Ngk Spark Plug Company, Limited

Mitsubishi Denki Kabushiki Kaisha

Honda Giken Kogyo Kabushiki Kaisha

Mitsubishi Denki K.k.

Kabushiki Kaisha

Mitsubishi Denki Ngk Spark Plug Co. Ltd.

Ngk Spark Plug So., Ltd.

Tetsusyo Yamada

Takao Kojima

Nobuhiro Hayakawa

Yutaka Nakayama

Shintaro Hirate

Hiroyuki Ishiguro

Kazunori Yokota

Yoshiki Kawachi

Yoshiaki Asayama

Toyohei Nakajima

Yasushi Okada

Yoshihide Kami

Sadao Ichikawa

Toshiyuki Ishihara

Takeshi Kamiya

Keiichi Hayashi

A zirconia-base solid electrolyte function element comprising a zirconia-base solid electrolyte substrate, wherein a reinforcing layer is formed directly on each side of said zirconia-base solid electrolyte substrate, the ratio of the shrinkage modulus to the zirconia-base electrolyte substrate to the reinforcing layers is 1.01 to 1.08, and the substrate and the reinforcing layers have been sintered simultaneously.

Reinforced electrolyte function elements

A method of treating a porous body in a gas concentration sensor to regulate the gas diffusion. The porous body is impregnated with a impregnant containing a component that adheres to or binds with the pore surfaces. The component may be a metal salt, examples of which are Al(NO.sub.3).sub.3, CaCl.sub.2 and H.sub.2 PtCl.sub.2. A colloidal solution may be used.

Method of adjusting a gas sensor

An air/fuel ratio sensor with a solid electrolyte oxygen pump and oxygen sensor defining a closed space therebetween. At least in the oxygen pump, porous electrodes sandwich an ionic oxygen conductive solid electrolyte. The voltage impressed on the electrodes of the pump is limited to a predetermined level, e.g., 6 V, in order to prevent blackening and cracking.

Solid electrolyte air/fuel ratio sensor with voltage control

An air/fuel ratio sensor is described, comprising an oxygen pump element composed of a solid electrolyte having a pair of electrodes on opposite sides thereof, a gas diffusing section section that is in contact with one electrode on said oxygen pump element and which accepts a limited inflow of a gas to be analyzed, and an oxygen gas detecting element that is based on a transition metal oxide disposed within said gas diffusing section, the resistance of which varies in proportion to the partial pressure of oxygen gas in the gas to be analyzed.

Air/fuel ratio sensor

A reinforced plate-like laminated sintered body is produced by the steps of providing a green laminate with an alumina-based layer including zirconia provided at least partly over one surface of the base material and simultaneously sintering the laminated surface layer and base material layer. The thickness ratio of the surface layer with respect to the base material layer is in the range of 1/100 to 20/100 and the laminate has a ratio of shrinkage moduli, calculated as the ratio of the shrinkage modulus of the base material layer when sintered alone to the shrinkage modulus of the surface layer when sintered alone, within the range of 1.01 to 1.08.

Reinforced plate-like sintered bodies

An A/F detector having an output which is unambiguous over the entire operating region of the device, including both fuel-rich and fuel-lean regions. The detector includes two cells, an electrochemical cell and a pump cell. A constant current is passed through the electrochemical cell and the current through the pump cell is controlled in such a manner that the voltage across the electrochemical cell is constant. The current through the pump cell is detected to provide the unambiguous output signal.

Air/fuel ratio detector

An air-fuel ratio sensor in which the temperature dependence as well as the pressure dependence of a detection signal obtained by the air-fuel ratio sensor are suppressed to thereby improve the accuracy in air-fuel ratio by the air-fuel ratio sensor, which is not influenced by deposits in an exhaust gas and which is high in durability. The suppression is achieved by using a gas-diffusion limiting portion having such critical parameters as 10-30% porosity, 1-3 micrometers mean pore size and 200-1000 micrometers thickness. Alternatively the parameters may be 15-25% porosity, 0.1-7 micrometers pore size and 400-800 micrometers thickness.

Air-fuel ratio sensor

A heater including an electron-conductive pattern designed to generate heat, which has a partially and/or entirely stabilized ZrO.sub.2 -base substrate, an Al.sub.2 O.sub.3 -base coating layer disposed on the surface of the substrate, and an electron-conductive pattern to generate heat disposed on the coating layer.

