b, and a lower flange extending downward from the right end of the lower wall 12c, and has a substantially hat-shaped cross section. The upper and lower flange portions of the inner panel 12 are joined to the upper and lower flange portions of the outer panel 11 by spot welding.

As shown in FIGS. 4 and 6, the inner panel 12 is provided with a first inner rain 14 disposed on the upper left side of the inner panel 12, and a plurality (for example, three) of second inner rains 15a to 15c. ing.
The first inner rain 14 is made of, for example, a 2.0 mm thick ultra-high tensile strength steel plate and has a substantially L-shaped cross section, and is formed from the front end of the inner panel 12 to the middle portion thereof.
The second inner rains 15a to 15c are respectively formed perpendicular to the front-rear direction.
These second inner rains 15a to 15c are joined to the inner wall portion 12a, the upper wall portion 12b, and the lower wall portion 12c, respectively, and constitute knot members that partition the closed cross section of the side sill 1 into front and rear parts.

The second inner rain 15a located at the frontmost side is arranged at a position in the longitudinal direction corresponding to the front end (front wall part) of the first cross member 4, and the second inner rain 15c located at the rearmost side is arranged at a position corresponding to the front end (front wall part) of the first cross member 4. It is arranged at a position in the front-rear direction corresponding to the rear end (rear wall part) of No. 5. The second inner rain 15b installed between the second inner rain 15a and 15c is arranged at a position in the front-rear direction corresponding to the front end (front wall) of the second cross member 5.

Next, the floor panel 2 and the pair of floor frames 3 will be explained.
The floor panel 2 is formed to span between a pair of side sills 1.
Both left and right end portions of the floor panel 2 are joined to the inner wall portions 12a of the pair of side sills 1, respectively, and constitute the floor surface of the cabin of the vehicle V. The rear end of the floor panel 2 is connected to a rear floor panel that forms a kick-up section that slopes rearward upward.

As shown in FIGS. 2 to 5, each of the pair of floor frames 3 has 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 extending back and forth.

Next, the first and second cross members 4 and 5 will be explained.
As shown in FIGS. 1 and 6, the first cross member 4 connects the front portions of the pair of side sills 1, and has a rectangular cross section extending left and right in cooperation with the upper surface of the floor panel 2. It forms a cross section. The first cross member 4 includes a first intermediate portion 4a and a pair of left and right first side portions 4b extending outward in the vehicle width direction from both left and right ends of the first intermediate portion 4a.

The first intermediate portion 4a is made of, for example, an ultra-high tensile strength 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 of the first intermediate portion 4a is joined to the upper surface of the floor panel 2 by welding.
The pair of first side portions 4b are made of a hot-rolled steel plate having a thickness of 1.0 mm, for example, and have a lower toughness than the first intermediate portion 4a, and each has a substantially hat-shaped cross section. The flange portions formed at the lower ends of these first side portions 4b are welded to the upper surface of the floor panel 2, and the flange portions formed at the outer end portions in the vehicle width direction are connected to the inner wall portions 12a of the side sills 1. It is joined by welding.

As shown in FIGS. 1, 5, and 6, the second cross member 5 connects the intermediate portions of the pair of side sills 1 behind the first cross member 4, and cooperates with the upper surface of the floor panel 2. It forms a closed cross section with a rectangular cross section extending left and right. The second cross member 5 includes a second intermediate portion 5a and a pair of left and right second side portions 5b extending outward in the vehicle width direction from both left and right ends of the second intermediate portion 5a.

The second intermediate portion 5a is made of, for example, an ultra-high tensile strength 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 of the second intermediate portion 5a is joined to the upper surface of the floor panel 2 by welding.
The pair of second side portions 5b are made of a hot rolled steel plate having a thickness of 2.3 mm, for example, and have a lower toughness than the second intermediate portion 5a, and each has a substantially hat-shaped cross section. The flange portions formed at the lower ends of the second side portions 5b are welded to the upper surface of the floor panel 2, and the flange portions formed at the outer end portions in the vehicle width direction are connected to the inner wall portions 12a of the side sills 1. It is joined by welding.

