| 摘要 |
<p>PROBLEM TO BE SOLVED: To perform high-efficient forced desorption treatment of an exhaust gas component by bringing an air-fuel ratio into a rich state at an optimum timing. SOLUTION: An SOx absorbing catalyst 4 is arranged upper stream from an NOx absorbing catalyst 3 in the exhaust passage 2 of an internal combustion engine 1 and inflow of an SOx component to the NOx absorbing catalyst 3 is prevented from occurring. Absorbed NOx is needed to effect desorption by bringing an air-fuel ratio into a rich state before saturation and based on a running route decided by a navigation system 11 for a vehicle, a running condition under running is estimated and an optimum desorption treatment timing is predicted. Thus, high-efficient desoprtion treatment is executed at a timing at which a condition, such as an exhaust gas temperature, is suitable for desorption. When it is predicted that a discharge SOx amount under running exceeds an absorbable amount, desorption treatment is immediately executed without waiting for a timing, and an outflow of SOx is surely avoided.</p> |
