Automobile roof structure

Abstract

This automobile roof structure comprises an outer panel, a pair of roof rails connected to the outer panel, and a plurality of connecting members connecting the pair of roof rails. The plurality of connecting members include: three main connecting members respectively disposed in a front end position and a rear end position of the roof rail in the vehicle front-rear direction, and in an intermediate position on the front side of the center; and sub-connecting members disposed between the three main connecting members in the vehicle front-rear direction. A front-side sub-connecting member is disposed between the intermediate position and the front end position as a sub-connecting member, and a rear-side sub-connecting member is disposed between the intermediate position and the rear end position as a sub-connecting member. The number of the rear-side sub-connecting members is larger than the number of the front-side sub-connecting members, and the main connecting members are formed of a material having a tensile strength greater than that of the sub-connecting members. The outer panel has a plate thickness of 0.6 mm or less.

Description

Roof structure of a motor vehicle

[0001] The present invention relates to a roof structure of a motor vehicle. This application claims priority based on Japanese Patent Application No. 2024-190470 filed in Japan on October 30, 2024, the content of which is incorporated herein by reference.

[0002] As a roof structure of a motor vehicle, a plurality of roof cross members are provided at intervals in the vehicle front-rear direction, and plate-shaped dynamic dampers are provided on adjacent roof cross members to suppress the resonance of the outer panel by the dynamic dampers (see, for example, Patent Document 1).

[0003] On the other hand, in an automobile manufacturing company, various automobile body parts such as door outer panels, hood outer panels, and back door panels of automobiles are manufactured by press-forming thin plate materials. In these outer panels, efforts have been made to reduce the weight by thinning the plate thickness from the perspective of weight reduction of automobiles for CO ２ emissions reduction. For example, in order to reduce the weight of automobiles, the development of technologies to strengthen the roof outer panel has been promoted.

[0004] Japanese Patent Application Laid-Open No. 2013-103651

[0005] However, when the roof outer panel is thinned for weight reduction, a problem arises in the reduction of the tension rigidity in the outer panel. In addition, the reduction of the tension rigidity due to the thinning of the outer panel also leads to a reduction in the natural frequency of the outer panel. Therefore, there is a concern that the noise entering the vehicle interior will increase due to the resonance of the outer panel caused by the vibration generated during the running of the automobile.

[0006] An object of the present disclosure is to provide a roof structure of a motor vehicle that can suppress the reduction of tension rigidity and the reduction of natural frequency accompanying the thinning of the outer panel.

[0007] To solve the aforementioned problems, the present disclosure proposes the following means: (1) One aspect of the present disclosure is a roof structure for an automobile comprising an outer panel, a pair of roof rails connected to the outer panel, and a plurality of connecting members connecting the pair of roof rails. The plurality of connecting members include three main connecting members positioned at the front end position, the rear end position, and an intermediate position forward of the center of the roof rails in the longitudinal direction of the vehicle, and sub-connecting members positioned between each of the three main connecting members in the longitudinal direction of the vehicle. A front sub-connecting member is positioned between the intermediate position and the front end position as the sub-connecting member, and a rear sub-connecting member is positioned between the intermediate position and the rear end position as the sub-connecting member, the number of rear sub-connecting members being greater than the number of front sub-connecting members, and the main connecting members being made of a material with greater tensile strength than the sub-connecting members. The outer panel has a plate thickness of 0.6 mm or less.

[0008] (2) In the roof structure of the automobile described in (1) above, only one of the front side auxiliary connecting members may be provided.

[0009] (3) In the roof structure of the automobile described in (2) above, the width of the front side auxiliary connecting member in the vehicle longitudinal direction may be greater than the width of the rear side auxiliary connecting member in the vehicle longitudinal direction.

[0010] (4) In the roof structure of an automobile described in any one of the above paragraphs (1) to (3), the sub-connecting member may have a smaller dimension in the vertical direction of the vehicle than the main connecting member at the front end position and the main connecting member at the rear end position.

[0011] (5) In the roof structure of an automobile described in any one of the above items (1) to (4), the intermediate position may be the connection position between the roof rail and the center pillar. (6) In the roof structure of an automobile described in any one of the above items (1) to (5), the main connecting member located at the intermediate position forward of the center may have a smaller dimension in the vehicle vertical direction than the main connecting member at the front end position, the main connecting member at the rear end position, and the sub-connecting member.

