Variable-Pitch Propeller Hub Design for Efficiency
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Solution Overview
Problem
Conventional controllable pitch propellers face issues with increased hub size, reduced propulsion efficiency, and higher manufacturing costs due to complex hydraulic systems, making them less suitable for low-speed ships, especially when adhering to marine environmental regulations.
Innovation Solution
A controllable pitch propeller design with a hub diameter ratio ranging from 0.170 to 0.200, featuring a diagonal guide slot for the crosshead movement, reduced blade pitch variation range, and a locking mechanism to minimize hydraulic system capacity and hub size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If facilities and equipment for changing blade angle are installed in the hub of a controllable pitch propeller, then the blade pitch can be adjusted according to operating conditions, but the hub size becomes larger than that of a fixed pitch propeller
Solution Approach 1:
The patent divides the hub into multiple segments or layers, allowing the pitch adjustment mechanism to be distributed rather than concentrated in a single large volume. This segmentation enables pitch control functionality while maintaining a more compact overall hub structure.
Solution Approach 2:
The patent employs a nested structure where the pitch adjustment mechanism is integrated within the hub's internal cavity or hollow spaces. The crosshead and blade angle adjustment components are positioned within existing hub volume, effectively nesting the control mechanism inside the hub structure rather than adding external volume.
2Adaptability or versatility
If a controllable pitch propeller is used to vary blade pitch according to operating conditions, then adaptability improves, but propulsion efficiency decreases by 4 to 8% compared to fixed pitch propeller
Solution Approach 1:
The patent implements a dynamic pitch adjustment system where the blade pitch can be continuously varied based on real-time operating conditions. The crosshead mechanism allows smooth transition between pitch angles, enabling the propeller to maintain optimal efficiency across different operating regimes by dynamically adjusting blade angle to match thrust requirements.
Solution Approach 2:
The patent changes the pitch parameter of the propeller blades based on operating conditions such as ship speed, load, and environmental factors. By adjusting the blade pitch parameter dynamically, the propeller maintains high propulsive efficiency across varying operating conditions, reducing energy loss compared to fixed pitch designs.
3Adaptability or versatility
If a controllable pitch propeller is used to meet marine environmental regulations, then operational flexibility improves, but manufacturing cost increases due to complicated processing
Solution Approach 1:
The patent designs the hub structure to serve multiple functions: it provides structural support, contains the pitch adjustment mechanism, and incorporates the crosshead guidance system. This multi-functionality reduces the need for separate components, simplifying manufacturing while maintaining controllable pitch capability.
Solution Approach 2:
The patent employs a self-contained pitch adjustment mechanism where the crosshead and guide slots work together to automatically control blade angle changes without requiring complex external actuation systems. The hydraulic or mechanical actuation system integrates directly with the hub structure, reducing manufacturing complexity while enabling pitch control for environmental regulation compliance.
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 design achieves a smaller hub size, reduced hydraulic pressure requirements, and improved propulsion efficiency, aligning with fixed pitch propeller performance while addressing marine environmental regulations.
Implementation Method 1
the guide slot extends diagonally with respect to a center line of the propulsion shaft such that movement of the pin along the guide slot between a top dead center and a bottom dead center rotates the blade carrier so as to vary the pitch of the blade
Implementation Method 2
the crosshead is movable in a longitudinal direction of the hub
Data Source
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Figure 3A
AI summary
The present invention relates to a variable-pitch propeller capable of changing a blade pitch according to the sailing conditions of a ship and, specifically, to a controllable pitch propeller having an optimal hub-to-tip diameter ratio, the propeller being capable of reducing the size of a hub so as to have a high efficiency that is close to the propulsion efficiency of a fixed pitch propeller (FPP). In order to accomplish the aforementioned objective, the present invention relates a controllable pitch propeller which comprises a hub mounted at the propelling shaft of a ship, and a blade that is mounted at the circumference of the hub and that has a variable pitch, and which is technically characterized by a H/D ratio, of diameter (H) of the propeller and diameter (D) of the hub, of 0.170-0.2.