Abstract: An ignition system for a multi-cylinder internal combustion engine eliminates high-voltage cables and a mechanical distributor in order to reduce electrical power losses due to joule effect caused mainly by the high voltage circuit, comprises a plurality of ignition coils and plugs, one provided for each cylinder, a distribution unit for distributing advance-angle control signals into the respective cylinders, and a booster for boosting the supply voltage in order to reduce the size of the ignition coil, in addition to the conventional ignition system. Furthermore, the ignition coil can be built integrally with the ignition plug for eliminating high-voltage cables connected between coil and plug.

Abstract: An ignition system for an internal combustion engine having a plurality of engine cylinders, wherein ignition coil and spark plug are integrally assembled into each engine cylinder so as to eliminate an ignition energy transmission loss, a DC-DC converter for boosting a low DC voltage into a high DC voltage is provided for applying the high DC voltage into each secondary winding of the ignition coils for achieving an efficient ignition of air-fuel mixture, the application of the high DC voltage being enabled according to a particular engine operating condition, e.g., engine low speed and light engine load condition, and the ignition energy being varied according to an engine operating condition by changing the pulsewidth of the ignition pulse signal to be fed into a cylinder judging circuit which judges the spark plug to be ignited and distributes the ignition pulse signal into the related circuit of the corresponding ignition coil.