Patent ID: 7805930
Filing Date: 2010-10-05
Classification: B01D,F01N,Y02T

Abstract:
1. An exhaust emission purifying apparatus for an engine, for reductively purifying NO x in exhaust gas of the engine, comprising: a reduction catalyst for accelerating reduction of NO a reducing agent tank for storing an NO a reducing agent injection nozzle disposed upstream of the reduction catalyst in a flow of the exhaust gas; a supplying device for supplying the reducing agent stored in the reducing agent tank to the reducing agent injection nozzle; a heating device for heating the reducing agent in the reducing agent tank, the heating device including a cooling water pipe for leading cooling water of the engine to the reducing agent tank and using, as a heating medium, the cooling water flowing in the cooling water pipe; a cutoff valve for interrupting the cooling water circulating through the cooling water pipe; and a controller for controlling opening or closing of the cutoff valve, wherein the controller is configured to open the cutoff valve to circulate the cooling water through the cooling water pipe for a predetermined period after start of the engine each time the engine starts.