Magnetic Rotary Encoder Using Permeable Discs for Precision Sensing
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Solution Overview
Problem
Existing encoders for flow metering, such as optical and electrical contact types, face issues like dirt sensitivity, light pollution, high expense, and low reliability, while magnetic encoders have limitations in precision due to permanent magnetization challenges.
Innovation Solution
A magnetic rotary encoder design utilizing soft magnetic materials with specific geometry, magnetic switch circuitry to reduce noise, and a ferromagnetic flux closure device to minimize cross-talk, along with optimized disk geometry and sensor designs for precise position sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical encoders are used, then measurement precision is improved, but reliability deteriorates due to dirt and light pollution
Solution Approach 1:
The patent replaces optical encoding mechanisms with magnetic encoding mechanisms. Instead of using optical disks with light sources and detectors, the invention uses magnetically permeable encoder disks that interact with magnetic sensors, eliminating susceptibility to light pollution and dirt while maintaining measurement precision through magnetic field interactions.
Solution Approach 2:
The patent changes the physical parameter used for encoding from optical properties (light transmission/reflection) to magnetic properties (magnetic permeability variations). By using magnetically permeable materials with specific geometric patterns, the system achieves reliable position sensing that is immune to optical interference while maintaining high measurement precision.
2Ease of manufacture
If electrical contact encoders are used, then cost is reduced, but reliability deteriorates due to wear over time
Solution Approach 1:
The patent replaces electrical contact mechanisms with non-contact magnetic sensing. Instead of physical contacts that wear over time, the invention uses magnetic fields to encode and detect position information, eliminating mechanical wear while keeping the system cost-effective through simpler magnetic components compared to optical systems.
3Reliability
If permanent magnet encoder wheels are used, then reliability is improved, but manufacturing precision deteriorates due to limited magnetization capability
Solution Approach 1:
The patent changes from using permanent magnets with fixed magnetization to using magnetically permeable materials whose magnetic properties can be precisely controlled during manufacturing. This allows for more accurate geometric patterns and magnetic field distributions, improving manufacturing precision while maintaining the reliability benefits of magnetic encoding.
Solution Approach 2:
The patent employs magnetically permeable materials with specific geometric patterns rather than traditional permanent magnets. This composite approach combines materials with high magnetic permeability and precisely engineered geometric features, enabling better control over magnetic field distribution and improving overall manufacturing precision.
4Measurement precision
If multiple wheels are added for long-term counting, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent designs each encoder wheel to be functionally identical with the same magnetic encoding pattern, allowing any wheel to serve any position in the multi-wheel assembly. This universality simplifies manufacturing and assembly while maintaining the ability to record readings over several decades through proper wheel configuration and magnetic interaction.
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 cost-effective, reliable, and high-precision magnetic rotary encoder with reduced noise and cross-talk, enabling accurate long-term flow measurement in flow meters.
Implementation Method 1
one or more permanent magnets to provide magnetic field bias
Implementation Method 2
a permeable magnetic disk structure, wherein the permeability of the disk varies with rotation angle of the disk about the rotation shaft
Implementation Method 3
multiple magnetic sensor units disposed in the same plane for sensing the magnetic permeability of the encoder disk, thereby outputting a signal characterizing the position of the encoder disk
Data Source
AI summary
Provided is a magnetic absolute rotary encoder, comprising a rotation shaft, multiple rotating wheels that can rotate along the rotation shaft, multiple encoding units that correspond to the multiple rotating wheels one-to-one, and one or more permanent magnet assemblies that provide the magnetic bias to the multiple encoding units. Each encoding unit comprises a magnetically permeable encoder disc, the structure thereof enabling the magnetic permeability thereof to be different according to the different positions of the rotation shaft, and comprises multiple sensor units that comprise multiple magnetic sensors. The sensor units are used to sense the magnetic permeability of the magnetically permeable encoder disc and to output the sensor signals that characterize the relative position of the magnetically permeable encoder disc. According to the sensor signals of the sensor units, each encoding unit outputs the value that characterizes the selected rotation position of the corresponding rotation wheel, thereby enabling an absolute magnetic rotating encoder that is simple and low in cost and has more precise magnetic encoder discs.