| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology to judge abnormal supply of reducing agent for NOx catalyst or to judge deterioration of catalyst in order to control the deterioration of exhaust emission. SOLUTION: This exhaust emission purifying device is equipped with a lean- burn internal combustion engine 1, NOx catalyst 20, an inlet gas temperature- measuring device 37 for exhaust temperature before the catalyst 20, an outlet gas temperature-measuring device 24 for exhaust temperature after the catalyst 20, a reducing agent supply device 28 for supplying reducing agent to the catalyst 20, and an abnormal determination device 35 for determine abnormality of a reducing agent supply device 28 based on exhaust temperature before and after the catalyst 20 whose reducing agent is supplied by of a reducing agent supply device 28. |
