JP3546571B2 - Power fuel control system for carburetor - Google Patents

Description

[0001]
[Industrial applications]
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 particularly to a carburetor that is supplied from a main fuel system when an opening of a throttle valve is a certain opening or more. The present invention relates to a power fuel control device for a carburetor that supplies power fuel to fuel.
[0002]
[Prior art]
A conventional power fuel control device for a carburetor is shown in FIG.
Reference numeral 1 denotes a carburetor body through which an intake passage 2 penetrates. A floater chamber body 3 is disposed below the carburetor body 1, and a floater chamber 4 is formed by the carburetor body 1 and the floater chamber body 3. Is done.
The intake path 2 is opened and closed by a throttle valve 5 controlled by a driver. The intake path 2 is connected to an upstream intake path 2A connected to an air cleaner (not shown in the drawing at the right side) by the throttle valve 5. , And is divided into a downstream intake passage 2 </ b> B connected to an engine (left side in the figure, not shown).
A constant fuel level XX is formed and held in the float chamber 4 by the cooperative action of the float 6, a valve seat (not shown) and the float valve.
M is a main fuel system, which is constituted by a needle jet 7, a mixing tube 8, and a main fuel jet 9. The needle jet 7 opens into the intake passage 2, and the main fuel jet 9 is a constant fuel in the floating chamber 4. The jet needle 10 immersed below the liquid level and attached to the throttle valve 5 is inserted into the needle jet 7.
Main fuel supplied from the main fuel system M into the intake passage 2 is controlled by an annular gap formed by the jet needle 10 and the needle jet 7.
[0003]
The power fuel control device P includes the following.
Reference numeral 12 denotes a power fuel passage which is provided at a downstream end thereof with a power nozzle 13 which opens into the intake passage 2A upstream of the throttle valve, and whose upstream end opens below the constant fuel level in the float chamber 4. In the power fuel passage 12 on the more upstream side, a power fuel control jet 14 and a normally open solenoid valve NO are arranged in series.
[0004]
When the throttle valve 5 opens the intake passage 2 to a certain opening (for example, １ ／ opening) or more, the increased negative pressure in the intake passage 2 </ b> A upstream of the throttle valve 5 acts on the power nozzle 13. Thereby, the power fuel controlled by the power fuel control jet 14 is additionally increased to the main fuel sucked from the needle jet 7 of the main fuel system M.
On the other hand, as shown in FIGS. 4 and 5, when the engine speed increases beyond a certain high speed, for example, 12000 RPM, it is known that the decrease in the engine output can be suppressed by reducing the fuel flow supplied to the engine. . This is indicated by the solid line in the figure.
On the other hand, it is shown by the dotted line in the figure that the engine output decreases when the fuel flow rate continues to increase beyond a certain high rotational speed.
As described above, when the engine speed reaches a constant high speed (for example, 12000 RPM), the power fuel passage 12 is closed by energizing the normally-open solenoid valve NO, and the power nozzle 13 is closed to the inside of the intake passage 2A. The supply of fuel to the engine is stopped to reduce the amount of fuel supplied to the engine, thereby suppressing a decrease in the output of the engine.
[0005]
[Problems to be solved by the invention]
Such a conventional power fuel control device for a carburetor has the following problems.
(1) The solenoid valve disposed in the power fuel passage is of a normally open type (in other words, an energized closed type), and a valve seat 15 formed in the solenoid valve is formed facing the opposite side of the movable core 16. .
According to this, the movable core 16 and the valve portion 17 that opens and closes the valve seat 15 are formed separately from each other in advance, and synchronize the valve portion 17 with the movable core 16 in a state where the valve portion 17 is assembled to the valve body 18. Must be integrally formed so as to move.
For this purpose, it is necessary to dispose the valve portion 17 by elastically pressing it toward the movable core 16 or to attach the valve portion 17 to the movable core 16 with fixing means.
According to the above description, the number of parts is increased and the number of assembling steps is increased, so that the solenoid valve is expensive, and the manufacturing cost of the vaporizer is increased, which is not preferable.
(2) The power fuel passage communicates the power nozzle with the portion below the constant fuel level of the float chamber, and furthermore, it is necessary to arrange an electromagnetic valve in the middle of the power fuel passage.
According to the above, the arrangement of the power fuel passage becomes complicated, which hinders the design freedom of the power fuel passage, and further hinders the smooth flow of the fuel flowing in the power fuel passage.
(3) When the coil is energized, the solenoid valve generates heat.
