| 摘要 |
PROBLEM TO BE SOLVED: To maintain a high exhaust emission control efficiency by a catalyst, and to further reduce HC, CO and NOx emissions. SOLUTION: This air-fuel ratio control device includes: a first air-fuel ratio sensor 11 provided upstream of an exhaust emission control catalyst 3 mounted in the exhaust passage of an internal combustion engine 2; a second air-fuel ratio sensor 12 provided downstream of the catalyst 3; and an air-fuel ratio control section 5 performing feedback control over an air-fuel ratio by referring to output of at least the first air-fuel ratio sensor 11. The air-fuel ratio control section 5 estimates the present ratio of oxygen in accordance with a model mathematical formula for a ratio of oxygen as a ratio of the amount of oxygen stored in the catalyst 3 to the oxygen storage capacity of the catalyst, and controls the estimated rate of oxygen to a target value. COPYRIGHT: (C)2011,JPO&INPIT |
