Vehicle underbody structure

Abstract

To provide a lower body structure for a vehicle that is able to improve, without increasing cost and mass, riding comfort by transmitting vertical vibration, input to a cross member at a seat rail position in a second-row seats, to an adjacent cross member.SOLUTION: A lower body structure for a vehicle includes: a pair of left seat rails 11 on the left and right, and a pair of right seat rails 12 on the left and right, which are respectively configured to allow the left and right seats 8, 9 to slide independently of each other in second-row seats 7; a first cross member 21 having fixing portions 18, 16 to which the left and right seat rails 11, 12 are fixed; a second cross member 25 provided apart from the first cross member 21 in a vehicle longitudinal direction; and a first connecting member 51 connecting the first cross member 21 and the second cross member 25 in the vehicle longitudinal direction; wherein the first connecting member 51 is located between the fixing portion 18 located on a left side of the right seat rail 12 and the fixing portion 16 located on a right side of the left seat rail 11, in a vehicle width direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to the lower body structure of a vehicle having a first-row seat and a second-row seat from the front of the vehicle.

Background Art

[0002] Generally, a structure for transmitting vibration input from a seat mounting bracket (so-called seat bracket) to a cross member extending in the vehicle width direction is known (see Patent Document 1). By the way, in the case of a vehicle with a wide floor panel, a large vehicle weight, and a high vehicle class, vibration is input in the vehicle vertical direction from the second-row seat to the cross member, causing the cross member to bend and deform vertically, which may deteriorate the riding comfort. In order to solve such problems, it is advisable to improve the rigidity by increasing the cross-sectional area of the above-mentioned cross member, etc. However, in this case, it will lead to an increase in cost and mass.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, an object of this invention is to provide a lower body structure of a vehicle that can transmit the vertical vibration input to the cross member at the seat rail position of the second-row seat to an adjacent cross member without increasing cost and mass, thereby improving the riding comfort.

Means for Solving the Problems

[0005] This invention relates to a lower body structure for a vehicle having a first row of seats and a second row of seats from the front of the vehicle, comprising: a pair of left and right seat rails configured to allow the left and right seats to slide independently in the second row of seats; a pair of left and right seat rails; a first cross member having a fixing portion to which the left and right seat rails are fixed; a second cross member provided spaced apart from the first cross member in the vehicle's longitudinal direction; and a first connecting member connecting the first cross member and the second cross member in the vehicle's longitudinal direction, wherein the first connecting member is positioned between the fixing portion located to the left of the right seat rail and the fixing portion located to the right of the left seat rail in the vehicle's width direction. Furthermore, the first connecting member is positioned in the vehicle width direction such that it overlaps with at least a portion of the fixing portion located to the left of the right seat rail and the fixing portion located to the right of the left seat rail. This is a vehicle lower body structure characterized by the following:

[0006] According to this invention, the first connecting member described above connects to the second cross member at the point where the vibration input from the seat rail of the second row seat is greatest, so that vibrations from the second row seat can be efficiently transmitted to the second cross member.

[0007] In other words, without increasing cost or mass, vertical vibrations input to the cross member at the seat rail position of the second-row seat (first cross member) can be transmitted to the adjacent cross member (second cross member), thereby improving ride comfort.

[0008] In one aspect of this invention, the second row seats are divided seats in which the left and right seats are separated at asymmetrical positions, the first connecting member is located outward in the vehicle width direction from the center in the vehicle width direction, and a second connecting member may be provided at a position symmetrical to the first connecting member with respect to the center in the vehicle width direction.

[0009] According to this invention, by providing a second connecting member, the load transmission path is increased, thereby improving rigidity. Furthermore, vibration transmission can be achieved most efficiently in the typical configuration of a seat rail for a second-row seat.

[0010] In an embodiment of this invention, the first connecting member may connect the lower surfaces of the first cross member and the second cross member in the longitudinal direction of the vehicle. According to this invention, the load from the ridge of the first cross member can be reliably transmitted to the ridge of the second cross member, thereby achieving load distribution.

[0011] In an embodiment of this invention, the first connecting member may have a tank mounting portion for the fuel tank. According to this invention, a fuel tank can be installed without the need to provide a separate tank mounting bracket. Furthermore, it allows for variations in design. Specifically, in the case of a plug-in hybrid electric vehicle (PHEV), the fuel tank is small, and in this case, it is preferable to support the fuel tank at the tank mounting portion of the first connecting member. On the other hand, in the case of a vehicle driven by an internal combustion engine, the fuel tank is large, and in this case, it is preferable to support the fuel tank on the second cross member.

