Mirrored Two-Stage Mixer

Abstract

A mixer for an exhaust aftertreatment system may include a housing and first and second groups of deflectors. The first group of deflectors may be disposed within the housing and may be arranged relative to each other to direct fluid flowing through the first group of deflectors into a first pair of vortices that rotate in opposite directions relative to each other. The second group of deflectors may be disposed within the housing and may be arranged relative to each other to direct fluid flowing through the second group of deflectors into a second pair of vortices that rotate in opposite directions relative to each other. The first and second groups of deflectors may be rotationally symmetric with each other about a longitudinal axis of the housing.

What is claimed is: 
     
         1 . An exhaust aftertreatment system comprising:
 an exhaust passageway receiving exhaust gas from an engine;   an exhaust aftertreatment device disposed within the exhaust passageway; and   a mixer disposed in the exhaust passageway upstream of the exhaust aftertreatment device, the mixer including a housing, a first group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the first group of deflectors into a first pair of vortices that rotate in opposite directions relative to each other, and a second group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the second group of deflectors into a second pair of vortices that rotate in opposite directions relative to each other, wherein the first and second groups of deflectors are rotationally symmetric with each other about a longitudinal axis of the housing.   
     
     
         2 . The exhaust aftertreatment system of  claim 1 , wherein the exhaust aftertreatment device includes a catalyst. 
     
     
         3 . The exhaust aftertreatment system of  claim 1 , further comprising a reductant delivery system including a reductant injector arranged to inject reductant into the exhaust passageway upstream of the first and second groups of deflectors. 
     
     
         4 . The exhaust aftertreatment system of  claim 1 , further comprising a reductant delivery system including first and second reductant injectors arranged to inject reductant into the exhaust passageway upstream of the first and second groups of deflectors. 
     
     
         5 . The exhaust aftertreatment system of  claim 4 , wherein the housing includes first and second ports through which reductant is injected into the housing from the first and second reductant injectors, respectively, the first and second ports being arranged relative to the first and second groups of deflectors such that a majority of reductant injected through the first port flows through the first group of deflectors and a majority of reductant injected through the second port flows through the second group of deflectors. 
     
     
         6 . The exhaust aftertreatment system of  claim 1 , wherein the mixer includes a third group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the third group of deflectors into a third pair of vortices that rotate in opposite directions relative to each other. 
     
     
         7 . The exhaust aftertreatment system of  claim 6 , wherein the first, second and third groups of deflectors are rotationally symmetric with each other about the longitudinal axis. 
     
     
         8 . The exhaust aftertreatment system of  claim 7 , further comprising a central mixer centered on the longitudinal axis, the central mixer including a plurality of deflectors. 
     
     
         9 . The exhaust aftertreatment system of  claim 6 , wherein the housing includes first, second and third ports arranged relative to the first, second and third groups of deflectors such that a majority of reductant injected through the first port flows through the first group of deflectors, a majority of reductant injected through the second port flows through the second group of deflectors, and a majority of reductant injected through the third port flows through the third group of deflectors. 
     
     
         10 . The exhaust aftertreatment system of  claim 6 , wherein the aftertreatment device includes a triangular shape. 
     
     
         11 . The exhaust aftertreatment system of  claim 6 , wherein the mixer includes a fourth group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the fourth group of deflectors into a fourth pair of vortices that rotate in opposite directions relative to each other. 
     
     
         12 . The exhaust aftertreatment system of  claim 11 , wherein the first, second, third and fourth groups of deflectors are rotationally symmetric with each other about the longitudinal axis. 
     
     
         13 . The exhaust aftertreatment system of  claim 12 , further comprising a central mixer centered on the longitudinal axis, the central mixer including a plurality of deflectors. 
     
     
         14 . The exhaust aftertreatment system of  claim 11 , wherein the housing includes first, second third and fourth ports arranged relative to the first, second, third and fourth groups of deflectors such that a majority of reductant injected through the first port flows through the first group of deflectors, a majority of reductant injected through the second port flows through the second group of deflectors, a majority of reductant injected through the third port flows through the third group of deflectors, and a majority of reductant injected through the fourth port flows through the fourth group of deflectors. 
     
     
         15 . The exhaust aftertreatment system of  claim 11 , wherein the aftertreatment device includes a square shape. 
     
     
         16 . The exhaust aftertreatment system of  claim 1 , wherein each of the first and second groups of deflectors include a plurality of plates extending parallel to the longitudinal axis of the housing and each including a plurality of tabs that are angled relative the plate and the longitudinal axis. 
     
