Method for controlling pressure in a high-pressure region of an internal combustion engine

1. A method for controlling pressure in a high-pressure region of an internal combustion engine by adjusting a quantity of fuel flowing out from the high-pressure region into a low-pressure region via an injector that comprises a control valve adjusted by a piezo actuator, and a control chamber, wherein the method comprises:

charging the piezo actuator with a first current pulse to move the control valve from a closed position into a partially open position such that fuel flows out of the high-pressure region into the low-pressure region,

discharging the piezo actuator with a second current pulse to move the control valve into the closed position, and

partially discharging the piezo actuator with a third current pulse after the first current pulse and before the second current pulse.

2. The method of claim 1 , wherein fuel is not injected into the combustion chamber of the internal combustion engine during the charging, discharging, and partially discharging steps.

3. The method of claim 1 , wherein the third current pulse is selected that provides an essentially stable control valve position.

4. The method of claim 1 , wherein the third current pulse is selected that provides an essentially stable pressure difference in the control chamber with respect to the pressure in the high-pressure region.

5. The method of claim 1 , comprising commencing the third current pulse at a time at which a pressure difference between the control chamber and the high-pressure region corresponds to a predetermined value.

6. The method of claim 1 , comprising setting at least one of an amplitude, a duration, and a temporal progression at least of one of the first, second, and third current pulses.

7. The method of claim 1 , comprising:

specifying a desired value for the electrical voltage at the piezo actuator,

monitoring an electrical voltage at the piezo actuator, and

adjusting the electrical voltage at the piezo actuator to the desired value by controlling the piezo actuator with a control signal.

8. The method of claim 7 , wherein the third current pulse is the control signal.

9. The method of claim 7 , wherein the control signal is is dependent upon the third current pulse.

10. The method of claim 7 , wherein the piezo actuator is actuated with the control signal after the third current pulse and before the second current pulse.

11. The method of claim 1 , comprising:

monitoring an electrical voltage at the piezo actuator,

evaluating the monitored voltage, and

immediately discharging the piezo actuator in in response to detecting that an increase in voltage at the piezo actuator exceeds a predetermined value.

12. The method of claim 7 , comprising continuously sampling the electrical voltage at the piezo actuator at a sampling rate greater than or equal to 10 kHz.

13. The method of claim 7 , comprising continuously sampling the electrical voltage at the piezo actuator at a sampling rate greater than or equal to 100 kHz.

14. A control system of a motor vehicle having an internal combustion engine with a high-pressure region and a low-pressure region

said control system comprising:

an injector comprising a control valve adjusted by a piezo actuator, and

a control device comprising a processor and instructions stored in non-transitory computer-readable media and executable by the processor to control pressure in the high-pressure region of the internal combustion engine by adjusting a quantity of fuel flowing out from the high-pressure region into the low-pressure region via the injector by:

charging the piezo actuator with a first current pulse to move the control valve from a closed position into a partially open position such that fuel flows out of the high-pressure region into the low-pressure region,

discharging the piezo actuator with a second current pulse to move the control valve into the closed position, and

partially discharging the piezo actuator with a third current pulse after the first current pulse and before the second current pulse.

15. The control system of claim 14 , wherein fuel is not injected into the combustion chamber of the internal combustion engine during the charging, discharging, and partially discharging steps.

16. The control system of claim 14 , wherein the third current pulse is selected that provides an essentially stable control valve position.

17. The control system of claim 14 , wherein the third current pulse is selected that provides an essentially stable pressure difference in the control chamber with respect to the pressure in the high-pressure region.

18. The control system of claim 14 , wherein the control device commences the third current pulse at a time at which a pressure difference between the control chamber and the high-pressure region corresponds to a predetermined value.

19. The control system of claim 14 , wherein the control device sets at least one of an amplitude, a duration, and a temporal progression at least of one of the first, second, and third current pulses.

20. The control system of claim 14 , wherein the control device is further programmed to:

specify a desired value for the electrical voltage at the piezo actuator,

monitor an electrical voltage at the piezo actuator, and

adjust the electrical voltage at the piezo actuator to the desired value by controlling the piezo actuator with a control signal.