Patent ID: 7490463

Claim:
A motor vehicle exhaust aftertreatment system comprising: an exhaust conduit for conveying exhaust fluid from an engine, said conduit comprising a NO x adsorber that includes a NO x adsorber inlet and a NO x adsorber outlet and further comprising a particulate filter that includes a particulate filter inlet and a particulate filter outlet; a reformer for generating reformate containing hydrogen and carbon monoxide from fuel supplied from a fuel source; a reformate conduit for conveying said reformate from said reformer into said exhaust conduit upstream of said particulate filter; an oxygen sensor disposed in said exhaust conduit downstream of said reformate conduit and upstream of said particulate filter; a pressure sensor disposed at each of said particulate filter inlet and outlet for determining pressure drop through said particulate filter; and a temperature sensor disposed at each of said particulate filter inlet and outlet; wherein, in response to a pressure drop through said particulate filter attaining a threshold value, as determined by said pressure sensors disposed at said particulate filter inlet and outlet, reformate is introduced under selected controlled flow conditions from said reformer through said reformate conduit into said exhaust conduit and caused to undergo combustion, resulting in an exotherm, said selected controlled flow and subsequent combustion of said reformate in said exhaust conduit being carried out under conditions effective to maintain the temperature within said particulate filter within a selected temperature range, as measured by said temperature sensors respectively disposed at said inlet and outlet of said particulate filter; and wherein said exotherm resulting from said combustion of said reformate heats fluid passing through said particulate filter to a temperature effective to oxidize and thereby remove soot from said particulate filter, said oxygen sensor determining the oxygen concentration entering said particulate filter of said heated fluid in said exhaust conduit, said oxygen concentration being maintained within a selected concentration range, introduction of reformate into said exhaust conduit being discontinued when the pressure drop through said particulate filter is decreased to a selected value.