JPH0219592Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of an engine stop circuit used in a magneto-ignition engine.

In institutions that traditionally use magneto,
In order to stop a rotating engine, a method has been adopted that short-circuits the power generation output using a self-resetting push button switch, but if the operator's hand leaves the button while the button is being operated, the engine will return to normal operation. When the vehicle returned to operation, it operated against the operator's will, resulting in a defect that resulted in a dangerous situation. Also, if a tumbler switch is used instead of a self-returning pushbutton switch, the above defects can be eliminated, but after the engine has stopped,
There were cases where the operator forgot to reset the tumbler switch, causing the engine to fail when restarted.

This device makes the semiconductor switching element with a control pole conductive by operating a self-returning stop switch once, and then uses a self-holding circuit to reliably hold the semiconductor switching element in the conductive state for a predetermined period of time to ensure power generation. By short-circuiting the output of the coil, the ignition of the engine is stopped continuously,
The engine stop circuit automatically releases the self-holding function after the engine is stopped in preparation for restarting the engine.

The following description will be made based on the embodiments shown in the drawings. In the figure, 1 is a magneto ignition circuit (not shown) of the engine, and 11 is its power generation coil, which generates positive and negative alternating current outputs in synchronization with engine rotation. 12 is a circuit breaker contact, 13 is a capacitor, and 14 is an ignition coil. 2 is a self-resetting stop switch; 3 is a stop circuit that is activated by the closing signal of stop switch 2 to stop the ignition of the engine;
31 is the diode, 32 and 36 are resistors, 3
3 is a capacitor that constitutes a self-holding circuit with a resistor 32, and 34 is a thyristor that is a semiconductor switching element with a control pole. Reference numeral 35 denotes a resistor forming a self-trigger means, which connects the connection point between the stop switch 2 and the thyristor 34, and the connection point between the stop switch 2 and the thyristor 34.
and the cathode of 4.

The operation of the device configured as described above will be explained. As the engine rotates, the generator coil 11 of the magneto ignition circuit 1 generates positive and negative alternating current output, and by interrupting this generated output with the interrupter contact 12, an ignition spark is obtained on the secondary side of the ignition coil 14. is well known. Now, while the engine is rotating, after the stop switch 2 is closed to stop the engine, the interrupter contact 12 is turned off at the engine ignition timing, and when a voltage of the polarity shown is generated across the interrupter contact 12, the thyristor 34 is turned off. Since a gate current is applied to the gate, the thyristor 34 which was in the off state is turned on, and the power of the generating coil 11 is consumed by the resistor 36, so that no ignition spark is generated on the secondary side of the ignition coil 14.

When the polarity of the voltage generated from the generator coil 11 becomes opposite to the above polarity, the current through the diode 31 disappears, but the capacitor is charged to the polarity shown by the voltage of the polarity shown during engine operation and generated at the interrupter contact 12. 33 is passed through the resistor 32 to the anode current (holding current) of the thyristor 34.
Since the anode current of the thyristor 34 does not become lower than the holding current, the thyristor 34 continues to be on until the voltage polarity is reversed, and the generating coil 11 remains on regardless of whether the stop switch 2 is opened or closed, that is, even if it is in the open circuit state. The power generation output continues to be short-circuited via the thyristor 34, and the engine continues to be unable to ignite.

Note that the short circuit current caused by the thyristor 34 is normally several
There is 100mA, and capacitor 33 is reliably charged.
On the other hand, since the holding current of the thyristor 34 is several mA, self-holding is reliably performed.

Furthermore, when the engine is stopped, the generator coil 11 does not generate electricity and the charge in the capacitor 33 is completely discharged, so that the engine can be restarted immediately when the engine is started next time.

Furthermore, in this invention, by selecting the values of the resistors 35 and 36, even if the thyristor 34 fails and becomes OFF, the engine can be stopped by continuing to operate the stop switch 2 in the same way as before. Therefore, even if the thyristor fails in the off state, the engine will not be impossible to stop.

As described above, in this invention, the power generation output of the power generation coil 11 is continued to be short-circuited by the thyristor 34 until it is certain that the engine cannot ignite.
The time to apply a holding current to this thyristor 34 and keep it in the on state is determined by the capacitor 33.
The discharge time constant is determined by the discharge time constant of the engine, and this time is set to be sufficient for the engine to become incapable of ignition. In short, the period in which the holding current is applied to the thyristor 34 only needs to be the period in which a power generation output of opposite polarity that is not used for ignition is generated. Further, in order to increase the charging time constant of the capacitor 33, it is also possible to connect a diode in parallel to the resistor 32. In this way, ignition can be prevented by keeping the short-circuit thyristor conductive using a self-holding circuit with a simple configuration, and even if the short-circuit thyristor remains off due to a failure, the stop switch can be continued to be pressed as before. This is a practically useful idea as it can prevent ignition.

Further, instead of the ignition circuit using the interrupter contact 12, a semiconductor switching element such as a transistor may be used.

[Brief explanation of the drawing]

The figure is an electrical circuit diagram showing an embodiment of this invention. In the figure, 1 is a magneto ignition circuit, 11 is a generator coil, 12 is a circuit breaker contact, 13 and 33 are capacitors, 14 is an ignition coil, 2 is a stop switch, 3 is a stop circuit, 31 is a diode, 3
2 and 36 are resistors, 34 is a thyristor, and 35 is a resistor serving as self-trigger means.

Claims (1)

[Scope of utility model registration request] An ignition circuit that controls the power generation output of a power generation coil having a magneto to induce an ignition voltage, a thyristor connected to both ends of the power generation coil to short-circuit the power generation output, and a connection between the gate of the thyristor and one end of the power generation coil. a self-returning stop switch connected between the stop switch and the gate, a first resistor connected between the connection point between the stop switch and the gate and the cathode of the thyristor, and the cathode of the thyristor and the other end of the generating coil. a second resistor connected between the thyristor, a connection point between the anode of the thyristor and one end of the power generating coil, and a third resistor and a capacitor connected in series between the other end of the power generating coil; The self-holding circuit includes a self-holding circuit consisting of a circuit, and after the stop switch makes the thyristor conductive to short-circuit the power generation output, the self-holding circuit applies a holding current to the thyristor to keep the thyristor in a conductive state for a predetermined period of time. An engine stop circuit characterized by: