JPH082456Y2 - Vaporizer passage structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention (1) Field of Industrial Use The present invention relates to a carburetor mounted on a small motorcycle that can be stored upside down. The present invention relates to a passage structure as a fuel leakage countermeasure in a carburetor.

(2) Conventional technology Immediately after the engine is stopped, the amount of heat transferred from the engine and the stop of the cooling action increase the pressure in the float chamber in the carburetor, and the fuel (raw gas) in the float chamber is increased. In order to prevent the main fuel system and the low-speed fuel system from flowing into the intake passage, an air bend passage and an overflow pipe are provided, one end of which is opened above the carburetor and the other end of which is in communication with the float chamber.

Further, JP-A-57-108447 and JP-A-64-8349 disclose a passage structure of a carburetor which is provided with an air vent passage which allows a tilt for storage.

In a small motorcycle including the above-described air vent passage and overflow pipe and a carburetor having a stop valve installed in the middle thereof, when the vehicle is left unattended for a long period of time, or when the vehicle body is tilted or upright for storage. When the stop valve is closed to prevent fuel leakage, the float chamber eventually becomes overpressure due to the rise in temperature,
It is not possible to prevent the outflow of fuel into the intake passage. Therefore, it is necessary to remove the fuel from the carburetor, which is troublesome.

(3) Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and is a carburetor mounted on a small motorcycle that can be stored upside down and provided with an air vent passage and / or an overflow pipe mechanism. It is an object of the present invention to provide a carburetor passage structure in which fuel does not flow out to the intake passage even when the stop valve of the air vent passage or the overflow pipe is closed in the inverted storage state.

B. Configuration of the Invention (1) Means for Solving the Problems According to the passage structure of the carburetor for a small motorcycle of the present invention, the carburetor mounted on the small motorcycle that can be stored upside down is The carburetor main body is formed with an intake passage having a venturi portion having a reduced inner diameter at an intermediate position thereof, and a float container forming a float chamber is installed at a lower portion of the carburetor main body. In addition, a fuel passage hole that opens into the venturi portion of the intake passage and communicates with the float chamber is formed in the carburetor body in a substantially vertical direction, and the fuel passage hole has a small amount in the opening on the intake passage side. With the main fuel nozzle, one end of which is open toward the upstream side of the intake passage, and an air passage hole which communicates with the fuel passage hole is formed in the ceiling portion of the float chamber and communicates with the float chamber. Vent passage and Alternatively, in a vaporizer provided with an overflow pipe and having a stop valve installed in the middle of the air vent passage and / or the overflow pipe, an annular space between the air passage hole or the fuel passage hole and the main fuel nozzle, and the float. A space above the oil level in the chamber,
Are communicated with each other through a leak hole, and the leak hole is always located above the fuel surface in the float chamber in the inverted inclination state of the carburetor.

(2) Action In a small two-wheeled vehicle equipped with this carburetor, even if the two-wheeled vehicle is inverted upright immediately after operation, there is a leak hole above the fuel surface in the carburetor, and in this case Since the heat of the engine is high and the vaporizer does not have a cooling effect, the vaporizer can be seen to suddenly rise in temperature.

At this time, the internal pressure of the float chamber of the vaporizer also rises as the temperature rises, but since the internal pressure is conducted to the intake passage through the leak hole, the escape of evaporative gas is allowed and the pressure rises above a certain level. Does not happen. As a result, fuel as raw gas in the float chamber does not flow out into the intake passage through the fuel passage hole and the air passage hole.

(3) Embodiment An embodiment of the passage structure of the carburetor of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 show the application to a carburetor equipped with a cable-operated sliding throttle valve that is commonly used for two-wheeled vehicles as one example. That is, FIG. 1 is an overall cross-sectional view showing the internal structure of the vaporizer, and FIG. 2 shows the structure of the main part thereof.

Referring to FIG. 1 and FIG. 2, in the carburetor C, an intake passage 2 penetrating in a horizontal direction is formed in a carburetor body 1.
Further, a throttle valve guide cylinder 3 having a sliding guide hole 3a therein is formed in a projecting manner on the upper portion of the carburetor main body 1 at right angles to the intake passage 2, and on the upper portion of the throttle valve guide cylinder 3. Has a cap 4 screwed on. Reference numeral 5 is a rubber cover.

Then, in the throttle valve guide cylinder 3, it is operated by pulling up the throttle cable 7 having the end portion 6 at the end, is urged downward by the return spring 8, and the needle valve 9 is hung from the lower end surface thereof. A throttle valve 10 is installed so that it can freely move in and out of the intake passage 2. The other end of the throttle cable 7 is connected to a throttle grip (not shown). The head of the needle valve 9 is locked to the throttle valve 10 by a grip 11. A cutaway 12 is formed at the lower end of the throttle valve 10 toward the upstream side of the intake passage 2.

The lower surface of the throttle valve 10 that moves up and down and the intake passage 2 form a venturi portion.

A float container 16 forming a float chamber 15 is installed in the lower portion of the carburetor main body 1, and the inside of the carburetor main body 1 is opened to the intake passage 2 in correspondence with the float chamber 15 and is float chamber. Fuel passage hole 17 communicating with 15
A column portion 18 having (main fuel passage hole 17a, low-speed fuel passage hole 17b) formed therein is projected, and a main fuel nozzle 20, a main fuel jet 21, and a low-speed fuel nozzle 22 are provided in the fuel passage holes 17a and 17b. It can be assembled.

Small holes 20a and 22a are formed in the main fuel nozzle 20 and the low-speed fuel nozzle 22, respectively, and the fuel supplied from below through these small holes 20a and 22a and the air supplied from the outside are mixed.

