DEVICE FOR PURIFYING EXHAUST GAS OF INTERNAL COMBUSTION ENGINE AND METHOD FOR PURIFYING EXHAUST GAS

摘要

A particulate filter (8) is arranged in an exhaust passage (7) of an internal combustion engine (1), and a reduction catalyst (9) is arranged in the downstream of the filter. A bypass passage (12) is arranged for bypassing the reduction catalyst (9), and a passage switching valve (13) is also arranged for switching the path of an exhaust gas passed through the particulate filter (8) between the exhaust passage (7) and the bypass passage (12). A controller (301) controls the passage switching valve (13) according to the temperature (Texh) of the exhaust gas passed through the particulate filter (8).