Patent ID: 8615987

Claim:
A method for controlling a Diesel Emission Fluid (DEF) injected quantity in a NO x reduction system employing a Selective Catalytic Reduction (SCR) catalyst, and a DEF injector adapted to inject said DEF to reach said SCR catalyst, the method comprising: determining a required quantity of DEF for the SCR catalyst at a given time; activating a DEF injection if the required quantity of DEF is at least equal to a threshold quantity, wherein said threshold quantity is a minimum injected fluid quantity that provides a substantially linear behavior for a given DEF injector; storing in memory of an Electronic Control Unit (ECU) the required quantity of DEF if the required quantity of DEF is less than said threshold quantity and after a period determining a further required quantity of DEF to be added to the required quantity of DEF to determine a new required quantity of DEF; continuously updating the new required quantity of DEF until the new required quantity of DEF is at least equal to said threshold quantity; and activating the DEF injection of the new required quantity of DEF.