Vehicle body structure

A vehicle body structure includes: a first frame that is formed of a first material and has a closed cross section; and a second frame that is formed of a second material and has a closed cross section. The first frame and the second frame are aligned with each other in a vehicle longitudinal direction. The second frame has higher tensile strength and is lighter than the first frame. In a front cross-sectional view of the vehicle, a second center associated with the second frame is located on an outer side in a vehicle width direction from a first center associated with the first frame with respect to vehicle center.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to Japanese App. No. 2020-113839 filed Jul. 1, 2020, the entire content and disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to a vehicle body structure of a vehicle.

BACKGROUND ART

Conventionally, a vehicle body structure, for which a pillar frame formed of an aluminum extruded material is adopted to improve durability and reduce weight of a vehicle body, in which the pillar frame has plural closed cross sections.

More specifically, in a pillar structure disclosed in patent document 1, a front pillar section and a side edge section of a roof are formed of the pillar frame that is formed by extruding an aluminum material. The pillar frame has a cross-sectional shape in which a large cylindrical section and a small cylindrical section facing outward are continuously provided and integrated as two closed cross sections located on the inside of the vehicle body.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY

According to one or more aspects, a vehicle body structure of a vehicle is disclosed or provided. The vehicle body structure can comprise: a first frame that is formed of a first material and has a first closed cross section; and a second frame that is formed of a second material, different from the first material, and has a second closed cross section. The first frame and the second frame can be aligned with each other in a vehicle longitudinal direction, the second frame can have higher tensile strength and is lighter than the first frame, and in a front cross-sectional view of the vehicle, a center associated with the second frame can be located on an outer side in a vehicle width direction from a center associated with the first frame with respect to a vehicle center.

DETAILED DESCRIPTION

A detailed description will hereinafter be made on a preferred embodiment of the present disclosure with reference to the accompanying drawings.

In the above vehicle body structure of the Background Art section, the pillar frame that is formed of the aluminum material and has the plural closed cross sections is used for the vehicle body. However, as a characteristic of the aluminum material, tensile strength thereof against pulling, twisting, and the like can be less than that of a material such as steel. Thus, it is concerned that sufficient steering stability of a vehicle cannot be achieved.

Thus, in order to improve the tensile strength of the vehicle body, it is considered to increase an amount of the aluminum material and enlarging a cross-sectional shape of the pillar frame. However, in these cases, weight reduction of the vehicle body may be inhibited, and improvement in freedom of design of the vehicle body may become difficult due to an increase in an external dimension of the pillar frame.

Embodiments of the present disclosure have been made in view of the above circumstance and other circumstances, and, therefore, can have a purpose, of multiple purposes, of providing a vehicle body structure capable of reducing weight of a vehicle body, improving steering stability, and/or improving freedom of design of the vehicle body.

In order to solve the above problem and other problems, a vehicle body structure according to embodiments of the present disclosure can involve a vehicle body structure of a vehicle that can include: a first frame that is formed of a first material and has a closed cross section; a second frame that is formed of a second material and has a closed cross section. The first frame and the second frame can be aligned with each other in a vehicle longitudinal direction. The second frame can have higher tensile strength and be lighter than the first frame. In a front cross-sectional view of the vehicle, a center of a drawing of the second frame can be located on an outer side in a vehicle width direction from a center of a drawing of the first frame with respect to vehicle center.

With such a configuration, in the vehicle body structure including the first frame and the second frame, which have the closed cross sections, the second frame can have the higher tensile strength and be lighter than the first frame. In the front cross-sectional view of the vehicle, the center of the drawing of the second frame can be located on the outer side in the vehicle width direction from the center of the drawing of the first frame with respect to the vehicle center. In this way, modification of the vehicle body can be suppressed while moment of inertia with respect to the vehicle center can be reduced during travel of the vehicle. Thus, it can be possible to simultaneously reduce weight of the vehicle body and improve steering stability of the vehicle. In addition, a composite frame formed of the first frame and the second frame, which can be lighter and have the higher tensile strength than the first frame, can be adopted. Accordingly, compared to a case where a frame having the plural closed cross sections is formed of only the first material constituting the first frame, it can be possible to suppress an increase in an external dimension while securing the tensile strength. Therefore, it can be possible to improve freedom of design of the vehicle body.

