Patent ID: 8511153

Claim:
A method for determining an injection law of a fuel injector ( 4 ) to be tested in an injection system ( 3 ) that includes a plurality of fuel injectors ( 4 ), a common rail ( 5 ) feeding fuel under pressure to the injectors ( 4 ), and a fuel pump ( 6 ) that keeps the fuel under pressure inside the common rail ( 5 ), said method comprising steps of: completely interrupting the feeding of the fuel from the fuel pump ( 6 ) to the common rail ( 5 ); avoiding opening of all of the fuel injectors ( 4 ) except for one of the fuel injectors ( 4 ) to be tested; measuring initial pressure (Pi) of the fuel inside the common rail ( 5 ) before starting the opening of the fuel injector ( 4 ) to be tested; opening the fuel injector ( 4 ) to be tested for a number (N) of consecutive openings greater than one with a same test-actuation time (T); measuring final pressure (P 0 ) of the fuel inside the common rail ( 5 ) after ending the opening of the fuel injector ( 4 ) to be tested; determining a pressure drop (ΔP) in the common rail ( 5 ) during the opening of the fuel injector ( 4 ) to be tested, which is equal to a difference between the initial pressure (Pi) and final pressure (Pf); estimating, according to the pressure drop (ΔP) in the common rail ( 5 ), a total fuel quantity (Q) that has been actually injected by the fuel injector ( 4 ) to be tested during the openings with the same test-actuation time (T); and calculating a fuel quantity (Q) that is actually injected by the fuel injector ( 4 ) to be tested when the fuel injector ( 4 ) is opened for the test-actuation time (T) by dividing the total fuel quantity (Q), that has been estimated according to the pressure drop (ΔP) in the common rail ( 5 ), by the number (N) of openings.