| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a leakage diagnostic device and a leakage diagnostic method for a reducing agent injection valve and an exhaust emission control device for an internal combustion engine, detecting abnormal leakage from the reducing agent injection valve of a reducing agent injection device. <P>SOLUTION: This leakage diagnostic device detects abnormality of the reducing agent injection valve in the exhaust emission control device including a pump for forcibly feeding a reducing agent regenerating ammonia, the reducing agent injection valve injecting the reducing agent forcibly fed by the pump into the exhaust pipe of the internal combustion eigne, a reducing catalyst converting NO<SB>x</SB>in exhaust gas by the use of the ammonia, and an ammonia sensor provided downstream from the reducing catalyst and detecting the concentration of the ammonia in exhaust gas. The leakage diagnostic device includes: a reducing agent injection valve control means determining the valve opening time of the reducing agent injection valve based on the target injection quantity of the reducing agent and controlling opening/closing of the reducing agent injection valve; and a leakage determination means detecting the abnormal leakage from the reducing agent injection valve when the concentration of the ammonia is equal to or higher than a predetermined concentration and the valve opening time is less than a predetermined time. <P>COPYRIGHT: (C)2011,JPO&INPIT |
