JPH03249362A - Starting fuel feeder for carburetor - Google Patents

Abstract

PURPOSE:To make it so as not to prevent the starting of an engine due to feed of starting excess fuel at a time when the engine is in a high-temperature state, by installing a temperature switch, which is opened when ambient temperature in the engine is more than the specified value, in a current-energizing circuit for a solenoid on-off value. CONSTITUTION:When ambient temperature in an engine is lower than the specified value, a temperature switch 71 is being closed, and when a starting switch 35 is closed, the engine 31 is rotated by a starting motor 29. When this motor 29 is rotated, a diaphragm 28 of a fuel pump A is vertically reciprocated by pulsation pressure in a crankshaft of the engine 31, and fuel in a fuel tank 18 is fed to a metering chamber 26 of an inflow valve 23, and simultaneously fuel in this chamber 26 is drawn into an intake passage 9 by way of a passage 11, a solenoid on-off valve C, and a fuel sump chamber 10, thus the engine 31 is started smoothly. On the other hand, when the ambient temperature of the engine 31 is higher, the temperature switch 71 is opened, and since a control circuit 37 comes to a state of nonoperation, the valve C becomes closed intact, so that starting excess fuel is not feed at all, thus such a possibility that unnecessary excess starting fuel is fed and thereby smooth starting might be hampered is brought to nothing.

Description

[Detailed Description of the Invention] [Industrial Field of Application C] The present invention relates to a starting fuel supply device for a carburetor in an internal combustion engine installed in a portable working machine. As a starting fuel supply system for the engine, when the engine is started, the electromagnetic on-off valve in the starting fuel supply passage is opened, and the fuel in the fuel chamber of the carburetor is supplied to the intake passage through the normal fuel supply system and the starting fuel passage. has been applied for.

According to this starting fuel supply system, when the engine is being driven by the starting motor and after starting the engine (in a complete explosion state)
Based on the difference in engine speed between
Since the engine is supplied with a rich air-fuel mixture that is optimal for a full-open start, the engine can be started smoothly.

However, when restarting the engine immediately after stopping the engine, there is no need to supply starting fuel because the engine is at a high temperature. Instead, when the engine is started, the electromagnetic on-off valve opens and a rich air-fuel mixture is supplied to the engine, which actually hinders smooth restart of the engine.

[Problem to be Solved by the Invention 1] In view of the above-mentioned problems, the purpose of the present invention is to provide a starting fuel for a carburetor that does not prevent the engine from starting when the engine is in a high temperature state. The purpose is to provide a supply device.

[Means for Solving the ξ Problem] In order to achieve the above object, the configuration of the present invention is such that the electromagnetic on-off valve provided in the starting fuel supply passage connecting the fuel chamber of the carburetor and the @air passage is connected to the flywheel of the internal combustion engine. In a starting fuel supply system for a carburetor that is activated by the output signal of the magneto's primary coil, the energizing circuit of the electromagnetic on-off valve is equipped with a temperature switch that opens when the ambient temperature is below a predetermined value, or a starting fuel supply passage is provided. r!, which is closed by a thermally responsive body when the ambient temperature of the engine is above a predetermined value. #It is equipped with a closing valve.

[When starting the engine, the engine! When the part temperature or ambient temperature is below a predetermined value, the temperature switch in the energizing circuit of the electromagnetic on-off valve closes, and the electromagnetic on-off valve on the starting fuel supply passage connecting the fuel chamber of the carburetor and the intake passage opens, or the shape memory alloy Alternatively, another opening/closing valve in the starting fuel supply passage opens due to thermal deformation of a thermally responsive body such as thermowax, so starting fuel is sucked from the fuel chamber into the intake passage, and a rich air-fuel mixture is supplied to the engine. A smooth start can be obtained.

On the other hand, when the ambient temperature of the engine is above the predetermined temperature, the temperature switch opens and the electromagnetic closing valve closes, or the R closing valve closes due to thermal deformation of the thermally responsive body, so that no starting fuel is supplied. Therefore, I! When restarting the engine immediately after the engine stops, no starting fuel is supplied, and the restart of the engine is not hindered by the supply of starting fuel.

