| 摘要 |
A means of adaptively controlling the purging strategy of a lean NOx trap (LNT) 112 when the operating conditions do not support a standard (optimal) strategy. An ECU 130 may monitor upstream or downstream sensors 115, 116 or may estimate NOx levels present. When a parameter indicative of purge effectiveness falls below a target level, the purge strategy is adapted by changing at least one of the frequency of purge events, the length of each purge event and the richness of the feedgas entering the lean NOx trap during a purge event so as to restore the purge effectiveness to the target level. The parameter indicative of purge effectiveness may be a value of NOx conversion efficiency at the end of a purge event, the average purge time or amount of reductant used during preceding purge events. |
