Vehicular rear frame

Abstract

To provide a vehicular rear frame that can be easily manufactured by a casting method and can prevent electrophoretic coating liquid from pooling.SOLUTION: A vehicular rear frame according to the present invention comprises a pair of side parts arranged separately along a vehicle width direction, a first cross part connecting the front portions of the pair of side parts, and a second cross part connecting the rear portions of the pair of side parts, where the pair of side parts, the first cross part and the second cross part form a single unit. Each of the side parts has: a front mounting seating surface on which a front mount of a rear sub frame is mounted, a front depression structure formed on the front mounting seating surface, a rear mounting seating surface on which a rear mount of the rear sub frame is mounted, and a rear depression structure formed on the rear mounting seating surface. The front depression structure is formed in a pocket shape whose upper part is opened and has a through-hole, and the rear depression structure is formed in a pocket shape whose upper part is opened and has a through-hole.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a rear frame for a vehicle, and more particularly, to a rear frame for a vehicle that is easy to manufacture by a casting method and can prevent the accumulation of electrodeposition coating liquid.

Background Art

[0002] In recent years, as the awareness of the crisis regarding the environment and the depletion of oil resources has increased, eco-cars such as electric vehicles (EVs) and hybrid electric vehicles (HEVs) have attracted attention.

[0003] Since electric vehicles have relatively heavy batteries and power electronics modules (PE modules), etc., their weight increases relatively. Along with this, electric vehicles have the opposite problems that their collision energy increases while the collision energy absorption space relatively shrinks. To solve this, electric vehicles need to increase the robustness of the vehicle body by integrating the connection structure of the load path and realize cost reduction and simplification of the assembly structure by minimizing the number of parts.

[0004] For weight reduction and rigidity enhancement of electric vehicles, a rear frame is adopted at the rear of the vehicle body. The rear frame is an essential part for the collision performance and NVH (Noise, Vibration, Harshness: vehicle comfort) performance of the vehicle body. The rear frame includes a pair of rear side members and a plurality of cross members connecting the pair of rear side members.

[0005] However, in the rear frame of a conventional electric vehicle, there is a demerit that the rear side members and the cross members are joined via mechanical fasteners such as self-piercing rivets (SPR) and flow drill screws (FDS), resulting in a loss of rigidity in the rear structure of the vehicle.

[0006] In addition, existing side members and cross members can satisfy the target rigidity of the side members and cross members by having a closed cross-section through a pressing method, a joining method, or the like. However, since a plurality of parts are manufactured by a pressing method and the plurality of parts are joined by fasteners, welding, or the like, the manufacturing process of the side members and cross members becomes very complicated, and there is a demerit that the manufacturing cost becomes relatively high.

[0007] Therefore, when manufacturing a rear frame by a casting method such as a high-vacuum die-casting method, the number of parts and the manufacturing cost can be reduced, which is advantageous in the integration of vehicle body parts. However, when manufacturing a rear frame by a casting method, it may have a pocket structure with an open upper part, and during the electrodeposition coating process, the electrodeposition coating liquid may accumulate in the pocket structure, and there is a problem that the electrodeposition coating liquid accumulated in the pocket structure burns during the baking of the electrodeposition coating process.

[0008] The matters described in this background art section are created to enhance the understanding of the background of the invention, and include matters that are not prior art already known to those having ordinary knowledge in the field to which this technology belongs.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention has been derived in consideration of the above points, and an object thereof is to provide a vehicle rear frame that is easy to manufacture by a casting method and can prevent the accumulation of electrodeposition coating liquid.

Means for Solving the Problems

[0011] The vehicle rear frame according to the present invention for achieving the above object can include a pair of side portions spaced apart along the width direction of the vehicle, a first cross portion connecting the front portions of the pair of side portions, and a second cross portion connecting the rear portions of the pair of side portions. The pair of side portions, the first cross portion, and the second cross portion can form a single body. Each side portion can include a front mounting seat surface to which a front mount of a rear subframe is attached, a front recessed structure formed on the front mounting seat surface, a rear mounting seat surface to which a rear mount of the rear subframe is attached, and a rear recessed structure formed on the rear mounting seat surface. The front recessed structure has a pocket shape with an open upper portion, the front recessed structure has a through hole, the rear recessed structure has a pocket shape with an open upper portion, and the rear recessed structure is characterized by having a through hole.

[0012] Each side portion includes a channel portion to which a wheelhouse inner panel and a wheelhouse reinforcement are attached. The channel portion has a pocket shape with an open upper portion, and the channel portion can have a through hole.

[0013] Each side portion further includes a damper receptacle to which a suspension damper is attached. The damper receptacle can have a pocket shape with a cavity having an open lower portion.

[0014] The damper receptacle can be located between the front mounting seat surface and the rear mounting seat surface.

[0015] Each side portion can include a front interior wall extending forward from the damper receptacle toward the front of the vehicle and a rear interior wall extending rearward from the damper receptacle toward the rear of the vehicle. The front interior wall and the rear interior wall can extend along the center line between the interior end and the exterior end of the side portion.

[0016] The front mounting seat surface can be formed at the lower edge of the front interior wall, and the rear mounting seat surface can be formed at the lower edge of the rear interior wall.

[0017] The front recessed structure is defined by the front interior wall and the front mounting seat surface, and the front recessed structure can have a reinforcing rib extending from the front interior wall toward the interior of the vehicle.

[0018] The rear recessed structure is defined by the rear interior wall and the rear mounting seat surface, and the rear recessed structure can have a reinforcing rib extending from the rear interior wall toward the interior of the vehicle.

