Body structure

Abstract

To enable peripheral components in a lower portion of a vehicle body to be efficiently mounted on the vehicle body, and to attain high mounting rigidity.SOLUTION: A vehicle body structure A includes a battery protection frame 33 having a hollow cross section. A partition wall portion 33e is provided within the battery protection frame 33. Closed cross section portions D1 to D4 are formed in the battery protection frame 33 by wall portions 33a to 33d and the partition wall portion 33e. Peripheral components 34, 35, 40 which are different from each other are mounted on the closed cross section portions D1 to D4.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle body structure for, for example, an electric vehicle. [Background technology]

[0002] For example, Patent Document 1 discloses a vehicle with a battery mounted below a floor panel. This patent document 1 includes an annular vehicle body bottom frame formed along the outer periphery of the floor panel and an annular battery mounting frame fixed to the vehicle body bottom frame, with the battery disposed inside the battery mounting frame. The battery mounting frame has upper and lower mounting walls that form flanges that protrude outward, and these upper and lower mounting walls are disposed on the underside of the vehicle body bottom frame and fastened with bolts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 105283 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the components that make up the suspension system are arranged under the vehicle body, and in the case of electric vehicles, many peripheral components such as battery-related components are also arranged. To attach each of these to the vehicle body requires the provision of individual dedicated brackets, which leads to problems of reduced space efficiency and manufacturing efficiency. In particular, if an attempt is made to increase the mounting rigidity of the peripheral components, the brackets become larger, further reducing space efficiency, and the number of fixing points on the brackets increases, further reducing manufacturing efficiency.

[0005] The present disclosure has been made in consideration of the above points, and its object is to enable peripheral parts on the lower part of a vehicle body to be efficiently attached to the vehicle body while also achieving high attachment rigidity. [Means for solving the problem]

[0006] To achieve the above object, a first aspect of the present disclosure can be based on a body structure of an electric vehicle that includes a traction motor and a battery that supplies power to the traction motor and is disposed below a floor panel. The body structure includes a hollow cross-sectional battery protection frame that is fixed to the vehicle body and protects the battery. A partition wall is provided inside the battery protection frame to partition the interior space of the battery protection frame. The battery protection frame has multiple closed cross-sectional sections formed by the partition wall and walls that form the outer surface of the battery protection frame, and different peripheral components are attached to each of the multiple closed cross-sectional sections.

[0007] According to this configuration, the battery protection frame fixed to the vehicle body has multiple closed cross-sectional portions, resulting in a highly rigid and lightweight battery protection frame. Because the multiple closed cross-sectional portions are located in different parts of the battery protection frame, it is possible to attach the lid and bottom plate of a battery unit to different closed cross-sectional portions, or to attach a suspension bracket to which a suspension device is connected to a closed cross-sectional portion other than the closed cross-sectional portion to which the lid and bottom plate of the battery unit are attached. This makes it possible to increase the mounting rigidity of peripheral components by utilizing the highly rigid battery protection frame, without having to provide dedicated brackets for each peripheral component, thereby improving space efficiency and manufacturing efficiency.

[0008] In the second aspect of the present disclosure, one of the closed cross-sectional portions may be provided with a plurality of attachment portions for the peripheral components.

[0009] According to this configuration, peripheral components to be attached to the closed cross-sectional portion can be attached by a plurality of attachment portions, thereby further increasing the attachment rigidity of the peripheral components.

[0010] A battery protection frame according to a third aspect of the present disclosure may be formed with a first closed cross-sectional portion, a second closed cross-sectional portion, and a third closed cross-sectional portion. A vehicle body structural member constituting a part of a vehicle body can be attached to the first closed cross-sectional portion, and the peripheral component constituting a part of a member supporting a suspension device can be attached to the second closed cross-sectional portion. Furthermore, the peripheral component constituting a part of a battery unit including a battery can be attached to the third closed cross-sectional portion.

[0011] With this configuration, the battery protection frame can be fixed to the vehicle body by attaching a vehicle body structural member to the first closed cross-sectional portion. Furthermore, by attaching peripheral components that form part of the member that supports the suspension device and peripheral components that form part of the battery unit to a common battery protection frame, it is possible to improve the space efficiency below the floor panel and ultimately increase the amount of battery that can be installed.

[0012] In a fourth aspect of the present disclosure, the battery protection frame may extend in the vehicle width direction and be disposed below the vehicle body structural member, and the first closed cross-sectional portion may be formed in an upper portion of the battery protection frame.

[0013] That is, the upper portion of the battery protection frame is close to the vehicle body structural member. This portion close to the vehicle body structural member can be fixed to the vehicle body structural member, so the battery protection frame can be firmly fixed to the vehicle body structural member.

[0014] The battery protection frame according to a fifth aspect of the present disclosure may extend in a vehicle width direction behind the battery, and the first closed cross-sectional portion may be formed in a vehicle rear portion of the battery protection frame, and the third closed cross-sectional portion may be formed in a vehicle front portion of the battery protection frame.

[0015] According to this configuration, the third closed cross-sectional portion is close to the battery unit, and by attaching peripheral components that form part of the battery unit to the third closed cross-sectional portion that is close to the battery unit, layout flexibility is improved and space efficiency is further improved.

[0016] According to a sixth aspect of the present disclosure, the partition wall may include a first partition wall extending in the vehicle longitudinal direction and in the vehicle width direction, and a second partition wall extending in the vehicle vertical direction and in the vehicle width direction. The first partition wall and the second partition wall may be integrated in a crossing state, thereby further improving the rigidity of the battery protection frame. [Effects of the Invention]

[0017] As described above, different peripheral components can be attached to each of the multiple closed cross-section sections formed in the hollow cross-section battery protection frame, so that multiple peripheral components can be efficiently attached to the vehicle body and high mounting rigidity can be obtained. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a side view of an electric vehicle according to an embodiment, with a portion thereof omitted; [Figure 2] FIG. 2 is a side view showing the electric vehicle divided into a lower structure and an upper structure. [Figure 3] FIG. [Figure 4] FIG. 2 is a bottom view of the rear portion of the vehicle body structure. [Figure 5] FIG. 2 is a perspective view of the rear portion of the lower structure as seen from above. [Figure 6] FIG. 10 is a side view of the rear portion of the lower structure. [Figure 7] FIG. 10 is a bottom view of the rear portion of the upper structure. [Figure 8] FIG. 2 is a cross-sectional view of the rear left portion of the vehicle body structure cut vertically. [Figure 9]FIG. 2 is an enlarged cross-sectional view of the rear left portion of the vehicle body structure cut in the vertical direction. [Figure 10] FIG. 2 is a cross-sectional perspective view of the rear left portion of the vehicle body structure cut in the vertical direction. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0020] Fig. 1 is a left side view of an electric vehicle (electric automobile) 1 equipped with a vehicle body structure A according to an embodiment of the present invention. As shown in Fig. 2, this electric vehicle 1 is equipped with a lower structure 2 and an upper structure 3. In Fig. 1, the front bumper, rear bumper, front and rear wheels, etc. are omitted and are shown with imaginary lines, and each part is shown schematically. In Fig. 2, in addition to the parts omitted in Fig. 1, the doors, bonnet hood, front fenders, windshields, front and rear lighting devices, interior materials, etc. are omitted and each part is shown schematically.

