Patent ID: 6557537
Filing Date: 2003-05-06
Classification: F02P

Abstract:
An ion current detection system for an internal combustion engine, the system comprising:a DC power source; an energy charge inductance connected in series to the DC power source; a first switching device connected in series to the energy charge inductance; a second switching device; an ignition coil including a primary winding and a secondary winding, the primary winding connected in series to the second switching device between a ground and a first point between the energy charge inductance and the first switching device; a spark plug connected to the secondary winding; a first switching control means that switches periodically on and off the first switching device and the second switching device during multispark duration of the spark plug such that each switching device has a different switching status from each other; and a second switching control means that switches periodically on and off the second switching device after the multispark duration with a shorter interval than that of the first switching means, wherein: a first energy charged in the energy charge inductance is, discharged to cause a first spark by switching on the second switching device; a second energy charged in the ignition coil is discharged to cause a second spark by switching off the second switching device; and an ion current flowing in the secondary winding during a fuel combustion caused by the sparks is detected.