JPH02246889A - Arrangement structure of fuel tank for motorcycle - Google Patents

Abstract

PURPOSE:To effectively lower the center of gravity of a vehicle and centralize mass and improve operation performance by arranging a fuel tank under a cylinder in front of a crankcase, when an engine under a main frame is equipped with the cylinder which projects forwardly in inclination from the crankcase. CONSTITUTION:When an engine 22 installed under a main frame 4 is equipped with a cylinder 31 which projects forwardly in inclination from a crankcase 30, an excessive space is formed under the cylinder 31 in front of the crankcase 30. Then, a fuel tank 39 having a large weight is arranged in utilization of the excessive space. Therefore, the fuel tank 39 is positioned under the frame 4, and the center of gravity can be lowered, in comparison with the conventional ways in which the fuel tank 39 is supported onto the main frame 4. Further, the engine 22 and the fuel lank 39 each of which has a large weight are installed in proximity, and the concentration of mass can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an arrangement structure for a fuel tank for a motorcycle.

(Prior Art) A motorcycle has a main frame whose body frame extends rearward and downward from a head pipe, supports a fuel tank on this main frame, and has an engine provided below the main frame. There are many things (to be seen).

Furthermore, in some of the above configurations, in order to improve the maneuverability of the motorcycle, the heavy cylinder protruding from the upper surface of the crankcase is tilted forward significantly to lower the center of gravity of the vehicle.

(Problem to be Solved by the Invention) Incidentally, in the conventional configuration described above, the center of gravity is lowered by tilting the cylinder forward, but even in this case, the heavy fuel tank of 1 weight is placed on the main frame. Therefore, the above conventional configuration is not necessarily satisfactory in terms of effectively lowering the center of gravity.

In addition to lowering the center of gravity, mass concentration is also necessary to improve maneuverability, but in the conventional configuration, the engine and fuel tank are separated vertically with the main frame in between. Therefore, this concentration of mass cannot be said to be sufficient.

(Objective of the Invention) This invention was made in view of the above-mentioned circumstances, and aims to further improve maneuverability of a motorcycle by effectively lowering the center of gravity and centralizing the mass of the vehicle. With the goal.

(Structure of the Invention) A feature of the present invention for achieving the above object is that in a motorcycle in which an engine provided below a main frame is provided with a cylinder protruding forward from a crankcase, The fuel tank is located below the cylinder at the front of the case.

(for production) The effect of the above configuration is as follows.

When the engine 22 provided below the main frame 4 is provided with a cylinder 31 that projects forward from the crankcase 30, there is an extra space below the cylinder 31 in front of the crankcase 30. Become. Therefore, the heavy fuel tank 39 is arranged here by utilizing this surplus space. As a result, this fuel tank 39
is located below the main frame 4, and as a result, a lower center of gravity can be achieved than in the conventional case where the fuel tank 39 was supported on the main frame 4.

In addition, with the above configuration, the heavy engine 2
2 and the fuel tank 39 are provided close to each other, thereby achieving mass concentration.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, 1 is a motorcycle and 2 is its body frame. The body frame 2 has a head pipe 3 at the front thereof, and a pair of left and right main frames 4.4 extend rearward and downward from the head pipe 3. Each of the main frames 4 has a wide cross section, a rectangular box shape, and an elongated shape, and has a rear arm bracket 6 extending downward at its rear end. In addition, each main frame 4 mentioned above
Seat rails 7.7 protrude rearward and upward from the front and rear midpoints, and each seat rail 7 is reinforced by a back stay 8.

A front fork 9 is supported on the head pipe 3 so as to be steerable. A front wheel 1.0 is supported at the lower end of the front fork 9, and a handle 11 is attached to the upper end of the front fork 9. 12 is a front fender.

On the other hand, the rear arm bracket 6.6 has a pivot shaft 13.
The rear arm 14 is pivotally supported to be able to swing up and down, and a rear wheel 15 is supported at the swinging end of the rear arm 14.

In this case, each main frame 4 is formed in a substantially straight line from the head pipe 3 side to the pivot portion of the rear arm 14. In other words, each main frame 4 has a box-shaped cross section as described above. In conjunction with this, it is formed to maintain sufficient strength against the load from the rear wheel 15 side.

Further, a shock absorber 16 is installed between the rear part of the main frame 4 and the rear arm 14 via a link machine '#R17. The shock absorber 16 is inserted into the vehicle body frame 2 from the rear wheel 15 side.
It cushions the impact that is transmitted to the sides, and is located at the center of the vehicle widthwise and tilted slightly forward.

19 is a seat, and this seat 19 is attached to the main frame 4.
4 and the seat rail 8.8, the seat 19 covers the space between the left and right main frames 4.4 and the space between the left and right backstays 8.8 from above. Further, a straddle fender 20 is provided behind the seat 19.

Reference numeral 22 denotes a two-stroke engine that drives the rear wheels 15, and this engine 22 is firmly supported by the vehicle body frame 2. At the rear of this engine 22 is a power transmission device 23.
The rear wheel 15 is connected to the power transmission device 23 by a chain transmission means 24. This chain transmission means 24 is composed of a drive chain wheel 26, a driven steel weight 27 attached to the rear wheel 15, and a transmission chain 28 wound around both chain wheels 26 and 27.

