Two-Pull Automatic Reset Latch System Design
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Solution Overview
Problem
Existing two-pull door latch systems face challenges in no-power scenarios where the first pull does not release the latch, and in power scenarios where timing is critical for motor reset, leading to potential premature door release due to partial pulls or quick successive pulls.
Innovation Solution
A two-pull, automatic reset latch system incorporating a release lever, coupling lever, reset lever, override link, and biasing member, along with an auto reset switch and gear home switch, which ensures decoupling during the first pull and automatic resetting before the second pull, preventing partial unlocks and ensuring accurate door release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor is used to electrically reset the system before the second pull, then the system can be reset in power scenarios, but timing becomes critical and premature door release may occur due to partial pulls or quick successive pulls
Solution Approach 1:
The system performs preliminary actions by using the first pull to decouple the release cable from the latch release system and trigger the motor reset before the second pull occurs. This ensures the system is ready for the second pull without timing conflicts, as the reset is initiated in advance during the first pull operation.
Solution Approach 2:
The patent introduces an intermediary mechanism (the decoupling mechanism and intermediate linkages) between the release cable and the latch release system. This intermediary allows the first pull to be absorbed without triggering immediate release, while still initiating the reset sequence, thereby preventing premature door release.
2Ease of operation
If the release cable is coupled to the latch release system on the first pull, then the latch can be released, but the system cannot reset properly before the second pull in power scenarios
Solution Approach 1:
The system dynamically changes the coupling state based on the pull sequence. On the first pull, the release cable is decoupled from the latch release system, allowing the cable to move freely while triggering the reset. On the second pull, the coupling is re-established, allowing the latch to release. This dynamic state change ensures both proper operation and reliable reset.
3Ease of operation
If partial pulls are allowed to partially unlock the door, then the door can be opened, but the system does not reset properly and may release prematurely on subsequent pulls
Solution Approach 1:
The system applies preliminary anti-action by preventing partial unlocks through the decoupling mechanism. The first pull is designed to decouple the release cable before any significant unlocking can occur, thereby counteracting the potential harmful effect of partial pulls. This ensures the system remains in a controlled state and resets properly before the second pull.
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 system effectively manages door release in both power and no-power scenarios by ensuring the latch is not released until the second pull, preventing premature unlocking and ensuring reliable operation by using a motor reset mechanism triggered by a timer or switch signals.
Implementation Method 1
a biasing member adapted to exert a biasing force upon the coupling lever in the first rotational direction with respect to the second axis
Data Source
AI summary
A two-pull, automatic reset, latch system is configured to operate during a no-power scenario and a power scenario. The latch system includes a release system, a release lever, and a coupling lever. The release lever is pivotally engaged to a stationary structure about a first axis. The coupling lever pivots about a second axis offset from the first axis, and is adapted to couple the release lever to the release system during a no-power scenario and upon two actuations of the release lever. The coupling lever is further adapted to maintain decoupling of the release lever from the release system during a power scenario.