Vehicle body pillar structure and vehicle body side structure

Abstract

This vehicle body pillar structure using a fiber-reinforced resin composite material comprises two cylindrical portions that are composed of a fiber-reinforced resin, disposed aligned in the vehicle body longitudinal direction, and extend in the axial direction along the vehicle body height direction, said vehicle body pillar structure further including a first region in which the two cylindrical portions are joined on the upper side in the vehicle body height direction, and a second region in which the two cylindrical portions are branched and spaced apart on the lower side in the vehicle body height direction.

Description

Body pillar structure and body side structure

[0001] The technology of the present disclosure relates to a vehicle body pillar structure and a vehicle body side structure using a fiber-reinforced resin composite material.

[0002] In recent years, with the aim of reducing the weight of vehicle bodies such as passenger cars, the use of fiber-reinforced resins, such as carbon fiber reinforced plastics (hereinafter referred to as CFRP), to manufacture vehicle body structures has been considered. Fiber-reinforced resin components have high rigidity and exhibit high strength, particularly against compressive stress or tensile stress acting along the fiber orientation direction. For example, Patent Documents 1 and 2 disclose center pillars that use fiber-reinforced resin composite materials as part of their components.

[0003] JP 2019-182168 A JP 2015-47895 A

[0004] Even when a pillar is constructed primarily from a fiber-reinforced plastic composite, it is still required to have the same functionality as a conventional metal pillar. For example, in the case of a center pillar, in the event of a side collision, the upper part of the center pillar needs to be prevented from breaking to protect the occupant's head, while the lower part of the center pillar needs to absorb energy by deforming. In this case, when considering the strength of the center pillar, it is desirable that the center pillar be molded continuously from the top to the bottom without any joints along the vehicle height.

[0005] Furthermore, when a load is applied to the center pillar during a side collision, the joint between the center pillar and the side sill twists, causing stress to concentrate at the joint, potentially causing the fiber-reinforced plastic center pillar to break and bend toward the passenger compartment.

[0006] Therefore, the technology of the present disclosure has been made in consideration of the above problems, and the purpose of the present disclosure is to provide a vehicle body pillar structure and a vehicle body side structure made of a fiber-reinforced resin composite material that can suppress a decrease in the strength of the pillar when the vehicle body pillar is constructed using the fiber-reinforced resin composite material.

[0007] In order to solve the above problems, according to one aspect of the technology of the present disclosure, there is provided a vehicle body pillar structure using a fiber-reinforced resin composite material, which has two tubular sections made of fiber-reinforced resin arranged side by side in the fore-and-aft direction of the vehicle body and each extending in an axial direction along the height direction of the vehicle body, and which has a first region on the upper side in the height direction of the vehicle body where the two tubular sections are joined, and a second region on the lower side in the height direction of the vehicle body where the two tubular sections are branched off and spaced apart.

[0008] Furthermore, in order to solve the above-described problems, according to another aspect of the technology of the present disclosure, there is provided a vehicle body side structure using a fiber-reinforced resin composite material, the vehicle body side structure comprising: a center pillar having two tubular portions made of fiber-reinforced resin arranged side by side in the fore-and-aft direction of the vehicle body and each extending in an axial direction along the height direction of the vehicle body, the center pillar having a first region where the two tubular portions are joined on the upper side in the height direction of the vehicle body and a second region where the two tubular portions branch off and are spaced apart on the lower side in the height direction of the vehicle body; and a side sill arranged along the fore-and-aft direction of the vehicle body and to which a lower part of the center pillar is connected, wherein a belt retractor is arranged in the space between the two tubular portions in the second region.

[0009] As described above, the technology of the present disclosure aims to provide a vehicle body pillar structure that can suppress a decrease in pillar strength when constructing a vehicle body pillar using a fiber-reinforced resin composite material.

[0010] FIG. 4 is a schematic diagram showing the overall configuration of the vehicle body side structure according to the present embodiment. FIG. 5 is an explanatory diagram showing a center pillar according to the present embodiment. FIG. 6 is an explanatory diagram showing a pillar structure portion of the center pillar according to the present embodiment. FIG. 7 is an explanatory diagram showing an end face of the II cross section of the pillar structure portion shown in FIG. 3. FIG. 8 is an explanatory diagram showing an end face of the II-II cross section of the pillar structure portion shown in FIG. 3. FIG. 9 is an explanatory diagram showing a connecting structure between the pillar structure portion and the side sill according to the present embodiment. FIG. 10 is an explanatory diagram showing a manufacturing method of the pillar structure portion of the center pillar according to the present embodiment. FIG. 11 is an explanatory diagram showing a manufacturing method of the pillar structure portion of the center pillar according to the present embodiment.

