Model based method for selective catalyst reducer urea dosing strategy
AssigneeDetroit Diesel Corporation
InventorsMin Sun, Sathish Sankara-Chinttoanony, Bryant Chan Pham, Amr Mohamed Radwan, Zhiping Han, Wolfgang Krueger
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Abstract
A method to control NH3 slippage and NOx conversion in an electronic controlled internal combustion engine exhaust system equipped with a selective catalyst reducer, a diesel particulate filter, a diesel oxidation catalyst and a urea doser.
Claims8
A method to control NOx conversion and ammonia slippage-in an electronic controlled internal combustion engine with an electronic control unit (ECU) having maps or data points to control an exhaust system equipped with a selective catalyst reducer (SCR) a diesel particulate filter (DPF), a diesel oxidation catalyst (DOC) and, a urea doser, and sensors to transmit data signals to said ECU indicative of exhaust system operating conditions, comprising:
- determining the SCR operating condition;
- determining engine out NOx exhaust flow rate into the SCR;
- determining NH3 dosing rate by inputting to a one dimensional model engine air mass flow rate, engine total air flow rate (AFR), engine NOx flow rate, SCR inlet NO2/NOx ratio;
- SCR inlet pressure, SCR inlet temperature, DOC inlet temperature, ambient temperature, oxygen flow rate from said DPF and vehicle speed, to determine NH3 storage of the SCR, ammonia slip from the SCR, SCR outlet NOx, SCR deNOx efficiency and a requested NH3 rate;
- and providing said determined NH3 storage of the SCR, NH3 slip from the SCR, SCR outlet NOx, SCR deNox efficiency, and the requested NH3 rate to a model inversion together with a critical NH3 slip and storage
- recalibrating the SCR operating condition in response to pre-targeted ammonia storage, ammonia slip, and NOx conversion;
- and
- injecting urea into the exhaust system.
Dependencies are inferred from the claim text.