Patent ID: 6186129
Filing Date: 2001-02-13
Classification: F02P,G01L,G01M

Abstract:
An apparatus for detecting a combustion event in a cylinder of an internal combustion engine having a spark plug proximate said cylinder, said apparatus comprising:an ignition coil having a primary winding and a secondary winding, said primary winding having a first end coupled to a power supply, said secondary winding having a first end coupled to said spark plug;a switch coupled to a second end of said primary winding opposite said first end, said switch being configured to cause a primary current to flow through said primary winding;a biasing circuit coupled to said second end of said primary winding and said second end of said secondary winding and configured to bias said spark plug with a bias voltage for producing an ion current indicative of the combustion event, said biasing circuit including a silicon-controlled rectifier (SCR) having an anode coupled to said second end of said secondary winding and configured to conduct a spark current through said secondary winding when an ignition voltage at said anode of said SCR reaches a predetermined level.