Rotor Blade Collet Coupling for Centrifugal Load Transfer
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Solution Overview
Problem
Existing rotor assemblies face challenges in efficiently coupling composite rotor blades to metallic bearing races, particularly in maintaining a centrifugal force load path and preventing relative rotation, which affects the durability and maintainability of the rotor assembly.
Innovation Solution
The use of a split collet assembly with circumferentially distributed collet members and an outer sleeve, along with anti-rotation elements, to create a centrifugal force load path between composite rotor blades and metallic bearing races, ensuring secure coupling and allowing for removable rotor blades for inspection and replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a direct coupling between composite rotor blade and metallic bearing race is used, then the structure is simple, but the centrifugal force load path is insufficient leading to potential deformation
Solution Approach 1:
The coupling assembly is segmented into multiple functional components: a collet assembly with segmented collets, a wear ring, and a retaining ring. Each component serves a specific function in managing centrifugal forces, providing wear protection, and enabling maintenance, thereby resolving the contradiction between structural simplicity and load path sufficiency.
Solution Approach 2:
The invention interfaces composite rotor blade material with metallic bearing race material through a specially designed coupling assembly. The wear ring and collet assembly are made of metallic materials that can handle the centrifugal forces, while the composite rotor blade maintains its lightweight properties, creating an effective composite structure that satisfies both strength requirements and weight considerations.
2Ease of repair
If the rotor blade is directly attached to the bearing race, then maintenance is difficult without disassembly, but adding a complex coupling mechanism increases device complexity
Solution Approach 1:
The coupling assembly is designed as a segmented structure with a retaining ring that can be independently removed. This segmentation allows the rotor blade to be accessed and replaced without disassembling the entire rotor hub, significantly improving maintenance accessibility while keeping the overall structure relatively simple.
Solution Approach 2:
The wear ring is extracted as a separate, sacrificial component that can be easily replaced when worn. This extraction principle allows maintenance personnel to replace only the wear ring rather than the entire coupling assembly or rotor blade, simplifying the maintenance process while protecting more critical components.
3Reliability
If expensive components are used throughout the assembly, then durability is improved, but cost increases; if cheaper components are used, then cost decreases but lifespan is reduced
Solution Approach 1:
The wear ring is designed as a cheap, sacrificial component made of metallic material that is intended to wear out and be replaced periodically. By using a less expensive material for this specific component compared to the rotor blade and bearing race, the overall system reliability is improved without significantly increasing cost, as the wear ring protects the more expensive components from wear.
Solution Approach 2:
Different components of the coupling assembly are made from materials with different properties optimized for their specific functions. The wear ring uses a material optimized for wear resistance, while the collet assembly uses materials optimized for handling centrifugal forces. This local optimization of material properties ensures each component contributes maximally to system reliability without unnecessarily increasing overall cost.
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
This configuration enhances the strength and durability of the rotor assembly by increasing the root-to-chord ratio and enables easy maintenance by allowing removable rotor blades, improving the overall performance and longevity of the rotor system.
Implementation Method 1
The outer sleeve maintains the collet members in a circumferential orientation around the bearing race and the rotor blade such that the split collet assembly provides a centrifugal force load path between the rotor blade and the bearing race
Data Source
AI summary
A rotor assembly for generating vehicle thrust. The rotor assembly includes a rotor hub with a plurality of rotor blade assemblies coupled thereto. Each rotor blade assembly includes a metallic bearing race, a composite rotor blade and a split collet assembly. The split collet assembly includes two circumferentially distributed collet members each having an inner inboard conical seat configured to mate with a radially outwardly extending conical feature of the bearing race and an inner outboard conical seat configured to mate with a radially outwardly extending conical feature of the rotor blade. The split collet assembly also includes an outer sleeve having an inner conical surface that mates with outer conical surfaces of the collet members to maintain the collet members in a circumferential orientation around the bearing race and the rotor blade such that the split collet assembly provides a centrifugal force load path therebetween.