Underbody structure of electric vehicles

Abstract

This design ensures ample legroom in the rear seats and prevents contact between the floor panel and the battery unit. [Solution] The vehicle understructure 100 of the electric vehicle includes a floor panel 1, a pair of side members 2,2, and a floor reinforcement panel 7 which is positioned on the upper surface 1c1 of the rear seat footwell panel portion 1c, which is the portion of the floor panel 1 between the lower part of the seating portion S1a of the front seat S1 and the lower part of the seating portion S2a of the rear seat S2 in the vehicle longitudinal direction, and is joined to the upper surface 1c1. The battery unit 5 is positioned below the floor panel 1, and the seating portion S2a of the rear seat S2 has a first seating portion S2a1 on one side in the vehicle width direction and a second seating portion S2a2 on the other side in the vehicle width direction. The floor reinforcement panel 7 is provided in a predetermined range W that fits inside the outer shape of the battery unit 5 in a plan view from one side in the vehicle vertical direction, and includes at least a portion located forward of the center of the first seating portion S2a1 in the vehicle width direction and a portion located forward of the center of the second seating portion S2a2 in the vehicle width direction.

Description

[Technical Field]

[0001] The present invention relates to a vehicle underbody structure for an electric vehicle. [Background Art]

[0002] Below a floor panel of an electric vehicle such as an electric vehicle that uses an electric motor as a power source for vehicle travel, or a hybrid vehicle that uses a combination of an electric motor and an internal combustion engine as a power source, a battery unit for supplying electric power to the electric motor is disposed. In recent years, battery units have been increasing in size, and a structure for arranging a large-sized battery unit below a floor panel is sometimes applied to a vehicle underbody structure of an electric vehicle.

[0003] As an example of a vehicle underbody structure having a structure for arranging a large-sized battery unit below a floor panel, the structure disclosed in Patent Document 1 is known. In the structure disclosed in Patent Document 1, a front seat and a rear seat are arranged on a floor panel, and a battery pack (hereinafter referred to as a battery unit) extends below the floor panel in a range corresponding to a range extending from the feet of an occupant seated in the front seat to a position below the rear seat. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2013-86609 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Incidentally, the space around the rear seats in a vehicle tends to be cramped, so there is a demand for ample legroom for rear-seat passengers. From this perspective, adopting a structure that brings the floor panel and the top surface of the battery unit close together is a possibility. However, simply bringing the floor panel and the top surface of the battery unit close together may cause contact between the floor panel and the battery unit, so some ingenuity may be required to prevent this.

[0006] Therefore, the present invention aims to provide an undercarriage structure for an electric vehicle that can prevent contact between the floor panel and the battery unit while ensuring sufficient legroom for the rear seats. [Means for solving the problem]

[0007] To achieve the above objective, according to one aspect of the present invention, a vehicle understructure for an electric vehicle is provided, comprising a floor panel constituting the bottom of a passenger compartment in which front and rear seats are provided, and a pair of side members extending in the longitudinal direction of the vehicle along the outer portion of the floor panel in the vehicle width direction, wherein a battery unit is disposed below the floor panel. The vehicle understructure for the electric vehicle includes a floor reinforcement panel disposed on the upper surface of the rear seat footwell panel portion of the floor panel, which is the portion between the portion below the seating area of ​​the front seat and the portion below the seating area of ​​the rear seat in the longitudinal direction of the vehicle, and joined to the upper surface, wherein the seating area of ​​the rear seat has a first seating area on one side in the vehicle width direction and a second seating area on the other side in the vehicle width direction, and the floor reinforcement panel is provided in a predetermined range that fits inside the outer shape of the battery unit in a plan view from one side in the vertical direction of the vehicle, and includes at least a portion located forward of the center of the first seating area in the vehicle width direction and a portion located forward of the center of the second seating area in the vehicle width direction. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide an undercarriage structure for an electric vehicle that can prevent contact between the floor panel and the battery unit while ensuring sufficient legroom for the rear seats. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of the undercarriage structure of an electric vehicle according to an embodiment of the present invention. [Figure 2] This is a top view of the vehicle's understructure. [Figure 3] This is a partial cross-sectional view along line AA shown in Figure 2. [Figure 4] This is an enlarged top view of the main parts of the vehicle's understructure. [Figure 5] This is a partial cross-sectional view along the BB line shown in Figure 4. [Figure 6] Figure 4 shows an enlarged perspective cross-sectional view along the CC line. [Figure 7] This is an enlarged top view of the main part of the undercarriage structure of the modified vehicle. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figures 1 to 3 are diagrams illustrating the vehicle understructure 100 of an electric vehicle according to one embodiment of the present invention. Figure 1 is a perspective view, Figure 2 is a top view, and Figure 3 is a partial cross-sectional view along line AA shown in Figure 2. In each of the figures described below, the direction of arrow Fr indicates the front in the vehicle's longitudinal direction, the direction of arrow U indicates the upward direction in the vehicle's vertical direction, and the directions of arrows R and L indicate the right and left in the vehicle width direction when viewing the front of the vehicle from inside the passenger compartment.

