US Patent 7398148 Control device for internal combustion engine

The valve timing is changed to increase the internal EGR amount the moment a fuel cut process begins (FIG. 2C). Before a sufficient amount of internal EGR is obtained, control is exercised so that the throttle-opening angle TA is larger than a basic idle-opening angle TA0. When a sufficient amount of internal EGR is obtained, control is exercised so that the throttle-opening angle TA is smaller than the basic idle-opening angle TA0 (FIG. 2D). The increase in the internal EGR amount is rendered smaller during fuel cut at a low rotation speed than during fuel cut at a high rotation speed. In addition, the amount of decrease in the throttle-opening angle TA is rendered smaller during fuel cut at a low rotation speed than during fuel cut at a high rotation speed.