Electro-Hydraulic Servo-Valve Damping for Limit Cycle Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electro-hydraulic servo-valves (EHSVs) in aircraft face dynamic instability due to limit cycle oscillations (LCO) caused by temperature changes and fluid viscosity variations, leading to inaccurate fluid delivery and potential premature failure, which complicates flight performance and increases weight with current stabilization methods.
Innovation Solution
Incorporating a damper system with a driving member and a driven member that generates damping forces to counter oscillations in the flexure tube and nozzle, along with a second damper and coupler to provide additional damping, allowing for stable operation across varying fluid flow rates and temperatures without increasing the weight of the EHSV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional stabilization methods are used to counter LCO, then stability is improved, but weight increases
Solution Approach 1:
A magnet is introduced as an intermediary component between the flexure tube and the damping mechanism. The magnet couples to the flexure tube and interacts with a stationary magnet array to provide damping forces that counter LCO oscillations, achieving stability without direct mechanical connection that would add weight
Solution Approach 2:
The patent replaces traditional mechanical stabilization methods with a magnetic field-based damping system. The interaction between magnets and the flexure tube creates damping forces through magnetic fields rather than direct mechanical contact, reducing the weight penalty associated with conventional mechanical stabilizers
2Productivity
If fluid flow rate is increased to improve productivity, then LCO oscillations are exacerbated, but higher flow rates are needed for flight performance
Solution Approach 1:
The magnetic damping system provides continuous feedback damping forces that respond to the oscillation state of the flexure tube. As the tube oscillates during high-flow operation, the magnet-stationary magnet interaction generates counteracting forces that dampen the oscillations, enabling stable operation at higher fluid flow rates
Solution Approach 2:
The damping characteristics of the magnetic system can be adjusted by changing parameters such as magnet strength, magnet geometry, and spacing. This allows optimization of the damping effect to match different operating conditions and fluid flow rates, maintaining stability across a range of productivity levels
3Stability of the object's composition
If the EHSV design is modified to reduce LCO, then stability is improved, but mounting geometry complexity increases
Solution Approach 1:
The damping system is segmented into modular components: the magnet array attached to the flexure tube and the stationary magnet array mounted on the valve body. This segmentation allows independent optimization of each component and simplifies the overall mounting geometry, as each magnet array can be designed and positioned separately
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 damper system effectively reduces or eliminates LCO, enhancing the stability and accuracy of fluid delivery to the actuator, allowing for higher fluid flow rates without oscillations, thus improving flight performance while maintaining a standard mounting geometry and minimizing weight.
Implementation Method 1
a damper operatively coupled to the flexure tube. The damper is disposed in the chamber
Implementation Method 2
a first damper, a second damper, and a coupler disposed between the first damper and the second damper
Data Source
AI summary
Electro-hydraulic servo-valves and related methods are disclosed herein. An example electro-hydraulic servo-valve includes an inlet to receive a fluid from a reservoir, a torque motor, a chamber, the fluid to return to the reservoir via the chamber, and a flexure tube coupled to the torque motor. At least a portion of the flexure tube is disposed in the chamber. The flexure tube includes a nozzle to deliver the fluid to an actuator. The example electro-hydraulic servo-valve includes a damper operatively coupled to the flexure tube. The damper is disposed in the chamber.