[0011] (Overview of the vehicle's undercarriage) Referring to Figures 1 to 3, the vehicle understructure 100 includes a floor panel 1 and a pair of side members 2, 2. In this embodiment, the vehicle understructure 100 further includes an upper front cross member 3 and an under rear cross member 4. The vehicle understructure 100 is applied to the understructure of electric vehicles, such as electric vehicles that use an electric motor as a power source for vehicle propulsion, or hybrid vehicles that use a combination of an electric motor and an internal combustion engine as a power source.

[0012] The floor panel 1 is a panel member that constitutes the bottom of the passenger compartment V where the front seat S1 and rear seat S2 are located. Below the floor panel 1 is a battery unit 5 for supplying power to the electric motor (not shown). In other words, the front seat S1 and rear seat S2 are located above the floor panel 1, and the battery unit 5 is located below the floor panel 1. The floor panel 1 forms a floor section that separates the space inside the passenger compartment V where the front seat S1 and rear seat S2 are located from the space outside the vehicle. The floor panel 1 is a member made of steel plate that extends from the lower part of the front of the passenger compartment (e.g., the dashboard panel) toward the rear of the vehicle. The width dimension of the floor panel 1 is approximately the width dimension of the vehicle body.

[0013] In the illustrated example, a driver's seat S1 and a passenger seat S1 are provided in the front area of ​​the passenger compartment V, spaced apart from each other in the vehicle width direction. In other words, two separate front seats S1 are positioned above the floor panel 1. Each front seat S1 has a seating area S1a in which the occupant sits, and a seat back S1b that is rotatably attached to the rear of the seating area S1a.

[0014] The rear seat S2 is located in the vehicle compartment V, at a position rearward from the seating area S1a of the front seat S1. The width dimension of the rear seat S2 is approximately the same as the width dimension of the vehicle compartment V. The rear seat S2 has a seating area S2a where the occupant sits, and a seat back S2b that is rotatably attached to the rear of the seating area S2a. The front end of the seating area S2a of the rear seat S2 is rearward from the rear end of the seating area S1a of the front seat S1.

[0015] The seating portion S2a of the rear seat S2 has at least a first seating portion S2a1 on one side in the vehicle width direction and a second seating portion S2a2 on the other side in the vehicle width direction. The rear seat S2 is a so-called bench seat type seat that is not separated on the left and right sides. Although not particularly limited, in the illustrated example, the one side in the vehicle width direction is the right side in the vehicle width direction when looking at the front of the vehicle from inside the passenger compartment V, and the other side in the vehicle width direction is the left side in the vehicle width direction when looking at the front of the vehicle from inside the passenger compartment V. The first seating portion S2a1 and the second seating portion S2a2 are formed integrally and continuously with respect to each other. A seat back S2b is provided on each of the first seating portion S2a1 and the second seating portion S2a2, and the left and right seat backs S2b are rotatable independently of each other. When viewed from above the vehicle, in the rear seat S2, the first seat center line L1, which passes through the widthwise center of the first seating area S2a1, passes through the widthwise center of the headrest S2c at the top of the seatback S2b attached to the first seating area S2a1. Similarly, the second seat center line L2, which passes through the widthwise center of the second seating area S2a2, passes through the widthwise center of the headrest S2c at the top of the seatback S2b attached to the second seating area S2a2.

[0016] The floor panel 1 includes a front seat under panel section 1a, a rear seat under panel section 1b, and a rear seat footwell panel section 1c. The floor panel 1 further includes a front seat footwell panel section 1d, a dash panel connecting panel section 1e, and a rear panel section 1f.

[0017] The front under-seat panel portion 1a is a portion of the floor panel 1 located below the seating portion S1a of the front seat S1. The rear under-seat panel portion 1b is a portion of the floor panel 1 located below the seating portion S2a of the rear seat S2. The rear foot panel portion 1c is a portion of the floor panel 1 located between the front under-seat panel portion 1a and the rear under-seat panel portion 1b in the vehicle front-rear direction. The front foot panel portion 1d is a portion extending forward from the front under-seat panel portion 1a in the floor panel 1. The dash panel connection panel portion 1e is a portion of the floor panel 1 that continuously extends forward from the front foot panel portion 1d and extends to curve upward. The rear panel portion 1f is a portion extending rearward from the rear under-seat panel portion 1b in the floor panel 1. That is, the regions of the floor panel 1 in the vehicle front-rear direction are divided, in order from the front, into the dash panel connection panel portion 1e, the front foot panel portion 1d, the front under-seat panel portion 1a, the rear foot panel portion 1c, the rear under-seat panel portion 1b, and the rear panel portion 1f. The feet of an occupant seated on the seating portion S1a of the front seat S1 are placed on the front foot panel portion 1d, and the feet of an occupant seated on the seating portion S2a of the rear seat S2 can be placed on the rear foot panel portion 1c.

[0018] In the present embodiment, the floor panel 1 is composed of a main floor panel 1M including the front under-seat panel portion 1a and the rear foot panel portion 1c of the floor panel 1, and a rear floor panel 1R including the rear under-seat panel portion 1b of the floor panel 1. A rear end portion 1Ma of the main floor panel 1M and a front end portion 1Ra of the rear floor panel 1R are vertically overlapped with each other and joined to each other by spot welding or the like. In the illustrated example, the main floor panel 1M further includes the front foot panel portion 1d and the dash panel connection panel portion 1e, and the rear floor panel 1R further includes the rear panel portion 1f.

