Abstract: A method and an apparatus for charging at least one capacitive control element, in particular a fuel injection valve of an internal combustion engine, charge the capacitive control element with different charging times. In order to shorten a charging time, a charging process is interrupted at a predetermined time, and a tuned circuit is connected to a freewheeling circuit which contains the control element and a ringing or charge reversal coil. If the freewheeling circuit contains a further capacitor, the charging process is further shortened, and a portion of a charge energy is fed back into a charge source while the control element is being discharged.

Abstract: A method of diagnosing an actuator includes supplying a predeterminable amount of energy to an actuator through a charge-reversal circuit. Faulty functional statuses of the actuator and its supply lines and/or its drive circuits, short- or long-term interruptions, short-circuits within the actuator or its supply lines, or excessively low capacitance values may be deduced from a discrepancy between reference values and determined variables including actuator voltage, actuator current, and actuator charge. A short-circuit of an electrical connection within the actuator or an electrical connection between the drive circuit and the actuator can be deduced if the actuator voltage is less than a lower voltage value. An interruption in the electrical connection within is the actuator or an electrical connection between the drive circuit and the actuator may be deduced if an actuator peak current is less than a lower current value. An apparatus for performing the method is also provided.

Abstract: A capacitive actuator is driven with a control signal st. The duration ti of actual actuator actuation is compared with the duration tst of the control signal st. Proper operation is determined, and the actuator is assumed to be operating correctly, if the measured duration ti is within a range determined by the duration tst of the control signal.

Abstract: A method of diagnosing an actuator includes supplying a predeterminable amount of energy to an actuator through a charge-reversal circuit. Faulty functional statuses of the actuator and its supply lines and/or its drive circuits, short- or long-term interruptions, short-circuits within the actuator or its supply lines, or excessively low capacitance values may be deduced from a discrepancy between reference values and determined variables including actuator voltage, actuator current, and actuator charge. A short-circuit of an electrical connection within the actuator or an electrical connection between the drive circuit and the actuator can be deduced if the actuator voltage is less than a lower voltage value. An interruption in the electrical connection within the actuator or an electrical connection between the drive circuit and the actuator may be deduced if an actuator peak current is less than a lower current value. An apparatus for performing the method is also provided.