Measuring sensor for determining the oxygen content of gas mixtures

US5474665A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Karl-Hermann Friese · Leonberg, DE
• Hermann Dietz · Gerlingen, DE
• Hermann Fischer · Augsburg, DE
• Manfred Koeder · Gerlingen, DE
• Werner Gruenwald · Gerlingen, DE
• Ulrich Eisele · Stuttgart, DE

Key dates

• Filing date: Sep 15, 1994
• Grant date: Dec 12, 1995
• Expiry date: Sep 15, 2014

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02B1/04
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The invention relates to a measuring sensor having pump reference for measuring the oxygen content of gas mixtures, particularly exhaust gases of internal combustion engines. The sensor includes a measuring cell (A) and a reference cell (B) each having a pair of electrodes, with one of each respective pairs of electrodes being common to the two cells, and having a fixed electrolyte. Reference cell (B) has defined therein an internal oxygen reference zone which is hermetically sealed from the gas mixture and which is connected to the atmosphere by way of a pressure-equalization line. The measuring cell (A) and the reference cell (B) can be heated by heating apparatus to a temperature at which the fixed electrolyte has an ionic conductivity which is sufficiently high. The heating apparatus and a porous insulation are advantageously disposed in the vicinity of the electrode of the reference cell which is not in common with the measuring cell and which is porous so that the porous insulation, together with the porous electrode, form the internal oxygen reference zone and, together with the porous electrode and its porous conductor track, form the pressure-equalization line.