[0011] Preferred embodiments of the technology of the present disclosure will be described in detail below with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0012] First, an outline of the vehicle body side structure according to this embodiment will be described. Fig. 1 is a schematic diagram showing the appearance of a vehicle body side structure 1. The vehicle body side structure 1 shown in Fig. 1 schematically shows a portion of the structure of the left side of a vehicle. Fig. 2 is a side view of a center pillar 3 as seen from the outside in the vehicle width direction. As shown in Figs. 1 and 2, in this specification, the fore-and-aft direction of the vehicle body is referred to as the X direction, the vehicle width direction is referred to as the Y direction, and the height direction of the vehicle body is referred to as the Z direction.

[0013] The vehicle body side structure 1 is composed of roof rails 5, rear pillars 4, front pillars 2, center pillars 3, and side sills 6. The roof rails 5 extend in the fore-and-aft direction of the vehicle body above the vehicle interior space, forming the side portions of the vehicle roof. The side sills 6 extend in the fore-and-aft direction of the vehicle body below the sides of the vehicle.

[0014] The front pillar 2 has a lower end connected to the front end of the side sill 6 and an upper end connected to the front end of the roof rail 5. The front pillar 2 forms the front portion that constitutes the cabin space of the vehicle, and is arranged to support the side of the windshield. The rear pillar 4 has a lower end connected to the rear end of the side sill 6 and an upper end connected to the rear end of the roof rail 5. The center pillar 3 has a lower end connected to the center of the side sill 6 in the longitudinal direction of the vehicle body, and an upper end connected to the center of the roof rail 5 in the longitudinal direction of the vehicle body. In this embodiment, the center pillar 3 corresponds to one form of the vehicle body pillar structure of the present disclosure.

[0015] An opening for a front door is formed between the side sill 6, the roof rail 5, the front pillar 2, and the center pillar 3. In addition, an opening for a rear door is formed between the side sill 6, the roof rail 5, the rear pillar 4, and the center pillar 3. Each of the members constituting the vehicle body side structure 1 may be made up of a plurality of members.

[0016] In the vehicle body side structure 1, the center pillar 3 is formed in a columnar shape with its longitudinal direction along the height direction. A first connecting member 14 that covers the connection portion with the side sill 6 is provided at the lower end of the center pillar 3, and a second connecting member 16 that covers the connection portion with the roof rail 5 is provided at the upper end of the center pillar 3.

[0017] The center pillar 3 is configured as a structure in which a pillar structural member is sandwiched and joined between, for example, an outer panel 18 disposed on the outer side in the vehicle width direction and an inner panel (not shown) disposed on the passenger compartment side. The center pillar 3 has flanges 11, 12 on the side surfaces on the front and rear sides of the vehicle body, respectively. The flanges 11, 12 are used, for example, as door stops. The method of forming the flanges 11, 12 on the center pillar 3 is not particularly limited; the flanges 11, 12 may be molded as separate members and joined to the center pillar 3, or the flanges 11, 12 may be provided on either or both of the outer panel 18 and the inner panel (not shown), which are exterior materials.

[0018] The first region 3a in the upper part of the center pillar 3, which includes at least an area corresponding to the height of the occupant's head, functions to prevent the center pillar 3 from breaking during a side collision of the vehicle and protect the occupant's head. On the other hand, the second region 3b in the lower part of the center pillar 3, which includes an area corresponding to the height of the bumper of a passenger car, functions to absorb the collision energy input during a side collision of the vehicle and reduce the impact on the passenger compartment, etc. The second region 3b corresponds to an energy absorption region.

[0019] Next, the configuration of the center pillar 3 as the vehicle body pillar structure according to this embodiment will be described in detail.

[0020] 3 to 6 are diagrams illustrating the configuration of the center pillar 3. Fig. 3 shows a perspective view of a portion of the pillar structure 21 including the connection portion between the center pillar 3 and the side sill 6. Fig. 4 shows a cross-sectional end view of the pillar structure 21 shown in Fig. 3 taken along line II, as viewed in the direction of the arrows, and Fig. 5 shows a cross-sectional end view of the pillar structure 21 shown in Fig. 3 taken along line II, as viewed in the direction of the arrows. Fig. 6 shows a cross-sectional view of the connection portion between the pillar structure 21 and the side sill 6.

