US 7,320,781 B2
Method for adjusting a reductant used in an internal combustion engine to reduce NOx
Christine Kay Lambert, 2310 W. Miller Cir., Westland, Mich. 48186 (US); Karen Marie Adams, 3235 Gensley Rd., Ann Arbor, Mich. 48103 (US); and Robert Henry Hammerle, 32500 Susanne, Franklin, Mich. 48025 (US)
Filed on Jul. 01, 2002, as Appl. No. 10/186,690.
Application 10/186690 is a continuation in part of application No. 09/592202, filed on Jun. 13, 2000, abandoned.
Prior Publication US 2003/0005683 A1, Jan. 09, 2003
Int. Cl. B01D 53/56 (2006.01)
U.S. Cl. 423—239.1 18 Claims
 
1. A method for controlling reductant injection into a catalyst coupled to an internal combustion engine, the method comprising:
determining a reductant fraction based on an amount of reductant used in the catalyst and an amount of the reductant passing through the catalyst, said fraction representative of a fractional amount of reductant used in a reaction in the catalyst, wherein the fractional amount is based on a desired ratio between ammonia in the supplied reductant and NOx exhausted from the engine;
varying the reductant injection in accordance with both said determined reductant fraction and an amount of reductant exiting the catalyst, and where said varying further includes increasing said reductant injection only when such increase provides increased NOx conversion in the catalyst; and
wherein said engine is a diesel engine in a vehicle.