Vehicle substructure

Abstract

To provide a vehicle substructure that can suppress deformation of a frame member while protecting an on-vehicle member.SOLUTION: A vehicle substructure is provided with: a protective member 40 which is located below a frame member 2 so as to face an on-vehicle member 6 from an outer side in a vehicle width direction; and support members 50, 60 which are fixed to an undersurface of the frame member 2 and support the protective member 40. The support members 50, 60 are provided with: a bottom wall part 61 which includes an opposing part 61A facing an upper end part 43A of the protective member 40 in a vertical direction, and extends along an undersurface 2F of the frame member 2; and a vertical wall part 6 which extends downward with an inside edge of the bottom wall part 61 in the vehicle width direction as a base end. The vertical wall part 62 is provided with: a curved part 62C which curves so as to evaginate inward in the vehicle width direction; and an extension part 62D which extends to a tip side from the curved part 62C, and is positioned on an outer side in the vehicle width direction with respect to the curved part 62C.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] As disclosed in Patent Document 1, in vehicles in which on-board components such as a fuel tank are mounted at the bottom, consideration is being given to providing a protective member (the protective bar in Patent Document 1) on the side of the on-board component in the vehicle width direction in order to protect the on-board component.

[0003] Specifically, Patent Document 1 discloses a configuration in which a protective member (protective bar in Patent Document 1) bent downward into a crank shape is disposed on the side of the fuel tank in the vehicle width direction and fixed to the underside of a frame member (rear side frame in Patent Document 1) of the vehicle. Patent Document 1 also discloses a configuration in which a middle portion of the protective member is disposed below the frame member and at approximately the same height as the bottom of the fuel tank.

[0004] According to the configuration of Patent Document 1, when an obstacle collides with the vehicle from the side in the vehicle width direction, the protective member can prevent the obstacle from coming into contact with the fuel tank, thereby protecting the fuel tank. Also, when the vehicle passes over a step or the like in the road surface, the step or the like and the fuel tank can be kept apart by the contact between the middle part of the protective member and the step or the like, thereby preventing contact between the fuel tank and the step or the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-123584 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the configuration of Patent Document 1, the protective member is directly fixed to the lower surface of the frame member, which poses a problem that when a step or the like collides with the protective member, the frame member is likely to deform due to the collision load.

[0007] The present invention has been made in consideration of the above circumstances, and has an object to provide a vehicle underbody structure that can suppress deformation of a frame member while protecting an on-board member. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides an undercarriage of a vehicle comprising: an on-board member arranged below a floor panel of the vehicle; a frame member arranged outside the on-board member in the vehicle width direction; a protective member arranged below the frame member so as to face the on-board member from the outside in the vehicle width direction; and a support member fixed to the underside of the frame member and supporting the protective member, wherein the support member has a bottom wall portion including an opposing portion that faces an upper end of the protective member in the up-down direction and extends along the underside of the frame member, and a vertical wall portion extending downward from an inner edge of the bottom wall portion in the vehicle width direction as a base end, and the vertical wall portion has a curved portion that curves so as to bulge inward in the vehicle width direction, and an extension portion that extends from the curved portion toward the tip side and is positioned outside the curved portion in the vehicle width direction.

[0009] According to the present invention, the protective member is disposed at a position facing the on-board member on the outer side of the on-board member in the vehicle width direction, and the protective member is disposed below the frame member, so that when an obstacle collides with the vehicle from the side or below in the vehicle width direction, the protective member can prevent contact between the obstacle and the on-board member to protect the on-board member. In the present invention, the support member is disposed between the upper end of the protective member and the frame member. Therefore, it is possible to prevent the collision load from being directly applied from the protective member to the frame member, and deformation of the frame member can be suppressed. In addition to the bottom wall portion extending along the lower surface of the frame member, the support member is provided with a vertical wall portion extending downward from the inner edge of the bottom wall portion in the vehicle width direction as a base end. Therefore, the rigidity of the support member can be increased, the support member can stably support the protective member, and deformation of the support member and, in turn, deformation of the frame member can be more reliably suppressed.

[0010] Moreover, the vertical wall portion is provided with a curved portion that curves so as to bulge inward in the vehicle width direction, and an extension portion extending from the curved portion toward the tip side is disposed outward in the vehicle width direction from the curved portion. Therefore, when a load is applied to the frame member from the outside in the vehicle width direction during a side collision of the vehicle, and the vertical wall portion swings inward in the vehicle width direction about its upper position as a center, the curved portion of the vertical wall portion can be made to come into contact with the on-board member first. Therefore, it is possible to prevent the sharp tip of the vertical wall portion from coming into contact with the on-board member, and to suppress damage to the on-board member.

[0011] In the above configuration, preferably, the support member has a first support member including the bottom wall portion and the vertical wall portion, and a second support member formed separately from the first support member and fixed to the underside of the frame member, and the second support member has a second bottom wall portion extending along the bottom wall portion below the bottom wall portion or between the bottom wall portion and the frame member, and including a second opposing portion that faces the opposing portion in the vertical direction (Claim 2).

[0012] According to this configuration, two support members (the first support member and the second support member) are disposed between the upper end of the protection member and the frame member, which makes it possible to further suppress deformation of the frame member compared to the case where only the first support member is provided.

[0013] In the above configuration, preferably, the second support member has a second vertical wall portion extending downward from an inner edge in the vehicle width direction of the second bottom wall portion (claim 3).

[0014] According to this configuration, the rigidity of the second support member can be increased, and deformation of the second support member, and therefore deformation of the frame member, can be more reliably suppressed.