[0021] In the description of this embodiment, the front side of the vehicle will be simply referred to as "front," the rear side of the vehicle will be simply referred to as "rear," the right side of the vehicle will be simply referred to as "right," and the left side of the vehicle will be simply referred to as "left." The left-right direction of the vehicle is the vehicle width direction.

[0022] As shown in FIG. 1, the electric vehicle 1 is a passenger car. The electric vehicle 1 may be, for example, a sedan, a hatchback, a minivan, or the like, and its shape is not particularly limited. As shown in FIG. 2, the electric vehicle 1 is formed with a cabin R1 that serves as a passenger space (interior space) for occupants. As shown in FIG. 1, a front seat (seat) S1 is provided at the front of the cabin R1, and a rear seat S2 is provided behind the front seat S1 in the cabin R1. A luggage compartment R2 is provided behind the rear seat S2 as needed. The cabin R1 and the luggage compartment R2 are provided in an upper structure 3. Note that the cabin R1 may be provided with only the front seat S1, or may also have a third-row seat (not shown) behind the rear seat S2.

[0023] Meanwhile, the space (front space) in front of the vehicle interior R1 at the front of the electric vehicle 1 can be, for example, a power room R3. That is, as shown in Fig. 3, the vehicle body structure A is provided on the electric vehicle 1 that includes a front running motor M1 mounted at the front of the vehicle and a rear running motor M2 mounted at the rear of the vehicle, a battery B that supplies power to the running motors M1 and M2, and a battery case 10 that houses the battery B. The battery case 10 is disposed below a floor panel 70, which will be described later.

[0024] The front running motor M1 generates driving force to drive the left and right front wheels FT, and a front power train PT1 is made up of this front running motor M1 alone or the front running motor M1 together with a reducer, a transmission, etc. The rear running motor M2 shown in Figures 2 and 3 generates driving force to drive the left and right rear wheels RT (shown in Figure 1), and a rear power train PT2 is made up of this rear running motor M2 alone or the rear running motor M2 together with a reducer, a transmission, etc.

[0025] In this embodiment, the rear traveling motor M2 is configured to generate a higher maximum output (maximum torque) than the front traveling motor M1, and is larger than the front traveling motor M1. Accordingly, the rear powertrain PT2 is larger than the front powertrain PT1. Note that the rear traveling motor M2 may generate a lower maximum output than the front traveling motor M1, or the rear traveling motor M2 and the front traveling motor M1 may generate the same maximum output. Also, only the front powertrain PT1 may be provided, or only the rear powertrain PT2 may be provided. Furthermore, for example, in the case of a large vehicle, the front traveling motor M1 and the rear traveling motor M2 will be larger than those in a small vehicle.

[0026] As shown in Figure 2, the lower structure 2 includes a battery case 10, a pair of left and right front side frames 11, 12 that extend forward in front of the battery case 10, and a pair of left and right rear frames 13, 14 that extend rearward behind the battery case 10. The left and right rear frames 13, 14 extend in the front-to-rear direction at the rear of the vehicle. Reference numeral 11 indicates the left front side frame, and reference numeral 12 indicates the right front side frame. Reference numeral 13 indicates the left rear frame, and reference numeral 14 indicates the right rear frame. In Figure 2, a cover 35 (described below) of the battery case 10 has been removed.

[0027] In the case of a typical electric vehicle, the battery case is often separate from the vehicle body and is detachably attached under the floor, but in this embodiment, not only is the battery case 10 integrated with the left and right front side frames 11, 12 and the left and right rear frames 13, 14, and the front side frames 11, 12 and the rear frames 13, 14, together with the battery case 10, are detachably attached to the upper structure 3.

[0028] Specifically, the electric vehicle 1 of this embodiment is configured to be separable into an upper and lower structure 2 having a battery case 10, and an upper structure 3 that forms the vehicle compartment R1 and luggage compartment R2. Being separable into upper and lower structures means that the lower structure 2 is integrated with the upper structure 3 using fastening members such as bolts, nuts, and screws, without using welding, adhesives, or the like. This allows the lower structure 2 to be separated from the upper structure 3 as needed when performing maintenance or repairs on the electric vehicle 1 after it has been delivered to the user, improving maintainability. Note that the fastening members used in the following description also include bolts, nuts, screws, and the like.

[0029] Here, a ladder frame type vehicle body structure is known as an automobile body structure. In the case of a ladder frame type vehicle body structure, the ladder frame can be separated into an upper and lower portion and a cabin. However, since the ladder frame extends continuously in the fore-and-aft direction, it mainly bears the collision load in the event of a frontal collision and a rearward collision. In the event of a side collision, the ladder frame only auxiliarily bears the collision load, and it is the cabin that mainly bears the collision load. In this way, in a ladder frame type vehicle body structure, the components that bear the collision load in the event of a frontal collision and a rearward collision and in the event of a side collision are usually separated.

[0030] In contrast, in the case of the electric vehicle 1 of this embodiment, the lower structure 2 having front side frames 11, 12 and rear frames 13, 14, and the upper structure 3 are separable, but in the event of a frontal collision, a rear collision, or a side collision, the collision load is received by the lower structure 2 and the upper structure 3, and the collision load can be distributed and absorbed between the two structures 2, 3, which is a significant difference in technical concept from a conventional ladder frame type vehicle body structure. The structures of the lower structure 2 and the upper structure 3 will be described in detail below.

[0031] (undercarriage) First, we will explain the lower structure 2. In addition to the battery case 10, front side frames 11, 12, and rear frames 13, 14, the lower structure 2 also includes front and rear powertrains PT1, PT2, front wheels FT, rear wheels RT, a front suspension device 20, and a rear suspension device 21. There is no particular restriction on the type of the front suspension device 20 and the rear suspension device 21.

[0032] The battery case 10 and the battery B housed inside the battery case 10 constitute a battery unit BY, but other components, such as a battery cooling device, may also be included in the battery unit BY.

[0033] The battery case 10 is a large case formed below the floor panel 70 of the upper structure 3, extending from near the left end to near the right end of the floor panel 70 and from near the front end to near the rear end of the floor panel 70. By disposing the battery case 10 over a wide area below the floor panel 70 in this manner, a large-capacity battery B can be mounted on the electric vehicle 1. The battery B may be, for example, a lithium-ion battery, an all-solid-state battery, or another secondary battery. The battery B may also be a so-called battery cell or a battery pack containing multiple battery cells. In this embodiment, the battery B is configured by a battery pack, and multiple battery packs are mounted lined up in the front-rear and left-right directions.

[0034] The battery case 10 includes a left battery frame 30, a right battery frame 31, a front battery frame 32, a rear battery frame 33, a bottom plate 34, and a lid 35 (shown in FIG. 5) that covers the battery B from above. Note that FIGS. 2 and 3 show the state in which the lid 35 is removed.

[0035] The left battery frame 30, the right battery frame 31, the front battery frame 32, and the rear battery frame 33 are made of, for example, an aluminum alloy extrusion, but may also be made of aluminum alloy plate material or a press-formed steel plate material. The bottom plate 34 can also be made of an extrusion. In the following description, "extrusion material" refers to an aluminum alloy extrusion material, and "press-formed material" refers to an aluminum alloy plate material or a press-formed steel plate material. Each member may also be made of, for example, a casting.

