| 摘要 |
A method of controlling an engine 10 having a lean NOx trap 40 in the exhaust is described. The method comprises during a first mode, at a first temperature, storing NOx at a lean condition and then purging stored NOx from the NOx trap 40 at a rich condition without concurrently supplying oxygen to the trap 40 during the purging and during a second mode, at a second, lower temperature, storing NOx at a lean condition and then purging stored NOx from the trap 40 so that an exothermic reaction is generated to temporarily raise the temperature of the trap 40. The exothermic reaction may be generated by operating a first group of cylinders of the engine 10 lean and a second group of cylinders rich. The reaction may be adjusted by adjusting the duration of the lean operation or the a/f ratio of the lean cylinder group. |
