JP4055308B2 - Ventilator air vent passage - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a carburetor that adjusts and controls the amount and concentration of an air-fuel mixture supplied to an engine, and more particularly, to an air vent passage that communicates an upper liquid level chamber of the carburetor and the atmosphere.
[0002]
[Prior art]
An air vent passage of a conventional carburetor is disclosed in Japanese Patent Laid-Open No. 11-182350. According to this, an expansion chamber is provided above the float chamber, and a main vent passage connected to the float chamber, a first branch vent passage that opens to the atmosphere, and a second branch vent passage are opened in the expansion chamber. This prevents the first branch passage and the second branch passage from being blocked at the same time even if fuel enters the main ventilation passage from the float chamber.
[0003]
[Problems to be solved by the invention]
According to the conventional air vent passage of the carburetor, the first branch air passage is formed at the bottom of the expansion chamber and protruding to the side of the carburetor body. This is because a single vaporizer has a free space on the side of 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 air passage is in the vicinity of the vaporizer, and the vaporizer is contaminated by the discharged fuel. According to the first branch air passage projecting from the side of the carburetor body, when a plurality of carburetors are arranged on the side to form a multiple carburetor, the continuous pitch of adjacent carburetors The freedom of choice is hindered. That is, each 1st branch ventilation path of an adjacent vaporizer contact | abuts and interferes, and it cannot be set as the adjacent installation pitch. Further, if the fuel that has flowed 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 still contaminated, which is not preferable. Furthermore, if a pipe and a vent tube are required as the first branch passage, the number of parts and the number of mounting steps increase, and a reduction in manufacturing cost cannot be achieved.
[0004]
The present invention has been made in view of the above problems, and has as its first object to provide an air vent passage of a carburetor that can achieve improvement in fuel economy of the carburetor and reduction in manufacturing cost. To do.
[0005]
[Means for solving the problems]
In order to achieve the above object, the air vent passage of the carburetor according to the present invention forms a constant fuel liquid level in the float chamber of the carburetor and connects the upper liquid level chamber of the fuel liquid level to the atmosphere by the air vent passage. In the air vent passage of the carburetor, an expansion chamber extending in the vertical direction is provided at a position above the liquid level upper chamber. One end of the expansion chamber opens into the liquid level upper chamber and the other end is the bottom of the expansion chamber. A first air vent passage projecting upward and opening, a second air vent passage having one end opened at the top of the enlarged chamber and the other end opened to the atmosphere, and one end opened at the bottom of the enlarged chamber, the other end Provided with a plurality of leak passages opened in the upper liquid level chamber, the cross-sectional area of the expansion chamber is made larger than the cross-sectional area of the first air vent passage, and the cross-sectional area of the single leak passage is crossed by the first air vent passage Smaller than area The first, characterized in that the.
[0006]
According to the present invention, in addition to the first feature, a first air vent press-fitting hole that opens toward the liquid level upper chamber and a first air vent press-fitting hole are provided at the bottom of the expansion chamber. A plurality of leak grooves opened toward the chamber are formed, and a first air vent passage is formed by press fitting the pipe into the first air vent press-fitting hole, and a plurality of leak passages are formed by the outer periphery of the pipe and the leak groove. Is the second feature.
[0007]
[Action]
According to the first feature, when the vehicle or the like on which the carburetor is mounted fluctuates greatly, the fuel in the float chamber vibrates and enters the first air vent passage, and a part of this fuel passes from the first air vent passage to the enlarged chamber. The other part of the fuel remains in the first air vent passage. The fuel ejected into the expansion chamber stays at the bottom of the expansion chamber, and this fuel is discharged again into the float chamber through a leak passage that opens at the bottom. On the other hand, the first air vent passage opens above the expansion chamber, and the upper portion of the expansion chamber opens to the atmosphere via 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 the second feature, the plurality of leak passages are formed by the outer periphery of the pipe forming the first air vent passage and the plurality of leak grooves connected to the pipe press-fitting hole for press-fitting the pipe. .
