Control device for internal combustion engine

A control device for an internal combustion engine with an EGR device which recirculates a part of exhaust gas of the internal combustion engine to an intake channel via an exhaust gas recirculation (EGR) channel, the internal combustion engine being programmed to control an EGR amount by adjusting an opening degree of an EGR valve disposed in the EGR channel, the control device comprising:

• a first temperature detection unit disposed in the intake channel and on an upstream side of a merging part at which the intake channel merges with the EGR channel;
• a second temperature detection unit disposed in the intake channel and on a downstream side of the merging part;
• a third temperature detection unit disposed in the EGR channel and between the EGR valve and the merging part;
• a pressure detection unit disposed in the intake channel and on the downstream side of the merging part;
• an EGR-valve basic opening degree calculation unit programmed to calculate a basic opening degree of the EGR valve on the basis of an operation state of the internal combustion engine;
• an estimate-value calculation unit programmed to calculate a first estimate value of an air-excess ratio in a combustion chamber of the internal combustion engine and a second estimate value of an intake oxygen concentration on the basis of a fuel-injection amount of the internal combustion engine, a rotation speed of the internal combustion engine, and detection values obtained by the first temperature detection unit, the second temperature detection unit, the third temperature detection unit, and the pressure detection unit;
• a target-value calculation unit programmed to calculate a first target value of the air-excess ratio and a second target value of the intake oxygen concentration on the basis of the operation state of the internal combustion engine;
• a correction-factor calculation unit programmed to calculate a correction factor for the basic opening degree of the EGR valve on the basis of the first estimate value, the second estimate value, the first target value and the second target value;
• an opening-degree command value calculation unit programmed to calculate an opening-degree command value for the EGR valve on the basis of the basic opening degree and the correction factor;
• a control unit programmed to control the opening degree of the EGR valve on the basis of the opening-degree command value;
• and
• a load detection unit programmed to detect a load of the internal combustion engine,
• wherein the correction-factor calculation unit is programmed to calculate the correction factor on the basis of the first estimate value and the first target value of the air-excess ratio if the load detected by the load detection unit is at least a predetermined value, and to calculate the correction factor on the basis of the second estimate value and the second target value of the intake oxygen concentration if the load detected by the load detection unit is less than the predetermined value.

A control device for an internal combustion engine with an EGR device which recirculates a part of exhaust gas of the internal combustion engine to an intake channel via an exhaust gas recirculation (EGR) channel, the internal combustion engine being programmed to control an EGR amount by adjusting of an opening degree of an EGR valve disposed in the EGR channel, the control device comprising:

• a first temperature detection unit disposed in the intake channel and on an upstream side of a merging part at which the intake channel merges with the EGR channel;
• a second temperature detection unit disposed in the intake channel and on a downstream side of the merging part;
• a third temperature detection unit disposed in the EGR channel and between the EGR valve and the merging part;
• a pressure detection unit disposed in the intake channel and on the downstream side of the merging part;
• an EGR-valve basic opening degree calculation unit programmed to calculate a basic opening degree of the EGR valve on the basis of an operation state of the internal combustion engine;
• an estimate-value calculation unit programmed to calculate an estimate value an intake oxygen concentration on the basis of a fuel-injection amount of the internal combustion engine, a rotation speed of the internal combustion engine, and detection values obtained by the first temperature detection unit, the second temperature detection unit, the third temperature detection unit, and the pressure detection unit;
• a target-value calculation unit programmed to calculate a target value of the intake oxygen concentration on the basis of the operation state of the internal combustion engine;
• a correction-factor calculation unit programmed to calculate a correction factor for the basic opening degree of the EGR valve on the basis of the estimate value and the target value;
• an opening-degree command value calculation unit programmed to calculate an opening-degree command value for the EGR valve on the basis of the basic opening degree and the correction factor;
• a control unit programmed to control the opening degree of the EGR valve on the basis of the opening-degree command value;
• and
• a load detection unit programmed to detect a load of the internal combustion engine,
• wherein the correction-factor calculation unit is programmed to suspend calculation of the correction factor for a predetermined period if a change rate of the load detected by the load detection unit is greater than a predetermined value.