[0019] The first cross portion includes an upper wall, a vertical wall extending vertically downward from the upper wall, a lower wall extending forward of the vehicle from the lower end of the vertical wall, a recessed wall recessed downward from the lower wall toward the lower part of the vehicle, a plurality of raised walls raised upward from the recessed wall, and a plurality of passages formed between the plurality of raised walls, and the plurality of passages can be located in the same plane as the upper surface of the recessed wall.

Advantages of the Invention

[0020] The rear frame for a vehicle according to the present invention has a plurality of pocket structures with open upper or lower portions, which has the advantage of being easy to manufacture by a casting method, can prevent the accumulation of electrodeposition coating liquid, and can improve the quality of electrodeposition coating. By connecting a reinforcing rib to the pocket structure, the rigidity can be enhanced, and the NVH and R&H performance of the vehicle can be improved.

[0021] The rear frame for a vehicle according to the present invention can enhance the rigidity of the rear structure of the vehicle by forming a unitary one-piece structure of a pair of side portions and a plurality of cross portions by a casting method. In particular, since the pair of side portions and the plurality of cross portions form a unitary body, there are no joints connected by welding, fasteners, brackets, reinforcing materials, etc., so that the load can be uniformly distributed or transmitted through the pair of side portions and the plurality of cross portions. In the conventional rear frame, at the joint between the rear side member and the cross member, breakage, damage, etc. occur, resulting in a decrease in its rigidity. On the other hand, since there is no joint between each side portion and the cross portion of the rear frame of the present invention, it is possible to prevent a decrease in rigidity at the joint portion, and not only sufficiently ensure the mounting rigidity, input point rigidity, etc. of related components connected to the rear frame, but also significantly improve the rear collision response strength.

Brief Description of the Drawings

[0022]

Figure 1

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Figure 15

Embodiments for Carrying Out the Invention

[0023] Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. When attaching reference numerals to the components of each drawing, the same components are given the same reference numerals as much as possible. In addition, when describing the embodiments of the present invention, if a detailed description of a related known configuration or function hinders the understanding of the embodiments of the present invention, the detailed description thereof will be omitted.

[0024] When explaining the components of the embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. are used. Such terms are for distinguishing the components from other components, and the essence, procedure, order, etc. of the components are not limited by such terms. Also, unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by those having ordinary knowledge in the technical field to which the present invention belongs. Terms defined in a generally used dictionary are interpreted to have a meaning consistent with the meaning in the context of the related art, and are not interpreted in an ideal or overly formal meaning unless clearly defined in the present application.

[0025] Referring to FIG. 1, a rear frame 10 according to an embodiment of the present invention includes a pair of side portions 11 spaced apart along the vehicle width direction, a first cross portion 12 connecting front portions of the pair of side portions 11, and a second cross portion 13 connecting rear portions of the pair of side portions 11. The pair of side portions 11, the first cross portion 12, and the second cross portion 13 are formed as a single body by a casting method. In the rear frame of the prior art, after a pair of rear side members, a first cross member, and a second cross member are individually manufactured, the pair of rear side members, the first cross member, and the second cross member are coupled to each other via various fasteners. In contrast, in the present invention, since the pair of side portions 11, the first cross portion 12, and the second cross portion 13 form a single body, there are no joints connected by welding, fasteners, brackets, reinforcements, etc., so that the load is uniformly distributed or transmitted through the pair of side portions and the plurality of cross portions. In the conventional rear frame, the rigidity is reduced due to breakage, damage, etc. occurring at the joints between the rear side member and the cross member, whereas in the rear frame 10 of the present invention, since there are no joints between each side portion 11 and the cross portions 12, 13, it is possible to prevent a decrease in rigidity at the joint portion, and not only sufficiently ensure the mounting rigidity, input point rigidity, etc. of related components connected to the rear frame 10, but also significantly improve the rear collision response strength.

[0026] The rear frame 10 can be connected to the rear edge portion of the vehicle center floor 1, and a pair of side sills 1a are attached to both side edge portions of the center floor 1. A plurality of rear floor panels 2, 3, 4 are attached to the rear frame 10. The plurality of rear floor panels 2, 3, 4 include a first rear floor panel 2 connected to the rear edge portion of the center floor 1, a second rear floor panel 3 located behind the first rear floor panel 2, and a storage well 4 located behind the second rear floor panel 3.

[0027] The front edge of the first rear floor panel 2 is fixed to the rear edge of the center floor 1 by means of fasteners, welding, etc. A plurality of vertical members 6 can be fixed to the first rear floor panel 2 by means of fasteners, welding, etc., and the rear end of the vertical member 6 is fixed to the first cross member 12 by means of fasteners, welding, etc. The rear edge of the first rear floor panel 2 is fixed to the front edge of the first cross member 12 by means of fasteners, welding, etc.

[0028] The second rear floor panel 3 is attached between the pair of side portions 11, the first cross member 12, and the second cross member 13. The second rear floor panel 3 can be positioned higher than the first rear floor panel 2. The front edge of the second rear floor panel 3 can be fixed to the first cross member 12 by means of fasteners, welding, etc., the rear edge of the second rear floor panel 3 can be fixed to the second cross member 13 by means of fasteners, welding, etc., and each side edge of the second rear floor panel 3 is fixed to the corresponding side portion 11 by means of fasteners, welding, etc.

[0029] Referring to FIG. 1, the rear frame 10 according to an embodiment of the present invention further includes a support member 14 extending along the longitudinal direction of the vehicle between the first cross member 12 and the second cross member 13. The front end of the support member 14 can be fixed to the middle portion of the first cross member 12, and the rear end of the support member 14 is fixed to the middle portion of the second cross member 13. Thereby, the support member 14 significantly enhances the longitudinal rigidity of the rear frame 10 by connecting the first cross member 12 and the second cross member 13 along the longitudinal direction of the vehicle. Further, since the support member 14 is attached across the first cross member 12 and the second cross member 13, the support member 14 firmly supports the second rear floor panel 3.

