Vehicle undercarriage

Abstract

To sustain the performance of supporting an upper vehicle component on an upper side in a vehicle of a rear floor panel.SOLUTION: A vehicle understructure includes a rear floor panel 10a, side members 11, and a cross member 25. In the vehicle understructure, a support body 70 supporting a battery B or tank T (upper vehicle component) is disposed on an upper side in a vehicle of the rear floor panel 10a. On a lower side in the vehicle of the rear floor panel 10a, a brace 20 joined to the cross member 25 and side members 11 is disposed. The brace 20 is joined to an undersurface of the rear floor panel 10a. The support body 70 includes: brace-side fixtures 70a that are located on parts of an upper surface of the rear floor panel 10a which overlap the brace 20 and that are fixed to the brace 20; and side member-side fixtures 70b fixed to the side members 11.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Vehicle components such as a battery pack may be disposed on the upper side of a rear floor panel located at the rear of the vehicle, among floor panels that constitute a vehicle body floor portion of the vehicle.

[0003] For example, in the vehicle rear body structure disclosed in Patent Document 1, a battery pack is supported in a suspended state by a suspension frame, which is connected to a pair of left and right rear frames (side members). In other words, the battery pack is supported by the suspension frame and fixed to the rear frame, and is therefore positioned above the vehicle rear floor panel. The suspension frame has a weak point near the fastening point with the rear frame, and when the vehicle receives an impact load, the suspension frame bends starting from the weak point, thereby mitigating the impact. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-114190 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the structure of the above example, since a weak part is provided in the suspension frame, distortion is likely to occur in the suspension frame when the vehicle is traveling on an unpaved road, which reduces the support performance (mounting performance) of the vehicle parts and may make it impossible to ensure sufficient support performance.

[0006] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a vehicle undercarriage structure that can maintain support performance for vehicle parts located on the upper side of the rear floor panel. [Means for solving the problem]

[0007] The present invention provides a vehicle undercarriage structure that achieves the above-mentioned object, comprising: a floor panel that constitutes a vehicle body floor portion; side members that are provided on both vehicle widthwise outer sides of the floor panel and extend in the fore-and-aft direction of the vehicle; and a cross member that is joined to the underside of a rear floor panel of the floor panels that is located at the rear of the vehicle and extends in the vehicle width direction between the side members on both sides. In this vehicle undercarriage structure, a support body that supports a vehicle component is provided on the vehicle upper side of the rear floor panel. In this vehicle undercarriage structure, a brace is provided on the vehicle lower side of the rear floor panel that is joined to the cross member and the side members, the brace is joined to the underside of the rear floor panel, and the support body has a brace-side fixing portion that is located at a portion of the upper surface of the rear floor panel that overlaps with the brace in a plan view seen from above the vehicle and is fixed to the brace, and a side-member-side fixing portion that is fixed to the side member. [Effects of the Invention]

[0008] According to the present invention, it is possible to maintain the support performance of the rear floor panel for upper vehicle components arranged on the upper side of the vehicle. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a bottom view showing an embodiment of a vehicle underbody structure according to the present invention; [Figure 2] FIG. 2 is a bottom view showing a state in which the rear suspension of FIG. 1 has been removed. [Figure 3] FIG. 2 is a perspective view of the vehicle undercarriage structure as viewed from above the vehicle. [Figure 4] FIG. 2 is a partial top view of the vehicle undercarriage. [Figure 5] 3 is a front view of the restricting member and the spare tire of FIG. 2 as viewed from the front of the vehicle. [Figure 6] 5 is an enlarged perspective view showing the brace and other components on the left side of FIG. 4 as viewed from above the vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one embodiment of a vehicle undercarriage structure for a vehicle according to the present invention will be described with reference to the drawings (FIGS. 1 to 6). In the drawings, the direction of arrow Fr indicates the front in the longitudinal direction of the vehicle. In the description of the embodiment, the "front (front end) and rear (rear end)" correspond to the front and rear in the longitudinal direction of the vehicle. Furthermore, arrows R and L indicate the right and left sides when an occupant looks forward of the vehicle. Furthermore, arrow U indicates the upper side of the vehicle, and arrow D indicates the lower side of the vehicle.