[0019] The main floor panel 1M includes a floor tunnel 10. The floor tunnel 10 bulges upward of the vehicle at the central portion of the main floor panel 1M in the vehicle width direction, and extends in the vehicle front-rear direction. The floor tunnel 10 extends over the entire length of the main floor panel 1M in the vehicle front-rear direction. In the illustrated example, the floor tunnel 10 is formed integrally with other portions of the main floor panel 1M, and has a groove-shaped cross-section that opens toward the lower side of the vehicle when viewed in the vehicle front-rear direction. The floor tunnel 10 bulges upward of the vehicle with a substantially trapezoidal outer shape.

[0020] In the illustrated example, a rear seat lower panel portion 1b of the rear floor panel 1R includes a front flange portion 1b1 and a bulging portion 1b2. A front edge (front end portion) of the front flange portion 1b1 constitutes a front end portion 1Ra of the rear floor panel 1R, and extends in the vehicle front-rear direction and the vehicle width direction. The bulging portion 1b2 occupies most of the area including the center of the rear seat lower panel portion 1b, and bulges upward of the vehicle. A front wall of the bulging portion 1b2 is continuous with the rear end of the front flange portion 1b1, and constitutes an inclined front wall 1b21 that extends rearward of the vehicle and obliquely upward from the rear end.

[0021] The pair of side members 2, 2 extend in the vehicle front-rear direction along the outer portion of the floor panel 1 in the vehicle width direction. That is, the pair of side members 2, 2 are spaced apart from each other in the vehicle width direction, and each side member 2 extends along the outer portion of the floor panel 1 in the vehicle width direction. The side member 2 is composed of a side sill 2A provided at a position generally corresponding to the main floor panel 1M, and a rear side member 2B provided at a position generally corresponding to the rear floor panel 1R. A front portion of the rear side member 2B is overlapped on a side sill side wall 2A1 facing inward in the vehicle width direction at a rear portion of the side sill 2A, and extends along the side sill side wall 2A1.

[0022] More specifically, the side sill 2A has a hat-shaped cross-section that opens outward in the vehicle width direction. The outer edge of the main floor panel 1M in the vehicle width direction is joined to the upper surface of the side sill upper wall 2A2 of the side sill 2A by spot welding or the like. The rear side member 2B has a roughly groove-shaped cross-section that opens upward, for example, towards the vehicle. The outer edge of the rear floor panel 1R in the vehicle width direction is joined to the rear side member 2B from above the vehicle by spot welding or the like so as to close the opening of the rear side member 2B. The lower part of the side member 2, which consists of the side sill 2A and the rear side member 2B, protrudes downward relative to the lower surface of the floor panel 1.

[0023] Referring to Figure 3, the rear side member 2B has an inclined member portion 2B1 that extends diagonally upward and rearward from the front end which is joined to the side sill 2A, and a straight member portion 2B2 that extends linearly rearward from the rear end of the inclined member portion 2B1 to the rear end of the side member 2.

[0024] The upper floor cross member 3 extends in the vehicle width direction along the upper surface of the front seat under panel portion 1a of the floor panel 1 and is a member for connecting a pair of side members 2, 2. In the illustrated example, the upper floor cross member 3 is provided at the front end portion and the rear end portion of the front seat under panel portion 1a, respectively. In other words, a pair of upper floor cross members 3, 3 are arranged on the upper surface of the front seat under panel portion 1a, spaced apart from each other in the vehicle's longitudinal direction. Each upper floor cross member 3 is joined to the upper surface of the floor panel 1 (front seat under panel portion 1a) by spot welding or the like and protrudes upward from the vehicle. Each upper floor cross member 3 is joined to the floor tunnel 10 from above the vehicle, overlapping the floor tunnel 10, and intersects the floor tunnel 10 when viewed from above the vehicle.

[0025] Each floor-mounted front cross member 3 has a roughly hat-shaped cross section that opens downwards towards the vehicle. Four front seat brackets S3 are attached to the upper surface of each floor-mounted front cross member 3. The front seat brackets S3 are provided on the upper surface of each floor-mounted front cross member 3 at two locations corresponding to the seating portion S1a of the right front seat S1 and at two locations corresponding to the seating portion S1a of the left front seat S1. A seat slide rail (not shown) is provided to connect the upper parts of two front seat brackets S3 that are aligned in the longitudinal direction of the vehicle, and the seating portion S1a of each front seat S1 is positioned on the floor panel 1 so as to be slidable in the longitudinal direction of the vehicle via the two seat slide rails. The lower front seat panel portion 1a, which is the part of the floor panel 1 below the seating portion S1a of the front seat S1, is set to a range that corresponds, for example, to the sliding range of the seating portion S1a by the slide rail when viewed from above the vehicle.

[0026] The vehicle width end of each floor front cross member 3 extends to the vicinity of the vehicle width outer edge of the main floor panel 1M. The front seat bracket S3 located on the outermost side in the vehicle width direction of the multiple front seat brackets S3 is joined to the upper surface of the side sill upper wall 2A2 of the side member 2 (side sill 2A) and the floor front cross member 3 by spot welding or the like. Thus, the floor front cross member 3 connects a pair of side members 2,2 by joining its vehicle width end to the corresponding side member 2 via the front seat bracket S3.

