Extended Magnetic Pole Pieces for Flow Meter Accuracy
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Solution Overview
Problem
Magnetic inductive flow meters face challenges in achieving accurate measurements at low flow rates due to increased flow noise and reduced repeatability with higher magnetic field strengths, and existing designs with ferromagnetic materials fail to provide sufficient internal pressure resistance and magnetic field homogeneity.
Innovation Solution
The magnetic flow transducer incorporates extended magnetic pole pieces with tab portions that overlap diamagnetic electrodes, creating a more symmetric magnetic field and reducing fringe effects, thereby increasing measurement accuracy and reliability while maintaining structural integrity and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher magnetic field strength is used to improve measurement accuracy, then measurement precision improves, but flow noise increases and repeatability decreases
Solution Approach 1:
The magnetic pole pieces are designed with non-uniform cross-sectional areas along their length, creating different magnetic field strengths in different regions. The pole pieces have larger cross-sectional areas at certain sections to concentrate magnetic flux and create stronger fields where needed, while having smaller cross-sectional areas at other sections to reduce fringe effects and noise. This local variation in magnetic field strength allows optimization of both measurement precision and repeatability.
2Power
If ferromagnetic materials are used to generate magnetic field, then magnetic field strength increases, but internal pressure resistance is insufficient
Solution Approach 1:
The magnetic pole pieces are constructed from composite materials that combine ferromagnetic properties for magnetic field generation with structural materials that provide internal pressure resistance. The pole pieces may have ferromagnetic cores surrounded by structurally strong materials, or use ferromagnetic alloys with enhanced mechanical properties, creating a composite structure that simultaneously achieves high magnetic field strength and sufficient pressure resistance.
3Measurement precision
If magnetic field strength is increased to improve measurement accuracy, then measurement precision improves, but fringe field interference increases
Solution Approach 1:
The magnetic pole pieces are designed with varying cross-sectional areas along their length, creating different magnetic field strengths in different regions. The pole pieces have larger cross-sectional areas at certain sections to concentrate magnetic flux and create stronger fields where needed, while having smaller cross-sectional areas at other sections to reduce fringe effects and noise. This local variation in magnetic field strength allows optimization of both measurement precision and repeatability.
Solution Approach 2:
The magnetic pole pieces extend in the longitudinal dimension with varying cross-sectional areas, creating a three-dimensional magnetic field distribution. This dimensional variation allows the magnetic field to be concentrated in specific regions while reducing fringe effects in other regions, effectively managing both measurement precision and interference simultaneously.
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 extended magnetic pole pieces enhance measurement accuracy and repeatability, especially at low flow rates, by minimizing fringe field interference and maintaining the magnetic field strength, thus improving the overall performance of the magnetic inductive flow meter.
Implementation Method 1
Magnetic inductive flow meters use a measuring method that is based on Faraday's law of electromagnetic induction
Implementation Method 2
The charge carriers present in the conductive fluid, such as ions and other charged particles, are deflected by the magnetic field: the positive charge carriers to one side and the negative charge carriers to another side
Data Source
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AI summary
A magnetic flow meter includes a -magnetic flow transducer positioned to sense the flow of water through the flow meter. The magnetic flow transducer includes first and second electrodes positioned on opposite sides of a measuring channel. First and second magnetic pole pieces are positioned on opposite sides of the measuring channel and orthogonal to the first and second electrodes. The magnetic pole piece includes extending tab portions that are located adjacent to the first and second electrodes on opposite sides of the first and second electrodes. The extended tabs formed on each of the first and second magnetic pole pieces reduce the induced voltage within the electrodes to increase the accuracy of the measurement taken by the magnetic flow transducer.