Annular Core Electric Current Detector with Partial Mold Resin
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Solution Overview
Problem
Existing electric current detectors require complex configurations and troublesome operations for core positioning, leading to increased size, hysteresis, and reduced yield due to resin molding, which can introduce dust and affect magnetic properties.
Innovation Solution
An electric current detector design where an annular core with a magnetic gap is covered by mold resin only along part of its length, allowing precise positioning and reducing hysteresis, with the core component being fixed into an outer case using a mold resin portion that contacts the inner surface, preventing foreign particles from entering during resin molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the core is covered with mold resins to form the outer case, then the core positioning becomes simpler, but large hysteresis occurs in the BH curve between coercive force and residual magnetic flux density
Solution Approach 1:
The core surface is divided into two regions: a first region covered with mold resin for simplified positioning, and a second region exposed without mold resin to maintain magnetic characteristics. This segmentation allows the core to benefit from both simplified assembly and preserved magnetic properties.
Solution Approach 2:
Different portions of the core surface are given different treatments: the first region receives mold resin coverage for positioning ease, while the second region remains exposed to maintain optimal magnetic characteristics. This local differentiation resolves the contradiction between operational ease and reliability.
2Stability of the object's composition
If the core is covered with mold resins, then the core is fixed into the outer case, but fine dust enters into the resins and exposes on the surface to lower the yield
Solution Approach 1:
The core surface is segmented into a first region covered with mold resin for fixation and a second region without mold resin that prevents dust exposure. This segmentation allows fixation while avoiding the yield-reducing dust exposure problem.
Solution Approach 2:
The mold resin coverage is extracted or removed from the second region of the core surface to prevent dust exposure and appearance defects, while maintaining coverage on the first region for fixation purposes.
3Ease of manufacture
If a large space is provided for filling synthetic resin, then the resin can be filled into the outer case, but the size of the outer case increases
Solution Approach 1:
Instead of providing large spaces throughout the entire outer case for resin filling, mold resin is applied only to the necessary first region of the core surface for fixation. This partial application achieves the fixation function without requiring excessive space that would increase overall case size.
4Manufacturing precision
If a complicate configuration is formed for positioning projection, then the core can be temporarily fixed into the outer case, but the positioning operation becomes troublesome
Solution Approach 1:
The positioning function is achieved by segmenting the core surface into a first region with mold resin coverage that provides positioning capability, eliminating the need for complicated positioning projections while maintaining positioning accuracy.
Solution Approach 2:
The mold resin coverage on the first region of the core surface serves dual purposes: it provides fixation and enables simple positioning operations. The structure itself provides the positioning function without requiring additional complicated configurations.
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 enables precise and easy core positioning without increasing the detector's size, reduces hysteresis, and improves manufacturing yield by minimizing external forces during resin molding and preventing dust entry, maintaining magnetic characteristics similar to unmolded detectors.
Implementation Method 1
an electromagnetic conversion element which is located in the magnetic gap of the core (2) and detects a magnitude of an electric current passing through the core (2)
Data Source
AI summary
In an electric current detector according to the present invention, an annular core 2 having a magnetic gap G and a Hall element 41 which is located in the magnetic gap of the core 2 and detects a magnitude of an electric current passing through the core 2 are arranged in an outer case 1. Here, in the core 2, a mold resin portion 3 which covers a surface of the core 2 over part of an overall length along a magnetic path thereof is molded at one or a plurality of portions along the magnetic path to configure an integral core component, the core component being fixed into the outer case 1 in a state where a surface of the mold resin portion 3 makes contact with an inner surface of the outer case 1.