Crankshaft Rotation Direction Detection via Pulse Width Differential
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Solution Overview
Problem
Existing methods for determining the rotating direction of an internal combustion engine's output shaft are prone to reduced detection accuracy due to environmental changes, such as temperature variations, affecting the characteristics of rotating sensors.
Innovation Solution
The method involves detecting the rotating direction of the output shaft based on changes in the waveform of a pulse signal output by a rotating sensor, specifically measuring and analyzing the pulse width or amplitude to differentiate between forward and reverse rotations, using a control system that calculates the rotating direction based on threshold values and operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotating sensor outputs a pulse signal with different pulse width or amplitude for forward or reverse rotation and detection is based on comparison with a threshold value, then the rotating direction can be detected, but detection accuracy is reduced when environmental conditions such as temperature change causing characteristic changes in the rotating sensor
Solution Approach 1:
The patent changes the detection parameter from absolute pulse width or amplitude to the change amount (difference) of pulse width or amplitude. By detecting the change amount between consecutive pulse signals rather than comparing absolute values with a threshold, the system becomes insensitive to environmental drift while maintaining the ability to detect rotation direction changes.
Solution Approach 2:
The patent uses feedback by comparing the current pulse signal characteristics with the previous pulse signal characteristics. The detection is based on the change amount between consecutive measurements, creating a differential feedback mechanism that automatically compensates for environmental drift without requiring external calibration.
2Ease of operation
If threshold-based detection is used for determining rotating direction, then the detection method is simple, but detection accuracy deteriorates under temperature variations
Solution Approach 1:
The patent transforms the detection parameter from absolute values to change amounts. Instead of comparing pulse width or amplitude against a fixed threshold, the system compares the difference between consecutive pulse signals, maintaining computational simplicity while achieving environmental robustness.
Solution Approach 2:
The patent introduces dynamic detection by continuously comparing current pulse characteristics with previous ones. This dynamic approach allows the system to adapt to changing environmental conditions in real-time without requiring recalibration or complex adaptive algorithms.
Data Source
AI summary
An apparatus and a method for controlling an internal combustion engine, detects a rotating direction of an output shaft of the internal combustion engine. The internal combustion engine includes a crank angle sensor for outputting a pulse signal in accordance with rotation of a crankshaft. The crank angle sensor outputs at the time of reverse rotation of the crankshaft a pulse signal POS having a wider pulse width than that at the time of forward rotation. A control unit receiving pulse signal POS calculates a difference between a present value and a previous value of a pulse width of pulse signal POS and detects switching of a rotating direction of the crankshaft based on a magnitude of this difference. Thus, it is possible to suppress lowering of detection accuracy of a rotating direction of the crankshaft under the influence of variation of measurement values of the pulse width.