Rotation Detection Threshold Adjustment for Engine Crankshaft
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Solution Overview
Problem
Existing rotation detecting devices face accuracy issues in determining normal versus reverse rotation of a rotating shaft due to variations in detector pulse widths and deterioration, leading to unreliable stop position detection and restart performance in internal combustion engines.
Innovation Solution
A rotation detecting device and method that includes a first determination unit for normal/reverse rotation based on rotation signals, a second unit for checking directional conditions, and a setting unit to adjust the threshold value based on the rotation signal when a directional condition is met, ensuring stable accuracy by adapting to variations in pulse widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold value is used for determining normal/reverse rotation, then the determination process is simple, but the accuracy deteriorates due to pulse width variations from detector variation or deterioration
Solution Approach 1:
The threshold value is changed from a fixed parameter to a dynamic parameter that automatically adjusts based on detected pulse width characteristics. The setting unit stores multiple threshold values and selects/apples the appropriate threshold based on the current operational state, making the system adaptive to detector variations and deterioration over time.
Solution Approach 2:
The system continuously monitors the pulse width of rotation signals and uses this feedback to adjust the threshold value. When pulse width variations are detected (indicating detector variation or deterioration), the setting unit modifies the threshold accordingly, creating a closed-loop system that maintains determination accuracy despite component degradation.
2Reliability
If the threshold value is adjusted to compensate for pulse width variations, then determination accuracy is maintained, but the device complexity increases due to additional setting and monitoring units
Solution Approach 1:
The determination device performs multiple functions: it detects rotation direction, measures pulse width characteristics, determines when directional conditions are satisfied, and adjusts thresholds accordingly. By integrating these functions into a single multi-functional unit, the patent avoids the need for separate independent systems for each function, thereby reducing overall device complexity while maintaining reliability.
Solution Approach 2:
The determination device automatically monitors its own operational state and self-adjusts the threshold value based on detected pulse width variations. The setting unit autonomously selects appropriate thresholds without requiring external calibration or manual intervention, enabling the system to maintain accuracy through self-correction of threshold parameters.
Data Source
AI summary
A rotation detecting device and a rotation detecting method determines normal rotation/reverse rotation of a rotating shaft based on a rotation signal different between the normal rotation and the reverse rotation of the rotating shaft. The rotation signal is set to have a pulse width different between the normal rotation and the reverse rotation of a crankshaft that is an output shaft of an internal combustion engine. By determining whether or not the pulse width is greater than a threshold value, the normal rotation or the reverse rotation of the crankshaft is detected. Whether or not the crankshaft is rotating normally is determined based on engine rotating speed, a cylinder in which a piston is in a predetermined position, an engine load, a starter switch, intake pressure, battery voltage, and the like. When the condition for the normal rotation is satisfied, the threshold of the pulse width is set based on a pulse width of a rotation signal measured at this time.