Patent ID: 6216530
Filing Date: 2001-04-17
Classification: F02P

Abstract:
A combustion state detecting device for an internal combustion engine, comprising:an ignition coil formed of a transformer having a primary winding, one end of which is connected to a battery and the other end of which is connected to a power transistor for interrupting the supply of a primary current, and a secondary winding, for developing an ignition high voltage between both ends of said secondary winding when the supply of said primary current is interrupted;an ignition plug to which said ignition high voltage is applied through a high-voltage path connected to a plurality of output terminals of said ignition coil;bias means for charging a bias voltage necessary for detecting ions which are generated as a result of discharging in said ignition plug upon application of said ignition high voltage;discharge current limiting means for discharging the bias voltage charged in said bias means;ion current detecting means for detecting the discharge of said bias voltage as an ion current that flows through said ignition plug; andan ECU for detecting a combustion state in said ignition plug on the basis of a detection value of said ion current;wherein said discharge current limiting means is disposed between an ignition current path formed by discharging in said ignition plug and said bias means.