Next, the battery unit 6 will be explained.
The battery unit 6 is laid out in a space below the floor panel 2, accommodating a high voltage battery in which a plurality of battery modules 21 are connected in series. Therefore, the battery unit 6 is configured to ensure vibration resistance and water resistance.
As shown in FIGS. 5 and 7, the battery module 21 that supplies power to the vehicle drive electric motor is a rectangular parallelepiped battery assembly in which a plurality of rectangular parallelepiped battery cells each having a standard voltage are arranged in a stacked manner. . The battery cell is, for example, a lithium ion battery, which is a type of secondary battery.

As shown in FIGS. 2 to 7, the battery unit 6 mainly includes a metal bottom plate 22, a synthetic resin upper cover 23, and a substantially square-shaped battery frame 30 that supports a plurality of battery modules 21. It is an element. The battery frame 30 and the metal bottom plate 22 correspond to a lower cover of the battery unit 6, and the lower cover and the upper cover 23 cooperate to form a sealed pack structure.

The battery frame 30 includes a pair of front and rear first frame members 31 extending left and right, a pair of left and right second frame members 32 that connect the left and right ends of these pairs of first frame members 31, and A third frame member 33 extends left and right so as to connect the middle parts of the pair of second frame members 32, and a third frame member 33 extends from side to side to connect the middle parts of the pair of second frame members 32 behind the third frame member 33. and a fourth frame member 34 extending left and right.
These frame members 31 to 34 are made of, for example, an ultra-high tensile strength steel plate with a thickness of 2.0 mm.

The pair of second frame members 32 are arranged vertically below the pair of floor frames 3 along the pair of floor frames 3 so as to move outward in the vehicle width direction toward the rear.
As shown in FIGS. 4 and 5, the second frame member 32 on the right side has a substantially L-shaped lower panel 32a and a substantially W-shaped upper panel 32b.
The lower panel 32a and the upper panel 32b connect left flanges (inner side in the vehicle width direction) that extend horizontally to the left, and join right side flanges (outer side in the vehicle width direction) that extend vertically upward. This constitutes a substantially flat closed cross section C extending back and forth. The closed cross section C is formed into a substantially flat shape with the left and right dimensions larger than the vertical dimension, and the upper end of the closed cross section C and the lower end of the floor frame 3 are configured to be separated by a predetermined distance.

As shown in FIGS. 2 to 4 and 7, the second frame member 32 is fastened and fixed to the floor frame 3 via four bolts b1.
The three bolts b1 arranged on the front side pass through the second frame member 32 (closed cross section C) from below and are fastened to nut members n1 fixed within the closed cross section of the floor frame 3.
A seating surface for a bolt b1 that is partially recessed upward is formed around a bolt hole formed in the lower wall portion of the lower panel 32a. The bolt b1 disposed at the rear end is inserted from below into the bracket 24 that is joined to the rear side wall of the second frame member 32 and extends upward, and is inserted into the nut member ( (not shown).

The pair of first frame members 31 are basically configured in the same manner as the second frame member 32, and form a pair of closed cross sections extending left and right by a lower panel and an upper panel.
The first front frame member 31 is fastened and fixed to the front part of the vehicle body via two bolts b2. These bolts b2 are inserted through the first front frame member 31 from below and fastened to nut members (not shown) fixed to the front of the vehicle body.

The rear first frame member 31 is fastened and fixed to the rear part of the vehicle body via two pairs of left and right bolts b3. The two pairs of bolts b3 are inserted from below into a pair of left and right brackets 25 that are joined to the rear wall portion of the first rear frame member 31 and extend upward, and are inserted into the left and right brackets 25 formed at the top of the kick-up portion. They are each fastened to a nut member (not shown) fixed within the closed cross section of an extending cross member member (not shown).

As shown in FIGS. 4 and 5, the metal bottom plate 22 is arranged such that its left and right outer edge portions overlap the upper walls and the inner flange in the vehicle width direction of the pair of second frame members 32 (upper panels 32b), respectively. It is set up. Further, the front left and right outer edge portions of the metal bottom plate 22 overlap the upper wall portion and the rear flange of the first front frame member 31, and the rear front left and right outer edge portions overlap the upper wall portion and the rear side flange of the first rear frame member 31. It is arranged so as to overlap the front flange.
The upper cover 23 is disposed such that its outer edge overlaps the outer edge of the metal bottom plate 22, and its internal space is sealed using a fastening member.