[0027] The underfloor rear cross member 4 extends in the vehicle width direction along the underside of the rear seat under panel portion 1b of the floor panel 1 and is a member that connects a pair of side members 2,2 (here, a pair of rear side members 2B,2B). In the illustrated example, the underfloor rear cross member 4 extends in the vehicle width direction along the rear corner portion 1b3 so as to cover the rear corner portion 1b3 formed by the front flange portion 1b1 and the inclined front wall 1b21 of the rear seat under panel portion 1b from below. In other words, the underfloor rear cross member 4 is positioned at the rear corner portion 1b3 of the underside of the rear seat under panel portion 1b. The underfloor rear cross member 4 is joined to the floor panel 1 (rear seat under panel portion 1b) and protrudes downward from the vehicle.

[0028] The underbody rear cross member 4 has a roughly hat-shaped cross section that opens upwards towards the vehicle. Multiple (four in the illustrated example) rear seat brackets S4 are attached to the upper surface of the rear seat lower panel 1b. The rear seat brackets S4 are provided at the front of the bulging portion 1b2 of the rear seat lower panel 1b. The seating portion S2a of the rear seat S2 (first seating portion S2a1 and second seating portion S2a2) is positioned on the floor panel 1 (rear floor panel 1R) by being attached to the multiple rear seat brackets S4. The ends of the underbody rear cross member 4 in the vehicle width direction are joined to the corresponding side members 2 (rear side members 2B).

[0029] As mentioned above, the battery unit 5 is located below the floor panel 1. The battery unit 5 has a generally box-shaped exterior with a height in the vertical direction of the vehicle that is approximately the same as the height of the side sill 2A. The space (allowable placement space) for arranging the battery unit 5 below the floor panel 1 extends outward in the vehicle width direction to the inner side surface in the vehicle width direction of the inner side wall of the side member 2 (side sill side wall 2A1 of the side sill 2A).

[0030] In general, a certain minimum ground clearance must be ensured at the underside of the vehicle, which is the distance from the road surface to the lowest point of the underside of the vehicle body. When the battery unit is located below the floor panel, from the standpoint of ensuring minimum ground clearance, it is conceivable to offset the height of the floor panel towards the interior of the vehicle. However, this would reduce the interior space (especially the legroom for passengers sitting in the rear seats), which is undesirable from the standpoint of ensuring interior space. Considering both the need to ensure interior space and minimum ground clearance, the understructure 100 of the vehicle is positioned as close as possible to the underside of the floor panel 1, as in conventional designs. However, to prevent contact between the battery unit 5 and the floor panel 1, the understructure 100 of the vehicle has the structure described below.

[0031] (Detailed structure of the vehicle's undercarriage) Next, the detailed structure of the vehicle understructure 100 will be explained, focusing mainly on the rear seat footwell panel 1c of the floor panel 1 and the surrounding structure. Figure 4 is an enlarged top view of the main part of the vehicle understructure 100 including the rear seat footwell panel 1c, Figure 5 is a partial cross-sectional view along the BB line shown in Figure 4, and Figure 6 is an enlarged perspective cross-sectional view of section C shown in Figure 5.

[0032] Referring to Figures 2 to 5, in the vehicle understructure 100, the battery unit 5 extends over approximately the entire area below the main floor panel 1M of the floor panel 1 in the longitudinal direction of the vehicle. In the illustrated example, the front end of the battery unit 5 is located below the front part of the main floor panel 1M (specifically, the front part of the front seat footwell panel 1d) in the longitudinal direction of the vehicle, and the rear end of the battery unit 5 extends beyond the rear end 1Ma of the main floor panel 1M and the inclined front wall 1b21 of the bulge 1b2 of the rear floor panel 1R to the rear of the vehicle, and is located below the central part of the bulge 1b2 in the longitudinal direction of the vehicle.

[0033] The battery unit 5 is attached to the side member 2 via a battery holding member 6. The battery holding member 6 is a member for attaching the outer portion of the battery unit 5 in the vehicle width direction to the side member 2, and for example, has a rectangular cylindrical cross-sectional shape and extends in the longitudinal direction of the vehicle. In the illustrated example, the battery holding member 6 has a generally trapezoidal outer shape when viewed from the top or bottom direction of the vehicle in a plan view. The battery unit 5 has a battery flange 5b that protrudes outward in the vehicle width direction from the battery outer surface 5a, which is the outer side in the vehicle width direction. In the illustrated example, the battery bottom surface 5c, which is the bottom surface of the battery unit 5, is located below the bottom surface 2a of the side member 2 (specifically, the side sill 2A) in the vehicle vertical direction. The upper part of the battery outer surface 5a faces the side sill side wall 2A1 of the side sill 2A.

