Abstract: A gas-sensing device is cooled down from 1470° C. to 457° C. after calcination when manufactured. The device comprises a solid electrolyte plate made of partially stabilized zirconia, a measurement electrode disposed on the plate to face an atmosphere of a gas to be measured, and a reference electrode disposed on the plate to face an atmosphere of a reference gas. A gas-permeable diffusion layer is laminated on the plate to cover the measurement electrode. A gas-non-permeable shield layer is laminated on the diffusion layer. A reference-gas-chamber forming plate is laminated on the solid electrolyte plate to form a reference gas chamber. One or more of the shield layer, diffusion layer, and reference-gas-chamber forming plate are made of a material that differs in a contraction percentage from the solid electrolyte plate by an amount of 0.3% or less.

Abstract: A nonfragile ad quickly activatable structure of a gas sensor element which may be built in a gas sensor employed in an air-fuel ratio control system for automotive vehicles for measuring the concentration of gas such O2, NOx, or CO. The gas sensor element is made of a lamination of a measurement gas electrode, a reference gas electrode, and a heater. The heater works to elevate the temperature of the gas sensor element up to a given value required to bring the gas sensor element into an activated condition. The heater includes a heater substrate, a heating element, and power supply leads. A minimum distance X between an edge of the heater substrate and an edge of the heating element meets a relation of 0.1 mm≦X≦0.6 mm, thereby minimizing a thermal expansion difference between the heater element and the heater substrate to avoid cracks in a portion of the heater substrate near the heater element.

Abstract: A gas sensor includes a body having a measurement-gas chamber and a reference-gas chamber. The measurement-gas chamber is supplied with a measurement gas. The reference-gas chamber is supplied with a reference gas. A detecting cell provided in the body includes (1) a solid electrolyte member, (2) a measuring electrode provided on the solid electrolyte member and facing the measurement-gas chamber, and (3) a reference electrode provided on the solid electrolyte member and facing the reference-gas chamber. A heater portion operates for heating the detecting cell. The heater portion includes (1) a first substrate, (2) a heating member provided on the first substrate, (3) a high-voltage-side lead portion provided on the first substrate and electrically connected to the heating member, (4) a low-voltage-side lead portion provided on the first substrate and electrically connected to the heating member, and (5) a second substrate covering the heating member.

Abstract: A gas sensing element having a sample gas chamber into which a sample gas is introduced, and a reference gas chamber into which a reference gas is introduced. A sensor cell detects a specific gas concentration in the sample gas chamber. An oxygen pump cell pump cell pumps oxygen gas from or to the sample gas chamber. An introducing passage includes at least one pinhole provided on a surface of the oxygen pump cell for introducing the measuring gas into the sample gas chamber. The surface of the oxygen pump cell faces an outside of the gas sensing element. And, a porous diffusion resistive layer is provided on the surface of the oxygen pump cell so as to cover a portion corresponding to the introducing passage, thus serving to reduce or eliminate the effects of temperature dependency upon gas sensor output for properly sized and machine pinholes.

Abstract: A gas concentration detector comprises a plate sensor element including a sensing action and a signal output section. A flange section is formed between the sensing section and the signal output section so as to protrude in the lateral direction thereof. A cylindrical housing has an inside space for receiving the sensor element. Powder is disposed in the inside space of the cylindrical housing at a predetermined position adjacent to the flange section so that the sensor element is airtightly fixed to the housing by applying a pressing force on the powder. Furthermore, a cross-sectional area of the signal output section is larger than a cross-sectional area of the sensing section.

Abstract: An air-fuel ratio sensing element comprises a pump cell having at least one pair of pump electrodes thereon, a sensor cell having at least one pair of sensor electrodes thereon, and a gas chamber having two surfaces defined by the pump cell and the sensor cell. Two to five gas holes, each having approximately the same diameter and communicating with the gas chamber, are provided for introducing sensed gas into the gas chamber. The gas holes form their projection images on the surface of the sensor cell which has a sensor electrode thereon and faces the gas chamber. The sensor electrode is shaped such that it is dividable into a plurality of similar subsections defined by virtual lines connecting the geometric centroid of the sensor electrode and the center of the projection image of each gas hole.

Abstract: An air-fuel ratio sensor comprises a platelike oxygen sensing section made of a solid electrolyte and a heater sheet heating the oxygen sensing section. The oxygen sensing section and the heater sheet are stacked via spacers to constitute a multilayer construction. The heater sheet comprises a first platelike insulating sheet chiefly containing at least one component selected from the group consisting of .alpha.-alumina, steatite and mullite, a filmy resistance element disposed on the first insulating sheet and having a resistance-temperature coefficient within a range of 0.5.times.10.sup.3 to 2.0.times.10.sup.3 ppm/.degree.C., and a second platelike insulating sheet covering the resistance element and chiefly containing at least one component selected from the group consisting of .alpha.-alumina, steatite and mullite.