[0011] As shown in FIGS. 1 to 4 , the vehicle undercarriage of this embodiment includes a metal floor panel 10 that constitutes a vehicle body floor, and side members 11 that are provided on both vehicle widthwise outer sides of the floor panel 10 and extend in the vehicle longitudinal direction. The floor panel 10 is a plate-shaped member formed of a metal material. The vehicle undercarriage also includes a cross member 25, an auxiliary cross member 28, and a brace 20. A rear floor panel 10a, which is located at the rear of the vehicle, is provided with a fuel tank 50 and a spare tire 55, both of which are lower vehicle components, attached to the underside of the rear floor panel 10a. A restricting member 30 that restricts movement of the spare tire 55 is also provided on the underside of the rear floor panel 10a. The spare tire 55 is located rearward of the fuel tank 50, which is also a lower vehicle component, and spaced apart from it. Note that the rear floor panel 10a, the fuel tank 50, and a rear bumper 65, which will be described later, have been removed from FIG. 3 .

[0012] Furthermore, a rear suspension 40 is provided on the underside of the rear floor panel 10a, as shown in Fig. 1. A suspension arm 41 extending in the front-to-rear direction of the vehicle is provided on the outer side in the vehicle width direction of the rear suspension 40. In addition, a rear bumper 65 extending in the vehicle width direction is disposed at the rear end of the floor panel 10 (see Figs. 1 and 2).

[0013] A support 70 that supports a battery B or a tank T as an upper vehicle component is provided on the vehicle upper side of the rear floor panel 10a (see FIGS. 3 and 4). That is, the battery B or the tank T is disposed on the vehicle upper side of the rear floor panel 10a. The battery B is a vehicle component that enables electrical drive and is used in hybrid vehicles and electric vehicles, and the tank T is filled with, for example, compressed natural gas to be supplied to the vehicle's drive source.

[0014] Each side member 11 is a highly rigid member that constitutes the vehicle body frame and is made of metal. Side members 11 are provided on the outer sides of floor panel 10 in the vehicle width direction and extend in the vehicle front-to-rear direction. Side members 11 have a U-shaped cross section that opens toward the top of the vehicle, and a flange is provided at the edge of the opening. The flange is joined to the underside of floor panel 10 by spot welding or the like.

[0015] Further, a suspension support portion 12 that supports a suspension arm 41 is provided on the underside of the side member 11. A suspension spring and the like (not shown) are disposed on the suspension arm 41 corresponding to the suspension support portion 12. An arm mounting bracket 15 to which the front portion of the suspension arm 41 is rotatably mounted is provided on the vehicle front side of the suspension support portion 12 on the underside of the side member 11.

[0016] The cross member 25 is a metal member extending in the vehicle width direction between the side members 11 on both sides, and, like the side members 11, is a highly rigid member that constitutes the vehicle body frame. The cross member 25 has a U-shaped cross section, and a flange is provided at the opening edge, and the flange is joined to the underside of the rear floor panel 10a by spot welding or the like. The vehicle width direction end of the cross member 25 is joined to the side member 11. The vehicle width direction end of the cross member 25 is located between the suspension support part 12 and the arm mounting bracket 15 in the vehicle fore-and-aft direction. In addition, the main body of the rear suspension 40 is located below the cross member 25.

[0017] Additionally, brackets (26a, 26b) are provided at the front of the cross member 25 for fixing the rear of a fuel tank 50, which serves as a lower vehicle component and into which gasoline is refilled. In this example, the brackets, a right-side bracket 26a for fixing the fuel tank and a left-side bracket 26b for fixing the fuel tank, are disposed at a distance from each other in the vehicle width direction and joined to the front of the cross member 25 and to the rear floor panel 10a. The fuel tank 50 can be replaced with a battery 51, and may be any important component related to vehicle drive.

[0018] The auxiliary cross member 28 is a metal member that extends in the vehicle width direction between the side members 11 on both sides, and, like the cross member 25, is a highly rigid member that constitutes the vehicle body frame. The auxiliary cross member 28 is disposed at a distance from the cross member 25 toward the rear of the vehicle, and, like the cross member 25, is joined to the underside of the rear floor panel 10a. A tire mounting portion 60 that accommodates a spare tire 55 is provided on the vehicle lower side of the auxiliary cross member 28. The spare tire 55 is attached in a horizontal position to the underside of the rear floor panel 10a via the tire mounting portion 60. The tire mounting portion will be described later.

[0019] Next, the brace 20 will be described. The brace 20 is provided on the vehicle lower side of the rear floor panel 10a and is joined to the cross member 25 and the side member 11. The brace 20 is also joined to the underside of the rear floor panel 10a. In this example, the brace 20 is a highly rigid member made of a metal material, and extends so as to incline generally outward in the vehicle width direction as it approaches the rear of the vehicle. A restricting member 30 is joined to the brace 20. The brace 20 will be described in detail below.

