Robert Boschgmbh

Hermann Fischer

Karl-Hermann Friese

Ernst Linder

Helmut Weyl

Helmut Maurer

Werner Gruenwald

Ulrich Eisele

Leo Steinke

Hermann Dietz

Friedrich J Esper

Lothar Weber

Peter Scharner

Rainer Noack

Hans-Ulrich Gruber

Wolfgang Heinemann

Manfred Koeder

Gunter Knoll

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.

Measuring sensor for determining the oxygen content of gas mixtures

To simplify manufacture and assembly of a temperature-compensated titanium dioxide oxygen sensor, the sensor (9, 9') is applied as a layer on the thermistor body (1), with an electrode (8) interposed; preferably, the thermistor body is densely sintered titanium dioxide, in the form of a closed tube (1, 1') which may have a central opening (FIG. 1: 2) therethrough, with the sensor body being porous titanium dioxide and located either on the inside (FIG. 1) surface of the thermistor body (1) or on the outside (FIG. 2) surface, and supported by the thermistor body, which forms the substrate and support surface for the sensor body.

Temperature-compensated, oxygen-content gas sensor

To improve operation and output voltage, particularly at 400.degree. C. and less, an oxygen sensor, especially adapted to determine oxygen content of automotive exhaust gases, is constructed by utilizing two electrodes applied on a body of stabilized zirconium dioxide, for example a closed tube, by making an electrode exposed to the exhaust gases in form of a mixture of finely dispersed ceramic material and a platinum-rhodium alloy, the ceramic material being present at about 40% (by volume) and 60% (by volume) platinum-rhodium alloy of 50-94% platinum and 50-6% rhodium (by weight). The second electrode, exposed to a reference gas comprises an alloy of palladium and another noble metal in a ratio of about 19-90% (by weight) Pd and 81-10% (by weight) noble metal. This electrode may also contain up to 40% (by volume) finely dispersed ceramic material. The electrode exposed to the exhaust gases is covered with a porous coating. The electrodes can be applied as aqueous or organic solutions of soluble noble metal compounds or suspensions, colloidal suspensions, with organic solvents, and the like, and subsequent sintering.

Oxygen content exhaust gas sensor, and method of its manufacture

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Stuttgart, Germany

Hermann Fischer