ENGINE EXHAUST EMISSION CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a sufficient HC removing effect by utilizing the reproducing capability of an HC adsorbent to its limit. SOLUTION: A bypass path 3 is provided in the upstream side of the exhaust pipe 2 of a diesel engine 1 so as to be branched from the same and connected to the same, an HC adsorbent 7 is provided in this bypass path 3, and electric heater 8 for increasing the temperature of this HC adsorbent 7 is also provided and an NOX reducing catalyst 9 for reducing and making NOX nontoxic by using HC as a reducing agent is provided. When the NOX reducing catalyst 9 is inactive, HC contained in exhaust gas is adsorbed through the bypass path 3 by the HC adsorbent 7 and when the NOX reducing catalyst 9 is active, HC is desorbed from the HC adsorbent 7 by a temperature increase caused by the electric heater 8 and decomposed by the NOX reducing catalyst 9.