Body structure

Abstract

To secure a large mounting capacity for a battery as well as improve comfortability for an occupant, while suppressing deformation of a cabin and a battery case in the event of a front collision by increasing the strength of a front part of the battery case.SOLUTION: A vehicle body structure includes front side frames 72, and longitudinal load transmission members 152 respectively extending from rear parts of the front side frames 72 toward a vehicle front part of a battery case 10. A floor panel 70 has: a rear floor portion 70b on which at least part of a seat fixing portion 100 for fixing a front seat S1 is attached; and a front floor portion 70a located higher than the rear floor portion 70b. A reinforcement member extending in a longitudinal direction and formed such that an upper end is located above the rear floor portion 70b is provided below the front floor portion 70a of the battery case 10.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

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

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

[0004] In Patent Document 1, the under-member is configured to be more easily deformed than the front extension, so that when the vehicle collides head-on with an obstacle, the under-member deforms first to absorb the collision load. Any collision load that cannot be absorbed by the deformation of the under-member is absorbed by the deformation of the front extension of the case main body. In other words, in Patent Document 1, the under-member and the front extension of the case main body are actively deformed as shock absorbing members during a frontal collision to absorb the collision load in two stages and suppress deformation of the case main body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-158688 A Summary of the Invention [Problem 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 that deforms under a relatively large load in the fore-and-aft direction of the vehicle, the collision load is prevented from being transmitted to the case main body, thereby suppressing deformation of the case main body.

[0007] However, there is a demand for further improvements in collision safety for automobiles. In particular, when a large collision load is input to the vehicle body, it is necessary not only to suppress deformation of the cabin caused by the collision load, but also to protect the large-capacity battery cells installed in electric vehicles.

[0008] Here, securing living space is also an issue for automobiles. If a large-capacity battery case is mounted under the floor as in Patent Document 1, the floor panel becomes higher, and as a result, the fixed position of the seat fixed to the floor panel also becomes higher, so the headroom for the passengers seated in the seat becomes narrow. This problem can be solved by reducing the battery capacity, but doing so would shorten the cruising range, so we do not want to adopt a solution that reduces the battery capacity.

[0009] One possible solution would be to increase the interior height without lowering the floor panel. However, increasing the interior height without lowering the floor panel would increase the vehicle height, which may be subject to restrictions on vehicle design or parking facilities, making this solution an option.

[0010] The present invention has been made in consideration of these points, and its purpose is to increase the strength of the front part of the battery case to suppress deformation of the cabin and battery case in the event of a frontal collision, while ensuring a large battery capacity and improving occupant living comfort. [Means for solving the problem]

[0011] In order to achieve the above object, a first aspect of the present disclosure can be based on the premise of a vehicle body structure of an electric vehicle that includes a driving motor and a battery case that houses a battery that supplies power to the driving motor and is disposed below a floor panel. The vehicle body structure includes a pair of left and right front side frames that are disposed at the front of the vehicle body and extend in the vehicle longitudinal direction, and a longitudinal load transmission member that extends from the vehicle rear of the left and right front side frames toward the vehicle front of the battery case. The floor panel has a rear floor portion to which at least a part of a seat fixing portion for fixing a front seat is attached, and a front floor portion that is provided in front of the rear floor portion and located above the rear floor portion. The battery case is formed so as to reach from below the front floor portion to below the rear floor portion. A front reinforcing member that extends in the vehicle longitudinal direction and is formed so that an upper end portion is located above the rear floor portion is provided below the front floor portion of the battery case.

[0012] With this configuration, the battery case is provided over a wide area below the floor panel, extending from below the front floor to below the rear floor, and the space below the relatively high front floor is used as a mounting space for the battery, increasing the mounting capacity of the battery. Also, since at least a part of the seat fixing part is attached to the relatively low rear floor, the seating position of the front seat can be lowered, improving the comfort of the front seat occupants.

[0013] On the other hand, when the electric vehicle is involved in a frontal collision, the collision load is input to the front side frame and transmitted from the vehicle rear of the front side frame to the front of the battery case via the longitudinal load transmission member. Since the front of the battery case is located below the front floor, a front reinforcing member extending in the longitudinal direction is provided at this portion. Since the upper end of the front reinforcing member is higher than the rear floor, the vertical dimension of the front reinforcing member is longer, and therefore the front reinforcing member with a large cross section is located at the front of the battery case. Therefore, when the collision load transmitted from the longitudinal load transmission member is received by the front of the battery case, deformation of the battery case is suppressed and deformation of the cabin is also suppressed.

[0014] In addition, by positioning the front floor part higher than the rear floor part, the operability of the pedal is also improved. That is, according to the study by the inventor, regarding the posture of the occupant when operating the pedal, the angle between the lower leg and the floor is reduced by placing the heel of the occupant who operates the pedal at a higher position than the usual position and lowering the hip point, and the operability of the pedal is improved. To be more specific, the pedal operation in a vehicle is an operation of pushing toward the front of the vehicle, and in most cases, the heel is placed on the floor panel at this time. Therefore, the reaction force from the pedal acts on the sole of the foot, and the reaction force from the floor panel mainly acts on the heel. The operation direction of a general pedal is not horizontal but obliquely downward, and the angle between the lower leg and the floor panel during this pedal operation is reduced, which means that the component force in the vertical direction input from the heel is reduced. This allows, for example, the operation of changing the foot from the brake pedal to the accelerator pedal or vice versa to be performed quickly and accurately, and as a result, the operability of the pedal is improved. In this regard, in the present configuration, the front floor section on which the pedal operator's heel is placed is positioned higher than the rear floor section, so that the pedal operator's heel is placed in a higher position. This reduces the angle between the pedal operator's lower leg and the front floor section, reducing the vertical component of force input from the heel when operating the pedal, improving pedal operability.

[0015] In a second aspect of the present disclosure, the front reinforcing member is provided at the center of the battery case in the vehicle width direction.

[0016] According to this configuration, the reinforcing member exerts a reinforcing effect against a collision load input from either the left or right front side frame, thereby enhancing the effect of suppressing deformation of the battery case.

[0017] In a third aspect of the present disclosure, an end member extending in a vehicle width direction is provided at a vehicle front end portion of the battery case.

[0018] With this configuration, the strength of the front portion of the battery case is further increased, so that the amount of deformation caused by the collision load transmitted to the front portion is further reduced.

[0019] In a fourth aspect of the present disclosure, the entire seat fixing portion is attached to the rear floor portion.

[0020] According to this configuration, the mounting position of the front seats can be lowered as a whole, so that the comfort for passengers seated in the front seats is further improved.

[0021] In a fifth aspect of the present disclosure, a rear reinforcing member extending in a vehicle front-rear direction is provided below the rear floor portion of the battery case so as to be located on an imaginary extension line of the front reinforcing member toward the rear of the vehicle.

[0022] According to this configuration, the front reinforcement member and the rear reinforcement member are aligned in the vehicle front-rear direction, so that the collision load input to the front reinforcement member can be received by the rear reinforcement member, thereby further reducing the deformation of the battery case.

