JPS5810144A - Carburetor - Google Patents

Abstract

PURPOSE:To enable a preferable operation of an engine under any operative condition of the engine by a method wherein even if some bubble are produced in the carburetor, they are caused to flow upwardly in the mixing pipe. CONSTITUTION:Lower end of the mixing pipe 10 is opened and an enlarged part 10b is arranged. When the mixing pipe 10 is arranged in the main well 4, bubbles 11 produced in the main well 4 are flowed upwardly and only a fuel is flowed upwardly outside of the mixing pipe 10. The bubbles 11 are mixed with the air and fuel suctioned from the main air jet 5, passed through the breeding holes 10a and flowed out of the nozzle passage 7. Continuous flow of both air containing fuel vapour and liquid fuel and another liquid fuel flowed upwardly in a clearance 12a are mixed to each other and then injected out as an air fuel mixture flow having a uniform composition from the main nozzle 8. Therefore, the mixture always shows a uniform air fuel mixture ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carburetor for an automobile engine, and more particularly to a carburetor that can prevent deterioration in drivability due to generation of gas bubbles.

FIG. 1 is a vertical cross-sectional view of a conventional vaporizer. A float chamber 1 is attached to the side of the carburetor, and Ganrin is accommodated therein up to the oil level 2. A main jet 3 is opened on the side surface of the bottom of the float chamber 1, and the gunlin that has passed through the main jet 3 rises in a main well 4 formed vertically. When the engine is rotating, intake air flows into the venturi section with the main nozzle 8 open, so negative pressure is generated in the main nozzle 8, and the air is introduced from the gantry in the main well 4 and the main air jet 5 into multiple air intakes. Bleed hole 6at
- The passed air mixes in the nozzle passage 7 and is discharged from the main nozzle 8. Note that the bleed hole 6a is located above the oil level 2 of the float chamber 1 by an amount H.

In such a fuel supply system, when the temperature around the carburetor increases, bubbles are more likely to form than the fuel in the fuel passage.
The air-fuel mixture ejected from the main nozzle 8 becomes intermittently different in density.

FIG. 2 is an enlarged view of the main part of the carburetor shown in FIG. 1, and the fuel vapor bubbles 11 generated from the fuel metered by the main jet 3 are
Since the volume expands with vaporization, it moves up intermittently through the gap between the wall of the main well 4 and the mixing tube 6. Therefore, when the bubbles 11 enter the nozzle passage 7, the mixture ejected from the main nozzle 8 becomes lean, and when the fuel enters the nozzle passage 7, the mixture becomes rich.

The air-fuel mixture ejected from the main nozzle 8 mixes with a large amount of intake air, passes around the throttle valve 9, and is supplied to the engine, so the air-fuel mixture when supplied to the engine also fluctuates greatly, which affects engine drivability. make it unsmooth. Moreover, there have been disadvantages in that the amount of harmful components in the exhaust gas increases and the amount of fuel consumed increases.

The purpose of the invention is to provide a carburetor that can supply a stable air-fuel mixture through relatively simple improvements.
Its feature is that the lower end opening of the mixing tube is expanded outward.

FIG. 3 is a sectional view of essential parts of a carburetor according to an embodiment of the invention, and the same parts as in FIG. 2 are designated by the same reference numerals. The mixing tube 10 in this case is the same as the conventional one in that it has a plurality of bleed holes 10a formed above the oil level 2, but its lower end is open and has an expanded portion lOb. That is, in relation to the wall surface of the main well 4, the gap 12b is
is small, and the gap 12a above it is a relatively wide gap similar to the conventional one. Note that the bleed hole 10a is provided above the oil level 2, as in the conventional case.

When the mixing tube 10i formed in this way is installed in the main well 4, the bubbles 11 generated in the main well 4 will rise inside the mixing tube 10, and only the fuel will rise outside the mixing tube 10. Bubbles 11 of vaporized fuel rising in the mixing tube 10 mix with the air and liquid fuel taken in from the main air jet 5, and continuously pass through the bleed hole 10ai and exit into the nozzle passage 7. This continuous flow of air and liquid fuel containing fuel vapor mixes with the liquid fuel rising in the gap 12a, and is ejected from the main nozzle 8 as a gas-liquid mixed flow with a uniform composition. Therefore, the concentration of the air-fuel mixture supplied to the engine is always a mixture with a uniform air-fuel ratio, the engine rotates smoothly, and the exhaust gas composition remains constant.

