Method and apparatus for controlling a capacitive actuator

US6472796B1 · kind B1 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Christian Hoffmann · Leonberg, DE
• Hellmut Freudenberg · Bad Abbach, DE
• Hartmut Gerken · Nittendorf, DE
• Martin Hecker · Laimerstadt, DE
• Richard Pirkl · Regensburg, DE

Key dates

• Filing date: Feb 25, 2000
• Grant date: Oct 29, 2002
• Expiry date: Feb 25, 2020

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02N2/067
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A method for controlling a capacitive actuator includes the steps of determining an energy applied to an actuator, measuring an actuator voltage present at the actuator, and inferring a functional state of the actuator by using the energy and the actuator voltage. A capacitive actuator is fed energy and the actuator voltage present at the actuator is measured. The energy and the comparison of the actuator voltage with reference values are used to infer a functional state, for example, either faults or correct function of the actuator or injection valve. Furthermore, the actuator voltage is used to infer an actuator stroke. The method is based on actuator characteristics. The invention also includes a circuit for controlling a capacitive actuator having a driving circuit with a main switch, a charging capacitor, a first series circuit including an oscillating coil, an auxiliary switch, and a second series circuit having a discharging switch, a charging switch, and a diode to be connected to the actuator, and a control device having a program and a family of characteristics with actuator characteristics defining characteristic curves, reference values, and correction factors.