Patent ID: 8042517

Claim:
A fuel property detector for an internal combustion engine, comprising: cylinder pressure detection means for detecting cylinder pressure in an internal combustion engine; ignition delay time calculation means for calculating ignition delay time in accordance with the cylinder pressure; high-cetane fuel judgment means for judging in accordance with the calculated ignition delay time whether the cetane number of an employed fuel is high; ignition delay time extension means which, when the cetane number of the employed fuel is judged to be high, increases the ignition delay time by correcting a control parameter for the internal combustion engine; ignition delay time recalculation means for recalculating the ignition delay time in accordance with the cylinder pressure after the ignition delay time is increased by the ignition delay time extension means; and cetane number calculation means for calculating the cetane number of the employed fuel in accordance with the ignition delay time calculated by the ignition delay time recalculation means.