JP7213292B2 - rear body structure - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear body structure of a vehicle.

2. Description of the Related Art As a vehicle body rear portion structure of a vehicle, there is one that includes a pair of rear side frames extending substantially along the vehicle front-rear direction. In a vehicle provided with a rear side frame, it is desired that the rear side frame can sufficiently absorb the energy of the impact load when the impact load is input from behind the rear side frame.
Various vehicle body rear structures that meet this demand have been devised in the past (see, for example, Patent Document 1).

In the vehicle body rear structure described in Patent Document 1, a rear side frame extending substantially along the vehicle front-rear direction is provided with a front side bending promoting portion, an intermediate bending promoting portion, and a rear side bending promoting portion. In this vehicle body rear structure , the deformation behavior of the rear side frame when an impact load is input is controlled by a plurality of bending promoting portions, thereby efficiently absorbing the energy of the impact load.

Japanese Patent No. 6098622

BACKGROUND ART As a vehicle body structure, a structure in which highly rigid subframes for supporting suspension parts and the like are installed on left and right rear side frames is known. In such a rear vehicle body structure , the deformation stroke of the rear side frame is restricted by the subframe, making it difficult to sufficiently absorb the energy of the impact load.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicle rear portion structure capable of sufficiently absorbing the energy of an impact load even with a structure in which subframes are installed on rear side frames.

In order to solve the above problems, the vehicle body rear portion structure according to the present application employs the following configuration.
That is, the vehicle body rear portion structure according to one aspect of the invention of the present application includes a pair of left and right rear side frames (for example, the rear side frames 10 of the embodiment) extending substantially along the longitudinal direction of the vehicle body, and a vehicle-mounted structure that is mounted on the pair of the rear side frames. a sub-frame (for example, the sub-frame 15 of the embodiment) that supports a component, and the sub-frame is a substantially U-shaped side member whose front and rear ends are coupled to the corresponding left and right rear side frames. (For example, the side members 16 of the embodiment) are provided on the left and right sides, and each of the rear side frames has a fragile portion (for example, the fragile portion 23 of the embodiment) that is weaker than other front and rear portions. The side member has a rear end portion coupled to a rear connection point (for example, the rear connection point 10r in the embodiment) provided in the fragile portion of the rear side frame, and a front end portion connected to the rear side frame. Each of the rear side frames is connected to a front connection point (for example, a front connection point 10f in the embodiment) provided in a non-weakened portion (for example, the non-weakened portion 24 in the embodiment) located on the front side of the weakened portion. A bending deformation starting point (for example, a bending deformation starting point S in the embodiment) is arranged between the front connection point and the rear connection point, and the body portion of the rear side frame is located between the front connection point and the rear connection point. is reinforced by a first reinforcing member (for example, the first reinforcing plate 21 of the embodiment) and a second reinforcing member (for example, the second reinforcing plate 22 of the embodiment) having higher rigidity than the first reinforcing member. , the first reinforcing member is arranged on the rear side of the second reinforcing member so that the front edge overlaps the rear edge of the second reinforcing member, and the rear end of the second reinforcing member and the second reinforcing member A boundary (for example, a boundary 25 in the embodiment) of the overlapping portion of one reinforcing member constitutes the starting point of bending deformation .

With the above configuration, when an impact load is input from behind the rear side frame, the fragile portion of the rear side frame first starts to deform, and the rear end of the side member of the subframe is pushed forward through the rear connection point. . When the rear end portion of the side member is pushed forward, the substantially U-shaped side member starts to deform between the front connection point and the rear connection point. After that, when the rear side frame starts to bend around the starting point of bending deformation, the side member continues to deform further. As a result, the impact load input from the rear side of the rear side frame is absorbed by the deformation of the side members of the sub-frame and the deformation of the vicinity of the sub-frame mounting portion on the rear side frame.