[0034] In the illustrated example, the battery holding member 6 extends in the longitudinal direction of the vehicle, generally from the front seat lower panel 1a to the rear seat footwell panel 1c. The battery holding member 6 is fixed to the lower surface 2a of the side member 2 (side sill 2A) by fasteners such as bolts (not shown), and protrudes inward in the vehicle width direction from the side sill side wall 2A1 of the side sill 2A. The inner end of the battery holding member 6 in the vehicle width direction abuts against the lower surface of the battery flange 5b and is fixed to the battery flange 5b by fasteners such as bolts (not shown). In this way, the battery unit 5 is attached to the side member 2 so as to connect the pair of side members 2,2 (a pair of side sills 2A,2A) via the left and right battery holding members 6.

[0035] Referring to Figures 1, 2, and 4 through 6, the vehicle understructure 100 includes a floor reinforcement panel 7. The floor reinforcement panel 7 is positioned on the upper surface 1c1 of the rear seat footwell panel portion 1c of the floor panel 1 and is joined to the upper surface 1c1. The floor reinforcement panel 7 is a steel plate panel for reinforcing the floor panel 1 from above, that is, a flattened member in the vehicle's vertical direction, and is joined to the floor panel 1 by spot welding or the like. The floor reinforcement panel 7 is not a member that has a certain height in the vehicle's vertical direction, like the floor front cross member 3. The floor reinforcement panel 7, like the underbody flattened cross member 8 described later, has a height (total height) in the vehicle's vertical direction that is sufficiently lower than, for example, the protruding height of the floor front cross member 3 in the vehicle's vertical direction, and is formed in a flattened shape in the vehicle's vertical direction.

[0036] The floor reinforcement panel 7 is provided in a predetermined range W that fits inside the outer shape of the battery unit 5 in a plan view taken from one side in the vertical direction of the vehicle. The predetermined range W includes at least a portion located forward of the center in the vehicle width direction of the first seating portion S2a1 of the rear seat S2, and a portion located forward of the center in the vehicle width direction of the second seating portion S2a2 of the rear seat S2. In the illustrated example, the predetermined range W is divided into the first seating portion S2a1 side (right side) and the second seating portion S2a2 side (left side). Specifically, the portion of the predetermined range W located forward of the center in the vehicle width direction of the first seating portion S2a1 intersects with the first seating center line L1 in the rear seat footwell panel portion 1c and has a predetermined width in the vehicle width direction, and the portion of the predetermined range W located forward of the center in the vehicle width direction of the second seating portion S2a2 intersects with the second seating center line L2 in the rear seat footwell panel portion 1c and has a predetermined width in the vehicle width direction.

[0037] In this embodiment, the floor reinforcement panel 7 consists of a first floor reinforcement panel 7A and a second floor reinforcement panel 7B that are spaced apart from each other in the vehicle width direction. The first floor reinforcement panel 7A is located forward of the vehicle width direction center of the first seating area S2a1 on the upper surface 1c1 of the rear seat footwell panel 1c, and the second floor reinforcement panel 7B is located forward of the vehicle width direction center of the second seating area S2a2 on the upper surface 1c1 of the rear seat footwell panel 1c.

[0038] In the illustrated example, the first floor reinforcement panel 7A is formed to have the same shape as the second floor reinforcement panel 7B. Each floor reinforcement panel 7A and 7B has a roughly rectangular outer shape when viewed from above the vehicle. In the illustrated example, the length of one side extending in the longitudinal direction of the vehicle and the length of one side extending in the width direction of the vehicle are set to approximate dimensions. In addition, the front corners of each floor reinforcement panel 7A and 7B are cut off.

[0039] In this embodiment, the rear end 7a of the floor reinforcement panel 7 (7A, 7B), the rear end 1Ma of the main floor panel 1M, and the front end 1Ra of the rear floor panel 1R are joined together in an overlapping manner. In the illustrated example, the rear end 7a of the floor reinforcement panel 7 (7A, 7B) abuts against the upper surface of the rear end 1Ma of the main floor panel 1M, the front end 1Ra of the rear floor panel 1R abuts against the lower surface of the rear end 1Ma of the main floor panel 1M, and the rear end 1Ma of the main floor panel 1M is sandwiched between the rear end 7a of the floor reinforcement panel 7 (7A, 7B) and the front end 1Ra of the rear floor panel 1R. In this state, the rear end 7a of the floor reinforcement panel 7 (7A, 7B), the rear end 1Ma of the main floor panel 1M, and the front end 1Ra of the rear floor panel 1R are joined together in a three-layer overlap by spot welding or the like. In other words, in the illustrated example, the rear end 7a of the first floor reinforcement panel 7A, the right portion of the rear edge of the rear seat footwell panel 1c (rear end 1Ma of the main floor panel 1M), and the right portion of the front flange 1b1 of the rear seat lower panel 1b (front end 1Ra of the rear floor panel 1R) are joined in a three-layer overlap, and the rear end 7a of the second floor reinforcement panel 7B, the left portion of the rear edge of the rear seat footwell panel 1c (rear end 1Ma of the main floor panel 1M), and the left portion of the front flange 1b1 of the rear seat lower panel 1b (front end 1Ra of the rear floor panel 1R) are joined in a three-layer overlap. Furthermore, the joining points at the rear end 7a of the floor reinforcement panels 7 (7A, 7B) are set at multiple locations spaced apart in the vehicle width direction.

