Method for purifying exhaust gas of an internal combustion engine

US7028464B2 · kind B2 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Gerd Rösel · Dresden, DE
• Hong Zhang · Schwieberdingen, DE

Key dates

• Filing date: Mar 8, 2002
• Grant date: Apr 18, 2006
• Expiry date: Jul 22, 2022

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F02D2041/1468
• WIPO field: Engines, pumps, turbines
• WIPO sector: Mechanical engineering

Abstract

A method for purifying the exhaust gas from an internal combustion engine, which is operated under lambda-based closed loop control and which has an exhaust gas tract in which is located a catalytic converter, is provided. According to this method, a pre-converter lambda value for the exhaust gas is continuously sensed upstream of the catalytic converter, from which a pre-converter lambda signal is generated, and this pre-converter lambda signal is used as the reference variable for the lambda control loop. A post-converter lambda value for the exhaust gas is continuously sensed downstream from the converter, from which a post-converter lambda signal is generated, this being a monotonically decreasing function of the lambda value for the exhaust gas downstream from the catalytic converter. The post-converter lambda signal is used in a trimming control loop to apply a correction to the lambda control loop, whereby a measurement signal is generated which, at least below a certain value of lambda close to lambda=1, is a strictly monotonically increasing or monotonically decreasing function of the lambda value for the exhaust gas downstream from the catalytic converter. For levels of t…