JP2580267Y2 - Load drive circuit for magneto power supply for ignition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a load driving circuit for a magneto power supply for ignition that drives an electric load such as a warning light without stopping an engine using a magnet as a power supply.

[Problems to be Solved by Conventional Techniques and Inventions] Conventionally, general-purpose engines and the like are disclosed in, for example, JP-A-62-2637.
As disclosed in Japanese Patent Publication No. 9, when an abnormality such as the oil level being below the reference oil level is detected, the engine is stopped by an oil level warning circuit connected to the ignition device.

Japanese Patent Application Laid-Open No. Sho 62-121833 discloses a technique for issuing a warning when an engine abnormality is detected. In this prior art, a warning device is connected in series to an engine abnormality detection circuit. Power is supplied from the ignition circuit side, and when an abnormality of the engine is detected, an electric load such as a warning light including a light emitting diode (LED) is driven and the engine is stopped.

In other words, many small engines such as general-purpose engines supply ignition power from the magneto to the ignition system.
When D is turned on, the current required to turn on the LED is relatively large, so the current supplied to the ignition system decreases. Therefore, the ignition energy generated in the ignition system is reduced, the combustion state is deteriorated, and the engine hunts.

Therefore, conventionally, for example, when an abnormality of the engine is detected, it is necessary to stop the engine at the same time as turning on the LED.

However, to drive an electric load such as the LED without stopping the engine, such as a pre-warning when there is enough time before a problem occurs even if the oil level falls below In addition to the ignition power source, a separate power source must be provided by providing an ignition coil in the magneto or by mounting a battery, thereby increasing costs.

[Purpose of the Invention] The present invention has been made in view of the above circumstances, and has a load drive of an ignition magneto power supply capable of driving an electric load without requiring a separate power supply and without affecting ignition performance. It is intended to provide a circuit.

[Means for Solving the Problems] The load drive circuit of the magneto power supply for ignition according to the present invention comprises:
The anode side is connected to the ground end of the primary side of the ignition coil,
A first thyristor having a cathode connected via an electric load to a primary power supply end of the ignition coil to which ignition power is supplied from an ignition magneto power supply; and a first terminal for igniting the ignition coil. A capacitor having a power supply terminal connected thereto, a gate terminal of the first thyristor connected to a second terminal, and a power supply terminal for ignition of the ignition coil connected via a first voltage dividing resistor; When the anode side is connected to the second terminal of the capacitor via a second voltage dividing resistor, the cathode side is connected to the ground terminal on the primary side of the ignition coil, and an external signal is output when the ignition magneto power supply has a positive polarity. And the second terminal side of the capacitor is turned on by a forward current flowing from the ignition magneto power supply through the first voltage dividing resistor and the second voltage dividing resistor. The capacitor is charged to a voltage determined by a second voltage-dividing resistor, turned off when the ignition magneto power supply has a negative polarity, and the second terminal side of the capacitor is connected to the second terminal side by the reverse current flowing from the ignition magneto power supply. 2 and a voltage on the second terminal side of the capacitor until the voltage level at which the first thyristor turns on after the discharge of the spark plug connected to the secondary side of the ignition coil. And a second thyristor for increasing the voltage.

[Operation] In the load drive circuit of the ignition magneto power supply according to the present invention, when the ignition magneto power supply has a positive polarity and the second thyristor is turned on by an external signal, the first voltage dividing resistance is supplied from the ignition magneto power supply. And a forward current flowing through the second voltage-dividing resistor charges the second terminal side of the capacitor to a voltage determined by the second voltage-dividing resistor, then turns to the polarity of the ignition magneto power supply to turn off the second thyristor. Then, the second terminal side of the capacitor is further charged by the reverse current flowing when the second thyristor is turned off with the time constant of the capacitor and the second voltage-dividing resistor, and the voltage of the second terminal side of the capacitor is changed. That is, the gate voltage of the first thyristor turns on after the discharge of the spark plug connected to the secondary side of the ignition coil occurs. Voltage level. As a result, the first thyristor is turned on after the discharge of the spark plug occurs, and current is supplied from the ignition magneto power supply to the electric load without stopping the engine.

[Embodiment of the present invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 shows an embodiment of the present invention, FIG. 1 is a circuit diagram, and FIG. 2 is a waveform diagram of an ignition magneto power supply.

(Configuration) In the drawing, reference numeral 1 denotes a well-known ignition circuit of a transistor type.
Is supplied. A primary side of an ignition coil 3 is connected to the ignition circuit 1, and an ignition plug 4 is connected to a secondary side of the ignition coil 3.

A load driving circuit 5 is connected to the primary side of the ignition coil 3 in parallel with the ignition circuit 1, and the load driving circuit 5 includes a load driving unit 5a and a trigger unit 5b.

The ignition circuit 1 includes an ignition power supply VIG and a ground G.
Are connected in series between the resistors R1 and R2, and the base of the NPN transistor TR1 is connected to the connection point between the resistors R1 and R2.

