Magnetic Core Leg Geometry for Cooler Continuous Stimulation

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Solution Overview

Problem

Conventional magnetic stimulation devices face challenges in maintaining a surface temperature below 43°C due to heat generation, especially in smaller devices used for rehabilitation, which limits the number of pulses and magnetic flux density, making it difficult to achieve continuous effective stimulation without overheating.

Innovation Solution

The magnetic stimulation device features a unique magnetic core design with sloping legs and a cooling mechanism, including a casing with cooling spaces, and conductors wound in a specific layered structure to reduce temperature rise and maintain magnetic flux density, allowing for continuous stimulation without exceeding safety limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a large current is supplied to the coil to generate effective magnetic flux for magnetic stimulation, then the magnetic flux density increases and stimulation effectiveness improves, but significant heat generation occurs in the coil causing temperature rise that limits continuous operation

Engineering Contradiction:
Improvemagnetic flux densityVSAvoidcoil temperature
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent converts the harmful heat generated by coil resistance into a beneficial cooling effect by introducing a cooling fluid through a cooling chamber. The heat that would otherwise limit continuous operation is now managed through controlled thermal exchange, allowing sustained high-power magnetic stimulation without dangerous temperature accumulation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a cooling fluid as an intermediary substance between the heat-generating coil and the surrounding environment. This fluid acts as a heat transfer medium, absorbing excess thermal energy from the coil and transporting it away, thereby enabling continuous high-power operation without direct thermal damage to the device or patient.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the device size is reduced for portability and patient comfort, then ease of operation improves, but heat dissipation capability decreases leading to faster temperature rise

Engineering Contradiction:
Improvedevice portabilityVSAvoidtemperature rise rate
Core Design Contradiction:
Ease of operationVSTemperature

Solution Approach 1:

The patent nests the cooling fluid passage and cooling chamber within the compact device structure, integrating the thermal management system into the existing device architecture. This nested arrangement allows effective heat dissipation without increasing the overall device footprint, maintaining portability while managing thermal loads from high-power operation.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Productivity

If the number of magnetic pulses is increased to enhance rehabilitation effectiveness, then treatment efficacy improves, but cumulative heat generation increases causing temperature to exceed safety limits

Engineering Contradiction:
Improvenumber of magnetic pulsesVSAvoidsurface temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent enables continuous magnetic stimulation by implementing an active cooling system that operates throughout the treatment session. The cooling fluid continuously removes heat as pulses are delivered, allowing the therapeutic process to proceed without interruption or temperature-related safety breaks, thereby maximizing the number of deliverable pulses within the treatment time.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent converts the harmful cumulative heat effect of repeated pulses into a manageable thermal exchange process. By introducing the cooling fluid, the heat that would otherwise accumulate and limit pulse number is transformed into a controlled thermal flow, enabling extended treatment sessions with high pulse counts while maintaining surface temperature below safety thresholds.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

This design effectively suppresses temperature rise and maintains consistent magnetic flux density, enabling longer and more effective magnetic stimulation sessions while ensuring patient safety, even in smaller devices, by reducing eddy currents and enhancing cooling efficiency.

Implementation Method 1

when a pulse current is supplied to a coil placed near the surface of a body to cause the coil to generate a magnetic flux

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

EP 3 332 837 A1 discloses a system including a magnetic field generating device created using a powdered ferromagnetic

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 3

JP 2016-28640 A discloses a technique for air-cooling a magnetic stimulation device so as to suppress a temperature rise of a coil and a magnetic core caused by heat generation during current supply

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

JP 2016-28640 A discloses a technique for air-cooling a magnetic stimulation device

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 5

when a pulse current is supplied to a coil placed near the surface of a body to cause the coil to generate a magnetic flux

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 6

a current is induced in the body by the magnetic flux and the induced current stimulates the nerves to activate the muscles

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4088778B1Magnetic stimulator
Publication Date: 2024.03.06 IFG
  • EP4088778B1 patent drawingFigure 1
  • EP4088778B1 patent drawingFigure 2
  • EP4088778B1 patent drawingFigure 3

AI summary

It is an object of the present invention to make practical use of a magnetic stimulation device, regardless of whether it is large or small in size, that can suppress a temperature rise caused by heat generation during current supply below a safety standard and thus allows continuous magnetic stimulation to be applied many times. A magnetic stimulation device A includes a magnetic core 2, conductors 1b, 1c (1b', 1c'), and a casing 4. The magnetic core 2 includes a core body 2a and first and second legs 2b, 2c extending in one direction from the core body 2a. The conductors 1b, 1c (1b', 1c') are respectively wound in a coil shape around the first leg 2b and the second leg 2c. The casing 4 is a container for housing the magnetic core 2 and the conductors 1b, 1c. The first and second legs 2b, 2c of the magnetic core 2 each have such a shape that a cross-sectional area Sb, Sc of the leg parallel to a plane K passing horizontally through both of the legs 2b, 2c gradually decreases from a base 2k, 21 of the leg near the core body 2a to a tip 2s, 2t of the leg.