[0040] In this embodiment, the first floor reinforcement panel 7A is joined to the rear seat footwell panel 1c adjacent to the vertical wall 10a on one side (right side in the illustrated example) of the floor tunnel 10 in the vehicle width direction, and the second floor reinforcement panel 7B is joined to the rear seat footwell panel 1c adjacent to the vertical wall 10a on the other side of the floor tunnel 10 in the vehicle width direction. In other words, each floor reinforcement panel 7A, 7B is positioned towards the overall vehicle width center of the rear seat footwell panel 1c and along the corresponding vertical wall 10a of the floor tunnel 10, with the floor tunnel 10 sandwiched between the first floor reinforcement panel 7A and the second floor reinforcement panel 7B.

[0041] Each floor reinforcement panel 7A, 7B has multiple reinforcement bead portions 71 that bulge out above the vehicle and extend in the vehicle's longitudinal direction or in the vehicle's longitudinal direction. In the illustrated example, each reinforcement bead portion 71 extends in the vehicle's longitudinal direction. The multiple reinforcement bead portions 71 are spaced apart from each other in the vehicle's width direction. Although not particularly limited, in the illustrated example, five reinforcement bead portions 71 are provided. The bead widths of the two reinforcement bead portions 71 on both sides in the width direction are wider than the bead widths of the remaining three reinforcement bead portions 71 on the center side in the width direction.

[0042] In addition, in the illustrated example, multiple panel-side bead portions 1g are also formed in the rear seat footwell panel portion 1c to which each floor reinforcement panel 7A, 7B is joined. The multiple panel-side bead portions 1g include at least intersecting bead portions 1g1 that extend in a direction intersecting with the reinforcement-side bead portion 71 (in the illustrated example, the vehicle width direction). In the illustrated example, the intersecting bead portion 1g1 is provided in the portion of the rear seat footwell panel portion 1c corresponding to the front end portion 7b of the floor reinforcement panel 7 (each floor reinforcement panel 7A, 7B), bulging upwards towards the vehicle and extending in the vehicle width direction. The panel-side bead portion 1g also includes parallel bead portions 1g2 (see Figure 5) that extend parallel to the reinforcement-side bead portion 71. The parallel bead portions 1g2 are provided, for example, in each of the portions located below the four reinforcement-side bead portions 71 on the floor tunnel 10 side, bulging upwards towards the vehicle and extending in the vehicle longitudinal direction.

[0043] The rear end portion 7a of each floor reinforcement panel 7A, 7B is joined to the rear end portion 1Ma of the main floor panel 1M and the front end portion 1Ra of the rear floor panel 1R in the portion between adjacent reinforcement-side bead portions 71. The front end portion 7b of each floor reinforcement panel 7A, 7B is joined to the intersecting bead portion 1g1 in the portion between adjacent reinforcement-side bead portions 71. The outer edge portion of each floor reinforcement panel 7A, 7B on the floor tunnel 10 side is joined to the portion along the vertical wall 10a of the floor tunnel 10 in the rear seat footwell panel portion 1c, and the outer edge portion of each floor reinforcement panel 7A, 7B on the side opposite to the floor tunnel 10 is joined to the rear seat footwell panel portion 1c. Furthermore, the portion of the central part of each floor reinforcement panel 7A, 7B between adjacent reinforcement-side bead portions 71 is joined to the portion between adjacent parallel bead portions 1g2.

[0044] In this embodiment, the vehicle understructure 100 further includes an underbody flat cross member 8. The underbody flat cross member 8 extends in the vehicle width direction along the lower surface 1c2 of the rear seat footwell panel portion 1c and is formed flat in the vehicle vertical direction, and is a flat cross member that connects a pair of side members 2,2. The underbody flat cross member 8 has a height (total height) in the vehicle vertical direction that is lower than, for example, the protruding height of the upper front cross member 3 in the vehicle vertical direction, and is formed in a flat shape in the vehicle vertical direction. The underbody flat cross member 8 is joined to the lower surface of the rear seat footwell panel portion 1c by spot welding or the like. Each end of the underbody flat cross member 8 in the vehicle width direction is joined to the inner side wall (side sill side wall 2A1) in the vehicle width direction of the corresponding side member 2 (side sill 2A).

[0045] The underfloor flat cross member 8 is positioned in the gap between the lower surface 1c2 of the rear seat footwell panel 1c and the upper surface 5d of the battery unit 5. In other words, the underfloor flat cross member 8 is located in the gap G between the lower surface of the floor panel 1 (main floor panel 1M) and the upper surface 5d of the battery unit 5, which faces upwards towards the vehicle (opposite the floor panel 1). The lower surface 4a of the underfloor rear cross member 4 faces the upper surface 5d of the battery, and the underfloor rear cross member 4 is located in the gap G between the lower surface of the floor panel 1 (rear floor panel 1R) and the upper surface 5d of the battery.

[0046] In this embodiment, the floor reinforcement panels 7 (7A, 7B), the floor panel 1 (rear seat footwell panel section 1c), and the underfloor flat cross member 8 are joined together in a superimposed manner. The underfloor flat cross member 8 extends along the lower surface 1c2 of the rear seat footwell panel section 1c over the entire width of the vehicle, and in a plan view from the vertical direction of the vehicle, the underfloor flat cross member 8 and the floor reinforcement panels 7 (7A, 7B) intersect at the point where they are joined together in a three-layer superimposed manner. In the illustrated example, the underfloor flat cross member 8 is joined to the central part of the floor reinforcement panels 7 (7A, 7B) in the longitudinal direction of the vehicle.

