Exhaust emission control device

Abstract

An exhaust emission control device reduces nitrogen oxide included in exhaust air from an internal combustion engine. The device includes an exhaust pipe, a catalyst, a supply device, a tank, and a temperature regulating device. The exhaust pipe defines a passage for exhaust air discharged from the engine. The catalyst is disposed in the exhaust pipe. The catalyst is capable of promoting reduction reaction of the nitrogen oxide in exhaust air. The supply device is for supplying a fluid-state additive agent, which is used for the reduction reaction, to an upstream side of the catalyst in a flow direction of exhaust air. The additive agent is stored in the tank. The temperature regulating device is for regulating temperature of the additive agent, which is supplied by the supply device, to be in a predetermined range.

1 . An exhaust emission control device for reducing nitrogen oxide included in exhaust air from an internal combustion engine, the device comprising:
 an exhaust pipe defining a passage for exhaust air discharged from the engine;   a catalyst disposed in the exhaust pipe, the catalyst being capable of promoting reduction reaction of the nitrogen oxide in exhaust air;   a supply means for supplying a fluid-state additive agent, which is used for the reduction reaction, to an upstream side of the catalyst in a flow direction of exhaust air;   a tank in which the additive agent is stored; and   a temperature regulating means for regulating temperature of the additive agent, which is supplied by the supply means, to be in a predetermined range.   
   
   
       2 . The exhaust emission control device according to  claim 1 , wherein:
 the additive agent is urea; and   the temperature regulating means regulates the temperature of the additive agent to be a temperature ranging from  60 ° C. to a boiling point of urea.   
   
   
       3 . The exhaust emission control device according to  claim 1 , wherein the temperature regulating means regulates the temperature of the additive agent to be in the predetermined range by heating the additive agent, which is stored in the tank. 
   
   
       4 . The exhaust emission control device according to  claim 1 , wherein the temperature regulating means regulates the temperature of the additive agent to be in the predetermined range by heating the additive agent using waste heat recovered from the engine as a heat source.