Abstract: 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.

Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected. Finally, the effect of the amount of moisture in the exhaust gas is removed or reduced from the detected value of gas concentration.

Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected.

Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected.

Abstract: A nitrogen oxide concentration detector has a first measurement chamber 2 into which is introduced a measurement gas via a first diffusion resistance 1; an oxygen concentration detection electrode 7a for measuring the oxygen concentration in the measurement gas in said first measurement chamber 1; a first oxygen ion pump cell 6 for pumping out oxygen in the measurement gas from said first measurement chamber 2 based on the potential of said oxygen concentration detection electrode 7a; a second measurement chamber 8 into which the gas is introduced from said first measurement chamber 2 via a second diffusion resistance 3; and a second oxygen ion pump cell 8 having a pair of electrodes 8a,8b across which a voltage is applied to decompose NOx in the second measurement chamber 4 to pump out dissociated oxygen to cause a circuit Ip2 corresponding to the NOx concentration to flow in the second oxygen ion pump cell 8. Variation of NOx concentration is a function of variation of Ip2.

Abstract: A nitrogen oxide concentration detector has a first measurement chamber 2 into which is introduced a measurement gas via a first diffusion resistance 1; an oxygen concentration detection electrode 7a for measuring the oxygen concentration in the measurement gas in said first measurement chamber 1; a first oxygen ion pump cell 6 for pumping out oxygen in the measurement gas from said first measurement chamber 2 based on the potential of said oxygen concentration detection electrode 7a; a second measurement chamber 8 into which the gas is introduced from said first measurement chamber 2 via a second diffusion resistance 3; and a second oxygen ion pump cell 8 having a pair of electrodes 8a,8b across which a voltage is applied to decompose NOx in the second measurement chamber 4 to pump out dissociated oxygen to cause a current Ip2 corresponding to the NOx concentration to flow in the second oxygen ion pump cell 8. Variation of NOx concentration is a function of variation of Ip2.

Abstract: An apparatus and method using a two-serial space sensor (having first and second internal spaces 2,3) 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 2 to an oxygen concentration level of 2×10−7 to 2×10−10 atm by pumping out oxygen from the first space 2. The NOx concentration is determined based on the second current measured in the second space 4 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 2×10−8 to 2×10−9 and the temperature drift of the sensor is maintained within ±5° C. under a sensor temperature range of 700-900° C.