Vehicle body lower part structure

Abstract

To reduce influence of an input load on a joined state of fixing parts when a seat belt anchor fixing part and a seat rear fixing part are located close to each other.SOLUTION: In a vehicle body lower part structure 1, a seat belt anchor fixing part 1C is located around a seat rear fixing part 1A reinforced by a seat bracket 20. The vehicle body lower part structure 1 includes an anchor reinforcement 30 which extends in a front-back direction in front of the seat rear fixing part 1A, has the seat belt anchor fixing part 1C, and is joined to an upper surface of a floor panel 10. The anchor reinforcement 30 has: an anchor reinforcement main part 30A having the seat belt anchor fixing part 1C; and a rear extension part 30B which extends rearward from a part of a rear end of the anchor reinforcement main part 30A and is located between the seat belt anchor fixing part 1C and the seat rear fixing part 1A in the vehicle front-back direction and joined to the floor panel 10 and the seat bracket 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A seat belt anchor fixing portion to which a seat belt anchor that supports a seat belt is fixed and a seat rear fixing portion to which a rear portion of the seat, such as a rear portion of a slide rail, is fixed are provided near the seat in the lower part of the vehicle body. A load that pulls each fixing portion forward and diagonally upward may act on each of the seat belt anchor fixing portion and the seat rear fixing portion. For this reason, in order to reinforce each fixing portion, a reinforcing member such as a reinforcement (also called a retainer) is often joined to each fixing portion by spot welding.

[0003] One example of a vehicle underbody structure having a reinforced seatbelt anchor fixing portion and a seat rear fixing portion is disclosed in Patent Document 1. In the structure disclosed in Patent Document 1, a seatbelt anchor retainer is welded to the underside of a floor panel at a location corresponding to the seatbelt anchor fixing portion, and the seatbelt anchor is fastened together with the floor panel by a bolt at the longitudinal center of the retainer. A hat-shaped cross member is welded to the underside of the floor panel at a location corresponding to the seat rear fixing portion, and the rear end of the slide rail can be fastened by a bolt to the closed cross-section formed by the cross member and the floor panel. In the structure disclosed in Patent Document 1, the retainer has a pair of stiffening members extending in the front-rear direction, sandwiching the fastening point to the floor panel by the bolt. The rear end of the retainer is welded to the underside of a flange of the cross member welded to the underside of the floor panel. The retainer is further welded to the underside of the floor panel in a region between the welding point to the cross member flange and the rear end of the stiffening member.

[0004] The structure disclosed in Patent Document 1 has the above configuration, and is intended to prevent separation of the spot weld between the rear end of the retainer and the flange of the cross member when a load is applied to the floor panel upward in the vehicle body, causing the fastening point of the retainer to the floor panel (in other words, the seat belt anchor fixing portion) to move upward and deform, causing the rear end of the rigidity reinforcement portion to lift the floor panel upward.In the structure disclosed in Patent Document 1, the seat belt anchor fixing portion (the fastening point of the retainer to the floor panel) is provided in the longitudinal center of the retainer, and the seat belt anchor fixing portion and the seat rear fixing portion (the fastening point of the rear end of the slide rail to the closed cross-sectional portion) are sufficiently separated from each other. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-218519 Summary of the Invention [Problem to be solved by the invention]

[0006] In some cases, the seat belt anchor fixing portion is disposed in front of and around the seat rear fixing portion in the lower part of the vehicle body, and the seat belt anchor fixing portion and the seat rear fixing portion, which are load input points, are disposed close to each other. In such cases, in order to suppress deformation of the floor panel or the like due to the input load, it is conceivable to increase rigidity by welding reinforcing members such as retainers and cross members to the seat belt anchor fixing portion and the seat rear fixing portion, as in Patent Document 1. However, in a layout in which the seat belt anchor fixing portion and the seat rear fixing portion are disposed close to each other, the rigidity of each fixing portion is increased by the reinforcing members, which may cause stress to concentrate around each fixing portion (seat belt anchor fixing portion, seat rear fixing portion), resulting in greater than expected deformation of the floor panel or the like and possibly affecting the joining condition of the fixing portions.

[0007] Therefore, the present invention aims to provide a vehicle lower body structure having a structure that can reduce the effect of the input load on the joining state of the fixing parts, even if the seat belt anchor fixing part and the seat rear fixing part are arranged close to each other. [Means for solving the problem]

[0008] In order to achieve the above object, according to one aspect of the present invention, there is provided a vehicle underbody structure including a floor panel disposed under a vehicle body and having a seat rear-side fixing portion, and a seat bracket reinforcing the seat rear-side fixing portion, wherein a seat belt anchor fixing portion is disposed in the underbody forward of the seat rear-side fixing portion and around the seat rear-side fixing portion. The vehicle underbody structure includes an anchor force extending in the fore-and-aft direction of the vehicle forward of the seat rear-side fixing portion and having the seat belt anchor fixing portion, and joined to an upper surface of the floor panel, the seat belt anchor fixing portion being provided at a rear portion of the anchor force, the anchor force having the seat belt anchor fixing portion and a thin plate-shaped rear extension portion extending rearward from a portion of the rear end of the anchor force body, the rear extension portion being located between the seat belt anchor fixing portion and the seat rear-side fixing portion in the fore-and-aft direction of the vehicle and joined to the floor panel and the seat bracket. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to provide a vehicle lower body structure having a structure that can reduce the effect of input load on the joining state of the fixing parts, even if the seat belt anchor fixing part and the seat rear fixing part are arranged close to each other. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a vehicle underbody structure according to an embodiment of the present invention; [Figure 2] FIG. [Figure 3]FIG. 2 is an enlarged top view of a main part of the vehicle body underbody structure. [Figure 4] FIG. 2 is a perspective view of a main part of the vehicle body underbody structure. [Figure 5] FIG. 2 is a perspective view of a portion of the vehicle body understructure including a seat bracket, as viewed from below. [Figure 6] FIG. 4 is a cross-sectional view taken along line AA shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a perspective view of a vehicle underbody structure 1 according to one embodiment of the present invention, Fig. 2 is a partial bottom view of the vehicle underbody structure 1, Figs. 3 and 4 are views showing essential parts of the vehicle underbody structure 1, Fig. 3 is an enlarged top view, and Fig. 4 is a perspective view. In the drawings, the arrow Fr direction indicates the front in the vehicle longitudinal direction, the arrow O direction indicates the outside of the vehicle in the vehicle width direction, and the arrow U direction indicates the up in the vehicle vertical direction. In the following description, "front" and "rear" correspond to the front and rear in the vehicle longitudinal direction, "up" and "down" correspond to the up and down in the vehicle vertical direction, and "left" and "right" correspond to the left and right in the vehicle width direction when a vehicle occupant is facing forward of the vehicle. In Fig. 3, a seat main body S1 (described later) has been removed, and a fixed rail S2a of a seat rail S2 (described later) is shown by a two-dot chain line. In Fig. 4, a seat S and a seat belt anchor S3 (described later) have been removed.