On the other hand, the power fuel flowing through the power fuel passage flows inside the solenoid valve, and according to the fuel flowing through the solenoid valve,
The fuel may generate vapor in the solenoid valve.
Care must therefore be taken that fuel does not cause vapor lock in the solenoid valve.
[0006]
The power fuel control device for a carburetor according to the present invention has been made in view of the above-mentioned problems, and aims at smoothing the flow of the fuel flowing through the power fuel passage, eliminating the occurrence of the vapor lock phenomenon of the fuel, and manufacturing the same. It is an object of the present invention to provide a low-cost device.
[0007]
[Means for solving the problem]
In the power fuel control device for a carburetor according to the present invention, the intake passage penetrating the carburetor body is controlled to be opened and closed by a throttle valve, and the intake passage upstream of the throttle valve is provided below the constant fuel level in the floating chamber. In a carburetor that opens a power nozzle communicated via a power fuel passage and draws power fuel from the power nozzle into an intake passage at an opening equal to or greater than a certain opening of a throttle valve,
A power fuel control jet is arranged in series in a power fuel passage upstream of the power nozzle, and a single power air passage communicating with the atmosphere is opened in the power fuel passage between the power nozzle and the power fuel control jet. The first feature is that a normally closed solenoid valve that opens the power air passage only when the engine speed is equal to or higher than a certain high speed is arranged in the power air passage.
[0008]
According to the present invention, in addition to the first feature, a second feature is that a power air amount adjusting means for controlling an air amount flowing through the power air passage is arranged in the power air passage.
[0009]
[Action]
According to the first feature, when the engine speed reaches a high speed equal to or higher than a certain high speed, the solenoid valve opens the power air passage and connects the power nozzle to the power fuel control jet from the power air passage. Supply air into the power fuel passage.
According to this, the negative pressure in the power fuel passage changes to the atmospheric pressure state, and power fuel is not sucked out from the power fuel control jet.
Thus, when the engine speed is equal to or higher than a certain high speed, the fuel flow rate can be reduced, and a large decrease in engine output can be suppressed.
[0010]
According to the second feature, when air is supplied into the power fuel passage via the solenoid valve when the engine speed is equal to or higher than a certain high speed, the supplied air amount is appropriately adjusted by the power air amount adjusting means. Since the adjustment control can be performed, the amount of decrease in the fuel flow rate at a certain high rotational speed or more can be appropriately controlled, and the fuel flow rate can be corrected to an optimal fuel flow rate for maintaining the engine output.
[0011]
【Example】
Hereinafter, a first embodiment of a power fuel control device for a carburetor according to the present invention will be described with reference to FIG.
The same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.
Reference numeral 20 denotes a power fuel passage, one end of which opens below the constant fuel level in the float chamber 4, and the other end of which opens into the intake passage 2 </ b> A upstream of the throttle valve 5 via the power nozzle 13.
Then, the power fuel control jet 14 is arranged in series in the power fuel passage 20 on the upstream side of the power nozzle 13.
Reference numeral 21 denotes a single power air passage, one end of which is open to the atmosphere (for example, near the upstream end of the intake passage 2A upstream of the throttle valve 5, an air cleaner (not shown), or directly to the atmosphere), and the other end. Opens in the power fuel passage 20A between the power nozzle 13 and the power fuel control jet 14.
[0012]
In the power air passage 21, a normally closed solenoid valve NC that opens and closes the air passage is arranged.
The normally closed solenoid valve NC includes an electromagnetic portion S and a valve portion V.
The electromagnetic portion S includes a coil bobbin 23 around which the coil 22 is wound, a housing 24 disposed around the outer periphery of the coil 22, and a fixed core which is inside the coil bobbin 23 and is fixed to the bottom of the housing 24. 25, a movable core 26 in the coil bobbin 23 that faces the fixed core 25 and is movably housed and disposed so as to be attracted to and separated from the fixed core 25, and separates the movable core 26 from the fixed core 25. And a movable core spring 27 that urges the movable core spring.
[0013]
The valve part V consists of:
The valve body 30 is provided with an air passage 32 that is divided into a primary air passage 32A and a secondary air passage 32B by a valve seat 31. The valve seat 31 faces a right end 30A of the valve body 30.
[0014]
The electromagnetic portion S is disposed on the right end 30A of the valve body 30. At this time, the valve seat 31 formed on the valve body 30 faces the movable core 26 side. The valve seat 31 is opened and closed by a valve portion 33 integrally formed with the movable core 26.
