Patent attributes
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 filter 22 disposed in an exhaust system of an internal combustion engine 2 and collecting particulates from exhaust gas, and an NO2 generating unit 21 upstream of or in the particulate filter 22; a discharged particulate amount calculating unit A1 calculates an amount Me of discharged particulates on the basis of an excess air ratio λ; a burnt particulate amount calculating unit A2 calculates 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.
