Segmented Shield Coil Unit for Compact Wireless Power Transfer
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Solution Overview
Problem
Existing wireless electric power transfer systems face challenges in reducing the dimensions of coil units while maintaining efficient power transfer, particularly in vehicles where installation space is limited, and the use of Litz wire is costly and labor-intensive.
Innovation Solution
A coil unit design incorporating a spiral-shaped coil with a magnetic resin layer and divided shield members, featuring gaps and angles between shield pieces to minimize dimensions and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Litz wire is used to suppress skin effect and reduce heat generation, then heat generation is reduced, but manufacturing cost and labor increase significantly
Solution Approach 1:
The patent replaces expensive Litz wire with ordinary enamel wire, accepting some heat generation in exchange for dramatically reduced manufacturing cost and complexity. The ordinary wire is used as a cost-effective alternative that sacrifices some thermal performance for economic viability.
Solution Approach 2:
The patent changes the wire material parameter from Litz wire to ordinary enamel wire, and introduces a magnetic resin layer with specific magnetic properties to compensate for the increased skin effect, thereby resolving the contradiction between cost and heat generation.
2Length of moving object
If planar coil with rectangular wire cross-section is used, then coil thickness is reduced, but coil unit dimensions cannot be sufficiently reduced for vehicle installation
Solution Approach 1:
The patent nests multiple functional layers within a compact structure: the planar coil is placed on a support plate, followed by a magnetic resin layer, then first and second shield members stacked in sequence. This nested arrangement reduces the overall coil unit volume while maintaining thin coil profile.
Solution Approach 2:
The patent transitions from traditional three-dimensional coil winding to a two-dimensional planar coil configuration with rectangular wire cross-section, reducing thickness in one dimension while compensating by optimizing the arrangement in other dimensions through layered stacking.
3Ease of manufacture
If first shield member is divided into multiple shield small pieces, then manufacturing and assembly are facilitated, but device complexity increases
Solution Approach 1:
The first shield member is divided into multiple shield small pieces arranged in an array, which facilitates manufacturing and assembly by allowing modular construction. The segmented structure enables easier handling, positioning, and replacement while maintaining the overall shielding function.
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 design achieves reduced dimensions and improved power transfer efficiency by optimizing the coil structure with shield members and gaps, addressing the limitations of Litz wire in cost and space constraints.
Implementation Method 1
Supplying electric power to the coil of the power transmission apparatus causes a magnetic field to be generated in the coil
Implementation Method 2
Due to the influence of this magnetic field, an electric current flows through the coil of the power receiving apparatus
Implementation Method 3
The amount of heat that the coil generates increases due to, for example, the skin effect
Data Source
AI summary
A coil unit includes a coil, a magnetic resin layer, a first shield member, and a second shield member. The coil includes a coil element formed into a spiral shape around an arbitrary central axis line C. The coil has a first principal surface and a second principal surface that is a surface opposite to the first principal surface. The magnetic resin layer is in direct contact with the second principal surface of the coil. A combination of the coil and the magnetic resin layer, the first shield member, and the second shield member are stacked in this order in a direction from the first principal surface toward the second principal surface. The first shield member is divided into a plurality of shield small pieces.