[0015] In the above configuration, preferably, a lower end of the second vertical wall portion is located above the curved portion (claim 4).

[0016] According to this configuration, the curved portion can be brought into contact with the on-vehicle member before the relatively sharp portion at the lower end of the second vertical wall portion comes into contact with the on-vehicle member. Therefore, while providing the second vertical wall portion on the second support member, it is possible to prevent the on-vehicle member from being damaged by the second vertical wall portion.

[0017] In the above configuration, preferably, the first support member and the second support member are fastened to the frame member by a common fastening member and joined to each other at positions forward and rearward of the fastening member in the vehicle fore-and-aft direction (claim 5).

[0018] According to this configuration, the first support member and the second support member can be fastened to the frame member using a common fastening member. Also, by joining the first support member and the second support member to each other at positions forward and rearward of the fastening portion, the first support member and the second support member can be integrated and stably supported by the frame member.

[0019] In the above configuration, preferably, the first support member and the second support member are fastened to the frame member by the fastening member at a position forward of the opposing portion in the vehicle fore-and-aft direction, and are joined to each other at a position rearward of the center of the opposing portion in the vehicle fore-and-aft direction (claim 6).

[0020] In this configuration, the first support member and the second support member are connected at the front and rear sides of the center of the facing portion, i.e., the center of the upper end of the protective member. As a result, the load applied to the facing portion and the second facing portion from the upper end of the protective member is stably received by the two first support members and the second support member. Therefore, deformation of the first and second support members can be suppressed, and the protective member can be stably supported by the support members.

[0021] In the above configuration, preferably, the extension portion extends downward from the curved portion (claim 7).

[0022] With this configuration, with a simple configuration, the above-mentioned vertical wall portion can be realized in the support member, which has the above-mentioned curved portion and has a shape in which the extension portion extending from the curved portion toward the tip side is positioned further outboard in the vehicle width direction than the curved portion. Effect of the Invention

[0023] As described above, according to the vehicle underbody structure of the present invention, it is possible to suppress deformation of the frame member while arranging a protective member on the underside of the frame member. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 is a bottom view showing a part of the rear of the vehicle. [Diagram 2] FIG. 2 is a side view showing a portion of the rear of the vehicle. [Diagram 3] 2 is a schematic perspective view of a part of the rear of the vehicle as viewed from the outside in the vehicle width direction. FIG. [Figure 4] 4 is a schematic perspective view of the rear end portion and its periphery of the protective member as viewed from the inside in the vehicle width direction. FIG. [Diagram 5]3 is a schematic cross-sectional view taken along line VV in FIG. 2. [Figure 6] FIG. 3 is a schematic cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is an enlarged view of a portion of FIG. 6. [Figure 8] 4 is a schematic side view of the periphery of a rear end portion of the protective member as viewed from the inside in the vehicle width direction. FIG. [Figure 9] FIG. 2 is a schematic cross-sectional view for explaining an effect. [Figure 10] FIG. 8 is a schematic cross-sectional view according to a modified example, which corresponds to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Fig. 1 is a schematic bottom view showing a part of the rear of a vehicle V to which an undercarriage according to an embodiment of the present invention is applied. Fig. 2 is a schematic side view showing a part of the rear of a vehicle V. In the following description, the front-rear direction of the vehicle will be referred to as the front-rear direction, and the vehicle width direction when looking forward will be referred to as the left-right direction, as appropriate.

[0026] (Overall structure of the rear of the vehicle) A pair of rear side frames 2, 2 extending in the front-rear direction and constituting a part of the vehicle body are provided on both the left and right sides of the vehicle V. The two rear side frames 2, 2 are symmetrically configured. The rear side frame 2 extends to the vicinity of the front end of the rear wheel 1. The rear side frame 2 extends substantially horizontally except for the rear end 2A. On the other hand, the rear end 2A of the rear side frame 2 is curved so as to be positioned higher toward the rear. In other words, the rear end 2A of the rear side frame 2 is curved obliquely upward toward the rear. From the rear end of the rear side frame 2, a wheel house panel 8 surrounding the rear wheel 1 extends rearward. In this embodiment, the rear side frame 2 is composed of a plurality of plate-shaped members. The rear side frame 2 corresponds to the "frame member" of the present invention.

[0027] A floor panel 4 constituting the floor surface of the vehicle compartment is provided between the two rear side frames 2. A fuel tank 6 for storing fuel is disposed below the floor panel 4 and in the space between the rear side frames 2. In other words, each rear side frame 2 is disposed on both outer sides of the fuel tank 6 in the left-right direction, and extends in the front-rear direction on both outer sides of the fuel tank 6 in the vehicle width direction. The fuel tank 6 corresponds to the "vehicle-mounted member" in this invention.

[0028] The fuel tank 6 is disposed below the floor panel 4 and is fixed to a cross member (not shown) provided on the floor panel 4 and extending in the left-right direction. The fuel tank 6 extends from a position forward of the rear wheels 1 to a position rearward of the front ends of the rear wheels 1 in the front-rear direction, and the rear part of the fuel tank 6 overlaps with the rear wheels 1 in a side view (when viewed along the left-right direction). The left-right dimension of the fuel tank 6 is set to a dimension slightly smaller than the left-right separation distance between the two rear side frames 2, 2, and the fuel tank 6 occupies most of the area between the rear side frames 2, 2 in the left-right direction. The up-down dimension of the fuel tank 6 is set so that the lower end of the fuel tank 6 is located lower than the lower ends of the rear side frames 2 when the fuel tank 6 is fixed below the floor panel 4. In other words, the fuel tank 6 is fixed to a cross member (not shown) provided on the floor panel 4 and extending in the left-right direction, in a state where it protrudes downward from the lower ends of the rear side frames 2.

