JP2001140699A - Air vent passage of carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air vent passage capable of improving the fuel economical efficiency of a carburetor and reducing production cost. SOLUTION: An expansion chamber 6 vertically extending is arranged at a position above the liquid level upper chamber R of a float chamber 4. The expansion chamber 6 is provided with a first air vent passage 9, one end of which opens in the liquid level upper chamber R and the other end of which protrudes and opens upward more than the bottom section 6A of the chamber 6, a second air vent passage 10, one end of which opens at a position above the chamber 6, and the other end of which opens facing atmosphere, and a plurality of leak passages 8, one end of each of which opens in the bottom section 6A of the chamber 6 and the other ed of each of which opens in the liquid level upper chamber R. The cross section area of the chamber 6 is made larger than that of the first air vent passage 9, and the cross section area of a single leak passage 8 is made smaller than that of the first air vent passage 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor for adjusting and controlling the amount and concentration of an air-fuel mixture supplied to an engine, and more particularly to an air vent passage for communicating a liquid level chamber of the carburetor with the atmosphere.

[0002]

2. Description of the Related Art A conventional air vent passage of a carburetor is disclosed in Japanese Patent Application Laid-Open No. H11-182350. According to this, the expansion chamber is provided above the float chamber, and the main ventilation path connected to the float chamber, and the first branch ventilation path and the second branch ventilation path open to the atmosphere are opened in the expansion chamber. This prevents the first branch passage and the second branch passage from being closed at the same time even if the fuel enters the main ventilation path from the float chamber.

[0003]

According to the air vent passage of the conventional carburetor, the first branch air passage is formed to open at the bottom of the expansion chamber and protrude to the side of the carburetor body. This is because a single vaporizer has free space beside the vaporizer body. A vent tube is connected to the first branch passage, and an opening of the vent tube is opened at a position away from the vaporizer. This is because when the vent tube is not used, the opening of the first branch ventilation path is near the vaporizer, and the vaporized fuel is contaminated by the discharged fuel. According to the first branch ventilation path, which is arranged so as to protrude to the side of the carburetor body, when a plurality of carburetors are arranged on the side to form a multiple carburetor, the connecting pitch of adjacent carburetors is set. The freedom of choice is hindered. In other words, the first branch air passages of the adjacent carburetors come into contact with each other and interfere with each other, so that the adjacent pitches cannot be formed in close proximity. Further, when the fuel flowing into the first branch passage is discharged to the outside through the vent tube, the fuel economy is deteriorated and the surroundings of the carburetor are polluted, which is not preferable. Furthermore, when the pipe and the vent tube are required as the first branch passage, the number of components and the number of mounting steps are increased, and a reduction in manufacturing cost cannot be achieved.

The present invention has been made in view of the above problems, and it is a first object of the present invention to provide an air vent passage for a carburetor that can achieve an improvement in fuel economy of a carburetor and a reduction in manufacturing cost. The purpose of.

[0005]

In order to achieve the above object, the air vent passage of the vaporizer according to the present invention has a constant fuel level in the float chamber of the vaporizer and a level above the fuel level. In the air vent passage of the vaporizer in which the chamber and the atmosphere are connected by an air vent passage, an expansion chamber extending vertically is provided above the liquid level chamber, and one end of the expansion chamber is open to the liquid level chamber. And a first air vent passage having the other end projecting upward from the bottom of the enlarged chamber and opening, a second air vent passage having one end opening at the top of the enlarged chamber and the other end opening to the atmosphere, and one end enlarged. A plurality of leak passages opening at the bottom of the chamber and having the other end opening to the chamber above the liquid surface, wherein the cross-sectional area of the enlarged chamber is larger than the cross-sectional area of the first air vent passage, and a single leak passage is formed. The cross section area is That it has a smaller than the cross-sectional area of the bets passage to the first feature.

[0006] In addition to the first feature, the present invention further comprises a first air vent press-in hole, which is open to the liquid level upper chamber, and a first air vent press-in hole formed at the bottom of the enlarged chamber. A plurality of leak grooves that open toward the upper surface of the liquid surface, and a first air vent passage formed by press-fitting the pipe into the first air vent press-fitting hole; and a plurality of leak passages formed by the outer circumference of the pipe and the leak groove. The formation is a second feature.

