Drive Assembly Selective Disconnect Mechanism
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Solution Overview
Problem
Aircraft electro-mechanical actuators can become stuck or jammed, making it difficult for backup systems to control flight control surfaces effectively, leading to inefficiencies and potential safety issues during system failures.
Innovation Solution
A drive assembly with a selective disconnect mechanism, comprising a motor, harmonic drive, and retracting mechanism, which allows for the axial decoupling of the motor drive shaft from the harmonic drive, enabling the system to disengage and reengage efficiently, preventing energy wastage and jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary electro-mechanical actuator system remains engaged, then the system maintains continuous control capability, but the backup system cannot effectively control flight control surfaces when the primary system jams
Solution Approach 1:
The drive assembly is segmented into separable components: the motor drive shaft assembly and the harmonic drive assembly. The retracting mechanism enables the motor drive shaft to be axially displaced, separating it from the harmonic drive. This segmentation allows the backup system to disengage the jammed primary system and independently control flight control surfaces.
Solution Approach 2:
The drive assembly transitions from a static connected state to a dynamic separable state. The retracting mechanism provides axial movement capability, allowing the motor drive shaft to move in and out of engagement with the harmonic drive. This dynamic capability enables the system to switch between primary and backup control modes.
2Loss of energy
If the motor drive shaft remains coupled to the harmonic drive, then continuous power transmission is maintained, but energy wastage occurs when the primary system is jammed
Solution Approach 1:
The retracting mechanism extracts the motor drive shaft from the harmonic drive assembly by applying axial force. This extraction separates the power transmission path, preventing energy wastage when the primary system is jammed. The mechanism takes out the engaged state and replaces it with a disengaged state.
Solution Approach 2:
The retracting mechanism acts as an intermediary between the motor drive shaft and the harmonic drive. It mediates the engagement and disengagement process by providing controlled axial movement, making the disengagement operation straightforward and controlled rather than requiring forceful separation.
3Reliability
If the primary system is allowed to remain engaged during failure, then system redundancy is maintained, but the backup system cannot overcome the jammed primary system
Solution Approach 1:
The retracting mechanism extracts the motor drive shaft from the harmonic drive, removing the jammed primary system from the power transmission path. This extraction eliminates the resistance force that would otherwise prevent the backup system from effectively controlling the flight control surfaces.
Solution Approach 2:
The system dynamically switches from primary system engagement to backup system engagement. The retracting mechanism enables this transition by providing axial movement to disengage the motor drive shaft, allowing the backup system to take over without overcoming the jammed primary system's resistance.
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 solution allows the backup system to function more efficiently and reliably by preventing the backup system from having to overcome resistance caused by a jammed primary system, ensuring safer and more controlled aircraft maneuverability during failures.
Implementation Method 1
a harmonic drive coupled to the motor drive shaft; an output shaft coupled to the harmonic drive
Data Source
AI summary
A drive assembly with selective disconnect includes a motor with a motor drive shaft; a harmonic drive coupled to one end of the motor drive shaft; an output shaft coupled to the harmonic drive; and a retracting mechanism that selectively retracts the motor drive shaft axially to decouple the motor drive shaft from the harmonic drive.