The transistor TR1 has an emitter connected to the ignition power supply V.
The collector is connected to IG, and the collector is connected to ground G via a resistor R3. Further, the base of an NPN power transistor TR2 is connected to the collector of the transistor TR1. The power transistor TR2 has an emitter connected to the ignition power supply VIG and a collector connected to the ground G.

On the other hand, in the load drive unit 5a of the load drive circuit 5, the cathode of the thyristor SCR1 (first thyristor) is connected to the ignition power supply VIG via the resistor R4, and the anode of the thyristor SCR1 is connected to the ground G. It is connected.

An electric load such as a light emitting diode LED is connected to the cathode of the thyristor SCR1 via a diode D1 and a resistor R5, and the cathode of the light emitting diode LED is connected to the ignition power supply VIG. Above ignition power supply VIG
The capacitor C1 is connected between the light emitting diode LED and the resistor R5 in parallel with the cathode of the diode D1.

The trigger section 5b of the load drive circuit 5 includes a trigger thyristor SCR2 (second terminal) having a first terminal connected to the ignition power supply VIG via a resistor R6 and a second terminal connected to the second terminal of the capacitor C2. Of the trigger thyristor SCR2 is connected to the ground G
Grounded.

The connection point between the capacitor C2 and the resistor R6 is a resistor.
One end of R7 is connected, and the gate of the thyristor SCR1 of the load drive unit 5a is connected.The other end of the resistor R7 is connected to the other end of a capacitor C3 that connects one end to the ignition power supply VIG. It is connected.

When the trigger signal generation source 5c is formed by the capacitors C2 and C3 and the resistors R6 and R7, and the terminal voltage of the capacitor C2 reaches the gate turn-on voltage of the thyristor SCR1 with a predetermined time constant, the thyristor SCR1 is turned off. Fired.

Further, the connection point between the capacitor C3 and the resistor R7 is connected to the cathode of a diode D2.
The anode of D2 is connected to the cathode of the thyristor SCR1 of the load driver 5a.

The gate of the trigger thyristor SCR2 is connected to a signal input terminal SIN via a resistor R8. By inputting a high-level signal between the signal input terminal SIN and the ground G, the load drive circuit 5 to drive an electric load such as the light emitting diode LED.

(Operation) Next, the operation of the embodiment having the above configuration will be described.

While the engine is operating, the ignition power supply VIG is supplied from the magneto 2 as an AC output synchronized with the engine rotation, and a primary current is supplied to the ignition coil 3 by the AC output.

Next, when the output voltage from the magneto 2 goes to the minus side, the power transistor TR2 is first turned on by the resistor R3 of the ignition circuit 1, and the transistor is turned on by the resistors R1 and R2.
A base voltage is applied to TR1, and at a predetermined timing, for example, BTDC20 °, the transistor TR1
Reach level to turn on. Then, this transistor TR
1 turns on at the same time as the power transistor TR2 turns off, and the current from the magneto 2 flows into the power transistor TR2.
Cut off by

As a result, a voltage having the waveform shown in FIG. 2 is generated on the primary side of the ignition coil 3, and the spark plug 4 is sparked by the discharge voltage induced on the secondary side of the ignition coil 3.

The ignition power supply VIG is applied to the load drive circuit 5, where, for example, the oil level of the engine falls below the reference oil level, and a high-level detection signal from a control device (not shown) is output from the load drive circuit 5. When input to the input terminal SIN, the trigger thyristor SCR2 of the trigger section 5b is turned on, and when the potential of the ignition power supply VIG is higher than the ground G, the resistor R4, the diode D2, the resistor R7, and the resistor R6
A forward current flows through the trigger thyristor SCR2, and the voltage at the second terminal of the capacitor C2 is determined by the combined resistance of the resistors R4 and R7 as the first voltage dividing resistor and the resistor R6 as the second voltage dividing resistor. Is charged.

Next, when the polarity of the ignition power supply VIG is inverted and becomes lower than the ground G as shown in FIG. 2, a negative anode voltage is applied to the trigger thyristor SCR2, and the trigger thyristor SCR2 is turned off. At this time, a current reverse to the forward direction flows from the trigger thyristor SCR2 to the resistor R6 and the capacitor C2, and the capacitor C2 is charged. The reverse current flowing through the trigger thyristor SCR2 is a reverse current flowing in a process in which the trigger thyristor SCR2 recovers from a turn-on state to a turn-off reverse blocking state, and is generally called a reverse recovery current, and is referred to as a reverse blocking state. It becomes a relatively large current with respect to the minute reverse leakage current when it becomes. And the capacitor C2
When the terminal voltage (the voltage on the second terminal side) VC2, that is, the trigger signal to the thyristor SCR1 of the load driver 5a reaches the turn-on voltage, the charge stored in the capacitor C2 flows to the gate of the thyristor SCR1 and Thyristor SCR1
Turns on.

