Electromechanical Actuator Anti-Blocking Pivot Mechanism
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Solution Overview
Problem
Existing electromechanical actuators in aircraft can block, causing safety issues when one actuator fails and opposes movement of a flight control surface, leading to the need for bulky torque limiters to decouple the control surface, which increases space requirements.
Innovation Solution
An electromechanical actuator with a coaxial gear reducer and an anti-blocking system that includes a movable clutch plate and an electrically-controlled latch, allowing the gear reducer to pivot and release the blocking mechanism, enabling free movement of the control surface when an actuator blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque limiter is interposed between the actuator and control surface to prevent blocking, then the control surface can be decoupled from the faulty actuator, but the actuator requires more space and becomes bulkier
Solution Approach 1:
The patent combines the anti-blocking function with the existing actuator structure by making the gear reducer itself pivotable about the motor outlet shaft axis. This merges the torque limiting function into the gear reducer design rather than adding a separate bulky torque limiter device, thus preventing actuator blocking while maintaining compact dimensions
Solution Approach 2:
The gear reducer is designed to pivot dynamically about the motor outlet shaft axis when blocking forces are detected. This dynamic capability allows the system to automatically decouple the control surface from the faulty actuator through controlled pivoting motion, providing anti-blocking functionality through motion rather than requiring a separate static torque limiter mechanism
2Reliability
If two actuators are provided for each flight control surface to ensure redundancy, then the aircraft can continue operating if one actuator fails, but the risk of the faulty actuator seizing and opposing movement increases
Solution Approach 1:
The patent implements preliminary anti-action by designing the gear reducer with built-in anti-blocking capability that prevents the faulty actuator from seizing and opposing movement before it can cause harm. The pivotable design allows the system to preemptively decouple the control surface from the failing actuator through controlled pivoting, eliminating the blocking force before it can affect the redundant actuator's operation
3Reliability
If the gear reducer is made pivotable about the motor outlet shaft axis to release blocking, then the control surface can oscillate freely when an actuator fails, but the mechanism becomes more complex
Solution Approach 1:
The motor outlet shaft serves multiple functions: it transmits motor torque to the gear reducer during normal operation and simultaneously serves as the pivot axis for the gear reducer during blocking conditions. This multi-functionality eliminates the need for separate pivot mechanisms, achieving the ability to release blocking without significantly increasing device complexity
Solution Approach 2:
The gear reducer is segmented into a pivotable section that can rotate independently about the motor outlet shaft axis. This segmentation allows the blocking-releasing function to be isolated to a specific portion of the mechanism, simplifying the overall design by localizing the complexity rather than distributing it throughout the entire actuator system
Data Source
AI summary
An electromechanical actuator comprising a frame having mounted thereon a rotary motor and a gear train having an inlet shaft lying on the same axis as an outlet shaft of the motor and connected thereto, and an outlet ring coaxial with the outlet shaft of the motor and connected to a lever for operating a member that is to be driven. The gear train is carried by a casing mounted on the frame to pivot about the axis of the outlet shaft of the motor. An anti-blocking device is mounted on the frame and comprises a movable element that is movable between a blocking position for blocking the casing in rotation relative to the frame, and a release position for releasing the casing in rotation relative to the frame.