[0023] In a sixth aspect of the present disclosure, the lower end portions of the front reinforcement member and the rear reinforcement member are attached to a bottom plate of the battery case, and the upper end portion of the rear reinforcement member is located lower than the upper end portion of the front reinforcement member.

[0024] According to this configuration, by lowering the upper end of the rear reinforcement member so as to correspond to the rear panel portion, the rear panel portion can be made sufficiently lower than the front panel portion, thereby improving occupant comfort. Effect of the Invention

[0025] As described above, a reinforcing member whose upper end is higher than the rear floor portion is provided below the relatively high front floor portion, thereby increasing the strength of the front part of the battery case and suppressing deformation of the cabin and battery case in the event of a frontal collision, while ensuring a large battery capacity and improving occupant living comfort. [Brief description of the drawings]

[0026] [Figure 1] 1 is a side view of an electric vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view showing the electric vehicle separated into a lower structure and an upper structure. [Diagram 3] FIG. 2 is a perspective view of the lower structure seen from above. [Figure 4] FIG. [Diagram 5] FIG. 5 is a view equivalent to FIG. 4 of a lower structure equipped with a small battery case. [Figure 6] FIG. 13 is a left side view of the lower structure when the height of the front central member is increased. [Figure 7] FIG. 2 is a cross-sectional view of the electric vehicle at the center in the left-right direction. [Figure 8] 1 is a cross-sectional view of an electric vehicle seen from the front. [Figure 9] FIG. 2 is a cross-sectional view of the electric vehicle as seen from the rear. [Figure 10] FIG. 2 is a front perspective view showing a cross section passing through the front seat portion of the electric vehicle. [Figure 11] 2 is a diagram showing a floor panel, a front seat, a front seat occupant, and a battery unit. FIG. [Figure 12]11 is an enlarged front view of part C in FIG. 10. FIG. [Figure 13] FIG. 2 is a perspective view from below showing a cross section of the rear part of the electric vehicle. [Figure 14] 13 is a diagram showing a floor panel and a battery unit according to a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely 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 is equipped with a lower structure 2 and an upper structure 3, and the lower structure 2 and the upper structure 3 constitute the vehicle body structure A. FIG. 2 shows a state in which the doors, bonnet hood, front fenders, windshields, bumpers, front and rear lighting devices, etc. have been removed. In the description of this embodiment, the front side of the vehicle will be simply referred to as "front", the rear side of the vehicle will be simply referred to as "rear", the right side of the vehicle will be simply referred to as "right", and the left side of the vehicle will be simply referred to as "left". The left-right direction of the vehicle is the vehicle width direction.

[0029] As shown in Fig. 1, the electric vehicle 1 is a passenger vehicle. As shown in Fig. 2, a front seat S1 is provided at the front of a passenger compartment R1, which is a living space for 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 necessary. The passenger compartment R1 and the luggage compartment R2 are provided in an 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 vehicle interior R1, which is the front part of the electric vehicle 1, can be, for example, a power room R3. That is, the vehicle body structure A includes a driving motor M that generates power for driving the drive wheels, and a battery case 10 that houses a battery B (only shown in FIG. 4) that supplies power to the driving motor M. A power train PT is configured by only the driving motor M, or by the driving motor M together with a reduction gear, a transmission, and the like. Although FIG. 1 and FIG. 2 show a case in which the power train PT is provided only in the power room R3, the power train PT may be provided in the lower space R4 of the luggage compartment R2 (the rear power train is not shown). When the power train PT is provided only in the power room 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 room R3 can be used as a luggage compartment space, etc. When the power train PT is provided in both the power room R3 and the lower space R4, the vehicle becomes a four-wheel drive vehicle. The battery case 10 is disposed below a floor panel 70, which will be described later.

[0031] 3 and 4, the lower structure 2 includes a battery case 10, a front frame member 11 extending forward in front of the battery case 10, and a rear frame member 12 extending 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 typical electric vehicles, the battery case is often separate from the vehicle body and can be attached and detached under the floor, but in this embodiment, not only is the battery case 10 provided, but a front frame member 11 and a rear frame member 12 are integrated into the battery case 10, and the front frame member 11 and the rear frame member 12, together with the battery case 10, can be attached and detached to the upper structure 3.

[0033] Specifically, the electric vehicle 1 of this embodiment is configured to be vertically separable into a lower structure 2 having a battery case 10 and an upper structure 3 forming a vehicle compartment R1 and a luggage compartment R2. Being vertically separable means that the lower structure 2 is integrated with the upper structure 3 using fastening members such as bolts, nuts, and screws, without using welding, adhesives, or the like. This allows the lower structure 2 to be separated from the upper structure 3 as necessary when maintenance or repair is performed after the electric vehicle 1 is delivered to the user, improving maintainability.

[0034] Here, a ladder frame type vehicle body structure is known as a vehicle body structure for automobiles. In the case of a ladder frame type vehicle body structure, it can be divided into a ladder frame and a cabin in an upper and lower part, but since the ladder frame extends continuously in the front-to-rear direction, it mainly bears the collision load in the case of a frontal collision and a rearward collision. In the case of a side collision, the ladder frame only bears the collision load auxiliaryally, and it is the cabin that mainly bears the collision load. In this way, in a ladder frame type vehicle body structure, the members that bear the collision load in the case of a frontal collision and a rearward collision and in the case of a side collision are usually separate.

[0035] In contrast, in the case of the electric vehicle 1 of this embodiment, the lower structure 2 and the upper structure 3 having frame members 11, 12 are separable, but in the case of both a frontal collision, a rear collision, and a side collision, the collision load is received by the lower structure 2 and the upper structure 3, and the collision load is distributed and absorbed by both structures 2, 3, which is a point that significantly differs in technical concept from a conventional ladder frame type vehicle body structure. Below, the structures and effects of the lower structure 2 and the upper structure 3 will be explained in order.

[0036] (Undercarriage) First, the lower structure 2 will be described. As shown in Figures 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 below a floor panel 70 described later, extending from near the left end to near the right end of the floor panel 70 and from near the front end to near the rear end of the floor panel 70. By providing the battery case 10 over a wide area below the floor panel 70 in this manner, it becomes possible to mount a large-capacity battery B in the electric vehicle 1 as shown in FIG. 4. The battery B may be, for example, a lithium-ion battery or an all-solid-state battery, or may be another secondary battery. The battery B may be a so-called battery cell, or may be 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 aluminum alloy extrusion material, but may also be made of an aluminum alloy plate material or a press-formed material of a steel plate. The bottom plate 24 may also be made of an extrusion material. In the following description, "extrusion material" refers to an aluminum alloy extrusion material, and "press-formed material" refers to an aluminum alloy plate material or a press-formed material of a steel plate. Each member may also be made of, for example, a casting.

