VEHICLE BODY UNDERGROUND

Abstract

Vehicle body underbody (1) comprising a floor plate (10) provided in a lower vehicle body section and including a rear seat mounting section (1A), and a seat bracket (20) for reinforcing the rear seat mounting section (1A), a seat belt anchorage mounting section (1C) provided in the lower vehicle body section at a vehicle front of the rear seat mounting section (1A) and around the rear seat mounting section (1A), characterized in that: the vehicle body underbody (1) comprises an anchorage reinforcement (30) extending in a front-rear direction of the vehicle at the vehicle front of the rear seat mounting section (1A) which includes the seat belt anchorage mounting section (1C), and which is joined to an upper surface of the floor plate (10);the seat belt anchorage mounting section (1C) is provided on a rear section of the anchorage reinforcement (30); and the anchorage reinforcement (30) comprises an anchorage reinforcement main body (30A) which includes the seat belt anchorage mounting section (1C), and a thin plate-shaped rear extension (30B) extending rearward from a portion of a rear end of the anchorage reinforcement main body (30A), the rear extension (30B) extending between the seat belt anchorage mounting section (1C) and the rear seat mounting section (1A) in the front-to-rear direction of the vehicle and joined to the floor plate (10) and the seat mount (20).

Description

The present invention relates to a vehicle body underframe. [State of the art] Near a seat in a lower section of a vehicle body, a seatbelt anchor mounting section, to which a seatbelt anchor carrying a seatbelt is attached, and a rear seat mounting section, to which a rear seat section, such as a rear slide rail section, is attached, are provided. The seatbelt anchor mounting section and the rear seat mounting section can be subject to a load that pulls each mounting section forward and obliquely upward. For this reason, to reinforce each mounting section, a reinforcing element, such as a reinforcement (which may also be called a bracket), is often spot-welded to each mounting section. A structure disclosed in patent literature 1 is known as an example of a vehicle body underbody comprising a structure in which a seatbelt anchorage mounting section and a rear seat mounting section are reinforced. In the structure disclosed in patent literature 1, a seatbelt anchorage holder is welded to a lower surface of a floor plate in a part corresponding to the seatbelt anchorage mounting section, and the seatbelt anchorage is attached, together with the floor plate, to a longitudinal center section of the holder by a bolt.In a section corresponding to the rear seat mounting section, a cross member having a hat-shaped cross-section is welded to the lower surface of the floor plate, and a rear end section of a slide rail can be bolted and attached to a section having a closed cross-section formed by the cross member and the floor plate.Then, in the structure disclosed in patent literature 1, the holder is provided with a pair of stiffness reinforcement sections extending in the front-rear direction such that they sandwich the attachment and fastening point on the base plate with the bolt, the rear end section of the holder is welded to a lower surface of the flange of the cross member, which is welded to the lower surface of the base plate, and furthermore, the holder is welded to the lower surface of the base plate in an area between the welding and fastening point on the flange of the cross member and the rear end of the stiffness reinforcement section. Since the structure disclosed in patent literature 1 provides the structure described above, when a load is applied to the floor plate in the direction of the upper surface of the vehicle body, and the attachment and fastening point (i.e., the seat belt anchorage fastening section) of the holder moves upwards and deforms on the floor plate, causing the rear section of the stiffness reinforcement section to lift the floor plate upwards, the spot weld of the rear end section of the holder and the flange of the cross member are prevented from detaching.Then, in the structure disclosed in patent literature 1, the seat belt anchorage fastening section (attachment and fastening point of the holder on the base plate) is provided in the longitudinal center section of the holder, and the seat belt anchorage fastening section is sufficiently spaced from the rear seat fastening section (attachment and fastening point of the rear end section of the slide rail to the closed cross-sectional section). [List of quotes] [Patent literature] [Patent literature 1] JP 2012 - 218 519 A From DE 10 2005 030 100 A1 a vehicle body underbody is known which has features of a corresponding underbody with integrated seat mounting sections and a seat belt anchorage. BRIEF SUMMARY OF THE INVENTION [Problem to be solved by the invention] In some cases, in a lower section of the vehicle body, the seat belt anchorage mounting section is located at the front of the vehicle, adjacent to the rear seat mounting section, and the seat belt anchorage mounting section and the rear seat mounting section, which are load entry points, are positioned close to each other. In this case, to reduce deformation of the floor panel and the like caused by the input load, it is conceivable to weld a reinforcing element, such as the bracket and cross member, to the seat belt anchorage mounting section and the rear seat mounting section, as described in patent literature 1, to improve stiffness.In the layout where the seatbelt anchorage mounting section and the rear seat mounting section are positioned close to each other, when the stiffness of each mounting section is improved by the reinforcement element, the load concentrates around each mounting section (seatbelt anchorage mounting section and rear seat mounting section), and the base plate and the like are deformed more than expected, which may compromise the assembled state of the mounting section. In view of the above, it is an object of the present invention to provide a vehicle body underbody which includes a structure which can reduce the effect of an input load in an assembled state of a fastening section even when a seat belt anchorage fastening section and a rear seat fastening section are arranged close to each other. [Means to solve the problem] According to one aspect of the present invention for achieving the above objective, a vehicle body underbody is provided comprising a floor plate provided in a lower vehicle body section and comprising a rear seat mounting section, a seat bracket for reinforcing the rear seat mounting section, and a seat belt anchorage mounting section provided in the lower vehicle body section at a vehicle front of the rear seat mounting section and around the rear mounting section.The vehicle body substructure includes an anchoring reinforcement extending in a front-to-rear direction of the vehicle at the front of the rear seat mounting section, which includes the seat belt anchorage mounting section, and which is joined to an upper surface of the floor panel; the seat belt anchorage mounting section is provided in a rear section of the anchoring reinforcement, and the anchoring reinforcement includes an anchoring reinforcement main body, which includes the seat belt anchorage mounting section, and a thin, plate-shaped rear extension, which extends rearward from part of a rear end of the anchoring reinforcement main body and the rear seat mounting section in the front-to-rear direction of the vehicle and is joined to the floor panel and the seat mount. [Advantageous effect of the invention] According to one aspect of the present