JPS5847258Y2 - Stop switch circuit in ignition system for internal combustion engine - Google Patents

Description

[Detailed description of the invention] The present invention relates to a stop switch circuit installed in a non-contact ignition device for internal combustion engines using an external trigger method.
The object of the present invention is to safely and reliably stop an internal combustion engine with a simple button operation, and to automatically return the internal combustion engine to a state in which it can be restarted after a predetermined period of time after stopping the internal combustion engine.

Generally, an ordinary changeover switch is used as the stop switch for an internal combustion engine. To stop the internal combustion engine, turn the stop switch to the OFF side and leave the switch in the same state until the internal combustion engine has completely stopped. It was necessary to hold the switch and turn the switch on when starting it up.

By the way, this stop switch is generally located far away from the operating device (for example, the steering wheel or handle) of the machine to which the internal combustion engine is attached, so it may suddenly change from a full load state to a no load state, etc. If the rotational speed of the internal combustion engine suddenly becomes overspeed due to a cause of I couldn't make it stop.

For this reason, this type of internal combustion engine is usually provided with an emergency safety stop switch in case of overspeeding.

Conventionally, this type of safety stop switch short-circuited the ignition coil of the ignition device when the stop switch was operated.
This short circuit of the ignition coil prevents spark discharge from occurring at the plug.

A conventional safety stop switch that shorts out this ignition coil is
It is true that it is possible to reliably prevent the ignition device from igniting, but on the other hand, since it is necessary to handle extremely large values of current and voltage, the capacity required for the contact as a switch is extremely large. Therefore, the available switches had to be large and expensive.

Moreover, once the ignition coil is short-circuited, the conventional safety stop switch described above must maintain its switched state for the required time, so it is natural that the conventional switch structure should be used. For this reason, many accidents occur in which the engine cannot be restarted due to forgetting to return the safety stop switch to its original position, making handling of the internal combustion engine troublesome.

The present invention was devised in order to eliminate the drawbacks of the conventional examples described above, and in a non-contact ignition device for internal combustion engines using an external trigger method, the trigger coil is short-circuited for a predetermined period of time by a simple push button operation. The ignition device is configured to stop the ignition operation during a short-circuit of the trigger coil.An embodiment of the present invention will be described below with reference to the drawings.

The stop switch circuit according to the present invention is used in an external trigger type non-contact ignition device for an internal combustion engine, and the reverse voltage induced in the trigger coil TC is activated by a single touch of the stop switch S having a push button structure. The capacitor C is charged by the switch operation, and the planar N-gate thyristor PUT connected in parallel with the trigger coil TC is turned on by the charging voltage of the capacitor C during the discharging time of the capacitor C to keep the trigger coil TC short-circuited. It is something to do.

That is, when a forward voltage is induced in the trigger coil TC in parallel with the trigger coil TC, the trigger coil T
A planar type N-gate thyristor PUT is connected between its anode and cathode in a posture in which both terminals of C are short-circuited, and a planar type N-gate thyristor PUT is connected in parallel with a trigger coil TC, and an induced voltage is applied to this trigger coil TC. A charging circuit having a stop switch S is connected to charge the reverse voltage to the capacitor C.
The negative pole side of the thyristor PUT is connected to the gate of the planar N-gate thyristor PUT via a resistor R2.

The charging circuit having the stop switch S for the capacitor C only needs to have a circuit configuration that can charge the reverse voltage induced in the trigger coil TC when the stop switch S is turned on. Capacitor C and diode DJ that regulates the direction of charging current
A stop switch S having a push button structure is connected in series to a series circuit of the resistor R1 and a resistor R1 for setting the charging voltage to the capacitor C.

Note that the resistor R2 connected to the gate of the planar N-gate thyristor PUT is for biasing the gate of the planar N-gate thyristor PUT negatively with respect to the anode by the charging voltage of the capacitor C.

Further, the diode D2 is used for rectification to send only the trigger pulse in the forward direction from the trigger coil TC to the ignition device.

Since the present invention has the above-described configuration, during operation of the internal combustion engine, only the trigger pulse, which is a forward voltage induced in the trigger coil TC, is sent to the ignition device through the diode D2. , normal ignition operation takes place.