[0012] According to the roof structure of the automobile disclosed herein, it is possible to suppress the decrease in tension stiffness and decrease in natural frequency that occur when the outer panel is made thinner.

[0013] This is a plan view of the roof structure of one embodiment of the present disclosure, as seen from the passenger compartment side. This is a cross-sectional view taken along the line II-II in Figure 1. This is a cross-sectional view taken along the line III-III in Figure 1. This is a cross-sectional view taken along the line IV-IV in Figure 1. This is a schematic diagram showing the state in which a load is applied to the first and second parts of the outer panel in one embodiment. This is a graph showing the load and deflection amount at the first part of the outer panel in one embodiment. This is a graph showing the load and deflection amount at the second part of the outer panel in one embodiment. This is a graph showing the deflection amount and load at the first to sixth parts of the outer panel in one embodiment.

[0014] The roof structure of the automobile according to the embodiment will be described below with reference to the drawings. Hereinafter, the roof structure of the automobile may be simply referred to as the "roof structure". In the drawings, the front-rear direction of the vehicle is indicated by the arrow FRONT-REAR, the left-right direction of the vehicle (vehicle width direction) is indicated by the arrow LEFT-RIGHT, and the up-down direction of the vehicle (vehicle height direction) is indicated by the arrow UP-DOWN.

[0015] (Roof Structure) Figure 1 is a plan view of the roof structure as seen from the passenger compartment side. As shown in Figure 1, the roof structure 10 comprises an outer panel 12, a pair of roof rails 14, and a plurality of connecting members 20. The outer panel 12 and the plurality of connecting members 20 are connected, for example, by adhesive. The outer panel 12 and the pair of roof rails 14 are connected, for example, by spot welding. The plurality of connecting members 20 and the pair of roof rails 14 are connected, for example, by spot welding.

[0016] (Outer Panel) The outer panel 12 is a plate-shaped member having a convex curved surface directed upward toward the vehicle body. The outer panel 12 is formed by press-forming a metal plate such as a steel plate. From the viewpoint of weight reduction, the thickness of the outer panel 12 is 0.6 mm or less, and preferably 0.5 mm or less. The outer panel 12 has tension rigidity ensured by a plurality of connecting members 20, thereby suppressing the decrease in the natural frequency of the outer panel 12 that occurs when it is made thinner. As a result, the outer panel 12 is lightweight despite its thin thickness, while exhibiting excellent tension rigidity, and resonance of the outer panel due to vibrations generated when the vehicle is running can be suppressed. The area of ​​the outer panel 12 is not particularly limited, but for example, the length in the front-rear direction of the vehicle is preferably 1500 mm or more, and the length in the left-right direction of the vehicle is preferably 1000 mm or more.

[0017] (Roof Rails) A pair of roof rails 14 are positioned on the left and right sides of the outer panel 12. The pair of roof rails 14 are members attached to the lower surface of the outer panel 12 and are positioned on both sides in the width direction of the vehicle body, extending in the front-rear direction of the vehicle. The roof rails 14 may be, for example, long, hollow members formed from a metal plate such as a steel plate. The upper end of a pillar (not shown) is connected to the lower surface of the roof rails 14.

[0018] Specifically, in the longitudinal direction of the vehicle, the upper end of a front pillar (not shown) is connected to the front end position 14a of the pair of roof rails 14. The upper end of a rear pillar (not shown) is connected to the rear end position 14b of the pair of roof rails 14. The upper end of a center pillar (not shown) is connected to the intermediate position 14c of the pair of roof rails 14. That is, the intermediate position 14c is the connection point between the pair of roof rails 14 and the center pillar. The pair of front pillars, the pair of rear pillars, and the pair of center pillars are rigid support columns that rise from the floor of the vehicle on the left and right sides of the vehicle. The pair of roof rails are connected by a plurality of connecting members 20.

[0019] (Connecting Members) The multiple connecting members 20 comprise three reinforcements (main connecting members) 21, 22, and 23, and multiple roof cross members (sub-connecting members) 24, 25, 26, and 27. The three reinforcements 21, 22, and 23 are made of a material with greater tensile strength than the multiple roof cross members 24, 25, 26, and 27. The method for measuring tensile strength is not particularly limited as long as the measurement conditions for the tensile strength of the reinforcements and the tensile strength of the roof cross members are equivalent. The thickness of each of the three reinforcements 21, 22, and 23 is set to be thicker than the thickness of each of the multiple roof cross members 24, 25, 26, and 27. The connecting members 20 have a cross-sectional shape that protrudes toward the passenger compartment, thereby enhancing the reinforcing effect of the roof structure 10.