FIG. 4 is a diagram showing the relationship between the elapsed operating time of the engine and the float chamber temperature. If the high-speed operation continues at t-At, fresh gasoline is continuously supplied from the tank, so the temperature of the float chamber 1 is low and hardly changes. When the engine is stopped at point A, the temperature of the heated engine rapidly increases and reaches the maximum temperature at time B, but thereafter gradually decreases and approaches the outside temperature. When the temperature of the float chamber 1 drops by Ct, if the engine is restarted and operated at a normal running speed, the temperature will gradually rise, but will hardly change after the time.

In the case where such a change is shown, the temperature of the float chamber 1 is high B
When the engine is restarted, the vaporization of gasoline is active, so many bubbles 11 are generated as shown in FIG. 2, and most of the fuel is vaporized when it is ejected from the main nozzle 8. Therefore, a fairly uniform air-fuel mixture could be supplied to the engine. In addition, when the temperature inside the float chamber-1 drops and the engine is restarted at 7'cc, the air-fuel ratio of the air-fuel mixture changes little because the generation of air bubbles 110 is almost complete, and the engine runs smoothly. .

However, when the temperature in the float chamber 1 is at the intermediate temperature E, when the engine is restarted, the temperature in the float chamber 1 decreases slightly as shown by the dashed line and matches the solid line at D4.

At this time, the temperature of the gasoline is in a state where bubbles are likely to form intermittently, making the engine rotation unstable in synchronization with the normal operating state, and in extreme cases, causing the engine to stop. was occurring.

On the other hand, in the non-embodiment carburetor shown in FIG. 3, the vaporized gasoline and the air taken in from the main air jet 5 are mixed and exit continuously from the bleed hole 10a to the nozzle passage 7. In the nozzle passage 7, liquid gasoline passes through the inner lower side of the main nozzle 8 and rises to the tip, where it is atomized by the air passing through the venturi section, so the air-fuel ratio is maintained continuously with little fluctuation. A mixture will be supplied.

In this embodiment, the carburetor is equipped with a mixing tube with a bleed hole above the oil level in the float chamber, so that the lower end opening of the mixing tube can be expanded outward to an extent that does not interfere with the upward movement of the oil. By forming a gap, the air bubbles rising in the mixing tube are mixed with the air from the main air jet and are continuously discharged from the bleed hole, mixed with the continuously rising gas bubbles and released from the main nozzle. It can be made to squirt. Since this air-fuel mixture is continuously supplied, the air-fuel mixture with a suitable air-fuel ratio is supplied to the engine under any operating conditions, ensuring smooth operation, reducing fuel consumption, and reducing exhaust gas emissions. This has the effect of reducing the amount of harmful ingredients in it.

The vaporizer of the present invention is modified by expanding the lower end of the mixing tube inserted into the main well to the outside, so that the air bubbles can rise inside and outside the mixing tube, and when bubbles are generated, the bubbles can rise all the way inside the mixing tube. This has the effect that suitable operation can be performed regardless of the operating condition.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a conventional carburetor, Fig. 2 is an enlarged view of the main part of the carburetor shown in Fig. 1, and Fig. 3 is a sectional view of the main part of a carburetor according to an embodiment of the invention. FIG. 4 is a diagram showing the relationship between the engine operating time and the float chamber temperature. 1... Float chamber, 2... Oil level, 3... Main jet, 4... Main well, 5... Main air jet, 6°10... Mixing pipe, 6", 10a...・Bleed hole, 7... Nozzle passage, 8... Main nozzle, 1
ob... Enlarged section, 10th 蓓a

Claims (1)

[Claims] 1. A mixing tube with a main air jet formed at the upper end is installed in the main well that communicates the main jet and the main nozzle, and a plurality of mixing tubes are installed above the oil level in the float chamber of this mixing tube. vi-
Characteristic vaporizer. 2. The vaporizer according to claim 1, wherein the bleed hole is a hole formed above a position where the nozzle passage to the main nozzle branches from the main well.