| 摘要 |
An exhaust purification apparatus for an engine includes a NOx absorption catalyst (11) provided in an exhaust passage (10) of an engine (2), and absorbing a NOx in exhaust, a selective reduction catalyst (13) provided in the exhaust passage (10) in the downstream side of the NOx absorption catalyst (11), and reducing and purifying the NOx by using urea water, and a selective reduction catalyst temperature sensor (22) detecting the temperature of the selective reduction catalyst (13), and an engine control unit (30) estimates a NOx absorption rate ·a of the NOx absorption catalyst (11), and when a temperature Tc of the selective reduction catalyst (13) is higher than a first temperature threshold value T1, and the NOx absorption rate ·a is higher than a first absorption threshold value ·1, executes a first purge control that sets the air/fuel ratio of the exhaust to a stoichiometric air/fuel ratio or to a slightly leaner air/fuel ratio than the stoichiometric air/fuel ratio, and causes the NOx absorbed in the NOx absorption catalyst (11) to be discharged. |
