Patent ID: 8793977

Claim:
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.