[0021] The pillar structure 21 shown in each figure is shown by omitting the first connecting member 14, the second connecting member 16, and the outer panel 18 from the center pillar 3 shown in Figure 2. Each figure shows the front-to-rear direction (X direction) of the vehicle body, the vehicle width direction (Y direction), and the vehicle height direction (Z direction).

[0022] The pillar structure 10 includes a first tubular portion 25a and a second tubular portion 25b. The first tubular portion 25a and the second tubular portion 25b are each made of a fiber-reinforced resin composite material and extend axially along the Z direction, and are arranged side by side in the X direction. The first tubular portion 25a and the second tubular portion 25b are joined together on the upper side in the Z direction. On the other hand, the second tubular portion 25b is branched and spaced apart on the lower side in the Z direction.

[0023] The first tubular portion 25a and the second tubular portion 25b are each provided continuously along the Z direction from the upper end to the lower end of the pillar structure 21. The first tubular portion 25a and the second tubular portion 25b are each made of a fiber-reinforced resin composite material and include continuous fibers oriented, for example, at angles of 0 degrees and ±45 degrees with respect to the Z direction. The pillar structure 21 may include three or more tubular portions as long as it includes the first tubular portion 25a and the second tubular portion 25b arranged in the X direction.

[0024] The first cylindrical portion 25a and the second cylindrical portion 25b each include an inner cylindrical portion 33a (33b), an outer cylindrical portion 34a (34b), a metal plate 35a (35b), and a reinforcing layer 37a (37b). The inner cylindrical portion 33a is the radially inner portion of the first cylindrical portion 25a, and the outer cylindrical portion 34a is the radially outer portion of the first cylindrical portion 25a. The inner cylindrical portion 33b is the radially inner portion of the second cylindrical portion 25b, and the outer cylindrical portion 34b is the radially outer portion of the second cylindrical portion 25b.

[0025] The metal plates 35a, 35b are made of a metal material such as aluminum or steel, and are plate-shaped metal materials extending along the Z direction and the Y direction. In particular, the metal plates 35a, 35b are made of aluminum plates, which can contribute to reducing the weight of the pillar structure portion 21.

[0026] The metal plates 35a, 35b are provided across the first region 3a and the second region 3b, respectively. In the first cylindrical portion 25a, the metal plate 35a is disposed between the inner cylindrical portion 33a and the outer cylindrical portion 34a, which constitute the wall surface on the second cylindrical portion 25b side. In the second cylindrical portion 25b, the metal plate 35b is disposed between the inner cylindrical portion 33b and the outer cylindrical portion 34b, which constitute the wall surface on the first cylindrical portion 25a side.

[0027] Because the metal plates 35a, 35b are provided extending in the Y and Z directions, the strength against a load input in the Y direction is increased compared to when the metal plates 35a, 35b are provided extending in the X and Z directions. Because the fracture strain of the metal plates 35a, 35b is greater than the fracture strain of a fiber-reinforced resin member, even a center pillar 3 made of a fiber-reinforced resin composite material can undergo plastic deformation during a side collision of the vehicle. Therefore, the strength against the input collision load is increased, and fracture of the center pillar 3 can be suppressed.

[0028] The reinforcing layers 37a, 37b are provided across the first region 3a and the second region 3b, respectively. The reinforcing layers 37a, 37b are disposed between the inner tubular portion 33a and the outer tubular portion 34a, which constitute the cabin-side wall surfaces of the first tubular portion 25a and the second tubular portion 25b, respectively. The reinforcing layers 37a, 37b are disposed so as to extend to positions that block the ends of the metal plates 35a, 35b from the cabin.

[0029] For example, the reinforcing layers 37a, 37b are made of a fiber-reinforced resin composite material that includes continuous fibers oriented at least in a direction intersecting the Z direction. The reinforcing layers 37a, 37b include continuous fibers oriented in a direction intersecting the Z direction, and thus have the function of preventing the metal plates 35a, 35b from flying out of the center pillar 3 when a load is applied to the center pillar 3 during a side collision.

[0030] However, the reinforcing layers 37 a, 37 b may be made of a material other than a fiber-reinforced resin composite material as long as the reinforcing layers 37 a, 37 b have the strength to receive the ends of the metal plates 35 a, 35 b. For example, the reinforcing layers 37 a, 37 b may be sheets made of a rubber composite material having the desired elasticity and strength.

