Current Sensor Laminated Magnetic Core Mechanical Fastening
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Solution Overview
Problem
Conventional electrical current sensors with laminated magnetic cores face inaccuracies due to mechanical shock, vibration, and thermal stresses, which cause deterioration of the welding holding the stacked sheets and shifts in the magnetic field detector, leading to changes in magnetic induction and measurement inaccuracy over time.
Innovation Solution
An electrical current sensor with a magnetic core and a magnetic field detector positioned in an air gap, secured by a conductive mounting element with crimped extensions and a bridge portion that also serves as an electrical terminal for grounding, providing secure assembly and resistance to mechanical stresses, and ensuring accurate positioning and grounding of the magnetic field detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to hold the stacked sheets together, then the magnetic core can be assembled, but the welding deteriorates under mechanical shock and vibration leading to measurement inaccuracy
Solution Approach 1:
The patent replaces the welding process (thermal/mechanical joining) with a mechanical fastening system using fasteners that pass through the stacked sheets. This substitution eliminates the deterioration issues associated with welding under mechanical shock and vibration, as the mechanical fastening system maintains its integrity under such stresses.
Solution Approach 2:
The patent divides the magnetic core into modular stacked sheets that are individually secured by fasteners. This segmentation allows each sheet to be independently positioned and secured, preventing relative movement between sheets under mechanical stress while maintaining the overall magnetic circuit integrity.
2Measurement precision
If the magnetic field detector is positioned in the air gap, then current measurement is enabled, but the detector shifts from its initial position under thermal and mechanical stresses causing measurement inaccuracy
Solution Approach 1:
The patent incorporates positioning features directly into the housing structure before the magnetic field detector is installed. These pre-formed positioning features guide and secure the detector in its correct position, preventing shifts under thermal and mechanical stresses during operation.
Solution Approach 2:
The patent introduces positioning features as intermediary elements between the housing and the magnetic field detector. These features act as mediators that maintain the detector's position relative to the air gap, isolating it from the effects of thermal expansion and mechanical vibrations.
3Ease of manufacture
If the stacked sheets are loosened, then assembly is simpler, but changes in magnetic induction occur leading to measurement inaccuracy
Solution Approach 1:
The patent designs the fastening system so that the fasteners automatically secure the stacked sheets in their correct positions during assembly. The sheets themselves provide the positioning information through their geometry and arrangement, eliminating the need for complex external fixtures or alignment procedures.
Solution Approach 2:
The patent employs fasteners that serve multiple functions: they mechanically secure the stacked sheets together, maintain the correct air gap dimensions, and prevent relative movement between sheets. This multi-functionality achieves both easy assembly and stable magnetic induction without requiring separate components for each function.
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 enhances the reliability and accuracy of current measurement by securely fastening the magnetic core and detector, resisting shock and vibration, and maintaining precise positioning, thus improving the sensor's performance under thermal and mechanical stresses.
Implementation Method 1
The magnetic induction generated by the electrical current is measured by a magnetic field detector positioned in the air gap of the magnetic core
Implementation Method 2
the bridge portion comprising an electrical terminal in electrical contact with a grounding terminal of the current sensor
Data Source
AI summary
An electrical current sensor (2) comprising a magnetic core (6) with an air gap (14), a magnetic field detector (8) positioned at least partially in the air gap, and a conductive mounting element (10). The mounting element comprises at least first and second fixing extensions (56) extending between opposed outer faces of the magnetic circuit, and a bridge portion (34) interconnecting the fixing extensions and spanning across the air gap. The bridge portion comprises an electrical terminal (42) in electrical contact with a grounding pad (24) of the magnetic field detector.