As shown in FIG. 2, the third frame member 33 is arranged between the first cross member 4 and the second cross member 5 in plan view.
The third frame member 33 has a substantially hat-shaped cross section projecting downward, and cooperates with the lower surface of the metal bottom plate 22 to form a closed cross section with a rectangular cross section extending left and right.
As shown in FIG. 4, both left and right end portions of the third frame member 33 are held between the inner flanges in the vehicle width direction of the lower panel 32a and the upper panel 32b, respectively, and are fixed by inserting the second bolt b1 from the front side. There is.

The fourth frame member 34 is disposed behind the second cross member 5 in a bottom view (plan view from below). The fourth frame member 34 has a substantially hat-shaped cross section projecting downward, and cooperates with the lower surface of the metal bottom plate 22 to form a closed cross section with a rectangular cross section extending left and right.
Similar to the third frame member 33, both left and right end portions of the fourth frame member 34 are held between the inner flanges in the vehicle width direction of the lower panel 32a and the upper panel 32b, respectively, and are fixed by inserting the third bolt b1 from the front side. has been done.

Next, the pair of gussets 7 will be explained.
The pair of gussets 7 are each made of, for example, a high tensile strength steel plate with a thickness of 2.0 mm.
As shown in FIG. 2, the pair of gussets 7 are respectively arranged at positions including positions in the longitudinal direction corresponding to the outer ends of the third frame member 33 in the vehicle width direction.
Specifically, the front end of the gusset 7 is arranged at a position in the longitudinal direction corresponding to the vicinity of the outer end of the front wall of the first cross member 4 in the vehicle width direction, and the rear end is arranged near the outer end of the front wall of the first cross member 4 in the vehicle width direction. It is arranged at a position in the longitudinal direction corresponding to the vicinity of the outer end of the rear wall in the vehicle width direction.
In the front and rear regions corresponding to the regions between the front and rear ends of the gusset 7, second inner rains 15a and 15b that partition the closed cross section of the side sill 1 into front and rear parts are arranged (see FIG. 6).

As shown in FIGS. 2 to 5 and 8, the right gusset 7 includes a main body portion 7a extending in an inclined manner from the right side sill 1 to the right second frame member 32, and a right end (upper end) of the main body portion 7a. ), and a flange portion 7c extending downward from the left end (lower end) of the main body portion 7a. In the flange portion 7b, four bolt holes arranged in front and behind are formed at approximately equal intervals.

As shown in FIGS. 4 and 5, bolts b4 inserted into each bolt hole of the flange portion 7b are fixed to the inner panel 12 corresponding to the left (inner side in the vehicle width direction) end of the side sill 1.
These bolts b4 are fastened to nut members n4 fixed to the lower wall portion 12c corresponding to the lower end portion of the side sill 1. Further, the flange portion 7c is welded to a vertical wall portion of the lower panel 32a corresponding to the right (outside in the vehicle width direction) end of the second frame member 32.

The main body part 7a is arranged so as to have a predetermined intersecting angle with the horizontal such that the height position becomes higher as it moves to the right side. In order to efficiently disperse impact energy to the battery frame 30, the intersection angle is set to 45° or less.
A plurality (for example, seven) of convex bead portions 7d are formed on the main body portion 7a.
As shown in FIG. 8, the bead portion 7d is connected to the main body portion 7a, the flange portion 7b, and the flange portion 7c, respectively, and is configured to protrude to the right (in the direction of the outer surface) from the reference plane of the main body portion 7a.
Each bead portion 7d is formed between adjacent bolt holes of the flange portion 7b, so-called adjacent fastening portions.

With the above configuration, when a relatively small impact energy that is less than the EA (Energy Absorption) performance of the gusset 7 is input to the side sill 1 during a side collision, the first side portion 4b of the first cross member 4, the second cross member 5 By actively compressing and deforming (plastically deforming) the second side portion 5b and the gusset 7, impact energy is absorbed in the area between the side sill 1 and the floor frame 3, and the area between the pair of floor frames 3 is This avoids any influence on the battery unit 6 disposed in the battery.