[0039] The cross-sectional shapes in a direction perpendicular to the longitudinal direction 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. Moreover, the left side member 20, the right side member 21, the front end member 22 and the rear end member 23 are all disposed 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. 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 approximately 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 accommodating space S (shown in FIG. 3) for accommodating a battery B is defined 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 accommodating space S can be changed according to the capacity of the battery B to be mounted. The size of the battery accommodating 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, in the case of a small vehicle with a short wheelbase and 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 the shape of the bottom plate 24 is accordingly made small, so that the battery accommodating space S becomes small according to the small vehicle (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 the shape of the bottom plate 24 is accordingly made large, so that the battery accommodating space S becomes large 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 material, the length can be easily changed. In addition, the bottom plate 24 can also be made of extruded material, so that the shape can be easily changed.

[0042] The upper part of the battery accommodating space S may be closed by a lid (not shown) or by a floor panel 70 (described later). In addition to the battery B, the battery accommodating space S may also be provided with a cooling device for cooling the battery B and a heating device for heating the battery B (temperature control device). Furthermore, the power of the battery B is supplied to the driving motor M via a control device (not shown). Furthermore, 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, 25C are provided as reinforcing members extending in the left-right direction. The first to third battery side cross members 25A, 25B, 25C all have the same height, which is approximately the same as the height of the left side member 20 and the like. The battery side cross members 25A, 25B, 25C may be made of an extruded material or a press-formed material. In this embodiment, three battery side cross members 25A, 25B, 25C are provided, but the number of battery side cross members 25A, 25B, 25C can be increased or decreased depending on the dimension of the battery case 10 in the front-rear direction.

[0044] The first to third battery side cross members 25A, 25B, 25C are disposed at intervals from each other in the front-rear direction, with the first battery side cross member 25A positioned at the front end and the third battery side cross member 25C positioned at the rear end. The lower portions of the battery side cross members 25A, 25B, 25C are fixed to the upper surface of the bottom plate 24. The left end portions of the battery side cross members 25A, 25B, 25C are fixed to the inner surface (right side surface) of the left side member 20, and the right end portions of the battery side cross members 25A, 25B, 25C are fixed to the inner surface (left side surface) of the right side member 21. In other words, the battery side cross members 25A, 25B, 25C are members that connect the left side member 20 and the right side member 21.

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

[0046] A front central member (front reinforcing member) 26 and first to third rear central members (rear reinforcing members) 27-29 are provided inside the battery case 10 as reinforcing members extending in the front-rear direction. The front central member 26 and the first to third rear central members 27-29 are disposed at approximately the same height and are provided in the center of the battery case 10 in the left-right direction. The lower ends of the front central member 26 and the first to third rear central members 27-29 are attached to the upper surface of the bottom plate 24.

[0047] The front central member 26 is disposed between the front end member 22 and the first battery side cross member 25A, with the front end of the front central member 26 fixed to the left-right center of the front end member 22 and the rear end of the front central member 26 fixed to the left-right center of the first battery side cross member 25A. Therefore, the front end member 22 is a member extending to connect the front ends of the left side member 20 and the right side member 21 to the front end of the front central member 26.

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

[0049] When imaginary straight line extending in the front-rear direction in plan view is assumed, the front central member 26 and the first to third rear central members 27-29 are positioned in the left-right direction so as to be disposed on the imaginary straight line. In other words, the first to third rear central members 27-29 are provided so as to be positioned on an imaginary extension line to the rear of the front central member 26. Note that the front central member 26 and the first to third rear central members 27-29 may be configured as a single member that is continuous in the front-rear direction.

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

[0051] 3 and 4, a pair of left and right front frame members 11 are provided, and extend substantially horizontally in a straight line below left and right front side frames 72 described below. Each front frame member 11 can be made of, for example, an extruded material or a press-molded material. In this embodiment, since each front frame member 11 is made of an extruded material, the cross-sectional shape in the direction perpendicular to the front-to-rear direction is substantially uniform from the front end to the rear end.

[0052] The left front frame member 11 is connected to a portion of the front end member 22 constituting the front part of the battery case 10 that is closer to the left of the center in the left-right direction, and this connection portion is located to the right of the left side member 20 of the battery case 10. The right front frame member 11 is connected to a portion of the front end member 22 that is closer to the right of the center in the left-right direction, and this connection portion is located to the left of the right side member 21 of the battery case 10. This provides a predetermined distance between the left and right front frame members 11, making it possible to dispose the lower part of the powertrain PT between the left and right front frame members 11. The distance between the left and right front frame members 11 is set narrower than the distance between the left side member 20 and the right side member 21 of the battery case 10.

[0053] The left and right front frame members 11 are approximately the same height. In addition, the left and right front frame members 11, the front central member 26, the left side member 20, and the right side member 21 of the battery case 10 are disposed at approximately the same height.

[0054] The battery case 10 side (rear side) of each front frame member 11 is connected to the battery case 10 at multiple locations spaced apart from each other in the left-right direction. Specifically, the rear end of the right front frame member 11 is connected to the front end member 22, and a location spaced forward from the rear end of the front frame member 11 is connected to the front end member 22 by an outer connection portion (one connection portion) 30 and an inner connection portion (the other connection portion) 31. This allows the collision load input to the front frame member 11 during a frontal collision to be distributed and transmitted to multiple locations of the battery case 10.

[0055] The outer connection part 30 and the inner connection part 31 are made of a highly rigid member, for example, an extruded material or a press-molded material, and are tubular, plate-like, or columnar. In a plan view, the width of the outer connection part 30 and the inner connection part 31 is set to be wider than the width of the front frame member 11, which further enhances the effect of dispersing the collision load. The width 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 narrower than the width of the front frame member 11.

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

[0057] The right inner connection part 31 is provided at approximately the same height as the right front frame member 11 to the left (inner in the vehicle width direction) of the right front frame member 11, and is inclined with respect to the front-rear direction in a plan view so as to be positioned more leftward as it approaches the rear end. The front end of the right inner connection part 31 is connected to a portion between the front-rear center and the rear end of the front frame member 11 (midway in the front-rear direction). The right inner connection part 31 extends leftward and rearward from the connection portion with the front frame member 11, that is, toward the left-right center of the battery case 10. The rear end of the inner connection part 31 is connected to a portion of the front end member 22 spaced leftward from the rear end of the front frame member 11. 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 points spaced apart from each other in the left-right direction, but this is not limited to the above, and one of the outer connection part 30 and the inner connection part 31 may be omitted and the front frame member 11 may be connected to the front end member 22 at two points, or the rear end of the front frame member 11 may be connected to the front end member 22 only by the outer connection part 30 and the inner connection part 31, without being connected to the front end member 22.

[0059] Incidentally, 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 symmetrical structure to that of the right front frame member 11.