[0009]
【Example】
Hereinafter, an embodiment of an air vent passage of a vaporizer according to the present invention will be described with reference to FIG. Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes, and a float chamber 4 is formed by a lower recess 1A of the carburetor main body 1 and a floating chamber main body 3 covering the lower recess 1A. A known constant liquid level control mechanism is arranged in the float chamber 4, which is a float 5, a valve seat that is connected to the fuel passage and opens into the float chamber, and a float valve that is opened and closed by the float 5. It becomes more. (The fuel passage, the valve seat, and the float valve are not shown.) In the float chamber 4, a constant fuel level XX is formed 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 expansion chamber that is recessed in the vaporizer main body 1, and this expansion chamber 6 is an upper liquid level chamber R (specifically, a lower concave portion of the vaporizer main body 1) formed above the fuel liquid level XX. 1 </ b> A and the fuel liquid level XX), on the side of the intake passage 2 of the carburetor body 1, and the expansion chamber 6 is formed in the vertical direction. A first air vent press-fitting hole 7 and a plurality of leak passages 8 that open toward the liquid level upper chamber R are formed in the bottom portion 6 </ b> A of the expansion chamber 6. A first air vent passage 9 made of a pipe P is press-fitted into the first air vent press-fitting hole 7, and the lower end of the first air vent passage 9 opens into the liquid surface upper chamber R, and the first air vent passage 9 The upper end protrudes and opens into the expansion chamber 6 located above the bottom 6A. The inner diameter d of the first air vent passage 9 and the protrusion height h from the bottom 6A are appropriately selected by a test in the vibration of the engine, the fluctuation of the vehicle, and the state. The leak passage 8 has an upper end opened to the bottom portion 6A of the expansion chamber 6 and a lower end opened to the liquid surface upper chamber R. The hole diameter e of the single leak passage 8 is equal to that of the first air vent passage 9. It must be smaller than the inner diameter d. Incidentally, the hole diameter e and the number of the leak passages 8 are appropriately selected by a test as described above. Reference numeral 10 denotes a second air vent passage having one end opened to the upper portion of the expansion chamber 6 and the other end opened to the atmosphere. Specifically, the second air vent passage 10 is formed as a plug for closing the upper opening of the expansion chamber 6. A tube 11 is connected to the second air vent passage 10. The second air vent passage 10 including the expansion chamber 6, the first air vent passage 9, the leak passage 8, and the tube 11 is formed in the same manner on the right side of the vaporizer body 1 in FIG.
[0010]
Next, the operation will be described. When the variation of the vehicle on which the carburetor is mounted is small, the variation of the fuel liquid level XX in the float chamber 4 is small. On the other hand, the liquid upper chamber R and the expansion chamber 6 are the first air vent passage 9. The expansion chamber 6 and the atmosphere are connected by the second air vent passage 10 and the tube 11. 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. The upper chamber R can be maintained at atmospheric pressure.
[0011]
Next, when the vehicle travels on a rough road and fluctuates greatly, the fuel level XX in the float chamber 4 fluctuates greatly, and according to this, the fuel level XX moves into the first air vent passage 9. The fuel enters well, 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 remains in the first air vent passage 9. 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 expansion chamber 6, the fuel jetted 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, the second air vent passage 10 is opened at the upper part of the expansion chamber 6, so that it is not blocked by the fuel jetted into the expansion chamber 6. Therefore, the inside of the expansion chamber 6 is maintained at an atmospheric pressure state 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 in the atmospheric pressure state. 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 if the fluctuation of the fuel liquid level XX is large, The chamber R can be reliably maintained at atmospheric pressure. Note that when the fuel level XX fluctuates greatly, the fuel in the float chamber 4 does not enter the leak passage 8 as well, but the cross-sectional area of the leak passage 8 (passage diameter e) Is made smaller than the cross-sectional area (passage diameter d) of the first air vent passage 9. In addition, the fuel that is intermittently collided toward the leak passage 8 having a small passage diameter e. Therefore, a large amount of fuel is prevented from entering the expansion chamber 6 through the leak passage 8.
[0012]
On the other hand, the fuel jetted into the expansion chamber 6 from the upper end 9A of the first air vent passage 9 stagnates in the bottom 6A of the expansion chamber 6 as described above. If this fuel is not discharged, the fuel is gradually accumulated. Anyway, it is predicted that the upper end 9A of the first air vent passage 9 will be closed. However, in the present invention, the leak passage 8 is opened at the bottom of the expansion chamber 6. And the upper surface of the fuel in the expansion chamber 6 stagnated on the bottom 6A faces the atmospheric pressure in the expansion chamber 6. Further, the fuel on the bottom 6A of the expansion chamber 6 is gradually discharged into the liquid level upper chamber R through the leak passage 8. Accordingly, no fuel is accumulated at the bottom 6A of the expansion chamber 6, and the upper end 9A of the first air vent passage 9 is not blocked by the fuel jetted 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, and particularly in the selection of the inner diameter e of the leak passage 8, The diameter of the fuel that is difficult for the fuel to enter the expansion chamber 6 due to intermittent undulations, and the discharge property of the fuel stagnating on the bottom 6A of the expansion chamber 6 is taken into consideration. These are determined by a test as appropriate in consideration of vehicle variation conditions.
[0013]
According to the above, even when the vehicle greatly fluctuates, the fuel stagnating in the first air vent passage 9 can be immediately discharged into the liquid level chamber R, and the liquid level chamber R is always in the atmospheric pressure state. Since it can be maintained, proper fuel control can be performed, and the engine performance can be maintained well. Further, the fuel jetted into the expansion chamber 6 is returned to the float chamber 4 through the leak passage 8, so that the fuel is not unnecessarily discharged to the outside, and the 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. In addition, it is no longer necessary to project the air vent passage on the side of the carburetor main body 1, which makes it possible to place a plurality of carburetors close to each other and select the continuous pitch of multiple carburetors. It is effective to increase the degree of freedom. Furthermore, the leak passage 8 is formed integrally with the carburetor body 1 and does not require any special pipes or tubes, so that the number of parts and assembly man-hours can be reduced, thereby reducing the manufacturing cost of the carburetor. It is.
