JP7635100B2 - Fuel tank fixing structure for straddle-type vehicle and straddle-type vehicle - Google Patents

Description

This disclosure relates to a structure for fixing a fuel tank of a saddle-type vehicle to the vehicle body.

A motorcycle (saddle-type vehicle) as shown in Patent Document 1 below is known. This motorcycle includes a body and a fuel tank in which fuel is stored. The fuel tank is fixed to the body by fastening it to a frame that constitutes the body using bolts, nuts, etc.

Patent No. 3489918

It is desirable for the fuel tank to be fixed to the vehicle body with the required rigidity. However, it is not desirable to complicate the fuel tank fixing structure in order to ensure rigidity.

This disclosure has been made in consideration of the above circumstances, and aims to provide a fuel tank fixing structure for a saddle-type vehicle that can properly fix a fuel tank to a vehicle body with a relatively simple structure, and a saddle-type vehicle.

In order to solve the above problem, a fuel tank fixing structure according to one aspect of the present disclosure is a structure for fixing a fuel tank to a body of a saddle-type vehicle, and includes a plate member joined to the fuel tank by welding , a boss member joined to the plate member in a state in which it protrudes in an out-of-plane direction from the plate member, and a connecting member connecting the boss member to the vehicle body, wherein the plate member includes a first joint which is a joint with the fuel tank, and a second joint which is a joint with the boss member, and is formed so that the plate thickness of the second joint is greater than the plate thickness of the first joint.

A saddle-type vehicle according to another aspect of the present disclosure includes a fuel tank that stores fuel and is fixed to a vehicle body , a plate member that is joined to the fuel tank by welding , a boss member that is joined to the plate member in a state in which it protrudes outwardly from the plate member, and a bracket that includes a first fixing portion fixed to the boss member and a second fixing portion fixed to the vehicle body, wherein the plate member includes a first joint that is a joint with the fuel tank and a second joint that is a joint with the boss member, and is formed so that the plate thickness of the second joint is greater than the plate thickness of the first joint.

The fuel tank fixing structure for a saddle-type vehicle and the saddle-type vehicle disclosed herein allow the fuel tank to be properly fixed to the vehicle body with a relatively simple structure.

1 is a side view of a motorcycle to which a fuel tank fixing structure according to an embodiment of the present disclosure is applied. FIG. 2 is a cross-sectional view showing the fuel tank and the vehicle body frame thereunder. FIG. 3 is an enlarged cross-sectional view of a portion of FIG. 2 . FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 4 is a cross-sectional view of the front stay alone. FIG. 4 is a bottom view of the front end portion of the fuel tank as viewed from below. FIG. 11 is an exploded perspective view showing how the front stay is fixed to the tank inner panel. FIG. 11 is an exploded perspective view showing how the bracket is fixed to the front stay. FIG. 11 is a perspective view showing a state in which the bracket has been fixed to the front stay.

[Overall configuration of motorcycle]
1 is a side view of a motorcycle to which a fuel tank fixing structure according to an embodiment of the present disclosure is applied. The motorcycle includes a fuel tank 1, a body frame 101, a front wheel 102 and a rear wheel 103, a head pipe 104, a front fork 105, a handlebar 106, a swing arm 107, a seat 108, and an engine 109. In other words, the motorcycle is a two-wheeled automobile that runs by the driving force of the engine 109, and is a type of saddle-type vehicle.

The fuel tank 1 is a tank that stores fuel to be supplied to the engine 109. The fuel tank 1 is fixed to the vehicle body frame 101 by a fixing structure described below.

The vehicle body frame 101 includes a main frame 111, a lower frame 112, a first connecting frame 113, a second connecting frame 114, and a rear frame 115. The main frame 111 is a frame that extends from the upper part of the head pipe 104 while slanting backward and downward. The lower frame 112 is a frame that extends from the lower part of the head pipe 104 while slanting backward and downward. The lower frame 112 is inclined greatly below the main frame 111 so that the distance between the main frame 111 and the lower frame 112 increases toward the rear. The first connecting frame 113 is a frame that connects the front end of the main frame 111 and the front end of the lower frame 112 in the vertical direction. The second connecting frame 114 is a frame that connects the respective middle parts of the main frame 111 and the lower frame 112 in the front-rear direction. The rear frame 115 is a frame that extends from the rear part of the main frame 111 while slanting backward and upward.

Although details are omitted, the body frame 101 has a bilaterally symmetrical structure. In other words, the frame group 111-115 of the body frame 101 described above is provided not only on the left side of the body shown in FIG. 1, but also on the right side. In other words, the body frame 101 includes a pair of main frames 111 and a pair of lower frames 112 that extend diagonally downward while branching out to the left and right from the head pipe 104, a pair of first connecting frames 113 and a pair of second connecting frames 114 that connect the left and right main frames 111 and the left and right lower frames 112, and a pair of rear frames 115 that extend rearward from the left and right main frames 111.

The head pipe 104 is a pipe material to which the front ends of the main frame 111 and the lower frame 112 are commonly connected. The head pipe 104 is positioned so that it extends vertically at an angle such that the upper end is located rearward of the lower end.

The front fork 105 is rotatably supported by the head pipe 104 via a steering shaft (not shown). The front fork 105 extends vertically while inclining at the same angle as the head pipe 104. A handlebar 106 is attached to the upper end of the front fork 105, and the front wheel 102 is journaled at the lower end of the front fork 105.

The swing arm 107 is an arm that extends in the front-rear direction and connects the body frame 101 and the rear wheel 103. The front end of the swing arm 107 is journaled on the rear end of the main frame 111. The rear wheel 103 is journaled on the rear end of the swing arm 107. In other words, the swing arm 107 supports the rear wheel 103 in a state in which it can swing up and down relative to the main frame 111.

The seat 108 is a seat on which a rider who drives the motorcycle sits. The seat 108 is supported on the rear frame 115.

The engine 109 is, for example, a four-stroke internal combustion engine. The engine 109 is supported by the vehicle body frame 101 below the fuel tank 1. The engine 109 has a cylinder block 121 that contains a space (cylinder) in which fuel supplied from the fuel tank 1 is burned. A crankshaft, which is the output shaft of the engine 109, is rotatably attached to the lower part of the cylinder block 121. The rotation of the crankshaft is transmitted to the rear wheel 103 via a transmission 123 and a chain 124. In other words, the engine 109 is a drive source that drives and rotates the rear wheel 103.

