Exhaust purifying apparatus for internal combustion engine

摘要

The exhaust purifying apparatus (30) includes an upstream catalyst (31) and a downstream catalyst (33) in an exhaust path (16) of an internal combustion engine (1). The catalysts (31, 33) each store and release a predetermined component of exhaust gas. The apparatus (30) includes a controller (40) to execute a first purging control involving the release of the component from the upstream catalyst (31) if the quantity of the stored component becomes equal to or larger than a first threshold, and a second purging control involving the release of the component from the downstream catalyst (33) if the quantity of the stored component becomes equal to or larger than a second threshold. If the quantities of the component stored in the upstream catalyst (31) and the downstream catalyst (33) respectively exceed a third threshold smaller than the first threshold and a fourth threshold smaller than the second threshold, the controller (40) simultaneously and continuously executes the first and second purging controls.