Vehicle body structure

Abstract

To transmit a buffer load acting in a vehicle fore and aft direction dispersedly to a vehicle body and a battery case to optimize strength of each member forming a vehicle body and achieve reduction of the weight of an entire vehicle.SOLUTION: A vehicle body structure A includes: side frames 72; side sills 73; floor reinforcements 151 each of which transmits a load from the side frame 72 to the side sill 73; frame members 11 each extending from a battery case 10 in an anteroposterior direction below the side frame 72; and outer connection parts each extending from a middle part as seen in the anteroposterior direction of the frame member 11 to the side sill 73 side and connected to the battery case 10. The floor reinforcement 151 and the outer connection part are spaced apart from each other in a vertical direction.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a vehicle body structure of an electric vehicle.

Background Art

[0002] For example, in the case of an automobile equipped with a driving motor, a battery unit for supplying power to the driving motor is mounted, and this battery unit has been increased in capacity in order to extend the cruising range by the driving motor.

[0003] The battery unit of the electric vehicle disclosed in Patent Document 1 is mounted in a wide area under the floor. In the front part of the vehicle body of this vehicle, a pair of left and right front side members extending in the vehicle longitudinal direction and an under member extending in the vehicle longitudinal direction below the front side member are provided. Further, the battery unit under the floor includes a case main body portion. From the front wall of the case main body portion, a pair of left and right front extending portions extending forward of the vehicle are integrally formed with the front wall by casting. The rear end portion of the under member is connected to the front end portion of each front extending portion, and the front extending portion and the under member are continuous in the vehicle longitudinal direction.

[0004] In Patent Document 1, the under member is configured to be more easily deformed than the front extending portion. Therefore, when the vehicle has a frontal collision with an obstacle or the like, first, the under member is deformed and the collision load is absorbed. The collision load that cannot be absorbed by the deformation of the under member is absorbed by the deformation of the front extending portion of the case main body portion. That is, in Patent Document 1, the collision load is absorbed in two stages by actively deforming the under member and the front extending portion of the case main body portion as impact absorbing members during a frontal collision, and the deformation of the case main body portion is suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in Patent Document 1, by combining an under member that deforms under a relatively small load and a front extension part that deforms under a relatively large load in the vehicle longitudinal direction, the collision load is prevented from being transmitted to the case main body part, and deformation of the case main body part is suppressed.

[0007] However, in automobiles, further improvement in collision safety is required. In particular, when a large collision load is input to the vehicle body, it is of course necessary to suppress deformation of the cabin due to the collision load, and in the case of electric vehicles, it is also required to protect the large-capacity battery cells mounted therein. On the other hand, there is also a strong demand for weight reduction of the vehicle body, so the issue is how to achieve both further improvement in collision safety and weight reduction of the vehicle body.

[0008] In this regard, in the case of Patent Document 1, since the under member and the front extension part are deformed to absorb the collision load at the lower part of the vehicle body, when trying to cope with a larger input of collision load, the strength of the front side member located above the under member must be increased, and for this reason, there is a concern that the vehicle body weight will increase. Further, when the strength of the front side member is increased, a local concentrated load is input to the vehicle body from the rear end portion of the front side member, so reinforcement of that portion is also necessary, which may lead to a further increase in vehicle body weight.

[0009] The present invention has been made in view of such points, and the object thereof is to optimize the strength of each member constituting the vehicle body by dispersing and transmitting the collision load in the vehicle longitudinal direction to the vehicle body and the battery case, thereby realizing weight reduction of the entire vehicle.

Means for Solving the Problems

[0010] In order to achieve the above object, in a first aspect of the present disclosure, a vehicle body structure of an electric vehicle can be premised on having a traveling motor and a battery case that houses a battery for supplying power to the traveling motor disposed below a floor panel. The vehicle body structure includes a pair of left and right side frames disposed to extend in the vehicle longitudinal direction on one side and above in the vehicle longitudinal direction with respect to the floor panel, a pair of left and right side sills disposed to extend in the vehicle longitudinal direction at both ends in the vehicle width direction of the floor panel, a floor reinforcement that connects the side frames and the side sills and transmits a load from the side frames to the side sills, a frame member that extends in one direction in the vehicle longitudinal direction below the side frame from the battery case, and an outer connection portion that extends from a midportion in the vehicle longitudinal direction of the frame member toward the side sill side and is connected to the battery case. The floor reinforcement and the outer connection portion are spaced apart from each other in the vertical direction.

[0011] According to this configuration, when the side frame and the frame member are provided at the vehicle front portion, a collision load during a frontal collision is input to the side frame and the frame member. The collision load input to the side frame is transmitted to the side sill via the floor reinforcement. Also, the collision load input to the frame member is transmitted to and absorbed by the battery case because the outer connection portion is connected to the battery case, and further, since the outer connection portion extends toward the side sill side, it can also act toward the side sill side via the outer connection portion. At this time, since the floor reinforcement and the outer connection portion are separated from each other in the vertical direction, the route of the collision load transmitted from the side frame to the side sill and the route of the collision load acting toward the side sill side from the frame member are different routes. Therefore, the collision load is transmitted to the side sill through a plurality of routes. Since this side sill is a member having particularly high rigidity among the members generally constituting the vehicle body, the collision load can be absorbed by the side sill. Thus, it becomes possible to optimize the strength of the side frame and the strength of the members near the rear end portion of the side frame.

[0012] Further, when the side frame and the frame member are provided at the rear part of the vehicle body, since the collision load at the time of rear-end collision is transmitted to the side sill through a plurality of routes, the amount of absorption of the collision load on the side sill can be increased in the same manner as in the case of a frontal collision. Therefore, it becomes possible to optimize the strength of each member constituting the vehicle body.

[0013] In a second aspect of the present disclosure, a portion on the side sill side in the floor reinforcement and a portion on the battery case side in the outer connection portion are positioned so as to overlap each other in plan view.

[0014] That is, since the portion on the side sill side in the floor reinforcement is a portion connected to the side sill, it is arranged so as to be adjacent to the side sill. On the other hand, since the outer connection portion is a member connected to the battery case, it will be separated from the side sill. However, in plan view, the fact that the portion on the battery case side in the outer connection portion overlaps the portion on the side sill side in the floor reinforcement means that the portion on the battery case side in the outer connection portion can be brought closer to the side sill. Therefore, the collision load can be surely applied toward the side sill side through the outer connection portion.

[0015] In a third aspect of the present disclosure, an inner reinforcement extending in the vehicle front-rear direction is provided inside the side sill.

[0016] According to this configuration, since the rigidity of the side sill is further increased, the absorption effect of the collision load transmitted from both the floor reinforcement and the outer connection portion on the side sill is further increased.

[0017] In a fourth aspect of the present disclosure, an inner connection portion is provided that extends from a mid-portion in the vehicle front-rear direction of the frame member toward the center in the vehicle width direction of the battery case and is connected to the battery case. A center member extending in the vehicle front-rear direction is provided at the center in the vehicle width direction of the battery case.

[0018] According to this configuration, the collision load input to the frame member is transmitted to and absorbed by the battery case because the inner connection portion is connected to the battery case. Since the inner connection portion extends toward the center in the vehicle width direction of the battery case, the collision load is transmitted to the central portion in the vehicle width direction of the battery case or the vicinity thereof. At this time, since there is a center member extending in the vehicle front-rear direction at the center in the vehicle width direction of the battery case, the collision load can also be absorbed by the center member.

[0019] In a fifth aspect of the present disclosure, the frame member is disposed on the inner side in the vehicle width direction than the side frame.

[0020] According to this configuration, the collision load is transmitted to the side sill through a plurality of routes via the side frame located relatively on the outer side in the vehicle width direction and the frame member located on the inner side in the vehicle width direction, respectively.

[0021] In a sixth aspect of the present disclosure, a pair of left and right hinge pillars extending upward from the pair of left and right side sills are provided. The portion on the side sill side in the floor reinforcement and the base end portion of the hinge pillar are arranged at the same position in the vehicle front-rear direction.

[0022] That is, the vicinity of the base end portion of the hinge pillar in the side sill is a portion having particularly high rigidity, and by connecting the floor reinforcement to this portion having particularly high rigidity, the collision load can be efficiently absorbed by the side sill.

[0023] In a seventh aspect of the present disclosure, the floor reinforcement is formed to extend in the vehicle front-rear direction along the upper surface of the floor panel, and is attached to the upper surface of the floor panel to form a closed cross-section together with the floor panel.

[0024] According to this configuration, the reinforcing effect by the floor reinforcement is further enhanced, and the collision load can be reliably transmitted to the side sill.

Effects of the Invention

[0025] As described above, since the floor reinforcement that transmits the load from the side frame to the side sill, the frame member that extends in the front-rear direction from the battery case, and the outer connection portion that extends from the mid portion in the front-rear direction of the frame member toward the side sill are provided, the collision load can be dispersed and transmitted to the side sill and the battery case of the vehicle body. Thereby, the strength of each member constituting the vehicle body can be optimized to achieve weight reduction of the entire vehicle.

Brief Description of the Drawings

[0026]

Figure 1

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Figure 14

Embodiments for Carrying Out the Invention

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

[0028] FIG. 1 is a left side view of an electric vehicle 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 includes a lower structure body 2 and an upper structure body 3, and the vehicle body structure A is constituted by the lower structure body 2 and the upper structure body 3. FIG. 2 shows a state in which doors, a bonnet, front fenders, a windshield, bumpers, front and rear lighting devices, etc. are removed. In the description of this embodiment, the front side of the vehicle is simply referred to as "front", the rear side of the vehicle is simply referred to as "rear", the right side of the vehicle is simply referred to as "right", and the left side of the vehicle is simply referred to as "left". The left - right direction of the vehicle is the vehicle width direction.

[0029] As shown in Fig. 1, the electric vehicle 1 is a passenger car. As shown in Fig. 2, a front seat S1 is provided at the front side in the passenger compartment R1 which is the living space for the passengers, and a rear seat S2 is provided behind the front seat S1 in the passenger compartment R1. A luggage compartment R2 is provided behind the rear seat S2 as required. The passenger compartment R1 and the luggage compartment R2 are provided in the upper structure 3. Note that only the front seat S1 may be provided in the passenger compartment R, or a third-row seat (not shown) may be provided behind the rear seat S2.

