Reinforcement structure for vehicle back door

Abstract

To satisfy a plurality of design requirements for a back door for a vehicle while maintaining a high degree of freedom in selecting a material of a component constituting the back door for a vehicle.SOLUTION: In a bent part 4 or a side part 7 of a back door 1, an inner panel 20 and a reinforcement material 30 constitute a hat-shaped structure 50. The inner panel 20 constitutes a bottom wall portion 55, and the reinforcement member 30 constitutes at least one of a pair of flange parts 51, 52. Regarding one of a pair of vertical wall portions 53, 54 that connects flange parts 31, 32 composed of the reinforcement member 30 to the bottom wall part 25 composed of the inner panel 20, reinforcement material vertical wall parts 33, 34 continuous from the flange parts 31, 32 and panel vertical wall parts 23, 24 continuous from the bottom wall part 25 are overlapped with and joined to each other in a vehicle width direction. The panel vertical wall portions 23, 24 extend in the up-down direction on the inner side in the thickness direction of the flange portions 31, 32.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a reinforcement structure for a vehicle back door. [Background technology]

[0002] The vehicle back door has, as its main components, an outer panel that forms the exterior surface of the back door and an inner panel that forms the interior surface of the back door. The two panels are overlapped at their outer peripheral edges in the thickness direction of the back door and are assembled together by hemming the outer panel.

[0003] A vehicle back door has, as an example of its characteristic parts, a through hole into which a window material is fitted to ensure rear visibility, and a pair of side edges extending in the up-down direction on both sides of the through hole in the vehicle width direction. The outer ends of the side edges in the vehicle width direction are part of the outer peripheral edge. The inner ends of the side edges in the vehicle width direction define the through hole.

[0004] At the side edges, the outer panel is joined to the inner panel in the thickness direction not only at the outer end but also at the inner end. The side edges are required to be narrow in the vehicle width direction to ensure a wide rearward field of view, while also having high strength.

[0005] Therefore, as disclosed in Patent Document 1, for example, the inner panel has a hat-shaped cross section at the side edge. A pair of flanges of the inner panel are joined to the outer end and inner end of the outer panel, respectively. This maintains the design of the exterior surface of the back door and increases the section modulus of the side edge. Furthermore, to improve strength, reinforcing material is added locally to the side edge as a part separate from both panels.

[0006] Generally, the two panels are made of steel. Materials other than steel may be used to meet weight reduction and other design requirements. When the inner panel is made of sheet metal, it is locally drawn around the sides, giving it a hat shape. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-116388 Summary of the Invention [Problem to be solved by the invention]

[0008] Some panel materials are lighter than steel but less formable than steel. When these materials are drawn, even if the drawing amount and vertical wall angle are acceptable for steel, cracks and wrinkles may occur, compromising the quality of the panel.

[0009] If the amount of drawing is made shallower to maintain quality, the section modulus of the side edges will decrease. To achieve the required strength, the thickness or number of reinforcing materials must be increased. Even if a lighter material is selected, this effect is offset. If the vertical wall angle is reduced to maintain both the amount of drawing and quality, the side edges will become thicker in the vehicle width direction. This will narrow the through holes in the vehicle width direction, reducing rear visibility.

[0010] Therefore, the objective of the present invention is to simultaneously satisfy multiple design requirements for vehicle tailgates, such as ensuring strength, reducing weight, or ensuring rear visibility, while maintaining a high degree of freedom in selecting materials for the parts that make up the vehicle tailgate. [Means for solving the problem]

[0011] One aspect of the present invention is a reinforcing structure for a vehicle back door that opens and closes an opening formed in a rear part of a vehicle, the reinforcing structure comprising: an outer panel that forms an outer surface of the back door; an inner panel that is overlapped on the outer panel in a thickness direction of the back door and forms an inner surface of the back door; and a reinforcing material that is interposed between the outer panel and the inner panel in the thickness direction, wherein the back door has a pair of side edge portions that extend in a vertical direction on the vehicle width direction outer sides of a through hole that is covered with a window material, and at the side edge portions, the outer panel has an outer end that forms an outer peripheral edge of the back door and an inner end that defines the through hole, and the inner panel and the reinforcing material are joined to a pair of frame members that are joined to the outer end and the inner end, respectively. A reinforcing structure for a vehicle back door is provided, which comprises a hat-shaped structure having a flange portion, a pair of vertical wall portions extending inward in the thickness direction from each of the pair of flange portions, and a bottom wall portion connecting the pair of vertical wall portions in the vehicle width direction, wherein the bottom wall portion is formed by the inner panel, at least one of the pair of flange portions is formed by the reinforcing material, and in a divided vertical wall portion connecting the flange portion of the pair of vertical wall portions formed by the reinforcing material to the bottom wall portion, the reinforcing material vertical wall portion continuing from the flange portion and the panel vertical wall portion continuing from the bottom wall portion are overlapped and joined to each other in the vehicle width direction, and the panel vertical wall portion extends in the vertical direction more inward in the thickness direction than the flange portions.

[0012] According to the above-mentioned configuration, the outer end and inner end of the outer panel are joined to the pair of flanges of the hat-shaped structure at the side edges. The hat-shaped structure is made up of the inner panel and the reinforcing material, and one or both of the pair of flanges are made of the reinforcing material.

[0013] Here, of the pair of vertical wall portions, the one connecting the flange portion made of a reinforcing material to the bottom wall portion is defined as a "divided vertical wall portion." The divided vertical wall portion is composed of a reinforcing material vertical wall portion of the reinforcing material that continues from the flange portion and a panel vertical wall portion of the inner panel that continues from the bottom wall portion. The reinforcing material vertical wall portion and the panel vertical wall portion are overlapped and joined to each other in the vehicle width direction, and the panel vertical wall portion extends in the up-down direction on the inside in the thickness direction of the flange portion. The divided vertical wall portion is formed by joining the reinforcing material that is divided in the thickness direction to the inner panel, thereby maintaining or improving the height (dimension in the thickness direction) and therefore the section modulus.

