Magnetic Cycloid Gear Assembly Torque Density

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Solution Overview

Problem

Existing magnetic gear arrangements face limitations in torque density and are prone to vibrations and wear, particularly in harsh industrial environments, such as ship engines and oil drilling rigs, where conventional mechanical gears are inadequate due to high maintenance needs and inefficiencies.

Innovation Solution

A magnetic cycloid gear assembly comprising multiple inner and outer magnet drums with offset axes and drive mechanisms that allow for eccentric rotation, distributing magnetic load and torque, enabling high torque density and reduced vibration through balanced operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional mechanical gears are used, then torque transmission is achieved, but acoustic noise and vibration increase

Engineering Contradiction:
Improvetorque transmissionVSAvoidacoustic noise and vibration
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical gear system with a magnetic gear system that uses magnetic fields instead of mechanical tooth engagement. The magnetic gears utilize permanent magnets arranged on input and output gear rings, with interpoles that modulate magnetic flux to achieve gear ratio transmission without physical contact, thereby eliminating mechanical noise and vibration associated with tooth meshing.

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

Solution Approach 2:

The patent introduces interpoles as intermediary magnetic elements positioned between the input and output gear rings. These interpoles act as mediators that modulate and transfer magnetic flux between the gear rings, enabling torque transmission through magnetic field interaction rather than direct mechanical contact, thus reducing harmful vibrations and noise.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If conventional mechanical gears are used, then torque transmission is achieved, but wear and fatigue occur requiring maintenance

Engineering Contradiction:
Improvetorque transmissionVSAvoidwear and fatigue resistance
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent replaces the mechanical gear system with a magnetic gear system that uses magnetic fields instead of mechanical tooth engagement. The magnetic gears utilize permanent magnets arranged on input and output gear rings, with interpoles that modulate magnetic flux to achieve gear ratio transmission without physical contact, thereby eliminating mechanical noise and vibration associated with tooth meshing.

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

Solution Approach 2:

The patent introduces interpoles as intermediary magnetic elements positioned between the input and output gear rings. These interpoles act as mediators that modulate and transfer magnetic flux between the gear rings, enabling torque transmission through magnetic field interaction rather than direct mechanical contact, thus reducing harmful vibrations and noise.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If magnetic gear arrangements are used to reduce wear, then mechanical contact is eliminated, but torque density decreases

Engineering Contradiction:
Improvewear resistanceVSAvoidtorque density
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent optimizes the magnetic gear design by varying critical parameters including the number and arrangement of permanent magnets on the gear rings, the positioning and magnetization of interpoles, and the geometric dimensions of the gear structure. These parameter adjustments enable the magnetic gear to achieve both high torque density and wear resistance simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite magnetic structures combining permanent magnets with magnetically soft materials in the gear rings and interpoles. This composite approach creates optimized magnetic circuits that enhance flux density and torque transmission capability while maintaining the non-contact advantage of magnetic gearing.

Inventive Principle:
Principle #40Composite materials

4Ease of repair

If magnetic gear arrangements are used to eliminate mechanical contact, then maintenance is reduced, but torque output capability is limited

Engineering Contradiction:
Improvemaintenance requirementVSAvoidtorque output
Core Design Contradiction:
Ease of repairVSPower

Solution Approach 1:

The patent optimizes the magnetic gear design by varying critical parameters including the number and arrangement of permanent magnets on the gear rings, the positioning and magnetization of interpoles, and the geometric dimensions of the gear structure. These parameter adjustments enable the magnetic gear to achieve both high torque density and wear resistance simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite magnetic structures combining permanent magnets with magnetically soft materials in the gear rings and interpoles. This composite approach creates optimized magnetic circuits that enhance flux density and torque transmission capability while maintaining the non-contact advantage of magnetic gearing.

Inventive Principle:
Principle #40Composite materials

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 magnetic cycloid gear assembly achieves high torque outputs with reduced vibration and wear, allowing for compact, efficient, and low-maintenance gear systems suitable for harsh industrial applications, such as oil drilling and wind turbines, with gear ratios up to 75:1 and compact motor integration.

Implementation Method 1

The nearest magnets between the inner and outer gear rings have the strongest attraction

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

the interpoles act to modulate (shutter) the magnetic flux transferred between the permanent magnets of the gear rings

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentEP3357149B1Radial magnetic cycloid gear assemblies, and related systems and methods
Publication Date: 2020.12.16 NAT OILWELL VARCO LP
  • EP3357149B1 patent drawingFigure 1A~1B
  • EP3357149B1 patent drawingFigure 2A~2B
  • EP3357149B1 patent drawingFigure 3~4

AI summary

A magnetic cycloid gear assembly includes an outer magnet drum comprising a plurality of outer drum magnets having a first number of magnetic pole pairs. The assembly also includes a first inner magnet drum comprising a first plurality of inner drum magnets having a second number of magnetic pole pairs. The assembly also includes a second inner magnet drum comprising a second plurality of inner drum magnets having a third number of magnetic pole pairs. Each of the first and second inner drums has an inner magnet drum axis that is offset from an outer magnet drum axis. The assembly further includes a plurality of drive mechanisms, each mechanism being operatively coupled to each of the first and second inner drums. The plurality of drive mechanisms is configured to drive each of the first and second inner magnet drums to revolve in an eccentric manner about the outer drum axis.