[0012] In an embodiment of this invention, the fuel tank is attached to the tank mounting portion via a tank band, the tank band fixing portion located at the end of the tank band is provided with a projection that bends upward from the tank band fixing portion, and the first connecting member may be provided with an inclined portion near the tank mounting portion that is inclined inward towards the rear or outward towards the rear to restrict the rotation of the projection with respect to the first connecting member. According to this invention, the inclined portion of the first connecting member restricts the aforementioned protruding portion, thereby preventing the tank band fixing portion from rotating.

[0013] In an embodiment of this invention, the first connecting member may have a first portion at the same height as the lower surface of the first cross member, and a second portion extending upward from the rear end of the first portion towards the rear. According to this invention, compared to a structure in which the first connecting member directly connects the lower surfaces of the first cross member and the second cross member, the cross-sectional area of ​​the first connecting member can be increased, and the rigidity of the first connecting member can be ensured.

[0014] As an aspect of the present invention, the first connecting member may have a bead that protrudes downward and extends in the vehicle longitudinal direction in the first portion. According to the present invention, by providing the above-described bead, it is possible to ensure the rigidity of the first connecting member, and since the above-described bead protrudes downward, a draining action can be achieved.

Effect of the Invention

[0015] According to the present invention, without increasing the cost and mass, the vertical vibration input to the cross member at the seat rail position of the second row seat can be transmitted to the adjacent cross member, and there is an effect that the riding comfort can be improved.

Brief Description of the Drawings

[0016] [Figure 1] Plan view showing the lower body structure of a vehicle. [Figure 2] Bottom view of FIG. 1. [Figure 3] Bottom perspective view showing the lower body structure of a vehicle. [Figure 4] Arrow-view cross-sectional view of the main part along line A-A of FIG. 1. [Figure 5] Arrow-view cross-sectional view of the main part along line B-B of FIG. 1. [Figure 6] Arrow-view cross-sectional view of the main part along line C-C of FIG. 1. [Figure 7] Bottom view showing the state where a fuel tank is attached. [Figure 8] Enlarged bottom view of the main part of FIG. 7.

Mode for Carrying Out the Invention

[0017] Without increasing cost and mass, the vertical vibration input to the cross member at the seat rail position of the second row seat is transmitted to the adjacent cross member to improve the riding comfort. The lower body structure of a vehicle having a first row seat and a second row seat from the front of the vehicle. In the second row seat, a pair of left and right seat rails are configured such that the left and right seats can slide independently, a pair of left and right seat rails, a first cross member having a fixing portion to which the left seat rail and the right seat rail are fixed, a second cross member provided spaced apart in the vehicle front-rear direction from the first cross member, and a first connecting member connecting the first cross member and the second cross member in the vehicle front-rear direction. The first connecting member is located between the fixing portion located on the left side of the right seat rail and the fixing portion located on the right side of the left seat rail in the vehicle width direction. The first connecting member is positioned in the vehicle width direction such that it overlaps with at least a portion of the fixing portion located to the left of the right seat rail and the fixing portion located to the right of the left seat rail. This is achieved by the above-described configuration.

Embodiment

[0018] One embodiment of this invention will be described in detail below based on the drawings. The drawings show the lower body structure of the vehicle. FIG. 1 is a plan view showing the lower body structure of the vehicle, FIG. 2 is a bottom view of FIG. 1, FIG. 3 is a bottom perspective view showing the lower body structure of the vehicle, and FIG. 4 is a cross-sectional view taken along the line A-A of FIG. 1 as viewed in the arrow direction of the main part.

[0019] Further, FIG. 5 is a cross-sectional view taken along the line B-B of FIG. 1 as viewed in the arrow direction of the main part, FIG. 6 is a cross-sectional view taken along the line C-C of FIG. 1 as viewed in the arrow direction of the main part, FIG. 7 is a bottom view showing the state in which the fuel tank is mounted, and FIG. 8 is an enlarged bottom view of the main part of FIG. 7. As shown in FIGS. 1 to 3, a front floor panel 1 as a floor panel forming the floor surface of the passenger compartment is provided. In the central portion in the vehicle width direction of the front floor panel 1, a tunnel portion (not shown) protruding into the passenger compartment and extending in the vehicle front-rear direction is formed. The tunnel portion may be integral with the front floor panel 1 or may be a separate body.

[0020] The upper part of the aforementioned front floor panel 1 is equipped with a first-row seat (a front seat consisting of a driver's seat and a passenger's seat), which is not shown in the diagram. At the rear end of the aforementioned front floor panel 1, a rear seat pan 5 is provided as a rear floor panel via a cross member 4 (so-called No. 3 cross member) which includes a cross member upper 2 shown in Figure 1 and a cross member lower 3 shown in Figure 2.