On the other hand, when a large impact energy that exceeds the EA performance of the gusset 7 is input to the side sill 1, the impact energy that cannot be absorbed by the crushing deformation of the first side portion 4b, the second side portion 5b, and the gusset 7 is transferred to the first and second side portions. It is distributed and propagated to the cross members 4 and 5, and is also propagated to the battery frame 30 via the gusset 7, and is not directly input to the floor frame 3.
Thereby, movement of the floor frame 3 in the vehicle width inward direction is suppressed, and the safety of the battery unit 6 disposed between the pair of floor frames 3 is ensured.

Next, the functions and effects of the above-mentioned lower vehicle body structure will be explained.
According to the lower vehicle body structure according to the first embodiment, the battery frame 30 of the battery unit 6 disposed between the pair of floor frames 3 includes at least the pair of front and rear first frame members 31 extending in the vehicle width direction. and a pair of left and right second frame members 32 that connect the pair of first frame members 31 and extend in the front-rear direction, so that the battery unit 6 is firmly disposed between the pair of floor frames 3. be able to.
Since the gusset 7 is provided to connect the inner panel 12 corresponding to the inner end of the side sill 1 in the vehicle width direction and the vertical wall part of the lower panel 32a corresponding to the outer end in the vehicle width direction of the second frame member 32, the gusset 7 is If impact energy that is less than the EA performance is input, the impact energy can be absorbed by plastic deformation between the side sill 1 and the floor frame 3 without affecting the battery unit 6. In addition, since the side sill 1 and the battery frame 30 are directly connected via the gusset 7 without using any other member, if impact energy exceeding the EA performance of the gusset 7 is input, it will not be absorbed by the gusset 7. Impact energy can be dispersed through the battery frame 30, and damage to the battery unit 6 can be avoided by suppressing movement of the floor frame 3 in the vehicle width inward direction.

Since the gusset 7 is connected to the lower wall portion 12c corresponding to the lower end of the side sill 1, by reducing the intersection angle of the gusset 7 with respect to the horizontal, impact energy that is not absorbed by the gusset 7 can be efficiently transmitted to the battery frame 30. be able to.

The battery frame 30 has a third frame member 33 that extends left and right between the pair of first frame members 31 and connects the pair of second frame members 32, and the gusset 7 is connected to the third frame member 33. Since it is arranged at a position including a position in the longitudinal direction corresponding to the outer end in the vehicle width direction, it is possible to increase the dispersion efficiency of impact energy that is not absorbed by the gusset 7.

The gusset 7 is fastened to the side sill 1 via bolts b4 at a plurality of fastening parts arranged in the front-rear direction, and a convex bead part 7d protruding outward is formed between adjacent fastening parts, so that due to the bead effect, The EA performance of the gusset 7 can be increased.

A first cross member 4 that cooperates with the floor panel 2 to form a closed section extending left and right on the upper surface of the floor panel 2 and connects a pair of side sills 1; The gusset 7 has a second cross member 5 on the upper surface that cooperates with the floor panel 2 to form a closed cross section extending left and right and connects the pair of side sills 1, and the front end of the gusset 7 is connected to the first cross member. The second cross member member 5 is disposed at a position corresponding to the outer end of the second cross member member 5 in the vehicle width direction, and its rear end is disposed at a position corresponding to the outer end of the second cross member member 5 in the vehicle width direction.
Thereby, impact energy that is not absorbed by the gusset 7 can be applied to the battery frame 30 and can be dispersed to the first and second cross members 4 and 5 on the vehicle body side.

The pair of side sills 1 each have a second inner rain 15a, 15b that respectively constitutes a closed cross section that extends in the front and back, and partitions the closed cross section into a front and back region corresponding to the region between the front and rear ends of the gusset 7. In the event of a side collision, the impact energy input to the side sill 1 can be reliably transmitted to the gusset 7 and the first and second cross members 4 and 5.

Since the third frame member 33 is disposed at a position in the longitudinal direction between the first and second cross members 4 and 5, the impact energy input to the side sill 1 is efficiently transferred using a plurality of load paths extending in the vehicle width direction. can be dispersed.

