Actuator Locking Mechanism Prevents False Engagement
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Solution Overview
Problem
Hydraulic or pneumatic actuators used for aircraft engine cowl doors face issues with maintaining the door in an open position without continuous hydraulic pressure, as existing locking mechanisms can falsely indicate a locked position if not fully extended, leading to potential door closure due to vibrations or pressure loss.
Innovation Solution
An actuator with a rotatable lock formation and resilient detent means, where a pin moves through an entry passage and is prevented from returning by a resilient finger, ensuring the actuator is fully extended before locking, and a ramped release surface facilitates retraction by rotating the lock formation to allow exit passage engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a push-push locking mechanism is used to lock the actuator in extended position, then the hydraulic pump does not need to operate continuously to hold the door open, but the actuator may falsely appear locked in intermediate positions leading to unsafe conditions
Solution Approach 1:
The resilient finger is pre-positioned to engage the pin only after the actuator has fully extended. The finger's deflection and engagement sequence ensures that locking can only occur after the predetermined extension distance is achieved, preventing false locking in intermediate positions
Solution Approach 2:
The resilient finger provides mechanical feedback through its deflection and engagement with the pin. The finger only engages the pin after the actuator has moved the predetermined distance, providing a physical confirmation that full extension has been achieved before locking occurs
2Adaptability or versatility
If the actuator allows retraction from locked position, then the door can be closed when needed, but the actuator may retract to intermediate positions and falsely engage the locking mechanism
Solution Approach 1:
The locking mechanism is inverted so that the resilient finger actively engages the pin rather than the pin passively entering a lock pocket. This inversion ensures that locking only occurs when the finger is deflected by the pin's movement beyond the predetermined position, preventing false engagement during retraction
Solution Approach 2:
During retraction, the actuator must first return to the fully extended position to disengage the lock before it can move to intermediate positions. The resilient finger's geometry ensures that the pin cannot engage it unless the actuator has completed the full extension cycle, preventing false locking during position transitions
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
The solution ensures the actuator remains locked only when fully extended, preventing false locking and maintaining the door open, and allows for safe retraction by ensuring the actuator is fully extended before locking, reducing the risk of door closure due to pressure loss or vibrations.
Implementation Method 1
resilient detent means operable such that, once the pin has moved beyond a predetermined position within the entry passage, the resilient detent means prevents return movement of the pin along the entry passage. The resilient finger which deflects as the pin passes over the finger
Implementation Method 2
The finger conveniently includes a sloped end surface cooperable with the pin to cause rotation of the lock formation to direct return movement of the pin towards the lock pocket
Data Source
Figure 1
Figure 2~3
AI summary
An actuator comprises an actuator output shaft (22), a rotatable lock formation (26) associated with the output shaft (22) so as to be axially fixed relative thereto, the lock formation (26) defining an entry passage (36), a lock pocket (38) and an exit passage (36), a pin (40) positioned for movement relative to the lock formation (26) such that, as the actuator approaches a fully extended position, a part of the pin (40) is received within and passes along the entry passage (36), and resilient detent means (44) operable such that, once the pin (40) has moved beyond a predetermined position within the entry passage (36), the resilient detent means (44) prevents return movement of the pin (40) along the entry passage (36).