Abstract: A method and a device for charging a capacitive actuator are described. The capacitive actuator, in particular for a fuel injection valve of an internal combustion engine, is charged or discharged with different charging and discharging times. In order to shorten the charging time, the capacitance of the recharging capacitor which is dimensioned for a maximum charging time is reduced at a predefined time during the charging process. Two exemplary embodiments of a device for carrying out the method are explained in more detail.

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 capacitive actuator (P), especially for a piezoelectrically operated injection valve for an internal combustion engine, is short-circuited by a discharge switch (M) after an actuation, the controlling input of the discharge switch (M) being connected to the actuator (P) so that the discharge switch (M) in case of a failure of the external control, is automatically rendered conductive by the actuator voltage (UP) and the actuator (P) is therefore automatically 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 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 control element, in particular a piezoelectrically operated fuel injection valve in an internal combustion engine, is charged, in order to compensate for stochastic reactions in the internal combustion engine, with a constant nominal voltage applied to a series circuit that includes a charge capacitor and a charge reversal capacitor, and it is discharged into the charge reversal capacitor to a prescribed voltage value. The remaining residual charge of the control element is charged into the charge capacitor via a limiter path.

Abstract: The device drives one or more capacitive actuators with a control circuit. The device has a series circuit with a charging capacitor, a discharging capacitor, an electric coil, and the one or more actuators each with an associated selector switch. A discharging switch has a drain terminal connected to the node point between the two capacitors, and a source terminal connected via decoupling diodes to the drain terminals of the selector switches.

Abstract: A short circuit between a negative pole GND and a capacitive actuator in a circuit with a charging capacitor, a recharging capacitor, a recharging coil and a selector switch is determined by calculating a value corresponding to the quantity of charge QL flowing off from the recharging capacitor during a charging operation. The quantity of charge is compared with an integral of current i flowing during the charging operation via the selector switch assigned to the actuator. A short circuit of the actuator to the negative pole is diagnosed when the integral is smaller than k*QL (k<1).

Abstract: A device and a method for driving at least one capacitive actuator, in particular a piezoelectrically operated fuel injection valve of an internal combustion engine, by a microprocessor-controlled control circuit. The device has a charging capacitor which can be recharged by an energy source, which charges the at least one actuator via switches controlled by the control circuit, and into which the actuator is discharged again.

Abstract: A method of driving at least one capacitive actuator with a charge voltage. From a charge quantity .DELTA.Q supplied to the actuator and from the actuator voltage U.sub.p applied to the actuator after the charging operation is terminated, the actuator capacitance is calculated by the equation C.sub.p =.DELTA.Q/U.sub.p. From these values, the energy E.sub.actual =0.5*C.sub.p *U.sub.p.sup.2 =0.5*.DELTA.Q*U.sub.p is calculated. The charge voltage is regulated such that the energy actually supplied is equivalent to a specified desired value.

Abstract: A capacitive control element is charged with a defined charging voltage Uc. From a stored mapping KF, the instantaneous control element capacitance Cp is determined from the charge voltage Uc and a control element voltage Up. In addition, energy E supplied to the control element is determined from the charge voltage Uc and the control element capacitance Cp. According to a deviation of energy E fed to the control element from a stipulated amount of energy Ev, the charge voltage Uc for a next drive process of the control element is regulated. The same process occurs for additional control elements.

Abstract: In a driving operation, a capacitive actuator is charged from a series circuit of two capacitors having a charging voltage. An actuator voltage established at the actuator is controlled to a prescribed desired value in a course of a subsequent driving operation; the same procedure occurs for further actuators.

Abstract: A power MOSFET switch is connected in parallel to a capacitive actuator for the purpose of protecting the actuator against over-voltage. The protective power MOSFET switch is rendered conductive by a supplemental circuit when the actuator voltage exceeds a predetermined threshold limit voltage or when the control circuit emits a corresponding signal.

Abstract: A device for driving at least one capacitive actuator contains two capacitors C1 and C2 connected in parallel. The two parallel-connected capacitors C1, C2 are charged to an output voltage U.sub.SNT of a voltage source SNT. The actuator is charged with a voltage U.sub.C1+C2 =2*U.sub.SNT by the capacitors, and thereafter discharged into the capacitors, which are again connected in parallel and are subsequently recharged to the output voltage U.sub.SNT of the voltage source SNT.

Abstract: A device for driving at least one capacitive actuator contains a charge capacitor C1 and a discharge capacitor C2. According to the method, the actuator is charged with a desired voltage U.sub.s by the capacitors C1+C2 connected in series, and is then discharged into the discharge capacitor C2. The charge capacitor is then recharged to a voltage U.sub.C1 =U.sub.s -U.sub.C2 by a voltage source which can be regulated.

Abstract: One or more capacitive actuators are controlled by a device that charges the actuators via a capacitor and from a switched mode power supply SMPS that operates according to the flyback converter principle. The secondary coil of the switched mode power supply functions as the charging coil and the discharging coil, i.e., it simultaneously undertakes the function of the large, heavy charging coil. This saves space and weight.