Reducing agent supplying device

Abstract

A reducing agent supplying device is for a fuel combustion system that includes a NOx purifying device with a reducing catalyst arranged in an exhaust passage to purify NOx. The reducing agent supplying device supplies a reducing agent into the exhaust passage upstream of the reducing catalyst. The reducing agent supplying device includes an air pipe, a vaporizing container, an injector, a heating member and a mixing plate. The air pipe defines an air passage therein. The vaporizing chamber is connected to the air pipe. The vaporizing container defines a vaporizing chamber therein that branches off from the air passage. The injector injects liquid hydrocarbon compound as a reducing agent. The heating member is disposed in the vaporizing chamber. The heating member heats and vaporizes the reducing agent. The mixing plate is connected to the heating member. The mixing plate extends from the vaporizing chamber into the air passage.

What is claimed is: 
     
         1 . A reducing agent supplying device for a fuel combustion system that includes a NOx purifying device with a reducing catalyst arranged in an exhaust passage to purify NOx contained in exhaust gas of an internal combustion engine, the reducing agent supplying device supplying a reducing agent into the exhaust passage at a position upstream of the reducing catalyst, the reducing agent supplying device comprising:
 an air pipe that defines an air passage therein;   a vaporizing container that is connected to the air pipe, the vaporizing container defining a vaporizing chamber therein that branches off from the air passage;   an injector that injects liquid hydrocarbon compound as a reducing agent;   a heating member that is disposed inside the vaporizing chamber, the heating member heating and vaporizing the reducing agent injected from the injector; and   a mixing plate that is connected to the heating member, the mixing plate extending from the vaporizing chamber into the air passage.   
     
     
         2 . The reducing agent supplying device according to  claim 1 , wherein
 the heating member includes a heat plate, onto which the reducing agent in liquid form injected from the injector is sprayed, and a heater that heats the heat plate, and   the mixing plate is connected to the heat plate.   
     
     
         3 . The reducing agent supplying device according to  claim 2 , wherein
 the mixing plate is formed of material having lower thermal conductivity than the heat plate.   
     
     
         4 . The reducing agent supplying device according to  claim 3 , wherein
 the mixing plate is made of stainless steel and the heat plate is made of copper.   
     
     
         5 . The reducing agent supplying device according to  claim 2 , further comprising
 an elastic member that is disposed between the heater and the heat plate, wherein   the elastic member is in contact with the heater and the heat plate while being elastically deformed.   
     
     
         6 . The reducing agent supplying device according to  claim 5 , wherein
 the elastic member is made of a material that exhibits elasticity even when a temperature of the heat plate increases to a temperature at which a deposit on the heat plate is combusted.   
     
     
         7 . The reducing agent supplying device according to  claim 2 , further comprising
 a retaining member that is attached to the vaporizing container, and   a binding member that binds the retaining member to the mixing plate, wherein   the heat plate is held by being interposed between the retaining member and the mixing plate.   
     
     
         8 . The reducing agent supplying device according to  claim 7 , wherein
 the retaining member includes a first portion that is attached to the vaporizing container, a second portion that is in contact with, and holds, the heat plate, and an intermediate portion that is interposed between the first portion and the second portion,   the first portion and the second portion are made of metal, and   the intermediate portion is made of a material having lower thermal conductivity than the first member and the second member.   
     
     
         9 . The reducing agent supplying device according to  claim 8 , wherein
 the second portion is made of stainless steel, and   the heat plate is made of copper.