Wound Magnetic Core Gap Stabilization via Welded Bridging Element
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Solution Overview
Problem
Conventional magnetic circuits with wound cores face challenges in maintaining accurate and reliable current sensing due to variations in air-gap size caused by thermal and mechanical stresses, magnetic saturation, and limitations in heat treatment post-resin application, which affect magnetic permeability and sensor performance.
Innovation Solution
A magnetic circuit with a wound core featuring stacked concentric ring layers and a non-magnetic metal bridging element welded on either side of the air gap, extending across all ring layers, which stabilizes the gap size and prevents radial separation under stress, allowing for annealing and maintaining uniform magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resin is applied around the wound core to hold concentric layers, then the structural integrity and layer binding are improved, but heat treatment (annealing) becomes difficult or impossible due to high temperature requirements
Solution Approach 1:
The patent removes the resin binding layer from the manufacturing process entirely. Instead of using resin to hold concentric layers together, the invention uses a different approach: the magnetic core is formed by winding and then heat-treated without resin, allowing proper annealing at high temperatures to achieve desired magnetic properties.
2Stability of the object's composition
If resin is used to bind magnetic layers, then layer stability is improved, but uniform magnetic properties and high magnetic permeability deteriorate due to inability to perform proper heat treatment
Solution Approach 1:
The resin binding material is completely removed from the process. The patent achieves layer stability through alternative means that do not interfere with heat treatment, allowing the magnetic core to be properly annealed to achieve uniform magnetic properties and high permeability throughout the structure.
3Manufacturing precision
If a T-shaped insert is used to fix the air gap from the outer radial side, then gap positioning is achieved, but the insert only engages outer peripheral layers and cannot prevent variation in inner radial layers due to thermal forces
Solution Approach 1:
Instead of positioning the gap-stabilizing element from the outer radial side (one-dimensional approach), the patent uses a bridging element that extends across the air gap in the radial dimension, connecting opposite sides of the gap. This multi-dimensional approach ensures that thermal expansion forces are counteracted throughout the entire magnetic core structure, not just at the periphery.
4Strength
If resin is applied to bind layers, then mechanical binding is improved, but annealing heat treatment is prevented due to resin degradation at high temperatures
Solution Approach 1:
The resin is completely removed from the manufacturing process. The patent achieves layer binding and structural integrity through mechanical winding and thermal processing without any organic binding materials that would degrade at annealing temperatures, enabling proper heat treatment to proceed.
5Ease of manufacture
If the bridging element is positioned on the outer radial periphery, then assembly is simplified, but it does not effectively stabilize the air gap or prevent thermal expansion variations in the magnetic core
Solution Approach 1:
The bridging element is repositioned from the outer radial periphery to span across the air gap itself, extending from one side of the gap to the other in the radial direction. This positioning allows the element to directly constrain the gap dimensions and counteract thermal expansion forces acting on the magnetic core layers, while still maintaining manufacturing simplicity.
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 compact, robust, and reliable magnetic circuit resistant to thermal and mechanical stresses, ensuring accurate current sensing with uniform magnetic permeability and enabling easy assembly of magnetic field detectors, while allowing for heat treatment to optimize magnetic properties.
Implementation Method 1
the bridging element is welded to the core either side of the gap, the welding connection between the bridging element and the core extending across the concentric ring layers from a radially innermost ring layer to a radially outermost ring layer
Implementation Method 2
A primary conductor extending through a central passage of the magnetic circuit generates a magnetic field that is picked-up by the magnetic core. The magnetic field flows across the gap and the magnetic field detector positioned therein
Implementation Method 3
magnetic core made of material with a high magnetic permeability
Implementation Method 4
losses due to the formation of Eddy currents in the magnetic core
Implementation Method 5
Once the resin has been applied, annealing of the material of the wound magnetic core is difficult or no longer possible in view of the high temperatures required for the annealing process
Data Source
AI summary
Magnetic circuit comprising a gap bridging element made of a non-magnetic metal and a wound magnetic core comprising a plurality of stacked concentric ring layers of magnetic material having a high magnetic permeability. The magnetic core has a gap extending through a section of the stacked concentric ring layers of magnetic material, wherein the bridging element is welded to a lateral face of the wound magnetic core on either side of the gap. Welding connections between the bridging element and the magnetic core extend across the stacked concentric ring layers.