Propeller Blade Redundant Anchoring for Rupture Safety
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Solution Overview
Problem
Existing propeller blades face challenges with secure fixation, ease of inspection, and high maintenance costs, particularly due to the risk of ejection during blade shank or anchoring bush rupture, and the need for complex and costly adaptations to the hub.
Innovation Solution
A propeller blade design featuring a separate safety device with a safety element that provides radial anchoring in case of rupture, allowing for easy inspection and replacement without hub dismantling, and a compact, lightweight, and robust construction with adjustable pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blade shank with anchoring bush is used to fix the blade in the hub, then the blade can be securely anchored and forces can be transmitted, but inspection of the fixing assembly requires dismantling the blade from the hub and the anchoring bush, making inspection difficult and time-consuming
Solution Approach 1:
The invention divides the blade assembly into separable components: the blade can be detached from the hub while the anchoring bush remains in the hub. This segmentation allows inspection of the anchoring bush and its fixing to the hub without requiring removal of the entire blade assembly, making inspection easier while maintaining secure anchoring.
Solution Approach 2:
The anchoring bush serves as an intermediary component between the blade shank and the hub. It can be independently removed and inspected from the hub side, allowing verification of the anchoring fixing without dismantling the blade itself. This intermediary structure enables easy inspection while maintaining the structural integrity of the blade-hub connection.
2Power
If the blade shank and anchoring bush are subjected to high stresses and vibrations during operation, then the blade can transmit forces effectively, but the risk of rupture increases, which could lead to blade ejection and serious consequences
Solution Approach 1:
The invention implements a retaining device that acts as a safety backup before blade rupture can cause catastrophic failure. The retaining device includes a retaining element anchored in the hub and a retaining member on the blade shank that can engage to prevent blade ejection in case the primary anchoring fails due to rupture under high stress and vibration conditions.
Solution Approach 2:
The retaining device changes the safety parameters of the blade assembly by adding a secondary retention mechanism. This device modifies the failure mode from complete blade ejection to controlled retention, effectively changing the reliability parameter by providing a backup system that activates only under extreme stress conditions when rupture occurs.
3Reliability
If a retaining device is anchored in both the blade and the hub to prevent blade ejection, then blade safety is improved, but the device becomes heavy and expensive, and requires adaptation of the hub of each propeller
Solution Approach 1:
The invention extracts the retaining element from the blade structure and places it solely in the hub. The retaining member remains on the blade shank, but the complex anchored retaining element is taken out and integrated into the hub structure. This allows the hub to provide the retained function for multiple blades without requiring complex modifications to each blade individually, reducing overall device complexity while maintaining safety.
Solution Approach 2:
The hub-integrated retaining element serves multiple blades simultaneously, providing a universal solution. Instead of requiring individual retaining devices for each blade-blade shank assembly, the hub contains retaining elements that can engage with retaining members on multiple different blades, reducing the overall complexity and number of components needed while maintaining blade retention safety across the entire propeller system.
4Strength
If the blade shank assembly is made robust to withstand high stresses, then the blade can be securely retained, but the blade becomes heavier and more difficult to replace
Solution Approach 1:
The invention segments the blade assembly into the blade, blade shank, and anchoring bush as separable components. The blade shank assembly is designed to be detachable from the hub by removing the anchoring bush, allowing the blade to be replaced without replacing the entire robust shank assembly. This segmentation maintains the strength of the shank assembly while enabling easy blade replacement by separating the replaceable blade from the durable shank and anchoring components.
Data Source
AI summary
A propeller blade includes an aerodynamic portion and a blade shank, a hub assembly (28, 32) which provides anchoring in a hub, a blade shank assembly of the aerodynamic portion, a safety device including a safety element (24) which extends from a distal assembly in the aerodynamic portion to a proximal assembly (26, 27) in the blade shank and which is adapted to be able to anchor the aerodynamic portion in the blade shank, wherein the blade shank assembly is anchored radially outside the hub assembly, the proximal assembly is anchored to the blade shank radially inside the hub assembly, and the distal assembly and/or the proximal assembly has a strictly positive radial clearance (30).