Marine Propulsion Cooling Layout With Parallel Water Jacket Distribution

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Solution Overview

Problem

Existing marine propulsion devices face challenges in efficiently cooling motors, transmission mechanisms, and inverters, as determining optimal cooling paths and amounts of cooling water is difficult, leading to insufficient or excessive cooling.

Innovation Solution

A marine propulsion device with a water-cooled cooling system that includes a motor water jacket, transmission mechanism water jacket, and inverter water jacket, where cooling water is distributed and supplied in parallel to each, with specific paths and amounts set based on heat generation and required cooling power, ensuring appropriate cooling without excess or deficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling water is supplied to all components (motor, transmission mechanism, inverter) with equal priority, then all components receive cooling, but the motor may not receive sufficient cooling while other components receive excessive cooling

Engineering Contradiction:
Improvecooling effectivenessVSAvoidcooling water distribution complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent applies local quality by providing different cooling water supply amounts to different components based on their individual heat generation characteristics. The motor, which generates the most heat, receives the largest supply amount, while the transmission mechanism and inverter receive smaller supply amounts. This differentiated approach ensures each component receives appropriate cooling without requiring complex centralized control systems.

Inventive Principle:
Principle #3Local quality

2Reliability

If cooling water supply amount is increased to ensure sufficient cooling, then cooling effectiveness improves, but energy waste and excessive cooling occurs

Engineering Contradiction:
Improvecooling reliabilityVSAvoidcooling energy waste
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies partial action by supplying cooling water in differentiated amounts matched to each component's actual cooling needs. The motor receives a larger supply amount due to higher heat generation, while the transmission mechanism and inverter receive smaller amounts. This prevents both insufficient cooling and excessive cooling, optimizing energy utilization and avoiding waste.

Inventive Principle:
Principle #16Partial or excessive action

3Temperature

If separate cooling systems are provided for each component, then each component receives optimized cooling, but device complexity and space requirements increase

Engineering Contradiction:
Improvecomponent temperature controlVSAvoidcooling system structure
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent merges the cooling water supply system into a unified structure where a single supply source distributes cooling water to multiple components (motor, transmission mechanism, inverter) through a distribution mechanism. This integrated approach provides differentiated cooling control for each component while avoiding the complexity and space requirements of completely separate cooling systems.

Inventive Principle:
Principle #5Merging (Combining)

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

The system effectively cools each component by prioritizing the motor's higher cooling capacity, preventing insufficient cooling while using lower capacity jackets for the transmission mechanism and inverter, thus preventing excessive cooling, thereby enhancing durability and performance.

Implementation Method 1

a motor water jacket configured to cool the motor, a transmission mechanism water jacket configured to cool the first transmission mechanism, an inverter water jacket configured to cool the inverter

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP4707156A1Marine propulsion device
Publication Date: 2026.03.11 SUZUKI MOTOR CORP
  • EP4707156A1 patent drawingFigure 1
  • EP4707156A1 patent drawingFigure 2
  • EP4707156A1 patent drawingFigure 3

AI summary

A marine propulsion device includes a motor, a first transmission mechanism transmitting a rotation of the motor to a drive shaft, a second transmission mechanism transmitting a rotation of the drive shaft to a propeller shaft, an inverter controlling the motor, and a cooling device. The cooling device includes a motor water jacket cooling the motor, a transmission mechanism water jacket cooling the first transmission mechanism, an inverter water jacket cooling the inverter, and a distribution mechanism distributing and suppling a cooling water after flowing in the motor water jacket to the transmission mechanism water jacket and the inverter water jacket in parallel. The distribution mechanism includes a first distribution passage suppling the cooling water after flowing in the motor water jacket to the transmission mechanism water jacket, and a second distribution passage suppling the cooling water after flowing in the motor water jacket to the inverter water jacket.