| 摘要 |
PROBLEM TO BE SOLVED: To improve NOx purifying performance by switching a combustion condition into first combustion wherein there is much rate of inert gas supplied into a combustion chamber and soot is hardly generated, and second combustion there is few rate of inert gas supplied into the combustion chamber, and making an air-fuel ratio in a rich condition when NOx of NOx absorbent is discharged. SOLUTION: In an internal combustion engine 1 wherein NOx absorbent 25 is arranged in an exhaust passage, combustion is switched into first combustion in which a rate of inert gas supplied into a combustion chamber is much more than a rate of inert gas having peaked soot generating rate and soot is hardly generated, and second combustion in which a rate of inert gas supplied into the combustion chamber is few more than the rate of inert gas having peaked soot generating rate. An air-fuel ratio sensor 27 is arranged in an exhaust passage 22, and an air-fuel ratio is corrected so as to set in a rich condition, when the air-fuel ratio in the combustion chamber is set in the rich condition or the rich condition is not detected by the air-fuel ratio sensor 27 in order to discharge NOx from NOx absorbent 25. Namely, an injection fuel rate is corrected, and the degree of the rich condition of the air-fuel ratio is decided. |
