JP2006125203A - Through-air cutting device for carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a through-air cutting device for a carburetor improving mountability on an engine by preventing a carburetor body from significantly projecting to one side and facilitating passage design of a first through-air passage and a second through-air passage. <P>SOLUTION: The first through-air passage 1 provided with a first through-air jet 19 and a vacuum operation type shut off valve V is arranged on one side A of an intake passage 11 and is communicated to a low speed fuel nozzle 15. The second through-air passage 2 provided with a second through-air jet 27 is arranged on another side B of the intake air passage 11 and is communicated to the low speed fuel nozzle 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a carburetor that adjusts and controls the concentration and amount of air-fuel mixture supplied to an engine, and particularly relates to a low-speed fuel system controlled by a slow air jet and a slow fuel nozzle.

A conventional slow air cut device for a vaporizer is shown in FIGS.
FIG. 3 is a cross-sectional view of a carburetor having a low-speed fuel system.
4 is a longitudinal sectional view taken along line EE of FIG. It is.
Reference numeral 10 denotes a carburetor body having an intake passage 11 penetrating through the side thereof. The intake passage 11 is opened and closed by a throttle valve (not shown) operated by a driver.
The downstream side of the intake passage 11 is connected to an engine (not shown), and the upstream side of the intake passage is connected to an air cleaner (not shown).
A float chamber body 12 is disposed below the vaporizer body 10, and a float chamber 13 is formed by the vaporizer body 10 and the float chamber body 12, and a float 14, A constant fuel liquid level XX is formed by the cooperative action of a valve seat connected to the fuel passage and a float valve (both not shown) for opening and closing the valve seat.
The low speed fuel system S is formed by the following.
Reference numeral 15 denotes a low-speed fuel nozzle. A male screw 15a is formed on the outer periphery of the intermediate portion, and a small-diameter cylindrical portion 15b is continuously provided upward from the tip of the male screw 15a.
In addition, a through hole 15e is formed in the low speed fuel nozzle 15 from the front end 15c to the rear end 15d, and a metering jet portion 15f is formed at an intermediate portion of the through hole 15e. A plurality of bleed holes 15g are formed in the portion 15b.
The male screw 15a of the low-speed fuel nozzle 15 is screwed to a low-speed fuel boss 10a protruding from the intake passage 11 into the float chamber 13, and the low-speed mixture chamber 16 faces the tip 15c of the low-speed fuel nozzle 15. The annular well 17 is formed on the outer periphery of the small diameter cylindrical portion 15b of the low speed fuel nozzle 15.
Reference numeral 18 denotes a first slow air passage. A first slow air jet 19 is disposed upstream of the first slow air passage, and a negative pressure operated shut-off valve V is disposed downstream of the first slow air jet 19.
(Note that upstream and downstream are in the direction of air flow)
The negative pressure actuated shut-off valve V is divided into an atmospheric pressure 21 and a pressure receiving chamber 22 by a diaphragm 20, and a spring 23 that presses the diaphragm 20 toward the atmospheric pressure 21 is contracted in the pressure receiving chamber 22 and a throttle (not shown). A negative pressure introduction passage 24 connected to the intake passage on the downstream side of the valve opens. (The downstream side of the throttle valve means the engine side of the throttle valve.)
Further, the diaphragm 20 is integrally attached with a valve body 25 for opening and closing the first slow air passage 18, and the throttle valve is rapidly closed from a state where the throttle valve is opened at a high opening degree. During the rapid deceleration operation of the engine, the negative pressure in the intake passage downstream of the throttle valve that has risen greatly is introduced into the pressure receiving chamber 22 through the negative pressure introduction passage 24, whereby the diaphragm 20 has the spring force of the spring 21. The first slow air passage 18 is closed by the valve body 25 that moves to the pressure receiving chamber 22 side and moves upward in FIG.
On the other hand, when the engine is not decelerating rapidly, the diaphragm 20 is pressed by the spring 23 toward the atmosphere chamber 21, and the valve body 25 is in the lower position as shown in FIG. The first slow air passage 18 is held open. That is, the negative pressure actuated shut-off valve V is a normally open type.
Reference numeral 26 denotes a second slow air passage, and a second slow air jet 27 is disposed upstream thereof.
The first slow air passage 18 provided with the first slow air jet 19, the negative pressure actuated cutoff valve V, and the second slow air passage 26 provided with the second slow air jet 27 are the longitudinal axis Y of the intake passage 11. -Y is formed on one side A (hereinafter simply referred to as one side A of the intake passage 11).
Reference numeral 28 denotes a merging throw air passage formed from one side portion of the carburetor body 10 on one side A of the intake passage 11 toward the well 17, and an opening on the outer side is closed by a plug 29.
The downstream side of the first slow air passage 18 is connected to the merging throw air passage, and the downstream side of the second slow air passage 26 is also connected to the merging throw air passage 28.

