JP2008238900A - Fuel tank of motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel tank of a motorcycle capable of holding satisfactory appearance even when using the fuel tank molded by injection molding. <P>SOLUTION: This motorcycle is provided with an engine 6 between a front wheel 5 and a rear wheel 9 and the fuel tank 11 formed by joining an upper tank 110 and a lower tank 120 mutually above the engine 6. Joint faces 112, 122 of the upper tank 110 and the lower tank 120 are provided between a side face 11b and a bottom face 11a of the fuel tank 11, and the joint face 112 on an upper tank 110 side is an inclined face 112b spreading outward and downward. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel tank for a motorcycle including a fuel tank formed of a resin material.

  A fuel tank formed from a resin material is known. Currently, such resin material molding methods include blow molding, injection molding, rotational molding, and the like. In a fuel tank of an automobile or the like, the entire fuel tank is integrally formed to reduce the manufacturing cost. Blow molding is often used. On the other hand, in blow molding, since it is difficult to make the plate thickness of the wall portion of the fuel tank thin or uniform, injection molding is also used (for example, see Patent Document 1).

In the case of manufacturing a fuel tank by this injection molding, it is necessary to form an upper tank and a lower tank in which the fuel tank is halved, and to join these upper tank and lower tank at a joint.
JP 2004-98886 A

  It is preferable that the joint surface of the joint portion between the upper tank and the lower tank is as flat as possible in order to improve adhesion. Therefore, it was necessary to join at the side of the fuel tank. However, in the type of motorcycle in which the fuel tank can be viewed from the outside of the vehicle body, the appearance on the side of the motorcycle is impaired.

  The present invention has been made in view of the above-described circumstances, and provides a motorcycle fuel tank capable of maintaining good appearance even when a fuel tank molded by injection molding is used. With the goal.

According to the present invention, there is provided a motorcycle including an engine between a front wheel and a rear wheel, and a fuel tank that is formed by joining an upper tank and a lower tank above the engine, and the joint surface between the upper tank and the lower tank is a fuel. It is provided between the side surface and the bottom surface of the tank, and the upper tank side joining surface is an inclined surface extending downward and outward.
According to this configuration, the joint surface of the fuel tank can be made inconspicuous from the outside of the motorcycle.

Further, the upper tank and the lower tank can be joined by ultrasonic welding, and a projection can be provided as a welding margin on the lower end side of the joining surface of the lower tank.
According to this structure, the protrusion can be melted by ultrasonic welding to weld the joint surface of the fuel tank.

Furthermore, the upper tank and the lower tank may be joined by laser welding.
According to this configuration, the joining surface of the fuel tank can be easily welded.

According to the present invention, since the joint surface of the upper tank and the lower tank is provided between the side surface and the bottom surface of the fuel tank, the joint portion of the fuel tank can be made inconspicuous from the outside of the motorcycle. As a result, the appearance of the motorcycle can be improved even when a fuel tank cover that covers the outer peripheral surface of the fuel tank is not provided.
In addition, since the joint surface on the upper tank side is an inclined surface that spreads downward and outward, when ultrasonic welding is performed, the joint surface can be easily added by simply forming an inclined surface that is similarly inclined on the joint surface on the lower tank side. Can be pressed. Furthermore, when laser welding is performed, a recess for irradiating laser light can be easily formed by making the joint surface on the lower tank side flat. As a result, the welding operation can be easily performed.

  In addition, the upper tank and the lower tank are joined by ultrasonic welding, and a protrusion is provided as a welding margin at the lower end side of the lower tank joining surface. Therefore, by melting the protrusion by ultrasonic welding, the fuel tank The joining surface can be easily welded. Moreover, assembly accuracy is also improved by performing ultrasonic welding.

  Furthermore, since the upper tank and the lower tank are joined by laser welding, the joining surface of the fuel tank can be easily welded. In addition, assembly accuracy is improved by performing laser welding.

(First embodiment)
Hereinafter, a fuel tank for a motorcycle according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a motorcycle equipped with a fuel tank according to a first embodiment of the present invention. In the following description, the vertical direction and the front-rear direction indicate directions based on FIG. 1, and the left-right direction indicates a direction viewed from the driver.

