Patent ID: 7331171

Claim:
A control system for an internal combustion engine having an injector for injecting fuel into a combustion chamber, comprising: operating condition-detecting means for detecting an operating condition of the engine; post injection control means for executing post injection in which fuel is injected from the injector during an expansion stroke or an exhaust stroke of the engine, based on the detected operating condition of the engine including an amount of particulate matter (PM) in a filter is larger than a predetermined value; engine oil dilution amount-calculating means for calculating an amount of dilution of engine oil diluted with fuel injected by post injection; fuel evaporation amount-calculating means for calculating an amount of fuel evaporation from the engine oil; and engine oil dilution state-estimating means for estimating a state of dilution of the engine oil based on the calculated amount of dilution of engine oil and the calculated amount of fuel evaporation.