The motorcycle of this embodiment is a so-called naked type motorcycle that is not equipped with a cover (cowl) that surrounds the engine 109. Therefore, both the left and right sides of the main parts of the engine 109, including the cylinder block 121, are exposed to the outside air.

[Fuel tank fixing structure]
Fig. 2 is a cross-sectional view showing the fuel tank 1 and the body frame 101 thereunder, and Fig. 3 is an enlarged cross-sectional view of a portion of Fig. 2. As shown in this figure, the fuel tank 1 is a tank having an internal storage space S for storing fuel, and includes a tank outer panel 11 and a tank inner panel 12. The tank outer panel 11 is a panel that constitutes the outer wall of the fuel tank 1, and the tank inner panel 12 is a panel that constitutes the inner wall of the fuel tank 1. The fuel tank 1 is fixed to the body frame 101 with the tank outer panel 11 facing up and the tank inner panel 12 facing down.

The tank outer panel 11 and the tank inner panel 12 have flange portions 11a, 12a on their respective peripheral edges. The flange portion 11a of the tank outer panel 11 and the flange portion 12a of the tank inner panel 12 are joined by welding or the like to construct the fuel tank 1 in which both panels 11, 12 are integrated. The tank outer panel 11 and the tank inner panel 12 are formed so as to be spaced apart from each other in areas other than the flange portions 11a, 12a. This forms a storage space S between the tank outer panel 11 and the tank inner panel 12.

A tank cap 13 that functions as a fuel filler is attached to the front of the tank outer panel 11. A fuel supply hole 12b to which a fuel pump (not shown) is attached is formed in the rear of the tank inner panel 12. The fuel pump supplies fuel stored in the storage space S to the engine 109 through the fuel supply hole 12b.

The fuel tank 1 is fixed to the vehicle body frame 101 by fastening its front to the main frame 111 and its rear to the rear frame 115. The fixing structures of the front and rear of the fuel tank 1 are described in detail below.

First, the fixing structure of the rear part of the fuel tank 1 will be described. The rear part of the fuel tank 1 is fixed to the front part of the rear frame 115 via the rear stay 60. The rear stay 60 is an L-shaped plate in a side view, and is joined by welding or the like to the rear fixing part 18 of the tank outer panel 11. The rear fixing part 18 is a vertical wall extending in the vertical direction that covers the area of the lower rear end of the storage space S from the rear. The rear stay 60 has a protruding part 60a that protrudes rearward from the rear fixing part 18 while being joined to the rear fixing part 18. A base 115a that faces the protruding part 60a of the rear stay 60 is joined to the front part of the rear frame 115 by welding or the like. The rear part of the fuel tank 1 is fixed to the rear frame 115 by fastening the protruding part 60a of the rear stay 60 to the base 115a via a fastening member 61 such as a bolt. A rubber bushing 62 is attached to the fastening portion between the rear stay 60 and the base 115a by the fastening member 61. The rubber bushing 62 is a vibration-damping rubber part similar to the rubber bushing 52 (described later) that is applied to the front part of the fuel tank 1.

The rear stays 60 are used separately for the left and right rear frames 115. That is, the rear of the fuel tank 1 is fixed to the right and left rear frames 115 shown in FIG. 2 using the rear stays 60. Specifically, the rear stays 60 are joined to two locations, left and right, on the rear of the fuel tank 1, and pedestals 115a are provided on the front of the left and right rear frames 115. Then, each rear stay 60 is fixed to each pedestal 115a via fastening members 61, thereby fixing the rear of the fuel tank 1 to each of the left and right rear frames 115.

Next, the fixing structure of the front part of the fuel tank 1 will be described. The front part of the fuel tank 1 is fixed to the front end part of the main frame 111 via the front stay 20 and the bracket 40. The front side fixing part 16 is a bottom wall that covers the front end area of the storage space S from below. The front stay 20 is joined to the front side fixing part 16 by welding. The bracket 40 is fixed to the front stay 20 and the tank inner panel 12 by fastening its rear end part (first fixing part 41 described later) to the front stay 20 via a first fastening member 51 consisting of a bolt or the like. A boss part 111a protruding upward is joined to the front end part of the main frame 111 by welding or the like. The front part of the fuel tank 1 is fixed to the main frame 111 by fastening the front end part of the bracket 40 (second fixing part 42 described later) to the boss part 111a via a second fastening member 55 consisting of a bolt or the like. The bracket 40 corresponds to the "connecting member" in this disclosure.

The front stay 20 and bracket 40 are used in common for both the left and right main frames 111. That is, the front of the fuel tank 1 is fixed to not only the right main frame 111 shown in Figures 2 and 3, but also the left main frame 111 using the common front stay 20 and bracket 40. Specifically, the common front stay 20 is joined to the front fixing portion 16 of the tank inner panel 12, and a boss portion 111a is provided at the front end of each of the left and right main frames 111. The left and right boss portions 111a and the front stay 20 are connected to each other via the common bracket 40, thereby fixing the front of the fuel tank 1 to the left and right main frames 111.

The fixing structure of the front part of the fuel tank 1 will be explained in more detail with reference to Figures 4 to 9. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3. Figure 5 is a cross-sectional view of the front stay 20 alone. Figure 6 is a bottom view of the front end part of the fuel tank 1 as viewed from below. Figure 7 is an exploded perspective view showing how the front stay 20 is fixed to the tank inner panel 12. Figure 8 is an exploded perspective view showing how the bracket 40 is fixed to the front stay 20. Figure 9 is a perspective view showing how the bracket 40 has been fixed to the front stay 20.

As shown in Figures 3 to 7, the front stay 20 includes a plate member 21 and a pair of left and right boss members 25. The plate member 21 is a plate-shaped member that is joined to the front fixing portion 16 of the tank inner panel 12. Each boss member 25 is a cylindrical member that is joined to the plate member 21 in a state in which it protrudes downward from the plate member 21.

