Abstract: An improved structure of a gas sensor is provided which may be employed in an oxygen measuring device of an air-fuel ratio control system measuring an oxygen content in exhaust gasses of an internal combustion engine of automotive vehicles. The gas sensor includes a sensing unit which is disposed in a housing and has defined in an end portion thereof a reference gas chamber to be filed with a reference gas used in determining a given gas component content in gasses, a metallic cover installed on the housing to cover the other end portion of the sensing unit; and a cylindrical insulation porcelain disposed in the metallic cover. The insulation porcelain has a groove formed on an outer peripheral wall thereof to define a portion of a reference gas passage communicating between an air inlet formed in the metallic cover and the reference gas chamber.

Abstract: An improved structure of a gas sensor is provided which may be employed in an oxygen measuring device of an air-fuel ratio control system measuring an oxygen content in exhaust gasses of an internal combustion engine of automotive vehicles. The structure includes a holding mechanism disposed within an air cover installed on an end of a sensor housing to cover a base of a gas-sensing element. The holding mechanism is made of a spring member or a rigid member to retain an insulation porcelain within the air cover elastically or rigidly. The use of the holding mechanism provides for ease of installation of the insulation porcelain, results in an increase in durability of the gas sensor, and allows the overall size of the gas sensor to be decreased.

Abstract: An improved structure of a gas sensor is provided which may be employed in an oxygen measuring device of an air-fuel ratio control system measuring an oxygen content in exhaust gasses of an internal combustion engine of automotive vehicles. The structure includes a holding mechanism disposed within an air cover installed on an end of a sensor housing to cover a base of a gas-sensing element. The holding mechanism is made of a spring member or a rigid member to retain an insulation porcelain within the air cover elastically or rigidly. The use of the holding mechanism provides for ease of installation of the insulation porcelain, results in an increase in durability of the gas sensor, and allows the overall size of the gas sensor to be decreased.

Abstract: An improved structure of a gas sensor is provided which may be employed in an oxygen measuring device of an air-fuel ratio control system measuring an oxygen content in exhaust gasses of an internal combustion engine of automotive vehicles. The gas sensor includes a sensing unit which is disposed in a housing and has defined in an end portion thereof a reference gas chamber to be filed with a reference gas used in determining a given gas component content in gasses, a metallic cover installed on the housing to cover the other end portion of the sensing unit; and a cylindrical insulation porcelain disposed in the metallic cover. The insulation porcelain has a groove formed on an outer peripheral wall thereof to define a portion of a reference gas passage communicating between an air inlet formed in the metallic cover and the reference gas chamber.

Abstract: A lead wire for a sensor has a conductor unit including at least stainless steel wires and copper wires. By setting the cross-sectional percentage of the stainless steel wires in the conductor unit within the range of 30 to 70%, it is possible to obtain a lead wire having low electrical resistance, and high flexibility, tensile strength and elasticity. There are preferred values in hardness and heat treatment of the stainless steel wires. The copper wires are preferably coated with an antioxidant film. The lead wire may include hybrid wires stranded together and obtained by integrally molding or forming stainless steel and copper. It is preferable that the lead wire is coated with an insulating coating material such as a Teflon type resin.

Abstract: An oxygen concentration detector has a detecting element comprising a solid electrolyte inserted into a housing and heating means for heating the detecting element, and the outer surface of the detecting element is provided with a surface layer, the contact angle of the surface layer being larger than the contact angle of the outer surface of the detecting element with which the surface layer directly contacts.

Abstract: An air-fuel ratio sensor comprises an oxygen concentration sensing element, a housing for holding this oxygen concentration sensing element, and protecting covers with gas holes. The protecting covers comprises an inside cover disposed closely to the oxygen concentration sensing element, and an outside cover surrounding the outside cover. Flange-like peripheral portions, formed on the protecting covers, are fixed to the abutting face of the housing by a caulking operation. These flange-like peripheral portions are disposed alternately along a same closed curve around the oxygen concentration sensing element, so that they are not overlapped with each other.