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Thick Film ZrO2 NOx Sensor for the Measurement of Low NOx Concentration
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English
Abstract
A practical ZrO2 NOx sensor using dual oxygen pumping cells has been introduced for the control of NOx emitted from a lean-burn gasoline engine and diesel engine.(1),(2). However, the measuring accuracy was not high enough to be useful for controlling or monitoring a low level of NOx concentration such as several tens ppm behind a three way catalyst or lean NOx catalyst which is NOx adsorption or De-NOx catalyst.
This paper describes improvement of the interference effect of oxygen in the exhaust gas from the lean-burn gasoline engine and diesel engine. The cause of oxygen dependency is analyzed/revealed and a method of improvement is introduced.
The improved NOx sensor has an approximately · · 2% measuring error in the wide range of oxygen concentration on a model gas system, compared to the · ·10% of the previous one. The improved NOx sensor provides a linear signal with a measuring error within · · 10%, in a diesel engine operating under practical conditions in which oxygen concentration, gas temperature, and back pressure of exhaust gas vary from 2 to 14.5 %, 175 to 730 · ·and 2 to 100 mmHg respectively. It is also confirmed that the improved NOx sensor can monitor less than 100 ppm of NOx emitted from a TOYOTA D-4 engine equipped with a NOx adsorption catalyst. The improved NOx sensor would be capable of measuring less than 100 ppm of NOx behind catalyst.
Therefore, the improved NOx sensor would be useful for OBD of lean NOx catalyst and for control of NOx adsorption catalyst.
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Authors
Citation
Kato, N., Kurachi, H., and Hamada, Y., "Thick Film ZrO2 NOx Sensor for the Measurement of Low NOx Concentration," SAE Technical Paper 980170, 1998, https://doi.org/10.4271/980170.Also In
Electronic Engine Controls 1998: Sensors, Actuators, and Development Tools
Number: SP-1356; Published: 1998-02-13
Number: SP-1356; Published: 1998-02-13
References
- Kato N. Nakagaki K. Ina N, “Thick film ZrO2 NOx sensor” SAE paper # 960334 1996
- Kato N. Hamada Y. Kurachi H. “Performance of thick film NOx sensor on diesel and gasoline engines” SAE paper # 970858 1997
- Miyoshi N. Takahashi N. Kasahara K. et.al. “Development of new concept three-way catalyst for automotive lean-burn engines” SAE paper # 950809 1995
- Takami A. Takemoto T. Iwakuni H. et.al. “Development of lean burn catalyst” SAE paper # 950746 1995
- Smedler G. Walker A. Winterborn D. et.al. “High performance diesel catalysts for Europe beyond 1996” SAE paper # 950750 1995
- Brogan M.S. Boegner W. et.al. “Evaluation of NOx storage catalysts as an effective system for NOx removal from the exhaust gas of leanburn gasoline engines” SAE paper # 952490 1995