Drive Shaft Monitoring with Dual Coded Discs
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Solution Overview
Problem
Existing drive shaft monitoring systems face challenges such as poor accuracy due to sensor movement, limited resolution for torsional analysis, critical installation requirements, and the need for specialized personnel for maintenance and repair, especially in maritime vessels, where they cannot be easily dismounted or remounted, and fail to provide accurate crankshaft monitoring and clutch slip detection.
Innovation Solution
A drive shaft monitoring system with two coded discs and multiple independent light sensor assemblies, allowing for precise measurement of torsional angle, torque, and shaft power, along with detection of shaft vibrations, torsion oscillations, axial displacement, and clutch slip, using a high-resolution incremental encoder for calibration and a processing unit to calculate these parameters, enabling accurate monitoring and reduced maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light sensor is used per code wheel, then the device complexity is reduced, but the measurement precision deteriorates when sensor foundations move relative to the shaft
Solution Approach 1:
The patent divides the measurement system into multiple independent light sensor assemblies (at least two per code wheel) positioned at different circumferential locations. Each sensor assembly independently measures the position of teeth on the code wheel, and the processing unit combines these measurements to calculate torque. This segmentation provides redundancy and compensates for sensor foundation movements, maintaining measurement precision while using simple individual sensor components.
2Device complexity
If large openings are used in code wheels, then the device complexity is reduced, but the measurement precision and resolution deteriorate
Solution Approach 1:
The patent implements different tooth configurations on different code wheels. The first code wheel has teeth with larger openings suitable for general position detection, while the second code wheel has teeth with smaller openings providing higher resolution for torsional analysis. Each code wheel is optimized for its specific measurement function, allowing the system to achieve both ease of construction and high measurement precision simultaneously.
3Measurement precision
If the relative position of code wheels is strictly controlled with no overlap, then the measurement accuracy is improved, but the ease of operation deteriorates due to critical installation requirements
Solution Approach 1:
The patent allows the code wheels to be positioned with partial overlap rather than requiring strict no-overlap positioning. The processing unit is designed to handle various relative positions of the code wheels and calculate torque based on the time displacement between tooth passages detected by the sensor assemblies. This approach provides a larger acceptance window for installation while maintaining measurement accuracy through computational correction.
4Measurement precision
If the distance between code wheels is restricted by opening size, then the measurement precision is improved, but the adaptability deteriorates for different shaft configurations
Solution Approach 1:
The patent makes the system adaptable to different code wheel distances by using dynamic calculation methods in the processing unit. The system measures the actual time displacement between tooth passages on different code wheels and calculates torsional angle based on the measured time difference and the known or measured distance between code wheels. This allows the system to maintain measurement precision while accommodating various shaft configurations and code wheel spacing.
5Measurement precision
If optical fibres and light beams are used, then the measurement precision is improved, but the ease of repair deteriorates due to specialized equipment and competence requirements
Solution Approach 1:
The patent replaces complex optical fibre transmission systems with direct light emission and detection using light sensor assemblies that can detect light passing through code wheel teeth. This substitution maintains measurement precision while significantly improving ease of repair, as the simplified optical system requires no specialized fibre optic equipment or expertise for installation and maintenance, making it suitable for routine servicing by standard maintenance personnel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides increased accuracy and reliability in measuring drive shaft parameters, including torsional angle, torque, and vibrations, while being easier to install and maintain, and capable of operating in various environments, including high RPM and large diameter shafts, with reduced dependency on specialized personnel.
Implementation Method 1
a light source emitting a light beam in a perpendicular plane to the multiple slots or recesses at one side of the respective coded disc and an electro-optical sensor for receiving modulated light through the multiple slots or recesses arranged at other side of the respective coded disc
Data Source
AI summary
Drive shaft monitoring system has a first and second coded disc. The first and second coded disc are provided with multiple slots or recesses evenly distributed in circumferential direction thereof. The drive shaft monitoring system includes at least two independent light sensor assemblies arranged in connection with the slots or recesses of the first and second coded disc.