Knock Detection Using Dynamic Angular Window Adjustment
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Solution Overview
Problem
Existing methods for detecting knock in internal combustion engines are affected by parasitic noises from injector closure, leading to non-detections or wrongful detections, especially when the angular position of injector closure varies rapidly or discontinuously.
Innovation Solution
A method using a system with an acoustic sensor and processor that applies a bandpass filter and an adjustable gain-correction function, defined by a calibration value and angular points, to correct for parasitic noise, ensuring accurate knock detection by adjusting the gain based on the angular position of injector closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed observation time window is used for knock detection, then parasitic noises outside the window are excluded, but injector closure noise that falls within the window causes wrongful detections or non-detections
Solution Approach 1:
The patent applies dynamics by making the observation window angular position variable rather than fixed. The observation window is dynamically adjusted based on the actual injector closure angular position detected during engine operation. This allows the system to adapt the observation window position in real-time to exclude injector closure noise while maintaining coverage of the actual knock event window, thereby resolving the contradiction between reliability and precision.
2Adaptability or versatility
If the angular position of injector closure varies rapidly or discontinuously, then the fixed observation window cannot track the noise position, leading to cases of non-detection and wrongful detection
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual injector closure angular position and using this information to adjust the observation window position in subsequent cycles. The system measures the injector closure position, compares it with the current observation window position, and dynamically repositions the window to maintain optimal alignment. This closed-loop feedback mechanism ensures reliable detection even when injector closure position varies rapidly or discontinuously.
3Measurement precision
If the observation window is adjusted to track injector closure noise, then wrongful detections are reduced, but the complexity of the detection system increases
Solution Approach 1:
The patent applies self-service by having the system use its own operational data (injector closure position from existing sensors and control units) to automatically adjust its detection parameters. The engine control unit leverages information already available from injection timing signals and crankshaft position sensors to dynamically position the observation window, eliminating the need for external complex adjustment mechanisms while improving detection precision.
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 the influence of parasitic noise within the observation window, improving detection accuracy and reducing uncertainty in ignition timing adjustments, while maintaining real-time processing without substantial modifications to existing software structures.
Implementation Method 1
a knock-detection function, based on an acoustic, and in particular piezoelectric, sensor installed on the cylinder casing
Implementation Method 2
applying a bandpass filter in order to preserve only the frequency range of interest for knock
Data Source
AI summary
A method for managing knock in a cylinder of an internal combustion engine, in a system including at least one acoustic sensor and a processor, in order to take into account acoustic pollution resulting from a noise, the method including: forming and digitizing the signals of the acoustic sensor, applying a bandpass filter to obtain a filtered noise, determining an adjustable gain-correction function using a gain-correction curve and, depending on the angular position of the end of injection, the point on the gain-correction curve to be used to convert the filtered noise into a corrected knock score, comparing a corrected knock score thus obtained to a knock decision threshold, to correct the timing advance, the gain-correction curve being defined by a calibration value and four angular points obtained by calculation based on the start and end positions of a knock-observation window and on a known characteristic of the noise.