[0021] The aforementioned cross member 4 is a vehicle body strength member that joins and fixes the cross member upper 2 and the cross member lower 3, and has a cross member closed section 6 that extends in the vehicle width direction. As shown in Figure 1, the second-row seats 7 (so-called rear seats) are mounted above the rear seat pan 5 described above. In other words, the lower body structure of this vehicle has a first-row seat (not shown) and a second-row seat 7 from the front of the vehicle. The first-row seat is mounted above the front floor panel 1, and the second-row seat 7 is mounted above the rear seat pan 5.

[0022] Furthermore, the second-row seat 7 described above is divided into a left seat 8 and a right seat 9 in an asymmetrical position. For example, these two seats 8 and 9 are divided in a 6:4 ratio in the vehicle width direction. Here, the left seat 8 and the right seat 9 each have a seat cushion that forms the seating surface for the rear passenger, a seat back that forms the backrest surface for the rear passenger, and a headrest that holds the head of the rear passenger.

[0023] As shown in Figure 1, the second-row seat 7 includes a pair of left-side seat rails 11 and a pair of right-side seat rails 12, which are configured to allow the left seat 8 and the right seat 9 to slide independently in the front-to-rear direction of the vehicle.

[0024] As shown in Figure 1, the front portion of the left rail 11L, which is located on the left side in the vehicle width direction of the pair of left and right seat rails 11, is fixed to the cross member 4 via a rail support bracket 13. The rear portion of the left rail 11L is fixed to the first cross member 21, which will be described later, via a rail support bracket 14.

[0025] As shown in the figure, the front portion of the left-side seat rail 11R, located on the right side in the vehicle width direction, is fixed to the cross member 4 via a rail support bracket 15. The rear portion of the right-side seat rail 11R is fixed to the first cross member 21, which will be described later, via a rail support bracket 16.

[0026] Similarly, as shown in Figure 1, the front portion of the left rail 12L, located on the left side in the vehicle width direction, of the pair of left and right seat rails 12, is fixed to the cross member 4 via a rail support bracket 17. The rear portion of the left rail 12L is fixed to the first cross member 21, which will be described later, via a rail support bracket 18.

[0027] As shown in the figure, the front portion of the right-side seat rail 12R, located on the right side in the vehicle width direction, is fixed to the cross member 4 via a rail support bracket 19. The rear portion of the right-side seat rail 12R is fixed to the first cross member 21, which will be described later, via a rail support bracket 20.

[0028] In short, the front portions of each of the left and right seat rails 11 and the right and right seat rails 12 are fixed to the cross member 4 via rail support brackets 13, 15, 17, and 19, while the rear portions of each are fixed to the first cross member 21, which will be described later, via rail support brackets 14, 16, 18, and 20.

[0029] As shown in Figures 1 and 2, a first cross member 21 (so-called No. 3.5 cross member) extending in the vehicle width direction is provided on the lower surface of the rear seat pan 5, opposite the positions of the rail support brackets 14, 16, 18, and 20 that fix the rear portions of the pair of left seat rails 11 and the pair of right seat rails 12 described above.

[0030] As shown in Figures 4 and 5, the first cross member 21 comprises a front flange portion 21a, a front portion 21b, a lower portion 21c, a rear portion 21d, and a rear flange portion 21e. Furthermore, ridges X1, X2, X3, and X4 extending in the vehicle width direction are formed between the front flange portion 21a and the front portion 21b, between the front portion 21b and the lower portion 21c, between the lower portion 21c and the rear portion 21d, and between the rear portion 21d and the rear flange portion 21e, respectively. In addition, a cross member closed section 22 extending in the vehicle width direction is formed between the lower surface of the rear seat pan 5 and the first cross member 21.

[0031] Furthermore, as shown in Figure 2, the first cross member 21 described above is formed by integrating three members so as to extend in the vehicle width direction: an intermediate member 21A that is long in the vehicle width direction, a left-side member 21L located at the left end in the vehicle width direction, and a right-side member 21R located at the right end in the vehicle width direction.

[0032] Furthermore, as shown in Figures 4, 5, and 6, each of the rail support brackets 14, 16, 18, and 20 described above is fixed to a weld nut 23 that is pre-welded and fixed within the closed cross member section 22 of the first cross member 21, using a bolt 24 that is tightened from above.

[0033] As shown in Figures 1 to 5, a second cross member (so-called No. 4 cross member) 25 is provided at the rear end of the rear seat pan 5 described above, spaced apart from the first cross member 21 in the vehicle's longitudinal direction. The first cross member 21 and the second cross member 25 are adjacent to each other in the vehicle's longitudinal direction.

[0034] As shown in Figures 4 and 5, the second cross member 25 comprises a cross member upper 26 and a cross member lower 27, and the cross member upper 26 and cross member lower 27 form a cross member closed section 28 that extends in the vehicle width direction, making it a vehicle body strength member.

