Variable Speed Magnetic Coupling With Ferrofluid Torque Control

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Solution Overview

Problem

Conventional magnetic couplings are limited in their ability to transfer torque between two shafts while allowing them to rotate at different speeds, as they are typically configured for equal rotational speeds, which is not suitable for applications requiring varying speeds.

Innovation Solution

A magnetic coupling design that includes a magnetic field gap between driving and driven connectors, utilizing magnet assemblies and a ferrofluid to control torque transfer, allowing for predictable rotational slip and varying rotational speeds by adjusting the magnetic flux through power supply to the electromagnets or energy applied to the ferrofluid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional magnetic couplings are used to transfer torque between two shafts, then coupling wear is eliminated and reliability is improved, but the rotational speeds of the two shafts must be equal which limits applicability

Engineering Contradiction:

Improvecoupling reliabilityVSAvoidspeed ratio adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The magnetic coupling system employs adjustable magnetic flux strength through controllable magnet assemblies (electromagnets or permanent magnets with adjustable positioning) to dynamically control the torque transfer characteristics. This allows the coupling to adapt to different speed ratios while maintaining reliable magnetic coupling, resolving the contradiction between reliability and speed ratio adaptability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the magnetic flux parameter by adjusting the strength or positioning of the magnet assemblies to enable different torque transfer levels. This parameter adjustment allows the coupling to accommodate varying speed ratios between shafts while maintaining the wear-free magnetic coupling mechanism, thus preserving reliability while gaining versatility.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If gearbox couplings are used to allow different shaft speeds, then speed ratio flexibility is achieved, but frequent maintenance and short lifespan occur due to frictional contact

Engineering Contradiction:

Improvespeed ratio flexibilityVSAvoidcoupling lifespan

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention replaces the mechanical gear-based torque transfer system with a magnetic field-based system. This substitution eliminates the frictional contact inherent in gearbox couplings, thereby removing the cause of wear and frequent maintenance while preserving the ability to handle different shaft speeds through adjustable magnetic flux.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The magnetic field acts as an intermediary between the two shafts, transferring torque without direct mechanical contact. This intermediary mechanism enables speed ratio flexibility while avoiding the frictional wear that plagues direct mechanical gear couplings, thus extending lifespan and reducing maintenance needs.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If magnetic field strength is increased to transfer more torque, then torque capacity is improved, but the ability to allow speed differences between shafts is reduced

Engineering Contradiction:

Improvetorque transfer capacityVSAvoidrotational speed difference capability

Core Design Contradiction:

ForceVSAdaptability or versatility

Solution Approach 1:

The magnetic coupling system provides dynamic control of magnetic flux strength, allowing the torque capacity to be adjusted in real-time. This dynamic adjustment capability enables the system to maintain high torque transfer when needed while still permitting speed differences between shafts by reducing magnetic flux, thus resolving the contradiction between torque capacity and speed difference capability.

Inventive Principle:

Principle #15Dynamics

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

Enables reliable torque transfer between shafts with controlled rotational speed differences, reducing maintenance needs and extending the lifespan of the coupling by allowing for adjustable torque and speed ratios between connected shafts.

Implementation Method 1

A magnetic field gap is disposed between the driving connector and the driven connector

Methodology Applied

Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 2

utilizing magnet assemblies and a ferrofluid to control torque transfer, allowing for predictable rotational slip and varying rotational speeds by adjusting the magnetic flux through power supply to the electromagnets or energy applied to the ferrofluid

Methodology Applied

Scientific EffectFerrofluid: Ferrofluid

Data Source

PatentEP2630384B1Variable speed magnetic coupling

Publication Date: 2019.12.11 DRESSER RAND CO

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AI summary

A magnetic coupling including a rotatable driving connector having a first magnet assembly coupled thereto and a rotatable driven connector having a second magnet assembly coupled thereto. The driven connector may be configured to slip predictably with respect to the driving connector based on a controllable amount of torque transferred between the driving and driven connectors.