The plate member 21 is a composite product made up of two plates that overlap in the thickness direction. Specifically, the plate member 21 includes a main plate 22 and a sub-plate 23. The main plate 22 is a rectangular plate material whose dimension in the left-right direction (vehicle width direction) is larger than its dimension in the front-rear direction. The sub-plate 23 is a strip-shaped (elliptical) plate material whose area is smaller than that of the main plate 22. The sub-plate 23 is formed so that its dimensions in the left-right direction and front-rear direction are both smaller than the corresponding dimensions of the main plate 22. The main plate 22 and the sub-plate 23 are joined to each other in an overlapping state such that the lower surface 23a of the sub-plate 23 abuts against the upper surface 22b of the main plate 22.

In this embodiment, as shown in FIG. 5, the plate thickness t2 of the sub-plate 23 is greater than the plate thickness t1 of the main plate 22. Also, the plate thickness t1 of the main plate 22 is greater than the plate thickness t3 of the tank inner panel 12 (FIG. 4). That is, in this embodiment, the plate thicknesses of the main plate 22 and the sub-plate 23 are set so that the relationship t2>t1>t3 is established. More specifically, the plate thickness t2 of the sub-plate 23 is greater than 1 time and less than 2 times the plate thickness t1 of the main plate 22 (t1<t2≦t1×2). Also, the plate thickness t1 of the main plate 22 is greater than 1 time and less than 2 times the plate thickness t3 of the tank inner panel 12 (t3<t1≦t3×2). Since the plate thickness t3 of the tank inner panel 12 is smaller than both the plate thickness t1 of the main plate 22 and the plate thickness t2 of the sub-plate 23, it is easy to reduce the weight of the fuel tank 1.

The subplate 23 has a pair of joining holes h2 capable of receiving each of the boss members 25 as holes for joining the pair of boss members 25. Each joining hole h2 is a circular hole penetrating the subplate 23 in the thickness direction. Each boss member 25 is joined to the subplate 23 with its upper end inserted into each joining hole h2. That is, the upper end of each boss member 25 is joined to the subplate 23 by welding to the periphery of each joining hole h2 by arc welding or the like. By welding the upper end to the periphery of each joining hole h2, the boss member 25 is joined to the subplate 23 with most of it, except for the upper end, protruding downward from the lower surface 23a of the subplate 23. In addition, in Figures 4 and 5, the weld bead generated by welding the boss member 25 to the subplate 23 is indicated by the symbol W.

The main plate 22 has a pair of through holes h1 at positions overlapping with each of the joining holes h2 of the sub-plate 23. Each through hole h1 is a circular hole that penetrates the main plate 22 in the thickness direction. The diameter of the through hole h1 is the same as or slightly larger than the diameter of the joining hole h2. A boss member 25 joined to the sub-plate 23 is inserted into the through hole h1. In other words, the main plate 22 and the sub-plate 23 are overlapped in the thickness direction with the pair of boss members 25 inserted into the pair of through holes h1 of the main plate 22, respectively.

The main plate 22 and the sub-plate 23 are joined by spot welding while overlapping in the thickness direction as described above. In FIG. 6, the points where this spot welding is performed are illustrated as welding points P2. In this embodiment, a case where there are a total of three welding points P2 is illustrated. That is, the main plate 22 and the sub-plate 23 are joined by spot welding at one welding point P2 set between the pair of boss members 25 and two welding points P2 set on the outside of the pair of boss members 25. Note that there may be more than one welding point P2, and the number may be increased or decreased from three as appropriate.

By joining the main plate 22 and the sub-plate 23 as described above, the plate member 21 consisting of both plates 22, 23 and the pair of boss members 25 are fixed to each other, and the front stay 20 is constructed. In this state, the pair of boss members 25 protrude further downward than the lower surface 22a of the main plate 22. In other words, the pair of boss members 25 are fixed to the plate member 21 in a state in which they protrude in a direction away from the fuel tank 1 along a normal to the lower surface 22a of the plate member 21 (main plate 22), that is, in a direction outward from the surface of the plate member 21.

The main plate 22 is joined to the front fixing portion 16 of the tank inner panel 12 by spot welding. In FIG. 6, the points where this spot welding is performed are illustrated as welding points P1. In this embodiment, a case where there are a total of 12 welding points P1 is illustrated. That is, the main plate 22 is joined to the front fixing portion 16 of the tank inner panel 12 by spot welding at 12 welding points P1 arranged at approximately equal intervals along its periphery. Note that there may be more than one welding point P1, and the number of welding points P1 may be increased or decreased from 12 as appropriate.

The position of each welding point P1 between the main plate 22 and the tank inner panel 12 is set so that the pitch, which is the center-to-center distance between adjacent welding points P1, is equal to or greater than a predetermined value. This value is determined taking into consideration the welding quality, etc., and may be set to, for example, about 20 mm. Similarly, the position of each welding point P2 between the main plate 22 and the sub-plate 23 is set so that the pitch of the welding points P2 is equal to or greater than the above-mentioned specified value.

The sub-plate 23 is joined to the main plate 22 inside the welding point P1 between the main plate 22 and the tank inner panel 12. That is, the sub-plate 23 is joined to an area including the center of the main plate 22 and excluding the peripheral edge. In FIG. 6, the overlapping area between the main plate 22 and the sub-plate 23 is shown in color. In this way, the plate member 21 can be divided into a colored area where the main plate 22 and the sub-plate 23 overlap, and an uncolored area outside of that. The colored area is the area where the pair of boss members 25 are joined, and the uncolored area is the area where the plate member 21 is joined to the tank inner panel 12.

Here, the non-colored region of the plate member 21 that is the joint with the tank inner panel 12 (fuel tank 1) is referred to as the first joint R1, and the colored region that is the joint with the boss member 25 is referred to as the second joint R2. The thickness of the first joint R1 is the thickness t1 of the main plate 22 itself. The thickness of the second joint R2 is the sum of the thickness t1 of the main plate 22 and the thickness t2 of the sub-plate 23. Therefore, the thickness (t1+t2) of the second joint R2 is greater than the thickness (t1) of the first joint R1. In other words, the plate member 21 has a first joint R1 with a smaller thickness that is joined to the fuel tank 1, and a second joint R2 with a larger thickness that is joined to the boss member 25.

When joined to the front fixing portion 16 of the tank inner panel 12, the plate member 21 (main plate 22 and sub-plate 23) has a shape that is symmetrical with respect to the tank axis L1 (FIG. 6) that divides the fuel tank 1 into left and right halves. As a result, the pair of boss members 25 are disposed symmetrically with respect to the tank axis L1. In other words, the pair of boss members 25 are attached to two locations on the left and right of the plate member 21 that are sandwiched between the tank axis L1, at positions that are the same distance from the tank axis L1.

