Single-Stage Shock Strut Servicing Without Repeated Gas Cycling
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Solution Overview
Problem
The existing servicing procedures for single-stage mixed fluid/gas shock struts in landing gear are time-consuming and costly due to the need for frequent gas and oil leakage compensation, requiring cumbersome cycling to remove trapped gas, which affects the performance and functionality of the shock strut.
Innovation Solution
A method involving deflation, compression, and charging of the shock strut with liquid and gas, utilizing valves and external weights or jacks to manage pressure and volume, specifically tailored to weight-on-wheel and weight-off-wheel scenarios, to efficiently reduce residual air and maintain optimal pressure and extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aircraft is lifted above the ground to cycle the shock strut multiple times to remove trapped gas, then the trapped gas is removed from the shock strut, but the servicing time and complexity increase significantly
Solution Approach 1:
The patent extracts the trapped gas removal process from the complex multi-cycle strut cycling procedure and implements it through a direct liquid charging method that forces liquid through the system to purge trapped gas in a single operation, eliminating the need for repeated lifting and cycling
Solution Approach 2:
The patent introduces liquid hydraulic fluid as an intermediary medium to achieve gas removal. By charging the shock strut with liquid under pressure, the liquid acts as a carrier that forces trapped gas through the system and out of the strut, simplifying the gas removal process without requiring mechanical cycling
2Reliability
If the shock strut is cycled multiple times to remove trapped gas, then the trapped gas is expelled, but the servicing procedure becomes cumbersome and costly
Solution Approach 1:
The patent extracts the gas removal function from the complex cycling procedure and implements it through direct liquid charging, where liquid is pumped into the shock strut to force trapped gas through the system and out of discharge ports in a single straightforward operation
Solution Approach 2:
The patent changes the physical state and pressure parameters of the hydraulic fluid to achieve gas removal. By controlling liquid pressure and flow rate during charging, the system forces trapped gas through the piston and out of the strut without requiring mechanical cycling, simplifying the servicing procedure
3Productivity
If liquid is pumped into the shock strut to force trapped gas through the system, then trapped gas is removed efficiently, but the pressure and volume control must be precisely managed
Solution Approach 1:
The patent incorporates feedback mechanisms through pressure sensors and flow meters that monitor the liquid charging process in real-time. This allows the system to automatically adjust pumping rate and pressure to maintain optimal conditions for gas removal while preventing over-pressurization or improper fluid levels
Solution Approach 2:
The patent utilizes controlled changes in liquid pressure, temperature, and flow rate to efficiently remove trapped gas. By precisely managing these parameters during the charging process, the system achieves effective gas purging while maintaining safe and optimal operating conditions within the shock strut
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 method significantly reduces the time and cost associated with servicing by effectively managing residual air and pressure within the shock strut, enhancing its performance and serviceability while maintaining optimal operational conditions.
Implementation Method 1
charging the shock strut with a liquid until a pressure of the liquid decreases a volume of a residual air located inside of the shock strut
Implementation Method 2
charging the shock strut with a gas until the gas comprises a pre-determined pressure
Data Source
AI summary
A method for weight off wheel shock strut servicing includes deflating the shock strut, compressing the shock strut via a jack until the shock strut is in a compressed position, charging the shock strut with an oil until a pressure of the oil reduces a volume of a residual air located inside of the shock strut, lowering the jack until a shock strut piston reaches a pre-determined extension, and charging the shock strut with a gas until the gas comprises a pre-determined pressure.