Motorized Trim Locking Mechanism for Power Reduction
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Solution Overview
Problem
Existing lockable exit device trims face issues with power consumption and susceptibility to adverse weather conditions, as well as tampering, necessitating improvements in their design and functionality.
Innovation Solution
A trim assembly with a housing assembly, a cam, a lift finger, and a locking mechanism that includes an interface member, a blocking member, and a driver, allowing for selective locking and unlocking, controlled by a control assembly that manages power usage and transitions between locking and unlocking states based on power availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid-actuated locking mechanism is used in the trim assembly, then the locking function can be achieved, but power consumption increases and susceptibility to adverse weather conditions and tampering worsens
Solution Approach 1:
The patent replaces the solenoid-actuated locking mechanism with a mechanically actuated locking system that uses a cam, lift finger, and blocking member assembly. The cam is rotated by the handle operation to mechanically drive the lift finger, which in turn moves the interface member and blocking member to achieve locking/unlocking. This mechanical substitution eliminates the need for electrical power while maintaining reliable locking functionality.
Solution Approach 2:
The locking mechanism is designed to be self-actuating through the handle operation itself. When the handle is operated, the cam rotates and automatically drives the entire locking sequence through the lift finger and interface member, without requiring any external power source or additional actuation. The system serves itself using the mechanical energy from the handle operation.
2Reliability
If a solenoid-actuated locking mechanism is used in the trim assembly, then the locking function can be achieved, but susceptibility to adverse weather conditions and tampering worsens
Solution Approach 1:
The patent replaces the electric solenoid system with a purely mechanical locking system that has no electrical components exposed to the environment. The mechanical components (cam, lift finger, blocking member) are enclosed within the trim housing, protecting them from weather conditions while maintaining reliable locking function through mechanical advantage and positive engagement.
Solution Approach 2:
The locking mechanism is divided into separate functional components (cam, lift finger, interface member, blocking member) that are distributed throughout the housing. This segmentation allows each component to be optimized for its specific function and protects the overall system by distributing risk - if one component fails or is tampered with, the segmented design can prevent complete system compromise.
3Ease of operation
If the lift finger is made movable to allow exit device operation, then ease of operation is improved, but vulnerability to unauthorized activation increases
Solution Approach 1:
The patent introduces an interface member as an intermediary between the lift finger and the blocking member. The interface member translates the vertical movement of the lift finger into horizontal movement of the blocking member, which then engages or disengages from the cam to lock or unlock the mechanism. This intermediary adds a mechanical translation step that prevents direct actuation while maintaining the desired operation when properly initiated through the handle.
Solution Approach 2:
The blocking member is positioned in advance to block the cam's path of rotation, preventing unauthorized activation. The mechanical linkage is designed so that the blocking member must be moved to a specific position by the proper handle operation before the cam can rotate and activate the exit device. This preliminary blocking action ensures that only authorized operation can disengage the block.
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 provides a reliable and efficient locking mechanism that reduces power consumption and enhances resistance to tampering and environmental factors, ensuring secure operation of exit devices while optimizing energy use.
Implementation Method 1
a cam rotatably mounted to the housing assembly, and a lift finger slidably mounted in the housing assembly such that the cam is operable to linearly drive the lift finger between a deactuated position and an actuated position
Data Source
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AI summary
An exemplary trim assembly comprises a housing assembly, a cam rotatably mounted to the housing assembly, a lift finger slidably mounted in the housing assembly such that the cam is operable to linearly drive the lift finger between a deactuated position and an actuated position, and a locking mechanism operable to selectively retain the lift finger in the deactuated position. The locking mechanism includes an interface member engaged with the lift finger such that movement of the lift finger moves the interface member between a home position and an offset position, a blocking member operable to selectively prevent movement of the interface member from the home position, and a driver configured to move the blocking member between a blocking position and an unblocking position to thereby lock and unlock the trim assembly.