Engine Spark Timing Control for Humidity and Octane Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine control methods inaccurately estimate fuel octane due to variations in engine speed-load conditions, leading to incorrect spark timing adjustments that can result in degraded fuel economy and unexpected engine knock, especially under high humidity conditions.
Innovation Solution
A method that selects initial spark timing based on engine operating parameters, learns adjustments from knock feedback, corrects timing based on operating parameters, updates fuel octane estimates, and adjusts spark timing to account for ambient humidity, thereby improving the accuracy of fuel octane estimation and reducing the speed-load effect of humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spark timing is determined as a function of engine speed-load and corrected with a factor based on the dilution effect of EGR and humidity, then the control approach accounts for inferred octane changes, but the inferred octane estimation becomes inaccurate under varying speed-load conditions
Solution Approach 1:
The patent implements dynamic adaptation by continuously learning the relationship between knock feedback and spark timing across varying engine speed-load conditions. Instead of using a static correction factor, the system adapts the spark timing adjustment based on actual knock occurrences at different operating points, making the control approach both adaptable to EGR/humidity effects and accurate under varying conditions.
Solution Approach 2:
The patent employs knock feedback as a measurement signal to learn and adjust spark timing. By using knock detection as feedback, the system directly measures the actual octane effect under current operating conditions and adjusts spark timing accordingly, resolving the inaccuracy of static inferred octane estimation methods.
2Reliability
If the inferred octane algorithm interprets the apparent octane effect of EGR/dilution as a real fuel octane addition, then spark timing adjustment is made, but this results in degraded fuel economy and unexpected knock
Solution Approach 1:
The system uses knock feedback to distinguish between apparent octane effects (from EGR/dilution) and real fuel octane characteristics. By monitoring actual knock occurrences and adapting spark timing based on this feedback, the system avoids incorrect spark timing adjustments that would degrade fuel economy or cause unexpected knock, while maintaining reliable control stability.
Solution Approach 2:
The engine control system performs self-diagnosis and self-adjustment by using its own knock feedback to learn the true octane effect. The system serves itself by automatically adapting to different fuel types and operating conditions without external intervention, correcting the misinterpretation of apparent vs. real octane effects and optimizing fuel economy while preventing knock.
3Reliability
If knock adaptation is performed without accurate humidity level knowledge, then the engine controller protects against knock, but this over-protection affects overall engine performance
Solution Approach 1:
The patent uses knock feedback as a direct measurement of actual knock conditions, eliminating the need for separate humidity level knowledge. The system learns the relationship between spark timing and knock occurrences under various humidity conditions and adjusts spark timing accordingly, providing reliable knock protection without over-protection that would degrade engine performance.
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 provides a more reliable fuel octane estimate, allowing for better setting of borderline spark settings and spark timing without significant torque loss, resulting in faster and more robust convergence of octane number estimation, independent of speed-load fluctuations.
Implementation Method 1
humidity reduces the knock tendency the engine by lowering the temperature of the end gases in the combustion chamber
Implementation Method 2
Internal combustion engines may include an exhaust gas recirculation (EGR) system to recirculate a controlled portion of exhaust as generated by the engine into an intake manifold of the engine
Data Source
AI summary
Methods and systems are provided for improving engine spark and torque control. In one example, adaptive spark control of an engine may include a modifier that adjusts the inferred fuel octane estimate and a spark adaptation based on ambient humidity. The method allows the speed-load dependent variation in octane effect of humidity to be reduced.