Folding Propeller Hub with Polymer Composite and Galvanic Anodes
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Solution Overview
Problem
Folding propellers for boats face issues with corrosion, fouling, and high moment of inertia, which affect their effectiveness and durability, particularly when used in sailboats and multihull yachts.
Innovation Solution
A folding propeller design featuring a hub with pivot pins and lockboxes that form a closed structure to distribute centrifugal forces, allowing for the use of low-tensile strength materials and incorporating galvanic anodes for corrosion protection, along with a polymer hub for reduced weight and inertia.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional folding propeller design is used, then the propeller can be folded to minimize drag and noise, but the moment of inertia remains high and corrosion resistance is insufficient
Solution Approach 1:
The propeller hub is constructed using composite materials specifically designed to provide both corrosion resistance and reduced weight. This allows the hub to maintain structural integrity while having lower moment of inertia compared to traditional metal hubs, directly addressing both corrosion resistance and moment of inertia issues simultaneously
Solution Approach 2:
The invention changes the material parameters of the hub from traditional high-density metals to low-density corrosion-resistant composites. This parameter change reduces the mass distribution of the hub, thereby lowering the moment of inertia while maintaining sufficient strength and corrosion resistance for marine environments
2Strength
If the propeller uses a robust mechanical linkage system, then structural integrity is maintained, but the complexity of the device increases
Solution Approach 1:
The mechanical linkage system is segmented into modular components that can be independently manufactured and assembled. This segmentation allows for simpler individual parts while maintaining overall structural integrity, reducing the complexity of manufacturing and maintenance without compromising the strength requirements
Solution Approach 2:
The mechanical linkage components are designed with multi-functionality, where single parts perform multiple functions such as both structural support and alignment. This reduces the total number of components needed, simplifying the overall device complexity while maintaining robust structural integrity through careful design of each multi-functional element
3Weight of moving object
If low-tensile strength materials are used, then the moment of inertia is reduced, but the ability to take up forces acting on the propeller is compromised
Solution Approach 1:
Composite materials are used to create a hub that combines low density (for reduced moment of inertia) with high strength-to-weight ratio (for force acceptance). The composite structure provides both low tensile strength material properties for weight reduction and sufficient strength through the composite construction to handle operational forces
Solution Approach 2:
Different regions of the hub are designed with different material properties optimized for their specific functions. Areas subject to high forces use composite materials with higher strength characteristics, while other areas use lower density materials for moment of inertia reduction, creating a non-uniform but functionally optimized structure
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 enhances corrosion resistance, reduces fouling, and lowers the propeller's moment of inertia, resulting in a more effective and robust folding propeller that minimizes drag and noise, while maintaining structural integrity and ease of maintenance.
Implementation Method 1
a mechanism, where the mentioned mechanism is arranged for taking up the forces acting on the propeller when operated, and comprises a closed mechanical system
Implementation Method 2
Galvanic corrosion can be limited by using sacrificial anodes that will be corroded instead of the propeller hub and blades
Data Source
AI summary
The present invention discloses a folding propeller (1) for a boat, e.g. for a sailboat or a multihull yacht, where said folding propeller (1) comprises a hub (2) for directly or indirectly fastening at a driveshaft connected to a motor, where said folding propeller (1) further comprises at least three individual blades (3), where each of said blades (3) comprises a blade root (4) arranged to pivot around a separate pivot pin (9), at said hub (2) in order to be either in a first and operative position, where the blade (3) is pointing mainly in a radial direction, or in a second and inoperative position, where the blade (3) is pointing mainly in an axial direction, where said pivot pin (9) comprises a first and second end (20, 21), where said hub (2) comprises a cut out (19) for each of said blade roots (4), and further comprises a set of holes (10) for installing said pivot pins (9).