The power of the engine 24 is transmitted to the rear wheel l5 via the power transmission device 23, transmission chain 28, and the like.

1 to 6, the engine 22 has a crankcase 30, and a cylinder 31 projects forward from the crankcase 30, and a spark plug 32 is attached to the projecting end. Further, a carburetor 3 is provided on an intake boat formed at the front upper part of the crankcase 30.
3 is attached, and this carburetor 33 is connected to an air cleaner 35 through an intake pipe 34.

On the other hand, an exhaust pipe 36 extends rearward from an exhaust boat formed on the upper surface of the forward-inclined cylinder 31, and a muffler 36a is attached to the exhaust pipe 36. A silencer 37 is attached to the rear end.

When the engine 22 is in operation, running air A is taken in through the introduction holes 38, air cleaners 35, and intake pipes 34 provided through each main frame 4, and is mixed with fuel in the carburetor 33. 30 and is sucked into the cylinder 31. Then, it is combusted here, and then the exhaust pipe 36. The air is exhausted to the rear of the vehicle through the muffler 36a and silencer 37 in this order.

A fuel tank 3 made of sheet metal that feeds fuel to the carburetor 33
9 is provided. The fuel tank 39 includes a tank body 40 located in front of the crankcase 30 and below the cylinder 31, a tank left side 41 extending rearward from the left side of the tank body 40, and a tank left side 41 extending rearward from the right side of the tank body 40. It consists of an extending tank right side 42, which are formed as a body.

In this case, the tank left side 41 is positioned to cover the left side of the cylinder 31, and the tank right side 42 is positioned to cover the cylinder 31 and the right side of the front part of the crankcase 30. Further, the upper surface of the tank body 40 is lower than the upper surfaces of the tank left side part 41 and the tank right side part 42, that is, a recess 43 is formed in the upper surface side of the tank body 40. And 1. Through this recess 43, the spark plug 32 can be maintained, inspected, and replaced.

Incidentally, the front and side surfaces of the fuel tank 39 are formed to be smooth, and in other words, the fuel tank 39 also functions as a cowling.

Further, the fuel tank 39 is supported by the vehicle body frame 2 in the following manner.

That is, the upper surfaces of the tank left side 41 and the tank right side 42 are screwed to the corresponding main frames 4.4 by bolts 48, respectively. Further, a pair of left and right support pieces 44, 44 are protruded from the lower surface of the tank body 40. On the other hand, a support frame 45 is provided to protrude downward from the front and rear midpoints of each main frame 4, and each support frame 45 is connected to the left and right side surfaces of the cylinder 31 and the tank left side 4.
1 and the tank right side 42 and extends downward. The support piece 44 is screwed to the lower end of each support frame 45 with a bolt 47 via a rubber shock absorber 46, thereby supporting the fuel tank 39 on the vehicle body frame 2.

A radiator 50 for cooling the cylinder 31 is provided. This radiator 50 is screwed and fixed to the main frame 4.4 and the support frame 45, and when viewed from the side, the radiator 50 is attached to the cylinder 31.
It is located above the fuel tank 39 and between the front fender 12 and each main frame 4, and is also located approximately at the center between the left and right main frames 4 when viewed from the front.

Side cowls 51 are provided on each side of the radiator 50, and these left and right side cowls 51.51 are formed to gradually expand as they move forward. Further, the protruding end of the cylinder 31 and the front upper surface of the fuel tank 39 are located between the lower ends of the left and right side cowls 51, 51 on the front side of the radiator 50. Therefore, the running wind A is guided by the left and right side cowls 51, 51, the protruding end of the cylinder 31, and the front upper surface of the fuel tank 39, and is forcibly sent toward the radiator 50. Therefore, the cooling effect of the evaporator 50 is enhanced.

By the way, in the above configuration, the left and right main frames are 4°4,
The portion surrounded by the seat 19 is a dead-end recess that opens toward the front. Therefore, the high temperature air after passing through the radiator 50 is transferred to the left and right main frames 4.
If the air enters between the four spaces, this air will remain in the recess and will not be smoothly exhausted to the outside of the vehicle body.

Therefore, a discharge hole 52 is formed in a portion of each side cowl 51 between the radiator 50 and the main frame 4. Further, a resin guide plate 61 facing the radiator 50 is provided at the rear of the radiator 50, and this guide plate 61 is installed between the left and right main frames 4.4, and each of the guide plates 61 is The side ends are attached to the lower surface of each main frame 4 by screwing or gluing. The high temperature air after passing through the radiator 50 is guided outward by the guide plate 61, and
This is discharged to the outside of the vehicle body through the discharge hole 52. Note that the guide plate 61 may be made of sheet metal and welded to each main frame 4.4.