[0060] As shown in FIG. 3, an intermediate connecting member 49, a front connecting member 50, and a rear connecting member 51 are provided in front of the battery case 10 of the lower structure 2 with a gap therebetween in the front-rear direction. The front connecting member 50 extends in the vehicle width direction from the front of the left front frame member 11 to the front of the right front frame member 11, and connects the left front frame member 11 to the right front frame member 11. The rear connecting member 51 extends in the vehicle width direction from the rear of the left front frame member 11 to the rear of the right front frame member 11, and connects the left front frame member 11 to the right front frame member 11. The front connecting member 50 and the rear connecting member 51 are made of, for example, an extrusion material or a press-molded material. 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 having a frame shape in a plan view is formed.

[0061] Moreover, the intermediate connecting member 49 is provided between the front connecting member 50 and the rear connecting member 51, and 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, connecting 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 beyond 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, with the left end of the rear connecting member 51 connected to the side surface of the left front frame member 11 and the right end of the rear connecting member 51 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 a fastening member, or may be fixed by welding, adhesive, or the like.

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

[0064] As shown in Fig. 4, the powertrain PT is disposed rearward of the front connecting member 50. Specifically, in a plan view, the powertrain PT is disposed between the front connecting member 50 and the rear connecting member 51. Drive shafts 52 are provided on the left and right sides of the lower structure 2 to transmit the output of the powertrain PT to the left and right front wheels F, respectively.

[0065] Furthermore, the left and right suspension arms 13a constituting part of the front suspension device 13 are supported by the left and right front frame members 11 via brackets 13b so as to be able to swing freely, respectively. 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 side connecting parts 53, 54 spaced apart from each other in the front-rear direction for connecting the left front frame member 11 to the left front side frame 72 (described later), and two right side connecting parts 55, 56 spaced apart from each other in the front-rear direction for connecting the right front frame member 11 to the right front side frame 72 (described later). The left side connecting parts 53, 54 and the right side connecting parts 55, 56 can be made of a plate material, a tubular member, a columnar member, or the like that extends in the vertical direction. In this embodiment, the left side connecting parts 53, 54 and the right side connecting parts 55, 56 are made of press-formed material, but they may be made of extruded material, or the like. The number of the left side connecting parts 53, 54 is not limited to two, and three or more may be provided spaced apart from each other in the front-rear direction. The same applies to the right side connecting parts 55, 56.

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

[0068] Moreover, the front right side connecting part 55 is provided at a connection portion 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 to overlap in the vertical direction, and the right end portion of the front connecting member 50 is connected to the front portion of the right front frame member 11, so that the connection portion is formed by the right end portion of the front connecting member 50. The lower end portion of the front right side connecting part 55 is attached to the right end portion of the front connecting member 50.

[0069] The rear left side connecting part 54 is provided at a connection portion between the left front frame member 11 and the intermediate connecting member 49. A lower end portion of the rear left side connecting part 54 is attached to the left front frame member 11, and is disposed rearward of the left drive shaft 52. Moreover, the rear right side connecting part 56 is provided at a connection portion between the right front frame member 11 and the intermediate connecting member 49. A lower end portion of the rear right side connecting part 56 is attached to the right front frame member 11, and is disposed rearward of the right drive shaft 52. This makes it possible to widen the distance between the front and rear left side connecting parts 53, 54 and the distance between the front and rear right side connecting parts 55, 56.

[0070] The right front frame member 11 is disposed to the left (inner 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 to the right (inner in the vehicle width direction) of the left front side frame 72 shown in Fig. 2. This makes the distance between the left and right front side frames 72 wider than the distance between the left and right front frame members 11. A powertrain PT including a driving motor M is mounted between the left and right front side frames 72.

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

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

[0073] The left rear frame member 12 is connected to a portion of the rear end member 23 that constitutes the rear of the battery case 10, which is disposed to the left of the center in the left-right direction, and this connection portion is located to the right of the left side member 20 of the battery case 10. In addition, the right rear frame member 12 is connected to a portion of the rear end member 23 that is disposed to the right of the center in the left-right direction, and this connection portion is located to the left 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 end member 22 of the front frame member 11 described above.

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

[0075] Left and right suspension arms 14a constituting part of the rear suspension device 14 are supported by the left and right rear frame members 12 via brackets 14b so as to be able to swing freely, respectively.

[0076] (superstructure) Next, the upper structure 3 will be described. As shown in Fig. 7 to Fig. 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. Fig. 7 to Fig. 10 show a state in which the doors, bonnet hood, front fenders, windshield, bumpers, front and rear lighting devices, some of the seats, interior materials, etc. have been removed.

[0077] The floor panel 70 constitutes the floor surface of the vehicle compartment R1 and is made of a steel plate or the like extending in the front-rear direction as well as the left-right direction. The space above the floor panel 70 forms the vehicle compartment R1. A roof 80 is provided at the upper part of the vehicle compartment R1. As shown in FIG. 2, a front opening 3a and a rear opening 3b are formed on the left side of the upper structure 3. As shown in FIG. 1, the front opening 3a and the rear opening 3b can be opened and closed by a front door 81 and a rear door 82, respectively. Although not shown, a front door and a rear door are also provided on the right side of the upper structure 3 so as to be opened and closed.

[0078] Dash panel 71 is a member for dividing the vehicle compartment R1 and the power compartment R3 in the front-rear direction. Dash panel 71 is made of, for example, a steel plate and extends in the left-right direction as well as the up-down direction. As shown in Figs. 7 to 9, front wheel house sections 85 (only the right one is shown in Figs. 7 to 9) for accommodating left and right front wheels F are provided on both the left and right sides of the front part of upper structure 3. The left end of dash panel 71 is connected to the left front wheel house section 85 (shown in Fig. 2), and the right end of dash panel 71 is connected to the right front wheel house section 85 (shown in Figs. 7 to 9).

[0079] As shown in FIG. 11, the floor panel 70 includes a front floor portion 70a and a rear floor portion 70b. Furthermore, as shown in FIG. 10, the floor panel 70 also includes a kick-up portion 70c at its rear. The front floor portion 70a, the rear floor portion 70b, and the kick-up portion 70c may be integrally formed from a single plate material, or may be formed from different plate materials. When formed from different plate materials, a single floor panel 70 can be constructed by joining multiple plate materials.

[0080] 11, the front floor portion 70a constitutes the front portion of the floor panel 70, and is inclined or curved so that it is positioned higher as it approaches the front. The front end of the front floor portion 70a is connected to the lower end of the dash panel 71. Therefore, the floor panel 70 is provided so as to extend rearward from the lower end of the dash panel 71.

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

[0082] The front-rear direction middle part of the floor panel 70 is lower than the front floor part 70a. That is, the front floor part 70a is provided in front of the rear floor part 70b and is located higher than the rear floor part 70b. At least a part of a seat fixing part 100 for fixing the front seat S1 is attached to the front part of the rear floor part 70b. The seat fixing part 100 is composed of, for example, a bracket. It is sufficient that at least the rear part of the seat fixing part 100 is attached to the rear floor part 70b, and the whole of the seat fixing part 100 may be attached to the rear floor part 70b. By attaching at least the rear part of the seat fixing part 100 to the rear floor part 70b, the front seat S1 can be laid out low, so that the hip point of the front seat occupant P can be lowered, and as a result, the head space of the front seat occupant P is increased, improving habitability. Furthermore, lowering the hip point means that the seating position of the front seat occupant P is lowered, which lowers the center of gravity of the vehicle when in the riding position. In this embodiment, the entire seat fixing part 100 is attached to the rear floor part 70b, so that the front seat S1 can be laid out even lower.

