Integral Shrink Piston Shock Strut for Hydraulic Wheel Well Retraction
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Solution Overview
Problem
Existing shock struts in aircraft landing gear systems face challenges in efficiently shrinking to fit within the wheel well, particularly in utilizing available aircraft power sources for retraction.
Innovation Solution
The design incorporates a strut cylinder, a strut piston, a shrink piston, and a shrink chamber, where the shrink piston is slidably reciprocable within the strut cylinder, and a vent orifice to manage fluid leakage, allowing the shock strut to shrink using hydraulic fluid from the aircraft system, with mechanical stops and seals to control movement and fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a shock strut uses conventional retraction mechanisms, then it can fit in the wheel well, but it fails to efficiently utilize available aircraft power sources for retraction
Solution Approach 1:
The shock strut system is designed to perform multiple functions: it serves as both a shock absorber during landing and a retractable mechanism during wheel well stowage. The shrink piston and shrink chamber are integrated into the existing shock strut structure, allowing the same hydraulic system to power both shock absorption and retraction operations, thereby efficiently utilizing the aircraft's available hydraulic power sources.
Solution Approach 2:
The invention employs hydraulic fluid from the aircraft system to actuate the shrink piston within the shrink chamber. This hydraulic actuation mechanism directly converts the aircraft's hydraulic power into mechanical motion for retraction, eliminating the need for separate mechanical retraction systems and maximizing energy utilization from the aircraft's existing power sources.
2Volume of moving object
If the shock strut shrinks for wheel well retraction, then it fits in the wheel well, but it complicates the device structure
Solution Approach 1:
The shrink piston is disposed at least partially within the strut cylinder, and the shrink chamber is formed within the existing shock strut structure. This nested arrangement allows the retraction mechanism to be compactly integrated within the shock strut itself, minimizing additional space requirements while achieving the necessary volume reduction for wheel well retraction.
Solution Approach 2:
The invention merges the shrink piston and shrink chamber into the existing shock strut assembly, combining the retraction function with the shock absorption structure. The mechanical stops and seals are integrated into this unified design, reducing the number of separate components and simplifying the overall device structure despite the added retraction capability.
3Stability of the object's composition
If the shock strut uses mechanical stops and seals for movement control, then it maintains structural integrity, but it increases device complexity
Solution Approach 1:
The mechanical stops are designed to automatically engage and disengage based on the position of the shrink piston during retraction and extension cycles. The seals self-regulate fluid containment within the shrink chamber, maintaining structural integrity without requiring external control systems. These components perform their functions autonomously as part of the normal operation cycle, reducing the need for additional control mechanisms.
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 configuration enables effective shrinking and extension of the shock strut using existing aircraft hydraulic power, ensuring efficient retraction into the wheel well while maintaining structural integrity and fluid containment.
Implementation Method 1
the shrink piston compresses into the strut cylinder in response to the strut piston mechanically engaging the shrink piston
Implementation Method 2
a vent orifice to manage fluid leakage, allowing the shock strut to shrink using hydraulic fluid from the aircraft system
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A shock strut (100; 200) may comprise a strut cylinder (110), a strut piston (120) operatively coupled to the strut cylinder, a shrink piston (130) disposed at least partially within the strut cylinder, and a shrink chamber (260) at least partially defined by the shrink piston. The shrink piston may comprise a shrink piston head (232), a sleeve (234) extending from the shrink piston head, and a mechanical stop (236). A hydraulic fluid may be moved into the shrink chamber to compress the shrink piston and the strut piston into the strut cylinder to reduce an overall length of the shock strut.