In this case, the portion between the front connection point and the rear connection point of the body portion of the rear side frame is reinforced by the first reinforcing member and the second reinforcing member. Thus, the boundary of the overlapping portion on the first reinforcing member where the rear end portion of the highly rigid second reinforcing member is overlapped has a sharp drop in strength compared to the front side portion where the second reinforcing member overlaps. Therefore, when an impact load is input from the rear side of the rear side frame, the boundary becomes a starting point of bending deformation, and the bending deformation of the rear side frame is accelerated. Therefore, when this configuration is adopted, it is possible to easily form the starting point of bending deformation on the rear side frame. can be easily changed.

The first reinforcing member and the second reinforcing member are plate-shaped members that are joined to the bottom wall (for example, the bottom wall 10b in the embodiment) and the side wall (for example, the side wall 10s in the embodiment) of the rear side frame. A portion of the first reinforcing member where the end portion of the second reinforcing member overlaps may be arranged along the bottom wall and the side wall of the rear side frame.

In this case, the boundary between the portion of the first reinforcing member that overlaps with the second reinforcing member and the portion that does not overlap (boundary of strength change) extends continuously along the bottom wall and side wall of the rear side frame. become. Therefore, when an impact load is input from behind the rear side frames, the rear side frames are more likely to be bent and deformed at the boundary extending three-dimensionally.

A vehicle rear portion structure according to another invention of the present application includes a pair of left and right rear side frames (for example, the rear side frames 10 of the embodiment) extending substantially along the longitudinal direction of the vehicle body, and an on-vehicle component installed on the pair of the rear side frames. and a supporting subframe (for example, the subframe 15 of the embodiment), and the subframe has a substantially U-shaped side member (for example, a , and a pair of side members 16 of the embodiment) on the left and right, each of the rear side frames having a fragile portion (for example, the fragile portion 23 of the embodiment) that is weaker than other front and rear portions, and each of the side members The member has a rear end portion coupled to a rear connection point (for example, a rear connection point 10r in the embodiment) provided at the weakened portion of the rear side frame, and a front end portion connected to the weakened portion of the rear side frame. is connected to a front connection point (for example, a front connection point 10f in the embodiment) provided in a non-weakened portion (for example, the non-weakened portion 24 in the embodiment) located on the front side of the rear side frame, and each of the rear side frames is connected to the front connection A bending deformation starting point (for example, the bending deformation starting point S in the embodiment) is arranged between the point and the rear connection point, and the subframe extends in the vehicle width direction and connects the pair of side members (for example, a cross beam). The front cross beam 17) of the embodiment is provided, and the bending deformation starting point is arranged in the vicinity of the extension position of the cross beam in the longitudinal direction of the vehicle body .

In this case, when an impact load is input, the rear side frame is bent and deformed with the vicinity of the extension position of the cross beam as a fulcrum. As a result, the side members of the sub-frames provided side by side with the rear side frames are likely to be bent and deformed in the vicinity of the joints with the cross beams. Therefore, when this configuration is adopted, it is possible to increase the deformation stroke of the sub-frame and the rear side frame when an impact load is applied.

The rear side frame may have an upper inclined portion (for example, the upper inclined portion 30 in the embodiment) that inclines upward toward the front of the vehicle body on the rear side of the rear connection point.

In this case, when an impact load is input from the rear side of the rear side frame, a moment acts on the rear side frame in a direction to push up the starting point of bending deformation of the rear side frame. As a result, the rear side frame is deformed into a mountain-fold shape starting from the folding deformation starting point. As a result, it is possible to prevent the rear side frames from interfering with vehicle body parts located inside the rear side frames in the vehicle width direction.

A bead portion (for example, the bead portion 35 of the embodiment) recessed toward the inside of the cross section of the rear side frame is provided at the upper inclined portion of the rear side frame or at the rear side of the upper inclined portion. You can do it.

In this case, when an impact load is input from behind the rear side frame, the rear region of the rear side frame is likely to be crushed and deformed due to the function of promoting crushing by the bead portion. Therefore, when an impact load is input, the energy of the impact load can be sufficiently absorbed by the crushing deformation of the rear region of the rear side frame and the deformation of the sub-frame accompanying the mountain-fold bending of the rear side frame.

