Patent ID: 7908910

Claim:
A combustion state detecting apparatus for an internal combustion engine, comprising: an ignition plug for generating a spark discharge for igniting an air-fuel mixture in a combustion chamber; an ignition coil for supplying a high voltage to cause the ignition plug to generate the spark discharge; ignition control means for feeding a driving signal for driving the ignition coil; ion current detection means for detecting an ion current generated in the combustion chamber; and combustion state detection means for detecting a combustion state in the ignition plug based on a detected value of the ion current, wherein an electromotive force generated in a secondary winding of the ignition coil due to electromagnetic induction when a primary current is caused to flow through a primary winding of the ignition coil in response to the driving signal fed to the ignition coil is applied to the ignition plug to detect the ion current generated in the combustion chamber to detect the combustion state in the ignition plug based on the detected value of the ion current, wherein the ignition control means provides the driving signal when the ion current is generated.