Control method and control device for internal combustion engine

An internal combustion engine control method for an internal combustion engine,

• the internal combustion engine including:
• an EGR passage connecting an exhaust passage to an intake passage for recirculating an EGR gas to the intake passage, wherein the EGR gas is a part of exhaust gas;
• and
• a negative pressure control valve disposed in a part of the intake passage upstream of a confluence of the EGR passage and the intake passage, and configured to open and close the intake passage;
• the internal combustion engine control method comprising:
• controlling the negative pressure control valve in a manner to ensure a differential pressure between the exhaust passage and the intake passage, when a state of operation of the internal combustion engine is in an EGR region where the EGR gas is recirculated to the intake passage through the EGR passage;
• and
• controlling the negative pressure control valve in a closing direction, and controlling an opening of the negative pressure control valve in a manner that a quantity of air passing through the negative pressure control valve is greater than or equal to a target intake air quantity, when the state of operation of the internal combustion engine is in an operation region lower in load than the EGR region, wherein the target intake air quantity is set based on the state of operation of the internal combustion engine.

An internal combustion engine control device comprising:

• an EGR passage connecting an exhaust passage to an intake passage for recirculating an EGR gas to the intake passage, wherein the EGR gas is a part of exhaust gas;
• a negative pressure control valve disposed in a part of the intake passage upstream of a confluence of the EGR passage and the intake passage, and configured to open and close the intake passage;
• and
• a control section configured to control operation of the negative pressure control valve, wherein the control section is further configured to:
• control the negative pressure control valve in a manner to ensure a differential pressure between the exhaust passage and the intake passage, when in an EGR region where the EGR gas is recirculated to the intake passage through the EGR passage;
• and
• control the negative pressure control valve in a closing direction, and control an opening of the negative pressure control valve in a manner that a quantity of air passing through the negative pressure control valve is greater than or equal to a target intake air quantity, when in an operation region lower in load than the EGR region, wherein the target intake air quantity is set based on a state of operation of an internal combustion engine.