Method and apparatus for detecting combustion knock from the ionic current in an internal combustion engine

US6230546A · kind A · utility

Assignees

• Temic Telefunken Microelectronik · DE
• Daimlerchrysler AG · US

Inventors

• Hartung Wilstermann · Gaildorf, DE
• Peter Hohner · Echterdingen, DE
• Peter Bertelshofer · Zirndorf, DE
• Juergen Schenk · Albershausen, DE

Key dates

• Filing date: Dec 14, 1998
• Grant date: May 15, 2001
• Expiry date: Dec 14, 2018

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L23/225
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and an apparatus for detecting knocking combustion in an internal combustion engine, by evaluating the ionic current signal sensed in the combustion chamber, is especially adapted to correct or compensate the ionic current signal for longterm variations arising therein, for example due to variations in the composition of the fuel as a result of contamination with metallic components or the like. Thereby, erroneous knock recognition is prevented. To achieve this, a frequency-filtered time-sampled knocking component integral of the ionic current signal generated in the present combustion cycle is multiplied by a correction value determined from at least one integral value of the ionic current signal generated during at least one prior combustion cycle. The correction value is preferably a time-weighted combination of plural difference values that are respectively determined by subtracting an average integrated value of the ionic current signal from the knocking component integral of the ionic current signal in plural prior combustion cycles, and that are stored in successive positions of a shift register. If the final corrected knocking component integral falls outside of an…