Method and apparatus to measure the operating temperature of solid electrolyte-type gas sensors

US4419190A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Hermann Dietz · Gerlingen, DE
• Ferdinand Grob · Besigheim, DE
• Klaus Muller · Tamm, DE
• Lothar Raff · Waiblingen, DE
• Franz Rieger · Aalen, DE
• Hans-Martin Wiedenmann · Stuttgart, DE

Key dates

• Filing date: Mar 12, 1982
• Grant date: Dec 6, 1983
• Expiry date: Mar 12, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G05D23/24
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

To provide for temperature measurement of a solid electrolyte polarographic gas composition sensor, an ac signal is superimposed from an ac voltage source (2) on the applied voltage from a voltage source (1) if the sensor is a polarographic sensor, the ac signal being separated from the output by a filter combination (6, 7), the dc output being evaluated as usual, and the ac output being rectified in a rectifier (9) to obtain a measure of the temperature since the ac resistance (R.sub.alt) is highly temperature dependent (see FIG. 3). The ac preferably is about 10% of the applied dc voltage, so that the voltage swing of the ac potential falls well within the linear range of output current with respect to voltage (see FIG. 2). The output from the ac channel (7, 9) to evaluate the temperature signal can be connected to a control loop circuit (10, 11), including a heater (11) to heat the sensor to maintain a uniform temperature thereof.