Excess air factor control of diesel engine

An excess air factor control device 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:

• means for detecting a running state of the diesel engine;
• means for setting a target excess air factor of the mixture based on the running state;
• means for 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
• means for 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.

An excess air factor control device 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:

• a sensor which detects a running state of the diesel engine;
• and
• a programmable controller programmed to:
• set a target excess air factor of the mixture based on the running state;
• control 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
• control 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.

An excess air factor control device 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:

• a sensor which detects a running state of the diesel engine;
• and
• a programmable controller programmed to:
• set a target excess air factor of the mixture based on the running state;
• control an air supply amount of the air supply mechanism to a target air supply amount calculated from a predetermined fuel supply amount 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
• control a fuel supply amount of the fuel supply mechanism to a target fuel supply amount calculated from a predetermined air supply amount and the target excess air factor when the target excess air factor is smaller than the value equivalent to the stoichiometric air-fuel ratio;
• wherein the running state detecting sensor further comprises a sensor which detects a load of the diesel engine and a sensor which detects a rotation speed of the diesel engine, and the controller is further programmed, when the target excess air factor is larger than the value equivalent to the stoichiometric air-fuel ratio equivalent value, to calculate a target engine torque based on the load of the diesel engine and the rotation speed of the diesel engine, calculate a target air amount basic value based on the target engine torque and the rotation speed of the diesel engine, calculate a conversion coefficient based on the target excess air factor and the rotation speed of the diesel engine, set the predetermined air supply amount equal to a value obtained by multiplying the target air amount basic value by the conversion coefficient, and control the air supply amount of the air supply mechanism to the predetermined air supply amount.