As shown in FIG. 5 in particular, a screw hole 25a is formed in each of the pair of boss members 25. The screw hole 25a is a screw hole that can be screwed into the shaft portion of the first fastening member 51, and is formed along the axis of the boss member 25. The screw hole 25a is drilled from the lower surface of the boss member 25 to near the upper surface (midway in the vertical direction) so as not to penetrate the boss member 25. In other words, the boss member 25 has the screw hole 25a and a blocking portion 25b that blocks the upper end of the screw hole 25a (the end on the tank inner panel 12 side).

The front fixing portion 16 of the tank inner panel 12 is a substantially rectangular region corresponding to the planar shape of the plate member 21 (or the main plate 22). That is, as shown in FIG. 3 and FIG. 7, the front fixing portion 16 includes a rectangular frame-shaped protrusion 16a and a recess 16b formed inside the protrusion 16a. The recess 16b has an oblong shape that is long in the left-right direction in a bottom view. The protrusion 16a is a protrusion formed by raising the periphery of the recess 16b (protruding downward), and is formed in a rectangular frame shape surrounding the recess 16b. The protrusion 16a is formed in a region that overlaps with the peripheral portion of the main plate 22 in a bottom view. The protrusion 16a corresponds to the "joined portion" in this disclosure.

As shown in Figures 6 and 7, the convex portion 16a has a number of ridges 17. Each ridge 17 is arranged along the outer periphery of the convex portion 16a. In addition, a number of step portions 22d are formed on the outer periphery of the main plate 22 to avoid interference with each ridge 17. Each step portion 22d is formed at each of the four corners of the rectangular main plate 22. In other words, the outline of the four corners of the main plate 22 is recessed one step inward from the outline of the remaining parts, thereby forming step portions 22d at each of the four corners of the main plate 22.

When the main plate 22 is joined to the front fixing part 16, each protrusion 17 slides against each step 22d, positioning the main plate 22 relative to the front fixing part 16 (tank inner panel 12). This positioning positions the main plate 22 so that its peripheral edge overlaps the protrusion 16a of the front fixing part 16 in a bottom view. With the main plate 22 and the protrusion 16a overlapping in this manner, multiple points of the overlap (the above-mentioned welding point P1) are spot welded to fix the main plate 22 to the front fixing part 16.

With the peripheral portion of the main plate 22 joined to the protrusion 16a of the front fixing portion 16 as described above, the sub-plate 23 is positioned so that it overlaps with the recess 16b in a bottom view. In other words, the sub-plate 23 has an outer shape that is one size smaller than the recess 16b in a bottom view. Then, by joining such a sub-plate 23 to an area including the center of the main plate 22, the sub-plate 23 is contained within the recess 16b when the main plate 22 is joined to the front fixing portion 16. This helps to avoid interference between the sub-plate 23 and the front fixing portion 16.

The main plate 22 has a pair of left and right protrusions 24. The pair of protrusions 24 are formed to protrude downward from the left and right side edges of the flat plate portion of the main plate 22. A hanging hole 24a is formed in each protrusion 24. The hanging hole 24a is a hole for hanging the fuel tank 1 when the fuel tank 1 is painted. In other words, the fuel tank 1 is held in a hanging state by a specified hanger when painted. At this time, the hanging hole 24a functions as an engagement hole for engaging the hanger with the protrusions 24.

3, 8 and 9, the bracket 40 includes a first fixing portion 41 fixed to the boss member 25 of the front stay 20, a second fixing portion 42 fixed to the boss portion 111a of the main frame 111, and an intermediate portion 43 connecting the first fixing portion 41 and the second fixing portion 42. As shown in FIG. 3, the first fixing portion 41 is disposed below the plate member 21 of the front stay 20 and approximately parallel to the plate member 21. More specifically, the first fixing portion 41 is fixed to the boss member 25 in an inclined position along the lower surface 22a of the plate member 21 (main plate 22) so that the height increases toward the rear. The second fixing portion 42 is disposed above the front end of the main frame 111 and approximately parallel to the main frame 111. More specifically, the second fixing portion 42 is fixed to the boss portion 111a of the main frame 111 in an inclined position along the front end of the main frame 111 so that the height decreases toward the rear. The intermediate portion 43 connects the first fixed portion 41 and the second fixed portion 42 in an inclined position so as to be non-parallel to both the first fixed portion 41 and the second fixed portion 42.

A pair of left and right fastening holes 42a (FIGS. 8 and 9) are formed in the second fixing portion 42. Each fastening hole 42a is a circular through hole for inserting a second fastening member 55 (FIG. 3). The second fastening member 55 is screwed into the boss portion 111a of the main frame 111 while being inserted into the fastening hole 42a. In other words, the second fastening members 55 inserted into the pair of fastening holes 42a are screwed into the boss portions 111a of the left and right main frames 111, respectively, thereby fixing the second fixing portion 42 to the left and right main frames 111.

A pair of left and right fastening holes 41a (Fig. 8) are formed in the first fixing portion 41. Each fastening hole 41a is a through hole for receiving a boss member 25. A first fastening member 51 is screwed into the boss member 25 inserted into the fastening hole 41a. In other words, the first fixing portion 41 is fixed to the front stay 20 by screwing the first fastening members 51 into the pair of boss members 25 inserted into the pair of fastening holes 41a.

As shown in Figures 4, 8 and 9, a rubber bushing 52 is attached to each fastening hole 41a of the first fixing part 41. The rubber bushing 52 is a cylindrical rubber part having elasticity. A constricted portion 52a (Figure 4) with a relatively reduced outer diameter is formed in the middle of the axial direction of the rubber bushing 52. The rubber bushing 52 is press-fitted into the fastening hole 41a so that the constricted portion 52a enters the inside of the fastening hole 41a. As a result, the constricted portion 52a engages with the periphery of the fastening hole 41a, and the rubber bushing 52 is fixed to the first fixing part 41.

