Air Over Oil Shock Strut Servicing via Sequential Pressurization
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Solution Overview
Problem
Conventional shock strut servicing methods require complex air bleeding procedures and high gas pressures, increasing the complexity and equipment needs for maintaining aircraft landing gear systems.
Innovation Solution
A method for servicing shock struts by pressurizing the gas portion to a lower initial pressure and then increasing the liquid portion pressure until a higher gas pressure is achieved in the sealed fluid chamber, eliminating the need for air bleeding and reducing equipment complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional air bleeding procedure and high gas pressure servicing is used, then the shock strut can be serviced with correct oil volume and gas pressure, but the servicing complexity and equipment requirements increase
Solution Approach 1:
The patent extracts and eliminates the air bleeding procedure from the servicing process by using a sealed fluid chamber that prevents air entrapment. The separated gas-fluid design allows independent servicing of oil and gas components, removing the need for complex air removal procedures while maintaining accurate oil volume and gas pressure.
Solution Approach 2:
The shock strut is divided into separate gas and fluid chambers with independent access ports. This segmentation allows the oil to be serviced at atmospheric pressure through one port while the gas is pressurized separately through another port, eliminating the need for high-pressure simultaneous servicing and complex air bleeding equipment.
2Stress or pressure
If high gas servicing pressure is used, then the gas chamber can be pressurized to desired operating pressure, but the equipment complexity and safety requirements increase
Solution Approach 1:
The patent implements preliminary action by first filling the shock strut with the correct oil volume at atmospheric pressure while the chamber is open to atmosphere. Only after the oil is in place does the procedure close the fluid access port and then pressurize the gas chamber. This sequence prevents air entrapment and allows simple atmospheric filling equipment to be used instead of high-pressure filling equipment.
Solution Approach 2:
The sealed fluid chamber acts as an intermediary that separates the oil filling process from the gas pressurization process. During oil filling, the chamber is open to atmosphere serving as a pressure equalization medium. During gas pressurization, the sealed chamber contains the oil while independent gas pressure is applied, eliminating the need for complex high-pressure simultaneous servicing equipment.
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 approach simplifies the servicing process, reduces equipment requirements, and allows for accurate temperature compensation, enabling shock strut performance across a wider temperature range without the need for high gas pressures.
Implementation Method 1
pressurizing the gas portion to a first servicing gas pressure
Implementation Method 2
pressurizing the liquid portion until a second servicing gas pressure is achieved in the gas portion. The liquid of liquid portion may comprise an oil. The liquid portion may comprise a liquid valve, and the step of pressuring the liquid portion may comprise pumping oil into the sealed fluid chamber
Data Source
AI summary
The present disclosure includes methods for servicing shock struts. Such shock struts may be “air over oil” type, having a gas portion and a liquid portion of a sealed fluid chamber. Methods in accordance with the disclosure include pressurizing the gas portion to a first pressure, then pressurizing the liquid portion until a final pressure is achieved in the gas portion.