[0029] A suspension frame 20 that supports suspensions (not shown) for a pair of left and right rear wheels 1 (only the right rear wheel 1 is shown in the figure) is provided at the rear of the vehicle V. The suspension frame 20 includes a pair of left and right sub-frames 21, 21 and a rear suspension cross 22 that extends laterally between these sub-frames 21, 21.

[0030] Each subframe 21 is connected to the rear side frame 2 via a support panel 25 described below. Specifically, the right subframe 21 is connected to the right rear side frame 2 via the right support panel 25, and the left subframe 21 is connected to the left rear side frame 2 via the left support panel 25. Each subframe 21 passes below the wheel house panel 8 extending rearward from the rear side frame 2 to which it is connected, and extends rearward from a position rearward of the rear end of the rear side frame 2.

[0031] In this embodiment, a bush retaining portion 21A, which is generally cylindrical and extends in the vertical direction and retains a bush, is provided at the front end of each subframe 21. Each bush retaining portion 21A is fixed to the rear end portion of the gusset frame 50. Each bush retaining portion 21A is disposed between the rear end portion of the gusset frame 50 and a support panel 25 disposed above the rear end portion, and is fixed to the rear end portion of the gusset frame 50 and the support panel 25.

[0032] The rear suspension cross 22 is located behind the fuel tank 6. In other words, the fuel tank 6 is disposed in a region surrounded by the pair of rear side frames 2, 2 and the rear suspension cross 22.

[0033] The vehicle V is provided with a pair of left and right protective members 40, 40 for protecting the fuel tank 6. These protective members 40 are disposed on both left and right sides of the fuel tank 6, i.e., on both outer sides of the fuel tank 6 in the vehicle width direction.

[0034] (Protective materials and their surrounding structures) Next, the structure of the protection member 40 and its surroundings will be described. Fig. 3 is a schematic perspective view of a part of the rear of the vehicle V as seen from the right side, i.e., from the outside in the vehicle width direction. Fig. 4 is a schematic perspective view of the periphery of the rear end of the right protection member 40 as seen from the left side, i.e., from the inside in the vehicle width direction. Fig. 5 is a schematic cross-sectional view taken along line VV in Fig. 4. Fig. 6 is a schematic cross-sectional view taken along line VI-VI in Fig. 4. Fig. 7 is an enlarged view of a part of Fig. 6.

[0035] The two protective members 40 have a symmetrical structure. The two protective members 40 are disposed so as to face each side surface of the fuel tank 6 at positions spaced outward in the left-right direction from each side surface in the left-right direction. Specifically, the right protective member 40 is disposed so as to face the right side surface 6a of the fuel tank 6 at a position spaced to the right from the right side surface 6a of the fuel tank 6. The left protective member 40 is disposed so as to face the left side surface 6b of the fuel tank 6 at a position spaced to the left from the left side surface 6b of the fuel tank 6. Each protective member 40 is disposed forward of the rear wheel 1.

[0036] The protective member 40 has a generally U-shaped configuration that opens upward. Specifically, the protective member 40 has a front contact portion 41 that extends in the front-rear direction. The protective member 40 has a front extension portion 42 that extends upward from the front end of the front contact portion 41 and a rear extension portion 43 that extends upward from the rear end of the front contact portion 41.

[0037] The front contact portion 41 has a generally cylindrical shape extending in the front-rear direction. A part of the front contact portion 41 is disposed at a position lower than the fuel tank 6. In this embodiment, the front contact portion 41 is disposed so that the height position of the vertical center thereof and the height position of the lower edge of the fuel tank 6 are substantially the same.

[0038] The front extension portion 42 and the rear extension portion 43 each have a generally cylindrical shape extending in the vertical direction. The front extension portion 42 and the rear extension portion 43 extend from the front-rear end portion of the front contact portion 41 to near the center of the fuel tank 6.

[0039] In each protective member 40, the front contact portion 41 and the two extension portions 42, 43 are formed integrally with each other. In this embodiment, the front contact portion 41 and the two extension portions 42, 43 are formed by bending a round pipe, i.e., a cylindrical member. Specifically, the round pipe is bent at two points in its axial direction, so that the front contact portion 41 is formed in the middle of the round pipe, and the front extension portion 42 and the rear extension portion 43 are formed on both sides of the front contact portion 41. The bending angle of the round pipe is approximately 90 degrees, and each extension portion 42, 43 extends approximately vertically upward from both ends of the front and rear direction of the front contact portion 41. In this embodiment, the round pipe is bent so as to follow a circular arc, and the connection portions of the front contact portion 41 and each extension portion 42, 43 each have a shape following a circular arc that bulges outward. In this embodiment, a seal member 140 is attached to the upper end portion 43A of the rear extension portion 43 to close the opening.

[0040] The vehicle V is provided with a pair of left and right gusset frames 50, 50, a pair of left and right brackets 60, 60, and a pair of left and right front support plates 130, 130. Each protective member 40 is supported by the rear side frame 2 via these. Specifically, the right protective member 40 is supported by the right rear side frame 2 via the right gusset frame 50, the right bracket 60, and the right front support plate 130. The left protective member 40 is supported by the left rear side frame 2 via the left gusset frame 50, the left bracket 60, and the left front support plate 130. The gusset frame 50 corresponds to the "second support member" of the present invention, the bracket 60 corresponds to the "first support member" of the present invention, and the member formed by combining the gusset frame 50 and the bracket 60 corresponds to the "support member" of the present invention.

