To provide a means of reliably suppressing engine oil dilution by fuel for use in a cylinder-direct fuel injection type internal combustion engine.
A dilution detector means detects the dilution of engine oil by fuel including gasoline on the basis of the concentration of hydrocarbon in blowby gas, the pressure, sonic velocity and infrared ray absorptance in the crankcase, and the viscosity, pH value, electric resistance and capacitance of engine oil-among others. If the detection value exceeds predetermined allowable dilution, a dilution suppressor means is started up to temporarily vary the fuel injection timing, injection pressure, cooling water temperature, oil temperature, ignition timing, and intake valve closing timing among others and thus to lower the dilution. That control prevents the sliding parts of the engine from seizing up.
KOHAMA TOKIO
SAITO KIMITAKA
KANO MASAO
