JP4464788B2 - Vaporizer low speed fuel system - Google Patents

Description

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

A conventional low speed fuel system for a carburetor 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 .
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 on the upstream side of the first slow air passage, and a negative pressure actuated 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 chamber 21 and a pressure receiving chamber 22 by a diaphragm 20, and a spring 23 that presses the diaphragm 20 toward the atmospheric chamber 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 on the downstream side of the throttle valve that has risen greatly is introduced into the pressure receiving chamber 22 through the negative pressure introduction passage 24, and thereby the diaphragm 20 has the spring force of the spring 23 . 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 Suroeya passages are disposed on the same side of the carburetor body, the carburetor body is to protrude significantly only to the one side toward, poor mountability to the engine.
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 carburetor slow-air cut device according to the present invention has been made in view of the above-mentioned 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 during the processing of the first and second slow air passages.

In order to achieve the above object, the present invention communicates a pilot outlet hole that opens to an intake passage of a carburetor body, an upper end portion that forms a bleed hole in the pilot outlet hole, and a lower end portion that is located in the float chamber. A low-speed fuel nozzle immersed under the liquid level of the fuel, an annular well surrounding the upper end portion where the bleed hole is formed, and a first slow air passage communicating with the well via a first slow jet upstream of the intake passage And a second slow air passage communicating with the well via a second slow jet on the upstream side of the intake passage, and the first slow air passage normally shuts off the first slow air passage when the engine is decelerating. A low-speed fuel system for a carburetor provided with an open-type negative pressure operation type shut-off valve and supplying a low-speed air-fuel mixture to the intake passage from the pilot outlet hole The first slow air passage extending along the intake passage on one side wall of the carburetor body, and on the other side wall on the opposite side of the one side wall of the carburetor body along the intake passage. The extending second slow air passages are respectively formed, and the downstream ends of the first and second slow air passages are individually opened in the wells .

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 present invention, the first slow air passage extending along the intake passage is formed on one side wall of the carburetor main body, and the other side wall on the opposite side of the one side wall of the carburetor body with the intake passage interposed therebetween. The second slow air passages extending along the passages are respectively formed, and the downstream ends of the first and second slow air passages are individually opened in the wells, so that the carburetor main body largely protrudes only to 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 Suroeya passage and second Suroeya passage are arranged across the intake passage, Ki out taking a sufficient distance between the two passages, thus during drilling of the Suroeya passage carburetor Both passages do not communicate with each other due to the nest of the main body.
Further, the first and second slow air passages are individually opened in the well, so that the slow air can be supplied uniformly to the bleed holes, especially during low, medium, high and acceleration operations of the throttle valve. It is possible to improve the mixing property between the slow air supplied from the bleed hole and the low speed fuel flowing in the low speed fuel nozzle.

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 wall of the carburetor body 10 on one side A side of the longitudinal axis YY of the intake passage 11.
The upstream end 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 end 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 wall of the carburetor body 10 on the other side B side of the longitudinal axis YY of the intake passage 11. Thus, the first and second slow air passages 1 and 2 are formed along the intake passage 11 on the one side wall and the other side wall of the carburetor body 10 facing each other with the intake passage 11 in between.
The upstream end 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 end is arranged to open to the well 17. Thus , the downstream ends of the first and second slow air passages 1 and 2 are individually opened in the well 17.

According to a vaporizer comprising a pre SL low speed fuel system, low throttle valve, inside, at the time of and during acceleration operation high opening operation, the valve body 25 of the negative pressure-actuated shut-off valve V is the first Suroeya passage 1 The first slow air that is held open 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 provided with the first slow air jet 19 and the negative pressure actuated shut-off valve V is connected to the carburetor on one side A side of the longitudinal axis YY of the intake passage 11 . The second slow air passage 2 formed on one side wall of the main body 10 and having the second slow air jet 27 is formed on the other side wall of the carburetor main body 10 on the other side B side of the longitudinal axis YY of the intake passage 11. Since it formed, only any one side wall of the vaporizer main body 10 does not protrude greatly toward the outside.
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 of the slow air supplied from the bleed hole 15g 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.

1 1st slow air passage 2 2nd slow air passage
V negative pressure operated shut-off valve
10 Vaporizer body 11 Intake passage
13 Float chamber 15 Low speed fuel nozzle
17 Well 19 1st slow air jet 27 2nd slow air jet
30 Pilot outlet hole
XX Fuel level

Claims (1)

A pilot outlet hole (30) that opens to the intake passage (11) of the carburetor body (10) and an upper end portion in which a bleed hole (15g) is formed communicate with the pilot outlet hole (30), and a lower end portion is connected to the pilot outlet hole (30). A low speed fuel nozzle (15) immersed under the fuel level in the float chamber (13), an annular well (17) surrounding the upper end portion where the bleed hole (15g) is formed, and an intake passage (11) A first slow air passage (1) communicating with the well (17) via a first slow jet (19) on the upstream side, and a second slow jet (27) on the upstream side of the intake passage (11) And a second slow air passage (2) communicating with the well (17). The first slow air passage (1) has a normally open negative passage that shuts off the first slow air passage (1) when the engine is decelerating. Pressure Doshiki shutoff valve (V) is provided, and to supply a low-speed fuel mixture in the intake passage (11) from the pilot outlet holes (30), in the slow fuel system of the carburetor,
  The first slow air passage (1) extending along the intake passage (11) is formed on one side wall of the carburetor body (10), and the one side wall is sandwiched between the intake passage (11) of the carburetor body (10). The second slow air passage (2) extending along the intake passage (11) is formed on the other side wall opposite to the first side, and the downstream ends of the first and second slow air passages (1, 2) are connected to the well ( 17) A low-speed fuel system for a carburetor, characterized by being individually opened.

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