[0030] The storage well 4 can be recessed downward with respect to the second rear floor panel 3, and the front edge of the storage well 4 is fixed to the second cross part 13 by means of fasteners, welding, etc. A pair of rear extension members 9 can be fixed to both side edges of the storage well 4 by means of fasteners, welding, etc., and the back panel 5 is fixed to the rear edge of the storage well 4 by means of fasteners, welding, etc.

[0031] A pair of wheelhouse inner panels 7 are individually attached to the pair of side parts 11. Each wheelhouse inner panel 7 is fixed to the corresponding side part 11 by means of fasteners, welding, etc.

[0032] Referring to FIG. 2, the pair of side parts 11 are spaced apart along the width direction of the vehicle. Each side part 11 extends along the longitudinal direction of the vehicle so as to define both side edges of the rear structure of the vehicle.

[0033] Each side part 11 includes a damper receptacle 23 to which a suspension damper 16 is attached, a front upper wall 21 extending forward from the damper receptacle 23 toward the front of the vehicle, and a rear upper wall 22 extending rearward from the damper receptacle 23 toward the rear of the vehicle. The front end of each side part 11 can be connected to the corresponding side sill 1a, and the rear end of each side part 11 is connected to the corresponding rear extension member 9.

[0034] Referring to FIGS. 4, 10, and 11, the damper receptacle 23 is in the shape of a pocket having a cavity 23e with its lower part open. The upper part of a suspension damper 16 such as a shock absorber can be received in the cavity 23e of the damper receptacle 23, and the upper part of the suspension damper 16 is attached to the cavity 23e of the damper receptacle 23. The damper receptacle 23 includes an upper wall 23a, an outdoor wall 23b extending downward from the outdoor edge of the upper wall 23a, and an indoor wall 23c extending downward from the indoor edge of the upper wall 23a. The cavity 23e is defined by the upper wall 23a, the outdoor wall 23b, and the indoor wall 23c. The front end of the outdoor wall 23b can be connected to the front end of the indoor wall 23c, and the rear end of the outdoor wall 23b is connected to the rear end of the indoor wall 23c. The damper receptacle 23 further includes a raised wall 23d that bulges upward from the upper wall 23a.

[0035] The front end of the front upper wall 21 can be configured to be connected to the corresponding side sill 1a, and the rear end of the front upper wall 21 is integrally connected to the front end of the damper receptacle 23.

[0036] Referring to FIG. 7, the front inboard wall 21a is a vertical wall extending vertically downward from the front upper wall 21, and the front inboard wall 21a faces the interior of the vehicle. The front inboard wall 21a extends along the center line between the outdoor edge and the indoor edge of the side portion 11. In particular, the front inboard wall 21a extends along the center line of the damper receptacle 23.

[0037] The front end of the rear upper wall 22 is integrally connected to the rear end of the damper receptacle 23. The rear end of the rear upper wall 22 is integrally connected to the front end of the corresponding rear extension member 9. The rear upper wall 22 has a rear portion 22b and an indoor wall 22c that accommodate the front portion of the rear extension member 9.

[0038] Referring to FIG. 8, the rear interior wall 22a can be a vertical wall extending vertically downward from the rear upper wall 22, and the rear interior wall 22a faces the interior of the vehicle. The rear interior wall 22a extends along the center line between the outer edge and the inner edge of the side portion 11. In particular, the rear interior wall 22a extends along the center line of the damper receptacle 23.

[0039] As described above, the front interior wall 21a can extend forward from the damper receptacle 23 toward the front of the vehicle, the rear interior wall 22a can extend rearward from the damper receptacle 23 toward the rear of the vehicle, and by integrally connecting the front interior wall 21a and the rear interior wall 22a to the damper receptacle 23, the rigidity of the damper receptacle 23 can be strengthened, and thus the load acting by the suspension damper 16 is dispersed along the front interior wall 21a and the rear interior wall 22a.

[0040] Referring to FIG. 2, each side portion 11 can further include a front flange 28a formed at the front portion of the front interior wall 21a, and the front flange 28a extends horizontally from the front interior wall 21a. Each side portion 11 includes an outer flange 26 extending along the outer edge of the front upper wall 21, the outer edge of the upper wall 23a of the damper receptacle 23, and the outer edge of the rear upper wall 22. The wheelhouse inner panel 7 can be fixed to the outer flange 26 of each side portion 11, and the wheelhouse reinforcement 8 is fixed to the middle portion of the wheelhouse inner panel 7 by fasteners, welding, etc. The wheelhouse reinforcement 8 is in a channel shape bent along the upper surface and the interior surface of the wheelhouse inner panel 7. The wheelhouse reinforcement 8 includes a front wall facing the front of the vehicle, a rear wall facing the rear of the vehicle, and an interior wall facing the interior of the vehicle.

[0041] Referring to FIGS. 1 and 2, each side portion 11 includes a channel portion 27 protruding upward from the front upper wall 21 and the damper receptacle 23. A part of the wheelhouse inner panel 7 and the lower end of the wheelhouse reinforcement 8 are fixed to the channel portion 27 by fasteners, welding, etc.

