Inductive Bending Moment Sensor for Rotor Shafts
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Solution Overview
Problem
Existing measurement systems for determining bending moments on hollow cylindrical bodies, such as rotor shafts, are prone to faults due to harsh environmental conditions like temperature, vibrations, and electromagnetic interference, and are costly and difficult to maintain, requiring complex installation and disassembly processes.
Innovation Solution
A contactless measurement apparatus using inductive sensors mounted inside the hollow cylindrical body without contact, with a processing system that calculates bending moments based on displacements measured between sensors and the inner surface, allowing for non-contact, directional measurement and reduced sensitivity to electromagnetic interference, and enabling easy maintenance and retrofitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strain gauges are bonded, soldered, and/or cemented inside the rotor shaft, then bending moment measurement is achieved, but maintenance and repair require complete disassembly of the rotor system which is costly and time-consuming
Solution Approach 1:
The measurement system is divided into separate components: the sensor assembly can be independently installed and removed from the rotor shaft without disassembling the entire rotor system. This segmentation allows the sensor to be maintained or replaced separately, reducing maintenance complexity while maintaining measurement reliability
Solution Approach 2:
The sensor assembly is extracted from the interior of the rotor shaft and mounted on the exterior surface. This extraction eliminates the need for complex internal installation and removal processes, allowing the sensor to be easily accessed for maintenance while continuing to measure bending moments accurately
2Ease of operation
If measurement equipment is mounted outside the hollow cylindrical body, then access and maintenance are easier, but the rotating parts make it difficult to externally mount measurement equipment near the hollow cylindrical body
Solution Approach 1:
A non-rotating support structure or stator assembly serves as an intermediary between the external measurement environment and the rotating rotor shaft. This intermediary provides a stable mounting platform for sensors that can measure rotor dynamics without requiring the sensors themselves to rotate or be mounted directly on rotating parts
Solution Approach 2:
The measurement system uses external sensors that detect and copy the mechanical deformations of the rotor shaft through non-contact or minimally contact methods. This allows the measurement function to be replicated externally without requiring physical attachment to rotating components, simplifying mounting while maintaining measurement capability
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 solution provides a reliable, cost-effective, and low-maintenance method for determining bending moments, reducing the need for complex installations and minimizing the impact of harsh environmental conditions, while offering real-time monitoring and alert systems for exceeding threshold values.
Implementation Method 1
a sensor arrangement that is mounted to the sensor support structure and comprises at least first and second sensors that measure first and second distances in first and second directions between the first and second sensors and the inner surface
Data Source
AI summary
A measurement apparatus for determining a bending moment acting on a hollow cylindrical body in a current state as well as to a method of operating such a measurement apparatus. The measurement apparatus may include a sensor support structure, a sensor arrangement with sensors, and a processing system. The processing system may determine displacements of the inner surface of the hollow cylindrical body relative to the sensors based on the distances measured in the current state compared to the distances measured during an initial undeformed state, and determine the bending moment acting on the hollow cylindrical body based on the displacements.