[0035] As shown in Figure 1, the cross member upper 26 is formed by integrating three members that extend in the vehicle width direction: an intermediate member 26A that is long in the vehicle width direction, a left member 26L located at the left end in the vehicle width direction, and a right member 26R located at the right end in the vehicle width direction.

[0036] As shown in Figures 2 and 3, the cross member lower 27 is formed by integrating three members that extend in the vehicle width direction: an intermediate member 27A that is long in the vehicle width direction, a left member 27L located at the left end in the vehicle width direction, and a right member 27R located at the right end in the vehicle width direction.

[0037] As shown in Figures 4 and 5, the lower cross member 27 of the second cross member 25 described above comprises a front flange portion 27a, a front portion 27b, a bottom portion 27c, a rear portion 27d, and a rear flange portion 27e. Furthermore, ridges X5, X6, X7, and X8 extending in the vehicle width direction are formed between the front flange portion 27a and the front portion 27b, between the front portion 27b and the bottom portion 27c, between the bottom portion 27c and the rear portion 27d, and between the rear portion 27d and the rear flange portion 27e, respectively.

[0038] As shown in Figures 4 and 5, a cargo floor 29, which serves as a floor panel, is connected to the rear of the second cross member 25, which includes a cross member upper 26 and a cross member lower 27. This cargo floor 29 constitutes the floor surface of the cargo area.

[0039] Incidentally, as shown in Figures 1 and 2, rear side frames 30 extending in the longitudinal direction of the vehicle are provided on both the left and right sides in the vehicle width direction of the rear seat pan 5 and the cargo floor 29 mentioned above. This rear side frame 30 has a rear side frame upper 31 shown in Figure 1 and a rear side frame lower 32 shown in Figure 2, and a rear side closed cross section extending in the longitudinal direction of the vehicle is formed between the rear side frame upper 31 and the rear side frame lower 32.

[0040] As shown in Figures 1 and 2, each of the aforementioned cross members, namely cross member 4 (so-called No. 3 cross member), first cross member 21 (so-called No. 3.5 cross member), and second cross member 25 (so-called No. 4 cross member), is provided to connect the left and right rear side frames 30, 30 in the vehicle width direction.

[0041] As shown in Figures 1 and 2, a side sill 33 is provided that extends in the longitudinal direction of the vehicle from the outer part in the vehicle width direction of the rear side frame 30, which corresponds to the vehicle width direction end of the first cross member 21, to the lower end of the hinge pillar at the front of the vehicle. This side sill 33 is a vehicle body strength member that has a closed side sill cross section extending in the longitudinal direction of the vehicle, formed by joining and fixing the side sill inner 34 and the side sill outer (not shown).

[0042] Furthermore, as shown in Figures 1 and 2, a rear wheel house 35 is provided at the rear end of the side sill 33 and on the outer side in the vehicle width direction of the rear side frame 30 which is continuous therewith. This rear wheel house 35 comprises a wheel house inner 36 and a wheel house outer (not shown), and the rear wheel house 35 surrounds the upper majority of the rear wheel at a distance.

[0043] Furthermore, as shown in Figures 2 and 3, the rear side frame lower 32, which corresponds to the vehicle width direction end of the first cross member 21 and the vehicle width direction end of the second cross member 25, is provided with a subframe support bracket 37 for attaching a subframe (not shown).

[0044] On the other hand, as shown in Figures 2 and 3, a pair of tank support brackets 38 and 39 are provided on the lower surface of the rear seat pan 5, located directly behind the cross member 4 and in the vehicle width direction inward of the rear side frame lower 32.

[0045] The tank support bracket 38, located on the left side in the vehicle width direction, comprises a flange portion 38a and a bottom surface, i.e., a mounting surface 38b, which protrudes downward from the flange portion 38a in a bottomed cylindrical shape. Similarly, the tank support bracket 39 located on the right side in the vehicle width direction comprises a flange portion 39a and a bottom surface, i.e., a mounting surface 39b, which protrudes downward from the flange portion 39a in a bottomed cylindrical shape, and the respective mounting surfaces 38b and 39b are formed flat.

[0046] As shown in Figure 7, when the fuel tank 40 is located below the rear seat pan 5, the fuel tank 40 is attached to and supported by the vehicle body via a pair of tank bands 41 and 42. Tank band fixing parts 43 and 44 are provided at the front and rear ends of the tank bands 41 and 42.

[0047] As shown in Figure 7, of the pair of left and right tank bands 41 and 42, the left tank band 41 has its front end located to the left and outward in the vehicle width direction, and its rear end located to the inward in the vehicle width direction. Similarly, in the pair of tank bands 41 and 42, the right-hand tank band 42 has its front end positioned to the right outer side in the vehicle width direction, and its rear end positioned to the inner side in the vehicle width direction.