[0020] 1 to 4, braces 20 are provided corresponding to the side members 11 on both sides. The front ends of the braces 20 extend in the vehicle width direction and are joined by spot welding or the like to the underside of the cross member 25. Furthermore, brackets (26a, 26b) for fixing the fuel tank are joined to the front side of the vehicle of the joint of the braces 20 on the cross member 25 (i.e., the joint of the front ends of the braces 20 on the cross member 25).

[0021] The outer end of the brace 20 in the vehicle width direction extends in the vehicle front-rear direction along the side member 11, and is joined to the inner part of the side member 11 in the vehicle width direction by spot welding or the like.

[0022] The rear portion of the brace 20 has a rear wall that protrudes downward from the underside of the rear floor panel 10a, and the rear wall extends inward in the vehicle width direction from the rear end of the brace 20 at the outer end in the vehicle width direction, curves toward the front of the vehicle, and extends so as to slope toward the front of the vehicle as it extends inward in the vehicle width direction, and is connected to the inner portion in the vehicle width direction at the front end of the brace 20. A rear flange 21a is provided at the upper end of the rear portion of the brace 20. The rear flange 21a protrudes toward the rear of the vehicle and extends in accordance with the sloped shape of the rear wall. The rear flange 21a is joined to the underside of the rear floor panel 10a by spot welding or the like.

[0023] The front portion of the brace 20 on the outer side in the vehicle width direction has a front wall that protrudes downward from the underside of the rear floor panel 10a, and the front wall is L-shaped when viewed from above the vehicle. The front wall extends inward in the vehicle width direction from the front end of the brace 20 on the outer side in the vehicle width direction, curves toward the front of the vehicle, extends forward, and is connected to the front end of the brace 20 on the outer side in the vehicle width direction. An outer flange 21b corresponding to the L-shape is provided at the upper end of the front wall. The outer flange 21b is joined to the rear floor panel 10a by spot welding or the like. The front wall is disposed opposite a corner 11a formed by the outer side in the vehicle width direction of the cross member 25 and the inner side in the vehicle width direction of the side member 11. In other words, the brace 20 is disposed so as to straddle the corner 11a.

[0024] In other words, brace 20 consists of the rear wall, the front wall, a bottom wall connecting the lower end of the rear wall with the lower end of the front wall, a rear flange 21a, and an outer flange 21b, and has a roughly hat-shaped cross-sectional shape that opens toward the top of the vehicle, and is joined to side member 11, cross member 25, and rear floor panel 10a near corner 11a.

[0025] Next, the restricting member 30 will be described. The restricting member 30 is a member that extends in the vehicle width direction as a whole, and in this example, is formed by curving both sides of a hollow member that extends in the vehicle width direction. A vehicle width direction intermediate portion of the restricting member 30 is disposed on the vehicle lower side with a gap between it and the underside of the rear floor panel 10a, and a vehicle width direction outer portion of the restricting member 30 is joined to the vehicle body floor portion. The restricting member 30 is disposed between the fuel tank 50 and the spare tire 55 in the vehicle front-rear direction, and more specifically, between the cross member 25 and the spare tire 55.

[0026] As shown in FIG. 5 , a downward extending portion 32 and a curved portion 33 are provided on the outer side of the restricting member 30 in the vehicle width direction. The downward extending portion 32 is joined to the lower surface of the brace 20 and extends from the lower surface of the brace 20 downward toward the vehicle. The curved portion 33 is formed such that the lower portion of the downward extending portion 32 curves inward in the vehicle width direction. The downward extending portion 32 is joined to the lower surface of the brace 20 via a joining member 37. The lower portion of the downward extending portion 32 is joined to the joining member 37 by welding or the like. The joining member 37 is also fastened to the lower surface of the brace 20 with a bolt. The downward extending portion 32 of the restricting member 30 in this embodiment is joined to the side member 11 and the cross member 25 via the brace 20.

[0027] Moreover, one end of the restricting member 30 is fixed to one brace 20, and the other end of the restricting member 30 is fixed to the other brace 20. Specifically, the joint member 37 of one downward extension portion 32 of the restricting member 30 is joined to one brace 20, and the joint member 37 of the other downward extension portion 32 of the restricting member 30 is joined to the other brace 20.

[0028] The restricting member 30 of this embodiment and the spare tire 55 are disposed with a gap between them in the vehicle longitudinal direction. The restricting member 30 of this embodiment is formed by bending a metal member into a pipe shape with a circular cross section. The diameter of the restricting member 30 is set to be larger than the diameter of a support member 61, which will be described later.

[0029] As described above, the regulating member 30 is joined to the rear floor panel 10a with a gap therebetween and is positioned between the spare tire 55 and the fuel tank 50, so that the regulating member 30 can prevent the spare tire 55 from flying out toward the front of the vehicle and colliding with the fuel tank 50 when an impact load due to a rear-end collision or the like is applied.

