Vehicle body lower part structure

Abstract

To provide a vehicle body lower part structure having a structure advantageous for suppressing vibration and noise while securing a space for disposing a power supply unit below a floor panel.SOLUTION: In a vehicle body lower part structure 1, a floor panel 10 includes: a first bead 11 and a second bead 12 which bulge toward a vehicle upper side while being separated from each other in a vehicle width direction; and a flat part 13 including an adjacent part 13b located between the first bead 11 and the second bead 12. The first bead 11 and the second bead 12, respectively, include adjacent bead parts (11a and 12a) extending along the adjacent part 13b in a vehicle front-rear direction. A point P of action of a load of a heavy object W onto the floor panel 10 is set on each of a first panel part 16 and a second panel part 17, in the floor panel 10, which are separated from each other in the vehicle width direction. The adjacent bead part 11a of the first bead 11 and the adjacent bead part 12a of the second bead 12 are disposed between the first panel part 16 and the second panel part 17.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a vehicle underbody structure. [Background technology]

[0002] If the floor panel located under the vehicle body vibrates while the vehicle is running, noise may be generated inside the vehicle cabin. For this reason, structures to suppress the vibration of the floor panel are often applied to the underbody structure.

[0003] As an example of a vehicle lower body structure having a structure for suppressing vibration of a floor panel, a structure disclosed in Patent Document 1 is known. Patent Document 1 discloses a vibration-damping structure using an auxiliary battery installed on the rear floor panel as a damper for suppressing vibration of the rear floor panel. In this vibration-damping structure, the auxiliary battery is accommodated in a bathtub-shaped box provided on the rear floor panel, and a protrusion for elastically supporting the auxiliary battery is provided on the bottom surface of the box. The auxiliary battery and the protrusion function as a damper for suppressing resonance of the rear floor panel, thereby suppressing vibration of the rear floor panel. The contact area between the protrusion of the rear floor panel and the auxiliary battery is adjusted during the design of the vehicle body, so that the resonance frequency of the rear floor panel is set to a lower frequency side than when there is no protrusion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-95110 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, with the recent trend toward electrification of vehicles (EVs), it may be necessary to secure a space below the floor panel for arranging a power supply unit including a battery pack. However, in the structure disclosed in Patent Document 1, since the bathtub-shaped box bulges downward significantly on the underside of the floor panel, it may be difficult to secure a sufficient space below the floor panel for arranging the power supply unit. In addition, in the structure disclosed in Patent Document 1, it may be difficult to set the resonance frequency of the floor panel to an appropriate frequency by only adjusting the contact area between the protrusion and the auxiliary battery. As a result, the structure may be disadvantageous in terms of suppressing vibration and noise.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a vehicle underbody structure that has a structure advantageous for suppressing vibration and noise while ensuring space for arranging a power supply unit below a floor panel. [Means for solving the problem]

[0007] In order to achieve the above object, according to one aspect of the present invention, there is provided a vehicle underbody structure including a floor panel arranged above a power supply unit in the vehicle underside and on which a heavy object is loaded, wherein the floor panel has a first bead and a second bead spaced apart from each other in the vehicle width direction and bulging upward of the vehicle, and a flat portion having an adjacent portion located between the first bead and the second bead, each of the first bead and the second bead has an adjacent bead portion extending in the vehicle front-rear direction along the adjacent portion, the application point of the load of the heavy object on the floor panel is set to each of a first panel portion and a second panel portion spaced apart from each other in the vehicle width direction on the floor panel, and the adjacent bead portion of the first bead and the adjacent bead portion of the second bead are arranged between the first panel portion and the second panel portion. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a vehicle underbody structure that has a structure that is advantageous for suppressing vibration and noise while ensuring space for arranging a power supply unit below a floor panel. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view of a vehicle underbody structure according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an enlarged top view of a main portion of the vehicle underbody structure. [Diagram 3] FIG. [Figure 4] 3 is a cross-sectional view taken along line AA shown in FIG. 2. [Diagram 5] FIG. 3 is a perspective view for explaining the shape of a floor panel in a main portion of FIG. 2. [Figure 6] 6 is a cross-sectional view taken along line BB shown in FIG. 5. [Figure 7] 11 is a diagram for explaining vibration suppression of a floor panel by a vehicle underbody structure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of a vehicle body underbody structure 1 according to an embodiment of the present invention, Figs. 2 and 3 are views showing a main part of the vehicle body underbody structure 1, Fig. 2 is an enlarged top view, and Fig. 3 is a perspective view. In the drawings, the arrow Fr direction indicates the front in the vehicle longitudinal direction, the arrow O direction indicates the outside of the vehicle in the vehicle width direction, and the arrow U direction indicates the upper side in the vehicle vertical direction. In the following description, "front" and "rear" correspond to the front and rear in the vehicle longitudinal direction, "up" and "down" correspond to the up and down in the vehicle vertical direction, and "left" and "right" correspond to the left and right in the vehicle width direction when a passenger in the vehicle faces the front of the vehicle.

[0011] (Outline of the underbody structure) 1, the vehicle body understructure 1 includes a floor panel 10. A floor tunnel 20 is provided in the center (middle) of the floor panel 10 in the vehicle width direction. The vehicle body understructure 1 further includes a side sill 30, a front floor cross member 40, and a rear floor cross member 50. The vehicle body understructure 1 of this embodiment is applied to the structure of the vehicle underbody of an electric vehicle driven by a power source unit B (see FIGS. 4 and 6 described below) including a battery pack.

[0012] The floor panel 10 is a panel member that constitutes the floor portion of the lower part of the vehicle body, and may also be called a main floor panel. In the illustrated example, the floor panel 10 is a plate-like member that extends from the lower part of the front part of the vehicle compartment toward the rear of the vehicle. The dimension of the floor panel 10 in the vehicle width direction approximately corresponds to the dimension of the vehicle body in the vehicle width direction. Note that in the vehicle body underbody structure 1, no member equivalent to a bathtub-shaped box or the like of a conventional vehicle body underbody structure is provided on the underside of the floor panel 10.

[0013] The floor tunnel 20 is provided in the center (middle) of the floor panel 10 in the vehicle width direction. The floor tunnel 20 bulges out toward the top of the vehicle and extends in the vehicle front-rear direction. The floor tunnel 20 extends from the lower part of the front of the vehicle compartment through the front floor cross member 40 and the rear floor cross member 50 to the rear of the rear floor cross member 50.

