Magnetically Geared Electric Drive for Underwater Propulsion
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Solution Overview
Problem
Current underwater vehicle propulsion systems face challenges with mechanical gearing, including excessive mechanical wear, vibrations, acoustic noise, and maintenance needs, while direct drive brushless motors have higher losses and larger size.
Innovation Solution
A magnetically geared electric drive system is designed with an encapsulated configuration around a central shaft, combining a motor stator, rotor, high-speed inner magnetic gear rotor, and low-speed outer magnetic gear rotor, providing a compact, reliable, and efficient solution for underwater applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical gearing is used to reduce rotational speed, then speed matching to propeller peak operating point is improved, but mechanical wear and maintenance needs increase
Solution Approach 1:
The patent replaces mechanical gearing with a magnetically coupled gearing system where the magnetic gear stator, magnetic gear rotor, and modulating rotor interact through magnetic fields without physical contact. This substitution eliminates mechanical wear between gear teeth while maintaining speed reduction functionality, directly resolving the contradiction between speed matching and mechanical wear.
2Speed
If mechanical gearing is used to reduce rotational speed, then speed matching to propeller peak operating point is improved, but vibrations and acoustic noise increase
Solution Approach 1:
By replacing mechanical gear contact with magnetic field interaction, the system eliminates the source of mechanical vibrations and acoustic noise generated by tooth meshing. The magnetic coupling provides smooth torque transmission without the impact and vibration characteristic of mechanical gears, resolving the contradiction between speed reduction and noise generation.
3Reliability
If direct drive brushless motor is used for reliability, then mechanical wear is eliminated, but size and losses increase
Solution Approach 1:
The patent merges the motor function with the gear function into a single integrated unit. The magnetic gear stator serves as both a motor component and a gear component, while the magnetic gear rotor combines rotor and gear output functions. This merging eliminates the need for separate mechanical gears while maintaining compact size, resolving the contradiction between reliability and motor size.
Solution Approach 2:
The modulating rotor is nested within the magnetic gear rotor, and the magnetic gear stator is nested within the motor stator assembly. This nested configuration allows multiple functional components to occupy overlapping spatial volumes, reducing the overall size of the drive system while maintaining the benefits of both direct drive reliability and gear reduction.
4Speed
If mechanical gearing is used, then speed reduction is achieved, but mechanical contact leads to excessive wear
Solution Approach 1:
The patent substitutes mechanical gear contact with magnetic field coupling throughout the gear interaction process. The magnetic gear stator, magnetic gear rotor, and modulating rotor interact through magnetic attraction and repulsion forces without physical contact between moving gear components. This substitution eliminates wear mechanisms entirely, allowing the system to achieve speed reduction while maintaining component lifespan indefinitely, resolving the contradiction between speed reduction and component durability.
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 enhances power density, reduces maintenance, and increases efficiency by eliminating mechanical contact, minimizing frictional losses, and allowing for multiple gear stages, resulting in improved reliability and reduced noise.
Implementation Method 1
A magnetically coupled gearing system... The device consists essentially of a motor stator, motor rotor, high-speed inner magnetic gear rotor, encapsulated pole pieces, and encapsulated low-speed outer magnetic gear rotor
Implementation Method 2
a magnetically geared electric drive... A magnetic gear can eliminate the need for rotary shaft seals by isolating the motor and drive electronics from the environment with a barrier in the air gap
Data Source
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AI summary
The invention provides an encapsulated magnetically geared brushless electric marine propulsion system with the principle components arranged axially around the central shaft. The marine propulsion system includes: the brushless DC motor, comprised of the stator fixed to the central shaft and motor magnets fixed within the motor rotor coupled to the central shaft using precision ball bearings; the high-speed magnetic gear rotor coupled to the motor rotor comprising an alternating array of magnets fixed to a ferromagnetic backing; the environmental barrier which protects the motor and additionally houses pole pieces to modulate magnetic flux; the low-speed magnetic gear rotor coupled to the central shaft and comprised of an alternating array of magnets fixed to a ferromagnetic backing; the propeller coupled to the low-speed magnetic gear rotor; and the shroud coupled to the struts of the motor mounting system.