It is important to evaluate the performance of a NO(x) storage-reduction catalyst installed in a lean-burn gasoline engine system under actual driving conditions. NO(x) measurements have been attempted in lean-burn exhaust gas using a ZrO2 NO(x) sensor. It was found that the NO(x) sensor, which can be directly installed in the exhaust stream, has good NO(x) sensitivity. In addition, it was possible to evaluate the performance of the NO(x) storage-reduction catalyst by effectively using both an air-fuel ratio signal and a NO(x) concentration signal from two NO(x) sensors that were placed upstream and downstream of the catalytic converter. The following conclusions were reached: Measurement of NO(x) concentration by NO(x) sensors during lean combustion driving can be quite accurate without NH3 interference. This is because the NH3 concentration is extremely low in the exhaust gas at the inlet and outlet of the NO(x) storage-reduction catalyst. Use of the A/F output from the NO(x) sensor enables highly accurate A/F measurements on the fuel-rich side from approximately A/F 20. Monitoring of the NO(x) concentration output and A/F output from the NO(x) sensor installed at the outlet of the catalyst at the time of A/F rich spike has shown that it is possible to detect the restoration process of the NO(x) storage capability of the catalyst. As an index for the NO(x) storage capability of the catalyst, a NO(x) storage ratio in the catalyst during the NO(x) storage interval has been proposed. This can be calculated based on the output from the two NO(x) sensors installed at the inlet and outlet of the catalyst, and by the exhaust gas flow amount. It has been shown that this index is effective for detecting the reduced NO(x) storage capability of the catalyst.
Analysis of NO(x) storage-reduction catalyst performance under various operating conditions, using a thick film ZrO2 NO(x) sensor for measurements
Analyse der Leistungsfähigkeit eines NO(x)-Speicherkatalysators unter Verwendung eines ZrO2-Dickschicht-NO(x)-Sensors
Review of Automotive Engineering (JSAE) ; 25 , 3 ; 279-283
2004
5 Seiten, 10 Bilder, 2 Tabellen, 2 Quellen
Article (Journal)
English
Abgasanlage , Abgasemission , Abgasentgiftung , Dickschichtsensor , Emissionsminderung , geregelter Katalysator , Konzentrationsmessung , Kraftfahrzeugelektronik , Kraftstoff-Luft-Gemisch , Lambda-Sonde , Leistungsfähigkeit , Personenkraftwagen , Stickoxid , Stickoxidentfernungsanlage , Wirksamkeit , Zirkoniumdioxid
Detection of NOx Storage-Reduction Catalyst Performance by Thick Film ZrO2 NOx Sensor
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