Evaporative fuel processing system for in-cylinder fuel injection type internal combustion engine and method

An evaporative fuel processing system for an in-cylinder injection type internal combustion engine comprising:

• an evaporative fuel processing mechanism that includes a canister to which an evaporative fuel in a fuel supply system is adsorbed and performs an operation of purging of the adsorbed evaporative fuel into an intake system of the internal combustion engine;
• and
• a controller that obtains a plurality of air/fuel ratio learned values corresponding to a plurality of engine load regions, each of which is used for compensating a variance tendency of an actual air/fuel ratio with respect to a target air/fuel ratio on a steady basis, and inhibits the purging operation performed by the evaporative fuel processing mechanism when a value representative of a variance of a first air/fuel ratio learned value corresponding to a highest engine load region among the plurality of engine load regions with respect to a second air/fuel ratio learned value corresponding to a lowest engine load region is equal to or larger than a predetermined value.

An evaporative fuel processing method for an in-cylinder injection type internal combustion engine provided with an evaporative fuel processing mechanism that includes a canister to which an evaporative fuel in a fuel supply system is adsorbed and performs an operation for purging the adsorbed evaporative fuel into an intake system of the internal combustion engine, the evaporative fuel processing method comprising:

• estimating a degree of dilution occurred in a lubricating oil for the internal combustion engine with a fuel mixed therewith;
• and
• inhibiting the purging operation performed by the evaporative fuel processing mechanism when the estimated degree of dilution is equal to or larger than a predetermined value.

An evaporative fuel processing method for an in-cylinder injection type internal combustion engine provided with an evaporative fuel processing mechanism that includes a canister to which an evaporative fuel in a fuel supply system is adsorbed and performs an operation for purging the adsorbed evaporative fuel into an intake system of the internal combustion engine, the evaporative fuel processing method comprising:

• obtaining a plurality of air/fuel ratio learned values corresponding to a plurality of engine load regions, each of which is used for compensating a variance tendency of an actual air/fuel ratio with respect to a target air/fuel ratio on a steady basis, and
• inhibiting the purging operation performed by the evaporative fuel processing mechanism when a value representative of a variance of a first air/fuel ratio learned value corresponding to a highest engine load region among the plurality of engine load regions with respect to a second air/fuel ratio learned value corresponding to a lowest engine load region is equal to or larger than a predetermined value.