The rubber bush 52 has a hollow portion capable of receiving the boss member 25. That is, the boss member 25 is coaxially inserted into the inside of the rubber bush 52 attached to the fastening hole 41a of the first fixing portion 41. In addition, with the boss member 25 inserted into the inside of the rubber bush 52 in this manner, the first fastening member 51 is screwed into the screw hole 25a of the boss member 25. A ring-shaped washer 53 is disposed between the rubber bush 52 and the head of the first fastening member 51. As a result, the rubber bush 52 is sandwiched and fixed between the head (or the washer 53) of the first fastening member 51 and the plate member 21. That is, the rubber bush 52 is compressed and fixed by the first fastening member 51 in a state in which it surrounds the boss member 25. In addition, by fixing the rubber bush 52 around the boss member 25 in this manner, the first fixing portion 41 is fixed to the boss member 25 via the rubber bush 52. In other words, the first fixing portion 41 of the bracket 40 is fixed to the boss member 25 via the first fastening member 51 , the washer 53 and the rubber bushing 52 .

[Procedure for fixing the front of the fuel tank to the vehicle body]
Next, a procedure for fixing the front part of the fuel tank 1 to the main frame 111 using the front stay 20 and bracket 40 constructed as described above will be described. Note that "upper" and "lower" in the following description refer to directions based on the state in which the fuel tank 1 has been attached to the body frame 101, and are not intended to limit the position of the fuel tank 1 during the fixing operation.

First, the front stay 20 is assembled. That is, a pair of boss members 25 are joined to the subplate 23, and the subplate 23 is joined to the upper surface 22b of the main plate 22. Specifically, the upper ends of the pair of boss members 25 are inserted into a pair of joining holes h2 of the subplate 23, and the upper ends of each boss member 25 are welded to the periphery of each joining hole h2. Then, the subplate 23 is overlapped on the upper surface 22b of the main plate 22 while each boss member 25 joined to the subplate 23 is passed through a pair of insertion holes h1 of the main plate 22. Then, the main plate 22 and the subplate 23 are joined to each other by spot welding three welding points P2 (FIG. 6) set at the overlapping portion of both. As a result, the front stay 20 is completed, which is integrally provided with the plate member 21 consisting of the main plate 22 and the subplate 23 and the pair of boss members 25.

Next, the completed front stay 20 is joined to the front fixing part 16 of the tank inner panel 12. Specifically, the front stay 20 is positioned at a specified position surrounded by the protrusions 17 around the front fixing part 16, and the front stay 20 is abutted against the front fixing part 16 from below. As a result, the first joint R1 (FIG. 6) of the plate member 21, that is, the peripheral part of the main plate 22 located outside the overlapping area between the sub-plate 23 and the main plate 22, is overlapped with the convex part 16a of the front fixing part 16. Then, the front stay 20 is joined to the front fixing part 16 by spot welding 12 welding points P1 set in the overlapping part between the main plate 22 and the convex part 16a. Note that when the front stay 20 is joined, the tank inner panel 12 is not joined to the tank outer panel 11. In other words, the front stay 20 is joined to the tank inner panel 12 in a single state that is not joined to the tank outer panel 11.

Next, the tank outer panel 11 is joined to the tank inner panel 12. This completes the fuel tank 1 consisting of the tank outer panel 11 and the tank inner panel 12.

Next, the bracket 40 is attached to the front of the fuel tank 1. That is, the first fixing portion 41 of the bracket 40 is fastened to the front stay 20 joined to the front fixing portion 16 of the tank inner panel 12. Specifically, the rubber bushes 52 are attached to the pair of fastening holes 41a of the first fixing portion 41, and the rubber bushes 52 are inserted into the pair of boss members 25 of the front stay 20. Then, in this state, the first fastening members 51 are screwed into the screw holes 25a of the pair of boss members 25. At this time, washers 53 are placed between the heads of the fastening members 51 and the rubber bushes 52. As a result, the rubber bushes 52 are sandwiched and fixed between the heads (or washers 53) of the first fastening members 51 and the plate member 21, and the first fixing portion 41 is fixed to the boss member 25 via the rubber bushes 52.

Next, the second fixing portion 42 of the bracket 40 is fastened to the main frame 111. Specifically, the second fastening members 55 are inserted through the pair of fastening holes 42a of the second fixing portion 42, respectively, and the second fastening members 55 are screwed into the boss portions 111a of the left and right main frames 111, respectively, thereby fixing the second fixing portion 42 to each main frame 111. Through the above procedure, the front portion of the fuel tank 1 is fixed to the left and right main frames 111.

[Action and Effect]
As described above, in this embodiment, the front stay 20 including the plate member 21 (main plate 22 and sub-plate 23) and the boss member 25 is joined to the front fixing portion 16 of the tank inner panel 12, and the boss member 25 is connected to the main frame 111 via the bracket 40, thereby fixing the fuel tank 1 to the vehicle body (vehicle frame 101). Such a configuration has the advantage that the fuel tank 1 can be appropriately fixed to the vehicle body with a relatively simple structure.

Specifically, in this embodiment, a large-area main plate 22 and a small-area sub-plate 23 are overlapped and joined in the thickness direction to construct a plate member 21 including a first joint R1 and a second joint R2 of different plate thicknesses (see FIG. 6). Then, a boss member 25 is joined to the second joint R2 of greater plate thickness, and the first joint R1 of smaller plate thickness is joined to the front fixing portion 16 of the tank inner panel 12. This allows the boss member 25 to be firmly joined to the plate member 21, and ensures good joint quality between the plate member 21 and the tank inner panel 12.

More specifically, the second joint R2, which is an overlapping region between the main plate 22 and the sub-plate 23, has a thickness equivalent to the total thickness (t1+t2 in FIG. 5 ) of both plates 22, 23. The thickness of this second joint R2 is greater than the thickness of the first joint R1 where both plates 22, 23 do not overlap (i.e., the thickness t1 of the main plate 22 alone). Therefore, by joining the boss member 25 to the second joint R2 having such a large thickness, the boss member 25 can be firmly joined to the plate member 21 while projecting from the plate member 21.

