Adaptive Moving-Average Period for Engine Knock Detection
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Solution Overview
Problem
Conventional internal combustion engine knock detection technologies face challenges in distinguishing between real knocks and pseudo knocks, leading to deteriorated knock detectability and increased mal-detection tolerance, especially under specific operation conditions such as high rotation speed and enriched air-fuel ratios.
Innovation Solution
An internal combustion engine control apparatus that employs a vibration detection unit, a knock detection window setting unit, a digital-signal processing unit, a moving-average processing unit, a knock determination unit, and a pseudo knock determination unit to differentiate between real and pseudo knocks by adjusting the moving-average period based on engine status, thereby improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If moving-average processing is performed with a period corresponding to the knock waveform width to reduce mechanical noise and electric noise, then the S/N ratio is improved, but knock detectability deteriorates when pseudo knock occurs
Solution Approach 1:
The patent applies dynamics by making the moving-average period adaptive rather than fixed. The control unit dynamically adjusts the moving-average period based on the detected knock waveform characteristics. When pseudo knock is detected, the system shortens the moving-average period to prevent noise reduction from masking the pseudo knock signal, while maintaining a longer period during normal knock conditions to effectively filter mechanical and electric noise.
Solution Approach 2:
The patent changes the parameter of the moving-average period based on operating conditions and detected waveform characteristics. By modifying this critical parameter dynamically, the system optimizes noise filtering effectiveness while avoiding the deterioration of knock detectability that occurs with fixed parameter settings, particularly in pseudo knock scenarios.
2Measurement precision
If the knock detection window area is set wider to accommodate variations in knock waveform position, then all knock waveforms are captured, but mechanical noise and electric noise are also included
Solution Approach 1:
The patent uses dynamics by adaptively adjusting the moving-average period based on the actual knock waveform characteristics detected within the fixed detection window. This dynamic adjustment allows the system to effectively filter noise while preserving the knock signal, regardless of the waveform's position within the detection window.
Solution Approach 2:
The patent applies preliminary action by first detecting the knock waveform characteristics (amplitude, frequency, position) within the detection window, then using this information to determine the appropriate moving-average period before performing the noise reduction processing. This preliminary detection enables optimized noise filtering tailored to each specific knock event.
3Adaptability or versatility
If frequency switching between first frequency and second frequency is performed based on operation status, then knock detection is optimized for different conditions, but mal-detection increases when pseudo knock occurs at either frequency
Solution Approach 1:
The patent applies dynamics by making the moving-average period adaptive to the detected waveform characteristics rather than being fixed for each frequency band. This allows the system to effectively distinguish between real knocks and pseudo knocks regardless of which frequency band is active, preventing mal-detection while maintaining adaptability to different operating conditions.
Solution Approach 2:
The patent uses feedback by continuously monitoring the vibration signal characteristics and using this information to adjust the moving-average period. The system feedbacks the detected waveform properties to the processing unit, which then optimizes the noise reduction parameters in real-time, improving reliability across different frequency switching scenarios.
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
The solution effectively suppresses the deterioration of knock detectability and mal-detection tolerance, allowing for rapid and accurate determination of knocks even when pseudo knocks occur, thereby preventing misclassification and improving engine control.
Implementation Method 1
a vibration detection unit that detects, as vibration data, a vibration or a pressure wave produced inside a cylinder
Implementation Method 2
a digital-signal processing unit that concurrently calculates, with regard to a plurality of frequencies, vibration levels, in steps of a predetermined time, that are obtained by applying a time-frequency analysis
Implementation Method 3
a moving-average processing unit that concurrently implements, with regard to the plurality of frequencies, processing in which the vibration levels in steps of the predetermined time are sequentially moving-averaged
Data Source
AI summary
An internal combustion engine control apparatus includes a pseudo knock determination unit that determines whether or not a pseudo knock has been produced in a knock detection window, based on at least one of the frequency, a status amount indicating a rotation speed of the internal combustion engine, a status amount indicating a load of the internal combustion engine, and a status amount indicating an air-fuel ratio of the internal combustion engine; and a moving-average processing unit that sets a second period to a period that is approximately the same as a first period, in the case where it has been determined that the pseudo knock was not produced, and that does not implement moving-averaging or sets the second period to a period that is narrower than the first period, in the case where it has been determined that a pseudo knock was produced.