[0012] (Outline of the underbody structure) 1 to 4, the vehicle underbody structure 1 includes a floor panel 10, a seat bracket 20, an anchoring force 30, a rear reinforcement force 40, a rear side member 50, a side sill 60, a cross member 70, and a brace 80. The vehicle underbody structure 1 of this embodiment is applied to the structure of the underbody of an electric vehicle powered by a power supply unit.

[0013] The floor panel 10 is a panel member disposed under the vehicle body and constituting the floor portion of the vehicle body, and is made of a metal plate material. The floor panel 10 is a plate-shaped member extending from the lower front portion of the vehicle compartment to the rear portion of the vehicle body. The widthwise dimension of the floor panel 10 corresponds approximately to the widthwise dimension of the vehicle body. The floor panel 10 has a main floor panel 10A and a rear floor panel 10B that has a width shorter than the widthwise width of the main floor panel 10A and extends rearward from the rear edge of the main floor panel 10A. In the illustrated example, the front edge of the rear floor panel 10B is joined to the upper surface of the rear edge of the main floor panel 10A.

[0014] A seat S is arranged on the floor panel 10. In this embodiment, the seat S is arranged on the main floor panel 10A. The seat S has a seat body S1 on which an occupant sits and a seat rail S2 that supports the seat body S1 from below. The seat rail S2 extends in the front-to-rear direction of the vehicle between the seat body S1 and the floor panel 10 and is a member that supports the seat body S1 from below so that the seat body S1 can slide in the front-to-rear direction of the vehicle. The seat rail S2 has a fixed rail S2a fixed to the vehicle body side and a movable rail S2b fixed to the bottom of the seat body S1 and attached to the fixed rail S2a so as to be slidable along the fixed rail S2a.

[0015] In the illustrated example, the rear end of the seat rail S2 protrudes rearward relative to the rear of the seat body S1, and the front end of the seat rail S2 is generally located below the front of the seat body S1.

[0016] 1, 3 and 4, the vehicle body understructure 1 is provided at its lower part with a seat rear fixing portion 1A to which the rear end of the fixed rail S2a of the seat rail S2 is fixed, a seat front fixing portion 1B to which the front end of the fixed rail S2a of the seat rail S2 is fixed, and a seat belt anchor fixing portion 1C to which a seat belt anchor S3 is fixed that supports a seat belt (not shown) that protects an occupant seated in the seat S.

[0017] The seat rear fixing portion 1A is provided on the floor panel 10 (main floor panel 10A), and the seat front fixing portion 1B and the seat belt anchor fixing portion 1C are provided on the anchoring force 30. Therefore, the floor panel 10 (main floor panel 10A) has the seat rear fixing portion 1A, and the anchoring force 30 has the seat front fixing portion 1B and the seat belt anchor fixing portion 1C. In other words, the seat rear fixing portion 1A is a fixing portion on the floor panel 10 to which the rear of the seat S is fixed, the seat front fixing portion 1B is a fixing portion on the lower part of the vehicle body (anchor force 30) to which the rear of the seat S is fixed, and the seat belt anchor fixing portion 1C is a fixing portion on the lower part of the vehicle body (anchor force 30) to which the seat belt anchor S3 is fixed.

[0018] The seat bracket 20 is a reinforcing member that reinforces the seat rear fixing portion 1A of the floor panel 10. The seat bracket 20 is joined to the floor panel 10. The seat bracket 20 is formed by performing processing such as press forming on a metal plate material. The seat bracket 20 is joined to the floor panel 10 from the outside of the vehicle compartment by spot welding. In other words, the seat bracket 20 is joined to the underside of the seat rear fixing portion 1A of the floor panel 10. The shape of the seat bracket 20 will be described in detail later.

[0019] The anchoring force 30 is a member that extends in the longitudinal direction of the vehicle in front of the seat rear fixing portion 1A and has a seat belt anchor fixing portion 1C. The anchoring force 30 is formed by processing a metal plate material such as press molding. The anchoring force 30 is formed with high rigidity and reinforces the seat belt anchor fixing portion 1C in the lower part of the vehicle body.

[0020] The anchoring force 30 is disposed on the interior side of the vehicle with respect to the floor panel 10, and is joined to the floor panel 10 (main floor panel 10A) by being spot welded to the upper surface of the floor panel 10.

[0021] 3 and 4, the floor panel 10 (main floor panel 10A) is formed so that, in a vertical view of the vehicle, the portion corresponding to the seat rear fixing portion 1A gradually widens outward in the vehicle width direction toward the front of the vehicle, and then bulges outward in the vehicle width direction significantly in the portion beyond the seat belt anchor fixing portion 1C. The anchoring force 30 has an outer shape that matches the shape of the outer side of the floor panel 10 in the vertical view of the vehicle, is disposed so as to overlap the upper surface of the floor panel 10, and extends in the front-to-rear direction of the vehicle. In other words, the anchoring force 30 is formed so that, in a vertical view of the vehicle, the portion corresponding to the seat belt anchor fixing portion 1C gradually widens outward in the vehicle width direction toward the front of the vehicle, and then bulges outward in the vehicle width direction significantly in the portion beyond the seat belt anchor fixing portion 1C. The inner edge of the anchoring force 30 in the vertical direction extends slightly diagonally so as to move away from the center of the vehicle width direction of the vehicle body as it moves toward the front of the vehicle.

