Method and device for operating an SCR system

US9217351B2 · kind B2 · utility

Assignee

• CONTINENTAL AUTOMOTIVE GMBH · DE

Inventors

• Philippe Grass · Regensburg, DE
• Denny Schädlich · Neustadt, DE

Key dates

• Filing date: May 21, 2012
• Grant date: Dec 22, 2015
• Expiry date: Jul 27, 2032

Classification

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

Abstract

A method for operating a selective catalytic reduction (SCR) system having a urea solution supply and an ultrasound based urea concentration sensor, the measurement signal of the urea concentration sensor being representative of a propagation time of an ultrasonic pulse along a predefined path length in a fluid of the urea solution supply includes: heating at least the fluid in a detection region of the urea concentration sensor from a predefined first temperature to a predefined second temperature; during the heating, detecting the measurement signal at at least a third and fourth temperature, and in each case determining a raw concentration characteristic value as a function of the respective measurement signal, which raw concentration characteristic value is representative of the propagation time of the ultrasonic pulse; and determining a concentration characteristic value, representative of a concentration of urea in the fluid, as a function of the raw concentration characteristic values.