JP3472895B2 - Power fuel control for carburetor - Google Patents

Description

Description: 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. At a certain opening or more,
The present invention relates to a power fuel control device for a carburetor that supplies power fuel to a main fuel supplied from a main fuel system. [0002] A conventional power fuel control device for a carburetor is:
As 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. You. The intake passage 2 is opened and closed by a throttle valve 5 controlled by a driver. The intake passage 2 is connected to an upstream intake passage 2A which is connected to an air cleaner (not shown in the figure on the right side) by the throttle valve 5. , And is divided into a downstream-side intake passage 2 </ b> B connected to an engine (left side in the figure, not shown). In the float chamber 4, a constant fuel level XX is formed and held by the cooperative action of the float 6, the valve seat (not shown), and the float valve. M
Is a main fuel system, comprising a needle jet 7, a mixing tube 8, and a main fuel jet 9,
The needle jet 7 opens into the intake passage 2, the main fuel jet 9 is immersed below the constant fuel level in the float chamber 4, and the jet needle 10 attached to the throttle valve 5 is inserted into the needle jet 7. You. 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 comprises the following. 1
Reference numeral 2 denotes a power fuel passage provided at the downstream end thereof with a power nozzle 13 opening into the intake passage 2A on the upstream side of the throttle valve, and having an upstream end opening below the constant fuel level in the float chamber 4. A power fuel control jet 14 and a normally open solenoid valve NO are arranged in series in the power fuel passage 12 on the more upstream side. When the throttle valve 5 opens the intake passage 2 to a certain opening (for example, 1/2 opening) or more, the increased negative pressure in the intake passage 2A upstream of the throttle valve 5 causes the power nozzle 13 to open. On the power fuel control jet 1
The power fuel controlled at 4 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. 3 and 4, when the engine speed increases beyond a certain high speed, for example, over 12000 RPM, it is known that a 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. From the 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 reduction in the output of the engine. [0005] The conventional power fuel control device for a carburetor has the following problems. That is, if the normally open solenoid valve is closed while the engine speed is higher than a certain high speed, the power fuel control jet controls the fuel supply to stop the supply of fuel from the power nozzle into the intake passage. Is done. This makes it possible to reduce the fuel flow rate when the engine is operating at a constant high speed or higher. The amount of decrease is uniquely determined corresponding to the amount of fuel supplied from the power fuel control jet. On the other hand, a vaporizer is commonly used by a plurality of engines. In addition, the use state of the engine may vary greatly depending on the use purpose and use conditions of the vehicle type to be mounted. Therefore, the optimal amount of decrease in the fuel flow rate when the engine speed is equal to or higher than a certain high speed is variously different. In view of the above, when the engine speed is higher than a certain high speed, if the decrease in fuel flow rate is uniquely determined by the control flow rate of the power fuel control jet, the optimum fuel flow rate for a plurality of engines Was difficult to supply. [0006] The power fuel control apparatus for a carburetor according to the present invention has been made in view of the above-mentioned problems, and has an optimum fuel flow rate for maintaining the engine output at a high output state when the engine speed is higher than a certain high speed. It is an object of the invention to provide such a device which can be easily obtained and is adaptable to a plurality of institutions. In order to achieve the above object, a power fuel control apparatus for a carburetor according to the present invention is arranged such that an intake passage penetrating through the carburetor body is controlled to be opened and closed by a throttle valve. In the intake path upstream of the valve, a power nozzle communicated via a power fuel passage below the constant fuel level in the float chamber is opened. In a carburetor that draws fuel into the intake passage, the power fuel passage upstream of the power nozzle, the power fuel control jet toward the upstream, and the power fuel passage only when the engine speed is higher than a certain high speed A normally-open solenoid valve to be closed is arranged in series, while a downstream power fuel passage between the solenoid valve and the power fuel control jet and an upstream power fuel passage upstream of the solenoid valve are bypassed. A sub-power fuel control jet having a diameter smaller than the jet diameter of the power fuel control jet is arranged in the bypass power fuel passage. When the number of revolutions of the engine reaches a certain high revolution or higher, the solenoid valve closes the power fuel passage. According to the above description, the fuel properly controlled by the sub-power fuel control jet is supplied from the power nozzle into the intake passage, and the amount of decrease in the fuel flow rate at a certain high speed or higher can be appropriately controlled to maintain the engine output. It can be corrected to the optimum fuel flow rate. FIG. 1 shows an embodiment of a power fuel control apparatus for a carburetor according to the present invention. Note that the same components as those in FIG. 20 is
One end of the power fuel passage opens below the constant fuel level XX in the float chamber 4, and the other end opens to the intake passage 2 </ b> A upstream of the throttle valve 5 via the power nozzle 13. And