On the other hand, since the first joint R1, which has a small plate thickness, is joined to the tank inner panel 12, the difference in plate thickness between the two can be suppressed, and good joining quality can be ensured. That is, the plate thickness t3 of the tank inner panel 12 is generally limited to a relatively small value from the viewpoint of reducing the weight of the fuel tank 1, etc. When joining the plate member 21 to such a thin tank inner panel 12 by spot welding, if the difference in plate thickness between the two is large, problems such as poor penetration are likely to occur, and the possibility of poor joining increases. In contrast, in this embodiment, the first joint R1, which has a relatively small plate thickness, is joined to the tank inner panel 12 by spot welding, and as a result of the small plate thickness difference, problems such as poor penetration are less likely to occur, and good joining quality can be ensured.

In this manner, in this embodiment, the joining of the boss member 25 to the plate member 21 and the joining of the plate member 21 to the tank inner panel 12 can both be performed satisfactorily, so that the boss member 25 can be securely fixed to the tank inner panel 12 via the plate member 21. Therefore, by connecting the boss member 25 to the main frame 111 via the bracket 40, the front part of the fuel tank 1 can be properly fixed to the main frame 111, and the support rigidity of the fuel tank 1 can be increased.

In addition, in this embodiment, where the joining quality between the plate member 21 (first joint R1) and the tank inner panel 12 is easily ensured, there is no need to perform post-processing such as brazing to supplement the joining strength. This makes it possible to increase the support rigidity of the fuel tank 1 while simplifying the structure that secures the front of the fuel tank 1 to the vehicle body.

In addition, in this embodiment, the plate thickness t2 of the sub-plate 23 is made larger than the plate thickness t1 of the main plate 22. With this configuration, the plate thickness (t1 + t2) of the second joint R2 consisting of the overlapping region of the main plate 22 and the sub-plate 23 can be made sufficiently large, and the boss member 25 can be joined to the second joint R2 with sufficient strength.

In addition, in this embodiment, the upper end of the boss member 25 is inserted into the joining hole h2 formed in the sub-plate 23, and the upper end is welded to the periphery of the joining hole h2. Also, an insertion hole h1 through which the boss member 25 can be inserted is formed in the main plate 22. With this configuration, the boss member 25 can be firmly joined to the sub-plate 23 while protruding downward from the main plate 22 through the insertion hole h1.

In particular, in this embodiment in which the joining hole h2 is provided in the subplate 23, the weld bead W (see FIG. 4 and FIG. 5) generated by welding the boss member 25 to the subplate 23 does not get in the way when the subplate 23 is joined to the main plate 22, so the joining quality between the main plate 22 and the subplate 23 can be improved. That is, if the upper end of the boss member 25 is butt-welded to the lower surface of the subplate 23 without a hole, the weld bead generated by the welding will be interposed between the main plate 22 and the subplate 23, and there is a possibility that a gap will be formed between the main plate 22 and the subplate 23. In contrast, in this embodiment, the upper end of the boss member 25 is welded to the periphery of the joining hole h2, so that the weld bead W is formed on the upper surface of the subplate 23. This avoids the above-mentioned situation in which the weld bead is interposed between the main plate 22 and the subplate 23, and the main plate 22 and the subplate 23 can be joined while being sufficiently in close contact with each other.

In this embodiment, an upwardly recessed recess 16b is formed in the area of the front fixing portion 16 of the tank inner panel 12 facing the sub-plate 23. That is, the front fixing portion 16 has a rectangular frame-shaped protrusion 16a that is joined to the peripheral portion (first joint portion R1) of the main plate 22, and a recess 16b formed in an area inside the protrusion 16a that overlaps (faces) the sub-plate 23 in a bottom view. With this configuration, the recess 16b can form a space in which the sub-plate 23 fits so that the sub-plate 23 does not interfere with the front fixing portion 16 when the main plate 22 is joined to the protrusion 16a. This can further improve the joining quality between the plate member 21 and the front fixing portion 16.

In addition, in this embodiment, a non-through screw hole 25a is formed in the boss member 25, and the first fixing portion 41 of the bracket 40 is fastened to the boss member 25 via the first fastening member 51 that is screwed into the screw hole 25a. With this configuration, it is possible to prevent the tank inner panel 12 from being damaged due to human error when screwing the first fastening member 51 into the screw hole 25a of the boss member 25. If the screw hole 25a penetrates the boss member 25, for example, if a fastening member with a longer axial length than the original is mistakenly used, the fastening member may penetrate the boss member 25 and reach the tank inner panel 12 (the wall surface of the recess 16b), causing damage to the tank inner panel 12. In contrast, in this embodiment in which the screw hole 25a is non-through, there is no need to worry about a fastening member of a different size penetrating the boss member 25. Therefore, damage to the tank inner panel 12 as described above can be avoided, and the quality of the fuel tank 1 can be ensured.

In this embodiment, a rubber bushing 52 is attached to a fastening hole 41a formed in the first fixing portion 41 of the bracket 40. The rubber bushing 52 is compressed and fixed by the first fastening member 51 that is screwed into the boss member 25 while surrounding the boss member 25. With this configuration, the rubber bushing 52 can absorb vibrations transmitted from the main frame 111 (vehicle body) to the fuel tank 1 via the bracket 40, and vibrations of the fuel tank 1 can be suppressed. This contributes to improving the riding comfort of the motorcycle.

In addition, in this embodiment, protrusions 24 are provided on the left and right side edges of the main plate 22, and hanging holes 24a are formed in the protrusions 24. With this configuration, the fuel tank 1 can be suspended during painting by using parts that are joined to the fuel tank 1 for fixing to the vehicle body. In particular, in this embodiment, the main plate 22 that is joined to the front fixing portion 16 of the tank inner panel 12 has hanging holes 24a formed therein, so that the fuel tank 1 can be suspended with the front of the fuel tank 1 facing up during painting. This means that the fuel tank 1 is suspended with the rear of the fuel tank 1, including the fuel supply hole 12b, facing down. If the fuel tank 1 is suspended in this manner, excess liquid that has infiltrated into the interior (storage space S) of the fuel tank 1 can be easily sucked out from the fuel supply hole 12b. That is, when the fuel tank 1 is painted, liquid such as a solvent used in pretreatment such as degreasing may have infiltrated into the interior of the fuel tank 1. Even in such a case, according to the present embodiment in which the hanging hole 24a is formed in the main plate 22, the fuel tank 1 can be hung with the rear part of the fuel tank 1, including the fuel supply hole 12b, facing downwards, so that the liquid can be easily sucked out by, for example, introducing a suction hose into the inside of the fuel tank 1 from the fuel supply hole 12b.