[0042] Referring to FIGS. 3 and 5, the channel portion 27 has a pocket shape including a cavity 27e with an open upper portion thereof. The channel portion 27 includes an indoor wall 27a facing the interior of the vehicle, an outdoor wall 27b facing the exterior of the vehicle, a front wall 27c facing the front of the vehicle, a rear wall 27d facing the rear of the vehicle, and a bottom wall 27f facing the lower portion of the vehicle. The cavity 27e is defined by the indoor wall 27a, the outdoor wall 27b, the front wall 27c, the rear wall 27d, and the bottom wall 27f. The lower end of the wheel house reinforcement 8 is fixed to the indoor wall 27a, the front wall 27c, and the rear wall 27d of the channel portion 27 by means of fasteners such as fastening tools, welding, etc. A part of the wheel house inner panel 7 is fixed to the outdoor wall 27b of the channel portion 27 by means of fasteners such as fastening tools, welding, etc.

[0043] Referring to FIG. 15, the lower end of the wheel house reinforcement 8 can be fixed to the indoor wall 27a of the channel portion 27 via a fastener such as a Flow Drill Screw (FDS), and a part of the wheel house inner panel 7 is fixed to the outdoor wall 27b of the channel portion 27 via a fastener such as a Flow Drill Screw (FDS).

[0044] The channel portion 27 has a pocket shape with an open upper end, and during the electrocoating of the rear frame 10, the electrocoating liquid can accumulate in the cavity 27e of the channel portion 27. There was a problem that the electrocoating liquid accumulated in the cavity 27e of the channel portion 27 would burn during the baking process of the electrocoating process. To solve this problem, the channel portion 27 can have a through hole 71 formed in the bottom wall 27f, and the through hole 71 is open toward the outside of the channel portion 27. By discharging the electrocoating liquid through the through hole 71 of the channel portion 27, the electrocoating liquid does not accumulate in the cavity 27e of the channel portion 27.

[0045] Each side portion 11 further includes a first interior horizontal wall 28b that extends horizontally from the front interior wall 21a, the interior wall 23c of the damper receptacle 23, and the rear interior wall 22a toward the interior of the vehicle, an interior vertical wall 28d that extends vertically downward from the first interior horizontal wall 28b, and a second interior horizontal wall 28c that extends horizontally from the interior vertical wall 28d.

[0046] The first cross portion 12 is configured to connect the front portions of a pair of side portions 11 along the vehicle width direction. The front edge of the first cross portion 12 can be fixed to the rear edge of the first rear floor panel 2, and the rear edge of the first cross portion 12 can be fixed to the front edge of the second rear floor panel 3.

[0047] Referring to FIG. 2, the first cross portion 12 includes an upper wall 41, a vertical wall 42 that extends vertically downward from the front edge of the upper wall 41, and a lower wall 43 that extends forward of the vehicle from the lower end of the vertical wall 42. The height of the upper wall 41 is the same as or similar to the height of the second cross portion 13. The rigidity of the first cross portion 12 is strengthened by the upper wall 41, the vertical wall 42, and the lower wall 43.

[0048] Referring to FIGS. 2 and 6, the first cross portion 12 includes a recessed wall 44 that recesses from the lower wall 43 toward the lower part of the vehicle, a plurality of raised walls 45 that bulge upward from the recessed wall 44, and a first cross portion front flange 47 that recesses downward from the front edge of the recessed wall 44.

[0049] Referring to FIGS. 2 and 14, the plurality of raised walls 45 can be adjacent to the front edge of the recessed wall 44. By separating the plurality of raised walls 45 along the vehicle width direction (i.e., the longitudinal direction of the first cross portion 12), a plurality of passages 46 can be formed between the plurality of raised walls 45, and the upper surfaces of each passage 46 are located in the same plane as the upper surface of the recessed wall 44. When electrodeposition coating liquid drips onto the recessed wall 44 during electrodeposition coating of the rear frame 10, the electrodeposition coating liquid can drip onto the first cross portion front flange 47 through the plurality of passages 46, thereby preventing the electrodeposition coating liquid from accumulating on the recessed wall 44.

[0050] The rear edge of the first rear floor panel 2 is fixed to the front flange 47 of the first cross member and the front flange 28a of the side portion 11 by fasteners, welding, etc.

[0051] Referring to FIGS. 4 and 5, each side portion 11 includes a front mounting seat surface 31 provided on the front bottom surface thereof and a rear mounting seat surface 32 provided on the rear bottom surface thereof. The front mount 15a of the rear subframe 15 can be attached to the front mounting seat surface 31, and the rear mount 15b of the rear subframe 15 can be attached to the rear mounting seat surface 32. The damper receptacle 23 is located between the front mounting seat surface 31 and the rear mounting seat surface 32.

[0052] The front mounting seat surface 31 is integrally formed with a part of the lower edge of the front interior wall 21a. Referring to FIGS. 3 and 4, the front mounting seat surface 31 can be substantially circular, and the front interior wall 21a passes across the center line of the front mounting seat surface 31 or a line adjacent thereto. The front mounting seat surface 31 is integrally connected to the front interior wall 21a.

[0053] Referring to FIG. 7, the front mounting seat surface 31 is horizontally flat on the bottom surface of the lower edge of the front interior wall 21a. Each side portion 11 includes a front mounting boss 35 located at the center of the front mounting seat surface 31. The center line of the front mounting seat surface 31 can be aligned with the center line of the corresponding side portion 11, whereby the front mounting boss 35 is aligned with the center line of the front left surface 31 and the center line of the corresponding side portion 11. The front mounting boss 35 can be formed at the lower part of the front portion of the front interior wall 21a, and the front mounting boss 35 extends vertically along the front interior wall 21a. The front mounting hardware 33 can be fixed to the front mounting boss 35, and the center of the front mounting hardware 33 is aligned with the center of the front mounting boss 35. The front mounting hardware 33 is in the shape of a nut. Referring to FIG. 10, the front mount 15a of the rear subframe 15 is attached to the front mounting seat surface 31 via the front mounting hardware 33.