[0022] The seat rear fixing portion 1A is set near the rear of the seat S on the floor panel 10 and near the outer edge of the floor panel 10 in the vehicle width direction. In relation to the anchoring force 30, the seat rear fixing portion 1A is adjacent to the rear end of the anchoring force 30 and rearward of the rear end of the anchoring force 30. In the illustrated example, the rear end of the fixing rail S2a is fastened to the seat rear fixing portion 1A using a rail fastening bolt B, thereby attaching and fixing the rear of the seat S to the floor panel 10.

[0023] The seat front fixing portion 1B is provided in the front part of the anchoring force 30. Specifically, the seat front fixing portion 1B is provided in the vehicle width direction inner portion of the front part of the anchoring force 30. In the illustrated example, a fixed rail front end support S4 is attached to the seat front fixing portion 1B by a fastener such as a bolt not shown, and the front end of the fixed rail S2a is fastened to the upper wall of the fixed rail front end support S4 using bolt B, thereby attaching and fixing the front part of the seat S to the front part of the anchoring force 30 via the fixed rail front end support S4.

[0024] The seat belt anchor fixing portion 1C is provided at the rear of the anchoring force 30. Specifically, the seat belt anchor fixing portion 1C is provided at a portion of the rear of the anchoring force 30 that is on the outer side in the vehicle width direction. In this way, the seat belt anchor fixing portion 1C is arranged in the lower part of the vehicle body, forward of the seat rear fixing portion 1A and around the seat rear fixing portion 1A. In the illustrated example, the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A are arranged close to each other. Furthermore, when viewed from above the vehicle, the seat belt anchor fixing portion 1C is provided at a position close to the seat rear fixing portion 1A and between the seat rear fixing portion 1A and the seat front fixing portion 1B in the fore-and-aft direction of the vehicle. In the illustrated example, the seat belt anchor S3 is attached and fixed to the anchoring force 30 by fastening the seat belt anchor fixing portion 1C using an anchor fastening bolt B.

[0025] The rear reinforcement 40 extends in the longitudinal direction of the vehicle rearward of the seat rear fixing portion 1A. The rear reinforcement 40 is made of a metal plate material that extends along the outer edge of the floor panel 10 in the vehicle width direction. The floor panel 10 is formed so that a portion rearward of the seat rear fixing portion 1A is cut out inward in the vehicle width direction by an amount that roughly corresponds to the seat rear fixing portion 1A. The rear reinforcement 40 extends along the upper surface of the outer edge of the vehicle width direction of the portion of the floor panel 10 rearward of the seat rear fixing portion 1A (i.e., the rear floor panel 10B in the illustrated example), and is joined to the floor panel 10 by spot welding.

[0026] The rear reinforcement 40 has a reinforcement main body 41 extending in the fore-and-aft direction of the vehicle, a reinforcement inner flange 42 extending along the inner edge of the reinforcement main body 41 in the vehicle width direction, and a reinforcement vertical wall 43 extending upward from the outer edge of the reinforcement main body 41 in the vehicle width direction.

[0027] The front edge of the reinforcement main body 41 is joined by spot welding to the upper surface of the vehicle width direction outer portion of the rear edge of the main floor panel 10A of the floor panel 10. The reinforcement inner flange 42 is joined by spot welding to the upper surface of the vehicle width direction outer edge of the rear floor panel 10B of the floor panel 10. In the illustrated example, the vehicle width direction outer edge of the rear floor panel 10B is sandwiched between the reinforcement inner flange 42 and a side member inner flange 53 (described later) of the rear side member 50, and the vehicle width direction outer edge of the rear floor panel 10B, the reinforcement inner flange 42, and the side member inner flange 53 are welded in a triple layer. The reinforcement vertical wall 43 is joined by spot welding to the upper part of the inner surface of a side member outer wall 54 (described later) of the rear side member 50.

[0028] The rear side member 50 is a member that extends in the fore-and-aft direction of the vehicle along the rear reinforcement 40 below the rear reinforcement 40. The rear side member 50 is formed by processing a metal plate material such as by press forming. The rear side member 50 is a member that extends along the outer edge of the floor panel 10 in the vehicle width direction at the rear of the side of the vehicle body, and constitutes part of the vehicle body structural member.

[0029] In the front portion of the vehicle body understructure 1 outside the illustrated range, front side members extending forward of the vehicle are provided on both sides in the vehicle width direction, but the rear side members 50 are not formed to be continuous with these front side members. In the vehicle body understructure 1, the side members are not continuous from the front to the rear of the vehicle body, which can reduce the impact performance of the side members, so the anchoring force 30 also serves as a member to compensate for the reduction in impact performance due to the discontinuity of the side members. In other words, the anchoring force 30 not only functions to reinforce the portion of the vehicle underbody where the seat belt anchor S3 is fixed, but also functions as a vehicle body structural member to satisfy impact performance.

[0030] The rear side member 50 has a rear side member main body portion 50A that fits along the rear reinforcement 40, and a protruding portion 50B that protrudes forward of the vehicle from the front end of the rear reinforcement 40 so as to cover the seat bracket 20 from below. In other words, when divided in the vehicle longitudinal direction, the rear side member 50 is made up of the rear side member main body portion 50A and the protruding portion 50B. In the illustrated example, the protruding portion 50B protrudes forward to a position that exceeds the lower position of the seat belt anchor S3 (seat belt anchor fixing portion 1C).

[0031] The rear side member 50 has a side member bottom wall 51 located below the rear reinforcement 40, a side member inner wall 52 extending upward from the inner end of the side member bottom wall 51 in the vehicle width direction, a side member inner flange 53 extending inward in the vehicle width direction from the upper end of the side member inner wall 52, and a side member outer wall 54 extending upward from the outer end of the side member bottom wall 51 in the vehicle width direction.

