Exhaust gas purification apparatus for internal combustion engine

Abstract

An exhaust gas purification apparatus includes a venturi constituting part of an exhaust pipe and formed by joining two axially divided parts together, and a reducing agent supply device for injecting an aqueous urea solution into the exhaust pipe. The venturi is positioned such that joints thereof are located to the right and left, respectively, of the center of a cross section perpendicular to the axis of the venturi.

1 . An exhaust gas purification apparatus for an internal combustion engine, comprising:
 an exhaust gas purification catalyst arranged in an exhaust pipe of the engine;   a throat located upstream of the exhaust gas purification catalyst and formed by narrowing part of the exhaust pipe; and   a reducing agent injection device located at the throat or upstream of the throat close thereto, for injecting a reducing agent into the exhaust pipe, wherein   the throat is formed by joining two axially divided parts together and is positioned such that joints thereof are located to the right and left, respectively, of a center of a cross section perpendicular to an axis of the throat.   
   
   
       2 . The exhaust gas purification apparatus according to  claim 1 , wherein
 the throat is positioned such that the joints are each located within an angular range between 22.5° above and 22.5° below a horizontal line passing through the center of the cross section.   
   
   
       3 . The exhaust gas purification apparatus according to  claim 1 , wherein
 an injection nozzle of the reducing agent injection device has an injection opening located substantially at the center of the cross section.   
   
   
       4 . The exhaust gas purification apparatus according to  claim 3 , further comprising a mixing/diffusing device arranged immediately upstream of the injection nozzle.