Fire-Rated Latch Mechanism With Heat-Deployed Bolt Retention
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Solution Overview
Problem
Conventional latch mechanisms fail to maintain doors in a locked state during elevated temperature events such as fires, potentially allowing doors to be opened and facilitating the spread of fire and smoke.
Innovation Solution
Incorporation of deployable pins in the latch mechanism that deploy at a threshold temperature to retain the latch bolt in the latched position, using mechanisms like intumescent materials, biasing members, or actuators to activate the pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional latch mechanisms are used in exit devices, then ease of operation is improved (users can easily open doors), but reliability deteriorates (latch cannot maintain locked state during fire)
Solution Approach 1:
The deployable pins are pre-positioned within the latch mechanism body, ready to deploy automatically when thermal conditions trigger their release. This preliminary positioning ensures that when fire occurs, the pins are already in place to engage the latch bolt and maintain the locked state, resolving the reliability issue without affecting normal operation
Solution Approach 2:
The deployable pins act as an intermediary element between the latch bolt and the housing. During normal operation, they remain retracted and do not interfere with door opening. When fire occurs, they deploy to engage the latch bolt, providing an additional retaining mechanism that prevents the door from being opened during fire conditions
2Reliability
If deployable pins are added to the latch mechanism, then reliability is improved (latch maintains locked state during fire), but device complexity increases
Solution Approach 1:
The deployable pins are integrated into the existing latch mechanism housing and share common structural elements with the latch bolt assembly. The pins are positioned within recesses in the housing and utilize the same thermal activation mechanism as the rest of the latch system, merging the fire-retention function into the existing structure rather than adding a separate system
Solution Approach 2:
The deployable pins are designed to deploy automatically in response to thermal conditions without requiring external actuation or control systems. The thermal expansion or phase change of the activation mechanism directly drives the pin deployment, allowing the system to self-regulate based on temperature conditions and eliminating the need for complex control circuitry
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 deployable pins effectively maintain the door in a locked state during a fire, preventing door opening and containing hazards.
Implementation Method 1
the pins may be configured to deploy in response to activation of an intumescent material positioned adjacent to the pins
Implementation Method 2
the pins may be configured to deploy in response to activation of a biasing member operatively coupled to the pins
Data Source
AI summary
According to some embodiments, a latch mechanism configured to be secured to a door is provided. The latch mechanism may include a latch bolt that is movable between a latched position and a retracted position, and the latch bolt may be configured to engage a corresponding door strike when in the latched position. The latch mechanism may also include one or more deployable pins configured to move to a deployed position in response to being exposed to a threshold temperature such that the deployable pins may retain the latch bolt in the latched position when the deployable pins are in the deployed position.