JPH053729Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a chamber internal pressure adjustment mechanism that communicates the chamber internal air pressure of a circulating carburetor with the fuel tank internal air pressure so that the pressure is always at atmospheric pressure. .

(Prior Art) Conventionally, fuel is supplied into a chamber by a fuel pump, and when the oil level in the chamber exceeds a certain level, the fuel overflows and the oil level is adjusted. In a circulation type carburetor that returns to the fuel tank through a return pipe, an outer vent type carburetor that opens the chamber to the atmosphere is provided with communication holes in a part or several places of the carburetor body to allow the chamber to communicate directly with the atmosphere. be.

(Problems to be Solved by the Invention) In the conventional circulation type carburetor, the inside of the chamber is directly exposed to the atmosphere through the communication hole, so dirt is easily sucked in through the communication hole, leading to the risk of dirt clogging. There have been cases where overflow fuel leaked outside when the vehicle was heated, tilted, or vibrated.

The present invention has been developed in view of the above, and an object of the present invention is to adjust the pressure within the chamber of a circulation type carburetor to atmospheric pressure without causing dust to enter or fuel to leak.

(Means for Solving the Problems) In order to achieve the above object, the solution means of the present invention supplies fuel into a chamber by a fuel pump, and when the oil level in the chamber reaches a certain level or more, The system is based on a circulation type carburetor in which fuel overflows, the oil level is adjusted, and the overflowed fuel is returned to the fuel tank through a return pipe. The fuel tank is equipped with an atmosphere-opening breather. On the other hand, a communication passage that constantly communicates between the chamber and the fuel tank is provided, and the inside of the chamber includes the communication passage,
The fuel tank is configured to communicate with the atmosphere only through the inside of the fuel tank and the breather in order so that the pressure is always adjusted to atmospheric pressure.

(Function) As a result, in the present invention, the inside of the chamber is communicated with the atmosphere only through the communication path and the inside of the fuel tank, and through the air-open type breather, which is excellent in dust-proofing and fuel blow-out prevention properties. It also prevents fuel from leaking out when the vehicle is tilted or vibrates.

(Embodiment) FIG. 1 shows an embodiment of a chamber internal pressure adjustment mechanism in a circulation type carburetor according to the present invention. In this embodiment, the passage of the return pipe 8 has a space where sufficient air can pass through so that the inside of the chamber is always in communication with the inside of the fuel tank and the pressure is always at atmospheric pressure even when the return fuel is flowing during engine operation. In this example, the size of the return pipe 8 is designed so that it not only serves to return the return fuel to the fuel tank 5, but also serves as an air vent (communication path) that communicates the air pressure inside the chamber with the atmosphere.

A ventilation passage 2 is formed inside the body of the carburetor 1, and in the drawing, the right side is upstream and the left side is downstream.

A bench lily 3 is formed in the middle of the ventilation passage 2, and a chamber 4 having an air layer above is connected below the bench lily 3.

A fuel tank 5 is provided below the chamber 4, and the fuel tank 5 has a cap portion that includes:
It is equipped with an atmosphere-opening type breather 6 that is excellent in dust-proofing properties and in preventing fuel from blowing out.

The fuel F in the fuel tank 5 is pumped up by, for example, a diaphragm fuel pump 7 and supplied into the chamber 4 .

A return passage 8a whose upper end communicates with the chamber 4 is provided on the side of the chamber 4, and a return pipe 8 is provided at the lower end of the return 8a. The oil level in the chamber 4 is maintained at the level of the side wall 4a of the chamber 4.

The passage area of the return pipe 8 is such that the fuel F does not accumulate in the middle of the return pipe 8, and even when the fuel F is flowing, the inside of the chamber is always communicated with the inside of the fuel tank, and the pressure is always adjusted to atmospheric pressure. It is said to be wide enough so that it does not obstruct the flow of air.

Note that the fuel tank 5 has a return port 9 for the fuel F.
is provided protrudingly, and the return port 9 is inserted into the lower end of the return pipe 8.

