Method and circuit configuration for protecting a heated temperature-dependent sensor resistor against overheating

US5616843A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Ludwig Schifferl · Pentling, DE
• Andreas Wildgen · Nittendorf, DE

Key dates

• Filing date: Mar 25, 1996
• Grant date: Apr 1, 1997
• Expiry date: Mar 25, 2016

Classification

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

Abstract

A temperature detector resistor and a sensor resistor are disposed in an intake manifold of an internal combustion engine. The two resistors each belong to a respective bridge branch of a measuring bridge having a bridge diagonal which is led to a first differential amplifier. A current in the bridge is adjusted in such a way that the sensor resistor always has a prescribed overtemperature. Due to backfires in the intake manifold, damage can occur to the sensor resistor due to sudden strong heating of the temperature detector resistor as a consequence of a strong rise in current. In order to avoid such damage, a third bridge branch is connected in parallel with the two bridge branches. The third bridge branch has a tap which is supplied, as is another tap, to inputs of a second differential amplifier having an output signal influencing the bridge current in such a way that the current is limited to a prescribed value. The device is applicable in internal combustion engines.