Hitachi, Ltd.

Hitachi Car Engineering Co., Ltd.

Hitachi Automotive Engineering Co., Ltd.

Naoki Minami

Sadayasu Ueno

Norio Hasegawa

Kanemasa Sato

Takao Sasayama

Seiko Suzuki

Shiro Oouchi

Shiro Ouchi

Shirou Ouchi

A gas composition sensor for detecting oxygen, and hydrocarbon group fuel or combustible composition produced after combustion having a zirconia solid electrolyte body, a concentration cell composed of a platinoid metal catalytic detecting electrode and a reference electrode opposite to each other and a sensing element composed of a gas diffusion limiting member coating the detecting electrode, which further comprises a pair of the sensing elements and heaters for setting both of the sensing elements to operating temperatures different from each other, whereby a specified gas component is selectively detected by operating both of the sensing elements so as to have sensitivity coefficients to the specified gas component different from each other.

Gas composition sensor and method for separately detecting components of

A method and apparatus are disclosed for measuring atmospheric pressure in conjunction with an air-fuel ratio sensor of the type comprising a concentration cell with atmospheric air and exhaust electrodes on opposite sides of a solid-state electrolyte having oxygen ion conductivity. During an atmospheric pressure measuring cycle, oxygen ions are pumped from the atmospheric air electrode to the exhaust electrode, in a quantity which is either predetermined at a fixed value, or is sufficient to bring the cell to an equilibrium state. Atmospheric pressure is then calculated from measured emf of the cell, using an experimentally derived functional relationship. In a second embodiment, ions are pumped until a predetermined change of the concentration cell emf is achieved, and atmospheric pressure is determined based on the amount of time required to achieve such change. The atmospheric pressure measuring mode is operated on a time shared basis with the air-fuel ration detection mode.

Air fuel ratio sensory

An air fuel ratio detecting arrangement using a diffusion suppressing type air fuel ratio sensor applicable to an air fuel ratio control unit for an internal combustion engine incorporating an atmospheric air pressure correction circuit in a signal processing and outputting device for correcting an output voltage signal processed therein based on a change in atmospheric air pressure which is detected when a predetermined operating condition of an internal combustion engine is satisfied. A secular change correction circuit included in the signal processing and outputting device detects a change in electromotive force of a concentration cell portion of the air fuel ratio sensor when a predetermined rich air fuel ratio is reached and corrects a reference voltage for the air fuel ratio sensor based on the detected change in electromotive force of the concentration cell portion in addition to an air calibration circuit.

Air fuel ratio detecting arrangement and method therefor for an internal

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Katsuta, Japan

Naoki Minami