In the vehicle body structure, the first frame can have a polygonal shape having plural sides in the front cross-sectional view of the vehicle, the plural sides can have the at least two outer sides with which a surface constituting an outer circumferential surface of the first frame faces an outer side in the vehicle width direction, and the second frame can include two fixed surfaces that can be fixed to the at least two outer sides.

With such a configuration, it can be possible to efficiently transmit a torsional load and/or a bending load, which may be applied to the first frame during travel of the vehicle, from the at least two outer sides, with which the surface constituting the outer circumferential surface of the first frame faces the outer side in the vehicle width direction of the first frame, to the second frame with the high tensile strength via the at least two fixed surfaces, which can respectively be fixed to the outer sides, in the second frame, that is, by plural transmission paths. As a result, it can be possible to further improve the steering stability of the vehicle.

In the above vehicle body structure, the at least two fixed surfaces can adhere to the at least two outer sides.

With such a configuration, the at least two fixed surfaces of the second frame can adhere to the at least two outer sides of the first frame. In this way, the two different adhesive surfaces can be formed. Accordingly, in the case where the torsional load and/or the bending load may be applied to the first frame, it can be possible to reliably transmit the load from the first frame to the second frame while at least one of the two adhesive surfaces is applied with a shearing load. As a result, it can be possible to further improve the steering stability of the vehicle.

In the vehicle body structure, the first frame can have a rhomboid shape having four sides including the two outer sides in the front cross-sectional view of the vehicle, and the second frame can include the two fixed surfaces that can be fixed to the two outer sides of the first frame.

With such a configuration, the first frame can have the rhomboid cross-sectional shape having the four sides. Thus, the first frame can have a small cross-sectional dimension even with the two outer sides. As a result, the freedom of the design of the vehicle body can be further improved. In addition, it can be possible to efficiently transmit the torsional load and/or the bending load, which may be applied to the first frame during the travel of the vehicle, from the two outer sides of the first frame to the second frame with the high tensile strength via the two fixed surfaces of the second frame by the two transmission paths. As a result, it can be possible to simultaneously achieve further improvement in the freedom of the design of the vehicle body and further improvement in the steering stability of the vehicle.

In the above vehicle body structure, the first frame can be arranged such that, of plural diagonal lines in the cross section of the polygonal shape, the longest diagonal line faces the vehicle vertical direction.

With such a configuration, cross-sectional secondary moment in the vertical direction of the first frame can be the highest. Thus, it can be possible to maximize bending strength of the first frame against the bending load in the vertical direction. Accordingly, it can be possible to improve the bending strength in the vertical direction without increasing the external dimension of the first frame and thus to further improve the freedom of the design of the vehicle body.

According to the vehicle body structure in embodiments of the present disclosure, it can be possible to reduce the weight of the vehicle body, improve the steering stability, and/or improve the freedom of the design of the vehicle body.

A vehicle body structure illustrated inFIGS. 1 to 2is a vehicle body structure of a vehicle1such as an automobile, and can include: a pair of roof rails3constituting an upper portion of a vehicle body2; a front windshield4; a roof panel5; and a pair of doors6attached to both sides of the vehicle body2in a vehicle width direction Y.

Each of the paired roof rails3can have: a roof rail body section3bthat extends in a vehicle longitudinal direction X; and a pillar section3athat extends downward and to vehicle front X1in the vehicle1from a front end of the roof rail body section3b.

The front windshield4can be provided to cover a portion between the pillar sections3aof the paired roof rails3. Each lateral end of the front windshield4can extend upward and to vehicle rear X2along the pillar section3a.

The roof panel5can cover a portion between the roof rail body sections3bof the paired roof rails3and can constitute a ceiling of the vehicle body2. Each lateral end of the roof panel5can extend to the vehicle rear X2along the roof rail body sections3b.

Each of the paired roof rails3can be constructed of a composite frame that is formed from plural types of materials. More specifically, as illustrated inFIGS. 3 to 7, each of the paired roof rails3can be constructed of a first frame11and a second frame12. The first frame11and the second frame12can be aligned in the vehicle width direction Y and a vertical direction Z and can extend in the vehicle longitudinal direction X.