[0007]

According to the first feature, when the vehicle on which the carburetor is mounted fluctuates greatly, the fuel in the float chamber vibrates, and the first fuel cell vibrates.
The fuel enters the air vent passage, a part of the fuel is ejected from the first air vent passage into the expansion chamber, and the other part of the fuel is discharged into the first air vent passage.
It remains in the air vent passage. The fuel ejected into the expansion chamber stays at the bottom of the expansion chamber, and the fuel is discharged again into the float chamber through a leak passage opening at the bottom. On the other hand, the first air vent passage opens above the expansion chamber, and the upper part of the expansion chamber opens to the atmosphere through the second air vent passage, so that atmospheric pressure can act on the opening of the first air vent passage to the expansion chamber. According to this, the fuel remaining in the first air vent passage is immediately discharged into the float chamber.

[0008] According to a second feature, the plurality of leak passages include an outer periphery of a pipe forming a first air vent passage,
It is formed by a plurality of leak grooves connected to a pipe press-fitting hole for press-fitting a pipe.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air vent passage of a carburetor according to the present invention will be described below with reference to FIG. Reference numeral 1 denotes a carburetor main body through which an intake passage 2 penetrates, and a float chamber 4 is formed by a lower concave portion 1A of the carburetor main body 1 and a float chamber main body 3 covering the lower concave portion 1A. A well-known constant level control mechanism is disposed in the float chamber 4, and includes a float 5, a valve seat connected to the fuel passage, and opening into the float chamber, and a float valve responsive to the float 5 to open and close the valve seat. Consisting of (The fuel passage, valve seat, and float valve are not shown.) A constant fuel level XX is formed in the float chamber 4 by the constant level control mechanism. The intake passage 2 is opened and closed by a throttle valve (not shown). Reference numeral 6 denotes an enlarged chamber recessed in the carburetor main body 1, and this enlarged chamber 6 is an upper liquid level chamber R formed above the fuel liquid level XX (specifically, a lower concave portion of the carburetor main body 1). 1A and the fuel level XX), on the side of the intake path 2 of the carburetor body 1, and the expansion chamber 6 is formed vertically. A first air vent press-in hole 7 and a plurality of leak passages 8 are formed in the bottom 6A of the enlarged chamber 6 and open toward the upper chamber R of the liquid level. A first air vent passage 9 made of a pipe P is press-fitted into the first air vent press-in hole 7, and the lower end of the first air vent passage 9 is opened to the upper liquid level chamber R, and the first air vent passage 9 is closed. The upper end protrudes and opens into the enlarged chamber 6 above the bottom 6A. The inner diameter d of the first air vent passage 9 and the height h of the first air vent passage 9 protruding from the bottom 6A are appropriately selected by a test in the case of the vibration of the engine, the fluctuation of the vehicle, and the state. The leak passage 8 has an upper end opening to the bottom 6A of the enlarged chamber 6 and a lower end opening to the upper liquid level chamber R.
Must be smaller than the inner diameter d of the first air vent passage 9. The hole diameter e and the number of the leak passages 8 are appropriately selected by a test in the same manner as described above. 1
Reference numeral 0 denotes a second air vent passage having one end opened to the upper part of the expansion chamber 6 and the other end opened to the atmosphere. Specifically, the second air vent passage is formed as a plug for closing the upper opening of the expansion chamber 6. The tube 11 is connected to the second air vent passage 10. still,
The expansion chamber 6, the first air vent passage 9, the leak passage 8,
The second air vent passage 10 including the tube 11 is similarly formed on the right side of the carburetor body 1 in FIG.

Next, the operation will be described. When the fluctuation of the vehicle on which the vaporizer is mounted is small, the fluctuation of the fuel level XX in the float chamber 4 is small.
The expansion chamber 6 is communicated with the first air vent passage 9 and the leak passage 8, and the expansion chamber 6 is communicated with the atmosphere by the second air vent passage 10 and the tube 11. And
As described above, since the fluctuation of the fuel liquid level XX is small, the fuel in the float chamber 4 does not enter the first air vent passage 9 and the leak passage 8 and is not blocked at all. R can be maintained at atmospheric pressure.

