| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an engine capable of restricting the thermal deterioration of a NOx catalyst. <P>SOLUTION: The exhaust emission control device 100 for an engine 10 includes a NOx catalyst converter 31 having a NOx catalyst 31A which collects NOx contained in the exhaust when an excess air ratio is larger than 1 and desorbs and reduces NOx collected when the excess air ratio is an excess regenerated air ratio smaller than 1 in an exhaust passage 30. The exhaust emission control device for the engine includes: an intake throttle valve 21 provided in the intake passage 20; an injector 11 for supplying fuel to the engine 10; and an excess air ratio control means 40 for making an opening of the intake throttle valve 21 small so that the excess air ratio is lowered at the regeneration of the NOx catalyst and lowering the excess air ratio to the excess regenerated air ratio by performing post fuel injection by the injector 11 when the excess air ratio becomes lower than the post fuel injection starting excess air ratio computed based on the engine operating state when the regeneration of the NOx catalyst is started. <P>COPYRIGHT: (C)2010,JPO&INPIT |
