Unequal Interval Engine Misfire Detection via Fluctuation Separation
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Solution Overview
Problem
Existing unequal interval combustion engine misfire determination devices face challenges in accurately detecting continuous misfires due to fluctuations in rotation speed caused by both combustion and non-combustion factors, making it difficult to distinguish between the two and achieve high-accuracy misfire detection.
Innovation Solution
The device acquires a rotation speed value in a section of 720xm crank angle degrees, where the fluctuation component attributable to unequal interval combustion is canceled, and removes this value from the rotation speed at the determination angle position to calculate a fluctuation manifested value, allowing for more accurate detection of misfires by isolating the combustion-related fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotation speed fluctuation is used directly for misfire determination, then the determination process is simple, but the determination accuracy is low due to mixed fluctuations from combustion and non-combustion factors
Solution Approach 1:
The patent segments the rotation speed fluctuation into two distinct components: combustion-related fluctuation and non-combustion-related fluctuation. By separating these components through mathematical processing (subtracting the average fluctuation from the instantaneous fluctuation), the system can isolate the combustion signal for accurate misfire determination while filtering out noise from other sources.
Solution Approach 2:
The patent extracts the combustion-related fluctuation component from the total rotation speed fluctuation by removing the non-combustion-related average fluctuation. This extraction process isolates the specific signal needed for misfire detection, enabling accurate determination without being interfered with by other fluctuation sources.
2Speed
If the average value of rotation speed in a section shorter than one cycle is used for misfire determination, then the response speed is fast, but the determination accuracy deteriorates due to insufficient cancellation of unequal interval combustion fluctuation
Solution Approach 1:
The patent changes the parameter of the analysis section length from a fixed short duration to a dynamically determined duration. By setting the section length to be equal to or longer than the period of unequal interval combustion fluctuation, the system ensures complete cancellation of combustion-related fluctuations when calculating the average, thereby improving accuracy while maintaining fast response through efficient processing of the optimized section.
Data Source
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AI summary
[Problem] To provide an unequal interval combustion engine misfire determination device and a vehicle that are applicable to various forms of misfires in an unequal interval combustion engine. [Solution] An unequal interval combustion engine misfire determination device determines a misfire in an unequal interval combustion engine including a plurality of cylinders in which combustion occurs at unequal intervals and a crankshaft, based on a crank angle signal indicating a rotation angle of the crankshaft. The misfire determination device includes: an unequal interval combustion fluctuation canceled value acquisition unit that acquires, based on the crank angle signal, an unequal interval combustion fluctuation canceled value which is a rotation speed in a section of 720xm crank angle degrees including a predetermined determination angle position, where m is a natural number; an unequal interval combustion fluctuation manifested value calculation unit that calculates an unequal interval combustion fluctuation manifested value in which a fluctuation component attributable to unequal interval combustion is manifested, by removing the unequal interval combustion fluctuation canceled value; and a specific cylinder misfire determination unit that determines a misfire in a specific cylinder based on the unequal interval combustion fluctuation manifested value.