Misfire Detection via Rotation Time Compensation
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Solution Overview
Problem
Existing misfire detection systems for internal combustion engines, particularly for opposed cylinder misfires, face accuracy issues due to errors in angular speed measurements caused by manufacturing errors and combustion variations, leading to incorrect detection of misfires.
Innovation Solution
A misfire detection system that includes a rotation detecting unit and a signal processing unit with a non-combustion state time-required-for-rotation memory, a combustion variation memory, a filter, and a threshold determination unit to compensate for errors in rotation time measurements, allowing for accurate detection of misfires by subtracting non-combustion and combustion variations from the measured rotation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If angular speed detection is used to detect misfire, then misfire detection can be implemented, but measurement precision deteriorates due to errors from manufacturing variations and combustion variations
Solution Approach 1:
The patent introduces an intermediary compensation value that mediates between the detected rotation time and the ideal rotation time. This compensation value, derived from manufacturing data and combustion variations, acts as a mediator to correct the measurements, allowing accurate misfire detection despite inherent measurement errors in the angular speed detection system
Solution Approach 2:
The patent changes the parameter used for misfire detection from raw angular speed to compensated rotation time. By transforming the measurement parameter and applying compensation based on manufacturing variations and combustion characteristics, the system achieves higher measurement precision while maintaining reliable misfire detection capability
2Device complexity
If simple angular speed comparison is used, then device complexity is reduced, but measurement precision deteriorates due to inability to compensate for manufacturing and combustion variations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values during the engine production stage. Manufacturing data and combustion variations are captured in advance and stored as compensation values, which are then applied during operation to correct rotation time measurements, achieving high precision without complex real-time computation
Solution Approach 2:
The system uses self-service by utilizing its own operational data and pre-stored manufacturing characteristics to compensate for measurement errors. The compensation mechanism serves itself by automatically applying corrections based on stored compensation values, maintaining high measurement precision through a relatively simple structure
Data Source
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AI summary
According to the present invention, when a fuel cut command is issued, a time required for a crankshaft (11) of each cylinder to rotate through a certain angle is stored in one memory (21) per cylinder. In a stage of engine production, a combustion variation per cylinder is stored in another memory (22). When fuel is supplied, a particular component is extracted from a value obtained by subtracting the sum of the time required for the rotation in a non-combustion state and the combustion variation from the time required for the rotation corresponding to a cylinder determined to be in a combustion stroke. The occurrence of a misfire is determined when the extracted particular component exceeds a threshold.