Latchbolt Damping Module for Quiet Exit Device Relatching
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Solution Overview
Problem
Conventional exit devices generate excessive noise due to the free return of the latchbolt and impact between components during latching and relatching operations, which is undesirable in quiet environments like healthcare settings.
Innovation Solution
A damper module is introduced, comprising a mounting bracket, a first slowing mechanism with a rack gear and rotary damper, and a second slowing mechanism with a slowing arm and biasing member, to independently slow the extension speed of the latchbolt, reducing noise generation during latching and relatching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the latchbolt is allowed to return freely to its extended position, then the latching operation is quick and efficient, but excessive noise is generated due to impact and grinding between components
Solution Approach 1:
The rotary damper is pre-installed on the rack gear and the slowing arm with biasing member are pre-positioned to engage the retractor before the latching operation begins. This preliminary setup ensures that the slowing mechanisms are already in place to control the latchbolt's movement, preventing excessive speed and impact noise from the start of the operation
Solution Approach 2:
The rotary damper acts as an intermediary element between the rack gear and the drive mechanism, providing resistance to the rack gear's movement. Similarly, the slowing arm with biasing member serves as an intermediary between the retractor and the latchbolt, controlling the retraction speed. These intermediary components reduce the direct impact and grinding between the latchbolt and strike, thereby reducing noise while maintaining latching functionality
2Device complexity
If conventional exit devices are used without damping mechanisms, then the device complexity is low, but the noise generated during latching operations exceeds recommended levels
Solution Approach 1:
The damping system is segmented into two independent mechanisms: a rotary damper for the rack gear and a slowing arm with biasing member for the retractor. This segmentation allows each component to address specific noise sources independently, providing effective noise control while keeping individual components relatively simple and modular for easier installation and maintenance
3Object-generated harmful factors
If the latchbolt extension speed is reduced to minimize noise, then noise generation is reduced, but the latching operation becomes slower
Solution Approach 1:
The damping mechanisms provide dynamic resistance to the latchbolt's movement rather than constant friction. The rotary damper creates velocity-proportional resistance through rotational damping, and the biasing member on the slowing arm provides elastic resistance that varies with compression. This dynamic approach allows the system to maintain reasonable latching speed while effectively controlling peak velocities that cause impact noise
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 damper module effectively reduces noise by slowing the deactuating and extending speeds of the latchbolt and retractor, minimizing vibrations and metal-to-metal contact noises, thereby enhancing the quiet operation of exit devices.
Implementation Method 1
The rotary damper is mounted to the mounting bracket. The second slowing mechanism includes a slowing arm and a biasing member engaged with the slowing arm
Implementation Method 2
The second slowing mechanism includes a slowing arm and a biasing member engaged with the slowing arm
Data Source
AI summary
An exemplary damper module is configured for use with a latchbolt assembly, and generally includes a mounting bracket, a first slowing mechanism, and a second slowing mechanism. The latchbolt assembly generally includes a drive member, a latchbolt, and a retractor connected between the drive member and the latchbolt. Each of the slowing mechanisms is independently operable to slow the extension speed of the latchbolt. The first slowing mechanism includes a rack gear and a rotary damper including a pinion gear. The rack gear is configured to be mounted to the drive member, and the rotary damper is mounted to the mounting bracket. The second slowing mechanism includes a slowing arm and a biasing member engaged with the slowing arm. The slowing arm is movably mounted to the mounting bracket and is configured to engage the retractor.