Method for monitoring the operability of a lambda sensor

US6439038B1 · kind B1 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

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

Key dates

• Filing date: Jul 31, 1998
• Grant date: Aug 27, 2002
• Expiry date: Jul 31, 2018

Classification

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

Abstract

A method of monitoring the dynamic operability of a lambda sensor (monitor sensor), disposed in the exhaust gas stream of an internal combustion engine downstream of a catalytic converter. Once the engine operating state of overrun fuel cutoff is detected, the rich/lean switching time of the monitor sensor disposed downstream of the catalytic converter is ascertained and weighted as a function of the air flow rate (LMM) in the intake conduit. By comparing the mean value of the thus-obtained switching time with a limit value and ensuing evaluation, the operability of the monitor sensor is diagnosed. Operability is assured if the switching time is below the limit value. Other diagnostic criteria are formed by evaluating the signal level of the monitor sensor.