invention, it is possible to provide a vehicle body underbody which includes a structure which can reduce the effect of an input load in an assembled state of a fastening section even when a seat belt anchorage fastening section and a rear seat fastening section are arranged close to each other. BRIEF DESCRIPTION OF DRAWINGS [Fig. 1] Fig. 1 is a perspective view of a vehicle body underbody according to an embodiment of the present invention. [Fig. 2] Fig. 2 is a partial bottom view of the vehicle body underbody. [Fig. 3] Fig. 3 is an enlarged top view of a main part of the vehicle body underbody. [Fig. 4] Fig. 4 is a perspective view of the main part of the vehicle body underbody. [Fig. 5] Fig. 5 is a perspective view of a part of the vehicle body underbody that includes a seat mount, viewed from below. [Fig. 6] Fig. 6 is a cross-sectional view taken along line AA in Fig. 3. [Mode of implementation of the invention] An embodiment of the present invention is described below with reference to the accompanying drawings. Fig. 1 is a perspective view of a vehicle body underbody 1 according to an embodiment of the present invention, Fig. 2 is a partial bottom view of the vehicle body underbody 1, and Figs. 3 and 4 are diagrams illustrating a major part of the vehicle body underbody 1. Fig. 3 is an enlarged top view and Fig. 4 is a perspective view. It should be noted that in the drawings, an arrow direction Fr indicates the front in the front-to-rear direction of the vehicle, an arrow direction O indicates the outside of the vehicle in the vehicle width direction, and an arrow direction U indicates the top in the front-to-rear direction of the vehicle.In the following description, “front” and “rear” correspond to the front and rear of the vehicle in the front-to-rear direction, “up” and “down” correspond to an upward and downward orientation of the vehicle, and “left” and “right” correspond to the left and right sides in the width direction of the vehicle when an occupant is facing the front of the vehicle. It should be noted that in Fig. 3, a seat main body S1, described below, is removed, and a stationary rail S2a of the seat rail S2, described below, is indicated by a double-dashed line. In Fig. 4, a seat S and a seat belt anchorage S3, described below, are each removed. (Overview of the vehicle body underbody) Referring to Figures 1, 2, 3 to 4, the vehicle body underbody 1 comprises a floor plate 10, a seat bracket 20, an anchoring reinforcement 30, a rear reinforcement 40, a rear side element 50, a side sill 60, a cross member 70, and a strut 80. The vehicle body underbody 1 of the present embodiment is applied to a vehicle body underbody of an electric vehicle powered by a power supply unit. The floor panel 10 is a plate element installed in a lower section of the vehicle body, forming a floor section of the lower vehicle body area and made of metal sheet material. The floor panel 10 is a plate-shaped element extending from a lower section of the front of a vehicle interior to a rear section of the vehicle body. The width of the floor panel 10 is essentially the same as the width of the vehicle body. The floor panel 10 comprises a main floor panel 10A and a rear floor panel 10B, which is narrower than the width of the main floor panel 10A and extends rearward from a rear edge section of the main floor panel 10A.In the illustrated example, a front edge section of the rear base plate 10B is connected to an upper surface of the rear edge section of the main base plate 10A. The seat S is mounted on the base plate 10. In the present embodiment, the seat S is mounted on the main base plate 10A. The seat S comprises a seat body S1, on which an occupant sits, and the seat rail S2, which supports the seat body S1 from below. The seat rail S2 is an element that extends in the front-to-rear direction of the vehicle between the seat body S1 and the base plate 10 and supports the seat body S1 from below such that the seat body S1 can slide in the front-to-rear direction of the vehicle. The seat rail S2 comprises the fixed rail S2a, which is attached to the side of the vehicle body, and a movable rail S2b, which is attached to a lower section of the seat body S1 and connected to the fixed rail S2a to be slidable along the fixed rail S2a. In the illustrated example, a rear end section of the seat rail S2 projects towards the rear of the vehicle from a rear section of the seat main body S1. In this case, a front end section of the seat rail S2 generally lies beneath a front section of the seat main body S1. With reference to Fig. 1, Fig. 3 and Fig. 4, a rear seat mounting section 1A, to which a rear end section of the fixed rail S2a of the seat rail S2 is attached, a front seat mounting section 1B, to which a front end section of the fixed rail S2a of the seat rail S2 is attached, and a seat belt anchorage mounting section 1C, to which the seat belt anchorage S3 for carrying a seat belt (not shown) that protects an occupant sitting in the seat S is attached, are provided in the lower vehicle body section of the vehicle body substructure 1. The rear seat mounting section 1A is provided in the floor plate 10 (main floor plate 10A), and the front seat mounting section 1B and the seat belt anchorage mounting section 1C are provided in the anchorage reinforcement 30. Accordingly, the floor plate 10 (main floor plate 10A) includes the rear seat mounting section 1A, and the anchorage reinforcement 30 includes the front seat mounting section 1B and the seat belt anchorage mounting section 1C.In other words, the rear seat mounting section 1A is a mounting point where the rear section of the seat S is attached to the floor plate 10, the front seat mounting section 1B is a mounting point where the rear section of the seat S is attached to the lower vehicle body section (anchoring reinforcement 30), and the seat belt anchor mounting section 1C is a mounting point where the seat belt anchorage S3 is attached to the lower vehicle body section (anchoring reinforcement (30)). The seat bracket 20 is a reinforcing element that strengthens the rear seat mounting section 1A of the floor plate 10. The seat bracket 20 is joined to the floor plate 10. It is formed by machining processes, such as pressing, on a metal sheet material. The seat bracket 20 is joined to the floor plate 10 from the outside of the vehicle interior by spot welding. The seat bracket 20 is therefore joined to a lower surface of the rear seat mounting section 1A of the floor plate 10. The shape and other features of the seat bracket 20 are described in more detail below. The anchoring reinforcement 30 is an element that extends in the front-to-rear direction of the vehicle at the front of the rear seat mounting section 1A and includes the seat belt anchorage mounting section 1C. The anchoring reinforcement 30 is formed by processing, such as pressing, on a metal sheet material. The anchoring reinforcement 30 is designed to have high rigidity and reinforces the seat belt anchorage mounting section 1C in the lower vehicle body section. The anchoring reinforcement 30 is located on the inside of the vehicle interior in relation to the floor plate 10 and is joined to the floor plate 10 (main floor plate 10A) by spot welding on an upper surface of the floor plate 10. Here, with reference to Figures 3 and 4 in a vertical view of the vehicle, the floor plate 10 (main floor plate 10A) is formed such that a section corresponding to the rear seat mounting section 1A gradually extends outwards in the vehicle width direction towards the front of the vehicle, and a section bulges far outwards over the seat belt anchorage mounting section 1C in the vehicle width direction. Then, in the vertical view of the