MANUFACTURE OF MEASURING MACHINE MAINLY MEASURING OXYGEN CONCENTRATION IN WASTE GAS OF INTERNAL COMBUSTION ENGINE

摘要

1385464 Electro-chemical sensors ROBERT BOSCH GmbH 19 Jan 1973 [10 Feb 1972] 2810/73 Heading G1N A sensor for determining the oxygen content of exhaust gases comprises an ion-conducting solid electrolyte and an electron conducting layer located on at least a portion of one surface thereof, the layer being covered by a porous protective coating and any portion of the one surface which is not covered by the layer being covered by a gastight layer resistant to exhaust gases. The electron conducting layer is such as to have micropores or micro-cracks if its thickness exceeds 100 to 300Š extending therethrough so that the layer acts on the gas permeating through the layer to enable the gas to attain a thermodynamically stable equilibrium state. In one embodiment a solid electrolyte tube closed at one end has its outer surface covered by a platinum conducting layer and an electrode painted on its inner surface, the platinum layer being covered by a protective coating. In an alternative embodiment only the bottom portion of the solid electrolyte tube is covered with the platinum ion-conducting layer with the rest of the tube being covered by a gastight layer. The platinum layer is again covered with a protective coating which overlaps the gastight layer. Examples of materials for the solid electrolyte ion-conducting layer, protective coating and gastight layer are given and methods of making the sensors described.