Knock Detection Using Waveform Noise Filtering
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Solution Overview
Problem
Existing knocking determination methods for internal combustion engines often lead to erroneous conclusions due to vibrations caused by valve seating, injector actuation, or high-pressure pumps, which can result in incorrect identification of knocking occurrence.
Innovation Solution
A knocking determination device that uses a crank position sensor and a knock sensor to detect vibrations at specific intervals, removes noise portions with magnitudes greater than a predetermined reference magnitude from the waveform, and compares the cleaned waveform with a knock waveform model to accurately determine knocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If knocking determination is based on waveform analysis, then knocking detection capability is improved, but false detection increases due to noise from valve seating, injector actuation, or high-pressure pump
Solution Approach 1:
The detection process is divided into two distinct segments: statistical processing for initial knock detection and waveform analysis for verification. This segmentation allows each method to focus on its strengths while compensating for its weaknesses, reducing false detections caused by noise from valve seating, injector actuation, or high-pressure pump operations.
Solution Approach 2:
Statistical processing acts as an intermediary between the knock sensor and waveform analysis. It pre-processes the sensor output to identify potential knock events, which then triggers selective waveform analysis. This intermediary layer filters out many false signals before they reach the waveform analysis stage, improving reliability while maintaining detection accuracy.
2Device complexity
If only statistical processing is used for knock determination, then computational complexity is reduced, but detection accuracy decreases due to inability to distinguish knock from noise
Solution Approach 1:
The system employs periodic waveform analysis at specific intervals rather than continuous analysis. Waveform analysis is triggered periodically when statistical processing indicates a potential knock event, and also at predetermined intervals to capture low-magnitude knock signals. This periodic approach maintains detection accuracy while limiting computational complexity.
Solution Approach 2:
Instead of performing full waveform analysis continuously, the system applies partial waveform analysis only when necessary - when statistical processing detects potential knock or at predetermined intervals. This partial action approach maintains sufficient detection accuracy while significantly reducing overall computational complexity compared to continuous waveform analysis.
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 significantly reduces erroneous determinations of knocking occurrence, ensuring accurate identification by differentiating between knocking vibrations and noise-induced vibrations.
Implementation Method 1
a knock sensor detecting the magnitude of vibration in the internal combustion engine in such a manner as to correspond to the crank angle
Implementation Method 2
a crank position sensor detecting a crank angle of the internal combustion engine
Data Source
AI summary
Out of synthesized waveforms of vibrations in a first frequency band A to a third frequency band C, a knock magnitude N is calculated by using a portion β having an integrated value greater than a reference magnitude in a knock region but not using a portion having an integrated value greater than the reference magnitude out of the knock region (i.e., a region obtained by excluding the knock region from a knock detecting gate). In a case where knock magnitude N is greater than a determination value V(KX), it is determined that knocking occurs. In contrast, in a case where knock magnitude N is not greater than determination value V(KX), it is determined that no knocking occurs.