[0030] For example, if an attempt were made to restrict the movement of spare tire 55 by deforming a portion of cross member 25 to provide a portion facing spare tire 55, the cross member 25 would need to ensure rigidity as a vehicle body frame member, which could restrict the shape of the facing portion and result in a decrease in the degree of freedom in the layout of the member. In contrast, the restricting member 30 of this embodiment is a pipe-shaped member and is provided at a distance from rear floor panel 10a, so that the restricting member 30 does not need to be larger than necessary, and the degree of freedom in the layout of the member is improved.

[0031] In addition, in this embodiment, the restricting member 30 is joined to the brace 20, which is joined to the cross member 25 and the side member 11, which are body frame members. This allows the load from the spare tire 55 input to the restricting member 30 to be transmitted to the cross member 25 and the side member 11. This improves the rigidity of the joint between the restricting member 30 and the brace 20 and the joint between the brace 20 and the connecting member 37 (in this example, the bolt fastening portion of the connecting member 37). Furthermore, the brace 20, which is smaller in volume than the body frame members, offers greater flexibility in shape, thereby improving layout flexibility. In this embodiment, the restricting member 30 is also joined to the rear floor panel 10a via the brace 20, allowing the load to be distributed over a wider area. Furthermore, joining the restricting member 30 between the left and right braces 20 shortens the width of the restricting member 30, thereby improving the longitudinal rigidity of the restricting member 30. As a result, even if the spare tire 55 comes into contact with the restricting member 30 during a rear collision, the restricting member 30 can restrict the spare tire 55 from moving forward.

[0032] Furthermore, because the brace 20 is joined to the side member 11 and the cross member 25 while spanning the rear of the corner 11a, when the spare tire 55 collides with the restricting member 30, it can be supported by the highly rigid corner 11a formed by the side member 11 and the cross member 25. As shown in FIG. 2, the outer end of the brace 20 in the vehicle width direction is joined to the side member 11 at a position corresponding to the suspension support part 12, so that the load transmitted to the brace 20 can be transmitted to a highly rigid part of the side member 11.

[0033] Furthermore, by providing the downward extension portion 32 and the curved portion 33 on the outer side of the regulating member 30 in the vehicle width direction, the area of ​​the spare tire 55 that the regulating member 30 comes into contact with is wider when the spare tire 55 flies out in front of the vehicle, which promotes impact absorption by the regulating member 30 and further enhances the effect of reducing damage to the fuel tank 50.

[0034] Furthermore, in this embodiment, the vehicle width direction intermediate portion of the regulating member 30 has a downward convex shape (convex shape) 31 that is convex toward the rear floor panel 10a. In this example, the vehicle width direction intermediate portion of the regulating member 30 is formed so as to be convex toward the front of the vehicle as well. Providing the downward convex shape 31 increases the contact area between the rear portion of the regulating member 30 and the spare tire 55, making it easier to withstand the load from the spare tire 55, further suppressing collision of the spare tire 55 with the fuel tank 50 and further enhancing the effect of reducing damage to the fuel tank 50.

[0035] Furthermore, in this embodiment, the vehicle width direction intermediate portion of the regulating member 30 is slightly convex toward the front of the vehicle, which corresponds to the outer shape (circular shape) of the spare tire 55, and the spare tire 55 can be guided to the portion that convex toward the front, making it possible to control the direction in which the spare tire 55 abuts against the regulating member 30. Furthermore, since the regulating member 30 is disposed at a distance toward the front of the vehicle from the spare tire 55, the spare tire 55 is more likely to abut against the portion that convex toward the front. As a result, when the spare tire 55 moves toward the front of the vehicle, the regulating member 30 can more easily receive the spare tire 55.

[0036] Next, the tire mounting portion 60 will be described. The tire mounting portion 60 is provided on the vehicle lower side of the rear floor panel 10a, and as shown in Figures 1 and 2, has a support member 61 and an auxiliary member 62. The support member 61 is U-shaped in a top view, opening toward the front of the vehicle, and the front ends of the U-shape on both sides in the vehicle width direction are curved upward toward the vehicle and are rotatably connected to rotating portions 34 (described later) of the restricting member 30. The rear end of the U-shape is curved upward toward the vehicle so as to support the rear portion of the spare tire 55.

[0037] In addition, the auxiliary member 62 is a member that is joined to the middle part of the support member 61 in the vehicle's fore-and-aft direction and extends in the vehicle width direction, and both sides in the vehicle width direction are curved upward of the vehicle so as to support the sides of the spare tire 55.

