Engine Knock Detection Using Variable Valve and Fuel Injection Timing
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Solution Overview
Problem
Existing engine knock control systems face challenges in accurately detecting engine knock due to sensor degradation and variations in engine background noise levels, leading to potential missed detections or false indications.
Innovation Solution
The method involves sampling a secondary knock sensor when the primary sensor generates fewer than a threshold number of indications, adjusting fuel injector and poppet valve timings to modify background noise levels, and reassessing engine knock background noise levels to improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single knock sensor is used for detection, then the system complexity is reduced, but the reliability of knock detection deteriorates due to sensor degradation
Solution Approach 1:
The knock detection function is segmented across multiple sensors. The system divides the detection task by using a first knock sensor for primary detection and a second knock sensor as backup, so that if one sensor degrades, the other can compensate. This segmentation maintains reliability without requiring a completely redundant system architecture.
Solution Approach 2:
The system prepares for sensor degradation in advance by having a second knock sensor ready as a backup. When the first sensor shows degradation signs (reduced signal quality or increased noise), the system beforehand switches to or incorporates the second sensor, cushioning against the reliability loss that would occur without such preparation.
2Measurement precision
If engine background noise levels are high, then the signal-to-noise ratio for knock detection deteriorates, but modifying engine operation to reduce noise reduces productivity
Solution Approach 1:
The system applies periodic modifications to engine operation (variable valve timing adjustments, fuel injector timing modifications) during specific cycles to reduce background noise temporarily during knock detection windows. These periodic adjustments lower noise during critical measurement periods without permanently reducing engine productivity.
Solution Approach 2:
The system dynamically adjusts engine parameters (valve timing, injection timing) in real-time based on detected noise levels. When high background noise is detected, the system dynamically modifies operation to reduce noise, then restores normal operation when noise levels are acceptable, maintaining productivity while improving detection precision when needed.
3Measurement precision
If fuel injector and poppet valve timings are adjusted to modify background noise, then the signal-to-noise ratio improves, but the device complexity increases
Solution Approach 1:
The existing fuel injector and poppet valve timing control systems are made multi-functional. These components continue their primary function of engine operation control while also serving as noise reduction tools for knock detection. By making the control system universal, no additional dedicated noise reduction devices are needed, avoiding increased complexity.
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 enhances engine knock detection accuracy and signal-to-noise ratios, reducing the likelihood of missed or false knock indications, especially in conditions where the primary sensor is degraded.
Implementation Method 1
The knock control system may include a knock sensor that senses vibrations of the engine's block
Data Source
AI summary
Methods and systems are disclosed for operating an engine that includes a knock control system. The method and system may increase opportunities to learn one or more engine knock background noise levels via changing poppet valve timing and/or fuel injection timing. The method and system may also improve knock detection if knock sensor degradation is suspected.