Manufacturing method for fuel tank and lower panel

Abstract

The deep lower panel is precisely formed to ensure sufficient fuel tank capacity. [Solution] The fuel tank (40) is supported from below by a pair of tank rails (12) of the saddle-type vehicle. The fuel tank is provided with a lower panel (42) that bulges downward so as to fit between the pair of tank rails, and an upper panel (41) that bulges upward at a position above the pair of tank rails. The flange (44) on the outer edge of the lower panel and the flange (43) on the outer edge of the upper panel are joined together. A stepped portion (45) is formed on the inside of the flange of the lower panel, one step down from the flange, and a dome portion (46) is formed on the inside of the stepped portion, protruding deeply downward from the stepped portion. The stepped portion is supported by the pair of tank rails, and the dome portion fits between the pair of tank rails.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a fuel tank and a lower panel.

Background Art

[0002] As a straddle-type vehicle, one in which a fuel tank is covered with a cover member is known (see, for example, Patent Document 1). The fuel tank described in Patent Document 1 has an upper and lower split structure composed of an upper panel and a lower panel, and the flanges of the upper panel and the lower panel are seam welded. A cover member is attached to the vehicle body so as to hide the flange-like joint portion between the upper panel and the lower panel. The cover member is formed by combining left and right side covers made of metal and a center cover made of resin, and the rigidity against the knee grip is enhanced by the metal side covers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the fuel tank as described above is supported by a pair of tank rails, but in order to secure the capacity, it is necessary to insert a lower panel between the pair of tank rails. However, due to the widthwise restriction by the pair of tank rails, it is difficult to accurately form a deep-bottomed lower panel in a narrow-width deep drawing.

[0005] The present invention has been made in view of this point, and an object thereof is to provide a method for manufacturing a fuel tank and a lower panel that can accurately form a deep-bottomed lower panel and secure the capacity.

Means for Solving the Problems

[0006] A fuel tank according to one aspect of the present invention is a fuel tank supported from below by a pair of tank rails of a saddle-type vehicle, comprising a lower panel that bulges downward so as to fit between the pair of tank rails, and an upper panel that bulges upward at a position above the pair of tank rails, wherein the flanges on the outer edges of the lower panel and the flanges on the outer edges of the upper panel are joined, a stepped portion is formed on the inside of the flange of the lower panel, one step down from the flange, and a dome portion is formed on the inside of the stepped portion, protruding deeply downward from the stepped portion, the stepped portion is supported by the pair of tank rails, and the dome portion fits between the pair of tank rails, thereby solving the above problem. [Effects of the Invention]

[0007] According to one embodiment of the present invention, the fuel tank is stably supported by a pair of tank rails by the stepped portion of the lower panel, and the space inside the pair of tank rails is effectively utilized by the dome portion of the lower panel. The fuel tank capacity is sufficiently secured by the stepped portion above the pair of tank rails and the dome portion that fits between the pair of tank rails. Furthermore, by forming the dome portion and the stepped portion separately, a deep dome portion is formed within a range that is not constrained in the width direction by the pair of tank rails. [Brief explanation of the drawing]

[0008] [Figure 1] This is a left side view of the saddle-type vehicle in this embodiment. [Figure 2] This is a left side view of the area around the fuel tank in this embodiment. [Figure 3] This is a bottom view of the area around the fuel tank in this embodiment. [Figure 4] This is a side view of the blank material after the first deep drawing in this embodiment. [Figure 5] This is a bottom view of the blank material after the first deep drawing in this embodiment. [Figure 6] This is a side view of the blank material after the second deep drawing in this embodiment. [Figure 7]This is a bottom view of the blank material after the second deep drawing in this embodiment. [Modes for carrying out the invention]

