Ngk Spark Plug Company, Limited

Takaki Otsuka

Takafumi Oshima

Noboru Ishida

Masashi Ando

Norihiko Nadanami

Satoshi Sugaya

Yoshikuni Sato

Yasuhisa Kuzuya

Tatsuo Okumura

Nobuhiro Hayakawa

Toshitaka Matsuura

Tessho Yamada

Yoshiro Noda

A method for detecting the concentration of a specific component in gas discharged from an internal combustion engine, which includes detecting the concentration of the specific component under certain driving conditions to determine a zero point, which indicates a zero concentration of the specific component, of the detection output; calibrating the detection output of the gas sensor based on the determined zero point; and detecting the concentration of the specific component in exhaust gas based on the calibrated detection output.

Methods and apparatus for measuring NOx gas concentration, for detecting exhaust gas concentration and for calibrating and controlling gas sensor

Method and apparatus for correcting a gas sensor response for moisture in exhaust gas

A nitrogen oxide concentration detector has a first measurement chamber into which is introduced a measurement gas via a first diffusion resistance an oxygen concentration detection electrode for measuring the oxygen concentration in the measurement gas in said first measurement chamber a first oxygen ion pump cell for pumping out oxygen in the measurement gas from said first measurement chamber based on the potential of said oxygen concentration detection electrode a second measurement chamber into which the gas is introduced from said first measurement chamber via a second diffusion resistance and a second oxygen ion pump cell having a pair of electrodes across which a voltage is applied to decompose NOx in the second measurement chamber to pump out dissociated oxygen to cause a circuit Ip corresponding to the NOx concentration to flow in the second oxygen ion pump cell Variation of NOx concentration is a function of variation of Ip The concentration obtained based on the Ip is corrected responsive to the oxygen concentration in the measurement gas. Particularly, a coefficient of the variation of the Ip gain, in said function is corrected responsive to the oxygen concentration in the measurement gas.

An apparatus and method using a two-serial space sensor (having first and second internal spaces ) for accurately measuring NOx concentration in gas, e.g., exhausted from an internal combustion engine. Both NOx (nitrogen oxide) and oxygen are forced to be partially dissociated in the first space to an oxygen concentration level of 2&times;10 to 2&times;10 atm by pumping out oxygen from the first space . The NOx concentration is determined based on the second current measured in the second space and based on the NO dissociation percentage in the first chamber which is 0.5-50%, or preferably 2-20%. The NOx measurement accuracy is further improved when the above oxygen concentration level is maintained from 2&times;10 to 2&times;10 and the temperature drift of the sensor is maintained within &plusmn;5&deg; C. under a sensor temperature range of 700-900&deg; C.

Method for measuring NOx concentration and NOx concentration sensor

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Komaki, Japan

Takaki Otsuka