Multirod Fluid Actuator Control for Low-Leakage Aircraft Surfaces
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Solution Overview
Problem
Current fluid actuator arrangements in aircraft control systems suffer from high energy consumption, weight, and heat generation due to large cylinder volumes and leakage issues, leading to inefficient energy use and increased drag, especially in flight control surfaces.
Innovation Solution
A multirod fluid actuator arrangement with a control unit that manages the motion of piston rods through a combination of first, second, and third multirod actuators, utilizing fluid supply systems with accumulator tanks to minimize energy consumption by shutting off motors during loitering modes and using fewer complex control valves, allowing for efficient fluid distribution and reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If large cylinder chamber volumes are used to provide long strokes, then the actuator can achieve required displacement, but the weight and energy consumption increase significantly
Solution Approach 1:
The actuator is divided into multiple independent piston rods (first, second, and third piston rods) that can be controlled separately. Each piston rod has its own control valve, allowing selective actuation. This segmentation enables the system to achieve long effective stroke through coordinated operation of multiple shorter-stroke pistons without requiring a single large-volume cylinder chamber, thereby reducing overall weight while maintaining required displacement capability.
2Ease of operation
If continuous and adjustable control valves are used for continuous piston motion, then precise control is achieved, but internal fluid leakage occurs between pressure and return sides
Solution Approach 1:
The control system uses on/off valves that switch between discrete states rather than continuous adjustment. The multirod actuator achieves continuous motion through periodic actuation sequences where piston rods are activated in alternating patterns (e.g., first rod extends while second retracts, then they swap roles). This periodic switching eliminates internal leakage associated with continuous adjustable valves while maintaining effective continuous control through coordinated discrete actions.
3Reliability
If hydraulic fluid is continuously pressurized to maintain piston balance, then the actuator remains ready for operation, but a major part of energy is consumed
Solution Approach 1:
The system uses accumulators to pre-store hydraulic fluid under pressure before it is needed. When actuation is required, the stored pressurized fluid is rapidly discharged to the active piston rods. This preliminary action eliminates the need for continuous pump operation and maintains actuator readiness without the ongoing energy consumption of continuous pressurization, as the accumulators can quickly replenish pressure between demand cycles.
4Reliability
If multiple piston rods are actuated simultaneously for redundant control, then flight safety is improved, but the system complexity and fluid distribution requirements increase
Solution Approach 1:
The control system uses a universal valve assembly design where each piston rod shares the same type of on/off valve and control mechanism. The valve assembly can be configured to direct pressurized fluid to any combination of piston rods through standardized ports and passages. This multi-functional design achieves redundant control of multiple piston rods while minimizing system complexity, as the same valve hardware serves multiple functions and can be controlled through a unified control interface.
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 solution results in a lightweight, energy-efficient aircraft control surface actuator system with reduced drag, enabling longer missions with lower fuel consumption and maintaining flight stability even in case of fluid leakage or pump failure, while eliminating internal fluid leakage and heat generation in the wing.
Implementation Method 1
a fluid supply system coupled to the first and second piston bodies for pressurizing the first and second piston bodies to move the first and second piston rods in the first direction
Implementation Method 2
The first and second engagement devices are configured to clamp around the first and second piston rods, respectively
Implementation Method 3
The first engagement device is configured to transfer motion of the first piston body to the first piston rod
Data Source
AI summary
A method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.