[0030] On the other hand, the space in front of the passenger compartment R1 which is the front part of the electric vehicle 1 can be, for example, a power compartment R3. That is, the vehicle body structure A includes a traveling motor M that generates power for driving the drive wheels, and a battery case 10 that houses a battery B (shown only in Fig. 4) for supplying power to the traveling motor M. Only the traveling motor M, or the power train PT is constituted by the traveling motor M and a speed reducer, a transmission, etc. Figs. 1 and 2 show the case where the power train PT is provided only in the power compartment R3, but the power train PT may be provided in the lower space R4 below the luggage compartment R2 (the rear power train is not shown). When the power train PT is provided only in the power compartment R3, only the front wheels F are driven. When the power train PT is provided in the lower space R4, only the rear wheels R are driven. In this case, the power compartment R3 can be used as a luggage space or the like. Also, when the power train PT is provided in both the power compartment R3 and the lower space R4, it becomes a four-wheel drive vehicle. The battery case 10 is disposed below the floor panel 70 described later.

[0031] As shown in Figs. 3 and 4, the lower structure 2 includes the battery case 10, a front frame member 11 that extends forward in front of the battery case 10, and a rear frame member 12 that extends rearward behind the battery case 10. In Fig. 3, the left front wheel F, rear wheel R, suspension arm, etc. are omitted.

[0032] In the case of a general electric vehicle, the battery case is often made detachable under the floor as a separate body from the vehicle body. However, in this embodiment, not only the battery case 10, but also the front frame member 11 and the rear frame member 12 are integrated with the battery case 10, and the front frame member 11 and the rear frame member 12 are also detachable from the upper structure 3 together with the battery case 10.

[0033] Specifically, the electric vehicle 1 of this embodiment is configured to be vertically divisible into a lower structure 2 having a battery case 10 and an upper structure 3 forming a passenger compartment R1 and a cargo compartment R2. Being vertically divisible means integrating the lower structure 2 with the upper structure 3 by using fastening members such as bolts, nuts, and screws without using welding, adhesion, etc. Thereby, when performing maintenance or repair after the electric vehicle 1 is delivered to the user, the lower structure 2 can be separated from the upper structure 3 as necessary, so that the maintainability is improved.

[0034] Here, as a vehicle body structure of an automobile, a ladder frame type vehicle body structure is known. In the case of a ladder frame type vehicle body structure, it is vertically divisible into a ladder frame and a cabin. However, since the ladder frame extends continuously in the front-rear direction, it mainly receives a collision load during a front collision and a rear collision. During a side collision, the ladder frame only receives the collision load supplementarily, and the cabin mainly receives the collision load. Thus, in a ladder frame type vehicle body structure, it is normal that the members receiving the collision load are separated between during a front collision and a rear collision and during a side collision.

[0035] On the other hand, in the case of the electric vehicle 1 of the present embodiment, the lower structure 2 having the frame members 11 and 12 and the upper structure 3 are separable. However, in both the case of a frontal collision and a rear collision, and in the case of a side collision, by receiving the collision load by the lower structure 2 and the upper structure 3, the collision load can be dispersed and absorbed by the two structures 2 and 3. In this respect, the technical idea is greatly different from that of the conventional ladder frame type vehicle body structure. Hereinafter, the structures of the lower structure 2 and the upper structure 3 and the effects will be described in order.

[0036] (Lower Structure) First, the lower structure 2 will be described. As shown in FIGS. 3 and 4, in addition to the battery case 10, the front frame 11, and the rear frame 12, the lower structure 2 also includes a power train PT, front wheels F, rear wheels R, a front suspension device 13, and a rear suspension device 14. The types of the front suspension device 13 and the rear suspension device 14 are not particularly limited.

[0037] The battery case 10 is a large case formed so as to extend from the vicinity of the left end portion to the vicinity of the right end portion of the floor panel 70 and from the vicinity of the front end portion to the vicinity of the rear end portion of the floor panel 70 below the floor panel 70 described later. By providing the battery case 10 in a wide range of the lower region of the floor panel 70 in this way, it becomes possible to mount a large-capacity battery B on the electric vehicle 1 as shown in FIG. 4. The battery B may be, for example, a lithium ion battery, a all-solid-state battery, or other secondary battery. Further, the battery B may be a so-called battery cell or a battery pack containing a plurality of battery cells.

[0038] The battery case 10 includes a left side member 20, a right side member 21, a front end member 22, a rear end member 23, and a bottom plate 24. The left side member 20, the right side member 21, the front end member 22, and the rear end member 23 are made of, for example, an extruded material made of an aluminum alloy, but may also be made of an aluminum alloy plate or a press-formed material of a steel plate. The bottom plate 24 can also be made of an extruded material. In the following description, the "extruded material" refers to an extruded material made of an aluminum alloy, and the "press-formed material" refers to an aluminum alloy plate or a press-formed material of a steel plate. Also, each member may be made of, for example, a casting.

[0039] The cross-sectional shapes in the direction orthogonal to the longitudinal direction of each of the left side member 20, the right side member 21, the front end member 22, and the rear end member 23 are all rectangular. Also, the left side member 20, the right side member 21, the front end member 22, and the rear end member 23 are all arranged at the same height and extend substantially horizontally.

[0040] The left side member 20 is provided at the left end of the battery case 1 and extends in the front-rear direction. The right side member 21 is provided at the right end of the battery case 1 and extends in the front-rear direction. Also, the front end member 22 is provided at the front end of the battery case 1 and extends in the left-right direction. The left end of the front end member 22 is connected to the front end of the left side member 20, and the right end of the front end member 22 is connected to the front end of the right side member 21. The rear end member 23 is provided at the rear end of the battery case 1 and extends in the left-right direction. The left end of the rear end member 23 is connected to the rear end of the left side member 20, and the right end of the rear end member 23 is connected to the rear end of the right side member 21. The bottom plate 24 extends substantially horizontally and is fixed to the lower surfaces of the left side member 20, the right side member 21, the front end member 22, and the rear end member 23. Therefore, a battery accommodation space S (shown in FIG. 3) for accommodating the battery B is partitioned and formed by the left side member 20, the right side member 21, the front end member 22, the rear end member 23, and the bottom plate 24.

[0041] The size of the battery accommodation space S can be changed according to the capacity of the mounted battery B. The size of the battery accommodation space S can be easily changed by changing the lengths of the left side member 20, the right side member 21, the front end member 22, and the rear end member 23 and the shape of the bottom plate 24. For example, when the vehicle is a small car with a short wheelbase and a narrow tread, the left side member 20, the right side member 21, the front end member 22, and the rear end member 23 are shortened, and accordingly, the shape of the bottom plate 24 is made smaller, so that the battery accommodation space S becomes smaller according to the small car (see Fig. 5). On the other hand, in the case of a large vehicle, the left side member 20, the right side member 21, the front end member 22, and the rear end member 23 are lengthened, and accordingly, the shape of the bottom plate 24 is made larger, so that the battery accommodation space S becomes larger according to the large vehicle. When the left side member 20, the right side member 21, the front end member 22, and the rear end member 23 are made of extruded materials, the length can be easily changed. Also, the bottom plate 24 can be made of an extruded material, whereby the shape can be easily changed.

[0042] The upper part of the battery accommodation space S may be closed by a lid body (not shown) or may be closed by a floor panel 70 described later. In the battery accommodation space S, in addition to the battery B, a cooling device for cooling the battery B, a heating device for heating the battery B, etc. (temperature control device) can also be provided. Also, the power of the battery B is supplied to the traveling motor M via a control device (not shown). Further, the battery B can be charged via a charging socket (not shown).

[0043] As shown in FIG. 3, inside the battery case 10, first to third battery-side cross members 25A, 25B, and 25C are provided as reinforcing members extending in the left-right direction. The heights of the first to third battery-side cross members 25A, 25B, and 25C are all the same and are substantially the same as the height of the left-side member 20 or the like. The battery-side cross members 25A, 25B, and 25C may be formed of an extruded material or a press-formed material. In this embodiment, three battery-side cross members 25A, 25B, and 25C are provided, but the number of the battery-side cross members 25A, 25B, and 25C can be increased or decreased according to the dimension of the battery case 10 in the front-rear direction.

[0044] The first to third battery-side cross members 25A, 25B, and 25C are arranged at intervals in the front-rear direction. The first battery-side cross member 25A is positioned at the frontmost, and the third battery-side cross member 25C is positioned at the rearmost. The lower portions of the respective battery-side cross members 25A, 25B, and 25C are fixed to the upper surface of the bottom plate 24. Also, the left end portions of the respective battery-side cross members 25A, 25B, and 25C are fixed to the inner surface (right side surface) of the left-side member 20, and the right end portions of the respective battery-side cross members 25A, 25B, and 25C are fixed to the inner surface (left side surface) of the right-side member 21. That is, the battery-side cross members 25A, 25B, and 25C are members that connect the left-side member 20 and the right-side member 21.

[0045] FIG. 5 above shows an example of the lower structure 2 provided with a small-sized battery case 10 whose dimension in the front-rear direction is set shorter than that of the battery case 10 shown in FIG. 4. In the example shown in this FIG. 5, the third battery-side cross member 25C is omitted due to the shortening of the dimension in the front-rear direction. Conversely, although not shown, a fourth battery-side cross member can also be provided.

[0046] Inside the battery case 10, as a reinforcing member extending in the front-rear direction, a front center member (front reinforcing member) 26 and first to third rear center members (rear reinforcing members) 27 to 29 are provided. The front center member 26 and the first to third rear center members 27 to 29 are arranged at substantially the same height and are provided at the center in the left-right direction of the battery case 10. The lower end portions of the front center member 26 and the first to third rear center members 27 to 29 are attached to the upper surface of the bottom plate 24.

[0047] The front center member 26 is disposed between the front end member 22 and the first battery side cross member 25A. The front end portion of the front center member 26 is fixed to the center in the left-right direction of the front end member 22, and the rear end portion of the front center member 26 is fixed to the center in the left-right direction of the first battery side cross member 25A. Therefore, the front end member 22 is a member that extends so as to connect the front end portions of the left side member 20 and the right side member 21 and the front end portion of the front center member 26.

