LEAN SENSOR

PURPOSE:To improve impact resistance by mounting metal fittings connecting electrically to metallic electrodes formed on the inside and outside surfaces of an oxygen ion permeable solid electrolyte and fixing these within the leading end of a cylindrical insulation pipe. CONSTITUTION:An element I consisting of a solid electrolyte 1 is inserted into the stepped ring part 8a of an outside metal fitting 8, and an inside metal fitting 7 is fitted to the inside tapered part 1a of the element I. The above-mentioned assembled parts are inserted into an insulation pipe 6 having a metallic thin film layer 10 and a protection layer 11 on the outside circumference from the upper part thereof, and the part 8a of the fitting 8 is engaged with the detaining part 6a of the pipe 6. A retaining member 9 is inserted into the pipe 6 in such a way that the closing part 9b of said members comes to the leading end, and the part 8b is fitted to the part 1a of the element I. The electric current change generated between inside electrode 2 and the outside electrode 3 of the electrolyte 1 is detected by the fitting 7 and the fitting 8.