Eddy Current Sensor Mounting for Gas Turbine Shaft Displacement
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Solution Overview
Problem
Existing methods for measuring axial displacement of rotating shafts in gas turbine engines are inadequate, particularly due to environmental factors like oil mist and tight clearances, which limit the effectiveness of optical techniques and other measurement methods.
Innovation Solution
An apparatus comprising a target member with a target surface normal to the shaft's axis, coupled with an eddy current proximity sensor and a mounting assembly that adjusts the sensor's position to optimize detection, allowing for accurate measurement of axial displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical measurement techniques are used to measure axial shaft displacement, then measurement capability is provided, but the measurement precision deteriorates due to oil mist interference and tight clearance constraints
Solution Approach 1:
The patent replaces optical measurement techniques with electromagnetic field-based eddy current sensing. The eddy current sensor uses electromagnetic induction to detect axial shaft displacement, eliminating the need for optical paths that are susceptible to oil mist interference and tight clearance limitations. This substitution of measurement physics enables reliable operation in the harsh gas turbine environment.
Solution Approach 2:
The patent changes the measurement parameter from optical properties (light reflection, transmission) to electrical properties (eddy current response). By measuring the electrical impedance changes in the eddy current sensor caused by variations in axial displacement, the system achieves measurement capability that is insensitive to oil mist and operates effectively within tight clearances.
2Measurement precision
If a fixed sensor mounting is used, then device complexity is reduced, but measurement precision deteriorates due to inability to optimize sensor positioning
Solution Approach 1:
The patent implements an adjustable sensor mounting structure that allows dynamic positioning of the eddy current sensor relative to the target surface. This adjustability enables optimization of the sensor gap for maximum measurement precision while maintaining a relatively simple overall structure. The mounting can be adjusted during installation or maintenance to achieve the optimal sensing distance.
Solution Approach 2:
The sensor mounting structure is designed to allow preliminary adjustment and calibration before final operation. This enables the sensor position to be optimized in advance during installation or maintenance activities, ensuring maximum measurement precision without requiring complex real-time adjustment mechanisms during engine operation.
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 precise detection of axial shaft displacement, even in challenging environments, providing early warning of potential engine failures and wear, while minimizing noise and ensuring accurate calibration.
Implementation Method 1
systems and methods for measuring axial displacement of a rotating shaft using an eddy current sensor
Data Source
AI summary
In some embodiments, an apparatus includes a target member, a sensor and a mounting assembly. The target member is coupled to a shaft that is disposed within an engine housing and that rotates about an axis. The target member includes a target surface that is substantially normal to the axis of rotation of the shaft. The sensor is configured to produce a signal associated with a distance between a sensor tip and the target surface. The mounting assembly is coupled to the sensor and the engine housing, and is configured to adjust the distance between the sensor and the target surface.