Single Coil Electromagnetic Flow Meter Design
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Solution Overview
Problem
The high cost of electromagnetic flow meters due to expensive materials and labor costs, as well as the inefficiency of traditional designs using two coils to generate a homogeneous magnetic field.
Innovation Solution
A cost-effective electromagnetic flow meter design featuring a single saddle-shaped coil and a moulded insert with a restriction section, which generates a magnetic field across a measuring section with a unique cross-sectional shape, allowing for accurate flow measurements while reducing material usage and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two coils are used to generate a homogeneous magnetic field, then measurement accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the magnetic field generation function from the traditional dual-coil configuration and implements it using a single coil positioned adjacent to one side of the measuring section. This simplifies the device structure while maintaining the essential function of generating a magnetic field for flow measurement according to Faraday's Law of induction
Solution Approach 2:
The patent applies local quality by positioning the single coil specifically adjacent to one side of the measuring section rather than distributing coils uniformly. This localized approach generates a magnetic field that is sufficient for accurate flow measurement in the critical measurement zone without requiring homogeneous field distribution throughout the entire conduit cross-section
2Stability of the object's composition
If traditional bobbin coils wound on pole pieces are used, then magnetic field homogeneity is improved, but manufacturing cost and labor intensity increase
Solution Approach 1:
The patent replaces expensive, labor-intensive bobbin coils wound on pole pieces with a simpler single coil configuration that can be manufactured more economically. The single coil design reduces material usage and assembly complexity while achieving sufficient magnetic field characteristics for accurate flow measurement
Solution Approach 2:
The patent changes the magnetic field generation parameters by using a single coil with specific positioning and geometry (curved around the outer wall over 140-180 degrees) rather than traditional dual bobbin coils. This parameter change simplifies manufacturing while maintaining adequate magnetic field properties for the measuring section
3Ease of manufacture
If a single coil is used to reduce cost, then manufacturing cost decreases, but magnetic field homogeneity may deteriorate
Solution Approach 1:
The patent addresses the magnetic field uniformity issue by extending the single coil along the length of the measuring section and curving it around the outer wall over an effective angle of 140-180 degrees. This three-dimensional coil configuration distributes the magnetic field generation across multiple spatial dimensions, creating sufficient field uniformity in the measurement zone despite using only one coil
Solution Approach 2:
The patent introduces a moulded insert with a specifically shaped measuring section as an intermediary between the single coil and the fluid flow. The insert's geometry (with parallel sides and specific cross-sectional area ratio less than 70%) acts as a mediator to condition the magnetic field distribution and fluid flow, enabling accurate measurements with a single coil
4Stability of the object's composition
If the measuring section cross-sectional area is reduced to less than 70% of the conduit area, then magnetic field uniformity is improved, but flow capacity decreases
Solution Approach 1:
The patent segments the flow conduit into distinct functional zones: an inlet section with a restriction for conditioning flow, a reduced-area measuring section for accurate magnetic field interaction, and an outlet section for maintaining pressure. This segmentation allows the measuring section to have a smaller cross-sectional area (less than 70% of conduit area) for improved magnetic field uniformity while the overall system maintains adequate flow capacity through the inlet and outlet sections
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 design achieves accurate flow measurements at a lower cost by using a single coil and optimizing the geometry of the insert and electrodes, resulting in a robust and economical flow meter suitable for various applications.
Implementation Method 1
The operating principles are based on Faraday's Law of induction, which states that the voltage induced across any conductor as it moves at right angles through a magnetic field will be proportional to the velocity of that conductor
Implementation Method 2
said inlet comprises a restriction for conditioning the fluid flow through said measuring section
Data Source
AI summary
An electromagnetic flow meter for measuring flow rate of a fluid passing therethrough includes a conduit defining a fluid inlet, a fluid outlet and a measuring section positioned between the inlet and the outlet. The flow meter also includes a single coil for generating a magnetic field across the measuring section and electrodes for detecting induced electrical potential due to the fluid passage. The flow meter also includes means for conditioning the flow through the measuring section. The combination of the single coil and the flow conditioning means provides a flow meter with a desired level of accuracy. The single coil and the electrodes may be arranged so that the integral of a weight function, which defines the sensitivity of the flow meter to fluid velocity through different parts of the measuring section, over the first half of a measuring section closest to the coil is between 0.4 and 1.3 times the integral of the weight function over the other half of the measuring section.