Exhaust emission control device of internal combustion engine

Abstract

An exhaust gas purifying system reliably detects an amount of accumulated particulates, lengthens forced regeneration intervals, and improves fuel efficiency. The exhaust gas purifying system comprises: a particulate filterdisposed in an exhaust system of an internal combustion engineand collecting particulates from exhaust gas, and an NOgenerating unitupstream of or in the particulate filter; a discharged particulate amount calculating unit Acalculates an amount Me of discharged particulates on the basis of an excess air ratio λ; a burnt particulate amount calculating unit Acalculates an amount Mb of burnt particulates on the basis of the temperature of exhaust gas in front of the particulate filter or the temperature of the particulate filter; and a particulate accumulation amount calculating unit calculates an amount Ma of accumulated particulates on the basis of the amount Me of discharged particulates or the amount Mb of burnt particulates.