NOx adsorber aftertreatment system for internal combustion engines

Abstract

The present invention provides for an NOx adsorber aftertreatment system for internal combustion engines which utilizes a parallel arrangement of an adsorber catalyst and a bypass. The exhaust flow from the engine is routed through the adsorber during lean operation. At a predetermined regeneration time (for example, when the adsorber catalyst is 20% full), the exhaust gas flow is reduced through the parallel leg that contains the adsorber catalyst to be regenerated (e.g., 20% through the catalyst leg, 80% of the flow to the bypass leg). A quantity of hydrocarbon is injected into the reduced-flow catalyst leg in order to make the mixture rich. Since the flow has been reduced in this leg, only a small fraction of the amount of hydrocarbon that would have been required to make the mixture rich during full flow is required. This will result in a substantial reduction in the fuel penalty incurred for regeneration of the adsorber catalyst. Once the leg has been regenerated, the exhaust flow is switched to flow 100% through the adsorber leg.

1 - 31 . (canceled)  
   
   
       32 . An engine exhaust aftertreatment system comprising: 
 parallel exhaust flow paths;    a NOx aftertreatment component disposed in each of the flow paths;    a reducing agent catalyst positioned downstream of the parallel flow paths and through which exhaust flow from the parallel flow paths is constrained to pass;    a SOx aftertreatment component; and    a particulate aftertreatment component;    wherein the system regulates exhaust flow through the parallel exhaust flow paths and is operable in a rich mode wherein the system consumes a reduced amount of reducing agent attributable to the regulation of exhaust flow.    
   
   
       33 . A system according to claim  31  wherein the reduced amount of reducing agent is attributable to exhaust flow in a first flow path being increased exhaust flow in a second flow path being decreased.