Operation of a fuel injector having a hydraulic stop

An engine control unit for a vehicle, the control unit comprising:

• a processor;
• and
• a memory storing a set of instructions, the set of instructions when loaded and executed by the processor, causing the processor to:
• apply a first current profile to a solenoid drive to perform a first injection process by moving the armature toward the pole piece to the hydraulic stop and inject a predefined injection quantity through a gap between the movable armature and the pole piece into a cylinder of an internal combustion engine;
• determine a first value of a system parameter indicative of a relationship between an actual injected fuel quantity and the predefined fuel quantity, wherein the system parameter measures an operation variable of the cylinder;
• determine, on the basis of the determined first value of the system parameter, whether the actual injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and the hydraulic stop caused by an opposite hydraulic force exerted on the armature by fuel;
• and
• if it was determined that the quantities differ by the predefined amount, apply a second current profile to the solenoid drive to perform a second injection process;
• wherein the second current profile, in comparison with the first current profile, exerts a lower magnetic force on the armature in the direction of the pole piece.

A computer program comprising a set of instructions stored on a non-transitory computer readable medium, the set of instructions when loaded and executed by a processor, causing the processor to:

• apply a first current profile to a solenoid drive to perform a first injection process by moving the armature toward the pole piece to the hydraulic stop and inject a predefined injection quantity through a gap between the movable armature and the pole piece into a cylinder of an internal combustion engine;
• determine a first value of a system parameter indicative of a relationship between an actual injected fuel quantity and the predefined fuel quantity, wherein the system parameter measures an operational variable of the cylinder;
• determine, on the basis of the determined first value of the system parameter, whether the actual injected fuel quantity is smaller than the predefined fuel quantity by a predefined amount corresponding to a disparity between a magnetic force exerted on the armature in the direction of the pole piece and the hydraulic stop caused by an opposite hydraulic force exerted on the armature by fuel;
• and
• if it was determined that the quantities differ by the predefined amount, apply a second current profile to the solenoid drive to perform a second injection process;
• wherein the second current profile, in comparison with the first current profile, exerts a lower magnetic force on the armature in the direction of the pole piece.