[0014] The inner panel has a pair of vertical wall portions and a bottom wall portion. When the inner panel is manufactured from a metal plate, it can be formed by drawing. Compared to a conventional configuration in which the inner panel has all the elements of a hat-shaped structure and is joined to an outer panel, the vertical wall portions of the inner panel are lower even if the overall height of the vertical wall portions is the same as in the conventional configuration. Therefore, the height of the vertical wall portions of the entire hat-shaped structure can be ensured while reducing the amount of drawing of the inner panel. In this case, because the amount of drawing is reduced, it is easier to avoid the occurrence of cracks and wrinkles even if the vertical wall angle is the same as in the conventional configuration.

[0015] In this way, even if a material with poor formability is selected as the material for the inner panel, the section modulus and thinness of the side edge portion can be maintained or improved without compromising the quality of the inner panel. This allows for greater freedom in material selection while ensuring both strength and visibility. While simultaneously satisfying multiple design requirements for vehicle tailgates, it is permissible to select materials that emphasize characteristics other than formability, such as lightness.

[0016] The back door may have a bent portion that is curved in a V-shape in a side view, the bent portion being provided in a range extending from a lower portion of the side edge portion to a portion below the side edge portion, and the hat-shaped structure may be provided at the bent portion, thereby ensuring high strength at the bent portion.

[0017] Both of the pair of flanges may be made of the reinforcing material, and both of the pair of vertical wall portions may be the dividing vertical wall portions. This allows both of the pair of panel side wall portions to be low-profile, further reducing the difficulty of molding the inner panel at the side edge portions. This makes it easier to simultaneously maintain the quality of the inner panel, ensure strength, ensure rear visibility, and increase the freedom of material selection for the inner panel.

[0018] The reinforcing member may have a bridge portion connecting the pair of reinforcing member vertical wall portions in the vehicle width direction between the outer panel and the bottom wall portion in the thickness direction, thereby improving the strength of the side edge portions.

[0019] The bridge may be provided with a bead extending vertically within the hat-shaped structure, thereby further improving the strength of the reinforcement.

[0020] The reinforcing material may include a first reinforcing material having an outer flange portion joined to the outer end of the pair of flange portions, and a second reinforcing material having an inner flange portion connected to the inner end of the pair of flange portions, and the first reinforcing material and the second reinforcing material may be joined by overlapping each other. As a result, when the reinforcing material constitutes both of the pair of flange portions, the reinforcing material is divided into the first reinforcing material and the second reinforcing material in the vehicle width direction. This eliminates the need to form the reinforcing material by drawing, reducing the difficulty of forming the reinforcing material. In addition, this makes it easier to assemble the hat-shaped structure.

[0021] The inner panel is joined to the outer panel at the outer peripheral edge of the tailgate excluding the side edges by hemming the outer panel, and the outer flange portion of the pair of flange portions is joined to the outer end of the outer panel by hemming the outer panel, and when the outer flange portion is formed from the reinforcing material, the outer flange portion may have a plate thickness equivalent to that of the inner panel. This allows the inner panel and the outer flange portion of the reinforcing material to have the same plate thickness, making it possible to form the outer peripheral edge of the tailgate without any steps along the entire periphery. This improves the quality of the outer panel to which hemming is applied.

[0022] The reinforcing material vertical wall portion may form a slit that opens inward in the thickness direction, and the panel vertical wall portion may be received in the slit. This allows the reinforcing material to be divided into a first reinforcing material and a second reinforcing material in the vehicle width direction when the reinforcing material forms both of the pair of flange portions. This eliminates the need for drawing the reinforcing material, making it easier to form the reinforcing material. It also makes it easier to assemble the hat-shaped structure. [Effects of the Invention]

[0023] According to the present invention, it is possible to simultaneously satisfy a plurality of design requirements for a vehicle back door while maintaining a high degree of freedom in the selection of materials for the components that make up the vehicle back door. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a side view of the back door according to the first embodiment. [Figure 2] FIG. 2 is a rear view of the back door according to the first embodiment. [Figure 3A] FIG. 10 is a cross-sectional view of a hemmed portion in a region of the back door to which no reinforcement structure is applied. [Figure 3B] FIG. 2 is a cross-sectional view of the outer end and outer flange of the reinforcing structure. [Figure 4] FIG. 2 is a cross-sectional view of the reinforcement structure according to the first embodiment. [Figure 5] FIG. 6 is a cross-sectional view of a reinforcement structure according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a reinforcement structure according to a third embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a reinforcement structure according to a fourth embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a reinforcement structure according to a fifth embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a reinforcement structure according to a sixth embodiment. [Figure 10] FIG. 13 is a cross-sectional view of a reinforcement structure according to a seventh embodiment. [Figure 11] FIG. 13 is a cross-sectional view of a reinforcement structure according to an eighth embodiment. [Figure 12] FIG. 13 is a cross-sectional view of a reinforcement structure according to a ninth embodiment. [Figure 13] FIG. 23 is a cross-sectional view of a reinforcement structure according to a tenth embodiment. [Figure 14] FIG. 23 is a cross-sectional view of a reinforcement structure according to an eleventh embodiment. [Figure 15] FIG. [Figure 16] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted. The directions of up / down, front / rear, and left / right are based on the directions seen from the driver's seat of the vehicle.

[0026] (First embodiment) Referring to FIG. 1, a vehicle tailgate 1 opens and closes an opening that opens rearward at the rear end of the vehicle body. FIG. 1 shows the tailgate 1 in a closed position in which the opening is closed. The tailgate 1 has an upper portion 2, a lower portion 3, and a bent portion 4. In the closed position, the upper portion 2 extends downward while tilting backward from the upper end of the entire tailgate 1. The lower portion 3 extends upward from the lower end of the entire tailgate 1. The bent portion 4 is interposed between the upper portion and lower portion 3, which extend in different directions, and is curved in a V-shape that convex backward in side view, connecting the upper portion 2 and the lower portion 3.

