JP2003254162A - Starting fuel supplying device for carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a starting fuel supplying device enabling an engine to start easily and certainly by supplying a specified amount of starting fuel neither too much nor insufficient using a manually operated fuel introducing pump to be handled simply. <P>SOLUTION: Downstream side of a throttle valve 4 installed in a suction passage 2, a starting fuel chamber 38 having a fuel sendout hole 53 is installed, connected with the discharge hole of the fuel introducing pump 31 through a starting fuel passage 37, and furnished with an introducing amount sensor 47 whereto a light emitter and light receiver are installed confronting. When a start switch 58 is put on, an opening/closing valve 42 is opened to cause the fuel to be introduced to the chamber 38 from the pump 31, and when the introduced quantity becomes a certain value approximately, the valve 42 is closed in conformity to a signal from the sensor 47 so that a further introduction can not be made. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor starting fuel supply device, and more particularly to a device capable of appropriately supplying starting fuel to a general-purpose engine by a simple operation procedure.

[0002]

2. Description of the Related Art A high concentration air-fuel mixture is often required for a good engine start. Therefore, in a carburetor for a general-purpose engine, it is widely known that a choke valve is installed at the inlet of the intake passage to generate a high negative pressure on the downstream side by cranking to increase the amount of fuel sucked into the intake passage. .

Further, in order to avoid the troublesome opening adjustment from the start of the choke valve to the completion of warming up, a manual fuel introduction pump is used to introduce a prescribed amount or more of fuel into the fuel system inside the carburetor before starting. That is, (see Japanese Patent Laid-Open No. 55-69748), the starting fuel is delivered to the intake passage at the time of cranking when the throttle valve is largely opened by using the fuel introduction pump that operates by the pressure pulsation generated by the engine rotation ( U.S. Pat. No. 5,706,774), starting fuel by connecting a mixture passage downstream of the throttle valve in the intake passage and opening / closing the mixture passage with an opening / closing valve that opens when the throttle valve is closed and closes when the throttle valve is opened. Is sent to the intake passage (JP-A-8-28).
No. 4754) is proposed.

[0004]

However, among the above-mentioned starting fuel supply means, the one using a manual fuel introduction pump is easy to operate, but on the other hand, in the state of lack of fuel or in many cases, it is excessive in the intake passage. It tends to be in a sent state,
It is difficult to ensure a stable start. In addition, the one using a fuel introduction pump that operates with pressure pulsation is not common because it corresponds to the peculiar usage of opening the throttle valve widely to start it, and also puts the throttle valve in the open position. It is extremely troublesome to handle because it is held and cranked. In addition, if the throttle valve is inadvertently released, the starting pump will stop and it will not be possible to start, or if the throttle valve is opened for normal operation after starting, fuel introduction There is the inconvenience that the pump operates again to make the mixture rich. Further, in the case of using the air-fuel mixture passage, since the air-fuel mixture passage is opened at the throttle valve idle position and closed at the off-idle position, if the throttle valve is opened at the wrong timing, the starting fuel is shut off and the engine cannot be started. In addition, starting fuel is added to idle fuel to make the mixture rich.

The present invention has been made to solve these problems of the above-mentioned conventional starting fuel supply means, and always uses a manual fuel introduction pump which is easy to operate and always supplies a required amount of starting fuel. It is an object of the present invention to provide a starting fuel supply device that can secure the fuel consumption.

[0006]

In order to solve the above-mentioned problems, the present invention provides a starting fuel supply device for a carburetor with a manual fuel introduction pump and a fuel delivery hole opened downstream of a throttle valve in an intake passage. A starting fuel chamber having the same, a starting fuel passage connecting the fuel introduction pump and the starting fuel chamber, an electromagnetically driven on-off valve for opening and closing the passage, and an introduction amount detection for detecting that fuel is introduced into the starting fuel chamber And an electric control circuit and a manual start switch; by first turning on the start switch, the electric control circuit opens the on-off valve,
Next, the fuel is introduced into the starting fuel chamber by operating the fuel introduction pump, and when a substantially constant amount of fuel is introduced based on the signal from the introduction amount detector, the electric control circuit closes the on-off valve. After that, the fuel introduction was stopped.

As described above, according to the present invention, the on-off valve and the introduction amount detector cannot be used after the introduction of a substantially constant amount of fuel into the starting fuel chamber, according to the present invention. With the introduction pump, the required amount of starting fuel can always be secured and the engine can be easily and surely started without any fear of excessive introduction.

In addition to the above, the present invention provides the operator of the fuel introduction pump with a visual confirmation of the fuel introduction status to the starting fuel chamber by turning on and off at the same time as the opening and closing of the on-off valve. It was equipped with an indicator light.