[0020] (Reinforcement) The three reinforcements 21, 22, and 23 are members that are attached to the lower surface of the outer panel 12, for example by a mastic sealer, and are arranged to extend in the width direction of the vehicle body. Examples of mastic sealers include resin-based adhesives mainly composed of synthetic rubber. The three reinforcements 21, 22, and 23 reinforce the roof structure 10 by connecting the pair of roof rails 14 together. The three reinforcements 21, 22, and 23 can be obtained, for example, by press-forming a metal plate such as a steel plate. The three reinforcements 21, 22, and 23 are formed in a hat-shaped cross section, as will be described later. In order to increase the bending strength of the three reinforcements 21, 22, and 23, it is preferable that the reinforcements be members with a hat-shaped cross section, but the three reinforcements 21, 22, and 23 may be, for example, flat plate-shaped members. The three reinforcements 21, 22, and 23 consist of a first reinforcement 21, a second reinforcement 22, and a third reinforcement 23.

[0021] The first reinforcement 21 is connected to the front end position 14a of a pair of roof rails 14 in the longitudinal direction of the vehicle. The first reinforcement 21 is a hat-shaped cross section member consisting of a pair of flanges 21a, a pair of side walls 21b that bend and extend from the edges of the pair of flanges 21a, and a bottom wall 21c that connects the edges of the pair of side walls 21b.

[0022] The second reinforcement 22 is connected to the rear end position 14b of a pair of roof rails 14 in the longitudinal direction of the vehicle. The second reinforcement 22 is a hat-shaped cross section member consisting of a pair of flanges 22a, a pair of side walls 22b that bend and extend from the edges of the pair of flanges 22a, and a bottom wall 22c that connects the edges of the pair of side walls 22b.

[0023] Figure 2 is a cross-sectional view taken along the line II-II in Figure 1. As shown in Figures 1 and 2, the third reinforcement 23 is connected to an intermediate position 14c of a pair of roof rails 14 in the longitudinal direction of the vehicle. The intermediate position 14c is located forward of the center in the longitudinal direction of the vehicle. The third reinforcement 23 is a member consisting of a pair of flanges 23a, a pair of side walls 23b extending from the edges of the pair of flanges 23a, and a bottom wall 23c connecting the edges of the pair of side walls 23b, with a portion of it formed in a hat-shaped cross section. The front flange 23a is formed in a stepped cross section consisting of a bottom wall 23a1, a side wall 23ab extending from the edge of the bottom wall 23a1, and a top wall 23a2 extending from the side wall 23ab.

[0024] The third reinforcement 23 has, for example, a width W1 in the vehicle's longitudinal direction set to 130 mm. The width W1 is the distance between the front and rear ends of a pair of flanges 23a in the vehicle's longitudinal direction. In this embodiment, since the third reinforcement 23 is a member that has the same width dimension at any position in the vehicle's lateral direction, the width W1 may be the width dimension of the third reinforcement 23 at any position in the vehicle's lateral direction. If the third reinforcement 23 has different width dimensions depending on its position in the vehicle's lateral direction, the width W1 (and widths W2 to W5 described later) is the width dimension measured at the center in the vehicle's lateral direction. For example, when the width W1 of the third reinforcement 23 is 130 mm, the width of the front flange 23a is set to 60 mm, the width of the rear flange 23a is set to 20 mm, and the height (dimension in the vehicle's vertical direction) is set to 10 mm. In this application, the height of the connecting member 20 is the maximum length in the vehicle vertical direction between the intersection point of the rear side wall 23b and the adjacent rear flange 23a and the intersection point of the rear side wall 23b and the adjacent bottom wall 23c, as shown in the example in Figure 2. The third reinforcement 23 is set to have a smaller dimension in the vehicle vertical direction than the first reinforcement 21 and the second reinforcement 22. This is preferable from the viewpoint of securing passenger compartment space. Furthermore, the third reinforcement 23 may also be set to have a smaller dimension in the vehicle vertical direction than the multiple roof cross members 24, 25, 26, and 27 described later, which is even more preferable from the viewpoint of securing passenger compartment space.