[0014] In the illustrated example, the floor tunnel 20 is formed of a separate member from the floor panel 10. The floor tunnel 20 has a hat-shaped cross section that opens downward when viewed in the vehicle longitudinal direction. The floor tunnel 20 is joined to the opening edge portion 10a of the floor panel 10 so as to close from below the opening that is provided in the center of the floor panel 10 in the vehicle width direction and extends in the vehicle longitudinal direction. Specifically, the floor tunnel 20 has a tunnel bulge portion 21 that bulges outward in a roughly trapezoidal shape toward the upper side of the vehicle. A tunnel flange portion 22 that protrudes outward in the vehicle width direction is provided at the lower end of the side wall of the tunnel bulge portion 21. The tunnel flange portion 22 is joined to the lower surface of the opening edge portion 10a of the floor panel 10 by spot welding or the like.

[0015] The side sill 30 is provided on the outer edge of the floor panel 10 in the vehicle width direction and extends in the vehicle front-rear direction. The side sill 30 has a hat-shaped cross section that opens outward in the vehicle width direction. The outer surface of the vertical flange 10b on the outer edge of the floor panel 10 in the vehicle width direction is joined to the upper part of the inner wall 31a of the side sill 30 facing the inside in the vehicle width direction by spot welding or the like. The lower part of the side sill 30 protrudes downward from the lower surface of the floor panel 10.

[0016] Each of the front floor cross member 40 and the rear floor cross member 50 is a member that is joined to the floor panel 10 and protrudes upward from the vehicle and extends in the vehicle width direction. Each of the front floor cross member 40 and the rear floor cross member 50 intersects with the floor tunnel 20 from above and is joined to the floor tunnel 20 and the floor panel 10. The rear floor cross member 50 is disposed at a position spaced apart from the front floor cross member 40 toward the rear of the vehicle.

[0017] Each of the floor cross members (40, 50) has a hat-shaped cross section that opens downward when viewed in the vehicle front-rear direction. A middle portion of each of the floor cross members (40, 50) in the vehicle width direction is bent to fit along the floor tunnel 20.

[0018] The front floor cross member 40 has a first bulging portion 41, a first front flange 42, a first rear flange 43, and a first outer joint portion 44.

[0019] The first bulging portion 41 bulges upward of the vehicle and extends from the right side sill 30 to the left side sill 30. The first front flange 42 extends forward from the lower end of the front wall of the first bulging portion 41, and the first rear flange 43 extends rearward from the lower end of the rear wall of the first bulging portion 41, and each flange (42, 43) is joined to the upper surface of the floor panel 10 by spot welding or the like. The first outer joint 44 is a portion that constitutes the end of the front floor cross member 40 in the vehicle width direction (longitudinal direction), and is joined to the side sill 30 by spot welding or the like. The first outer joint 44 extends continuously to the top surface portion and the side wall portion of the first bulging portion 41, and is extended in the cross member width direction (vehicle front-rear direction). The first outer joint 44 is formed so as to follow the upper portion of the inner wall 31a of the side sill 30 and the upper wall 31b that extends from the upper end of the inner wall 31a to the outside in the vehicle width direction.

[0020] The rear floor cross member 50 has the same structure as the front floor cross member 40, and has a second bulge portion 51, a second front flange 52, a second rear flange 53, and a second outer joint portion 54 corresponding to each element (41, 42, 43, 44) of the front floor cross member 40.

[0021] Here, the floor panel 10 is divided into a plurality of sections (1R1, 1R2, 1R3, 1L1, 1L2, 1L3) by the floor tunnel 20, the side sill 30, the front floor cross member 40, and the rear floor cross member 50. In other words, the floor panel 10 is divided into a plurality of sections (1R1, 1R2, 1R3, 1L1, 1L2, 1L3) in a plan view seen from above the vehicle by a plurality of high-rigidity members (20, 30, 40, 50) extending vertically and horizontally that constitute the framework member of the lower part of the vehicle body. In the illustrated example, the floor panel 10 is divided (sectioned) into six sections (1R1, 1R2, 1R3, 1L1, 1L2, 1L3).

[0022] In the following, the three right-hand compartments of the six compartments will be appropriately referred to as, from the front, right front compartment 1R1, right middle compartment 1R2, and right rear compartment 1R3, and the three left-hand compartments of the six compartments will be appropriately referred to as, from the front, left front compartment 1L1, left middle compartment 1L2, and left rear compartment 1L3.

[0023] In the vehicle body underbody structure 1 of this embodiment, the structure described below is adopted for a target section, which is at least one section among a plurality of sections divided by high-rigidity members (20, 30, 40, 50). Although not particularly limited, in the illustrated example, the target sections are the right middle section 1R2 and the left middle section 1L2. In the illustrated example, the structure of the right middle section 1R2 and the structure of the left middle section 1L2 are the same except that they are symmetrical to each other. Below, the structure of the left middle section 1L2 and its surroundings will mainly be described.

[0024] (Details of the underbody structure) Next, the detailed structure of the vehicle body lower structure 1 will be described with a focus on the left intermediate section 1L2 and its surrounding structure. Fig. 4 is a cross-sectional view taken along line AA in Fig. 2, and Fig. 5 is a perspective view for explaining the shape of the floor panel 10 in the main part of Fig. 2. Fig. 6 is a cross-sectional view taken along line BB in Fig. 5. Figs. 2 to 6 each show a portion including the left intermediate section 1L2. In Fig. 6, a bracket 60, which will be described later, has been removed, and the outer shape of the bracket 60 is shown by a two-dot chain line.

[0025] 4 and 6, in the vehicle body underbody structure 1, as described above, the lower surface side of the floor panel 10 does not have a portion having a relatively large cross section corresponding to a bathtub-shaped box of a conventional vehicle body underbody structure. A power supply unit B including a battery pack is disposed below the floor panel 10. Also, referring to FIGS. 2 and 4, a predetermined heavy object W is disposed above the floor panel 10 of the left intermediate section 1L2, and the heavy object W is loaded on the floor panel 10 from above. In other words, the floor panel 10 is a member disposed above the power supply unit B including a battery pack in the vehicle body underbody and on which the predetermined heavy object W is loaded. Note that the heavy object W is omitted from the illustration in FIGS. 1, 3, 5, and 6 for clarity of the drawings. The heavy object W is also loaded on the floor panel 10 of the right intermediate section 1R2.

[0026] The heavy object W is a device having a predetermined weight that can be provided between the floor panel 10 and a seat (not shown). An example of a device as the heavy object W is a capacitor, which is a temporary power source used when an abnormality occurs in the power supply unit B. The heavy object W has an outer shape having a predetermined area in a plan view in one section (the left middle section 1L2 in the illustrated example). Although not particularly limited, referring to FIG. 2, the heavy object W has an approximately rectangular outer shape when viewed from above the vehicle, and the weight of the heavy object W is, for example, about 1 kg.

