| 摘要 |
PURPOSE:To improve the startability of an engine and to stabilize its rotation at low speed by changing the turning on voltage of a semiconductor switching element in accordance with the output of a detecting means for the number of engine revolutions. CONSTITUTION:In the case where the number of engine revolutions at which the trigger level voltage of a thyristor 8 is changed over is denoted using N, and an engine rotates below the set number of revolution N, since a relation between one period t2 of an output voltage wave form of a signal coil 5 and its fixed period t1 is t2>t1, a transistor 30 has some turning on duration after it has been cut off. A capacitor 34 is therefore quickly charged to increase in its voltage up to a power source one, and its terminal voltage is applied to a transistor 37 to keep it in a turned on state. The trigger level voltage of the thyrister 8 therefore becomes low to cause the thyrister 8 to surely perform its turning on and cutting off actions even on a signal level at low speed rotation of the engine. Thus a fuel ignition can be surely performed even at the low speed rotation of the engine in a case of its starting up to improve its startability, and moreover an ignition timing can be exactly kept even during the rotational fluctuation of the engine at its low speed rotation to improve the rotational stability of the engine.
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