Biased reductant mixer

Abstract

An engine exhaust aftertreatment system including a mixer with a varying contact area that assists in the introduction and conversion of a reductant introduced by an injector.

1 . An engine exhaust aftertreatment system comprising:
 an injector configured to introduce a reductant into an exhaust conduit of a engine; and   a mixer disposed in the exhaust conduit wherein a frontal contact area of the mixer varies.   
     
     
         2 . The engine exhaust aftertreatment system of  claim 1  wherein the frontal contact area of the mixer is greater in an impingement region where the reductant predominately strikes the mixer compared to a smaller contact area in a remainder of the mixer. 
     
     
         3 . The engine exhaust aftertreatment system of  claim 2  wherein the mixer is disposed downstream of the injector and upstream of a selective catalytic reduction catalyst. 
     
     
         4 . The engine exhaust aftertreatment system of  claim 2  wherein the mixer is a cone tilted off center from a centerline of the exhaust conduit with a longer surface associated with the impingement region compared to a shorter surface associated with the remainder of the mixer. 
     
     
         5 . The engine exhaust aftertreatment system of  claim 4  wherein the cone includes an end opening associated with the remainder of the mixer. 
     
     
         6 . The engine exhaust aftertreatment system of  claim 2  wherein the mixer includes openings and the openings in the impingement region are smaller than the openings in the remainder of the mixer. 
     
     
         7 . The engine exhaust aftertreatment system of  claim 2  wherein the mixer includes openings and the openings in the impingement region are spaced further apart than the openings in the remainder of the mixer. 
     
     
         8 . The engine exhaust aftertreatment system of  claim 2  wherein the mixer includes a ring with a wider width associated with the impingement region compared to a width associated with the remainder of the mixer. 
     
     
         9 . The engine exhaust aftertreatment system of  claim 2  wherein the mixer is constructed from only a single piece of metal. 
     
     
         10 . The engine exhaust aftertreatment system of  claim 2  wherein a maximum contact area for a portion of the mixer in the impingement region is between 10% and 40% greater than a minimum contact area for a portion of the mixer in the remainder of the mixer. 
     
     
         11 . An engine exhaust aftertreatment system comprising:
 an injector configured to introduce a reductant into an exhaust conduit of a engine; and   a mixer disposed in the exhaust conduit wherein the mixer is a cone tilted off center from a centerline of the exhaust conduit.   
     
     
         12 . The engine exhaust aftertreatment system of  claim 11  wherein a longer surface of the tilted cone is associated with an impingement region where the reductant predominately strikes the mixer compared to a shorter surface associated with a remainder of the mixer. 
     
     
         13 . The engine exhaust aftertreatment system of  claim 12  wherein the tilted cone includes an end opening associated with the remainder of the mixer. 
     
     
         14 . An engine exhaust aftertreatment system comprising:
 an injector configured to introduce a reductant into an exhaust conduit of a engine; and   a mixer disposed in the exhaust conduit, the mixer including openings that vary in size in different regions of the mixer.   
     
     
         15 . The engine exhaust aftertreatment system of  claim 14  wherein a frontal contact area of the mixer varies in the different regions. 
     
     
         16 . The engine exhaust aftertreatment system of  claim 15  wherein the frontal contact area of the mixer is greater in an impingement region where the reductant predominately strikes the mixer compared to a smaller contact area in a remainder of the mixer. 
     
     
         17 . The engine exhaust aftertreatment system of  claim 16  wherein the openings in the impingement region are smaller compared to the openings in a remainder of the mixer. 
     
     
         18 . The engine exhaust aftertreatment system of  claim 17  wherein a maximum contact area for a portion of the mixer in the impingement region is between 10% and 40% greater than a minimum contact area for a portion of the mixer in the remainder of the mixer. 
     
     
         19 . The engine exhaust aftertreatment system of  claim 14  wherein the mixer is a cone. 
     
     
         20 . The engine exhaust aftertreatment system of  claim 14  wherein the mixer is a planar disc.