[0027] The space (allowable placement space) for placing the power supply unit B below the floor panel 10 extends outward in the vehicle width direction to the inner side surface in the vehicle width direction of the inner wall 31a of the side sill 30. In other words, since the vehicle body underbody structure 1 does not have a conventional bathtub-shaped box on the underside of the floor panel 10, the allowable placement space for the power supply unit B extends outward in the vehicle width direction to the outer edge of the floor panel 10 in the vehicle width direction.

[0028] Referring to FIGS. 2 to 6, the floor panel 10 has a first bead 11, a second bead 12, and a flat portion 13.

[0029] The first bead 11 and the second bead 12 are spaced apart from each other in the vehicle width direction and bulge upward in the vehicle. In the illustrated example, the first bead 11 is located on the inner side in the vehicle width direction relative to the second bead 12, and the second bead 12 is located on the outer side in the vehicle width direction relative to the first bead 11. In the vehicle body underbody structure 1, because it is necessary to secure an allowable space for disposing the power supply unit B below the floor panel 10, a member (such as a side member) that improves the rigidity of the floor panel 10 cannot be provided on the underside of the floor panel 10. Therefore, the floor panel 10 is provided with beads (11, 12) that bulge upward.

[0030] In this embodiment, each of the first bead 11 and the second bead 12 is formed in an annular shape when viewed in the vertical direction of the vehicle. In the illustrated example, each bead (11, 12) extends in a generally rectangular annular shape. Each bead (11, 12) extends in an annular shape with a cross-sectional shape that bulges upward of the vehicle. The top of each bead (11, 12) is formed flat, and each bead (11, 12) has a generally trapezoidal outer shape.

[0031] In the illustrated example, when viewed in the vertical direction of the vehicle, the first bead 11 is smaller than the second bead 12. A portion between the first bead 11 and the second bead 12 (an adjacent portion 13b described later) is shifted inward in the vehicle width direction with respect to the center of the left intermediate section 1L2 in the vehicle width direction, and the left intermediate section 1L2 is intentionally divided unequally in the vehicle width direction by the adjacent portion 13b described later.

[0032] The flat portion 13 is a portion that surrounds the periphery of the first bead 11 and the periphery of the second bead 12, and has flat surfaces without any irregularities that do not bulge in the vehicle vertical direction and extend in the vehicle front-rear direction and the vehicle width direction. In the floor panel 10, the height position of the lower surface 13a of the flat portion 13 in the vehicle vertical direction is set to the same level over the entire floor panel 10. The opening edge portion 10a of the floor panel 10 is formed continuously with the flat portion 13 on the floor tunnel 20 side, and the vertical flange 10b of the floor panel 10 is formed continuously with the flat portion 13 on the side sill 30 side (outside in the vehicle width direction). Here, the flat portion 13 (more specifically, the lower surface 13a of the flat portion 13) is used as a reference for the height position in the vehicle vertical direction. In this case, the floor tunnel 20 (tunnel bulging portion 21), the front floor cross member 40, and the rear floor cross member 50 all protrude (bulge) upward from the flat portion 13 of the floor panel 10.

[0033] The flat portion 13 has an adjacent portion 13b located between the first bead 11 and the second bead 12. In other words, the flat portion 13 also extends into the portion of the floor panel 10 between the first bead 11 and the second bead 12, and this portion constitutes the adjacent portion 13b. The adjacent portion 13b connects the lower end of the side wall of the first bead 11 on the outer side in the vehicle width direction to the lower end of the side wall of the second bead 12 on the inner side in the vehicle width direction.

[0034] In this embodiment, the main portion 10c of the floor panel 10 in the left intermediate section 1L2, including the adjacent portion 13b, the first bead 11, and the second bead 12, is surrounded by a plurality of high-rigidity members (20, 30, 40, 50) joined to the floor panel 10. The flat portion 13 has an annular flat portion 13c that connects the main portion 10c and the inner edge portions of the plurality of high-rigidity members (20, 30, 40, 50). The main portion 10c occupies most of the range of the left intermediate section 1L2 of the floor panel 10, and the area of ​​the annular flat portion 13c occupies the remaining range of the left intermediate section 1L2 of the floor panel 10.

[0035] The first bead 11 and the second bead 12 each have adjacent bead portions (11a, 12a). The adjacent bead portions (11a, 12a) extend in the vehicle front-rear direction along the adjacent portion 13b of the flat portion 13. The adjacent bead portion 11a of the first bead 11 and the adjacent bead portion 12a of the second bead 12 extend in the front-rear direction adjacent to each other with a gap therebetween.

[0036] In the illustrated example, each of the first bead 11 and the second bead 12 extends in a generally rectangular ring shape as described above, and has adjacent bead portions (11a, 12a), opposing bead portions (11b, 12b), front bead portions (11c, 12c), and rear bead portions (11d, 12d). The opposing bead portion 11b of the first bead 11 faces the adjacent bead portion 11a of the first bead 11 with a gap in the vehicle width direction and extends in the vehicle front-rear direction. The front bead portion 11c of the first bead 11 extends in the vehicle width direction and connects the front end of the adjacent bead portion 11a and the front end of the opposing bead portion 11b. The rear bead portion 11d of the first bead 11 extends generally in the vehicle width direction and connects the rear end of the adjacent bead portion 11a and the rear end of the opposing bead portion 11b. Similarly, the opposing bead portion 12b of the second bead 12 faces the adjacent bead portion 12a of the second bead 12 with a gap in the vehicle width direction and extends in the vehicle front-rear direction. The front bead portion 12c of the second bead 12 extends in the vehicle width direction and connects the front end of the adjacent bead portion 12a to the front end of the opposing bead portion 12b. The rear bead portion 12d of the second bead 12 extends roughly in the vehicle width direction and connects the rear end of the adjacent bead portion 12a to the rear end of the opposing bead portion 12b. The annular first bead 11 and the annular second bead 12 are connected to a plurality of high-rigidity members (20, 30, 40, 50) via the annular flat portion 13c of the flat portion 13.

[0037] The adjacent bead portions (11a, 12a) and the opposing bead portions (11b, 12b) each extend parallel to the floor tunnel 20 and the side sill 30, and the front bead portions (11c, 12c) and the rear bead portions (11d, 12d) each extend parallel to the front floor cross member 40 and the rear floor cross member 50. The bead width (bead thickness) of each bead (11, 12) is set appropriately according to the rigidity, etc. required of the floor panel 10 in the left intermediate section 1L2, and each element of the bead (11, 12) can be set to a different width as appropriate.

