Engine Knock Detection Noise Mapping Update
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Solution Overview
Problem
Internal combustion engine knock detection systems face challenges in accurately diagnosing knock due to varying background noise levels caused by changes in engine temperature, ethanol content, fuel injection type, air-fuel mixture, and deactivated cylinders, leading to false positives or negatives in knock detection.
Innovation Solution
A knock detection system that generates an indicator of present operating conditions and determines background noise levels based on engine speed and load, updating noise mappings when operating conditions change, and calculates a knock value using vibration intensity and noise levels to selectively diagnose knock and adjust spark timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If background noise is not updated when operating conditions change, then the system structure remains simple, but knock detection accuracy deteriorates due to false positives or negatives
Solution Approach 1:
The background noise mapping is dynamically updated based on changing operating conditions. When conditions such as engine temperature, ethanol content, or fuel injection type change, the system triggers a relearning process that updates the noise mapping, allowing the system to adapt to varying operating states while maintaining accurate knock detection
Solution Approach 2:
The system changes the parameters stored in the background noise mapping by relearning noise levels under different operating conditions. This involves modifying the mapping table with new noise values corresponding to different engine states, thereby improving detection accuracy without requiring complete system redesign
2Measurement precision
If the system continuously monitors and updates background noise under all conditions, then knock detection accuracy improves, but processing time and computational load increase
Solution Approach 1:
The system performs preliminary learning of background noise levels during engine operation and stores them in a mapping structure before knock detection is required. This pre-processing allows rapid knock detection without time-consuming real-time noise analysis, as the noise characteristics are already characterized and stored for quick reference
Solution Approach 2:
The system uses feedback from knock detection results to validate and refine the background noise mapping. When knock events are detected or operating conditions change, the system adjusts the noise levels in the mapping accordingly, creating a self-correcting system that improves accuracy over time without requiring continuous computational overhead
3Reliability
If multiple operating conditions are considered in noise mapping, then false alarms are reduced, but the mapping size and data storage requirements increase
Solution Approach 1:
The background noise mapping is segmented into distinct entries corresponding to different operating conditions such as engine temperature ranges, ethanol content levels, and fuel injection types. This segmentation allows the system to store and retrieve noise characteristics for specific conditions without processing all possible conditions simultaneously, reducing unnecessary data storage while maintaining reliability
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 system effectively diagnoses knock by accounting for varying background noise, reducing false alarms and ensuring accurate detection of engine knock, thereby optimizing engine performance and preventing damage.
Implementation Method 1
A vibration sensor measures vibration of the engine. For example only, the vibration sensor may include a piezoelectric accelerometer.
Implementation Method 2
the vibration sensor may include a piezoelectric accelerometer
Data Source
AI summary
A method includes: generating an indicator of present operating conditions of an engine; determining a first amount of noise based on vibration measured during a first plurality of combustion events of a cylinder; storing the first amount of noise and a first value of the indicator in a mapping based on a first engine speed and a first engine load; determining the first value of the indicator from the mapping based on a second engine speed and a second engine load; generating a trigger signal when the first value is different than a second value of the indicator; and, when the trigger signal is generated: determining a second amount of noise based on vibration measured during a second plurality of combustion events of the cylinder; and replacing the first amount of noise and the first value in the mapping with the second amount of noise and the second value.