The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 02, 2004
Filed:
Jul. 09, 2001
Johannes-Jörg Rueger, Vaihingen/enz, DE;
Matthias Mrosik, Stuttgart, DE;
Marco Gangi, Esslingen, DE;
Udo Schulz, Vaihingen/enz, DE;
Robert Bosch GmbH, Stuttgart, DE;
Abstract
A method and a device are described for detecting a fault current across a piezoelectric actuator ( ) of an injector or its high voltage supply lead ( ). Because the fault current upon contact with a person, for example, is relatively small compared to the useful current that charges or discharges the actuator, direct measurement of the current is not reliable. Therefore, it is suggested that, during the injection or in an injection pause, when the piezoelectric actuator ( ) is charged, the voltage variation or a change in voltage (dU) be measured and the difference be compared to a predefined threshold value (S). When the threshold value (S) is exceeded, a fault message is produced, the voltage source is shut off, and/or the piezoelectric actuator ( ) is discharged. The measured fault can be weighted using a counting algorithm. The method thus provides maximum protection upon contact, in particular for service personnel.