[0038] Referring to FIG. 5, the outer edge of each bead (11, 12) is adjacent to a drainage portion 14 having a drainage hole 14a. The drainage hole 14a is opened at the center of the drainage portion 14. A part of the outer edge of the drainage portion 14 is continuous with the corresponding bead (11 or 12). In the illustrated example, the drainage portion 14 is adjacent to the inner part of the rear bead portion 11d in the vehicle width direction in the first bead 11, and is adjacent to the outer part of the rear bead portion 12d in the vehicle width direction in the second bead 12. The bead height of the part of the rear bead portion (11d, 12d) that is continuous with the drainage portion 14 is lower than the bead height of the other part. Even if liquid accumulates in the inner part of the bead (first panel portion 16 and second panel portion 17 described later) of the bead (11, 12), the accumulated liquid is easily led to the drainage portion 14.

[0039] In addition, a plurality of protrusions 15 protruding upward from the vehicle are formed on the inner portion of each bead (first panel portion 16, second panel portion 17 described later). In the illustrated example, each protrusion 15 has a truncated cone shape when viewed from above. Although not particularly limited, five protrusions 15 are provided on the inner portion of the first bead 11, and six protrusions 15 are provided on the inner portion of the second bead 12. Some of the plurality of protrusions 15 are adjacent to the beads (11, 12) and are continuous with the beads (11, 12). In the inner portion of the first bead 11, two protrusions 15 are adjacent to the adjacent bead portion 11a. In the inner portion of the second bead 12, two protrusions 15 are adjacent to the adjacent bead portion 12a, and one protrusion 15 is adjacent to the rear bead portion 12d.

[0040] 2 and 4, as described above, a heavy object W is loaded on the floor panel 10 of the left middle section 1L2. Therefore, the load of the heavy object W acts on and is received by the floor panel 10. Referring to FIG. 2, the center of the heavy object W in the vehicle width direction is shifted inward in the vehicle width direction with respect to the center of the left middle section 1L2 in the vehicle width direction in correspondence with the adjacent portion 13b when viewed from above the vehicle. When viewed from above the vehicle, the heavy object W is disposed so as to intersect with the adjacent bead portion 11a of the first bead 11, the adjacent portion 13b of the flat portion 13, and the adjacent bead portion 12a of the second bead 12, and has a rectangular outer shape with the vehicle width direction as the longitudinal direction. When viewed from above the vehicle, the heavy object W is located approximately in the inner portion of the main portion 10c. In detail, the heavy load W is located above the floor panel 10 in the vertical direction, between the front bead portion (11c, 12c) and the rear bead portion (11d, 12d) in the front-to-rear direction, and between the opposing bead portion 11b of the first bead 11 and the opposing bead portion 12b of the second bead 12 in the vehicle width direction.

[0041] The application point P of the load of the heavy object W on the floor panel 10 is set on each of the first panel portion 16 and the second panel portion 17, which are spaced apart from each other in the vehicle width direction of the floor panel 10. The adjacent bead portion 11a of the first bead 11 and the adjacent bead portion 12a of the second bead 12 are disposed between the first panel portion 16 and the second panel portion 17. In other words, the application point P of the load of the heavy object W is set on two areas (the first panel portion 16 and the second panel portion 17) of the floor panel 10 that are spaced apart in the vehicle width direction so as to straddle the adjacent bead portion 11a of the first bead 11, the adjacent portion 13b of the flat portion 13, and the adjacent bead portion 12a of the second bead 12 in the vehicle width direction. Therefore, the load of the heavy load W does not directly act on the area (11a, 13b, 12a) consisting of the adjacent bead portion 11a, the adjacent portion 13b, and the adjacent bead portion 12a, but acts on areas located on both sides of the boundary in the vehicle width direction when this area (11a, 13b, 12a) is taken as the boundary. In this way, the application point P of the load of the heavy load W is set in two areas away from this area (11a, 13b, 12a) in the vehicle width direction, avoiding the flat adjacent portion 13b between the first bead 11 and the second bead 12 and the adjacent bead portions (11a, 12a).

[0042] In this embodiment, the first panel portion 16 is the portion of the floor panel 10 that occupies the inside of the annular first bead 11 (in other words, the inner portion of the first bead 11), and the second panel portion 17 is the portion of the floor panel 10 that occupies the inside of the annular second bead 12 (in other words, the inner portion of the second bead 12). In other words, the application point P of the load of the heavy object W is set in an area inside the inner edges of the left and right annular beads (11, 12).

[0043] In this embodiment, each of the first panel portion 16 and the second panel portion 17 has a curvature (1 / r) and bulges downward of the vehicle. Therefore, the setting area of ​​the load application point P of the heavy load W is not flat but has a curved shape, and is a high rigidity area compared to the flat portion 13.

[0044] In the vehicle body understructure 1, the inner portions of the beads (11, 12) (i.e., the first panel portion 16, the second panel portion 17) bulge downward, but the inner portions (16, 17) are formed inside the inner edges of the beads (11, 12) which bulge upward. As a result, the height positions of the lower ends (16a, 17a) of the inner portions (16, 17) are offset upward by the bead height of the beads (11, 12). Therefore, the vehicle body understructure 1 has a structure that can reduce or eliminate the amount of downward protrusion of the inner portions (16, 17) relative to the lower surface 13a of the flat portion 13. If the downwardly bulging inner portion (16, 17) were formed on the flat portion 13 (i.e., in the case of the bathtub-shaped box of the conventional vehicle underbody structure), the inner portion (16, 17) would necessarily protrude downward from the underside 13a of the flat portion 13 by the amount of the bulge of the inner portion (16, 17).

[0045] Generally, the underside of the vehicle body must have a certain minimum ground clearance, which is the distance from the running surface to the bottom surface of the underside of the vehicle body. When the power supply unit is disposed below the floor panel, it is possible to offset the height position of the floor panel toward the interior of the vehicle from the viewpoint of ensuring the minimum ground clearance. However, this narrows the space inside the vehicle interior, which is undesirable from the viewpoint of ensuring the space inside the vehicle interior. When considering the securing of space inside the vehicle interior and the minimum ground clearance, it may be necessary to dispose the power supply unit as close as possible to the underside of the floor panel.

[0046] Regarding the arrangement of the power supply unit B, (1) in the vehicle body understructure 1 of this embodiment, the lower surface 13a of the floor panel 10 (flat portion 13) does not have the bathtub-shaped box that bulges downward as in the conventional case, so that the power supply unit B can be brought closer to the floor panel 10 by the height of the box. (2) Furthermore, in the vehicle body understructure 1 of this embodiment, the downwardly bulging inner parts (16, 17) are formed on the inside of the inner edges of the upwardly bulging (beads 11, 12), and the amount of downward protrusion of the inner parts (16, 17) relative to the lower surface 13a of the flat portion 13 can be reduced or eliminated, so that the power supply unit B can be brought even closer to the lower surface 13a of the floor panel 10 (flat portion 13). (3) In this way, the vehicle body understructure 1 has a structure that allows the space for arranging the power supply unit B below the floor panel 10 to be expanded in the vehicle width direction and toward the floor panel 10.

