Exhaust emission control apparatus for internal combustion engine, and control method for the exhaust emission control apparatus

摘要

An exhaust emission control apparatus for an internal combustion engine includes a urea water addition valve (104) provided in an exhaust passageway (1) and a supply passageway (102) that supplies urea water to the addition valve (104). This apparatus executes a recovery process of recovering an additive present in the supply passageway (102) by driving an electric urea water pump (103) with a vehicle-mounted battery (2) after the engine stops. In the exhaust emission control apparatus, the execution time of the recovery process is variably set on the basis of the battery voltage of the vehicle-mounted battery (2).