Next, a modified example in which the above embodiment is partially modified will be described.
1] In the above embodiment, an example was described in which the battery unit 6 was arranged between the pair of floor frames 3, and a pair of second frame members 32 were arranged below the pair of floor frames 3. However, at least the battery module 21, which is the main part, should be arranged between the pair of floor frames 3 in plan view, and most of the battery unit 6 should be arranged between the pair of floor frames 3. It includes structure.

2] In the embodiment described above, an example has been described in which the gusset 7 directly connects the lower wall portion 12c of the side sill 1 and the lower panel 32a of the battery frame 30. It is only necessary that the portion be propagated to the second frame member 32.
For example, if the impact energy propagating on the load path toward the second frame member 32 starting from the gusset 7 is larger than the impact energy propagating on the other load paths, the gusset 7 may partially Alternatively, the structure may be connected to the floor frame 3.

3] In addition, those skilled in the art can implement various modifications to the embodiments described above or combinations of the embodiments without departing from the spirit of the present invention. It also includes any modifications.

1 Side sill 2 Floor panel 3 Floor frame 4 First cross member 5 Second cross member 6 Battery unit 7 Gusset 7d Bead portions 15a, 15b Second inner rain 21 Battery module 30 Battery frame 31 First frame member 32 Second frame member V Vehicle

Claims (3)

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 pair of left and right side sills extending in the longitudinal direction of the vehicle body between the pair of side sills and below the floor panel. A lower body structure for an electric vehicle, comprising: a floor frame; and a battery unit including a battery frame that supports a battery module, the battery unit being disposed between the pair of floor frames;
The battery frame includes at least a pair of front and rear first frame members extending in the vehicle width direction, and a pair of left and right second frame members connecting the pair of first frame members and extending in the vehicle body front and rear direction. death,
providing a gusset member that connects an inner end in the vehicle width direction of the side sill and an outer end in the vehicle width direction of the second frame member ;
The battery frame has a third frame member that extends in the vehicle width direction between the pair of first frame members and connects the pair of second frame members,
The gusset member is arranged at a position including a position in the vehicle body longitudinal direction corresponding to an outer end in the vehicle width direction of the third frame member,
The gusset member is fastened to the side sill at a plurality of fastening portions arranged in the longitudinal direction of the vehicle body, and a convex bead portion protruding outward is formed between the adjacent fastening portions. Lower body structure. 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 pair of left and right side sills extending in the longitudinal direction of the vehicle body between the pair of side sills and below the floor panel. A lower body structure for an electric vehicle, comprising: a floor frame; and a battery unit including a battery frame that supports a battery module, the battery unit being disposed between the pair of floor frames;
The battery frame includes at least a pair of front and rear first frame members extending in the vehicle width direction, and a pair of left and right second frame members connecting the pair of first frame members and extending in the vehicle body front and rear direction. death,
providing a gusset member that connects an inner end in the vehicle width direction of the side sill and an outer end in the vehicle width direction of the second frame member;
The battery frame has a third frame member that extends in the vehicle width direction between the pair of first frame members and connects the pair of second frame members,
The gusset member is arranged at a position including a position in the vehicle body longitudinal direction corresponding to an outer end in the vehicle width direction of the third frame member,
a first cross member member that cooperates with the floor panel to form a closed cross section extending in the vehicle width direction on the upper surface of the floor panel and connects the pair of side sills;
A second cross member member that cooperates with the floor panel to form a closed cross section extending in the vehicle width direction on the upper surface of the floor panel behind the first cross member member and connects the pair of side sills. death,
The gusset member has a front end located at a position corresponding to an outer end in the vehicle width direction of the first cross member member, and a rear end thereof located at an outer end in the vehicle width direction of the second cross member member. placed in corresponding positions,
The pair of side sills each constitute a closed cross section extending in the longitudinal direction of the vehicle body, and each has a joint member that partitions the closed cross section into front and rear parts in a region in the longitudinal direction of the vehicle body corresponding to a region between both front and rear ends of the gusset member. A lower body structure of an electric vehicle characterized by: 3. The lower vehicle body structure for an electric vehicle according to claim 2 , wherein the third frame member is disposed at a position in the longitudinal direction of the vehicle body between the first and second cross member members.