Dual-Stage Shock Strut Servicing With Temperature-Based Gas Charging
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Solution Overview
Problem
Existing methods for servicing shock struts in aircraft landing gear do not efficiently maintain optimal internal gas and oil levels across varying temperatures, leading to suboptimal performance and extended servicing times.
Innovation Solution
A method for servicing dual-stage, separated gas/fluid shock struts involves charging secondary and primary gas chambers with compressed gas and pumping oil to match specific pressure and extension curves, ensuring optimal gas and oil levels regardless of temperature, using reference charts and tables for precise pressure settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional shock strut servicing methods are used, then servicing can be completed with basic equipment, but servicing time is extended and optimal gas/oil levels cannot be maintained across varying temperatures
Solution Approach 1:
The method performs preliminary actions by pre-determining the target pressure and extension values based on temperature before actual servicing. The servicing chart is prepared in advance, containing pre-calculated optimal parameters for different temperatures, allowing technicians to quickly reference and achieve correct gas chamber pressure and oil level without trial and error during the servicing process.
Solution Approach 2:
The invention changes parameters by using temperature as the key variable to determine optimal servicing parameters. The servicing chart provides different target pressure and extension values based on temperature conditions, allowing the servicing process to adapt to varying thermal environments. This parameter-based approach replaces fixed servicing procedures with dynamic, condition-specific parameters.
2Measurement precision
If traditional servicing methods are used, then equipment complexity is low, but measurement precision and manufacturing precision of gas/oil levels deteriorate
Solution Approach 1:
The servicing chart acts as an intermediary tool that translates complex thermodynamic relationships into simple, actionable parameters. Instead of requiring technicians to understand complex gas laws and temperature-pressure relationships, the chart provides pre-calculated target values that bridge the gap between theoretical precision requirements and practical servicing capabilities.
Solution Approach 2:
The optimal pressure and extension values are pre-calculated and stored in the servicing chart before servicing begins. This preliminary computation of precise parameters eliminates the need for complex real-time measurements and calculations during servicing, achieving high measurement precision through pre-determined reference values rather than sophisticated measurement equipment.
3Duration of action of moving object
If traditional servicing methods are used, then procedures are simpler, but shock strut cycling and bleeding procedures are extended
Solution Approach 1:
The invention replaces mechanical trial-and-error cycling and bleeding procedures with a reference-based systematic approach. Instead of repeatedly compressing and extending the shock strut to approximate correct levels, or performing lengthy bleeding operations to remove excess oil, the method uses the servicing chart to directly determine target parameters, substituting mechanical iteration with informational guidance.
Solution Approach 2:
The servicing chart provides feedback by establishing clear target pressure and extension values based on temperature. During servicing, technicians compare actual measurements against these predetermined targets, creating a closed-loop process that quickly converges on optimal levels without requiring extended cycling or bleeding procedures.
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 allows for more efficient and time-effective servicing of shock struts, minimizing bleeding procedures and shock strut cycling, while maintaining optimal oil and gas levels across a range of temperatures, ensuring consistent landing gear functionality.
Implementation Method 1
The gas acts as an energy storage device, similar to a spring, so that upon termination of a compressing force the shock strut returns to its original length
Implementation Method 2
Shock struts also dissipate energy by passing the oil through the orifice so that as the shock absorber is compressed or extended, its rate of motion is limited by the damping action from the interaction of the orifice and the oil
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method for servicing a dual-stage, separated gas/fluid shock strut (100) may comprise measuring a servicing temperature, charging a secondary gas chamber (140) with compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature, pumping oil into the shock strut (100), and charging a primary gas chamber (130) with compressed gas.