[0025] (Roof Cross Members) As shown in Figure 1, the multiple roof cross members 24, 25, 26, and 27 are positioned between the three reinforcements 21, 22, and 23 in the longitudinal direction of the vehicle. The multiple roof cross members 24, 25, 26, and 27 are components attached to the lower surface of the outer panel 12, for example by a mastic sealer, and are arranged to extend in the width direction of the vehicle body. Examples of mastic sealers include resin-based adhesives mainly composed of synthetic rubber. The multiple roof cross members 24, 25, 26, and 27 reinforce the outer panel 12 by connecting pairs of roof rails 14 together.

[0026] The multiple roof cross members 24, 25, 26, 27 can be obtained, for example, by press forming a metal sheet such as a steel plate. The multiple roof cross members 24, 25, 26, 27 are formed in a hat-shaped cross section, as will be described later. In the multiple roof cross members 24, 25, 26, 27, the dimensions in the vehicle's vertical direction are set to be smaller than those of the first reinforcement 21 and the second reinforcement 22. In order to increase the bending strength of the multiple roof cross members 24, 25, 26, 27, it is preferable that the roof cross members be hat-shaped cross section members, but the roof cross members may also be, for example, flat plate-shaped members.

[0027] The multiple roof cross members 24, 25, 26, and 27 are composed of a front roof cross member (front auxiliary connecting member) 24 and multiple rear roof cross members (rear auxiliary connecting members) 25, 26, and 27. The number of multiple rear roof cross members 25, 26, and 27 is set to be greater than the number of front roof cross members 24.

[0028] Figure 3 is a cross-sectional view taken along the line III-III in Figure 1. As shown in Figures 1 and 3, there is only one front roof cross member 24 positioned between the intermediate position 14c and the front end position 14a in the longitudinal direction of the vehicle. That is, the front roof cross member 24 is positioned between the third reinforcement 23 and the first reinforcement 21 and is connected to a pair of roof rails 14. The front roof cross member 24 is a hat-shaped cross section member consisting of a pair of flanges 24a, a pair of side walls 24b that bend and extend from the edges of the pair of flanges 24a, and a bottom wall 24c that connects the edges of the pair of side walls 24b.

[0029] The front roof cross member 24 has a width W2 of 150 mm in the vehicle's longitudinal direction. The width W2 is the distance between the front and rear ends of a pair of flanges 24a in the vehicle's longitudinal direction. The width W2 of the front roof cross member 24 is set to be larger than the widths W3 to W5 of the multiple rear roof cross members 25, 26, and 27, which will be described later, in the vehicle's longitudinal direction. Therefore, even by placing only one front roof cross member 24 between the third reinforcement 23 and the first reinforcement 21, the distance L1 of the first part 12a and the distance L2 of the second part 12b, which will be described later, can be appropriately set. For example, when the width W2 of the front roof cross member 24 is 150 mm, the width of the flange 24a is set to 20 mm and the height to 15 mm. The dimensions of the front roof cross member 24 are set to be smaller in the vehicle's vertical direction than the first reinforcement 21 and the second reinforcement 22. Distances L1 and L2 (and distances L3 to L6, described later) are distances measured at the center of the connecting member 20 in the width direction (vehicle left-right direction).

[0030] The front roof cross member 24 is positioned at a distance L1 rearward from the first reinforcement 21 in the longitudinal direction of the vehicle. The front roof cross member 24 is positioned at a distance L2 forward from the third reinforcement 23 in the longitudinal direction of the vehicle. The outer panel 12 is divided into a first portion 12a by the first reinforcement 21 and the front roof cross member 24, and a second portion 12b by the front roof cross member 24 and the third reinforcement 23. For example, the distance L1 of the first portion 12a is set to 153 mm. For example, the distance L2 of the second portion 12b is set to 138 mm.

[0031] Multiple rear roof cross members 25, 26, and 27 are positioned between an intermediate position 14c and a rear end position 14b in the longitudinal direction of the vehicle. The multiple rear roof cross members 25, 26, and 27 consist of a first rear roof cross member 25, a second rear roof cross member 26, and a third rear roof cross member 27.

[0032] The first rear roof cross member 25 is positioned between the third reinforcement 23 and the second rear roof cross member 26 (described later) and is connected to a pair of roof rails 14. The first rear roof cross member 25 is a hat-shaped cross section member consisting of a pair of flanges 25a, a pair of side walls 25b that bend and extend from the edges of the pair of flanges 25a, and a bottom wall 25c that connects the edges of the pair of side walls 25b.