[0038] The restricting member 30 is provided with two rotating parts 34 arranged at an interval from each other. These rotating parts 34 have shafts (not shown) extending in the vehicle width direction, and the front part of the support member 61 is configured to be rotatable around the shafts of the rotating parts 34.

[0039] As the support member 61 rotates, the rear portion of the support member 61 moves downwards on the vehicle, and the spare tire 55 is placed on the support member 61 and the auxiliary member 62. After that, the rear portion of the support member 61 is moved upwards on the vehicle and the rear portion of the support member 61 is engaged with the underside of the vehicle body by the engaging portion 63, thereby attaching the spare tire 55. While supported by the support member 61 and the auxiliary member 62, the spare tire 55 can rotate so that the rear portion of the spare tire 55 moves downwards on the vehicle.

[0040] 5 , when the spare tire 55 is supported by the support members 61 and the auxiliary members 62 and attached to the tire mounting portion 60, the intermediate portion of the regulating member 30 in the vehicle width direction is disposed between the upper and lower ends of the spare tire 55. Thus, by supporting the spare tire 55 with the support members 61, the angle of the spare tire 55 in the event of a collision can be adjusted, and by setting the positional relationship between the regulating member 30 and the spare tire 55 within the above range, it is possible to control the load transmitted to the spare tire 55 so that most of it is input to the regulating member 30.

[0041] Next, the support body 70 will be described with reference to Figures 3, 4, 6, etc. In this embodiment, the support body 70 supports a battery B or a tank T as an upper vehicle component, and is used to arrange the battery B or the tank T on the vehicle upper side of the rear floor panel 10a. Note that the rear floor panel 10a is not shown in Figure 6.

[0042] The support body 70 has a brace-side fixing portion 70a that is located at a portion that overlaps with the brace 20 on the upper surface of the rear floor panel 10a in a plan view seen from above the vehicle and is fixed to the brace 20, and a side-member-side fixing portion 70b that is fixed to the side member 11. In other words, the battery B or the tank T is fixed to the support body 70, and the support body 70 to which the battery B or the tank T is fixed is fixed (attached) to a vehicle body structure (the brace 20, the side member 11) via the brace-side fixing portion 70a and the side-member-side fixing portion 70b.

[0043] Specifically, the support body 70 has a front frame 71 extending in the vehicle width direction, a rear frame 72 extending in the vehicle width direction behind the front frame 71, a left support frame 73 and a right support frame 74 connecting the front frame 71 and the rear frame 72 and spaced apart from each other in the vehicle width direction, a left fixed frame 75 fixed to the left brace 20, and a right fixed frame 76 fixed to the right brace 20.

[0044] The front frame 71 is made of metal and extends linearly in the vehicle width direction. The front frame 71 has a length slightly shorter than the distance between the left and right side members 11, and is located between the left and right side members 11 when viewed from above the vehicle.

[0045] The rear frame 72 is formed from a metal member and has a straight portion 72a, a left leg portion 72b, and a right leg portion 72c. The straight portion 72a has a length in the vehicle width direction that is approximately the same as that of the front frame 71. The left leg portion 72b continues from the left end portion of the straight portion 72a in the vehicle width direction, extends from the left end portion toward the rear of the vehicle as seen from above the vehicle, and extends from the left end portion to the upper surface of the left side member 11. The right leg portion 72c continues from the right end portion of the straight portion 72a in the vehicle width direction, extends from the right end portion toward the rear of the vehicle as seen from above the vehicle, and extends from the right end portion to the upper surface of the right side member 11.

[0046] The left support frame 73 and the right support frame 74 are each formed from a metal member and joined to the front frame 71 and the rear frame 72 by welding or the like, thereby connecting the front frame 71 and the rear frame 72. The longitudinal middle portions of the left support frame 73 and the right support frame 74 are curved to match the shape of the body of the battery B or the tank T. The left portion of the body in the vehicle width direction is supported from below by the curved middle portion of the left support frame 73, and the right portion of the body in the vehicle width direction is supported from below by the curved middle portion of the right support frame 74. The front end portion of the left support frame 73 and the front end portion of the right support frame 74 protrude further forward than the front frame 71 of the vehicle, and the rear end portion of the left support frame 73 and the rear end portion of the right support frame 74 protrude further rearward than the rear frame 72 of the vehicle. A band 77 is wrapped around the upper body of the battery B or tank T supported in the middle portion of each support frame (73, 74), and the ends of the band 77 are connected to the ends of each support frame (73, 74).

