JPS6239382A - Fuel feeder for scooter type car - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply device used in scooter-type motorcycles and tricycles.

[Prior art]

Conventionally, the fuel tank of a scooter-type motorcycle is installed almost directly above the engine, and the difference in water head between the fuel tank and the carburetor is used to transfer the fuel in the fuel tank to the float of the carburetor. It is supplied to the room.

By the way, recently, the present applicant has proposed installing the fuel tank in front of the footboard for placing the feet, that is, for example, inside the leg shield, in order to secure storage space for, for example, a helmet under the seat. The application has already been completed.

According to this configuration, the fuel tank and the engine's carburetor are separated from each other by a large distance in the front and rear, and the bottom of the fuel tank is located below the float chamber. A fuel pump is installed to forcibly pump fuel toward the float chamber.

[Problem that the invention seeks to solve]

However, in the configuration of this prior art, when the fuel level in the fuel tank decreases and its liquid level falls below the fuel level in the float chamber, the pressure fluctuations applied to the float chamber become large, making it difficult to maintain a stable state. There was a problem that made fuel supply difficult.

[Means for solving problems]

Therefore, in the present invention, the fuel supply line connecting the fuel tank and the float chamber is branched between the fuel pump and the float chamber, and this branched line is located at a position higher than the float chamber by a water head difference H1. It is characterized by communicating above the highest liquid level of the fuel tank.

[Effect]

According to this configuration, when the liquid level in the float chamber reaches a specified level due to fuel supply from the fuel pump, the fuel is returned to the upper part of the fuel tank at a position higher than the water head difference H1 through the pipe. In this case, the fuel level in the pipe will be higher than the liquid level in the float chamber by the head difference H1, just as when the tank is full, so the float chamber will have a head pressure corresponding to this height H1. act.

In addition, a stable water head is obtained in the pipe line by the amount of the fuel being pushed up by the water head difference H1, so even if the liquid level in the fuel tank falls below the liquid level in the float chamber, the pressure in the float chamber Fluctuations can be suppressed to a minimum, and stable fuel supply can be achieved.

Further, since there is no need to provide a special orifice or the like in the pipe line to increase pipe resistance, the pipe line configuration can be simplified.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on the drawings in which the present invention is applied to a scooter type motorcycle.

Figure 2 birth number 1 shows an underbone-shaped frame,
This frame 1 is largely bent downward between a front fork 2 that supports a front wheel 2a and a rear seat 3, and a footboard 5 is installed on this bent portion 4. The front end of the footboard 5 stands up upwards,
A pufferfish shield 6 is continuously provided, and a wide space 7 is secured between the leg shield 6 and the seat 3 in which the driver's feet can be placed.

Further, a swing type engine unit 8 is pivotally supported at the rear end of the bending portion 4 . Engine unit 8 of this embodiment
is a combination of a two-stroke engine 9 and a transmission case 10 that houses a V-belt continuously variable transmission. It supports the rear wheels 11 which are driven by.

Note that the area from below the seat 3 to around the engine 9 is covered with a cover 12.

On the other hand, a fuel tank 13 is arranged inside the leg shield 6 located in front of the space 7. A cylindrical inlet 16 that is opened and closed by a tank cap 15 is formed on the top surface of the fuel tank 13, and the bottom of the fuel tank 13 is connected to a float chamber 14 of a carburetor 14 connected to the engine 9.
It protrudes below a. Therefore, as shown in FIG. 1, the fuel level L2 in the float chamber 4a is
is located above the lowest fuel level L1 in the fuel tank 13. And these fuel tanks 13
The foot chamber 14a and the foot chamber 14a are communicated with each other, and the piping structure for this communication will be described below.

That is, the fuel outlet 17 at the bottom of the fuel tank 13 and the float chamber L4a are connected by a communication pipe 18 serving as a fuel supply path. It is led rearward through a position lower than the minimum liquid level L1, that is, below the footboard 5, and is connected to the float chamber 14a located at a position higher than the minimum liquid level L1. A fuel pump 19 is installed in the middle of this communication pipe 18 to forcibly feed fuel to the float chamber 14a. It is located below L+.

