Patent ID: 8196391

Claim:
An emissions-control system of a vehicle coupled to an engine of the vehicle and comprising: an LNT disposed in an exhaust system of the vehicle, downstream of the engine; an SCR device disposed in the exhaust system of the vehicle, downstream of the LNT; a controller operatively coupled to the engine, configured to cause the engine to provide a reducing exhaust to the LNT during an enrichment interval, the enrichment interval including an enrichment subinterval, the controller further configured to adjust the enrichment subinterval in response to an aging of the LNT; an upstream sensor disposed within the LNT, wherein the controller is configured to adjust a start of the enrichment subinterval based on an output of the upstream sensor and is further configured to adjust a level of enrichment of the enrichment subinterval based on aging of the LNT; and a downstream sensor disposed in the exhaust system downstream of the LNT and upstream of the SCR, wherein the controller is further configured to lengthen the enrichment subinterval if an output of the downstream sensor is below a first threshold, and to shorten the enrichment subinterval if the output of the downstream sensor is above a second threshold, different than the first threshold.