Hitachi, Ltd.

Other

Futoshi Ichiyanagi

Shoichi Sakai

Akira Uchikawa

Shigeo Isitani

Goji Matsumoto

Yasuji Orimo

Chiharu Katsuyama

Shigeo Ohkuma

Masao Tsukada

Toshiaki Inoue

Junji Onozuka

An oxygen sensor includes a base body portion; and a plurality of function layers laminated on a surface of the base body portion. The function layers includes a solid electrolyte layer adapted to conduct oxygen ions; a reference electrode layer located on a base body portion side of the solid electrolyte layer; a sensing electrode layer located on the opposite side of the solid electrolyte layer to the reference electrode layer; a heater portion adapted to activate the solid electrolyte layer by heating; and a gas diffusion layer formed between the reference electrode layer and the base body portion, and adapted to diffuse a reference gas within the gas diffusion layer. The gas diffusion layer is formed to have a porosity indicating a limit current value ranging between 60 &#x3bc;A and 200 &#x3bc;A. The limit current value is a value of a current flowing between the reference electrode layer and the sensing electrode layer when the current flowing therebetween becomes substantially constant during the process of bringing a voltage applied therebetween higher.

Oxygen sensor

An oxygen concentration detecting element including a base member made of an electrically insulating material, a heater disposed on an outer surface of the base member, the heater being adapted to generate heat upon being energized, and an oxygen detecting unit disposed in an offset position on the outer surface of the base member in which the oxygen detecting unit is prevented from overlapping with the heater, the oxygen detecting unit including a solid electrolyte layer and a pair of electrodes between which the solid electrolyte layer is disposed.

Oxygen concentration detecting element

An oxygen sensor includes a sensing element detecting an oxygen concentration in a measurement gas that flows in a pipe, a cylindrical protector which covers an outside of the sensing element and whose top end portion projects toward an inside of the pipe. An outside diameter D of the protector and a projection amount L of the protector inside the pipe are set so that a ratio of the product of the outside diameter D and the projection amount L (D&#xd7;L) to a cross-sectional area S of a flow passage of the pipe becomes substantially smaller than or equal to 2.5%.

The invention relates to an air/fuel ratio detection apparatus. This apparatus includes (a) a heater portion having an elongate cylindrical shape and heating by applying electricity thereto from outside; (b) a solid electrolyte layer surrounding the heater portion and being activated by heat to conduct oxygen ions therethrough; (c) first and second electrodes in contact with the solid electrolyte layer and being away from each other such that pumping voltage is applied by the first and second electrodes to the solid electrolyte layer; (d) a reference electrode for outputting an air/fuel ratio detection signal, the reference electrode being formed on the solid electrolyte layer and being away from the first and second electrodes; and (e) a diffusion layer made of a porous material and surrounding periphery of the solid electrolyte layer to cover the first and second electrodes and the reference electrode.

Air/fuel ratio detection apparatus

In an oxygen sensor that measures a limiting current of when a voltage is applied between pumping electrodes, and also performs a rich/lean judgment based on an electromotive force generated between one of the pumping electrodes and a reference electrode, an oxygen supply voltage for supplying oxygen to the reference electrode is applied, and the reference electrode is covered with a dense layer.

Oxygen sensor and method of manufacturing same

The invention relates to an air/fuel ratio detection apparatus for a gas. This apparatus includes (a) a heater portion having an elongate cylindrical shape; (b) a solid electrolyte layer surrounding the heater portion and activated by heat to conduct oxygen ions therethrough; (c) a first electrode positioned between the heater portion and the solid electrolyte layer; (d) second and third electrodes in contact with an outer surface of the solid electrolyte layer and away from each other; (e) a first voltage applying device for applying a first voltage between the first and second electrodes; (f) a second voltage applying device for applying a second voltage between the first and third electrodes, the second voltage being higher than the first voltage; and (g) a diffusion layer made of a porous material and covering the second electrode to adjust transmission of the gas to the second electrode.

A temperature of an oxygen concentration detector generating an electromotive force according to a difference between oxygen concentration in an engine exhaust gas and oxygen concentration in the atmosphere, is detected, and coefficients in a transformation for converting the electromotive force to a value having a characteristic linear to an air-fuel ratio is modified according to the temperature.

Air-fuel ratio detecting apparatus of engine and method thereof

An air/fuel-ratio detecting apparatus includes a compact layer arranged on the outer surface of a solid electrolyte layer to externally conceal a gas diffusion layer, solid electrolyte layer, outer measuring electrode, and reference electrode to restrain entry of exhaust gas. A gas introduction window is formed in the compact layer to have a predetermined width. The gas introduction window allows entry of exhaust gas toward the gas diffusion layer and the outer measuring electrode in the range of an opening width of the gas introduction window.

Air/fuel-ratio detecting apparatus

An A/F ratio detecting arrangement includes a sensor casing having an oxygen sensor part arranged between first and second electrodes and an oxygen pump part arranged between third and fourth electrodes, which are heated by a heater. A signal output processing circuit serves to provide an A/F ratio signal. A signal switcher serves to provide a provisional oxygen content signal derived from the first and second electrodes when the oxygen pump part is not activated yet, and the A/F ratio signal when the oxygen pump part is activated.

Growing community of inventors

Gunma, Japan

Futoshi Ichiyanagi