Method for determining a quality of a reducing agent solution containing ammonia used to reduce nitrite oxide

US9737853B2 · kind B2 · utility

Assignee

• Daimler AG · DE

Inventors

• Bernd Christner · Altensteig, DE
• Uwe Hofmann · Würzburg, DE
• Tobias Peters · Gernrode, DE

Key dates

• Filing date: Jun 29, 2012
• Grant date: Aug 22, 2017
• Expiry date: May 6, 2034

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T10/40
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A determination of a quality of a reducing agent solution containing ammonia used to reduce nitrogen oxides involves actuating a metering unit that delivers metered quantities of reducing agent solution into an engine's discharged exhaust gas and determining an efficiency value that is at least correlated with the efficiency of the SCR catalytic converter and comparing the efficiency value to a predefinable limit value. If an efficiency value not corresponding to proper functioning of the SCR exhaust emission control system is identified by the comparison, a switch is made to a diagnostic mode in a second method step. If a predefinable deviation of the efficiency value from a limit value is identified after expiration of the second method step time period, a third method step is performed for conditioning the SCR catalytic converter. A fourth step involves an adaptation mode in which a deviation from the efficiency value is determined.