Patent ID: 8667783

Claim:
A method for controlling an operation of a pump of a system that supplies a liquid additive for exhaust gases of an internal combustion engine, said pump driven in two opposite rotational directions by an electric motor and controlled by a controller, according to which an electronic control module (ECM) sends, to the controller, a pulse width modulation control signal having a variable duty cycle and according to which the controller acts on the electric motor to apply desired operating conditions to the pump, wherein each duty cycle of the pulse width modulation control signal is associated to a plurality of information relative to said operating conditions of the pump, the plurality of information comprising at least one information relative to a desired output pressure of the pump and one information relative to a desired rotational direction of the pump, wherein corresponding to a first duty cycle range (I) is a setpoint for stopping the pump, corresponding to a second duty cycle range (II) is a setpoint for forward drive of the pump, and corresponding to a third duty cycle range (III) is a setpoint for reverse drive of the pump, and wherein during a purge cycle, the electronic control module emits the pulse width modulation control signal with a duty cycle value in the first duty cycle range to stop the pump, changes the duty cycle value to a value in the third duty cycle range to cause the purge, and changes the duty cycle value to a value in the first duty cycle range to stop the pump again.