[0041] The structure and arrangement of the two gusset frames 50, 50, the two brackets 60, 60, and the two front support plates 130, 130 are symmetrical, and in the following, we will explain the structure and arrangement of these on the right side of the vehicle V as a representative example.

[0042] The front support plate 130 is a generally plate-shaped member, and is fixed to the lower surface of the rear side frame 2 by bolts 91 so as to extend along the lower surface of the rear side frame 2. The front extension portion 42 of the protective member 40 is joined to the lower surface of the front support plate 130 by welding or the like with its upper end portion abutting against the lower surface of the front support plate 130, and the front extension portion 42 is supported by the lower surface of the rear side frame 2 via the front support plate 130 and the bolts 91.

[0043] The gusset frame 50 has a gusset bottom wall portion 51 extending substantially horizontally along the front-rear direction. The gusset bottom wall portion 51 is provided over the entire front-rear direction of the gusset frame 50. The gusset frame 50 also has a pair of left and right gusset flanges 52A, 52B extending downward from the left and right edges of the gusset bottom wall portion 51. Specifically, the gusset frame 50 has a gusset outer flange 52A extending downward from the right edge of the gusset bottom wall portion 51, i.e., the outer edge in the vehicle width direction, as a base end, and a gusset inner flange 52B extending downward from the left edge of the gusset bottom wall portion 51, i.e., the inner edge in the vehicle width direction, as a base end. In this embodiment, the gusset bottom wall portion 51 and the gusset flanges 52A, 52B are formed integrally with each other. For example, the gusset bottom wall portion 51 and the gusset flanges 52A, 52B are formed in the gusset frame 50 by bending a single plate-shaped member. The gusset bottom wall portion 51 corresponds to the "second bottom wall portion" of the present invention, and the gusset inner flange 52B corresponds to the "second vertical wall portion" of the present invention.

[0044] The gusset frame 50 is disposed below the rear side frame 2. The gusset frame 50 is disposed so that the front end of the gusset bottom wall portion 51 is located above the rear extension portion 43. That is, the gusset bottom wall portion 51 has a gusset side facing portion 51A located above and facing the upper end portion 43A of the rear extension portion 43. The gusset side facing portion 51A faces the entire upper end portion 43A of the rear extension portion 43 in the up-down direction. The gusset bottom wall portion 51 and the gusset frame 50 extend rearward from a position forward of the upper end portion 43A of the rear extension portion 43. In this embodiment, the gusset bottom wall portion 51 and the gusset frame 50 extend from a position rearward of the center of the protection member 40 to a position rearward of the front end of the rear wheel 1 in the front-rear direction. The gusset side facing portion 51A corresponds to the "second facing portion" of the present invention.

[0045] The rear side frame 2 is provided with a gusset frame fixing portion 2C that bulges downward near the boundary between the rear end portion 2A that curves obliquely upward toward the rear and a portion further forward than the rear end portion 2A. The front end portion of the gusset bottom wall portion 51 is fixed to the lower surface 2F of the gusset frame fixing portion 2C, that is, the lower surface 2F of the rear side frame 2, in a state of being aligned with the lower surface 2F, and the gusset frame 50 is supported by the rear side frame 2. In this embodiment, the front end portions of the gusset bottom wall portion 51 and the gusset frame 50 are fastened to the lower surface 2F of the rear side frame 2 by a bolt 92A and a nut 92B. In the front-rear direction, the bolt 92A fastens a portion of the gusset bottom wall portion 51 forward of the gusset side opposing portion 51A, that is, a portion forward of the upper end portion 43A of the rear extension portion 43 in the front-rear direction, to the lower surface 2F of the rear side frame 2.

[0046] The gusset flanges 52A, 52B extend almost straight downward from both left and right edges of the gusset bottom wall portion 51. The gusset flanges 52A, 52B are provided over almost the entire front-to-rear direction of the gusset bottom wall portion 51 and therefore the gusset frame 50. The height dimension of each of the gusset flanges 52A, 52B is set to be smaller than the dimension of the gusset bottom wall portion 51 in the width direction (left-right direction).

[0047] The bracket 60 has a bracket bottom wall portion 61, a bracket flange 62, and a holder portion 63. In this embodiment, the bracket bottom wall portion 61, the bracket flange 62, and the holder portion 63 are formed integrally with one another. For example, the above-mentioned portions 61, 62, and 63 are formed in the bracket 60 by bending a single plate-like member. The bracket bottom wall portion 61 corresponds to the "bottom wall portion" of the present invention, and the bracket flange 62 corresponds to the "vertical wall portion" of the present invention.

[0048] In the front-to-rear direction, the bracket 60 extends rearward from approximately the same position as the front end of the gusset frame 50. However, the dimension of the bracket 60 in the front-to-rear direction is shorter than the dimension of the gusset frame 50 in the front-to-rear direction, and the rear end position of the bracket 60 is forward of the rear-front position of the gusset frame 50. In this embodiment, the rear end position of the bracket 60 is forward of the center of the gusset frame 50 in the front-to-rear direction.

[0049] The bracket bottom wall 61 has a plate shape extending in the front-rear direction along the lower surface of the gusset bottom wall 51. The bracket bottom wall 61 is provided over the entire front-rear direction of the bracket 60. The bracket 60 is disposed so that the bracket bottom wall 61 is located above the rear extension 43. That is, the bracket 60 has a bracket side facing portion 61A located above and facing the upper end 43A of the rear extension 43. The bracket side facing portion 61A faces the entire upper end 43A of the rear extension 43 in the up-down direction. As described above, the upper end 43A of the rear extension 43 faces the gusset side facing portion 51A, and the gusset side facing portion 51A and the bracket side facing portion 61A face each other in the up-down direction. Also, the gusset side facing portion 51A and the bracket side facing portion 61A face each other over their entirety. The bracket side facing portion 61A corresponds to the "facing portion" of the present invention.

