Patent ID: 6966179

Claim:
An exhaust-gas purifying system comprising: an exhaust-throttling valve and a diesel particulate filter set in an exhaust passage; and regeneration control means for regenerating the diesel particulate filter; said regeneration control means being provided with an exhaust-gas temperature detector, a fuel injection control unit and an exhaust-throttling control unit; wherein regenerating of the diesel particulate filter is performed in a manner such that when it is detected by the exhaust-gas temperature detector that the exhaust-gas temperature is in a predetermined first temperature region, said regeneration control means carries out an exhaust-gas temperature raising control by a multistage delay fuel-injection through the fuel injection control unit and by an exhaust throttling through the exhaust-throttling control unit; while when it is detected by the exhaust-gas temperature detector means that the exhaust-gas temperature is in a predetermined second temperature region in which the exhaust-gas temperature is higher than in the predetermined first temperature region, said regeneration control means carries out an exhaust-gas temperature raising control by a multistage delay fuel-injection through the fuel injection control unit without carrying out an exhaust throttling.