| 摘要 |
PROBLEM TO BE SOLVED: To stably and completely decrease the exhaust amount of emission by performing perturbation control of an air-fuel ratio, directly focusing on conditions of exhaust gas flowing out of a catalyst. SOLUTION: This exhaust emission control device has a catalyst device consisting of first and second catalysts 53, 54 disposed in series in an exhaust passage and an electrical control device 70. An electric control device 70 is integrated with a catalyst model which virtually divides the catalyst device into a plurality of blocks along an exhaust gas flow direction, and computes an oxygen concentration or the like which indicates degree of an over and short of oxygen in the gas flowing out of the respective blocks. The electric control device performs the perturbation control of the air-fuel ratio by controlling so that the air-fuel ratio may become at a prescribed rich air-fuel ratio when the oxygen concentration in the gas flowing out of the controlling blocks selected to move to the downstream side with degradation in oxygen absorbing capability of the catalyst device becomes larger than a positive threshold around "0", and controlling so that the air/fuel ratio may become at a prescribed lean air/fuel ratio when the oxygen concentration becomes smaller than a negative threshold around "0". COPYRIGHT: (C)2004,JPO&NCIPI
|