By seeing the indicator lamp in this way, it is possible to recognize that the fuel can be introduced while the lamp is lit and that a predetermined amount is introduced when the lamp is extinguished and the fuel is not introduced thereafter. According to the present invention, it is possible to secure a predetermined amount of fuel necessary for starting without operating the fuel introduction pump in excess or shortage and causing fuel shortage or continuing wasteful operation.

Furthermore, the present invention, in addition to any of the above,
The return passage for returning the fuel discharged from the fuel introduction pump to the fuel tank after the on-off valve is closed is branched from the starting fuel passage.

As described above, according to the present invention, the fuel sent by the extra operation of the fuel introduction pump is returned to the fuel tank, so that the abnormal increase of the pressure due to the closing of the on-off valve is prevented and the parts are damaged. And fuel leakage can be eliminated.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. Atmosphere is introduced into a lower surface of a main body 1 which is formed by laterally penetrating an intake passage 2 having a venturi 2 and a throttle valve 4. A back pressure chamber 5 and a diaphragm 6 define a measuring chamber 7 defined by the diaphragm 6. Also, the main body 1
A base 9 is superposed on the upper surface of the main body 1 with the diaphragm 8 interposed therebetween, and the diaphragm 8 is placed on the upper surface of the main body 1 and the lower surface of the base 9.
The recess formed between the two is the pulse chamber 11 of the fuel pump 10.
And a pump chamber 12 are formed.

The pulse chamber 11 is connected to the crankcase or the intake manifold of the engine by a passage (not shown), and the pressure pulsation generated in the crankcase of the engine with the rotation of the engine is introduced to reciprocally displace the diaphragm 8. The pump chamber 12 is connected to the fuel tank 13 by a suction passage 15 having an inlet check valve 14 formed by the diaphragm 8 and an external suction pipe line 16, and an outlet check valve 17 also formed by the diaphragm 8 is connected to the fuel tank 13. It is connected to the measuring chamber 7 by a discharge passage 18 provided therein. A lever 19 that rotates according to the displacement of the diaphragm 6 is provided at the outlet of the discharge passage 18 to the measuring chamber 7.
A fuel valve 20 attached to the.

Further, the main jet 22 and the Venturi 3
A main fuel passage 21 having a main nozzle 23 opened to the lower side and a low speed fuel passage 24 having an idle port 26 and a slow port 27 opened to the side of the low speed jet 25 and the throttle valve 4 extend from the metering chamber 7.

The fuel pump 10 operates by pressure pulsation generated by the rotation of the engine to suck the fuel in the fuel tank 13 into the pump chamber 12 through the suction pipe line 16 and the suction passage 15, and then pressurizes and discharges the fuel. 18 to the metering chamber 7 and the fuel valve 20 opens and closes the discharge passage 18 according to the displacement of the diaphragm 6 so that the metering chamber 7 holds a certain amount of fuel. Is the same.

Next, in the starting fuel supply system according to the present embodiment, a manual fuel introducing pump 31, a starting fuel chamber 38, a starting fuel passage 37 extending from the fuel introducing pump 31 to the starting fuel chamber 38, and a branch from this. Return passage 39 leading to the fuel tank 13, an external return pipe 40, an electromagnetically driven on-off valve 4
2, introduction amount detector 47, electric control circuit 54, indicator light 5
6. It has a start switch 58.

The fuel introduction pump 31 is made up of an elastic dome body 32 whose peripheral portion is overlapped and fixed to the base 9, and a pump chamber 33 is formed inside thereof. The pump chamber 33 is connected to the metering chamber 7 by a suction passage 35 having an inlet check valve 34, and is also connected to a starting fuel passage 37 leading to a starting fuel chamber 38 via an outlet check valve 36.

The on-off valve 42 is a normally-closed type electromagnetic valve, which has a valve chamber 43, a valve body 44 and a valve seat 45 formed in the middle of the starting fuel passage 37, and a coil case 46 of the drive section is a base. Stand 9
It is fixed to. The coil case 46 holds the coil and the fixed iron core, and the valve element 44 is attached to the movable iron core projecting from the coil case 46 into the valve chamber 43.

The return passage 39 is provided in the valve chamber 43, and the starting fuel passage 3 is provided.
7 has a throttle 41 that restricts the flow of fuel.

As the introduction amount detector 47, there is used a well-known water turbine type fuel flow rate sensor in which a light emitting diode and a photodiode are arranged to face each other and a rotor is installed between them, and this is installed in the starting fuel passage 37. The introduction amount may be known by integrating the detected flow rates. However, in the present embodiment, a light emitting device 48 formed of an infrared light emitting diode and a light receiving device 49 formed of a phototransistor, which are used to measure the transmittance of a transmission material, are arranged so as to face each other. Three
Installed in 8.

