FUEL PROPERTY DETERMINATION DEVICE FOR INTERNAL COMBUSTION ENGINE

A minute amount of fuel is injected from an injector into a cylinder at a fuel injection timing at which an n-cetane etc. combustion period and a combustion period of components other than n-cetane etc. are separated in the compression stroke of a diesel engine. An integrated value of the equivalent torque generated in the period on the angle of advance side out of the separated combustion periods is obtained in a period from when the cylinder gas temperature reaches a low-temperature oxidation reaction start temperature until when it reaches a high-temperature oxidation reaction start temperature, and the cetane number of fuel is extracted from a cetane number determination map by applying that equivalent torque to the cetane number determination map.