[0047] Referring to FIG. 6, in this embodiment, the inner portion (first panel portion 16, second panel portion 17) bulges (concaves) downward of the vehicle with a curvature (1 / r). In the illustrated example, the inner portion (16, 17) bulges downward with a substantially constant curvature (1 / r), in other words, with a substantially constant radius of curvature r. Therefore, the upper and lower surfaces of the inner portion (16, 17) are formed as curved surfaces with a radius of curvature r. In the illustrated example, the radius of curvature r1 of the curved surface of the inner portion (first panel portion 16) of the first bead 11 is set to be smaller than the radius of curvature r2 of the curved surface of the inner portion (second panel portion 17) of the second bead 12. Note that the radius of curvature r is not limited to being substantially constant, and may change continuously, for example, like a downwardly convex paraboloid of revolution, or may change intermittently.

[0048] In the illustrated example, the lower ends (16a, 17a) of the inner portions (16, 17) are located above the lower surface 13a of the flat portion 13 in the vertical direction of the vehicle. In other words, the downwardly bulging inner portions (16, 17) do not protrude below the lower surface 13a of the flat portion 13 in the vertical direction of the vehicle. The amount of downward protrusion of the inner portions (16, 17) from the lower surface 13a of the flat portion 13 is zero. The power supply unit B is disposed close to the lower surface 13a of the flat portion 13 of the floor panel 10.

[0049] In this embodiment, the vehicle body lower structure 1 further includes a bracket 60 that is provided between the heavy load W and the floor panel 10 and joined to the floor panel 10, to which the heavy load W is attached.

[0050] The bracket 60 is made of a metal plate material, and in the illustrated example, is provided in the left middle section 1L2 and the right middle section 1R2. The bracket 60 mainly has a function of supporting a heavy load W (see Figs. 2 and 4) placed above the floor panel 10. In other words, the bracket 60 is a support plate that supports the heavy load W, and also a mounting plate for mounting the heavy load W to the floor panel 10. The bracket 60 has an outer shape that is approximately the same size as the underside of the heavy load W when viewed from above the vehicle. In other words, the bracket 60 is formed to a size according to the size of the heavy load W (the projected area of ​​the heavy load W on the floor panel 10).

[0051] The bracket 60 is located between the heavy load W and the floor panel 10, and faces the underside of the heavy load W. The bracket 60 is provided in a range corresponding to the heavy load W when viewed from above the vehicle. Therefore, like the heavy load W, the vehicle width center of the bracket 60 is shifted inward in the vehicle width direction with respect to the vehicle width center of the left intermediate section 1L2 in correspondence with the adjacent portion 13b when viewed from above the vehicle. When viewed from above the vehicle, the bracket 60 is disposed so as to intersect with the adjacent bead portion 11a of the first bead 11, the adjacent portion 13b of the flat portion 13, and the adjacent bead portion 12a of the second bead 12 in the approximate center of the left intermediate section 1L2, and has an outer shape with the vehicle width direction as the longitudinal direction. The bracket 60 is located generally on the inside of the main portion 10c when viewed from above the vehicle, and more specifically, is located between the front bead portions (11c, 12c) and the rear bead portions (11d, 12d) in the front-rear direction, and between the opposed bead portions 11b and 12b in the vehicle width direction. Furthermore, the front-rear end portions of the adjacent bead portions (11a, 12a) of the beads (11, 12) and the adjacent portion 13b of the flat portion 13 protrude in the front-rear direction of the vehicle relative to the bracket 60 and the heavy load W when viewed from above the vehicle.

[0052] In the illustrated example, the bracket 60 has a generally trapezoidal outer shape when viewed in the vehicle vertical direction, and a hat-shaped cross-sectional shape that opens downward when viewed in the vehicle longitudinal direction. A first width, which is the width in the vehicle longitudinal direction of the inner side (first panel portion 16 side) of the bracket 60 in the vehicle width direction, is wider than a second width, which is the width in the vehicle longitudinal direction of the outer side (second panel portion 17 side) of the bracket 60 in the vehicle width direction. In the illustrated example, the first width of the bracket 60 narrows from an inner end (one end) in the vehicle width direction (longitudinal direction) of the bracket 60 to a portion roughly corresponding to the adjacent bead portion 11a toward the outer side in the vehicle width direction. The second width of the bracket 60 is roughly constant from a portion roughly corresponding to the adjacent bead portion 12a to an outer end (other end) in the vehicle width direction (longitudinal direction) of the bracket 60.

[0053] More specifically, the bracket 60 has a main body portion 61 , a front joining flange 62 , a rear joining flange 63 , and a lateral joining flange 64 .

[0054] The main body 61 bulges outwardly above the vehicle and extends in the vehicle width direction, occupying most of the area of ​​the bracket 60. The outer end of the main body 61 in the vehicle width direction is open and constitutes the outer end of the bracket 60 in the vehicle width direction. The inner end of the main body 61 in the vehicle width direction is closed and connected to the lateral joint flange 64. A portion of the main body 61 including the outer end in the vehicle width direction bulges outwardly, and a third seat portion 65c described below is formed in this bulging portion 61a.

[0055] The joining flanges (62, 63, 64) are portions that are joined to the floor panel 10. The front joining flange 62 extends forward from the front edge of the main body portion 61. The rear joining flange 63 extends rearward from the rear edge of the main body portion 61. The lateral joining flange 64 extends inward in the vehicle width direction from the vehicle width direction inner end of the main body portion 61. The lateral joining flange 64 connects the vehicle width direction inner end of the front joining flange 62 and the vehicle width direction inner end of the rear joining flange 63.

[0056] The bracket 60 is provided with a plurality of (three in the illustrated example) seats (65a, 65b, 65c) for mounting a heavy object. That is, the bracket 60 has a first seat 65a, a second seat 65b, and a third seat 65c.

[0057] In the illustrated example, the three seats (65a, 65b, 65c) are arranged such that a line connecting the first seat 65a, the second seat 65b, and the third seat 65c forms a triangle. Each seat (65a, 65b, 65c) bulges upward from the vehicle and has a seat surface at its top that abuts against the underside of the heavy load W. Each seat (65a, 65b, 65c) has a bolt insertion hole (65a1, 65b1, 65c1) that penetrates the seat surface. A bolt (not shown) is inserted into the bolt insertion hole (65a1, 65b1, 65c1) and screwed into a weld nut N welded to the back surface of the top of each seat (65a, 65b, 65c). As a result, the heavy load W is fastened to and attached to the bracket 60 in a state in which the heavy load W is supported from below at three points by the three seats (65a, 65b, 65c).

