Propeller Hub Cooling Tunnel for Electric Motor Heat Management

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Solution Overview

Problem

Electric boat propeller motors face inefficiencies due to heat losses, leading to reduced performance and short lifespan, and are limited to small boats due to ineffective cooling and high temperature issues.

Innovation Solution

A boat propeller arrangement with a stator and rotor around the propeller hub, featuring a cooling tunnel and ribs for enhanced heat transfer, using a permanent magnet synchronous motor with thermally conductive surfaces, eliminating the need for separate transmission and cooling systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If electric motor power is increased, then propulsion capability is improved, but motor temperature increases and efficiency drops

Engineering Contradiction:
Improvemotor powerVSAvoidmotor temperature
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent converts the harmful effect of motor heat into a beneficial cooling mechanism by directing water flow through the propeller hub tunnel to cool the motor. The water that would otherwise be wasted is utilized to remove heat from the stator and rotor, transforming a harmful thermal effect into a useful cooling function.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent merges the propulsion system and cooling system into a single integrated structure. The propeller hub serves dual functions: generating propulsion through the rotor-stator mechanism and cooling the motor through internal water channels. This eliminates the need for separate cooling components and reduces overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Power

If motor size is increased to provide more power, then propulsion capability is improved, but device complexity and boat size limitations increase

Engineering Contradiction:
Improvepropulsion powerVSAvoidcooling system complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The propeller hub is designed as a multi-functional component that simultaneously performs propulsion generation and motor cooling. The water flow path through the hub serves both to cool the motor and to be part of the propulsion mechanism, eliminating the need for dedicated cooling pipes and heat exchangers.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the propulsion and cooling functions into a single integrated system. The rotor-stator mechanism provides propulsion while the water flow through the hub provides cooling, eliminating the need for separate cooling systems and reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Power

If motor power is increased, then propulsion capability is improved, but energy efficiency decreases due to heat losses

Engineering Contradiction:
Improvemotor powerVSAvoidheat loss
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent converts the wasted thermal energy into a useful cooling function. By directing water through the motor components, the heat that would otherwise be lost is actively removed, maintaining lower operating temperatures and improving overall energy efficiency. The cooling water absorbs heat from the stator and rotor, preventing energy loss through thermal degradation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent implements continuous cooling through constant water flow through the motor during operation. This ensures that heat is continuously removed from the stator and rotor, maintaining optimal operating temperatures and preventing efficiency degradation over time. The cooling action is sustained throughout the entire operational cycle.

Inventive Principle:
Principle #20Continuity of useful action

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 energy efficiency, allows for wider boat size applications, including racing boats, reduces environmental impact, and achieves energy savings by effective cooling and reduced need for additional cooling systems.

Implementation Method 1

a tunnel is created through the propeller hub to allow water to flow through the tunnel for cooling the motor

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 2

cooling ribs are also arranged in the tunnel in order to further enhance the heat transfer from the stator to the water

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

the magnet frame is magnetized, and the magnetic force thus created by the stator rotates the surrounding rotor comprised of barrels and a blade

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2762402B1Propulsion arrangement for a vessel
Publication Date: 2023.03.22 SUPERSTREAM OY
  • EP2762402B1 patent drawingFigure 1~2
  • EP2762402B1 patent drawingFigure 3~4

AI summary

The invention relates to a propeller driven by an electric motor. The use of electric outboard motors is known but, because they have been relatively ineffective so far, they have only been used with very small boats or inflatable boats, for example. The boat propeller arrangement according to the present invention comprises a stator (102) and a rotor (104) arranged within each other around the propeller hub, on the outer surface of which rotor propeller blades (106) are provided, wherein a tunnel (108) is created through the propeller hub to allow water to flow through the tunnel (108) for cooling the motor.