Knock Detection Frequency Band Selection
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Solution Overview
Problem
Existing knock determining devices for internal combustion engines face challenges in accurately distinguishing between knock and noise, particularly due to background engine noise from fuel injection valves, leading to reduced knock detection performance.
Innovation Solution
A device and method that maximize the number of specific frequency bands for knock determination by excluding only necessary frequency regions with high false-detection causing noise, using a vibration detector, intensity computing unit, background-noise computing unit, and frequency computing unit to determine the occurrence of knock based on vibration intensity in specific frequency regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency bands are excluded to avoid false detection from background engine noise, then false detection is reduced, but the number of frequency bands available for knock detection is reduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the exclusion criteria based on the ratio of false-detection causing noise intensity to background noise intensity. When this ratio exceeds a threshold, frequency bands are excluded; when it falls below, they are included. This dynamic parameter adjustment resolves the contradiction by adapting the number of frequency bands to actual noise conditions, maintaining detection accuracy while maximizing usable frequency regions.
Solution Approach 2:
The invention implements dynamics by making the frequency band exclusion decision variable rather than fixed. The system continuously monitors noise characteristics and adjusts which frequency bands to exclude in real-time based on current engine operating conditions. This dynamic approach allows the system to include more frequency bands when noise is low and exclude only necessary bands when noise is high, resolving the contradiction between reliability and quantity.
2Measurement precision
If more frequency bands are used for knock detection, then detection coverage is improved, but false detection from background noise increases
Solution Approach 1:
The patent changes the parameter of frequency band selection based on the noise-to-background ratio. By calculating this ratio for each frequency band and comparing it to a threshold, the system dynamically determines which bands to include or exclude. This resolves the contradiction by allowing broader detection coverage when noise is low while automatically restricting to cleaner bands when noise is high.
Solution Approach 2:
The invention introduces an intermediary mechanism - the noise ratio calculation and threshold comparison process - that mediates between the desire for broad detection coverage and the need to avoid false detections. This intermediary evaluates each frequency band's suitability and makes inclusion/exclusion decisions, allowing the system to optimize both detection coverage and false detection rejection simultaneously.
3Reliability
If frequency bands with high noise intensity are excluded, then false detection is minimized, but knock detection performance is reduced
Solution Approach 1:
The patent applies parameter changes by adjusting the exclusion threshold based on the calculated noise-to-background ratio. When the ratio is high, frequency bands are excluded to reject false detections; when the ratio is low, bands are included to maintain detection performance. This dynamic parameter adjustment resolves the contradiction by adapting exclusion decisions to actual noise conditions.
Solution Approach 2:
The invention implements dynamics by making the frequency band exclusion status changeable based on real-time noise assessment. Rather than permanently excluding noisy frequency bands, the system temporarily excludes them only when noise levels justify such action, and reinstates them when conditions improve. This dynamic behavior maintains both false detection rejection and detection performance.
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 reduces the likelihood of false negatives in knock detection, allowing for more accurate identification of knock occurrences by utilizing a broader range of specific frequency regions while minimizing false detections.
Implementation Method 1
a vibration detector that detects vibration of the internal combustion engine and produces a signal corresponding to the vibration
Data Source
AI summary
An internal combustion engine knock determining device includes a vibration detector that produces a signal corresponding to engine vibration, an intensity computing unit that retrieves vibrational components in a plurality of frequency regions in which vibration intensity peaks are located when knock occurs, a background-noise computing unit that calculates background noise caused by factors other than knock, a frequency computing unit that determines specific frequency regions from which to determine whether knock is occurring by excluding certain frequency regions designated as frequency regions requiring exclusion due to the intensity of false-detection causing noise as a proportion of the background noise in the certain regions, and a knock determining unit that determines the occurrence of knock based on the vibration intensity in the specific frequency regions obtained by excluding the frequency regions requiring exclusion, wherein the number of specific frequency regions is increased to improve the accuracy of knock detection.