Magnetic Harmonic Drive With Bearingless Flex Gear Actuation

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Solution Overview

Problem

Traditional harmonic gear trains have limited service lives due to the need for bearings, which contribute to increased failure rates and wear, limiting their reliability and efficiency.

Innovation Solution

A compound harmonic actuator is designed with a deformable flex gear incorporating permanent magnets and a magnetic drive using multiphase electric coils, eliminating the need for bearings by deforming the flex gear to engage teeth without wear points, while maintaining performance characteristics similar to traditional wave generators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional harmonic gear trains use bearings to support the wave generator, then the structure is simple and easy to manufacture, but the service life is limited due to bearing wear and failure

Engineering Contradiction:

Improveservice lifeVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical bearing support system with a magnetic field-based support system. The wave generator is supported by magnetic fields generated by electromagnets or permanent magnets, eliminating physical contact and mechanical wear. This substitution of mechanical support with magnetic field support resolves the contradiction by improving reliability through elimination of bearing wear while managing the added complexity of the magnetic support system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of support mechanism from mechanical contact to magnetic field interaction. By transforming the support system from a mechanical bearing-based system to a magnetic field-based system, the patent eliminates wear and extends service life, while the complexity is managed through the use of standard electromagnetic components.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If bearings are used in harmonic gear trains, then the initial structure is simple, but failure rates increase and wear occurs over time

Engineering Contradiction:

Improvefailure rateVSAvoidmanufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical bearings with a magnetic field-based support system. The wave generator is supported by magnetic fields from electromagnets or permanent magnets, eliminating physical contact points that cause wear and failure. This resolves the contradiction by dramatically improving reliability through contactless support, while the manufacturing complexity is managed through the use of standard electromagnetic components and assemblies.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a magnetic drive system is implemented to eliminate bearings, then reliability and efficiency are enhanced, but the device complexity increases

Engineering Contradiction:

ImprovereliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the drive function and support function into a single integrated magnetic field system. The electromagnets or permanent magnets that generate the magnetic field for driving the flex gear also provide the support function, eliminating the need for separate bearing components. This merging resolves the contradiction by enhancing reliability through elimination of bearings while managing complexity through functional integration.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The magnetic field system serves multiple functions: it provides both the driving force for the flex gear and the support for the wave generator. This multi-functionality resolves the contradiction by improving reliability through bearing elimination while managing the added complexity through the dual-use nature of the magnetic system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enhances the reliability and efficiency of harmonic gear trains by eliminating bearing-related failures and wear, providing a more durable and efficient electro-magnetically driven system without the need for intervening gear trains.

Implementation Method 1

a coil assembly disposed and configured to generate a magnetic field with which the permanent magnets interact to deform the flex gear

Methodology Applied

Scientific EffectElectromagnetic interaction: Electromagnetic Induction

Implementation Method 2

permanent magnets arranged along a circumferential length thereof, a coil assembly disposed and configured to generate a magnetic field with which the permanent magnets interact

Methodology Applied

Scientific EffectMagnetic interaction: Magnetism

Data Source

PatentEP3561337B1Magnetically driven harmonic drive

Publication Date: 2023.05.31 HAMILTON SUNDSTRAND CORP

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AI summary

A compound harmonic actuator (10) is provided. The compound harmonic actuator (10) includes a circular gear (40), a flex gear (50) including permanent magnets (53) and a coil assembly (60) disposed and configured to generate a magnetic field with which the permanent magnets (53) interact to deform the flex gear (50). The coil assembly (60) is controllable such that the deformation of the flex gear (50) is such that the flex gear (50) engages with the circular gear (40) resulting in flex gear rotation.