Patent ID: 7624717

Claim:
An internal-combustion-engine combustion condition detection apparatus comprising: first and second ignition devices each having an ignition plug that ignites a fuel-air mixture taken in for performing combustion when an internal combustion engine is operated, the first ignition device including a first ignition plug that causes main combustion in a combustion chamber, and the second ignition device including a second ignition plug that is disposed in the same combustion chamber as the first ignition plug of the first ignition device, spaced apart from the first ignition plug; an ignition control device that generates a control signal for controlling operations of the ignition devices; an ion-current detection device that detects an ion current generated during combustion; and a pre-ignition detection device that detects pre-ignition or a precursor phenomenon of pre-ignition, based on an ion current detected by the ion-current detection device, wherein the ion-current detection device detects a combustion ion current that is generated in the second ignition device regardless of whether or not ignition is performed by the second ignition device, thereby detecting pre-ignition or the precursor phenomenon of pre-ignition.