The rear side frame may be composed of a high-strength plate, and the weakened portion (for example, a hole or notch in the embodiment) may be arranged in a portion of the high-strength plate.

In this case, by providing a weakened portion such as a hole or a notch in a portion of the high-strength plate, the weakened portion can be provided in a portion of the rear side frame. Therefore, the weight of the rear side frame can be reduced by forming the rear side frame from a high-strength steel plate or the like.

The vehicle body rear structure according to the present invention absorbs the energy of the impact load by deformation of the subframe and deformation of the vicinity of the subframe mounting portion on the rear side frame when the impact load is input from behind the rear side frame. can be done. Therefore, when the vehicle body rear portion structure according to the present invention is employed, the energy of the impact load is sufficiently absorbed in the vicinity of the sub-frame mounting portion on the rear side frame even in the structure where the sub-frame is installed on the rear side frame. can do.

FIG. 2 is a bottom view of the rear portion of the vehicle of the embodiment; The perspective view which looked at the rear part of the vehicle of embodiment from the downward direction. FIG. 2 is a side view of the lower frame portion of the rear portion of the vehicle of the embodiment; FIG. 2 is a top view of the lower frame portion of the rear portion of the vehicle of the embodiment; FIG. 2 is a perspective view of the lower frame portion of the rear portion of the vehicle of the embodiment as viewed from above; FIG. 5 is a partially cross-sectional perspective view of the lower frame portion of the rear portion of the vehicle including the VI-VI cross section of FIG. 4; FIG. 4 is a top view of the rear portion of the rear side frame of the embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In the following description, front and rear, up and down, and left and right refer to the forward direction of the vehicle unless otherwise specified. In addition, an arrow FR pointing to the front of the vehicle, an arrow UP pointing to the upper side of the vehicle, and an arrow LH pointing to the left side of the vehicle are shown at appropriate locations in the drawing.

FIG. 1 is a bottom view of the rear part of the vehicle 1 of this embodiment, and FIG. 2 is a perspective view of the rear part of the vehicle 1 as seen from the lower right side. FIG. 3 is a side view of the lower frame portion of the rear portion of the vehicle 1. As shown in FIG.
Reference numeral 10 in the drawing denotes a pair of left and right rear side frames extending substantially along the front-rear direction at the rear portion of the vehicle 1 . A front end portion of each rear side frame 10 is connected to the rear portion of the corresponding left and right side sills 11 . A rear floor panel 12 and a rear floor pan 13 are joined to the left and right rear side frames 10 . A front floor panel 14 is joined to the left and right side sills 11 .
Further, reference numeral Wr in the drawing denotes a rear wheel of the vehicle, and reference numeral 2 denotes a rear wheel house that covers the outside of the rear wheel Wr.

Subframes 15 for supporting left and right suspension parts (in-vehicle parts) (not shown) are provided on the lower surfaces of the bottom walls 10b of the left and right rear side frames 10, respectively. The sub-frame 15 includes a pair of left and right side members 16 whose front and rear ends are coupled to the lower surfaces of the corresponding left and right rear side frames 10, a front cross beam 17 connecting intermediate regions of the left and right side members 16, and a A rear cross beam 18 is provided.

Each side member 16 of the sub-frame 15 has a substantially U-shaped overall shape. The side members 16 are coupled to the corresponding rear side frames 10 so that the center region thereof is recessed inward in the vehicle width direction when viewed from the bottom of the vehicle. The curved central region of each side member 16 is located inside the corresponding rear side frame 10 in the vehicle width direction in this state. Front and rear end portions of the side member 16 are formed into a front joint portion 16f and a rear joint portion 16r which are joined to the lower surfaces of the corresponding left and right rear side frames 10, respectively. The front joint portion 16f and the rear joint portion 16r are fixed to the lower surface of the rear side frame 10 by bolting.

