Injector control for a selective catalytic reduction system

摘要

Systems and methods are provided for controlling the amount and timing of nitrogen oxides reductant injected during a given injection cycle into an exhaust system of a vehicle as part of a selective catalytic reduction system. The amount of reductant injected is determined by at least one computational model that accounts for the growth of liquid and/or solid reductant film growth on the interior of the exhaust system. The model determines reductant injection characteristics (e.g., amount, timing, etc.) that reduce and/or eliminate reductant films on the interior of the exhaust system. Exemplary inputs into the model include exhaust temperature, exhaust flow, and the amount of reductant injected in a previous injection cycle.

主权项

1. A method of using an on-board vehicle computing system to determine an amount of a reductant solution for reacting with nitrogen oxides, the reductant solution to be injected by an injector into an exhaust flow from an engine producing nitrogen oxides towards a catalyst, the method comprising:
(a) determining a first value of a first operating parameter using the on-board vehicle computing system; (b) determining a first value of a second operating parameter using the on-board vehicle computing system; (c) determining a first injector flow rate of the reductant solution injected into the exhaust flow by the injector using the on-board vehicle computing system; (d) determining a first reductant solution puddle size using the on-board vehicle computing system using the determined first value of the first operating parameter, the determined first value of the second operating parameter, and the first injector flow rate; (e) determining a reductant solution puddle delta using the on-board vehicle computing system using the determined first value of the first operating parameter, the determined first value of the second operating parameter, the first injector flow rate, and the first reductant solution puddle size; (f) determining a second injector flow rate parameter of the reductant solution using the on-board vehicle computing system, wherein the second injector flow rate parameter is determined using the determined reductant solution puddle delta and the determined first injector flow rate of the reductant solution; (g) determining a third injector flow rate of the reductant solution using the on-board vehicle computing system, wherein the third injector flow rate is determined using the determined first value of the first operating parameter, the determined first value of the second operating parameter, the determined first reductant solution puddle size, and the determined second injector flow rate parameter; and (h) adjusting the first injector flow rate of the reductant solution injected by the injector into the exhaust flow to the third injector flow rate of the reductant solution.