Declutchable Flight Control Output Lever for Actuator Jamming
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Solution Overview
Problem
Flight control actuators in aircraft systems are prone to jamming due to the large number of bearings in their gearboxes, leading to loss of control if a jam occurs, and existing mechanical fuse solutions require significant physical strength to bypass and can cause unsafe aircraft movements.
Innovation Solution
A flight control actuator with a declutchable output lever and solenoid-plunger mechanism that allows automatic or manual declutching to prevent jamming, enabling continued pilot control without the need for physical strength or involuntary aircraft movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical fuse (shear pin) is used to bypass actuator jamming, then the pilot can regain control in case of actuator failure, but the fuse requires great physical strength to break and can cause substantial involuntary aircraft movement
Solution Approach 1:
The patent replaces the purely mechanical shear pin system with an electromechanical declutching mechanism. A solenoid actuator electronically controls the engagement and disengagement of the output lever from the gearbox, eliminating the need for manual breaking of mechanical fuses. This substitution allows the pilot to bypass actuator jamming through electrical actuation rather than physical force, directly resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
The patent introduces a solenoid actuator as an intermediary device between the pilot's control input and the mechanical linkage. This intermediary converts electrical signals into mechanical motion to control the declutching mechanism, providing a controlled and safe method to bypass actuator failures without the dangerous involuntary movements associated with breaking mechanical fuses.
2Reliability
If a mechanical fuse is used to bypass actuator jamming, then control can be regained, but the action of breaking the fuse can cause substantial involuntary movement of the aircraft which could be extremely dangerous
Solution Approach 1:
The patent replaces the violent mechanical breaking action of shear pins with a controlled electromechanical declutching process. The solenoid actuator gradually disengages the output lever from the gearbox through controlled mechanical motion, eliminating the sudden involuntary aircraft movements that occur when mechanical fuses are broken. This directly addresses the harmful effects while maintaining control continuity.
Solution Approach 2:
The patent implements preliminary declutching capability that can be activated before critical failure occurs. The solenoid-controlled mechanism allows the pilot to disengage the actuator from the mechanical linkage in advance, preventing the dangerous involuntary movements that would result from emergency breaking of mechanical fuses during critical flight phases.
3Power
If multiple bearings are used in the gearbox to achieve two stages of gears, then the actuator can provide force feel and position backdrive, but the large number of bearings increases the risk of jamming
Solution Approach 1:
The patent extracts the output lever from the gearbox assembly, making it a separate declutchable component. By taking the output lever out as an independent element that can be disengaged, the system maintains the multi-bearing gearbox for normal operation while providing a means to isolate the gearbox from the mechanical linkage in case of jamming, thus resolving the contradiction between power transmission and reliability.
Solution Approach 2:
The patent segments the actuator system into distinct modular components: the gearbox with multiple bearings for force feel, the output lever as a separate declutchable element, and the mechanical linkage. This segmentation allows the gearbox to maintain its complex bearing structure for power transmission while the output lever can be independently disengaged to prevent jamming propagation, resolving the contradiction between power capability and reliability.
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
Enables safe and effortless bypassing of actuator jams, maintaining aircraft control and reducing the risk of unsafe movements, with automatic detection and re-clutching capabilities for quick recovery and reduced pilot effort.
Implementation Method 1
a solenoid actuator configured to move the output lever axially between a first position and a second position
Data Source
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AI summary
A flight control actuator (14) for actuating an aircraft flight control system is provided. The flight control actuator (14) comprises a gearbox, an output shaft (20) attached to the gearbox and an output lever (21) provided on the output shaft (20).The output lever (21) is declutchable from the output shaft (20).