EXHAUST EMISSION PURIFYING APPARATUS AND METHOD FOR AN INTERNAL COMBUSTION ENGINE

摘要

A particulate filter 8 is disposed in an exhaust passage 7 of an internal combustion engine 1, and a reduction catalyst 9 is disposed downstream of the particulate filter 8. A bypass passage 12 for bypassing the reduction catalyst 9 and a flow path switching valve 13 which switches a flow path for the exhaust gas which has passed through the particulate filter 8 between the exhaust passage 7 and the bypass passage 12 are disposed. A control unit 301 controls the flow path switching valve 13 in association with a temperature Texh of the exhaust gas which has passed through the particulate filter 8.