[0033] The first rear roof cross member 25 has a width W3 in the vehicle longitudinal direction set to 90 mm, for example. The width W3 is the distance between the front and rear ends of a pair of flanges 25a in the vehicle longitudinal direction. The width W3 of the first rear roof cross member 25 is set to be smaller than the width W2 of the front roof cross member 24. The dimensions of the first rear roof cross member 25 in the vehicle vertical direction are set to be smaller than those of the first reinforcement 21 and the second reinforcement 22.

[0034] The first rear roof cross member 25 is positioned at a distance L3 rearward from the third reinforcement 23 in the vehicle's longitudinal direction. The outer panel 12 is partitioned into a third portion 12c by the third reinforcement 23 and the first rear roof cross member 25. The distance L3 of the third portion 12c is set to, for example, 182 mm.

[0035] Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 1. As shown in Figures 1 and 4, the second rear roof cross member 26 is positioned between the first rear roof cross member 25 and the third rear roof cross member 27 (described later), and is connected to a pair of roof rails 14. The second rear roof cross member 26 is a hat-shaped cross-sectional member consisting of a pair of flanges 26a, a pair of side walls 26b that bend and extend from the edges of the pair of flanges 26a, and a bottom wall 26c that connects the edges of the pair of side walls 26b.

[0036] The second rear roof cross member 26 has a width W4 in the vehicle longitudinal direction set to 80 mm, for example. The width W4 is the distance between the front and rear ends of a pair of flanges 26a in the vehicle longitudinal direction. The width W4 of the second rear roof cross member 26 is set to be smaller than the width W2 of the front roof cross member 24. For example, when the width W4 of the second rear roof cross member 26 is 80 mm, the width of the flanges 26a is set to 20 mm and the height to 15 mm. The dimensions of the second rear roof cross member 26 in the vehicle vertical direction are set to be smaller than those of the first reinforcement 21 and the second reinforcement 22.

[0037] The second rear roof cross member 26 is positioned at a distance L4 behind the first rear roof cross member 25 in the longitudinal direction of the vehicle. The outer panel 12 is divided into a fourth section 12d by the first rear roof cross member 25 and the second rear roof cross member 26. For example, the distance L4 of the fourth section 12d is set to 182 mm.

[0038] As shown in Figure 1, the third rear roof cross member 27 is positioned between the second rear roof cross member 26 and the second reinforcement 22 and is connected to a pair of roof rails 14. The third rear roof cross member 27 is a hat-shaped cross section member consisting of a pair of flanges 27a, a pair of side walls 27b that bend and extend from the edges of the pair of flanges 27a, and a bottom wall 27c that connects the edges of the pair of side walls 27b.

[0039] The third rear roof cross member 27 has, for example, a width W5 in the vehicle's longitudinal direction set to 90 mm. The width W5 is the distance between the front and rear ends of a pair of flanges 27a in the vehicle's longitudinal direction. The width W5 of the third rear roof cross member 27 is set to be smaller than the width W2 of the front roof cross member 24. The third rear roof cross member 27 has a smaller dimension in the vehicle's vertical direction than the first reinforcement 21 and the second reinforcement 22.

[0040] The third rear roof cross member 27 is positioned at a distance L5 rearward from the second rear roof cross member 26 in the longitudinal direction of the vehicle. The third rear roof cross member 27 is positioned at a distance L6 forward from the second reinforcement 22 in the longitudinal direction of the vehicle. The outer panel 12 is divided into a fifth section 12e by the second rear roof cross member 26 and the third rear roof cross member 27, and a sixth section 12f by the third rear roof cross member 27 and the second reinforcement 22. For example, the distance L5 of the fifth section 12e is set to 182 mm. For example, the distance L6 of the sixth section 12f is set to 185 mm.

[0041] (Setting the distance from the first to the sixth part of the outer panel) Next, the reason for setting the distance L1 from the first part 12a to the sixth part 12f of the outer panel 12 to L6 will be explained based on Figures 5 to 7. First, an example of setting the distance L1 of the first part 12a of the outer panel 12 will be explained based on Figures 5 and 6. Figure 5 is a schematic diagram showing the state in which a load is applied to the first part 12a and the second part 12b of the outer panel 12.

