Method and apparatus for controlling reductant injection into an exhaust gas feedstream of an internal combustion engine

A method for controlling a reductant delivery system arranged to inject a reductant into an exhaust aftertreatment system for an internal combustion engine, wherein the reductant delivery system includes a fluidic pump fluidly connected to an injector that is disposed in the exhaust aftertreatment system upstream relative to a catalytic device, the method comprising:

• operating the fluidic pump at a preset state, operating the injector at a zero-flow state, and monitoring, via a pressure sensor, pressure upstream of the injector to determine a zero-flow pressure;
• activating the injector under a preset condition and monitoring an actual pressure drop upstream of the injector;
• determining a pressure drop deviation based upon the actual pressure drop upstream of the injector and an expected pressure drop upstream of the injector under similar operating conditions;
• dynamically determining an adjustment to the activation of the injector based upon the pressure drop deviation;
• and
• controlling the injector based upon the adjustment to achieve the expected pressure drop in the reductant delivery system.

An exhaust aftertreatment system arranged to inject a reductant into an exhaust gas feedstream of an internal combustion engine, comprising:

• a reductant delivery system including a fluidic pump fluidly connected to a reductant injector including a nozzle that is disposed in an exhaust aftertreatment system upstream relative to a catalytic device;
• a pressure sensor disposed to monitor fluidic pressure in the reductant delivery system;
• a controller, operatively connected to the reductant delivery system and in communication with the pressure sensor, the controller including an instruction set, the instruction set executable to:
• determine a desired reductant dosing rate;
• determine an initial injector command for controlling the reductant injector based upon the desired reductant dosing rate;
• dynamically determine an adjustment factor based upon a difference between an expected pressure drop and an actual pressure drop in the reductant delivery system under similar operating conditions;
• and
• control the reductant injector based upon the adjustment factor and the initial injector command to achieve the expected pressure drop in the reductant delivery system.