[0048] The tank band fixing portion 43 at the front end of the left tank band 41 is then fixed to the mounting surface 38b of the left tank support bracket 38 using fastening members 45 such as bolts. Similarly, the tank band fixing portion 43 at the front end of the right tank band 42 is fixed to the mounting surface 39b of the right tank support bracket 39 using fastening members 45 such as bolts.

[0049] Incidentally, as shown in Figures 2 and 3, the lower part of the rear seat pan 5 is provided with a first connecting member 51 that connects the first cross member 21 and the second cross member 25 in the longitudinal direction of the vehicle. The first connecting member 51 described above is located between the fixing part located to the left of the right seat rail 12 in the vehicle width direction, that is, the rail support bracket 18 of the left rail 12L, and the fixing part located to the right of the left seat rail 11, that is, the rail support bracket 16 of the right rail 11R.

[0050] More specifically, the first connecting member 51 described above is located within the vehicle width direction region between the left end in the vehicle width direction of the rail support bracket 16 at the rear of the right rail 11R and the right end in the vehicle width direction of the rail support bracket 18 at the rear of the left rail 12L.

[0051] As a result, the first connecting member 51 connects the second cross member 25 to the area where the vibration input from the seat rails 11 and 12 of the second row seat 7 is greatest (a predetermined area of ​​the first cross member 21 to which the adjacent rail support brackets 16 and 18 are attached), thereby efficiently transmitting vibrations from the second row seat 7 to the second cross member 25.

[0052] In other words, the system is configured to improve ride comfort by transmitting vertical vibrations input to the cross member at the seat rail position of the second-row seat 7 (i.e., the first cross member 21) to the adjacent cross member (i.e., the second cross member 25) without increasing cost or mass.

[0053] As shown in Figure 1, the second row seats 7 described above are asymmetrical seats, with the left and right seats 8 and 9 divided into a 6:4 ratio. As shown in Figure 2, the first connecting member 51 is located to the right and outward in the vehicle width direction from the center CL in the vehicle width direction, and the second connecting member 52 is provided at a position symmetrical to the first connecting member 51 with respect to the center CL in the vehicle width direction.

[0054] In other words, the first connecting member 51 is positioned offset to the right of the center CL in the vehicle width direction, and the second connecting member 52 is positioned offset to the left of the center CL in the vehicle width direction. The amount of offset of the first connecting member 51 from the center CL in the vehicle width direction and the amount of offset of the second connecting member 52 from the center CL in the vehicle width direction are set to be the same.

[0055] Furthermore, as shown in Figure 1, the first connecting member 51 is provided so as to include the opposing boundary between the seat cushion of the left seat 8, which is divided in a 6:4 ratio, and the seat cushion of the right seat 9.

[0056] Similar to the first connecting member 51, the second connecting member 52 also connects the first cross member 21 and the second cross member 25 in the longitudinal direction of the vehicle at the lower part of the rear seat pan 5. Furthermore, both the first and second connecting members 51 and 52 are rigid members.

[0057] In this way, by providing the second connecting member 52 symmetrically with respect to the center CL in the vehicle width direction with respect to the first connecting member 51, the load transmission path is increased by the second connecting member 52, and as a result, rigidity is improved. Furthermore, this configuration is designed to transmit vibrations most efficiently in the typical seat rail configuration of the second-row seat 7.

[0058] As shown in Figures 6 and 8, the first connecting member 51 has a front flange portion 51a, a right flange portion 51b, a left flange portion 51c, and a rear flange portion 51d. The front flange portion 51a is joined and fixed to the first cross member 21, the left and right flange portions 51c and 51b are joined and fixed to the lower surface portion 27c of the cross member lower 27 of the second cross member 25. As shown in Figure 3, the first connecting member 51 described above is formed such that the portion for which the tank mounting portion 53, which will be described later, is provided protrudes downward from the left and right flange portions 51c and 51b.

[0059] As shown in Figures 6 and 8, the second connecting member 52 also has a front flange portion 52a, a right flange portion 52b, a left flange portion 52c, and a rear flange portion 52d. The front flange portion 52a is joined and fixed to the first cross member 21, the left and right flange portions 52c and 52b are joined and fixed to the lower surface of the rear seat pan 5, and the rear flange portion 52d is joined and fixed to the front flange portion 27a of the cross member lower 27 of the second cross member 25. As shown in Figure 3, the second connecting member 52 described above is formed such that the portion for which the tank mounting portion 55, which will be described later, is provided protrudes downward from the left and right flange portions 52c and 52b.