[0036] The cross-sectional shape in the direction perpendicular to the longitudinal direction of the left battery frame 30, the right battery frame 31, the front battery frame 32, and the rear battery frame 33 are all rectangular. The left battery frame 30, the right battery frame 31, the front battery frame 32, and the rear battery frame 33 are all disposed at the same height and extend substantially horizontally.

[0037] The left battery frame 30 and the right battery frame 31 are outer battery frames that extend in the front-rear direction outside the battery B in the vehicle width direction. The left battery frame 30 is provided on the left side of the battery case 10 and extends in the front-rear direction along the left side sill 74. The left battery frame 30 is attached to the left side sill 74 with fastening members or the like. The right battery frame 31 is provided on the right side of the battery case 10 and extends in the front-rear direction along the right side sill 75. The right battery frame 31 is attached to the right side sill 75 with fastening members or the like. The left battery frame 30 and the right battery frame 31 are battery protection frames that protect battery B.

[0038] The front battery frame 32 is provided at the front of the battery case 10 and extends in the left-right direction. The rear battery frame 33 extends in the left-right direction at the rear of the battery case 10, i.e., behind the battery B. The front battery frame 32 and the rear battery frame 33 are battery protection frames that protect the battery B.

[0039] The left end of the front battery frame 32 is connected to the front end of the left battery frame 30, and the right end of the front battery frame 32 is connected to the front end of the right battery frame 31. The left end of the rear battery frame 33 is connected to the rear end of the left battery frame 30, and the right end of the rear battery frame 33 is connected to the rear end of the right battery frame 31. Therefore, the left battery frame 30, the right battery frame 31, the front battery frame 32, and the rear battery frame 33 are members that make up a frame-shaped frame formed to surround all of the batteries B in a plan view.

[0040] The left and right ends of the front battery frame 32 and the rear battery frame 33 are attached to left and right side sills 74, 75, respectively, by fastening members or the like. Furthermore, the left and right ends of the rear battery frame 33 are connected to the left and right battery frames 30, 31, and are therefore attached to the left and right side sills 74, 75 via the left and right battery frames 30, 31. Furthermore, the left and right ends of the rear battery frame 33 may be attached directly to the left and right side sills 74, 75.

[0041] The bottom plate 34 shown in Figure 4 and other figures extends substantially horizontally and is fixed to the undersides of the left battery frame 30, the right battery frame 31, the front battery frame 32, and the rear battery frame 33. The lid body 35 shown in Figures 5 and 6 and other figures is fixed to the upper surfaces of the left battery frame 30, the right battery frame 31, the front battery frame 32, and the rear battery frame 33. In other words, the lid body 35 is attached to the battery frames 30 to 33. The rear battery frame 33 protrudes rearward beyond the rear of the lid body 35.

[0042] The lid 35 may be attached to the battery frames 30 to 33 using, for example, fastening members, adhesives, welding, etc. Therefore, the left battery frame 30, the right battery frame 31, the front battery frame 32, the rear battery frame 33, the bottom plate 34, and the lid 35 define a battery storage space S (shown in FIG. 2) that stores the battery B.

[0043] The size of the battery storage space S can be changed depending on the capacity of the battery B to be installed. The size of the battery storage space S can be easily changed by changing the lengths of the left battery frame 30, right battery frame 31, front battery frame 32, and rear battery frame 33 and the shape of the bottom plate 34. For example, in the case of a compact vehicle with a short wheelbase and narrow tread, the left battery frame 30, right battery frame 31, front battery frame 32, and rear battery frame 33 can be shortened and the shape of the bottom plate 34 and lid 35 can be reduced accordingly, thereby making the battery storage space S smaller for a compact vehicle. On the other hand, in the case of a large vehicle, the left battery frame 30, right battery frame 31, front battery frame 32, and rear battery frame 33 can be lengthened and the shape of the bottom plate 34 and lid 35 can be increased accordingly, thereby making the battery storage space S larger for a large vehicle. If the left battery frame 30, right battery frame 31, front battery frame 32, and rear battery frame 33 are made of extruded material, the length can be easily changed. The bottom plate 34 can also be made of an extruded material, which allows for easy shape changes.

[0044] The top of the battery accommodating space S may be closed by the lid 35 or by the floor panel 70 of the upper structure 3. In addition to the battery B, the battery accommodating space S may also be provided with a cooling device for cooling the battery B, a heating device for heating the battery B (temperature control device), etc. Furthermore, the power of the battery B is supplied to the driving motors M1, M2 via a control device (not shown). Furthermore, the battery B can be charged via a charging socket, a contactless charger, etc. (not shown).

[0045] As shown in FIG. 2, first to third case interior members (unit interior members) 25A, 25B, and 25C are provided inside the battery case 10 constituting the battery unit BY as reinforcing members extending in the left-right direction. The first to third case interior members 25A, 25B, and 25C all have the same height, which is approximately the same as the height of the left battery frame 30 and the like. The case interior members 25A, 25B, and 25C may be made of an extruded material or a press-formed material. In this embodiment, three case interior members 25A, 25B, and 25C are provided, but the number of case interior members 25A, 25B, and 25C can be increased or decreased depending on the dimension of the battery case 10 in the front-rear direction. The first to third case interior members 25A, 25B, and 25C are second members.

[0046] The first to third case internal members 25A, 25B, and 25C are spaced apart from one another in the front-to-rear direction, with the first case internal member 25A positioned at the forefront and the third case internal member 25C positioned at the rearmost. The lower portions of each of the case internal members 25A, 25B, and 25C are fixed to the upper surface of the bottom plate 34. The left end portions of each of the case internal members 25A, 25B, and 25C are fixed to the inner surface (right side surface) of the left battery frame 30, and the right end portions of each of the case internal members 25A, 25B, and 25C are fixed to the inner surface (left side surface) of the right battery frame 31. In other words, the case internal members 25A, 25B, and 25C are members that connect the left battery frame 30 and the right battery frame 31.

[0047] A front central member (intra-unit member) 26 and first to third rear central members (intra-unit members) 27 to 29 are provided inside the battery case 10 as strength members extending in the front-rear direction. The front central member 26 and the first to third rear central members 27 to 29 are disposed at approximately the same height and are provided in the center of the battery case 10 in the left-right direction. The lower ends of the front central member 26 and the first to third rear central members 27 to 29 are attached to the upper surface of the bottom plate 34. The front central member 26 and the first to third rear central members 27 to 29 are first members. The front central member 26 and the first to third rear central members 27 to 29 intersect with the first to third case internal members 25A, 25B, and 25C.

[0048] The front central member 26 is disposed between the front battery frame 32 and the first case internal member 25A, with the front end of the front central member 26 fixed to the left-right center of the front battery frame 32 and the rear end of the front central member 26 fixed to the left-right center of the first case internal member 25A. Therefore, the front battery frame 32 is a member that extends to connect the front ends of the left and right battery frames 30, 31 and the front end of the front central member 26.