[0027] Referring to FIG. 2 , the back door 1 has a through hole 5 to be covered with a window material (not shown). The window material is formed from a plate material that transmits visible light, such as glass, and is fixed into the through hole 5. The driver can view the rear of the vehicle while facing forward from the driver's seat through a rearview mirror (not shown) and the window material. The through hole 5 is rectangular or an isosceles trapezoid. Its four corners may be curved. The back door 1 has a window frame portion 6 that surrounds the through hole 5. The window frame portion 6 includes a pair of side edges 7 that extend vertically outside the through hole 5 in the vehicle width direction. The width of the driver's rearward field of view depends on the size of the through hole 5 in the vehicle width direction, or conversely, the narrowness of the pair of side edges 7.

[0028] The back door 1 further has a plate mounting portion 8 and a pair of lamp mounting portions 9. The plate mounting portion 8 is provided below the through hole 5 and in the center in the vehicle width direction. A vehicle number registration plate (not shown) is attached to the plate mounting portion 8. The pair of lamp mounting portions 9 are provided between the through hole 5 and the plate mounting portion 8 in the up-down direction and are spaced apart from each other in the vehicle width direction. A pair of rear combination lamps (not shown) are attached to each of the pair of lamp mounting portions 9.

[0029] The through hole 5 and most of the side edge portions 7 are formed in the upper portion 2 of the back door 1. The lower portion of the through hole 5 and the lower portion of the side edge portions 7 are formed in the bent portion 4. The bent portion 4 further includes a portion below the through hole 5 and the pair of side edge portions 7. The upper portion of the plate mounting portion 8 and the lamp mounting portion 9 are formed in the bent portion 4.

[0030] 1 and 3, the tailgate 1 includes, as its main components, an outer panel 10 and an inner panel 20. The outer panel 10 forms the outer surface of the tailgate 1. The inner panel 20 forms the inner surface of the tailgate 1. When the tailgate 1 is in a closed position, the outer surface faces rearward outside the vehicle, and the inner surface faces forward inside the vehicle.

[0031] The material of the outer panel 10 and the inner panel 20 is not particularly limited and may be appropriately selected from, for example, steel plate, aluminum plate, or aluminum alloy plate. In this embodiment, aluminum alloy plate, which is lightweight and strong, is selected as the material. The outer panel 10 and the inner panel 20 are formed from the same type of metal plate, which facilitates joining, as described below.

[0032] The outer peripheral edge of the back door 1 forms a hemmed portion 1a along the entire periphery. In this regard, the outer peripheral edge 10a of the outer panel 10 is hemmed along the entire periphery, and the outer peripheral edge 20a of the inner panel 20 is sandwiched between the hemmed outer peripheral edge 10a of the outer panel 10. In this manner, the hemmed portion 1a is formed, and the outer panel 10 and the inner panel 20 are assembled to each other at the hemmed portion 1a. In the thickness direction of the back door 1, the side where the outer panel 10 is arranged is referred to as the outer side, and the side where the inner panel 20 is arranged is referred to as the inner side.

[0033] The reinforcing structure 100 according to this embodiment is applied to both ends of the back door 1 configured as described above in the vehicle width direction, and extends generally in the vertical direction. The reinforcing structure 100 is provided at least on the side edge portion 7, and is also provided in a portion below the side edge portion 7. In other words, the reinforcing structure 100 is provided on the bent portion 4.

[0034] Referring to FIG. 4 , the outer panel 10 and the inner panel 20 constitute a reinforcing structure 100. The reinforcing structure 100 further includes a reinforcing member 30 as a component separate from the panels 10, 20. The reinforcing member 30 is interposed between the outer panel 10 and the inner panel 20 in the thickness direction of the back door 1. The reinforcing structure 100 includes a hat-shaped structure 50 joined to the outer panel 10. The hat-shaped structure 50 is not formed by the inner panel 20 alone, but is formed by the inner panel 20 and the reinforcing member 30.

[0035] In the side edge portion 7, which is an example of an application region of the reinforcing structure 100, the outer panel 10 has an outer end portion 11 and an inner end portion 12 that are spaced apart from each other in the vehicle width direction. The outer end portion 11 is part of the outer peripheral edge portion of the back door 1 and is hemmed. The inner end portion 12 defines the through hole 5.

[0036] The hat-shaped structure 50 has a pair of flanges 51, 52, a pair of vertical wall portions 53, 54, and a bottom wall portion 55. The pair of flanges 51, 52 are spaced apart in the vehicle width direction and are joined to the outer end portion 11 and inner end portion 12 of the outer panel 10, respectively. Of the two, the outer flange 51 is clamped by the hemmed outer end portion 11. Of the two, the inner flange 52 is overlapped on the inner surface of the inner end portion 12 and joined at multiple joining points set at intervals in the vertical direction. The joining method is not particularly limited, and spot welding, gas-shielded arc welding, or friction stir spot welding may be used.

[0037] The pair of vertical wall portions 53, 54 extend inward in the thickness direction from the inner ends in the vehicle width direction of the pair of flanges 51, 52 and face each other in the vehicle width direction. The outer vertical wall portion 53 is continuous with the outer flange 51, and the inner vertical wall portion 54 is continuous with the inner flange 52.

[0038] The bottom wall portion 55 connects the pair of vertical wall portions 53, 54 in the vehicle width direction. The surface of the bottom wall portion 55 forms part of the inner surface of the tailgate 1 and also forms a sealing surface that crushes a weatherstrip (not shown) provided on the periphery of the opening in the vehicle body when the tailgate 1 is in the closed position. In order to ensure airtightness of the vehicle interior, the bottom wall portion 55 has a dimension in the vehicle width direction that is large enough to fit tightly with the weatherstrip. In other words, there is a limit to how much the bottom wall portion 55 and, therefore, the side portion 7 can be reduced in dimension in the vehicle width direction.

[0039] Generally speaking, the outer portion of the hat-shaped structure 50 in the thickness direction is made up of the reinforcing material 30, while the inner portion of the hat-shaped structure 50 in the thickness direction is made up of the inner panel 20. The bottom wall portion 55 is made up of the inner panel 20. At least one of the pair of flange portions 51, 52 is made up of the reinforcing material 30.

