Engine Knock Determination Using Waveform Correlation
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Solution Overview
Problem
Existing knock determination methods for internal combustion engines often incorrectly identify noise as knocking due to similar vibration intensities, leading to inaccurate determination values and potential delays in correction.
Innovation Solution
A knock determination device that uses a knock sensor and an operation unit to detect vibration intensity and waveform, calculating first and second values based on comparisons with a reference waveform model, and corrects the determination value based on the number of values exceeding a threshold in continuous ignition cycles, distinguishing between knocking and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the determination value is corrected based on all vibration intensity data including noise, then the correction speed increases, but the accuracy of knock detection deteriorates due to false positives from noise
Solution Approach 1:
The patent extracts and separates noise components from knock vibration components by comparing waveform shapes against a reference waveform model. Only vibration data matching the characteristic knock waveform pattern is used for correction, while noise is excluded. This resolves the contradiction by enabling fast correction through sufficient data while maintaining accuracy through selective data filtering.
Solution Approach 2:
The patent applies different quality criteria to different data points by evaluating waveform characteristics locally. Vibration events are classified as either knock or noise based on their specific waveform properties (shape, duration, frequency pattern) rather than treating all vibrations uniformly. This allows accurate differentiation between knock and noise while maintaining efficient correction processes.
2Measurement precision
If the determination value is corrected only using data from cycles with waveform matching, then the accuracy of knock detection improves, but the correction speed decreases due to insufficient data
Solution Approach 1:
The patent performs preliminary classification of vibration events by comparing waveforms against a reference model before using them for correction. By pre-identifying and filtering knock-specific waveform patterns, the system ensures that only relevant data accumulates toward correction, preventing data insufficiency while maintaining high accuracy through selective data collection.
3Device complexity
If vibration intensity alone is used for knock determination, then the device complexity remains low, but the reliability of knock detection deteriorates due to noise interference
Solution Approach 1:
The patent transitions from one-dimensional vibration intensity measurement to two-dimensional analysis by incorporating waveform shape characteristics as an additional dimension. The reference waveform model comparison adds temporal and shape-based criteria, enabling reliable knock identification while maintaining relatively simple device architecture through software-based pattern recognition.
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 accurate and quick correction of determination values, reducing false positives and negatives in knock detection, thereby improving the reliability of knock determination.
Implementation Method 1
a knock sensor detecting vibration intensity of an internal combustion engine
Data Source
AI summary
An engine ECU executes a program including: the step of increasing a determination value by a correction amount if the number of knock intensities not lower than the determination value is not smaller than a threshold value among knock intensities of a plurality of predetermined number of continuous ignition cycles; and the step of increasing the determination value by a correction amount if the number of knock intensities not smaller than the determination value is not smaller than a threshold value, among knock intensities of a plurality of ignition cycles satisfying the condition that a coefficient of correlation calculated by comparing a vibration waveform and a knock waveform model is not smaller than a threshold value, of the knock intensities of a plurality of predetermined continuous ignition cycles.