[0060] As shown in Figure 4, the first connecting member 51 described above connects the lower surfaces of the cross member lower 27 of the first cross member 21 and the second cross member 25 in the vehicle longitudinal direction. More specifically, as shown in Figure 4, the first connecting member 51 connects the lower surface portion 21c of the first cross member 21 and the lower surface portion 27c of the cross member lower 27 of the second cross member 25 in the longitudinal direction of the vehicle. This configuration ensures that the load from the ridge line X3 of the first cross member 21 is reliably transmitted to the ridge line X6 of the cross member lower 27 of the second cross member 25, thereby distributing the load.

[0061] As shown in Figures 6 and 8, the first connecting member 51 has a tank mounting portion 53 for the fuel tank 40 (see Figure 7). As shown in Figure 4, this tank mounting portion 53 is formed as an opening, and a weld nut 54 is provided on the upper part of the tank mounting portion 53 of the first connecting member 51 so as to be continuous with the opening and the screw hole.

[0062] As shown in Figures 6 and 8, the second connecting member 52 described above is also provided with a tank mounting portion 55 for the fuel tank 40 (see Figure 7). The tank mounting portion 55 is formed as an opening, and a weld nut (not shown) is provided on the upper part of the tank mounting portion 55 of the second connecting member 52 so that the opening and the screw hole are continuous. This configuration eliminates the need to provide a separate tank mounting bracket, allowing the fuel tank 40 to be installed.

[0063] Furthermore, the system is configured to accommodate variations. Specifically, in the case of a plug-in hybrid vehicle (so-called PHEV), the fuel tank is small, and in this case, the fuel tank 40 is supported by the tank mounting portions 53 and 55 of the first connecting member 51 and the second connecting member 52, respectively. On the other hand, in the case of a vehicle driven by an internal combustion engine, the fuel tank is large, and in this case, the system is configured to support the fuel tank on the second cross member 25.

[0064] As shown in Figures 7 and 8, the fuel tank 40 is attached to the tank mounting sections 53 and 55 via the pair of left and right tank bands 41 and 42 described above. More specifically, the tank band fixing sections 44 and 44 located at the rear ends of the tank bands 41 and 42 are attached to the tank mounting sections 53 and 55 using fastening members 56 such as bolts that are screwed into the weld nuts 54.

[0065] The tank band fixing portion 44 on the tank band 42 side is provided with a projection portion 44a that extends from the rear left side of the tank band fixing portion 44 toward the front of the vehicle and toward the left in the vehicle width direction, then bends and extends upward. The tank band fixing portion 44 on the tank band 41 side is provided with a projection portion 44b that extends from the rear left side of the tank band fixing portion 44 toward the rear of the vehicle and toward the left in the vehicle width direction, then bends and extends upward.

[0066] As shown in Figure 8, the first connecting member 51 is provided with an inclined portion 57 near the tank mounting portion 53 described above, which is inclined towards the rear and inward in the vehicle width direction (to the left in the vehicle width direction in this embodiment) to restrict the rotation of the projection portion 44a relative to the first connecting member 51.

[0067] As shown in the figure, the second connecting member 52 is provided with an inclined portion 58 near the tank mounting portion 55 described above, which is inclined towards the rear in the direction of the vehicle width (to the right in the direction of the vehicle width in this embodiment) to restrict the rotation of the projection portion 44b relative to the second connecting member 52.

[0068] As a result, on the first connecting member 51 side, the inclined portion 57 restricts the protruding portion 44a, thereby preventing the tank band fixing portion 44 from rotating. On the second connecting member 52 side, the inclined portion 58 restricts the protruding portion 44b, thereby preventing the tank band fixing portion 44 from rotating.

[0069] As shown in Figure 4, the first connecting member 51 has a first portion α that extends in the longitudinal direction of the vehicle at the same height as the lower surface portion 21c of the first cross member 21, and a second portion β that extends rearward from the rear end of the first portion α.

[0070] As a result, compared to a structure in which the first connecting member 51 directly and linearly connects the lower surfaces of the first cross member 21 and the lower cross member 27 of the second cross member 25, the cross-sectional area of ​​the first connecting member 51 can be increased, thereby ensuring the rigidity of the first connecting member 51.

[0071] As shown in Figures 6 and 8, the first connecting member 51 has a bead 61 in the first portion α that protrudes downward and extends in the longitudinal direction of the vehicle. Similarly, as shown in Figures 6 and 8, the second connecting member 52 also has a portion at the same height as the lower surface of the first cross member 21, and in this portion, it has a bead 62 that protrudes downward and extends in the longitudinal direction of the vehicle.

[0072] As shown in Figure 6, the front end of each of these beads 61, 62 is open toward the front of the vehicle. In this way, by providing the aforementioned beads 61 and 62, the rigidity of each connecting member 51 and 52 is ensured, and the downward protrusion of the beads 61 and 62 provides a water drainage function.

