Magnetic Resin Coil Structure for Higher Wireless Power Coupling
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Solution Overview
Problem
Existing contactless power transmission systems for vehicles equipped with secondary batteries face challenges in reducing leakage magnetic flux and improving the coupling coefficient while maintaining ease of maintenance and robustness.
Innovation Solution
A coil unit is designed with a magnetic resin member that includes a plate-shaped support portion, a frame-shaped wall portion inserted into the air-core region of the coil, and a cover portion that opens and closes the wall portion, enhancing magnetic flux distribution and maintenance accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic member such as a ferrite core is provided, then magnetic flux conduction is improved, but robustness deteriorates due to breakage, defects, and insulation layer breakdown
Solution Approach 1:
The patent uses a magnetic resin member that combines magnetic particles (ferrite or magnetite) dispersed in a resin matrix. This composite structure provides both magnetic flux conduction properties and mechanical robustness, eliminating the fragility of solid ferrite cores while maintaining magnetic functionality. The resin matrix prevents breakage and protects against insulation layer breakdown.
Solution Approach 2:
The invention changes the physical state of the magnetic material from solid ferrite core to magnetic particles suspended in resin. This parameter change transforms the material from brittle to flexible and robust, while still achieving the desired magnetic flux conduction through the dispersed magnetic particles.
2Ease of manufacture
If magnetic flux conductive material is merely formed of core portion and flat portion, then manufacturing is simple, but coupling coefficient improvement is limited
Solution Approach 1:
The patent extends the magnetic resin member to include a wall portion that protrudes into the air-core region of the coil, adding a third dimensional element. This three-dimensional configuration improves magnetic flux distribution and coupling coefficient beyond what simple flat portions can achieve, while still maintaining ease of manufacture through integral molding.
Solution Approach 2:
The magnetic resin member is divided into distinct functional portions: a plate-shaped support portion, a frame-shaped wall portion, and a cover portion. This segmentation allows each portion to be optimized for its specific function while maintaining overall manufacturing simplicity through integral construction.
3Reliability
If wall portion protrudes into air-core region, then main magnetic flux concentration is improved, but maintenance accessibility deteriorates
Solution Approach 1:
The cover portion is designed to be movable, allowing it to open and close the hollow region. This dynamic feature enables maintenance personnel to access the internal space when needed, while maintaining the magnetic flux concentration benefits of the protruding wall portion during normal operation.
Solution Approach 2:
The magnetic resin member is segmented into a wall portion and a separate cover portion. This segmentation allows the wall portion to protrude into the air-core region for magnetic flux concentration while the removable cover provides maintenance access to the hollow region.
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 coil unit improves the coupling coefficient by concentrating main magnetic flux at the center, reduces magnetic flux density on the outer sides, and enhances maintenance ease by exposing the hollow region formed by the wall portion.
Implementation Method 1
the distribution of the main magnetic flux between the power transmitting side and the power receiving side can be spread at a center portion in the direction perpendicular to the axial direction, and a core constant of the entire system can be improved. By improving the core constant, the main magnetic flux can be concentrated in the center portion, an increase in magnetic flux density on the outer side in the direction perpendicular to the axial direction can be curbed, and thus a coupling coefficient can be improved.
Implementation Method 2
a coil configured to transmit or receive electric power through contactless power transmission
Implementation Method 3
it is possible to curb an increase in eddy current loss due to breakage or defects, and occurrence of ground faults and short circuits due to breakdown of an insulation layer through debris
Data Source
AI summary
A coil unit includes a coil and a magnetic resin member (a back member and an inner member). When the power transmitting side and the power receiving side face each other, the magnetic resin member is disposed behind the coil when seen from the other side. A through hole that passes therethrough in an axial direction along a central axis of the coil is formed in the plate-shaped back member. A frame-shaped wall portion (a power receiving side wall portion or a power transmitting side wall portion) of the inner member protrudes in the axial direction from a peripheral edge portion of the through hole and is disposed in an air-core region of the coil. A cover portion (a power receiving side cover portion or a power transmitting side cover portion) of the inner member opens and closes an open end of the wall portion on the protruding side.