Patent ID: 7153342

Claim:
An exhaust gas purifying system of an internal combustion engine, comprising: a particulate matter (PM) filter installed in an exhaust passage line extending from the engine, the PM filter collecting particulate matter in the exhaust gas from the engine; a pressure difference sensor for detecting a pressure difference between upstream and downstream portions of the PM filter; a control unit which includes a collected PM amount estimating section that estimates an amount of collected PM in the PM filter based on the pressure difference; and a reactivation timing judging section that, based on the estimated amount of the collected PM, judges a reactivation time when the reactivation of the PM filter is needed; and a reactivation carrying out system that, upon judgment of the reactivation time, carries out a predetermined operation to increase the temperature of the PM filter thereby to burn the collected PM in the PM filter, wherein the control unit further comprises: a dispersion condition judging section that judges a dispersion condition of the collected PM in the PM filter; and a correction section that corrects the estimated amount of the collected PM in accordance with the judged dispersion condition of the collected PM.