[0054] According to the prior art, the rear side member has a front mounting boss formed at its front portion, the front mount of the rear subframe is attached to the front mounting boss, the front mounting boss is formed at the lower portion of the front part of the indoor wall of the rear side member, and since the indoor wall of the rear side member is adjacent to the indoor edge of the rear side member, the thickness of the front mounting boss can be formed relatively thick. As a result, not only does the castability of the rear side member deteriorate, but a large number of pores can be formed inside the indoor wall, so that the casting quality can deteriorate. In contrast, in the present invention, since the front indoor wall 21a extends along the center line between the outdoor edge and the indoor edge of the side portion 11, the thickness of the front mounting boss 35 formed at the lower portion of the front indoor wall 21a can be relatively thin. Thereby, its castability can be improved, and since no pores are formed inside the front mounting boss 35, its casting quality is improved.

[0055] Referring to FIG. 7, each side portion 11 can include a front recessed structure 37 formed on the front mounting seat surface 31. By forming the front recessed structure 37 on the front mounting seat surface 31, the castability of the rear frame 10 is ensured. Since the front mounting seat surface 31 is formed at the lower edge portion of the front interior wall 21a, the front recessed structure 37 is a structure that recesses downward from a part between the front interior wall 21a and the first cross portion 12. Thereby, the front recessed structure 37 can be limited by the front interior wall 21a, the lower wall 43 of the first cross portion 12, and the front mounting seat surface 31, and the front recessed structure 37 has a pocket shape with its upper part open. Referring to FIG. 12, the front recessed structure 37 has a substantially semi-circular pocket shape facing the front interior wall 21a. The front recessed structure 37 has a reinforcing rib 35a extending from the front interior wall 21a toward the interior of the vehicle. Since the front reinforcing rib 35a extends from the front mounting boss 35 of the front interior wall 21a toward the lower wall 43 of the first cross portion 12, the front reinforcing rib 35a is formed across the front recessed structure 37. The front reinforcing rib 35a can extend along the width direction of the vehicle, and the front reinforcing rib 35a is orthogonal to the front interior wall 21a. Thereby, the rigidity of the front recessed structure 37 is strengthened by the front reinforcing rib 35a.

[0056] The front recessed structure 37 has a pocket shape with its upper part open. During the electrocoating of the rear frame 10, the electrocoating liquid can accumulate inside the front recessed structure 37, and there was a problem that the electrocoating liquid accumulated in the front recessed structure 37 would burn during the baking process of the electrocoating process. To solve this problem, a through hole 72 can be formed in a part of the front interior wall 21a that limits the front recessed structure 37, and the through hole 72 is open toward the outside of the front recessed structure 37. According to an example, the through hole 72 can extend obliquely from the front interior wall 21a toward the outside of the vehicle, and the through hole 72 communicates directly with the front recessed structure 37. Thereby, the electrocoating liquid accommodated in the front recessed structure 37 is discharged through the through hole 72 of the front recessed structure 37, so that the electrocoating liquid does not accumulate in the front recessed structure 37.

[0057] The rear mounting seat surface 32 is formed on a part of the lower edge of the rear interior wall 22a. Referring to FIGS. 3 and 4, the rear mounting seat surface 32 can be substantially circular, and the rear interior wall 22a passes across the center line of the rear mounting seat surface 32 or a line adjacent thereto. The rear mounting seat surface 32 is integrally connected to the rear interior wall 22a.

[0058] Referring to FIG. 8, the rear mounting seat surface 32 is horizontally flat on the bottom surface of the lower edge of the rear interior wall 22a. Each side portion 11 includes a rear mounting boss 36 located at the center of the rear mounting seat surface 32. The center line of the rear mounting seat surface 32 can be aligned with the center line of the corresponding side portion, and the rear mounting boss 36 is aligned with the center line of the side portion 11 and the center line of the corresponding rear mounting seat surface 32. The rear mounting boss 36 can be formed at the lower part of the rear portion of the rear interior wall 22a, and the rear mounting boss 36 extends vertically along the rear interior wall 22a. The rear mounting hardware 34 can be fixed to the rear mounting boss 36, and the center of the rear mounting hardware 34 is aligned with the center of the rear mounting boss 36. The rear mounting hardware 34 is in the shape of a bolt. Referring to FIG. 10, the rear mount 15b of the rear sub-frame 15 is attached to the rear mounting seat surface 32 via the rear mounting hardware 34.

[0059] According to the prior art, the rear side member has a rear mounting boss formed at its rear portion, and the rear mount of the rear subframe is attached to the rear mounting boss. The rear mounting boss is formed at the lower portion of the rear part of the indoor wall of the rear side member. Since the indoor wall of the rear side member is adjacent to the indoor edge portion of the rear side member, the thickness of the rear mounting boss can be formed relatively thick. As a result, not only does the castability of the rear side member deteriorate, but a large number of pores may be formed inside the indoor wall, and its casting quality may decrease. In contrast, in the present invention, since the rear indoor wall 22a extends along the center line between the outdoor edge portion and the indoor edge portion of the side portion 11, the thickness of the rear mounting boss 36 formed at the lower portion of the rear indoor wall 22a can be relatively thin. Thereby, its castability can be improved, and since no pores are formed inside the rear mounting boss 36, its casting quality is improved.

