Current Sensor Core Stress Isolation via Molding Gap
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current sensor configurations face issues with core deformation due to case dilation and contraction, leading to decreased output and accuracy in current sensing, as stress from temperature and humidity changes is transferred to the core through the molding compound.
Innovation Solution
A current sensor structure featuring projections on the case or magnetic core, with a gap filled by molding compound, absorbs dilative and contractive deformations, preventing stress transfer to the core and maintaining core stability through a three-point-support mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the core is secured to the case using a thick-walled molding compound, then the core is firmly fixed and positioned, but stress from case dilation and contraction is transferred to the core causing deformation
Solution Approach 1:
The molding compound is segmented into two distinct functional zones: a first molding compound that fills the gap and absorbs thermal expansion stress without transferring it to the core, and a second molding compound that firmly secures the core to the case. This segmentation allows the securing function and stress isolation function to be performed by separate material regions, resolving the contradiction between firm fixation and stress prevention.
Solution Approach 2:
The first molding compound acts as an intermediary layer between the case and the core. It absorbs the dilative and contractive deformations of the case and prevents these deformations from being transmitted to the core, thereby protecting the core from stress-induced deformation while still allowing the core to be securely positioned.
2Adaptability or versatility
If the case is made of insulating synthetic resin, then electrical insulation is provided, but the case undergoes rapid dilation and contraction with temperature and humidity changes causing core stress
Solution Approach 1:
Different regions of the molding compound have different mechanical properties tailored to their specific functions. The first molding compound in the gap region has properties optimized for absorbing thermal expansion stress, while the second molding compound in the securing region has properties optimized for firm fixation. This local differentiation of material properties resolves the contradiction between using resin for insulation and maintaining dimensional stability.
3Manufacturing precision
If projections are provided on the case inner surface for positioning, then position gap of the core is prevented, but the core surface is adhered too firmly causing stress transfer
Solution Approach 1:
The positioning projections are covered with the first molding compound that has different stress-absorbing properties compared to the second molding compound. This creates a segmented structure where positioning is achieved through the projections, but stress transmission is blocked by the intermediate first molding compound layer, resolving the contradiction between positioning precision and stress resistance.
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
This solution effectively mitigates core deformation, enhances accuracy in current sensing by absorbing case deformations with the molding compound, and simplifies manufacturing by eliminating the need for additional components.
Implementation Method 1
a gap being provided between the front surface of the magnetic core and the front side of the case, the gap being adapted to be filled with a molding compound so that dilative and contractive deformations of the case in a direction orthogonal to the thickness direction of the magnetic plates are absorbed by the molding compound within the gap
Data Source
AI summary
A current sensor structure includes a substantially ring-shaped magnetic core comprising layers of magnetic plates to be accommodated in an insulating case and secured to the case via a molding compound. Projections protruding in the magnetic plate's thickness direction are provided either on a front-side wall portion of the case in the thickness direction or on a surface of the magnetic core in the thickness direction. By virtue of, the surface of the magnetic core is supported by the front-side wall portion via the projections, leaving a gap between this surface and the wall portion to the same height as that of the projections. The gap is filled with the molding compound. Dilative and contractive deformation of the case in the direction orthogonal to the thickness direction is absorbed by the molding compound in the gap to prevent the stress from acting upon the magnetic core.