Engine Knock Detection Dynamic Gain Adjustment
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Solution Overview
Problem
Existing engine knock detection systems face challenges in accurately detecting knock due to rapidly changing background noise levels, which can lead to false indications and reduced engine fuel efficiency, especially with noise sources like direct fuel injectors and poppet valves.
Innovation Solution
The method involves adjusting a rectified and integrated knock sensor signal using gain tables or functions to compensate for varying engine noise sources, allowing for improved signal-to-noise ratio and accurate knock detection without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional knock detection systems are used without compensation for background noise, then the system structure remains simple, but knock detection accuracy deteriorates due to rapidly changing background noise levels
Solution Approach 1:
The system pre-calculates and stores multiple gain values in lookup tables corresponding to different engine operating conditions (speed, load, temperature) and different noise sources (port injector, direct injector, valve timing). During operation, the appropriate gain value is selected based on current conditions, compensating for background noise before knock detection. This preliminary preparation allows accurate knock detection without complex real-time calculations.
Solution Approach 2:
The system dynamically changes the gain parameter applied to knock sensor signals based on engine operating conditions. By selecting different gain values from lookup tables according to engine speed, load, temperature, and active noise sources, the system adapts the detection sensitivity to match current background noise levels, maintaining accurate knock detection across varying operating conditions.
2Measurement precision
If multiple gain tables are used to compensate for different noise sources, then knock detection accuracy improves, but device complexity increases
Solution Approach 1:
The system divides the knock detection compensation into separate segments for different noise sources. Individual gain tables are created for port fuel injector noise, direct fuel injector noise, and variable valve timing noise, allowing each noise source to be compensated independently. This segmentation enables precise compensation without requiring a single complex gain table covering all conditions.
Solution Approach 2:
The system dynamically selects and applies the appropriate gain table based on current engine operating conditions and active noise sources. The gain application is not static but adapts in real-time to changing conditions, selecting the most appropriate compensation level from multiple pre-calculated gain tables to match current operational state.
3Reliability
If background noise levels are not compensated, then the system operates quickly without complex calculations, but false knock indications increase reducing fuel efficiency
Solution Approach 1:
Gain values for compensating different noise sources are pre-calculated and stored in lookup tables during system setup or calibration. During engine operation, the system simply retrieves the appropriate pre-calculated gain value based on current conditions rather than performing complex real-time noise analysis, maintaining fast response while improving reliability.
Solution Approach 2:
The system uses feedback from engine operating condition sensors (speed, load, temperature, injector status, valve timing) to select the appropriate gain value from lookup tables. This feedback mechanism ensures the correct compensation is applied based on actual operating conditions, reducing false knock indications while maintaining efficient processing.
Data Source
AI summary
Methods and systems for adjusting engine knock control system dynamic gains are presented. In one example, a plurality of tables or functions output gain values, each of which is adjusted via a unique weighting factor. A rectified and integrated engine knock sensor level is adjusted according to a sum of weighted gain output values of the plurality of tables or functions.