Spring Loaded Actuator Assembly for Aircraft Stowage Bins
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Solution Overview
Problem
Existing spring actuators fail to provide selective retention and release of assist force relative to objects like aircraft stowage bins, particularly in over center conditions, leading to inefficient opening and closing mechanisms.
Innovation Solution
A spring-loaded actuator assembly comprising a first member with rails, a second member with ramp-like teeth, and a third member that translates within the second member, allowing for axial movement while preventing rotation, enabling the coil spring to be compressed or extended as needed to assist in opening or closing, and capturing the spring force to prevent interference during over center conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spring actuator is used to provide assist force for opening and closing operations, then the hand force required is reduced, but the actuator may impede operation during initial opening before over center condition
Solution Approach 1:
The actuator system transitions from a static spring connection to a dynamic telescoping mechanism that adapts its state based on operational phase. The telescoping members allow the spring to be disengaged during initial opening (when not needed) and engaged after over center (when needed), making the force assistance dynamic rather than continuous.
Solution Approach 2:
The ramp-like teeth act as an intermediary mechanism between the telescoping members and the spring. These teeth engage to lock the telescoping members in place, thereby activating the spring's assist force, and disengage to allow free telescoping movement, thereby deactivating the spring force. This intermediary mechanism enables selective engagement of the spring based on operational needs.
2Force
If the actuator provides continuous spring force, then opening assistance is maximized, but the actuator interferes with free actuation when not required
Solution Approach 1:
The system dynamically transitions between two states: a locked state where ramp-like teeth engage to hold the telescoping members and activate spring force, and an unlocked state where the teeth are disengaged allowing free telescoping movement and spring force deactivation. This dynamic state change enables adaptive force application based on operational requirements.
Solution Approach 2:
The ramp-like teeth are positioned specifically at certain locations on the telescoping members to engage only at appropriate moments during operation. This localized engagement mechanism ensures that spring force is applied only in specific operational phases (after over center) rather than continuously, providing selective force application where needed.
3Ease of operation
If the actuator allows free telescoping movement, then operation is simplified, but the spring force cannot be captured and retained
Solution Approach 1:
The ramp-like teeth serve as an intermediary locking mechanism that can engage to capture and retain spring force by preventing telescoping movement, or disengage to allow free telescoping. This intermediary provides selective control between freedom of movement and force retention based on operational phase.
Solution Approach 2:
The ramp-like teeth are positioned and configured to automatically engage at the appropriate moment during operation to capture the spring force. This preliminary positioning ensures that when the telescoping members reach the over center position, the teeth are ready to engage and lock the spring in place, capturing the force before it can dissipate.
Data Source
AI summary
A spring loaded actuator assembly includes a first member having a set of rails, a second member configured to translate axially relative to the first member and a third member configured for translational movement within the second tubular member. The second and third members each include a set of ramp-like teeth configured to engage one another when the third member is moved within the second member; and grooves configured to engage the rails of the first member and permit translational movement of the second and third members relative to the first member while preventing rotational movement of the second and third members. A coil spring is disposed between the first and second members wherein translational movement of the second member beyond a predetermined axial position causes the ramp-like teeth of the second member to extend beyond the rails, causing the second member to rotate and the ramp-like teeth to be retained by the rails of the first member, thereby maintaining the coil spring in a compressed condition while enabling the third member to be freely movable axially.