Embodiments of the Invention: FIG. 1 is a schematic diagram of a starting fuel supply system of the present invention applied to a tire flam type carburetor. The starting fuel supply device includes a diaphragm type fuel pump A in the main body 4 of the carburetor 1.
, the fuel supply mechanism B, the electromagnetic on-off valve C that opens and closes the starting fuel supply passage 1'1 between the fuel supply mechanism B and the intake passage 9, and the operation of the electromagnetic on-off valve C is controlled by the flywheel magnet 30 of the engine 31. Based on the signal of the primary coil 30a! 1lJIil
The control circuit 37 is provided with a control circuit 37 that controls the operation.

In the carburetor 1, a rotary throttle valve 8 is rotatably and axially movably supported by a cylindrical portion 7 that crosses an intake passage 9 of a main body 4. A lever 2 is coupled to the small diameter shaft portion of the compensating valve 8 having a throttle hole 8a, and a follower hanging down from the lever 2 is attached by a spring (not shown) to a cam 3a formed on the lid 3 that closes the cylindrical portion 7. force is engaged. When the lever 2 rotates the valve 8 to increase its opening, the rod valve 5 connected to the throttle valve 8 rises, the opening of the fuel injection hole 6a of the fuel supply pipe 6 increases, and the amount of fuel increases. The output of 31 is increased during 11.

A #5F4 reservoir 10 is formed at the bottom of the cylindrical portion 7, that is, below the comparison valve 8, and the #5F4 reservoir 10 for retaining the starting II' is formed so that when the engine 31 is started, the fuel in the fuel reservoir 10 is compared with the cylindrical portion 7. The air is sucked into the intake passage 9 through the gap with the valve 8. The fuel reservoir chamber 10 preferably accommodates a porous member such as ceramics.

The fuel pump A has a fuel ram 2 inside the fuel tank main body 4.
The pulsating pressure introducing chamber and the pump 28a are separated by 8, and the pulsating pressure introducing chamber is connected to the crank of the two-stroke engine 31. The pump 28a is the check valve 27. i! 55 to the fuel tank 18, and via a check valve 24, a valve 15, and an inlet valve 23 to a fuel chamber called a metering chamber 26 of the fuel supply IIA structure B.

! ! The fuel supply mechanism B has a metering chamber 26 and an atmospheric air 20 separated by a diaphragm 19 inside the vaporizer main body 4. The lever 21 is supported by a support shaft 22 inside the metering chamber 26 . One end of lever 2] is biased by a spring toward diaphragm 19, while F#! The station engages the inlet valve 23 and is biased to close it. The metering chamber 26 receives fuel F4I# supply via the fuel jet 25! It is communicated to No. 6, S. Haruka hole 6a.

Flywheel magneto 30 and first train vJ machine 2 are placed at the transfer station 31.
You can get 9. When starting 81 open 31, start switch 1 switch 3
When you close 5, lil! The starter motor 29 is driven by the battery 36 . A known ignition circuit unit 32 is connected to the primary coil 30a of the flywheel mag support 30,
By the signal of the ignition circuit unit 32, the secondary coil 30b
The point at which high voltage is applied to the ignition plug 40 is controlled. The current in the primary coil 30 is rectified by a diode 34 to charge a power supply battery 36.

Metering! 26 is the passage 11, the connection 17, the valve of the electromagnetic on-off valve C, and the aforementioned fuel reservoir via the passage 11! 10. lf @ control circuit M37 of on-off valve C is if switch 7
1. It is connected to the power source battery 36 via a switch 33a that is interlocked with the stop switch 33.

FIG. 2 is an electric circuit diagram of the starting fuel supply system. As shown in the left half of FIG.
A diode 34 is connected to the li source battery 36. A stop switch 33 for stopping the 'a function 31 is connected between both terminals of the spark plug 40.

As shown in the right half of FIG. 2, a control circuit 37 for the electromagnetic on-off valve C is configured. 35 is a starting switch, 29 is a starting motor, C is an electromagnetic on-off valve, and 71 is a temperature switch made of a bimetal or the like that senses the engine wall temperature or ambient temperature. )
The circuit is closed when the following conditions occur, while the circuit is opened when the value exceeds a predetermined value, and the control circuit 37 is inactivated. 33a is a switch interlocked with the stop switch 33, 43-47.49-5
1 is a resistor, 42 is a Zener diode, 41.54 is a capacitor, 48.52 is a transistor, and 53.56 is a diode.

