Engine Misfire Detection via Lateral Vibration Spectral Analysis
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Solution Overview
Problem
Existing methods for detecting misfires in internal combustion engines are either expensive, complex, and prone to inaccuracies due to environmental factors or require long processing times, making real-time analysis challenging.
Innovation Solution
A method using an acceleration sensor to sense lateral displacement of the engine, performing spectral analysis to extract frequencies associated with engine orders, and determining misfires based on the magnitude of specific frequencies, which are compared to historical values or normal operating conditions to identify faulty cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensors (exhaust gas sensors, pressure sensors, ion-current sensors) are used to detect misfire in each cylinder, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple detection approaches (crankshaft acceleration data and accelerometer data) into a unified misfire detection system. Instead of using separate complex sensor systems for each cylinder, the method merges vibration signal processing with crankshaft rotational analysis to achieve reliable misfire detection through a single integrated approach.
Solution Approach 2:
The patent uses vibration signals and acceleration data as intermediary measurements to indirectly detect misfire conditions. Rather than directly measuring combustion parameters in each cylinder, the system uses accelerometer signals and crankshaft acceleration as mediators that reflect combustion abnormalities without requiring direct exposure to harsh in-cylinder environments.
2Device complexity
If mathematical modeling methods are used to detect misfire, then device complexity is reduced, but measurement precision and real-time capability deteriorate
Solution Approach 1:
The patent employs dynamic threshold adjustment based on engine operating conditions. The misfire detection thresholds are not fixed but adapt dynamically to varying engine loads, speeds, and temperatures. This allows the simplified accelerometer-based system to maintain high precision across different operating regimes by adjusting detection criteria in real-time.
Solution Approach 2:
The system changes detection parameters (thresholds, frequency ranges, time windows) based on engine operating conditions. By adjusting these parameters dynamically, the method maintains measurement precision across varying engine states without requiring complex modeling, achieving both simplicity and accuracy.
3Ease of operation
If fixed thresholds are used for misfire detection, then ease of operation is improved, but reliability deteriorates under varying operating conditions
Solution Approach 1:
The patent implements dynamic threshold adjustment that adapts to changing engine operating conditions such as load, speed, and temperature. This dynamic approach maintains reliability across varying conditions while preserving ease of operation, as the system automatically adjusts without requiring manual intervention or complex user input.
Solution Approach 2:
The system uses feedback from accelerometer signals and crankshaft acceleration data to continuously adjust detection thresholds. By incorporating feedback loops that monitor engine behavior and adapt detection criteria accordingly, the method maintains high reliability under varying operating conditions while keeping the operation simple and automated.
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 reliable, cost-effective, and real-time method for detecting misfires by analyzing temporal signatures of engine displacement, improving the accuracy and efficiency of identifying faulty cylinders and assessing engine health.
Implementation Method 1
sensing a temporal signature of a lateral displacement of the engine via an acceleration sensor. The acceleration sensor senses the lateral displacement in at least one direction
Implementation Method 2
processing the signal with the control unit. The processing comprises performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency
Data Source
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AI summary
A method of detecting misfire in an internal combustion engine comprises: sensing a temporal signature of a lateral displacement of the engine, performing a spectral analysis of the temporal signature of the lateral displacement to extract a magnitude of a predetermined frequency, and determining that misfiring in at least one of the plurality of cylinders has occurred based on the magnitude of the predetermined frequency. The predetermined frequency is associated with one of a plurality of orders of the engine. The one of the plurality of orders is representative of engine displacement due to in-cylinder pressures. Other methods of detecting misfire and a vehicle are also presented.