Elevator Door Locking Mechanism with Cam Interlock
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Solution Overview
Problem
Existing elevator door locking systems lack a simple and reliable mechanism to prevent unintended opening of both elevator car and landing doors, especially when the car is not properly aligned with a landing, which can lead to safety issues and operational inefficiencies.
Innovation Solution
An integrated mechanical locking system with lock control elements on both the elevator car and landing doors, where a driven element on the car automatically unlocks both doors only when the car is correctly positioned at a landing, ensuring that the doors remain locked when misaligned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical locking system is used to prevent unintended door opening, then safety and reliability are improved, but the device complexity increases
Solution Approach 1:
The patent combines the locking mechanisms for both the car door and landing door into a single integrated system. The locking bar and cam mechanism serve dual functions: when the car is at a landing, the cam engages with the cam follower to unlock both doors simultaneously, eliminating the need for separate locking systems and reducing overall complexity while maintaining reliability
Solution Approach 2:
The cam mechanism acts as an intermediary element that translates the position of the car (via the driven element) into the locking/unlocking action. When the car is properly positioned, the cam rotates to engage the cam follower, which then triggers the release of both door locks through a single mechanical action, simplifying the control system
2Productivity
If the driven element is designed to unlock both doors when car is positioned correctly, then operational efficiency is improved, but the risk of unintended door opening increases
Solution Approach 1:
The system incorporates preliminary safety checks through the alignment mechanism. Before the driven element can engage the cam to unlock the doors, the car must be precisely positioned at the landing, which is verified by the alignment of the driven element with the cam mechanism. This preliminary condition prevents unintended unlocking by ensuring the car is properly positioned before door release is permitted
Solution Approach 2:
The locking system uses dynamic elements including the rotatable cam and movable locking bar that respond to the car's position. The cam rotates only when the driven element is in the correct position, and the locking bar moves dynamically between locked and unlocked states based on cam rotation, providing automatic safety control that prevents unintended door opening while maintaining operational efficiency
3Reliability
If the locking elements use pivotal motion, then reliability is improved by avoiding friction sticking, but the device complexity increases
Solution Approach 1:
The patent employs curved cam surfaces instead of flat contacting surfaces. The cam has a specifically shaped profile that rotates to engage and disengage the cam follower, replacing sliding friction with rolling contact and pivotal motion. This curved geometry eliminates friction sticking problems while the cam's rotational movement provides reliable locking and unlocking actions
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 effectively prevents unintended opening of elevator car and landing doors by ensuring that they remain locked unless the car is properly registered with a landing, enhancing safety and operational reliability.
Implementation Method 1
a cam (250) positioned on the locking bar (220) and engageable with the cam follower (240)
Implementation Method 2
a spring (230) engaged with the locking bar (220) and biased in a locking direction
Implementation Method 3
avoid erratic movement frequently encountered with translation or straight-line action induced by friction sticking at flat contacting or guiding surfaces
Data Source
AI summary
A door locking system for a freight or passenger elevator or goods lift installation having vertically spaced landings served by a vertically movable car, the landings and car each being protected by associated horizontal slide doors, a mechanical interlock device at each landing that prevents a landing door from opening without the presence of the car in registration with the landing, a door lock on the car for normally preventing the car door from opening when the car is out of registration with any landing, the interlock device being arranged to mechanically enable the door lock to release the car door to open when the car is in registration with a landing.