Motorized Exit Device Link Control for Wear Reduction
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Solution Overview
Problem
Solenoid actuated exit devices for emergency and fire exit doors experience rapid wear and excessive noise due to abrupt changes in locking mechanism states, which is not addressed by existing mechanical dogging systems or solenoid actuated mechanisms.
Innovation Solution
A method and apparatus for operating an exit device using a motor connected to a link that moves between locked and unlocked positions, where the motor operates until a hard stop position is reached, and then selectively moves to a soft stop position to maintain the unlocked state, reducing wear and noise through controlled movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If solenoid actuated mechanisms are used to replace mechanical dogging devices, then unmanned operation of the exit device is achieved, but the locking mechanism experiences rapid wear and generates excessive noise due to abrupt state changes
Solution Approach 1:
The patent applies dynamics by transitioning from static abrupt state changes to dynamic controlled movement. The motor gradually moves the link from locked to unlocked position over time, rather than instantaneously switching states. This dynamic approach reduces mechanical impact and wear while maintaining automation.
Solution Approach 2:
The patent changes the parameter of movement speed control. The motor operates at controlled speeds with acceleration and deceleration phases, changing the temporal parameter of the locking mechanism's movement. This parameter modification eliminates abrupt transitions, reducing wear and noise while preserving unmanned operation capability.
2Extent of automation
If solenoid actuated mechanisms are used to replace mechanical dogging devices, then unmanned operation of the exit device is achieved, but the locking mechanism generates excessive noise due to abrupt state changes
Solution Approach 1:
The patent applies dynamics by transitioning from static abrupt state changes to dynamic controlled movement. The motor gradually moves the link from locked to unlocked position over time, rather than instantaneously switching states. This dynamic approach reduces mechanical impact and wear while maintaining automation.
Solution Approach 2:
The patent changes the parameter of movement speed control. The motor operates at controlled speeds with acceleration and deceleration phases, changing the temporal parameter of the locking mechanism's movement. This parameter modification eliminates abrupt transitions, reducing wear and noise while preserving unmanned operation capability.
3Length of moving object
If the motor operates until the link reaches the hard stop position, then the link achieves full travel range, but the locking mechanism experiences increased wear and noise
Solution Approach 1:
The patent applies partial action by stopping the motor before the link reaches the hard stop position. A predetermined distance is maintained between the link and hard stop, providing a cushioning effect. This partial approach prevents full impact while still achieving sufficient travel range for operational purposes.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a buffer zone before the hard stop. The motor controller is programmed to decelerate and stop the link at a position that maintains a predetermined distance from the hard stop, cushioning against potential impact and wear before contact occurs.
4Length of moving object
If the motor operates until the link reaches the hard stop position, then the link achieves full travel range, but excessive noise is generated
Solution Approach 1:
The patent applies partial action by stopping the motor before the link reaches the hard stop position. A predetermined distance is maintained between the link and hard stop, providing a cushioning effect. This partial approach prevents full impact while still achieving sufficient travel range for operational purposes.
Solution Approach 2:
The patent implements beforehand cushioning by introducing a buffer zone before the hard stop. The motor controller is programmed to decelerate and stop the link at a position that maintains a predetermined distance from the hard stop, cushioning against potential impact and wear before contact occurs.
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 solution effectively reduces wear and noise in exit devices by controlling the movement of the locking mechanism, allowing for efficient and quiet operation, and enabling unmanned operation with reduced maintenance needs.
Implementation Method 1
a motor operably connected to the link
Data Source
AI summary
An exit device that includes a locking mechanism for locking and unlocking a door, the locking mechanism having a latch bolt, and a link connected to the latch bolt, movement of the link between locked and unlocked positions causes movement of the latch bolt between an extended state and a retracted state to lock and unlock the door, and a motor operably connected to the link. A method of operating the exit device includes operating the motor to move the link in a first direction toward the unlocked position, the motor being operated until the link reaches a hard stop position; thereafter determining a soft stop position based on the hard stop position; and thereafter selectively using the motor to move the link in the first direction toward the unlocked position, the motor being operated only until the link reaches the soft stop position.