vehicle, the anchoring reinforcement 30 has an outer shape corresponding to the shape of the floor plate 10 on the outside in the vehicle width direction, is configured to overlap the upper surface of the floor plate 10, and extends in the front-to-rear direction of the vehicle.Therefore, the anchoring reinforcement 30, in a vertical view of the vehicle, is designed such that it gradually extends outwards in the vehicle width direction towards the front of the vehicle at a section corresponding to the seat belt anchorage mounting section 1C, and even further bulges outwards in the vehicle width direction at a section extending beyond the seat belt anchorage mounting section 1C. Additionally, an edge section of the anchoring reinforcement 30 extends slightly obliquely on the inside in the vehicle width direction such that it extends from the center of the vehicle body width towards the front of the vehicle. The rear seat mounting section 1A is positioned on the floor plate 10 near a rear section of the seat S and close to an outer edge section spanning the vehicle width of the floor plate 10. With respect to the anchoring reinforcement 30, the rear seat mounting section 1A is located behind and adjacent to the rear end of the anchoring reinforcement 30. In the illustrated example, the rear section of the seat S is attached and secured to the floor plate 10 by fastening the rear end section of the fixed rail S2a to the rear seat mounting section 1A using a rail fastening bolt B. The front seat mounting section 1B is provided on a front section of the anchoring reinforcement 30. Specifically, the front seat mounting section 1B is provided in an inner part spanning the vehicle width of the front section of the anchoring reinforcement 30. In the illustrated example, a fixed support tool S4 of the front rail end is attached to the front seat mounting section 1B by a fastener, such as a bolt B. The front section of the seat S is attached and secured to the front section of the anchoring reinforcement 30 via the fixed support tool S4 of the front rail end by fastening the front end section of the fixed rail S2a to an upper wall of the fixed support tool S4 of the front rail end using the bolt B. The seat belt anchorage mounting section 1C is provided in a rear section of the anchorage reinforcement 30. Specifically, the seat belt anchorage mounting section 1C is provided in an outer portion spanning the vehicle width of the rear section of the anchorage reinforcement 30. Therefore, in the lower vehicle body section, the seat belt anchorage mounting section 1C is located on the vertical front side and around the rear seat mounting section 1A. In the illustrated example, the seat belt anchorage mounting section 1C and the rear seat mounting section 1A are located close to each other. Furthermore, viewed from above the vehicle in the rear-front direction of the vehicle, the seat belt anchorage mounting section 1C is located between the rear seat mounting section 1A and the front seat mounting section 1B, in a position close to the rear seat mounting section 1A.In the illustrated example, the seat belt anchorage S3 is attached and secured to the anchorage reinforcement 30 by attaching the seat belt anchorage S3 to the seat belt anchorage fastening section 1C using the anchorage fastening bolt B. The rear reinforcement 40 extends in the rear-front direction of the vehicle at the rear of the rear seat mounting section 1A. The rear reinforcement 40 is made of a metal sheet material that extends along an outer edge section spanning the vehicle width of the floor panel 10. The floor panel 10 is formed such that only a section, generally corresponding to the rear seat mounting section 1A, is cut out in the inward direction in the vehicle width direction in a portion behind the rear seat mounting section 1A. The rear reinforcement 40 then extends along an upper surface of the outer edge section spanning the vehicle width of a portion (i.e., rear floor panel 10B in an illustrated example) of the floor panel 10 behind the seat mounting section 1A and is joined to the floor panel 10 by spot welding. The rear reinforcement 40 includes a reinforcement main body 41 extending in the front-rear direction of the vehicle, an inner lateral reinforcement flange 42 extending along an inner edge section in the vehicle width of the reinforcement main body 41, and a vertical reinforcement wall 43 extending upwards from an outer edge section in the vehicle width of the reinforcement main body 41. A leading edge section of the main reinforcement body 41 is spot-welded to an upper surface of an outer section, the width of the vehicle, of a rear edge section of the main floor panel 10A of the floor panel 10. The inner lateral reinforcement flange 42 is spot-welded to an upper surface of an outer edge section, the width of the vehicle, of the rear floor panel 10B of the floor panel 10. In the illustrated example, the outer edge section, the width of the vehicle, of the rear floor panel 10B is sandwiched between the inner lateral reinforcement flange 42 and an inner lateral flange 53 of the side element of the rear side element 50, as described below. The three elements of the outer edge section, the width of the vehicle, of the rear floor panel 10B, the inner lateral reinforcement flange 42, and the inner lateral flange 53 of the side element are welded together.The vertical reinforcement wall 43 is joined to an upper section of an inner surface of the outer side wall 54 of the rear side element 50 described below by spot welding. The rear side element 50 is an element that extends along the rear reinforcement 40 below the rear reinforcement 40 in the front-to-rear direction of the vehicle. The rear side element 50 is formed by processing, such as pressing, on a metal sheet material. The rear side element 50 is an element that extends along the outer edge section across the vehicle width of the floor panel 10 at the rear of a vehicle body side section and forms part of a vehicle body structural element. In a front section of the vehicle body underbody 1, outside the illustrated area, a front side element extending towards the front of the vehicle is provided on both sides in the vehicle width direction, but the rear side element 50 is not formed to be continuous with the front side element. In the vehicle body underbody 1, the side element is not continuous from the front vehicle body section to the rear vehicle body section, and the impact performance of the side element can be reduced. The anchoring reinforcement 30 therefore also serves as an element that compensates for the reduced impact performance due to the interruption of the side element.The anchoring reinforcement 30 therefore has, in addition to the reinforcing function of the part of the vehicle body substructure to which the seat belt anchorage S3 is attached, a function as a vehicle body structural element to meet the impact performance. The rear side element 50 comprises a main body section 50A of the rear side element along the rear reinforcement 40 and a projecting section 50B that extends towards the front of the vehicle from the front end of the rear reinforcement 40 such that the seat mount 20 is covered from below. In other words, when divided longitudinally along the vehicle, the rear side element 50 is formed from the main body section 50A of the rear side element and the projecting section 50B. In the illustrated example, the projecting section 50B extends forward to a position that exceeds a position below the seat belt anchorage S3 (seat belt anchorage mounting section 1C). The rear side element 50 includes a side element floor wall 51, which lies below the rear reinforcement 40, a