Internal combustion engine

摘要

First combustion and second combustion are selectively switched. During the first combustion, a combustion chamber (5) contains inactive gas of an amount larger than an amount where a generation amount of soot reaches its peak, so that soot is hardly generated. During the second combustion, the combustion chamber (5) contains inactive gas of an amount smaller than an amount where a generation amount of soot reaches its peak. In switching from the second combustion to the first combustion, a transition to the first combustion with a lean air-fuel ratio in the combustion chamber is made so as to heat a catalyst beyond a predetermined temperature.