[0049] The first rear central member 27 is disposed between the first case internal member 25A and the second case internal member 25B, with the front end of the first rear central member 27 fixed to the left-right center of the first case internal member 25A and the rear end of the first rear central member 27 fixed to the left-right center of the second case internal member 25B. The second rear central member 28 is disposed between the second case internal member 25B and the third case internal member 25C, with the front end of the second rear central member 28 fixed to the left-right center of the second case internal member 25B and the rear end of the second rear central member 28 fixed to the left-right center of the third case internal member 25C. Furthermore, the third rear central member 29 is disposed between the third case internal member 25C and the rear battery frame 33, with the front end of the third rear central member 29 fixed to the left-right center of the third case internal member 25C and the rear end of the third rear central member 29 fixed to the left-right center of the rear battery frame 33. Therefore, the first to third case internal members 25A, 25B, 25C, the front central member 26, and the first to third rear central members 27-29 are arranged in a lattice pattern inside the battery case 10 and connected to one another, further enhancing the reinforcing effect of the battery case 10.

[0050] When an imaginary straight line extending in the front-to-rear direction is imagined in a plan view, the front central member 26 and the first to third rear central members 27-29 are positioned in the left-to-right direction so as to be disposed on that imaginary straight line. In other words, the first to third rear central members 27-29 are provided so as to be positioned on an imaginary extension line to the rear of the front central member 26. The front central member 26 and the first to third rear central members 27-29 may be configured as a single member that is continuous in the front-to-rear direction.

[0051] 5 and 6, the lower structure 2 includes a rear battery frame 33, left and right rear frames 13, 14, and an arm support bracket 40, and these members form part of the vehicle body structure A. The rear frames 13, 14 can be made of, for example, extruded material or press-formed material. In this embodiment, because the rear frames 13, 14 are made of extruded material, the cross-sectional shape in the direction perpendicular to the fore-and-aft direction is approximately uniform from the front end to the rear end.

[0052] The left and right rear frames 13, 14 are attached to a rear battery frame 33 that forms the rear part of the battery case 10 via arm support brackets 40. In other words, the arm support brackets 40 extend in the left-right direction along the rear battery frame 33, and the front parts of the left and right rear frames 13, 14 are fixed to the arm support brackets 40, which are connected to the rear battery frame 33.

[0053] Specifically, the arm support bracket 40 is made of a member that is integrally molded using metal, and can also be called a cross member because it extends in the left-right direction. The front parts of the left and right rear frames 13, 14 are fixed to the arm support bracket 40 using welding, adhesive, fastening members, etc. The metal that constitutes the arm support bracket 40 is not particularly limited, but examples include aluminum, in which case the arm support bracket 40 can be made from aluminum die-cast.

[0054] The left and right rear frames 13, 14 are attached to the rear battery frame 33 via arm support brackets 40, and the front portions of the rear frames 13, 14 can abut against the rear surface of the rear battery frame 33. Therefore, the rear frames 13, 14 extend rearward from the rear battery frame 33. Note that the front portions of the rear frames 13, 14 may be somewhat spaced rearward from the rear surface of the rear battery frame 33. In this case, too, it can be said that the rear frames 13, 14 extend rearward from the rear battery frame 33 when viewed as a whole.

[0055] The front portion of the left rear frame 13 is disposed so as to correspond to a portion of the rear battery frame 33 that is more to the left of the center in the left-right direction. In addition, the front portion of the right rear frame 14 is disposed so as to correspond to a portion of the rear battery frame 33 that is more to the right of the center in the left-right direction. This results in a predetermined distance between the left and right rear frames 13, 14. The distance between the rear frames 13, 14 is set narrower than the distance between the left battery frame 30 and the right battery frame 31 of the battery case 10. In addition, the heights of the left and right rear frames 13, 14 are approximately the same.

[0056] As shown in FIGS. 8 to 10 , the rear battery frame 33 has a hollow cross section perpendicular to the longitudinal direction, forming an internal space. Specifically, the rear battery frame 33 includes an upper wall 33a extending in the left-right direction, a front wall 33b extending downward from the front edge of the upper wall 33a and also extending in the left-right direction, a rear wall 33c extending downward from the rear edge of the upper wall 33a and also extending in the left-right direction, and a lower wall 33d extending from the lower edge of the front wall 33b to the lower edge of the rear wall 33c and also extending in the left-right direction. Therefore, the rear battery frame 33 has a rectangular cross section, but the cross-sectional shape of the rear battery frame 33 is not limited to a rectangular shape and may be a complex polygonal shape. While the upper wall 33a and the lower wall 33d are set to have the same longitudinal dimension, one may be shorter than the other. Furthermore, the front wall portion 33b and the rear wall portion 33c are set to have the same vertical dimension, but this is not limitative, and one may be shorter than the other.

[0057] A first partition wall 33e is provided inside the rear battery frame 33 between the upper wall portion 33a and the lower wall portion 33d to divide the interior space of the rear battery frame 33 into upper and lower sections. The first partition wall 33e extends in the front-rear direction from the vertically middle portion of the front wall portion 33b to the vertically middle portion of the rear wall portion 33c, and also extends in the left-right direction. The first partition wall 33e and the upper wall portion 33a are generally parallel, and the first partition wall 33e and the lower wall portion 33d are also generally parallel. In this embodiment, the first partition wall 33e is horizontal, but it may be inclined.

[0058] A second partition wall 33f is provided inside the rear battery frame 33 between the front wall wall 33b and the rear wall 33c, dividing the interior space of the rear battery frame 33 into front and rear sections. That is, in this embodiment, the partition wall includes a first partition wall 33e and a second partition wall 33f. Although not shown, only the first partition wall 33e or only the second partition wall 33f may be provided. Furthermore, although not shown, a third partition wall, a fourth partition wall, etc. may also be provided.

[0059] The second partition 33f and the first partition 33e are substantially perpendicular to each other, and the vertical middle portion of the second partition 33f and the front-rear middle portion of the first partition 33e are integrated in a crossed state. The second partition 33f extends in the vertical direction from the vertical middle portion of the upper wall 33a to the vertical middle portion of the lower wall 33d, and also extends in the left-right direction. The second partition 33f and the front wall 33b are substantially parallel, and the second partition 33f and the rear wall 33c are substantially parallel. In this embodiment, the second partition 33f is vertical, but it may be inclined.

[0060] The outer surface of the rear battery frame 33 is composed of an upper wall portion 33a, a front wall portion 33b, a rear wall portion 33c, and a lower wall portion 33d. As shown in FIGS. 9 and 10 , the rear battery frame 33 has four closed cross-sectional portions, namely, a first closed cross-sectional portion D1, a second closed cross-sectional portion D2, a third closed cross-sectional portion D3, and a fourth closed cross-sectional portion D4, formed by the upper wall portion 33a, the front wall portion 33b, the rear wall portion 33c, the lower wall portion 33d, the first partition portion 33e, and the second partition portion 33f. The first closed cross-sectional portion D1 is formed in the upper and rear portions of the rear battery frame 33. The second closed cross-sectional portion D2 is formed in the lower and rear portions of the rear battery frame 33. The third closed cross-sectional portion D3 is formed in the upper and front portions of the rear battery frame 33. The fourth closed cross-sectional portion D4 is formed in the lower and front portions of the rear battery frame 33. The third closed cross-sectional portion D3 and the fourth closed cross-sectional portion D4 are formed on the side closer to the rear battery frame 33, while the first closed cross-sectional portion D1 and the second closed cross-sectional portion D2 are formed on the side farther from the rear battery frame 33, i.e., on the side closer to the rear suspension device 21. As will be described in detail later, different peripheral parts are attached to the first to fourth closed cross-sectional portions D1 to D4. The peripheral parts are parts arranged around the rear battery frame 33, and include, for example, parts that form part of the member that supports the rear suspension device 21 and parts that form part of the battery unit BY.

