Reduction of fouling in after treatment components

Abstract

A device and method for influencing exhaust gas flow downstream of a turbocharger turbine and upstream of after treatment components prevents doser tip fouling by using a passive exhaust flow control surface comprising ridges protruding into the exhaust gas flow conduit. The ridges are disposed parallel to each other, and perpendicular to the direction of gas flow. In one embodiment, a funnel is disposed in the conduit, downstream of the ridges, to further direct the exhaust gas flow more precisely towards a HC doser tip.

1 . An active regeneration arrangement for a diesel particulate filter (dpf) comprising:
 a conduit upstream of the dpf;   a doser mounted to the conduit for injecting hydrocarbon fuel into the conduit; and   at least one protrusion for influencing the flow of exhaust gas in the conduit to decrease fouling of the doser, the protrusion located upstream of the doser in an exhaust gas flow direction and extending into the conduit, the protrusion being disposed along an inner circumferential surface of the conduit such that the protrusion is in contact with the flow of exhaust gas.   
     
     
         2 . The arrangement of  claim 1 , wherein the protrusion is a ridge. 
     
     
         3 . The arrangement of  claim 1 , wherein the at least one protrusion comprises a plurality of protrusions that are aligned in parallel. 
     
     
         4 . The arrangement of  claim 3 , wherein the protrusions of the plurality are evenly spaced apart. 
     
     
         5 . The arrangement of  claim 1 , wherein the at least one protrusion comprises a plurality of protrusions that are aligned perpendicular to the net direction of gas flow along the conduit. 
     
     
         6 . The arrangement of clam  1 , further comprising a gas flow directing surface disposed downstream of the at least one protrusion. 
     
     
         7 . The arrangement of  claim 6 , wherein the gas flow directing surface extends from a portion of an inner surface of the conduit. 
     
     
         8 . The arrangement of  claim 6 , wherein the gas flow directing surface is a funnel. 
     
     
         9 . The arrangement of  claim 8 , wherein the mouth of the funnel is disposed within a plane perpendicular to the direction of gas flow. 
     
     
         10 . The arrangement of  claim 8 , wherein the mouth of the funnel is disposed within a plane oblique to the direction of gas flow. 
     
     
         11 . The arrangement of  claim 8 , wherein the stem of the funnel is oriented to direct gas flow toward a tip of the doser disposed within the conduit. 
     
     
         12 . The arrangement of  claim 6 , wherein the gas flow directing surface is oriented to direct gas flow toward a tip of the doser disposed within the conduit. 
     
     
         13 . The arrangement of  claim 1 , wherein the at least one protrusion comprises a plurality of protrusions wherein the protrusions circumscribe an inner surface of the conduit with consistent depth. 
     
     
         14 . A method for increasing the velocity of gas in a conduit past a doser in a diesel particulate filter active regeneration arrangement, comprising:
 providing a flow of gas past at least one protrusion disposed within an inner surface of a conduit upstream of the doser.   
     
     
         15 . The method of  claim 14 , further comprising the step of providing a flow of gas past a gas flow directing surface. 
     
     
         16 . The method of  claim 14 , further comprising the step of channeling the flow of gas around a curved portion in the conduit, wherein the protrusion is located on an inside of the curved portion. 
     
     
         17 . The method of  claim 15 , wherein the steps of providing a flow of gas past at least one protrusion and providing a flow of gas past a gas flow directing surface allows for a predetermined gas velocity into a predetermined region of the conduit.