GAS SENSOR FOR NATURAL GAS ENGINE

摘要

PROBLEM TO BE SOLVED: To enable highly accurate air-fuel ratio control by preventing sensor output from deviating due to H2 in exhaust gases peculiar to a natural gas engine and improving detection accuracy. SOLUTION: An outside electrode 23 to be exposed to exhaust gases is provided at the outer surface of an oxygen ion conductive solid electrolyte 21, and an inside electrode 22 to be exposed to gaseous oxygen of reference concentration is provided at the inner surface. A protective coating layer 24 to cover the surface of the outside electrode 23 is provided and constituted of a porous film with an average pore diameter of 1000 Å or more. As the difference in diffusing steed between H2 and O2 becomes sufficiently small with an average pore diameter of 1000 Å, and the outside electrode 23 does not become richer in H2 than reality it is possible to eliminate the effects of H2 to sensor output and to prevent output deviations.