Patent ID: 7571602

Claim:
A method of exhaust aftertreatment for a lean burn internal combustion engine comprising: providing at least one lean NOx trap (LNT) in downstream lean exhaust flow relation with the lean burn internal combustion engine; providing a diesel oxidation catalyst in fluid communication with said at least one LNT such that said diesel oxidation catalyst is upstream of said at least one LNT; selectively directing substantially all of said lean exhaust flow to a first portion of said at least one LNT; selectively blocking substantially all of said lean exhaust flow to a second portion of said at least one LNT; introducing a mass flow rate of reductant to said second portion of said at least one LNT to regenerate said second portion of said at least one LNT; and combining exhaust flow from said first portion of said at least one LNT and exhaust flow from said second portion of said at least one LNT upstream of a diesel particulate filter disposed in a downstream flow relation to said at least one LNT; introducing said mass flow rate of reductant to said second portion of said at least one LNT at quantities greater than required to regenerate said second portion of said at least one LNT such that excess reductant passes through said second portion of said at least one LNT; and communicating said excess reductant and said lean exhaust gas to said diesel particulate filter (DPF) to effect regeneration of said DPF.