[0042] As shown in Figure 5, the load F is applied to the first portion 12a of the outer panel 12 toward the passenger compartment. The thickness of the outer panel 12 is 0.5 mm. The first portion 12a is the portion of the outer panel 12 between the first reinforcement 21 and the front roof cross member 24. The distance L1 of the first portion 12a is set to 180 mm, 150 mm, and 140 mm. Under these conditions, the amount of deflection δ of the first portion 12a when the load F is applied to the first portion 12a of the outer panel 12 is shown in the graph in Figure 6.

[0043] In FIG. 6, the vertical axis represents the deflection amount δ (mm), and the horizontal axis represents the load F (N). Graph line G1a shows the case where the distance L1 of the first part 12a is 180 mm. Graph line G1b shows the case where the distance L1 of the first part 12a is 150 mm. Graph line G1c shows the case where the distance L1 of the first part 12a is 140 mm. Graph line G1s shows the reference deflection amount δ with respect to the load F. The reference deflection amount δ is a value that satisfies the tension rigidity of the outer panel 12. Graph lines G1a to G1c satisfy the reference deflection amount δ of graph line G1s. That is, the first part 12a satisfies the required tension rigidity when the distance L1 is 180 mm, 150 mm, and 140 mm.

[0044] Here, the deflection amount δ of the conventional example is shown by graph line G1r. The conventional example is a roof structure (not shown) of a generally used automobile. The plate thickness of the outer panel of the conventional example is 0.7 mm. Comparing graph lines G1a to G1c with graph line G1r, it is estimated that the deflection amount δ of graph lines G1b and G1c is equal to or greater than that of the conventional roof structure at a load F of 90 N. Graph line G1b has a distance L1 of 150 mm for the first part 12a. Graph line G1c has a distance L1 of 140 mm for the first part 12a. Therefore, in the present embodiment, the distance L1 of the first part 12a is set to 153 mm.

[0045] Next, an example of setting the distance L2 of the second part 12b in the outer panel 12 will be described based on FIGS. 5 and 7.

[0046] As shown in FIG. 5, the load F is applied to the second part 12b of the outer panel 12 toward the passenger compartment side. The plate thickness of the outer panel 12 is 0.5 mm. The second part 12b is a part of the outer panel 12 between the front roof cross member 24 and the third reinforcement 23. The distance L2 of the second part 12b is set to 190 mm, 180 mm, and 170 mm. Under these conditions, the deflection amount δ of the second part 12b when the load F is applied to the second part 12b of the outer panel 12 is shown in the graph of FIG. 7.

[0047] In FIG. 7, the vertical axis represents the deflection amount δ (mm), and the horizontal axis represents the load F (N). The graph line G2a shows the case where the distance L2 of the second part 12b is 190 mm. The graph line G2b shows the case where the distance L2 of the second part 12b is 180 mm. The graph line G2c shows the case where the distance L2 of the second part 12b is 170 mm. The graph line G2s shows the reference deflection amount δ with respect to the load F. The reference deflection amount is a value that satisfies the tension rigidity of the outer panel 12. Here, the deflection amount δ of the conventional example is shown by the graph line G2r. The conventional example is a roof structure (not shown) of a generally used automobile. The roof structure of the conventional example has a plate thickness of 0.7 mm for the outer panel.

[0048] The graph line G2c satisfies the reference deflection amount δ of the graph line G2s in the vicinity of the initial load F of 30 N. That is, the second part 12b satisfies the required tension rigidity when the distance L2 is 170 mm. Therefore, in the present embodiment, the distance L2 of the second part 12b is set to 138 mm.

[0049] Here, in the vehicle front-rear direction of the outer panel 12, the radius of curvature on the vehicle front side is smaller than that on the vehicle rear side. That is, in the first part 12a and the second part 12b of the outer panel 12, the radius of curvature is smaller than that from the third part 12c to the sixth part 12f. Therefore, the third part 12c to the sixth part 12f are formed relatively flat compared to the first part 12a and the second part 12b. That is, the third part 12c to the sixth part 12f can suppress the deflection amount δ to be smaller than that of the first part 12a and the second part 12b.

[0050] Therefore, the distance from the third part 12c to the sixth part 12f is set to be relatively larger than the distance of the first part 12a and the second part 12b. Specifically, the distance L3 of the third part 12c is set to 182 mm, the distance L4 of the fourth part 12d is set to 182 mm, the distance L5 of the fifth part 12e is set to 182 mm, and the distance L6 of the sixth part 12f is set to 185 mm, respectively.

