Exhaust gas purifying apparatus for internal combustion engine

Abstract

An object of the present invention is to provide an exhaust gas purifying apparatus for an internal combustion engine which can properly purge at least NOx of unpurified components contained in exhaust gas while considering characteristics of NOx desorbed from an adsorbent. A bypass passagebypassing a main exhaust passageof the internal combustion engineis provided. A HC/NOx adsorbenthaving a function of adsorbing HC and NOx is provided in the bypass passage. A second underfloor catalystis provided downstream of the adsorbent. A purge passagebranching off from the bypass passagewhile connecting to an intake passage is provided. An exhaust switching valveand a purge control valveare provided as a flow path switching means that is capable of switching a flow target into which the exhaust gas flows between the main exhaust passageand the bypass passage. If the purging operations are executed, the intake purging operation is first executed. After that, the intake purging operation is switched to the exhaust purging operation at a timing existing after the purge of NOx is completed and at the time point at which the temperature of the adsorbent becomes stable.