[0083] When a driver as a front seat occupant P sits on the front seat S1, the heel P1 of the front seat occupant P is placed on the front floor part 70a. Since the front floor part 70a on which the heel P1 is placed is positioned higher than the rear floor part 70b, the heel P1 is placed at a higher position than the operating posture of a general automobile (an automobile in which the front floor part and the rear floor part are at the same height). With this layout, the upper leg P2 and the lower leg P3 of the front seat occupant P are placed in a posture with a large spread. In FIG. 11, the reference numeral 101 indicates the center line of the upper leg P2, and the reference numeral 102 indicates the center line of the lower leg P3. The difference in height between the front floor part 70a and the rear floor part 70b is set so that the angle between the center line 101 and the center line 102 (the spread angle α between the upper leg 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 between the lower leg P3 and the front floor part 70a (angle β between the center line 101 and the front floor part 70a) is reduced, so that the vertical component of force input to the heel P1 during pedal operation is reduced, improving the operability of the brake pedal 103. Specifically, when the front seat occupant P depresses the brake pedal 103, the heel P1 applies a diagonally downward force F to the front floor part 70a. If this force F is divided into a vertical force and a horizontal force, they are force F1 and force F2, respectively. As described above, since the angle β is reduced, the vertical component of force F1 input from the heel P1 is reduced. This allows, for example, a change of foot from the brake pedal 103 to the accelerator pedal (not shown) or vice versa to be performed quickly and accurately, improving the operability of the pedal.

[0085] In addition, rear seat passengers may place their feet on the rear floor portion 70b. Since the rear floor portion 70b is lower than the front floor portion 70a, the foot space of the rear seat passengers is increased, improving the habitability of the rear seat passengers.

[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 higher than the rear floor portion 70b, and a vertical plate portion 70d extending in the up-down 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. A rear seat S2 (shown in Fig. 2) is attached to the upper surface of the kick-up portion 70c. A battery B may be disposed below the kick-up portion 70c, or a control device for the electric vehicle 1, etc. (not shown) may be disposed below the kick-up portion 70c.

[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 this embodiment, it bulges upward and opens downward, and has a substantially same cross-sectional shape over both left-right ends. 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 of the floor-side cross member 110 is located near the inner surface of the left side sill 73 in the vehicle width direction, and the right end of the floor-side cross member 110 is located near the inner surface of the right side sill 73 in the vehicle width direction. The floor-side cross member 110 may be attached to the lower surface of the rear floor portion 70b.

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

[0089] The left and right front side frames 72 have a symmetrical structure and can be formed, for example, by joining a plurality of press-formed materials together or by extrusion. The cross section of each front side frame 72 in a direction perpendicular to the front-rear direction is set to be larger than the cross section of the front frame member 11 of the lower structure 2 in the same direction. This makes each front side frame 72 a thicker and stronger member than the front frame member 11.

[0090] The front ends of the left and right front side frames 72 each have a crash can 72a that is compressed and deformed during a frontal collision to absorb collision energy. The crash can 72a is a cylindrical metal member that extends in the front-rear direction. A front bumper reinforcement 86 that extends in the left-right direction is fixed to the front ends of the left and right crash cans 72a.

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

[0092] 5, the lower part of the rear right connecting part 56 is connected to the front frame member 11 rearward of the drive shaft 52, and as shown in Fig. 8, the upper part of the rear right connecting part 56 is connected to a part of the front side frame 72 that is rearward of the center in the fore-and-aft direction. This makes it possible to further increase the distance in the fore-and-aft direction between the right connecting parts 55, 56. The same applies to the left connecting parts 53, 54.

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

[0094] The left and right side sills 73 have a symmetrical structure. The detailed structure of the left side sill 73 will be described below with reference to FIG. 12. The left side sill 73 includes an inner member 90 and an outer member 91 made of press-molded material. The inner member 90 is a member that constitutes the vehicle interior side portion of the side sill 73, and is formed to bulge toward the vehicle interior and to be long in the front-rear direction. The outer member 91 is a member that constitutes the vehicle exterior side portion of the side sill 73, and is formed to bulge toward the vehicle exterior and to be 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 to form the hollow side sill 73.

[0095] A first recess 73a is formed in the lower part of the inner side in the vehicle width direction of the side sill 73 so as to extend in the front-rear direction and recessed outward in the vehicle width 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 2 is formed 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. This makes it possible to ensure a long dimension of the battery case 10 in the vehicle width direction and reduce the downward protrusion of the battery case 10.

[0096] A hollow side load transfer member 120 is provided inside the side sill 73, extending in the front-rear direction and transferring a load from the outside to the inside in the vehicle width direction to the inside in the vehicle width direction. The side load transfer member 120 transfers loads not intended for normal driving, but for extremely large loads that cause deformation of the members on the sides of the electric vehicle 1, such as in the case of a side collision in which an obstacle hits the electric vehicle 1 from the side.

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

[0098] The lateral load transfer member 120 has high rigidity so as to transfer the load during a side collision to the inside in the vehicle width direction, and is therefore resistant not only to compressive forces but also to bending and twisting forces, and functions as a reinforcing member that reinforces the side sill 73 during normal driving and contributes to improving the rigidity of the vehicle body. Since the lateral load transfer member 120 is a member that reinforces the side sill 73 inside the side sill 73, it can be called an inner reinforcement.

[0099] The side 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 in the vicinity of the upper end portion inside the side sill 73. The outer wall portion 122 extends downward from the outer end portion in the vehicle width direction of the upper wall portion 121 and is disposed in the vicinity of the outer end portion in the vehicle width direction inside the side sill 73. The upper end portion of the outer wall portion 122 is located above the upper end portion of the floor-side cross member 110. The lower end portion of the outer wall portion 122 is located below the upper end portion 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 side load transmission member 120 is also approximately the same.

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

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

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

[0103] The lower wall portion 126 extends from the lower end of the inner lower vertical wall portion 124 to the lower end 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, an upper portion of the side load transfer member 120 overlaps with the floor-side cross member 110, and a lower portion of the side load transfer member 120 overlaps with the second battery-side cross member 25B. That is, the side load transfer 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. Note that a lower portion of the inner upper vertical wall portion 123 may overlap with an upper portion of the battery case 10.

[0105] First to fourth ribs 131 to 134 are integrally formed inside the side load transfer member 120. The first rib 131 extends in the vehicle width direction at a location spaced upward from the intermediate wall portion 125, and an inner end portion of the first rib 131 in the vehicle width direction is connected to a vertical intermediate portion of the inner upper vertical wall portion 123. The first rib 131 is inclined so as to be positioned higher as it moves outward in the vehicle width direction.