[0048] The first rear center member 27 is disposed between the first battery-side cross member 25A and the second battery-side cross member 25B. The front end portion of the first rear center member 27 is fixed to the center portion in the left-right direction of the first battery-side cross member 25A, and the rear end portion of the first rear center member 27 is fixed to the center portion in the left-right direction of the second battery-side cross member 25B. Further, the second rear center member 28 is disposed between the second battery-side cross member 25B and the third battery-side cross member 25C. The front end portion of the second rear center member 28 is fixed to the center portion in the left-right direction of the second battery-side cross member 25B, and the rear end portion of the second rear center member 28 is fixed to the center portion in the left-right direction of the third battery-side cross member 25C. Further, the third rear center member 29 is disposed between the third battery-side cross member 25C and the rear end member 23. The front end portion of the third rear center member 29 is fixed to the center portion in the left-right direction of the third battery-side cross member 25C, and the rear end portion of the third rear center member 29 is fixed to the center portion in the left-right direction of the rear end member 23. Therefore, the first to third battery-side cross members 25A, 25B, 25C, the front center member 26, and the first to third rear center members 27 to 29 are arranged in a lattice pattern and connected to each other inside the battery case 10, so that the reinforcing effect of the battery case 10 is further enhanced.

[0049] When a virtual straight line extending in the front-rear direction is assumed in a plan view, the front center member 26 and the first to third rear center members 27 to 29 are set such that their respective left-right positions are arranged on the virtual straight line. That is, the first to third rear center members 27 to 29 are provided so as to be positioned on the virtual extension line rearward of the front center member 26. Incidentally, the front center member 26 and the first to third rear center members 27 to 29 may be constituted by a single member continuous in the front-rear direction.

[0050] FIG. 6 is a diagram showing an example in which the height of the front center member 26 is made higher than the heights of the first to third rear center members 27 to 29 (not shown in FIG. 6). Although details will be described later, in the floor panel 70 of the upper structure 3, the front floor portion 70a is located above the rear floor portion 70b. The front center member 26 is provided below the front floor portion 70a, and the first to third rear center members 27 to 29 are provided below the rear floor portion 70b. The upper end portion of the front center member 26 is formed so as to be located above the rear floor portion 70b. In other words, the upper end portions of the first to third rear center members 27 to 29 are located below the upper end portion of the front center member 26 so as to correspond to the relatively low rear floor portion 70b. At this time, the first battery side cross member 25A may be provided below the front floor portion 70a, and in this case, the upper end portion of the first battery side cross member 25A can be formed so as to be located above the second and third battery side cross members 25B and 25C.

[0051] As shown in FIGS. 3 and 4, a pair of left and right front frame members 11 are provided, and extend linearly substantially horizontally below the left and right front side frames 72 described later. Each front frame member 11 can be composed of, for example, an extruded material or a press-formed material. In this embodiment, since each front frame member 11 is composed of an extruded material, the cross-sectional shape in the direction orthogonal to the front-rear direction is substantially equal from the front end portion to the rear end portion.

[0052] The left front frame member 11 is connected to a position leftward of the center in the left-right direction of the front end member 22 that constitutes the front portion of the battery case 10, and this connection position is located on the right side of the left side member 20 of the battery case 10. Also, the right front frame member 11 is connected to a position rightward of the center in the left-right direction of the front end member 22, and this connection position is located on the left side of the right side member 21 of the battery case 10. As a result, the interval between the left and right front frame members 11 becomes a predetermined interval, and it becomes possible to arrange the lower portion of the power train PT between the left and right front frame members 11. The interval between the left and right front frame members 11 is set to be narrower than the interval between the left side member 20 and the right side member 21 of the battery case 10.

[0053] The heights of the left and right front frame members 11 are substantially the same. Also, the left and right front frame members 11, the front center member 26, the left side member 20, and the right side member 21 of the battery case 10 are arranged at substantially the same height.

[0054] The side (rear side) of each front frame member 11 on the battery case 10 side is connected at a plurality of positions spaced apart from each other in the left-right direction with respect to the battery case 10. Specifically, the rear end portion of the right front frame member 11 is connected to the front end member 22, and further, a portion farther forward than the rear end portion of the front frame member 11 is connected to the front end member 22 by the outer connection portion (one connection portion) 30 and the inner connection portion (the other connection portion) 31. Thereby, the collision load input to the front frame member 11 during a frontal collision can be dispersed and transmitted to a plurality of locations of the battery case 10.

[0055] The outer connection part 30 and the inner connection part 31 are composed of highly rigid members made of, for example, extruded materials or press-formed materials, and have a cylindrical shape, a plate shape, or a columnar shape. In plan view, the widths of the outer connection part 30 and the inner connection part 31 are set wider than the width of the front frame member 11, thereby further enhancing the dispersion effect of the above-mentioned collision load. Incidentally, the widths of the outer connection part 30 and the inner connection part 31 may be the same as the width of the front frame member 11, or may be made narrower than the width of the front frame member 11.

[0056] The right outer connection part 30 is provided at substantially the same height as the front frame member 11 on the right side (outer side in the vehicle width direction) of the right front frame member 11, and is inclined in the front-rear direction in plan view so as to be positioned more to the right as it approaches the rear end. The front end of the right outer connection part 30 is connected to a part (midway part in the front-rear direction) between the center in the front-rear direction and the rear end in the front frame member 11. The outer connection part 30 extends from the connection part with the front frame member 11 to the right and rear, that is, toward the side sill 73 (described later) of the upper structure 3. And the rear end of the right outer connection part 30 is connected to a part spaced rightward from the rear end of the front frame member 11 in the front end member 22. The connection structure between the outer connection part 30 and the front frame member 11, and the connection structure between the outer connection part 30 and the front end member 22 may be a connection structure using fastening members such as bolts and nuts, or may be a connection structure using welding, adhesion, or the like.

[0057] The right inner connection part 31 is provided at substantially the same height as the front frame member 11 on the left side (inner side in the vehicle width direction) of the right front frame member 11, and is inclined in the front-rear direction in plan view so as to be positioned more to the left as it approaches the rear end part. The front end part of the right inner connection part 31 is connected to a part (midway part in the front-rear direction) between the center in the front-rear direction and the rear end part of the front frame member 11. The right inner connection part 31 extends from the connection part with the front frame member 11 toward the left and rear, that is, toward the center in the left-right direction of the battery case 10. Then, the rear end part of the inner connection part 31 is connected to a part spaced leftward from the rear end part of the front frame member 11 in the front end member 22. The connection structure between the inner connection part 31 and the front frame member 11 and the connection structure between the inner connection part 31 and the front end member 22 can be the same as the connection structure of the outer connection part 30.

[0058] In this embodiment, the right front frame member 11 is connected to the front end member 22 at three locations spaced apart from each other in the left-right direction, but the present invention is not limited to this. One of the outer connection part 30 and the inner connection part 31 may be omitted and the connection may be made at two locations, or the front end member 22 may be connected only by the outer connection part 30 and the inner connection part 31 without connecting the rear end part of the front frame member 11 to the front end member 22.

[0059] In addition, the left front frame member 11 can also be connected to the front end member 22 in the same manner as the right front frame member 11. The connection structure of the left front frame member 11 can be a left-right symmetric structure with respect to that of the right front frame member 11.

[0060] As shown in FIG. 3, in front of the battery case 10 of the lower structure 2, an intermediate connecting member 49, a front connecting member 50, and a rear connecting member 51 are provided at intervals in the front-rear direction. The front connecting member 50 extends in the vehicle width direction from the front part of the left front frame member 11 to the front part of the right front frame member 11, and is a member that connects the left front frame member 11 and the right front frame member 11. Further, the rear connecting member 51 extends in the vehicle width direction from the rear part of the left front frame member 11 to the rear part of the right front frame member 11, and is a member that connects the left front frame member 11 and the right front frame member 11. The front connecting member 50 and the rear connecting member 51 are composed of, for example, extruded materials, press-formed materials, etc. By connecting the left and right front frame members 11 with the front connecting member 50 and the rear connecting member 51, a frame structure in the shape of a frame is formed in plan view.

[0061] Also, the intermediate connecting member 49 is provided between the front connecting member 50 and the rear connecting member 51, extends in the vehicle width direction from the front part of the left front frame member 11 to the front part of the right front frame member 11, and is a member that connects the left front frame member 11 and the right front frame member 11. The intermediate connecting member 49 may be provided as necessary and may be omitted.

[0062] The front connecting member 50 extends from the upper surface of the left front frame member 11 to the upper surface of the right front frame member 11 and is disposed so as to protrude upward from the upper surfaces of both front frame members 11. On the other hand, the rear connecting member 51 is disposed between the left and right front frame members 11, the left end portion of the rear connecting member 51 is connected to the side surface of the left front frame member 11, and the right end portion of the rear connecting member 51 is connected to the side surface of the right front frame member 11. The front connecting member 50 and the rear connecting member 51 may be fixed to the front frame member 11 by fastening members, or may be fixed by welding, adhesion, etc.

[0063] The front-rear dimensions of the front connecting member 50 and the rear connecting member 51 are set to be longer than the left-right dimension of the front frame member 11. Thereby, the connection strength of the front frame member 11 by both connecting members 50 and 51 can be enhanced.

[0064] As shown in FIG. 4, the power train PT is disposed rearward of the front connecting member 50. Specifically, in a plan view, the power train PT is disposed between the front connecting member 50 and the rear connecting member 51. The lower structure 2 is provided with drive shafts 52 on the left and right for respectively transmitting the output of the power train PT to the left and right front wheels F.

[0065] Also, the left and right suspension arms 13a that form part of the front suspension device 13 are swingably supported on the left and right front frame members 11 via brackets 13b. The brackets 13b are provided at the connection sites between the left and right front frame members 11 and the rear connecting member 51.

[0066] The lower structure 2 is provided with two left connecting portions 53 and 54 that connect the left front frame member 11 to a left front side frame 72 (described later) at intervals in the front-rear direction, and two right connecting portions 55 and 56 that connect the right front frame member 11 to a right front side frame 72 (described later) at intervals in the front-rear direction. The left connecting portions 53 and 54 and the right connecting portions 55 and 56 can be formed of plate materials, cylindrical members, columnar members, etc. that extend in the vertical direction. In this embodiment, the left connecting portions 53 and 54 and the right connecting portions 55 and 56 are formed of press-formed materials, but they may be formed of extruded materials or the like. Also, the number of the left connecting portions 53 and 54 is not limited to two, and three or more may be provided at intervals in the front-rear direction. The same applies to the right connecting portions 55 and 56.