[0009] A fuel tank according to one aspect of the present invention is supported from below by a pair of tank rails of a saddle-type vehicle. The fuel tank is formed by joining the flanges on the outer edges of a lower panel and the flanges on the outer edges of an upper panel. The lower panel bulges downward so as to fit between the pair of tank rails, and the upper panel bulges upward at a position above the pair of tank rails. A stepped portion is formed on the inside of the flange of the lower panel, one step down from the flange, and a dome portion is formed on the inside of the stepped portion, protruding deeply downward from the stepped portion. The stepped portion stably supports the fuel tank on the pair of tank rails, and the dome portion fits between the pair of tank rails, making effective use of the space inside the pair of tank rails. The stepped portion above the pair of tank rails and the dome portion that fits between the pair of tank rails ensure sufficient fuel tank capacity. Furthermore, by forming the dome portion and the stepped portion separately, a deep dome portion can be formed within a range that is not constrained in the width direction by the pair of tank rails. [Examples]

[0010] The saddle-type vehicle of this embodiment will be described below with reference to the attached drawings. Figure 1 is a left side view of the saddle-type vehicle of this embodiment. In the following figures, arrow Fr indicates the front of the vehicle, arrow Re indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle. In Figure 1, the driver is indicated by a dashed line.

[0011] As shown in Figure 1, the saddle-type vehicle 1 is constructed by mounting various components such as the engine 30 and electrical system on a vehicle frame 10. A pair of tank rails 12 extend diagonally downward and to the rear from the head pipe 11 of the vehicle frame 10, and a pair of body frames 13 extend downward from the rear of the pair of tank rails 12. In addition, a down frame 14 extends downward from the head pipe 11, and a rearward-bent under loop 15 is connected to the lower part of the down frame 14. The rear end of the under loop 15 is connected to the lower part of the pair of body frames 13, so that the vehicle frame 10 is formed in a cradle shape.

[0012] A steering shaft (not shown) supports a front fork 21 on the head pipe 11 so that it can be steered. A handlebar 22 is provided on the upper part of the front fork 21, and a front wheel 23 is rotatably supported on the lower part of the front fork 21. A fuel tank 40 is placed over a pair of tank rails 12, and the pair of tank rails 12 and the fuel tank 40 are covered by a tank cover 26 and a pair of front side covers 27. A seat 29 is installed behind the fuel tank 40, and a seat frame (not shown) that supports the seat 29 from below is covered from the side by a pair of rear side covers 28.

[0013] A swingarm 24 is pivotably supported on the body frame 13. The swingarm 24 extends rearward from the body frame 13, and a rear wheel 25 is rotatably supported at the rear end of the swingarm 24. The engine 30 is suspended inside the vehicle frame 10 via a plurality of suspension brackets 17. A cylinder assembly, consisting of a cylinder 32, a cylinder head 33, and a cylinder head cover 34, is mounted on the upper surface of the crankcase 31 of the engine 30. An exhaust pipe 35 extends downward from the front left side of the cylinder head 33, passes to the right side of the cylinder 32, and connects to a muffler 36 at the rear of the vehicle.

[0014] Incidentally, typical off-road vehicles employ a semi-cradle type frame, with the fuel tank mounted across a single tank rail. The fuel tank has a horseshoe-shaped cross-section, with a narrow bottom. However, the wide sides of the fuel tank are used as knee grip areas, eliminating the need for a cover to enclose the fuel tank. While a carburetor setup can easily accommodate a fuel tank with a narrow bottom, a fuel injection (FI) setup requires an in-tank pump at the bottom of the fuel tank, making a narrow, horseshoe-shaped fuel tank impractical.

[0015] In fuel-injected (FI) off-road vehicles, a double-cradle type chassis frame is often used, and a split fuel tank is mounted on the chassis frame. The split fuel tank is formed by seam welding the flanges of the upper and lower panels. Because the lower panel fits between a pair of tank rails, the opening is narrow, making it difficult to form the lower panel to be deep. Also, it is preferable that the lower panel is supported by a pair of tank rails. Therefore, in this embodiment, a deep dome section that fits between a pair of tank rails and a shallow stepped section supported by a pair of tank rails are formed in two stages.

[0016] The fuel tank support structure will be described with reference to Figures 2 and 3. Figure 2 is a left side view of the area around the fuel tank in this embodiment. Figure 3 is a bottom view of the area around the fuel tank in this embodiment. Note that the vehicle frame is indicated by a dashed line in Figure 3.

