Shock Strut Pressure Monitoring for Gas Dissolution Servicing
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Solution Overview
Problem
Current methods for monitoring and servicing aircraft landing gear shock struts do not accurately account for gas absorption and desorption, leading to potential imbalances in gas and oil levels, which can affect the strut's performance and functionality.
Innovation Solution
A method and system that measure and calculate the servicing condition of shock struts by determining the number of moles of gas dissolved in the fluid, using temperature and pressure readings before and after takeoff, and considering gas absorption and desorption, without the need for a position sensor, utilizing existing temperature sensors on the aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional shock strut monitoring methods are used without accounting for gas absorption and desorption, then the monitoring system is simpler, but the measurement precision of gas and oil levels deteriorates
Solution Approach 1:
The patent applies parameter changes by monitoring pressure and temperature variations of the shock strut fluid over time, and by calculating the number of moles of gas dissolved in the fluid using thermodynamic relationships. This allows accurate determination of gas and oil levels without adding complex physical sensors, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces direct physical measurement of gas and oil levels with a calculation-based approach using pressure and temperature data. By substituting mechanical level sensors with computational methods that account for gas absorption and desorption, the system achieves high measurement precision while maintaining simplicity
2Reliability
If gas absorption and desorption are not accounted for in shock strut servicing, then the servicing process is simpler, but the reliability of landing gear performance deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring pressure and temperature changes in the shock strut and using this data to calculate the servicing condition. The system provides feedback on whether the shock strut requires servicing with gas or oil, ensuring reliable landing gear performance while keeping the monitoring process integrated into existing systems rather than adding complex external equipment
3Measurement precision
If pressure measurements are taken only at static conditions, then the measurement process is simpler, but the measurement precision of dynamic servicing conditions deteriorates
Solution Approach 1:
The patent applies continuity of useful action by taking pressure measurements at multiple time points (before and after takeoff) rather than a single static measurement. This continuous monitoring approach captures the dynamic behavior of gas absorption and desorption during flight operations, improving servicing condition accuracy without requiring excessively long measurement periods
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 approach provides more accurate measurements of shock strut servicing conditions, ensuring proper gas and oil volumes, thereby maintaining optimal landing gear performance and 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
Implementation Method 3
determining a number of moles of gas dissolved in a fluid
Data Source
AI summary
A method for monitoring a shock strut may comprise measuring a first shock strut pressure, measuring an ambient temperature, measuring a shock strut stroke, measuring a second shock strut pressure, and determining a servicing condition of the shock strut based upon the first shock strut pressure, the ambient temperature, the shock strut stroke, and the second shock strut pressure, wherein the servicing condition indicates whether it is desirable for the shock strut to be serviced with at least one of a liquid and a gas. The first shock strut pressure and the shock strut stroke may be measured before the takeoff event with a weight of an aircraft supported by the shock strut.