[0073] In Figure 1, 63 is a brace member that connects the vehicle width end of the second cross member 25 to the body side panel including the wheelhouse inner 36. In the diagram, arrow F indicates the front of the vehicle, arrow R indicates the rear of the vehicle, arrow LE indicates the left outward direction in the vehicle width direction, arrow RI indicates the right outward direction in the vehicle width direction, and arrow UP indicates the top of the vehicle.

[0074] As described above, the lower body structure of the vehicle according to this embodiment is a lower body structure of a vehicle having a first row of seats and a second row of seats 7 from the front of the vehicle, and comprises a pair of left and right seat rails 11 configured to allow the left and right seats (left seat 8, right seat 9) of the second row of seats 7 to slide independently, a pair of left and right seat rails 12, a first cross member 21 having fixing parts (see rail support brackets 16, 18) to which the left seat rails 11 and the right seat rails 12 are fixed, a second cross member 25 provided spaced apart from the first cross member 21 in the vehicle longitudinal direction, and a first connecting member 51 connecting the first cross member 21 and the second cross member 25 in the vehicle longitudinal direction, wherein the first connecting member 51 is located between the fixing part (rail support bracket 18) located to the left of the right seat rail 12 and the fixing part (rail support bracket 16) located to the right of the left seat rail 11 in the vehicle width direction (see Figures 1 and 2).

[0075] With this type of vehicle underbody structure, the first connecting member 51 connects the second cross member 25 to the part of the second row seat 7 where the vibration input from the seat rails 11 and 12 is greatest, thus efficiently transmitting vibrations from the second row seat 7 to the second cross member 25.

[0076] In other words, without increasing cost or mass, vertical vibrations input to the cross member (first cross member 21) at the seat rail positions 11 and 12 of the second-row seat 7 can be transmitted to the adjacent cross member (second cross member 25), thereby improving ride comfort.

[0077] Furthermore, in the lower body structure of such a vehicle, the second row seat 7 is a split seat in which the left and right seats (left seat 8, right seat 9) are divided at asymmetrical positions, the first connecting member 51 is located outward in the vehicle width direction from the center CL in the vehicle width direction, and the second connecting member 52 is provided at a position symmetrical to the first connecting member 51 with respect to the center CL in the vehicle width direction (see Figures 1 and 2).

[0078] With this type of vehicle lower body structure, the addition of the second connecting member 52 increases the load transmission path, thereby improving rigidity. Furthermore, vibration transmission can be achieved most efficiently with the typical configuration of the seat rails 11 and 12 of the second-row seat 7.

[0079] Furthermore, in the lower body structure of such a vehicle, the first connecting member 51 connects the lower surfaces of the first cross member 21 and the second cross member 25 in the longitudinal direction of the vehicle (see Figure 4). With such a vehicle lower body structure, the load from the ridge line X3 of the first cross member 21 can be reliably transmitted to the ridge line X6 of the second cross member 25 (more specifically, the lower cross member 27 of the second cross member 25), thereby distributing the load.

[0080] Furthermore, in the lower body structure of such a vehicle, the first connecting member 51 has a tank mounting portion 53 for the fuel tank 40 (see Figures 2, 4, and 7). With this type of vehicle underbody structure, there is no need to provide a separate tank mounting bracket, and the fuel tank 40 can be mounted. Furthermore, it allows for variations. Specifically, in the case of a plug-in hybrid electric vehicle (PHEV), the fuel tank 40 is small, and in this case, it is preferable to support the fuel tank 40 with the tank mounting portion 53 of the first connecting member 51. On the other hand, in the case of a vehicle driven by an internal combustion engine, the fuel tank is large, and in this case, it is preferable to support the fuel tank with the second cross member 25.

[0081] In addition, in the lower body structure of such a vehicle, the fuel tank 40 is attached to the tank mounting portion 53 via a tank band 42, and the tank band fixing portion 44 located at the end of the tank band 42 is provided with a projection portion 44a that bends upward from the tank band fixing portion 44, and the first connecting member 51 is provided with an inclined portion 57 near the tank mounting portion 53 that is inclined inward towards the rear or outward towards the rear (the former in this embodiment) to restrict the rotation of the projection portion 44a relative to the first connecting member 51. With this type of lower body structure for a vehicle, the inclined portion 57 of the first connecting member 51 restricts the aforementioned protruding portion 44a, thereby preventing the tank band fixing portion 44 from rotating.

[0082] Furthermore, in the lower body structure of such a vehicle, the first connecting member 51 has a first portion α at the same height as the lower surface of the first cross member 21, and a second portion β that extends upward from the rear end of the first portion α towards the rear (see Figure 4).

[0083] With this type of lower body structure for a vehicle, the cross-sectional area of ​​the first connecting member 51 can be increased compared to a structure in which the first connecting member 51 directly connects the lower surfaces of the first cross member 21 and the second cross member 25, thereby ensuring the rigidity of the first connecting member 51.

