Variable-Pitch Marine Propulsion for Electric Motor Efficiency
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Solution Overview
Problem
Marine vessel propulsion devices, particularly outboard motors, suffer from reduced propulsion efficiency in medium and low speed ranges due to fixed propeller blade pitches designed for maximum power output, leading to deteriorated power efficiency of electric motors.
Innovation Solution
A propulsion device with a changeable propeller blade pitch system, utilizing a propeller shaft rotation drive unit and a pitch change drive unit, driven by multiple electric motors, allowing adjustable blade pitches to optimize efficiency across various speed ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the propeller blade pitch is designed for maximum power output, then high speed performance is improved, but propulsion efficiency deteriorates in medium and low speed ranges
Solution Approach 1:
The patent implements a variable pitch propeller system where the blade pitch can be dynamically adjusted based on operating conditions. The pitch change drive unit allows the propeller blades to change their angle of attack, enabling the system to optimize propulsion efficiency across different speed ranges while maintaining the capability for maximum power output when needed.
2Power
If the electric motor operates at high rotation speed, then power output is improved, but power efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts the propeller blade pitch to match the operating speed range, allowing the electric motor to operate more efficiently across varying loads. By optimizing the blade pitch for current operating conditions, the system maintains better power efficiency even when the motor operates at different rotation speeds.
3Use of energy by moving object
If a transmission is added to suppress electric motor rotation during high-speed operation, then power efficiency is improved, but device complexity increases
Solution Approach 1:
Instead of adding a transmission system, the patent changes the propeller blade pitch parameter to optimize efficiency. This approach achieves the goal of improving power efficiency during high-speed operation without introducing complex transmission mechanisms, maintaining system simplicity while achieving the desired performance improvement.
Data Source
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AI summary
A propulsion device for a marine vessel that is able to improve the power efficiency of an electric motor is provided. The propulsion device for the marine vessel that propels the marine vessel, includes a driving source including at least one electric motor, a propeller that includes a plurality of blades whose pitches are changeable and rotates around a central axis of a propeller shaft together with the propeller shaft, a propeller shaft rotation drive unit that transmits a driving force from the driving source to the propeller shaft and rotates the propeller shaft around the central axis, and a pitch change drive unit that transmits the driving force from the driving source to the respective blades and changes pitches of the respective blades. The propeller shaft rotation drive unit includes a first shaft. The pitch change drive unit includes a second shaft disposed closer to a bow side of the marine vessel than the first shaft.