[0051] (Effects) Next, the tension stiffness and natural frequency of the outer panel 12 will be explained based on Figures 1 and 8. The thickness of the outer panel 12 is set to 0.5 mm. As shown in Figure 1, the outer panel 12 is divided into six sections, from the first section 12a to the sixth section 12f, between the first reinforcement 21 and the second reinforcement 22 by the front roof cross member 24, the third reinforcement 23, and the rear roof cross members 25, 26, and 27.

[0052] Figure 8 is a graph showing the deflection and load at the first to sixth sections 12a to 12f of the outer panel. In Figure 8, the vertical axis shows the deflection δ (mm) and the horizontal axis shows the load F (N). As shown in Figures 1 and 8, graph line G1 shows the deflection δ and load F of the first section 12a. Graph line G2 shows the deflection δ and load F of the second section 12b. Graph line G3 shows the deflection δ and load F of the third section 12c. Graph line G4 shows the deflection δ and load F of the fourth section 12d. Graph line G5 shows the deflection δ and load F of the fifth section 12e. Graph line G6 shows the deflection δ and load F of the sixth section 12f. Graph line Gs shows the relationship between the reference deflection δ and load F. The reference deflection amount δ is a value that satisfies the tension stiffness required by the outer panel 12.

[0053] Graph lines G1 to G6 satisfy the reference deflection amount δ of graph line Gs. That is, the first section 12a to the sixth section 12f satisfy the tension stiffness required by the outer panel 12.

[0054] In other words, the roof structure 10 of the embodiment has optimized arrangement and spacing of the three reinforcements 21, 22, and 23 and the multiple roof cross members 24, 25, 26, and 27 that stiffen the outer panel 12. As a result, even when the thickness of the outer panel 12 is reduced to 0.5 mm, it is possible to ensure the same tension rigidity as an outer panel with a thickness of 0.7 mm.

[0055] Furthermore, by ensuring the tensile rigidity of the outer panel 12, the decrease in the natural frequency of the outer panel 12 that occurs when the plate thickness is reduced to 0.6 mm or less for weight reduction can be suppressed. As a result, it is possible to suppress the increase in noise inside the vehicle cabin due to resonance caused by vibrations generated when the vehicle is in motion.

[0056] As described above, according to the roof structure 10 of this embodiment, three reinforcements 21, 22, and 23 are positioned at the front end position 14a, the rear end position 14b, and an intermediate position 14c forward of the center in the longitudinal direction of the vehicle. The three reinforcements 21, 22, and 23 are made of a material with greater tensile strength than the multiple roof cross members 24, 25, 26, and 27. As a result, the three reinforcements 21, 22, and 23 can contribute to the tensile rigidity of the outer panel 12.

[0057] Furthermore, a front roof cross member 24 is positioned between the intermediate position 14c and the front end position 14a. Multiple rear roof cross members 25, 26, and 27 are positioned between the intermediate position 14c and the rear end position 14b. Here, the intermediate position 14c is positioned forward of the center, and the number of multiple rear roof cross members 25, 26, and 27 is greater than the number of front roof cross members 24.

[0058] Therefore, the distance between the intermediate position 14c and the front end position 14a can be appropriately adjusted using the front roof cross member 24. In addition, the distance between the intermediate position 14c and the rear end position 14b can be appropriately adjusted using the multiple rear roof cross members 25, 26, and 27. As a result, the front roof cross member 24 and the multiple rear roof cross members 25, 26, and 27 can contribute to the tension rigidity of the outer panel 12.

[0059] In this way, the three reinforcements 21, 22, and 23 contribute to the tension rigidity of the outer panel 12, and the front roof cross member 24 and the multiple rear roof cross members 25, 26, and 27 also contribute to the tension rigidity of the outer panel 12. As a result, even when the outer panel 12 is thinned to a thickness of 0.6 mm or less, the three reinforcements 21, 22, and 23, the front roof cross member 24, and the multiple rear roof cross members 25, 26, and 27 can suppress a decrease in the tension rigidity of the outer panel 12. Furthermore, by suppressing a decrease in the tension rigidity of the outer panel 12, a decrease in the natural frequency of the outer panel 12 can be suppressed.

[0060] Furthermore, only one front roof cross member 24 is positioned between the third reinforcement 23 and the first reinforcement 21. This helps to reduce the cost of the automobile's roof structure.

