Misfire Detection Using Crankshaft Segment Time Differences
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Solution Overview
Problem
Current methods for detecting misfires in internal combustion engines are complex and resource-intensive, requiring costly learning steps and specific components like shift registers, making them inefficient for precise monitoring of crankshaft speed and rotation disturbances.
Innovation Solution
A method that produces a measurement signal by calculating the difference between segment times of piston movement in successive cylinders, with an offset reduction using filtering, dependent on engine speed and load, to generate a misfire signal by comparing the filtered signal with a threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional correction means and learning steps are used for misfire detection, then misfire detection accuracy is improved, but device complexity and computational resources required increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for misfire detection from the crankshaft signal - specifically the period corresponding to a predetermined angle of rotation. By focusing solely on this critical parameter rather than processing the entire complex signal, the system achieves accurate misfire detection without requiring complex correction means or extensive learning steps.
Solution Approach 2:
The patent segments the crankshaft rotation into predetermined angular intervals and measures the period for each segment. This segmentation approach allows the system to detect misfires by comparing individual segment periods against threshold values, simplifying the detection process while maintaining high accuracy without needing complex computational resources.
2Measurement precision
If shift registers and specific correction means are implemented, then misfire detection precision is improved, but memory resources and computational cost increase
Solution Approach 1:
The patent extracts only the essential information needed for misfire detection from the crankshaft signal - specifically the period corresponding to a predetermined angle of rotation. By focusing solely on this critical parameter rather than processing the entire complex signal, the system achieves accurate misfire detection without requiring complex correction means or extensive learning steps.
Solution Approach 2:
The patent applies partial action by measuring only the period corresponding to a predetermined angle of rotation rather than analyzing the entire crankshaft rotation cycle. This selective measurement approach provides sufficient precision for misfire detection while significantly reducing the computational and memory resources required compared to full signal processing methods.
3Measurement precision
If complex correction means are used, then detection accuracy is improved, but ease of operation and implementation are reduced
Solution Approach 1:
The patent extracts only the essential information needed for misfire detection from the crankshaft signal - specifically the period corresponding to a predetermined angle of rotation. By focusing solely on this critical parameter rather than processing the entire complex signal, the system achieves accurate misfire detection without requiring complex correction means or extensive learning steps.
Solution Approach 2:
The patent employs a self-service approach where the system automatically compares the measured period against predetermined threshold values to detect misfires. This eliminates the need for complex manual correction procedures or extensive learning steps, making the system easy to implement and operate while maintaining high detection accuracy.
Data Source
AI summary
Method of detecting a misfire in an internal combustion engine provided with at least two cylinders and a crankshaft, includes:a. producing a measurement signal linked to the crankshaft travel time by supplying a succession of instantaneous values each corresponding to the difference between two successive segment times, each of these segment times corresponding to the time interval separating two characteristic instants of the movement of the pistons in two successive cylinders in the firing order,b. comparing the value of the measurement signal with a threshold value, andc. generating a signal representative of a misfire if the value of the measurement signal crosses the threshold value,the measurement signal having, for each cylinder, an average value that is offset relative to a reference average value,a step of reducing, for each cylinder, this offset, is performed by a high-pass filtering operation on the measurement signal.