As described above, when the coil 22 is not energized, the valve portion 33 closes the valve seat 31, and a normally closed solenoid valve NC is formed in which the valve portion 33 opens the valve seat 31 by energizing the coil 22.
[0015]
The left end 30B of the valve body 30 of the normally closed solenoid valve NC is disposed on the right side of the carburetor body 1, whereby the primary air passage 32A of the solenoid valve NC is located on the atmosphere side. The secondary air passage 32B is connected to the power air passage 21 toward the power fuel passage 20A between the power nozzle 13 and the power fuel control jet 14.
In other words, the normally closed solenoid valve NC is disposed in the power air passage 21.
[0016]
Next, the operation will be described.
The throttle valve 5 is energized to the coil 22 of the normally closed solenoid valve NC when the throttle valve 5 is, for example, at an intermediate opening degree or more, at a high opening degree, and at a constant high rotation rate of 12000 RPM or less, for example. However, according to this, the valve portion 33 of the solenoid valve NC closes and holds the valve seat 31, and the air flows from the power air passage 21 into the power fuel passage 20 </ b> A between the power nozzle 13 and the power fuel control jet 14. Is not supplied.
According to the above description, the negative pressure generated in the intake passage 2A on the upstream side of the throttle valve 5 effectively acts on the power fuel passage 20A between the power nozzle 13 and the power fuel control jet 14 via the power nozzle 13. Power fuel corresponding to the negative pressure is supplied into the intake passage 2 through the power nozzle 13, whereby the flow rate of fuel supplied to the engine can be increased to obtain a desired engine output.
[0017]
Next, when the engine speed is increased to 12000 RPM or more when the throttle valve 5 is at a medium opening or higher and at a high opening, a current flows through the coil 22 of the normally closed solenoid valve NC. 26 is attracted to the fixed core 25 against the spring force of the movable core spring 27, and the valve section 33 opens the valve seat 31.
When the valve seat 31 is opened, the atmospheric pressure is introduced from the power air passage 21 into the power fuel passage 20A between the power nozzle 13 and the power fuel control jet 14.
According to the above description, the negative pressure in the intake passage 2A acting on the power fuel passage 20A between the power nozzle 13 and the power fuel control jet 14 via the power nozzle 13 immediately becomes the atmospheric pressure. Since the power fuel cannot be sucked into the power fuel passage 20A from the power fuel control jet 14, the supply of the power fuel into the intake passage 2A via the power nozzle 13 is stopped.
When the supply of the power fuel from the power nozzle 13 to the intake passage 2A is stopped, the fuel flow rate is reduced at a stretch, and the fuel mixture is supplied to the engine at an appropriate concentration. Therefore, the engine output is controlled to be thin, and a decrease in engine output can be suppressed.
[0018]
When the engine speed rises above a certain speed, the coil 22 is energized only by detecting the engine speed with a rotation sensor and performing ON / OFF control of the current.
[0019]
As described above, according to the present invention, the power fuel passage 20 only needs to communicate with the power nozzle 13 and below the constant fuel level in the float chamber 4 and the solenoid valve is not disposed in the power fuel passage 20. The arrangement of the fuel passage is simple, the degree of freedom in designing the power fuel passage can be greatly increased, and the flow of the fuel flowing through the power fuel passage 20 can be made smooth by the simple passage configuration, thereby improving the dynamic characteristics of the fuel supply. I was able to.
On the other hand, the power air passage 21 is a single passage and one end thereof only needs to be opened on the atmospheric pressure side. Therefore, the degree of freedom in selecting the opening position is high, and the design freedom of the power air passage is not limited. Not inhibited.
[0020]
Further, when the solenoid valve NC is energized, the valve body 30 is warmed by the heat generated by the coil 22. However, since fuel does not flow into the valve body 30, the vapor lock due to evaporation of the fuel is prevented. On the other hand, there is no need to consider anything, and the degree of freedom in designing the vaporizer can be increased.
[0021]
Furthermore, according to the use of the normally closed type electromagnetic valve, the valve seat 31 is formed facing the movable core 26 of the electromagnetic portion S, and the valve portion 33 can be formed integrally with the movable core 26. This makes it possible to use an inexpensive solenoid valve with a small number of man-hours, which is effective in reducing the manufacturing cost of the vaporizer.
[0022]
A second embodiment of the present invention will be described with reference to FIG.
1 are denoted by the same reference numerals, and description thereof will be omitted.
Numeral 40 denotes a power air amount adjusting means disposed in the power air passage 21. The power air amount adjusting means 40 may be an air jet or a tapered needle valve. The power air passage 21 extending between the jet 14 and the power nozzle 13 toward the power fuel passage 20A, the power air passage 21 extending from the valve seat 31 to the atmosphere side, or the valve seat 31 may be provided.