[0084] Furthermore, in the lower body structure of such a vehicle, the first connecting member 51 has a bead 61 that protrudes downward and extends in the longitudinal direction of the vehicle in the first portion α (see Figures 6 and 8). With such a vehicle lower body structure, the rigidity of the first connecting member 51 can be ensured by providing the bead 61 described above, and the downward protrusion of the bead 61 allows for water drainage.

[0085] In the correspondence between the structure of this invention and the above-described embodiments, The second-row seat of this invention corresponds to the second-row seat 7 of the embodiment, The same applies to the following: The left and right seats correspond to seat number 8 on the left and seat number 9 on the right. The left seat rail corresponds to the left seat rail 11. The right-side seat rail corresponds to the right-side seat rail 12. The fixing part located on the right side of the left seat rail corresponds to the rail support bracket 16. The fixing part located on the left side of the right seat rail corresponds to the rail support bracket 18. The first cross member corresponds to the first cross member 21 (the so-called No. 3.5 cross member), The second cross member corresponds to the second cross member 25 (the so-called No. 4 cross member), The fuel tank corresponds to fuel tank 40. The tank band is compatible with tank band 42. The tank band fixing part corresponds to the tank band fixing part 44. The projection corresponds to projection 44a, The first connecting member corresponds to the first connecting member 51, The second connecting member corresponds to the second connecting member 52, The tank mounting section corresponds to the tank mounting section 53. The inclined section corresponds to the inclined section 57, The bead is compatible with bead 61. The center in the vehicle width direction corresponds to the center CL in the vehicle width direction. Part 1 corresponds to Part 1 α, Part 2 corresponds to Part 2β, This invention is not limited to the configuration of the above-described embodiment, and many other embodiments can be obtained. [Industrial applicability]

[0086] As described above, the present invention is useful for the lower body structure of a vehicle having a first row of seats and a second row of seats from the front of the vehicle. [Explanation of Symbols]

[0087] 7…2nd row seats 8…Left seat 9…Right seat 11…Left seat rail 12…Right-side seat rail 16… Rail support bracket (fixing part located to the right of the left seat rail) 18… Rail support bracket (fixing part located on the left side of the right seat rail) 21…First Crossmember 25…2nd Crossmember 40…Fuel tank 42... Tank band 44... Tank band fixing part 44a...Protruding piece 51…First connecting member 52...Second connecting member 53... Tank mounting section 57…Slope part 61... Bead CL... Center in the vehicle width direction α…First part β…Second part

Claims

1. A lower body structure of a vehicle having a first row of seats and a second row of seats from the front of the vehicle, In the above-mentioned second-row seats, a pair of left-side seat rails and a pair of right-side seat rails are configured to allow the left and right seats to slide independently. A first cross member having a fixing portion to which the left seat rail and the right seat rail are fixed, A second cross member is provided spaced apart from the first cross member in the vehicle's longitudinal direction, The system includes a first connecting member that connects the first cross member and the second cross member in the longitudinal direction of the vehicle, The first connecting member described above is located in the vehicle width direction between the fixing portion located to the left of the right seat rail and the fixing portion located to the right of the left seat rail. The first connecting member is positioned in a location that overlaps with at least a portion of the fixing portion located to the left of the right seat rail and the fixing portion located to the right of the left seat rail in the vehicle width direction. The lower body structure of the vehicle.

2. The second row seats mentioned above are split seats, with the left and right seats separated at asymmetrical positions. The above-mentioned first connecting member is located outward in the vehicle width direction from the center in the vehicle width direction. A second connecting member is provided at a position symmetrical to the first connecting member with respect to the center in the width direction of the vehicle. The lower body structure of the vehicle according to claim 1.

3. The first connecting member connects the lower surfaces of the first cross member and the second cross member in the vehicle's longitudinal direction. The lower body structure of the vehicle according to claim 1.

4. The first connecting member described above has a tank mounting portion for the fuel tank. The lower body structure of the vehicle according to claim 1.

5. The above fuel tank is attached to the tank mounting section via a tank band. The tank band fixing portion located at the end of the above-mentioned tank band is provided with a projection that bends upward from the tank band fixing portion. The first connecting member is provided with an inclined portion near the tank mounting portion that is inclined inward towards the rear or outward towards the rear to restrict the rotation of the projection portion relative to the first connecting member. The lower body structure of the vehicle according to claim 4.

6. The first connecting member has a first portion at the same height as the lower surface of the first cross member, and a second portion that extends upward from the rear end of the first portion towards the rear. The lower body structure of the vehicle according to claim 3.

7. The first connecting member has a bead in the first portion that protrudes downward and extends in the longitudinal direction of the vehicle. The lower body structure of a vehicle according to claim 6.

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