Declutchable Flight Control Actuator for Jam Bypass
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Solution Overview
Problem
Flight control actuators in aircrafts are prone to jamming due to the large number of bearings in their gearboxes, leading to loss of control when jammed, and existing mechanical fuses require significant physical strength to break and can cause involuntary aircraft movement.
Innovation Solution
A declutchable flight control actuator with an output lever that can be automatically or manually disconnected from the gearbox, using a solenoid and plunger mechanism to allow continued control of the aircraft without jamming, reducing the need for physical strength and minimizing involuntary movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical fuse (shear pin) is used to bypass the actuator in case of jamming, then the pilot can continue to control the aircraft, but the fuse requires great physical strength to break and can cause substantial involuntary movement of the aircraft
Solution Approach 1:
The patent replaces the purely mechanical shear pin system with an electromechanical declutching mechanism. A solenoid actuates a plunger that engages with a cam mechanism to rotate the output lever away from the output shaft, disengaging the actuator. This substitution of mechanical force with electromagnetic force eliminates the need for the pilot to exert great physical strength while maintaining the ability to bypass a jammed actuator.
Solution Approach 2:
The patent introduces a solenoid and plunger as intermediary components between the pilot's control input and the output lever. The solenoid converts electrical signals into mechanical motion, which is then transmitted through the plunger and cam mechanism to achieve smooth declutching. This intermediary system mediates the force requirement and eliminates the harmful effect of substantial involuntary aircraft movement.
2Reliability
If a mechanical fuse (shear pin) is used to bypass the actuator in case of jamming, then the pilot can continue to control the aircraft, 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 employs a dynamic declutching mechanism where the output lever is rotated gradually away from the output shaft through a cam mechanism actuated by a solenoid. This dynamic, controlled movement replaces the sudden, static force application of breaking a shear pin. The gradual engagement and disengagement of the declutching mechanism ensures smooth transition and eliminates harmful involuntary aircraft movement while maintaining control continuity.
3Ease of operation
If a gearbox with multiple bearings is used in the flight control actuator, 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 segments the flight control system into two independent pathways: the actuated path through the gearbox and the direct mechanical linkage path. The declutching mechanism allows the system to switch between these segments. When the gearbox segment jams, the system can be declutched to bypass it and use the direct linkage segment, maintaining control while preserving the force feel capability provided by the gearbox segment during normal operation.
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 disconnection of the actuator from the flight controls in case of jamming, maintaining control without substantial effort or unwanted aircraft movement, and allows for automatic detection and response to jams, enhancing safety by reducing the time the aircraft is uncontrollable.
Implementation Method 1
using a solenoid and plunger mechanism to allow continued control of the aircraft without jamming
Data Source
AI summary
A flight control actuator for actuating an aircraft flight control system is provided. The flight control actuator comprises a gearbox, an output shaft attached to the gearbox and an output lever provided on the output shaft. The output lever is declutchable from the output shaft. The output lever includes an inner diameter through which the output shaft passes and at least one indentation in said inner diameter. The output shaft includes a hollow cylindrical member with at least one hole provided at the axial position of the at least one indentation of the output lever.