[0031] The first cylindrical portion 25a and the second cylindrical portion 25b are clearly distinguished from each other at the wall surfaces where the metal plates 35a, 35b and the reinforcing layers 37a, 37b are arranged, but may be integrated at other wall surfaces.

[0032] As shown in Fig. 4, the pillar structure 21 has, in the first region 3a, a wound layer 31 including continuous fibers wound around the joined first and second tubular portions 25a and 25b. The wound layer 31 has a double structure consisting of a first wound layer 31a on the radially inner side and a second wound layer 31b on the radially outer side. The wound layer 31 functions to integrally hold the pillar structure 21. In the second region 3b, the first tubular portion 25a has the first wound layer 31a wound around the axis, and the second tubular portion 25b has the second wound layer 31b wound around the axis.

[0033] That is, the first wound layer 31a is provided from the first region 3a to the first tubular portion 25a of the second region 3b. The second wound layer 31b is provided from the first region 3a to the second tubular portion 25b of the second region 3b. For example, the first wound layer 31a and the second wound layer 31b contain continuous fibers oriented along directions at angles of 0 degrees and ±45 degrees with respect to the Z direction, respectively.

[0034] In the first region 3a, the winding layer 31 has a double structure including a first winding layer 31a and a second winding layer 31b, and the winding layer 31 in the first region 3a is formed thicker than the first winding layer 31a of the first cylindrical portion 25a and the second winding layer 31b of the second cylindrical portion 25b in the second region 3b. In the first region 3a, the winding layer 31 is provided up to at least a region corresponding to a window shoulder of the side window. In this embodiment, the winding layer 31 is provided up to the upper end portion of the pillar structure portion 21.

[0035] The first wound layer 31a and the second wound layer 31b are clearly distinguished in the second region 3b, but may be integrated in the first region 3a.

[0036] The ends of the first tubular portion 25a and the second tubular portion 25b on the second region 3b side are fitted with fitting portions 7a and 7b provided on the side sill 6, respectively (see FIG. 3). The metal plates 35a and 35b provided on the first tubular portion 25a and the second tubular portion 25b are fastened to the fitting portions 7a and 7b using fastening members 39, respectively (see FIG. 6). The number of fastening members 39 used is not particularly limited.

[0037] The first tubular portion 25a, the second tubular portion 25b, the first winding layer 31a, the second winding layer 31b, and the reinforcing layers 37a, 37b are formed using a fiber-reinforced resin, for example, carbon fiber impregnated with a thermoplastic resin or a thermosetting resin as a matrix resin.

[0038] When the matrix resin is a thermoplastic resin, its main material may be, for example, any one or a mixture of two or more of polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin (acrylonitrile-butadiene-styrene copolymer synthetic resin), polystyrene resin, AS resin (acrylonitrile-styrene copolymer synthetic resin), polyamide resin, polyacetal resin, polycarbonate resin, polyester resin, PPS (polyphenylene sulfide) resin, fluororesin, polyetherimide resin, polyetherketone resin, and polyimide resin. Alternatively, the thermoplastic resin may be a copolymer of the above resins. When a mixture of these thermoplastic resins is used as the matrix resin, a compatibilizer may be further added. Furthermore, a flame retardant such as a bromine-based flame retardant, a silicon-based flame retardant, or red phosphorus may be added to the thermoplastic resin.

[0039] When the matrix resin is a thermosetting resin, its main material may be, for example, one or a mixture of two or more of epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, polyurethane resin, and silicone resin. The thermosetting resin may also contain an appropriate curing agent or reaction accelerator.

[0040] The carbon fibers may contain an appropriate ratio of continuous fibers oriented in the Z direction (axial fibers) and continuous fibers oriented in a direction intersecting the Z direction (cross fibers). The amount of axial fibers can adjust the tensile stress generated by the load input during a side collision. The amount of cross fibers can adjust the rigidity against the input load during a side collision, thereby adjusting the amount of energy absorption. Furthermore, the carbon fibers may contain short fibers in addition to the continuous fibers, and may contain fibers other than carbon fibers as reinforcing fibers.

[0041] The first region 3a and the second region 3b formed by the first tubular portion 25a and the second tubular portion 25b are molded bodies each having a cylindrical shape with a closed cross section, so that the continuity of the fibers can be maintained not only in the axial direction (Z direction) but also in the circumferential direction around the axis, thereby increasing the rigidity against the input load during a side collision.