[0032] In the illustrated example, the side member outer wall 54 of the rear side member 50 extends so as to follow the outer surface of the reinforcement vertical wall 43 of the rear reinforcement 40, the outer surface of a bracket vertical wall 24 (described later) of the seat bracket 20, the outer surface of a panel outer wall 15 (described later) of the main floor panel 10A, and the outer surface of an anchoring force vertical wall 35 (described later) of the anchoring force 30. The side member outer wall 54 is joined to the reinforcement vertical wall 43, the bracket vertical wall 24, the panel outer wall 15, and the anchoring force vertical wall 35 by spot welding.

[0033] The side sill 60 extends in the fore-and-aft direction of the vehicle along the outer edge of the main floor panel 10A in the vehicle width direction and the outer edge of the anchoring force 30 in the vehicle width direction, and is joined to the main floor panel 10A and the anchoring force 30 by spot welding. The side sill 60 is formed by processing a metal plate material, such as press forming. A side sill vertical wall 61 on the outer side of the side sill 60 in the vehicle width direction is joined to the outer surface of the rear end of the side member outer wall 54 of the protruding portion 50B of the rear side member 50 by spot welding.

[0034] The cross member 70 is located below the floor panel 10 and extends in the vehicle width direction at a position corresponding to the seat belt anchor fixing portion 1C in the vehicle longitudinal direction. The cross member 70 is a member that constitutes part of the vehicle body structural member that is along the underside of the main floor panel 10A, and extends in the vehicle width direction so as to bridge the left and right rear side members 50. The cross member 70 is formed into a hat-shaped cross section by processing a metal plate material using press forming or the like. In the illustrated example, the cross member 70 is formed in sections in the vehicle width direction, but this is not limited to this, and it may also be formed as a single unit across the entire vehicle width direction.

[0035] The cross member 70 is joined to the underside of the main floor panel 10A by spot welding. The rear portion of the side sill 60 is joined to the vehicle width direction end of the cross member 70 from the outside of the vehicle width direction by spot welding. In other words, the cross member 70 has an end portion joined to the side sill 60. The front portion of the rear side member 50 is formed to cover the vehicle width direction end of the cross member 70 from below and behind, and is joined to the cross member 70 by spot welding. The vehicle width direction end of the cross member 70 and the main floor panel 10A are sandwiched between the rear portion of the anchoring force 30 and the front portion of the rear side member 50. Therefore, the rear portion of the anchoring force 30 and the front portion of the rear side member 50 are connected via the main floor panel 10A and the cross member 70.

[0036] The brace 80 extends forward from the front of the rear side member 50. The brace 80 is formed to partially cover the front of the rear side member 50, the rear of the side sill 60, and the end of the cross member 70 in the vehicle width direction from below the vehicle, and is joined to the floor panel 10, the rear side member 50, the side sill 60, and the cross member 70 by spot welding.

[0037] The brace 80 has a brace main body 81 that bulges downward in the vehicle, a brace inner flange 82 that extends inward in the vehicle width direction from the inner edge of the brace main body 81 in the vehicle width direction, a brace outer flange 83 that extends outward in the vehicle width direction from the outer edge of the brace main body 81 in the vehicle width direction, and a brace rear flange 84 that extends rearward from the rear edge of the brace main body 81.

[0038] The brace inner flange 82 is joined to the main floor panel 10A and the cross member 70, the brace outer flange 83 is joined to the rear of the side sill 60, and the brace rear flange 84 is joined to the front of the side member bottom wall 51 of the rear side member 50 and the cross member 70.

[0039] (Detailed structure of the underbody) Next, the detailed structure of the main parts of the vehicle body understructure 1 will be described with reference to Figures 1 to 6. Figure 5 is a perspective view of a portion of the vehicle body understructure 1 including the seat bracket 20, as viewed from below, and Figure 6 is a cross-sectional view taken along line AA shown in Figure 3. In Figure 5, the rear side members 50, side sills 60, cross members 70, and braces 80 are omitted from the illustration.

[0040] Referring to Figures 5 and 6, the seat bracket 20 is joined to the floor panel 10 and is also joined to the rear of the anchoring force 30 and the front of the rear reinforcement 40 so as to bridge the gap between the anchoring force 30 and the rear reinforcement 40.

[0041] Specifically, the front edge of the seat bracket 20 overlaps the underside of the main floor panel 10A in front of and near the seat rear fixing portion 1A, and the rear edge of the anchoring force 30 (rear extension portion 30B described below) overlaps the upper surface of the main floor panel 10A at a position corresponding to the front edge of the seat bracket 20, and the front edge of the seat bracket 20, the rear edge of the anchoring force 30, and the main floor panel 10A are joined in a three-layer configuration by spot welding. The rear edge of the seat bracket 20 overlaps the underside of the rear edge of the main floor panel 10A, and the front edge of the reinforcement body 41 of the rear reinforcement 40 overlaps the upper surface of the rear edge of the main floor panel 10A, and the rear edge of the seat bracket 20, the front edge of the reinforcement body 41, and the rear edge of the main floor panel 10A are joined in a three-layer configuration by spot welding.

[0042] In the vehicle body lower structure 1, the metal plate material used for the anchoring force 30 and the rear reinforcement 40 is a high-tensile steel plate, and the metal plate material used for the seat bracket 20 is an ordinary steel plate having a tensile strength lower than that of the high-tensile steel plate. For example, the rear side member 50, the side sill 60, the cross member 70, and the brace 80 are each made of a high-tensile steel plate like the anchoring force 30 and the rear reinforcement 40, and the floor panel 10 is made of an ordinary steel plate like the seat bracket 20.