[0061] More specifically, the first closed cross-sectional portion D1 is made up of a portion of the upper wall portion 33a rearward of the second partition wall portion 33f, a portion of the rear wall portion 33c above the first partition wall portion 33e, a portion of the second partition wall portion 33f above the first partition wall portion 33e, and a portion of the first partition wall portion 33e rearward of the second partition wall portion 33f. The rectangular closed cross-sectional portion formed by these wall portions is the first closed cross-sectional portion D1.

[0062] The second closed cross-sectional portion D2 is composed of a portion of the lower wall portion 33d rearward of the second partition wall portion 33f, a portion of the rear wall portion 33c below the first partition wall portion 33e, a portion of the second partition wall portion 33f below the first partition wall portion 33e, and a portion of the first partition wall portion 33e rearward of the second partition wall portion 33f. The rectangular closed cross-sectional portion formed by these wall portions constitutes the second closed cross-sectional portion D2. The first closed cross-sectional portion D1 and the second closed cross-sectional portion D2 share a common wall portion in the portion of the first partition wall portion 33e rearward of the second partition wall portion 33f.

[0063] The third closed cross-sectional portion D3 is composed of a portion of the upper wall portion 33a forward of the second partition wall portion 33f, a portion of the front wall portion 33b above the first partition wall portion 33e, a portion of the second partition wall portion 33f above the first partition wall portion 33e, and a portion of the first partition wall portion 33e forward of the second partition wall portion 33f. The rectangular closed cross-sectional portion formed by these wall portions constitutes the third closed cross-sectional portion D3. The first closed cross-sectional portion D1 and the third closed cross-sectional portion D3 share a common wall portion in the portion of the second partition wall portion 33f above the first partition wall portion 33e.

[0064] The fourth closed cross-sectional portion D4 is composed of a portion of the lower wall portion 33d forward of the second partition wall portion 33f, a portion of the front wall portion 33b below the first partition wall portion 33e, a portion of the second partition wall portion 33f below the first partition wall portion 33e, and a portion of the first partition wall portion 33e forward of the second partition wall portion 33f. The rectangular closed cross-sectional portion formed by these wall portions is the fourth closed cross-sectional portion D4. The second closed cross-sectional portion D2 and the fourth closed cross-sectional portion D4 share a common wall portion in the portion of the second partition wall portion 33f below the first partition wall portion 33e. The third closed cross-sectional portion D3 and the fourth closed cross-sectional portion D4 share a common wall portion in the portion of the first partition wall portion 33e forward of the second partition wall portion 33f.

[0065] 9, the arm support bracket 40 includes a vertical plate portion 40a extending in the vehicle width direction and up-down direction along the rear wall portion 33c of the rear battery frame 33, and a lower plate portion 40b extending forward from the lower edge of the vertical plate portion 40a along the lower wall portion 33d of the rear battery frame 33 and also extending in the vehicle width direction. The vertical plate portion 40a and the lower plate portion 40b are fixed to the rear wall portion 33c and the lower wall portion 33d of the rear battery frame 33, respectively, by a plurality of fastening members described below. By fixing the vertical plate portion 40a and the lower plate portion 40b of the arm support bracket 40 to the rear wall portion 33c and the lower wall portion 33d of the rear battery frame 33, respectively, in this manner, the mounting rigidity of the arm support bracket 40 to the rear battery frame 33 can be increased.

[0066] 4 and 5, the arm support bracket 40 includes a left outer rib 40c located on the left side of the left rear frame 13, a left inner rib 40d located on the right side of the left rear frame 13, a right outer rib 40e located on the right side of the right rear frame 14, and a right inner rib 40f located on the left side of the right rear frame 14. The left outer rib 40c and the left inner rib 40d prevent the left rear frame 13 from tipping in the left-right direction, and the right outer rib 40e and right inner rib 40f prevent the right rear frame 14 from tipping in the left-right direction. Furthermore, since the ribs 40c, 40d, 40e, and 40f are arranged to protrude in the left-right direction of the left and right rear frames 13 and 14, when an impact load acts on the rear frames 13 and 14 from behind, for example, the impact load can be dispersed over a wide range in the left-right direction by using the ribs 40c, 40d, 40e, and 40f.

[0067] The arm support bracket 40 is provided with a connecting portion 41 that connects the rear ends of the left outer rib 40c and the left inner rib 40d to the rear ends of the right outer rib 40e and the right inner rib 40f. The connecting portion 41 extends in the left-right direction and connects the front-rear direction middle portions of the left and right rear frames 13, 14 to each other by this connecting portion 41. That is, in a plan view, the left and right rear frames 13, 14, the rear battery frame 33, and the connecting portion 41 form a rectangular closed cross section.

[0068] A pair of left and right arm connectors (suspension connectors) 42, 43 are provided on the left and right sides, which are outboard in the vehicle width direction, of the arm support bracket 40. The front portions of the left and right suspension arms 21A are connected to the arm connectors 42, 43 so that they can rotate up and down. The arm connectors 42, 43 extend upward beyond the connector 41, and the upper portions of the arm connectors 42, 43 are each detachably attached to the upper structure 3. The arm support bracket 40 is also a component that constitutes part of the rear suspension device 21, and is a peripheral component that is disposed around the rear battery frame 33.

[0069] A rear suspension cross member 44 extending in the left-right direction is provided at the rear portions of the left and right rear frames 13, 14. The rear portions of the left and right rear frames 13, 14 are connected to each other by the rear suspension cross member 44. A pair of left and right arm connectors 44a, 44b are provided on the left and right sides, which are outboard in the vehicle width direction, of the rear suspension cross member 44 to which rear portions of the left and right suspension arms 21A are connected so as to be rotatable in the up-down direction. The arm connectors 44a, 44b extend upward, and the upper portions of the arm connectors 44a, 44b are each detachably attached to the upper structure 3. In addition, in a plan view, the left and right rear frames 13, 14, connector 41, and rear suspension cross member 44 form a rectangular closed cross section.

[0070] A subframe 46 is provided at the rear of the lower structure 2. The subframe 46 includes a left member 46a that is disposed rearward of the left rear frame 13 and extends in the front-to-rear direction, a right member 46b that is disposed rearward of the right rear frame 14 and extends in the front-to-rear direction, and a rear member 46c that connects the rear ends of the left member 46a and the right member 46b together.

[0071] The front portions of the left member 46a and the right member 46b of the subframe 46 are fixed to the rear suspension cross member 44. In other words, the subframe 46 is connected to the left and right rear frames 13, 14 via the rear suspension cross member 44. As shown in FIG. 6 , in the connected state, the left and right rear frames 13, 14 are positioned lower than the subframe 46.

[0072] (superstructure) Next, the upper structure 3 will be described. As shown in Fig. 2, the upper structure 3 includes a floor panel 70, a dash panel (partition portion) 71, and a pair of left and right side sills 74, 75. Reference numeral 74 denotes the left side sill, and reference numeral 75 denotes the right side sill.

