Aircraft Shock Strut Shrink Using an Accumulator Energy Source
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Solution Overview
Problem
Aircraft landing gear shock strut systems require an independent mechanism to shrink in size for retraction without overloading the utility hydraulic system, as tapping into it decreases system performance.
Innovation Solution
A pneumatic system comprising a pneumatic cylinder, gas piston, hydraulic chamber, and valves that control gas pressure to shrink the shock strut, allowing it to transition between unshrunk and shrunk states without relying solely on the hydraulic system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If power is provided by the aircraft utility hydraulic system to shrink the shock strut, then the shock strut can be shrunk to fit in the wheel well, but the utility hydraulic system load increases and system performance decreases
Solution Approach 1:
The hydraulic system is segmented into a utility hydraulic system and a separate shrink hydraulic system. The shrink hydraulic system with its dedicated pump and accumulator is isolated from the utility system, allowing shock strut shrinkage operations to be performed independently without impacting utility hydraulic system performance.
Solution Approach 2:
The utility hydraulic system is relieved of the multi-function burden by separating the shock strut shrinkage function into an independent system. This allows the utility system to maintain optimal performance for its primary functions while the separate shrink system handles strut retraction.
2Loss of energy
If an independent pneumatic system is used to shrink the shock strut, then the hydraulic system load is reduced and performance is maintained, but the device complexity increases
Solution Approach 1:
A pneumatic accumulator system is implemented as the independent energy source for shock strut shrinkage. The accumulator stores pneumatic energy and releases it to drive the shrink piston, providing an independent mechanism that does not rely on the utility hydraulic system while maintaining a relatively simple structure.
Solution Approach 2:
A pneumatic intermediary system is introduced between the gas source and the hydraulic shrink mechanism. The pneumatic accumulator acts as an intermediary energy storage device that decouples the direct connection between the utility hydraulic system and the shock strut shrinkage function, reducing system complexity while maintaining independence.
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 solution enables efficient shrinking and unshrinking of the shock strut, reducing the load on the hydraulic system and maintaining performance by using a separate pneumatic system to manage the strut's length, thereby enhancing aircraft operations.
Implementation Method 1
a gas piston configured to apply gas pressure to a hydraulic chamber
Implementation Method 2
an accumulator comprising a pneumatic cylinder, a gas piston, and a hydraulic chamber
Data Source
AI summary
Systems and methods for enabling aircraft shock strut shrink are provided. The system may comprise a shock strut comprising a shrink piston, an accumulator comprising a gas piston and a hydraulic chamber, wherein the gas piston is configured to apply gas pressure to the hydraulic chamber, and a first valve in fluid communication with the accumulator. The system may further comprise a second valve, wherein the second valve is in fluid communication with a vent, the pneumatic cylinder, and the gas piston, wherein the first valve is in fluid communication with the hydraulic chamber and the shrink piston.