[0058] In the illustrated example, the first seat portion 65a is formed by bulging upward the connecting portion between the front joining flange 62 and the lateral joining flange 64, and the second seat portion 65b is formed by bulging upward the connecting portion between the rear joining flange 63 and the lateral joining flange 64. The third seat portion 65c is formed by further bulging upward the bulging portion 61a on the vehicle width direction outer side of the main body portion 61. The seat surfaces of the first seat portion 65a, the second seat portion 65b, and the third seat portion 65c are set, for example, at the same level (height position) in the vehicle up-down direction.

[0059] In this embodiment, the joint points of the bracket 60 to the floor panel 10 are set on each of the first panel portion 16 and the second panel portion 17, and also serve as the application point P of the load of the heavy load W to the floor panel 10. In other words, the position of the joint point of the bracket 60 to the floor panel 10 coincides with the position of the application point P of the load of the heavy load W to the floor panel 10. Since the heavy load W is not directly placed on the floor panel 10 but is placed on the floor panel 10 via the bracket 60, the load of the heavy load W is input to the seat portions (65a, 65b, 65c) of the bracket 60 and acts on the floor panel 10 from the joint points of the bracket 60 to the floor panel 10.

[0060] In the illustrated example, the joining points of the bracket 60 to the floor panel 10 (in other words, the points of application P of the load of the heavy object W to the floor panel 10) are provided at multiple locations on each of the first panel portion 16 and the second panel portion 17. In the illustrated example, the first panel portion 16 has three joining points (points of application P), and the second panel portion 17 has two joining points (points of application P).

[0061] 2, the three joint points (points of application P) in the first panel portion 16 are set at the apexes of three of the five protruding portions 15 that are formed toward the center of the first panel portion 16, and the two joint points (points of application P) in the second panel portion 17 are set at the apexes of two of the six protruding portions 15 that are formed toward the center of the second panel portion 17. The three joint points in the first panel portion 16 are arranged so that lines connecting the respective joint points form a triangle, and the two joint points in the second panel portion 17 are arranged so that they are spaced apart from each other in the fore-and-aft direction of the vehicle.

[0062] In the first panel portion 16, the inner end of the front joining flange 62 in the vehicle width direction is joined by spot welding or the like to the top surface of the protruding portion 15 in the vicinity of the first seat portion 65a, the inner end of the rear joining flange 63 in the vehicle width direction is joined by spot welding or the like to the top surface of the protruding portion 15 in the vicinity of the second seat portion 65b, and the central portion of the lateral joining flange 64 in the vehicle front-rear direction is joined by spot welding or the like to the top surface of the protruding portion 15 between the first seat portion 65a and the second seat portion 65b. In the second panel portion 17, the outer end of the front joining flange 62 in the vehicle width direction is joined by spot welding or the like to the top surface of the protruding portion 15 in the vicinity of the front side of the third seat portion 65c, and the outer end of the rear joining flange 63 in the vehicle width direction is joined by spot welding or the like to the top surface of the protruding portion 15 in the vicinity of the rear side of the third seat portion 65c.

[0063] In this embodiment, the bracket 60 is curved so as to bulge upward of the vehicle when viewed from the vehicle front-rear direction (see FIG. 4). The bracket 60 extends with the vehicle width direction as the longitudinal direction, and bulges generally in a bow shape upward of the vehicle when viewed from the vehicle front-rear direction. One end (inner end) of the bracket 60 in the vehicle width direction (longitudinal direction) is joined to the first panel portion 16 (three joint points in the illustrated example), and the other end (outer end) of the bracket 60 in the vehicle width direction (longitudinal direction) is joined to the second panel portion 17 (two joint points in the illustrated example).

[0064] The four protrusions 15 adjacent to the adjacent bead portions (11a, 12a) are disposed at positions overlapping the bracket 60 when viewed from above the vehicle, but are not joined to the bracket 60. The bracket 60 is curved so as to bulge upward, so that a gap is provided between the bracket 60 and each of the apexes of the four protrusions 15 adjacent to the adjacent bead portions (11a, 12a). Gaps are also provided between the bracket 60 and each of the apexes of the adjacent bead portion 11a of the first bead 11 and the apex of the adjacent bead portion 12a of the second bead 12.

[0065] In this embodiment, a weak portion 66 that promotes elastic deformation of the bracket 60 is formed in at least a portion of the bracket 60 that overlaps with the adjacent portion 13b of the flat portion 13 when viewed in the vertical direction of the vehicle.

[0066] In this embodiment, the fragile portion 66 is formed by opening a through hole 66a in a portion of the bracket 60 that overlaps with at least the adjacent portion 13b of the flat portion 13 when viewed in the vertical direction of the vehicle, and the through hole 66a extends from an upper region of the first panel portion 16 to an upper region of the second panel portion 17. In the illustrated example, the through hole 66a is formed so as to open most of the area of ​​the main body portion 61.

[0067] Next, the operation and effects of the vehicle underbody structure 1 according to this embodiment will be described.

[0068] In the vehicle body understructure 1, a heavy load W is loaded on the floor panel 10, and the heavy load W functions as a member for suppressing vibration of the floor panel 10. That is, in the vehicle body understructure 1, a vibration model of a so-called spring-mass system between the floor panel 10 and the heavy load W is intentionally constructed in desired sections (in the embodiment, the left middle section 1L2 and the right middle section 1R2) of the floor panel 10 that have a relatively large area.

[0069] In a vibration model of a spring-mass system of the vehicle body underbody structure 1, a heavy load W having sufficient mass such as a capacitor functions as a vibration-damping member that lowers the resonant frequency and the vibration level (gain) of a frequency band higher than the lowered resonant frequency by the mass effect, and lowers the vibration level (gain) of the resonant frequency by the damping effect. The heavy load W is not a vibration-damping material such as a merci specially provided for vibration control, but a device such as a capacitor provided in the vehicle. In the vehicle body underbody structure 1 according to this embodiment, the above-mentioned configuration enhances the vibration-damping effect of the heavy load W.