In the low-speed fuel system constructed as described above, the diaphragm 20 of the negative pressure actuated shut-off valve V is pressed and held to the atmosphere chamber 21 side by the spring 23, and the valve body 25 is connected to the first slow air passage 18 as shown in FIG. Hold open.
Therefore, the first slow air controlled by the first slow air jet 19 is supplied to the merging throw air passage 28 via the first slow air passage 18, and the second slow air controlled by the second slow air jet 27 is the second slow air passage. 26 to the merging slow air passage 28 via
According to the above, the first slow air and the second slow air are merged and increased in the merged slow air passage 28, and the increased slow air is supplied into the well 17.
On the other hand, the low speed fuel nozzle 15 controls the fuel in the float chamber 13 by the metering jet portion 15f to form a slow fuel, and this slow fuel flows toward the tip 15c of the low speed fuel nozzle 15. The slow fuel flowing through the nozzle 15 is mixed with the slow air supplied from the well 17 through the bleed hole 15g to form a slow mixture.
The slow mixture is sucked into the low-speed mixture chamber 16, and the low-speed mixture is sucked into the intake passage 11 through the pilot outlet hole 30. Thus, the idling operation of the engine, the throttle valve low, medium Opening operation is performed.
Reference numeral 31 denotes a main fuel nozzle as a main fuel system for supplying the main air-fuel mixture during high opening operation in the throttle valve.

Next, a description will be given of a sudden deceleration operation of an engine that is suddenly closed from a state where the throttle valve is opened at a medium and high opening degree. In the intake passage on the downstream side of the throttle valve, compared with the above operation state. A considerably large negative pressure is generated, and this negative pressure is introduced into the pressure receiving chamber 22 of the negative pressure actuated shut-off valve V through the negative pressure introduction passage 24.
According to the above, the diaphragm 20 largely moves toward the pressure receiving chamber 22 against the spring force of the spring 23, and the valve body 25 that moves upward in synchronism with this closes and holds the first slow air passage 18. .
As described above, when the first slow air passage 18 is closed by the valve body 25, the supply of the first slow air from the first slow air passage 18 toward the merging throw air passage 28 is shut off. 17. The amount of the slow air supplied to the low speed fuel nozzle 15 through the bleed hole 15g can be reduced corresponding to the amount of the first slow air, so that the concentration of the slow air-fuel mixture can be increased.
Thus, it is possible to suppress the dilution of the slow mixture during the rapid deceleration operation of the engine, and it is possible to perform the rapid deceleration operation of the engine.

According to the conventional slow air cut device for a carburetor having a negative pressure operated shut-off valve, the first slow air passage having the first slow air jet and the negative pressure actuated shut-off valve, and the second slow air jet are provided. The second slow air passage is disposed on one side of the longitudinal axis of the intake passage.
According to this, since the two slow air passages are arranged on the same side of the carburetor main body, the carburetor main body largely protrudes only on one side, and the mountability to the engine is inferior.
Further, in order to solve the above-mentioned problem, it is considered that two slow air passages are arranged close to each other. According to this, however, two slow air passages are drilled in a vaporizer body formed by injection molding. When doing so, there is a risk that both passages may communicate with each other due to nest leakage.
In addition, the first slow air passage and the second slow air passage are not overlapped with each other and are formed at different positions, and the first and second slow air passages are located at different positions with respect to the single merged throw air passage. It is extremely difficult to design a passage that communicates the downstream side of the two slow air passages, requiring a lot of development man-hours.

  The slow air cut device for a carburetor according to the present invention has been made in view of the above-described problems. The carburetor main body is largely prevented from projecting to one side, thereby improving the mountability to the engine and the first slow air passage. It is an object of the present invention to facilitate the passage design of the second slow air passage and to control the slow air stably without causing both passages to communicate with each other when the first and second slow air passages are processed.

A carburetor slow-air cut device according to the present invention is a low-speed fuel system that supplies a low-speed mixture toward an intake passage that penetrates the carburetor body in order to achieve the above-described object,
A first slow air passage comprising a first slow air jet and a normally open negative pressure operated shut-off valve that shuts off the first slow air passage during deceleration operation of the engine is communicated toward the low speed fuel nozzle and the second A second slow air passage with a slow air jet is communicated towards the low speed fuel nozzle,
A first slow air passage comprising the first slow air jet and a negative pressure actuated shut-off valve is disposed on one side of the longitudinal axis of the intake passage;
The second slow air passage including the second slow air jet is arranged on the other side of the intake air 11.

During low, medium, high opening operation and acceleration operation of the throttle valve, the negative pressure operated shut-off valve keeps the first slow air passage open, and the first slow air controlled by the first slow air jet is the first. A second slow air supplied to the low speed fuel nozzle through the slow air passage and controlled by the second slow air jet is supplied to the low speed fuel nozzle through the second slow air passage.
On the other hand, when the engine is rapidly decelerating, the negative pressure operated shut-off valve keeps the first slow air passage closed, and the supply of the first slow air from the first slow air passage toward the low speed fuel nozzle is stopped, while the second The second slow air controlled by the slow air jet is supplied toward the low speed fuel nozzle via the second slow air passage.
According to the slow air cut device of the present invention, the first slow air passage is disposed on one side of the intake passage, and the second slow air passage is disposed on the other side of the intake passage, so that the carburetor main body largely protrudes toward one side. Therefore, it is possible to improve the mountability to the engine.
In addition, since the first slow air passage and the second slow air passage are independently drilled toward the low speed fuel nozzle, the passage design of the passage can be freely performed regardless of the position of the other slow air passages. And the passage design can be simplified.
In addition, since the first slow air passage and the second slow air passage are disposed across the intake passage and a sufficient distance between the two passages can be secured, the carburetor main body can be used when drilling the slow air passage. Both passages do not communicate with each other through the nest.