[0042] The first connecting member 14 and the second connecting member 16 cover the lower end and upper end of the center pillar 3, respectively, and also function to connect the center pillar 3 to the side sill 6 and the roof rail 5. The first connecting member 14 and the second connecting member 16 may be molded products made of, for example, a metal material, but may also be molded products made of other materials.

[0043] In the center pillar 3 having the pillar structure 21 configured as described above, the thickness of the wound layer 31 in the first region 3a is greater than the thicknesses of the first wound layer 31a of the first tubular portion 25a and the second wound layer 31b of the second tubular portion 25b in the second region 3b. The first region 3a is a region that protects the head of an occupant by suppressing bending of the center pillar 3. The wall portion constituting the center pillar 3 in the first region 3a has a relatively large thickness, thereby increasing the rigidity of the center pillar 3 in the first region 3a. This allows the entire first tubular portion 25a and second tubular portion 25b to receive an input load, thereby suppressing bending of the center pillar 3 in the first region 3a.

[0044] On the other hand, the second region 3b is required to absorb the collision load input during a side collision and reduce the impact on the vehicle interior, etc. The wall portions constituting the first tubular portion 25a and the second tubular portion 25b in the second region 3b have a relatively thin layer thickness, and the rigidity of the center pillar 3 in the second region 3b is relatively low. Therefore, in the second region 3b, deformation of the center pillar 3 due to the load input from the outside of the center pillar 3 in the vehicle width direction during a side collision can be concentrated in the second region 3b, and the collision energy can be efficiently absorbed.

[0045] Furthermore, since the first tubular portion 25a and the second tubular portion 25b have the metal plates 35a and 35b extending in the axial direction, respectively, breakage due to input load can be suppressed. Furthermore, since the first tubular portion 25a and the second tubular portion 25b have the reinforcing layers 37a and 37b, respectively, the first tubular portion 25a and the second tubular portion 25b can withstand the load, and the center pillar 3 can be prevented from entering the vehicle interior.

[0046] The lower ends of the first tubular portion 25a and the second tubular portion 25b are fitted into tubular fitting portions 7a, 7b provided on the side sill 6, respectively, and are fastened by fastening members 39 using metal plates 35a, 35b. This increases the connection strength between the pillar structure portion 21 and the side sill 6. It also disperses the stress caused by torsion that occurs at the connection portion between the center pillar 3 and the side sill 6 due to the input load during a side collision. This prevents the center pillar 3 from collapsing toward the passenger compartment.

[0047] Furthermore, the first tubular portion 25a and the second tubular portion 25b are formed continuously from the top to the bottom in the longitudinal direction of the center pillar 3. This provides structural continuity throughout the entire longitudinal direction of the center pillar 3, preventing the center pillar 3 from breaking and from intruding into the vehicle cabin. Furthermore, because the center pillar 3 has a closed cross-section structure with the first wound layer 31a and the second wound layer 31b around it, even when a collision load is input during a side collision, fractures originating from seams or the like are prevented, preventing the center pillar 3 from breaking and from intruding into the vehicle cabin.

[0048] Furthermore, in the second region 3b of the pillar structure 21, the first tubular portion 25a and the second tubular portion 25b are spaced apart from each other. A belt retractor 29, which is a seat belt retractor, can be disposed in the space 27 between the first tubular portion 25a and the second tubular portion 25b (see FIG. 3 ). If the pillar structure were formed from a single tubular portion, an opening would be required to accommodate the belt retractor. However, by disposing the belt retractor 29 in the space 27 between the first tubular portion 25a and the second tubular portion 25b, such an opening is not required. This eliminates the need for an opening. This reduces the number of manufacturing steps and prevents a decrease in strength due to fiber breakage. Furthermore, since the first connecting member 14 is formed as a molded product made of a metal material, the belt retractor 29 can be protected during a side collision.

[0049] Next, an example of a manufacturing method for the pillar structure 21 will be briefly described.

[0050] 7 to 9 are explanatory diagrams showing a manufacturing method of the pillar structure portion 21. First, as shown in Fig. 7, the first tubular portion 25a and the second tubular portion 25b made of fiber-reinforced resin are molded by a known braiding or winding method. Specifically, by using the braiding or winding method, axial fibers are arranged around the periphery of the molding dies for the first tubular portion 25a and the second tubular portion 25b, and cross fibers are wound around them. These continuous fibers are then hardened using a matrix resin to form the inner tubular portions 33a, 33b.