The front coupling portion 16f of each side member 16 is fixed in the vicinity of the connection portion with the side sill 11 on the front side of the rear wheel Wr of the corresponding rear side frame 10. As shown in FIG. On the other hand, the rear coupling portion 16r of each side member 16 is fixed at a position on the rear side of the rear wheel Wr of the corresponding rear side frame 10. As shown in FIG.

The front regions of the left and right rear side frames 10 (the vicinity of the front connection point 10f to which the front connection portion 16f is connected) extend along the vehicle width direction and are joined to the lower surface of the rear floor panel 12 by an under-floor cross member 19l. and an upper floor cross member 19 u that extends along the vehicle width direction and is joined to the upper surface of the rear floor panel 12 . Further, the rear connection points 10r of the left and right rear side frames 10 to which the rear joint portions 16r are joined are connected together with the rear joint portions 16r of the left and right side members 16 by a connecting rod 20. As shown in FIG.

Also, the front cross beam 17 of the subframe 15 connects the curved tops of the left and right side members 16, that is, the areas where the left and right side members 16 are closest to each other. The rear cross beam 18 connects the left and right side members 16 on the front side of the front cross beam 17 . The front cross beam 17 is set to have a higher bending rigidity than the rear cross beam 18 .

The detailed structure of the rear side frame 10 will be described below. Hereinafter, of the rear side frame 10 shown in FIG. The front side of the area Ar" is referred to as a " front area Af ".

FIG. 4 is a top view of the front area Af of the left rear side frame 10, and FIG. 5 is a perspective view of the front area Af of the same left rear side frame 10 viewed from above the right rear. 6 is a partial sectional perspective view of the left rear side frame 10 including the VI-VI section of FIG. The right rear side frame 10 has the same structure as the left rear side frame 10 .
A main body portion 10A (see FIG. 6) of the rear side frame 10 includes a bottom wall 10b and a pair of side walls 10s rising upward from both left and right ends of the bottom wall 10b. A main body portion 10A of the rear side frame 10 is formed to have a substantially U-shaped cross section opening upward.

In the front region Af of the rear side frame 10, a first reinforcing plate 21 (first reinforcing member) made of metal and a second reinforcing plate 22 made of metal having higher rigidity than the first reinforcing plate 21 are provided inside the main body portion 10A. (Second reinforcing member) is joined. The first reinforcing plate 21 and the second reinforcing plate 22 each include bottom wall portions 21b and 22b along the bottom wall 10b of the main body portion 10A, and side walls along the left and right side walls 10s of the main body portion 10A and shorter than the side walls 10s. It has parts 21s and 22s. The first reinforcing plate 21 and the second reinforcing plate 22 are arranged in a region between the front connection point 10f and the rear connection point 10r to which the corresponding left and right side members 16 of the main body portion 10A are connected.

The front edge of the first reinforcing plate 21 overlaps the upper surface of the rear edge of the second reinforcing plate 22, and in this state, the first reinforcing plate 21 is joined to the inner surface of the main body 10A. In the front region Af of the rear side frame 10, a difference in rigidity (difference in brittleness) is created for each region in the front-rear direction by a reinforcing plate joined to the main body portion 10A. That is, the rear side frame 10 has the lowest rigidity (crushing resistance) in the region where the first reinforcing plate 21 is arranged alone, and the rigidity in the region where the second reinforcing plate 22 is arranged is relatively high. there is The rigidity of the portion where the first reinforcing plate 21 and the second reinforcing plate 22 overlap is the highest.

In the present embodiment, the region of the rear side frame 10 where the first reinforcing plate 21 is arranged alone is the weakened portion 23, and the front side of the region where the first reinforcing plate 21 is arranged alone is non-weak. 24. A rear connection point 10r to which the rear connection portion 16r of the side member 16 is connected is arranged at the fragile portion 23 of the rear side frame 10. As shown in FIG. A front connecting point 10 f to which the front connecting portion 16 f of the side member 16 is connected is arranged at the non-weakened portion 24 on the front side of the weakened portion 23 of the rear side frame 10 .