[0023]
According to the above description, when the engine speed rises above a certain high speed and the normally closed solenoid valve NC opens the valve seat 31, the power air controlled by the power air amount adjusting means 40 from the power air passage 21. Is supplied to the power fuel passage 20 </ b> A between the power fuel control jet 14 and the power nozzle 13.
Here, by selecting the air amount controlled by the power air amount adjusting means 40, it is possible to freely set the decreasing rate of the fuel flow rate when the engine speed is higher than a certain high speed.
[0024]
That is, when the fuel flow rate is greatly reduced at a certain high engine speed or higher, a large amount of power air is supplied by the power air amount adjusting means 40 between the power fuel control jet 14 and the power nozzle 13. The fuel is supplied to the fuel passage 20A.
According to the above, the pressure in the power fuel passage 20A is close to the atmospheric pressure. According to this, the power fuel cannot be sucked out from the power fuel control jet 14, and the fuel flow rate can be greatly reduced.
[0025]
On the other hand, when a small amount of power air is supplied by the power air amount adjusting means 40 to the power fuel passage 20A between the power fuel control jet 14 and the power nozzle 13 at a certain high engine speed or higher, the power fuel passage 20A The internal pressure slightly brings the pressure closer to the atmospheric pressure than the pressure before the solenoid valve NC opens the valve seat 31.
According to this, the power fuel sucked from the power fuel control jet 14 is slightly reduced, whereby the rate of decrease in the fuel flow rate can be reduced.
[0026]
Above a certain high engine speed, the rate of decrease in the fuel flow rate varies depending on the characteristics of the engine, the characteristics of the vehicle, the running conditions, and the like. By the selection, it is possible to obtain a reduced fuel flow rate optimal for each characteristic, and it is possible to provide a carburetor power fuel control device capable of effectively improving the engine output characteristic.
[0027]
【The invention's effect】
According to a first aspect of the present invention, a single power air passage is opened in a power fuel passage between a power nozzle and a power fuel control jet, and the power air passage has a constant high engine speed. Since a normally closed solenoid valve that opens the power air passage only when the number is more than a few is arranged, the flow of power fuel flowing through the power fuel passage can be smoothed, and the dynamic characteristics of fuel supply can be improved. It is possible to provide an inexpensive power fuel control device that does not cause a vapor lock phenomenon in the power fuel passage.
[0028]
According to the second feature of the present invention, in addition to the first feature, the power air passage is provided with the power air amount adjusting means for controlling the amount of air flowing through the power air passage. The reduction rate of the fuel flow rate at a high rotational speed or higher can be set very easily, and the output control of the engine can be more effectively performed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a first embodiment of a power fuel control device for a carburetor according to the present invention.
FIG. 2 is a longitudinal sectional view showing a second embodiment of the power fuel control device for a carburetor according to the present invention.
FIG. 3 is a longitudinal sectional view showing a conventional example of a conventional power fuel control device for a carburetor.
FIG. 4 is a diagram showing a relationship between an engine output and an engine speed;
FIG. 5 is a diagram showing a relationship between a fuel flow rate and an engine speed;
[Explanation of symbols]
REFERENCE SIGNS LIST 1 carburetor main body 2 intake passage 2A intake passage 4 upstream of throttle valve 4 float chamber 5 throttle valve 13 power nozzle 14 power fuel control jet 20 power fuel passage 20A power fuel passage 21 between power fuel control jet and power nozzle Power air passage NC Normally closed solenoid valve 40 Power air amount adjusting means

Claims (2)

The intake passage that penetrates the carburetor body is controlled to open and close by a throttle valve, and a power nozzle that is connected to the intake passage upstream of the throttle valve through a power fuel passage below the constant fuel level in the float chamber is opened. In the carburetor that draws the power fuel from the power nozzle into the intake passage at an opening equal to or greater than the fixed opening of the throttle valve,
A power fuel control jet is arranged in series in a power fuel passage upstream of the power nozzle, and a single power air passage communicating with the atmosphere is opened in the power fuel passage between the power nozzle and the power fuel control jet. A power fuel control device for a carburetor, wherein a normally closed solenoid valve that opens the power air passage only when the engine speed is equal to or higher than a certain high speed is arranged in the power air passage. The power fuel control device for a carburetor according to claim 1, wherein power air amount adjusting means for controlling an air amount flowing through the power air passage is arranged in the power air passage.

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