Engine Combustion Control Using Crankshaft Angular Acceleration
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Solution Overview
Problem
Current engine management systems fail to effectively detect and control irregular vibration caused by incomplete combustion in vehicles, as the existing ER index is not highly correlated with actual vibration, leading to inadequate combustion control.
Innovation Solution
A method is introduced that uses a combustion characteristic index (CCI) calculated from crank position sensor signals to identify unstable combustion cylinders, adjusting ignition timing and fuel amounts based on this index to reduce irregular vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ER index is used to judge irregular vibration, then the engine management system can detect combustion issues, but the detection accuracy is insufficient because the ER index is not highly correlated with actual irregular vibration
Solution Approach 1:
The patent changes the detection parameter from the conventional ER index to a new combustion characteristic index (CCI) that is highly correlated with irregular vibration. The CCI is calculated using the formula CCI = (α × |dω/dθ| + β × |d²ω/dθ²|) / ω, where ω is angular velocity, dω/dθ is angular acceleration, and d²ω/dθ² is angular jerk. This parameter transformation enables accurate detection of irregular vibration by directly measuring crankshaft rotational characteristics during combustion events.
Solution Approach 2:
The patent replaces the conventional vibration-based detection method with a rotational mechanics-based method. Instead of measuring physical vibrations from the engine block, the system measures angular velocity and angular acceleration of the crankshaft using a crank position sensor. This substitution provides more direct and accurate information about combustion instability while eliminating the need for complex vibration analysis systems.
2Measurement precision
If no specific detection technology is implemented, then the system structure remains simple, but irregular vibration cannot be effectively detected and controlled
Solution Approach 1:
The patent introduces the combustion characteristic index (CCI) as an intermediary parameter that bridges the gap between simple crank position sensing and complex vibration analysis. The CCI serves as a computational mediator that transforms basic angular velocity and acceleration data into a meaningful metric for irregular vibration detection, enabling accurate control without requiring complex additional hardware.
Solution Approach 2:
The system uses the existing crank position sensor to generate all necessary data for irregular vibration detection. The same sensor that provides basic engine timing information is also used to calculate angular velocity, angular acceleration, and ultimately the CCI. This self-service approach eliminates the need for separate vibration sensors or additional measurement devices.
3Object-affected harmful factors
If combustion factors are not adjusted for unstable cylinders, then the engine operates smoothly, but irregular vibration persists and reduces driving comfort and safety
Solution Approach 1:
The patent applies local quality control by identifying and treating only the specific cylinder(s) exhibiting unstable combustion. The CCI is calculated for each cylinder individually, allowing the system to pinpoint problematic cylinders and adjust combustion factors (ignition timing, fuel injection amount) only for those specific cylinders rather than the entire engine. This targeted approach reduces irregular vibration while maintaining optimal performance of stable cylinders.
Solution Approach 2:
The system implements continuous feedback control by monitoring the CCI of each cylinder and dynamically adjusting combustion factors based on real-time combustion characteristics. When unstable combustion is detected in a specific cylinder, the controller modifies ignition timing and/or fuel injection for that cylinder, then continues monitoring to ensure the correction is effective. This closed-loop feedback ensures rapid response to combustion instability while maintaining overall engine smoothness.
Data Source
AI summary
A method for controlling engine combustion may include receiving a signal of a crank position sensor, determining an angular velocity and an angular acceleration of a crank on the basis of the signal of the crank position sensor, determining a combustion characteristic index for each cylinder using the angular velocity and the angular acceleration of the crank, judging an unstable combustion cylinder using the combustion characteristic index for each cylinder, and changing a combustion factor for controlling the unstable combustion cylinder.