[0060] Referring to FIG. 8, each side portion 11 can include a rear recessed structure 38 formed on the rear mounting seat surface 32. By forming the rear recessed structure 38 on the rear mounting seat surface 32, the castability of the rear frame 10 is ensured. Since the rear mounting seat surface 32 is formed at the lower edge portion of the rear interior wall 22a, the rear recessed structure 38 is a structure that recesses downward from a part between the rear interior wall 22a and the first interior horizontal wall 28b. Thereby, the rear recessed structure 38 can be defined by the rear interior wall 22a, the first interior horizontal wall 28b of the side portion 11, and the rear mounting seat surface 32, and the rear recessed structure 38 has a pocket shape with its upper part open. Referring to FIG. 13, the rear recessed structure 38 has a substantially semi-circular pocket shape facing the rear interior wall 22a. The rear recessed structure 38 has a rear reinforcing rib 36a extending from the rear interior wall 22a toward the interior of the vehicle. By extending the rear reinforcing rib 36a from the rear mounting boss 36 of the rear interior wall 22a toward the first interior horizontal wall 28b of the side portion 11, the rear reinforcing rib 36a is formed across the rear recessed structure 38. The rear reinforcing rib 36a can extend along the width direction of the vehicle, and the rear reinforcing rib 36a is orthogonal to the rear interior wall 22a. Thereby, the rigidity of the rear recessed structure 38 is strengthened by the rear reinforcing rib 36a.

[0061] The rear recessed structure 38 has a pocket shape with its upper part open. During the electrocoating of the rear frame 10, the electrocoating liquid can accumulate inside the rear recessed structure 38, and there was a problem that the electrocoating liquid accumulated in the rear recessed structure 38 would burn during the baking process of the electrocoating process. To solve this problem, a through hole 73 can be formed in a part of the rear interior wall 22a that defines the rear recessed structure 38, and the through hole 73 is open toward the outside of the rear recessed structure 38. According to an example, the through hole 73 can extend obliquely from the rear interior wall 22a toward the outside of the vehicle, and the through hole 73 communicates directly with the rear recessed structure 38. Thereby, the electrocoating liquid accommodated in the rear recessed structure 38 is discharged through the through hole 73, so that the electrocoating liquid does not accumulate in the rear recessed structure 38.

[0062] As described above, the front interior wall 21a is integrally connected to the front mounting seat surface 31, the rear interior wall 22a is integrally connected to the rear mounting seat surface 32, the front mount 15a of the rear sub-frame 15 is attached to the front mounting seat surface 31, and the rear mount 15b of the rear sub-frame 15 is attached to the rear mounting seat surface 32. Thus, the rear sub-frame 15 attached to the pair of side portions 11 is stably supported along the longitudinal direction of the vehicle by the front interior wall 21a and the rear interior wall 22a.

[0063] The rear end of each side portion 11 is connected to the corresponding rear extension member 9. The rear interior wall 22a of each side portion 11 is fixed to the rear extension member 9. Referring to FIGS. 5 and 9, the rear interior wall 22a can include a plurality of rear extension member mounting bosses 51 provided at its rear portion, and each mounting boss 51 has a mounting hole defined therein. The front portion of the rear extension member 9 is fixed to the rear extension member mounting boss 51 of the rear interior wall 22a via a bolt 81. Mounting hardware such as a tapping nut 61 is attached to the mounting hole of the corresponding rear extension member mounting boss 51. The tapping nut 61 has an internal female thread portion 61a formed on its inner surface and an external male thread portion 61b formed on its outer surface. By tapping the rear extension member mounting boss 51 with the male thread portion 61b of the tapping nut 61, the tapping nut 61 can be attached to the rear extension member mounting boss 51, and the male thread portion 81a of the bolt 81 is threadedly coupled to the female thread portion 61a of the tapping nut 61, whereby the front portion of the rear extension member 9 is attached to the rear extension member mounting boss 51 of the rear interior wall 22a.

[0064] Referring to FIG. 3, the first cross member 12 includes a plurality of seat-side mounting bosses 52 adjacent to its front edge. The plurality of seat-side mounting bosses 52 can be spaced along the vehicle width direction, and each seat-side mounting boss 52 has a mounting hole defined therein. Referring to FIG. 6, the seat-side mounting boss 52 can project upward from the raised wall 45 of the first cross member 12, and the rear seat mount 17 of a rear vehicle seat (e.g., a two-row vehicle seat) is attached to the seat-side mounting boss 52 via a bolt. Mounting hardware such as a tapping nut 62 is attached to the mounting hole of the corresponding seat-side mounting boss 52. The tapping nut 62 has an internal thread portion 62a formed on its inner surface and an external thread portion 62b formed on its outer surface. When the seat-side mounting boss 52 is tapped by the external thread portion 62b of the tapping nut 62, the tapping nut 62 can be attached to the seat-side mounting boss 52, and the bolt is threadedly coupled to the internal thread portion 62a of the tapping nut 62, whereby the rear seat mount 17 is attached to the seat-side mounting boss 52 of the first cross member 12. The plurality of seat-side mounting bosses 52 are symmetrically arranged with respect to the center of the first cross member 12.

[0065] Referring to FIG. 3, the first cross member 12 includes a plurality of battery side mounting bosses 53 adjacent to a plurality of seat side mounting bosses 52. The plurality of battery side mounting bosses 53 are spaced apart along the vehicle width direction. Each battery side mounting boss 53 has a mounting hole defined therein. Referring to FIG. 6, the battery side mounting boss 53 can be located behind the seat side mounting boss 52, the battery side mounting boss 53 can protrude downward from the raised wall 45 of the first cross member 12, and the battery 18 is attached to the rear mounting boss 53 via a bolt. Mounting hardware such as a tapping nut 63 is attached to the battery side mounting boss 53. The tapping nut 63 has an internal thread portion 63a formed on its inner surface and an external thread portion 63b formed on its outer surface. When the battery side mounting boss 53 is tapped by the external thread portion 63b of the tapping nut 63, the tapping nut 63 can be attached to the battery side mounting boss 53, and when the bolt is threadedly coupled to the internal thread portion 63a of the tapping nut 63, the battery 18 is attached to the battery side mounting boss 53 of the first cross member 12. The plurality of battery side mounting bosses 53 are symmetrically arranged with respect to the central portion of the first cross member 12.