A power fuel control jet 14 and a normally open solenoid valve NO are arranged in series in the power fuel passage 20 upstream of the power nozzle 13 toward the upstream. The normally-open solenoid valve NO is, in other words, an energized closed type and is a known solenoid valve. The power fuel passage 20 is divided into a downstream power fuel passage 20A connected to the power nozzle 13 and an upstream power fuel passage 20B connected to the float chamber 4 by the valve seat 21 of the solenoid valve NO. Power fuel control jet 14
Is disposed in the downstream power fuel passage 20A. And an upstream power fuel passage 20B;
A downstream power fuel passage 20 </ b> A between the power fuel control jet 14 and the valve seat 21 of the solenoid valve NO bypasses the valve seat 21 and is connected by a bypass power fuel passage 22. In the bypass power fuel passage 22,
An auxiliary power fuel control jet 23 for controlling the amount of fuel passing through the bypass power fuel passage 22 is provided. The jet diameter of the auxiliary power fuel control jet 23 is selected to be smaller than the jet diameter of the power fuel control jet 14. That is, the amount of fuel controlled by the auxiliary power fuel control jet 23 is smaller than the amount of fuel controlled by the power fuel control jet 14. Next, the operation will be described. Throttle valve 5
For example, when the opening is medium or higher, at the time of high opening, and at a constant high rotation of, for example, 12000 RPM or less, the coil of the normally open solenoid valve NO is not energized. Then, the valve portion of the solenoid valve NO holds the valve seat 21 open. According to the above description, the negative pressure generated in the intake passage 2 </ b> A on the upstream side of the throttle valve 5
The power fuel corresponding to the negative pressure is controlled by the power fuel control jet 14, supplied to the intake passage 2 through the power nozzle 13, and supplied to the engine. A desired engine output can be obtained by increasing the fuel flow rate. The jet diameter of the sub-power fuel control jet 23 is selected to be smaller than the jet diameter of the power fuel control jet 14, but the power fuel control jet 14 is provided with the sub-power fuel control jet 23. Fuel having a sufficiently large flow rate of the sum of the controlled fuel and the fuel flowing from the upstream power fuel passage 20B to the downstream power fuel passage 20A via the valve seat 21 due to the opening of the valve seat 21. The fuel supplied from the power nozzle 13 into the intake passage 2A is supplied by the fuel controlled by the power fuel control jet 14. Next, when the throttle valve 5 is at an intermediate opening degree or higher and at a high opening degree, when the engine speed rises to 12000 RPM or more, a current flows through the coil of the normally open solenoid valve NO,
According to this, the movable core is attracted to the fixed core against the spring force of the movable core spring, and the valve section 30 closes the valve seat 21. When the valve seat 21 is closed by the valve portion 30, the fuel flow from the upstream power fuel passage 20B to the downstream power fuel passage 20B via the valve seat 21 is cut off, and the power fuel control jet 14 , Only the fuel controlled by the auxiliary power fuel control jet 23 is supplied. Since the jet diameter of the auxiliary power fuel jet 23 is smaller than the jet diameter of the power fuel control jet 14, the reduced fuel controlled by the auxiliary power fuel jet 23 is supplied from the power nozzle 13 to the intake passage 2A. Supplied inside. Thus, the concentration of the air-fuel mixture is appropriately controlled to be lean, so that a decrease in engine output can be suppressed. When the engine speed rises above a certain speed, the coil is energized only by detecting the engine speed by a rotation sensor and performing ON / OFF control of the current. . As described above, when the engine speed rises above a certain high speed, the normally open solenoid valve NO comes into contact with the valve seat 21 to connect the upstream power fuel passage 20B and the downstream power fuel passage 20A. The fuel is controlled by the sub-power fuel control jet 23 and is supplied into the intake passage 2A via the power nozzle 13. Here, by selecting the amount of fuel to be controlled by the sub-power fuel control jet 23, it is possible to freely set the rate of decrease in the fuel flow rate at a certain high engine speed or higher. That is, when the fuel flow rate is greatly reduced at a certain high engine speed or higher, the jet diameter of the auxiliary power fuel control jet 23 is set to an extremely small diameter. On the other hand, when the fuel flow is reduced by a relatively small amount at a certain high engine speed or higher, the jet diameter of the auxiliary power fuel control jet 23 is set to a small diameter. As described above, when the engine speed is higher than a certain high speed, the decreasing rate of the fuel flow rate varies depending on the characteristics of the engine, the characteristics of the vehicle, the running conditions, and the like. By appropriately selecting the power fuel control jet, it is possible to obtain a reduced fuel flow rate optimal for each characteristic, and to provide a power fuel control device for a carburetor capable of effectively improving engine output characteristics. As described above, according to the power fuel control apparatus for a carburetor according to the present invention, a power fuel control jet is provided in the power fuel passage upstream of the power nozzle toward the upstream thereof, and A normally open solenoid valve that closes the power fuel passage only when the rotation speed is equal to or higher than a certain high rotation speed is arranged in series, while a downstream power fuel passage between the solenoid valve and the power fuel control jet is provided. An upstream power fuel passage upstream of the solenoid valve is connected to the upstream power fuel passage by a bypass power fuel passage, and a sub power fuel control jet having a diameter smaller than the jet diameter of the power fuel control jet is arranged in the bypass power fuel passage. Therefore, the reduction rate of the fuel flow rate at a certain high engine speed or higher can be set very easily, and the output control of the engine can be more effectively performed. It was something that could be done.

