Wheel-Integrated Power Reception Coil Shape for Obstacle-Safe Charging

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Solution Overview

Problem

In wireless power transfer systems, obstacles such as small animals or metal objects between the power transmission and reception devices can cause eddy currents, leading to reduced power reception efficiency and potential fires.

Innovation Solution

A wireless power reception system with a power reception coil housed in a wheel, configured to face downward and have a convex shape, to minimize interference and improve power reception efficiency by aligning with the power transmission coil.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the power transmission device and power reception device are placed far apart, then the installation flexibility is improved, but the power reception efficiency deteriorates due to obstacles causing eddy currents

Engineering Contradiction:

Improveinstallation flexibilityVSAvoidpower reception efficiency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The power reception coil is designed with a convex shape in side view that follows the outer circumferential surface of the wheel. This curved configuration allows the coil to maintain a consistent, minimal distance from the road surface power transmission device as the wheel rotates, preventing obstacles from interfering with the magnetic field path while preserving installation flexibility.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If the power reception coil is positioned close to the power transmission device, then the power reception efficiency is improved, but the safety deteriorates due to obstacles heating up and catching fire

Engineering Contradiction:

Improvepower reception efficiencyVSAvoidobstacle heating and fire risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The convex curved shape of the power reception coil maintains an optimal distance from the road surface, close enough for efficient power transfer but far enough to prevent direct contact with obstacles. This curvature ensures that small animals or metal objects cannot easily enter the magnetic field path, eliminating the fire hazard while preserving power reception efficiency.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The power reception coil is nested within the wheel structure, with at least a portion of it housed inside the wheel. This nesting arrangement protects the coil from direct exposure to road obstacles while maintaining its functional position for wireless power reception, solving both efficiency and safety concerns.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If the power reception coil has a convex shape facing downward, then the power reception efficiency is improved by reducing obstacle interference, but the device complexity increases

Engineering Contradiction:

Improvepower reception efficiencyVSAvoidcoil structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The convex curved shape of the power reception coil is formed to follow the natural outer circumferential surface of the wheel. This curvature, while adding geometric complexity, integrates seamlessly with the wheel's existing structure, minimizing additional manufacturing complexity. The convex shape ensures the coil maintains optimal positioning relative to the road surface during wheel rotation, improving power reception efficiency by preventing obstacle interference.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

Enhances power reception efficiency by reducing the likelihood of obstacles and optimizing magnetic field alignment, thereby improving power transfer reliability and safety.

Implementation Method 1

a power reception coil that receives power supplied wirelessly from a power transmission coil of a power transmission device installed in a road surface

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the power reception coil has a convex shape pointing downward in a side view as seen from an axial direction of the wheel

Methodology Applied

Scientific EffectMagnetic field alignment: Magnetic Field

Data Source

PatentUS12570165B2Wireless power reception system, moving body, and wheel

Publication Date: 2026.03.10 BRIDGESTONE CORP

AI summary

A wireless power reception system 1 includes: a power reception device 5 including a power reception coil 51 that receives power supplied wirelessly from a power transmission coil 41 of a power transmission device 4 installed in a road surface, at least a portion of the power reception coil 51 being housed in a wheel 3 of a moving body 2; and an onboard device 6 which is installed in the moving body 2 and which is electrically connected to the power reception device 5, wherein the power reception device 5 can transmit received power to the onboard device 6, and the power reception coil 51 has a convex shape pointing downward in a side view as seen from an axial direction of the wheel 3.