     
         17 . The exhaust aftertreatment system of  claim 16 , wherein the plurality of tabs of each of the plurality of plates includes a plurality of first tabs extending from a first side of the corresponding plate in a first direction and a plurality of second tabs extending from a second opposite side of the corresponding plate in a second direction. 
     
     
         18 . The exhaust aftertreatment system of  claim 1 , wherein the housing is a generally tubular member. 
     
     
         19 . A mixer for an exhaust aftertreatment system comprising:
 a housing;   a first group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the first group of deflectors into a first pair of vortices that rotate in opposite directions relative to each other; and   a second group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the second group of deflectors into a second pair of vortices that rotate in opposite directions relative to each other,   wherein the first and second groups of deflectors are rotationally symmetric with each other about a longitudinal axis of the housing.   
     
     
         20 . The mixer of  claim 19 , wherein the housing includes first and second ports arranged relative to the first and second groups of deflectors such that a majority of reductant injected through the first port flows through the first group of deflectors and a majority of reductant injected through the second port flows through the second group of deflectors. 
     
     
         21 . The mixer of  claim 19 , further comprising a third group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the third group of deflectors into a third pair of vortices that rotate in opposite directions relative to each other. 
     
     
         22 . The mixer of  claim 21 , wherein the first, second and third groups of deflectors are rotationally symmetric with each other about the longitudinal axis. 
     
     
         23 . The mixer of  claim 21 , wherein the housing includes first, second and third ports arranged relative to the first, second and third groups of deflectors such that a majority of reductant injected through the first port flows through the first group of deflectors, a majority of reductant injected through the second port flows through the second group of deflectors, and a majority of reductant injected through the third port flows through the third group of deflectors. 
     
     
         24 . The mixer of  claim 21 , further comprising a fourth group of deflectors disposed within the housing and arranged relative to each other to direct fluid flowing through the fourth group of deflectors into a fourth pair of vortices that rotate in opposite directions relative to each other. 
     
     
         25 . The mixer of  claim 24 , wherein the first, second, third and fourth groups of deflectors are rotationally symmetric with each other about the longitudinal axis. 
     
     
         26 . The mixer of  claim 24 , wherein the housing includes first, second third and fourth ports arranged relative to the first, second, third and fourth groups of deflectors such that a majority of reductant injected through the first port flows through the first group of deflectors, a majority of reductant injected through the second port flows through the second group of deflectors, a majority of reductant injected through the third port flows through the third group of deflectors, and a majority of reductant injected through the fourth port flows through the fourth group of deflectors. 
     
     
         27 . The mixer of  claim 19 , wherein each of the first and second groups of deflectors include a plurality of plates extending parallel to the longitudinal axis of the housing and each including a plurality of tabs that are angled relative the plate and the longitudinal axis. 
     
     
         28 . The mixer of  claim 27 , wherein the plurality of tabs of each of the plurality of plates includes a plurality of first tabs extending from a first side of the corresponding plate in a first direction and a plurality of second tabs extending from a second opposite side of the corresponding plate in a second direction. 
     
     
         29 . The mixer of  claim 19 , wherein the housing is a generally tubular member. 
     
     
         30 . A mixer for an exhaust aftertreatment system comprising:
 a housing;   a first group of deflectors disposed within the housing and arranged to generate a first pair of counter-rotating vortices; and   a second group of deflectors disposed within the housing and arranged to generate a second pair of counter-rotating vortices,   wherein the first and second groups of deflectors are arranged in a circular array about a longitudinal axis of the housing.   
     
     
         31 . The mixer of  claim 30 , further comprising a third group of deflectors disposed within the housing and arranged to generate a third pair of counter-rotating vortices. 
     
     
         32 . The mixer of  claim 31 , wherein the circular array includes the third group of deflectors. 
     
     
         33 . The mixer of  claim 31 , further comprising a fourth group of deflectors disposed within the housing and arranged to generate a fourth pair of counter-rotating vortices. 
     
     
         34 . The mixer of  claim 33 , wherein the circular array includes the fourth group of deflectors. 
     
     
         35 . The mixer of  claim 34 , further comprising a fifth group of deflectors centered on the longitudinal axis and surrounded by the first, second, third and fourth groups of deflectors. 
     
     
         36 . The mixer of  claim 35 , wherein all of the first, second, third, and fourth groups of deflectors are rotationally oriented differently from each other. 
     
     
         37 . The mixer of  claim 30 , wherein the first and second groups of deflectors are surrounded by first and second collars, respectively. 
     
     
         38 . The mixer of  claim 37 , wherein the first and second collars include first and second longitudinal axes, respectively, that are angled relative to each other and relative to the longitudinal axis of the housing.