[0050] The bracket bottom wall portion 61 is fixed to the lower surface 2F of the gusset frame fixing portion 2C in a state where it is aligned with the lower surface of the gusset bottom wall portion 51, and the bracket 60 is supported by the rear side frame 2. In this embodiment, the bracket bottom wall portion 61 is fixed to the lower surface 2F of the rear side frame 2 by a bolt 92A and a nut 92B for fastening the gusset bottom wall portion 51 to the lower surface 2F of the rear side frame 2. That is, the gusset bottom wall portion 51 and the bracket bottom wall portion 61, i.e., the gusset frame 50 and the bracket 60, are fastened together to the lower surface 2F of the rear side frame 2 by the bolt 92A and the nut 92B. The bolt 92A and the nut 92B for fastening the gusset frame 50 and the bracket 60 together to the lower surface 2F of the rear side frame 2 correspond to the "fastening member" of the present invention.

[0051] The bracket flange 62 has a generally plate-like shape extending downward from the left edge, i.e., the inner edge in the vehicle width direction, of the bracket bottom wall portion 61. In other words, the bracket flange 62 has a plate-like shape and extends downward from the left edge, i.e., the inner edge in the vehicle width direction, of the bracket bottom wall portion 61 as a base end.

[0052] The bracket flange 62 extends in the vertical direction along the right side surface of the gusset inner flange 52B, i.e., the outer side surface in the vehicle width direction. Both the bracket flange 62 and the gusset inner flange 52B extend downward from a position slightly above the upper end of the rear extension portion 43 in the vertical direction at a position spaced from the rear extension portion 43 to the left, i.e., inward in the vehicle width direction. However, the vertical dimension of the bracket flange 62 is longer than the vertical dimension of the gusset inner flange 52B, and the bracket flange 62 extends downward beyond the gusset inner flange 52B. In this embodiment, the vertical dimension of the gusset inner flange 52B is set to about one-fifth of the vertical dimension of the rear extension portion 43, and the vertical dimension of the bracket flange 62 is set to about one-third of the vertical dimension of the rear extension portion 43.

[0053] The bracket 60 and the gusset frame 50 are joined together. In this embodiment, the bracket flange 62 and the gusset inner flange 52B are welded to each other at a plurality of locations.

[0054] 8 is a schematic side view of the vicinity of the front end of the gusset frame 50 as viewed from the left side, that is, from the inside in the vehicle width direction. In this embodiment, the bracket flange 62 and the gusset inner flange 52B are welded to each other at three welds P1, P2, and P3 aligned in the front-rear direction. Hereinafter, a portion of the gusset bottom wall portion 51 and the bracket bottom wall portion 61 that is fastened to the underside 2F of the rear side frame 2 by the bolt 92A and nut 92B and that overlaps with the bolt 92A in the up-down direction of the gusset bottom wall portion 51 and the bracket bottom wall portion 61 is referred to as a fastening portion Q1.

[0055] In the front-rear direction, the first welded portion P1, which is the frontmost of the three welded portions P1-P2, is located forward of the bolt 92A, that is, forward of the fastening portion Q1. The first welded portion P1 is also located forward of the gusset-side facing portion 51A, the bracket-side facing portion 61A, and the upper end portion 43A of the rear extension portion 43.

[0056] In the front-rear direction, the third welded portion P3, which is the rearmost of the three welded portions P1-P2, is located rearward of the bolt 92A, i.e., rearward of the fastening portion Q1. The third welded portion P3 is also located rearward of the upper end portion 43A of the rear extension portion 43, the gusset side facing portion 51A, and the bracket side facing portion 61A. More specifically, in the front-rear direction, the third welded portion P3 is located rearward of the center positions X1 of the upper end portion 43A of the rear extension portion 43, the gusset side facing portion 51A, and the bracket side facing portion 61A.

[0057] In the front-rear direction, the position of the second welded portion P2 between the first welded portion P1 and the third welded portion P3 is slightly rearward of the bolt 92A, i.e., slightly rearward of the fastening portion Q1. In addition, in the front-rear direction, the position of the second welded portion P2 is set forward of the respective central positions of the upper end portion 43A of the rear extending portion 43, the gusset side facing portion 51A, and the bracket side facing portion 61A, and rearward of the front end positions of the upper end portion 43A of the rear extending portion 43, the gusset side facing portion 51A, and the bracket side facing portion 61A.

[0058] The bracket flange 62 has a first portion 62A extending downward from the left edge of the bracket bottom wall portion 61, i.e., the inner edge in the vehicle width direction, a second portion 62B extending downward from the lower end of the first portion 62A, a third portion 62C extending downward from the lower end of the second portion 62B, and a fourth portion 62D extending downward from the lower end of the third portion 62C. The third portion 62C corresponds to the "curved portion" in this invention, and the fourth portion 62D corresponds to the "extended portion" in this invention.

[0059] The second portion 62B extends substantially along a plane that is inclined diagonally downward to the left, and has a substantially planar shape that is located more inward in the vehicle width direction toward the lower side. On the other hand, the fourth portion 62D extends substantially along a plane that is inclined diagonally downward to the right in a direction symmetrical to the second portion 62B, and has a substantially planar shape that is located more outward in the vehicle width direction toward the lower side. The third portion 62C that connects the second portion 62B and the fourth portion 62D and is disposed at the middle position in the up-down direction of the bracket flange 62 is curved so as to bulge toward the left side, that is, toward the inside in the vehicle width direction.