[0040] In this embodiment, the pair of flange portions 51, 52 are integrated within a single component (see the second to fourth embodiments for cases where the pair of flange portions 51, 52 are separate components). In this embodiment, both of the pair of flange portions 51, 52 are made of the reinforcing material 30 (see the fifth and sixth embodiments for cases where only one of the flange portions is made of the reinforcing material).

[0041] In the side edge portion 7, which is an example of an application portion of the reinforcing structure 100, the inner panel 20 has a bottom wall portion 25 and a pair of panel vertical wall portions 23, 24. That is, the inner panel 20 has a U-shaped cross section. The reinforcing member 30 has a pair of reinforcing member flange portions 31, 32 and a pair of reinforcing member vertical wall portions 33, 34. The bottom wall portion 25 functions as a bottom wall portion 55 of the hat-shaped structure 50. The pair of reinforcing member flange portions 31, 32 function as a pair of flange portions 51, 52 of the hat-shaped structure 50.

[0042] Hereinafter, of the pair of vertical wall portions 53, 54, those that connect the flange portions 51, 52 (reinforcement flange portions 31, 32) made of the reinforcing material 30 to the bottom wall portion 55 will be referred to as "divided vertical wall portions." In this embodiment, both of the pair of vertical wall portions 53, 54 correspond to divided vertical wall portions.

[0043] In the outer vertical wall portion 53 serving as the dividing vertical wall portion, the reinforcement outer vertical wall portion 33 continuing from the reinforcement outer flange portion 31 and the panel outer vertical wall portion 23 continuing from the bottom wall portion 25 are overlapped and joined to each other in the vehicle width direction. The outer vertical wall portions 23, 33 are joined to each other at a plurality of joining points set at intervals in the vertical direction. The joining method is not particularly limited, and spot welding, gas shielded arc welding, or friction stir spot joining may be used.

[0044] The panel outer vertical wall portion 23 extends in the vertical direction on the inner side in the thickness direction of the outer flange portion 51 (reinforcement outer flange portion 31). Therefore, at the side edge portion 7, the edge of the panel outer vertical wall portion 23 of the inner panel 20 extends in the vertical direction in a side view, and the surface of the reinforcing material outer vertical wall portion 23 of the reinforcing material 30 is exposed between this edge and the outer panel 10.

[0045] The same applies to the inner vertical wall portion 54 serving as a dividing vertical wall portion. The panel outer vertical wall portion 24 and the reinforcement inner vertical wall portion 34 are overlapped and joined to each other in the vehicle width direction. The panel inner vertical wall portion 23 extends in the up-down direction on the inner side of the inner flange portion 52 (reinforcement inner flange portion 32) in the thickness direction.

[0046] The reinforcement 30 has a bridge portion 36 that connects the pair of reinforcement vertical wall portions 33, 34 in the vehicle width direction. The bridge portion 36 is disposed between the outer panel 10 and the bottom wall portion 55 (35) in the thickness direction.

[0047] In this embodiment, the pair of reinforcement flange portions 31, 32 are seamlessly integrated via the pair of reinforcement vertical wall portions 33, 34 and the bridge portion 36. That is, the reinforcement 30 has a hat-shaped cross section. In addition, in this embodiment, the bridge portion 36 is spaced apart from both the surface of the outer panel 10 and the surface of the bottom wall portion 25 of the inner panel 20.

[0048] Here, the dimension in the thickness direction from the hemmed portion 1a (particularly the outer end portion of the outer panel 10) to the inner surface of the bottom wall portion 55 in the thickness direction is defined as the "depth D50 of the hat-shaped structure 50." In addition, in a cross-sectional view, the inclination angle of the extension direction of the outer vertical wall portion 53 with respect to the vehicle width direction is defined as the "vertical wall angle θ53." Changing the design of the outer vertical wall portion 53 so that the vertical wall angle θ53 of the outer vertical wall portion 53 becomes smaller is sometimes referred to as "tilting the outer vertical wall portion 53."

[0049] 15 and 16 show reinforcement structures 800 and 900 according to reference examples, in which hat-shaped structures 850 and 950 are constituted only by inner panels 820 and 920, respectively. In the first reference example, a reinforcement member 830 is interposed between the outer panel 810 and the inner panel 820, but does not constitute either of the pair of flange portions 851 and 852, and no dividing vertical wall portion exists. Therefore, the depth D850 of the hat-shaped structure 850 in the reference example is synonymous with the amount of drawing performed on the inner panel 820. The same applies to the second reference example. In both reference examples, as in the present embodiment, an aluminum alloy plate is selected as the material for the inner panels 820 and 920.

[0050] In the reinforcement structure 800 according to the first reference example shown in FIG. 15 , the depth D850 (the amount of drawing of the inner panel 820) is equivalent to the depth D50 according to this embodiment. In this case, it is difficult to make the vertical wall angle θ853 equivalent to the vertical wall angle θ53 according to this embodiment. This is because drawing an aluminum alloy plate is highly difficult, which can cause cracks and wrinkles in the inner panel 20, making it impossible to maintain quality. Because the outer vertical wall portion 853 needs to be tilted further than in this embodiment, it is difficult to reduce the dimension of the bottom wall portion 855. This, combined with the difficulty of reducing the dimension of the bottom wall portion 855, increases the vehicle width direction dimension W800 from the outer end portion 811 to the inner end portion 812 of the outer panel 810. In other words, the side edge portion 807 becomes wider in the vehicle width direction, and the vehicle width direction dimension of the through hole 805 becomes smaller. This narrows the driver's rearward visibility.

[0051] In the reinforcement structure 900 according to the second reference example shown in FIG. 16 , the vertical wall angle θ953 is equivalent to the vertical wall angle θ53 according to this embodiment. Therefore, the vehicle width direction dimension W900 from the outer end 911 to the inner end 912 of the outer panel 910 is equivalent to the similar dimension W100 according to this embodiment. That is, the thinness of the side edge portion 907 and therefore the dimension of the through hole 905 are maintained. However, it is difficult to make the depth D950 (the amount of drawing of the inner panel 920) equivalent to the depth D50 according to this embodiment. Because the depth D950 becomes smaller, the strength decreases. Therefore, unless the thickness or number of the reinforcement members 930 is increased, the required strength cannot be obtained, and the lightness of the material cannot be fully utilized.