[0073] The floor panel 70 forms the floor surface of the vehicle compartment R1 and is made of steel plates or the like that extend in the front-to-rear and left-to-right directions. The space above the floor panel 70 forms the vehicle compartment R1. A roof 80 is provided above the vehicle compartment R1. A front opening 3a and a rear opening 3b are formed on both the left and right sides of the upper structure 3. As shown in FIG. 1, the front opening 3a and the rear opening 3b can be opened and closed by a front door 81 and a rear door 82, respectively. Although not shown, a front door and a rear door are also provided on the right side of the upper structure 3 in an openable and closable manner.

[0074] The left and right side sills 74, 75 are disposed so as to extend in the front-to-rear direction at both left and right ends of the floor panel 70. The left end of the floor panel 70 is connected to the vertical middle portion of the left side sill 74, and the right end of the floor panel 70 is connected to the vertical middle portion of the right side sill 75. The upper portions of the side sills 74, 75 protrude upward from the connection portion of the floor panel 70, and the lower portions of the side sills 74, 75 protrude downward from the connection portion of the floor panel 70. The battery case 10 is disposed below the floor panel 70, and is therefore disposed between the left and right side sills 74, 75. In a side view of the vehicle, the lower portions of the side sills 74, 75 overlap with the battery case 10.

[0075] The dash panel 71 extends in the vehicle width direction and the vertical direction, and is a member for separating the vehicle compartment R1 from the power compartment R3. The lower end of the dash panel 71 is connected to the front end of the floor panel .

[0076] Figure 7 is a bottom view of the rear portion of the upper structure 3, and as shown in Figure 7, the floor panel 70 of the upper structure 3 has a rear panel portion 70A that forms the floor surface of the luggage compartment R2. Left and right rear wheel houses 72, 73 are provided on the left and right sides of the rear panel portion 70A, respectively.

[0077] The upper structure 3 includes a pair of left and right rear side frames 90, 91 that extend in the front-to-rear direction at the rear of the vehicle. The left rear side frame 90 is formed to extend along the left end of the rear panel portion 70A, on a position inward in the vehicle width direction from the left rear wheel house 72. A left crash can 90a is provided at the rear of the left rear side frame 90 so as to protrude rearward beyond the rear of the rear panel portion 70A.

[0078] The right rear side frame 91 is formed to extend along the right end of the rear panel portion 70A, on a position inward in the vehicle width direction from the right rear wheel house 73. A right crash can 91a is provided at the rear of the right rear side frame 91 so as to protrude rearward beyond the rear of the rear panel portion 70A. Bumper reinforcements 92 extending in the left-right direction are attached to the rear of the left crash can 90a and the rear of the right crash can 91a. The front portions of the left and right rear side frames 90, 91 are formed to bend or slope downward.

[0079] 4 and 8, the rear battery frame 33 of the battery case 10 extends in the vehicle width direction forward of the front portions of the rear side frames 90, 91. More specifically, because the battery case 10 is provided below the floor panel 70, the rear battery frame 33 is disposed below the front portions of the rear side frames 90, 91.

[0080] The front portion of the left rear side frame 90 is spaced a predetermined distance rearward and inward in the vehicle width direction from the rear portion of the left side sill 74, and the front portion of the left rear side frame 90 is not connected to the rear portion of the left side sill 74. Similarly, the front portion of the right rear side frame 91 is spaced a predetermined distance rearward and inward in the vehicle width direction from the rear portion of the right side sill 75, and the front portion of the right rear side frame 91 is not connected to the rear portion of the right side sill 75. In other words, assuming that the left rear side frame 90 and the left side sill 74 are connected, the front portion of the rear side frame 90 would extend forward and be connected to the rear portion of the side sill 74. This would result in the front portion of the rear side frame 90 protruding inward in the vehicle width direction from the rear wheel well 72. Similarly, on the right side, the front portion of the rear side frame 91 would protrude inward in the vehicle width direction from the rear wheel well 73. If the left and right rear side frames 90, 91 protrude inward in the vehicle width direction, the dimension of the rear side of the battery case 10 in the left-right direction must be shortened, which in turn reduces the amount of battery B that can be mounted.

[0081] In this embodiment, the rear side frames 90, 91 are disconnected from the side sills 74, 75, respectively, to form a space that allows the battery case 10 to be extended rearward. This allows the battery case 10 to be extended rearward until the rear side of the battery case 10 approaches the rear wheel houses 72, 73, and also ensures a long dimension in the left-right direction at the rear of the battery case 10, allowing for an increased capacity for the battery B to be mounted.

[0082] 7, for example, assuming an imaginary straight line L1 extending forward from the center of the front of the left rear side frame 90 in the left-right direction, and an imaginary straight line L2 extending forward from the center of the front of the right rear side frame 91 in the left-right direction, the battery case 10 (outline shown by the imaginary line) is provided from an area to the left of the imaginary line L1 to an area to the right of the imaginary line L2. By providing such a large battery case 10, the battery B can be mounted outside the imaginary lines L1 and L2 in the vehicle width direction, thereby further increasing the amount of battery B that can be mounted.

[0083] In addition, in a side view of the vehicle, the battery case 10 extends rearward beyond the rear portions of the side sills 74, 75. Therefore, the rear battery frame 33 is positioned rearward beyond the rear portions of the side sills 74, 75, and therefore the battery B can be mounted rearward beyond the rear portions of the side sills 74, 75.

[0084] Furthermore, if the rear side frames 90, 91 and the side sills 74, 75 are disconnected from each other, there may be a problem in that there is no direct load transfer path from the rear side frames 90, 91 to the side sills 74, 75 when an impact load acts from behind. However, in this embodiment, even if there is no such load transfer path, the impact load from behind can be absorbed by using the battery case 10.

[0085] 8 to 10, the left and right rear side frames 90, 91 are connected to the rear battery frame 33 by arm support brackets 40. Specifically, the upper structure 3 includes a rear cross member 95 as a vehicle body structural member that forms part of the vehicle body, and this rear cross member 95 is disposed so that the front portions of the rear side frames 90, 91 abut against it from behind, and extends in the vehicle width direction. The rear cross member 95 continues from near the front of the left wheel house 72 to near the front of the right wheel house 73, and includes a front plate portion 95a that extends in the up-down and left-right directions, a rear plate portion 95b that is disposed rearwardly from the front plate portion 95a and extends in the up-down and left-right directions, and a lower plate portion 95c that extends from the lower end of the front plate portion 95a to the lower end of the rear plate portion 95b. The vertical dimension of the rear plate portion 95b is set to be longer than the vertical dimension of the front plate portion 95a, and the upper end of the rear plate portion 95b is located higher than the upper end of the front plate portion 95a. In addition, the inclination angles of the front plate portion 95a and the rear plate portion 95b are set so that the distance between the front plate portion 95a and the rear plate portion 95b in the vertical direction becomes wider as it goes up.

[0086] The upper end of the front plate portion 95a and the upper end of the rear plate portion 95b are joined to the underside of the floor panel 70, and a closed cross section is formed by the front plate portion 95a, the rear plate portion 95b, the lower plate portion 95c, and the floor panel 70. This increases the rigidity of the floor panel 70.

[0087] The front portions of the rear side frames 90, 91 abut against a rear plate portion 95b of the rear cross member 95 from behind, and are joined to this rear plate portion 95b and a lower plate portion 95c. Because the vertical dimension of the rear plate portion 95b is longer than that of the front plate portion 95a, a wide joining area between the rear side frames 90, 91 and the rear cross member 95 can be ensured.

