Solid pole oxygen sensor and its manufacturing process

A process of manufacturing a solid pole oxygen sensor, said process comprising the steps of:

• forming a solid pole by burying one end of a lead wire in a powder mixture and sintering it with the upper end of the lead wire exposed thereabove;
• forming an internal electrode on the outside surface of the solid poly with the internal electrode electrically connected to the lead wire;
• compression molding a solid electrolyte into a substantially cylindrical shape, with a projection circular in transverse cross-section and of small diameter, on the top, with the upper end of the lead wire connected to the outside surface of the solid electrolyte;
• forming an external electrode on the outside surface of the solid electrolyte to produce an oxygen sensor element;
• forming on the cylindrical side surface of a substantially cylindrical ceramic insulator with a recess, circular in transverse cross-section and of complementary shape to that of the projection, in the bottom thereof, a first longitudinally extending electroconductive zone and a second longitudinally extending electroconductive zone diametrically opposed to and nonconductive with the first zone;
• and
• adhesively securing the projection on the oxygen sensor element into the recess on the insulator with the first electroconductive zone electrically connected to the upper end of the lead wire and the second electroconductive zone electrically connected to the external electrode.

A process of manufacturing a solid pole oxygen sensor, said process comprising the steps of:

• forming a solid pole by burying one end of a lead wire in a powder mixture and sintering it with the upper end of the lead wire exposed thereabove;
• forming an internal electrode on the outside surface of the solid pole with the internal electrode electrically connected to the lead wire;
• compression molding under a pressure of 600 to 2000 kg/cm.sup.2 a solid electrolyte into a substantially cylindrical shape, with a projection, circular in transverse cross-section and of smaller diameter, on the top, about the solid pole with the upper end of the lead wire connected to the outside surface of the solid electrolyte;
• drying the compression molded solid electrolyte with the solid pole therein for 15 to 30 minutes at about 200.degree. C. in the atmosphere;
• firing the compression molded solid electrolyte with the solid pole therein for 2 to 3 hours at 1350.degree. to 1500.degree. C. in a reducing atmosphere of inert gas;
• forming an external electrode on the outside surface of the solid electrolyte to produce an oxygen sensor element;
• forming on the cylindrical side surface of a substantially cylindrical ceramic insulator with a recess, circular in transverse cross-section end of complementary shape to that of the projection, in the bottom thereof, a first longitudinally extending electroconductive zone and a second longitudinally extending electroconductive zone diametrically opposed to and nonconductive with the first zone;
• and
• adhesively securing the projection on the oxygen sensor element into the recess on the insulator with the first electroconductive zone electrically connected to the upper end of the lead wire and the second electroconductive zone electrically connected to the external electrode.

A solid pole oxygen sensor comprising:

• a lead wire;
• a solid pole with one end of said lead wire buried therein, the other end of the wire being exposed;
• an internal electrode on the outside surface of said solid pole and electrically connected to said lead wire;
• a solid electrolyte enclosing said solid pole and being connected to the other end of said lead wire at its outer surface;
• an external electrode on the outside surface of said solid electrolyte;
• a ceramic insulator having formed thereon one electroconductive zone and another electroconductive zone spaced therefrom and nonconductive thereto:
• a projection on the top of said solid electrolyte;
• a recess, of profile matching that of the projection, on the bottom of the ceramic insulator;
• said projection being fitted into said recess for joining the element and the insulator;
• and,
• the first electroconductive zone on the insulator is connected to the lead wire, and the second electroconductive zone is connected to the external electrode.

A solid pole oxygen sensor comprising:

• a lead wire;
• a solid pole, one end of said lead wire being buried in said solid pole and the other end thereof being exposed exterior of said solid pole;
• an internal electrode on the outside surface of said solid pole and externally connected to the lead wire;
• a solid electrolyte enclosing said solid pole, said electrolyte being substantially cylindrical with a centrally disposed projection, of circular transverse cross-section and smaller diameter, on the top thereof, the upper outside surface of said projection being connected to the other end of said lead wire;
• an external electrode on the outside surface of the solid electrolyte;
• a substantially cylindrical ceramic insulator having a first longitudinally extending electroconductive zone thereon and a second longitudinally extending electroconductive zone thereon, said second zone being diametrically opposed to and nonconductive with said first zone, said first zone being connected to the lead wire and said second zone being connected to the external electrode, means defining a centrally disposed recess, circular in transverse cross-section and of complementary shape to that of the projection cross-section in the bottom of the insulator, said projection being adhesively secured within said recess.