At this time, the timing at which the terminal voltage VC2 of the capacitor C2, that is, the gate voltage of the thyristor SCR1 reaches the turn-on voltage depends on the charging time constant TO of the resistor R6 and the capacitor C2 and the waveform of the ignition power supply VIG shown in FIG. Medium, the first ignition region, that is, the timing of transition from the capacity discharge region TIGC where discharge is first performed in the ignition plug 4 by the secondary induction voltage generated in the ignition coil 3 to the induction discharge region TIGL due to the next induction component. Become.

That is, the current supply to the light emitting diode LED is performed at the time when the arc discharge of the ignition plug 4 ends and the glow discharge is started.
The LED is turned on when ignition by the discharge of the ignition plug 4 has already been completed.

Thereby, the thyristor SCR1 is connected to the ignition coil 3
Is fired later than the initial stage of secondary voltage generation, from the ignition power supply VIG via the thyristor SCR1, the diode D1,
A current flows through the path of the resistor R5 and the light emitting diode LED, and the light emitting diode LED is turned on.
C3 is charged.

Usually, for general-purpose engines, for example, BTDC 20 °
Ignition is performed at a fixed ignition timing such as
It was confirmed that there was no decrease in ignition performance in the advanced angle range up to DC23 °, and there was no effect on the output performance of the engine.

Then, when the ignition power supply VIG becomes higher than the ground G again, the thyristor SCR1 is turned off, and a discharge current flows from the capacitor C1 to the light emitting diode LED. Therefore, when the cycle of the polarity change of the ignition power supply VIG is long, that is, even when the engine speed is low, the light emitting diode LED is turned on by the discharge current from the capacitor C1, and the thyristor SCR1 is turned off. The turn-off time during the period is reduced.

Further, when the thyristor SCR1 is turned off, at the same time, a discharge current flows from the capacitor C3 charged by the ignition power supply VIG via a resistor R7, and charges the capacitor C2.

The capacitor C2 is charged with a time constant T1 of R7 × C2,
The terminal voltage VC of the capacitor C2 is determined by the time constant T1.
2, that is, the timing at which the gate voltage of the thyristor SCR1 reaches the turn-on voltage depends on the capacity discharge region described above.
It is time to shift from TIGC to the induction discharge region TIGL.

Therefore, once the thyristor SCR1 is fired, the thyristor SCR1 turns on and off the trigger thyristor SCR2.
It does not depend on F, and even if the polarity of the ignition power supply VIG changes and turns off, the capacitors C2 and C3 re-ignite with the time constant T1, and the light emitting diode LED is turned on without lowering the ignition performance. Keep on lighting.

Thus, for example, by setting the oil detection oil level and the like with a margin in advance, the light emitting diode LED can be turned on without stopping the engine, and a warning can be given in advance.

The present invention is not limited to the embodiment, and the electric load in the load driving circuit 5 may be not only the light emitting diode LED but also an equivalent load current such as an hour meter.

[Effects of the Invention] As described above, according to the present invention, the cost can be reduced by driving the electric load without requiring a separate power supply for the ignition magneto power supply. Since the first thyristor is turned on at the timing after the discharge of the spark plug occurs, deterioration of the ignition performance is prevented, and malfunction such as hunting does not occur in the engine. Therefore, for example, by detecting the state of the engine and inputting it as an external signal, it is possible to perform an advance warning or display without stopping the engine.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, and FIG.
FIG. 2 is a waveform diagram of the ignition magneto power supply. 2: Magneto 3: Ignition coil SCR1: Thyristor (first thyristor) SCR2: Trigger thyristor (second thyristor) C2: Capacitor R4, R7: Resistance (first voltage dividing resistor) R6: Resistance (second voltage dividing resistor) VIG… Ignition power supply LED… Light emitting diode (electric load)

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02P 1/00-3/12 F02P 9/00-17/00

Claims (1)

(57) [Scope of request for utility model registration] An anode is connected to a ground terminal on a primary side of an ignition coil, and a cathode side is connected via an electric load to a power supply terminal on a primary side of the ignition coil to which ignition power is supplied from a magnet magneto power supply. A first thyristor, a first terminal connected to an ignition power supply end of the ignition coil, a second terminal connected to a gate side of the first thyristor, and a first voltage dividing resistor. A capacitor to which an ignition power supply terminal of the ignition coil is connected via a first terminal; and an anode side connected to a second terminal of the capacitor via a second voltage-dividing resistor, while grounding the primary side of the ignition coil. The cathode side is connected to the end, and when the ignition magneto power supply has a positive polarity, it is turned on by an external signal, and the ignition magneto power supply supplies the first voltage-dividing resistor and the second voltage-dividing resistor. Charging the second terminal side of the capacitor to a voltage determined by the second voltage-dividing resistor, turning off the ignition magneto power supply when the polarity becomes negative, and turning off the ignition magneto power supply. The reverse current flowing from the
Is charged through the second voltage-dividing resistor, and the second thyristor is turned on to a voltage level at which the first thyristor turns on after the discharge of the spark plug connected to the secondary side of the ignition coil. And a second thyristor for increasing the voltage on the terminal side of the load drive circuit for the magneto magneto power supply for ignition.