Gas sensor

摘要

Because of their response rate, which is in the millisecond range, oxygen sensors based on the sputtered titanate layers are particularly suitable as lambda sensors for cylinder selective control of air number. Since chlorohydrocarbons and chlorine gas can irreversibly damage the titanate layers which are only a few mu m thick, these exhaust gas components should under no circumstances come into contact with the oxygen-sensitive element. In a sensor according to the invention, a porous protective layer (34) covers the gas-sensitive element (33). The protective layer (34), produced with the aid of a screen printing process, consists of a material which chemically binds a gas which is detrimental to the sensor element (33). A protective layer (34) consisting of titanium dioxide, barium titanate or calcium titanate can, for example, prevent interaction of chlorohydrocarbons and chlorine gas with the strontium titanate used in fast oxygen sensors. <IMAGE>