[0017] As shown in FIGS. 2 and 3, at the upper part of the vehicle body frame 10, a pair of tank rails 12 extend obliquely downward rearward from the upper rear side of the head pipe 11, and a single down frame 14 extends downward from the lower rear side of the head pipe 11. The middle part of the pair of tank rails 12 and the middle part of the down frame 14 are connected via a pair of reinforcing bridges 16. A fuel tank 40 is supported from below by the pair of tank rails 12, and the fuel tank 40 and the pair of tank rails 12 are covered from above by a tank cover 26 (see FIG. 1), and the fuel tank 40 and the pair of tank rails 12 are covered from both sides by a pair of front side covers 27 (see FIG. 1).

[0018] The fuel tank 40 is a two-piece type tank with an upper panel 41 and a lower panel 42 joined together. The upper panel 41 bulges upward at a position above the pair of tank rails 12, and the lower panel 42 bulges downward so as to enter between the pair of tank rails 12. A flange 43 on the outer edge of the upper panel 41 and a flange 44 on the outer edge of the lower panel 42 are seam welded. In a side view, the flange 43 of the upper panel 41 and the flange 44 of the lower panel 42 are curved in an arc shape bulging downward, and the flanges 43 and 44 are hidden by the tank cover 26 and the pair of front side covers 27.

[0019] A stepped portion 45 that is one step lower than the flange 44 is formed on the inner side in the vehicle width direction of the flange 44 of the lower panel 42, and a dome portion 46 that protrudes deeply downward from the stepped portion 45 is formed on the inner side in the vehicle width direction of the stepped portion 45. In this case, the stepped portion 45 is positioned above the upper surface of the tank rail 12, and the dome portion 46 is positioned below the upper surface of the tank rail 12. At the front side of the lower panel 42, the stepped portion 45 is formed with a shallow bottom, and at the rear side of the lower panel 42, the stepped portion 45 is formed with a deep bottom. At the front side of the lower panel 42, the dome portion 46 is formed with a deep bottom, and at the rear side of the lower panel 42, the dome portion 46 is formed with a shallow bottom.

[0020] In a view from below, the stepped portion 45 on the front side of the lower panel 42 is formed to protrude outward in the vehicle width direction from the pair of tank rails 12, and the stepped portion 45 on the rear side of the lower panel 42 is formed along the inner edge of the pair of tank rails 12. In a view from below, the dome portion 46 is formed to fit entirely inside the pair of tank rails 12 in the vehicle width direction. On the front side of the lower panel 42, the dome portion 46 is formed to be significantly narrower than the stepped portion 45, and on the rear side of the lower panel 42, the dome portion 46 is formed to be slightly narrower than the stepped portion 45. In a view from the side, the dome portion 46 protrudes downward from the pair of tank rails 12.

[0021] In a side view, a pair of flat support surfaces 47 are formed on the stepped portion 45 at the front of the lower panel 42, along the upper surface of the tank rail 12, and the flange 44 at the rear of the lower panel 42 curves toward the rear, away from the pair of tank rails 12. A pair of front rail cushions 61 are attached to the front of the pair of tank rails 12, and a pair of rear rail cushions 62 are attached to the rear of the pair of tank rails 12. The pair of support surfaces 47 at the front of the fuel tank 40 are supported from below by the pair of front rail cushions 61, and the rear half of the flange 44 of the fuel tank 40 is supported from below by the pair of rear rail cushions 62 via a pair of connecting members 63.

[0022] In this manner, the stepped portion 45 of the lower panel 42 is supported by the pair of tank rails 12, and the dome portion 46 of the lower panel 42 fits between the pair of tank rails 12. The fuel tank 40 is stably supported by the pair of tank rails 12 by the pair of support surfaces 47 of the stepped portion 45, and the load of the fuel tank 40 is distributed from the support surfaces 47 and flange 44 to a wide area of ​​the pair of tank rails 12 via the front rail cushion 61, rear rail cushion 62 and intermediate member 63. The capacity of the fuel tank 40 is secured not only by the dome portion 46 that fits between the pair of tank rails 12, but also by the stepped portion 45 above the pair of tank rails 12. In particular, the capacity is expanded by bringing the pair of support surfaces 47 of the stepped portion 45 closer to the upper surface of the tank rails 12.