[0047] According to the vehicle understructure 100 of this embodiment, (1) the rear seat footwell panel portion 1c can be reinforced by a floor reinforcement panel 7 joined to the upper surface 1c1 of the rear seat footwell panel portion 1c, that is, by a panel material which is a flattened member in the vehicle vertical direction. As a result, the rear seat footwell panel portion 1c can be reinforced while securing legroom for occupants seated in the rear seat S2. (2) The floor reinforcement panel 7 is arranged in a predetermined range W that fits inside the outer shape of the battery unit 5 in a plan view from one side in the vehicle vertical direction, and this predetermined range W includes at least a portion located forward of the center in the vehicle width direction of the first seating portion S2a1 on one side in the vehicle width direction of the rear seat S2, and a portion located forward of the center in the vehicle width direction of the second seating portion. Therefore, even if the battery unit 5 is positioned close to the rear seat footwell panel 1c, at least the portion of the rear seat footwell panel 1c that is susceptible to loads from occupants and heavy objects, corresponding to the feet of occupants seated in the rear seats, is reinforced by the flat floor reinforcement panel 7. Consequently, even if the load of occupants acts on the rear seat footwell panel 1c when getting in and out of the vehicle, or if heavy objects fall onto the rear seat footwell panel 1c, deformation of the rear seat footwell panel 1c is reduced, and contact between the rear seat footwell panel 1c and the battery unit 5 can be efficiently prevented.

[0048] As described above, the vehicle understructure 100 can prevent contact between the floor panel 1 and the battery unit 5 while ensuring sufficient legroom for the rear seat S2.

[0049] In this embodiment, the rear end 7a of the floor reinforcement panel 7, the rear end 1Ma of the main floor panel 1M, and the front end 1Ra of the rear floor panel 1R are joined together in an overlapping manner. With this configuration, the rigidity of the rear end 1Ma of the main floor panel 1M is increased by joining it with the rear floor panel 1R, and the rear end 7a of the floor reinforcement panel 7 is joined to this strengthened portion. As a result, deformation of the floor reinforcement panel 7 is effectively reduced, and the occurrence of delamination (impact delamination) at the joint between the floor reinforcement panel 7 and the floor panel 1 in the event of a side collision (side impact) such as a pole collision is also effectively reduced.

[0050] In this embodiment, the floor reinforcement panel 7, the floor panel 1 (rear seat footwell panel portion 1c), and the underfloor flattened cross member 8 are joined together in a stacked manner. With this configuration, the rigidity of the portion corresponding to the floor reinforcement panel 7 is more effectively increased by the three-layer laminated structure. Moreover, since the underfloor flattened cross member 8 below the rear seat footwell panel portion 1c is formed flat in the vehicle's vertical direction, contact between the battery unit 5 and the rear seat footwell panel portion 1c can be easily prevented simply by appropriately setting the gap G between the floor panel 1 and the battery unit 5. Furthermore, since the underfloor flattened cross member 8 supports the floor panel 1 from below, the support rigidity against loads from above to below is more effectively increased.

[0051] In this embodiment, the first floor reinforcement panel 7A is joined to the rear seat footwell panel 1c adjacent to the vertical wall 10a on one side in the vehicle width direction of the floor tunnel 10, and the second floor reinforcement panel 7B is joined to the rear seat footwell panel 1c adjacent to the vertical wall 10a on the other side in the vehicle width direction of the floor tunnel 10. With this configuration, the rigidity of the portion of the rear seat footwell panel 1c adjacent to the vertical wall 10a of the floor tunnel 10 is increased, and the outer edges of each floor reinforcement panel 7A and 7B on the floor tunnel 10 side can be joined to this strengthened portion. As a result, deformation of each floor reinforcement panel 7A and 7B is effectively reduced. Furthermore, the occurrence of delamination at the joint between the floor reinforcement panel 7 and the floor panel 1 in the event of a side impact such as a pole collision is also more effectively reduced.

[0052] Furthermore, in this embodiment, the rear end 7a of the floor reinforcement panel 7, the rear end 1Ma of the main floor panel 1M, and the front end 1Ra of the rear floor panel 1R are joined together in an overlapping manner, and the floor reinforcement panel 7, the floor panel 1 (rear seat footwell panel portion 1c), and the underfloor flat cross member 8 are joined together in an overlapping manner. With this configuration, in the event of a side impact such as a pole collision, the amount of deformation displacement that displaces the middle portion of the underfloor flat cross member 8 in the vehicle width direction upwards is effectively reduced, and the occurrence of peeling at the joint between the main floor panel 1M and the rear floor panel 1R is reliably reduced or prevented.

[0053] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and further modifications and changes are possible based on the technical concept of the present invention.

