Ram Air Turbine Actuator Relief Valve for Downlock Pin Protection
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Solution Overview
Problem
Existing ram air turbine stowage systems risk damage to components when operators fail to retract the downlock pin before restowing, due to the actuator assembly exerting force against the pin and strut, leading to potential damage during the restowage process.
Innovation Solution
The actuator assembly incorporates a low-pressure relief valve and relief outlet positioned within the housing, which activates when the downlock pin is engaged, redirecting hydraulic fluid pressure to prevent movement of the actuator rod and piston, thereby preventing damage to the downlock pin and strut, and allowing normal restowage when the pin is retracted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the actuator assembly exerts full hydraulic force during restowage, then the restowage speed and efficiency are improved, but damage occurs to the downlock pin and strut when the pin is not retracted
Solution Approach 1:
The relief outlet is positioned to activate before the piston reaches the end of its stroke, preliminarily relieving hydraulic pressure when the downlock pin engagement is detected, preventing damage before it occurs
Solution Approach 2:
The relief outlet acts as an intermediary mechanism between the hydraulic system and the mechanical components, providing a pressure relief path that protects the downlock pin and strut from excessive forces
2Object-affected harmful factors
If the relief outlet is positioned early in the piston stroke, then protection against downlock pin damage is improved, but the restowage time increases due to prolonged pressure relief
Solution Approach 1:
The relief outlet is positioned at a specific location within the housing that corresponds to a precise position in the piston stroke, providing protection only in the critical zone where downlock pin engagement occurs, rather than throughout the entire stroke
3Object-affected harmful factors
If the relief outlet is positioned at less than 20 percent of the piston stroke, then protection against component damage is maximized, but the restowage cycle time increases
Solution Approach 1:
The system changes the hydraulic pressure parameter dynamically by providing a relief path when pressure exceeds safe levels for the downlock pin, while maintaining full pressure for the remainder of the stroke to ensure efficient restowage
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 effectively prevents damage to the downlock pin and associated components by limiting hydraulic pressure when the downlock pin is not retracted, while enabling successful restowage of the ram air turbine without adding significant weight or complexity to the system.
Implementation Method 1
The pressure relief valve may be activated by a pressure differential between the first and second cavity equal to or less than 689 kPa (100 psid)
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An actuator assembly for stowing a ram air turbine includes a housing 32, an internal cavity within the housing configured to partially contain a pressurized fluid, a fluid inlet port 14 connecting a first opening on an outer surface of the housing to the internal cavity, a fluid outlet port 44 connecting a second opening on the outer surface of the housing to the internal cavity, and a pressure relief channel 48 having a relief inlet and a relief outlet. The relief outlet is in fluid communication with the internal cavity and a distance between the fluid inlet port and the relief outlet is less than half a distance between the fluid inlet port and fluid outlet port.