Ngk Spark Plug Company, Limited

Takeshi Kawai

Satoshi Teramoto

Shigeki Mori

Tessho Yamada

Hiroshi Inagaki

Toshiya Matsuoka

Yuji Oi

Kenji Kato

Kentaro Mori

Nobuhiro Hayakawa

Koji Shiotani

Ryohei Aoki

Takuya Saito

Yuichi Yamada

Seiji Oya

Makoto Kume

Hisashi Sasaki

Katsuhisa Yabuta

Masaki Nakagawa

Masashi Tsuzuki

Noboru Matsui

Hirotaka Onogi

Shin Yoshida

Yukinobu Nagao

Tomohiro Mabuchi

Tomohisa Fujita

Masamichi Hiraiwa

Hideki Toyoda

Takahiro Akiyama

Kouji Shiotani

Shinichiro Iwama

Harumi Aiba

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

In order to compensate for variation in output of sensor elements, there is provided a compensating resistorthat has a resistance value reflected by correction information. The resistoris connected in parallel with a VS cellthrough paired electrode leadsandand paired electrode padsand. The paired electrode leadsandare placed at a position electrically isolated from solid electrolyte substratesand

Gas sensor element, gas sensor and control system of 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

[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 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.

Detection method for defect of sensor

A method and apparatus for detecting an abnormality of a nitrogen oxide purifying catalyst using an NOx sensor, the method including: calculating a detection integrated value by integrating corresponding values corresponding to the NOx sensor output signal obtained until a first predetermined detection period has elapsed after the NOx sensor begins to generate an output signal and subtracting a variation integrated value. The variation integrated value is calculated by integrating corresponding values obtained until a predetermined second detection period has elapsed after the NOx sensor beings to generate an output signal when driven in a gas atmosphere having a constant nitrogen oxide concentration.

Method and apparatus for detecting abnormality of nitrogen oxide purifying catalyst

A gas sensor including: a gas sensing element including first and second ceramic layers. The first ceramic layer has a first through hole and a first through hole conductor covering an inner surface thereof. The first ceramic layer includes a first conductor which includes: a first peripheral conductive portion electrically connected to the first through hole conductor; a first lead portion that is narrower than the first peripheral conductive portion; and a first contact conductive portion that is wider than the first lead portion. The first peripheral conductive portion, the first lead portion and the first contact conductive portion are integrally formed and arranged in this order in a longitudinal direction. The second ceramic layer includes a second conductor electrically connected to at least the first contact conductive portion.

Using a gas detection voltage Vs output from a terminal CU, a determination is made at to whether, after startup of an air-fuel ratio detection apparatus (), a full-range air-fuel ratio sensor () has reached a semi-activated state in which a determination can be made as to whether the air-fuel ratio is on the rich or lean side based on a change in a gas detection signal Vic. After determining that the sensor has reached the semi-activated state, the signal Vic is compared with a threshold to determine whether the air-fuel ratio is on the rich or lean side. In the apparatus (), the potential difference between an outer pump electrode of a pump cell () and a reference electrode of an oxygen concentration measurement cell () is obtained via a first differential amplification circuit () as the gas detection signal Vic, the signal Vic being highly responsive to a change in air-fuel ratio of exhaust gas.

Air fuel ratio detection apparatus

A prismatic multilayer gas sensor element and method of making the same, the prismatic multilayer gas sensor element () having a substantially rectangular cross section, and including a gas-sensing cell portion () formed at a distal end portion of the prismatic gas sensor element (); and a posterior lead portion () adjoining the gas-sensing cell portion (). The longitudinal lateral surfaces of the posterior lead portion () are coated with a non-porous alumina layer (), the non-porous alumina layer () having a multilayered structure including at least a joining layer () and a surface layer (). The longitudinal lateral surface of the gas-sensing portion () is not coated with a non-porous alumina layer.

Gas sensor and method for manufacturing the same

A control apparatus for a gas sensor, wherein a microcomputer, which is connected to an oxygen sensorincluding a detection elementand a heater, detects the cooling water temperature Tw of the engine. The control apparatus determines that condensation water within the exhaust pipe is being generated when the cooling water temperature Tw is equal to or lower than 0&#xb0; C. When equal to or lower than 0&#xb0; C., the microcomputersupplies to the heaterelectrical power for maintaining the temperature of the detection elementwithin the range of 100&#xb0; C. to a splash-water-cracking generation temperature (e.g., about 300&#xb0; C.) at or above which cracking can occur in a laminated-type oxygen sensor elementdue to splash of condensation water. Electrical power is supplied to the heatersuch that a pulse signal Sh is output from the microcomputer, and the heateris pulse-driven by use of a heater electrification control circuit

Control apparatus for gas sensor

A method of stabilizing pump current in a gas sensor through suppression of oscillations of the pump current which result from pulsations of measured gas is provided. The gas sensor includes an oxygen pump element, an oxygen concentration cell element and a measurement gap between the oxygen pump element and the oxygen concentration cell element, and is operative to control the pump current through the oxygen pump element so that an output voltage of the oxygen concentration cell element is constant in order that an oxygen concentration in the measurement gap is maintained constant and detect an oxygen concentration in the measured gas on the basis of the pump current. The method comprising adjusting an activity of electrodes of an oxygen pump element so as to change a responsiveness in control of the pump current and thereby reduce an amplitude of the oscillations of the pump current. There is also provided the above described type gas sensor wherein the activity of the electrodes of the oxygen pump element is adjusted so as to change a responsiveness in control of the pump current and thereby reduce the oscillations of the pump current.