The first frame11can be a long or elongate body (e.g., elongate cylinder or elongate cube) that is formed of a first material, can have a closed cross section11a, and can extend in the longitudinal direction X of the vehicle1. The first frame11may be hollow.

For example, the first frame11can be manufactured by using, as the first material, a metal material, such as aluminum or steel, that is rigid and can be manufactured inexpensively.

The first frame11illustrated inFIGS. 3 to 6can have a polygonal shape having plural sides11b,11c,11d,11ein front cross-sectional view of the vehicle1, and can have a rhomboid shape in this embodiment. In other words, these sides11b,11c,11d,11ecan constitute the closed cross section11ain the rhomboid shape (the polygonal shape).

The plural sides11b,11c,11d,11ecan have a first outer side11band a second outer side11cas at least two outer sides with which a surface constituting an outer circumferential surface of the first frame11can face an outer side Y1in the vehicle width direction. The first outer side11bcan face the outer side Y1in the vehicle width direction of the first frame11and obliquely upward. The second outer side11ccan face the outer side Y1in the vehicle width direction of the first frame11and obliquely downward.

Meanwhile, the second frame12can include at least two fixed surfaces12b1,12b2, which will be described below, as surfaces that can be fixed to the at least two outer sides11b,11c, respectively.

Accordingly, the first frame11can have the at least two outer sides11b,11c, each of which can face outward in the vehicle width direction Y. Thus, compared to a case where only one outer side is provided (for example, only the outer side11bof the first frame11having a rectangular cross section faces the outer side Y1in the vehicle width direction), it can be possible to secure a large area for fixing to the second frame12by adhesion or the like.

As illustrated inFIGS. 3 to 5andFIG. 7, the second frame12can be a long or elongate body that is formed of a second material, can have a closed cross section12a, and can extend in the longitudinal direction X of the vehicle1.

For example, the second frame12can be manufactured by using, as the second material, a reinforced fiber resin, such as CFRP, that is reinforced by carbon fiber. Compared to the metal material, such as aluminum or steel, that is adopted as the above first material, the reinforced fiber resin such as the CFRP can have properties of being lightweight (that is, weight per unit weight (or specific weight) is light) and high tensile strength (further more specifically, rigidity such as torsional rigidity or bending rigidity is high).

The second frame12can have the long or elongate shape having the closed cross section12awhen being cut in the vehicle width direction Y of the vehicle1. The closed cross section12acan be formed of a first frame fixed section12b, an outer surface constituting section12c, and a weather strip attachment section12d. Each of these first frame fixed section12b, outer surface constituting section12c, and weather strip attachment section12dcan be manufactured by using a fiber-reinforced resin material, for instance, in a flat plate shape formed from the CFRP and the like. Each of the fiber-reinforced resin material in the thin plate shape can be oriented such that the reinforced fiber such as the carbon fiber extends in a longitudinal direction (primarily, the vehicle longitudinal direction X) of the second frame12. The second frame12having the closed cross section12acan be manufactured by joining the first frame fixed section12b, the outer surface constituting section12c, and the weather strip attachment section12dat the time of sintering of the carbon fiber, for instance. Due to a structure having the closed cross section12athat is formed of such a fiber-reinforced resin material, the second frame12can have higher tensile strength and can be lighter (that is, weight per unit weight (or specific weight) is lighter) than the first frame11.

The first frame fixed section12bcan include a first fixed surface12b1and a second fixed surface12b2as two fixed surfaces that can be fixed to the two outer sides11b,11cof the first frame11, respectively. That is, the fixed surface12b1can be fixed to the outer side11b, and the fixed surface12b2can be fixed to the outer side11c.

The first fixed surface12b1and the second fixed surface12b2can face different directions and can be orthogonal to each other in this embodiment illustrated inFIGS. 3 to 5.

In this embodiment, as illustrated inFIGS. 3 to 5, the at least two fixed surfaces12b1,12b2of the second frame12can respectively adhere to the at least two outer sides11b,11cof the first frame11.