  The motorcycle 1 is attached to a body frame 2, a pair of left and right front forks 3 rotatably supported by a head pipe 30 at the front of the body frame 2, and a top bridge 3 A that supports the upper end of the front fork 3. A steering wheel 4, a front wheel 5 rotatably supported by the front fork 3, an engine (internal combustion engine) 6 supported by the vehicle body frame 2 at the approximate center of the vehicle body, and a front of the engine 6. A radiator 7, a swing arm 8 supported by the rear end of the engine 6 and the vehicle body frame 2 so as to swing up and down, a rear wheel 9 rotatably supported by the rear end of the swing arm 8, and a swing arm The left and right rear cushions 10 disposed between the rear portion of the vehicle body 8 and the vehicle body frame 2, and the engine 6 so as to straddle the vehicle body frame 2 over the vehicle body frame 2. A fuel tank 11 disposed above, and a seat 12 disposed behind the fuel tank 11.

A bracket 13 is attached between the top bridge 3A and the bottom bridge 3B that support the front fork 3. A headlight 14, a blinker 15, a meter 16, and a horn 17 are attached to the bracket 13. The switch box 18 and the rearview mirror 19 are attached.
Further, an air cleaner side cover 20, a side cover 21, a rear cowl 22, a grab rail 23 and a rear fender 24 are attached to the body frame 2, and a taillight 25 and a winker 26 are attached to the rear fender 24. A side stand 27 and a main stand 28 are attached.

The vehicle body frame 2 includes a pair of left and right main pipes 31 that extend from the head pipe 30 to the rear of the vehicle body and then bend and extend obliquely downward from the vehicle body. A pair of left and right down tubes 33 extending to the left and a pair of left and right seat rails 34 supported by a cross member 31A disposed in the middle of the main pipe 31 and extending rearward of the vehicle body.
Further, the vehicle body frame 2 includes a pair of left and right reinforcing frames 35 that connect the head pipe 30 and the main pipe 31, and a pair of left and right reinforcing frames 36 that connect the reinforcing frame 35 and the down tube 33. 36, the rigidity of the body frame 2 is further increased.

The rear end of the main pipe 31 is joined to the down tube 33, and a pair of left and right pivot plate portions 37 that pivotally support the swing arm 8 that supports the rear wheel 9 are joined to the main pipe 31 and the down tube 33 at the joined portion. Has been.
The rear end of the down tube 33 is joined to a seat rail 34, and the seat rail 34 supports the seat 12, the rear cowl 22, and the like. In addition to the cross member 31A, a cross member is appropriately disposed in the vehicle body frame 2, and appropriate frame rigidity is secured by the cross member and the like.

The main pipe 31 and the down tube 33 are provided with a plurality of engine hangers 39, and the engine 6 is supported via the engine hangers 39.
Thus, the engine 6 is supported in a gap surrounded by the main pipe 31 and the down tube 33. The engine 6 is connected to the crankcase 40, a cylinder block 41 extending substantially upward from the front portion of the crankcase 40, a cylinder head 42 connected to the upper part of the cylinder block 41, and an upper part of the cylinder head 42. This is an in-line multi-cylinder (4-cylinder) engine including a head cover 43 and four cylinders arranged in a horizontal row in a cylinder block 41.

In the cylinder block 41, a piston is accommodated in each cylinder (cylinder) so as to be reciprocally movable. In the crankcase 40, a crank shaft, a counter shaft and an output shaft (main shaft) connected to the piston via a connecting rod. 45 and the like are supported, and a power transmission mechanism (clutch mechanism), a transmission mechanism and the like for connecting / disconnecting between the crankshaft and the countershaft are accommodated.
As shown in FIG. 1, the output shaft 45 and the rear wheel 9 are provided with sprockets 46 and 47, respectively, and the power of the engine 6 is transmitted through the drive chain 48 wound around the sprockets 46 and 47. It is transmitted to the wheel 9. Note that the motorcycle 1 of the present embodiment includes a six-speed transmission mechanism for forward movement.

  As shown in FIG. 1, exhaust pipes 60 are connected to the exhaust ports 50A of the exhaust ports 50. The exhaust pipes 60 extend downward from the exhaust ports 50A to the vehicle body. And is connected to a collective exhaust pipe, and is connected to the muffler 62 via the collective exhaust pipe. A throttle body 70 is connected to the intake port 55A of each intake port 55 via an insulator (pipe), and an air cleaner 80 is connected to the rear of the throttle body 70.

  The air cleaner 80 includes an outside air introduction part 81 into which outside air is introduced and a clean air part 82. The outside air introduction part 81 cleans the outside air with a built-in air filter and supplies it to the clean air part 82. The clean air part 82 is connected to the throttle body 70 and supplies the engine 6 with the clean air stored in the clean air part 82 by the negative pressure in the cylinder of the engine 6. Here, the clean air part 82 has a capacity capable of storing the amount of air required by the engine 6 and also functions as a surge tank that absorbs intake pulsation.

