Elevator Car Door Control for Uniform Panel Speed
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Solution Overview
Problem
Elevator car door systems with thrust crank drives experience non-uniform movement and varying kinetic energy due to changing translation ratios, leading to inefficient closing and opening times and potential safety issues with excessive force application.
Innovation Solution
A control device that adjusts the electric motor's rotational speed and torque to maintain substantially constant door panel speed and actuation force throughout the movement path, compensating for kinematic irregularities and ensuring safe operation by monitoring and adapting to actual motor variables and angular positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If constant rotational speed is used for the electric motor, then the door panels move at non-uniform speed due to varying translation ratios, but the control system remains simple
Solution Approach 1:
The control system dynamically adjusts the motor rotational speed based on the instantaneous translation ratio of the thrust crank drive. By making the speed profile adaptive rather than fixed, the system compensates for kinematic irregularities and achieves uniform door panel movement throughout the opening/closing cycle.
Solution Approach 2:
The control system incorporates feedback from sensors that monitor the actual door panel position and motor rotational speed. This feedback loop enables real-time adjustments to maintain the desired speed profile, compensating for variations in the thrust crank drive's translation ratio during operation.
2Productivity
If the door panels are moved faster to reduce closing and opening times, then productivity improves, but the maximum kinetic energy exceeds permissible values creating safety issues
Solution Approach 1:
The system employs a dynamic speed profile that adapts to the instantaneous kinetic energy levels. During portions of the cycle where kinetic energy is acceptable, the door panels move at higher speeds to reduce overall operation time. When kinetic energy approaches permissible limits, the speed is automatically reduced, ensuring safety while maximizing productivity.
Solution Approach 2:
The control system continuously monitors and adjusts the motor rotational speed parameter based on calculated kinetic energy levels. By dynamically changing this critical parameter, the system optimizes the balance between operation speed and safety, preventing excessive kinetic energy while minimizing total door operation time.
3Force
If constant torque is delivered by the electric motor, then power consumption is simplified, but the maximum actuation force varies due to changing translation ratios
Solution Approach 1:
The control system dynamically adjusts the motor torque output based on the instantaneous translation ratio of the thrust crank drive. By making the torque profile adaptive rather than constant, the system compensates for kinematic variations and maintains uniform actuation force on the door panels throughout the movement cycle.
Solution Approach 2:
The system continuously modifies the motor torque parameter in response to changing translation ratios. This dynamic parameter adjustment ensures that the actuation force remains consistent despite the varying mechanical advantage of the thrust crank drive at different positions in the door opening/closing cycle.
Data Source
AI summary
An elevator car has an access opening, a car door for closing the access opening, which door has at least one door panel that can be displaced parallel to the access opening, a thrust crank drive for displacing the at least one door panel between an open position and a closed position, an electric motor for driving the thrust crank drive, and a control device for actuating the electric motor. The control device actuates the electric motor so that a displacement velocity of the at least one door panel is substantially constant over the entire displacement path between the open position and the closed position of the door panel.