[0067] The previous left connecting portion 53 is provided at the connection site of the front connecting member 50 with the left front frame member 11. Specifically, the front portion of the left front frame member 11 and the left end portion of the front connecting member 50 are arranged overlapping in the vertical direction, and since the left end portion of the front connecting member 50 is connected to the front portion of the left front frame member 11, the connection site is constituted by the left end portion of the front connecting member 50. The lower end portion of the previous left connecting portion 53 is attached to the left end portion of this front connecting member 50.

[0068] Also, the previous right connecting portion 55 is provided at the connection site of the front connecting member 50 with the right front frame member 11. Specifically, the front portion of the right front frame member 11 and the right end portion of the front connecting member 50 are arranged overlapping in the vertical direction, and since the right end portion of the front connecting member 50 is connected to the front portion of the right front frame member 11, the connection site is constituted by the right end portion of the front connecting member 50. The lower end portion of the previous right connecting portion 55 is attached to the right end portion of this front connecting member 50.

[0069] The rear left connecting portion 54 is provided at the connection site of the left front frame member 11 with the intermediate connecting member 49. The lower end portion of the rear left connecting portion 54 is attached to the left front frame member 11 and is arranged on the rear side of the left drive shaft 52. Also, the rear right connecting portion 56 is provided at the connection site of the right front frame member 11 with the intermediate connecting member 49. The lower end portion of the rear right connecting portion 56 is attached to the right front frame member 11 and is arranged on the rear side of the right drive shaft 52. Thereby, the intervals between the front and rear left connecting portions 53, 54 and the intervals between the front and rear right connecting portions 55, 56 can be widened.

[0070] The right front frame member 11 is disposed on the left side (inside in the vehicle width direction) of the right front side frame 72 shown in FIG. 8, and the left front frame member 11 is disposed on the right side (inside in the vehicle width direction) of the left front side frame 72 shown in FIG. 2. As a result, the interval between the left and right front side frames 72 becomes wider than the interval between the left and right front frame members 11. A power train PT including a traveling motor M is mounted between the left and right front side frames 72.

[0071] As shown in FIG. 3, the right connection portions 55 and 56 are formed so as to be located on the right side (outside in the vehicle width direction) as they go upward. This is because the right front side frame 72 is positioned on the right side of the front frame member 11 above the front frame member 11. Similarly, the left connection portions 53 and 54 are formed so as to be located on the left side (outside in the vehicle width direction) as they go upward.

[0072] A pair of left and right rear frame members 12 are provided in the same manner as the front frame members 11, and extend linearly rearward in a substantially horizontal manner. Each rear frame member 12 can be formed of, for example, an extruded material or a press-formed material. In this embodiment, each rear frame member 12 is formed of an extruded material.

[0073] The left rear frame member 12 is connected to a portion closer to the left than the center in the left-right direction of the rear end member 23 that constitutes the rear portion of the battery case 10, and this connection portion is located on the right side of the left side member 20 of the battery case 10. Further, the right rear frame member 12 is connected to a portion closer to the right than the center in the left-right direction of the rear end member 23, and this connection portion is located on the left side of the right side member 21 of the battery case 10. The connection structure of the rear frame member 12 to the rear end member 23 can be the same as the connection structure of the front frame member 11 to the front end member 22 described above.

[0074] Also, in the form shown in FIG. 5, the front ends of the left and right rear frame members 12 are connected to the rear end member 23, and the intermediate portion in the front-rear direction of the rear frame member 12 is connected to the rear end member 23 by the connecting member 60. As a result, the side of the rear frame member 12 on the battery case 10 side is connected to the battery case 10 at a plurality of positions spaced apart from each other in the left-right direction.

[0075] The left and right suspension arms 14a that form part of the rear suspension device 14 are swingably supported on the left and right rear frame members 12 via brackets 14b, respectively.

[0076] (Upper structure) Next, the upper structure 3 will be described. As shown in FIGS. 7 to 10, the upper structure 3 includes a floor panel 70, a dash panel 71, a pair of left and right front side frames 72, and a pair of left and right side sills 73. FIGS. 7 to 10 show a state in which the doors, bonnet hood, front fenders, windshield, bumpers, front and rear lighting devices, some seats, interior materials, etc. are removed.

[0077] The floor panel 70 constitutes the floor surface of the passenger compartment R1 and is made of a steel plate or the like that extends in the front-rear direction and also in the left-right direction. The space above the floor panel 70 is the passenger compartment R1. A roof 80 is provided above the passenger compartment R1. Also, as shown in FIG. 2, a front opening 3a and a rear opening 3b are formed in the left side portion 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 the front door 81 and the rear door 82, respectively. Although not shown, a front door and a rear door are also disposed on the right side of the upper structure 3 so as to be openable and closable.

[0078] The dash panel 71 is a member for partitioning the passenger compartment R1 and the power compartment R3 in the front-rear direction. This dash panel 71 is composed of, for example, a steel plate or the like, and extends in the left-right direction and also in the up-down direction. As shown in FIGS. 7 to 9, on both the left and right sides of the front part of the upper structure body 3, there are provided front wheel house parts 85 (only the right side one is shown in FIGS. 7 to 9) for accommodating the left and right front wheels F respectively. The left end portion of the dash panel 71 is connected to the left front wheel house part 85 (shown in FIG. 2), and the right end portion of the dash panel 71 is connected to the right front wheel house part 85 (shown in FIGS. 7 to 9).

[0079] As schematically shown in FIG. 11, the floor panel 70 includes a front floor portion 70a and a rear floor portion 70b. Further, as shown in FIG. 10, the floor panel 70 also includes a kick-up portion 70c at its rear part. The front floor portion 70a, the rear floor portion 70b, and the kick-up portion 70c may be integrally formed with a single plate material, or may be formed with separate plate materials. When formed with separate plate materials, a single floor panel 70 can be constituted by joining a plurality of plate materials.

[0080] As shown in FIG. 11, the front floor portion 70a constitutes the front side portion of the floor panel 70, and is inclined or curved so as to be positioned higher toward the front side. The front end portion of the front floor portion 70a is connected to the lower end portion of the dash panel 71. Therefore, the floor panel 70 is provided so as to extend rearward from the lower end portion of the dash panel 71.

[0081] The rear floor portion 70b is formed to extend rearward from the rear end portion of the front floor portion 70a, and constitutes the middle portion in the front-rear direction of the floor panel 70. The front portion of the battery case 10 of the lower structure 2 is located directly below the front floor portion 70a, and the rear portion of the battery case 10 is located directly below the rear floor portion 70b. Therefore, the battery case 10 is formed to reach from below the front floor portion 70a to below the rear floor portion 70b, whereby the battery B can be mounted in most of the area under the floor panel 70.

[0082] The middle portion in the front-rear direction of the floor panel 70 is lower than the front floor portion 70a. That is, the front floor portion 70a is provided in front of the rear floor portion 70b and is located above the rear floor portion 70b. At least a part of the seat fixing portion 100 for fixing the front seat S1 is attached to the front side portion of the rear floor portion 70b. The seat fixing portion 100 is composed of, for example, a bracket or the like. It is sufficient that at least the rear portion of the seat fixing portion 100 is attached to the rear floor portion 70b, and all of the seat fixing portion 100 may be attached to the rear floor portion 70b. By attaching at least the rear portion of the seat fixing portion 100 to the rear floor portion 70b, the front seat S1 can be laid out lower, so that the hip point of the front seat occupant P can be lowered. As a result, a margin is created in the overhead space of the front seat occupant P, and the habitability is improved. Also, the fact that the hip point is lowered means that the seating position of the front seat occupant P is lowered, whereby the center of gravity height of the vehicle in the driving state is lowered. In this embodiment, since all of the seat fixing portion 100 is attached to the rear floor portion 70b, the front seat S1 can be laid out even lower.

[0083] When the driver as the front-seat passenger P sits on the front seat S1, the heel P1 of the front-seat passenger P will be placed on the front floor part 70a. Since the front floor part 70a where the heel P1 is placed is positioned higher than the rear floor part 70b, the heel P1 will be placed at a higher position compared to the operating posture of a general automobile (an automobile with the same height of the front floor part and the rear floor part). With such a layout, the upper thigh P2 and the lower leg P3 of the front-seat passenger P will be in a posture where they are widely opened. In FIG. 11, reference numeral 101 indicates the center line of the upper thigh P2, and reference numeral 102 indicates the center line of the lower leg P3. The height difference between the front floor part 70a and the rear floor part 70b is set so that the angle formed by the center line 101 and the center line 102 (the opening angle α between the upper thigh P2 and the lower leg P3) is in the range of 125° to 150°.

[0084] By setting the height difference in this way, the angle formed by the lower leg P3 and the front floor part 70a (the angle β formed by the center line 101 and the front floor part 70a) becomes smaller. Therefore, the vertical component force input to the heel P1 during pedal operation becomes smaller, and the operability of the brake pedal 103 is improved. Specifically, when the front-seat passenger P steps on the brake pedal 103, the heel P1 applies an obliquely downward force F to the front floor part 70a. When this force F is divided into a vertical force and a horizontal force, they become force F1 and force F2 respectively. As described above, since the angle β is smaller, the vertical component force F1 input from the heel P1 becomes smaller. As a result, for example, the operation of switching from the brake pedal 103 to the accelerator pedal (not shown) or the reverse switching operation can be performed quickly and accurately, and thus the operability of the pedal is improved.

[0085] Also, the feet of the rear-seat passengers may be placed on the rear floor part 70b. Since the rear floor part 70b is lower than the front floor part 70a, the foot space for the rear-seat passengers is enlarged, and the habitability of the rear-seat passengers is also improved.

[0086] As shown in FIGS. 7 to 9, the kick-up portion 70c constitutes the rear portion of the floor panel 70 and is connected to the rear end of the rear floor portion 70b. The kick-up portion 70c is located above the rear floor portion 70b, and a vertical plate portion 70d extending in the vertical direction is formed between the kick-up portion 70c and the rear floor portion 70b. The height of the kick-up portion 70c is set higher than that of the front floor portion 70a. The rear seat sheet S2 (shown in FIG. 2) is attached to the upper surface of the kick-up portion 70c. Under the kick-up portion 70c, the battery B may be disposed, or a control device (not shown) of the electric vehicle 1 or the like may be disposed.

