Patent ID: 6629520
Filing Date: 2003-10-07
Classification: F02P

Abstract:
An ignition apparatus for an internal combustion engine comprising:a DC power source unit; an ignition coil having a primary winding through which primary current flows upon application to the primary winding of power source voltage from the DC power source unit, and a secondary winding which forms a closed loop in cooperation with a spark plug attached to the internal combustion engine; switching means connected in series to the primary winding and adapted to interrupt and resume the primary current flowing through the primary winding; and ignition control means for outputting an ignition command signal for controlling ignition timing, the ignition command signal causing the switching means to interrupt and resume the primary current flowing through the primary winding in order to generate at the secondary winding high voltage for ignition to thereby cause the spark plug to generate spark discharge, characterized in that the ignition apparatus further comprises: spark-discharge duration time setting means for setting a spark-discharge duration time on the basis of operation conditions of the internal combustion engine, the spark-discharge duration time representing a period during which spark discharge of the spark plug is to be maintained; spark-discharge interruption control means for outputting a spark-discharge interruption command signal for controlling the spark-discharge duration time; a spark-discharge interruption circuit for resuming, after generation of spark discharge by the spark plug, supply of the primary current to the primary winding in accordance with the spark-discharge interruption command signal so as to interrupt the spark discharge; and energy control means for maintaining at a substantially constant level magnetic flux energy which accumulates in the ignition coil by supply of electricity to the primary winding by means of the ignition control means.