Robert Boschgmbh

Karl H Friese

Hermann Dietz

Ernst Linder

Klaus D Muller

Franz Rieger

Helmut Maurer

Friedrich J Esper

Harald Reber

Gerhard Holfelder

Barbara Beyer

Hermann Ziener

To permit a layer construction, which is inexpensive and lends itself to mass production manufacture, a solid electrolyte body, in plate-like construction, with electrodes at either thereof is positioned in a housing with a portion thereof extending in the region where it is exposed to gases to be sensed; a porous cover is applied on one of the electrodes, the porous cover having a predetermined diffusion resistance to oxygen molecules. A flat insulating plate of approximately the same dimension as the solid electrolyte plate is positioned flat thereagainst, and a flat layer-like electrical heating element is secured on the flat insulating plate or, in other embodiments, against another insulating covering on the other side of the heating element as well, close to the electrodes and adjacent the plane surfaces of the body. The heating element and the electrodes of the sensing element are carried out as conductive tracks for connection to respective sources of operating or biassing potential and, with respect to the sensing electrodes, to an evaluation circuit.

Electrochemical oxygen sensor, particularly for use with exhaust gases

To facilitate manufacture of a sensor, particularly a polarographic sensor which has no sealing or heat expansion difficulties and only low heat capacity in the measuring range and electrical connections, a solid electrolyte (17) is formed as a plate extending transversely across a bottom opening (13) of a preferably ceramic tube (11), the plate having two electrodes (16,21) applied to its major sides. The side facing the opening (13) is covered with a ceramic layer (20) having a predetermined diffusion or migration resistance to oxygen molecules. The electrical connections are formed by a conductive track (15) extending on the inside of the ceramic tube, in contact with the sensing electrode on one side of the plate; and a counter head (23) connected to a conductive bolt or pin (24) and resiliently spring pressed against the electrode, and holding the plate (17) and the diffusion barrier (20) thereon in position in the sensor. The test gas is applied to the diffusion resistance layer through a ceramic heat storage plate, for instance, having openings therethrough, which has a film-type heater applied thereto, connected to a current source by conductive tracks (31, 31'; 32, 32') positioned on the outside of the ceramic tube.

Gas sensor construction, particularly to determine oxygen content

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Leonberg, Germany

Karl H Friese