More specifically, the first fixed surface12b1can oppose the first outer side11b, which can face the outer side Y1in the vehicle width direction of the first frame11and obliquely upward, and can be adhered to the first outer side11bby an adhesive13.

The second fixed surface12b2can oppose the second outer side11c, which can face the outer side Y1in the vehicle width direction of the first frame11and obliquely downward, and can be adhered to the second outer side11cby an adhesive14.

In this embodiment, the adhesives13,14can be separated, but alternatively may be connected.

The outer surface constituting section12ccan be a portion that can be seen from the outside of the vehicle1, and can constitute a part of a design surface of the vehicle1.

The weather strip attachment section12dcan have a fitting concave section12d1(seeFIG. 7) that can face and be opened to the outer side Y1in the vehicle width direction of the vehicle1. The fitting concave section12d1can be a groove that extends in the vehicle longitudinal direction X, and a weather strip that is formed of a long resin material can be attached thereto.

In this embodiment, the weather strip attachment section12dcan be integrally formed in the second frame12, which can prevent a bulge, a seam, or the like that may be otherwise formed at the time when another member is attached. As a result, design quality of the vehicle1can be improved.

The weather strip may be fixed to the fitting concave section12d1by a method other than adhesion such as riveting or by both of adhesion and riveting.

As illustrated inFIGS. 3 to 5, the second frame12can further have a flange section12ethat is formed by projecting the first frame fixed section12band the outer surface constituting section12c, which can constitute the closed cross section12a, to an inner side Y2in the vehicle width direction Y. In a portion on the vehicle front side X1of the second frame12, the flange section12ecan extend in the longitudinal direction (e.g., primarily the vehicle longitudinal direction X) of the second frame12. End portions on both sides of the front windshield4can be fixed to the flange section12eby adhesion or the like.

As illustrated inFIG. 5, in a portion that extends in parallel with the roof panel5in the second frame12, the first frame fixed section12band the outer surface constituting section12c, which can constitute the closed cross section12aof the second frame12, can be projected to the inner side Y2in the vehicle width direction Y from the first upper outer side11bof the first frame11, and an inner extending section12a1of the closed cross section12acan be thereby formed. Meanwhile, a flange section5bthat can be projected to the outer side Y1in the vehicle width direction Y can be formed on each side in the vehicle width direction Y of the roof panel5. The flange section5bcan adhere to a lower surface of the inner extending section12a1of the closed cross section12a. In this way, end portions on both of the sides of the roof panel5can be fixed to the paired roof rails3.

Here, as illustrated inFIG. 5, an upper end portion of the front windshield4can be adhered (directly or indirectly) to an upper surface of the flange section12eof the second frame12and can be adhered (directly or indirectly to a flange section5cthat can be projected to the front of a body section5aof the roof panel5. A front end portion of the flange section5bof the roof panel5can be adhered (directly or indirectly) to a lower surface of the flange section12eof the second frame12.

When the arrangement of the second frame12, which can be configured as described so far, is observed, as illustrated inFIG. 3, in the front cross-sectional view of the vehicle1, a center C2(e.g., as shown in the drawing) of the second frame12can be located on the outer side Y1in the vehicle width direction from a center C1(e.g., as shown the drawing) of the first frame11with respect to a vehicle center CL (that is, a center line of the vehicle1in the vehicle width direction Y illustrated inFIG. 2).

Here, the “front cross-sectional view” can mean cross-sectional view in which cross sections of the first frame11and the second frame12in extending directions thereof are seen from the front of the vehicle. The center C1(e.g., as shown in the drawing) can mean center (center of gravity) of the cross section in the vehicle width direction of the first frame11. The center C2(e.g., as shown in the drawing) can mean center (center of gravity) of the cross section in the vehicle width direction of the second frame12.

As illustrated inFIG. 2, a position of the vehicle center CL in the vehicle width direction Y can be located at center of the vehicle1when seen from the front of the vehicle, and can be the same as a center of gravity G of the vehicle1.

The center C2of the drawing of the second frame12in this embodiment can be located on an upper side of the center C1of the drawing of the first frame11in the vertical direction Z, but alternatively may be located at the same height as or below the center C1of the drawing of the first frame11.