Next, when the vehicle travels on a rough road or fluctuates greatly, the fuel level XX in the float chamber 4 fluctuates greatly and fluctuates. The fuel enters the first air vent passage 9 partly, and a part of the fuel in the first air vent passage 9 is ejected from the upper end 9A of the first air vent passage 9 into the expansion chamber 6, and the other part of the fuel enters the first air vent passage 9. Remains. Here, paying attention to the upper end 9A of the first air vent passage 9, since the upper end 9A opens above the bottom 6A of the enlarged chamber 6, the fuel injected from the upper end 9A stays in the vicinity including the upper end 9A. And immediately falls toward the bottom 6A of the expansion chamber 6. On the other hand, since the second air vent passage 10 opens at the upper part of the enlarged chamber 6, it is not blocked by the fuel jetted into the enlarged chamber 6. Therefore, the inside of the expansion chamber 6 is maintained at the atmospheric pressure by the second air vent passage 10 including the tube 11, and the upper end 9A of the first air vent passage 9 opens into the expansion chamber 6 under the atmospheric pressure. According to the above,
The fuel remaining in the first air vent passage 9 is immediately discharged into the float chamber 4, so that even when the fuel level XX fluctuates greatly, the fuel level chamber R can be reliably maintained. Can be maintained at atmospheric pressure. The fuel level X-
When the fluctuation of X is large, the fuel in the float chamber 4 does not enter the leak passage 8, but the cross-sectional area (passage diameter e) of the leak passage 8 is traversed by the first air vent passage 9. It should be smaller than the area (passage diameter d). And intermittent collision of fuel with a leak toward the leak passage 8 having a small passage diameter e. , A large amount of fuel is prevented from entering the expansion chamber 6 through the leak passage 8.

On the other hand, the fuel injected from the upper end 9A of the first air vent passage 9 into the expansion chamber 6 is supplied to the expansion chamber 6 as described above.
If the fuel accumulates at the bottom 6A and the fuel is not discharged, it is expected that the fuel will gradually accumulate and eventually block the upper end 9A of the first air vent passage 9. However, in the present invention, the leak passage 8 is opened at the bottom of the enlarged chamber 6. And the upper surface of the fuel in the expansion chamber 6 accumulated on the bottom 6A faces the atmospheric pressure of the expansion chamber 6. More expanded room 6
The fuel on the bottom 6A is gradually discharged into the upper chamber R through the leak passage 8. Therefore, the bottom 6 of the expansion chamber 6
No fuel is accumulated in A, and the upper end 9A of the first air vent passage 9 is not blocked by the fuel ejected into the expansion chamber 6. What is important here is the selection of the inner diameter d of the first air vent passage 9 and the inner diameter e of the leak passage 8. Particularly, in the selection of the inner diameter e of the leak passage 8, the fuel flow caused by a large fluctuation in the liquid level is determined. The diameter is such that fuel does not easily enter the expansion chamber 6 due to intermittent undulations, and the ability to discharge fuel that accumulates on the bottom 6A of the expansion chamber 6 is taken into consideration. These are appropriately determined by tests in consideration of the vehicle fluctuation conditions.

According to the above description, even when the vehicle greatly fluctuates, the fuel that has accumulated in the first air vent passage 9 can be immediately discharged into the upper liquid level chamber R, and the larger liquid level chamber R is always enlarged. Since the air pressure can be maintained, appropriate fuel control can be performed, and the engine performance can be favorably maintained. Further, the fuel injected into the expansion chamber 6 is returned into the float chamber 4 through the leak passage 8, so that the fuel is not unnecessarily discharged to the outside, and fuel economy can be improved. Further, the fuel is not discharged to the outside and the surroundings of the vaporizer are not contaminated by the fuel. Further, since the air vent passage is not provided so as to protrude on the side of the carburetor body 1, a plurality of carburetors can be arranged close to each other. It is effective to increase the degree of freedom. Furthermore, since the leak passage 8 is formed integrally with the carburetor body 1 and does not require special pipes and tubes,
The number of parts and the number of assembling steps can be reduced, thereby reducing the manufacturing cost of the carburetor.

FIGS. 2 and 3 show another embodiment of the leak passage 8. FIG. 2 is an enlarged longitudinal sectional view of a main part showing a leak passage 8 portion. FIG. 3 is a cross-sectional view taken along line YY of FIG. Note that the same components as those in FIG. Above the liquid level chamber R,
A first air vent press-fitting hole 7 is formed, and a plurality of leak grooves V are formed continuously with the first air vent press-fitting hole 7. (The leak groove also has a bottom 6A
To the upper chamber R of the liquid surface. Then, the pipe P forming the first air vent passage 9 is press-fitted into the first air vent press-fitting hole 7. According to the above description, the upper end (corresponding to 9A) of the pipe P constituting the first air vent passage 9 is arranged so as to open above the bottom 6A, the lower end opens into the upper liquid level chamber R, and the pipe P And a plurality of leak passages 8 are formed by the outer periphery and the leak groove V. As in the first embodiment, the upper end of the leak passage 8 is the enlarged chamber 6 as in the first embodiment.
The lower end is opened in the upper liquid level chamber R, and the cross-sectional area of the single leak passage 8 is set smaller than the cross-sectional area of the first air vent passage 9.