[0043] In this embodiment, the main floor panel 10A of the floor panel 10 has an inclined portion 11 that slopes downward toward the front of the vehicle in front of the seat rear fixing portion 1A, and a front floor portion 12 that extends in the longitudinal direction of the vehicle in front of the inclined portion 11. The seat rear fixing portion 1A of the main floor panel 10A is formed as a horizontally extending wall. The seat rear fixing portion 1A has a bolt insertion hole 13 through which a bolt B for fastening the seat is inserted. In the illustrated example, the main floor panel 10A of the floor panel 10 has a bead portion 14 that extends to surround the seat rear fixing portion 1A. The bead portion 14 bulges out toward the upper side of the vehicle. When viewed from above the vehicle, the bead portion 14 extends in a groove shape (U-shape) that is open toward the front, and surrounds the seat rear fixing portion 1A (in other words, the rear end of the fixing rail S2a) from the rear. In the illustrated example, the main floor panel 10A has a panel outer wall 15 that extends upward in the vehicle in a range corresponding to the seat rear fixing portion 1A and the seat belt anchor fixing portion 1C at the outer edge in the vehicle width direction.

[0044] The seat bracket 20 is bent to fit along the floor panel 10, and a bolt insertion hole that communicates with the bolt insertion hole 13 in the seat rear fixing part 1A is opened in the center of the seat bracket 20. A bolt B for fastening the seat is inserted from above through the bolt insertion hole formed in the rear end of the fixed rail S2a, the bolt insertion hole 13 in the seat rear fixing part 1A, and the bolt insertion hole in the seat bracket 20, and is screwed into a weld nut N on the underside of the seat bracket 20. This fastens and fixes the rear end of the fixed rail S2a to the seat rear fixing part 1A.

[0045] In the illustrated example, the seat bracket 20 has a bracket main body 21 to which a weld nut N is welded, a bracket rear flange 22 extending from the rear edge of the bracket main body 21 toward the rear of the vehicle, a bracket inner flange 23 extending from the inner edge of the bracket main body 21 in the vehicle width direction toward the inner side in the vehicle width direction, and a bracket vertical wall 24 extending above the vehicle from a portion of the outer edge of the bracket main body 21 in the vehicle width direction.

[0046] The front edge of bracket body 21 overlaps the underside of inclined portion 11 of main floor panel 10A and is joined by spot welding in a three-layer configuration together with the rear edge of anchoring force 30. The center of bracket body 21 abuts against the underside of seat rear fixing portion 1A of floor panel 10, extends forward and backward, and is joined by spot welding to the underside of seat rear fixing portion 1A. Bracket rear flange 22 overlaps the underside of the rear edge of main floor panel 10A and is joined by spot welding in a three-layer configuration together with the front edge of rear reinforcement 40.

[0047] 2, 4, and 5, the bracket inner flange 23 is sandwiched between the lower surface of a portion of the inner bead portion 14a of the main floor panel 10A that is along the inner side in the vehicle width direction and the upper surface of the side-member inner flange 53 of the rear side member 50, and the bracket inner flange 23, the main floor panel 10A, and the side-member inner flange 53 are joined in three layers by spot welding. Furthermore, the bracket vertical wall 24 is sandwiched between the outer surface of the panel outer wall 15 of the main floor panel 10A and the inner surface of the side-member outer wall 54 of the rear side member 50, and the bracket vertical wall 24, the panel outer wall 15, and the side-member outer wall 54 are joined in three layers by spot welding. Furthermore, the panel outer wall 15 is sandwiched at the front edge of the rear reinforcement 40 between the reinforcement vertical wall 43 and the side-member outer wall 54, and the front edge of the reinforcement vertical wall 43, the rear edge of the panel outer wall 15, and the side-member outer wall 54 are joined in three layers by spot welding.

[0048] The anchoring force 30 has an anchoring force main body 30A having a seat belt anchor fixing portion 1C, and a thin plate-shaped rear extension portion 30B extending rearward from a part of the rear end of the anchoring force main body 30A. The anchoring force main body 30A accounts for the majority of the anchoring force 30, and the rear extension portion 30B is a portion that constitutes the rear end portion including the rear end of the anchoring force 30.

[0049] In this embodiment, the anchoring force main body 30A has a central bottom wall portion 31, a bulging portion 32, an anchoring force inner flange 33, an anchoring force outer flange 34, and an anchoring force vertical wall 35. In the illustrated example, the central bottom wall portion 31, the bulging portion 32, the anchoring force inner flange 33, and the anchoring force outer flange 34 are each curved so that the rear portion is positioned outward in the vehicle width direction relative to the front portion in a plan view seen from above the vehicle.

[0050] The central bottom wall portion 31 extends in the vehicle longitudinal direction at the vehicle widthwise central portion of the anchoring force body 30A, and is formed to fit along the upper surface of the inclined portion 11 and the front floor portion 12 of the main floor panel 10A.

[0051] The bulging portion 32 bulges upward from the vehicle and extends from the rear end of the anchoring force body in the forward direction of the vehicle. In the illustrated example, the bulging portion 32 is provided along each of the outer and inner portions in the vehicle width direction of the central bottom wall portion 31. That is, in the illustrated example, the anchoring force body 30A has two bulging portions (32, 32).

[0052] The two bulging portions (32, 32) extend in the longitudinal direction of the vehicle, spaced apart from each other in the vehicle width direction, and each bulging portion 32 bulges upward of the vehicle. The inner bulging portion 32 extends to be continuous with the inner bead portion 14a of the bead portion 14 of the floor panel 10, and the outer bulging portion 32 extends to be continuous with the outer bead portion 14b of the bead portion 14 of the floor panel 10.

[0053] In the illustrated example, a seat front fixing portion 1B is provided on the upper wall of the front end portion of the inner bulge portion 32. Also, in the illustrated example, a seat belt anchor fixing portion 1C is provided on the upper wall of the rear end portion of the outer bulge portion 32.

[0054] The seat belt anchor fixing portion 1C is formed as a horizontally extending upper wall of a bulge formed so as to bulge slightly upward on the upper wall of the outer bulge portion 32. A bolt insertion hole 36 is formed in the seat belt anchor fixing portion 1C, and a bolt B for fastening the anchor is inserted through the bolt insertion hole 36 formed in the seat belt anchor S3 and the bolt insertion hole 36 in the seat belt anchor fixing portion 1C from above, and is screwed into a weld nut N on the underside of the seat belt anchor fixing portion 1C. This fastens and fixes the seat belt anchor S3 to the seat belt anchor fixing portion 1C.