side element inner wall 52, which extends upwards from the inner end in the vehicle width of the side element floor wall 51, wherein the inner lateral flange 53 of the side element extends inwards in the vehicle width direction from the upper end of the side element inner wall 52, and the side element outer wall 54 extends upwards from the outer end in the vehicle width of the side element floor wall 51. In the illustrated example, the outer side wall 54 of the rear side element 50 extends along an outer surface of the vertical reinforcement wall 43 of the rear reinforcement 40, an outer surface of a vertical support wall 24 of the seat support 20 (described below), an outer surface of the outer plate wall 15 of the main floor plate 10A (described below), and an outer surface of the vertical anchor reinforcement wall 35 of the anchor reinforcement 30 (described below). The outer side wall 54 is joined to the vertical reinforcement wall 43, the vertical support wall 24, the outer plate wall 15, and the vertical anchor reinforcement wall 35 by spot welding. The side wall 60 extends in the front-to-rear direction of the vehicle along each of an outer edge section of the vehicle in the vehicle width of the main floor plate 10A and an outer edge section in the vehicle width of the anchoring reinforcement 30, and is joined to the main floor plate 10A and the anchoring reinforcement 30 by spot welding. The side sill 60 is formed by processing, such as pressing, on a metal sheet material. A vertical side sill wall 61 on the outside in the vehicle width direction of the side sill 60 is joined to an outer surface of a rear end section of the side element outer wall 54 of the projecting section 50B of the rear side element 50 by spot welding. The cross member 70 is provided beneath the floor panel 10 and extends in the vehicle width direction in a position corresponding to the seat belt anchorage mounting section 1C in the front-to-rear direction of the vehicle. The cross member 70 is an element that forms part of a vehicle body structural element along the lower surface of the main floor panel 10A and extends in the vehicle width direction such that it bridges the left and right rear side elements 50. The cross member 70 is configured to have a hat-shaped cross-section by performing processing, such as pressing, on a metal sheet material. While the cross member 70 is divided and formed in the vehicle width direction in the illustrated example, the invention is not limited thereto, and the cross member 70 can be formed as a single body spanning the entire vehicle width direction. The cross member 70 is spot-welded to the lower surface of the main floor plate 10A. A rear section of the side sill 60 is spot-welded to an end section of the cross member 70, spanning the vehicle width, from the outside in the vehicle width direction. In other words, the cross member 70 includes an end section that is joined to the side sill 60. A front section of the rear side element 50 is formed such that it covers an end section of the cross member 70, spanning the vehicle width, from below and behind, and is spot-welded to the cross member 70. The vehicle-width end section of the cross member 70 and the main floor plate 10A are sandwiched between a rear section of the anchoring reinforcement 30 and a front section of the rear side element 50.Accordingly, the rear section of the anchoring reinforcement 30 and the front section of the rear side element 50 are coupled via the main base plate 10A and the crossbeam 70. The strut 80 extends forward in such a way that it is continuous with the front section of the rear side element 50. The strut 80 is designed such that it partially covers a front section of the rear side element 50, a rear section of the side sill 60, and the end section of the cross member 70 across the vehicle width from below the vehicle, and is joined to each of the floor plate 10, the rear side element 50, the side sill 60, and the cross member 70 by spot welding. The strut 80 includes a strut main body 81 that curves towards the lower side of the vehicle, an inner lateral strut flange 82 that extends inwards in the vehicle width direction from an inner edge section in the vehicle width of the strut main body 81, an outer lateral strut flange 83 that extends outwards in the vehicle width direction from an outer edge section in the vehicle width of the strut main body 81, and a rear strut flange 84 that extends rearwards from a rear edge section of the strut main body 81. The inner lateral strut flange 82 is joined to the main base plate 10A and the crossbeam 70, the outer lateral strut flange 83 is joined to a rear section of the side sill 60, and the rear strut flange 84 is joined to a front section of the side element base wall 51 of the rear side element 50 and the crossbeam 70. (Detailed structure of the vehicle body underbody) A detailed structure of a main part and the like of the vehicle body underbody 1 is described below with reference to Figures 1, 2, 3, 4, 5 to 6. Figure 5 is a perspective view of a part of the vehicle body underbody 1, which includes the seat bracket 20 viewed from below, and Figure 6 is a cross-sectional view along line AA of Figure 3. The rear side element 50, the side sill 60, the cross member 70, and the strut 80 have been omitted from Figure 5. Referring to Fig. 5 and Fig. 6, the seat support 20 is joined to the base plate 10 and is also attached to the rear section of the anchoring reinforcement 30 and the front section of the rear reinforcement 40 to bridge the anchoring reinforcement 30 and the rear reinforcement 40. Specifically, the front edge section of the seat mount 20 overlaps the lower surface of the main floor plate 10A in a position forward of and near the rear seat mounting section 1A, and a rear edge section (rear extension 30B, described below) of the anchoring reinforcement 30 overlaps an upper surface of the main floor plate 10A in a position corresponding to the front edge section of the seat mount 20. The three elements—the front edge section of the seat mount 20, the rear edge section of the anchoring reinforcement 30, and the main floor plate 10A—are joined together by spot welding. Then, a rear edge section of the seat mount 20 overlaps a lower surface of a rear edge section of the main floor plate 10A, and a front edge section of the reinforcement main body 41 of the rear reinforcement 40 overlaps an upper surface of a rear edge section of the main floor plate 10A.The three elements of the rear edge section of the seat support 20, the front edge section of the reinforcement main body 41 and the rear edge section of the main base plate 10A are joined together by spot welding. In the vehicle body substructure 1, the metal plate material used for the anchorage reinforcement 30 and the rear reinforcement 40 is a high-strength steel plate, while the metal plate material used for the seat bracket 20 is a conventional steel plate, which has a lower tensile strength than the high-strength steel plate. It should be noted that each of the rear side element 50, the side sill 60, the cross member 70, and the strut 80 is made of a high-strength steel plate, as in the case of the anchorage reinforcement 30 and the rear reinforcement 40, and the floor plate 10 is made of a conventional steel plate, as in the case of the seat bracket 20.In the present embodiment, the main floor plate 10A of the floor plate 10 at the vehicle front of the rear mounting section 1A includes an inclined section 11, which is inclined downwards towards the front, and a front floor section 12, which extends in the front-to-rear direction of the vehicle at the vehicle front of the inclined section 11. The rear seat