Fly-By-Wire Actuator Valve Redundancy Without Force Fights
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In fly-by-wire aircraft systems, multi-stage redundant hydraulic actuators often experience force fights due to unsynchronized control valves, leading to increased stresses and the need for more robust designs that result in weight and cost increments.
Innovation Solution
The actuator system incorporates a control valve system with mechanically linked direct drive valves and an electro-hydraulic servovalve as a backup, eliminating synchronization requirements and providing redundant motor and solenoid valve configurations to manage actuation forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-stage redundant hydraulic actuators are used in FBW FCS applications, then safety and redundancy are improved, but force fight conditions occur that require larger actuators than necessary
Solution Approach 1:
The patent replaces the traditional mechanical synchronization approach with an electronic control system. A control valve system with electronically controlled valves (ECVs) and direct drive valves (DDVs) is used instead of purely mechanical linkages, allowing precise electronic coordination of multiple actuator stages to eliminate force fights while maintaining redundancy.
Solution Approach 2:
The patent implements feedback control through position sensors and control valves that continuously monitor and adjust actuator positions. The control system uses feedback signals to synchronize opposing hydraulic stages, preventing differential pressure buildup and force fight conditions while maintaining smaller, more efficient actuator designs.
2Reliability
If control valves of opposing hydraulic stages are not synced, then force build up occurs in chambers, but synchronization is difficult to achieve
Solution Approach 1:
The patent replaces complex mechanical synchronization mechanisms with electronic control. Electronically controlled valves and direct drive valves are coordinated through electronic control systems, simplifying the synchronization process while improving control precision and eliminating the need for complex mechanical linkages between opposing stages.
Solution Approach 2:
The control valve system is designed to perform multiple functions: normal operation control, synchronization of opposing stages, and force fight prevention. The same control valves and electronic control system handle all these functions, reducing overall system complexity compared to having separate dedicated systems for each function.
3Strength
If actuators are designed to be more robust to withstand increased stresses, then strength is improved, but weight and cost increase
Solution Approach 1:
The patent uses feedback control to maintain precise synchronization of opposing hydraulic stages, preventing differential pressure buildup and force fights. This eliminates the need for oversized, robust actuators, allowing the use of smaller, lighter actuators that would otherwise be insufficient to handle potential stress conditions.
Solution Approach 2:
The patent replaces mechanical robustness (thicker walls, larger components) with electronic control precision. The electronically controlled valve system provides precise coordination that prevents force fights, allowing the use of lighter actuators with thinner chamber walls while maintaining the ability to withstand operational stresses.
4Reliability
If redundant FBW systems are employed, then safety is improved, but cost increases
Solution Approach 1:
The patent merges multiple control functions into a single integrated control valve system. The same control valves and electronic control system manage both primary and backup actuator stages, coordinating them to work together rather than as separate redundant systems. This reduces overall system complexity and cost while maintaining safety through coordinated redundancy.
Solution Approach 2:
The control valve system is designed with universal functionality to control multiple actuator stages simultaneously. The same electronic control system and valve architecture handle both primary and backup systems, eliminating the need for completely separate redundant control systems and reducing overall cost and complexity.
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 configuration eliminates force fights by ensuring continuous actuation control without position transients, even in case of hydraulic pressure loss or motor failure, thereby reducing stress and weight while maintaining safety and redundancy.
Implementation Method 1
a first direct drive valve (DDV) mechanically connected to a second DDV
Implementation Method 2
The backup valve system includes one of an electro-hydraulic servovalve (EHSV) and a DDV
Implementation Method 3
a first solenoid valve operatively connected to the first bypass valve and a second solenoid valve operatively connected to the second bypass valve
Data Source
AI summary
An actuator system for an aircraft includes an actuator, and a control valve system operatively connected to the actuator. The control valve system includes a first direct drive valve (DDV) mechanically connected to a second DDV. A backup valve system is operatively connected to the actuator. The backup valve system includes one of an electro-hydraulic servovalve (EHSV) and a DDV.