In addition, since the boundary 25 of the overlapping portion between the rear end portion of the second reinforcing plate 22 and the first reinforcing plate 21 is the boundary between the portion with the highest rigidity and the portion with the lowest rigidity, when an external force acts, It becomes the starting point of deformation. In the present embodiment, the portion where this boundary 25 is arranged is the bending deformation starting point S between the front connection point 10f and the rear connection point 10r of the rear side frame 10. As shown in FIG. Therefore, in this configuration, the front connection point 10f is arranged at the weak portion 23 on the rear side frame 10, and the rear connection point 10r is arranged at the non-weak portion 24, so that the front connection point 10f and the rear connection point of the rear side frame 10 are arranged. A bending deformation starting point S is arranged between 10r.
In this embodiment, the bottom wall portions 21b and 22b and the side wall portions 21s and 22s of the first reinforcing plate 21 and the second reinforcing plate 22 are aligned with the bottom wall 10b and the side wall 10s of the main body portion 10A of the rear side frame 10. are placed in Therefore, the boundary 25 between the first reinforcing plate 21 and the second reinforcing plate 22, which is the bending deformation starting point S, is arranged along the bottom wall 10b and the side wall 10s of the main body 10A.

Here, as shown in FIGS. 1 to 3, the bending deformation starting point S on the rear side frame 10 is arranged near the vehicle body front-to-rear position where the rear cross beam 18 of the sub-frame 15 extends.

At least a part of the rear area Ar of the rear side frame 10 (the area on the rear side of the rear connection point 10r) is inclined upward toward the front side of the vehicle body, as shown in FIG. That is, the rear side frame 10 is provided with an upper inclined portion 30 that is inclined upward toward the front of the vehicle body on the rear side of the rear connection point 10r.

Further, in the rear region Ar of the rear side frame 10, the upper inclined portion 30 or the side wall 10s on the rear side of the upper inclined portion has a plurality of bead portions recessed toward the inside of the cross section of the rear side frame 10. 35 is provided. These bead portions 35 function to promote crushing deformation of the rear region Ar when an impact load is input from behind the rear side frame 10 .

In the above configuration, when an impact load is input from behind the rear side frame 10, first, the rear region Ar of the rear side frame 10 is crushed, and the fragile portion 23 of the front region Af starts crushing deformation. As a result, the rear end portion of the side member 16 of the subframe 15 coupled to the rear connection point 10r of the fragile portion 23 is pushed forward through the rear connection point 10r. When the rear end portion of the side member 16 is thus pushed forward, the substantially U-shaped side member 16 starts to deform between the front connection point 10f and the rear connection point 10r.

As the impact load continues to be input, the front region Af of the rear side frame 10 starts to bend around the starting point S of bending deformation, and along with this, the side member 16 continues to deform further. As a result, the impact load input from the rear side of the rear side frame 10 is absorbed by the deformation of the side member 16 of the sub-frame 15 and the deformation of the vicinity of the sub-frame mounting portion on the rear side frame 10 .

When an impact load is input from the rear side of the rear side frame 10, the vehicle body rear structure of the present embodiment is affected by the deformation of the side member 16 of the sub-frame 15 and the deformation of the vicinity of the sub-frame mounting portion on the rear side frame 10. It can absorb the energy of the load. Therefore, when the vehicle body rear portion structure of the present embodiment is employed, even in the structure in which the sub-frame 15 is installed on the rear side frame 10, the energy of the impact load is absorbed in the vicinity of the sub-frame mounting portion on the rear side frame 10. can be fully absorbed.