[Modification]
In the above embodiment, the relationship t2>t1>t3 is established among the plate thickness t1 of the main plate 22, the plate thickness t2 of the sub-plate 23, and the plate thickness t3 of the tank inner panel 12 (fuel tank 1), but the plate thickness relationship is not limited to this. For example, the plate thicknesses t1 and t2 of the main plate 22 and the sub-plate 23 may be set to be the same, or the plate thickness t1 of the main plate 22 may be made larger than the plate thickness t2 of the sub-plate 23. Furthermore, the plate thickness (t1 or t2) of at least one of the main plate 22 and the sub-plate 23 may be equal to or smaller than the plate thickness t3 of the tank inner panel 12.

In the above embodiment, the plate member 21 is formed by overlapping and joining two plates (main plate 22 and sub-plate 23) with different areas in the thickness direction, but the plate member 21 may be formed from a single plate whose thickness varies depending on the location. In other words, the plate member 21 may be a plate formed so that the portion joined to the fuel tank 1 (first joint R1) has a small thickness and the portion joined to the boss member 25 (second joint R2) has a large thickness, regardless of whether it is a combination of multiple plates or a single plate.

In the above embodiment, the plate thicknesses t1 and t2 of the main plate 22 and the sub-plate 23 constituting the plate member 21 are set to be greater than the plate thickness t3 of the tank inner panel 12 (fuel tank 1), but the relationship of the plate thicknesses is not limited to this. However, at least the plate member 21 should be formed so that the plate thickness (t1 + t2 in the above embodiment) of the second joint R2 is greater than the plate thickness t3 of the tank inner panel 12. In this way, the first joint R1 of the plate member 21 can be well joined to the fuel tank 1 while improving the formability of the fuel tank 1. That is, by making the plate thickness of the tank inner panel 12 smaller than the plate thickness of at least the second joint R2, the formability when the tank inner panel 12 is molded by press molding or the like can be improved, and the manufacturing efficiency of the fuel tank 1 can be increased. On the other hand, the plate thickness of the tank inner panel 12 being smaller than the plate thickness of the second joint R2 means that the plate thickness difference between the tank inner panel 12 and the first joint R1 is kept small. This makes it less likely that defects such as poor penetration will occur when welding the tank inner panel 12 to the first joint R1, ensuring good joint quality.

In the above embodiment, an example was described in which a pair of (two) boss members 25 are joined to the plate member 21, but the number of boss members is not limited to two, and may be one or three or more.

In the above embodiment, the tank inner panel 12 is formed with the front fixing portion 16 including the protrusion 16a to which the plate member 21 (main plate 22) is joined and the recess 16b recessed into the protrusion 16a, but the shape of the front fixing portion 16 is not limited to this. For example, a plate member having a flat surface facing the front fixing portion 16 can be used, and in such a case, the front fixing portion 16 can be formed flat. Even when the plate member 21 including the main plate 22 and the subplate 23 is used as in the above embodiment, the front fixing portion 16 only needs to have a recess recessed so that a gap is generated at least in the joint portion (weld bead W) between the upper end of the boss member 25 and the periphery of the joint hole h2 of the subplate 23. This makes it possible to avoid interference between at least the weld bead W and the tank inner panel 12.

In the above embodiment, an example was described in which the fuel tank fixing structure of the present disclosure was applied to the front part of the fuel tank 1, but the fuel tank fixing structure of the present disclosure can also be applied when fixing a part of the fuel tank other than the front part to the vehicle body.

In the above embodiment, an example was described in which the fuel tank fixing structure of the present disclosure was applied to a motorcycle, which is a type of saddle-ride type vehicle, but the fuel tank fixing structure of the present disclosure can also be applied to other saddle-ride type vehicles, such as three-wheeled vehicles and four-wheeled buggies.

[summary]
The above embodiment and its modified examples can be summarized as follows.

The fuel tank fixing structure is a structure for fixing a fuel tank to the body of a saddle-type vehicle, and includes a plate member joined to the fuel tank, a boss member joined to the plate member while protruding from the plate member in an out-of-plane direction, and a connecting member connecting the boss member to the body. The plate member includes a first joint portion which is a joint portion with the fuel tank, and a second joint portion which is a joint portion with the boss member, and is formed so that the plate thickness of the second joint portion is greater than the plate thickness of the first joint portion.

In this embodiment, the boss member is joined to the second joint of the plate member having a large plate thickness, so that the boss member can be firmly joined to the plate member while protruding from the plate member. Meanwhile, the first joint of the plate member having a small plate thickness is joined to the fuel tank, so that the joining quality of the two can be ensured well. That is, the plate thickness of the fuel tank is generally limited to a relatively small value from the viewpoint of weight reduction, etc. When joining a plate member to such a fuel tank having a small plate thickness by spot welding, etc., if the difference in plate thickness between the two is large, problems such as poor penetration are likely to occur, and the possibility of poor joining increases. In contrast, in this embodiment, the first joint, which has a relatively small plate thickness, is joined to the fuel tank, so that the plate thickness difference can be suppressed, and good joining quality can be ensured.

In this manner, in this embodiment, the joining of the boss member to the plate member, and the joining of the plate member to the fuel tank can both be performed satisfactorily, so that the boss member can be securely fixed to the fuel tank via the plate member. Therefore, by connecting the boss member to the vehicle body via a connecting member, the fuel tank can be properly fixed to the vehicle body, and the supporting rigidity of the fuel tank can be increased.

In addition, in this embodiment, it is easy to ensure the quality of the joint between the plate member (first joint) and the fuel tank, and there is no need to perform post-processing such as brazing to supplement the joint strength. This makes it possible to increase the support rigidity of the fuel tank while simplifying the structure that secures the fuel tank to the vehicle body.

Preferably, the plate thickness of the fuel tank is smaller than the plate thickness of the second joint.

In this embodiment, the first joint of the plate member can be satisfactorily joined to the fuel tank while improving the formability of the fuel tank. That is, by making the plate thickness of the fuel tank smaller than at least the plate thickness of the second joint of the plate member, the formability when forming the fuel tank by press forming or the like can be improved, and the manufacturing efficiency of the fuel tank can be increased. On the other hand, the plate thickness of the fuel tank being smaller than the plate thickness of the second joint means that the difference in plate thickness between the fuel tank and the first joint can be kept small. This makes it less likely that defects such as poor penetration will occur when welding the fuel tank to the first joint, and therefore ensures good joining quality.