[0052] In contrast, in this embodiment, even if a material that is difficult to draw, such as an aluminum alloy plate, is selected, the amount of drawing D20 required for the inner panel 20 can be small, and it is possible to simultaneously increase the depth D50 and the vertical wall angle θ53. In other words, it is possible to simultaneously increase the section modulus and reduce the dimension W100 of the side edge portion 7 in the vehicle width direction. In this way, it is possible to simultaneously satisfy multiple design requirements for the tailgate 1, such as ensuring the necessary strength, reducing weight, and ensuring rear visibility, while improving the freedom of material selection.

[0053] 3B, the thickness t31 of the reinforcing-material outer flange portion 31 is equal to the thickness t20 of the inner panel 20. This allows the hemming process to be performed evenly around the entire outer peripheral edge 10a of the outer panel 10, thereby improving the quality of the outer panel 10.

[0054] (Second embodiment) Next, a second embodiment will be described, focusing on the differences from the above-described embodiment, with reference to Fig. 5. As in the first embodiment, both of the pair of flange portions 51, 52 of the hat-shaped structure 50 are formed of the reinforcing material 30.

[0055] In this embodiment, the reinforcing material 30 includes a first reinforcing material 30A having an outer flange portion 31 and a second reinforcing material 30B having an inner flange portion 32. The first reinforcing material 30A and the second reinforcing material 30B are stacked on top of each other in the thickness direction and joined to each other at a plurality of joining points set at intervals in the vertical direction. The joining method is not particularly limited, and spot welding, gas-shielded arc welding, or friction stir spot welding may be used.

[0056] The first reinforcement member 30A has an outer flange portion 31, an outer vertical wall portion 33, and a first bridge portion 36A. The second reinforcement member 30B has an inner flange portion 32, an inner vertical wall portion 34, and a second bridge portion 36B. The first bridge portion 36A and the second bridge portion 36B are overlapped and joined together in the thickness direction.

[0057] The first reinforcing member 30A and the second reinforcing member 30B can also be formed by bending. This reduces the difficulty of forming the reinforcing member 30, making it easier to form the hat-shaped structure 50 deeper. Furthermore, the first bridge portion 36A and the second bridge portion 36B form the bridge portion 36 with a plate thickness that is roughly twice as thick as that of the above embodiment. This provides high strength.

[0058] (Third embodiment) Next, a third embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 6. As in the second embodiment, each of the pair of flanges 51, 52 of the hat-shaped structure 50 is formed of a reinforcing member 30, and the reinforcing member 30 includes a first reinforcing member 30A and a second reinforcing member 30B.

[0059] In this embodiment, the first reinforcement member 30A has an outer flange portion 31, a reinforcement member outer vertical wall portion 33, a bridge portion 36, and a first reinforcement member inner vertical wall portion 34A. The second reinforcement member 30B has an inner flange portion 32 and a second reinforcement member inner vertical wall portion 34B. The first reinforcement member inner vertical wall portion 34A is overlapped and joined to the panel inner vertical wall portion 24 in the vehicle width direction, and is also overlapped and joined to the second reinforcement member inner vertical wall portion 34B in the vehicle width direction. Note that these two joining points are spaced apart from each other in the thickness direction. In this case, as in the second embodiment, the difficulty of forming the reinforcement member 30 is reduced.

[0060] The first reinforcement member 30A further has a bead portion 37 provided on the bridge portion 36. The bead portion 37 protrudes outward in the thickness direction from the center of the bridge portion 36 in the vehicle width direction and extends in the vertical direction. This improves the strength of the reinforcement member 30 and, in turn, the reinforced structure 100 while suppressing an increase in weight.

[0061] (Fourth embodiment) Next, a fourth embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 7. As in the second embodiment, each of the pair of flanges 51, 52 of the hat-shaped structure 50 is formed of a reinforcing member 30, and the reinforcing member 30 includes a first reinforcing member 30A and a second reinforcing member 30B.

[0062] In this embodiment, the first reinforcement member 30A has a first reinforcement member outer vertical wall portion 33A, a first bridge portion 36A, and a first reinforcement member inner vertical wall portion 34A, as well as an outer flange portion 31. The second reinforcement member 30B has a second reinforcement member inner vertical wall portion 34B, a second bridge portion 36B, and a second reinforcement member outer vertical wall portion 33B, as well as an inner flange portion 32. The first bridge portion 36A is located between the second bridge portion 36B and the bottom wall portion 25 in the thickness direction, and the first bridge portion 36A and the second bridge portion 36B extend parallel to each other in the vehicle width direction.

[0063] The first reinforcement outer vertical wall portion 33A is joined to the panel outer vertical wall portion 23 so as to be overlapped in the vehicle width direction, and is also joined to the second reinforcement outer vertical wall portion 33B so as to be overlapped in the vehicle width direction. The second reinforcement outer vertical wall portion 34A is joined to the panel inner vertical wall portion 24 so as to be overlapped in the vehicle width direction, and is also joined to the second reinforcement inner vertical wall portion 34B so as to be overlapped in the vehicle width direction. The outer vertical wall portion 53 and the inner vertical wall portion 54 may be joined at two points spaced apart in the thickness direction, as in the third embodiment (see the outer vertical wall portion 53 shown in FIG. 7), or may be joined in three layers (see the inner vertical wall portion 54 shown in FIG. 7).

[0064] In this embodiment, as in the second embodiment, the difficulty of forming the reinforcing material 30 is reduced. Furthermore, since the two bridge portions 36A, 36B are interposed between the outer panel 10 and the inner panel 20, the strength of the reinforcing material 30 and therefore the reinforcing structure 100 is improved.

[0065] (Fifth embodiment) Next, a fifth embodiment will be described with reference to Fig. 8, focusing on the differences from the above-described embodiments. As in the first embodiment, the reinforcing member 30 is a single member. In this embodiment, one of a pair of flange portions 51, 52 of the hat-shaped structure 50 is formed by the reinforcing member 30, and the other is formed by the inner panel 20.

