Ferrite Particle Envelope for Low-Frequency Magnetic Shielding
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Solution Overview
Problem
Existing magnetic shields for electrical cables, particularly at the ends, are inadequate in effectively limiting electromagnetic disturbances and maintaining mechanical integrity during connector insertion and maintenance, leading to degradation in immunity performance.
Innovation Solution
A magnetic shielding solution involving an envelope made of non-conductive material with magnetized particles, such as ferrite, is applied only around the untwisted end of the cable, sliding along the twisted portion to ensure continuous coverage and easy installation/removal, without requiring grounding or complex connector designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional electromagnetic shields (conductive wires, Faraday cage, metal mesh) are used around the cable end, then electromagnetic shielding is provided, but the shields are ineffective against magnetic fields below 3MHz and require grounding connections that complicate the design
Solution Approach 1:
The patent changes the material parameter from conductive materials to ferrite particles with specific magnetic properties. The ferrite particles are suspended in a polymer matrix to create a magnetic shielding envelope that is effective for frequencies below 3MHz, eliminating the need for grounding connections and complex connector designs while maintaining shielding effectiveness
Solution Approach 2:
The patent uses a composite material consisting of ferrite particles suspended in a polymer matrix (such as polyurethane, epoxy, or silicone). This composite provides both the magnetic shielding properties needed to block low-frequency magnetic fields and the mechanical flexibility required for cable applications, replacing traditional metal shields
2Ease of operation
If the cable end is detorted for connector insertion, then mechanical connection is enabled, but the twisting protection is lost at the end where shielding is most needed
Solution Approach 1:
The patent segments the cable into two functional zones: the twisted portion for electromagnetic shielding and the detorted end portion for connector insertion. The magnetic shielding envelope is applied specifically to the twisted portion, allowing the end to be prepared for connection while maintaining shielding where the twisted structure provides protection
Solution Approach 2:
The magnetic shielding envelope acts as an intermediary that extends the shielding effect to the cable end region. By applying the ferrite particle envelope to the twisted portion, it mediates between the twisted structure's natural shielding and the need for end preparation, maintaining magnetic field protection while allowing mechanical connection operations
3Object-affected harmful factors
If a rigid Faraday cage shield is used, then electromagnetic shielding is provided, but the shield degrades mechanical properties of the cable and complicates maintenance operations
Solution Approach 1:
The patent replaces rigid Faraday cage shields with a flexible polymer matrix containing ferrite particles. This flexible envelope maintains cable bendability and mechanical properties while providing magnetic shielding. The polymer matrix allows the shield to conform to the cable's flexible nature without degrading its mechanical characteristics
Solution Approach 2:
The patent changes the physical state parameter from rigid metal structures to a flexible polymer-ferrite composite. This parameter change enables the shield to maintain cable flexibility and ease of maintenance while providing effective magnetic shielding, eliminating the trade-off between shielding and mechanical properties
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 configuration effectively attenuates electromagnetic disturbances at frequencies less than 3MHz, maintaining mechanical properties and facilitating maintenance operations while avoiding the inefficiencies of traditional shields.
Implementation Method 1
an envelope with magnetized particles oriented perpendicular to the electric current direction in the cable
Implementation Method 2
Use, for the envelope, a non-conductive electricity material, such as a glue or varnish, charged with a magnetic material, such as ferrite particles
Data Source
Figure 1~3
Figure 4~5
AI summary
It is a question of electromagnetically shielding one end of a multiwire electrical cable (1a, 1b). To do this, a jacket (13) provided with magnetised particles is placed around the cable.