In addition, in the vehicle body rear structure of this embodiment, the portion between the front connection point 10f and the rear connection point 10r of the main body portion 10A of the rear side frame 10 is reinforced by the first reinforcing plate 21 and the second reinforcing plate 22, and is arranged forward. The second reinforcing plate 22 on the rear side has higher rigidity than the first reinforcing plate 21 on the rear side. The front edge of the first reinforcing plate 21 overlaps the rear edge of the second reinforcing plate 22 , and the boundary 25 between the rear edge of the second reinforcing plate 22 and the overlapping portion of the first reinforcing plate 21 is the rear side frame 10 . constitutes the starting point of folding deformation. In this configuration, the first reinforcing plate 21 and the second plate 22 can reinforce the space between the front connecting point 10f and the rear connecting point 10r of the rear side frame 10, and the boundary 25 between the first reinforcing plate 21 and the second plate 22 can provide The bending deformation starting point S can be easily formed. That is, the boundary 25 of the overlapping portion on the first reinforcing plate 21 on which the rear end portion of the second reinforcing plate 22 having high rigidity is overlapped sharply increases in strength with respect to the portion on the front side where the second reinforcing plate 22 overlaps on the surface. decreases, it functions as a bending deformation starting point S when an impact load is input.
Further, when this configuration is adopted, the position of the bending deformation starting point S can be easily changed to any position by changing the overlapping position of the first reinforcing plate 21 and the second reinforcing plate 22 .

Further, in the vehicle body rear portion structure of the present embodiment, a boundary 25 where the rear end portion of the second reinforcing plate 22 overlaps on the first reinforcing plate 21 is arranged along the bottom wall 10b and the side wall 10s of the rear side frame 10. . Therefore, the portion (boundary 25) where the strength of the reinforcing plate abruptly changes extends continuously along the bottom wall 10b and the side wall 10s of the rear side frame 10. As shown in FIG. Therefore, when this configuration is adopted, the rear side frame 10 is more likely to be bent and deformed at the boundaries 25 extending in three dimensions when an impact load is applied.

Further, in the vehicle body rear portion structure of the present embodiment, the bending deformation starting point S on the rear side frame 10 is arranged near the extension position of the front cross beam 17 of the sub-frame 15 . Therefore, when an impact load is input from the rear side of the rear side frame 10, the rear side frame 10 bends around the extension position of the front cross beam 17 as a fulcrum. As a result, the side members 16 of the sub-frames 15 arranged side by side with the rear side frames 10 are likely to be bent and deformed in the vicinity of the connecting portion with the front cross beam 17 . Therefore, when this configuration is adopted, the deformation stroke of the sub-frame 15 and the rear side frame 10 can be increased when an impact load is applied.

Further, in the vehicle body rear portion structure of the present embodiment, an upper inclined portion 30 is provided in the rear region Ar of the rear side frame 10 . Therefore, when an impact load is input from the rear side of the rear side frame 10, a moment acts on the rear side frame 10 in a direction to push up the bending deformation starting point S of the rear side frame 10, and the rear side frame 10 moves from the bending deformation starting point S as a starting point. Then, it will be deformed into a mountain fold shape. Therefore, when this configuration is adopted, it is possible to prevent the rear side frames 10 from interfering with vehicle body parts located inside the rear side frames 10 in the vehicle width direction when an impact load is applied.

Further, in the vehicle body rear portion structure of the present embodiment, a bead portion 35 recessed toward the inside of the cross section of the rear side frame 10 is provided in the rear region Ar of the rear side frame 10 . Therefore, when an impact load is input from the rear side of the rear side frame 10, the bead portion 35 can smoothly crush and deform the rear region Ar of the rear side frame 10 due to the function of promoting crushing. Therefore, when this configuration is adopted, deformation of the sub-frame 15 accompanied by crushing deformation of the rear region Ar of the rear side frame 10 and mountain-fold bending of the front region Af of the rear side frame 10 when an impact load is applied. can sufficiently absorb the energy of the impact load.

