Actuator Mechanism Helical Lock Prevents Intermediate Sticking
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Solution Overview
Problem
Conventional actuator mechanisms for aircraft engine cowls can become stuck in intermediate positions during transition from locked to stowed states, leading to false locking and potential damage or injury due to reliance on spring biased detent balls, which are sensitive to torque variations and limited in angular deviation tolerance.
Innovation Solution
The actuator system employs a rotatable lock mechanism with a collar and tine gate combination, featuring a detent finger and sloping surfaces to prevent pin return to the lock recess, and a helical profile on the locking collar to handle larger angular deviations, eliminating the need for spring biased detent balls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring biased detent balls are used to prevent intermediate positioning, then reliability is improved, but the system becomes sensitive to torque variations and limited in angular deviation tolerance
Solution Approach 1:
The patent removes the spring biased detent ball mechanism from the system and replaces it with a helical groove guide path. This extraction eliminates the torque sensitivity and angular deviation limitations inherent in the detent ball approach, while maintaining the reliability of preventing intermediate positioning through the geometric constraints of the helical path.
Solution Approach 2:
Instead of using a detent ball that relies on spring force and friction to prevent intermediate positioning, the patent inverts the approach by using a helical groove that passively guides the pin through a controlled path. The prevention mechanism shifts from active force-based detention to passive geometric constraint, eliminating torque sensitivity.
2Reliability
If a rotatable lock mechanism with pin and collar is used, then the actuator can be locked in extended position, but the pin may become stuck in intermediate positions during transition
Solution Approach 1:
The patent introduces a helical groove - a curved, three-dimensional path - that guides the locking pin during state transitions. This curved guide path ensures smooth, controlled movement of the pin from locked to stowed position, preventing it from becoming stuck in intermediate positions while maintaining the locking capability when fully extended.
Solution Approach 2:
The helical groove acts as an intermediary element between the locking pin and the collar. It mediates the transition by providing a predetermined path that the pin must follow, ensuring smooth operation and preventing direct, uncontrolled engagement that could lead to intermediate sticking.
3Measurement precision
If the actuator is not fully extended before retraction, then the lock mechanism may not be properly engaged, but the actuator appears to be locked in extended position
Solution Approach 1:
The helical groove provides inherent feedback through its geometric design. The pin can only reach the final locked position by completing the full helical path, which requires full extension. Any incomplete extension results in the pin being unable to reach the final position in the groove, providing clear feedback that the locking process is incomplete, thus preventing false locking indications.
Data Source
AI summary
An actuator system comprising a rotatable lock mechanism defining a path for an actuator pin as the actuator is expanded and retracted, wherein the lock mechanism defines an entry passage through which the pin enters as the actuator extends, a guide surface along which the pin travels from the entry passage as the actuator retracts, a locking recess into which the pin is guided by the guide surface, and an exit passage into which the pin is guided as it is caused to leave the lock recess by extension of the actuator and subsequent retraction; whereby a detent surface is provided to prevent the pin returning back into the lock recess when the actuator is extended to cause the pin to leave the lock recess.