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 conventional example of a conventional power fuel control device for a carburetor. FIG. 3 is a diagram showing a relationship between an engine output and an engine speed; FIG. 4 is a diagram showing a relationship between a fuel flow rate and an engine speed; [Description of Signs] 1 Vaporizer main body 2 Intake path 2A Intake path 4 upstream of throttle valve 4 Float chamber 5 Throttle valve 13 Power nozzle 14 Power fuel control jet 20 Power fuel path 20A Downstream power fuel path 20B Upstream power fuel Passage 21 Valve seat 22 Bypass power fuel passage 23 Secondary power fuel control jet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02M 7/04 F02M 7/06 F02M 7/12 F02M 7/133

Claims (1)

(57) [Claims 1] An intake passage penetrating the carburetor body is controlled to be opened and closed by a throttle valve, and an intake passage upstream of the throttle valve is provided below a constant fuel level in a floating chamber. In the carburetor that opens the power nozzle communicated with the power fuel passage through the power fuel passage and draws the power fuel from the power nozzle into the intake passage at the opening of the throttle valve that is equal to or greater than a certain opening, the power upstream of the power nozzle is In the fuel passage, a power fuel control jet and a normally open solenoid valve that closes the power fuel passage only when the engine speed is equal to or higher than a certain high speed are arranged in series toward the upstream side, A downstream power fuel passage between the solenoid valve and the power fuel control jet and an upstream power fuel passage upstream of the solenoid valve are connected by a bypass power fuel passage. Power fuel control system of the vaporizer, characterized in that a secondary power fuel control jet of from jet diameter of your jet forms a small diameter.