| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust gas purification device that can suppress the deterioration in a NOpurification ratio in an internal combustion engine where fuel and a reduction agent are added.SOLUTION: An exhaust passage 26 of an engine 1 includes: a reduction agent supply mechanism 200 for supplying an oxidation catalyst 31, an SCR catalyst 41, and the reduction agent to the exhaust passage 26; a fuel addition mechanism for adding the fuel to the exhaust passage 26; and a first NOsensor 130 for detecting the NOconcentration before purified by the SCR catalyst 41. A control device 80 suppresses the additive amount of the reduction agent based on the NOconcentration detected by the first NOsensor 130. The control device 80 adds the reduction agent after the period from when the fuel addition is stopped by the fuel addition mechanism until NOreduction reaction is suppressed in the oxidation catalyst 31 passes. |
