Ignition apparatus for internal combustion engine

Abstract

An ignition apparatus for internal combustion engine includes an ignition power unit 1A having a power transistor 14A for feeding and shutting off a primary current i1 to and from an ignition coil 13 and a control circuit 2 having a CPU 21 for calculating an ignition timing of an internal combustion engine and a feeding time of the primary current in accordance with an operating state D and outputting an ignition signal G to the power transistor, feeds and shuts off the primary current in response to an ignition signal Ga to generate a high-tension secondary voltage from the ignition coil. The power transistor has a characteristic for increasing a direct current amplifying ratio as a base to emitter voltage VBE between a base and emitter increases to suppress the rising-up of the primary current to thereby suppress a secondary voltage generated when the primary current starts to be fed. With this arrangement, the ignition apparatus for internal combustion engine can suppress malfunction when the ignition signal rises up without the use of a high-tension diode and realize cost reduction and miniaturization of the apparatus.

Dependencies are inferred from the claim text.