Tail Rotor Clevis Assembly With Mechanical Fuse for Torque Spikes
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Solution Overview
Problem
In rotary wing aircraft, component failures in the tail rotor system can introduce additional torque, leading to unpredictable damage to mechanical components, as existing systems do not effectively manage and mitigate such failures.
Innovation Solution
A clevis assembly with a shearing device, featuring a mechanical fuse with a frangible point, which shears under high torque conditions, allowing the piston to spin with the tail rotor and preventing damage to input/feedback linkages, thereby enabling continued control for a safe landing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid mechanical connection is used in the tail rotor system, then structural strength is improved, but the system becomes vulnerable to unpredictable damage from torque spikes during component failure
Solution Approach 1:
The mechanical fuse divides the rigid mechanical connection into segments: a strong outer housing and a weaker frangible point. This segmentation allows the system to maintain overall structural integrity while creating a controlled weak point that can fail predictably to protect other components.
Solution Approach 2:
The mechanical fuse acts as an intermediary element between the piston and the clevis assembly. It mediates the torque transmission, allowing normal operation while providing a controlled failure mode that protects the broader mechanical system from damage during component failures.
2Reliability
If a fail-safe mechanism is added to the tail rotor system, then system reliability under failure conditions is improved, but device complexity increases
Solution Approach 1:
The mechanical fuse is a self-regulating device that automatically responds to torque spikes without requiring external control systems, sensors, or complex mechanisms. The frangible point inherently detects excessive torque through mechanical stress and fails predictably, providing fail-safe functionality through passive mechanical design.
Solution Approach 2:
The mechanical fuse is designed as a simple, inexpensive component with a predetermined limited life or single-use failure mode. Once the frangible point fails, the mechanical fuse performs its protective function and can be replaced, providing reliable fail-safe protection without requiring complex or expensive mechanisms.
3Manufacturing precision
If the shearing device is positioned within the bearing aperture, then localization of breakage is improved, but the device complexity increases due to precise positioning requirements
Solution Approach 1:
The mechanical fuse is integrated with the clevis assembly such that the frangible point is positioned within the bearing aperture. This merging of components eliminates the need for separate positioning mechanisms, as the structural integration itself provides the precise positioning required for controlled breakage localization.
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 solution localizes torque-induced breaks to a predetermined area, reducing unpredictability and allowing limited operation to ensure a safe landing by disconnecting the translating element's output from anti-rotation features while maintaining mechanical input control.
Implementation Method 1
A clevis assembly with a shearing device, featuring a mechanical fuse with a frangible point, which shears under high torque conditions
Data Source
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AI summary
According to an aspect, a clevis assembly includes a shackle having two ends, each end respectively including an aperture, a structure connecting the apertures and housing a bearing, and a shearing device that includes a frangible point and is in operable communication with the bearing, where the shearing device is housed in a hollow portion of the structure.