Variable Reluctance Resolver-Encoder for High-Radiation Environments
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Solution Overview
Problem
Conventional resolvers and encoders are not well-suited for high-radiation environments, such as neutron choppers, due to damage from radiation and high rotational speeds, which affect their precision and longevity.
Innovation Solution
A variable reluctance angular position detector with a cylindrical rotor and multiple ferromagnetic rings and sensors, configured to produce consistent output signals despite changes in magnetic flux, using a controller to process signals from multiple sensors to maintain accuracy and resist radial movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If semiconductor elements or optical elements are used in conventional resolvers and encoders to achieve precise angular measurement, then measurement precision is improved, but reliability deteriorates in high-radiation environments
Solution Approach 1:
The patent changes the material parameters of the sensor from semiconductor or optical elements to ferromagnetic materials and conductive wire, which have different physical properties that are resistant to radiation damage. This parameter change allows the sensor to maintain both precision and reliability in high-radiation environments.
Solution Approach 2:
The patent uses simple ferromagnetic materials and wire that are not adversely affected by radiation, replacing expensive and fragile semiconductor/optical elements. These simpler components can withstand radiation without degradation, effectively making the sensor system more durable and less prone to premature failure.
2Measurement precision
If conventional sensors are used in high-speed rotation environments, then angular position measurement is achieved, but reliability deteriorates due to damage from high rotational speeds
Solution Approach 1:
The patent changes the sensor construction from delicate semiconductor/optical components to robust ferromagnetic materials and wire windings. This parameter change in material strength and mechanical durability allows the sensor to withstand the centrifugal forces and mechanical stress of high-speed rotation (30,000-40,000 RPM) without damage.
3Measurement precision
If multiple sensors and signal processing are used to maintain accuracy during radial movements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent positions two first-ring magnetic sensors at asymmetric locations (0 degrees and 180 degrees) around the rotor. This asymmetric placement creates differential signals that naturally compensate for radial movements and eccentricity, maintaining measurement precision without requiring complex active compensation mechanisms.
Solution Approach 2:
The controller processes signals from multiple sensors using feedback mechanisms to compensate for radial movements and maintain accurate angular position measurement. The controller adjusts for variations in magnetic flux caused by radial displacement, ensuring consistent output signals despite mechanical tolerances.
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 precise angular position measurement with sub-degree accuracy, resistant to radiation and high-speed rotation, extending the lifespan of the detector in harsh environments.
Implementation Method 1
A variable reluctance sensor is a good candidate for measuring shaft position in such environments. Variable reluctance sensors generally include a permanent magnet sensor core around which a conductive wire is wrapped. Changes in the magnetic flux produced by the sensor core affect a current flow in the wire wrapped around the magnet.
Implementation Method 2
The path of the magnetic flux may be affected by moving a body of ferromagnetic material toward and away from the sensor core. Placing a body of ferromagnetic material near the magnet concentrates the flux path in the body of material because the body exhibits a lower reluctance than the surrounding air.
Data Source
AI summary
An angular position detector includes a cylindrical rotor having an axis of rotation and a first ring with a plurality of alternating teeth and valleys, a first first-ring magnetic sensor having a sensor surface facing the first ring, the first first-ring magnetic sensor being configured to produce a first signal in response to movement of the first ring past the first first-ring magnetic sensor, a second first-ring magnetic sensor having a sensor surface facing the first ring and being configured to produce a second signal in response to movement of the first ring past the second first-ring magnetic sensor, the second first-ring magnetic sensor being circumferentially offset from the first first-ring magnetic sensor by a first angle and a controller operatively connected to the first and second first-ring magnetic sensors and configured to produce a first output signal based on the first and second signals.