[0060] With the above-mentioned configuration, the bracket flange 62 has a shape that bulges out toward the left side, that is, toward the inside in the vehicle width direction, as a whole. The first portion 62A is curved from the left edge of the bracket bottom wall portion 61 toward a position diagonally downward and to the left of the left edge of the bracket bottom wall portion 61.

[0061] In addition, with the above-mentioned configuration, the fourth portion 62D, which is a portion of the bracket flange 62 extending from the third portion 62C toward the tip side of the bracket flange 62 and extending downward from the third portion 62C, is located to the right of the third portion 62C, that is, outside in the vehicle width direction. In this embodiment, the bracket flange 62 extends downward from the left edge of the bracket bottom wall portion 61 as described above, and the lower end of the bracket flange 62 is the tip of the bracket flange 62. Thus, the above-mentioned portion of the bracket flange 62 extending from the third portion 62C toward the tip side coincides with the portion of the bracket flange 62 below the third portion 62C.

[0062] In the up-down direction, the third portion 62C is provided at a position lower than the lower end of the gusset inner flange 52B. In the present embodiment, the third portion 62C is provided at a position lower than the center of the bracket flange 62 in the up-down direction.

[0063] The holder portion 63 supports the rear extension portion 43. That is, the rear extension portion 43 is supported by the bracket 60 by the holder portion 63, and is supported by the rear side frame 2 via the bracket 60. The holder portion 63 has a first extension portion 63A extending downward from the rear end portion of the bracket bottom wall portion 61, and a second extension portion 63B extending substantially horizontally from the lower edge of the first extension portion 63A. The first extension portion 63A extends downward from the left side of the rear end portion of the bracket bottom wall portion 61, that is, from the outer portion in the vehicle width direction, and the second extension portion 63B extends from the lower edge of the first extension portion 63A diagonally to the left in front, that is, toward the front side and the outer side in the vehicle width direction. The holder portion 63 including the first extension portion 63A and the second extension portion 63B has a plate shape.

[0064] The holder portion 63 is fastened to a connecting member 160 fixed to the rear extension portion 43 by a bolt 93A and a nut 93B, and supports the rear extension portion 43 via the bolt 93A, the nut 93B and the connecting member 160.

[0065] Specifically, the connecting member 160 has a plate-like first connecting piece 161 extending in the up-down direction along the outer peripheral surface of the rear extension portion 43, and a second connecting piece 162 extending substantially horizontally from the lower edge of the first connecting piece 161. The first connecting piece 161 is disposed along the right part of the outer peripheral surface of the rear extension portion 43, i.e., the outer part in the vehicle width direction, and is joined thereto by welding or the like. The second connecting piece 162 extends from the lower edge of the first connecting piece 161 diagonally leftward toward the rear, i.e., toward the rear and the outer side in the vehicle width direction. The second connecting piece 162 is disposed below and parallel to the second extending portion 63B of the holder portion 63, and the second connecting piece 162 and the second extending portion 63B are fastened together by a bolt 93A and a nut 93B. In the illustrated example, the second connecting piece 162 and the second extending portion 63B are connected in a state of being spaced apart in the up-down direction.

[0066] As described above, by fastening the second connecting piece 162 and the second extending portion 63B together, the rear extending portion 43 is supported by the holder portion 63 and, in turn, the bracket 60. In addition, the rear extending portion 43 is supported by the rear side frame 2 via the bracket 60.

[0067] (action, etc.) As described above, in the undercarriage structure according to the embodiment, the two protective members 40 are supported by the rear side frames 2 on both sides of the fuel tank 6 in the left-right direction, facing both side surfaces 6a, 6b of the fuel tank 6 in the left-right direction. In addition, a part of the leading abutment portion 41 of each protective member 40 is disposed below the fuel tank 6. Therefore, the fuel tank 6 can be protected by the protective member 40. Specifically, when an obstacle collides with the vehicle V from the side in the vehicle width direction, the protective member 40 can prevent contact between the obstacle and the fuel tank 6. In addition, when the vehicle V passes over a step or the like formed on the road surface, the leading abutment portion 41 contacts the step or the like to keep the step or the like and the fuel tank 6 apart, thereby preventing contact between the step or the like and the fuel tank 6.

[0068] In the above embodiment, the gusset frame 50 and the bracket 60 are disposed between the upper end 43A of the rear extension 43 of the protective member 40 and the rear side frame 2, and the gusset frame 50 and the bracket 60 are provided with a gusset-side opposing portion 51A and a bracket-side opposing portion 61A that face the upper end 43A of the rear extension 43. This makes it possible to prevent a collision load from being directly applied from the rear extension 43 to the rear side frame 2, thereby suppressing deformation of the rear side frame 2. In other words, the portion of the rear side frame 2 to which the collision load is transmitted from the protective member 40 is reinforced by the gusset frame 50 and the bracket 60, thereby suppressing deformation of the rear side frame 2.

[0069] In particular, in the above embodiment, in addition to the bracket bottom wall portion 61 extending along the underside of the rear side frame 2, the bracket 60 is provided with a bracket flange 62 extending downward from the inner edge of the bracket bottom wall portion 61 in the vehicle width direction as a base end, thereby increasing the rigidity of the bracket 60. Therefore, deformation of the bracket 60, and therefore deformation of the rear side frame 2, can be suppressed.