Preferably, the plate member includes a main plate and a sub-plate that is joined to the main plate in a state where it overlaps with the main plate in the thickness direction and has a smaller area than the main plate. In this case, the overlapping area of the main plate and the sub-plate in the plate member is the second joint, and the non-overlapping area of the main plate with the sub-plate is the first joint.

In this embodiment, by overlapping and joining a sub-plate having a smaller area to a main plate having a larger area, it is possible to easily form the plate member having different plate thicknesses depending on the location (including the first joint portion and the second joint portion).

Preferably, the thickness of the sub-plate is greater than the thickness of the main plate.

In this embodiment, the plate thickness of the second joint portion consisting of the overlapping area between the main plate and the sub-plate can be made sufficiently large, and the boss member can be joined to the second joint portion with sufficient strength.

Preferably, the subplate has a connection hole capable of receiving the end of the boss member on the fuel tank side. The main plate has an insertion hole at a position overlapping with the connection hole, through which the boss member can be inserted.

In this embodiment, the boss member can be firmly joined to the subplate while allowing the boss member to protrude from the main plate through the insertion hole.

In particular, in this embodiment where a joining hole is provided in the subplate, the weld bead that is generated, for example when welding the end of the boss member to the periphery of the joining hole, does not get in the way when joining the subplate and the main plate. This allows the main plate and the subplate to be joined while being sufficiently in close contact with each other, improving the joining quality between the two.

Preferably, the fuel tank has a recess that is recessed so that a gap is created at the joint between the end of the boss member and the periphery of the joint hole.

In this embodiment, it is possible to prevent the joint portion (e.g., the weld bead) between the end of the boss member and the periphery of the joint hole from interfering with the fuel tank.

More specifically, it is preferable that the fuel tank has a joint portion that is joined to the main plate, and a recess that is formed in an area facing the subplate and is recessed into the joint portion.

In this embodiment, the main plate can be satisfactorily joined to the joint portion that protrudes into the recess. In addition, the recess can form a space in which the subplate fits so that the subplate does not interfere with the fuel tank when the main plate is joined.

Preferably, the fuel tank fixing structure further includes a fastening member that fastens the connecting member to the boss member. The boss member has a screw hole into which the fastening member is screwed and a blocking portion that blocks the end of the screw hole on the fuel tank side.

In this embodiment, it is possible to prevent the fuel tank from being damaged due to human error when screwing the fastening member into the threaded hole of the boss member. If the threaded hole were to pass through the boss member, for example, if a fastening member with a longer axial length than intended was mistakenly used, the fastening member could pass through the boss member and reach the wall surface of the fuel tank, damaging the fuel tank. In contrast, in this embodiment, in which the threaded hole does not pass through, there is no need to worry about a fastening member of a different size passing through the boss member. This makes it possible to avoid the above-mentioned damage to the fuel tank and ensure good quality of the fuel tank.

1: Fuel tank 16a: Protruding portion (jointed portion)
16b: Recess 21: Plate member 22: Main plate 23: Sub-plate 25: Boss member 25a: Screw hole 25b: Closure portion 40: Bracket (connecting member)
41: First fixing portion 42: Second fixing portion 51: First fastening member (fastening member)
R1: First joint R2: Second joint h1: Insertion hole h2: Joint hole t1: Plate thickness (of main plate) t2: Plate thickness (of sub-plate) t3: Plate thickness (of fuel tank)

Claims (9)

A structure for fixing a fuel tank to a body of a saddle-type vehicle,
a plate member joined to the fuel tank by welding ;
a boss member joined to the plate member in a state where the boss member protrudes in an out-of-plane direction from the plate member;
a connecting member that connects the boss member to the vehicle body,
a plate member including a first joint portion which is a joint portion with the fuel tank and a second joint portion which is a joint portion with the boss member, and which is formed so that the plate thickness of the second joint portion is greater than the plate thickness of the first joint portion. 2. The fuel tank fixing structure for a saddle-type vehicle according to claim 1,
A fuel tank fixing structure for a saddle-type vehicle, wherein a plate thickness of the fuel tank is smaller than a plate thickness of the second joint portion. 3. The fuel tank fixing structure for a saddle-type vehicle according to claim 1,
the plate member includes a main plate and a sub-plate that is joined to the main plate in a thickness direction and has an area smaller than that of the main plate,
a second joint portion that is a portion of the plate member that is not overlapped with the subplate and ... 4. The fuel tank fixing structure for a saddle-type vehicle according to claim 3,
A fuel tank fixing structure for a saddle-type vehicle, wherein a plate thickness of the sub-plate is greater than a plate thickness of the main plate. The fuel tank fixing structure for a saddle-type vehicle according to claim 3 or 4,
the sub-plate has a joining hole capable of receiving an end of the boss member on the fuel tank side,
The main plate has an insertion hole, through which the boss member can be inserted, at a position overlapping with the joining hole. 6. The fuel tank fixing structure for a saddle-type vehicle according to claim 5,
The fuel tank has a recess that is recessed so as to create a gap at a joint portion between the end of the boss member and a periphery of the joint hole. 7. The fuel tank fixing structure for a saddle-type vehicle according to claim 6,
a fuel tank fixing structure for a saddle-type vehicle, the fuel tank having a joint portion joined to the main plate, and the recess portion formed in an area facing the sub-plate and recessed toward the joint portion. The fuel tank fixing structure for a saddle-type vehicle according to any one of claims 1 to 7,
A fastening member for fastening the connecting member to the boss member is further provided.
The boss member has a threaded hole into which the fastening member is screwed, and a closing portion that closes an end of the threaded hole on the fuel tank side. A fuel tank that stores fuel and is fixed to the vehicle body ;
a plate member joined to the fuel tank by welding ;
a boss member joined to the plate member in a state where the boss member protrudes in an out-of-plane direction from the plate member;
a bracket including a first fixing portion fixed to the boss member and a second fixing portion fixed to the vehicle body,
the plate member includes a first joint portion that is a joint portion with the fuel tank and a second joint portion that is a joint portion with the boss member, and is formed so that the plate thickness of the second joint portion is greater than the plate thickness of the first joint portion.

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