Ignition apparatus for internal combustion engine

Abstract

An ignition apparatus includes a blow-off determining unit 5b. The blow-off determining unit 5b determines, when the value ΔI2 of the time derivative of a secondary electric current exceeds a predetermined threshold value Z during a determination period, that blow-off has occurred; the determination period is a predetermined time period ΔT from the start of a spark discharge by a main ignition circuit 3. Further, when it is determined that blow-off has occurred during a main ignition (full-transistor ignition), it is controlled to perform a continuing spark discharge after the main ignition in a next cycle. Moreover, a secondary electric current command value in performing the continuing spark discharge is set to an electric current value that is obtained by adding a predetermined electric current value α to the secondary electric current value I2x immediately before the occurrence of blow-off. Consequently, in the next cycle, it is possible to reliably prevent blow-off, thereby reliably preventing misfire.

Dependencies are inferred from the claim text.