Magnetic Shield Plate Below Iron Bolts for Wireless Power

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Solution Overview

Problem

Conventional contactless power receiving devices face issues with reduced magnetic flux reception due to induction heating of iron bolts and potential loosening caused by vehicle vibrations, affecting the secure holding of the power reception coil unit.

Innovation Solution

A contactless power receiving device with a magnetic shield plate arranged below the iron bolts, featuring a rectangular shape and recessed bolt shield portions to reduce magnetic flux interference with the iron bolts, thereby increasing received magnetic flux and stabilizing the power reception coil unit's attachment to the vehicle body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If iron bolts are used to fix the power reception coil unit, then the power reception coil unit can be securely attached to the vehicle body, but the iron bolts are heated by induction due to magnetic flux and the amount of magnetic flux received by the power reception coil decreases

Engineering Contradiction:
Improveholding strength of iron boltsVSAvoidmagnetic flux received by power reception coil
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The magnetic shield plate is divided into multiple functional regions: a shield plate main body that provides overall magnetic shielding, and separate bolt shield portions that specifically target the iron bolts. This segmentation allows different parts of the shield plate to perform specialized functions - protecting both the magnetic flux reception area and the bolt attachment points simultaneously.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The magnetic shield plate acts as an intermediary component positioned between the power supply coil and the iron bolts. By introducing this intermediate magnetic shielding structure, the harmful magnetic flux is redirected away from the iron bolts before they can be heated by induction, while still allowing the power reception coil to function effectively.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If iron bolts are used to fix the power reception coil unit, then the power reception coil unit can be attached to the vehicle body, but the iron bolts may loosen due to vehicle vibrations

Engineering Contradiction:
Improveholding strength of iron boltsVSAvoidstability of iron bolt attachment
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The magnetic shield plate combines two functions into a single component: magnetic shielding and mechanical reinforcement. The shield plate main body provides magnetic flux shielding, while the integrated bolt shield portions simultaneously serve as reinforcement structures that prevent bolt loosening from vibrations, eliminating the need for separate reinforcement components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The magnetic shield plate utilizes composite structural design with the shield plate main body and bolt shield portions forming an integrated composite structure. This composite configuration provides both magnetic shielding properties and enhanced mechanical strength to resist vibration-induced loosening.

Inventive Principle:
Principle #40Composite materials

3Object-affected harmful factors

If a magnetic shield plate is arranged below the power reception coil unit, then magnetic flux diffusion to surroundings is suppressed, but the iron bolts are still affected by magnetic field and heated by induction

Engineering Contradiction:
Improvemagnetic flux diffusion to surroundingsVSAvoidtemperature of iron bolts
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The magnetic shield plate implements local quality by creating regions with different shielding characteristics. The shield plate main body provides general magnetic flux containment, while the bolt shield portions create localized shielding zones specifically around the iron bolts. This local differentiation allows the structure to address both overall flux diffusion and localized bolt heating issues.

Inventive Principle:
Principle #3Local quality

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 solution enhances the amount of magnetic flux received by the power reception coil while ensuring stable attachment of the power reception coil unit, addressing both flux reduction and holding strength concerns.

Implementation Method 1

a power reception coil configured to contactlessly receive magnetic flux sent from a power supply coil

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a magnetic shield plate configured to suppress diffusion of the magnetic flux received by the power reception coil unit to surroundings

Methodology Applied
Scientific EffectMagnetic shielding: Magnetic Field

Implementation Method 3

the iron bolts are affected by a magnetic field and are heated by induction

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Data Source

PatentEP3466746B1Non-contact power receiving device
Publication Date: 2021.02.24 NISSAN MOTOR CO LTD
  • EP3466746B1 patent drawingFigure 1
  • EP3466746B1 patent drawingFigure 2~3
  • EP3466746B1 patent drawingFigure 4~5

AI summary

A contactless power receiving device includes: a power reception coil unit 11 including a power reception coil 41 configured to contactlessly receive magnetic flux sent from a power supply coil; iron bolts 13 fixing the power reception coil unit 11 to a reinforcement member 5; and a magnetic shield plate 21 configured to suppress diffusion of the magnetic flux received by the power reception coil unit 11 to surroundings. The magnetic shield plate 21 is arranged below all of the iron bolts 13.