Device for burnoff of a measuring resistor

US4373383A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Gunther Plapp · Echterdingen, DE
• Peter Romann · Stuttgart, DE

Key dates

• Filing date: May 21, 1980
• Grant date: Feb 15, 1983
• Expiry date: May 21, 2000

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T10/40
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A device is proposed for burnoff of a measuring resistor, in particular a hot wire or hot film in the air flow rate meter of an internal combustion engine, wherein the occurrence of the burnoff procedures, their intensity, and their duration can be controlled in open-loop fashion. Primarily the initiation of a burnoff procedure is made dependent upon how often the driving or ignition circuit of a vehicle equipped with the engine is shut off. The initiation of the procedure can be controlled in addition in accordance with operational characteristics, for instance. The realization substantially includes a counter following the driving switch and having an associated comparator, wherein the threshold value of this comparator is controllable both in accordance with operational characteristics and, if needed, in accordance with time. Furthermore a timing element is provided with the aid of which the onset of a burnoff procedure can be delayed after the shutoff of the engine. The different intensity of a burnoff procedure can be realized via the parallel disposition of different resistors with the bridge resistors, in order to obtain a predefined bridge imbalance.