External-Rotor Submersible Thruster for Full-Ocean-Depth Operation
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Solution Overview
Problem
Conventional electric thrusters are limited by air- or oil-filled cavities, requiring frequent maintenance, being costly, and restricted to shallow depths, making them unsuitable for deep-sea applications and cost-effective for hobbyist, academic, or small commercial use.
Innovation Solution
A compact submersible electric thruster design with a low number of parts, no enclosed cavities, and a protective coating to prevent water contact, utilizing an external rotor brushless permanent magnet motor with a propeller and electronic speed controller, allowing operation at extreme pressures and extended periods without maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional enclosed motor designs with air- or oil-filled cavities are used, then the motor is protected from water, but the thruster cannot operate at deep ocean depths due to high pressure affecting the cavities
Solution Approach 1:
The invention removes the air- or oil-filled cavities entirely from the motor design, allowing the motor components to be directly exposed to the surrounding water environment. This extraction of the enclosing medium eliminates the pressure-related reliability issues while maintaining motor functionality through direct water cooling and lubrication of bearings.
Solution Approach 2:
The invention changes the operational parameters by allowing the motor to operate directly in the water environment rather than in an enclosed cavity. The motor is designed to withstand and operate optimally at high pressures, with the water serving as both the operating medium and cooling/lubrication fluid, thereby enabling deep ocean operation.
2Reliability
If mechanical seals are used to seal the motor, then the motor is protected from water, but frequent maintenance is required to replace seals and add grease
Solution Approach 1:
The invention removes mechanical seals and grease lubrication systems from the design. The motor operates with open bearings that are directly lubricated by the surrounding water, eliminating the need for sealed enclosures and periodic maintenance of sealing components.
Solution Approach 2:
The water environment itself serves as the lubrication and cooling medium for the motor bearings. The motor design allows water to freely access the bearing surfaces, providing continuous self-lubrication and cooling without requiring external sealing mechanisms or periodic human intervention for maintenance.
3Reliability
If traditional thruster designs with multiple components are used, then the motor is protected and controlled, but the overall size and cost of the thruster increases
Solution Approach 1:
The invention merges the motor housing, bearing support structure, and control electronics into a highly integrated compact assembly. The stator assembly serves as both the motor structure and bearing support, while the electronics are miniaturized and integrated within the same housing, eliminating the need for separate protective enclosures and reducing overall thruster volume.
Solution Approach 2:
The stator assembly performs multiple functions simultaneously: it provides the motor's electromagnetic structure, supports the bearings, houses the control electronics, and serves as the structural connection to the propeller. This multi-functionality reduces the number of separate components needed, thereby reducing overall thruster size and cost.
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 continuous operation at full ocean depth with minimal maintenance, reducing costs and complexity, making it accessible for various marine applications, including deep-sea exploration and compact vehicle designs.
Implementation Method 1
The stator and motor windings are at the core of the motor and the permanent magnets are arranged in a radial pattern around the stator. Such motors typically have three phase magnetic windings that are commutated by an electronic speed controller.
Implementation Method 2
an external rotor brushless permanent magnet motor that is similar to those commonly used on model aircraft and computer disk drives
Data Source
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AI summary
The invention is a submersible electric thruster that can be used to propel underwater vehicles, surface vehicles, amphibious vehicles, etc. The submersible electric thruster comprises a stationary stator assembly with a base, stator, windings, and bearings and an external rotor assembly comprising a cylindrical arrangement of permanent magnets with a hub that is secured to a shaft wherein the stator forms the center of the motor and the permanent magnets spin around said stator. A propeller hub is integrally connected to the rotor assembly with angularly spaced propeller blades extending radially from said propeller hub. An annular nozzle surrounds the propeller and motor, forming an inlet and outlet for water flow. A nose cone is connected to the stator assembly and a tail cone is integrally connected to the nozzle assembly. A plurality of supporting arms extends from the stator assembly to support the nozzle and a plurality of supporting arms extends from the nozzle to the support the tail cone.