| 摘要 |
<P>PROBLEM TO BE SOLVED: To perform comprehensive failure diagnosis of a supply system of liquid reducer and precursor thereof. <P>SOLUTION: In an exhaust emission control device provided with an NOx reduction catalyst 20 reducing and converting NOx in exhaust gas, a reducer tank 24 storing urea aqueous solution as liquid reducer precursor, and a reducer adding device at least comprising an injection nozzle 18, a pump module 28 and an adding module 32 to add urea aqueous solution stored in the reducer tank 24 to an exhaust gas upstream side of the NOx reduction catalyst 20, a reducer adding ECU 40 operates addition flow rate of urea aqueous solution according to engine operation condition, and electronically controls the pump module 28 and the adding module 32 based on the addition flow rate, on the other hand, the reducer adding ECU 40 judges based on ratio of integration quantity obtained by sequentially integrating addition flow rate and consumption quantity operated from water level L of urea aqueous solution whether a failure occurs in the urea aqueous solution supply system or not. <P>COPYRIGHT: (C)2008,JPO&INPIT |