[0087] A floor side cross member 110 extending in the left-right direction along the floor panel 70 is attached to the floor panel 70. The floor side cross member 110 is, for example, welded to the upper surface of the rear floor portion 70b of the floor panel 70. The shape of the floor side cross member 110 is not particularly limited, but in the present embodiment, it bulges upward and is open downward, and has substantially the same cross-sectional shape over both left and right ends in the left-right direction. By attaching the floor side cross member 110 to the rear floor portion 70b, a closed cross-section is formed by the floor side cross member 110 and the rear floor portion 70b. The left end portion of the floor side cross member 110 is located near the inner surface in the vehicle width direction of the left side sill 73, and the right end portion of the floor side cross member 110 is located near the inner surface in the vehicle width direction of the right side sill 73. Incidentally, the floor side cross member 110 may be attached to the lower surface of the rear floor portion 70b.

[0088] As shown in FIGS. 7 to 9, the left and right front side frames 72 are disposed at the front part of the vehicle body and are high-strength members extending in the front-rear direction. In FIGS. 7 to 9, only the right front side frame 72 is shown, and in FIG. 2, the left front side frame 72 is shown. That is, the left and right front side frames 72 are positioned in front of the floor panel 70 and above the floor panel 70, and specifically, they are disposed so as to extend forward from both left and right sides at the lower part of the dash panel 71.

[0089] The left and right front side frames 72 have a symmetrical structure and can be configured, for example, by joining a plurality of press-formed materials or by using an extruded material. The cross-section of each front side frame 72 in the direction orthogonal to the front-rear direction is set to be larger than the cross-section of the front frame member 11 of the lower structure body 2 in the same direction. As a result, each front side frame 72 becomes a thicker and higher-strength member than the front frame member 11.

[0090] The front end portions of the left and right front side frames 72 each have a crush can 72a that compresses and deforms during a frontal collision to absorb collision energy. The crush can 72a is a cylindrical metal member extending in the front-rear direction. A front bumper reinforcement 86 extending in the left-right direction is fixed to the front end portions of the left and right crush cans 72a.

[0091] As shown in FIG. 8, the upper part of the right connecting portion 55 located in front of the lower structure 2 is connected to the right crash can 72a. Also, the upper part of the left connecting portion 53 (shown in FIG. 2) located in front of the lower structure 2 is connected to the left crash can 72a. Since the crash can 72a is at the front end of the front side frame 72, by connecting the upper part of the left connecting portion 53 to the crash can 72a, the connecting portion of the left connecting portion 53 can be set at a position closer to the front end of the vehicle body. As a result, the distance in the front-rear direction between the left connecting portions 53 and 54 can be widened, so that the effect of connecting the front frame member 11 to the front side frame 72 by the left connecting portions 53 and 54 becomes even more remarkable. The same applies to the right connecting portions 55 and 56. The connection structure of the left connecting portions 53 and 54 and the right connecting portions 55 and 56 to the front side frame 72 is, for example, a structure using fastening members such as bolts and nuts. Incidentally, the previous left connecting portion 53 and right connecting portion 55 may be connected to a position behind the crash can 72a in the front side frame 72.

[0092] Also, as shown in FIG. 5, the lower part of the rear right connecting portion 56 is connected to the front frame member 11 behind the drive shaft 52, and as shown in FIG. 8, the upper part of the rear right connecting portion 56 is connected to a position behind the center in the front-rear direction of the front side frame 72. As a result, the distance in the front-rear direction between the right connecting portions 55 and 56 can be further widened. The same applies to the left connecting portions 53 and 54.

[0093] The left and right side sills 73 are disposed at both left and right ends of the floor panel 70 so as to extend in the front-rear direction. As shown in FIG. 12, the left end of the floor panel 70 is connected to the middle portion in the vertical direction of the left side sill 73. The upper portion of the side sill 73 protrudes upward from the connection portion of the floor panel 70, and the lower portion of the side sill 73 protrudes downward from the connection portion of the floor panel 70. Since the battery case 10 is disposed below the floor panel 70, in a side view of the vehicle, the lower portion of the side sill 73 and the battery case 10 are arranged so as to overlap. Also, the right side sill 73 is similarly connected to the right end of the floor panel 70.

[0094] The left and right side sills 73 have a symmetric structure. Hereinafter, based on FIG. 12, the detailed structure of the left side sill 73 will be described. The left side sill 73 includes an inner member 90 and an outer member 91 made of press-formed materials. The inner member 90 is a member that constitutes the inner side portion of the side sill 73 in the vehicle interior. It bulges inward of the vehicle interior and is formed long in the front-rear direction. The outer member 91 is a member that constitutes the outer side portion of the side sill 73 outside the vehicle. It bulges outward of the vehicle exterior and is formed long in the front-rear direction. The upper portions of the inner member 90 and the outer member 91 are joined together, and the lower portions of the inner member 90 and the outer member 91 are joined together, thereby forming a side sill 73 with a hollow interior.

[0095] A first recess 73a that depresses outward in the vehicle width direction is formed at the lower portion inside the vehicle width direction of the side sill 73 so as to extend in the front-rear direction. The first recess 73a is open downward and inward in the vehicle width direction. The outer side in the vehicle width direction of the battery case 10 of the lower structure body 2 is formed so as to fit into the first recess 73a. Specifically, the left side member 20 of the battery case 10 enters the first recess 73a from below the first recess 73a. Thereby, it is possible to secure a long dimension in the vehicle width direction of the battery case 10 and reduce the amount of protrusion of the battery case 10 downward.

[0096] Inside the side sill 73, a hollow lateral load transmission member 120 is provided which extends in the longitudinal direction and transmits a load acting from the outside in the vehicle width direction toward the inside in the vehicle width direction. The lateral load transmission member 120 performs load transmission not assuming the load during normal driving, but a very large load such that the members on the side of the electric vehicle 1 are deformed, like in a side collision where an obstacle collides from the side of the electric vehicle 1.

[0097] The lateral load transmission member 120 can be formed of, for example, an extruded material and is continuous from the front end portion to the rear end portion of the side sill 73. The lateral load transmission member 120 is fixed to the side sill 73 at appropriate positions. The fixing structure of the lateral load transmission member 120 to the side sill 73 is not particularly limited, and examples thereof include a structure using fastening members such as bolts, nuts, and rivets.

[0098] Since the lateral load transmission member 120 has high rigidity so that it can transmit the load during a side collision toward the inside in the vehicle width direction, it is strong not only against compressive force but also against bending force and torsional force, and also functions as a reinforcing member that reinforces the side sill 73 during normal driving and contributes to improving the vehicle body rigidity. Such a lateral load transmission member 120 can be called an inner reinforcement because it is a member that reinforces the side sill 73 inside the side sill 73.

[0099] The lateral load transmission member 120 has an upper wall portion 121, an outer wall portion 122, an inner upper vertical wall portion 123, an inner lower vertical wall portion 124, an intermediate wall portion 125, and a lower wall portion 126. The upper wall portion 121 extends in the vehicle width direction and is disposed near the upper end inside the side sill 73. The outer wall portion 122 extends downward from the outer end in the vehicle width direction of the upper wall portion 121 and is disposed near the outer end in the vehicle width direction inside the side sill 73. The upper end of the outer wall portion 122 is located above the upper end of the floor side cross member 110. The lower end of the outer wall portion 122 is located below the upper end of the second battery side cross member 25B provided inside the battery case 10. Although not shown, the positional relationship between the first battery side cross member 25A and the third battery side cross member 25C and the lateral load transmission member 120 is also substantially the same.

[0100] The inner upper vertical wall portion 123 extends downward from the inner end in the vehicle width direction of the upper wall portion 121 and is disposed near the inner end in the vehicle width direction inside the side sill 73. The upper end of the inner upper vertical wall portion 123 is located above the upper end of the floor side cross member 110. The lower end of the inner upper vertical wall portion 123 is located below the rear floor portion 70b and above the upper end of the second battery side cross member 25B.

[0101] The intermediate wall portion 125 extends outward in the vehicle width direction from the lower end of the inner upper vertical wall portion 123. The outer end in the vehicle width direction of the intermediate wall portion 125 is located closer to the inner side than the center in the vehicle width direction of the upper wall portion 121. The inner lower vertical wall portion 124 extends downward from the inner end in the vehicle width direction of the intermediate wall portion 125. The lower end of the inner lower vertical wall portion 124 is located below the upper end of the second battery side cross member 25B. The dimension in the vertical direction of the inner lower vertical wall portion 124 is set shorter than the dimension in the vertical direction of the inner upper vertical wall portion 123.

[0102] The lower part of the interior side of the lateral load transmission member 120 is recessed outward in the vehicle width direction by the inner lower vertical wall portion 124 and the intermediate wall portion 125 so as to correspond to the first recess 73a of the side sill 73. The portion where the first recess 73a of the side sill 73 is formed fits into the second recess 120a of the lateral load transmission member 120.

[0103] The lower wall portion 126 extends from the lower end portion of the inner lower vertical wall portion 124 to the lower end portion of the outer wall portion 122. The dimension of the lower wall portion 126 in the vehicle width direction is set to be longer than the dimension of the intermediate wall portion 125 in the vehicle width direction.

[0104] In a side view of the vehicle, the upper part of the lateral load transmission member 120 overlaps with the floor side cross member 110, and the lower part of the lateral load transmission member 120 overlaps with the second battery side cross member 25B. That is, the lateral load transmission member 120 has an inner upper vertical wall portion (first vertical wall portion) 123 that overlaps with the floor side cross member 110 in a side view of the vehicle and extends in the vertical direction, and an inner lower vertical wall portion (second vertical wall portion) 124 that overlaps with the battery case 10 in a side view of the vehicle and extends in the vertical direction. Incidentally, the lower part of the inner upper vertical wall portion 123 may overlap with the upper part of the battery case 10.

[0105] Inside the lateral load transmission member 120, the first to fourth ribs 131 to 134 are integrally formed. The first rib 131 extends in the vehicle width direction at a location away from the intermediate wall portion 125 upward, and the inner end portion of the first rib 131 in the vehicle width direction is connected to the middle portion in the vertical direction of the inner upper vertical wall portion 123. The first rib 131 is inclined so as to be positioned higher as it goes outward in the vehicle width direction.

[0106] The second rib 132 extends in the vehicle width direction at a location below and away from the first rib 131, and the inner end portion of the second rib 132 in the vehicle width direction is connected to the upper end portion of the inner lower vertical wall portion 124. The outer end portion of the second rib 132 in the vehicle width direction is connected to the middle portion in the vertical direction of the outer wall portion 122. The first rib 131 and the second rib 132 may extend substantially horizontally, may be inclined so as to be positioned higher as going toward the inner side in the vehicle width direction, or may be inclined so as to be positioned higher as going toward the outer side in the vehicle width direction.

