Exhaust system having reductant nozzle flow diverter

Abstract

An exhaust system for use with an engine is disclosed. The exhaust system may have an exhaust passage with an indentation having an upstream wall and a downstream wall. The exhaust system may also have a nozzle disposed within the downstream wall, and a flow diverter cantilevered from the upstream wall partway into the exhaust passage.

1 . An exhaust system, comprising:
 an exhaust passage having an indentation with an upstream wall and a downstream wall;   a nozzle disposed within the downstream wall; and   a flow diverter cantilevered from the upstream wall partway into the exhaust passage.   
     
     
         2 . The exhaust system of  claim 1 , wherein the flow diverter is tilted relative to the upstream wall by an angle less than about 30 degrees. 
     
     
         3 . The exhaust system of  claim 1 , wherein the flow diverter tapers in width from a base end to a tip end at an angle less than about 20 degrees. 
     
     
         4 . The exhaust system of  claim 1 , wherein a cantilevered length of the flow diverter is about 0.2 to 1.5 times a width of the flow diverter. 
     
     
         5 . The exhaust system of  claim 1 , wherein a width of the flow diverter is about 0.2 to 0.8 times a width of the indentation. 
     
     
         6 . The exhaust system of  claim 1 , wherein a thickness of the flow diverter is about 1 to 2 mM. 
     
     
         7 . The exhaust system of  claim 1 , wherein the flow diverter is curved and has an axis of curvature parallel with a length direction. 
     
     
         8 . The exhaust system of  claim 1 , wherein the indentation is located within a bend portion of the exhaust passage. 
     
     
         9 . The exhaust system of  claim 8 , wherein the indentation restricts exhaust flow through the bend portion. 
     
     
         10 . The exhaust system of  claim 1 , wherein the flow diverter increases near-nozzle exhaust velocities and swirling in a plane generally parallel with the downstream wall. 
     
     
         11 . The exhaust system of  claim 10 , wherein the flow diverter increases near-nozzle exhaust velocities by about 100%. 
     
     
         12 . The exhaust system of  claim 10 , wherein the increased velocities continue in a length direction of the exhaust passage. 
     
     
         13 . The exhaust system of  claim 12 , wherein the increased velocities continue for about ½ of a length of the exhaust passage. 
     
     
         14 . The exhaust system of  claim 1 , wherein the flow diverter causes injections from the nozzle to oscillate relative to a plane of symmetry through the flow diverter. 
     
     
         15 . The exhaust system of  claim 14 , wherein the flow diverter causes the injections to oscillate through a range of about 20-90°. 
     
     
         16 . The exhaust system of  claim 14 , wherein the flow diverter causes the injections to oscillate across an entire diameter of the exhaust passage. 
     
     
         17 . The exhaust system of  claim 1 , wherein the flow diverter reduces reductant deposits at the nozzle by about 50-95%. 
     
     
         18 . An exhaust system, comprising:
 an exhaust passage configured to receive exhaust from an engine and having a bend portion with an indentation; and   a flow diverter located in the bend portion and configured to generate a vortex in the exhaust at the indentation.   
     
     
         19 . The exhaust system of  claim 18 , wherein the flow diverter tapers in width from a base end to a tip end at an angle less than about 20 degrees. 
     
     
         20 . The exhaust system of  claim 18 , wherein a length of the flow diverter is about 0.2 to 1.5 times a width of the flow diverter. 
     
     
         21 . The exhaust system of  claim 18 , wherein the flow diverter is curved and has an axis of curvature parallel with a length direction. 
     
     
         22 . The exhaust system of  claim 18 , wherein the flow diverter extends from the indentation partway through the exhaust passage. 
     
     
         23 . The exhaust system of  claim 18 , wherein the vortex is located within a plane generally perpendicular to a flow direction through the bend portion. 
     
     
         24 . The exhaust system of  claim 23 , wherein the vortex increases near-nozzle exhaust velocities by about 100%. 
     
     
         25 . The exhaust system of  claim 23 , wherein the vortex continues in a length direction of the exhaust passage. 
     
     
         26 . The exhaust system of  claim 25 , wherein the vortex continues for about ½ of a length of the exhaust passage. 
     
     
         27 . An exhaust system, comprising:
 an exhaust passage configured to receive exhaust from an engine;   a treatment device located within the exhaust passage;   a reductant nozzle located upstream of the aftertreatment device and having a tip mounted generally flush with an interior wall of the exhaust passage; and   a flow diverter located upstream of the reductant nozzle and configured to increase a speed of exhaust impinging upon the tip of the reductant nozzle.