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

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

[0108] The fourth rib 134 extends in the vehicle width direction at a location spaced upward from the second rib 132. An inner end of the fourth rib 134 in the vehicle width direction is connected to a vertical middle portion of the third rib 133. An outer end of the fourth rib 134 in the vehicle width direction is connected to a vertical middle portion of the outer wall portion 122. An inner end of the fourth rib 134 in the vehicle width direction and an outer end 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 form one rib that is 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 five or more.

[0109] The battery case 10 is fixed to the side sill 73 and is also directly fixed to the side load transmission member 120. A plurality of metallic tubular members 140 extending in the vertical direction are fixed to the left side member 20 of the battery case 10. The intervals between the tubular members 140 in the front-rear direction can be set to, for example, about several tens of centimeters. The plurality of tubular members 140 are arranged at intervals from one another in the front-rear direction as shown in FIG. 2. A bolt 141 is inserted into each tubular member 140 from below.

[0110] Meanwhile, an opening is provided in a portion of the side sill 73 corresponding to the inner surface of the first recess 73a so that the shank of the bolt 141 can be inserted therethrough. Similarly, an opening is provided in the intermediate wall portion 125 of the side load transfer member 120 so that the shank of the bolt 141 can be inserted therethrough, and both openings are aligned. A nut 142 is accommodated inside the side load transfer member 120. The nut 142 is fixed to the upper surface of the intermediate wall portion 125 of the side load transfer member 120. The number and positions of the openings and nuts 142 correspond to the number and positions of the tubular members 140.

[0111] Therefore, by inserting each bolt 141 into the cylindrical member 140, passing it through the openings of the side sill 73 and the openings of the lateral load transmission member 120, and screwing it into the nut 142 and tightening it, it is possible to fix multiple locations on the left side of the battery case 10 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 this embodiment, the side load transfer member 120 is described as being integrally molded, but the present invention is not limited thereto, and the side load transfer member 120 may be configured by combining a plurality of members. Although not shown, for example, the side load transfer member 120 may have a two-piece structure in which an inner portion and an outer portion in the vehicle width direction are molded separately and then integrated. The side load transfer member 120 may also have a three-piece structure.

[0113] As shown in Fig. 7 etc., the upper structure 3 is equipped with 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. Left and right front doors 81 (shown in Fig. 1) are attached to the left and right hinge pillars 150, respectively.

[0114] 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 a middle portion in the front-rear direction of the right side sill 73. As shown in Fig. 2, the left center pillar 157 extends upward from a middle portion in the front-rear direction of the left side sill 73. 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 is provided with a pair of left and right floor reinforcements (first front-rear 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 of the right floor reinforcement 151 is connected to the rear end of the right front side frame 72. The rear end of the right floor reinforcement 151 is connected to the front end 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, for example, when a collision load is input to the front side frame 72 during a frontal collision, the collision load is transmitted to the side sill 73 via the floor reinforcement 151.

[0116] The floor reinforcement 151 bulges upward and opens downward, and this bulging shape continues from the front end to the rear end. 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 positioned outboard in the vehicle width direction relative to the front side frame 72, the floor reinforcement 151 extends while curving in a plan view so that it is positioned more outboard in the vehicle width direction as it moves toward the rear. The curved shape of this floor reinforcement 151 corresponds to the shape of the lower end portion of the front wheel house portion 85. In other words, the floor reinforcement 151 extends along the lower end portion of the front wheel house portion 85, and is connected to and integrated with the front wheel house portion 85. The left floor reinforcement (not shown) has a symmetrical structure to 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, so that the floor reinforcement 151 and the outer connection portion 30 are spaced apart from each other in the vertical direction. Similarly, the floor reinforcement 151 and the inner connection portion 31 are also spaced apart from each other in the vertical direction.

[0119] In addition, in a plan view, a portion of the right floor reinforcement 151 on the side sill 73 side (the rear end of the floor reinforcement 151) and a portion of the right outer connection portion 30 on the battery case 10 side (the rear end of the outer connection portion 30) overlap with each other. The rear end of the floor reinforcement 151 is a portion connected to the side sill 73, so it is disposed adjacent to the side sill 73. On the other hand, the outer connection portion 30 is a member connected to the battery case 10, so it is separated from the side sill 73. However, the fact that the rear end of the outer connection portion 30 overlaps with the rear end of the floor reinforcement 151 in a plan view means that the rear end of the outer connection portion 30 can be brought close to the side sill 73. Therefore, a collision load from the front can be reliably applied toward the side sill 73 side via the outer connection portion 30. The same is true for the left side.

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

[0121] As shown in FIG. 7, the upper structure 3 is provided with a pair of left and right lower load transmission members (second front-rear 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 spaced apart from each other in the up-down direction. The lower load transmission members 152 extend in the front-rear direction along the lower surface of the front floor portion 70a. As shown in FIG. 11, the front end of the right lower load transmission member 152 is connected to the rear end of the right front side frame 72. Since the lower load transmission members 152 extend toward the front of the battery case 10, for example, when a collision load is input rearward to the front side frame 72 during a frontal collision, the collision load is transmitted to the front of the battery case 10 via the lower load transmission members 152. The left lower load transmission member 152 is symmetrical to the right one.

[0122] The lower load transfer member 152 bulges downward and opens upward, and this bulging shape continues from the front end to the rear end. By attaching the lower load transfer member 152 to the underside of the front floor portion 70a, a closed cross section is formed by the lower load transfer member 152 and the front floor portion 70a.

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

[0124] As shown in Figs. 7 to 9, a cross member 153 is disposed on the underside of the front floor portion 70a, extending in the left-right direction and connecting the rear portion of the left lower load transmission member 152 with the rear portion of the right lower load transmission member 152. The cross member 153 bulges downward and opens upward, and has a substantially uniform cross-sectional shape across both left-right ends. By attaching the cross member 153 to the underside 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, it is possible to suppress the rear portion of the lower load transmission member 152 from being displaced in the left-right direction when the left and right lower load transmission members 152 receive a collision load during a frontal collision.

[0125] 11, the front end member 22 constituting the front part 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 with bolts and nuts (not shown). The fastening structure of the front end member 22 can be the same as the fastening structure of the left side member 20 to the side sill 73.

[0126] A protruding portion 22a that protrudes upward is provided at the front of the battery case 10. Specifically, the protruding portion 22a is provided at a portion of the front end member 22 that is rearward of the cross member 153. This protruding portion 22a is located rearward of the rear portion of the lower load transmission member 152. The protruding portion 22a is formed such that its upper end portion is located above the lower surface of the cross member 153 and above the lower surface of the rear portion of the lower load transmission member 152. As a result, the cross member 153 and the lower load transmission member 152 overlap with the protruding portion 22a when viewed in the front-rear direction. The protruding portion 22a is a portion to which a collision load is transmitted from the lower load transmission member 152 when the lower load transmission member 152 moves backward due to a collision load during a frontal collision.