mounting section 1A of the main floor plate 10A is formed as a horizontally extending wall. A bolt insertion hole 13, through which the seat mounting bolt B is inserted, is open in the rear seat mounting section 1A. In the illustrated example, the main floor plate 10A of the floor plate 10 includes a bead section 14, which extends such that it surrounds the rear seat mounting section 1A. The bead section 14 curves towards the top of the vehicle.Viewed from above the vehicle, the bead section 14 extends in the form of a concave groove, opening towards the front (U-shape), and surrounds the rear seat mounting section 1A (i.e., the rear end section of the fixed rail S2a) from the rear. In the illustrated example, the main floor panel 10A includes the panel outer wall 15, which extends towards the top of the vehicle in an outer edge section across the vehicle width in an area corresponding to the rear seat mounting section 1A and the seat belt anchorage mounting section 1C. The seat bracket 20 is curved along the base plate 10, and a bolt insertion hole, connected to the bolt insertion hole 13 of the rear seat mounting section 1A, is open in a central section of the seat bracket 20. The seat mounting bolt B is inserted from above into the bolt insertion hole formed in the rear end section of the fixed rail S2a, the bolt insertion hole 13 of the rear seat mounting section 1A, and the bolt insertion hole of the seat bracket 20, and screwed into a weld nut N in a lower surface of the seat bracket 20. The rear end section of the fixed rail S2a is thus attached to and secured against the rear seat mounting section 1A. In the illustrated example, the seat mounting 20 includes a mounting main body 21 to which the weld nut N is welded, a rear mounting flange 22 extending towards the rear of the vehicle from the rear edge of the mounting main body 21, an inner lateral mounting flange 23 extending inwards in the vehicle width from an inner edge section in the vehicle width direction of the mounting main body 21, and the vertical mounting wall 24 extending from the top of the vehicle from a part of an outer edge section in the vehicle width of the mounting main body 21. A leading edge section of the main mounting body 21 overlaps a lower surface of the inclined section 11 of the main floor plate 10A, and the three elements of the leading edge section of the main mounting body 21, the inclined section 11 of the main floor plate 10A, and a rear edge section of the anchoring reinforcement 30 are joined together by spot welding. A central section of the main mounting body 21 extends to the front and rear, abutting the lower surface of the rear seat mounting section 1A of the floor plate 10A, and is joined to the lower surface of the rear seat mounting section 1A by spot welding.The rear mounting flange 22 overlaps a lower surface of the rear edge section of the main base plate 10A, and the three elements of the rear mounting flange 22, the rear edge section and the main base plate 10A and the front edge section of the rear reinforcement 40 are joined together by spot welding. Referring to Fig. 2, Fig. 4 and Fig. 5, the inner lateral mounting flange 23 is sandwiched between a lower surface of a part along the inside in the vehicle width direction of an inner bead section 14a of the main floor plate 10A and an upper surface of the inner lateral flange 53 of the side element of the rear side element 50, and the three elements of the inner lateral mounting flange 23, the main floor plate 10A and the inner lateral flange 53 of the side element are joined together by spot welding.Furthermore, the vertical support wall 24 is sandwiched between an outer surface of the outer wall 15 of the main base plate 10A and an inner surface of the outer wall 54 of the rear side element 50, and the three elements of the vertical support wall 24, the outer wall 15 of the plate, and the outer wall 54 of the side element are joined together by spot welding. Additionally, in a front edge section of the rear reinforcement 40, the outer wall 15 of the plate is sandwiched between the vertical reinforcement wall 43 and the outer wall 54 of the side element, and the three elements of the front edge section of the vertical reinforcement wall 43, the rear edge section of the outer wall 15 of the plate, and the outer wall 54 of the side element are joined together by spot welding. The anchoring reinforcement 30 comprises an anchoring reinforcement main body 30A, which includes the seat belt anchorage attachment section 1C, and the thin, plate-shaped rear extension 30B, which extends rearward from a portion of the rear end of the anchoring reinforcement main body 30A. The anchoring reinforcement main body 30A occupies the majority of the anchoring reinforcement 30, and the rear extension 30B is a portion that forms a rear end section, which includes the rear end of the anchoring reinforcement 30. In the present embodiment, the anchor reinforcement main body 30A comprises a central bottom wall section 31, a curved section 32, an inner lateral flange 33 of the anchor reinforcement, an outer lateral flange 34 of the anchor reinforcement, and a vertical anchor reinforcement wall 35. In the illustrated example, each of the central bottom wall section 31, the curved section 32, the inner lateral flange 33 of the anchor reinforcement, and the outer lateral flange 34 of the anchor reinforcement is curved such that, in the top view as seen from above the vehicle, the rear section faces outwards in the vehicle width direction of the front section. The central floor wall section 31 extends in the front-rear direction of the vehicle in the central section in the vehicle width direction of the anchoring reinforcement main body 30A and is formed along the inclined section 11 of the main floor plate 10A and the upper surface of the front floor section 12. The bulging section 32 bulges forward toward the top of the vehicle and extends toward the front of the vehicle from the rear end of the anchoring reinforcement main body 30A. In the illustrated example, the bulging section 32 is provided along each of the outer part of the vehicle in the width and the inner part of the vehicle in the width of the central floor wall section 31. Therefore, in the illustrated example, the anchoring reinforcement main body 30A includes two bulging sections (32, 32). The two convex sections (32, 32) extend in the front-to-rear direction of the vehicle, while being spaced apart in the vehicle's width direction, and each convex section 32 curves towards the top of the vehicle. The inner convex section 32 extends such that it is continuous with the inner bead section 14a of the bead section 14 of the floor plate 10, and the outer convex section 32 extends such that it is continuous with an outer bead section 14b of the bead section 14 of the floor plate 10. In the illustrated example, the front seat mounting section 1B is provided in an upper wall of a front end section of the inner convex section 32. Additionally, the illustrated example provides the seat belt anchorage mounting section 1C in an upper wall of a rear end section of the outer convex section 32. The seatbelt anchorage mounting section 1C is formed as a horizontally extending upper wall of the arched section, which is shaped such that it arches slightly further upwards from an upper wall of the outer arched section 32. A bolt insertion hole 36, into which the anchorage mounting bolt B is inserted, is open in the seatbelt anchorage mounting section 1C. The anchorage mounting bolt B is inserted from above into a bolt insertion hole formed in the seatbelt anchorage S3 and the bolt insertion hole 36 of the seatbelt anchorage mounting section 1C, and