  A storage case 95 that stores the battery 91 and the control unit 90 is disposed behind the air cleaner 80. The control unit 90 is also referred to as a PGM-FI (Electronically Controlled Fuel Injector) / IGN unit, and as shown in FIG. 4, electronic components such as various sensors provided in the motorcycle 1 are connected by wiring.

FIG. 2 is a side view showing the fuel tank shown in FIG. 1 alone. FIG. 3 is a cross-sectional view of the fuel tank taken along line AA in FIG. 2 and is shown upside down.
As shown in FIG. 2, the fuel tank 11 has a substantially streamlined shape in the longitudinal direction of the vehicle body (the left side is the front in FIG. 2). As shown in FIG. 3, a bottom surface 11 a of the fuel tank 11 is formed in the lower central portion of the fuel tank 11 so as to be recessed upward (downward on the paper surface of FIG. 3). As shown in FIG. 2, the bottom surface 11 a in the depressed state is formed continuously in the front-rear direction of the vehicle body. When the fuel tank 11 is attached to the vehicle body, the recess in the bottom surface 11 a becomes the vehicle body frame 2. It has come to straddle. The side surface 11b of the fuel tank 11 is visible from the outside of the vehicle body, and constitutes the exterior surface of the motorcycle 1.

The fuel tank 11 is divided into an upper part of the fuel tank 11 and an upper tank 110 having a side face 11b, and a lower part of the fuel tank 11 and a lower tank 120 having a bottom face 11a. .
The upper tank 110 is integrally formed by injection molding. The mold for injection molding of the upper tank 110 is divided into two in the vertical direction in FIG. 3 so that the fuel supply port 111 is formed.
The lower tank 120 is also integrally formed by injection molding. The injection mold for the lower tank 120 is also divided into two parts in the vertical direction in FIG.

  As the resin material used for these upper tank 110 and lower tank 120, various resin materials (for example, polyamide resin) having low gas permeability and excellent heat resistance that are not easily affected by heat convection from the engine 6 are used. It can be used.

  The joint portion 100 that joins the upper tank 110 and the lower tank 120 is formed in the lower portion of the side surface 11 b of the fuel tank 11 so that the joined portion does not appear on the external appearance surface of the fuel tank 11. More specifically, as shown in FIG. 3, the fuel tank 11 is formed between the lower edge portion of the side surface 11b and both side portions of the bottom surface 11a. Further, the position of the joint portion 100 in the front-rear direction is formed in such a manner that it makes one round along the lower edge of the side surface 11b of the fuel tank 11, as shown by a two-dotted line (indicated by S) in FIG. .

FIG. 4A and FIG. 4B are enlarged views showing the joining of the upper tank 110 and the lower tank 120 in the joint portion 100. 5A shows a joining surface 112 on the upper tank 110 side, FIG. 5B shows a joining surface 122 on the lower tank 120 side, and FIG. 5C shows a state in which these joining surfaces 112 and 122 are joined. It is a thing.
Since this joining is performed with the fuel tank 11 turned upside down (state shown in FIG. 3), FIGS. 4 (a), 4 (b), and 5 (a) to 5 (c) are also up and down. Shown with the direction reversed.

The joining surface 112 on the upper tank 110 side and the joining surface 122 on the lower tank 120 side are formed in a shape suitable for joining by ultrasonic welding.
Here, the ultrasonic welding is a method in which a strong frictional heat is generated on the joint surface by applying a pressure simultaneously with the ultrasonic vibration, and welding is performed by the heat. The ultrasonic welding machine used for this ultrasonic dressing converts electrical energy into mechanical vibration energy, and simultaneously applies pressure to generate strong frictional heat on the two joint surfaces to melt the resin. And combine.

  The joint surface 112 on the upper tank 110 side includes a vertical surface 112a extending downward from FIG. 5A from an upper end portion 113a shown in FIG. 5A (a lower end portion when the fuel tank 11 is attached to the vehicle body). An aspect that inclines from the lower end 113b of the vertical surface 112a toward the diagonally lower right side of FIG. 5 (a) and spreads downward and outward from the fuel tank 11 when viewed with the fuel tank 11 attached to the vehicle body. And a curved surface 112c that extends downward from the lower end 113c of the inclined surface 112b in a manner that slightly protrudes to the right in FIG. 5A. That is, the bonding surface 112 is formed with a concave portion 114 that is depressed to the left in FIG. 5A by the vertical surface 112a and the inclined surface 112b.