[0055] The anchoring force inner flange 33 extends inward in the vehicle width direction from the lower end of the inner vertical wall of the inner bulging portion 32 on the vehicle width direction inner side, and is joined to the upper surface of the main floor panel 10A. When viewed from above the vehicle, the anchoring force inner flange 33 is arranged so as to be aligned with the reinforcement inner flange 42 of the rear reinforcement 40, the bracket inner flange 23 of the seat bracket 20, and the side member inner flange 53 of the rear side member 50.

[0056] The anchoring force outer flange 34 extends outward in the vehicle width direction from a portion of the outer edge of the anchoring force 30 that is rearward of the seat belt anchor fixing portion 1C. In the illustrated example, the anchoring force outer flange 34 extends outward in the vehicle width direction from the lower end of the outer vertical wall of the outer bulge portion 32, and is joined to the outer edge of the upper surface of the main floor panel 10A in the vehicle width direction.

[0057] The anchoring force vertical wall 35 extends upward from a portion of the outer edge of the anchoring force 30 in the vehicle width direction that corresponds to the seat belt anchor fixing portion 1C. The anchoring force vertical wall 35 is joined to the inner surface of the panel outer wall 15 of the main floor panel 10A and the inner surface of the side member outer wall 54 of the rear side member 50 by spot welding.

[0058] The rear extension portion 30B constitutes the rear edge portion of the anchoring force 30 and is formed in a thin plate shape, extending rearward from a portion of the rear end of the anchoring force main body 30A, as described above. In other words, the rear extension portion 30B is not formed across the entire rear edge portion of the anchoring force 30 in the vehicle width direction. Rather, the rear extension portion 30B is a portion that extends slightly rearward of the vehicle and has a width shorter than the entire width of the rear portion of the anchoring force main body 30A in the vehicle width direction. The rear extension portion 30B is located between the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A in the vehicle fore-and-aft direction and is joined to the floor panel 10 and the seat bracket 20. The rear extension portion 30B overlaps the upper surface of the inclined portion 11 of the main floor panel 10A at a position corresponding to the front edge portion of the seat bracket 20, and the front edge portion of the seat bracket 20, the rear edge portion of the anchoring force 30, and the main floor panel 10A are joined in a three-layer configuration by spot welding.

[0059] Spot welding points to the floor panel 10 are set at each of the inner and outer end portions of the rear extension portion 30B in the vehicle width direction. In the illustrated example, the center portion of the rear extension portion 30B in the vehicle width direction bulges outward from the vehicle so as to be continuous with the bulging portion 32 on the outside of the anchoring force main body 30A. Both ends of the rear extension portion 30B in the vehicle width direction are bent toward the floor panel 10 and then extend rearward in a flange-like manner along the floor panel 10 (see Figure 6). The rear portion of the anchoring force vertical wall 35 is connected to the outer end portion of the rear extension portion 30B in the vehicle width direction.

[0060] In this embodiment, a notch 37 is formed in the rear portion of the anchoring force main body 30A, in a portion located on the vehicle widthwise inner side relative to the rear extension portion 30B, and is cut out toward the front of the vehicle. The notch 37 is formed in the rear portion of the anchoring force main body 30A, cutting out the vehicle widthwise inner portion of the rear of the central bottom wall portion 31, the rear portion of the inner bulge portion 32, and the rear portion of the anchoring force inner flange 33. When viewed from above the vehicle, the first edge portion 37a constituting the notch 37 extends generally in the vehicle width direction, and the second edge portion 37b constituting the notch 37 extends generally in the vehicle front-rear direction. The second edge portion 37b is continuous with the vehicle widthwise inner edge portion of the rear extension portion 30B. Therefore, the spot welding point at the vehicle widthwise inner end portion of the rear extension portion 30B is adjacent to the second edge portion 37b.

[0061] Of the anchoring force main body 30A, the inner rear corner 38 adjacent to the first edge 37a extending in the vehicle width direction and constituting the cutout portion 37 is joined to the floor panel 10 (main floor panel 10A). In other words, the inner rear corner 38 is also the rear end portion of the anchoring force inner flange 33 of the anchoring force main body 30A. The inner rear corner 38 is adjacent to the first edge 37a extending in the vehicle width direction of the cutout portion 37. In other words, the rear edge of the anchoring force inner flange 33 constitutes part of the first edge 37a. In a plan view seen from above the vehicle, the cutout portion 37 is located between the inner rear corner 38 and the inner end portion in the vehicle width direction of the rear extension portion 30B, both of which are joining points (spot welding points) to the floor panel 10. In other words, the rear portion of the anchoring force 30 is cut out at the inner portion in the vehicle width direction, and spot welding points to the floor panel 10 are set on both sides of this cutout portion 37 in the vehicle width direction.

[0062] In this embodiment, the inner rear corner 38 of the anchoring force main body 30A is joined to the floor panel 10 and the cross member 70. Referring to FIG. 6, the cross member 70 is formed with a hat-shaped cross section that opens upward, and the front flange 71 and rear flange 72 of the cross member 70 are each joined by spot welding to the underside of the inclined portion 11 of the main floor panel 10A. Referring to FIG. 4, the inner rear corner 38 of the anchoring force main body 30A is located above the rear flange 72 of the cross member 70. Therefore, the inclined portion 11 of the main floor panel 10A is sandwiched between the inner rear corner 38 of the anchoring force main body 30A and the rear flange 72 of the cross member 70, and the inner rear corner 38, the inclined portion 11, and the rear flange 72 are joined in a three-layer configuration by spot welding, and the inner rear corner 38 is joined not only to the floor panel 10 but also to the cross member 70.

[0063] In this embodiment, the seat belt anchor fixing portion 1C is provided at the rear of the anchor force main body 30A, on the vehicle width direction outer side of the second edge portion 37b that constitutes the cutout portion 37 and extends in the vehicle front-rear direction, and is adjacent to the rear extension portion 30B. In the illustrated example, the seat belt anchor fixing portion 1C is located on the upper wall of the outer bulging portion 32 that is located outward from the second edge portion 37b, adjacent to the rear end of the bulging portion 32, and is continuous with the front end of the rear extension portion 30B. In relation to the seat rear fixing portion 1A, the seat belt anchor fixing portion 1C is arranged on the vehicle width direction outer side of the seat rear fixing portion 1A.

