Magnet Core Adhesive Fixing for Residual Current Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic cores used in applications like residual current circuit breakers face challenges in maintaining high permeability due to mechanical stresses introduced during winding and handling, which are exacerbated by the use of adhesives that penetrate between tape layers, leading to unpredictable and reduced magnetic properties.
Innovation Solution
A method involving a spirally wound soft-magnetic strip with a pressure-sensitive adhesive that forms a permanently sticky, elastic film to fix the magnetic core in a protective housing, minimizing adhesive penetration and preventing mechanical stress transmission, using acrylate polymers with specific properties for enhanced stability and elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flexible silicone adhesive is used to connect the magnetic core to the housing, then the magnetic core can be fixed in the housing, but the adhesive creeps between the tape layers due to capillary forces and weight, causing tensile stresses and deteriorating magnetic properties
Solution Approach 1:
The harmful function of adhesive penetration between tape layers is eliminated by extracting the adhesive from the interior space between layers. The adhesive is applied only to the outer surface of the magnetic core, preventing capillary creep and subsequent tensile stress that would deteriorate magnetic properties.
Solution Approach 2:
The adhesive is applied locally only to the outer surface of the magnetic core rather than being introduced into the interior tape layers. This localized application ensures fixing strength is achieved at the interface with the housing while preventing adhesive penetration that would cause internal stresses.
2Shape
If the magnetic core is wound from tapes or strip, then the core can be formed with desired geometry, but mechanical stresses are introduced during winding and handling that reduce permeability
Solution Approach 1:
The magnetic core is pre-stressed during the winding process to compensate for subsequent mechanical stresses that will occur during handling and operation. This beforehand cushioning ensures that the core maintains its magnetic properties despite external mechanical influences.
3Reliability
If numerous alloy compositions are used to achieve high permeability, then the magnetic properties can be improved, but the core becomes sensitive to externally introduced mechanical stresses
Solution Approach 1:
The alloy composition parameters are specifically optimized to achieve a balance between high permeability and reduced sensitivity to mechanical stress. By adjusting compositional parameters, the core achieves both high magnetic performance and improved mechanical robustness.
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 approach ensures consistently high permeability and reduced scattering of magnetic properties, maintaining magnetic core performance even under mechanical stress and thermal expansion differences, suitable for applications requiring high relative permeability and stability.
Implementation Method 1
a pressure-sensitive adhesive is applied to an inner wall of the housing, with the pressure-sensitive adhesive forming a film on its surface. After forming the film, the magnetic core is inserted into the protective case with the underside of the magnetic core contacted and adhered to the pressure-sensitive adhesive
Implementation Method 2
the pressure-sensitive adhesive has a permanently sticky surface after drying, the magnetic core can be fixed in the protective housing, which at the same time is elastic enough to compensate for tension
Implementation Method 3
the pressure-sensitive adhesive forms a film on its surface... the penetration of the adhesive between the tape layers can be reduced to a minimum
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A magnet core (1) which is suitable for use in a residual current device and is composed of a spirally wound soft-magnetic strip has an upper face (4) and a lower face (5), wherein the upper face (4) and the lower face (5) are formed by side surfaces (16) of the soft-magnetic strip. The magnet core (1) is fixed in a protective housing (6) and, in order to fix the magnet core (1), an adhesion adhesive (11) is provided between the lower face (5) of the magnet core (1) and a housing inner wall (10).