In addition, as described above, since the high temperature air after passing through the radiator 50 is smoothly discharged to the outside of the vehicle body, the left and right main frames 4, 4, the lower surface 19a of the seat 19, and the rear surface side of the guide plate 61. A space 49 that is not affected by the high temperature air is formed in the area surrounded by. Therefore, the air cleaner 35 is disposed in this space 49 to effectively utilize the surplus space that is not affected by heat.

The side cowls 51 are screwed to the main frame 4.4 and the radiator 50 with bolts 54.

Further, the front portion of the side cowl 51 covers the introduction hole 38 from the outside. The front part of the side cowl 51 guides the running wind A to the introduction hole 38, while also preventing the introduction hole 38 from being easily visible and preventing foreign matter from jumping into the introduction hole 38. ing.

According to the above embodiment, the heavy fuel tank 39, which was conventionally provided on the main frame 4, is provided below the main frame 4 and near the engine 22, thereby lowering the center of gravity of the vehicle. centralization and mass concentration will be achieved. Furthermore, since the lightweight air cleaner 35 is provided in place of the conventional fuel tank 39, the above-mentioned lowering of the center of gravity becomes even more effective.

On the other hand, a rigid protection plate 55 is provided to cover and protect the lower surfaces of the upper crankcase 30 and fuel tank 39. This protective plate 55 is dish-shaped and downwardly downwards, and the bracket 55 is attached to the lower end of each of the support frames 45 and the lower end of the rear arm bracket 6.
6 and 6, respectively, with bolts 57 and 58.

In the above case, a protrusion 60 is formed on the lower surface of the fuel tank 39, and this protrusion 60 is fitted into the front part of the protection plate 55. Further, the outer surface of the lower end of the fuel tank 39 and the outer surface of the upper end of the front part of the protection plate 55 are formed substantially flush with each other, thereby creating a sense of unity in appearance between the fuel tank 39 and the protection plate 55. It is done like this.

Further, the running wind A flows backward through between the cylinder 31 and the radiator 50, and the running air A flows between the cylinder 31 and the recess 43, and between the crankcase 30 and the protection plate 55. In other words, the entire surface of the cylinder 31 is cooled by the running wind A.

Referring to FIG. 7, a fuel supply device for supplying fuel from the fuel tank 39 to the carburetor 33 will be explained.

A fuel pump 63 is provided on the lower surface side of the crankcase 30, and this fuel pump 63 is covered from below by a protection plate 55. On the other hand, a reserve tank 64 is provided above the vaporizer 33 , and the reserve tank 64 is connected to the vaporizer 33 via the fuel tank 5 and a supply vibe 66 . And fuel tank 39
The protruding portion 60 is connected to the fuel pump 6 by the suction vibrator 67.
The discharge side of this fuel pump 63 is connected to the reserve tank 64 through a discharge vibro 8. Further, this reserve tank 64 is connected to the upper part of the fuel tank 39 through an overflow vibro 9.

The fuel pump 63 is linked to the engine 22, and if the fuel pump 63 operates in conjunction with the engine 22,
Fuel in the fuel tank 39 is continuously fed into the reserve tank 64. Then, a part of the fuel in this reserve tank 64 is transferred from the reserve tank 64 to the carburetor 33 as appropriate.
On the other hand, fuel overflowing from the reserve tank 64 is returned to the fuel tank 39 through the overflow vibro 9.

(Effects of the Invention) According to the present invention, in a motorcycle in which an engine provided below a main frame is provided with a cylinder that protrudes forward from a crankcase, a fuel tank is provided below the cylinder in front of the crankcase. This has the following effects.

That is, the present invention focuses on the fact that when an engine is provided with a cylinder that protrudes forward from the crankcase, there is an extra space in front of the crankcase and below the cylinder. The heavy fuel tank was placed here to take advantage of the space, and for this reason, this fuel tank was located below the main frame. Therefore, a lower center of gravity can be achieved than in the conventional case where the fuel tank was supported on the main frame.

Furthermore, with the above configuration, the engine and fuel tank, both of which are heavy, are placed close to each other,
Therefore, mass concentration is also achieved.

As described above, by effectively lowering the center of gravity and concentrating mass, the maneuverability of the motorcycle can be improved.

(Margin below)

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially enlarged view of Fig. 2, Fig. 2 is an overall side view of the motorcycle, Fig. 3 is a partial plan view, Fig. 4 is a partial front view, and Fig. 4 is a partial front view. Figure 5 is a partially enlarged cross-sectional view of Figure 1, Figure 6 is a partially enlarged cross-sectional view of Figure 4, and Figure 7 is a partially enlarged cross-sectional view of Figure 4.
The figure is a side view of the fuel supply device. 1. Motorcycle, 2. Body frame, 3. Head pipe, 4. Main frame, 22. Engine, 30.
・Crankcase, 31...Cylinder, 39...Fuel tank. Figure 5' / Figure 5'

Claims (1)

[Claims] 1. In a motorcycle in which a main frame extends rearward and downward from a head pipe, an engine is provided below this main frame, and the engine is provided with a cylinder that protrudes forward from the crankcase. A motorcycle fuel tank arrangement structure in which the fuel tank is located below the cylinder at the front.