Internal-combustion-engine ignition apparatus

An internal-combustion-engine ignition apparatus for an internal combustion engine having a main combustion chamber and a subsidiary combustion chamber with which a fuel-air mixture in the main combustion chamber is ignited by combustion gas to be injected through an orifice provided between the main combustion chamber and the subsidiary combustion chamber, the internal-combustion-engine ignition apparatus comprising:

• an ignition plug provided in the subsidiary combustion chamber;
• an ignition coil having a primary coil, a secondary coil that is magnetically coupled with the primary coil and supplies a secondary current to the ignition plug, and a tertiary coil magnetically coupled with the primary coil and the secondary coil;
• a first switching circuit that turns on or off energization from a power source to the primary coil;
• a second switching circuit that turns on or off energization from the power source to the tertiary coil;
• and
• a controller that estimates a combustion state in the subsidiary combustion chamber based on an operating state of the internal combustion engine, that performs on/off-control of the first switching circuit so that the secondary current is generated in the secondary coil by a change in magnetic flux generated in the primary coil and a spark discharge is produced in the ignition plug and that performs on/off-control of the second switching circuit so that magnetic flux in the tertiary coil is changed so as to increase the secondary current, when deterioration of the combustion state including one of a misfire and a smolder has been estimated in the subsidiary combustion chamber.