[0088] 8, the rear battery frame 33 is disposed below the rear cross member 95, and the lower plate portion 95c of the rear cross member 95 is formed to extend along the outer surface (upper surface) of the upper wall portion 33a of the rear battery frame 33. The rear cross member 95 and the rear battery frame 33 are fastened and fixed in the vertical direction, so that the rear battery frame 33 is detachably attached to the rear cross member 95.

[0089] Specifically, as shown in Fig. 9, the first closed cross-sectional portion D1 of the rear battery frame 33 is adjacent to and below the rear cross member 95, and the rear cross member 95 is attached to the first closed cross-sectional portion D1 of the rear battery frame 33. As a prerequisite for this configuration, the lower surface of a cylindrical nut N1 extending in the vertical direction is fixed to the upper surface of the lower plate portion 95c of the rear cross member 95. Because the nut N1 is disposed inside the rear cross member 95, the internal space of the rear cross member 95 can be effectively utilized.

[0090] As shown in FIG. 10 , multiple nuts N1 are provided at intervals in the left-right direction. A corresponding number of reinforcing plates 95d are provided inside the rear cross member 95. The reinforcing plates 95d have through holes 95e through which the upper portions of the nuts N1 pass. With the upper portions of the nuts N1 passing through the through holes 95e, the outer surfaces of the nuts N1 are welded to the peripheries of the through holes 95e, thereby increasing the fixing strength of the nuts N1. A front portion of the reinforcing plate 95d is formed to fit along the inner surface of the front plate portion 95a and is welded to the front plate portion 95a. A rear portion of the reinforcing plate 95d is formed to fit along the inner surface of the rear plate portion 95b and is welded to the rear plate portion 95b. Therefore, the front plate portion 95a and the rear plate portion 95b are connected by the reinforcing plate 95d.

[0091] The first partition wall portion 33e of the rear battery frame 33 has insertion holes 33g formed therein, through which bolts B1 are inserted from below. The number of insertion holes 33g is the same as the number of nuts N1, and the insertion holes 33g are formed at the same intervals as the spacing between the nuts N1. The nuts N1 are disposed directly above the insertion holes 33g. The bolts B1 inserted into the insertion holes 33g penetrate the upper wall portion 33a of the rear battery frame 33 and the lower plate portion 95c to be screwed into the nuts N1 from below. Although not shown, the upper wall portion 33a of the rear battery frame 33 has insertion holes formed therein, through which the bolts B1 are inserted, and the lower plate portion 95c of the rear cross member 95 also has insertion holes formed therein, through which the bolts B1 are inserted.

[0092] A hole 33h is formed in the lower wall 33d of the rear battery frame 33. This hole 33h is for passing a bolt B1 through, and is formed to open to the outer surface (lower surface) of the lower wall 33d of the rear battery frame 33 and to communicate with the interior space of the rear battery frame 33. The shape of the hole 33h is circular, but is not limited to this. The diameter of the hole 33h is set larger than the maximum outer diameter of the head of the bolt B1, allowing the bolt B1 to be easily inserted.

[0093] The number of holes 33h provided is the same as the number of nuts N1, and they are spaced apart at the same intervals as the spacing between the nuts N1. By inserting the bolts B1 with their shanks facing upward through the holes 33h into the space inside the rear battery frame 33 and threading them into the nuts N1, the rear cross member 95 and the rear battery frame 33 can be fastened together at multiple locations.

[0094] The head of the bolt B1 enters the interior of the rear battery frame 33 and abuts against the peripheral edge of the insertion hole 33g in the first partition wall 33e from below. As a result, the head of the bolt B1 applies a fixing force from below to above on the peripheral edge of the insertion hole 33g in the first partition wall 33e, thereby fixing the rear battery frame 33 to the rear cross member 95 inside the rear battery frame 33. In other words, the bolt B1 is a fixing member that is inserted into the space inside the rear battery frame 33 from the hole 33h and can fix the rear battery frame 33 to the rear cross member 95, which is separate from the arm support bracket 40, inside the rear battery frame 33. Note that although not shown, the fixing member is not limited to a bolt and may be a fastening member such as a screw or a rivet.

[0095] The lower plate portion 40b of the arm support bracket 40 is formed to extend along the outer surface (outer surface of the lower wall portion 33d) of the rear battery frame 33 on which the hole 33h is formed. Therefore, the lower plate portion 40b can cover the hole 33h from below. In this embodiment, the lower plate portion 40b is a cover portion that covers the hole 33h from the outside of the rear battery frame 33. Because the lower plate portion 40b extends further forward than the front portion of the hole 33h, it can completely cover the hole 33h.

[0096] (Arm support bracket mounting structure) Next, the mounting structure of the arm support bracket 40 to the rear battery frame 33 will be described. As shown in Fig. 9, the second closed cross-sectional portion D2 of the rear battery frame 33 is adjacent to and above the lower plate portion 40b of the arm support bracket 40, and the lower plate portion 40b of the arm support bracket 40 is mounted to the second closed cross-sectional portion D2 of the rear battery frame 33. As a prerequisite configuration, a plurality of nuts N2 are fixed to the inner surface (upper surface) of the rear portion of the lower wall portion 33d of the rear battery frame 33 at intervals in the vehicle width direction. The axes of the nuts N2 extend in the vertical direction and are parallel to the axis of the nuts N1. The rear portion of the lower wall portion 33d is part of the second closed cross-sectional portion D2.

[0097] The lower plate portion 40b of the arm support bracket 40 is disposed on the outer surface (lower surface) of the lower wall portion 33d of the rear battery frame 33, and a plurality of bolts B2 that thread into nuts N2 pass through the lower wall portion 33d of the rear battery frame 33 and the lower plate portion 40b of the arm support bracket 40 from below. The bolts B2 that pass through the lower wall portion 33d of the rear battery frame 33 and the lower plate portion 40b of the arm support bracket 40 from below are threaded into the nuts N2 from below. By threading each bolt B2 into each nut N2, the arm support bracket 40 and the rear battery frame 33 can be fastened together at multiple locations.

[0098] The first closed cross-sectional portion D1 and the second closed cross-sectional portion D2 of the rear battery frame 33 are adjacent to and rear of the vertical plate portion 40a of the arm support bracket 40, and the vertical plate portion 40a of the arm support bracket 40 is attached to the first closed cross-sectional portion D1 and the second closed cross-sectional portion D2 of the rear battery frame 33. As a prerequisite configuration, a plurality of nuts N3 are fixed to the inner surface (front surface) of the rear wall portion 33c of the rear battery frame 33. The axis of the nuts N3 extends in the front-rear direction and is perpendicular to the axes of the nuts N1 and N2 in a side view. The multiple nuts N3 are provided spaced apart from one another in the vehicle width direction and are also provided on the upper portion (portion forming the first closed cross-sectional portion D1) and the lower portion (portion forming the second closed cross-sectional portion D2) of the rear wall portion 33c of the rear battery frame 33. The vertical plate portion 40a of the arm support bracket 40 is disposed on the outer surface (rear surface) of the rear wall portion 33c of the rear battery frame 33, and a plurality of bolts B3 that thread into nuts N3 pass through the rear wall portion 33c of the rear battery frame 33 and the vertical plate portion 40a of the arm support bracket 40. The bolts B3 that pass through the rear wall portion 33c of the rear battery frame 33 and the vertical plate portion 40a of the arm support bracket 40 from below are threaded into the nuts N3 from behind. By threading each bolt B3 into each nut N3, the arm support bracket 40 and the rear battery frame 33 can be fastened together at multiple locations.

