Ngk Spark Plug Company, Limited

Satoshi Teramoto

Takeshi Kawai

Shigeki Mori

Hirotaka Onogi

Kenji Kato

Takeshi Mitsuoka

Kuniharu Tanaka

Masaki Onkawa

Hiroshi Inagaki

Toshiya Matsuoka

Tessho Yamada

Yuji Oi

Toru Iwano

Shigehiro Otsuka

Koji Shiotani

Tetsuya Ito

Dai Nishijima

Yukinobu Nagao

Takuya Saito

Masamichi Hiraiwa

Yuichi Yamada

Kentaro Mori

Seiji Oya

Tomonori Uemura

Makoto Kume

Masaki Nakagawa

Satoru Abe

Noboru Matsui

Nobuhiro Inoue

Ryohei Aoki

Tomohiro Mabuchi

Tomohisa Fujita

Kouji Shiotani

Hiroki Inouchi

Yuichi Ishida

Takahiro Akiyama

Shinichiro Iwama

Sigehiro Otsuka

Takashi Kawai

Takeshi c/o Ngk Spark Plug Co Ltd Kawai

Shigeki c/o Ngk Spark Plug Co Ltd Mori

Tomohiro c/o Ngk Spark Plug Co Ltd Mabuchi

A sensor control apparatus for a gas sensor which detects a particular gas component contained in a gas under measurement. In the case where humidity detection is performed using an electromotive-force-type gas sensor, a sensor control apparatus changes a target voltage of an electromotive force cell to a second target voltage for humidity detection and then to a third target voltage which is lower than a first target voltage which is a target voltage used for detecting the concentration of the particular gas component. In the case where humidity detection is performed using a limiting-current-type gas sensor, the sensor control apparatus changes the voltage applied to a pump cell to a second application voltage for humidity detection and then to a third application voltage which is lower than a first application voltage which is an application voltage used for detecting the concentration of the particular gas component.

Sensor control apparatus and sensor control system

A gas concentration detection device for detecting a gas concentration using a limiting current type gas concentration sensor. In an application voltage line set to pass through a plurality of limiting current regions for different values of gas concentration, a ratio for lean is set as a ratio of change in current with respect to a change in voltage when an air/fuel ratio corresponding to the gas concentration is lean, and a ratio of rich different from the ratio for lean is set when the air/fuel ratio is rich.

Gas concentration detection device

An apparatus and method for individually detecting NO and NOconcentrations as NOcomponents of an object gas. An NO concentration corresponding value is obtained from a first detection element not having a reduction section. An NO concentration corresponding value is obtained from a second detection element having a reduction section, and having an NO/NO sensitivity ratio greater than that of the first detection element. The difference &#x394;C between the NO concentration corresponding values of the two detection elements is obtained, and divided by the difference &#x394;S between the NO/NO sensitivity ratios of the two detection elements, whereby an NOconcentration corresponding value is obtained. A value obtained by multiplying the NOconcentration corresponding value by the NO/NO sensitivity ratio of the second detection element is subtracted from the NO concentration corresponding value of the second detection element, whereby an NO concentration corresponding value is obtained.

NOx concentration detection apparatus and NOx concentration detection method

An NOdetection apparatus computes a first NOconcentration NOon the basis of a second pumping current Ip2, and sets correction coefficients a, b (concentration variation correction information) on the basis of the first NOconcentration NO. Therefore, the NOdetection apparatus can set the correction coefficients a, b in accordance with the concentration of NOactually contained in a to-be-measured gas. Since the NOdetection apparatus uses Equation 3, determined by the correction coefficients a, b, for correction of the first NOconcentration NO, the NOdetection apparatus can correct the first NOconcentration NOin accordance with the state of change of the NOconcentration even when the magnitude of an output variation caused by a pressure change changes depending on the NOconcentration.

[object Object]

An NOdetection apparatus does not always perform correction processing, but it determines whether to perform the correction processing on the basis of the result of a determination of whether a first Noconcentration is higher than a predetermined specific concentration. The first NOconcentration NOcalculated from a second pumping current Ipwhich changes with the actual NOconcentration. Therefore, the NOdetection apparatus can determine whether to correct the first NOconcentration NOin accordance with the actual NOconcentration. Accordingly, the NOdetection apparatus can suppress a decrease in gas detection accuracy even in the case where the gas detection value based on the sensor output involves an error in a specific concentration range (concentration range of 90 ppm or higher).

A sensor control apparatus is disclosed, including a preliminary control for supplying a constant current to a second oxygen pump cell of a gas sensor for a constant period of time so as to control to a constant level the amount of oxygen pumped out from a second measurement chamber (Sto S). At the beginning of drive control (Sto S), oxygen is pumped back into the second measurement chamber. During the pumping back operation, an NOconcentration correspondence value has a large time course change and is not stable. The NOconcentration correspondence value is corrected using correction data common among gas sensors, wherein the timing for applying the correction data is adjusted by making use of an application time determined in accordance with individual differences of each gas sensor.

