| 摘要 |
<p>PURPOSE:To provide an exhaust emission control method to prevent the increase of a total amount of NOx exhausted during deterioration of a lean NOx catalyst and to provide a deterioration degree of catalyst detecting device to perform decision of deterioration with accuracy and high stability CONSTITUTION:Based on the temperature TCAT of a leans NO catalyst, a deterioration factor R is calculated and integrated at intervals of 10 seconds to execute processing for updating the degree K of deterioration at S10-S40. From a non-volatile memory, the degree K of deterioration is read and in a case of K>=-Kbs, an O2 feedback condition is varied at S110-S130 so that an operation region on which feedback control is applied in a stoichiometeric amount of air is widen and a lean burn region is narrowed. As a result, a region where NOx is purified by a three-dimensional catalyst is widened on the whole of running and though a fuel consumption is slightly increased, an amount of NOx discharged in the atmosphere air on the whole of running is prevented from an increase.</p> |
