| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress the generation of N<SB>2</SB>O in an exhaust emission control device that removes NOx in emission while using ammonium as a reducing agent. <P>SOLUTION: The exhaust emission control device includes at least: a reducing catalyst that causes a reduction reaction of nitrogen oxides in emissions using ammonium; an oxidation catalyst that causes an oxidation reaction of nitrogen monoxides in the emissions into the nitrogen dioxide at the side upstream of the reducing agent; an ammonium oxidation catalyst that causes an oxidation reaction of ammonium in the emission at the side downstream of the reducing agent; a bypass pipe that cause the emission to flow bypassing the oxidation catalyst; and a flow control valve for controlling the emission flow in the bypass pipe. A controller of the exhaust emission control device calculates the valve opening of the flow control valve based on an engine operating state to set a NOx ratio in the emission to an optimal value (S1 to S4), estimates an ammonium adsorption state in the reducing catalyst, and corrects the valve opening based on the estimated ammonium adsorption state (S5). <P>COPYRIGHT: (C)2011,JPO&INPIT |
