Knock Signal Normalization for Internal Combustion Engine
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Solution Overview
Problem
Existing knock control apparatuses for internal combustion engines face challenges in accurately setting knock determination thresholds due to variations in average value and standard deviation of knock signals with changing operating states, leading to erroneous knock detection and omission, particularly when normalization methods affect the correlation between actual and detected knocks.
Innovation Solution
A knock control apparatus that normalizes knock signals using base statistics calculated from both current and last values of the knock signal, with interpolation based on the engine's operating state, to set adequate knock determination thresholds, thereby enhancing detection performance without lowering the correlation between actual and detected knocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If normalization is applied using standard deviation to suppress variances of knock signal, then erroneous knock detection is improved, but the vibration component resulting from knock occurrence is normalized and correlation in magnitude between actual knock and detected knock is lowered
Solution Approach 1:
The patent extracts only the average value component from the knock signal statistics, deliberately excluding the standard deviation component. This extraction approach allows suppression of operating state variances through average value normalization while preserving the magnitude correlation of actual knock vibrations, as the standard deviation (which correlates with knock magnitude) is not used for normalization.
Solution Approach 2:
The patent introduces an intermediary approach by using only the average value as a mediator for normalization, rather than using the full statistical description (mean and standard deviation). This intermediary normalization method achieves the dual goal of suppressing operating state variances while maintaining knock magnitude correlation, avoiding the harmful effect of normalizing the knock vibration component.
2Measurement precision
If knock determination threshold is set using gain and offset matched to average knock signal, then detection baseline is established, but it takes large number of man-hours to match parameters in response to variance with operating state changes
Solution Approach 1:
The system performs self-adjustment by automatically calculating the average value of the knock signal for each operating state and using this self-derived statistic for normalization. This eliminates the need for external manual parameter matching, as the system serves itself by generating the normalization baseline from its own operational data, thereby reducing man-hours to zero for parameter matching.
Solution Approach 2:
The patent changes the normalization parameter from fixed pre-matched gain and offset values to a dynamic parameter (average value) that automatically adapts to operating state changes. This parameter change enables the knock determination threshold to self-adjust with operating conditions, eliminating the time-consuming manual matching process while maintaining detection accuracy.
3Power
If spark timing is advanced to maximize torque, then output torque is enhanced, but knock occurs more readily
Solution Approach 1:
The patent implements dynamic spark timing control that continuously adjusts spark timing based on real-time knock detection. The system operates at advanced spark timing (maximizing torque) when no knock is detected, and dynamically retards spark timing when knock is detected, creating a dynamic balance between torque maximization and knock suppression rather than using a fixed conservative timing setting.
Solution Approach 2:
The system employs feedback control by using knock detection results to adjust spark timing. The knock detection apparatus provides feedback about knock occurrence, and this feedback is used to modify spark timing in real-time, enabling the engine to operate at torque-maximizing advanced timing while automatically preventing knock through closed-loop control.
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 apparatus effectively suppresses erroneous knock detection and omission, maintaining the correlation between actual and detected knocks, even in varying operating states, by using base statistics that account for the engine's variance, thus improving overall knock detection performance.
Implementation Method 1
when a knock occurs while the internal combustion engine is in operation, vibrations in a specific frequency band are known to occur according to a bore diameter of the internal combustion engine or a vibration mode of the knock. Hence, a knock is detected by measuring vibration intensity
Data Source
AI summary
A knock control apparatus for an internal combustion engine includes a knock signal normalization portion that normalizes a knock signal using base statistics calculated on the basis of the knock signal. The knock signal normalization portion calculates base statistics on the basis of a last value and a current value of the knock signal and normalizes the knock signal using a base statistic interpolated according to an operating state.