JPS6339784B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a main nozzle of a vaporizer, and more particularly,
This invention relates to a main nozzle structure that improves the uniformity of fuel supply.

In order to comply with automobile exhaust regulations and improve fuel economy, atomization of the fuel supplied to the engine and prevention of temporal fluctuations are important issues, and unless these are resolved, the objectives cannot be achieved.

FIG. 1 is a sectional view showing the main fuel system of a conventional carburetor. A large bench lily portion 2 is formed in the middle of the intake passage 1, and a throttle valve 12 is installed downstream of the large bench lily portion 2. A holder part that integrally supports the second bench lily part 3 and the small bench lily part 4 is installed at the upper part of the large bench lily part 2, crossing the intake passage 1, and its left end surface is attached to the wall surface of the carburetor with a retaining screw 13. The main nozzle 5 is fixed in the small bench lily part 4.
is placed facing upward. Further, a nozzle hole 15 is provided at the tip of this main nozzle 5, and a nozzle hole 14 is provided on the bottom surface, and a slightly larger hole is formed in the small bench lily portion 4 around the main nozzle 5, and this hole is provided in the holder portion. Assist air passage 6 with an inlet on the top surface
is connected to.

The right end of the main nozzle 5 communicates with a fuel passage containing a mixing tube 8, and the lower end of this fuel passage communicates with the bottom of the float chamber 10 via a main jet 9. The mixing tube 8 is provided with a large number of bleed holes, the upper end of which serves as the main air bleed 7. Note that a float 11 is installed in the float chamber 10.
to keep the fuel level constant.

FIG. 2 is a sectional view taken along the line AB in FIG. 1, showing a cross section of the holder portion 19 passing through the assist air passage 6. FIG. An assist air passage 6 communicates with an annular space around the main nozzle 5, and the outer shape of the holder portion 19 is streamlined to reduce resistance to intake air flow. Since the assist air passage 6 provided perpendicularly to the holder portion 19 receives the dynamic pressure of the intake air flow, as the amount of intake air increases, the flow rate of air flowing through the assist air passage 6 also increases.

In the main fuel system configured in this way, when the intake flow rate increases, the negative pressure in the main nozzle 5 increases, and fuel is sucked in through the main jet 9, and air is sucked in from the main air bleed 7. This air is injected into the fuel from the numerous bleed holes in the mixing tube 8 and becomes a gas-liquid mixed flow, which then flows through the nozzle hole 1 of the main nozzle 5.
It erupts from 4,15. At this time, the air flow introduced from the assist air passage 6 scatters the fuel droplets that come out from the nozzle holes 14 and 15 and adhere to the outer surface of the main nozzle 5 and the small bench lily, and the air is emptied by the falling fuel droplets. Prevents fluctuations in fuel ratio.

Generally, the phenomenon of fuel droplets adhering to the outer surface of the main nozzle 5 tends to occur during relatively low-speed operation where the jetting speed of the air-fuel mixture is low, but in such cases, the dynamic pressure of the air flow applied to the assist air passage 6 is small, Not very effective. Particularly, assist air is required when fuel starts to come out from the main nozzle 5, but at this time the amount of assist air is small. On the other hand, during high-speed operation with a large amount of fuel supplied, the intake air flow rate passing through the small bench lily section 4 becomes high, so that the fuel jetted from the main nozzle 5 is actively atomized, and assist air is not required. However, at this time, the amount of assist air also increases in response to the dynamic pressure of the intake flow, resulting in the following negative effects.

Since the amount of air introduced from the assist air passage 6 increases, the outflow of the air-fuel mixture from the downward injection hole 14 of the main nozzle 5 is inhibited, thereby reducing the amount of fuel supplied. During so-called high-speed operation, a phenomenon occurs in which the fuel supply reaches a ceiling, and the amount of air-fuel mixture supplied to the engine becomes diluted. Also, since the outflow direction of the assist air is perpendicular to the intake air, the small bench lily portion 4
This reduces the intake air flow rate within the main nozzle 5 and reduces the negative pressure generated within the main nozzle 5. This also causes the fuel supply to reach a ceiling. Furthermore, since the flow velocity of the fuel jetted out from the nozzle hole 15 is promoted, the small bench lily portion 4
The fuel is sprayed onto the opposite wall of the wall, causing the fuel to adhere to the wall and inhibiting the atomization of the fuel. That is, the air introduced from the assist air passage 6 has the disadvantage that it reduces the atomization of the fuel and impairs the proportionality of fuel supply at medium and high speeds.

For example, in Japanese Patent Application Laid-Open No. 54-58141,
Related technology is disclosed.

