Robert Boschgmbh

Juergen Boss

Johannes-Joerg Rueger

Klaus Zimmermann

Andreas Hoyler

Klaus Zimmerman

A fuel injection system having a fuel injection valve in which an injection valve member is urged in an opening direction counter to a closing force by pressure in a pressure chamber which generated by a high-pressure fuel pump driven by a cam. A control valve is actuated by a piezoelectric actuator triggered by an electric control unit by which a communication of the pressure chamber with a relief chamber is controlled. When the control valve is closed, the pressure chamber is disconnected from the relief chamber. The control valve has a control valve member coupled with the actuator via a hydraulic coupler. The actuator, after a charging phase, communicates with an associated voltage meter, and the voltage between the electrical terminals of the actuator is monitored for detecting the function of the control valve.

Fuel injection device for internal combustion engine

A method for controlling an injector is described, where the trigger signal for the actuator is controlled as function of the amplitude and the duration. The actuator, using an hydraulic coupler, actuates a control valve which, at a low voltage, operates in a ballistic mode and opens up an opening cross-section to an inlet channel. The opening cross-section becomes smaller with increasing trigger voltage, and the fuel quantity to one injected increases. The control valve is brought from ballistic mode to nonballistic mode via the amplitude and duration of the trigger voltage. The delivery duration and the amplitude of the trigger voltage are tuned to each other so that one or several jumps may occur, during which a switch is made from one voltage value to another voltage value, and from one delivery duration to another delivery injection. A piezoelectric element is preferably used as an actuator.

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Kornwestheim, Germany

Juergen Boss