[0047] The left fixed frame 75 and the right fixed frame 76 are each formed from a metal member and joined by welding or the like to a lower portion of the front frame 71 and a lower portion of the rear frame 72, thereby connecting the front frame 71 and the rear frame 72. The left fixed frame 75 and the right fixed frame 76 each have a U-shaped cross section that opens toward the top of the vehicle and extends in the front-to-rear direction of the vehicle. When viewed from above the vehicle, the left fixed frame 75 is located between the left end of the front frame 71 and the left support frame 73, and the right fixed frame 76 is located between the right end of the front frame 71 and the right support frame 74. The front end of the left fixed frame 75 and the front end of the right fixed frame 76 protrude further forward than the front frame 71, and the rear end of the left fixed frame 75 and the rear end of the right fixed frame 76 protrude further rearward than the rear frame 72.

[0048] In this embodiment, in a plan view seen from above the vehicle, the front end of the left fixing frame 75 is located at a portion of the upper surface of the rear floor panel 10a that overlaps with the left brace 20 and is fixed to the left brace 20, and the front end of this left fixing frame 75 constitutes the left brace-side fixing portion 70a. In a plan view seen from above the vehicle, the front end of the right fixing frame 76 is located at a portion of the upper surface of the rear floor panel 10a that overlaps with the right brace 20 and is fixed to the right brace 20, and the front end of this right fixing frame 76 constitutes the right brace-side fixing portion 70a.

[0049] In this embodiment, the brace-side fixing portion 70a is disposed more inward in the vehicle width direction than the side-member-side fixing portion 70b. The brace 20 to which the brace-side fixing portion 70a is fixed is disposed so as to straddle the corner 11a. The side-member-side fixing portion 70b is disposed more rearward in the vehicle than the brace-side fixing portion 70a. Specifically, a line connecting the brace-side fixing portion 70a and the side-member-side fixing portion 70b is defined as a first imaginary line L1, and a line extending in the inclination direction of the brace 20 (for example, a line extending in the direction of the rear wall of the brace 20) is defined as a second imaginary line L2. In this case, on the left side in the vehicle width direction, the angle formed by the second imaginary line L2 and the vehicle width-direction inner surface of the left side member 11 is set to be larger than the angle formed by the first imaginary line L1 and the vehicle width-direction inner surface of the left side member 11. The same applies to the right side in the vehicle width direction.

[0050] In this embodiment, a reinforcing plate 80 is joined to each brace 20, and each brace-side fixing portion 70a is fixed to the brace 20 via the reinforcing plate 80.

[0051] Specifically, the reinforcing plate 80 is formed from a metal plate and is joined to the upper surface of the brace 20. The reinforcing plate 80 comprises a reinforcing plate main body 81 located on the upper surface of the bottom wall of the brace 20, and a reinforcing plate rear portion 82 formed integrally with the reinforcing plate main body 81 and extending along a portion of the rear wall of the brace 20 and along a portion of the upper surface of the rear flange 21a of the brace 20. A middle portion of the reinforcing plate main body 81 in a direction along the rear wall bulges outward toward the vehicle, and an upper wall 81a of this middle portion has an upper surface parallel to the bottom wall of the brace 20. The lower surface of the rear floor panel 10a abuts against the upper wall 81a. Reinforcing plate flange portions 81b, which are portions on both sides of the middle portion of the reinforcing plate main body 81, are fastened to the bottom wall of the brace 20 with first bolts 83. Furthermore, the reinforcing plate 80 has a rear portion 82 joined to the rear wall or rear flange 21a of the brace 20 by welding or the like. In this way, the reinforcing plate 80 is fixed to the upper surface side of the brace 20 by fastening and joining. Furthermore, an insertion hole through which a second bolt 84 is inserted is opened in each of the upper wall 81a, a portion of the rear floor panel 10a corresponding to the upper wall 81a, and the brace-side fixing portion 70a which is the front end of each fixing frame (75, 76) of the support body 70. Then, with the second bolt 84 inserted into each insertion hole, the threaded portion of the second bolt 84 is screwed into a nut welded to the underside of the upper wall 81a, whereby the brace-side fixing portion 70a is fastened and fixed to the brace 20 via the reinforcing plate 80.

[0052] In this embodiment, a bolt fastening point by a second bolt 84 to the brace 20 via the reinforcing plate 80 of the brace side fixing portion 70a is located between two bolt fastening points by a first bolt 83 to the brace 20.

