Patent ID: 8161952

Claim:
An electronically controlled blow-by gas returning apparatus for an internal combustion engine, wherein the engine corrects a fuel injection amount such that the fuel injection amount is reduced in accordance with a degree of enrichment of an actual air-fuel ratio in relation to a target air-fuel ratio, the blow-by gas returning apparatus comprising: an electronically controlled ventilation valve which regulates a flow rate of blow-by gas in a crank chamber of the engine fed into an intake passage; and a control unit for controlling the ventilation valve, wherein the control unit sets a demand value of an opening degree of the ventilation valve based on an engine operating state, and controls the opening degree of the ventilation valve such that the actual value of the opening degree of the ventilation valve is maintained at the demand value, and wherein the control unit corrects the demand value based on a relation between the degree of enrichment and an intake air amount, which is the amount of air fed into a combustion chamber of the internal combustion engine, such that the degree of enrichment of the actual air-fuel ratio (AFR) in relation to the target air-fuel ratio (AFT) does not exceed a previously set allowable range.