ECU Knock Detection Signal Saturation Control
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Solution Overview
Problem
Conventional knock detection methods in internal combustion engines face challenges in accurately detecting small knocks due to saturation of the output signal from amplification circuits, leading to deterioration in knock determination accuracy, especially when engine operation states change rapidly.
Innovation Solution
An electronic control unit (ECU) with a sensor, sensor signal amplifier, and A/D converter that adjusts amplification power based on the amplitude of the sensor signal and determination results, preventing signal saturation and enabling quick adjustments to accurately detect small abnormal combustion events like knocks and pre-ignitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amplification power of the amplification circuit is increased to improve knock detection accuracy, then the detection accuracy of small knocks is improved, but the output signal becomes saturated which deteriorates the accuracy of knock determination
Solution Approach 1:
The amplification power is made dynamically adjustable rather than fixed. The control unit changes the amplification power based on the detected sensor signal amplitude, allowing the system to adapt to varying knock intensities and prevent saturation while maintaining detection accuracy for small knocks
Solution Approach 2:
The system uses feedback from the sensor signal amplitude detection to control the amplification power. The control unit monitors the signal amplitude and adjusts the amplification power accordingly, creating a closed-loop control system that prevents signal saturation while improving knock detection accuracy
2Adaptability or versatility
If the amplification power is switched based on engine rotation speed and past signal statistics, then the amplification power adjustment is performed, but the adjustment cannot respond quickly enough when the sensor signal amplitude changes drastically
Solution Approach 1:
The system implements real-time feedback control where the sensor signal amplitude is continuously monitored and immediately used to adjust the amplification power. This feedback mechanism enables rapid response to drastic changes in signal amplitude, overcoming the delay inherent in methods based on past statistics
Solution Approach 2:
The control unit proactively adjusts the amplification power based on the current signal amplitude before saturation can occur. By detecting the signal amplitude and preemptively adjusting the amplification power, the system prevents the lag problem associated with reactive adjustments based on past data
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 improves the accuracy of abnormal combustion detection by preventing signal saturation and allowing for timely adjustments in amplification power, enhancing the detection of small knocks and pre-ignitions while maintaining high resolution.
Implementation Method 1
a knock sensor (e.g., a vibration sensor)
Implementation Method 2
Japanese Patent Laid-Open No. 2006-177259 (JP '259), a knock detection method is disclosed for accurately detecting a knock
Implementation Method 3
an amplification circuit having the variable amplification power
Implementation Method 4
a high resolution A/D converter... a ΔΣ type A/D converter
Data Source
AI summary
An electronic control unit (ECU), for use with an internal combustion engine, determines whether an abnormal combustion has occurred in the engine. The ECU uses a sensor signal amplifier to amplify a sensor signal from a sensor by changing an amplification power of the sensor signal and an A/D converter to convert the sensor signal amplified to a digital signal (i.e., a digitized sensor signal). The ECU uses an abnormal combustion detector to determine whether an abnormal combustion has occurred based on a characteristic of a waveform of the digitized sensor signal, and performs an abnormal combustion prevention control to prevent the abnormal combustion when an abnormal combustion is detected. An amplification controller is used to set the amplification power of the sensor signal amplifier based on the amplitude of the digitized sensor signal and a determination result of the abnormal combustion by the abnormal combustion detector.