Next, the operation of the starting fuel supply system according to the present invention will be explained. When the starting switch 35 is closed, the starting motor 29
is rotated, the flywheel is rotated together with the crankshaft of the engine 31, an induced current flows through the primary coil 30a of the flywheel magneto 30, and 2
The induced voltage of the 61st coil 30a where a high voltage is applied from the secondary coil 30b to both terminals of the ignition plug 40 is III#3
1 is very low when being driven by the motor 29, and becomes high when the engine 31 is started and reaches idle rotation.

When the ambient temperature of the engine is lower than a predetermined value, the temperature switch 71 is closed. When the starting switch 35 is closed, the starting motor 29 rotates the 1IWA 31. However, 1
The voltage of the primary coil 30a is extremely low until the first opening is started (complete explosion state). In other words, from the primary coil 30a to the diode 56 and the resistor 44, 45, 47
The current flowing through to the base of transistor 48 is very small and transistor 48 is non-conducting. At this time, a large amount of current flows from the power supply battery 36 to the transistor 52 through the switch 33a and the resistor 43°49.50, so that the transistor 52 becomes conductive and the power supply battery 3
6 to switch 33a, ilf switch 71.111!
The on-off valve C and the transistor 52 are energized, and the iI magneto-coulometric valve C is opened. The current flowing through the resistor 51 is set to be minute.

When the starting electric motor R29 is rotated, the diaphragm 28 of the fuel pump A is reciprocated up and down due to the pulsating pressure from the crank of the engine 31, and the fuel in the fuel tank 18 passes through the passage 55 and the check valve 27 and flows into the fuel pump A. The water is sucked into the pump 28a, and is supplied to the metering chamber 26 through the check valve 24, the passage 15, and the inflow valve 23. The fuel in the metering chamber 26 passes through the fuel jet 25 and flows from the fuel nozzle hole 6 to the calibration hole 8a.
supplied to At the same time, the fuel in the metering v26 is in the passage 11, compared to 17. The rich air-fuel mixture is sucked into the intake passage 9 through the electromagnetic on-off valve C1 passage 11 and the fuel reservoir chamber 10, and the rich mixture is drawn into the engine 3.
1, the engine 31 is started smoothly.

When the engine 31 reaches idle rotation, the primary coil 30a
As the voltage increases, more current flows to the base of transistor 48, causing transistor 48 to conduct. Along with this, the switch 33a and the resistor 43 are connected to the power supply battery 36.
．． 49, the transistor 48 is energized, the II current flowing through the resistor 50 to the base of the transistor 52 is drastically reduced, the transistor 52 becomes non-conductive, the electromagnetic shut-off valve C is no longer energized, the solenoid shut-off valve C is closed, and the metering 726
of fuel is no longer supplied to the fuel reservoir chamber 10.

However, since the starting fuel remaining in the porous member of the fuel reservoir chamber 10 continues to be sent to the intake passage 9 for a while, smooth warm-up of the engine 31 is maintained.

On the other hand, when restarting the engine immediately after stopping, or when the ambient temperature of III open 31 is high such as in the summer, the temperature switch 7]
opens and the control circuit 37 becomes inactive, so the electromagnetic on-off valve C remains closed.

No starting fuel is supplied, which solves the problem of unnecessary starting fuel being supplied and preventing smooth starting.

In the embodiment shown in FIGS. 3 and 4, instead of the temperature switch 71, an on-off valve 72 that is opened and closed by a spring made of a shape memory alloy as a thermally responsive body is provided in the middle of the starting fuel supply passage 11. It is something. As shown in FIG. 4(a), a valve hole 73 whose end is connected to the passage 11 is provided in the wall of the carburetor main body 4. In addition to housing the spring 76, the valve seat 77a
A cylindrical spring seat 77 having a cylindrical shape is screwed together to constitute the on-off valve 72, and a pipe serving as a passage 11 connecting to the electromagnetic on-off valve C is connected to the spring seat 77.

In this embodiment, when the ambient temperature of the engine 31 is below a predetermined value, as shown in FIG. Since it is pushed away from the valve seat 77a, when the engine 31 is started, the fuel in the metering to 26 passes through the passage 11, the valve 17, the electromagnetic on-off valve C, the on-off valve 72, the passage 11, and the fuel storage chamber 10. It is supplied to the intake passage 9.