Method of stabilizing pump current in gas sensor

A constant current Iconst is applied to an electromotive force cell which is interposed between a gap (measurement chamber) of a fixed atmosphere and an oxygen reference chamber of a constant oxygen content, for measurement of a resistance value of the electromotive force cell, whereby the resistance value can be measured accurately irrespective of an oxygen content in an atmosphere to be measured by an oxygen sensor element or cell unit. The resistance value of the electromotive force cell is measured at a predetermined timing T2 after application of a current is started, so that a measure resistance value is free of a variation of a resistance value due to deterioration of porous electrodes of an electromotive force cell, such a variation being included in the measured resistance value in case the measurement is done by using an AC current, and therefore accurate measurement can be attained. A temperature control methods and a temperature control apparatus for an oxygen sensor, capable of detecting the temperature accurately without suspending measurement of an oxygen content for a long period of time are also provided. Further, a temperature control method and a temperature control apparatus for an oxygen sensor, capable of detecting not only the temperature of the electromotive force cell but the temperature of the pump cell by applying a current or voltage to the electromotive force cell are provided.

Temperature control for all range oxygen sensor

A method of detecting a deteriorated condition of a wide range air-fuel ratio sensor is provided. Firstly, a current is applied to an electromotive force cell to detect a voltage Vs0 across electrodes on opposite side surfaces of the cell. Application of the current is suspended, and a voltage drop Vsd1 across the electrodes is detected after lapse of a time ranging from 10 .mu.s to 1 ms after the application of the current is suspended. Based on the voltage drop Vsd1 is detected a first resistance value Rvs1 equated to the temperature of the electromotive force cell. Further, after lapse of a time ranging from 10 ms to 50 ms after the application of the current to the electromotive force cell is suspended, a voltage drop Vsd2 across the electrodes of the electromotive force cell is detected. Based on the voltage drop Vsd2 is detected a second resistance value Rvs2 equated to an internal resistance of the electromotive force cell including a resistance component resulting from deterioration. By comparison of the resistance values Rvs1 and Rvs2, the deteriorated condition of the wide range air-fuel ratio is detected. An apparatus for carrying out such a method is also provided.

Method of and apparatus for detecting a deteriorated condition of a wide

A method of detecting an activated condition of a wide range air-fuel ratio sensor is provided. With this method, application of a current to a heater is started idiately after an engine is started (S00). Then, a current Icp for pumping is passed through an electromotive force cell (S10). A lapse of a predetermined time Tin is waited for (S18). After a lapse of time Tin, a voltage Vs across both electrodes of the electromotive force cell is detected (S20) and labeled as Vs0 (S22). Then, application of Icp is suspended (S30) and a routine is held on standby until a time of 25 ms elapses (S35). At the point of time when the time of 25 ms has elapsed, the voltage across the electrodes on the opposite sides of the electromotive force cell is detected (S40) and labeled as Vs1 (S45). A resistance value Rs1 is calculated from Vs0, Vs1 and Icp (S50). The resistance value Rs1 is compared with a value Rss which has been prepared previously (S55) and it is judged, when Rs1 is smaller than Rss, that the electromotive force cell has been put into an activated condition. An apparatus for detecting an activated condition of a wide range air-fuel ratio sensor is also provided.

Method of and apparatus for detecting an activated condition of a wide

A gas sensor has a sensor cell unit which includes a detection member made up of an oxygen concentration cell, oxygen pump cell and a spacer interposed between the oxygen concentration cell and the oxygen pump cell to define therebetween a measurement gas chamber. The spacer has a pair of communicating holes for providing communication between the measurement gas chamber and the outside. Diffusion control layers made of porous material are formed within the communicating holes of the spacer so as to control flow of the detection gas into the measurement gas chamber, etc. The diffusion control layer is made of alumina and has on the outer surface thereof (i.e., on the inner peripheral surfaces thereof defining gas permeating pores) a thin Ca coating which inhibits formation of a substance which is in a liquid phase at a temperature range in which the gas sensor is used, due to reaction of the alumina forming the diffusion control layer with a suspended component of the detection gas such as phosphorus (P) in an engine exhaust gas.

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Komaki, Japan

Takeshi Kawai