Magnet-Driven Heat Sink Flaps for Fanless Convection

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Solution Overview

Problem

Existing heat sinks for electric conductors rely on passive flow phenomena and require additional energy sources, such as fans, to effectively dissipate heat, especially at electric connections where contact resistance generates significant heat.

Innovation Solution

A heat sink design featuring alternatingly arranged fixed fins and flexible flaps with embedded or attached magnets, where the flexible flaps resonate with the AC frequency to enhance convection without additional energy, by oscillating in response to the magnetic field generated by the current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If passive flow phenomena are used for heat dissipation, then device complexity is reduced, but heat dissipation effectiveness is insufficient

Engineering Contradiction:
Improveheat dissipation system complexityVSAvoidheat dissipation effectiveness
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent applies mechanical vibration by attaching magnets to flexible flaps that resonate at the AC frequency of the current flowing through the electric conductor. This vibration enhances convective heat transfer from the heat sink fins to the surrounding air, improving heat dissipation effectiveness without adding complex active cooling systems. The vibration frequency matches the AC frequency (e.g., 50Hz or 60Hz), creating sustained oscillatory motion that disrupts boundary layers and enhances heat transfer.

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The patent replaces the need for mechanical fan systems with an electromagnetic-mechanical coupling system. Instead of using motor-driven fans to force air flow, the system uses the existing AC magnetic field to directly drive flexible flaps with attached magnets, converting electromagnetic energy into mechanical vibration. This substitution eliminates the need for additional motors, power supplies, and control systems while achieving enhanced convection.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If fan-like devices are used to supplement passive flow, then heat dissipation effectiveness is improved, but energy consumption increases

Engineering Contradiction:
Improveheat dissipation effectivenessVSAvoidenergy consumption
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The heat sink system serves itself by utilizing the existing AC current flowing through the electric conductor to drive the flexible flaps. The AC magnetic field generated by the conductor directly actuates the magnets attached to the flaps, creating self-sustaining vibration without requiring external power sources. The system converts the energy already present in the electrical circuit into useful mechanical motion for enhanced heat transfer.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces energy-consuming mechanical fan systems with an electromagnetic-mechanical coupling system that harvests energy from the existing AC field. Instead of using motor-driven fans that require additional power supply, the system uses the AC magnetic field to directly drive flexible flaps with attached magnets, converting electromagnetic energy into mechanical vibration. This substitution eliminates the need for additional motors, power supplies, and control systems while achieving enhanced convection.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Temperature

If flexible flaps with magnets are used to enhance convection, then heat dissipation effectiveness is improved, but device complexity increases

Engineering Contradiction:
Improveconvection enhancementVSAvoidheat sink structure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The heat sink is segmented into fixed fins and flexible flaps with attached magnets. The flexible flaps are distributed among the fins, creating a modular structure where each flap-fin combination acts as an independent convective element. This segmentation allows the system to achieve enhanced heat transfer through distributed vibration while maintaining a relatively simple overall structure that can be manufactured using conventional techniques.

Inventive Principle:
Principle #1Segmentation

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 passive heat dissipation with reduced costs and design effort, providing improved convection and temperature reduction of up to 10 K without requiring external energy sources.

Implementation Method 1

at least one of the flexible flaps comprises a magnet attached to or embedded in at least one of the flexible flaps... positioning the heat sink such that the magnet is arranged substantially perpendicular to the magnetic field generated by a current flowing through the electric conductor

Methodology Applied
Scientific EffectElectromagnetic interaction: Lorentz Force

Implementation Method 2

the resonance frequency of at least one of the plurality of flexible flaps comprises a resonance frequency substantially equal to the AC frequency

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 3

heat sink with improved convection... providing improved convection and temperature reduction

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

a heat sink according to embodiments described herein is in thermal contact with the electric conductor

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 5

passive heat dissipation with reduced costs and design effort, providing improved convection and temperature reduction of up to 10 K

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4712137A1Heat sink with improved convection
Publication Date: 2026.03.18 ABB (SCHWEIZ) AG
  • EP4712137A1 patent drawingFigure 1a~1d
  • EP4712137A1 patent drawingFigure 2~4
  • EP4712137A1 patent drawingFigure 5~6

AI summary

A heat sink, comprising a plurality of fixed fins; a plurality of flexible flaps arranged between the fixed fins; wherein at least one of the flexible flaps comprises a magnet attached to or embedded in at least one of the flexible flaps.