Coaxial Marine Propeller Drive With High-Torque Axial Flux Motor
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Solution Overview
Problem
Traditional marine propulsion systems face inefficiencies due to limited torque generation at low speeds and the need for reduction gearing, which increases cost, weight, and friction, while also being limited by the number of poles that can be fitted around the axis of rotation in induction motors.
Innovation Solution
A marine propulsion apparatus featuring an electric motor with a rotor and stator configured to generate high torque, where the stator includes multiple phase assemblies with coils that extend circumferentially around a common axis, allowing for a high pole count that minimizes off-center forces and eliminates the need for reduction gearing, with the motor and propeller being coaxial for direct drive and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional induction motors are used with limited poles, then the motor structure is simpler, but torque generation at low speeds is limited and reduction gearing is required
Solution Approach 1:
The patent transitions from traditional radial flux motors to axial flux motors, changing the dimensional orientation of magnetic flux from radial to axial direction. This dimensional change enables high pole count configuration where multiple pole pairs can be arranged around the stator circumference, generating high torque at low speeds without requiring reduction gearing while maintaining a compact structure
Solution Approach 2:
The patent changes key motor parameters including increasing the pole count significantly, switching from radial to axial flux configuration, and operating at variable frequencies (50-400 Hz). These parameter changes enable the motor to generate high torque at low speeds and eliminate the need for reduction gearing while keeping the motor structure compact and simple
2Force
If reduction gearing is added to increase torque, then torque output is improved, but weight, friction, and cost increase
Solution Approach 1:
The patent extracts and eliminates the reduction gearing component from the propulsion system by designing the electric motor itself to generate sufficient high torque at low speeds through axial flux configuration and high pole count. This removal of the gearbox reduces system weight, friction, and complexity while maintaining the required torque output
Solution Approach 2:
The patent replaces the mechanical reduction gearing system with an electromagnetic solution where the axial flux motor directly generates high torque through its magnetic field configuration. This substitution eliminates mechanical friction and weight associated with gearboxes while providing the same torque multiplication effect through electromagnetic design
3Force
If reduction gearing is used to achieve high torque, then torque is improved, but friction and maintenance needs increase
Solution Approach 1:
The patent removes the reduction gearing from the system, eliminating the source of mechanical friction and energy loss. The axial flux motor with high pole count directly generates high torque at low speeds without requiring mechanical speed reduction, thereby eliminating friction losses and reducing maintenance requirements
4Force
If more poles are added to generate high torque, then torque generation is improved, but off-center forces increase
Solution Approach 1:
The patent employs asymmetric winding configurations and pole arrangements in the axial flux motor where pole pairs are strategically positioned and wound to balance magnetic forces. The stator windings are designed with specific asymmetries that cancel out radial and axial off-center forces while maintaining high torque generation through the axial flux configuration
Solution Approach 2:
Instead of adding more radial poles as in traditional motors, the patent inverts the approach by using axial flux with multiple pole pairs arranged circumferentially. This inversion of the traditional pole arrangement method allows high pole count for high torque while the axial flux path naturally balances forces, reducing off-center effects
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 configuration enables high torque generation at both low and high speeds with minimal gearing, reducing weight, friction, and package size, while providing efficient and responsive propulsion with reduced maintenance needs.
Implementation Method 1
a stator disposed within the motor housing and configured to be electrically energized to generate magnetic flux that causes the rotor to rotate
Data Source
AI summary
A fluid moving apparatus includes an electric motor having a rotor and a stator and a propeller. The rotor rotates relative to the stator on an axis to generate a rotational output. The rotational output is provided to the propeller to power the marine propulsion apparatus. The stator includes one or more coils configured to power rotation of the rotor. The one or more coils extend circumferentially around and can be coaxial on the axis. A portion of a housing of the motor extends into the aquatic environment to facilitate heat dissipation.