Rotation Speed Calculation Apparatus with Adaptive Angle Thresholds
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Solution Overview
Problem
Existing rotation speed calculation apparatuses face challenges in maintaining stable determination of engine speed and detection of invalid signals due to changes in transmission intervals, which affects calculation accuracy.
Innovation Solution
A rotation speed calculation apparatus that includes a detector and a CPU with memory, which calculates engine speed based on different predetermined angles in low- and high-rotation ranges, adjusting sampling times and calculation intervals to enhance accuracy and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the transmission interval is changed in accordance with a change in the pulse signal occurrence interval, then the loss or duplication of transmission data is reduced, but the stability of determination on detection of invalid signal or soundness of connected apparatus deteriorates
Solution Approach 1:
The invention segments the engine rotation range into multiple ranges (first rotation range, second rotation range, third rotation range) with different threshold values. This segmentation allows the system to apply different determination criteria for different rotation conditions, maintaining stable invalid signal detection across varying engine speeds while avoiding the need to change transmission intervals.
2Productivity
If the transmission interval is changed in accordance with a change in the pulse signal occurrence interval, then data transmission efficiency is improved, but the calculation accuracy of engine speed deteriorates
Solution Approach 1:
The invention dynamically adjusts the threshold value based on the current rotation range of the engine. The determination part selects different threshold values (first, second, or third threshold) according to which rotation range the engine is currently in, allowing accurate engine speed determination across the entire operating range while maintaining a fixed transmission interval.
3Device complexity
If a fixed threshold value is used for engine speed determination, then the device complexity is reduced, but the accuracy of engine speed calculation across different rotation ranges deteriorates
Solution Approach 1:
The invention changes the threshold parameter based on the engine's rotation range. By establishing multiple threshold values corresponding to different rotation ranges (low, medium, high speed ranges), the system achieves high measurement precision across all operating conditions. The determination part automatically selects the appropriate threshold based on current engine speed, maintaining calculation accuracy without requiring complex additional hardware.
Data Source
AI summary
A rotation-speed-calculation-apparatus includes: a detector configured to detect a rotation-angle of an engine; and a CPU and a memory coupled to the CPU. The CPU is configured to perform: calculating an engine-speed each time the detector detects a predetermined-angle based on a time-period required for the engine to rotate the predetermined-angle; and determining whether the engine-speed calculated is in a low-rotation range equal to or lower than a threshold-value or in a high-rotation range over the threshold-value. The CPU is configured to perform: the calculating including: calculating the engine-speed based on a time-period required for the engine to rotate a first-predetermined-angle when it is determined that the engine-speed is in the low-rotation range; and calculating the engine-speed based on a time-period required for the engine to rotate a second-predetermined-angle smaller than the first-predetermined-angle when it is determined that the engine-speed is in the high-rotation range.