In the carburetor 1, 10 is a choke valve, and 11 is a throttle valve that can be moved up and down.

12 is a main jet, which regulates the amount of fuel injected.

Reference numeral 13 denotes a needle jet, and by changing the insertion position of the jet needle 14 suspended from the throttle valve 11, the amount of fuel F to be ejected changes.

An air cleaner (not shown) is connected upstream of the carburetor 1, and the air cleaner uses a filter to remove dirt and dust from the air.

The carburetor 1 is connected to the cylinder 1 of the engine via a packing 15a and an insulator 15.
6.

Since this embodiment has the above-described configuration, the air in the chamber 4 can be passed through the return passage 8a, even without providing a communication hole to the atmosphere in the body of the carburetor 1.
After passing through the return pipe 8 and the fuel tank 5, it is constantly communicated with the atmosphere through the breather 6.

Therefore, since the pressure P ₁ inside the chamber is always maintained at atmospheric pressure, the pressure at the bench lily 3 is
The balance with P ₂ is not disrupted, and the amount of fuel F ejected is stabilized.

In the above embodiment, the return pipe is straight in the vertical direction and has a cylindrical shape, but the shape of the return pipe in the present invention is not limited to this, and other embodiments include a shape that is somewhat oblique, or a rectangular prism, etc. It does not matter if it is prismatic.

Further, in the embodiment described above, the return port protruding from the fuel tank is inserted into the lower end of the return pipe, but in other embodiments, if the lower end of the return port is inserted into the return pipe, This creates a smooth air flow path and further improves the function of the return pipe as an air vent.

In addition, in the present invention, as long as the passage area of the return pipe is sufficiently wide, the inner surface of the return pipe does not need to be straight as in the above embodiment, and may be tapered in other embodiments. No problem.

FIG. 2 shows an example in which a separate air pressure adjustment pipe 17 is provided to form a communication path that constantly communicates the chamber internal air section and the fuel tank internal air section.
In this case, a separate system of pipes is required, but air communication is more reliable.

Figure 3 shows the air pressure adjustment pipe 17 in a separate system.
This is an example in which the fuel tank 5 is connected to a side remote from the return pipe connection portion. With this arrangement, even if the fuel tank 5 and the entire engine are tilted, either the return pipe 8 or the air pressure adjustment pipe 17 will not be blocked by fuel. 1
If a pipe with a large area as shown in the figure is used, air communication will be more reliable even when the pipe is tilted.

(Effects of the invention) According to the invention, dirt does not enter the chamber from the outside, and the structure prevents fuel from leaking outside from the carburetor when tilting or vibrating. The pressure can always be maintained at atmospheric pressure, and the amount of fuel jetted to the bench lily can be stabilized.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the circulating carburetor according to the present invention, which also serves as a return pipe. FIG. 2 is a sectional view showing an embodiment in which a separate system of pipes for adjusting air pressure is provided. FIG. 3 is a sectional view showing an embodiment in which a pipe of another system is provided on a side remote from the return pipe. 1... Carburetor, 2... Ventilation passage, 3... Bench lily, 4... Chamber, 5... Fuel tank,
6...Atmospheric pressure release breather, 7...Fuel pump,
8... Return pipe, 17... Air pressure adjustment pipe (communication path).

Claims (1)

[Scope of utility model registration request] Fuel is supplied into the chamber by a fuel pump, and when the oil level in the chamber exceeds a certain level, the fuel overflows and the oil level is adjusted, and the overflowing fuel is returned to the fuel tank through the return pipe. In the circulation type carburetor, the fuel tank is equipped with an atmosphere-opening breather, and a communication passage is provided that constantly communicates the chamber and the fuel tank,
A chamber internal pressure adjustment mechanism for a circulation type carburetor, characterized in that the inside of the chamber communicates with the atmosphere only through the communication passage, the inside of the fuel tank, and the breather in order so that the pressure is always adjusted to atmospheric pressure.