[0070] Specifically, in the vehicle body underbody structure 1 according to this embodiment, (1) the first bead 11 and the second bead 12, which are spaced apart from each other in the vehicle width direction and bulge upward of the vehicle, each have adjacent bead portions (11a, 12a) extending in the vehicle front-rear direction along the adjacent portion 13b of the flat portion 13 located between the first bead 11 and the second bead 12. With this configuration, a portion with high rigidity and a portion with low rigidity are formed in the floor panel 10, and the adjacent portion 13b with low rigidity is likely to become an antinode of vibration. (2) Then, the application point P of the load of the heavy object W on the floor panel 10 is set to each of the first panel portion 16 and the second panel portion 17, which are spaced apart from each other in the vehicle width direction in the floor panel 10, and the adjacent bead portion 11a of the first bead 11 and the adjacent bead portion 12a of the second bead 12 are disposed between the first panel portion 16 and the second panel portion 17. With this configuration, the load application point P of the heavy load W is set in two areas of the floor panel 10 separated in the vehicle width direction so as to straddle the adjacent bead portions (11a, 12a) and the adjacent portion 13b of the flat portion 13 in the vehicle width direction. As a result, vibrations with the adjacent portion 13b having low rigidity as an antinode tend to occur in a wide range beyond the range of the adjacent bead portions (11a, 12a). Therefore, in the vehicle body understructure 1, the adjustment margin toward the low frequency side of the resonance frequency of the floor panel 10 is wider than that of the conventional structure, and the resonance frequency of the floor panel can be set to an appropriate frequency, which can be advantageous in terms of suppressing vibration and noise. (3) As described above, the vehicle body understructure 1 has a structure that allows the space for arranging the power supply unit B under the floor panel 10 to be expanded in the vehicle width direction and toward the floor panel 10.

[0071] As described above, the vehicle underbody structure 1 according to this embodiment has a structure that is advantageous for suppressing vibration and noise while ensuring a space for arranging the power supply unit B below the floor panel 10.

[0072] Fig. 7 is a diagram for explaining vibration suppression of the floor panel 10 by the vehicle body underbody structure 1. Fig. 7 shows an example of the frequency characteristic X of the vibration of the floor panel 10 according to this embodiment, and the frequency characteristics (Y1, Y2) of the vibration of the floor panels according to Comparative Example 1 and Comparative Example 2. In Fig. 7, the horizontal axis shows the frequency f, and the vertical axis shows the vibration gain G (vibration level) at each frequency f.

[0073] The frequency characteristic X of this embodiment is the frequency characteristic when the floor panel 10 is vibrated in a state where the load of a heavy object W acts on the first panel portion 16 and the second panel portion 17 via the bracket 60 having the weak portion 66. The frequency characteristic Y1 of the comparative example 1 is the frequency characteristic when the floor panel 10 is vibrated in a state where no heavy object is loaded on the floor panel 10 and a bracket (not shown) without the weak portion 66 is simply joined to the floor panel 10. The frequency characteristic Y2 of the comparative example 2 is the frequency characteristic when the floor panel 10 is vibrated in a state where no heavy object is loaded and the bracket 60 having the weak portion 66 is simply joined to the floor panel 10. In other words, Figure 7 shows the frequency characteristic X (this embodiment) of the vehicle body underbody structure 1 when a heavy object W is loaded and there is a weak portion 66, the frequency characteristic Y1 (Comparative Example 1) when there is no heavy object W loaded and there is no weak portion 66, and the frequency characteristic Y2 (Comparative Example 2) when there is no heavy object W loaded but there is a weak portion 66.

[0074] In the frequency characteristic Y1 of Comparative Example 1, the vibration gain G peaks at fn1, and in the frequency characteristic Y2 of Comparative Example 2, the vibration gain G peaks at fn2, which is lower than fn1. In the frequency characteristic X of this embodiment, the vibration gain peaks at fn, which is lower than fn1 and fn2. The difference (reduction amount) between fn1 and fn2 is due to the presence or absence of the weak portion 66 (reduction in rigidity). The difference (reduction amount) between fn2 and fn is mainly due to the presence or absence of the heavy load W (mass effect) and the above-mentioned configuration of the application point P of the load of the heavy load W.

[0075] In this embodiment, since each of the first bead 11 and the second bead 12 is formed in an annular shape when viewed in the vertical direction of the vehicle, the rigidity of the portion occupying the inside of the beads (11, 12) is improved, and the portion is less likely to be elastically deformed. Since the first panel portion 16 and the second panel portion 17, which are the setting area of ​​the application point P of the load of the heavy object W, are the portions of the floor panel 10 occupying the inside of the annular beads (11, 12), the load of the heavy object W acts on the first panel portion 16 and the second panel portion 17, which have been made highly rigid, and the load is distributed throughout. As a result, a vibration mode in which the first bead 11 and the first panel portion 16 on the inside thereof vibrate rigidly, and the second bead 12 and the second panel portion 17 on the inside thereof vibrate rigidly, is easily maintained. In other words, a primary mode vibration is easily generated with the adjacent portion 13b of the flat portion 13 as an antinode. Therefore, the resonance frequency of the floor panel 10 can be easily set to a low frequency side.

[0076] In this embodiment, the vehicle body lower structure 1 further includes a bracket 60 that is joined to the floor panel 10 and to which a heavy load W is attached, and each of the first panel portion 16 and the second panel portion 17 has a curvature (1 / r) and bulges downward of the vehicle, and the joining points of the bracket 60 to the floor panel 10 are set on the first panel portion 16 and the second panel portion 17, respectively, and also serve as the application point P of the heavy load W. With this configuration, the panel portions (16, 17) have a curvature (1 / r) and are therefore highly rigid, and local elastic deformation of the panel portions (16, 17) is suppressed, so that the stress due to the load of the heavy load W is concentrated around the panel portions (16, 17). Then, the load of the heavy load W acts on the panel portions (16, 17) through the joining points of the bracket 60 to the floor panel 10, which promotes stress concentration around the periphery, thereby promoting elastic deformation of the floor panel 10 and making it easier for the vibration of the primary mode to occur. Furthermore, the load of the heavy load W acts on the panel portions (16, 17) at the intended position via the bracket 60 without being affected by the size of the heavy load W, improving the accuracy of setting the intended vibration mode. In the embodiment, the protrusions 15 are formed on parts of the first panel portion 16 and the second panel portion 17, and the application point P of the load of the heavy load W is set to the protrusions 15, so that the load input position to the floor panel 10 is fixed with higher accuracy, improving the accuracy of setting the vibration mode.

[0077] In this embodiment, a weak portion 66 that promotes elastic deformation of the bracket 60 is formed in the portion of the bracket 60 that overlaps at least the adjacent portion 13b when viewed in the vertical direction of the vehicle. This configuration reduces the rigidity of the bracket 60, making the portion of the bracket 60 that overlaps with the adjacent portion 13b more likely to elastically deform, and also promotes elastic deformation of the floor panel 10 on the bracket 60 side, making it easier for vibration of the primary mode to occur. In addition, since the effect of the bracket 60 in improving the rigidity of the floor panel 10 is reduced, the reduced rigidity allows the resonance frequency of the floor panel 10 to be adjusted to a lower frequency.

