EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of treating NOx exhausted at cold start while suppressing fluctuation of an air fuel ratio.

SOLUTION: The exhaust emission control device for the internal combustion engine 12 is provided with a branch passage 26 branched from a main exhaust pipe 16 of the internal combustion engine 12; a change-over valve 28 for switching an exhaust gas flow passage between the main exhaust pipe 16 and the branch passage 26; a NOx adsorbent 30 provided on the branch passage 26 and adsorbing NOx included in exhaust gas; a purge means for purging desorption NOx desorbed from the NOx adsorbent 30 to an intake system of the internal combustion engine 12; and a moisture introducing means for selectively introducing moisture to the NOx adsorbent 30 based on the temperature of the NOx adsorbent 30 during execution by the purge means. Preferably, exhaust gas passed through a moisture adsorbent 24 is introduced to the NOx adsorbent 30 and moisture desorbed from the moisture adsorbent 24 is made flow.

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