FIELD: monitoring and measuring equipment.
SUBSTANCE: object of the invention is a method of controlling the amount of urea crystals present in the exhaust system, containing catalyst for selective catalytic reduction of nitrogen oxides (NOx) using a reducing agent, called SCR catalyst, wherein said method includes a step of heating the exhaust system to a temperature sufficient for sublimation of urea crystals, which is started periodically based on the calculation model, is accompanied by measuring the amount of nitrogen oxides and/or the amount of reducing agent at the inlet and outlet of the catalyst, then the step of calculating the amount of urea crystals (MCm) present in the exhaust system, based on measurements made at the heating stage, then the correction stage of the calculation model using the amount of urea crystals calculated at the calculation step. Object of the invention is also a power unit comprising an electronic control unit which automatically executes said control method. Finally, subject of invention is motor vehicle containing such power unit.
EFFECT: disclosed is a method of controlling the amount of urea crystals present in the exhaust system of an internal combustion engine containing a SCR catalyst.
9 cl, 1 dwg
