MEMS Accelerometer Engine Crank Angle Control
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Solution Overview
Problem
Current methods for detecting misfires and partial combustion in internal combustion engines are inefficient, particularly due to the difficulty in accurately measuring in-cylinder pressure and the high cost and complexity of pressure sensors, as well as the limitations of non-intrusive diagnostic techniques like accelerometer data analysis.
Innovation Solution
A method using a microelectromechanical system (MEMS) accelerometer to generate and filter acceleration signals, determining the timing of the maximum acceleration signal, and correlating it with engine crank angle to detect in-cylinder pressure peaks, allowing for adjustments in ignition timing and engine control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct pressure measurement sensors are installed in the cylinder, then measurement precision of in-cylinder pressure is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses an intermediary approach by measuring cylinder pressure through the exhaust manifold rather than directly in the combustion chamber. The pressure sensor is installed in the exhaust manifold, which is accessible and less complex to install, while still providing sufficient pressure data to detect misfires and combustion anomalies. This mediator approach resolves the contradiction by maintaining measurement precision while reducing device complexity.
Solution Approach 2:
The patent replaces the mechanical/intrusive pressure sensor installation in the combustion chamber with a non-intrusive measurement approach using the exhaust manifold pressure as a proxy. This substitution eliminates the need for complex sensor installation in difficult-to-access locations while maintaining the ability to detect combustion quality through pressure variations.
2Device complexity
If accelerometer data analysis is used for misfire detection, then device complexity is reduced, but measurement precision of combustion quality deteriorates
Solution Approach 1:
The patent uses exhaust manifold pressure as an intermediary parameter that directly reflects combustion quality without requiring complex accelerometer analysis. By measuring pressure in the exhaust manifold, the system obtains a direct and precise indicator of combustion anomalies, misfires, and partial burning, resolving the contradiction between simplicity and precision.
3Ease of operation
If crankshaft speed fluctuation method is used, then ease of operation is improved, but measurement precision of misfire detection deteriorates under high inertia conditions
Solution Approach 1:
The patent uses exhaust manifold pressure as a direct intermediary measure of combustion quality, which is not affected by the same limitations as crankshaft speed measurement. Pressure measurement in the exhaust manifold provides consistent and accurate misfire detection regardless of engine inertia, number of cylinders, or operating conditions, resolving the precision issue while maintaining operational simplicity.
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 cost-effective and efficient means to diagnose misfires and partial combustion by correlating acceleration signals with in-cylinder pressure, enabling real-time engine control and improving combustion quality without the need for intrusive pressure sensors.
Implementation Method 1
generating, with a microelectromechanical system (MEMS) accelerometer, an acceleration signal representing vibrations of the internal combustion engine
Data Source
AI summary
A method for control of an internal combustion engine includes generating, with a microelectromechanical system (MEMS) accelerometer, an acceleration signal representing vibrations of the internal combustion engine. An engine crank angle signal is generated based on the acceleration signal. The engine crank angle signal is compared with a target value. The internal combustion engine is adjusted based upon the comparing.