<Other embodiments>
In the above embodiment, the rear side frame is not made of a special high-strength plate material such as a high-strength steel plate. However, by forming the rear side frame from a high-strength plate such as a high-strength steel plate and providing a weakened portion such as a hole or notch in a portion of the high-strength plate, it is possible to provide a weak portion in a portion of the rear side frame. be. In this case, the weakened portion provided with the weakened portion is provided with a rear connection point for connecting the rear portion of the side member.
Also in this case, if a bending deformation starting point is provided between the front connecting point and the rear connecting point on the rear side frame, the same effect as the above embodiment can be obtained.

The present invention is not limited to the above-described embodiments, and various design changes are possible without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10... Rear side frame 10b... Bottom wall 10... Side wall 10A... Main-body part 10f... Front connection point 10r... Rear connection point 10b... Bottom wall 10s... Side wall 15... Sub-frame 16... Side member 17... Front cross beam (cross beam)
21... First reinforcing plate (first reinforcing member)
22... Second reinforcing plate (second reinforcing member)
23... Weak part 24... Non-weak part 25... Boundary 30... Upper inclined part 35... Bead part S... Starting point of bending deformation

Claims (6)

a pair of left and right rear side frames extending substantially along the longitudinal direction of the vehicle body;
a sub-frame that is mounted on the pair of rear side frames and supports an in-vehicle component,
The sub-frame has a pair of substantially U-shaped side members on the left and right, the front and rear ends of which are coupled to the corresponding left and right rear side frames,
Each of the rear side frames has a fragile portion that is weaker than other front and rear portions,
Each of the side members has a rear end coupled to a rear connection point provided in the weakened portion of the rear side frame, and a front end of the side member that is a non-weakened portion located in front of the weakened portion of the rear side frame. is connected to the front connection point provided in the
Each of the rear side frames has a bending deformation starting point arranged between the front connection point and the rear connection point ,
A portion between the front connection point and the rear connection point of the body portion of the rear side frame is reinforced by a first reinforcing member and a second reinforcing member having higher rigidity than the first reinforcing member,
The first reinforcing member is arranged on the rear side of the second reinforcing member such that the front edge overlaps the rear edge of the second reinforcing member,
The vehicle body rear portion structure , wherein a boundary between a rear end portion of the second reinforcing member and an overlapping portion of the first reinforcing member constitutes the starting point of bending deformation . The first reinforcing member and the second reinforcing member are plate-like members joined to the bottom wall and side wall of the rear side frame,
2. The rear portion of the vehicle body according to claim 1 , wherein a portion of the first reinforcing member where the end portion of the second reinforcing member overlaps is arranged along the bottom wall and the side wall of the rear side frame. structure. a pair of left and right rear side frames extending substantially along the longitudinal direction of the vehicle body;
a sub-frame that is mounted on the pair of rear side frames and supports an in-vehicle component,
The sub-frame has a pair of substantially U-shaped side members on the left and right, the front and rear ends of which are coupled to the corresponding left and right rear side frames,
Each of the rear side frames has a fragile portion that is weaker than other front and rear portions,
Each of the side members has a rear end coupled to a rear connection point provided in the weakened portion of the rear side frame, and a front end of the side member that is a non-weakened portion located in front of the weakened portion of the rear side frame. is connected to the front connection point provided in the
Each of the rear side frames has a bending deformation starting point arranged between the front connection point and the rear connection point,
The subframe includes a cross beam extending in the vehicle width direction and connecting the pair of side members,
The vehicle body rear portion structure, wherein the bending deformation starting point is arranged in the vicinity of the extension position of the cross beam in the vehicle longitudinal direction. 4. The rear vehicle body structure according to claim 1 , wherein the rear side frame has an upper inclined portion that is inclined upward toward the front of the vehicle body on the rear side of the rear connection point. . 5. A bead portion recessed toward the inside of the cross section of the rear side frame is provided at the upper inclined portion of the rear side frame or at the rear side of the upper inclined portion. Body rear structure as described. The rear side frame is composed of a high-strength plate,
The vehicle body rear portion structure according to any one of claims 1 to 5 , wherein the weakened portion is configured by arranging a weakened portion on a portion of the high-strength plate.

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