[0107] The third rib 133 extends upward from the upper end portion of the inner lower vertical wall portion 124. The upper end portion of the third rib 133 is connected to the middle portion in the vehicle width direction of the upper wall portion 121. The third rib 133 is inclined so as to be positioned more outward in the vehicle width direction as going upward. The outer end portion of the first rib 131 in the vehicle width direction is connected to the middle portion in the vertical direction of the third rib 133.

[0108] The fourth rib 134 extends in the vehicle width direction at a location above and away from the second rib 132. The inner end portion of the fourth rib 134 in the vehicle width direction is connected to the middle portion in the vertical direction of the third rib 133. The outer end portion of the fourth rib 134 in the vehicle width direction is connected to the middle portion in the vertical direction of the outer wall portion 122. The inner end portion of the fourth rib 134 in the vehicle width direction and the outer end portion of the first rib 131 in the vehicle width direction are connected via the third rib 133, and the first rib 131 and the fourth rib 134 constitute one rib continuous in the vehicle width direction. The number and shape of the ribs formed inside the side load transmission member 120 are not limited to those described above, and the number of ribs may be three or less, or may be five or more.

[0109] The battery case 10 is fixed to the side sill 73 and is directly fixed to the side load transmission member 120. A plurality of metal cylindrical members 140 extending in the vertical direction are fixed to the left side member 20 of the battery case 10. The interval in the front-rear direction of the cylindrical members 140 can be set to, for example, about several tens of cm. As shown in FIG. 2, the plurality of cylindrical members 140 are arranged at intervals in the front-rear direction. Bolts 141 are adapted to be inserted into each of the cylindrical members 140 from below.

[0110] On one hand, a portion corresponding to the inner surface of the first recess 73a in the side sill 73 is open so that the shaft portion of the bolt 141 can be inserted therethrough. Similarly, an opening is provided in the intermediate wall portion 125 of the lateral load transmission member 120 so that the shaft portion of the bolt 141 can be inserted therethrough, and the two openings coincide. Inside the lateral load transmission member 120, a nut 142 is accommodated. The nut 142 is fixed to the upper surface of the intermediate wall portion 125 of the lateral load transmission member 120. The number and positions of the openings and the nut 142 correspond to the number and positions of the cylindrical members 140.

[0111] Therefore, by inserting each bolt 141 into the cylindrical member 140, inserting it through the opening of the side sill 73 and the opening of the lateral load transmission member 120, and screwing and tightening it to the nut 142, a plurality of locations on the left side of the battery case 10 can be fixed to the lateral load transmission member 120 and the side sill 73. The right side of the battery case 10 can be fixed in the same manner.

[0112] In the present embodiment, the case where the lateral load transmission member 120 is integrally formed has been described, but the present invention is not limited thereto, and the lateral load transmission member 120 may be configured by combining a plurality of members. Although not shown, for example, the inner and outer portions in the vehicle width direction of the lateral load transmission member 120 may be separately formed and then integrated into a two-part structure. Further, the lateral load transmission member 120 may have a three-part structure.

[0113] As shown in FIG. 7 and the like, the upper structure 3 includes a pair of left and right hinge pillars 150. The right hinge pillar 150 extends upward from the front end portion of the right side sill 73. Also, as shown in FIG. 2, the left hinge pillar 150 extends upward from the front end portion of the left side sill 73. The left and right front doors 81 (shown in FIG. 1) are respectively attached to the left and right hinge pillars 150.

[0114] Also, as shown in FIG. 10, the upper structure 3 also includes a pair of left and right center pillars 157. The right center pillar 157 extends upward from the middle portion in the front-rear direction of the right side sill 73. Also, as shown in FIG. 2, the left center pillar 157 extends upward from the middle portion in the front-rear direction of the left side sill 73. The left and right rear doors 82 (shown in FIG. 1) are attached to the left and right center pillars 157, respectively.

[0115] As shown in FIG. 9, the upper structure 3 includes a pair of left and right floor reinforcements (first front-rear direction load transmission members) 151. The floor reinforcement 151 extends in the front-rear direction along the upper surface of the front floor portion 70a. The front end portion of the right floor reinforcement 151 is connected to the rear end portion of the right front side frame 72. The rear end portion of the right floor reinforcement 151 is connected to the front end portion of the right side sill 73. Therefore, since the front side frame 72 and the side sill 73 are connected by the floor reinforcement 151, when a collision load is input during a frontal collision to the front side frame 72, for example, it is transmitted to the side sill 73 via the floor reinforcement 151.

[0116] The floor reinforcement 151 bulges upward and is open downward, and this bulging shape is continuous from the front end portion to the rear end portion. By attaching the floor reinforcement 151 to the upper surface of the front floor portion 70a, a closed cross-section is formed by the floor reinforcement 151 and the front floor portion 70a.

[0117] Since the side sill 73 is located outside the vehicle width direction from the front side frame 72, the floor reinforcement 151 extends while curving in a plan view so as to be located outside in the vehicle width direction as it goes to the rear side. The curved shape of this floor reinforcement 151 corresponds to the shape of the lower end portion of the front wheel house portion 85. That is, the floor reinforcement 151 extends along the lower end portion of the front wheel house portion 85 and is connected and integrated with the front wheel house portion 85. Incidentally, the left floor reinforcement (not shown) has a left-right symmetric structure with the right one.

[0118] While the floor reinforcement 151 is attached to the upper surface of the front floor portion 70a, the outer connection portion 30 (shown in FIG. 3 etc.) of the lower structure 2 is located below the front floor portion 70a. Therefore, the floor reinforcement 151 and the outer connection portion 30 are in a positional relationship of being separated from each other in the vertical direction. Similarly, the floor reinforcement 151 and the inner connection portion 31 are also in a positional relationship of being separated from each other in the vertical direction.

[0119] Also, in a plan view, the portion on the side sill 73 side (the rear end portion of the floor reinforcement 151) in the right floor reinforcement 151 and the portion on the battery case 10 side (the rear end portion of the outer connection portion 30) in the right outer connection portion 30 overlap each other. Since the rear end portion of the floor reinforcement 151 is a portion connected to the side sill 73, it is arranged so as to be adjacent to the side sill 73. On the other hand, since the outer connection portion 30 is a member connected to the battery case 10, it will be separated from the side sill 73. However, in a plan view, the fact that the rear end portion of the outer connection portion 30 overlaps the rear end portion of the floor reinforcement 151 means that the rear end portion of the outer connection portion 30 can be brought close to the side sill 73. Therefore, the collision load from the front can be surely applied to the side sill 73 side via the outer connection portion 30. The same applies to the left side.

[0120] The rear end of the right floor reinforcement 151 and the base end portion (lower end portion) of the right hinge pillar 150 are arranged at the same position in the front-rear direction. That is, the vicinity of the base end portion of the hinge pillar 150 in the side sill 73 is a portion with particularly high rigidity. By connecting the rear end portion of the floor reinforcement 151 to this portion with particularly high rigidity, the collision load can be efficiently absorbed by the side sill 73.

[0121] As shown in FIG. 7, the upper structure 3 includes a pair of left and right lower load transmission members (second front-rear direction load transmission members) 152. The lower load transmission members 152 are disposed above the front frame member 11 of the lower structure 2, and the front frame member 11 and the lower load transmission members 152 are separated from each other in the vertical direction. Further, the lower load transmission members 152 extend in the front-rear direction along the lower surface of the front floor portion 70a. As schematically shown in FIG. 11, the front end portion of the right lower load transmission member 152 is connected to the rear end portion of the right front side frame 72. And since the lower load transmission members 152 extend toward the front portion of the battery case 10, for example, when a collision load is input rearward during a frontal collision with respect to the front side frame 72, the collision load is transmitted to the front portion of the battery case 10 via the lower load transmission members 152. The left lower load transmission member 152 is symmetric with the right one with respect to left and right.

[0122] The lower load transmission members 152 bulge downward and are open upward, and this bulged shape is continuous from the front end portion to the rear end portion. By attaching the lower load transmission members 152 to the lower surface of the front floor portion 70a, a closed cross-section is formed by the lower load transmission members 152 and the front floor portion 70a.

[0123] The rear portion of the right lower load transmission member 152 is positioned on the right side of the front central member 26 in the battery case 10 and on the left side of the right side member 21. Also, the rear portion of the left lower load transmission member 152 is positioned on the left side of the front central member 26 in the battery case 10 and on the right side of the left side member 20.

[0124] As shown in FIGS. 7 to 9, a cross member 153 extending in the left - right direction and connecting the rear portions of the left lower load - transmitting member 152 and the right lower load - transmitting member 152 is disposed on the lower surface of the front floor portion 70a. The cross member 153 bulges downward and is open upward, and has substantially the same cross - sectional shape over both left - right ends. By attaching the cross member 153 to the lower surface of the front floor portion 70a, a closed cross - section is formed by the cross member 153 and the front floor portion 70a. By disposing the cross member 153, when the left and right lower load - transmitting members 152 receive a collision load during a frontal collision, displacement of the rear portions of the lower load - transmitting members 152 in the left - right direction can be suppressed.

[0125] As shown in FIG. 11, a front - end member 22 that constitutes the front portion of the battery case 10 is disposed directly below the cross member 153. The front - end member 22 is fastened to the cross member 153 by bolts and nuts (not shown). The fastening structure of the front - end member 22 can be the same as the fastening structure to the side sill 73 of the left - side member 20.

[0126] A protruding portion 22a protruding upward is provided at the front portion of the battery case 10. Specifically, the protruding portion 22a is provided at a portion of the front - end member 22 behind the cross member 153. This protruding portion 22a is located behind the rear portion of the lower load - transmitting member 152. Also, the protruding portion 22a is formed such that its upper end is located above the lower surface of the cross member 153 and above the lower surface of the rear portion of the lower load - transmitting member 152. Thereby, in a front - rear direction view, the cross member 153, the lower load - transmitting member 152, and the protruding portion 22a overlap each other. The protruding portion 22a is a portion where the collision load is transmitted from the lower load - transmitting member 152 when the lower load - transmitting member 152 retreats due to the collision load during a frontal collision.

