Electric Propulsion Motor Cooling Jacket Isolated From Seawater

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Solution Overview

Problem

Existing electric propulsion devices suffer from corrosion of the cooling jacket due to seawater, which can lead to leakage and damage, as the cooling jacket has a complex route with thin walls and smaller diameter.

Innovation Solution

The device employs a dual cooling system, where seawater cools a refrigerant in a heat exchanger outside the motor, and the refrigerant then cools the motor, eliminating direct seawater contact with the motor cooling jacket.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If seawater is used to cool the motor through the cooling jacket, then cooling effectiveness is improved, but corrosion of the cooling jacket occurs

Engineering Contradiction:
Improvemotor cooling effectivenessVSAvoidcooling jacket corrosion resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent introduces a heat exchanger as an intermediary component between the seawater cooling system and the motor cooling jacket. Seawater flows through the heat exchanger to cool the refrigerant, and the refrigerant then circulates through the cooling jacket to cool the motor. This intermediary arrangement prevents direct contact between seawater and the cooling jacket, eliminating corrosion while maintaining effective cooling.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a direct seawater cooling system is used, then device complexity is reduced, but corrosion damage increases

Engineering Contradiction:
Improvecooling system structureVSAvoidcooling jacket durability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The heat exchanger serves as a mediating device that adds a refrigerant circulation loop between the seawater intake and the motor cooling jacket. This intermediary system, while adding components, prevents corrosion of the cooling jacket and extends its service life, ultimately improving system reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If the cooling jacket has thin walls and complex routes, then cooling efficiency is improved, but susceptibility to corrosion damage increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling jacket resistance to corrosion
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The refrigerant circulation system acts as an intermediary that allows the cooling jacket to maintain its optimized thin-wall complex route design for efficient heat transfer, while the heat exchanger prevents seawater from contacting the jacket, thereby protecting it from corrosion.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the seawater cooling function from direct contact with the motor cooling jacket by separating the seawater flow path (through heat exchanger) from the refrigerant flow path (through cooling jacket). This extraction allows the cooling jacket to maintain its efficient design without being exposed to corrosive seawater.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Prevents corrosion of the motor cooling jacket by using a refrigerant to cool the motor, thereby maintaining the integrity of the cooling system and improving the device's stability and maintenance accessibility.

Implementation Method 1

a heat exchanger that uses water from outside the electric propulsion device as cooling water and configured to cool refrigerant

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 2

a motor cooling jacket that is provided in the motor and configured to cool the motor with the refrigerant

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4707159A1Electric propulsion device
Publication Date: 2026.03.11 SUZUKI MOTOR CORP
  • EP4707159A1 patent drawingFigure 1
  • EP4707159A1 patent drawingFigure 2
  • EP4707159A1 patent drawingFigure 3

AI summary

An electric propulsion device (1) includes a motor (3) for rotating a propeller (16) and a cooling device for cooling the motor (3). The cooling device includes a first cooling system and a second cooling system. The first cooling system includes a heat exchanger (45) that uses water from outside the electric propulsion device (1) as cooling water and cools refrigerant, and a supply passage that supplies the water from outside the electric propulsion device (1) as the cooling water to the heat exchanger (45). The second cooling system includes a motor cooling jacket (61) that is provided in the motor (3) and cools the motor (3) with the refrigerant, and a circulation passage that circulates the refrigerant between the heat exchanger (45) and the motor cooling jacket (61).