Ram Air Turbine Actuator Can Pivoting for Seal Integrity
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Solution Overview
Problem
The existing ram air turbine (RAT) actuator designs face issues with fluid leakage and misalignment due to the lack of flexibility in the nose and cylinder assembly, leading to potential fluid loss and vacuum creation during deployment, especially with increased return pressure in modern aircraft systems.
Innovation Solution
A design where a can surrounds the cylinder and piston rod, allowing radial pivoting relative to the housing, providing a flexible seal and maintaining concentricity, and a vented cavity to prevent fluid entry and collect any leakage, reducing the need for aircraft fluid makeup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the nose is fixed relative to the housing and the cylinder is fixed relative to the nose, then structural stability is improved, but misalignment and fluid leakage occur during deployment
Solution Approach 1:
The can is designed to pivot dynamically relative to the housing during actuator deployment. This dynamic adjustment allows the can to maintain proper alignment with the cylinder despite movement and pressure changes, preventing misalignment-induced leakage while preserving structural stability.
Solution Approach 2:
The system changes the operational parameters of the can from fixed to movable, allowing radial pivoting. This parameter change enables the sealing surface to adapt to pressure-induced deformations and alignment shifts, maintaining seal integrity under varying deployment conditions.
2Loss of substance
If check valves are installed upstream of the RAT to prevent hydraulic oil loss, then fluid loss prevention is improved, but vacuum creation and fluid leakage occur during deployment
Solution Approach 1:
The pivotable can design allows the sealing interface to adapt dynamically during deployment, accommodating pressure changes and vacuum conditions without creating leakage paths. This maintains seal integrity even when check valves create vacuum conditions during fluid draw.
3Stress or pressure
If return pressure is increased on recent aircraft designs, then system pressure capability is improved, but fluid leakage risk increases
Solution Approach 1:
The can is designed to change its operational state under pressure, pivoting radially to maintain proper sealing alignment. This parameter change allows the system to accommodate increased return pressure while preventing leakage through adaptive realignment of the sealing surfaces.
Data Source
AI summary
An actuator for a ram air turbine includes a housing that supports a piston rod arranged in a cylinder. The piston rod and the cylinder are slideably moveable relative to one another between retracted and deployed positions. A can surrounds the cylinder and is loosely fixed relative to the housing. The can is permitted to pivot relative to the housing and cylinder relative to the cylinder in a radial direction during operation. In operation, the ram air turbine is deployed by initiating a deploy sequence. The piston rod and the cylinder are extended relative to one another to the deployed position. The method includes pivoting a can that surrounds the cylinder and the piston rod.