Rotary Actuator Gearbox Decoupling for Jam Release
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Solution Overview
Problem
Gearbox driven rotary actuators in aircraft flight control systems are prone to jamming due to broken gear teeth or seized bearings, leading to hazardous flight conditions as they cannot move relative to the support structure, causing loss of control.
Innovation Solution
A flight control actuation arrangement with a latch arrangement that selectively couples and decouples the gearbox outer housing to the support housing, including a jam sensor and a release actuator to transition between locking and unlocking states, allowing the gearbox to move relative to the support structure and incorporating a damper or anti-float device to control motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a gearbox is introduced to compensate for reduced torque from an electric motor, then torque output is improved, but the risk of jamming increases due to broken gear teeth or seized bearings
Solution Approach 1:
The system is divided into a fixed support housing and a movable gearbox outer housing that can be selectively coupled or decoupled. This segmentation allows the gearbox to be isolated from the support structure when jamming occurs, enabling the jammed components to be released while maintaining the overall actuation system functionality.
Solution Approach 2:
The latch arrangement transitions between locked and unlocked states dynamically. When a jam is detected, the system automatically transitions from a fixed coupled state to a dynamic uncoupled state, allowing the gearbox to move freely relative to the support housing and release the jammed condition.
2Stability of the object's composition
If the gearbox is fixed to the support housing to maintain structural stability, then structural stability is improved, but the ability to release jams is lost as the jammed actuator cannot move
Solution Approach 1:
The connection between the gearbox outer housing and support housing is made dynamic through the latch arrangement. The system can switch between a stable locked state for normal operation and an unlocked state for jam release, combining structural stability with operational flexibility.
Solution Approach 2:
The latch arrangement acts as an intermediary mechanism between the fixed support housing and the movable gearbox outer housing. It provides a controlled coupling that maintains stability during normal operation but can be easily disengaged to allow jam release, mediating between the conflicting requirements of stability and mobility.
3Ease of operation
If the gearbox is decoupled from the support housing to enable jam release, then jam release capability is improved, but uncontrolled motion and fluttering may occur
Solution Approach 1:
The damper serves as a mediator between the gearbox outer housing and support housing, providing controlled resistance to motion. When the latch is unlocked, the damper allows the gearbox to move freely to release jams while simultaneously damping excessive motions and preventing fluttering, thus controlling the motion stability.
Solution Approach 2:
The damper provides beforehand cushioning by being pre-installed between the gearbox and support housing. When the latch is unlocked, the damper is already in position to cushion and control the motion, preventing uncontrolled movements and fluttering before they can occur.
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 movement of jammed rotary actuators to a neutral position, preventing permanent sticking and maintaining aircraft safety by allowing external loads to shift components, thus preventing hazardous flight conditions.
Implementation Method 1
a damper (e.g., a friction damper, a fluid damper, etc.) is disposed between the gearbox outer housing and the support structure. The damper limits the velocity of the motion of the gearbox outer housing relative to the support housing
Implementation Method 2
a damper (e.g., a friction damper, a fluid damper, etc.) is disposed between the gearbox outer housing and the support structure
Implementation Method 3
the latch arrangement includes a solenoid that extends and retracts to couple and decouple the rotary actuator (e.g., via the gearbox outer housing) to the support structure
Data Source
AI summary
Various flight control components can be operated through gearbox driven rotary actuators. In the event of a jam occurring the gearbox, the gearbox can be decoupled from a surrounding support housing to enable free-trailing or limited motion relative to the support housing. The motion may or may not be damped. Decoupling the gearbox enables the flight control component to move to a neutral or non-interfering position even when user control over the component has been lost.