Hereinafter, an embodiment of a slow-air cutting device for a vaporizer according to the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view of a carburetor having a low-speed fuel system.
FIG. 2 is a longitudinal sectional view taken along line DD of FIG.
3 and 4 are denoted by the same reference numerals, and description thereof is omitted.
The first slow air passage 1 is formed on one side A of the longitudinal axis YY of the intake passage 11.
The upstream side of the first slow air passage 1 is arranged to open to the upstream side of the intake passage 11 with the first slow air jet 19, and the downstream side is arranged to open to the well 17.
Further, a negative pressure actuated shut-off valve V similar to the conventional one is disposed downstream of the first slow air jet 19, and the first slow air passage 1 is opened and closed by a valve body 25 of the negative pressure actuated shut-off valve V. Be controlled.
The second slow air passage 2 is formed on the other side B of the longitudinal axis YY of the intake passage 11.
The upstream side of the second slow air passage 2 is arranged to open to the upstream side of the intake passage 11 with the second slow air jet 27 and the downstream side is arranged to open to the well 17.

According to the carburetor having the low-speed fuel system, the valve body 25 of the negative pressure operated shut-off valve V opens the first slow air passage 1 when the throttle valve is operating at low, medium, high opening and acceleration. The first slow air held and controlled by the first slow air jet 19 is supplied into the well 17 through the first slow air passage 1.
The second slow air controlled by the second slow air jet 27 is supplied into the well 17 via the second slow air passage 2.
On the other hand, during the rapid deceleration operation of the engine, the valve body 25 of the negative pressure operation type shut-off valve V closes the first slow air passage 1, and the second slow air controlled by the second slow air jet 27 is the second. It is supplied into the well 17 through the slow air passage 2.
Thus, the engine can be operated in the same manner as before.

Here, according to the present invention, the first slow air passage 19 including the first slow air jet 19 and the negative pressure actuated shut-off valve V is disposed on one side A of the longitudinal axis YY of the intake passage 11, and the second Since the second slow air passage 2 including the slow air jet 27 is disposed on the other side B of the longitudinal axis YY of the intake passage 11, either one side of the carburetor main body 10 protrudes greatly outward. It will not be done.
According to the above, the degree of freedom of mounting on the engine can be improved, and this is particularly effective when the carburetor is arranged in a narrow storage space below the fuel tank like a two-wheeled vehicle.
Further, since the outside of the carburetor main body 10 can be prevented from protruding outward greatly, when the occupant straddles the two-wheeled vehicle, there is no interference with the foot, which is preferable in terms of the carburetor layout.
Further, when the first and second slow air passages 1 and 2 are formed in the carburetor body 10 by drilling, the slow air passages 1 and 2 are not communicated with each other by the cast hole existing in the carburetor main body 10. .
Further, since the first slow air passage 1 and the second slow air passage 2 are independently drilled toward the well 17 without crossing each other, the degree of freedom in designing the passages can be improved.
Further, since the first and second slow air passages 1 and 2 are opened in the well 17, the slow air is supplied uniformly to the bleed hole 15g particularly during low, medium, high and acceleration operations of the throttle valve. Therefore, the mixing property between the slow air supplied from the bleed hole 16g and the low speed fuel flowing in the low speed fuel nozzle 15 can be improved.

The cross-sectional view which shows one Example of the slow-air cut apparatus of the vaporizer | carburetor which becomes this invention. The longitudinal cross-sectional view in the DD line of FIG. The cross-sectional view which shows the slow cut apparatus of the conventional vaporizer | carburetor. The longitudinal cross-sectional view in the EE line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st slow air passage 2 2nd slow air passage 4 Negative pressure operation type shut-off valve 11 Intake passage 15 Low speed fuel nozzle 19 1st slow air jet 27 2nd slow air jet

Claims (1)

A low-speed fuel system that supplies a low-speed air-fuel mixture toward an intake passage that penetrates the carburetor body, and is a normally open type that shuts off the first slow-air jet 19 and the first slow-air passage 1 during deceleration operation of the engine. A first slow air passage 1 having a negative pressure actuated shut-off valve V is communicated to the low speed fuel nozzle 15 and a second slow air passage 2 having a second slow air jet 27 is communicated to the low speed fuel nozzle 15. ,
The first slow air passage 1 including the first slow air jet 19 and the negative pressure actuated shut-off valve V is disposed on one side A of the longitudinal axis YY of the intake passage 11,
A slow air cut device for a carburetor, wherein the second slow air passage 2 including the second slow air jet 27 is disposed on the other side B of the intake passage 11.

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