Exhaust gas purifying apparatus and method for regenerating particulate filter thereof

摘要

An exhaust gas purifying apparatus includes an exhaust pipe, a first oxidation catalyst, a selective catalytic reduction (SCR) catalyst, a urea water supply system, a particulate filter (PF) and a controller. Exhaust gas discharged from an internal combustion engine flows through the exhaust pipe. The first oxidation catalyst is disposed in the exhaust pipe. The SCR catalyst is disposed in the exhaust pipe downstream of the first oxidation catalyst. The urea water supply system supplies urea water to the SCR catalyst. The PF is disposed in the exhaust pipe downstream of the SCR catalyst. The controller stops supplying the urea water from the urea water supply system during regeneration of the PF, so as to supply the NO 2 formed in the first oxidation catalyst to the PF, wherein the NO 2 functions as an oxidizing agent to oxidize particulate matter (PM) deposited on the PF for regenerating the PF.