  On the other hand, the joint surface 122 on the lower tank 120 side is inclined from the upper end portion 123b shown in FIG. 5B to the lower right side and the lower end portion 123c of the inclined surface 122b in FIG. 4B. And a vertical surface 122c extending downward. That is, the joint surface 122 is formed with a convex portion 124 that protrudes to the left in FIG. 5B with the upper end portion 123b as a vertex. This convex part 124 becomes a welding margin in ultrasonic welding.

Next, a procedure for joining these joining surfaces 112 and 122 will be described.
The ultrasonic vibration amplified by the transmitter of the ultrasonic landing machine (not shown) is transmitted to the vibrator 140 shown in FIG. As shown in FIG. 3, the upper tank 110 is supported by support portions 141 a and 141 b that support both sides of the upper tank 110 toward the inside of the upper tank 110 and receives a lower portion of the upper tank 110 (the upper surface of the fuel tank 11). 141c.

  While applying ultrasonic vibration near the joint surface 122 of the lower tank 120 by the vibrator 140, the joint surface 122 is moved to the upper tank 110 side (Z direction in FIG. 4). Then, the inclined surface 122b on the lower tank 120 side is pressed against the inclined surface 112b on the upper tank 110 side. At this time, as shown in FIG. 5C, a force to escape in the Y direction in FIG. 4 acts on the inclined surface 112b of the upper tank 110 by the inclination angle of the inclined surfaces 112b and 122b. By receiving this force by the support portion 141a (see FIG. 3), pressure is generated on the joint surfaces 112 and 122. Thereby, frictional heat is generated mainly on the inclined surfaces 112b and 122b, and the joining surfaces are welded. At this time, since the convex portion 124 located on the joint surface 122 of the lower tank is easily melted by frictional heat, the convex portion 124 is positively welded to the concave portion 114 of the joint surface 112.

According to the fuel tank of the motorcycle according to the first embodiment of the present invention, the joining surfaces 112 and 122 of the upper tank 110 and the lower tank 120 are provided between the side surface 11b and the bottom surface 11a of the fuel tank 11, so that the fuel The joint part 100 of the tank 11 can be made inconspicuous from the outside of the motorcycle. As a result, the appearance of the motorcycle 1 can be improved even when a fuel tank cover that covers the outer peripheral surface of the fuel tank 11 is not provided.
Further, since the joining surface 112 on the upper tank 110 side is an inclined surface 112b that spreads downward and outward, when ultrasonic welding is performed, it is only necessary to form the inclined surface 122b that is similarly inclined on the joining surface 122 on the lower tank 120 side. The joining surfaces 112 and 122 can be easily pressurized.

  Further, the upper tank 110 and the lower tank 120 are joined by ultrasonic welding, and the protrusion 124 is provided as a welding margin at the lower end side of the joining surface of the lower tank 120. Therefore, by melting the protrusion 124 by ultrasonic welding. The joining surfaces 112 and 122 of the fuel tank 11 can be easily welded. Moreover, assembly accuracy is also improved by performing ultrasonic welding.

(Second Embodiment)
In the second embodiment, the joining surface 222 of the lower tank 220 is brought into contact with the joining surface 112 of the upper tank 110 in the first embodiment, and laser joining is performed. Since other structures are the same as those of the first embodiment, detailed description thereof is omitted.

6A shows a joining surface 112 on the upper tank 110 side, FIG. 6B shows a joining surface 222 on the lower tank 220 side, and FIG. 6C shows a state in which these joining surfaces 112 and 122 are joined. It is.
Since this joining is performed with the fuel tank 11 upside down (the state shown in FIG. 3), FIGS. 6A to 6C are also shown upside down.

The joining surface 112 on the upper tank 110 side and the joining surface 222 on the lower tank 220 side are formed in a shape suitable for joining by laser welding.
Here, laser welding is a method for welding resin members using a laser beam.
As a laser irradiation method used for the laser welding method, a locus processing is typically performed in which a laser is irradiated and scanned with a spot and the locus portion is welded. Since the laser welding method uses a laser, fine welding is possible. Furthermore, since it is not necessary to provide a melting margin in advance, it has a feature that burrs are hardly formed at the joint.

The joint surface 112 on the upper tank 110 side is shown from the upper end portion 113a shown in FIG. 6A (the fuel tank 11 is shown upside down, so that the lower end portion when the fuel tank 11 is attached to the vehicle body side). 6 (a), a vertical surface 112a extending downward, an inclined surface 112b inclined from the lower end 113b of the vertical surface 112a toward the lower right side of FIG. 6 (a), and a lower end of the inclined surface 112b. A curved surface 112c extending downward from 113c in a manner slightly projecting to the right in FIG. 6 (a). That is, the bonding surface 112 is formed with a concave portion 114 that is depressed to the left in FIG. 6A by the vertical surface 112a and the inclined surface 112b.
On the other hand, as shown in FIG. 6B, the joint surface 222 on the lower tank 220 side is constituted only by a vertical surface 222c extending downward from the upper end 223c.

