Exhaust gas purifying system

Abstract

In an exhaust gas purifying system having a catalyst provided in an exhaust pipe for carrying out chemical reduction reaction so as to remove NOx contained in exhaust gas from an engine, an additive injection valve is provided in the exhaust pipe at an upstream side of the catalyst for injecting additive agent into the exhaust pipe, so that the chemical reduction reaction at the catalyst is facilitated. An injection port of the additive injection valve is formed into a slit-shape, so that a sheet-like spray is formed when the additive is injected from the additive injection valve.

1 . An exhaust gas purifying system for a vehicle comprising:
 a catalyst provided in an exhaust pipe of an internal combustion engine for facilitating chemical reduction reaction to purifying NOx contained in exhaust gas from the engine; and   an additive injection valve provided in the exhaust pipe at an upstream side of the catalyst for injecting additive agent into the exhaust pipe, so that the chemical reduction reaction at the catalyst is facilitated,   wherein an injection port of the additive injection valve is formed into a slit-shape.   
   
   
       2 . The exhaust gas purifying system according to the  claim 1 , wherein
 the slit-shape injection port is formed as a straightly extending slit.   
   
   
       3 . The exhaust gas purifying system according to the  claim 1 , wherein
 a width of the slit-shape injection port in a short side direction is not uniform.   
   
   
       4 . The exhaust gas purifying system according to the  claim 3 , wherein
 the width of the slit-shape injection port at a position away from a center in a longitudinal direction is made smaller than the width of the slit-shape injection port at the center.   
   
   
       5 . The exhaust gas purifying system according to the  claim 1 , wherein
 a center line of the injection by the additive injection valve is arranged to be in parallel to a center line of the exhaust pipe.   
   
   
       6  The exhaust gas purifying system according to the  claim 1 , wherein
 the slit-shape injection port crosses a center of the exhaust pipe and straightly extends in a radial direction of the exhaust pipe.   
   
   
       7 . An exhaust gas purifying system for a vehicle comprising:
 a catalyst provided in an exhaust pipe of an internal combustion engine for facilitating chemical reduction reaction to purify NOx contained in exhaust gas from the engine; and   a spray forming means provided in the exhaust pipe at an upstream side of the catalyst for injecting additive agent into the exhaust pipe, so that the chemical reduction reaction at the catalyst is facilitated,   wherein a sheet-like spray is formed when the additive is injected from the spray forming means.   
   
   
       8 . The exhaust gas purifying system according to the  claim 1 , further comprising:
 DPF provided in the exhaust pipe at an upstream side of the additive injection valve or the spray forming means.   
   
   
       9 . The exhaust gas purifying system according to the  claim 1 , wherein
 the exhaust pipe has a straight pipe portion,   the catalyst is provided at a downstream side of the straight pipe portion,   the additive injection valve is provided at an upstream side of the straight pipe portion, and   the additive injection valve is provided in the straight pipe portion in such a manner that a center line of a nozzle portion of the additive injection valve comes into line with a center line of the straight pipe portion.   
   
   
       10 . The exhaust gas purifying system according to the  claim 9 , wherein
 a center line of the catalyst comes into line with the center line of the straight pipe portion.   
   
   
       11 . The exhaust gas purifying system according to the  claim 9 , wherein
 the exhaust pipe has a first curved pipe at the upstream end of the straight pipe portion, and   the additive injection valve is provided at the first curved pipe.