[0066] Specifically, the inner panel 20 has a bottom wall portion 25, a panel outer vertical wall portion 23, a panel inner vertical wall portion 24, and a panel inner flange portion 22. The panel inner flange portion 22 is overlapped in the thickness direction on the inner end portion of the outer panel 10 and joined to the outer panel 10. The inner vertical wall portion 54 of the hat-shaped structure 50 is formed by the inner panel 20, rather than by a divided vertical wall portion formed by the inner panel 20 and the reinforcing member 30 as in the previous embodiments.

[0067] The reinforcement 30 has a reinforcement outer flange portion 31, a reinforcement outer vertical wall portion 33, a bridge portion 36, and a reinforcement inner vertical wall portion 34. The reinforcement outer vertical wall portion 33 and the panel outer vertical wall portion 23 are overlapped and joined to each other in the vehicle width direction, and the outer vertical wall portion 53 of the hat-shaped structure 50 is a divided vertical wall portion. The reinforcement inner vertical wall portion 34 is overlapped on the inner surface of the panel inner vertical wall portion 24 in the vehicle width direction and joined to the panel inner vertical wall portion 24, thereby stably fixing the reinforcement 30 to the outer panel 10 and the inner panel 20.

[0068] The inner panel 20 and the reinforcing member 30 can also be formed by bending, which reduces the difficulty of forming the inner panel 20 and the reinforcing member 30.

[0069] (Sixth embodiment) Next, a sixth embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 9. As in the fifth embodiment, one of a pair of flange portions 51, 52 of a hat-shaped structure 50 is formed of a reinforcing member 30, and the other is formed of an inner panel 20.

[0070] Specifically, the inner panel 20 has a bottom wall portion 25, a panel outer vertical wall portion 23, a panel inner vertical wall portion 24, and a panel outer flange portion 21. The panel outer flange portion 21 is sandwiched by the outer end portion 11 of the hemmed outer panel 10. The outer vertical wall portion 53 of the hat-shaped structure 50 is formed by the inner panel 20, rather than by a divided vertical wall portion formed by the inner panel 20 and the reinforcing member 30 as in the previous embodiments.

[0071] The reinforcement 30 has a reinforcement inner flange portion 32, a reinforcement outer vertical wall portion 33, a bridge portion 36, and a reinforcement inner vertical wall portion 34. The reinforcement inner vertical wall portion 34 and the panel inner vertical wall portion 24 are overlapped and joined to each other in the vehicle width direction, and the inner vertical wall portion 54 of the hat-shaped structure 50 is a divided vertical wall portion. The reinforcement outer vertical wall portion 33 is overlapped on the inner surface of the panel outer vertical wall portion 23 in the vehicle width direction and joined to the panel outer vertical wall portion 23, thereby stably fixing the reinforcement 30 to the outer panel 10 and the inner panel 20.

[0072] In this embodiment, contrary to the fifth embodiment, the outer flange portion 51 is formed by the inner panel 20, and the inner flange portion 52 is formed by the reinforcing material 30. In this embodiment, the same effects as those in the fifth embodiment can be obtained.

[0073] Seventh embodiment Next, the seventh embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 10. As in the first embodiment, the outer vertical wall portion 53 of the hat-shaped structure 50 is a divided vertical wall portion.

[0074] In this embodiment, the thickness of the reinforcing material 30 varies depending on the location. As in the first embodiment, the thickness t31 of the reinforcing material outer flange portion 31 is equal to the thickness t20 of the inner panel 20, which contributes to the stability of the hemming process.

[0075] Here, the upper part 33a of the reinforcement outer vertical wall part 33 is located on the outer side in the thickness direction and is continuous with the reinforcement outer flange part 31. The lower part 33b of the reinforcement outer vertical wall part 33 is located on the inner side in the thickness direction and is continuous with the bridge part 36. The plate thickness of the lower part 33b is thinner than the plate thickness of the upper part 33a. The upper part 33a and the lower part 33b form a common inner surface that is continuous without any step on the inner side in the vehicle width direction. On the other hand, the outer surface of the reinforcement outer vertical wall part 33 has a step due to the difference in plate thickness between the upper parts 33a and 33b.

[0076] The outer vertical wall portion 23 of the inner panel 20 is in surface contact with the outer surface of the lower portion 33b and joined to the reinforcing material 30. The lower portion 33b is allowed to be thinned because its strength is increased by overlapping with the inner panel 20. The thickness of the upper portion 33a is relatively large, for example, equal to the sum of the thicknesses of the lower portion and the inner panel. Therefore, sufficient strength can be ensured even in the portion of the outer vertical wall portion 53 that is composed solely of the reinforcing material 30. Therefore, even when other mounting parts for the tailgate 1 (for example, damper stays, etc.) are attached, the mounting parts can be stably supported.

[0077] Furthermore, the bridge portion 36 has a thickness greater than that of the lower portion 33a. Because the bridge portion 36 has a relatively large thickness, the strength of the hat-shaped structure 50 can be increased efficiently.

[0078] Although detailed illustration is omitted, the above configuration can be similarly applied to the inner vertical wall portion 54. Incidentally, varying the plate thickness depending on the portion can be relatively easily achieved by extrusion molding. The reinforcing member 30 may be formed by pressing a roll-formed plate material, but it may also be an extruded material.

[0079] (Eighth embodiment) Next, an eighth embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 11. As in the first embodiment, the outer vertical wall portion 53 of the hat-shaped structure 50 is a divided vertical wall portion, and the outer surface of the reinforcement outer vertical wall portion 33 has a step.

[0080] In this embodiment, the reinforcing structure 100 includes a plate 40 in the dividing vertical wall portion. The plate 40 is overlapped on the outer surface of the upper portion 33a of the reinforcing material outer vertical wall portion 33 and joined to the reinforcing material outer vertical wall portion 33. The plate 40 extends in the up-down direction and protrudes inward in the thickness direction beyond the upper portion 33a. The reinforcing material outer vertical wall portion 33 and the plate 40 form a slit 38 that opens inward in the thickness direction. The slit 38 is defined by the lower portion 33b of the reinforcing material outer vertical wall portion 33 and the plate 40. The panel outer vertical wall portion 23 of the inner panel 20 is received in the slit 38.