The introduction amount detector 47 according to the present embodiment as described above has an advantage that the number of parts is smaller than that of the water turbine type fuel flow rate sensor and that there is no fear of error due to rotation of the water turbine due to inertia. There is. In addition, since the starting fuel chamber 38 is a space where external light such as sunlight does not enter, it is not necessary to consider the influence of external light, which is noise, and accurate detection can be easily performed.

The light emitter 48 and the light receiver 49 are attached to the side walls 50a and 50b of the U-shaped attachment block 50 which face each other. Then, the block 50 is hermetically fitted into the mounting hole 51 formed on the downstream side of the throttle valve 4 below the intake passage 2 of the main body 1 by the O-ring 52, and the side walls 50a, 50b and the bottom between them. The space surrounded by the wall portion 50c and the hole wall of the mounting hole 51 forms the starting fuel chamber 38. At the center of the top surface of the starting fuel chamber 38,
Fuel delivery hole 5 opened downstream of the throttle valve 4 in the intake passage 2.
3 is provided.

Further, the light emitter 48 and the light receiver 49 are installed at the center of a high place of the starting fuel chamber 38.
The infrared rays emitted by the laser beam enter the light receiver 49 across the central portion of the starting fuel chamber 38, which is close to the top surface. Therefore, even if the fuel is introduced in a state where the vaporizer is not horizontal but inclined, all the infrared rays incident on the light receiver 49 will pass through the fuel when a substantially constant amount of fuel is introduced. Therefore, it is possible to confirm that the fuel introduced into the starting fuel chamber 38 has reached a substantially constant amount by presetting the amount of change from the transmittance (100%) when there is no fuel at that time. You can know exactly.

In addition to the signal from the introduction amount detector 47, the electric control circuit 54 receives a signal from a temperature sensor 55 for detecting the temperature of the engine or its vicinity. In addition to the current supplied to the coil of the drive unit of the on-off valve 42, the current supplied to the indicator lamp 56 is output. Generally, a dry battery can be used as the power source 57 of the electric control circuit 54, and the electric control circuit 54 becomes operable by closing the power supply circuit by turning on the start switch 58, thereby making the coil and the indicator lamp. Supply current to 56.

The indicator lamp 56 is installed at a location where an operator of a machine / equipment equipped with an engine equipped with a carburetor can easily see it, and consumes less power and is less likely to be damaged. Therefore, the indicator lamp 56 is preferably red. Those that emit colored light such as green are used. Also, the start switch 58
May be a dedicated one, but in the present embodiment, it is also used as an engine ignition switch. As is well known, the ignition switch of a general-purpose engine is placed in two positions, an off position and an ignition position, and the electric control circuit 54 can be operated at the same time when the ignition switch is in the ignition position for starting.

Next, the procedure for introducing the starting fuel according to the present embodiment having such a structure will be described. First, the starting switch 58 is turned on to energize the electric control circuit 54 to bring it into an operable state. At the same time, the on-off valve 42 is opened by the magnetic force generated by energizing the coil, and the indicator lamp 5
6 is energized and lights up. Further, the light emitter 48 of the introduction amount detector 47 emits infrared rays toward the light receiver 49.

Next, when the operator turns on the start switch 58 or confirms that the indicator lamp 56 is turned on, the operator repeatedly repeats compression and release of the dome body 32 of the fuel introduction pump 31, and a negative pressure is applied to the suction side. From the fuel tank 13 to the suction pipe line 16, the suction passage 15, the pump chamber 12, the discharge passage 1
The fuel is sucked into the pump chamber 33 through 8, the measuring chamber 7, and the suction passage 35, and then the pressurized fuel is sent to the starting fuel chamber 38 through the starting fuel passage 37. At this time, a part of the fuel passing through the valve chamber 43 flows into the return passage 39 and returns to the fuel tank 13, but its amount is small because it is limited by the throttle 41, and the efficiency of the fuel introduction pump 31 is remarkably increased. Do not lower.

When the fuel introduced into the starting fuel chamber 38 reaches a substantially constant amount, all of the infrared rays incident on the photodetector 49 will pass through the fuel, and the infrared ray transmittance from the infrared ray in the absence of fuel will be transmitted. The rate change rate reaches the set value. As a result, the electric control circuit 54 causes the starting fuel chamber 3
It is judged that the required amount of starting fuel has been introduced into the valve 8, and the energization of the coil of the on-off valve 42 is stopped and the valve is closed.

