EXHAUST GAS PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To suppress the deterioration of a NOx purification catalyst caused by a thermal effect during DPF reproduction, and to effectively suppress the deterioration of the NOx purification ratio of the NOx purification catalyst by a simple constitution of an exhaust gas purification device.

SOLUTION: An exhaust gas purification device includes: a first post-treatment unit 20 which is arranged in an exhaust gas passage 11 in an internal combustion engine 10 and contains an NOx purification catalyst 23 capable of purifying NOx in exhaust gas; a second post-treatment unit 21 which contains an oxidation catalyst 24 and a filter 25 capable of trapping particulate substances contained in the exhaust gas; a bypass passage 12 which is branched from the upstream side of the first post-treatment unit 20 and joins a part between the first post-treatment unit 20 and the second post-treatment unit 21; an opening/closing means valve 13 which can open and close the bypass passage; and a control means which can open the opening/closing means 13 when the filter is regenerated, and can achieve post injection for the purpose of supplying fuel to the oxidation catalyst 24.

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