Sensor control apparatus, sensor control system, and sensor control method

A gas sensor element and a gas sensor incorporating the gas sensor element. The gas sensor element () includes a detection portion () including a solid electrolyte body () and a pair of electrodes () and () disposed on the solid electrolyte body; and a porous protection layer () covering the detection portion. The porous protection layer includes an inner porous layer () and an outer porous layer (). The inner porous layer has a higher porosity than the outer porous layer. Further, the inner porous layer contains, as main components, ceramic particles (), and ceramic fiber filaments (), and the amount of the ceramic fiber filaments is 25 to 75 vol % based on the total amount of the ceramic particles and the ceramic fiber filaments taken as 100 vol %.

Gas sensor element and gas sensor

A gas sensor element () including a detection portion () including a solid electrolyte body () and a pair of electrodes () and () disposed on the solid electrolyte body; and a porous protection layer () covering the detection portion. The porous protection layer includes an inner porous layer () and an outer porous layer (); the inner porous layer is higher in porosity than the outer porous layer; the inner porous layer contains, as main components, ceramic particles (), and ceramic fiber filaments () which are mainly formed of a ceramic material and which have a mean fiber length of 70 to 200 &#x3bc;m; and the amount of the ceramic fiber filaments is 25 to 75 vol % on the basis of the total amount of the ceramic particles and the ceramic fiber filaments, the total amount being taken as 100 vol %.

Gas sensor element, and gas sensor

A gas sensor including coating layers () and () of fluorine or a fluorine compound formed on the surface of a separator (), including a front separator () and a rear separator (), disposed inside a sheath (). The coating layers () and () have water impermeability and water repellency. Even in the case where moisture contained in the atmosphere within a sheath () forms dew on the surface of the separator (), the coating layers () and () prevent soaking of moisture into the separator (), to thereby secure the insulation property of the separator (). Also, the coating layers () and () having water repellency prevent a water droplet from spreading on the surface of the separator () with resultant formation of a film of water, to thereby prevent flow of leakage current via a film of water.

Gas sensor

A gas sensor element () includes a laminate of a detection element () and a heater (), and a porous protection layer () covering a forward end portion thereof. The laminate has a measuring chamber () into which a gas-to-be-measured is introduced via a diffusion resistor (). The porous protection layer includes an inner porous layer (), and an outer porous layer (). The inner porous layer has a higher porosity than the outer porous layer and the diffusion resistor. As viewed in a plurality of 100 &#x3bc;m&#xd7;100 &#x3bc;m regions ato aand bto bon sections of the inner porous layer and the diffusion resistor, respectively, a pore diameter greater than the greatest pore diameter Cin the regions of the diffusion resistor exists in each of the regions of the inner porous layer.

There is provided a gas sensor element for detecting the concentration of a specific gas component in gas under measurement, which includes a plate-shaped element body and a porous protection layer. The element body has, at one end portion thereof, a gas sensing portion formed with a solid electrolyte substrate and a pair of electrodes. The porous protection layer has a porous structure formed of ceramic particles and surrounds at least the circumference of the one end portion of the element body. In the present invention, the porous protection layer has an inner region, an intermediate region and an outer region laminated together in order of mention from the element body toward the outside. The intermediate region has a porosity lower than those of the inner and outer regions. There is also provided a gas sensor with such a gas sensor element.

[Objective] An object is to provide a sensor control apparatus and a sensor-control-apparatus control method which can reduce variation in startup time among a plurality of times of execution of detection processing, in consideration of variation in output characteristic among a plurality of gas sensors. [Means for Solution] In a sensor control apparatus, before drive control (Sto S) is started, preliminary control is executed so as to supply a constant current to a second oxygen pump cell over a constant time, to thereby control to a constant level the amount of oxygen pumped from a second measurement chamber to the outside of the second measurement chamber (Sto). The preliminary control is executed under control conditions of the sensor control apparatus which are determined for each gas sensor and are associated with the amount of oxygen pumped from the second measurement chamber to the outside thereof. The control conditions bring into a target range the concentration correspondence value calculated after start of the drive control which is started after the preliminary control is executed in a state in which a reference gas having a known concentration is introduced into the gas sensor.

Sensor control device and sensor control method

A gas sensor () includes an oxygen pump cell () and an oxygen-concentration detection cell () laminated together with a spacer () interposed therebetween. The spacer () has a gas detection chamber () which faces electrodes () of the cells (). The oxygen-concentration detection cell () produces an output voltage corresponding to the concentration of oxygen in the gas detection chamber (). The oxygen pump cell () pumps oxygen into and out of the measurement chamber () such that the output voltage of the oxygen-concentration detection cell () becomes equal to a predetermined target voltage. A leakage portion mainly formed of zirconia is disposed between which electrically connects the oxygen-concentration detection cell () and the oxygen pump cell ().

A defect detection method for a sensor in which a fixing member provides a seal between a sensor element and tubular metallic members, the method being capable of detecting breakage of a conductor caused by breakage of the element.

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Nisshin, Japan

Satoshi Teramoto