An object of the present invention is to provide a main nozzle of a carburetor suitable for improving the proportionality of fuel supply to the intake air amount and atomization of fuel. It has a holder part to support, and a main nozzle provided in the holder part, one end communicating with the mixing pipe and the other end protruding into the small bench lily part, and assist air introduced from the assist air passage provided in the holder part. of,
In the vaporizer configured such that the air flows out from an opening formed in the inner circumferential wall surface of the small bench lily part toward the tip of the main nozzle through an annular air passage provided between the main nozzle and the holder part. Entrances of the assist air passage are opened on both side surfaces of the holder portion viewed from the tip side of the main nozzle, and an outlet of the assist air passage is opened on an inner circumferential wall surface of the bench lily portion below the tip of the main nozzle.

FIG. 3 is a sectional view of a main fuel system according to an embodiment of the present invention, and FIG. 4 is a sectional view taken along line CD in FIG.
The same parts as in FIGS. 1 and 2 are given the same reference numerals, but in this case, assist air passages 16a and 16b are provided on both sides of the streamlined holder part 19 that supports the small bench lily part, etc. The annular air passage communicating with this assist air passage 16 has an outlet into the small bench lily part 4 only in the lower half of the main nozzle 5, and a blow-through prevention part 17 is provided in the upper half.

In this way, the pressure in the assist air passages 16a, 16b decreases as the amount of intake air increases, so the amount of air entering from the assist air passage 16 remains approximately constant regardless of the amount of intake air. Therefore, unlike in the conventional case, the speed of the fuel ejected from the nozzle hole 15 is increased and the fuel is collected in the intake air flow and passed through the small bench lily portion 4 without adhering to the opposite wall. In addition, since the entire amount of assist air flows out only along the outside of the lower half of the main nozzle 5,
The fuel flowing out of the nozzle hole 14 can be completely prevented from dripping along the inner wall surface of the small bench lily portion 4.
That is, the conventional assist air passage 6 provides a dynamic effect proportional to the intake flow path, but in this embodiment, the assist air passage 6 provides a static effect in which the amount of assist air does not change much even if the intake flow rate changes. Since it is given, the conventional drawbacks are removed.

Furthermore, when fuel starts to come out from the main nozzle 5, it is particularly easy for the fuel to flow down the inner wall surface of the small bench lily section 4, but as described above, two assist air passages 16 are provided so that the fuel flows only to the bottom surface of the main nozzle 5. As a result, the amount of assist air is much larger than before. Therefore, atomization at the beginning of fuel discharge is promoted.

The members forming the small bench lily part 4 and the second bench lily part 3 shown in FIG.
It is fixed with a retaining screw 13 shown in the figure, which facilitates machining of the holder portion 19. In particular, it becomes easier to form the assist air passage 16 and the blow-through prevention part 17, which improves productivity and reduces costs.

In the main fuel system of this embodiment, the assist air passages are provided on both sides of the holder part, and the outlet of the assist air is formed only in the lower half of the outer periphery of the main nozzle, so that the air is ejected from the nozzle hole of the main nozzle. This has the effect of improving the atomization of the fuel and supplying a uniform air-fuel mixture even when the main fuel starts to flow.

In the above embodiment, the blow-through prevention part 17 is formed in the holder part, but the assist air outlet of the holder part 19 is processed into an annular shape, and the outer diameter of the main nozzle 5 is expanded by 180 degrees to form the blow-through prevention part 17. It can also be formed.

The main nozzle of the carburetor of the present invention has the effect of atomizing the fuel and supplying a uniform air-fuel mixture to the engine regardless of the amount of intake air and even when the main fuel starts to flow. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main fuel system of a conventional carburetor, FIG. 2 is a sectional view taken along line AB in FIG. 1, and FIG. 3 is a sectional view of the main fuel system according to an embodiment of the present invention. FIG. 4 is a sectional view taken along the line CD in FIG. 3. 1...Intake path, 2...Large bench lily, 4...
Small bench lily section, 5... Main nozzle, 6... Assist air passage, 7... Main air bleed, 8
... Mixing pipe, 9 ... Main jet, 12 ... Throttle valve, 13 ... Holding screw, 14, 15 ... Nozzle hole,
16...Assist air passage, 17...Blow-through prevention part, 18...O ring, 19...Holder part.

Claims (1)

[Scope of Claims] 1. A holder part that supports a small bench lily part of a vaporizer, and a main nozzle provided in the holder part, one end of which communicates with the mixing tube and the other end of which projects into the small bench lily part, The assist air introduced from the assist air passage provided in the holder part is passed through the annular air passage provided between the main nozzle and the holder part, and then from the opening formed in the inner circumferential wall surface of the small bench lily part to the main nozzle. In the carburetor configured to flow out toward the tip of the nozzle, the inlet of the assist air passage is opened on both sides of the holder part when viewed from the tip of the main nozzle, and the outlet of the assist air passage is connected to the main nozzle. A main nozzle of a vaporizer, characterized in that the main nozzle of the vaporizer is opened at the inner circumferential wall surface of the bench lily section at the lower part of the tip. 2. The claim that the holder is a member that is manufactured separately from the main body of the carburetor and is fitted to the upper end of a large bench lily formed on the inner wall of the main body of the vaporizer. The main nozzle of the vaporizer according to item 1.