[0127] The protruding portion 22a extends continuously in the left - right direction. That is, during a frontal collision, although it is conceivable that the rear part of the lower load transmission member 152 is somewhat displaced in the left - right direction, since the protruding portion 22a is continuous in the left - right direction, even if the rear part of the lower load transmission member 152 is displaced in the left - right direction, the collision load can be surely input to the protruding portion 22a. Note that the protruding portion 22a is not limited to being continuous in the left - right direction, and it may be formed discontinuously, as long as at least a part thereof overlaps with the rear part of the lower load transmission member 152 when viewed in the front - rear direction.

[0128] The protruding portion 22a may be integrally formed with the front end member 22, or may be composed of a separate member. When the front end member 22 is an extruded material, the protruding portion 22a can be easily integrally formed. The protruding portion 22a may be fixed to, for example, the bottom plate 24, or may be fixed to the left - side member 20, the right - side member 21, etc. The protruding portion 22a may have any shape such as, for example, a plate shape (rib shape), a rod shape, a cylindrical shape, etc. By forming the protruding portion 22a in a rib shape and integrally forming it with the front end member 22, the reinforcing effect of the front end member 22 can also be obtained.

[0129] The rear part of the lower load transmission member 152 and the protruding portion 22a are arranged with a predetermined interval in the front - rear direction. By providing a predetermined interval, during normal running, the lower load transmission member 152 and the protruding portion 22a do not come into contact with each other, so the generation of interference noise and the like is avoided. On the other hand, when the lower load transmission member 152 moves rearward during a frontal collision, the rear part of the lower load transmission member 152 comes into contact with the protruding portion 22a, so that the collision load can be surely input to the protruding portion 22a. That is, the above - mentioned predetermined interval is an interval set so that the lower load transmission member 152 and the protruding portion 22a do not come into contact with each other during normal running, and the rear part of the lower load transmission member 152 comes into contact with the protruding portion 22a during a frontal collision, and can be, for example, about several millimeters to several centimeters. Note that the rear part of the lower load transmission member 152 and the protruding portion 22a may be brought into contact with each other. Also, the rear part of the lower load transmission member 152 and the protruding portion 22a may be joined by a fastening member.

[0130] Also, in the form shown in FIG. 6, the front central member 26 within the battery case 10 is provided below the front floor portion 70a and has a greater height compared to the first to third rear central members 27 to 29. Therefore, since the vertical dimension of the front central member 26 becomes longer, the front central member 26 with a large cross-section is positioned at the front portion of the battery case 10. As a result, when the collision load transmitted from the lower load transmission member 152 is received at the front portion of the battery case 10, deformation of the battery case 10 is suppressed.

[0131] (Connection structure between the rear portion of the battery case and the upper structure) As shown in FIG. 13, the rear portion of the battery case 10 and the upper structure 3 are connected by a connecting member 160. Before explaining this connection structure, the structure on the rear side of the upper structure 3 will be described. On both the left and right sides of the rear portion of the upper structure 3, rear wheel house portions 170 (only the right one is shown in FIGS. 7 to 9) for accommodating the left and right rear wheels R are respectively provided. The cargo floor portion 70e that constitutes the floor surface of the cargo compartment R2 in the floor panel 70 extends rearward from the rear portion of the kick-up portion 70c and is positioned above the rear floor portion 70b. The rear floor portion 70b is taken as the first floor portion, and the kick-up portion 70c and the cargo floor portion 70e are taken as the relatively high second floor portion. The left end portion of the cargo floor portion 70e is connected to the lower portion of the left rear wheel house portion 170 (shown in FIG. 2), and the right end portion of the cargo floor portion 70e is connected to the right rear wheel house portion 170 (shown in FIGS. 7 to 9).

[0132] As shown in FIGS. 7 to 9, a rear cross member (first cross member) 171 extending in the left-right direction is attached to the lower surface of the kick-up portion 70c. The rear cross member 171 bulges downward and is open upward, and this bulged shape is continuous from the left end portion to the right end portion. By attaching the rear cross member 171 to the lower surface of the kick-up portion 70c, a closed cross-section is formed by the rear cross member 171 and the kick-up portion 70c.

[0133] On the upper surface of the kick-up portion 70c, a rear floor side cross member 172 extending in the left-right direction is attached directly above the rear cross member 171. The rear floor side cross member 172 bulges upward and is open downward, and this bulging shape continues from the left end to the right end. By attaching the rear floor side cross member 172 to the upper surface of the kick-up portion 70c, a closed cross section is formed by the rear floor side cross member 172 and the kick-up portion 70c. In plan view, the rear floor side cross member 172 and the rear cross member 171 overlap.

[0134] Also, the right end of the rear floor side cross member 172 is connected to the right rear wheel house portion 170, and the left end of the rear floor side cross member 172 is connected to the left rear wheel house portion 170. Further, at the right end of the rear floor side cross member 172, the lower end of a side reinforcement 173 extending upward along the right rear wheel house portion 170 is connected. Also, at the left end of the rear floor side cross member 172, the lower end of a side reinforcement (not shown) extending upward along the left rear wheel house portion 170 is connected. And the upper part of the right side reinforcement 173 and the upper part of the left side reinforcement are connected by a connecting member 174 (shown in FIGS. 8 and 9) extending in the left-right direction. That is, an annular structure is formed by the rear floor side cross member 172, the left and right side reinforcements 173, and the connecting member 174. The annular structure may be formed using a reinforcement (not shown) provided up to the roof 80 side.

[0135] On the other hand, as shown in FIG. 13, the battery case 10 has a case side cross member (second cross member) 180 (omitted in FIGS. 2 to 6). The case side cross member 180 extends in the left-right direction and is attached to a rear end member 23 that constitutes the rear part of the battery case 10. The case side cross member 180 is located above the rear end member 23. The case side cross member 180 and the rear cross member 171 are arranged to face each other in the vertical direction.

[0136] As shown in FIG. 13, the connecting member 160 is a member for connecting the rear end member 23 of the battery case 10 and the kick-up portion 70c. Thereby, since the kick-up portion 70c is reinforced using the battery case 10, the rigidity of the kick-up portion 70c is improved. By improving the rigidity of the kick-up portion 70c, the rigidity of the entire floor panel 70 is also improved. In this embodiment, the connecting member 160 is composed of a plate material extending in the left-right direction and the up-down direction, but is not limited thereto, and may be a closed cross-sectional member, a shaft member, a cylindrical member, etc. extending in the up-down direction or obliquely. Also, a plurality of connecting members 160 may be provided.

[0137] The upper part of the connecting member 160 is fixed to the lower part of the rear cross member 171. Thereby, the battery case 10 and the kick-up portion 70c are connected by the connecting member 160 via the rear cross member 171. That is, since the upper part of the connecting member 160 can be fixed to the portion where the rigidity is improved by providing the rear cross member 171, the fixing strength of the connecting member 160 to the kick-up portion 70c can be increased. As the fixing structure of the upper part of the connecting member 160, a detachable fastening structure using fastening members such as bolts and nuts (not shown) can be used. Note that the upper part of the connecting member 160 may be directly connected to the kick-up portion 70c.

[0138] Also, the lower part of the connecting member 160 is fixed to the case side cross member 180 which forms a part of the battery case 10. Thereby, since the lower part of the connecting member 160 can be fixed to the portion where the rigidity of the battery case 10 is improved, the fixing strength of the connecting member 160 to the battery case 10 can be increased. Note that the lower part of the connecting member 160 may be detachably fixed to the battery case 10 by the above-described fastening members. The connecting member 160 may be a component on the upper structure body 3 side or a component on the lower structure body 2 side.

[0139] (Positional relationship between the cross members of the upper structure body and the lower structure body) FIG. 14 is a schematic diagram showing the positional relationship between the cross members of the upper structure 3 and the lower structure 2 according to a modification of the embodiment. On the upper surface of the floor panel 70 of the upper structure 3, first to third floor-side cross members 110A, 110B, and 110C extending in the vehicle width direction are attached, and a cross member 153 is attached to the lower surface of the floor panel 70. Since the cross member 153 is attached to the floor panel 70, it is a floor-side cross member.

[0140] The first floor-side cross member 110A is the above-described cross member 110 and is arranged behind the cross member 153. The second floor-side cross member 110B is arranged behind the first floor-side cross member 110A. The third floor-side cross member 110C is arranged behind the second floor-side cross member 110B. On the other hand, the first to third battery-side cross members 25A, 25B, and 25C described above are provided on the battery case 10 of the lower structure 2. In a side view, the cross member 153, the first to third floor-side cross members 110A, 110B, and 110C, and the first to third battery-side cross members 25A, 25B, and 25C overlap with the side sill 73 (shown in FIG. 10 etc.).

[0141] In a side view of the vehicle, the cross member 153, the first to third floor-side cross members 110A, 110B, and 110C, and the first to third battery-side cross members 25A, 25B, and 25C are displaced in the vehicle front-rear direction. That is, in order from the front side to the rear side of the vehicle, the cross member 153, the first battery-side cross member 25A, the first floor-side cross member 110A, the second battery-side cross member 25B, the second floor-side cross member 110B, the third battery-side cross member 25C, and the third floor-side cross member 110C are located, and the cross member 153, the first to third floor-side cross members 110A, 110B, and 110C, and the first to third battery-side cross members 25A, 25B, and 25C are provided alternately in the front-rear direction.

[0142] For example, when focusing on the first floor side cross member 110A and the second floor side cross member 110B, the second battery side cross member 25B is located in front of the first floor side cross member 110A and behind the second floor side cross member 110B. On the other hand, when focusing on the first battery side cross member 25A and the second battery side cross member 25B, the first floor side cross member 110A is located behind the first battery side cross member 25A and in front of the second battery side cross member 25B. Such a positional relationship is referred to as "being offset in the vehicle longitudinal direction".

[0143] Also, "being offset in the vehicle longitudinal direction" may include another form. For example, it can include a form in which the center in the longitudinal direction of the first floor side cross member 110A and the center in the longitudinal direction of the second battery side cross member 25B are offset in the longitudinal direction. In this case, the form shown in FIG. 14 is also included. For example, a form in which the rear part of the first floor side cross member 110A and the front part of the second battery side cross member 25B are in an overlapping positional relationship in plan view is also included.

[0144] Also, for example, a form in which the front part of the first floor side cross member 110A is located in front of the front part of the second battery side cross member 25B, and a form in which the rear part of the second battery side cross member 25B is located behind the rear part of the first floor side cross member 110A are also included in "being offset in the vehicle longitudinal direction".

