Patent ID: 6993901

Claim:
An excess air factor control method for a diesel engine which burns a mixture of air supplied by an air supply mechanism and fuel supplied by a fuel supply mechanism, comprising: detecting a running state of the diesel engine; setting a target excess air factor of the mixture based on the running state; controlling an air supply amount of the air supply mechanism to a target air supply amount calculated from a predetermined fuel supply amount that has been determined without depending on the air supply amount of the air supply mechanism and the target excess air factor when the target excess air factor is larger than a value equivalent to a stoichiometric air-fuel ratio; and controlling a fuel supply amount of the fuel supply mechanism to a target fuel supply amount calculated from a predetermined air supply amount that has been determined without depending on the fuel supply amount of the fuel supply mechanism and the target excess air factor when the target excess air factor is smaller than the value equivalent to the stoichiometric air-fuel ratio.