INTERNAL COMBUSTION ENGINE EXHAUST PURIFYING DEVICE AND EXHAUST PURIFYING METHOD

An exhaust purifying device for an internal combustion engine is provided that can regenerate an exhaust purifying filter at high efficiency without deteriorating the fuel economy. An exhaust purifying device of an engine (1) includes: a turbocharger (8); DPF (32); oxidation catalyst (31); high-pressure EGR path (6) that recirculates a portion of exhaust gas upstream of a turbine (81) into intake plumbing (2); a high-pressure EGR valve (11) and high-pressure EGR control portion (43) that control a flow rate of exhaust gas being recirculated via the high-pressure EGR path (6); a low-pressure EGR path (10) that recirculates a portion of exhaust gas downstream of the DPF (32) into the intake plumbing (2); a low-pressure EGR valve (12) and low-pressure EGR control portion (44) that control a flow rate of exhaust gas being recirculated via the low-pressure EGR path (10); exhaust gas temperature sensor (22) that detects the temperature of exhaust gas; and an EGR switching portion (45) that selects between recirculation control of exhaust gas by way of the high-pressure EGR control portion (43) and recirculation control of exhaust gas by way of the low-pressure EGR control portion (44) in accordance with the detected value of the exhaust gas temperature sensor, in a case of having determined to be a time at which to cause PM collected in the DPF to combust.