When the ambient temperature of III is above the predetermined fi1,
As shown in b), the shape memory alloy spring 74 is stretched;
Ball 75 is pressed against valve seat 77a against the force of spring 76. Even if the electromagnetic on-off valve C opens with the engine starting operation, the R closing valve 72 is closed, so starting fuel is not supplied.

In the embodiment shown in FIG.
It was placed in the middle of . When the ambient temperature of the engine is below a predetermined value, the wax filled in the cylinder contracts,
A valve body 79 is retracted from the passage 11 together with a not-shown histone to open the passage 11. When the ambient salinity at III-open is higher than a predetermined value, the wax expands and the valve body 79a protrudes together with the piston into the passage 11 to block the passage 11. For example, when restarting the engine immediately after stopping it,
No starting fuel is supplied.

[Effects of the Invention] As described above, the present invention is characterized in that the electromagnetic on-off valve provided in the starting fuel supply passage connecting the fuel chamber of the carburetor and the intake passage is activated by the output signal of the primary coil of the flywheel magneto of the internal combustion engine. When starting fuel is supplied to the carburetor, either the energizing circuit of the electromagnetic on-off valve is equipped with a temperature switch that opens when the ambient temperature of the engine is above a predetermined value, or the starting fuel supply passage is equipped with a temperature switch that opens when the ambient salinity of the engine is at a predetermined value. Since it is equipped with an on-off valve that is closed by a heat-responsive body at the above times, when the engine is started and the ambient temperature of the engine is below a predetermined value, the electromagnetic on-off valve and the on-off valve in the starting fuel supply passage are opened and vaporized. Since the fuel in the fuel chamber of the engine is sucked into the intake passage via the starting fuel supply passage, a rich air-fuel mixture is supplied to the engine, and the engine can be started smoothly.

On the other hand, when the ambient temperature of the engine is above a predetermined temperature, such as when restarting the engine immediately after stopping, the electromagnetic on-off valve or on-off valve closes and the starting fuel supply passage is cut off, so starting fuel is not supplied. As mentioned above, starting fuel is automatically supplied or not supplied depending on the engine conditions, making the starting operation easy and easy to operate. The engine can be started smoothly at all times, not only when the engine is started, but also when the engine is frequently stopped and restarted.

[Brief explanation of drawings]

FIG. 1 is a side view sectional view showing a schematic configuration of a starting fuel supply device for a carburetor according to a first embodiment of the present invention, FIG. 2 is an electric circuit diagram of the starting fuel supply device, and FIG. 3 is a diagram of the present invention. FIG. 4 is a side sectional view of the carburetor starting fuel supply device according to the second embodiment of
Figures (a) and (b) are side sectional views showing the opening and closing states of the on-off valve of the device, and Fig. 5 is a side sectional view of essential parts of a carburetor starting fuel supply device according to a third embodiment of the present invention. It is. A: Fuel pump C: Electromagnetic r! @Valve closed 1; Carburetor 9;
Intake passage 11: Starting fuel supply passage 18: Fuel tank 26: Metering chamber (fuel tank 29: Starting motor 3
o: Flywheel magneto 30a: Primary coil 7
1: Temperature switch 72° 79: Open/close valve 74: Spring (
Shape memory alloy) 76 spring 78: Thermo wax

Claims (3)

[Claims] (1) In a starting fuel supply system for a carburetor in which an electromagnetic on-off valve provided in a starting fuel supply passage connecting the fuel chamber of the carburetor and an intake passage is activated by an output signal from the primary coil of a flywheel magneto of an internal combustion engine. A starting fuel supply device for a carburetor, characterized in that the energizing circuit of the electromagnetic on-off valve is equipped with a temperature switch that opens when the ambient temperature of the engine is above a predetermined value. (2) In a starting fuel supply system for a carburetor in which the electromagnetic on-off valve provided in the starting fuel supply passage connecting the fuel chamber of the carburetor and the intake passage is activated by the output signal of the primary coil of the flywheel magneto of the internal combustion engine. A starting fuel supply device for a carburetor, characterized in that a starting fuel supply passage is provided with an on-off valve that is closed by a thermally responsive body when the ambient temperature of the engine is above a predetermined value. (3) Claim (2) in which the thermally responsive body is composed of any one of bimetal, shape memory alloy, and thermowax.
) The starting fuel supply device for a carburetor described in ).