An air passage hole 24 is formed in the carburetor main body 1 at the ceiling of the float chamber 15, one end of which communicates with the main fuel passage hole 17a and the other end of which opens toward the upstream side of the intake passage 2.

In such a configuration, the air passage portion A includes the air passage hole 24 and the gap space 25 between the fuel passage hole 17 and the main fuel nozzle 20 described above. 27 is the fuel stored in the float chamber 15, 27A is the oil level at all times, 28 is the float floating on the fuel 27, and the function of this float 28 causes the float valve ( The oil surface 27A of the fuel 27 in the float chamber 15 is held at a constant height together with (not shown). Although other functional members are appropriately installed in the float chamber 15, they are not shown.

Thus, in the vaporizer C of this embodiment, the float chamber
A so-called leak hole 30 communicating with the air passage portion A is formed on the ceiling surface of 15.

More specifically, the leak hole 30 is always always higher than the oil level of the fuel 27 when the motorcycle equipped with the carburetor C is tilted at the time of falling or inverted at the time of storage. It is provided.

The throttle valve 10 configured in this manner moves up and down to change the opening area of the intake passage 2 and adjust the opening of the needle valve 9 accordingly to adjust the fuel discharge amount.

The carburetor C of the present embodiment has the above-described characteristic configuration and has the following operation.

In a small two-wheeled vehicle equipped with this carburetor C, when mounted inside a four-wheeled vehicle in an inverted state immediately after driving,
Also becomes an inclined state, and the oil level 27B of the fuel 27 becomes the chain line state shown in FIG. That is, the leak hole 30 is formed on the oil surface 27 of the fuel 27.
It is above B. And the heat of the engine is high,
Moreover, since the main vaporizer C has no cooling action, the vaporizer C can be seen around a rapid temperature rise.

At this time, the internal pressures of the bath of the main vaporizer C and the chamber 15 also increase as the temperature rises, but the internal pressure is conducted to the intake passage 2 through the leak holes 30, so that the pressure does not rise. As a result, the fuel 27 in the float chamber does not flow out into the intake passage 2 via the fuel passage hole 17 and the air passage hole 24.

According to the configuration of the carburetor C of the present embodiment, even if the air vent or the overflow pipe is closed immediately after the operation, the internal pressure in the float chamber 15 does not rise, so that the labor for removing the fuel during storage is not required unlike the conventional case. It is very convenient.

The mode of the leak hole 30 is not limited to that of this embodiment. Various design changes are possible within the scope of the basic technical idea of the present invention.

3 and 4 show another arrangement of the leak holes.
In these figures, the same members as those in the previous embodiment are designated by the same reference numerals.

In the embodiment shown in FIG. 3, the main air jet 32 is mounted at the inlet of the air passage hole 24, and the leak hole 30A is provided at the back of the air passage hole 24, that is, at the downstream side of the air jet 32. It

In the embodiment shown in FIG. 4, the main air jet 33 is mounted in the innermost part of the air passage hole 24, and the leak hole 30B is opened upstream of the main air jet 33.

In the above embodiment, the carburetor having the cable-operated sliding throttle valve is shown, but it is also applicable to the negative pressure-operated sliding throttle valve carburetor and further to the butterfly valve carburetor. Needless to say.

That is, in the butterfly valve type carburetor, the main fuel nozzle is arranged so as to face the reduced diameter portion of the intake passage, that is, the venturi portion, and the fuel is discharged by the negative pressure action of the venturi portion, but it does not have a needle valve. Outside, the structure of the inside of the float chamber is based on the above embodiment.

C. Effect of the Invention According to the present invention, even when the vehicle equipped with the vaporizer is tilted or inverted for storage immediately after driving,
The air vent or the overflow pipe may be kept closed, so that it is not necessary to remove the fuel from the inside of the carburetor as in the conventional case.

[Brief description of drawings]

The drawing shows an embodiment of the passage structure of the carburetor of the present invention,
FIG. 1 is a sectional view of the entire vaporizer of the embodiment, and FIG.
FIG. 3 and FIG. 4 are enlarged views of a main part of the drawing and are views of other aspects of the leak hole. 1 ... Vaporizer main body, 2 ... Intake passage, 3 ... Throttle valve guide tube, 3a
… Sliding guide hole, 9… Needle valve, 10… Sliding throttle valve, 15…
Float chamber, 16 ... Float container, 17 ... Fuel passage, 20 ...
Main fuel nozzle, 24, 25 ... Air passage, 30, 30A, 30B ... Leak hole

Claims (1)

[Scope of utility model registration request] 1. A carburetor to be mounted on an inverted compact motorcycle that can be stored, wherein the carburetor main body is formed with an intake passage having a venturi portion having an inner diameter reduced at an intermediate position thereof. A float container forming a float chamber is installed in the lower portion of the carburetor body, and a fuel passage hole that opens to the venturi portion of the intake passage and communicates with the float chamber is substantially provided in the carburetor body. Is formed vertically,
At least the main fuel nozzle is assembled in the opening of the fuel passage hole on the intake passage side, and one end of the fuel passage hole is opened toward the upstream side of the intake passage, and an air passage hole communicating with the fuel passage hole is formed in the float chamber. A carburetor formed in a ceiling part, comprising an air vent passage and / or an overflow pipe communicating with the float chamber, and a stop valve being installed in the middle of the air vent passage and / or the overflow pipe, wherein the air passage hole Alternatively, the annular space between the fuel passage hole and the main fuel nozzle is communicated with the space above the oil surface of the float chamber by a leak hole, and the leak hole is located above the fuel surface in the float chamber with the carburetor upside down. A passage structure for a carburetor for small motorcycles, which is always located.