Patent ID: 8474244

Claim:
A method for controlling an injector intended for injecting a pollution-control liquid additive into exhaust gases of an internal combustion engine at a flow rate governed by a given frequency and opening time of the injector, the injector having a calibration curve that establishes, at given frequency, pressure, temperature and nature of the liquid, an amount of liquid injected during an opening of the injector as a function of the duration of the opening time, the curve comprising at least one linear zone (calibration line) and a non-linear zone, said method comprising: determining whether a predetermined flow rate falls within the linear zone of the calibration curve; if said predetermined flow rate falls within the linear zone of the calibration curve, using a set frequency and determining a variable opening time to obtain the predetermined flow rate on the basis of the calibration line; if said predetermined flow rate does not fall within the linear zone of the calibration line, using a set opening time and determining a variable frequency on the basis of at least one calibration point; controlling said injector in accordance with the determined opening time and frequency, wherein said set opening time is greater than or equal to a minimum time (t min ) required in order for the opening of the injector to be effective, if said predetermined flow rate is lower than said linear zone, and wherein, to achieve increasing flow rates, use is made of the set opening time and the variable frequency until a certain flow rate is obtained, then use is made of the given frequency and the variable opening time until a second flow rate is reached; next, use is also made of a given, but higher, frequency and a second variable opening time and finally, if necessary, use is made of another set opening time and a third variable frequency.