Exit Device Firedog Link Fire Safety
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Solution Overview
Problem
Existing exit devices for doors in large facilities lack a reliable mechanism to prevent unauthorized retraction of the latchbolt during high-temperature events, such as fires, which can compromise door security.
Innovation Solution
The exit device incorporates a bracket configured to melt at high temperatures, supporting a firedog link that moves to inhibit the deadlock link from switching from a locked to an unlocked position, ensuring the door remains closed during a fire by preventing the deadlock link from being moved back to its unlocked position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bracket is added to support the firedog link to prevent latchbolt retraction during fires, then door security during high-temperature events is improved, but device complexity increases
Solution Approach 1:
A bracket is introduced as an intermediary component between the firedog link and the housing. This bracket provides a mounting structure that supports the firedog link in a position to engage with the deadlock link, preventing unauthorized retraction during fires. The bracket acts as a mediator that enables the firedog link to perform its security function without being directly integrated into the main body of the exit device.
Solution Approach 2:
The exit device is divided into distinct functional components: the housing, the deadlock link, the firedog link, and the bracket. This segmentation allows each component to perform its specific function independently. The bracket is a separate element that can be designed and positioned optimally to support the firedog link, while the other components maintain their individual roles in the locking and unlocking mechanisms.
2Ease of operation
If separate springs are used to bias the auxiliary bolt and deadlock link, then individual control of each component is improved, but device complexity and number of parts increases
Solution Approach 1:
Multiple springs are combined into a single integrated spring assembly. Instead of using separate springs for the auxiliary bolt and the deadlock link, the invention employs a unified spring mechanism that provides the necessary biasing forces for both components. This merging reduces the total number of parts while maintaining the individual controllability and functional independence of each component through the coordinated action of the combined spring system.
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
This solution enhances door security by maintaining the locked state during high-temperature events, preventing unauthorized opening and ensuring safety and security in emergency situations.
Implementation Method 1
The bracket is configured to melt at relatively high temperatures
Data Source
AI summary
An exit device includes a housing, a latchbolt coupled to and movable relative to the housing, and an auxiliary bolt coupled to the housing and movable relative to the latchbolt. The exit device also includes a deadlock link coupled to the housing and movable relative to the latchbolt and the auxiliary bolt between a first position, in which the deadlock link allows movement of the latchbolt relative to the housing, and a second position, in which the deadlock link inhibits movement of the latchbolt relative to the housing. The exit device further includes a spring biasing the auxiliary bolt into engagement with a portion of the deadlock link to move the deadlock link toward the first position.