When the opening / closing valve 42 is closed, the fuel is not introduced into the starting fuel chamber 38, and even if the operation of the fuel introduction pump 31 is continued thereafter, all the discharged fuel is returned to the return passage 39 and the return conduit. Fuel tank 13 through 40
Returned to. In the present embodiment, since the indicator light 53 is turned off, it is possible to eliminate extra operation of the fuel introduction pump 31 by confirming that the indicator 53 is turned off. Then, generally, the engine is started by pulling the starter rope. The fuel in the starting fuel chamber 38 is sucked to a high negative pressure on the downstream side of the throttle valve 4 and is discharged to the suction passage 2 from the fuel discharge hole 53. Since the fuel delivery hole 53 only delivers the starting fuel, it can be formed in an arbitrary size and delivered in a short time to improve the startability.

Here, in this embodiment, the temperature sensor 55 is used.
Since the temperature of the engine or the vicinity thereof is detected by the engine, the amount of change in the transmittance when the on-off valve 42 is closed and the indicator lamp 56 is turned off, that is, the amount of fuel introduced into the starting fuel chamber 38 is set to the temperature. According to the setting, it is possible to secure the optimum amount of starting fuel according to the temperature. Further, when the temperature is high above a certain level, even if the start switch 58 is turned on, the on-off valve 42 is kept closed and the indicator lamp 53 is kept off, so that unnecessary starting fuel is not required at high temperature restart. Will never be supplied.

The electric control circuit 54 has a built-in switch function for cutting off the current when the fuel is introduced into the starting fuel chamber 38 and the on-off valve 42 is closed and the indicator lamp 56 is turned off. Even if the activation switch 58 which is also used as a switch remains in the ON state, the power source 57 is not consumed unnecessarily.

[0032]

As described above, according to the present invention, it is possible to start the engine easily and surely by using the manual fuel introduction pump which is easy to operate and supplies the required amount of starting fuel without excess or deficiency. belongs to.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged partial view of FIG.

3 is a sectional view taken along the line AA of FIG.

[Explanation of symbols]

2 intake passage, 4 throttle valve, 7 metering chamber, 10 fuel pump, 13 fuel tank, 31 fuel introduction pump, 37
Start fuel passage, 38 start fuel chamber, 39 return passage,
41 throttle, 42 on-off valve, 47 introduction amount detector, 48
Light emitter, 49 light receiver, 53 fuel outlet, 54 electric control circuit, 55 temperature sensor, 56 indicator light, 58 start switch,

Claims (8)

[Claims] 1. A manual fuel introducing pump, a starting fuel chamber having a fuel delivery hole opened downstream of a throttle valve in an intake passage, a starting fuel passage connecting the fuel introducing pump and the starting fuel chamber, and An electromagnetically driven opening / closing valve for opening / closing the passage, an introduction amount detector of the fuel introduced into the starting fuel chamber, an electric control circuit and a manual starting switch are provided, and by first turning on the starting switch, An electric control circuit opens the on-off valve and then operates the fuel introduction pump to introduce fuel into the starting fuel chamber, and a substantially constant amount of fuel based on a signal from the introduction amount detector. When the fuel injection is introduced, the electric control circuit closes the on-off valve to stop the subsequent fuel introduction, so that the carburetor start-up fuel supply device. 2. The starting fuel supply device according to claim 1, further comprising an indicator light, wherein the indicator light is turned on at the same time as the opening and closing of the on-off valve and turned off at the same time as the closing valve is operated. A starting fuel supply device for a carburetor, which allows a person to visually recognize the state of introduction of fuel into the starting fuel chamber. 3. The starter fuel supply device according to claim 1, further comprising a return passage branched from the starter fuel passage and connected to a fuel tank, wherein the return passage has the opening / closing valve closed. After that, the fuel discharged from the fuel introduction pump is returned to the fuel tank. 4. The introduction amount detector comprises an infrared light emitting diode, which is a light emitting device, and a phototransistor, which is a light receiving device, which are installed opposite to each other at the center of a high place in the starting fuel chamber, and measure the amount of change in light transmittance. The starting fuel supply device for a carburetor according to claim 1, 2, or 3. 5. The carburetor starting fuel supply device according to claim 1, wherein the start switch is an engine ignition switch. 6. The carburetor starting fuel supply device according to claim 2, wherein the indicator lamp uses a light emitting diode as a light source to emit colored light. 7. The starter fuel supply system for a carburetor according to claim 3, wherein the return passage has a throttle for limiting a fuel flow. 8. The engine starting fuel supply device according to claim 1, wherein the amount of introduction into the starting fuel chamber is variable according to the temperature of the engine or the vicinity thereof.