Ngk Insulators, Inc.

Naoya Saito

Takayuki Sekiya

Mika Murakami

Kazuki Takegawa

Hiroki Fujita

Sumiko Horisaka

Shota Kageyama

Tomoya Seimori

Noriyuki Ina

Takeshi Omori

Provided is a method of inspecting an assembly defect of a gas sensor in a mass-production process. The sensor element included in a second constituting member includes a heater therein and an electrode terminal for a heater in its surface, and the first constituting member includes a contact point member contacting the terminal in a state where the sensor element is inserted into its opening. A first heater resistance value before incorporated is measured to associate the resistance value with an identification information of the sensor element, a second heater resistance value is measured via a contact point member, in a state where the first and second constituting members are integrated with each other, to associate the resistance value with the identification information of the sensor element, and when a difference value between these resistance values associated with the identical identification information exceeds a threshold value, it is determined that an assembly defect occurs.

Method of inspecting gas sensor and method of manufacturing gas sensor

An inspection apparatus capable of performing responsivity inspection on a plurality of gas sensors at equivalent accuracies is provided. The inspection apparatus includes a plurality of inspected sensor disposing parts that are provided halfway through one gas flow path at equal intervals in an extending direction of the flow path and in each of which a gas sensor to be inspected is disposed, and a plurality of straightening plates provided upstream of each of the inspected sensor disposing parts on the gas flow path and separated at a constant distance from the inspected sensor disposing parts. The straightening plates each include a rectangular opening orthogonal to the gas flow path and open to the gas flow path. When the gas flow path extends in one direction in a horizontal plane, the opening has a longitudinal direction along a direction orthogonal to the one direction in the horizontal plane.

Inspection apparatus for gas sensor

In a sensor element, a fourth diffusion rate-controlling portion includes a diffusion rate-controlling portion. The diffusion rate-controlling portion is formed between one or more and three or less surfaces, e.g., an upper surface, of upper, lower, left and right inner peripheral surfaces of a measurement-object gas flowing portion and a partition wall. A measurement electrode is formed on one, e.g., a lower surface, of upper, lower, left and right inner peripheral surfaces of a third inner cavity, the one surface being different in orientation from the Csurface along which the diffusion rate-controlling portion is formed. The diffusion rate-controlling portion and the measurement electrode may be formed on surfaces opposite to each other. A distance L between the measurement electrode and the diffusion rate-controlling portion may be 0.1 mm or more.

Sensor element and gas sensor

Provided is a gas sensor free from an unbonded space being in communication with an internal space. A gas sensor, which includes a sensor element including a plurality of layers that are bonded and formed of an oxygen-ion conductive solid electrolyte and which reduces a predetermined gas component of a measurement gas to identify a concentration of the gas component on the basis of a current flowing through the solid electrolyte, includes an internal space in which a measurement gas having the ability to reduce the gas component is provided. Of the plurality of layers, an interlaminar bonding layer, which bonds a layer forming a bottom surface of the internal space and a layer forming a side surface of the internal space, projects into the internal space.

Gas sensor

In a sensor element, a reference gas regulation pump cell pumps in oxygen to the periphery of a reference electrode in which a reference gas is introduced, by the flow of a control current Ipbetween the reference electrode and an outer pump electrode located in a region exposed to a measurement-object gas. An average current density of the reference electrode under the flow of the control current Ipis higher than 0 &#x3bc;A/mmand lower than 400 &#x3bc;A/mm. The average current density is preferably not higher than 170 &#x3bc;A/mm. An average value of the control current Ipis preferably higher than 1 &#x3bc;A. The outer pump electrode as a measurement-object gas side electrode of the reference gas regulation pump cell may be provided on an outer surface of a layered body (or more specifically, on a second solid electrolyte layer).

A method for setting a temperature rising profile of a sensor element in the activation of a gas sensor is capable of quickly increasing the temperature of the sensor element while reliably preventing or reducing the occurrence of a crack. The method includes Weibull plotting a failure rate that is a cumulative frequency at which a crack occurs as a result of the rapid temperature rising of the sensor element, identifying a temperature-rising-rate upper limit from the plotting results, determining, based on the temperature-rising-rate upper limit, a temperature-rise upper limit curve, and determining, as an appropriate function, a temperature rising profile in a range in which a temperature rising rate at an appropriate temperature does not exceed values on the temperature-rising-rate upper limit curve for the temperature.

Method for setting temperature rise profile of sensor element of gas sensor

A gas sensor is provided with a multilayer body of solid electrolyte layers, a measurement electrode, a reference electrode, a reference gas introduction layer, a detection unit and a heater. The reference electrode and the measurement electrode are formed directly on the same first solid electrolyte layer. Thus, heat from the heater is transferred from a third substrate layer to the first solid electrolyte layer, and also to the reference electrode and the measurement electrode through the same first solid electrolyte layer. The reference electrode is covered with a reference gas introduction layer, formed of a porous body. The transference of heat from the heater to the reference electrode through the reference gas introduction layer is smaller than the transference of heat from the heater to the reference electrode through the first solid electrolyte layer on which the reference electrode is formed directly.

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Nagoya, Japan

Naoya Saito