[0061] Furthermore, the width of the front roof cross member 24 in the vehicle longitudinal direction is made larger than the width of the multiple rear roof cross members 25, 26, and 27 in the vehicle longitudinal direction. Therefore, the distance L1 between the first reinforcement 21 and the front roof cross member 24, and the distance L2 between the third reinforcement 23 and the front roof cross member 24 can be appropriately adjusted. As a result, a decrease in the tension rigidity of the outer panel 12 between the first reinforcement 21 and the third reinforcement 23 can be suppressed, as can a decrease in the natural frequency.

[0062] Furthermore, the vertical dimensions of the multiple roof cross members 24, 25, 26, and 27 are made smaller than those of the first reinforcement 21 and the second reinforcement 22. This allows for adequate space in the passenger compartment without being obstructed by the multiple roof cross members 24, 25, 26, and 27.

[0063] Furthermore, the intermediate position 14c is the connection point between the pair of roof rails 14 and the center pillar (not shown). Therefore, the third reinforcement 23 at the intermediate position 14c can be connected to the center pillar. The center pillar is a highly rigid support column that rises from the floor of the vehicle on the left and right sides of the vehicle. Therefore, by connecting the third reinforcement 23 to the center pillars on the left and right sides, a highly rigid gate-shaped member is formed in an inverted U shape by the center pillars on the left and right sides and the third reinforcement 23. This allows the reduction in the tension rigidity of the outer panel 12 to be appropriately suppressed by the third reinforcement 23.

[0064] The thickness of the outer panel 12 is set to 0.6 mm or less. For example, the outer panel of the roof structure in a typical automobile is made of a steel plate with a thickness of 0.7 mm. Therefore, by keeping the thickness of the outer panel 12 to 0.6 mm or less, the outer panel 12 can be made thinner. This makes it possible to reduce the weight of the automobile (specifically, the roof structure 10). Furthermore, by keeping the thickness of the outer panel 12 to 0.6 mm or less, the cost of the roof structure 10 can be reduced.

[0065] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. Furthermore, it is possible to replace the components in the embodiments with well-known components without departing from the spirit of the invention, and the above-described modifications can be combined as appropriate. For example, the roof cross members are arranged parallel to the left-right direction of the vehicle, but they may also be arranged to intersect with the left-right direction of the vehicle.

[0066] According to the present invention, in an automobile roof structure, it is possible to suppress the decrease in tension rigidity and natural frequency that occurs when the outer panel is thinned. Therefore, it has high potential for industrial application.

[0067] 10 Roof structure (automobile roof structure) 12 Outer panel 14 Roof rail 14a Front end position 14b Rear end position 14c Intermediate position 20 Multiple connecting members 21, 22, 23 Three reinforcements (main connecting members) 24, 25, 26, 27 Roof cross members (secondary connecting members) 24 Front roof cross member (front secondary connecting member) 25, 26, 27 Rear roof cross member (rear secondary connecting member)

Claims

1. A roof structure for an automobile comprising: an outer panel; a pair of roof rails connected to the outer panel; and a plurality of connecting members connecting the pair of roof rails, wherein the plurality of connecting members include: three main connecting members positioned at the front end position, the rear end position, and an intermediate position forward of the center of the roof rails in the longitudinal direction of the vehicle; and sub-connecting members positioned between each of the three main connecting members in the longitudinal direction of the vehicle, wherein a front sub-connecting member is positioned between the intermediate position and the front end position as the sub-connecting member; a rear sub-connecting member is positioned between the intermediate position and the rear end position as the sub-connecting member; the number of rear sub-connecting members is greater than the number of front sub-connecting members; the main connecting members are made of a material with greater tensile strength than the sub-connecting members; and the outer panel has a plate thickness of 0.6 mm or less.

2. The roof structure of an automobile according to claim 1, wherein only one of the front side auxiliary connecting members is provided.

3. The roof structure of an automobile according to claim 2, wherein the width of the front side auxiliary connecting member in the vehicle longitudinal direction is greater than the width of the rear side auxiliary connecting member in the vehicle longitudinal direction.

4. The roof structure of an automobile according to claim 1, wherein the sub-connecting member has a smaller dimension in the vehicle vertical direction than the main connecting member at the front end position and the main connecting member at the rear end position.

5. The roof structure of an automobile according to claim 1, wherein the intermediate position is the connection position between the roof rail and the center pillar.

6. The roof structure of an automobile according to claim 1, wherein the main connecting member positioned at an intermediate position forward of the center has a smaller dimension in the vehicle vertical direction than the main connecting member at the front end position, the main connecting member at the rear end position, and the sub-connecting member.

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