Diagnostic and mitigation strategy for reductant injector obstruction in exhaust system

A method of mitigating obstruction of a reductant injector in an exhaust system of an internal combustion engine, the method comprising:

• monitoring a duty cycle of a reductant injector structured to couple with an exhaust conduit in the exhaust system;
• monitoring a duty cycle of a pump operated to supply a reductant to the reductant injector in a plurality of monitoring periods;
• determining that a relative maximum amount of the reductant is injected in a first one of the plurality of monitoring periods and that a relative minimum amount of the reductant is injected in a second one of the plurality of monitoring periods;
• calculating a diagnostic value based on a difference between a duty cycle of the pump in the first one of a plurality of monitoring periods, and a duty cycle of the pump in the second one of the plurality of monitoring periods;
• producing an error signal based on the diagnostic value;
• and
• triggering an obstructed-injector mitigation action in response to the error signal.

An exhaust system for an internal combustion engine comprising:

• a reductant tank;
• an exhaust conduit;
• an electronically controlled reductant injector structured for coupling with the exhaust conduit;
• an electronically controlled pump structured to supply a reductant from the reductant tank to the electronically controlled reductant injector;
• an electronic control unit coupled with each of the electronically controlled reductant injector and the electronically controlled pump, the electronic control unit being structured to:
• receive data indicative of a duty cycle of the electronically controlled reductant injector, and data indicative of a duty cycle of the electronically controlled pump;
• determine each of a maximum duty cycle of the electronically controlled reductant injector and a minimum duty cycle of the electronically controlled reductant injector from among the plurality of monitoring periods;
• calculate a diagnostic value based on a difference between a duty cycle of the electronically controlled pump in a first one of a plurality of monitoring periods corresponding to the determined maximum duty cycle, and a duty cycle of the electronically controlled pump in a second one of the plurality of monitoring periods corresponding to the determined minimum duty cycle:
• compare the diagnostic value with a threshold value;
• produce an error signal based on the comparing of the diagnostic value with a threshold value;
• and
• trigger an obstructed-injector mitigation action in response to the error signal.