[0064] In this embodiment, the seat rear fixing portion 1A is disposed approximately on the outer side in the vehicle width direction of the second edge portion 37b of the cutout portion 37 and on the inner side in the vehicle width direction of the seat belt anchor fixing portion 1C. In the illustrated example, the seat rear fixing portion 1A is located rearward of the rear extension portion 30B in a vehicle width direction region corresponding to the central bottom wall portion 31 of the anchor force main body 30A.

[0065] As described above, the bulge portion 32 extends in the vehicle fore-and-aft direction on both sides of the central bottom wall portion 31 of the anchoring force main body 30A. In this embodiment, referring to FIG. 4, the bulge height H of the bulge portion 32 decreases at the rear of the bulge portion 32 toward the rear end of the anchoring force main body 30A. The bulge portion 32 extends in the vehicle fore-and-aft direction along the central bottom wall portion 31, the anchoring force inner flange 33, and the anchoring force outer flange 34 of the anchoring force main body 30A, and the central bottom wall portion 31, the anchoring force inner flange 33, and the anchoring force outer flange 34 are each formed rearwardly upward to follow the upper surface of the inclined portion 11 of the main floor panel 10A. As a result, the bulge height H of the bulge portion 32 decreases toward the rear end of the anchoring force main body 30A depending on the degree of inclination of the inclined portion 11.

[0066] Next, the operation of the vehicle body underbody structure 1 according to this embodiment in the event of a frontal collision or the like will be described.

[0067] 1, 3, and 6, in the event of a frontal collision, a tensile load acts on the seat rear fixing portion 1A and the seat belt anchor fixing portion 1C, pulling them forward and diagonally upward, and this tensile load also has a component force inward in the vehicle width direction at the seat belt anchor fixing portion 1C. Here, the fixing portions of the seat S to the lower part of the vehicle body, the seat rear fixing portion 1A and the seat front fixing portion 1B, are separated by a large distance in the front-to-rear direction of the vehicle by the fore-and-aft length of the seat rail S2, and both are provided on the anchor reinforcement 30, and the seat belt anchor fixing portion 1C is disposed near the front of the vehicle and around the seat rear fixing portion 1A. Therefore, when a tensile load acts on the seat rear fixing portion 1A and the seat belt anchor fixing portion 1C, which are close to each other, during a frontal collision, the lower part of the vehicle body (floor panel 10, anchor force 30, etc.) may adopt a deformation mode in which the rear end of the seat rail S2 (seat rear fixing portion 1A) is lifted forward and diagonally upward, with the seat front fixing portion 1B as the starting point (center of rotation).

[0068] In response to the deformation modes that may occur during a frontal collision, the vehicle body lower structure 1 has the following configuration: (1) an anchor force 30 having a seat belt anchor fixing portion 1C extends in the fore-and-aft direction of the vehicle in front of the vehicle relative to the seat rear fixing portion 1A and is joined to the upper surface of the floor panel 10; and (2) the seat belt anchor fixing portion 1C is provided at the rear of the anchor force 30, and the anchor force 30 has an anchor force main body 30A having the seat belt anchor fixing portion 1C and a thin plate-shaped rear extension portion 30B extending rearward from a part of the rear end of the anchor force main body 30A, which is located between the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A in the fore-and-aft direction of the vehicle, and the rear extension portion 30B is joined to the seat bracket 20 that reinforces the seat rear fixing portion 1A and the floor panel 10.

[0069] According to the above configurations (1) and (2) of the vehicle body lower structure 1, the rear extension portion 30B of the anchor force 30, which is located between the seat belt anchor fixing portion 1C and the seat rear side fixing portion 1A and is joined to the seat bracket 20 and the floor panel 10, does not extend over the entire vehicle width direction of the rear edge of the anchor force 30, but extends rearward from a part of the rear end of the anchor force main body 30A, so that part of the rear portion of the anchor force 30 is interrupted. In addition, in the floor panel 10 between the seat belt anchor fixing portion 1C and the seat rear side fixing portion 1A, there is a portion joined to the rear extension portion 30B and a portion not joined to the rear extension portion 30B (in other words, a portion adjacent to the rear extension portion 30B in the vehicle width direction), and a difference in rigidity occurs between the portion joined to the rear extension portion 30B and the portion not joined to the rear extension portion 30B. As a result, when a tensile load acts on the seat belt anchor fixing portion 1C during a frontal collision or the like, the portion of the floor panel 10 between the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A that is not joined to the rear extension portion 30B (the portion adjacent to the rear extension portion 30B in the vehicle width direction) becomes the starting point of deformation of the floor panel 10, making it more likely to deform, and the impact due to the input load is more likely to be absorbed by the deformation of the floor panel 10. Therefore, even if the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A are arranged close to each other, in the above deformation mode, deformation of the anchoring force 30 and the like is significantly suppressed, and peeling of the welded portion of the anchoring force 30 having the seat belt anchor fixing portion 1C to the floor panel 10 is effectively prevented.

[0070] As described above, the vehicle body lower structure 1 of this embodiment has a structure that can reduce the effect of the input load on the joining state of the seat belt anchor fixing portion 1C, even if the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A are arranged close to each other.

[0071] In this embodiment, a notch 37 is formed in the rear portion of the anchoring force main body 30A, in a portion located inward in the vehicle width direction relative to the rear extension 30B, and an inner rear corner 38 of the anchoring force main body 30A adjacent to a first edge 37a extending in the vehicle width direction and constituting the notch 37, is joined to the floor panel 10. As a result, compared to when the notch 37 is not formed, the floor rigidity of the portion of the floor panel 10 located inward in the vehicle width direction relative to the rear extension 30B can be locally and significantly reduced. Therefore, in the portion inward in the vehicle width direction relative to the rear extension 30B, upward deformation of the floor panel 10 is more likely to be promoted, and impacts due to input loads are more likely to be absorbed by deformation of the floor panel 10. As a result, peeling of the welded portion of the anchoring force 30 to the floor panel 10 can be more effectively prevented.

