Variable-Pitch Marine Propeller Layout for Low-Speed Electric Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Marine vessel propulsion devices, particularly outboard motors, suffer from reduced power efficiency in medium and low speed ranges due to fixed propeller blade pitches that are optimized for maximum power source output, leading to inefficiencies with electric motors.
Innovation Solution
Incorporation of a propeller with changeable blade pitches and a pitch change driver mechanism, allowing the propeller shaft and blades to be rotated and pitched independently, optimizing efficiency across various speed ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the propeller blade pitch is fixed for maximum power source output, then the propulsion efficiency is optimized at maximum power, but the power efficiency deteriorates in medium and low speed ranges
Solution Approach 1:
The propeller blade pitch is made dynamically adjustable through a pitch change driver that can vary the pitch angle according to the operating conditions. The pitch angle is changed based on the rotation speed of the propeller shaft, allowing the propeller to adapt to different speed ranges and maintain optimal propulsion efficiency while improving power efficiency across all operating conditions.
Solution Approach 2:
The pitch parameter of the propeller blades is changed according to the rotation speed of the propeller shaft. By adjusting the pitch angle parameter dynamically, the system optimizes the match between the propeller characteristics and the electric motor output characteristics at different operating points, resolving the contradiction between propulsion efficiency and power efficiency.
2Device complexity
If the propeller shaft rotation and blade pitch are coupled, then the structure is simple, but the ability to optimize efficiency across various speed ranges is limited
Solution Approach 1:
The propulsion system is segmented into two independent control functions: propeller shaft rotation (driven by a propeller shaft rotation driver) and blade pitch change (driven by a pitch change driver). This segmentation allows each function to be optimized independently, maintaining structural simplicity while enabling efficient operation across various speed ranges through independent control of rotation and pitch.
Data Source
AI summary
A propulsion device for a marine vessel includes a driving source including at least one electric motor, a propeller including blades with changeable pitches and rotatable around a central axis of a propeller shaft together with the propeller shaft, a propeller shaft rotation driver to transmit a driving force from the driving source to the propeller shaft and rotate the propeller shaft around the central axis, and a pitch change driver to transmit the driving force from the driving source to the blades and change pitches of the blades. The propeller shaft rotation driver includes a first shaft, and the pitch change driver includes a second shaft closer to a bow side of the marine vessel than the first shaft.