screwed into the weld nut N on the lower surface of the seatbelt anchorage mounting section 1C. The seatbelt anchorage S3 is thus attached and fastened to the seatbelt anchorage mounting section 1C. The inner lateral flange 33 of the anchoring reinforcement extends in the vehicle width direction from the lower end of the vertical wall on the inside of the inner curved section 32 inwards and is joined to the upper surface of the main floor plate 10A. The inner lateral flange 33 of the anchoring reinforcement is arranged such that, viewed from above the vehicle, it is aligned with the inner lateral reinforcement flange 42 of the rear reinforcement 40, the inner lateral support flange 23 of the seat bracket 20, and the inner lateral flange 53 of the side element of the rear side element 50. The outer lateral flange 34 of the anchoring reinforcement extends outwards in the vehicle width direction from a portion of the outer edge section, across the vehicle width, of the anchoring reinforcement 30 on the vehicle front of the seatbelt anchorage mounting section 1C. In the illustrated example, the outer lateral flange 34 of the anchoring reinforcement extends outwards in the vehicle width direction from the lower end of a vertical wall on the outside, across the vehicle width, of the outwardly bulging central section 32 and joins with an outer edge section, across the vehicle width, of the upper surface of the principal points 10A. The vertical anchoring reinforcement wall 35 extends towards the top of the vehicle from a portion of the outer edge section of the anchoring reinforcement 30, corresponding to the seatbelt anchorage attachment section 1C, across the vehicle width. The vertical anchoring reinforcement wall 35 is joined by spot welding to an inner surface of the outer wall 15 of the main floor panel 10A and to an inner surface of the outer wall 54 of the rear side panel 50. The rear extension 30B forms the rear edge section of the anchoring reinforcement 30, is formed in a thin plate shape, and extends rearward from a portion of the rear end of the anchoring reinforcement main body 30A as described above. The rear extension 30B is therefore not formed across the entire width of the vehicle in the rear edge section of the anchoring reinforcement 30. The rear extension 30B is a portion that is narrower than the width of the entire rear section of the anchoring reinforcement main body 30A in the width of the vehicle and extends slightly toward the rear of the vehicle. Furthermore, the rear extension 30B lies between the seat belt anchorage mounting section 1C and the rear seat mounting section 1A in the front-to-rear direction of the vehicle and is joined to the floor plate 10 and the seat bracket 20.The rear extension 30B overlaps an upper surface of the inclined section 11 of the main base plate 10A in a position corresponding to the front edge section of the seat support 20, and the three elements of the front edge section of the seat support 20, the rear edge section of the anchoring reinforcement 30 and the main base plate 10A are joined together by spot welding. A spot weld 10 is provided in each of the inner end sections (vehicle width) and outer end sections of the rear extension 30B. In the illustrated example, the central section of the rear extension 30B curves in the vehicle width direction toward the top of the vehicle to be continuous with the outer curved section 32 of the anchoring reinforcement main body 30A. Both end sections (vehicle width) of the rear extension 30B curve rearward toward the side of the base plate 10 in a flange shape along the base plate 10 (see Fig. 6). A rear section of the vertical anchoring reinforcement wall 35 is connected to an outer end section (vehicle width) of the rear extension 30B. In the present embodiment of the rear section of the anchoring reinforcement main body 30A, a portion located inward in the vehicle width direction of the rear extension 30B is provided with a cutout 37 extending toward the front of the vehicle. The cutout 37 is formed such that it cuts out an inner portion in the vehicle width of the rear section of the central floor wall section 31, a rear portion of the bulging inner section 32, and a rear portion of the inner lateral flange 33 of the anchoring reinforcement in a rear section of the anchoring reinforcement main body 30A. Viewed from above the vehicle, a first edge section 37a forming the cutout 37 extends substantially in the vehicle width direction, and a second edge section 37b forming the cutout 37 extends substantially in the front-to-rear direction of the vehicle.The second edge section 37b is continuous with the inner edge section across the vehicle width of the rear extension 30B. Accordingly, the spot weld in the inner end section across the vehicle width of the rear extension 30B borders the second edge section 37b. An inner rear corner 38 of the anchoring reinforcement main body 30A, which adjoins the first edge section 37a forming the cutout 37 and extending in the vehicle width direction, is joined to the base plate 10 (main base plate 10A). In other words, the inner rear corner 38 is also a rear end section of the inner lateral flange 33 of the anchoring reinforcement of the anchoring reinforcement main body 30A. The inner rear corner 38 then adjoins the first edge section 37a of the cutout 37, which extends in the vehicle width direction. In other words, the rear edge of the inner lateral flange 33 of the anchoring reinforcement forms part of the first edge section 37a.Then, in the top view, as seen from above the vehicle, the cutout 37 lies between the inner rear corner 38 and the inner end section of the rear extension 30B, which are both joining elements (spot welds) of the base plate 10. In other words, the rear section of the anchoring reinforcement 30 is cut out at an inner point in the vehicle width, and spot welds are made on the base plate 10 on both sides in the vehicle width direction of the cutout 37. In the present embodiment, the inner rear corner 38 of the anchor reinforcement main body 30A, the base plate 10, and the crossbeam 70 are joined together. Referring to Fig. 6, the crossbeam 70 has a hat-shaped cross-section open to the top, and a front flange 71 and a rear flange 72 of the crossbeam 70 are both spot-welded to the lower surface of the inclined section 11 of the main base plate 10A. Then, referring to Fig. 4, the inner rear corner 38 of the anchor reinforcement main body 30A lies above the rear flange 72 of the crossbeam 70.Accordingly, the inclined section 11 of the main base plate 10A is sandwiched between the inner rear corner 38 of the anchoring reinforcement main body 30A and the rear flange 72 of the crossbeam 70, and the three elements of the inner rear corner 38, the inclined section 11, and the rear flange 72 are joined together by spot welding. The inner rear corner 38 is joined not only to the base plate 10 but also to the crossbeam 70. In the present embodiment, the seat belt anchorage mounting section 1C is provided in the rear section of the anchorage reinforcement main body 30A on the outside, in the vehicle width direction, of the second edge section 37b, which forms the cutout 37 and extends in the front-to-rear direction of the vehicle, and is adjacent to the rear extension 30B. In the illustrated example, on the upper wall of the outer convex section 32, which lies outside the second edge section 37b, the seat belt anchorage mounting section 1C is adjacent to the rear end of the convex section 32 and is continuous with the front end of the rear extension 30B. With respect to the rear seat mounting section 1A, the seat belt anchorage mounting section 1C is located on the outside, in the