As illustrated inFIGS. 3 to 5, the vehicle body structure in this embodiment is the vehicle body structure of the vehicle1and can include: the first frame11that can be formed of the first material such as aluminum or steel and that can have the closed cross section11a; and the second frame12that can be formed of the second material such as the CFRP that can differ from the first material and can have the closed cross section12a. The first frame11and the second frame12can be aligned in the vehicle width direction Y and the vertical direction Z and extend in the vehicle longitudinal direction X. The second frame12can have a higher tensile strength and be lighter than the first frame11. As illustrated inFIG. 3, in the front cross-sectional view of the vehicle1, the center C2of the drawing of the second frame12can be located on the outer side Y1in the vehicle width direction from the center C1of the drawing of the first frame11with respect to the vehicle center CL.

With such a configuration, in the vehicle body structure including the first frame11and the second frame12, which can be formed of the different materials and can have the closed cross sections11a,12a, the second frame12can have the higher tensile strength and be lighter than the first frame11. In the front cross-sectional view of the vehicle, the center C2of the drawing of the second frame12can be located on the outer side Y1in the vehicle width direction from the center C1of the drawing of the first frame11with respect to the vehicle center CL (the center line of the vehicle1in the vehicle width direction Y inFIG. 2). In this way, modification of the vehicle body can be suppressed while moment of inertia with respect to the vehicle center CL can be reduced during travel of the vehicle1. Thus, it can be possible to simultaneously reduce weight of the vehicle body and improve steering stability of the vehicle1. In addition, the composite frame formed of the first frame11and the second frame12, which can be lighter and can have the higher tensile strength than the first frame11, can be adopted. Accordingly, compared to a case where a frame having the plural closed cross sections is formed of only the first material constituting the first frame11, it can be possible to suppress an increase in an external dimension while securing the tensile strength. Therefore, it can be possible to improve the freedom of the design of the vehicle body.

In other words, in the vehicle body structure in this embodiment, it can be possible to reduce the moment of inertia of the vehicle body with respect to the vehicle center CL by arranging the second frame12, which can be the lighter member, away from the vehicle center CL. In addition, since the second frame12can be located away from the vehicle center CL, cross-sectional secondary moment of the second frame12with respect to the vehicle center CL can be increased, and the tensile strength of the second frame12can be high. Thus, it can be possible to suppress torsional deformation of the vehicle body and improve the steering stability.

In the vehicle body structure in this embodiment, as illustrated inFIGS. 3 to 5, the first frame11can have the polygonal shape (e.g., the rhomboid shape in this embodiment) having the plural sides11b,11c,11d,11ein the front cross-sectional view of the vehicle1. The plural sides11b,11c,11d,11ecan have the at least two outer sides11b,11cwith which the surface constituting the outer circumferential surface of the first frame11can face the outer side Y1in the vehicle width direction. The second frame12can include the at least two fixed surfaces12b1,12b2that can be fixed to the at least two outer sides11b,11c, respectively. That is, the fixed surface12b1can be fixed to the outer side11b, and the fixed surface12b2can be fixed to the outer side11c.

With such a configuration, it can be possible to efficiently transmit a torsional load or a bending load, which may be applied to the first frame11during the travel of the vehicle1, from the at least two outer sides11b,11c, with which the surface constituting the outer circumferential surface of the first frame11can face the outer side in the vehicle width direction Y of the first frame11, to the second frame12with the high tensile strength via the at least two fixed surfaces12b1,12b2, which can respectively be fixed to the outer sides11b,11c, in the second frame12, that is, by plural transmission paths. As a result, it can be possible to further improve the steering stability of the vehicle1.

In the vehicle body structure in this embodiment, as illustrated inFIGS. 3 to 5, the at least two fixed surfaces12b1,12b2respectively can be adhered (directly or indirectly) to the at least two outer sides11b,11c.

With such a configuration, the at least two fixed surfaces12b1,12b2of the second frame12can be separately adhere to the at least two outer sides11b,11cof the first frame11. In this way, the two different adhesive surfaces can be formed. Accordingly, in the case where the torsional load or the bending load is applied to the first frame11, it can be possible to reliably transmit the load from the first frame11to the second frame12while at least one of the two adhesive surfaces is applied with a shearing load. As a result, it can be possible to further improve the steering stability of the vehicle1.