In this state, if it is desired to stop the operation of the internal combustion engine because the internal combustion engine is in an overspeed state, etc., the stop switch S, which has a push button structure, is turned on.

The switch-on operation of the stop switch S may be for a short period of time on the order of milliseconds, and after this switch-on operation, the stop switch S automatically returns to the original switch-off state.

In any case, when the stop switch S is switched on, the reverse voltage induced in the trigger coil TC during the extremely short period of time when the stop switch S is switched on is as follows: trigger coil TC → stop switch S → capacitor C → The capacitor C is charged by the amount set by the resistor R1 along the path from the diode D1 to the trigger coil TC.

When the capacitor C is charged with a reverse voltage, the potential of the negative pole of the capacitor C is applied to the gate of the planar N-gate thyristor PUT via the resistor R2, and the gate of the planar N-gate thyristor PUT is connected to the anode. to negative bias and trigger the planar N-gate thyristor PUT.

When a forward voltage, that is, a normal trigger pulse, is induced in the trigger coil TC by the trigger of this planar type N-gate thyristor PUT, this trigger coil TC
The conduction of the planar N-gate thyristor PUT causes its terminals to be short-circuited. Therefore, no trigger pulse is applied to the ignition device, and ignition cannot be performed, so the internal combustion engine Stop that operation.

The conduction of the planar N-gate thyristor PUT, which cuts the trigger pulse from the trigger coil TC to the ignition device, is maintained until the discharge of the capacitor C is completed.
and the time constant of the discharge circuit formed by both resistors R1+R2.

Therefore, the capacitance of this capacitor C and both resistances R1,
By appropriately setting the value of R2, it is possible to freely set the time period during which the internal combustion engine becomes inoperable when the stop switch S is pressed once.

For example, when this stop switch S is used to completely stop the internal combustion engine, the above-mentioned time constant is set to a relatively large value, and the stop switch S is set to a relatively large value when the internal combustion engine is overspeeding. When used to temporarily stop the operation of the internal combustion engine to prevent the engine from overspeeding when It can be restarted automatically while rotating due to inertia.

In any case, when the discharge of the capacitor C is completed, the planar type N-gate thyristor PUT returns to the cut-off state, and the forward voltage induced in the trigger coil TC can be applied to the ignition device again. It will return automatically.

In this way, the present invention aims to stop the operation of the internal combustion engine by short-circuiting the trigger coil TC of the external trigger type ignition system, so whether it is a stop switch S or a planar type N-gate thyristor. Since the power handled by the PUT is relatively small, inexpensive parts with small ratings can be used, and there is no risk of damage due to surges or the like.

In addition, the ignition device itself can be simply attached to an existing ignition device without any special modification, and the structure is simple, so it is easy to implement.

Furthermore, since the time period during which the internal combustion engine is held in an inoperative state can be freely set, the range of use as a safety switch circuit can be freely set depending on the model and requirements.

As is clear from the above explanation, the present invention has an extremely simple structure and can be manufactured at low cost. Furthermore, since it is attached to the trigger coil TC which generates small electric power, there is no risk of damage due to surges, etc. It has many excellent functions and effects, such as being extremely convenient to use because the stop time can be freely set, and the system automatically returns to a restartable state with a simple push button operation.

[Brief explanation of the drawing]

The drawing is an electrical connection diagram showing an embodiment of the present invention. Explanation of symbols, PUT: Planar type N-gate thyristor,
TC:) Riga coil, S Nistop switch, C: capacitor, D 1 + D 2: diode, R1, R
2: Resistance.

Claims (1)

[Scope of utility model registration request] A stop switch circuit that is attached to a non-contact ignition device for an internal combustion engine using an external trigger method, the stop switch circuit having a trigger coil TC.
A planar N-gate thyristor PUT is connected in parallel with the trigger coil TC in a position that short-circuits it when forward induced voltage is generated, and in parallel with the trigger coil TC, a capacitor C is charged with the reverse induced voltage of the trigger coil TC. A stop switch circuit in an ignition system for an internal combustion engine, in which a charging circuit having a stop switch S is connected, and the negative pole side of the capacitor C is connected to the gate of the planar N-gate thyristor PUT via a resistor R2. .