[0070] Moreover, in the above embodiment, the bracket flange 62 is provided with the third portion 62C that is curved so as to bulge inward in the vehicle width direction, and the fourth portion 62D that extends from the third portion 62C to the tip side is disposed further outward in the vehicle width direction than the third portion 62C. Therefore, the fuel tank 6 can be protected more reliably.

[0071] A specific description will be given with reference to FIG. 9. FIG. 9 is a cross-sectional view corresponding to FIG. 6. When an obstacle collides with the vehicle V from the side in the vehicle width direction and the collision load is large, the rear side frame 2 is displaced from the state shown by the solid line in FIG. 9 to the state shown by the chain line. That is, the rear side frame 2 is deformed so that its lower end portion faces inward in the vehicle width direction. When the rear side frame 2 is deformed inward in the vehicle width direction, the protective member 40, the gusset frame 50, and the bracket 60 supported by the rear side frame 2 also swing inward in the vehicle width direction from their upper positions as shown by the chain line in FIG. 9. Accordingly, the bracket flange 62 is displaced toward the fuel tank 6. Therefore, when the collision load is particularly large, the bracket flange 62 may come into contact with the fuel tank 6. Here, if a sharp portion at the tip of the bracket flange 62 comes into contact with the fuel tank 6 with force first, the fuel tank 6 may be damaged by the tip. In contrast, in the above embodiment, the bracket flange 62 is provided with the third portion 62C that curves to bulge toward the inside in the vehicle width direction, and the fourth portion 62D that extends from the third portion 62C to the tip side is disposed outside the third portion 62C in the vehicle width direction. Therefore, the third portion 62C that curves to bulge toward the inside in the vehicle width direction, i.e., toward the fuel tank 6 as described above, rather than the sharp tip of the bracket flange 62, can be brought into contact with the fuel tank 6 first. Thus, according to the above embodiment, it is possible to prevent the sharp tip from coming into contact with the fuel tank 6 with force, and further rocking of the bracket 60 is suppressed by the contact between the third portion 62C and the fuel tank 6, thereby preventing the sharp tip of the bracket flange 62 from coming into contact with the fuel tank 6.

[0072] In the above embodiment, the fourth portion 62D, which is a portion of the bracket flange 62 extending from the third portion 62C toward the tip side, extends downward from the third portion 62C. Therefore, the shape of the bracket flange 62 can be simplified compared to a case in which the portion extending from the third portion 62C toward the tip side is formed to extend upward from the lower end of the third portion 62C.

[0073] In the above embodiment, the gusset frame 50 is provided with the gusset outer flange 52A and the gusset inner flange 52B, which extend downward from both left and right edges, i.e., both edges in the vehicle width direction, as base ends, thereby increasing the rigidity of the gusset frame 50 in addition to the bracket 60. Therefore, deformation of the rear side frame 2 can be more reliably suppressed.

[0074] In the above embodiment, the third portion 62C is disposed below the lower end of the gusset inner flange 52B. Therefore, the gusset frame 50 is provided with the gusset inner flange 52B to increase the rigidity of the gusset frame 50, while the third portion 62C can come into contact with the fuel tank 6 before the sharp lower end of the gusset inner flange 52B. This makes it possible to prevent the fuel tank 6 from being damaged by contact with the sharp lower end of the gusset inner flange 52B.

[0075] In the above embodiment, the bracket 60 and the gusset frame 50 are fastened to the rear side frame 2 by the common bolt 92A and nut 92B. Therefore, the configuration can be simplified compared to the case where they are fastened to the rear side frame 2 individually. Furthermore, in the above embodiment, the bracket 60 and the gusset frame 50 are joined to each other at the first welded portion P1 and the second welded portion P2, which are forward of the fastening portion Q1 fastened by the bolt 92A and the nut 92B, and at the third welded portion P3, which is rear of the fastening portion Q1. Therefore, the bracket 60 and the gusset frame 50 are integrated and can be supported by the rear side frame 2 more stably. In addition, the rigidity of the bracket 60 and the gusset frame 50 can be mutually increased, and deformation of the rear side frame 2 can be further suppressed.

[0076] In the above embodiment, the fastening portion Q1 is located forward of the upper end portion 43A of the rear extension portion 43, the gusset side facing portion 51A, and the bracket side facing portion 61A, and the third welded portion P3 is located rearward of the center positions X1 of the upper end portion 43A of the rear extension portion 43, the gusset side facing portion 51A, and the bracket side facing portion 61A. Therefore, the gusset side facing portion 51A and the bracket side facing portion 61A can be integrated to increase their rigidity. Therefore, the load applied from the upper end portion 43A of the rear extension portion 43 to the gusset side facing portion 51A and the bracket side facing portion 61A can be stably received by the gusset frame 50 and the bracket 60, and deformation of these and thus deformation of the rear side frame 2 can be suppressed.

[0077] (Modification) In the above embodiment, the case where the gusset frame 50 and the bracket 60 are disposed between the rear extension portion 43 and the rear side frame 2 has been described, but only one of them may be disposed between the rear extension portion 43 and the rear side frame 2. In addition, the gusset frame 50 and the bracket 60 may be integrally formed with each other, so that one member is disposed between the rear extension portion 43 and the rear side frame 2.

[0078] 10, the gusset frame may be disposed below the bracket 60. Specifically, instead of the gusset frame 50 according to the above embodiment, a gusset frame 150 (second support member) including a gusset bottom wall portion 151 (second bottom wall portion) that extends along the bracket bottom wall portion 61 below the bracket bottom wall portion 61 and includes a gusset side opposing portion 151A (second opposing portion) that faces the bracket side opposing portion 61A in the up-down direction may be fixed to the rear side frame 2. FIG. 10 is a schematic cross-sectional view corresponding to FIG. 7. Other configurations of the gusset frame 150 according to the example of FIG. 10 are generally the same as those according to the above embodiment. In detail, the gusset frame 150 according to the example of FIG. 10 has a gusset inner flange 152B (second vertical wall portion) that extends downward from the inner edge of the gusset bottom wall portion 151 in the vehicle width direction to a position above the third portion 62C, and a gusset outer flange 52A that extends downward from the outer edge of the gusset bottom wall portion 51 in the vehicle width direction as a base end. The bracket 60 and the gusset frame 150 are fastened together to the lower surface 2F of the rear side frame 2 by bolts 92A and nuts 92B. In the configuration shown in FIG. 10, the bracket flange 62 and the gusset inner flange 152B are preferably welded to each other in the same manner as in the above embodiment, that is, at a plurality of positions shown in FIG. 8.

[0079] In the above embodiment, a third portion D3 that curves so as to bulge inward in the vehicle width direction is provided at the middle position of the bracket 60 in the vertical direction, but the third portion D3 may also be provided at the lower end of the bracket 60.

[0080] In the above embodiment, the fourth portion D4 extends downward from the lower end of the third portion D3, but the fourth portion D4 may be formed to extend inward and upward in the vehicle width direction from the third portion D3.

[0081] In the above embodiment, a case was described in which a gusset frame 50 and a bracket 60 were arranged between the rear extension portion 43 and the rear side frame 2, but a gusset frame 50 and a bracket 60 may also be arranged between the front extension portion 42 and the rear side frame 2.

[0082] In the above embodiment, the gusset frame 50 and the bracket 60 are fastened together and joined by the bolt 92A and the nut 92B, but the configuration for connecting the gusset frame 50 and the bracket 60 is not limited to this. In addition, the specific positions and number of the joined parts are not limited to the above.

[0083] In the above embodiment, the on-vehicle member protected by the protective member 40 is the fuel tank 6. However, the on-vehicle member may be a member other than the fuel tank 6.

[0084] In the above embodiment, the case has been described in which the tip contact portion 41 and the extending portions 42, 43 are integrally formed from a round pipe, but these may be formed separately and then joined to each other by welding or the like.

[0085] In the above embodiment, the angle between the tip portion 41 and each of the extending portions 42, 43 is approximately 90 degrees, but the angle is not limited to this.

[0086] Furthermore, the vehicle body members that support the extensions 42, 43 and the protective member 40 are not limited to the rear side frame 2 and the gusset frame 50. Furthermore, the positional relationship between the rear wheel 1 and the protective member 40 is not limited to the above. [Explanation of symbols]

[0087] 2 Rear side frame (frame member) 4 Floor Panel 6 Fuel tank (vehicle component) 40 Protective materials 42 Rear extension part 50 Gusset frame (second support member, support member) 51 Gusset bottom wall portion (second bottom wall portion) 51A Gusset side opposing part (second opposing part) 52B Gusset inner flange (second vertical wall) 60 bracket (first support member, support member) 61 Bracket bottom wall (bottom wall) 61A Bracket side facing part (facing part) 62 Bracket flange (vertical wall part) 62C 3rd section (curved section) 92A Bolt (fastening member) 92B Nut (fastening member) Q1 Fastening part

Claims

1. An in-vehicle member disposed below a floor panel of the vehicle; A frame member disposed on an outer side of the on-board member in a vehicle width direction; a protection member disposed below the frame member so as to face the on-board member from the outer side in the vehicle width direction; a support member fixed to a lower surface of the frame member and supporting the protection member, the support member has a bottom wall portion including an opposing portion that faces an upper end portion of the protective member in the up-down direction and extends along a lower surface of the frame member, and a vertical wall portion that extends downward from an inner edge of the bottom wall portion in the vehicle width direction as a base end, the vertical wall portion having a curved portion that curves so as to bulge inward in a vehicle width direction, and an extension portion that extends from the curved portion toward a tip side and is positioned outward in the vehicle width direction than the curved portion.

2. The vehicle underbody structure according to claim 1, the support member includes a first support member including the bottom wall portion and the vertical wall portion, and a second support member formed separately from the first support member and fixed to a lower surface of the frame member, A vehicle understructure characterized in that the second support member has a second bottom wall portion extending along the bottom wall portion below the bottom wall portion or between the bottom wall portion and the frame member, and including a second opposing portion that faces the opposing portion in the vertical direction.

3. The vehicle underbody structure according to claim 2, The second support member has a second vertical wall portion extending downward from an inner edge of the second bottom wall portion in a vehicle width direction.

4. The vehicle underbody structure according to claim 3, A vehicle underbody structure, characterized in that a lower end of the second vertical wall portion is located above the curved portion.

5. The vehicle underbody structure according to claim 2, A vehicle understructure, characterized in that the first support member and the second support member are fastened to the frame member by a common fastening member and joined to each other at positions forward and rearward of the fastening member in the fore-and-aft direction of the vehicle.

6. The vehicle underbody structure according to claim 5, a first support member and a second support member fastened to the frame member by the fastening member at a position forward of the opposing portion in the fore-and-aft direction of the vehicle, and joined to each other at a position rearward of the center of the opposing portion in the fore-and-aft direction of the vehicle.

7. The vehicle underbody structure according to any one of claims 1 to 6, The vehicle undercarriage, wherein the extension portion extends downward from the curved portion.

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