[0072] In this embodiment, the vehicle body lower structure 1 includes a cross member 70 that is located below the floor panel 10 and extends in the vehicle width direction at a position corresponding to the seat belt anchor fixing portion 1C in the vehicle fore-and-aft direction, and is joined to the floor panel 10, and the inner rear corner portion 38 of the anchoring force main body 30A, the floor panel 10, and the cross member 70 are joined. As a result, deformation of the floor panel 10 in the portion that is located inward in the vehicle width direction from the rear extension portion 30B of the floor panel 10 and rearward of the vehicle from the inner rear corner portion 38 of the floor panel 10 is more significantly promoted. Therefore, peeling of the welded portion of the anchoring force 30 to the floor panel 10 can be more significantly prevented.

[0073] In this embodiment, the seat belt anchor fixing portion 1C is provided at the rear of the anchor force main body 30A, on the vehicle widthwise outer side of the second edge portion 37b that extends in the vehicle fore-and-aft direction and constitutes the cutout portion 37, and is adjacent to the rear extension portion 30B. Since the tensile load acting on the seat belt anchor fixing portion 1C in the forward and diagonally upward direction during a frontal collision or the like also acts on the vehicle widthwise inner side, by arranging the seat belt anchor fixing portion 1C on the vehicle widthwise outer side of the cutout portion 37 and adjacent to the rear extension portion 30B, deformation of the floor panel 10 in the vehicle widthwise inner side and toward the vehicle front, starting from the cutout portion 37, is more effectively promoted, and peeling of the welded portion, etc. can be more effectively prevented.

[0074] In this embodiment, the seat rear fixing portion 1A is disposed rearward of the second edge 37b of the cutout 37 and inward in the vehicle width direction of the seat belt anchor fixing portion 1C. As a result, the seat belt anchor fixing portion 1C and the seat rear fixing portion 1A are shifted in the vehicle width direction, and the input point of the tensile load is shifted in the vehicle width direction, which also promotes lateral deformation of the floor panel 10 and promotes three-dimensional deformation. As a result, peeling of welded portions can be more effectively prevented.

[0075] In this embodiment, the anchor force main body 30A has a bulge portion 32 that bulges upward from the vehicle and extends from the rear end of the anchor force main body in the forward direction of the vehicle, and the bulge height H of the bulge portion 32 decreases at the rear of the bulge portion 32 toward the rear end of the anchor force main body 30A. Therefore, the rigidity in the vertical direction of the rear of the anchor force main body 30A decreases toward the rear end of the anchor force main body 30A in accordance with the decrease in the bulge height H of the bulge portion 32. As a result, in the event of a frontal collision, etc., a certain degree of deformation is possible even at the rear of the anchor force 30, and the impact due to the input load is also absorbed by the deformation of the anchor force 30, and peeling of the welded portions of the anchor force 30 can be extremely effectively prevented.

[0076] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and further modifications and changes are possible based on the technical concept of the present invention. [Explanation of symbols]

[0077] 1...Underbody structure 1A...Rear seat fixing part 1C...Seatbelt anchor fixing part 10...Floor panel 20…Seat bracket 30...Anchoring Force 30A...Anchoring Force main body 30B…Rear extension part 32...bulge 37...Notch 37a...first edge 37b…Second edge 38…Medial posterior corner 40...Rear reinforcement 50...Rear side member 60...Side sill 70...Cross member S...Seat S3...Seatbelt anchor H: Bulge height

Claims

1. A vehicle body underbody structure including: a floor panel disposed in a vehicle body underbody and having a seat rear fixing portion; and a seat bracket reinforcing the seat rear fixing portion, wherein a seat belt anchor fixing portion is disposed in the vehicle underbody forward of the seat rear fixing portion and in the periphery of the seat rear fixing portion, an anchoring force extending in the vehicle front-rear direction in front of the seat rear fixing portion and having the seat belt anchor fixing portion, and joined to an upper surface of the floor panel; The seat belt anchor fixing portion is provided at the rear of the anchoring force, The anchoring force is An anchoring force main body having the seat belt anchor fixing portion; a thin plate-shaped rear extension portion extending rearward from a portion of the rear end of the anchoring force body, the rear extension portion being located between the seat belt anchor fixing portion and the seat rear fixing portion in the vehicle longitudinal direction and joined to the floor panel and the seat bracket; A vehicle underbody structure comprising:

2. A notch portion is formed in a portion of the rear portion of the anchoring force body that is located on the inner side in the vehicle width direction with respect to the rear extension portion, the notch portion being cut out toward the front of the vehicle, 2. The vehicle body understructure according to claim 1, wherein an inner rear corner portion of the anchoring force body adjacent to a first edge portion extending in the vehicle width direction and constituting the cutout portion is joined to the floor panel.

3. a cross member that is below the floor panel and extends in the vehicle width direction at a position corresponding to the seat belt anchor fixing portion in the vehicle front-rear direction, and is joined to the floor panel; The vehicle underbody structure according to claim 2 , wherein the inner rear corner portion of the anchoring force body, the floor panel, and the cross member are joined together.

4. The vehicle body understructure described in claim 2, wherein the seat belt anchor fixing portion is provided at the rear of the anchor force main body, outside in the vehicle width direction relative to a second edge portion extending in the vehicle fore-and-aft direction that constitutes the cutout portion, and is adjacent to the rear extension portion.

5. The vehicle body underbody structure according to claim 4, wherein the seat rear fixing portion is disposed rearward of the second edge portion and inward in the vehicle width direction of the seat belt anchor fixing portion.

6. The anchoring force body has a bulging portion that bulges upward from the vehicle and extends from a rear end of the anchoring force body in a forward direction of the vehicle, 6. The vehicle underbody structure according to claim 1, wherein the bulging height of the bulging portion decreases toward the rear end of the anchoring force body at the rear of the bulging portion.

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