Device and method for controlling an injection valve

1. A method for setting operational parameters of a fuel injector for an internal combustion engine of a motor vehicle, the fuel injector having a coil drive for moving a closing element, the method comprising:

carrying out a plurality of measurements, wherein each measurement comprises:

determining a measurement-specific maximum current value;

applying a voltage pulse to the coil drive of the fuel injector;

detecting a time curve of the current intensity of a current flowing through the coil drive;

ending the voltage pulse when the detected current intensity reaches the maximum current value; and

storing the time curve of the detected current intensity;

generating a plurality of differential curves each based on two stored time curves of the detected current intensity for successive measurements; and

determining a peak current for driving the actuator of the fuel injector based at least in part on the plurality of differential curves; and

operating the coil at the determined peak current.

2. The method as claimed in claim 1 , wherein each measurement of the plurality of measurements further comprises:

detecting a time curve of the movement of the closing element; and

storing the time curve of the detected movement; and

wherein determining the peak current for the fuel injector depends at least in part on the time curves of the detected movement.

3. The method as claimed in claim 1 , wherein determining the peak current for the fuel injector includes determining a saturation current value at which the fuel injector is in saturation.

4. The method as claimed in claim 1 , wherein determining a measurement-specific maximum current value includes increasing the measurement-specific maximum current value for a following measurement by a predetermined value as compared with the measurement-specific maximum current value of the immediately preceding measurement.

5. The method as claimed in claim 1 , further comprising

generating a graphic representation of the time curves of the detected current intensities, the time curves of the detected movements, and the plurality of differential curves, and

wherein the graphic representation includes a reference point for the time in each measurement at which the voltage pulse was ended.

6. A device for ascertaining parameter values for a fuel injector for an internal combustion engine of a motor vehicle, said fuel injector having a coil drive for moving a closing element, the device comprising:

an application unit for applying a voltage pulse to the coil drive of the fuel injector;

a detection unit for detecting a time curve of the current intensity of a current flowing through the coil drive or a time curve of the movement of the closing element;

a memory for storing the detected time curves; and

a processor for:

determining a plurality of differential curves based on stored time curves of the detected current intensities;

generating a plurality of differential curves each based on two stored time curves of the detected current intensity for successive measurements; and

determining a peak current for driving the actuator of the fuel injector based at least in part on the plurality of differential curves.

7. A motor controller for an internal combustion engine of a motor vehicle, the internal combustion engine comprising at least one fuel injector having a coil drive for moving a closing element, the device comprising:

an application unit for applying a voltage pulse to the coil drive of the fuel injector;

a detection unit for detecting a time curve of the current intensity of a current flowing through the coil drive or a time curve of the movement of the closing element;

a memory for storing the detected time curves; and

a processor for:

determining a plurality of differential curves based on stored time curves of the detected current intensities;

generating a plurality of differential curves each based on two stored time curves of the detected current intensity for successive measurements; and

determining a peak current for driving the actuator of the fuel injector based at least in part on the plurality of differential curves;

wherein the application unit operates the coil at the determined peak current.

8. A computer program for ascertaining parameter values for a fuel injector for an internal combustion engine of a motor vehicle, the fuel injector having a coil drive for moving a closing element, wherein the computer program, when it is executed by a processor, is configured to carry out a method comprising:

carrying out a plurality of measurements, wherein each measurement comprises:

determining a measurement-specific maximum current value;

applying a voltage pulse to the coil drive of the fuel injector;

detecting a time curve of the current intensity of a current flowing through the coil drive;

ending the voltage pulse when the detected current intensity reaches the maximum current value; and

storing the time curve of the detected current intensity;

generating a plurality of differential curves each based on two stored time curves of the detected current intensity for successive measurements;

determining a peak current for driving the actuator of the fuel injector based at least in part on the plurality of differential curves; and

operating the coil at the determined peak current.