vehicle width direction, of the rear seat mounting section 1A. In the present embodiment, the rear seat mounting section 1A is oriented essentially outwards in the vehicle width direction of the second edge section 37b of the cutout 37 and inwards in the vehicle width direction of the seat belt anchorage mounting section 1C. In the illustrated example, the rear seat mounting section 1A is located at the rear of the vehicle of the rear extension 30B in the area across the vehicle width that corresponds to the central floor wall section 31 of the anchorage reinforcement main body 30A. As described above, the convex section 32 extends in the front-to-rear direction of the vehicle on both sides of the central floor wall section 31 of the anchoring reinforcement main body 30A. Then, in the present embodiment, with reference to Fig. 4, the convexity H of the convex section 32 decreases in the rear section of the convex section 32 towards the rear end of the anchoring reinforcement main body 30A.The arched section 32 extends in the front-to-rear direction of the vehicle along each of the central floor wall section 31, the inner lateral flange 33 of the anchoring reinforcement, and the outer lateral flange 34 of the anchoring reinforcement of the anchoring reinforcement main body 30A. Each of the central floor wall section 31, the inner lateral flange 33 of the anchoring reinforcement, and the outer lateral flange 34 of the anchoring reinforcement is formed to be inclined upwards towards the rear along the upper surface of the inclined section 11 of the main floor plate 10A. Consequently, the arch height H of the arched section 32 decreases towards the rear end of the anchoring reinforcement main body 30A according to the degree of inclination of the inclined section 11. The following describes the effect of the vehicle body underbody 1 according to the present embodiment at the time of a frontal collision or the like. As indicated by white arrows in Figs. 1, 3, and 6, at the time of a frontal collision or similar event, a tensile load acting forward and obliquely upwards is exerted on the rear seat mounting section 1A and the seat belt anchorage mounting section 1C. This tensile load also includes a force component directed inwards in the vehicle width direction within the seat belt anchorage mounting section 1C. Here, the mounting points of the seat S on the vehicle body substructure are widely separated by the longitudinal length of the seat rail S2 in the front-to-rear direction of the vehicle between the rear seat mounting section 1A and the front seat mounting section 1B, both of which are provided in the anchorage reinforcement 30. The seat belt anchorage mounting section 1C is positioned in front of and around the rear seat mounting section 1A.Accordingly, at the time of a frontal collision or the like, when a tensile load acts on the rear seat mounting section 1A and the seat belt anchorage mounting section 1C, which are located close to each other, the vehicle body substructure (floor plate 10, anchoring reinforcement 30 and the like) can enter a deformation mode in which the rear end section (rear seat mounting section 1A) of the seat rail S2 is lifted forward and obliquely upward with the front seat mounting section 1B as the starting point (center of rotation). To cope with the deformation mode that may occur in the vehicle body substructure 1 at the time of a frontal collision or the like, (1) the anchoring reinforcement 30, which includes the seat belt anchorage mounting section 1C, extends in the front-to-rear direction of the vehicle at the front of the rear seat mounting section 1A and is joined to the upper surface of the floor plate 10, and (2) the seat belt anchorage mounting section 1C is provided in the rear section of the anchoring reinforcement 30, and the anchoring reinforcement 30 includes the anchoring reinforcement main body 30A, which includes the seat belt anchorage mounting section 1C and the thin, plate-shaped rear extension 30B, which extends from a portion of the rear end of the anchoring reinforcement main body 30A. 30B,which extends between the seat belt anchorage mounting section 1C and the rear seat mounting section 1A in the front-rear direction of the vehicle and is joined to the seat bracket 20, which reinforces the rear seat mounting section 1A and the base plate 10, extending rearward. According to configurations (1) and (2) of the vehicle body substructure 1, the rear extension 30B of the anchoring reinforcement 30, which lies between the seat belt anchorage mounting section 1C and the rear seat mounting section 1A and is joined with the seat bracket 20 and the floor plate 10, does not extend over the entire vehicle width direction of the rear edge section of the anchoring reinforcement 30, but extends rearward from a part of the rear end of the anchoring reinforcement main body 30A such that the rear section of the anchoring reinforcement 30 is partially detached. Then the base plate 10 is connected between the seat belt anchorage mounting section 1C and the rear seat mounting section 1A with a part that is joined to the rear extension 30B and a part that is not joined to the rear extension 30B (i.e.a part adjacent to the rear extension 30B in the vehicle width direction) and a stiffness difference occurs between the part joined to the rear extension 30B and the part not joined to the rear extension 30B. Consequently, at the time of a frontal collision or the like, when a tensile force acts on the seat belt anchorage mounting section 1C, in the floor plate 10 between the seat belt anchorage mounting section 1C and the rear seat mounting section 1A, the part (the part adjacent to the rear extension 30B in the vehicle width direction) not joined to the rear extension 30B acts as a deformation origin point of the floor plate 10 and is readily deformed, and the impact due to the input load is readily absorbed by the deformation of the floor plate 10.Accordingly, even if the seat belt anchorage mounting section 1C and the rear seat mounting section 1A are positioned close to each other, in the deformation mode the deformation of the anchorage reinforcement 30 and the like is significantly reduced, and detachment or the like of weld points of the anchorage reinforcement 30, including the seat belt anchorage mounting section 1C on the base plate 10, is effectively prevented. As described above, the vehicle body substructure 1 according to the present embodiment includes a structure that can reduce the effect of an input load in an assembled state of the seat belt anchorage mounting section 1C even when the seat belt anchorage mounting section 1C and the rear seat mounting section 1A are positioned close to each other. In the present embodiment, the portion of the rear section of the anchoring reinforcement main body 30A that faces inwards in the vehicle width direction of the rear extension 30B is provided with a cutout 37 that extends towards the front of the vehicle, and the inner rear corner 38 of the anchoring reinforcement main body 30A, which adjoins the first edge section 37a forming the cutout 37 and extending in the vehicle width direction, is joined to the base plate 10. As a result, compared to a case where the cutout 37 is not formed, it is possible to locally reduce the base stiffness of the portion of the base plate 10 that extends inwards in the vehicle width direction of the rear extension 30B.Accordingly, in the section extending inwards in the vehicle width direction of the rear extension 30B, upward deformation of the base plate 10 is more easily promoted, and the impact due to an input load is more readily absorbed by the deformation of the base plate 10. As a result, detachment