Exhaust gas purification apparatus for engine

Abstract

An exhaust gas purification apparatus of an engine having a reduction catalytic converter arranged in an engine exhaust gas system, for reducing and purifying nitrogen oxide by a liquid reducing agent, a reducing agent supply device controlling a flow rate of a liquid reducing agent that is supplied to the reduction catalytic converter, depending on engine operating conditions, an injection nozzle secured to the exhaust system via a flange, for injection-supplying the liquid reducing agent into exhaust gas at a position upstream of the reduction catalytic converter, and piping providing a fluid communication between the reducing agent supply device and the injection nozzle. The piping is constructed of a material made of ceramics, or water repellency treatment is applied to the inner wall of at least one of the injection nozzle and the piping.

1 . An exhaust gas purification apparatus of an engine comprising: 
 a reduction catalytic converter arranged in an engine exhaust system, for reducing and purifying nitrogen oxide by a liquid reducing agent;    a reducing agent supply device that controls a flow rate of a liquid reducing agent that is supplied to said reduction catalytic converter, depending on engine operating conditions;    an injection nozzle that is secured to said exhaust system via a flange, for injection-supplying the liquid reducing agent into exhaust gas at a position upstream of said reduction catalytic converter; and    piping that provides a fluid communication between said reducing agent supply device and said injection nozzle,    wherein said piping is constructed from a material made of ceramics.    
   
   
       2 . The exhaust gas purification apparatus of an engine according to  claim 1 , wherein cooling fins are provided and disposed in rows on said flange.  
   
   
       3 . The exhaust gas purification apparatus of an engine according to  claim 1 , wherein a coolant is permitted to flow through said flange.  
   
   
       4 . The exhaust gas purification apparatus of an engine according to  claim 1 , wherein an insulating material gasket is interposed between said exhaust system and said flange.  
   
   
       5 . An exhaust gas purification apparatus of an engine comprising: 
 a reduction catalytic converter arranged in an engine exhaust system, for reducing and purifying nitrogen oxide by a liquid reducing agent;    a reducing agent supply device that controls a flow rate of a liquid reducing agent that is supplied to said reduction catalytic converter, depending on engine operating conditions;    an injection nozzle that injection-supplies the liquid reducing agent into exhaust gas at a position upstream of said reduction catalytic converter; and    piping that provides a fluid communication between said reducing agent supply device and said injection nozzle,    wherein a water repellency treatment is applied to an inner wall of at least one of said injection nozzle and said piping.    
   
   
       6 . The exhaust gas purification apparatus of an engine according to  claim 5 , wherein said water repellency treatment is a fluorocarbon resin treatment.  
   
   
       7 . The exhaust gas purification apparatus of an engine according to  claim 5 , wherein said water repellency treatment is an organic plating treatment.  
   
   
       8 . The exhaust gas purification apparatus of an engine according to  claim 5 , wherein said piping is arranged to have an axis thereof extending in a substantially vertical direction, and said injection nozzle is connected to a lower end of said piping.