JPH0517407Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a percolation prevention mechanism for a carburetor of an internal combustion engine.

[Conventional technology]

Generally, when an engine is stopped and left in a high temperature state, the fuel in the carburetor is heated and its light components evaporate, creating vapor.The buoyancy of these vapor bubbles causes liquid fuel to flow and overflow from the main nozzle. The so-called percolation phenomenon occurs. Due to this percolation phenomenon, fuel in the float chamber flows out and accumulates in the intake manifold from the intake passage, creating an extremely rich condition that makes restarting difficult. In the past, countermeasures against this problem include measures such as a constriction configuration, a wire mesh configuration, or a gas-liquid separation tube that prevents the bubbles from growing large, in order to prevent the floating bubbles caused by the evaporation of light components in the gasoline liquid from spewing out the liquid fuel together. It has been taught.

In addition, in Utility Model Application Publication No. 54-39727, the passage inside the main well is simplified by providing a bleed air chamber around the outer periphery of the main well, and when vapor is generated, the vapor can move smoothly inside the main well, resulting in a high temperature. This prevents fuel from being improperly extruded and causing percolation.

Furthermore, in Japanese Patent Application Laid-Open No. 55-140729, an outer tube is arranged outside the emulsion tube in the main well, and a fuel vapor release passage is arranged which communicates the outside of the outer tube with the downstream side of the throttle valve in the intake passage. A float valve is provided to close the discharge passage when the liquid level in the main well is constant, and fuel vapor is generated when the engine is at high temperature, making it easy for percolation to occur. When this happens, the float valve opens and releases vapor downstream of the throttle valve, preventing percolation.

[Problem that the invention attempts to solve]

The above-described aperture configuration and wire mesh configuration for preventing percolation are of little use when a large amount of percolation occurs above a certain limit. Furthermore, even if the gas-liquid separation configuration is used, the vapor release area may be inappropriate and the fuel may be taken out again, or if a vapor bleed is provided to release the vapor, the air may be removed from there depending on the engine operating condition. This causes excessive air bleed, which causes the air-fuel ratio to become too lean during transient periods, resulting in breathing problems, which makes it difficult to achieve both drivability and percolation countermeasures.

Also, Utility Model Publication No. 54-39727, Japanese Patent Application Publication No. 55-
All of the methods listed in Publication No. 140729 allow vapor to escape smoothly into the intake passage when it is generated, thereby preventing liquid fuel from flowing due to vapor bubbles and being discharged in large quantities from the main nozzle. Efforts have been made to prevent this, but even in this case, if a large amount of vapor is generated, the fuel will flow through the main nozzle together with vapor bubbles into the intake passage, making the intake air rich and causing percolation. The effect of prevention of staining does not improve.

[Means for solving problems]

In order to solve the above problems, in the present invention, as shown in FIGS. 1 and 2, the main fuel passage 10 is
In the carburetor 1, the fuel stored in the main well 12 is emulsified with bleed air and then injected into the intake passage 2 through the main nozzle 5. A vapor bleed 15 is provided, a main fuel tube 13 communicating with the main nozzle 5 is provided in the main well 12, a plurality of communication holes 14 for air bleed emulsion are bored in the side wall of the main fuel tube 13, The lower end 13a of the tube provides an anti-percolation mechanism for an internal combustion engine arranged such that the main fuel passage opens below the opening 10c connecting with the main well.

[Effect]

When the engine is stopped at a high temperature, fuel bubbles generated in the liquid fuel stored in the main well 12 from the float chamber 6 via the main jet 8 and the main fuel passage 10 are stored in the main fuel tube 13 in the main well 12. The air floats along the outer wall and is discharged outward from the main air bleed/vapor bleed 15 bored above the main well. This prevents the liquid fuel from rising and being ejected from the main nozzle 5 due to the floating of fuel bubbles as in the conventional case.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

1 and 2 show a schematic cross-sectional view of this embodiment. The carburetor 1 has a small bench lily 3 and a large bench lily 4 formed in its intake passage 2, and the small bench lily 3 has a main nozzle 5. is open. A float level 7 is maintained within the float chamber 6 and fuel is stored therein. The fuel metered at the main jet 8 and power jet valve 9 joins together at the main fuel passage 10, and flows through the reverse U.
It enters a bubble separation chamber 11 forming a letter-shaped well. This bubble separation chamber 11 is provided at a position lower than the float chamber oil level 7. Furthermore, a check valve 18 is provided at the upper end of this bubble separation chamber 11, which opens by the buoyancy of vapor bubbles.This valve 18 forms a closed circuit and is closed when the main fuel passage is not under negative pressure during engine operation. It does not inhibit sexuality. When vapor bubbles are generated while the engine is stopped, the check valve 18 is opened and the vapor is returned to the flow chamber 6 through the passage 19. The main fuel from which air bubbles have been removed enters the main well 12 of the present invention. A main fuel tube 13 is disposed within the main well 12, and the main fuel tube 13 communicates with the main nozzle 5 at its upper end.