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

[0128] The protruding portion 22a may be integrally molded with the front end member 22, or may be formed as a separate member. When the front end member 22 is an extruded material, the protruding portion 22a can be easily integrally molded. The protruding portion 22a may be fixed to, for example, the bottom plate 24, or may be fixed to the left side member 20 or the right side member 21, etc. The protruding portion 22a may have any shape, for example, a plate shape (rib shape), a rod shape, a tube shape, etc. By integrally molding the protruding portion 22a in a rib shape with the front end member 22, a 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 part 22a are disposed at a predetermined interval in the front-rear direction. By leaving the predetermined interval, the lower load transmission member 152 and the protruding part 22a do not come into contact with each other during normal driving, and therefore, 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 part 22a, so that the collision load is reliably input to the protruding part 22a. In other words, the above-mentioned predetermined interval is an interval set so that the lower load transmission member 152 and the protruding part 22a do not come into contact with each other during normal driving, and the rear part of the lower load transmission member 152 comes into contact with the protruding part 22a during a frontal collision, and can be, for example, about several mm to several cm. The rear part of the lower load transmission member 152 and the protruding part 22a may be brought into contact with each other. Also, the rear part of the lower load transmission member 152 and the protruding part 22a may be connected to each other by a fastening member.

[0130] 6, the front central member 26 in the battery case 10 is provided below the front floor portion 70a, and is taller than the first to third rear central members 27 to 29. Therefore, the vertical dimension of the front central member 26 is longer, and the front central member 26 with a large cross section is located at the front of the battery case 10. This suppresses deformation of the battery case 10 when a collision load transmitted from the lower load transmission member 152 is received at the front of the battery case 10.

[0131] (Connection structure between rear of battery case and upper structure) As shown in FIG. 13, the rear of the battery case 10 and the upper structure 3 are connected by a connecting member 160. Before describing this connecting structure, the rear structure of the upper structure 3 will be described. On both the left and right sides of the rear of the upper structure 3, rear wheel house sections 170 (only the right one is shown in FIGS. 7 to 9) for accommodating the left and right rear wheels R are provided. The luggage compartment floor section 70e constituting the floor surface of the luggage compartment R2 in the floor panel 70 extends rearward from the rear of the kick-up section 70c and is located higher than the rear floor section 70b. The rear floor section 70b is the first floor section, and the kick-up section 70c and the luggage compartment floor section 70e are the second floor section which is relatively higher. The left end of the luggage compartment floor section 70e is connected to the lower part of the left rear wheel house section 170 (shown in FIG. 2), and the right end of the luggage compartment floor section 70e is connected to the right rear wheel house section 170 (shown in FIGS. 7 to 9).

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

[0133] A rear floor side cross member 172 extending in the left-right direction directly above the rear cross member 171 is attached to the upper surface of the kick-up portion 70c. The rear floor side cross member 172 bulges upward and opens downward, with this bulging shape continuing 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 a plan view, the rear floor side cross member 172 and the rear cross member 171 overlap.

[0134] The right end of the rear floor cross member 172 is connected to the right rear wheel house section 170, and the left end of the rear floor cross member 172 is connected to the left rear wheel house section 170. The right end of the rear floor cross member 172 is connected to the lower end of a side reinforcement 173 extending upward along the right rear wheel house section 170. The left end of the rear floor cross member 172 is connected to the lower end of a side reinforcement (not shown) extending upward along the left rear wheel house section 170. 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 cross member 172, the left and right side reinforcements 173, and the connecting member 174. The annular structure may be formed by 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 the rear end member 23 that constitutes the rear 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 disposed so as to face each other in the up-down 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. As a result, the kick-up portion 70c is reinforced by utilizing the battery case 10, and the rigidity of the kick-up portion 70c is improved. The improved rigidity of the kick-up portion 70c also improves the rigidity of the entire floor panel 70. In this embodiment, the connecting member 160 is made of a plate material extending in the left-right and up-down directions, but is not limited thereto, and may be a member with a closed cross section extending in the up-down direction or obliquely, an axial member, a cylindrical member, or the like. Also, a plurality of connecting members 160 may be provided.

[0137] An upper portion of the connecting member 160 is fixed to a lower portion of the rear cross member 171. As a result, 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 portion of the connecting member 160 can be fixed to a portion whose rigidity has been 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. The fixing structure of the upper portion of the connecting member 160 can be a detachable fastening structure using fastening members such as bolts and nuts (not shown). The upper portion of the connecting member 160 may be directly connected to the kick-up portion 70c.

[0138] Further, the lower part of the connecting member 160 is fixed to a case-side cross member 180 constituting a part of the battery case 10. This allows the lower part of the connecting member 160 to be fixed to a part of the battery case 10 with improved rigidity, thereby increasing the fixing strength of the connecting member 160 to the battery case 10. Note that the lower part of the connecting member 160 may be detachably fixed to the battery case 10 by the fastening member. The connecting member 160 may be a component member on the upper structure 3 side or a component member on the lower structure 2 side.

[0139] (Relative position of the upper structure and lower structure cross members) 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 modified embodiment. First to third floor-side cross members 110A, 110B, 110C extending in the vehicle width direction are attached to the upper surface of the floor panel 70 of the upper structure 3, and a cross member 153 is attached to the underside 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 cross member 110A is the above-mentioned cross member 110, and is disposed rearwardly away from the cross member 153. The second floor cross member 110B is disposed rearwardly away from the first floor cross member 110A. The third floor cross member 110C is disposed rearwardly away from the second floor cross member 110B. Meanwhile, the above-mentioned first to third battery side cross members 25A, 25B, 25C are provided in 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, 110C and the first to third battery side cross members 25A, 25B, 25C overlap with the side sill 73 (shown in FIG. 10, etc.).

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

[0142] For example, when looking at 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 looking at 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. This positional relationship is referred to as being "displaced in the fore-and-aft direction of the vehicle."

[0143] In addition, "displaced in the vehicle fore-and-aft direction" may include other configurations. For example, it may include a configuration in which the fore-and-aft center of the first floor-side cross member 110A and the fore-and-aft center of the second battery-side cross member 25B are offset in the fore-and-aft direction. In this case, the configuration shown in FIG. 14 is also included, but it also includes a configuration in which, for example, 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 a positional relationship that overlaps in a plan view.

[0144] In addition, for example, a configuration in which the front portion of the first floor side cross member 110A is located in front of the front portion of the second battery side cross member 25B, and a configuration in which the rear portion of the second battery side cross member 25B is located behind the rear portion of the first floor side cross member 110A are also included in the term "displaced in the fore-and-aft direction of the vehicle."