[0078] In this embodiment, the weak portion 66 is formed by opening the through hole 66a in a portion of the bracket 60 that overlaps at least the adjacent portion 13b in the vehicle vertical direction, and the through hole 66a extends from the upper region of the first panel portion 16 to the upper region of the second panel portion 17. With this configuration, the opening inner region of the through hole 66a expands to a range that intersects with the adjacent bead portions (11a, 12a) and the adjacent portion 13b of the flat portion 13 in the vehicle vertical direction. As a result, the central portion of the bracket 60 in the vehicle width direction becomes more likely to elastically deform vertically. And, by expanding the range of the weak portion 66 of the bracket 60, the vibration of the primary mode of the floor panel 10 becomes more likely to occur. And, the effect of improving the rigidity of the floor panel 10 by the bracket 60 is not substantially exerted, and the reduction of the resonance frequency due to the mass effect of the heavy object W is effectively achieved.

[0079] In this embodiment, the bracket 60 is curved so as to bulge upward when viewed from the front-rear direction of the vehicle, and the end of the bracket 60 in the vehicle width direction is joined to the panel portion (16, 17). With this configuration, the bracket 60 also has a curved structure, and the joining span of the bracket 60 to the floor panel 10 is relatively long in the vehicle width direction, so that the upper portion of the adjacent portion 13b in the bracket 60 is easily bent. As a result, when the floor panel 10 elastically deforms due to the vibration of the primary mode with the adjacent portion 13b as the antinode, the bracket 60 also easily deforms elastically in response to the elastic deformation, and the promotion of the vibration of the primary mode of the floor panel 10 is not hindered by the bracket 60.

[0080] In this embodiment, the flat portion 13 has an annular flat portion 13c that connects the main portion 10c (11, 12, 13b) of the floor panel 10 and the inner edge portion of the multiple high-rigidity members (20, 30, 40, 50). This configuration makes the annular flat portion 13c more likely to become a low-rigidity portion relative to the multiple high-rigidity members (20, 30, 40, 50) and the main portion 10c. As a result, elastic deformation is more likely to occur in the floor panel 10 with the annular flat portion 13c as a node, and the promotion of the primary mode vibration with the adjacent portion 13b as an antinode can be more reliably achieved.

[0081] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and further modifications and changes are possible based on the technical concept of the present invention.

[0082] For example, in this embodiment, when viewed from the vertical direction of the vehicle, adjacent portion 13b (the position of the antinode of the vibration of the primary mode) is shifted inward in the vehicle width direction with respect to the center of the left middle section 1L2 in the vehicle width direction, but this is not limited to this. The target frequency characteristics for the vibration of floor panel 10 differ from vehicle to vehicle and may also differ for each section position of floor panel 10. Therefore, the position of adjacent portion 13b in the vehicle width direction can be determined according to the target frequency characteristics.

[0083] Moreover, the fragile portion 66 is not limited to the through hole 66a, but may be a fold (groove) that is likely to induce elastic deformation, such as vertical folds.

[0084] In this embodiment, the vehicle body underbody structure 1 is applied to the left middle section 1L2 and the right middle section 1R2 in a symmetrical structure, but may be applied to an asymmetrical structure. In this case, the bracket 60 in one section may not be provided with a weak portion 66, and the bracket 60 in the other section may be provided with a weak portion 66, intentionally making the rigidity of the floor panel 10 different between the left and right sections, and making the frequency characteristics different.

[0085] In this embodiment, the above-mentioned structures such as the beads (11, 12), the adjacent portion 13b, and the bracket 60 are provided in the right middle section 1R2 and the left middle section 1L2, but are not limited thereto. The positions and number of sections in which the above-mentioned structures are provided are determined according to the rigidity required for the floor panel 10, and the like, and they may be provided in at least one of the multiple sections. [Explanation of symbols]

[0086] 1...Vehicle underbody structure 10…Floor panel 10c…Main parts 11...First bead 11a…adjacent bead area 12...Second bead 12a…adjacent bead area 13...Flat area 13b…adjacent area 13c…Circular flat area 16…First panel section 17…Second panel section 20...Floor tunnel (high rigidity material) 30...Side sill (high-rigidity material) 40...Front floor cross member (high rigidity member) 50...Rear floor cross member (high rigidity member) 60…Bracket 66…Weakened part 66a...Through hole B…Power supply unit P...point of action W…Heavy load

Claims

1. A vehicle underbody structure including a floor panel that is disposed above a power supply unit in a vehicle underbody and on which a heavy object is loaded, The floor panel has a first bead and a second bead spaced apart from each other in a vehicle width direction and bulging upward of the vehicle, and a flat portion having an adjacent portion located between the first bead and the second bead, Each of the first bead and the second bead has an adjacent bead portion extending in a vehicle front-rear direction along the adjacent portion, a point of application of the load of the heavy object to the floor panel is set on each of a first panel portion and a second panel portion spaced apart from each other in a vehicle width direction of the floor panel, A vehicle underbody structure, wherein the adjacent bead portion of the first bead and the adjacent bead portion of the second bead are disposed between the first panel portion and the second panel portion.

2. Each of the first bead and the second bead is formed in an annular shape when viewed in a vehicle vertical direction, 2. The vehicle body underbody structure according to claim 1, wherein the first panel portion is a portion of the floor panel that occupies an inner side of the first bead, and the second panel portion is a portion of the floor panel that occupies an inner side of the second bead.

3. a bracket provided between the heavy object and the floor panel and joined to the floor panel, the heavy object being attached to the bracket; Each of the first panel portion and the second panel portion has a curvature and bulges downwardly of the vehicle, 3. The vehicle underbody structure according to claim 2, wherein a joining point of the bracket to the floor panel is set on each of the first panel portion and the second panel portion, and also serves as the point of application.

4. 4. The vehicle underbody structure according to claim 3, wherein a weakened portion that promotes elastic deformation of the bracket is formed in at least a portion of the bracket that overlaps with the adjacent portion when viewed in the vehicle vertical direction.

5. The fragile portion is formed by opening a through hole in a portion of the bracket that overlaps at least the adjacent portion as viewed in a vehicle vertical direction, The vehicle underbody structure according to claim 4 , wherein the through hole extends from an upper region of the first panel portion to an upper region of the second panel portion.

6. When viewed from the front-rear direction of the vehicle, the bracket is curved so as to bulge upwardly of the vehicle, A portion of the bracket on one end side in the vehicle width direction is joined to the first panel portion, The vehicle underbody structure according to claim 3 , wherein a portion of the bracket on the other end side in the vehicle width direction is joined to the second panel portion.

7. a main portion of the floor panel including the adjacent portion, the first bead, and the second bead is surrounded by a plurality of high-rigidity members joined to the floor panel; 7. The vehicle underbody structure according to claim 2, wherein the flat portion has an annular flat portion connecting between the main portion and inner edge portions of the plurality of high-rigidity members.

Images