Knock Detection Using Vibration Waveform Segmentation
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Solution Overview
Problem
Existing knock control systems for internal combustion engines face challenges in accurately determining knock occurrence due to noise vibrations from components like piston slap, injectors, and valves, leading to inappropriate ignition timing adjustments.
Innovation Solution
An ignition timing control device that detects vibration intensity values and waveforms, calculates deviations from stored waveforms to differentiate between knock and noise vibrations, and adjusts ignition timing based on accurate knock determination, excluding noise-induced intensity values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If knock intensity values are detected from vibration signals, then knock detection capability is improved, but false detection of knock due to noise vibrations from piston slap, injectors, and valves increases
Solution Approach 1:
The patent segments the vibration signal analysis into two distinct components: intensity value detection (amplitude) and waveform pattern recognition (temporal structure). By separating these analysis dimensions, the system can identify knock based on both intensity and characteristic waveform patterns, while filtering out noise vibrations that may have similar intensity but different waveform characteristics.
Solution Approach 2:
The patent transforms the vibration signal into a different representation domain by analyzing waveform patterns and temporal characteristics. This transformation allows the system to distinguish between knock and noise vibrations based on their unique waveform signatures, similar to how color changes can differentiate between different substances.
2Device complexity
If a fixed knock determination level is used, then the control system is simple, but accurate knock detection cannot be achieved due to manufacturing variations and temporal changes
Solution Approach 1:
The patent implements dynamic adaptation of the knock determination level by continuously learning from operational data. The system adjusts the determination level based on detected waveform patterns and intensity values, allowing it to adapt to manufacturing variations and temporal changes in engine and sensor characteristics, thereby maintaining high detection accuracy without requiring complex manual calibration.
Solution Approach 2:
The system performs self-calibration by automatically adjusting the knock determination level based on its own operational experience. Through continuous monitoring and pattern recognition, the system learns the specific characteristics of its own sensor and engine, eliminating the need for external calibration procedures or complex adjustment mechanisms.
3Device complexity
If vibration signals from all sources are used for knock detection, then the detection system is simple, but correct determination of knocking occurrence state becomes difficult
Solution Approach 1:
The patent segments the vibration signal characteristics into intensity components and waveform pattern components. By analyzing both segments separately and combining the results, the system can distinguish between knock vibrations and noise vibrations from other engine components, thereby improving determination accuracy without significantly increasing system complexity.
Solution Approach 2:
The patent transforms vibration signals into waveform pattern representations that highlight the unique temporal characteristics of knock events. This transformation enables the system to differentiate between knock and non-knock vibrations based on their distinct waveform signatures, improving reliability while maintaining relatively simple detection hardware.
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 enables precise determination of knock occurrence, suppressing noise influence and allowing for appropriate ignition timing control, thereby improving engine performance and reducing misfire risks.
Implementation Method 1
a knock sensor for detecting knock in the internal combustion engine; a knock intensity value detector for detecting knock intensity values V effective for knock detection from signals of the knock sensor
Data Source
AI summary
An engine ECU executes a program including a step of calculating intensity values LOG(V), a step of detecting vibration waveforms, a step of calculating a correlation coefficient K based on vibration waveforms, a step of preparing frequency distribution of intensity values LOG(V) smaller than a threshold V(1) and intensity values LOG(V) in an ignition cycle where correlation coefficient K is larger than a threshold K(1), a step of calculating a knock determination level V(KD) based on a median V(50) and a standard deviation σ of intensity values LOG(V), and a step of counting the number of intensity values LOG(V) larger than knock determination level V(KD) as the number of times that knocking has occurred.