[0054] For example, the front end portion 7b of the floor reinforcement panel 7 may be joined to the front floor cross member 3. For details, referring to Figure 7, an enlarged top view of the main part of the vehicle understructure according to a modified example, the front end portion 7b of the floor reinforcement panel 7 may abut against the upper surface of the rear flange portion 3a of the rear front floor cross member 3, and the front end portion 7b of the floor reinforcement panel 7, the rear flange portion 3a, and the floor panel 1 may be joined in a three-layer stack. Alternatively, the front end portion 7b of the floor reinforcement panel 7 may be formed in a flange shape that is bent upward, and the flange-shaped front end portion 7b may be joined to the rear vertical wall portion of the rear front floor cross member 3.

[0055] Furthermore, the shape, stretching direction, number, and location of the reinforcement-side bead portion 71 and the panel-side bead portion 1g can be set as appropriate. [Explanation of Symbols]

[0056] 1 Floor Panel 1M Main Floor Panel 1Ma rear end 1R Rear Floor Panel 1Ra front end 1a Front seat lower panel 1b Rear seat lower panel 1b1 Front flange section 1b2 Bulge 1b21 Sloped front wall 1b3 Posterior corner 1c Rear footwell panel 1c1 top surface 1c2 bottom surface 1d Front seat footwell panel 1e Dash panel connection panel 1F Rear Panel Section 1g Panel side bead 1g1 Cross-bead section 1g2 Parallel bead section 10 Floor Tunnel 10a Vertical wall 2,2 Pair of side members 2a Bottom side 2A Side Sill 2A1 Side sill side wall 2A2 Side sill upper wall 2B Rear side member 2B1 Inclined Member Section 2B2 Straight Member Section 3. Front cross member above floor 3a Rear flange section 4. Underfloor rear cross member 4a Bottom side 5 Battery Unit 5a Battery outer surface 5b Battery flange 5c battery bottom 5d battery top 6 Battery holding member 7 Floor reinforcement panels 7a Rear end 7b Front end 7A First Floor Reinforcement Panel 7B Second Floor Reinforcement Panel 71 Reinforcement side bead section 8. Underfloor flat cross member 100 Vehicle understructure G Gap L1 First seat, center line L2 Second seat, center line S1 Front Seats S1a Seating area S1b Seatback S2 Rear Seats S2a Seating area S2a1 First seating area S2a2 Second seating area S2b Seatback S2c Headrest S3 Front Seat Bracket S4 Rear Seat Bracket V cabin W within a predetermined range

Claims

1. An undercarriage structure for an electric vehicle, comprising a floor panel forming the bottom of a passenger compartment where front and rear seats are provided, and a pair of side members extending in the longitudinal direction of the vehicle along the outer side of the floor panel in the vehicle width direction, wherein the battery unit is located below the floor panel, The floor panel includes a floor reinforcement panel that is positioned on the upper surface of the rear seat footwell panel, which is the portion between the lower part of the front seat seat and the lower part of the rear seat seat in the longitudinal direction of the vehicle, and is joined to the upper surface. The seating portion of the rear seat has a first seating portion on one side in the vehicle width direction and a second seating portion on the other side in the vehicle width direction. The undercarriage structure of an electric vehicle is characterized in that the floor reinforcement panel is provided in a predetermined range that fits inside the outer shape of the battery unit in a plan view from one side in the vertical direction of the vehicle, and includes at least a portion located forward of the center of the first seating portion in the vehicle width direction and a portion located forward of the center of the second seating portion in the vehicle width direction.

2. The floor panel is composed of a main floor panel including the portion below the seating area of ​​the front seats and the rear footwell panel portion, and a rear floor panel including the portion below the seating area of ​​the rear seats. The vehicle understructure of an electric vehicle according to claim 1, wherein the rear end of the floor reinforcement panel, the rear end of the main floor panel, and the front end of the rear floor panel are joined together in an overlapping manner.

3. The underfloor flattened cross member extends in the vehicle width direction along the lower surface of the rear seat footwell panel and is formed to be flat in the vehicle vertical direction, connecting the pair of side members, and further includes the underfloor flattened cross member which is positioned in the gap between the lower surface of the rear seat footwell panel and the upper surface of the battery of the battery unit, The undercarriage structure of an electric vehicle according to claim 1, wherein the floor reinforcement panel, the floor panel, and the underbody flat cross member are joined together in an overlapping manner.

4. The main floor panel, which includes the portion below the seating area of ​​the front seats and the rear footwell panel portion of the floor panel, has a floor tunnel that bulges upward towards the vehicle at the center of the main floor panel in the width direction of the vehicle and extends in the longitudinal direction of the vehicle. The floor reinforcement panel consists of a first floor reinforcement panel and a second floor reinforcement panel that are spaced apart from each other in the vehicle width direction. The first floor reinforcement panel is joined to the rear seat footwell panel portion adjacent to the vertical wall on one side in the vehicle width direction of the floor tunnel, The vehicle understructure of an electric vehicle according to claim 1, wherein the second floor reinforcing panel is joined to the rear seat footwell panel portion adjacent to the vertical wall on the other side in the vehicle width direction of the floor tunnel.

5. The floor panel further includes a front floor cross member that extends in the vehicle width direction along the upper surface of the portion below the seating area of ​​the front seats and connects the pair of side members, The front end of the floor reinforcement panel is joined to the floor front cross member, the vehicle understructure of an electric vehicle according to any one of claims 1 to 4.

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