[0051] Next, the metal plates 35a, 35b and the reinforcing layers 37a, 37b are placed in predetermined positions on the inner tubular portions 33a, 33b, and then axial fibers are placed and cross fibers are wound using a braiding method or a filament winding method, and these continuous fibers are hardened using a matrix resin to form the outer tubular portions 34a, 34b.

[0052] Next, as shown in FIG. 8, the first tubular portion 25a and the second tubular portion 25b are joined together at the portion corresponding to the first region 3a, and axial fibers are arranged in the first region 3a and the first tubular portion 25a in the second region 3b by braiding or filament winding, and cross fibers are wound around them to form a first wound layer 31a.

[0053] Next, as shown in Fig. 9, axial fibers are arranged in the first region 3a and the second tubular portion 25b of the second region 3b by braiding or filament winding, and cross fibers are wound around the first region 3a and the second tubular portion 25b to form a second wound layer 31b. The first wound layer 31a and the second wound layer 31b are then cured using a matrix resin to manufacture the pillar structure 21. After the first wound layer 31a is cured using a matrix resin, the second wound layer 31b may be formed and cured.

[0054] In this way, it is possible to efficiently manufacture a pillar structure 21 made of a fiber-reinforced resin composite material containing continuous fibers, which has a first tubular portion 25a and a second tubular portion 25b formed continuously from the top to the bottom in the longitudinal direction of the center pillar 3, and in which the layer thickness of the wall portion of the upper first region 3a is relatively thicker than the layer thickness of the wall portion of the lower second region 3b.

[0055] Although preferred embodiments of the technology of the present disclosure have been described in detail above with reference to the accompanying drawings, the technology of the present disclosure is not limited to these examples. It is clear that a person skilled in the art of the technology to which the present disclosure pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure. Furthermore, combinations of the above-described embodiments and each modified example also naturally fall within the technical scope of the present disclosure.

[0056] For example, in the above embodiment, a center pillar is used as an example of the vehicle body pillar structure, but the technology of the present disclosure may be applied to a front pillar or a rear pillar.

[0057] REFERENCE SIGNS LIST 1: Vehicle body side structure 2: Front pillar 3: Center pillar 3a: First region 3b: Second region 4: Rear pillar 5: Roof rail 6: Side sill 7a, 7b: Fitting portion 10: Pillar structure portion 21: Pillar structure portion 25a: First tubular portion 25b: Second tubular portion 27: Space 29: Belt retractor 31: Winding layer 31a: First winding layer 31b: Second winding layer 39: Fastening member

Claims

1. A vehicle body pillar structure using a fiber-reinforced resin composite material, comprising two tubular sections made of fiber-reinforced resin arranged side by side in the fore-and-aft direction of the vehicle body and each extending in an axial direction along the vehicle body height direction, a first region where the two tubular sections are joined at the upper side in the vehicle body height direction, and a second region where the two tubular sections branch off and are spaced apart at the lower side in the vehicle body height direction.

2. The vehicle body pillar structure according to claim 1, wherein each of the two tubular portions has a metal plate extending across the first region and the second region.

3. The vehicle body pillar structure according to claim 2, wherein the ends of the two tubular portions on the second region side are fitted into fitting portions provided on the side sill, and the metal plate is fastened to the fitting portions by fastening members.

4. The vehicle body pillar structure according to claim 1, wherein the vehicle body pillar structure has, in the first region, a first wound layer and a second wound layer including continuous fibers wound around an axis around the two tubular portions, the first wound layer being provided from the first region to one of the two tubular portions in the second region, and the second wound layer being provided from the first region to the other of the two tubular portions in the second region.

5. The vehicle body pillar structure according to claim 4, wherein the first winding layer and the second winding layer are provided at least in a region corresponding to a window shoulder of a side window in the first region.

6. A vehicle body side structure using a fiber-reinforced resin composite material, comprising: a center pillar having two tubular portions made of fiber-reinforced resin arranged side by side in the fore-and-aft direction of the vehicle body, each extending in an axial direction along the vehicle body height direction, a first region where the two tubular portions are joined at an upper side in the vehicle body height direction, and a second region where the two tubular portions branch off and are spaced apart at a lower side in the vehicle body height direction; and a side sill arranged along the vehicle fore-and-aft direction and to which a lower part of the center pillar is connected, wherein a belt retractor is arranged in the space between the two tubular portions in the second region.

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