JPH0310384Y2 - - Google Patents

Description

[Detailed explanation of the idea] Technical field The present invention relates to an engine ignition system.

Background Art For example, if you want to start a large single-cylinder engine of 400 to 600 cc or more using a starter motor,
Due to the large compression pressure or cranking force, a large output torque is required from the starter motor.
Furthermore, the peak value of load torque is larger than that of a multi-cylinder engine of the same capacity. In order to start such a large single-cylinder engine, a large starter motor with a large output torque is required. However, since large starter motors are expensive, a method of decelerating the motor rotation using gears is also used to compensate for the lack of torque.

In the case of such a method using a reduction gear, since the cranking speed decreases, the cranking speed becomes the slowest when the crank angle is near TDC, and a trigger signal for generating an ignition pulse must be obtained near this point.

However, the amplitude of the rotational pulse synchronized with the engine rotation obtained from the pulser coil is proportional to the speed of the magnet pieces passing near the pulser coil, so when the cranking speed is reduced, the rotational pulse voltage decreases and the ignition starts. There is a problem in that a rotation pulse of sufficient amplitude cannot be obtained to activate the trigger signal generation circuit for this purpose.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an engine ignition device including a rotational pulse generation circuit that allows the trigger signal generation circuit to operate correctly even when the engine is started by low-speed cranking.

The engine ignition system according to the present invention is provided with a voltage superimposing means for superimposing a predetermined DC voltage only when the starter switch is activated in the current path through which the rotational pulse passes.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a charge-discharge type ignition device (CDI) including voltage superimposition means according to the present invention. That is, the exciter coil 1 generates an alternating current voltage in cooperation with a magnet (not shown) that responds to the rotation of the engine crankshaft, and this alternating voltage is rectified by diodes D ₁ and D ₂ and supplied to the capacitor C ₁ . be done. The charge charged in capacitor _C1 is
Due to conduction of the SCR, a discharge occurs through the primary coil of the ignition transformer 2, a high voltage is generated on the secondary side of the ignition transformer 2, and a spark is generated at the ignition plug 3.
The SCR is made conductive by a trigger signal from the trigger signal generation circuit 4. The trigger signal generating circuit 4 consists of transistors Q ₁ , Q ₂ and a diode D ₄ , and the emitter of the transistor Q ₁ is a diode D ₃ , a resistor R ₁ , and a diode D 4 .
The collector of _the transistor _Q1 is connected to the gate terminal of the SCR.The collector of the transistor _Q1 is connected to the gate terminal of the SCR.
The base of the transistor _Q1 is connected to the collector of the transistor _Q2 , and the rotating pulse generated in the pulser coil 5 is supplied between _the base and emitter of the transistor Q2 via the resistor _R3 .
The pulser coil 5 cooperates with a magnet piece that rotates in synchronization with the rotation of the engine crankshaft to generate the rotation pulse when the crank angle is near TDC. Note that the diode _D4 is provided to obtain a sufficient collector current when the transistor _Q2 is conductive.

The pulser coil 5 and the resistor _R3 form a rotational pulse generating means, but according to the present invention, DC voltage is also generated from the starter switch SW, battery B, and motor starter circuit of the starter motor M when the starter switch SW is on. A voltage relay circuit is provided to relay the voltage to the resistor _R3 . The voltage relay circuit consists of resistors R ₄ , R ₅ , capacitor C ₃ , and Zener diode ZD ₂ , and together with resistor R ₃ forms voltage superimposition means for superimposing a predetermined DC voltage (booster voltage) on the rotational pulse. .

This voltage superimposition means may be any circuit that applies a DC voltage V to the resistor _R3 when the starter switch SW is on, as shown in FIG.

Effects of the Invention As is clear from the above, in the engine ignition system according to the present invention, the rotation pulse generating means for generating a rotation pulse synchronized with the rotation of the crankshaft generates a predetermined magnitude in the rotation pulse when the starter switch is turned on. Since it includes a voltage superimposing means for superimposing the booster voltage of This makes it possible to make the transistors sufficiently conductive.

In other words, if the ignition device according to the present invention is used, it is possible to use a low-output starter motor for a large single-cylinder engine, thereby reducing costs.

Furthermore, when a kick start is performed, the voltage boost effect described above is not performed, and the engine is started only after sufficient engine rotation is given by the kick, so no reverse torque is generated.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an engine ignition system according to the present invention, and FIG. 2 is a circuit diagram for explaining the gist of the present invention. Explanation of symbols of main parts, 1... Exciter coil, 2... Ignition transformer, 3... Spark plug, 4
...Trigger signal generation circuit, 5...Pulser coil, M...Starter motor, SW...Starter switch.

Claims (1)

[Claims for Utility Model Registration] Rotation pulse generation means that generates a rotation pulse synchronized with engine rotation; a trigger signal generation circuit that conducts in response to the rotation pulse and generates a trigger signal; and an ignition pulse supply circuit that supplies ignition pulses to an ignition coil, wherein the rotational pulse generation means includes voltage superimposition means for superimposing a DC voltage on the rotational pulse when the starter switch is turned on. An engine ignition system featuring: