Elevator Door Dynamic Braking During Power Failure
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Solution Overview
Problem
Elevator doors tend to close abruptly during power outages, causing noise and potential damage due to the lack of braking action, and existing solutions like friction brakes or motor generators are costly or require special designs.
Innovation Solution
A method and device that utilize an electrical buffer connected between the door drive's control unit and power supply to store energy during normal operation, releasing it as backup power during a power outage to control the door's closing movement, allowing the door drive to act as a dynamic brake.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a friction brake is added to prevent noise during power failure, then noise is reduced, but device complexity and cost increase
Solution Approach 1:
The door drive motor serves dual purposes: normal driving function and emergency braking function during power failure. The control unit enables the motor to act as a dynamic brake by controlling current flow during unpowered closing, eliminating the need for separate friction brake components
Solution Approach 2:
The door drive motor is designed to perform multiple functions: it drives the door during normal operation and acts as a dynamic brake during power failure. This multi-functionality eliminates the need for dedicated friction brake components while reducing overall system complexity
2Object-affected harmful factors
If the door drive is permanently wired as a generator to brake during power outage, then braking action is achieved, but device complexity and manufacturing requirements increase
Solution Approach 1:
The door drive's braking function is dynamically activated only when needed (during power failure). The control unit detects power loss and switches the motor to generator mode temporarily, allowing flexible adaptation without permanent structural modifications or special design requirements
Solution Approach 2:
The control unit changes the electrical parameters of the door drive motor by altering current flow characteristics during power failure. This enables the motor to transition from motor mode to generator mode dynamically, achieving braking without permanent wiring changes or special design modifications
3Device complexity
If no braking action is applied during power failure, then device complexity is reduced, but harmful noise and potential damage occur
Solution Approach 1:
The control unit continuously monitors the door's closing speed during power failure and adjusts the braking force accordingly. By measuring actual door movement and feedbacking to the control algorithm, the system achieves smooth controlled stopping without excessive braking force that would increase complexity
4Object-affected harmful factors
If an electrical buffer with control electronics is added to enable dynamic braking, then noise is reduced and braking control is achieved, but device complexity increases
Solution Approach 1:
The electrical buffer and control electronics are integrated into the existing door drive control unit. By merging the backup power storage and control functions with the existing control architecture, the system achieves dynamic braking capability without adding separate complex subsystems
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
Enables a cost-effective and easy retrofit solution for elevator doors to achieve smooth closing during power failures without additional modifications, reducing noise and damage.
Implementation Method 1
electrical energy is buffered during normal operation of the door and, in response to a power failure, the energy is provided as substitute energy for a control unit of the door
Implementation Method 2
the door drive's control unit is designed so that, during a power outage, the door drive can essentially rotate freely, and is locked once the power supply is restored
Data Source
Figure 1
AI summary
The present invention relates to a method for controlling a closing movement of a door (104) of a lift car (100) during a power failure, wherein, during a control operation of the door (104), electrical power is buffered and, in response to the power failure, the power is provided as backup power (128) to a control device (110) of the door (104) in order to decelerate the closing movement.