[0099] Therefore, when focusing on the first closed cross-sectional portion D1 of the rear battery frame 33, the rear cross member 95 and the vertical plate portion 40a of the arm support bracket 40 are attached to the first closed cross-sectional portion D1. The multiple attachment portions of the rear cross member 95 to the first closed cross-sectional portion D1 are formed by bolts B1, and the multiple attachment portions of the vertical plate portion 40a to the first closed cross-sectional portion D1 are formed by upper nuts N3.

[0100] Furthermore, the vertical plate portion 40a of the arm support bracket 40 is also attached to the second closed cross-sectional portion D2 of the rear battery frame 33, and the multiple attachment portions of the vertical plate portion 40a to the second closed cross-sectional portion D2 are formed by lower nuts N3.

[0101] (Installation structure of battery unit lid and bottom plate) The lid body 35 and bottom plate 34 of the battery unit BY are peripheral components disposed around the rear battery frame 33. As shown in FIG. 9 , the third closed cross-sectional portion D3 of the rear battery frame 33 is adjacent to and below the rear portion of the lid body 35 of the battery unit BY, and the rear portion of the lid body 35 is attached to the third closed cross-sectional portion D3 of the rear battery frame 33. The rear portion of the lid body 35 overlaps the upper surface of the third closed cross-sectional portion D3 and is attached to the upper surface of the third closed cross-sectional portion D3 by welding or adhesive. Although not shown, the rear portion of the lid body 35 may also be attached to the third closed cross-sectional portion D3 by a fastening member.

[0102] Furthermore, the fourth closed cross-sectional portion D4 of the rear battery frame 33 is adjacent to and above the rear portion of the bottom plate 34 of the battery unit BY, and the rear portion of the bottom plate 34 is attached to the fourth closed cross-sectional portion D4 of the rear battery frame 33. As a prerequisite configuration, a plurality of nuts N4 are fixed to the inner surface (upper surface) of the front portion of the lower wall portion 33d of the rear battery frame 33 at intervals in the vehicle width direction. The axes of the nuts N4 extend in the vertical direction and are parallel to the axis of the nuts N1. The front portion of the lower wall portion 33d is part of the fourth closed cross-sectional portion D4.

[0103] A bottom plate 34 is disposed on the outer surface (lower surface) of the lower wall portion 33d of the rear battery frame 33, and a plurality of bolts B4 that thread into nuts N4 penetrate from below through the lower wall portion 33d and bottom plate 34 of the rear battery frame 33. The bolts B4 that penetrate the lower wall portion 33d and bottom plate 34 of the rear battery frame 33 from below are threaded into the nuts N4 from below. By threading each bolt B4 into each nut N4, the bottom plate 34 and the rear battery frame 33 can be fastened together at multiple locations.

[0104] (Effects of the embodiment) As described above, according to this embodiment, the first partition wall 33e and the second partition wall 33f are provided on the rear battery frame 33 fixed to the vehicle body to form the first to fourth closed cross-sectional portions D1 to D4, resulting in a highly rigid and lightweight rear battery frame 33. The first to fourth closed cross-sectional portions D1 to D4 are located at different positions on the rear battery frame 33, allowing the third closed cross-sectional portion D3 and the fourth closed cross-sectional portion D4 to be located close to the battery unit BY. This allows the cover 35 of the battery unit BY to be attached to the third closed cross-sectional portion D3, and the bottom plate 34 to be attached to the fourth closed cross-sectional portion D4. Furthermore, the first closed cross-sectional portion D1 and the second closed cross-sectional portion D2 can be located close to the rear suspension device 21, allowing the arm support bracket 40 to be attached to the first closed cross-sectional portion D1 and the second closed cross-sectional portion D2. This allows the highly rigid rear battery frame 33 to be used to increase the mounting rigidity of peripheral components without providing dedicated brackets for each peripheral component, and also improves space efficiency.

[0105] The above-described embodiments are merely examples in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention.

[0106] In this embodiment, four closed cross-sectional portions are formed on the rear battery frame 33, but this is not limiting and two, three, or five or more closed cross-sectional portions may be formed. In this case, different peripheral components can be attached to each closed cross-sectional portion. The size of the closed cross-sectional portions can be set arbitrarily, and the multiple closed cross-sectional portions may all be different sizes, some may be the same size, or all may be the same size. The peripheral components may also be cross members, various frames, electrical components, etc. [Industrial Applicability]

[0107] As described above, the vehicle body structure according to the present disclosure can be provided in, for example, an electric vehicle. [Explanation of symbols]

[0108] 1 Electric vehicles 10 Battery case 21 Rear suspension device 33 Rear battery frame (battery protection frame) 33a Upper wall part 33b Front wall 33c Rear wall 33d Lower wall part 33e 1st bulkhead part 33f 2nd bulkhead part 34 Bottom plate (peripheral parts) 35 Lid (peripheral parts) 40 Arm support bracket (peripheral parts) 42, 43 Arm connection part (suspension connection part) 95 Rear cross member (body component) BY Battery Unit D1~D4 1st~4th closed section

Claims

1. A vehicle body structure for an electric vehicle including a driving motor and a battery that supplies power to the driving motor and is disposed below a floor panel, a hollow cross-section battery protection frame fixed to a vehicle body to protect the battery; the battery protection frame is disposed below a rear cross member that extends in a vehicle width direction behind the battery and that constitutes a part of the vehicle body, a partition wall portion that divides the internal space of the battery protection frame is provided inside the battery protection frame, In the battery protection frame, a first closed cross-sectional portion, a second closed cross-sectional portion, and a third closed cross-sectional portion to which peripheral components are attached are formed by a wall portion constituting an outer surface of the battery protection frame and the partition wall portion, the first closed cross-sectional portion is formed in a vehicle rear portion of an upper portion of the battery protection frame, the second closed cross-sectional portion is formed in a vehicle rear portion of a lower portion of the battery protection frame, the third closed cross-sectional portion is formed in a vehicle front portion of the battery protection frame, the rear cross member is attached to the first closed cross-sectional portion as the peripheral component, a component constituting a part of a member supporting a suspension device disposed rearward of the battery protection frame in the vehicle is attached to the second closed cross-sectional portion as the peripheral component, A vehicle body structure in which a lid of a battery case that houses the battery or a bottom plate of the battery case is attached as the peripheral part to the third closed cross-sectional portion.

2. The vehicle body structure according to claim 1, A vehicle body structure in which a plurality of mounting portions for the peripheral components are provided in one of the first closed cross-sectional portion, the second closed cross-sectional portion, and the third closed cross-sectional portion.

3. The vehicle body structure according to claim 1 or 2, the partition wall portion includes a first partition wall portion extending in the vehicle longitudinal direction and in the vehicle width direction, and a second partition wall portion extending in the vehicle vertical direction and in the vehicle width direction, A vehicle body structure in which the first partition wall portion and the second partition wall portion are integrated in a crossing state.

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