Control device and method for controlling an injector

A method for controlling a fuel injector attached to an internal combustion engine by a control device, the control device comprising a control parameter calculation unit, an injection pulse calculation unit, an injection pulse compensation unit and at least one memory, the method comprising the steps

• determining, by the control parameter calculation unit, a target closing time for the fuel injector based on a fuel amount to be injected into the internal combustion engine;
• if the determined target closing time is larger than a maximum closing time of the fuel injector in ballistic operation;
• calculating, by the injection pulse calculation unit, a pulse duration for the fuel injector based on a characteristic curve of the fuel injector;
• outputting, by the injection pulse calculation unit, the calculated pulse duration to the fuel injector for injecting the fuel amount into the internal combustion engine;
• if the determined target closing time is equal to or smaller than the maximum closing time of the fuel injector in the ballistic operation;
• receiving, by the injection pulse compensation unit, a set of parameters correlating to the determined target closing time from the at least one memory;
• calculating, by the injection pulse compensation unit, a pulse duration for the fuel injector based on the received set of parameters;
• outputting, by the injection pulse compensation unit, the calculated pulse duration to the fuel injector for injecting the fuel amount into the internal combustion engine.

A method for adapting a pulse duration of a fuel injector attached to an internal combustion engine by an injection pulse learning unit in a learning mode of the internal combustion engine, the method comprising the steps:

• stepwise increasing a pulse duration of the fuel injector;
• detecting a closing time for each pulse duration;
• calculating a slope and an intercept between the pulse duration and the closing time of the fuel injector for each pulse duration;
• determining a closing time at which the calculated slope is equal to or smaller than a predetermined slope value and/or a closing time at which the calculated slope has a negative slope value as a maximum closing time of the fuel injector in ballistic operation;
• stopping the learning mode after determining the maximum closing time of the fuel injector in ballistic operation;
• and
• storing the calculated slopes and intercepts and the maximum closing time of the fuel injector in ballistic operation as a set of parameters in at least one memory.