JPS6133993B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an internal combustion engine stopping device.

Among internal combustion engines, those that do not have a battery installed, especially agricultural machinery, etc., are usually connected to have an ignition device that operates constantly for ease of operation. The engine had been stopped due to a short circuit or other such actuation of the stop switch.

The stop switch is typically a pushbutton switch that is closed or opened only when actuated, or remains closed or open. It consisted of a snap switch, etc.

Stopping the internal combustion engine using the stop switch described above has the following drawbacks.

In other words, with a push button switch, it is necessary to keep pressing the button until the engine completely stops. Especially in agricultural general-purpose engines, etc., because the inertia force is large, it takes a long time until the engine stops, and during that time, There was a problem where the engine restarted when the push button switch was released.

Furthermore, in the case of a snap switch, if the switch is operated when the engine is stopped, it is necessary to open the switch after the engine has stopped in order to maintain the stopped state. In this case, if you forget to open the switch after stopping, the ignition system will not work when the engine is restarted, so the engine will not start, and you will be unable to start the engine without realizing that you forgot to operate the switch. This caused problems such as fuel adhering to the spark plug, making it impossible to start the engine.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and uses a self-returning stop switch to ensure that the engine can be stopped, and after the engine has stopped, it cannot be restarted. The purpose of this invention is to provide an internal combustion engine stop device that can be operated without any problems.

An embodiment of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is an ignition coil installed in the magnet generator, and 1a is 1 which also serves as a generating coil.
The secondary coil 1b is a secondary coil connected to the spark plug P. 2 is an interrupter that opens and closes in synchronization with the engine's ignition timing, 3 is a capacitor that eliminates the arc generated between the contacts of interrupter 2, and 4 is a generator coil 2.
5 is a Zener diode that supplies base current to transistor 4; 6 is a capacitor that serves as a power source for the self-holding circuit; and 7 is a resistor that forms a discharge path for capacitor 6. 8, whose resistance value is set relatively large, supplies the base current to the transistor 4, and connects the capacitor 6 and resistor 7.
A thyristor 9 is a second semiconductor switching element forming a self-holding circuit.
A diode 10, which is connected to the capacitor 6 from its cathode and is used to charge the capacitor 6, is connected to a self-resetting stop switch 11, and is a diode that supplies base current to the transistor 4 when the stop switch 11 is closed.

To explain the ignition operation, in FIG. 2a, the dotted line represents the electromotive force waveform of the generating coil 1a, and the solid line represents the operating voltage waveform. In the figure, point A is the ignition timing of the engine, and is the open position of the interrupter that opens and closes in synchronization with the engine. The electromotive force generated in the generator coil 1a is short-circuited by the interrupter 2, and a short-circuit current flows. At point A of the ignition timing, the interrupter 2 opens, cutting off the short-circuit current, causing a sudden change in magnetic flux in the generator coil 1a, generating an induced voltage, which is converted to the secondary coil 1b and becomes the ignition voltage to ignite. Discharge to plug P.

Next, the stopping operation of the engine will be explained. When the pushbutton switch 11 is pressed and closed, a constant voltage circuit consisting of the diode 10, the Zener diode 5, and the transistor 4 is formed. Here, the Zener voltage of the Zener diode 5 is 2
The voltage induced in the secondary coil 1b is set to such a low voltage that it does not discharge to the spark plug P. Therefore, as shown in FIG. 2b, even if the interrupter 2 opens and an induced voltage is generated, the voltage across the generator coil 1a is discharged to the spark plug P by the constant voltage circuit consisting of the Zener diode 5 and the transistor 4. It will not be maintained at any voltage.

Here, the capacitor 6 is connected in parallel to the Zener diode 5 and the transistor 4, and when the stop switch 11 is closed, the capacitor 6 receives the induced voltage of the generator coil 1a and is charged to the Zener voltage. This voltage is applied to the gate cathode of thyristor 8 and the resistor 7.
The thyristor 2 is discharged in the discharge circuit, and the thyristor 2 is made conductive. Even after the stop switch 11 is opened due to conduction of the thyristor 8, the base circuit of the transistor 4 consisting of the thyristor 8, the diode 9, and the Zener diode 5 is formed.
performs constant voltage operation, the generator coil 1a is maintained at the Zener voltage, and no ignition voltage is generated. That is,
The charging voltage of the capacitor 6 is as shown in Fig. 2c,
The thyristor 8 repeats charging and discharging in response to the induced voltage in the generator coil 1a generated when the interrupter 2 opens, and the thyristor 8 forms a self-holding circuit in cooperation with the capacitor 6 and the resistor 7 to maintain the conductive state.

Therefore, if the discharge time constants of the capacitor 6 and resistor 7 are set to a low rotational cycle that does not cause the engine to run, the self-holding circuit will remain in operation until the engine is stopped by operating the stop switch 11 while the engine is running. It works and there is no ignition voltage. here,
Since the induced voltage of the generating coil 1a is suppressed to below the Zener voltage by the transistor 4 and the Zener diode 5, the value of the register 7 is set to be large regardless of the induced voltage of the generating coil 1a, and the discharge time constant is set large. It is possible to operate the self-holding circuit reliably up to a low rotation period.

In the above embodiment, an ignition device having a mechanical interrupter 2 has been described, but an ignition device using a semiconductor switching element, such as a transistor, can have similar effects. Furthermore, the third
As shown in the figure, the transistor 4 used for the stop circuit of the present invention is replaced by the transistor 1 used for the ignition timing.
It is also possible to use both. In this case, the transistor 12 of the ignition device operates as a constant voltage circuit after cutting off the current flowing through the generating coil 1a. Further, although the transistor 4 is used in the constant voltage circuit, the same effect can be obtained even if a thyristor is used.
In this case, after the thyristor is turned on, short-circuit control is performed by the thyristor, but the self-holding circuit operates in the same way, so it has the same effect.

As described above, according to the present invention, the power for the self-holding circuit for stopping the engine is obtained from the induced voltage generated when the current in the generator coil is cut off, so that sufficient power supply voltage can be obtained even at extremely low rotational speeds. In addition, it is possible to set the discharge time constant of the self-holding circuit to a large value regardless of the suppression value of the induced voltage in the primary coil, and to operate the self-holding circuit reliably up to an extremely low rotation period. It is possible to obtain a highly reliable internal combustion engine stop device that can reliably stop an engine by operation.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing one embodiment of the present invention, Fig. 2 a, b, and c are waveform diagrams for explaining the circuit operation of Fig. 1, and Fig. 3 is another embodiment of the invention. FIG. 1 is an ignition coil, 1a is a primary coil, 1b is a secondary coil, 2 is an interrupter, 3 and 6 are capacitors,
4 and 12 are transistors, 5 is a Zener diode, 7 is a register, 8 is a thyristor, 9 and 10 are diodes, and 11 is a stop switch. In addition, in each figure,
The same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. An ignition coil that generates a secondary voltage for ignition when the primary current is cut off, a first semiconductor switching element connected in parallel to the primary coil of the ignition coil, the primary coil of the ignition coil, and a a second semiconductor switching element and a discharge resistor connected in parallel to the first semiconductor switching element and in series with each other; a control voltage is applied to a control pole of the second semiconductor switching element; a constant voltage element connected between a connection point between the second semiconductor switching element and the discharge resistor and a control pole of the first semiconductor switching element; An internal combustion engine stop device equipped with a self-resetting stop switch that forms a charging path.