Elevator Car Position Control with Open Door Brake
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Solution Overview
Problem
Elevator systems face challenges in controlling the movement of an elevator car when it is parked at a landing, particularly when the doors are open, to ensure compliance with revised industry standards and prevent uncontrolled movement, which existing solutions may not adequately address.
Innovation Solution
The system employs a controller that uses door zone detectors and level sensors to determine the position of the elevator car relative to the landing and applies a machine brake to prevent uncontrolled movement when the car is near a landing and the door is open, allowing for releveling and door operation before the car stops, and requiring a manual reset for resuming service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake device is applied to limit movement of the elevator car when the door is open, then safety and compliance with standards are improved, but the complexity of the control system increases
Solution Approach 1:
The control system continuously monitors the position of the elevator car using door zone detectors and level sensors, comparing actual position with desired position. When unauthorized movement is detected, the system provides feedback to the brake device to apply braking force, creating a closed-loop control system that ensures safety while maintaining simplicity through automated monitoring and response
Solution Approach 2:
The control system automatically detects unauthorized movement and triggers the brake device without requiring external intervention. The system self-monitors through door zone detectors and level sensors, and self-corrects by applying brake force when needed, reducing the need for complex external control mechanisms while maintaining safety
2Reliability
If the elevator car position is strictly controlled at the landing, then compliance with standards is improved, but the ease of operation for passengers is reduced
Solution Approach 1:
The control system dynamically adjusts its response based on the operational context. During normal door operation, the system allows controlled movement for releveling and door opening/closing. However, when unauthorized movement is detected, the system dynamically switches to a restrictive mode applying brake force, thus maintaining both passenger convenience and standard compliance
3Measurement precision
If door zone detectors and level sensors are used to monitor car position, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The door zone detectors and level sensors serve multiple functions: they detect the presence of the car in the door zone, measure the precise position of the car relative to the landing, and provide input for the control algorithm. This multi-functionality reduces the need for separate specialized sensors, maintaining measurement precision while limiting the increase in system complexity
Data Source
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AI summary
An exemplary method is useful for controlling movement of an elevator car in an elevator system that includes a machine that selectively moves the elevator car and a machine brake that selectively resists movement of the elevator car. The method includes determining whether the elevator car is near a landing and determining whether a door of the elevator car is open. A desired operation includes desired movement of the elevator car while the elevator car is near the landing and the door is open. A determination is made whether the elevator car moves other than according to the desired movement. The machine brake is applied for stopping movement of the elevator car responsive to elevator car movement other than the desired movement while the elevator car is near the landing and the door is open.