Patent ID: 7908843
Filing Date: 2011-03-22
Classification: B01D,F01N,Y02T

Abstract:
1. An exhaust gas purification device comprising: a NOx catalyst that is interposed in an exhaust path of an engine and purifies NOx contained in exhaust gas by using ammonia as a reducing agent; ammonia supply means for supplying ammonia to the NOx catalyst; catalyst temperature detection means for detecting internal temperature of the NOx catalyst; and control means that stops ammonia supply from the ammonia supply means when a stop condition is satisfied that the temperature detected by the catalyst temperature detection means is equal to or higher than first prescribed temperature in the process where ammonia is supplied from the ammonia supply means to the NOx catalyst, wherein the catalyst temperature detection means calculates the quantity of heat supplied to the NOx catalyst and the quantity of heat removed from the NOx catalyst using the exhaust flow rate of the NOx catalyst, a heat capacity of a carrier of the NOx catalyst and the exhaust temperature, and obtains the internal temperature of the NOx catalyst based upon a difference between these quantities of heat.