Engine Misfire Detection Using Reference Angle Cycle Segmentation
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Solution Overview
Problem
Existing control devices for internal combustion engines face challenges in accurately determining misfire due to rotational fluctuations caused by factors other than misfire, such as vehicle acceleration and intake air amount, which can lead to inaccurate detection results.
Innovation Solution
A control device that calculates the angle detection cycle using an angle sensor and includes an arithmetic processing device, storage device, and input circuit, where the storage device stores the angle detection cycle within a reference angle interval as a reference detection cycle, and compares it with a threshold value cycle to determine misfire presence or absence, thereby isolating the influence of rotational fluctuations due to misfire.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the angle detection cycle in the combustion stroke is used for misfire detection, then misfire can be detected, but rotational fluctuations caused by factors other than misfire (vehicle acceleration, intake air amount) reduce detection accuracy
Solution Approach 1:
The patent divides the angle detection cycle measurement into two separate segments: (1) reference angle interval including top dead center of compression stroke, and (2) combustion stroke interval after top dead center. By segmenting the measurement periods, the patent isolates the rotational fluctuation component present in both intervals from the combustion-specific fluctuation, enabling accurate misfire detection through comparison of the two segments.
Solution Approach 2:
The patent introduces the reference angle interval measurement as an intermediary component that captures the baseline rotational fluctuation caused by vehicle acceleration and intake air amount. This intermediary measurement serves as a reference against which the combustion stroke measurement is compared, allowing the system to identify deviations specifically caused by misfire rather than general rotational fluctuations.
2Measurement precision
If the integrated value of rotational speed deviation is used for misfire determination, then misfire can be detected, but the accuracy decreases when angle detection cycle fluctuates due to factors other than misfire
Solution Approach 1:
The patent implements a feedback mechanism where the reference angle interval measurement (taken before combustion) provides baseline information about rotational fluctuation. This baseline feedback is then used to interpret the combustion stroke measurement, allowing the system to distinguish between fluctuations caused by vehicle dynamics (captured in reference) and fluctuations caused by misfire (deviation from reference).
Data Source
AI summary
The control device for an internal combustion engine disclosed in the present application is a control device that determines the presence or absence of misfire based on an angle detection cycle calculated from an output signal of an angle sensor, the control device includes an arithmetic processing device and a storage device, the control device is configured so that the storage device stores the angle detection cycle calculated in a misfire detection threshold value comparison section after the reference angle section as a threshold value comparison target cycle and is configured such that the arithmetic processing device determines the presence or absence of misfire based on the misfire detection threshold value cycle calculated based on the reference detection cycle and the threshold value comparison target cycle, thereby it becomes possible to accurately determine the presence or absence of misfire in the control device for the internal combustion engine.