Free-Floating Washer Orifice Control for Oleo Strut Rebound Damping
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Solution Overview
Problem
Existing rebound damping systems in landing gears lack effective control over fluid flow during extension and compression phases, leading to inadequate damping forces and potential latent failures due to reliance on springs or elastomers that wear out over time.
Innovation Solution
A free-floating washer is positioned adjacent an orifice plate within the oleo strut, which covers orifices during extension to increase damping force by restricting fluid flow and moves away during compression to allow flow, modifying the flow area and characteristics to control damping forces without the need for springs or elastomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a free-floating washer is used to control fluid flow during extension, then rebound damping force is increased, but the complexity of the damping system increases
Solution Approach 1:
The free-floating washer is designed to automatically position itself based on fluid pressure without requiring external control mechanisms. During extension, fluid pressure pushes the washer against the orifice plate to restrict flow and increase damping. During compression, the washer moves away from the orifice plate to allow flow. This self-regulating mechanism provides the desired rebound damping control while avoiding complex actuation systems.
Solution Approach 2:
The free-floating washer acts as an intermediary element between the fluid pressure and the orifice plate. It mediates the fluid flow control by positioning itself in response to pressure differential, thereby controlling the effective orifice area. This intermediary mechanism provides a simple yet effective way to achieve variable damping without direct mechanical linkage or complex control systems.
2Force
If springs or elastomers are used for rebound damping, then damping force is provided, but reliability decreases due to wear over time
Solution Approach 1:
The invention replaces traditional mechanical spring or elastomer-based damping systems with a fluid-based damping mechanism. Instead of relying on elastic deformation of materials that wear out, the system uses hydraulic fluid flow through variable orifice areas controlled by the free-floating washer. This substitution eliminates the wear associated with elastic materials while maintaining the damping force function.
Solution Approach 2:
The rebound damping is achieved through hydraulic principles rather than mechanical elasticity. Fluid must pass through the orifice plate and around the free-floating washer, creating pressure-dependent flow resistance that provides damping force. This hydraulic approach replaces wear-prone elastic materials with a wear-free fluid system, significantly improving reliability.
3Force
If fluid flow is restricted during extension, then damping force increases, but fluid flow resistance increases
Solution Approach 1:
The system dynamically adjusts the orifice area through the movement of the free-floating washer based on the direction of motion. During extension, the washer is pushed against the orifice plate to reduce the effective area and increase damping force. During compression, the washer moves away to increase the effective area and reduce flow resistance. This dynamic adaptation allows the system to optimize damping force while minimizing unnecessary energy loss in each direction.
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 provides enhanced rebound damping with increased damping force during extension, reducing the speed of landing gear extension while minimizing the risk of latent failures and wear, by dynamically controlling fluid flow through the oleo strut.
Implementation Method 1
During extension of the oleo strut, fluid flow pushes the free-floating washer against the orifice plate, which covers a portion of the fluid path to prevent fluid flow for increased damping
Implementation Method 2
During compression of the oleo strut, fluid pushes the free-floating washer away from the orifice plate allowing fluid flow through the fluid path
Data Source
AI summary
An oleo strut includes an outer cylinder forming a first fluid chamber and an inner cylinder forming a second fluid chamber. The inner cylinder is adapted for sliding concentrically within the outer cylinder in a longitudinal direction. An orifice plate, which is located within the inner cylinder, has holes for fluidly coupling the first fluid chamber with the second fluid chamber. A free-floating washer is constrained in a slot of the orifice plate adjacent the holes and is adapted to move in the longitudinal direction for alternatively blocking and unblocking at least a portion of the holes. During compression of the oleo strut, fluid pushes the washer away from the holes for reducing resistance to fluid flow. During extension of the oleo strut, fluid pushes the washer against the orifice plate covering at least a portion of the holes, which increases the damping force and reduces the extension speed.