Pin Latch Intermediate Position via Segmented Finger Slot
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Solution Overview
Problem
Conventional pin latches for aerospace applications typically have only two positions: closed and open, lacking an intermediate position that could be useful for secure but partially open configurations, such as during maintenance or inspection.
Innovation Solution
A pin latch design featuring a housing with a handle that can pivot between closed, intermediate, and open positions, utilizing a shear pin mechanism and a finger member with slots to retain the handle in an intermediate position, allowing for secure but partially open configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional pin latch with only two positions (closed and open) is used, then the device complexity is low, but the adaptability is limited because it cannot provide an intermediate position for partial access configurations
Solution Approach 1:
The slot in the finger member is segmented into three distinct portions (first, second, and third portions) that guide the pin through different positions. This segmentation allows the latch to achieve multiple positions (closed, intermediate, and open) by having the pin traverse through different segments of the slot, thereby providing adaptability without requiring entirely separate mechanisms for each position.
Solution Approach 2:
The finger member acts as an intermediary element between the handle and the housing. It includes a slot with a stop that mediates the movement of the pin, allowing the handle to be retained at an intermediate position. The stop within the slot serves as a mediator that temporarily holds the pin, enabling the intermediate position to be achieved without complex additional locking mechanisms.
2Reliability
If the handle is allowed to move freely between positions, then the ease of operation is improved, but the reliability decreases because the handle cannot be reliably retained in the intermediate position
Solution Approach 1:
The slot is designed with a stop positioned at a specific location within the third portion, which preliminarily determines the intermediate position before the handle is fully operated. This preliminary positioning feature ensures that when the pin engages the stop, the handle is reliably retained at the intermediate position, providing reliable retention without restricting the overall ease of movement between positions.
Solution Approach 2:
The latch mechanism is designed to automatically retain the handle at the intermediate position through the interaction between the pin and the stop within the slot. No additional external locking mechanism or complex control system is required; the geometry of the slot and stop themselves provide the retention function, allowing the mechanism to serve itself in maintaining the intermediate position reliably.
Data Source
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Figure 3A~3B
Figure 4
AI summary
A pin latch (10) includes a housing (12), a handle (14) attached to the housing (12), a shear pin (110) attached to the handle (14), and a finger member (118) attached to the handle (14) and the shear pin (110). The handle (14) may be set in an intermediate position between open and closed positions. Trigger pins (140) slidably engage slots (128) formed within the finger member (118) until they engage stops (135) to retain the handle (14) in its intermediate position. To further retract the shear pin (110) and move the handle (14) towards the open position, the finger member (118) is lifted and the trigger pins (140) disengage the stops (135). Alternately, the latch (10) includes a button mechanism (372) having a cross-pin (384) that engages a stop (344) formed by a slot (342) within the shear pin (330) to maintain the handle (214) in its intermediate position. To further retract the shear pin (330) and rotate the handle (214), the button mechanism (372) is depressed to disengage the cross-pin (384) from the slot (342) of the shear pin (330).