EXHAUST GAS PURIFYING DEVICE FOR ENGINE

摘要

PROBLEM TO BE SOLVED: To enhance a Nox purification rate by a catalyst. SOLUTION: An exhaust gas purifying device comprises: a catalyst 22 disposed at an exhaust passage 20 of an engine to purify NOx in exhaust gas by reduction with a reducing agent; a reducing agent increasing means for increasing an amount of the reducing agent supplied to the catalyst 22; a detecting means 19 for detecting a degree of NOx purification in the catalyst 22; and a restraining means for temporally restraining the amount of the reducing agent increased by means of the reducing agent increasing means when the degree of NOx purification detected by the detecting means 19 is below a predetermined degree.