In the vehicle body structure in this embodiment, as illustrated inFIGS. 3 to 5, the first frame11can have the rhomboid shape having the four sides11b,11c,11d,11eincluding the two outer sides11b,11cin the front cross-sectional view of the vehicle1.

The second frame12can include the two fixed surfaces12b1,12b2that can be fixed to the two outer sides11b,11cof the first frame11, respectively.

With such a configuration, the first frame11can have the rhomboid cross-sectional shape having the four sides11b,11c,11d,11e. Thus, the first frame11can have the small cross-sectional dimension even with the two outer sides11b,11c. As a result, the freedom of the design of the vehicle body can be further improved. In addition, it can be possible to efficiently transmit the torsional load and/or the bending load, which may be applied to the first frame11during the travel of the vehicle1, from the two outer sides11b,11cof the first frame11to the second frame12with the high tensile strength via the two fixed surfaces12b1,12b2of the second frame12by the two transmission paths. As a result, it can be possible to simultaneously achieve further improvement in the freedom of the design of the vehicle body and further improvement in the steering stability of the vehicle1.

In the vehicle body structure in this embodiment, as illustrated inFIG. 8, the first frame11can be arranged such that, of plural diagonal lines in the cross section of the polygonal shape (that is, the closed cross section11a), a longest diagonal line L can face the vehicle vertical direction Z.

With such a configuration, the cross-sectional secondary moment in the vertical direction Z of the first frame11can be the highest. Thus, it can be possible to maximize bending strength of the first frame11against the bending load in the vertical direction Z. Accordingly, it can be possible to improve the bending strength in the vertical direction Z without increasing the external dimension of the first frame11and thus to further improve the freedom of the design of the vehicle body.

Here, a magnitude of stress that is applied to the four sides11b,11c,11d,11e, which constitute the closed cross section11aof the first frame11, at the time when the torsional load and the bending load are applied to the first frame11in this embodiment can be considered.

For example, in the case where the torsional load that is applied to the first frame11at the time of turning during the travel of the vehicle is assumed and, as illustrated inFIG. 9, the torsional load is applied to the first frame11having the rhomboid closed cross section11ain a downward direction on the outer side Y1in the vehicle width direction Y, that is, in a counterclockwise direction, the highest tensile stress can be applied to the upper outer side11b, slightly high compressive stress can be applied to the lower outer side11c, the low tensile stress can be applied to the upper inner side11d, and the lowest compressive stress can be applied to the lower inner side11e.

Next, as illustrated inFIG. 10, in the case where the bending load is applied to the first frame11in a direction toward the inner side Y2in the vehicle width direction Y, the highest tensile stress can be applied to the upper outer side11b, the slightly high tensile stress can be applied to the lower outer side11c, the low compressive stress can be applied to the upper inner side11d, and the lowest compressive stress can be applied to the lower inner side11e.

It is understood that, in the case where the torsional load and the bending load are applied to the first frame11as illustrated inFIGS. 9 to 10above, both of the high tensile stress and the high compressive stress can be applied to the outer sides11b,11c, and in particular, the highest tensile stress can be applied to the first outer side11bon the upper side.

When this experiment result is considered, the first frame11can be reinforced by the second frame12by causing the first fixed surface12b1and the second fixed surface12b2to respectively adhere to the two outer sides11b,11cof the first frame11, and it thus can be possible to exert high rigidity against the torsional load and the bending load.

MODIFIED EXAMPLES

A tip of the first fixed surface12b1of the second frame12illustrated inFIG. 3can be located in a region on the left side of the first upper outer side11bof the first frame11(the outer side Y1in the vehicle width direction Y). However, embodiments of the present disclosure are not limited thereto.

As a modified example, as illustrated inFIG. 11, the tip of the first fixed surface12b1may be extended to an end portion on the right side (the inner side Y2in the vehicle width direction Y) of the first outer side11b, and the closed cross section12aof the second frame12may thereby be expanded to an entire range of the first outer side11b.