Plate-like ceramic heater

An air-fuel ratio detecting device with which the air-fuel ratio can be accurately detected over the entire range of ratios, both for the lean range and for the rich range. An oxygen pumping element and an oxygen sensing element are arranged opposite one another with a gap therebetween and are disposed in a chamber in which exhaust gas flows. A signal which is symmetric in lean and rich regions is thereby obtained, and this signal is divided into separate portions in the two regions, which are then composed to obtain a single-valued signal accurately representing the air-fuel ratio over the entire operating range.

Air-fuel ratio detecting device

A heater comprising a sheet substrate formed of alumina and an electron-conductive pattern provided thereon and designed to generate heat, in which at least a portion of the electron-conductive pattern is provided thereon with an oxygen ion-conductive layer.

Plate-like alumina heater

An air/fuel ratio sensor apparatus which is capable of detecting deterioration of the sensing elements and correcting the output of the apparatus accordingly. The apparatus includes two sensing elements and a closed compartment of which the two sensing elements define at least portions. One of the sensing elements is used as an oxygen concentration measuring cell, and the other as an oxygen pump cell. When the internal combustion engine with which the sensor is associated is running without fuel supply, a reference voltage used for controlling the oxygen pumping current is set to a smaller value than that employed when the engine is running with a fuel supply. Deterioration of the sensing elements is then detected by comparing the output air/fuel ratio signal produced at that time with a preset fixed value.

Air/fuel ratio sensor apparatus for use with internal combustion engine

An air/fuel ratio sensor having two units of probe is disclosed each of which comprises two sensing elements, each having a pair of porous electrodes on oppostie sides of an oxygen ion-conductive solid electrolyte; a gas compartment which is formed in contact with one porous electrode for each sensing element and which communicates with the gaseous atmosphere of interest by way of a gas diffusion limiting portion; and an internal reference oxygen source which is formed in contact with one sensing element on the porous electrode side which is opposite the side where said gas compartment is provided. The oxygen source communicates with the outside by way of a leakage resisting portion. The gas compartment in the first unit of probe communicates directly with the gaseous atmosphere of interest by way of a first gas diffusion limiting portion while the gas compartment in the second unit of probe communicates with the gas in the first unit of probe by way of a second gas diffusion limiting portion.

The invention relates to a gas sensor having first and second solid electrolyte cells each of which has a solid electrolyte plate, e.g. a zirconia plate, and a pair of porous electrode layers formed on the opposite surfaces of the plate, spacing means to hold the first and second cells in a narrowly spaced, opposite and parallel arrangement and to define a gas chamber, which admits a gas atmosphere subject to measurement, within the gap between the two cells such that the inner electrode layers of the two cells face each other across the gas chamber and means to appropriately restrict diffusion of the gas atmosphere into the gas chamber. Usually one of the two solid electrolyte cells is used as a concentration cell and the other as an ion pump. To prevent unintentional changes in the distance between the two electrode layers facing each other across the gas chamber during the manufacturing process including sintering treatment, at least one support pillar is disposed in the gas chamber so as to fixedly extend from the inner electrode layer of the first cell to the inner electrode layer of the second cell.

Gas sensor with gas diffusion chamber between two platy solid

An air/fuel ratio detector comprising a pump and an electrochemical cell in which both the pump and electrochemical cell comprise an oxygen ion conductive solid electrolyte sandwiched between porous electrodes. One of the elements has an insulating substrate formed on a portion of the electrolyte. Over the substrate is formed a layer of semiconducting metal oxide. The cell and pump face each other with the cell providing an EMF and the pump being pumped by a pump current. The size of the resistance of the metal oxide layer indicates whether the air/fuel mixture is rich or lean relative to a stoichiometric mixture and the values of the EMF and pump current indicate the deviation from stoichiometry.

In an oxygen sensor which is provided with an oxygen pump element having electrodes on both front and rear surfaces of a solid electrolyte plate with oxygen ion conductive property, voltage from an external power source is applied between the electrodes and a pumping current flows between the electrodes. Thereby oxygen is pumped out of ambient gases to be measured through a member including a gap with oxygen diffusion limiting property. The limit value of the pumping current accompanied by the oxygen pumping is determined or the oxygen concentration difference produced before and after the diffusive motion of oxygen through the member or oxygen concentration produced after the diffusive motion of oxygen through the member is measured. Thereby the oxygen concentration of the ambient gases is calculated. The oxygen sensor comprises a heater unit installed on the solid electrolyte plate of the oxygen pump element through an electric insulation layer, and a lead wire unit of one electrode of the oxygen pump element connected at one end to the heater unit. Thus the oxygen sensor is excellent in energy saving, detection accuracy, and reduction of use amount of electrode lead wires.

Growing community of inventors

Aichi, Japan

Tetsusyo Yamada