[0066] Referring to FIG. 3, the first cross member 12 can include a plurality of first mounting bosses 54 adjacent to its rear edge portion, and each first mounting boss 54 has a mounting hole defined therein. The front seat mount of a vehicle seat (e.g., a three-row vehicle seat) located at the rearmost position in the passenger compartment of the vehicle is attached to the first mounting boss 54 of the first cross member 12 via a bolt.

[0067] Referring to FIG. 3, the second cross member 13 can include a plurality of second mounting bosses 55, and each second mounting boss 55 has a mounting hole defined therein. The rear seat mount of a vehicle seat (e.g., a three-row vehicle seat) located at the rearmost position in the passenger compartment of the vehicle is attached to the second mounting boss 55 of the second cross member 13 via a bolt.

[0068] Referring to FIG. 4, each side portion 11 includes a plurality of reinforcing ribs 11a, 11b, 11c integrally formed on its bottom surface. The plurality of reinforcing ribs 11a, 11b, 11c consists of a plurality of first reinforcing ribs 11a extending along the longitudinal direction of each side portion 11, a plurality of second reinforcing ribs 11b extending along the diagonal direction, and a plurality of third reinforcing ribs 11c extending along the width direction of each side portion 11. The first reinforcing ribs 11a are spaced apart from the front interior wall 21a, the damper receptacle 23, and the rear interior wall 22a toward the interior of the vehicle. The plurality of reinforcing ribs 11a, 11b, 11c can be arranged to intersect each other along the longitudinal direction of each side portion 11, and the plurality of reinforcing ribs 11a, 11b, 11c are integrally connected to the front interior wall 21a, the interior wall 23c of the damper receptacle 23, and the rear interior wall 22a. The plurality of second reinforcing ribs 11b can connect the damper receptacle 23 to the first reinforcing ribs 11a, and the plurality of third reinforcing ribs 11c connect the front interior wall 21a and the rear interior wall 22a to the first reinforcing ribs 11a. Thereby, the rigidity of each side portion 11 and the damper receptacle 23 is enhanced by the plurality of reinforcing ribs 11a, 11b, 11c.

[0069] Referring to FIG. 5, each side portion 11 can include a plurality of reinforcing ribs 11f integrally formed on the front interior wall 21a, the interior wall 23c of the damper receptacle 23, and the rear interior wall 22a, and the plurality of reinforcing ribs 11f are connected to intersect each other along the longitudinal direction of the side portion 11. Thereby, the lateral stiffness of each side portion 11 is enhanced by the plurality of reinforcing ribs 11f.

[0070] Referring to FIG. 4, the first cross member 12 includes a plurality of reinforcing ribs 12a, 12b, 12c integrally formed on its bottom surface. The plurality of reinforcing ribs 12a, 12b, 12c are composed of a plurality of first reinforcing ribs 12a extending along the vehicle width direction, a plurality of second reinforcing ribs 12b extending along the vehicle longitudinal direction, and a plurality of third reinforcing ribs 12c extending in the diagonal direction. The plurality of reinforcing ribs 12a, 12b, 12c can be arranged to intersect each other along the vehicle width direction. As a result, the rigidity of the first cross member 12 is strengthened by the plurality of reinforcing ribs 12a, 12b, 12c. Some of the reinforcing ribs 12a, 12b, 12c are connected to the plurality of battery side mounting bosses 53. For example, by connecting the first reinforcing ribs 12a, the second reinforcing ribs 12b, and the third reinforcing ribs 12c so as to intersect each battery side mounting boss 53, the rigidity of the plurality of battery side mounting bosses 53 is strengthened.

[0071] Referring to FIG. 4, the first cross member 12 includes a plurality of reinforcing ribs 54a, 54b, 54c connected to the first mounting boss 54. The plurality of reinforcing ribs 54a, 54b, 54c are composed of a plurality of first reinforcing ribs 54a extending along the vehicle width direction, a plurality of second reinforcing ribs 54b extending in the diagonal direction, and a plurality of third reinforcing ribs 54c extending along the vehicle longitudinal direction. For example, the plurality of first reinforcing ribs 54a are connected to the first mounting boss 54 adjacent to the center line of the rear frame 10. The first reinforcing rib 54a, the second reinforcing rib 54b, and the third reinforcing rib 54c are connected so as to intersect the first mounting boss 54 adjacent to each end of the first cross member 12.

[0072] Referring to FIG. 4, the second cross member 13 includes a plurality of reinforcing ribs 13a, 13b integrally formed on its bottom surface. The plurality of reinforcing ribs 13a, 13b are composed of a plurality of first reinforcing ribs 13a extending along the vehicle width direction and a plurality of second reinforcing ribs 13b extending in the diagonal direction. The plurality of reinforcing ribs 13a, 13b can be arranged to intersect each other along the vehicle width direction, and the rigidity of the second cross member 13 is strengthened by the plurality of reinforcing ribs 13a, 13b.

