Magnetic Circuit for Electromagnetic Flowmeter
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Solution Overview
Problem
Magnetic-inductive flowmeters are costly to manufacture and consume significant electrical power due to high stray magnetic field losses, making them unsuitable for mass applications, especially mains-free and maintenance-free operations.
Innovation Solution
A magnetic circuit device with a ring-shaped outer contour formed by arcuate magnetically conductive connecting elements that extensively encompass flat pole elements, reducing stray fields and power consumption by minimizing the cross-section of coil cores and connecting elements, and using a single coil with a cylindrical design and orthocyclic windings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional magnetic circuit devices with rectangular outer contour are used, then the magnetic field can be generated between pole elements, but stray magnetic field losses are high and power consumption is significant
Solution Approach 1:
The magnetic circuit device uses arcuate magnetically conductive connecting elements that form an annular outer contour, curving around the measuring tube to extensively encompass the pole elements. This curved configuration guides magnetic flux along the annular path, containing the magnetic field and reducing stray field losses compared to conventional rectangular configurations.
Solution Approach 2:
The magnetic circuit device is divided into functionally optimized segments: flat pole elements for field generation, arcuate connecting elements for flux guidance, and a coil core for coil support. This segmentation allows each component to be optimized for its specific function, with the connecting elements specifically designed to minimize stray fields while maintaining structural integrity.
2Power
If electrical power is made available permanently to generate sufficient magnetic field, then measurement can be performed, but power consumption occupies significant proportion of total electrical power required
Solution Approach 1:
The invention converts what would be wasted energy (stray magnetic fields) into useful magnetic flux by providing magnetically conductive connecting elements that guide the flux along a controlled annular path. This reduces energy loss and allows sufficient magnetic field generation with lower power consumption, enabling mains-free operation with extended battery life.
3Loss of energy
If the cross section of coil core and magnetically conductive connecting elements is minimized, then stray fields are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes the cross-sectional dimensions of the magnetically conductive connecting elements to achieve a balance between reducing stray fields and maintaining manufacturability. By carefully selecting the cross-section parameters of the arcuate connecting elements, sufficient magnetic conductivity is achieved while minimizing stray field generation, making the design suitable for mass production.
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
Significantly reduces stray field losses to less than 35% of the generated magnetic field, allowing for low-power operation with an operating voltage as low as three volts, making the flowmeter suitable for mass market applications, including domestic use with extended battery life.
Implementation Method 1
The generation of a magnetic field in the measuring tube of a magneto-inductive flowmeter is essential for the realization of the measuring principle, which is based on the separation of moving charges in a magnetic field. The metrological basis is a measuring tube made of a non-magnetic material, for example a non-magnetic metal, which is electrically insulated from the measuring fluid on the flow side by an insulating lining and which is penetrated by a magnetic field generated by the coil of the magnetic circuit device perpendicular to the direction of flow.
Implementation Method 2
a first magnetically conductive connecting element is connected to a narrow side of a first pole element, a second magnetically conductive connecting element is connected to the opposite narrow side of the first pole element and the first connecting element, the second connecting element and the first pole element form an annular magnetic circuit element which defines the annular outer contour of the magnetic circuit device
Implementation Method 3
If a measuring fluid with a minimum electrical conductivity flows through the measuring tube, the charge carriers present in the conductive measuring fluid are deflected by the magnetic field. At measuring electrodes arranged perpendicularly to the magnetic field and to the direction of flow, the charge separation creates a potential difference, i.e. a voltage, which is recorded with a measuring device and evaluated as a measuring voltage. The measuring voltage is proportional to the flow speed of the charge carriers moving with the measuring fluid
Data Source
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Figure 3
AI summary
The magnetic circuit device (1) has a coil (2b) producing a magnetic field, and two plane pole elements (3a,3b), between which in the installed condition the magnetic-inductive flow measuring device is placed. The magnetic conductive connection elements (4a,4b) are provided for magnetic flux of the magnetic circuit. The cross section of the coil core (2a) of the coil or of one or more magnetic conductive connection elements is as small as possible.