Next, a procedure for joining these joining surfaces 112 and 222 will be described.
The joint surface 222 of the lower tank 220 is moved to the upper tank 110 side (Z direction in FIG. 3). Then, the vertical surface 222c on the lower tank 220 side is applied to the curved surface 112c on the upper tank 110 side. Then, the laser is irradiated from the concave portion 114 of the upper tank 110 toward the inside of the joint portion on the upper side of FIG. Thereby, the part irradiated with the laser is welded. At this time, the concave portion 114 located on the joint surface 112 of the upper tank 110 forms a gap for allowing the laser light to reach the inside of the joint surface. In the second embodiment, the convex portion 124 described in the first embodiment is not provided on the joint surface 222 of the lower tank 220 because the convex portion 124 blocks the laser beam. is there.

In the motorcycle fuel tank according to the second embodiment of the present invention, the joining surfaces 112 and 222 of the upper tank 110 and the lower tank 220 are provided between the side surface 11b and the bottom surface 11a of the fuel tank 11, The joint part 200 of the tank 11 can be made inconspicuous from the outside of the motorcycle. As a result, the appearance of the motorcycle 1 can be improved even when a fuel tank cover that covers the outer peripheral surface of the fuel tank 11 is not provided.
Further, since the joint surface 112 on the upper tank 110 side is an inclined surface 112b that spreads downward and outward, when performing laser welding, the joint surface 222 on the lower tank 220 side is made a flat surface 222c, so that the concave surface 114 of the upper tank 110 is removed. Laser light can be applied to the inside of the bonding surfaces 112 and 222. As a result, the welding operation can be easily performed.

1 is a side view of a motorcycle equipped with a fuel tank according to a first embodiment of the present invention. It is a side view which shows the fuel tank of FIG. It is sectional drawing of the fuel tank cut | disconnected by the AA line of FIG. 2, Comprising: The up-down direction in FIG. 2 is reversely shown. BRIEF DESCRIPTION OF THE DRAWINGS It is 1st Embodiment of this invention, Comprising: (a) is sectional drawing which shows the state before joining of a joint surface, (b) is sectional drawing which shows the state after joining of a joint surface. BRIEF DESCRIPTION OF THE DRAWINGS It is 1st Embodiment of this invention, Comprising: (a) is an expanded sectional view of the joint surface of an upper tank, (b) is an expanded sectional view of the joint surface of a lower tank, (c) joins each joint surface. It is the expanded sectional view made into the state. It is the 2nd Embodiment of this invention, (a) is an expanded sectional view of the joining surface of an upper tank, (b) is an expanded sectional view of the joining surface of a lower tank, (c) joins each joining surface. It is the expanded sectional view made into the state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motorcycle 2 Body frame 5 Front wheel 6 Engine 9 Rear wheel 10 Rear cushion 11 Fuel tank 11a Bottom surface 11b Side surface 31 Main pipe 33 Down tube 40 Crankcase 60 Exhaust pipe 62 Muffler 80 Air cleaner 100 Joint part 110 Upper tank 111 Fuel supply port 112 Joint Surface 112a Vertical surface 112b Inclined surface 112c Curved surface 113a Upper end portion 113b Lower end portion 113c Lower end portion 114 Recessed portion 120 Lower tank 122 Joint surface 122b Inclined surface 122c Vertical surface 123b Upper end portion 123c Lower end portion 124 Convex portion 140 Vibrator 220 Lower tank 222c Vertical surface 223c Upper end

Claims (3)

A motorcycle having an engine between a front wheel and a rear wheel, and a fuel tank formed by joining and molding an upper tank and a lower tank above the engine,
A fuel tank for a motorcycle, wherein a joint surface between the upper tank and the lower tank is provided between a side surface and a bottom surface of the fuel tank, and a joint surface on the upper tank side is an inclined surface extending downward and outward.   The fuel tank for a motorcycle according to claim 1, wherein the upper tank and the lower tank are joined by ultrasonic welding, and a protrusion is provided as a welding margin at a lower end side of the joining surface of the lower tank.   The fuel tank for a motorcycle according to claim 1, wherein the upper tank and the lower tank are joined by laser welding.

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