Although the fuel pump 19 of this embodiment uses a pulse pump whose driving source is the pulsating pressure in the crank chamber of the engine 9, other electromagnetic pumps may be used.

Further, the communication pipe 18 is connected to the fuel pump 19 and the float chamber 14a.
This branched pipe is connected to the upper part of the fuel tank 13 as a fuel return pipe 20. That is, this fuel return pipe 20 is branched from the communication pipe 18 and then guided forward through the lower part of the footboard 5 which is lower than the lowest liquid level L1 of the fuel tank 13, and its front end is in front of the footboard 5. has been launched again. The upper end of this fuel return pipe 20 is connected to the upper end of the fuel tank 13, and the communication part of this fuel return pipe 20 is connected to the liquid level L1 of the float chamber L4a.
The highest liquid level L of the fuel tank 13 is higher than the water head difference H1.
It is located above 3.

Note that fuel filters 21 are provided at the fuel outlet 17 of the fuel tank 13 and the fuel return pipe 20, respectively.

According to such an embodiment of the present invention, the fuel return pipe 20 branched from the communication pipe 18 is connected to the highest liquid level in the fuel tank 13 located at a position higher than the liquid level L2 in the float chamber 14a by the head difference H1. Since the communication is made above the surface level L3, when the liquid level L2 in the float chamber 14a reaches the specified liquid level with the pressure feeding of fuel from the fuel pump 19, the fuel sent from the fuel pump 19 is transferred to the fuel return pipe. 20 and is returned to the fuel tank 13.

At this time, the liquid level of the fuel in the fuel return pipe 20 is higher than the liquid level L2 in the float chamber 14a by the head difference H1, as is the case when the tank is full. A corresponding hydraulic head pressure acts on this fuel return pipe 20.
Inside, the fuel is pushed up by the water head difference H1, and a stable water head is obtained.

Therefore, even if the liquid level of the fuel in the fuel tank 13 falls below the liquid level L2 in the float chamber 14a while driving, the pressure fluctuation in the float chamber 14a is suppressed to a small level, and the remaining m of fuel in the fuel tank 13 is reduced. Even when the fuel is low, a stable fuel supply can be maintained.

Further, according to this configuration, there is no need to install a special orifice or the like in the middle of the fuel return pipe 20 to increase the pipe resistance, and the structure of the fuel return pipe 20 can be simplified.

In addition, after the engine has stopped, if the fuel in the float chamber 4a evaporates under the influence of heat from the engine side and the liquid level drops, the fuel corresponding to the water head difference H1 in the fuel return pipe 20 is automatically removed. It is replenished into the float chamber 4a. Therefore, even during restart, the liquid level in the float chamber 4a is always maintained at a specified level, and good startability can be ensured.

Note that the vehicle according to the present invention is not limited to a motorcycle, but can be similarly applied to a tricycle having two rear wheels.

〔Effect of the invention〕

According to the present invention described in detail above, even if the fuel level in the fuel tank is lower than the liquid level in the float chamber, a stable fuel supply can be performed, and in addition, a special orifice is provided in the conduit to increase the conduit resistance. There is no need to provide the same, and there is an advantage that the structure can be simplified.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of a fuel supply path, and FIG. 2 is a partially cutaway side view of a scooter type motorcycle. 2...Front fork, 3...Seat, 7...
Space, 9...Engine, 13...Fuel tank, 14
... Carburetor, 14a... Float chamber, 18... Fuel supply path (communication pipe), 19... Fuel pump, 20...
・Pipe line (fuel return pipe). Applicant's agent Patent attorney Takehiko Suzue Figure 1 2a Figure 2

Claims (1)

[Claims] A space for the driver's feet is provided between the front fork and the seat, a fuel tank is placed in front of this space, and an engine is connected to the engine behind the space. In a scooter type vehicle in which a carburetor is arranged and the liquid level in the float chamber of the carburetor is located above the lowest liquid level of fuel in the fuel tank, a fuel supply path connecting the fuel tank and the float chamber. At the same time, this fuel supply line is branched between the fuel pump and the float chamber, and this branched line is connected to the highest liquid level of the fuel tank located at a position higher than the float chamber by a head difference of H_1. A fuel supply device for a scooter type vehicle, characterized in that the fuel supply device communicates upward.