Method and apparatus for driving at least one capacitive control element
AssigneeSiemens Aktiengesellschaft
InventorsHellmut Freudenberg, Hartmut Gerken, Martin Hecker, Christian Hoffmann, Richard Pirkl, Günther Riedel
Life of this patent
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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.
Claims10
A method of driving at least one capacitive control element with a control circuit, which comprises:
- providing a series circuit of a charge capacitor and a charge reversal capacitor, the charge capacitor having a capacitance substantially greater than a capacitance of the charge reversal capacitor;
- selectively charging a capacitive control element with a nominal voltage applied to the series circuit of the charge capacitor and the charge reversal capacitor, and discharging the control element into the charge reversal capacitor, and thereby charging the charge reversal capacitor to a prescribed voltage value;
- and
- when the charge reversal capacitor has reached the prescribed voltage value, charging a remaining residual charge of the control element into the charge capacitor.
An apparatus for driving at least one capacitive control element, comprising:
- a charge capacitor connected between a positive pole and a negative pole of a voltage source;
- a first series circuit connected in parallel with said charge capacitor, said first series circuit including a charging switch and a discharging switch connected to the negative pole;
- a second series circuit connected in parallel with said discharging switch, said second series circuit including a charge reversal capacitor, a charge reversal coil, a first control element, and a first selection switch;
- for each further control element, a further series circuit connected in parallel with said first control element and said first selection switch, each said further series circuit respectively including a control element and a selection switch associated with said control element;
- a control circuit connected to and controlling all said switches;
- wherein said charge capacitor is dimensioned substantially larger than said charge reversal capacitor;
- a limiter path connected from a node between said charge reversal capacitor and said charge reversal coil to a node between said charge capacitor and said charging switch, said limiter path comprising a series circuit formed of a diode, which is forward biased in a direction of said charge capacitor, and a limiter switch.
Dependencies are inferred from the claim text.