[0145] In the event of a side collision, the cross member 153, the first to third floor side cross members 110A, 110B, 110C, and the first to third battery side cross members 25A, 25B, 25C can receive the collision load. Since the cross member 153, the first to third floor side cross members 110A, 110B, 110C, and the first to third battery side cross members 25A, 25B, 25C are displaced in the vehicle longitudinal direction as described above, even if the obstacle is a thin object such as a pole, the collision load of the obstacle can be input to any of the floor side cross members 153, 110A, 110B, 110C and the battery side cross members 25A, 25B, 25C.

[0146] In a side view of the vehicle, only the floor side cross members 110A, 110B, 110C and the battery side cross members 25A, 25B, 25C in the region non-overlapping with the hinge pillar 150 (shown by a virtual line in FIG. 14) are displaced in the longitudinal direction. That is, the floor side cross members 110A, 110B, 110C and the battery side cross members 25A, 25B, 25C located behind the hinge pillar 150 are displaced in the longitudinal direction. That is, since the portion where the hinge pillar 150 is located has high strength against the collision load from the side, even if the floor side cross member and the battery side cross member are not displaced in the longitudinal direction, the collision load can be received by the hinge pillar 150.

[0147] Similarly, in a side view of the vehicle, only the floor side cross members 110A, 110C and the battery side cross members 25A, 25B, 25C in the region non-overlapping with the center pillar 157 may be displaced in the longitudinal direction.

[0148] (Effect during frontal collision) Next, the case where the electric vehicle 1 configured as described above collides frontally will be described. The collision load during a frontal collision is input to the left and right front side frames 72 via the front bumper reinforcement 86. Also, the collision load during a frontal collision is input to the left and right front frame members 11.

[0149] Regarding the front frame member 11, since a plurality of portions spaced apart in the front-rear direction of the front frame member 11 are respectively connected to the left front side frame 72 by the left connection portions 53 and 54, the left front frame member 11 into which a collision load is input is stabilized and is less likely to tilt in the left-right direction and the up-down direction. The same applies to the right front frame member 11. Thereby, the collision load is linearly transmitted to the front portion of the battery case 10 by the left and right front frame members 11.

[0150] At this time, since the front frame member 11 is connected to the battery case 10 at a plurality of portions spaced apart from each other in the left-right direction by the outer connection portion 30 and the inner connection portion 31, the collision load input to the front frame member 11 is input to a plurality of portions spaced apart in the left-right direction in the battery case 10. Since the battery case 10 includes a front center member 26 extending in the front-rear direction, a left side member 20, and a right side member 21, the collision load input to a plurality of portions spaced apart in the left-right direction is dispersed and transmitted to the front center member 26, the left side member 20, and the right side member 21. Thereby, it becomes possible to absorb the collision load by actively using the battery case 10, so that the amount of collision load absorbed by the lower structure 2 can be increased, and accordingly, the strength of the front side frame 72 and the strength of the members near the rear end portion of the front side frame 72 can be optimized to realize weight reduction of the entire vehicle.

[0151] In addition, the collision load input to the front side frame 72 is transmitted to the side sill 73 via the floor reinforcement 151. Further, since the outer connection portion 30 extends toward the side sill 73 side, the collision load input to the front frame member 11 can also be made to act toward the side sill 73 side via the outer connection portion 30. At this time, since the floor reinforcement 151 and the outer connection portion 30 are separated in the vertical direction, the route of the collision load transmitted from the front side frame 72 to the side sill 73 and the route of the collision load acting from the front frame member 11 toward the side sill 73 side are different routes. Therefore, the collision load is transmitted to the side sill 73 through a plurality of routes. Since the side sill 73 is a member with particularly high rigidity among the members constituting the vehicle body, the collision load can be absorbed by the side sill 73.

[0152] In addition, the collision load input to the front side frame 72 is transmitted to the battery case 10 from the rear part of the front side frame 72 via both the floor reinforcement 151 and the lower load transmission member 152. As a result, a route of the collision load transmitted to the battery case 10 via the lower load transmission member 152 is also formed, so that the collision load is dispersed and absorbed by both the side sill 73 and the battery case 10. Further, since the floor reinforcement 151 and the lower load transmission member 152 are along the floor panel 70, a part of the collision load input to the floor reinforcement 151 and the lower load transmission member 152 is also transmitted to the floor panel 70 and absorbed by the floor panel 70.

[0153] In the case of an offset frontal collision, a large collision load is input to either the left or right side. However, this embodiment is also effective in this case. Also, in the case of a rear collision, since the rear frame member 12 is provided, the same operational effects can be achieved.

[0154] (Effect during side collision) Next, a case where the electric vehicle 1 configured as described above undergoes a side collision will be explained. The collision load during a side collision is input from the outside to the inside in the vehicle width direction with respect to the side sill 73. Since a side load transmission member 120 is provided inside this side sill 73, the collision load is input to the side load transmission member 120 from the outside to the inside in the vehicle width direction. At this time, since the inner upper vertical wall portion 123 of the side load transmission member 120 overlaps with the cross members 110 and 153 on the floor side, and the inner lower vertical wall portion 124 overlaps with the battery case 10, the collision load is dispersed and transmitted to the cross members 110 and 153 on the floor side and the battery case 10. Since the cross members 110 and 153 on the floor side extend in the vehicle width direction while being attached to the floor panel 70, they have high strength against side loads. As a result, a part of the collision load is absorbed, and the collision load input to the battery case 10 is reduced, protecting the battery B. Also, since the first to third battery-side cross members 25A, 25B, 25C, the front end member 22, and the rear end member 23 are provided on the battery case 10, the battery case 10 can also absorb the collision load.

[0155] Further, for example, when an obstacle such as a pole collides with the side of the vehicle, as shown in FIG. 14, the cross member 153 and the first to third floor-side cross members 110A, 110B, 110C, and the first to third battery-side cross members 25A, 25B, 25C are displaced in the vehicle front-rear direction, so that the collision load can be input to any of the cross members. It should be noted that it is conceivable that a thin pole collides between the first floor-side cross member 110A and the second battery-side cross member 25B. In this case, after the high-strength side load transmission member 120 receives the collision load of the pole, the collision load can be dispersed and absorbed at least by the first floor-side cross member 110A and the second battery-side cross member 25B.

[0156] Furthermore, when the obstacle is a large-diameter pole, an automobile, or the like, a collision load is input to both the floor-side cross members 110A, 110B, 110C and the battery-side cross members 25A, 25B, 25C. Therefore, the collision load is dispersed and transmitted to the floor panel 70 and the battery case 10.

[0157] The above-described embodiments are merely illustrative in every respect and should not be construed in a limiting sense. Further, modifications and changes belonging to the equivalent scope of the claims are all within the scope of the present invention.

Industrial Applicability

[0158] As described above, the vehicle body structure according to the present invention is suitable for an electric vehicle equipped with a driving motor and a battery.

Explanation of Reference Numerals

[0159] 1 Electric vehicle 10 Battery case 11 Front frame member 20 Left side member 21 Right side member 22 Front end member 22a Protrusion 25A, 25B, 25C First to third battery-side cross members 26 Front center member (front reinforcement member) 27 - 29 First to third rear center members (rear reinforcement members) 30 Outer connection part (one connection part) 31 Inner connection part (the other connection part) 53, 54 Left connection parts 55, 56 Right connection parts 70 Floor panel 70a Front floor part 70b Rear floor part (first floor part) 70c Kick-up part (second floor part) 72 Front side frame 73 Side sill 100 Seat fixing part 110A, 110B, 110C First to Third Floor Side Cross Members 120 Side Load Transmission Member (Inner Reinforcement) 123 Inner Upper Vertical Wall Portion (First Vertical Wall Portion) 124 Inner Lower Vertical Wall Portion (Second Vertical Wall Portion) 150 Hinge Pillar 151 Floor Reinforcement (First Front - Rear Direction Load Transmission Member) 152 Lower Load Transmission Member (Second Front - Rear Direction Load Transmission Member) 153 Cross Member 160 Connecting Member 170 Rear Wheel House Portion 171 Rear Cross Member (First Cross Member) 180 Case Side Cross Member (Second Cross Member) A Vehicle Body Structure B Battery M Driving Motor

Claims

1. In a vehicle body structure of an electric vehicle having a traveling motor and a battery case that houses a battery for supplying power to the traveling motor, the battery case is disposed below a floor panel, a pair of left and right side frames disposed so as to extend in the vehicle longitudinal direction on one side and above in the vehicle longitudinal direction with respect to the floor panel, a pair of left and right side sills disposed so as to extend in the vehicle longitudinal direction at both ends in the vehicle width direction of the floor panel, a floor reinforcement that connects the side frame and the side sill and transmits a load from the side frame to the side sill, a frame member that extends in one direction in the vehicle longitudinal direction below the side frame from the battery case inside the vehicle width direction with respect to the side sill, an outer connection portion that extends outward in the vehicle width direction from a mid portion in the vehicle longitudinal direction of the frame member toward the side sill side and is connected to the battery case, a vehicle body structure in which the floor reinforcement and the outer connection portion are vertically spaced apart from each other.

2. In the vehicle body structure according to Claim 1, a vehicle body structure in which a portion on the side sill side in the floor reinforcement and a portion on the battery case side in the outer connection portion are positioned so as to overlap each other in plan view.

3. In the vehicle body structure according to Claim 1 or 2, a vehicle body structure in which an inner reinforcement extending in the vehicle longitudinal direction is provided inside the side sill.

4. In the vehicle body structure according to any one of Claims 1 to 3, an inner connection portion that extends from a mid portion in the vehicle longitudinal direction of the frame member toward the center in the vehicle width direction of the battery case and is connected to the battery case, a vehicle body structure in which a center member extending in the vehicle longitudinal direction is provided at the center in the vehicle width direction of the battery case.

5. In the vehicle body structure according to any one of Claims 1 to 4, a vehicle body structure in which the frame member is disposed inside the side frame in the vehicle width direction.

6. In the vehicle body structure according to any one of Claims 1 to 5, a pair of left and right hinge pillars extending upward from the pair of left and right side sills respectively, a vehicle body structure in which a portion on the side sill side in the floor reinforcement and a base end portion of the hinge pillar are arranged at the same position in the vehicle longitudinal direction.

7. In the vehicle body structure according to any one of claims 1 to 6, the floor reinforcement is formed to extend in the vehicle longitudinal direction along the upper surface of the floor panel, and is attached to the upper surface of the floor panel to form a closed cross-section together with the floor panel.

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