[0081] As a result, when viewed from the outside of the hat-shaped structure 50, the path to its interior appears labyrinth-shaped. Therefore, while adopting a structure in which the outer panel 10 partially constitutes the reinforcing member 30 and the hem processed portion 1a, the airtightness of the interior space of the back door 1 is improved. Although detailed illustration is omitted, the above configuration can also be applied to the inner vertical wall portion 54 in the same manner.

[0082] (Ninth embodiment) Next, a ninth embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 12. As in the eighth embodiment, a slit 38 is provided in the dividing vertical wall portion, and the inner panel 20 is received in the slit 38.

[0083] In this embodiment, the reinforcing material outer vertical wall portion 33 alone forms the slit 38. Therefore, in this embodiment as well, the airtightness of the interior space of the back door 1 is improved. Note that, although detailed illustration is omitted, the above configuration can also be applied to the inner vertical wall portion 54 in the same manner.

[0084] (Tenth embodiment) Next, the tenth embodiment will be described, focusing on the differences from the above-described embodiments, with reference to Fig. 13. As in the first embodiment, the inner panel 20 has a pair of panel vertical wall portions 23, 24 and a bottom wall portion 25.

[0085] In this embodiment, the inner panel 20 has a protrusion 27 that protrudes outward in the thickness direction from the bottom wall portion 25. The provision of the protrusion 27 improves the rigidity of the inner panel 20. After assembly, this contributes to improving the strength of the side edge portion 7 or the bent portion 4, and before assembly, it can prevent deformation during transportation.

[0086] (Eleventh embodiment) Next, an eleventh embodiment will be described with reference to Fig. 14, focusing on the differences from the above-described embodiments. As with the tenth embodiment, the inner panel 20 has a protrusion 27 provided on the bottom wall portion 25. In this embodiment, the protrusion 27 protrudes inward in the thickness direction. This embodiment also achieves the same effects as the tenth embodiment.

[0087] (Variation) Although the embodiments have been described above, the above configurations can be appropriately added to, modified, or deleted within the scope of the spirit of the present invention. [Explanation of symbols]

[0088] 1. Backdoor 1a Hemming section 2. Top 3 Lower 4 Bend 5 through holes 6 Window frame 7 Side part 8 Plate mounting part 9 Lamp mounting part 10 Outer panel 10a Outer periphery 11 (at the side) outer edge 12 (at the side) inner edge 20 Inner panel 20a Outer edge 21 Panel outer flange 22 Panel inner flange 23 Panel outer vertical wall 24 Vertical wall inside panel 25 Bottom wall 27 Bead section 30 Reinforcement 30A First Reinforcement 30B Second Reinforcement 31 Reinforcement outer flange 32 Reinforcement inner flange 33 Reinforcement outer vertical wall 34 Reinforcement inner vertical wall 36 Hashibe 37 Bead section 38 Slit 40 plates 50 Hat-shaped structure 51 Outer flange 52 Inner flange 53 External vertical wall section 54 Inner vertical wall section 55 Bottom wall 100 Reinforcement structure D20 Aperture D50 depth W100 width θ53 Vertical wall angle

Claims

1. A reinforcement structure for a vehicle back door that opens and closes an opening formed in a rear portion of a vehicle, an outer panel that forms the outer surface of the back door; an inner panel that is overlapped on the outer panel in a thickness direction of the tailgate and that forms an inner surface of the tailgate; a reinforcing material interposed between the outer panel and the inner panel in the thickness direction, The back door has a pair of side edges extending in the up-down direction on the outer sides of the through hole in the vehicle width direction, the side edges being covered with a window material, At the side edge portion, the outer panel has an outer end portion that forms an outer peripheral edge of the tailgate and an inner end portion that defines the through hole, and the inner panel and the reinforcing material form a hat-shaped structure having a pair of flange portions that are joined to the outer end portion and the inner end portion, respectively, a pair of vertical wall portions that extend inward in the thickness direction from each of the pair of flange portions, and a bottom wall portion that connects the pair of vertical wall portions in the vehicle width direction, the bottom wall portion is formed by the inner panel, and at least one of the pair of flange portions is formed by the reinforcing material, In the pair of vertical wall portions, in the divided vertical wall portion that connects the flange portion made of the reinforcing material to the bottom wall portion, the reinforcing material vertical wall portion that continues from the flange portion and the panel vertical wall portion that continues from the bottom wall portion are overlapped and joined to each other in the vehicle width direction, and the panel vertical wall portion extends in the up-down direction on the inner side of the flange portion in the thickness direction, Both of the pair of flange portions are formed by the reinforcing material, and both of the pair of vertical wall portions are the divided vertical wall portions. Reinforcement structure for a vehicle back door.

2. A reinforcement structure for a vehicle back door that opens and closes an opening formed in a rear portion of a vehicle, an outer panel that forms the outer surface of the back door; an inner panel that is overlapped on the outer panel in a thickness direction of the tailgate and that forms an inner surface of the tailgate; a reinforcing member interposed between the outer panel and the inner panel in the thickness direction, The back door has a pair of side edges extending in the up-down direction on the outer sides of the through hole in the vehicle width direction, the side edges being covered with a window material, At the side edge portion, the outer panel has an outer end portion that forms an outer peripheral edge of the tailgate and an inner end portion that defines the through hole, and the inner panel and the reinforcing material form a hat-shaped structure having a pair of flange portions that are joined to the outer end portion and the inner end portion, respectively, a pair of vertical wall portions that extend inward in the thickness direction from each of the pair of flange portions, and a bottom wall portion that connects the pair of vertical wall portions in the vehicle width direction, the bottom wall portion is formed by the inner panel, and at least one of the pair of flange portions is formed by the reinforcing material, In the pair of vertical wall portions, in the divided vertical wall portion that connects the flange portion made of the reinforcing material to the bottom wall portion, the reinforcing material vertical wall portion that continues from the flange portion and the panel vertical wall portion that continues from the bottom wall portion are overlapped and joined to each other in the vehicle width direction, and the panel vertical wall portion extends in the up-down direction on the inner side of the flange portion in the thickness direction, The inner panel is joined to the outer panel by hemming the outer panel at an outer peripheral edge portion of the back door excluding the side edge portion, an outer flange portion of the pair of flange portions joined to the outer end portion of the outer panel by hemming the outer panel; When the outer flange portion is formed of the reinforcing material, the outer flange portion has a plate thickness equivalent to that of the inner panel. Reinforcement structure for a vehicle back door.

3. A reinforcement structure for a vehicle back door that opens and closes an opening formed in a rear portion of a vehicle, an outer panel that forms the outer surface of the back door; an inner panel that is overlapped on the outer panel in a thickness direction of the tailgate and that forms an inner surface of the tailgate; a reinforcing member interposed between the outer panel and the inner panel in the thickness direction, The back door has a pair of side edges extending in the up-down direction on the outer sides of the through hole in the vehicle width direction, the side edges being covered with a window material, At the side edge portion, the outer panel has an outer end portion that forms an outer peripheral edge of the tailgate and an inner end portion that defines the through hole, and the inner panel and the reinforcing material form a hat-shaped structure having a pair of flange portions that are joined to the outer end portion and the inner end portion, respectively, a pair of vertical wall portions that extend inward in the thickness direction from each of the pair of flange portions, and a bottom wall portion that connects the pair of vertical wall portions in the vehicle width direction, the bottom wall portion is formed by the inner panel, and at least one of the pair of flange portions is formed by the reinforcing material, In the pair of vertical wall portions, in the divided vertical wall portion that connects the flange portion made of the reinforcing material to the bottom wall portion, the reinforcing material vertical wall portion that continues from the flange portion and the panel vertical wall portion that continues from the bottom wall portion are overlapped and joined to each other in the vehicle width direction, and the panel vertical wall portion extends in the up-down direction on the inner side of the flange portion in the thickness direction, The reinforcing member vertical wall portion forms a slit that opens toward the inside in the thickness direction, and the panel vertical wall portion is received in the slit. Reinforcement structure for a vehicle back door.

4. A reinforcement structure for a vehicle back door that opens and closes an opening formed in a rear portion of a vehicle, an outer panel that forms the outer surface of the back door; an inner panel that is overlapped on the outer panel in a thickness direction of the tailgate and that forms an inner surface of the tailgate; a reinforcing member interposed between the outer panel and the inner panel in the thickness direction, The back door has a pair of side edges extending in the up-down direction on the outer sides of the through hole in the vehicle width direction, the side edges being covered with a window material, At the side edge portion, the outer panel has an outer end portion that forms an outer peripheral edge of the tailgate and an inner end portion that defines the through hole, and the inner panel and the reinforcing material form a hat-shaped structure having a pair of flange portions that are joined to the outer end portion and the inner end portion, respectively, a pair of vertical wall portions that extend inward in the thickness direction from each of the pair of flange portions, and a bottom wall portion that connects the pair of vertical wall portions in the vehicle width direction, the bottom wall portion is formed by the inner panel, and at least one of the pair of flange portions is formed by the reinforcing material, In the pair of vertical wall portions, in the divided vertical wall portion that connects the flange portion made of the reinforcing material to the bottom wall portion, the reinforcing material vertical wall portion that continues from the flange portion and the panel vertical wall portion that continues from the bottom wall portion are overlapped and joined to each other in the vehicle width direction, and the panel vertical wall portion extends in the up-down direction on the inner side of the flange portion in the thickness direction, An outer flange portion of the pair of flange portions joined to the outer end portion is made of the reinforcing material. Reinforcement structure for a vehicle back door.

5. A reinforcement structure for a vehicle back door that opens and closes an opening formed in a rear portion of a vehicle, an outer panel that forms the outer surface of the back door; an inner panel that is overlapped on the outer panel in a thickness direction of the tailgate and that forms an inner surface of the tailgate; a reinforcing member interposed between the outer panel and the inner panel in the thickness direction, The back door has a pair of side edges extending in the up-down direction on the outer sides of the through hole in the vehicle width direction, the side edges being covered with a window material, At the side edge portion, the outer panel has an outer end portion that forms an outer peripheral edge of the tailgate and an inner end portion that defines the through hole, and the inner panel and the reinforcing material form a hat-shaped structure having a pair of flange portions that are joined to the outer end portion and the inner end portion, respectively, a pair of vertical wall portions that extend inward in the thickness direction from each of the pair of flange portions, and a bottom wall portion that connects the pair of vertical wall portions in the vehicle width direction, the bottom wall portion is formed by the inner panel, and at least one of the pair of flange portions is formed by the reinforcing material, Of the pair of vertical wall portions, in the divided vertical wall portion connecting the flange portion made of the reinforcing material to the bottom wall portion, a reinforcing material vertical wall portion continuing from the flange portion and a panel vertical wall portion continuing from the bottom wall portion are overlapped and joined to each other in the vehicle width direction, the panel vertical wall portion extends in the up-down direction on the inner side of the flange portion in the thickness direction, and an edge of the panel vertical wall portion terminates at a position away from the flange portion on the inner side in the thickness direction. Reinforcement structure for a vehicle back door.

6. The reinforcing member has a bridge portion connecting the pair of reinforcing member vertical wall portions in the vehicle width direction between the outer panel and the bottom wall portion in the thickness direction. The reinforcement structure for a vehicle back door according to claim 1.

7. The bridge portion is provided with a bead portion extending in the vertical direction within the hat-shaped structure. The reinforcement structure for a vehicle back door according to claim 6.

8. the reinforcing material includes a first reinforcing material having an outer flange portion joined to the outer end portion of the pair of flange portions, and a second reinforcing material having an inner flange portion connected to the inner end portion of the pair of flange portions, The first reinforcing material and the second reinforcing material are overlapped and joined to each other. The reinforcement structure for a vehicle back door according to claim 1.

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