LNT DESULFATION STRATEGY WITH REFORMER TEMPERATURE MANAGEMENT

摘要

Desulfation methods for an exhaust treatment system (7) having a fuel reformer (12) configured upstream of a LNT (13). Reductant is injected upstream of the fuel reformer (12). The reductant reacts within the reformer (12) to generate heat, but the system is configured for some reductant to breakthrough and react in the LNT (13) to generate further heat. This configuration allows the LNT (13) to operate at temperatures higher the than first device (12) and facilitates independent control of the LNT (13) and first device (12) temperatures. An outer loop controls the LNT (13) temperature by issuing instructions to an inner loop that controls the first device (12). Typically, the inner loop will pulse the reductant injection rate in order to limit the first device (12) temperature. The outer loop pulses the reductant injection rate on a longer time scale, resulting in two pulse periods. Through timing, a reformate peak from one period is made to overlap a temperature peak from a previous period.