To stabilize combustion when introducing EGR gas by using an intake air control valve.
In the engine 200, an impulse valve 224 is provided in an intake pipe 204, the intake pipe 204 is branched into a communication pipe 206 in a branch position downstream of the impulse valve 224, and an EGR passage 226 is connected to the downstream side of the impulse valve 224 and the upstream side of the branch position. An ECU 100 performs EGR combinedly using the impulse valve when injection quantity Q falls under an EGR range using the impulse valve together. At this time, an impulse valve opening Aip is controlled to be reduced from a value equivalent to full open as a default value to an intermediate opening. The ECU 100 calculates the intermediate opening for every cylinder based on a reference intermediate opening Aipm and an opening correction value Aadj so as to suppress deviation of the amount of EGR among cylinders, and controls the impulse valve 224 through an actuator 225 to set the impulse valve opening Aip to a value calculated for every cylinder.
KATSUMATA MASAJI
YOTSUEDA KEIJI
NISHIDA HIDEYUKI
TANNO SHIRO
Koji Yamamoto
Satoshi Nakamura