Knock Control Apparatus Dynamic Threshold Adjustment
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Solution Overview
Problem
Conventional knock control systems for internal combustion engines face challenges in setting a precise knock determination level due to manufacturing variations and distribution profile issues, leading to inappropriate knock detection and potential engine damage or output loss.
Innovation Solution
A knock control apparatus that performs frequency analysis using discrete Fourier transform on knock sensor signals to calculate knock intensity, variance, and standard deviation, and adjusts a confidence coefficient based on these metrics to set an accurate knock determination level, correcting for manufacturing and operational variations without requiring close matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional knock determination level setting methods are used, then the system can detect knock, but the detection precision is insufficient due to manufacturing variations and distribution profile issues
Solution Approach 1:
The system performs frequency analysis on knock sensor signals to calculate knock intensity, then uses the calculated variance and standard deviation to feedback-adjust the knock determination level dynamically, improving both detection precision and reliability
Solution Approach 2:
The invention changes the parameter calculation method by using variance and standard deviation of knock intensity distribution instead of fixed thresholds, allowing the knock determination level to adapt to manufacturing variations and different engine conditions
2Measurement precision
If the knock determination level is set too high, then false knock detection is reduced, but actual knock occurrences are missed leading to engine damage
Solution Approach 1:
The knock determination level is made dynamic rather than fixed, adjusting based on calculated statistical parameters (variance and standard deviation) of the knock intensity distribution, enabling the system to adapt to varying engine conditions and prevent both false detection and missed detection
Solution Approach 2:
The system performs preliminary frequency analysis and statistical calculation on knock sensor signals to establish an appropriate determination level before actual knock detection occurs, ensuring the threshold is optimally set for current engine conditions
3Measurement precision
If the knock determination level is set too low, then knock detection sensitivity is improved, but false detection increases causing ignition timing retardation and output loss
Solution Approach 1:
The system uses feedback from statistical analysis of knock intensity distribution to dynamically adjust the determination level, preventing false detection while maintaining high sensitivity for actual knock events, thus preserving engine output
4Measurement precision
If close matching of gain and offset is performed, then knock detection precision is improved for specific engines, but the system complexity and matching process time increase
Solution Approach 1:
The system performs self-adjustment by automatically calculating the knock determination level based on statistical parameters derived from knock sensor signals, eliminating the need for manual close matching of gain and offset while maintaining high detection precision
Solution Approach 2:
The invention changes from fixed parameters requiring manual matching to dynamically calculated parameters (variance and standard deviation) that automatically adapt to each engine's characteristics, reducing system complexity
5Measurement precision
If logarithmic transformation and statistical processing are applied, then knock determination is improved for lognormal distribution, but the system fails when distribution does not become lognormal
Solution Approach 1:
The system calculates variance and standard deviation directly from the knock intensity frequency distribution without requiring logarithmic transformation, making it adaptable to any distribution profile while maintaining detection accuracy
Solution Approach 2:
The invention creates a universal knock detection method that works with any frequency distribution profile by using general statistical parameters (variance and standard deviation) rather than distribution-specific transformations, enhancing versatility
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
Enables precise detection of knock occurrences with high accuracy, avoiding engine damage and optimizing output by automatically adjusting the knock determination level to suit various factors.
Implementation Method 1
a knock sensor for detecting knock of an internal combustion engine
Implementation Method 2
a signal processing section for performing frequency analysis using discrete Fourier transform on a knock sensor signal output from the knock sensor for each cylinder and each ignition cycle to calculate a knock intensity
Data Source
AI summary
A knock control apparatus includes: a knock sensor for detecting knock of an internal combustion engine; a signal processing section for calculating a knock intensity; and knock determination level setting sections: for calculating an average value of the knock intensity; for calculating, based on the average value, an overall variance of the knock intensity of an entirety of a frequency distribution, a higher variance of the knock intensity above the average value, and a lower variance of the knock intensity below the average value; for calculating a standard deviation of the knock intensity from the overall variance; for presetting a value allowing the frequency distribution of the knock intensity to be a predetermined confidence interval as a confidence coefficient; and for setting a sum of the average value and a value obtained by multiplying the standard deviation by the corrected confidence coefficient as a knock determination level.