According to this embodiment, the bottom portion 6A of the enlarged chamber 6 is ejected from the first air vent passage 9 in the same manner as the above embodiment.
The fuel that accumulates above is discharged through the plurality of leak passages 8 into the liquid level upper chamber R, but by forming the leak passage 8 by the leak groove V and the outer periphery of the pipe P, Manufacturing costs can be reduced.

The bottom 6A of the enlarged chamber 6 is formed in a conical shape projecting downward, and the first air vent press-fitting hole 7 and the leak groove V connected thereto are provided at the top of the cone. Can be reliably converged on the center of the bottom 6A, and can be discharged effectively.

[0017]

As described above, according to the air vent passage of the vaporizer according to the present invention, an expansion chamber extending in the vertical direction is provided above the chamber above the liquid surface, and one end of the expansion chamber is above the liquid surface. A first air vent passage opening to the chamber and having the other end projecting upward from the bottom of the enlarged chamber and opening; a second air vent passage opening at one end to the top of the enlarged chamber and opening to the atmosphere at the other end; A plurality of leak passages, one end of which is open to the bottom of the expansion chamber, and the other end of which is open to the upper chamber above the liquid surface. Since the cross-sectional area of the leak passage is smaller than the cross-sectional area of the first air vent passage, even when the vehicle fluctuates greatly, the chamber above the liquid surface can be reliably maintained at atmospheric pressure, and good engine performance can be maintained. . The fuel is not discharged to the outside, the fuel economy is not deteriorated, and the vicinity of the engine including the carburetor is not polluted. Also, since the air vent passage is not protrudingly arranged on the side of the carburetor body, when forming multiple carburetors, the flexibility of selecting the mounting pitch can be increased, and the number of parts and the number of assembly steps are reduced. As a result, the manufacturing cost of the vaporizer can be reduced.

Further, a first air vent press-in hole which opens toward the upper chamber above the liquid surface is provided at the bottom of the enlarged chamber, and a plurality of leaks which are connected to the first air vent press-in hole and open toward the upper chamber above the liquid surface. The first air vent passage is formed by press-fitting the pipe into the first air vent press-fitting hole, and the plurality of leak passages are formed by the outer periphery of the pipe and the leak groove. It is effective in reducing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an air vent passage of a vaporizer according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part showing another embodiment of a leak passage.

FIG. 3 is a transverse sectional view taken along line YY of FIG. 2;

[Explanation of symbols]

 Reference Signs List 6 Expansion chamber 6A bottom 7 First air vent press-in hole 8 Leak passage 9 First air vent passage 10 Second air vent passage R Above liquid level chamber V Leak groove P pipe

Claims (2)

[Claims] An air vent passage of a carburetor in which a constant fuel level is formed in a float chamber of the carburetor and the upper level of the fuel level is communicated with the atmosphere by an air vent path. An enlarged chamber 6 extending in the vertical direction is provided at a position above R. One end of the enlarged chamber 6 is opened to the upper liquid surface chamber R and the other end is opened by projecting upward from the bottom 6A of the enlarged chamber 6. First air vent passage 9
A second air vent passage 10 having one end opened to the upper part of the enlarged chamber 6 and the other end opened to the atmosphere, one end opened to the bottom 6A of the enlarged chamber 6, and the other end opened to the liquid level upper chamber R. A plurality of leak passages 8 are provided, the cross-sectional area of the enlarged chamber 6 is larger than the cross-sectional area of the first air vent passage 9, and the cross-sectional area of a single leak passage 8 is smaller than the cross-sectional area of the first air vent passage 9. An air vent passage for a carburetor. 2. A first air vent press-fitting hole 7 that opens toward the upper liquid level chamber R at the bottom 6A of the enlarged chamber, and is connected to the first air vent press-fitting hole 7 and faces the upper liquid level chamber R. The first air vent passage 9 is formed by press-fitting the pipe P into the first air vent press-fit hole 7 and the plurality of leak passages 8 are formed by the outer periphery of the pipe P and the leak groove V. 2. An air vent passage for a carburetor according to claim 1, wherein: