Elevator Door Drive Control for Chimney Effect Compensation
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Solution Overview
Problem
Elevator doors in tall buildings face difficulties in opening and closing due to air resistance caused by the chimney effect, which can exceed the maximum intended closing force, leading to operational failures, as existing systems do not differentiate between obstacles and external influences like wind and temperature changes.
Innovation Solution
An elevator system equipped with a sensor unit to detect external conditions such as pressure, temperature, and wind, and an evaluation unit to adjust the reference driving force based on these measurements, ensuring the door drive can handle increased air resistance without exceeding permissible forces, allowing for safe operation even in strong chimney effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the door drive uses a fixed maximum closing force, then the door can close reliably under normal conditions, but the door cannot open or close when air resistance from the chimney effect exceeds this fixed force
Solution Approach 1:
The door drive control is changed from a fixed maximum closing force to a dynamic closing force that automatically adapts to external conditions. The control unit continuously monitors the actual closing force and adjusts the motor output force in real-time based on detected external influences such as chimney effect, wind, or obstacles, enabling the door to operate reliably across varying environmental conditions without requiring manual intervention or fixed force settings.
Solution Approach 2:
A feedback mechanism is implemented where the actual closing force is continuously measured and fed back to the control unit. The control unit compares the actual closing force with the target closing force and adjusts the motor output accordingly. This closed-loop control enables the door drive to automatically compensate for external influences like chimney effect or wind, maintaining reliable door operation while adapting to changing environmental conditions.
2Object-affected harmful factors
If the door drive increases the closing force to overcome air resistance, then the door can close in strong chimney effects, but the door may exceed the permissible force and damage obstacles or the door itself
Solution Approach 1:
The feedback mechanism continuously monitors the actual closing force and compares it with the permissible force limit. When the actual closing force approaches the limit, the control unit automatically reduces the motor output to prevent exceeding the permissible force. This prevents damage to obstacles or the door while still enabling the door to overcome air resistance from chimney effects, wind, or obstacles through controlled force adjustment.
Solution Approach 2:
The control unit dynamically changes the motor output force parameter based on detected external conditions and the current state of the door movement. Instead of using a fixed maximum force, the system adjusts the force parameter in real-time to match the actual requirements, increasing force when needed to overcome air resistance and reducing it when approaching the permissible limit, thus preventing damage while maintaining operational capability.
3Device complexity
If the system treats all force deviations as obstacles, then obstacle detection is simplified, but external influences like wind and temperature changes are incorrectly identified as obstacles causing false stops
Solution Approach 1:
The feedback mechanism provides continuous information about the actual closing force and compares it with expected values based on detected external conditions. The control unit uses this feedback to distinguish between force deviations caused by obstacles versus those caused by external influences like wind or temperature changes. By analyzing the pattern and magnitude of force deviations in context with environmental data, the system can accurately differentiate between true obstacles and false conditions, preventing false stops while maintaining simple obstacle detection logic.
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 adapts the reference driving force to account for changing external conditions, ensuring elevator doors can open and close reliably in tall buildings by differentiating between obstacles and external influences, preventing door failure due to air resistance.
Implementation Method 1
the sensor is suitable for measuring the motor current required to open and/or close the elevator door
Implementation Method 2
air from outside the building enters the elevator shaft, which experiences a vertical flow due to the so-called chimney effect. In most cases, warm air rises in a chimney or elevator shaft
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a lift car (1) having at least one lift door (2), having a door drive (3) for actuating the lift door (2), having a sensor (4) for detecting the motor power of the door drive (3) and having an evaluating unit (5), which determines, based on the motor power detected, whether there is a deviation in the travel profile (6) from a reference travel profile (7). According to the invention, the evaluating unit (5) is designed to determine whether a deviation occurs due to an obstacle in contact with the lift door (2) or due to altered external conditions, particularly due to altered pressure conditions and/or air flow.