[0014]
2 and 3 show another embodiment of the leak passage 8. FIG. 2 is an enlarged vertical sectional view of a main part showing a leak passage 8 portion. 3 is a cross-sectional view taken along line YY of FIG. In addition, about the same structure as FIG. 1, the description is abbreviate | omitted using the same code | symbol. A first air vent press-fitting hole 7 that opens toward the liquid level upper chamber R is formed in the bottom portion 6A of the expansion chamber 6, and a plurality of leak grooves V are further provided continuously to the first air vent press-fitting hole 7. Is done. (The leak groove also opens from the bottom portion 6A toward the liquid level upper chamber R.) 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, the upper end (corresponding to 9A) of the pipe P forming the first air vent passage 9 is disposed to open above the bottom 6A, the lower end is opened into the liquid level chamber R, and the pipe P A plurality of leak passages 8 are formed by the outer periphery of each and the leak groove V. Similarly to the first embodiment, the leak passage 8 also has an upper end that opens to the bottom 6A of the expansion chamber 6, a lower end that opens into the liquid level chamber R, and the cross-sectional area of the single leak passage 8 is the first. 1 It is set smaller than the cross-sectional area of the air vent passage 9.
[0015]
According to the present embodiment, the fuel that is ejected from the first air vent passage 9 and stagnates on the bottom portion 6A of the expansion chamber 6 in the liquid upper chamber R via the plurality of leak passages 8 is the same as in the previous embodiment. Although the leak passage 8 is formed by the leak groove V and the outer periphery of the pipe P, the manufacturing cost can be reduced.
[0016]
Further, the bottom 6A of the expansion chamber 6 has a conical shape protruding 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. The fuel to be discharged can be reliably converged on the center of the bottom 6A, and can be effectively discharged.
[0017]
【The invention's effect】
As described above, according to the air vent passage of the carburetor according to the present invention, an expansion chamber extending in the vertical direction is provided above the liquid level chamber, and one end of the expansion chamber opens into the liquid level chamber. A first air vent passage having the other end projecting upward from the bottom of the expansion chamber and opening, a second air vent passage having one end opening at the top of the expansion chamber and the other end opening to the atmosphere, and one end of the expansion chamber A plurality of leak passages opened at the bottom and having the other end opened into the upper liquid level chamber, and the cross-sectional area of the expansion chamber is made larger than the cross-sectional area of the first air vent passage and the cross-sectional area of the single leak passage Is smaller than the cross-sectional area of the first air vent passage, so that even when the vehicle fluctuates greatly, the upper chamber of the liquid level 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. In addition, since the air vent passage does not protrude from the side of the carburetor body, it is possible to increase the degree of freedom in selecting the continuous pitch when forming multiple carburetors and reduce the number of parts and assembly man-hours. This can reduce the manufacturing cost of the vaporizer.
[0018]
In addition, a first air vent press-fitting hole that opens toward the liquid level upper chamber and a plurality of leak grooves that are connected to the first air vent press-fitting hole and open toward the liquid level upper chamber are formed at the bottom of the expansion chamber. And forming a first air vent passage by press-fitting the pipe into the first air vent press-fitting hole and forming a plurality of leak passages by the outer periphery of the pipe and the leak groove, the leak passage can be easily formed, It is effective in reducing manufacturing costs.
[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 an essential part showing another embodiment of a leak passage.
3 is a cross-sectional view taken along line YY in FIG.
[Explanation of symbols]
6 Expansion chamber 6A Bottom portion 7 First air vent press-fit hole 8 Leak passage 9 First air vent passage 10 Second air vent passage R Liquid level upper chamber V Leak groove P Pipe

Claims (2)

In the air vent passage of the carburetor where a constant fuel liquid level is formed in the float chamber of the carburetor and the upper liquid level chamber of the fuel liquid level and the atmosphere are communicated with each other by the air vent passage, the position is higher than the upper liquid level chamber R. A first air vent passage having one end opened to the upper liquid level chamber R and the other end projecting upward from the bottom 6A of the enlargement chamber 6. 9, one end opened to the top of the expansion chamber 6, the other end opened to the atmosphere, one end opened to the bottom 6 A of the expansion chamber 6, and the other end opened to the liquid level upper chamber R A plurality of leak passages 8, the cross-sectional area of the expansion chamber 6 is larger than the cross-sectional area of the first air vent passage 9, and the cross-sectional area of the single leak passage 8 is larger than the cross-sectional area of the first air vent passage 9. Characterized by being small Air vent passage of the equalizer. A first air vent press-fitting hole 7 that opens toward the liquid level upper chamber R and a plurality of air vents that open toward the liquid level upper chamber R and that are continuous with the first air vent press-fitting hole 7 at the bottom 6A of the expansion chamber. A leak groove V is provided, and the pipe P is press-fitted into the first air vent press-fitting hole 7 to form a first air vent passage 9 and a plurality of leak passages 8 are formed by the outer periphery of the pipe P and the leak groove V. The air vent passage of the carburetor according to claim 1.

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