[0023] A pair of front tank cushions 64 and a pair of rear tank cushions 65 are attached to the flanges 43 and 44 of the upper panel 41 and the lower panel 42. The pair of front tank cushions 64 are attached to the intermediate position in the front-rear direction of the flanges 43 and 44, and the pair of rear tank cushions 65 are attached to the rear end position of the flanges 43 and 44. The pair of front tank cushions 64 and the pair of rear tank cushions 65 are folded over to cover the side edges of the flanges 43 and 44. The front tank cushions 64 face the front inner surface of the front side cover 27, and the rear tank cushions 65 face the rear inner surface of the front side cover 27.

[0024] Furthermore, a front tank bracket (not shown) is provided at the front end of the fuel tank 40, and a rear tank bracket 67 is provided at the rear end of the fuel tank 40. A front rail bracket 68 is provided on the front side of a pair of tank rails 12, and a rear rail bracket (not shown) is provided on the protruding portion that extends upward from the body frame 13. The front tank bracket and front rail bracket 68 are fastened horizontally with bolts 69, and the rear tank bracket 67 and rear rail bracket are fastened vertically with bolts 70. An in-tank type pump 71 is installed on the bottom surface of the fuel tank 40 (lower panel 42).

[0025] In the fuel tank 40 described above, the upper panel 41 and the lower panel 42 are formed by deep drawing. The flange 44 on the outer edge of the lower panel 42 and the flange 43 on the outer edge of the upper panel 41 are curved in an arc shape that bulges downward so as to pass approximately midway through the height of the fuel tank 40. Because the flanges 43 and 44 are curved in an arc shape that bulges downward, even if the lower panel 42 bulges significantly downward, it is easier to balance the amount of drawing in the upper panel 41, which bulges upward, and the amount of drawing in the lower panel 42, which bulges downward. The amount of drawing in the upper panel 41 and the lower panel 42 is suppressed, preventing a decrease in processing accuracy and material damage.

[0026] The manufacturing method for the lower panel of the fuel tank will be described with reference to Figures 4 to 7. Figure 4 is a side view of the blank material after the first deep drawing in this embodiment. Figure 5 is a bottom view of the blank material after the first deep drawing in this embodiment. Figure 6 is a side view of the blank material after the second deep drawing in this embodiment. Figure 7 is a bottom view of the blank material after the second deep drawing in this embodiment. In Figures 6 and 7, areas formed by the first deep drawing are indicated by light dots, and areas formed by the second deep drawing are indicated by dark dots.

[0027] As shown in Figures 4 and 5, a first deep drawing is performed on the blank material 48 of the metal plate (a step to form the dome portion 46). In the first deep drawing, the area of ​​the blank material 48 that will become a stepped portion 45 (see Figure 7) after the lower panel 42 is manufactured is pressed by the die face, and a dome portion 46 with a narrower opening than the stepped portion 45 is formed in the center of the blank material 48. The width dimension of the dome portion 46 in the vehicle width direction is formed to be large enough for the dome portion 46 to fit between a pair of tank rails 12 (see Figure 2). Once the dome portion 46 is formed on the blank material 48, the blank material 48 is bent at the rear end of the dome portion 46.

[0028] As shown in Figures 6 and 7, a second deep drawing is performed on the blank material 48 after the first deep drawing (a step to form the stepped portion 45). In the second deep drawing, the portion of the blank material 48 that will become the flange 44 after the lower panel 42 is manufactured is pressed against the die face, and a stepped portion 45 with a wider opening than the dome portion 46 is formed on the blank material 48. A flat support surface 47 is formed at the bottom of the stepped portion 45, which is supported by a pair of tank rails 12 (see Figure 2). Even if the blank material 48 is bent in the first deep drawing, the stepped portion 45 is formed with a small amount of drawing in the second deep drawing, so the bending of the blank material 48 does not hinder the formation of the stepped portion 45.

[0029] On the front side of the lower panel 42, the dome portion 46 is formed deeper than the stepped portion 45, while on the rear side of the lower panel 42, the dome portion 46 is formed shallower than the stepped portion 45. In a side view, the boundary between the stepped portion 45 and the dome portion 46 is formed along the upper surface of the pair of tank rails 12, and in a bottom view, the boundary between the stepped portion 45 and the dome portion 46 is formed along the inner edge of the pair of tank rails 12. The dome portion 46 inside the pair of tank rails 12 and the stepped portion 45 protruding from the pair of tank rails 12 are formed separately in two separate stages of the first and second deep drawing, so that the molds used in the first and second deep drawing do not become complex.

[0030] As described above, according to the fuel tank 40 of this embodiment, the fuel tank 40 is stably supported by the pair of tank rails 12 by the stepped portion 45 of the lower panel 42, and the inner space of the pair of tank rails 12 is effectively utilized by the dome portion 46 of the lower panel 42. The upper stepped portion 45 of the pair of tank rails 12 and the dome portion 46 that fits between the pair of tank rails 12 ensure sufficient capacity for the fuel tank 40. Furthermore, by forming the dome portion 46 and the stepped portion 45 separately, a deep dome portion 46 is formed within a range that is not constrained in the width direction by the pair of tank rails 12.

[0031] In this embodiment, the lower panel was formed by two deep drawing processes, but it may also be formed by three or more deep drawing processes.

[0032] Furthermore, in this embodiment, a flat support surface is formed on the stepped portion, but the support surface on the stepped portion does not have to be formed flat, and a support surface does not have to be formed on the stepped portion.

[0033] Furthermore, in this embodiment, the flanges of the lower panel and the upper panel are curved in an arc shape when viewed from the side, but the shapes of the flanges of the lower panel and the upper panel are not particularly limited. For example, the flanges of the lower panel and the upper panel may be formed in a straight line when viewed from the side.

[0034] Furthermore, the fuel tank of this embodiment is not limited to the off-road type saddle-type vehicle described above, but may also be used in other types of saddle-type vehicles. Note that the term "saddle-type vehicle" is not limited to all vehicles in which the driver sits straddling a seat, but also includes scooter-type vehicles in which the driver does not straddle a seat.

[0035] As described above, the first embodiment is a fuel tank (40) supported from below by a pair of tank rails (12) of a saddle-type vehicle (1), comprising a lower panel (42) that bulges downward so as to fit between the pair of tank rails, and an upper panel (41) that bulges upward at a position above the pair of tank rails, wherein the flange (44) on the outer edge of the lower panel and the flange (43) on the outer edge of the upper panel are joined together, a stepped portion (45) is formed on the inside of the flange of the lower panel, one step down from the flange, and a dome portion (46) is formed on the inside of the stepped portion, protruding deeply downward from the stepped portion, the stepped portion is supported by the pair of tank rails, and the dome portion fits between the pair of tank rails. With this configuration, the stepped portion of the lower panel stably supports the fuel tank on the pair of tank rails, and the dome portion of the lower panel makes effective use of the space inside the pair of tank rails. The stepped section above the pair of tank rails and the dome section that fits between the pair of tank rails ensure sufficient fuel tank capacity. Furthermore, by forming the dome section and the stepped section separately, a deep dome section can be formed within the limits where the width direction is not restricted by the pair of tank rails.

[0036] In the second embodiment, as in the first embodiment, a flat support surface (47) is formed on the stepped portion along the upper surface of a pair of tank rails, and the support surface of the stepped portion is supported by the pair of tank rails from below. With this configuration, the fuel tank is stably supported by the pair of tank rails by the flat support surface. The capacity is expanded as the support surface of the stepped portion approaches the upper surface of the tank rails.

[0037] In the third aspect, as in the first or second aspect, the flanges on the outer edge of the lower panel and the flanges on the outer edge of the upper panel are curved in an arc shape that bulges downward when viewed from the side. With this configuration, even if the lower panel bulges significantly downward due to the downward arc curvature of the flanges, it is easier to balance the amount of tapering of the upper panel, which bulges upward, with the amount of tapering of the lower panel, which bulges downward.