Further, a large number of emulsion holes 14 for air bleed are bored in the side surface of the main fuel tube 13. During engine operation, metered air enters the main well 12 through the main air bleed/vapor bleed 15 provided above the main well 12, passes from the outside of the main fuel tube 13 through the air bleed emulsion hole 14, and enters the tube 1.
3, where the air bubbles and fuel mix to form a foam, and fuel is ejected from the main nozzle 5 in response to opening and closing of the throttle valve 16.
That is, in the emulsion air bleed within the main well, air flows from the outside to the inside, contrary to the conventional emulsion tube. Further, the lower end 13a of the main fuel tube 13 is lowered and deepened by Hmm below the position of the opening 10c of the main fuel passage 10 to the main well 12, as shown in FIG. After the bubbles in the fuel in the main fuel passage 10 enter the main well 12, they rise as they are and do not enter the main fuel tube 13. Also, the lower end 13a of this main fuel tube 13
is cylindrical and open, and there is no resistance to the flow of fuel through it.

Due to the above structure, vapor bubbles generated in the main fuel passage 10 and main well 12 while the engine is stopped at high temperature will not enter the main fuel tube 13, and will float only on the outside of the tube 13 and The air bleed/vapor bleed 15 is reached, and at this time, the bleed 15 acts as a vapor bleed and releases the fuel vapor to the outside. Therefore, since the vapor bubbles do not pass through the main nozzle 5, a large amount of fuel is not carried out and outflowed from the main nozzle by the vapor bubbles as in the conventional type, and the occurrence of percolation is prevented.

In addition, in this embodiment, a bubble separation chamber 11 is provided just before the main well 12, and its shape is formed into an inverted U-shape as shown in FIG. A check valve 18 is provided which opens. Check valve 18
The vapor bubbles that have passed through return to the float chamber 6 through the passage 19. This check valve 18
During engine operation, the fuel passage becomes under negative pressure and forms a closed circuit, so drivability is not affected.

FIG. 3 shows an example in which the configuration of the bubble separation chamber 11 is changed. In this case, the configuration inside the main well 12 remains unchanged as described above. In this case, the check valve 18 for removing air bubbles is the same as in the previous embodiment, but the shape of the air bubble separation chamber 22 is different. That is, in the case of FIG. 1, the main fuel passage 10 is a passage 10a leading from the main jet 8 to the bubble separation chamber 11.
and the passage 10b leading from the bubble separation chamber 11 to the main well 12 are arranged on the same horizontal plane,
In this example, the passage 10a and the passage 10b are the third
As shown in Fig. 20, the height difference is hmm. This makes use of the property that the bubbles do not sink downward to increase the effect of bubble separation.

Further, FIG. 4 shows another example in which the configuration of the bubble separation chamber is changed. In this case, an inverted U-shaped well 33 for the bubble separation chamber 33 is provided in the downward passage downstream of the upper end of the inverted U-shaped well 33 in which the slow jet 42 can be housed. This has the advantage that the passage of the slow jet 42 of the slow system 40 of the carburetor shown in FIG. 1 can be simplified.

With the above configuration, when the engine is left stopped in a high temperature state and fuel vapor is generated in the carburetor, the vapor in the fuel is first separated in the bubble separation chambers 11, 22, and 33, and this vapor is Passage 1
The remaining vapor is returned to the float chamber via the main well 12, ascends the outer periphery of the main fuel tube 13, and is discharged to the outside from the main air bleed/vapor bleed 15. In this way, the vapor in the fuel can be completely discharged to the outside from outlets other than the main nozzle, so the floating of these vapor bubbles causes a large amount of liquid fuel to be ejected from the main nozzle, resulting in percolation. It is possible to prevent the phenomenon from occurring.

Although the above embodiment has been explained by applying it to a carburetor installed in an automobile engine, the scope of application of the present invention is not limited thereto, and can be applied to a carburetor installed in a general internal combustion engine. The same applies to

[Effect of idea]

Implementation of the present invention has the following effects.

(1) By discharging the fuel bubbles generated by the engine through the vapor bleed, a large amount of liquid fuel is not discharged from the main nozzle along with the bubbles as in the conventional method, and the occurrence of percolation phenomenon can be prevented. .

(2) By reversing the flow of air into and out of the emulsion tube in the conventional air bleed system so that air flows from the outside to the inside of the tube, and by making it function as both the main air bleed and vapor bleed, It is now possible to use both bleeds while the engine is running and when it is stopped.
Unlike in the past, air enters through the vapor bleed during operation, resulting in a lean phenomenon, and the engine drivability and percolation countermeasures are both achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional explanatory diagram of an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the main well portion of FIG. 1, and FIG.
The figure shows another example of the bubble separation chamber shown in Fig. 1, and Fig. 4
The figure shows yet another example of the bubble separation chamber. DESCRIPTION OF SYMBOLS 1... Carburetor, 2... Intake passage, 5... Main nozzle, 6... Float chamber, 8... Main jet, 9... Power jet valve, 10...
...Main fuel passage, 11, 22, 33...Bubble separation chamber, 12...Main well, 13...Main fuel tube, 14...Air bleed emulsion hole, 15...Main air bleed and vapor bleed, 18... ...Check valve, 40...Slow type.

Claims (1)

[Scope of Claim for Utility Model Registration] The structure is such that the fuel stored in the main well passes through the main fuel passage from the float chamber through the main jet, is emulsified with bleed air, and then is injected into the intake passage through the main nozzle. In the vaporizer, a main air bleed/vapor bleed is provided in the upper part of the main well, a main fuel tube communicating with the main nozzle is provided in the main well, and a side wall of the main fuel tube is provided with an air bleed emulsion. A percolation prevention mechanism for an internal combustion engine, wherein a plurality of communication holes are bored, and the lower end of the tube opens below an opening where the main fuel passage connects with the main well.