Fixed-Pitch Propeller Hub With High-Strength Retention Plates
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Solution Overview
Problem
Existing fixed-pitch bolted propellers face challenges in securing blades robustly to the hub with sufficient structural integrity, requiring numerous high-strength bolts due to the material strength disparity between bolts and hub/blade materials, leading to increased complexity and maintenance burdens.
Innovation Solution
The design incorporates high-strength retention plates or threaded inserts with high-strength bolts, reducing the number of bolts needed and enhancing fatigue strength, while allowing for external bolt access for easier maintenance and underwater servicing, and utilizing materials like nickel aluminum bronze or stainless steel for the hub and blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high strength bolts are threaded into the blade or hub body to secure propeller blades, then structural integrity is achieved, but the number of bolts and/or their size must be increased due to material strength disparity
Solution Approach 1:
The patent applies composite materials by combining high-strength steel bolts with stainless steel or nickel aluminum bronze hub and blade components. This material composite approach allows the high-strength bolts to provide sufficient structural integrity while reducing the total number of bolts needed compared to using only lower-strength materials throughout the assembly.
Solution Approach 2:
The patent implements local quality by using high-strength steel bolts specifically at the critical connection points where blades attach to the hub, while the hub and blade bodies themselves are made of stainless steel or nickel aluminum bronze. This localized application of high-strength material optimizes the strength-to-complexity ratio by concentrating strength where most needed.
2Strength
If numerous high strength bolts are used to secure blades to the hub, then sufficient structural integrity is achieved, but maintenance burden and complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the fastening system into distinct high-strength steel bolts and stainless steel/Nickel aluminum bronze hub-blade components. This segmentation allows for easier maintenance and replacement of individual bolts without affecting the entire propeller assembly, reducing the maintenance burden compared to integrated fastening systems.
3Strength
If high strength bolts are used to secure blades robustly to the hub, then structural integrity is achieved, but the size and number of bolts must be increased
Solution Approach 1:
The patent uses composite materials combining high-strength steel bolts with stainless steel or nickel aluminum bronze hub and blade components. This material combination achieves the required structural integrity with fewer and smaller bolts compared to using only lower-strength materials, thereby reducing the total mass of the fastening system.
Solution Approach 2:
The patent applies parameter changes by utilizing high-strength steel bolts with superior tensile and yield strength properties compared to standard bolts. This parameter change in material strength allows for reduction in bolt size and number while maintaining the required structural integrity, thus reducing the overall weight of the fastening system.
Data Source
AI summary
A fixed-pitch bolted propeller includes: a hollow hub body configured for attachment to a rotatable shaft, where the hollow hub body includes connection ports circumferentially distributed on an outer surface thereof; propeller blades, where each of the propeller blades terminates in a blade flange attached to the outer surface of the hollow hub body at one of the connection ports; retention plates positioned on an inner surface of the hollow hub body adjacent to the connection ports, where the retention plates include threaded recesses; and bolts extending through bolt holes in the blade flanges and the connection ports and into the threaded recesses of the retention plates to secure the propeller blades to the hollow hub body. The retention plates and the bolts each comprise a material having a tensile strength of at least about 125 ksi and/or a fatigue endurance limit of at least about 50 ksi.