Dual Magnetic Sensor Drum for Speed and Position Sensing
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Solution Overview
Problem
Existing sensor systems for detecting rotational speed of gas turbine components, such as turbines and shafts, face challenges in high-speed and thermally dynamic environments, leading to compromised speed information due to increased voltages and potential misalignment issues.
Innovation Solution
A sensor system comprising a cylindrical drum with axially extending members that deflect radially outward with rotational speed, utilizing two magnetic sensors positioned radially inward and outward to generate electrical outputs for determining rotational speed and axial position, with a controller processing these outputs to regulate voltage and detect anomalies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic sensor is used to detect rotational speed, then the device complexity is reduced, but the measurement precision deteriorates due to inability to distinguish voltage variations from speed changes
Solution Approach 1:
The system divides the detection function into two separate magnetic sensors: one positioned radially inward and one positioned radially outward. Each sensor independently detects the rotational speed, providing two separate voltage signals that can be compared and processed to distinguish true speed changes from voltage fluctuations, thereby improving measurement precision without significantly increasing system complexity
Solution Approach 2:
The patent introduces a comparison mechanism that uses the voltage output from one magnetic sensor as a reference to evaluate the voltage output from the other sensor. This intermediary comparison process allows the system to identify and compensate for voltage variations, enabling more accurate rotational speed measurement
2Measurement precision
If magnetic sensors are positioned close to the drum for accurate detection, then the measurement precision improves, but the reliability deteriorates due to increased vulnerability to thermal expansion and misalignment
Solution Approach 1:
By positioning magnetic sensors on opposite sides of the drum (radially inward and radially outward), the system creates two independent detection paths. This segmentation allows the sensors to remain at optimal detection distances while being less susceptible to cumulative alignment errors and thermal expansion effects that would affect a single sensor position
Solution Approach 2:
The system continuously compares the voltage outputs from both magnetic sensors and uses this feedback to identify and compensate for drift caused by thermal expansion or misalignment. The comparison mechanism provides real-time feedback that enables the system to maintain measurement accuracy despite environmental changes
3Productivity
If high rotational speed is detected, then the productivity increases, but the reliability deteriorates due to voltage increases causing compromised speed information
Solution Approach 1:
The system deliberately positions one magnetic sensor radially inward and another radially outward, creating an excessive detection setup where one sensor's voltage output serves as a reference to evaluate the other. This partial redundancy allows the system to tolerate and compensate for voltage increases at high speeds, maintaining reliable speed information even when operating at high productivity levels
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 effectively determines rotational speed and axial position with improved accuracy, self-regulating voltage outputs at high speeds and detecting axial displacement, preventing over-speed conditions and ensuring reliable operation by generating alert signals for potential hazards.
Implementation Method 1
The first magnetic sensor may be configured to generate a first electrical output that indicates passage of each of the plurality of axially extending members about the first magnetic sensor when the cylindrical drum rotates about the rotation axis
Implementation Method 2
The plurality of axially extending members may be adapted to deflect radially outward away from the rotation axis based on a rotational speed of the cylindrical drum
Data Source
AI summary
A sensor system includes a drum, a first sensor, and a second sensor. The drum is mounted for rotation about a rotation axis and includes a band and a plurality of members that extend axially away from the band. The first sensor and the second sensor are configured to generate electrical output in response to detecting one or more of the plurality of members.