In this configuration of the second frame12illustrated inFIG. 11, the closed cross section12acan be expanded to the entire range of the first outer side11b. Thus, the effect of the closed cross section12ato reinforce the flange section12ecan be increased. As a result, it can be possible to reduce a width of the flange section12ewhile securing support rigidity for the front windshield4. In this way, it can be possible to relieve visual obstruction (more specifically, an obstruction angle) of the roof rails3on both of the sides in the vehicle width direction Y of the front windshield4.

In embodiments of the present disclosure, as long as the cross-sectional shape of the closed cross section of the first frame is the polygonal shape, the cross-sectional shape thereof may be a hexagonal cross sectional shape as illustrated inFIG. 12, for example. That is, a vehicle body structure in the modified example illustrated inFIG. 12includes a first frame21and a second frame22.

The first frame21can be formed of the first material that is the metal material such as aluminum or steel, and can be in a shape having a hexagonal closed cross section21a. The closed cross section21acan have three outer sides21b,21c,21dthat can face the outer side Y1in the vehicle width direction Y.

Meanwhile, the second frame22can be formed of the second material, such as the CFRP, that differs from the first material, and can be a member having a closed cross section22a. The second frame22can have the higher tensile strength and can be lighter than the first frame21. The second frame22can have a first frame fixed section22bthat can be fixed to the first frame21. The first frame fixed section22bcan constitute a part of the closed cross section22a. The first frame fixed section22bcan have fixed surfaces22b1,22b2,22b3that can respectively oppose the three outer sides21b,21c,21dof the first frame21. These three fixed surfaces22b1,22b2,22b3respectively can be adhered to the three outer sides21b,21c,21d, for instance, by adhesives23,24,25. These adhesives23,24,25may be separate or connected.

With the configuration in the modified example illustrated inFIG. 12, it can be possible to efficiently transmit the torsional load and/or the bending load, which may be applied to the first frame21during the travel of the vehicle1, from the three outer sides21b,21c,21d, which can face the outer side Y1in the vehicle width direction Y, in the first frame21to the second frame22with the high tensile strength via the three fixed surfaces22b1,22b2,22b3, which can respectively be fixed to the outer sides21b,21c,21d, in the second frame22, that is, by the three transmission paths. As a result, it can be possible to further improve the steering stability of the vehicle1.

In addition, as noted above, the three fixed surfaces22b1,22b2,22b3of the second frame22separately can be adhered to the three outer sides21b,21c,21dof the first frame21. In this way, the three different adhesive surfaces can be formed. Accordingly, in the case where the torsional load and/or the bending load is applied to the first frame21, it can be possible to reliably transmit the load(s) from the first frame21to the second frame22while at least one of the three adhesive surfaces is applied with the shearing load. As a result, it can be possible to further improve the steering stability of the vehicle1.

The shape of the closed cross section of the first frame may only need to have the at least two outer sides that face the different directions, and may be a circular closed cross-sectional shape instead of the polygonal cross-sectional shape. However, in the case of the circular closed cross-sectional shape, a joint surface between the first frame and the second frame is an arc surface, and a direction of an end portion of the arc surface is orthogonal to a joint direction. As a result, it may become difficult to control a film thickness of the adhesive. Accordingly, as in the above embodiment, it is noted that the control of the film thickness of the adhesive may be easier with the polygonal closed cross-sectional shape of the first frame than with the circular closed cross-sectional shape thereof.

In one or more embodiments of the present disclosure, the second frame, which can have the higher tensile strength and can be lighter than the first frame, may only need to be arranged on the farther side from the center of gravity of the vehicle than the first frame. The second frame may only need to be arranged farther from the center of gravity G than the first frame not only when seen in the cross section in the vehicle width direction Y illustrated inFIGS. 2 to 5as in the above embodiment, but also when seen in a cross section in another direction.

In the above embodiment, the description has been made on the example of the roof rail including the first frame and the second frame. However, embodiments of the present disclosure are not limited thereto. Embodiments of the present disclosure can also be applied to another member as long as such a member constitutes the vehicle body. Thus, it can be possible to apply embodiments of the present disclosure not only to the pillar but also to the side sill.