[0053] In this embodiment, the connecting member 37 of the restricting member 30 is located in a portion of the underside of the brace 20 that corresponds to the reinforcing plate 80. That is, the bottom wall of the brace 20 is sandwiched between the reinforcing plate 80 and the connecting member 37. Furthermore, insertion holes through which first bolts 83 are inserted are formed in each of the reinforcing plate flange portions 81b of the reinforcing plate main body 81, the portion of the bottom wall of the brace 20 that corresponds to the reinforcing plate flange portion 81b, and the portion of the connecting member 37 that corresponds to the reinforcing plate flange portion 81b. With the first bolts 83 inserted into the respective insertion holes, the threaded portions of the first bolts 83 are screwed into nuts 85 on the upper surfaces of the reinforcing plate flange portions 81b, thereby fastening and fixing the reinforcing plate 80 together with the connecting member 37 to the brace 20.

[0054] As described above, in the vehicle undercarriage structure according to this embodiment, the support body 70, which is provided on the vehicle upper side of the rear floor panel and supports the battery B or the tank T (upper vehicle component), has a brace-side fixing portion 70a that is located at a portion that overlaps with the brace 20 on the upper surface of the rear floor panel 10a in a plan view seen from above the vehicle and is fixed to the brace 20, and a side-member-side fixing portion 70b that is fixed to the side member 11. In other words, the support body 70 to which the battery B or the tank T is fixed has the brace-side fixing portion 70a that is fixed to the brace 20 that is joined to the cross member 25 and the side member 11 that constitute the body frame, and the side-member-side fixing portion 70b that is fixed to the side member 11 that also constitutes the body frame. As a result, when an impact load generally from the rear to the front of the vehicle or an impact load in the vertical direction of the vehicle acts on the support body 70 due to a minor collision from the rear of the vehicle or driving on an unpaved road, the impact load can be transmitted to the side members 11 and the cross members 25 through the brace-side fixing portions 70a, the side-member-side fixing portions 70b, and the braces 20, effectively suppressing the occurrence of deformation such as distortion. As a result, the vehicle undercarriage structure according to this embodiment can maintain the support performance (mounting performance) for the battery B or tank T (upper vehicle component) arranged on the vehicle upper side of the rear floor panel 10a.

[0055] In more detail, since the brace 20 is joined to the side member 11 and the cross member 25 which extend in two mutually perpendicular directions, the brace side fixing portion 70a fixed to the brace 20 is integrated with the brace 20 and has high rigidity in the fore-and-aft direction and the up-and-down direction of the vehicle, and the side member side fixing portion 70b is integrated with the side member 11 and has high rigidity in the direction along the side member 11.

[0056] In this embodiment, one end of the restricting member 30 is fixed to one brace 20, and the other end of the restricting member 30 is fixed to the other brace 20, so that the brace 20 is fixed to the restricting member 30 in addition to the side member 11 and the cross member 25. Therefore, even if an impact acts on the brace 20 in the vertical direction or the longitudinal direction of the vehicle, movement and deformation of the brace 20 are effectively restricted. As a result, the rigidity of the portion of the brace 20 to which the support body 70 is fixed is improved, and the support performance of the battery B or the tank T (upper vehicle component) is improved.

[0057] Furthermore, the regulating member 30 is fixed to the brace 20 from below the vehicle, and the cross member 25 is fixed to the brace 20 from the front of the vehicle, and since the regulating member 30 is fixed to the brace 20 from a direction different from that of the cross member 25, deformation of the brace 20 is effectively suppressed even if, for example, a load is concentrated on one of the braces 20.

[0058] In this embodiment, the brace-side fixing portion 70a of the support body 70 is disposed more inward in the vehicle width direction than the side-member-side fixing portion 70b. Therefore, when an impact load acts on the support body 70 from the rear of the vehicle, the impact load can be transmitted not only to the side member 11 but also to the cross member 25 via a transmission path generally along the imaginary line L1. Furthermore, the brace 20 is disposed so as to straddle the corner 11a formed by the cross member 25 and the side member 11. Therefore, the brace 20 extends in a direction inclined in the vehicle width direction with respect to the vehicle front-rear direction and is also joined to the side member 11. As a result, when an impact load acts on the support body 70 from the rear of the vehicle, the brace 20 can support the side member 11 so as to brace it in the direction of the second imaginary line L2 against the side member 11, further increasing rigidity.

[0059] In this embodiment, brackets (26a, 26b) for fixing the fuel tank 50 (a lower vehicle component) are joined to the cross member 25 at the portion of the cross member 25 on the vehicle front side of the joint where the brace 20 is joined, thereby improving the rigidity of the joint where the brace 20 is joined to the cross member 25, allowing the cross member 25 to withstand a load input toward the front of the vehicle via the brace 20 due to a rear-end collision or the like, and preventing deformation of the cross member 25. As a result, the position of the brace 20 is maintained unchanged, deformation of the brace 20 is more effectively suppressed, and ultimately the support performance of the support body 70 for the battery B or the tank T (an upper vehicle component) is more effectively maintained.

