Knock Detection Waveform Correction for Combustion Engines
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Solution Overview
Problem
Existing methods for determining knocking in internal combustion engines can lead to erroneous conclusions due to vibrations caused by factors other than knocking, such as intake or exhaust valve seating and injector actuation, which can result in incorrect waveform analysis.
Innovation Solution
A device using a crank position sensor and a knock sensor to detect and analyze the waveform of vibrations, comparing them to a predetermined waveform model, with correction techniques to differentiate between knocking and non-knocking vibrations based on magnitude and frequency patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If waveform shape comparison is used for knock detection, then false positives from non-knock vibrations are reduced, but false negatives occur when knock vibrations are masked by other vibrations
Solution Approach 1:
The patent segments the vibration detection process into multiple independent analysis methods: statistical processing (effective value comparison), waveform shape analysis (pattern matching), and temporal determination (timing-based detection). Each method processes the vibration signal independently and their results are combined through logical operations to achieve more reliable knock detection than any single method alone.
Solution Approach 2:
The patent merges multiple detection approaches by combining their output signals through logical operations. The statistical processing result, waveform shape match result, and temporal determination result are integrated to produce a final knock determination, allowing the system to leverage the strengths of each method while compensating for their individual weaknesses.
2Measurement precision
If multiple determination methods are combined, then determination accuracy improves, but system complexity increases
Solution Approach 1:
The complex determination system is segmented into distinct functional modules: a statistical processing unit that calculates effective values, a waveform shape analysis unit that performs pattern matching, and a temporal determination unit that analyzes timing characteristics. Each module operates independently with clearly defined inputs and outputs, making the overall complex system manageable through modular design.
Solution Approach 2:
The vibration detection system is designed with multi-functionality, where a single vibration sensor serves multiple purposes: providing signals for statistical analysis, waveform pattern matching, and temporal analysis. This universal approach allows one sensor to support multiple determination methods without requiring separate sensing systems, thereby managing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise determination of knocking presence or absence by reducing noise effects and preventing false negatives or positives, thereby improving the accuracy of knocking detection.
Implementation Method 1
a knock sensor detecting magnitude of vibration of the internal combustion engine
Implementation Method 2
a crank position sensor detecting a crank angle of the internal combustion engine
Data Source
AI summary
An engine ECU executes a program including the steps of: calculating an absolute value ΔS(I) of the deviation of the vibration waveform detected by a knock sensor and a knock waveform model from each other at each crank angle; when ΔS(I) greater than threshold value ΔS(0) is present and the number of ΔS(I) greater than threshold value ΔS(0) is equal to or smaller than Q(1), correcting the vibration waveform; calculating a correlation coefficient K which is a value related to the deviation of the corrected vibration waveform and the knock waveform model from each other; and when the number of ΔS(I) greater than threshold value ΔS(0) is greater than predetermined number Q(1), calculating the correlation coefficient K without correcting the vibration waveform. Based on the correlation coefficient K, whether knocking is present or absent is determined.