| 摘要 |
<p>PROBLEM TO BE SOLVED: To efficiently restrain deterioration of both a catalytic converter rhodium 32 and a storage type NOx catalyst 33, while avoiding poor fuel consumption. SOLUTION: The deterioration index of a catalytic converter rhodium 32 and the deterioration index of the storage type NOx catalyst 33 are derived from catalyst temperature, exhaust gas flow rates and exhaust gas components so that lean operation is prohibited, when the deterioration index of the catalytic converter rhodium 32 exceeds a second preset value and stoichiometric operation is prohibited, when the deterioration index of the storage type NOx catalyst 33 exceeds a first preset value, the deterioration of the easy-to-deteriorate catalyst is inhibited in priority, rich operation is performed when both deterioration indexes are higher, and the deterioration of both the catalytic converter rhodium 32 and the storage type NOx catalyst 33 is efficiently inhibited, while poor fuel consumption is restrained.</p> |