[0060] In this embodiment, a reinforcing plate 80 is joined to the brace 20, and the brace-side fixing portion 70a is fixed to the brace 20 via the reinforcing plate 80. This reinforces the inside of the brace 20 and improves the rigidity of the brace 20, thereby more effectively maintaining the support performance of the support body 70 for the battery B or the tank T.

[0061] The description of the present embodiment is merely an example for explaining the present invention, and does not limit the invention described in the claims. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0062] In this embodiment, the restricting member 30 is joined to the brace 20, but this is not limiting. The restricting member 30 may also be joined to the floor panel 10 or the cross member 25. The restricting member 30 does not necessarily have to be provided.

[0063] In this embodiment, the upper vehicle component supported by the support body 70 is a battery B or a tank T, and the tank T is filled with compressed natural gas, but the filled gas is not limited to this. Furthermore, when the upper vehicle component is a battery B, a fuel tank 50 as a lower vehicle component does not need to be provided, or a battery 51 may be provided instead of the fuel tank 50. Furthermore, lower vehicle components (for example, the fuel tank 50 or the battery 51) or a spare tire 55 at the rear of the vehicle as a lower vehicle component do not need to be provided. [Explanation of symbols]

[0064] 10...floor panel, 10a...rear floor panel, 11...side member, 11a...corner portion, 12...suspension support portion, 15...arm mounting bracket, 20...brace, 21a...rear flange, 21b...outer flange, 25...cross member, 26a...right side bracket (bracket) for fixing fuel tank, 26b...left side bracket (bracket) for fixing fuel tank, 28...auxiliary cross member, 30...regulating member, 31...downward convex shape (convex shape), 32...downward extension portion, 33...curved portion, 34...rotating portion, 37...joint member, 40...rear suspension, 41...suspension arm, 50...fuel tank (lower vehicle part), 51...battery (lower vehicle part), 55...spare Tire, 60... tire mounting portion, 61... support member, 62... auxiliary member, 63... engaging portion, 65... rear bumper, 70... support body, 70a... brace side fixing portion, 70b... side member side fixing portion, 71... front frame, 72... rear frame, 72a... straight portion, 72b... left leg portion, 72c... right leg portion, 73... left support frame, 74... right support frame, 75... left fixing frame, 76... right fixing frame, 77... band, 80... reinforcing plate, 81... reinforcing plate main body, 81a... upper wall, 81b... reinforcing plate flange portion, 82... reinforcing plate rear portion, 83... first bolt, 84... second bolt, 85... nut, L1... first imaginary line, L2... second imaginary line, B... battery (upper vehicle part), T... tank (upper vehicle part)

Claims

1. The vehicle comprises a floor panel constituting a vehicle body floor portion, side members provided on both outer sides of the floor panel in the vehicle width direction and extending in the vehicle front-rear direction, and a cross member joined to the underside of a rear floor panel of the floor panels located at the rear of the vehicle and extending in the vehicle width direction between the side members on both sides, a support body for supporting an upper vehicle component is provided on an upper side of the rear floor panel, a brace joined to the cross member and the side member is provided on the vehicle lower side of the rear floor panel, The brace is joined to the underside of the rear floor panel, the support body has a brace-side fixing portion that is located at a portion of the upper surface of the rear floor panel that overlaps with the brace in a plan view seen from above the vehicle and is fixed to the brace, and a side-member-side fixing portion that is fixed to the side member, a restricting member extending in the vehicle width direction is provided on the lower surface of the rear floor panel, a vehicle width direction intermediate portion of the restricting member is disposed on a vehicle lower side with a gap therebetween with respect to the lower surface of the rear floor panel, The braces are provided corresponding to the side members on both sides, a first end of the restricting member fixed to one of the braces, and a second end of the restricting member fixed to the other of the braces,

2. The vehicle width direction end of the cross member is joined to the side member, the brace-side fixing portion is disposed more inward in the vehicle width direction than the side-member-side fixing portion, 2. The vehicle underbody structure according to claim 1, wherein the brace is disposed so as to straddle a corner formed by the cross member and the side member.

3. 3. The vehicle underbody structure according to claim 1, wherein a bracket for fixing a lower vehicle component is joined to a portion of the cross member on the front side of the vehicle of the joint portion of the brace.

4. A reinforcing plate is joined to the brace, 4. The vehicle underbody structure according to claim 1, wherein the brace-side fixing portion is fixed to the brace via the reinforcing plate.

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