Patent ID: 6311484
Filing Date: 2001-11-06
Classification: B01D,F01N,Y02A,Y02T

Abstract:
A system for reducing transient and steady-state NOx emissions in the exhaust gases of a vehicle powered by a diesel fueled internal combustion engine comprising:a) a reducing catalytic converter downstream of said engine having a plurality of channels with a washcoat surface on the walls thereof and a reducing catalyst deposited over a portion of said washcoat surface, said channels having a set cross-sectional area and extending through said catalytic converter from an inlet to an exit thereof;b) a source of substantially long chain, unbranched hydrocarbons having a majority of hydrocarbon molecules containing more than 10 carbon atoms per molecule in its liquid phase;c) a fuel metering valve for pulsing variably set quantities of said hydrocarbons from said source pursuant to a valved pulse command signal;d) a plurality of vehicle sensors generating sensor signals indicative of an operating condition of said engine; said sensors including at least a temperature sensor generating a signal indicative of the temperature of said exhaust gases and an acceleration sensor generating a signal indicative of the change in operation of said engine set by the vehicular operator; ande) an engine control unit having a plurality of programmed routines for controlling said engine in response to said plurality of sensor signals; at least a first routine setting a constant pulsed quantity of said hydrocarbons when said engine is operating at steady state conditions sufficient to reduce a portion of NOx emissions produced at the steady state condition and a second routine activated when said acceleration sensor generates a signal indicative of impending acceleration, said second routinei) calculating a transient quantity of hydrocarbons necessary to reduce the NOx emissions generated during the time the engine is accelerating andii) generating a pulse command signal sufficient to meter said transient quantity of said hydrocarbons at a set time prior to the engine producing said transient NOx emissions when said washcoat has an acidic pH and after the engine has produced said transient NOx emissions when said washcoat has an alkaline pH.