Gas component detection apparatus

摘要

A gas component detection apparatus for detecting gaseous components of exhaust gases from a combustion device. There is provided a gas component detecting element composed of semiconductive metal oxides and having its outer surface partly exposed to the exhaust gases. A catalyst layer is carried on the larger part of the latter outer surface of the detecting element. A pair of electrodes are provided for sensing the electric resistance exhibited at the portion of the detecting element which carries the catalyst layer. Also another electrode is provided for cooperating with one of the above pair of electrodes to detect the electric resistance exhibited at the portion of the detecting element which does not carry the catalyst layer. The former portion of the detecting element exhibits variable electric resistances resulting from concentrations of the gaseous components and the temperatures of the exhaust gases, while the latter portion thereof exhibits variable electric resistances related mainly upon the temperatures of the exhaust gases. Consequently, an output signal reflecting substantially only the gaseous components of the exhaust gases is produced by offsetting both of the electric resistances separately sensed utilizing a suitable electric circuit.