EXHAUST GAS TREATMENT DEVICE FOR DIESEL ENGINE

摘要

A filter unit is provided on the upstream side of an exhaust gas passage extending from a diesel engine. The filter unit is comprised of a plurality of filter chambers which are thermally isolated from one another and in which the exhaust gas is selectively introduced. A nitrogen oxide treatment portion provided with a nitrogen oxide reduction catalyst which causes a reaction between the exhaust gas and a reducing agent consisting of a reducing gas is provided on the downstream side of the exhaust gas passage. The exhaust gas is introduced into one of the plurality of filter chambers which constitute the filter unit, so that the particulate matter is captured by a filter provided in that filter chamber. The reducing gas passes through the filter and is introduced into the nitrogen oxide treatment portion provided on the downstream side, and a reduction reaction between the exhaust gas and the reducing agent consisting of the reducing gas occurs in the presence of the nitrogen oxide reduction catalyst. In the filter chambers in which no exhaust gas is introduced, heaters are operated to burn the particulate matter captured by the filters.