Floating Motor Assembly for Exit Device Latch Calibration
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Solution Overview
Problem
Motorized latch retraction systems for exit devices often require calibration due to variations in dimensions and tolerances, leading to issues like motor stalling and incomplete disengagement of latches, and lack a clear indication of the locked or unlocked state.
Innovation Solution
A motorized latch retraction system with a floating motor assembly and a lock/unlock indicator, where the motor is positioned within a floating space with a restrictor to limit movement and a resilient restraint allows continued operation after the latch is actuated, and a visible indicator shows the lock or unlock status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a motorized latch retraction system is implemented, then the latch can be automatically retracted and released, but the system requires calibration due to dimensional variations and tolerances, leading to motor stalling and incomplete disengagement
Solution Approach 1:
The motor assembly is made dynamically adjustable through a calibration mechanism that allows the motor position to be shifted along the actuator shaft. This dynamic adjustment capability enables the system to compensate for dimensional variations and tolerances in different installations, preventing motor stalling and incomplete latch disengagement while maintaining automatic operation.
Solution Approach 2:
The system allows changes in the motor's positional parameter along the actuator shaft through mechanical calibration. By adjusting the motor's position parameter, the system adapts to specific installation dimensions and tolerances, ensuring reliable latch retraction without stalling while preserving the automated function.
2Reliability
If calibration is performed to ensure proper installation and functioning, then the device operates reliably, but the process is time-consuming and requires precise adjustment for each system
Solution Approach 1:
The calibration mechanism is designed to allow preliminary adjustment of the motor position before final installation testing. The mechanical calibration features enable installers to pre-set the motor position based on expected dimensional variations, reducing the time required for on-site calibration while ensuring reliable operation.
3Device complexity
If the motor position is fixed relative to the actuator, then the assembly is simple, but the motor may stall or fail to fully retract the latch due to system variations
Solution Approach 1:
The motor assembly incorporates a calibration mechanism that provides controlled adjustability of the motor position along the actuator shaft. This dynamic feature adds minimal structural complexity while significantly improving reliability by preventing motor stalling and ensuring complete latch retraction across different installation scenarios.
4Device complexity
If no indication of lock status is provided, then the device is simpler, but users cannot determine whether the latch is locked or unlocked
Solution Approach 1:
The lock status indicator uses visual color changes or position changes to indicate whether the latch is locked or unlocked. This provides clear lock status information to users with minimal additional complexity, using visual cues such as colored indicators or visible movement of indicator elements.
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 prevents motor stalling and allows for pre-calibration to accommodate installation variations, ensuring reliable latch operation and providing a clear indication of the lock status, enhancing user safety and convenience.
Implementation Method 1
a resilient restraint positioned between the first longitudinal end of the restrictor and the motor
Data Source
AI summary
A motorized latch retraction system for transitioning a latch of an exit device from a latched position to an unlatched position is provided. The motorized latch retraction system includes a lock indicator indicating the latched or unlatched position of the latch and a floating motor.