Flexible Coupling Load Measurement Using Eddy Current Sensing
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Solution Overview
Problem
Current methods for coupling load measurements in the turbine field fail to accurately measure axial loads on driven shafts without interfering with the apparatus, are sensitive to thermal expansion, and require significant modifications to existing installations, leading to wear and damage on thrust bearings.
Innovation Solution
A contactless coupling load measurement device using flexible coupling elements as part of the measurement system, employing eddy current sensors to measure distance variations between flanges, and applying Hooke's Law to calculate axial loads, with cooling and temperature compensation to minimize errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional contact-based load measurement devices are installed on coupled shafts, then load measurement capability is achieved, but the apparatus becomes complex and requires significant modifications to existing installations
Solution Approach 1:
The patent introduces an intermediary measurement system using eddy current sensors that measure the axial position of the flexible coupling element without direct contact. This intermediary approach allows load measurement through distance measurement between flanges, avoiding complex contact-based load cells while maintaining measurement capability.
Solution Approach 2:
The patent replaces traditional mechanical contact-based load measurement devices with a non-contact electromagnetic measurement system. Eddy current sensors use electromagnetic fields to measure axial position, substituting mechanical contact with field-based measurement, thereby reducing device complexity and modification requirements.
2Measurement precision
If measurement devices are installed on rotating shafts in high temperature environments, then load measurement is achieved, but thermal expansion causes measurement errors
Solution Approach 1:
The patent addresses thermal expansion by measuring distance variations relative to a reference position rather than absolute distance. By detecting changes in axial position from a known reference state, the system compensates for thermal expansion effects, maintaining measurement accuracy in high temperature environments.
3Reliability
If flexible coupling elements are used to compensate for misalignment and axial displacement, then shaft protection is improved, but accurate load measurement becomes difficult without interfering with the coupling
Solution Approach 1:
The patent uses the flexible coupling element itself as part of the measurement system by measuring its axial position relative to flanges. This intermediary approach allows load measurement through the coupling's natural movement without interfering with its protective function, as the coupling continues to compensate for misalignment while providing measurement data.
Solution Approach 2:
The flexible coupling element serves dual purposes: protecting shafts from excessive forces and providing measurement information for load determination. By measuring the axial position of the coupling element, the system utilizes the coupling's own movement characteristics to derive load information without additional protective measures.
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
Enables accurate, non-invasive axial load measurement on coupled shafts, reducing wear and damage on thrust bearings, while being resistant to thermal expansion and requiring minimal modifications to existing setups.
Implementation Method 1
employing eddy current sensors to measure distance variations between flanges
Implementation Method 2
Applying Hooke's Law to the measured distance in order to calculate an axial load on the shafts
Data Source
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AI summary
The coupling load measurement method allows to measure load between a first driving shaft (1) and a second driven shaft (2) connected by means of a hub (3) coupled both with the first shaft (1) and with the second shaft (2) by means of at least one flexible coupling element (5,6) coupled to said hub (3) and to said first shaft (1) and/or to said second shaft (2); the method comprises, during operation of the shafts (1,2), a measurement step of measuring a distance variation respect to a reference distance between a first flange of the hub (31) and a second flange (61) of the flexible coupling element (5,6) and the step of using said measured distance variation for calculating said load.