[0145] During a side collision, the collision load can be received by 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. Because 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 offset in the front-to-rear direction of the vehicle 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 area that does not overlap with the hinge pillar 150 (shown by a virtual line in FIG. 14) are shifted in the fore-aft direction. In other words, the floor-side cross-members 110A, 110B, 110C and the battery-side cross-members 25A, 25B, 25C located rearward of the hinge pillar 150 are shifted in the fore-aft direction. In other words, since the area where the hinge pillar 150 is located has high strength against a collision load from the side, the collision load can be received by the hinge pillar 150 even if the floor-side cross-member and the battery-side cross-member are not shifted in the fore-aft direction.

[0147] Similarly, only the floor-side cross-members 110A, 110C and the battery-side cross-members 25A, 25B, 25C in the area that does not overlap with the center pillar 157 in a side view of the vehicle may be shifted in the front-rear direction.

[0148] (Effective in the event of a frontal collision) Next, a case where the electric vehicle 1 configured as described above is involved in a frontal collision 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. The collision load during a frontal collision is also input to the left and right front frame members 11.

[0149] With regard to the front frame member 11, a plurality of portions of the front frame member 11 spaced apart in the fore-and-aft direction are connected to the left front side frame 72 by the left connecting portions 53, 54, respectively, so that the left front frame member 11 to which a collision load is input is stabilized and is less likely to tilt in the left-right or up-down directions. The same is true for the right front frame member 11. As a result, the collision load is transmitted linearly to the front 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 by the outer connection portion 30 and the inner connection portion 31 at multiple locations spaced apart from each other in the left-right direction, the collision load input to the front frame member 11 is input to multiple locations in the battery case 10 spaced apart in the left-right direction. Since the battery case 10 includes the front central member 26, the left side member 20, and the right side member 21 that extend in the front-rear direction, the collision load input to the multiple locations spaced apart in the left-right direction is distributed and transmitted to the front central member 26, the left side member 20, and the right side member 21. This makes it possible to actively utilize the battery case 10 to absorb the collision load, so that the amount of the 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 in the vicinity of the rear end portion of the front side frame 72 can be optimized to achieve a reduction in the weight of the entire vehicle.

[0151] Moreover, the collision load input to the front side frame 72 is transmitted to the side sill 73 via the floor reinforcement 151. Moreover, since the outer connection portion 30 extends toward the side sill 73, the collision load input to the front frame member 11 can also be applied toward the side sill 73 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 are different routes, and therefore the collision load is transmitted to the side sill 73 via multiple routes. Since the side sill 73 is a particularly high-rigidity member among the members constituting the vehicle body, the collision load can be absorbed by the side sill 73.

[0152] Furthermore, the collision load input to the front side frame 72 is transmitted from the rear of the front side frame 72 to the battery case 10 via both the floor reinforcement 151 and the lower load transmission member 152. This also forms a route for the collision load to be transmitted to the battery case 10 via the lower load transmission member 152, so that the collision load is dispersed and absorbed by both the side sill 73 and the battery case 10. Furthermore, because the floor reinforcement 151 and the lower load transmission member 152 are aligned along the floor panel 70, 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, and 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 effect can be achieved.

[0154] (Effective in the event of a side collision) Next, a case where the electric vehicle 1 configured as described above is subjected to a side collision will be described. The collision load during a side collision is input to the side sill 73 from the outside to the inside in the vehicle width direction. Since the side load transmission member 120 is provided inside the 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, 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, so that the collision load is distributed 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 a high resistance to the load from the side, and thus a part of the collision load is absorbed, reducing the collision load input to the battery case 10, and the battery B is protected. Furthermore, since the battery case 10 is provided with the first to third battery side cross members 25A, 25B, 25C, the front end member 22 and the rear end member 23, the battery case 10 can also absorb the collision load.

[0155] Also, when an obstacle such as a pole collides with the vehicle from the side, as shown in Fig. 14, the cross member 153 and the first to third floor side cross members 110A, 110B, 110C are offset from the first to third battery side cross members 25A, 25B, 25C in the vehicle front-rear direction, so that the collision load can be input to one of the cross members. It is also possible 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 distributed and absorbed by at least the first floor side cross member 110A and the second battery side cross member 25B.

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

[0157] The above-described embodiment is merely illustrative in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [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 symbols]

[0159] 1. Electric vehicles 10 Battery case 11 Front frame member 20 Left side member 21 Right side member 22 Front end member 22a Protrusion 25A, 25B, 25C 1st to 3rd battery side cross members 26 Front center member (front reinforcing member) 27~29 1st~3rd rear central members (rear reinforcement members) 30 Outer connection part (one side connection part) 31 Inner connection part (other connection part) 53, 54 Left side connection part 55, 56 Right side connection part 70 Floor Panel 70a Front floor 70b Rear floor section (first floor section) 70c kick up section (2nd floor section) 72 Front side frame 73 Side sill 100 Seat fixing part 110A, 110B, 110C 1st to 3rd floor cross members 120 Lateral load transfer member (inner reinforcement) 123 Inner upper vertical wall section (first vertical wall section) 124 Inner lower vertical wall (second vertical wall) 150 Hinge pillar 151 Floor reinforcement (first longitudinal load transmission member) 152 Lower load transmission member (second front-rear load transmission member) 153 Cross member 160 Connecting member 170 Rear wheel house 171 Rear cross member (first cross member) 180 Case side cross member (second cross member) A. Body structure B Battery M Driving motor

Claims

1. A vehicle body structure for an electric vehicle including a driving motor and a battery case housing a battery that supplies power to the driving motor and is disposed below a floor panel, A pair of left and right front side frames disposed at a front portion of the vehicle body and extending in a front-rear direction of the vehicle; a front-rear load transmission member extending from a vehicle rear portion of each of the left and right front side frames toward a vehicle front portion of the battery case, the floor panel has a rear floor portion to which at least a part of a seat fixing portion for fixing a front seat is attached, and a front floor portion that is provided in front of the rear floor portion and located higher than the rear floor portion, the battery case is formed so as to extend from below the front floor portion to below the rear floor portion, A vehicle body structure in which a front reinforcing member is provided below the front floor portion of the battery case, the front reinforcing member extending in the front-to-rear direction of the vehicle and formed so that an upper end portion is positioned above the rear floor portion.

2. The vehicle body structure according to claim 1, A vehicle body structure in which the front reinforcement member is provided at the center of the battery case in the vehicle width direction.

3. The vehicle body structure according to claim 1 or 2, A vehicle body structure in which an end member extending in a vehicle width direction is provided at a vehicle front end portion of the battery case.

4. The vehicle body structure according to any one of claims 1 to 3, A vehicle body structure in which the entire seat fixing portion is attached to the rear floor portion.

5. The vehicle body structure according to any one of claims 1 to 4, A vehicle body structure in which a rear reinforcing member extending in a front-to-rear direction of the vehicle is provided below the rear floor portion of the battery case so as to be located on an imaginary extension line of the front reinforcing member toward the rear of the vehicle.

6. The vehicle body structure according to claim 5, Lower ends of the front reinforcing member and the rear reinforcing member are attached to a bottom plate of the battery case, A vehicle body structure, wherein an upper end portion of the rear reinforcement member is located lower than an upper end portion of the front reinforcement member.

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