[0038] The fourth aspect is a lower panel of a fuel tank in which the flange of the outer edge of an upper panel and the flange of the outer edge of a lower panel are joined, and is a lower panel that bulges downward so as to fit between a pair of tank rails when the fuel tank is supported by a pair of tank rails of a saddle-type vehicle, and comprises the steps of: pressing down on a blank material which will become a stepped portion after the lower panel is manufactured and forming a dome portion that fits between a pair of tank rails by a first deep drawing; and pressing down on a blank material which will become a flange after the lower panel is manufactured and forming a stepped portion that is supported by a pair of tank rails by a second deep drawing, wherein a stepped portion is formed on the inside of the flange of the lower panel which is one step lower than the flange, and a dome portion is formed on the inside of the stepped portion which protrudes deeply downward from the stepped portion. With this configuration, the fuel tank is stably supported by a pair of tank rails by the stepped portion of the lower panel, and the space inside the pair of tank rails is effectively utilized by the dome portion of the lower panel. The stepped portion above the pair of tank rails and the dome portion that fits between the pair of tank rails ensure sufficient fuel tank capacity. Furthermore, since the dome portion and the stepped portion are formed separately by the first and second deep drawing processes, a deep dome portion is formed within a range that is not constrained in the width direction by the pair of tank rails. Even if the blank material bends during the first deep drawing process, the stepped portion is formed with a small amount of drawing during the second deep drawing process, so the bending of the blank material does not hinder the formation of the stepped portion.

[0039] Although this embodiment has been described, other embodiments may include combinations of the above embodiment and its modifications, either entirely or partially.

[0040] Furthermore, the technology of the present invention is not limited to the embodiments described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea. Moreover, if the technical idea can be realized in a different way by advances in the technology or by other derived technologies, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of Symbols]

[0041] 1: Saddle-type vehicle 10: Vehicle frame 12: Tank Rail 40: Fuel tank 41: Upper Panel 42: Lower Panel 43: Upper panel flange 44: Lower panel flange 45: Stepped section 46: Dome section 47: Support surface 48: Blank material

Claims

1. A fuel tank supported from below by a pair of tank rails on a saddle-type vehicle, A lower panel that bulges downward so as to fit between the pair of tank rails, It comprises an upper panel that bulges upward at a position above the pair of tank rails, The flange on the outer edge of the lower panel and the flange on the outer edge of the upper panel are joined together. A stepped portion is formed on the inside of the flange of the lower panel, one step down from the flange, and a dome portion is formed on the inside of the stepped portion, protruding deeply downward from the stepped portion. A fuel tank characterized in that the stepped portion is supported by the pair of tank rails, and the dome portion is positioned between the pair of tank rails.

2. A flat support surface is formed in the stepped portion, along with the upper surface of the pair of tank rails. The fuel tank according to claim 1, characterized in that the support surface of the stepped portion is supported from below by the pair of tank rails.

3. The fuel tank according to claim 1 or 2, characterized in that, when viewed from the side, the flanges on the outer edge of the lower panel and the flanges on the outer edge of the upper panel are curved in an arc shape that bulges downward.

4. A lower panel of a fuel tank in which the flange of the outer edge of the upper panel and the flange of the outer edge of the lower panel are joined, and a lower panel that bulges downward so as to fit between a pair of tank rails when the fuel tank is supported by a pair of tank rails of a saddle-type vehicle, The steps include: holding down the blank material in the planned location that will become a stepped portion after the manufacturing of the lower panel, and forming a dome portion that fits between the pair of tank rails by a first deep drawing; The process includes a step of holding down the blank material that will become the flange after the lower panel is manufactured, and forming the stepped portion that will be supported by the pair of tank rails by a second deep drawing, A method for manufacturing a lower panel, characterized in that a stepped portion is formed on the inside of the flange of the lower panel, one step lower than the flange, and a dome portion is formed on the inside of the stepped portion, protruding deeply downward from the stepped portion.

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