or similar issues with the welds of the anchoring reinforcement 30 on the base plate 10 can be more effectively prevented. In the present embodiment, the vehicle body substructure 1 includes the cross member 70, which is provided beneath the floor panel 10 and extends in the vehicle width direction in a position corresponding to the seat belt anchorage mounting section 1C in the front-to-rear direction of the vehicle, with the cross member 70 being joined to the floor panel 10. The inner rear corner 38 of the anchorage reinforcement main body 30A, the floor panel 10, and the cross member 70 are joined together. As a result, deformation of the floor panel 10 is more strongly promoted in a portion that lies inward in the vehicle width direction of the rear extension 30B, and in a portion of the floor panel 10 that lies at the rear of the vehicle at the inner rear corner 38. Accordingly, delamination or similar issues with the welds of the anchorage reinforcement 30 on the floor panel 10 can be more effectively prevented. In the present embodiment, the seat belt anchorage fastening section 1C is provided in the rear section of the anchorage reinforcement main body 30A outwards in the vehicle width direction of the second edge section 37b, which forms the cutout 37 and extends in the front-rear direction of the vehicle, and borders the rear extension 30B.Since the tensile load in the frontal direction and obliquely upwards, which acts inwards in the vehicle width direction on the seat belt anchorage mounting section 1C at the time of a frontal collision or the like, orienting the seat belt anchorage mounting section 1C outwards in the vehicle width direction of the cutout 37 and adjacent to the rear extension 30B promotes the deformation of the base plate 10 inwards in the vehicle width direction and towards the front of the vehicle with the cutout 37 as a starting point more effectively, and the detachment or the like of the weld joint can be more effectively prevented. In the present embodiment, the rear seat mounting section 1A is positioned essentially outwards in the vehicle width direction of the second edge section 37b of the cutout 37 and inwards in the vehicle width direction of the seat belt anchorage mounting section 1C. As a result, the seat belt anchorage mounting section 1C and the rear seat mounting section 1A are displaced in the vehicle width direction, and the point of application of the tensile load is also displaced in the vehicle width direction, thereby promoting lateral deformation of the base plate 10 and potentially three-dimensional deformation. Consequently, delamination or similar issues at the weld joint can be more effectively prevented. In the present embodiment, the anchoring reinforcement main body 30A includes the convex section 32, which convexes towards the upper surface of the vehicle and extends towards the front of the vehicle from the rear end of the anchoring reinforcement main body, and the convexity H of the convex section 32 decreases towards the rear end of the anchoring reinforcement main body 30A in the rear section of the convex section 32. Accordingly, the vertical stiffness of the rear section of the anchoring reinforcement main body 30A decreases towards the rear end of the anchoring reinforcement main body 30A according to the convexity H of the convex section 32.As a result, in the event of a frontal collision or the like, the rear section of the anchoring reinforcement 30 can be deformed to a certain extent, whereby the impact due to an input load is also absorbed by the deformation of the anchoring reinforcement 30, and detachment or the like of the weld joint of the anchoring reinforcement 30 can be very effectively prevented. [List of reference symbols] 1 Vehicle body underbody 1A Rear seat mounting section 1C Seat belt anchorage mounting section 10 Floor plate 20 Seat bracket 30 Anchorage reinforcement 30A Anchorage reinforcement main body 30B Rear extension 32 Curved section 37 Cutout 37a First edge section 37b Second edge section 38 Inner rear corner 40 Rear reinforcement 50 Rear side element 60 Side sill 70 Crossmember S Seat S3 Seat belt anchorage H Curvature height

Claims

Vehicle body underbody (1) comprising a floor plate (10) provided in a lower vehicle body section and including a rear seat mounting section (1A), and a seat bracket (20) for reinforcing the rear seat mounting section (1A), a seat belt anchorage mounting section (1C) provided in the lower vehicle body section at a vehicle front of the rear seat mounting section (1A) and around the rear seat mounting section (1A), characterized in that: the vehicle body underbody (1) comprises an anchorage reinforcement (30) extending in a front-rear direction of the vehicle at the vehicle front of the rear seat mounting section (1A) which includes the seat belt anchorage mounting section (1C), and which is joined to an upper surface of the floor plate (10);the seat belt anchorage mounting section (1C) is provided on a rear section of the anchorage reinforcement (30); and the anchorage reinforcement (30) comprises an anchorage reinforcement main body (30A) which includes the seat belt anchorage mounting section (1C), and a thin plate-shaped rear extension (30B) extending rearward from a portion of a rear end of the anchorage reinforcement main body (30A), the rear extension (30B) extending between the seat belt anchorage mounting section (1C) and the rear seat mounting section (1A) in the front-to-rear direction of the vehicle and joined with the floor plate (10) and the seat mount (20). Vehicle body underbody (1) according to claim 1, wherein a portion of a rear section of the anchoring reinforcement main body (30A) which lies inwards in a vehicle direction of the rear extension (30B) is provided with a cutout (37) which is cut out in the direction of the vehicle front, and an inner rear corner (38) of the anchoring reinforcement main body (30A) which adjoins the first edge section (37a) which forms the cutout (37) and extends in the vehicle width direction is joined to the base plate (10). Vehicle body underbody (1) according to claim 2, comprising a cross member (70) provided below the floor plate (10) and extending in the vehicle width direction in a position corresponding to the seat belt anchorage attachment section (1C) in the front-rear direction of the vehicle, wherein the cross member (70) is joined to the floor plate (10), wherein the inner rear corner (38) of the anchorage reinforcement main body (30A), the floor plate (10) and the cross member (70) are joined together. Vehicle body underbody (1) according to claim 2, wherein the seat belt anchorage fastening section (1C) is provided in the rear section of the anchorage reinforcement main body (30A) outwards in the vehicle width direction of a second edge section (37b) which forms the cutout (37) and extends in the front-rear direction of the vehicle and adjoins the rear extension (30B). Vehicle body underbody (1) according to claim 4, wherein the rear seat mounting section (1A) is arranged on the rear of the vehicle of the second edge section (37b) and inwards in the vehicle width direction from the seat belt anchoring mounting section (1C). Vehicle body underbody (1) according to one of claims 1 to 5, wherein the anchoring reinforcement main body (30A) includes a curved section (32) that curves towards a vehicle top and extends to the vehicle front from a rear end of the anchoring reinforcement main body (30A), and a curvature height (H) of the curved section (32) decreases towards the rear end of the anchoring reinforcement main body (30A) in a rear section of the curved section (32).

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