Dual-Stage Shock Strut Servicing With Temperature-Based Pressure Charging
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Solution Overview
Problem
The functionality and performance of landing gear shock struts depend on internal gas and oil levels, which are affected by temperature, making it challenging to maintain optimal servicing conditions across varying ambient temperatures without extensive bleeding procedures and shock strut cycling.
Innovation Solution
A method for servicing dual-stage, mixed gas/fluid shock struts involves measuring the servicing temperature, charging a secondary gas chamber with compressed gas, pumping oil into the primary chamber, and adjusting pressures to match reference curves, allowing for efficient extension and retraction while maintaining optimal gas and oil levels, regardless of temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shock strut servicing methods are used, then gas and oil levels can be maintained, but extensive bleeding procedures and shock strut cycling are required, increasing service time and complexity
Solution Approach 1:
The patent applies preliminary action by pre-charging the secondary gas chamber to a specific pressure corresponding to the servicing temperature before servicing the shock strut. This pre-preparation eliminates the need for extensive bleeding procedures and multiple cycling operations during the actual servicing process, significantly reducing service time while ensuring accurate gas and oil level maintenance.
2Reliability
If traditional shock strut servicing methods are used, then gas and oil levels can be maintained, but extensive bleeding procedures and shock strut cycling are required, increasing service complexity
Solution Approach 1:
By pre-charging the secondary gas chamber to the temperature-corresponding pressure before servicing, the patent eliminates complex bleeding procedures and multiple cycling operations. This preliminary preparation simplifies the servicing procedure to a straightforward process of pumping oil into the primary chamber, thereby reducing service complexity while maintaining reliable gas and oil level control.
Solution Approach 2:
The patent replaces complex mechanical bleeding procedures and iterative cycling operations with a pressure-based system. By establishing the secondary gas chamber pressure corresponding to the servicing temperature, the system uses pressure equilibrium principles to automatically control oil and gas levels, substituting mechanical complexity with a more elegant pressure-based control mechanism.
3Productivity
If shock strut servicing is performed without temperature compensation, then servicing can be performed quickly, but optimal gas and oil levels cannot be maintained across varying ambient temperatures
Solution Approach 1:
The patent applies parameter changes by adjusting the secondary gas chamber pressure based on the servicing temperature. Different temperatures correspond to different optimal pressures in the secondary chamber, which in turn determine the correct oil levels in the primary chamber. This temperature-dependent pressure adjustment ensures optimal gas and oil levels are maintained across varying ambient temperatures while keeping the servicing process efficient and straightforward.
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 enables more efficient servicing by minimizing shock strut cycling and bleeding, ensuring optimal gas and oil levels across a range of temperatures, thus improving the reliability and efficiency of landing gear operations.
Implementation Method 1
charging a secondary gas chamber with a first quantity of compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature
Implementation Method 2
a secondary chamber pressure corresponds to the servicing temperature
Implementation Method 3
charging the primary chamber with a second quantity of compressed gas
Implementation Method 4
pumping oil into a primary chamber of the dual-stage, mixed gas/fluid shock strut, wherein the dual-stage, mixed gas/fluid shock strut extends in response to the oil being pumped into the primary chamber
Implementation Method 5
pumping oil into a primary chamber
Implementation Method 6
a volume of oil is metered through an orifice. 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. 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
AI summary
A method for servicing a dual-stage, mixed gas/fluid shock strut may comprise measuring a servicing temperature, charging a secondary gas chamber with compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature, pumping oil into a primary chamber of the shock strut, and charging the primary chamber with compressed gas.