[0073] Referring to FIG. 4, the second cross member 13 includes a plurality of reinforcing ribs 55a, 55b, 55c integrally connected to the second mounting boss 55. The plurality of reinforcing ribs 55a, 55b, 55c are composed of a plurality of first reinforcing ribs 55a extending along the longitudinal direction of the vehicle, a plurality of second reinforcing ribs 55b extending along the diagonal direction, and a plurality of third reinforcing ribs 55c extending along the width direction of the vehicle. For example, the first reinforcing rib 55a, the second reinforcing rib 55b, and the third reinforcing rib 55c are connected so as to intersect the second mounting boss 55 of the second cross member 13.

[0074] The above description is merely illustrative of the technical idea of the present invention, and those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and deformations without departing from the essential characteristics of the present invention.

[0075] Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but for the purpose of explanation, and the scope of the technical idea of the present invention is not limited by such embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the rights of the present invention.

Description of Reference Numerals

[0076] 1 Center Floor 1a Side Sill 2 First Rear Floor Panel 3 Second Rear Floor Panel 4 Storage Well 5 Back Panel 6 Longitudinal Member 7 Wheelhouse Inner Panel 8 Wheelhouse Reinforcement 9 Rear Extension Member 10 Rear Frame 11 Side Portion 11a, 11b, 11c, 11f Reinforcing Rib 12 First Cross Member 12a, 12b, 12c Reinforcing ribs 13 Second cross section 13a, 13b Reinforcing ribs 14 Support member 15 Rear subframe 15a Front mount 15b Rear mount 16 Suspension damper 17 Rear seat mount 18 Battery 21 Front upper wall 21a Front interior wall 22 Rear upper wall 22a Rear interior wall 22b Rear part 22c Interior wall 23 Damper receptacle 23a Upper wall 23b Exterior wall 23c Interior wall 23d Raised wall 23e Cavity 26 Exterior flange 27 Channel part 27a Interior wall 27b Exterior wall 27c Front wall 27d Rear wall 27e Cavity 27f Bottom wall 28a Front flange 28b First interior horizontal wall 28c Second interior horizontal wall 28d Interior vertical wall 31 Front mounting seat surface 32 Rear mounting seat surface 33 Front mounting hardware 34 Rear mounting hardware 35 Front mounting boss 35a Front reinforcing rib 36 Rear mounting boss 36a Rear reinforcing rib 37 Front recessed structure 38 Rear recessed structure 41 Upper wall 42 Vertical wall 43 Lower wall 44 Sunken wall 45 Raised wall 46 Passage 47 Front flange of the first cross section 51 Rear extension member mounting boss 52 Seat side mounting boss 53 Battery side mounting boss 54 First mounting boss 54a, 54b, 54c Reinforcing ribs 55 Second mounting boss 55a, 55b, 55c Reinforcing ribs 61 Tapping nut 61a Female thread part 61b Male thread part 62 Tapping nut 62a Female thread part 62b Male thread part 63 Tapping nut 63a Female thread part 63b Female thread part 71, 72, 73 Through holes 81 Bolt 81a Male thread part

Claims

1. A pair of side portions spaced apart along a width direction of the vehicle; a first cross portion connecting front portions of the pair of side portions; a second cross portion connecting rear portions of the pair of side portions, the pair of side portions, the first cross portion, and the second cross portion form a single body; each side portion includes a front mounting seat surface to which a front mount of the rear subframe is attached, a front recessed structure formed on the front mounting seat surface, a rear mounting seat surface to which a rear mount of the rear subframe is attached, and a rear recessed structure formed on the rear mounting seat surface, The front recessed structure is in the shape of a pocket with an open upper portion, the front recessed structure having a through hole, and the rear recessed structure is in the shape of a pocket with an open upper portion, the rear recessed structure having a through hole.

2. The rear frame according to claim 1, characterized in that each side portion includes a channel portion to which a wheelhouse inner panel and a wheelhouse reinforcement material are attached, the channel portion being pocket-shaped with an open upper portion, and the channel portion having a through hole.

3. Each side portion further includes a damper receptacle in which a suspension damper is mounted; The rear frame according to claim 1 , wherein the damper receptacle is in the shape of a pocket having a cavity with an open lower portion.

4. The rear frame according to claim 3 , wherein the damper receptacle is located between the front mounting seat surface and the rear mounting seat surface.

5. Each side portion includes a front interior wall extending from the damper receptacle toward the front of the vehicle and a rear interior wall extending from the damper receptacle toward the rear of the vehicle, The rear frame according to claim 3 , wherein the front interior wall and the rear interior wall extend along a center line between an interior edge portion and an exterior edge portion of the side portion.

6. 6. The rear frame according to claim 5, wherein the front mounting seat surface is formed on a lower edge portion of the front interior wall, and the rear mounting seat surface is formed on a lower edge portion of the rear interior wall.

7. The rear frame according to claim 5, characterized in that the front recessed structure is defined by the front interior wall and the front mounting seat surface, and the front recessed structure has a reinforcing rib extending from the front interior wall toward the interior of the vehicle.

8. The rear frame according to claim 5, characterized in that the rear recessed structure is defined by the rear interior wall and the rear mounting seat surface, and the rear recessed structure has a reinforcing rib extending from the rear interior wall toward the interior of the vehicle.

9. 2. The rear frame of claim 1, wherein the first cross portion includes an upper wall, a vertical wall extending vertically downward from the upper wall, a lower wall extending from a lower end of the vertical wall toward a front of the vehicle, a recessed wall recessed from the lower wall toward a lower portion of the vehicle, a plurality of raised walls protruding upward from the recessed wall, and a plurality of passages formed between the plurality of raised walls, the plurality of passages being located in the same plane as an upper surface of the recessed wall.

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