Mode-Switchable Door Strike Lever Stops
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Solution Overview
Problem
Existing electric door strike mechanisms require complex reconfiguration and are vulnerable to tampering when switching between fail-safe and fail-secure modes, often requiring repositioning of actuators and being prone to component binding due to debris accumulation.
Innovation Solution
A mode-switchable electric door strike design where stops are positioned within the housing to limit the actuation range of release levers, allowing seamless switching between modes without repositioning actuators, and incorporating magnets to collect metal particles and prevent binding, with solenoid or motor-driven release levers engaging close to their pivot axes for enhanced security and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If stops are positioned within the housing to limit actuation range of release levers for mode switching, then ease of operation is improved, but device complexity increases due to internal reconfiguration requirements
Solution Approach 1:
The stop positions are made movable rather than fixed, allowing the mechanism to dynamically reconfigure between fail-safe and fail-secure modes by simply repositioning the stops along the release lever travel path. This dynamic positioning enables mode switching without requiring complex reconfiguration of the entire mechanism.
Solution Approach 2:
The release lever actuation range is segmented into distinct zones defined by stop positions. By positioning stops at different locations along the lever's travel path, the mechanism creates separate operational modes (fail-safe and fail-secure) without requiring separate mechanisms for each mode.
2Reliability
If release levers engage close to their pivot axes for enhanced security, then reliability is improved, but the actuation stroke required increases
Solution Approach 1:
The solenoid actuator is designed to provide more than enough force to move the release lever the full required stroke. By using an actuator with excessive capability, the system can engage the release lever close to the pivot axis for enhanced security while still achieving the necessary movement within acceptable stroke limits.
3Ease of manufacture
If metal particles are allowed to accumulate within the housing, then manufacturing simplicity is maintained, but reliability deteriorates due to component binding
Solution Approach 1:
Metal particles generated by wear are converted from harmful debris that causes binding into useful magnetic attractants. By incorporating magnets in the housing, the particles are drawn to and collected by the magnets, transforming the harmful accumulation problem into a beneficial self-cleaning mechanism that maintains reliability without complex manufacturing.
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
Simplifies mode switching between fail-safe and fail-secure operations while enhancing security by reducing tamperability and minimizing component binding, ensuring reliable operation without the need for actuator repositioning and effective debris management.
Implementation Method 1
A solenoid actuator may be used to move the release lever between a first position in which the transmission lever is locked and a second position in which the transmission lever is unlocked
Implementation Method 2
A magnet may be provided within the housing to attract and collect metal particles generated by wear of the latch over the lifetime of the assembly
Data Source
AI summary
A lockable keeper arm extends across an opening of a door strike housing. A pivotally mounted transmission lever releasably engages the keeper arm. A pivotally mounted release lever releasably engages the transmission lever. An actuator engages the release lever at a point between the release lever pivot and the transmission lever and drives the release lever between alternate positions in either fail-safe and fail-secure modes. The actuator engagement point may be closer to the release lever pivot point than the transmission lever engagement point. A stop limits travel of the release lever and may be positioned in alternate positions. In alternate positions, the primary lever unlocks the keeper arm when the actuator is either energized or de-energized, placing the strike in fail-safe or fail-secure modes. Magnets may be mounted inside the housing to attract metal particles. The actuator may be an electric solenoid or a motor.