IGNITION DEVICE IN INTERNAL-COMBUSTION ENGINE

PURPOSE:To aim at simplifying the arrangement of components and to realize the reduction of cost, by using an ignition coil which can produce power capable of generating dielectric breakdown voltage between the electrodes of an spark plug, and by arrnging such that a DC-DC converter may afford all sparkling energy. CONSTITUTION:A primary high voltage trans 15 in a condenser discharge contactless ignition unit (CDI) 14 of converter type is connected to one end of a primary coil 7a in an ultra-miniature ignition coil 7'. The anode side of a switching SCR 22 is connected to the other end of the primary coil 7a. A spark signal trans 21 is connected to the terminal of the SCR 22, and there is connected in the intermediate part thereof a microcomputer 26 to which a spark signal obtained in accordance with the outputs of a signal detector 24 and an intake air flowmeter 25 is applied. Meanwhile, one end of a secondary coil 7'b is connected to a center cord 9, and the other end of the coil 7'b is connected to a secondary high voltage trans 16 through a pi circuit or the like consisting of a connection discharge coil 20, a discharge condenser 19, a charge condenser 17 and a coil 18 of extremely low alternate current loss.