Multiple Flow Path Exhaust Treatment System

Abstract

A vehicle exhaust system for an engine having a plurality of combustion chambers includes a first emission treatment device, a second emission treatment device and a housing defining a first exhaust passageway in fluid communication with the combustion chambers and containing the first emission treatment device. A second parallel exhaust passageway is in fluid communication with the combustion chambers and contains the second emission treatment device. The first and second passageways share a common wall having a serpentine shape such that the cross-sectional area of the passageways varies along a direction of exhaust flow. The first emission treatment device is positioned at a location of increased cross-sectional area in the first passageway and the second emission treatment device is positioned at an axially offset location of increased cross-sectional area in the second passageway.

1 . A vehicle exhaust system for an engine having a plurality of combustion chambers, comprising:
 a first emission treatment device;   a second emission treatment device; and   a housing including a first exhaust passageway in fluid communication with the combustion chambers and containing the first emission treatment device, the housing further including a second parallel exhaust passageway in fluid communication with the combustion chambers and containing the second emission treatment device, the first and second passageways sharing a common wall having a serpentine shape such that the cross-sectional area of the first and second exhaust passageways varies along a direction of exhaust flow, the first emission treatment device being positioned at a location of increased cross-sectional area in the first passageway and the second emission treatment device being positioned at an axially offset location of increased cross-sectional area in the second passageway.   
     
     
         2 . The exhaust system of  claim 1  wherein a sum of the cross-sectional area of the first emission treatment device and the cross-sectional area of the second emission treatment device is greater than a cross-sectional area of the housing at the first emission treatment device position. 
     
     
         3 . The exhaust system of  claim 1  wherein the cross-sectional area of the first and second emission treatment devices is substantially the same. 
     
     
         4 . The exhaust system of  claim 1  wherein the first and second emission treatment devices include diesel particulate filters. 
     
     
         5 . The exhaust system of  claim 1  further including a third emission treatment device positioned within the first passageway downstream of the first emission treatment device. 
     
     
         6 . The exhaust system of  claim 5  further including a fourth emission treatment device positioned within the second passageway downstream of the second emission treatment device. 
     
     
         7 . The exhaust system of  claim 6  wherein the cross-sectional area of the first and third emission treatment devices is substantially the same. 
     
     
         8 . The exhaust system of  claim 7  wherein the third and fourth emission treatment devices include selective catalytic reduction elements. 
     
     
         9 . A vehicle exhaust system for an engine having a plurality of combustion chambers, comprising:
 a housing;   a first array of parallel positioned emission treatment devices;   a second array of parallel positioned emission treatment devices, the first and second arrays being axially spaced apart within the housing;   a first exhaust passageway in fluid communication with the combustion chambers and containing the first array of emission treatment devices; and   a second and separate exhaust passageway in fluid communication with the combustion chambers and containing the second array of emission treatment devices, the first and second passageways extending parallel to one another within the housing, wherein the first exhaust passageway includes a portion bypassing the second array of emission treatment devices and wherein the second passageway includes a portion bypassing the first array of emission treatment devices.   
     
     
         10 . The exhaust system of  claim 9  wherein the bypassing portion of the first passageway extends parallel to the second array. 
     
     
         11 . The exhaust system of  claim 10  wherein the bypassing portion of the second passageway extends parallel to the first array. 
     
     
         12 . The exhaust system of  claim 11  wherein an upstream end of the bypassing portion of the first passageway is positioned downstream of the first array. 
     
     
         13 . The exhaust system of  claim 12  wherein a downstream end of the bypassing portion of the second passageway is positioned upstream of the second array. 
     
     
         14 . The exhaust system of  claim 9  further including a third array of parallel positioned emission treatment devices axially spaced apart from the first and second arrays, and a third separate exhaust passageway in fluid communication with the combustion chambers and containing the third array of emission treatment devices, wherein the third passageway extends parallel to the first and second passageways and includes a portion bypassing the first and second arrays. 
     
     
         15 . The exhaust system of  claim 14  wherein the bypassing portion of the third passageway extends parallel to the first and second arrays. 
     
     
         16 . The exhaust system of  claim 14  wherein ends of each of the first, second and third passageways are in communication with each other at an outlet of the housing. 
     
     
         17 . The exhaust system of  claim 16  wherein ends of each of the first, second and third passageways are in communication with each other at a collector portion of the housing in receipt of exhaust from the combustion chambers. 
     
     
         18 . The exhaust system of  claim 14  wherein each of the bypassing portions of the first, second and third passageways is positioned adjacent to two emission treatment devices.