Exhaust gas purification system of internal combustion engine

An exhaust gas purification system of an internal combustion engine, comprising:

• a particulate filter disposed in an exhaust passage of the engine;
• temperature increasing means for increasing temperature of the particulate filter;
• particulate matter accumulation quantity estimating means for estimating a quantity of particulate matters accumulated in the particulate filter;
• and
• temperature increase controlling means for operating the temperature increasing means to increase the temperature of the particulate filter to a target temperature so that the particulate matters accumulated in the particulate filter are combusted and eliminated if the quantity of the particulate matters accumulated in the particulate filter, which is estimated by the particulate matter accumulation quantity estimating means, exceeds a predetermined value, wherein
• the temperature increase controlling means includes first correcting means for estimating the temperature of the particulate filter based on a state of the exhaust gas flowing into the particulate filter, an operating state of the engine and a manipulated variable of the temperature increasing means, and for correcting the manipulated variable of the temperature increasing means based on a result of comparison between the estimated temperature of the particulate filter and the target temperature;
• and
• the first correcting means calculates convergence temperature, to which the temperature of the particulate filter eventually converges if the present state of the exhaust gas flowing into the particulate filter, the present operating state of the engine and the present manipulated variable of the temperature increasing means are retained for a long time, based on the state of the exhaust gas flowing into the particulate filter, the operating state of the engine and the manipulated variable of the temperature increasing means, and calculates a first temperature estimate in accordance with a delay in a change of the temperature of the particulate filter due to a heat capacity of the particulate filter.