Inductive Elevator Positioning for Cable Stretch Compensation
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Solution Overview
Problem
Existing elevator systems lack an effective method to accurately align the elevator car floor with the building floor, leading to potential safety issues and inefficiencies, especially in emergency situations, as they rely on primary control systems that may fail or require manual adjustments.
Innovation Solution
The implementation of an inductive sensing system using multiple sensors and targets, which allows for accurate positioning and leveling of the elevator car without manual repositioning of sensors and targets, and operates in emergency modes to ensure safe evacuation by dynamically adjusting the door zone length and detecting cable stretch for maintenance alerts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual repositioning of sensors and targets is required to adjust leveling, then positioning accuracy can be achieved, but system complexity and maintenance difficulty increase
Solution Approach 1:
The inductive sensing system automatically detects cable stretch and compensates for positioning drift without requiring manual intervention. The system self-adjusts by detecting changes in the magnetic field caused by cable elongation and dynamically recalibrates the door zone parameters, eliminating the need for manual sensor repositioning while maintaining positioning accuracy.
Solution Approach 2:
The system continuously monitors the position of the elevator car using inductive sensors and targets, and feeds this information back to the control system. The control system processes this feedback to detect cable stretch and automatically adjusts the door zone length and positioning parameters, creating a closed-loop system that maintains accuracy without manual intervention.
2Productivity
If primary control systems are used for elevator operation, then normal operation efficiency is maintained, but reliability decreases in emergency situations
Solution Approach 1:
The inductive sensing system is designed to operate independently of the primary control system, providing a backup positioning and door zone detection capability. This redundant system is prepared in advance to take over if the primary control system fails, ensuring continued safe operation and evacuation capability during emergencies.
Solution Approach 2:
The inductive sensing system acts as an intermediary between the elevator car position and the door control system. It provides a reliable, independent method for detecting when the car is in the door zone, serving as a mediator that can operate even when the primary control system is compromised, thereby enhancing overall system reliability.
3Device complexity
If fixed door zone length is used, then system simplicity is maintained, but adaptability to different operating conditions decreases
Solution Approach 1:
The door zone length is made dynamic rather than fixed. The control system automatically adjusts the door zone length based on detected cable stretch and actual car position feedback. This dynamic adjustment allows the system to adapt to different operating conditions and wear states while maintaining the simplicity of the inductive sensing approach, requiring no additional hardware complexity.
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
This solution enables precise alignment of the elevator car with the building floor, enhances safety by allowing operation in emergency modes, and automatically adjusts for cable stretch, reducing the need for manual intervention and ensuring reliable operation.
Implementation Method 1
inductive sensors configured to pass ferrous metal targets
Data Source
AI summary
An elevator moves through a hoistway with one or more sensors positioned so that they pass by one or more targets that are in fixed positions relative to the hoistway. As they pass, an inductive current is generated, giving the elevator's control circuitry precise information as to the vertical position of the elevator car. The control system adjusts the raising and/or lowering of the elevator car based on that position information and any discrepancy between it and the supposed position at which the control system had believed the car was. Discrepancies are accumulated over time as an indication of cable stretch, and when the stretch exceeds a particular threshold, an alarm is raised for maintenance. The control system also defines a “door zone” around each landing where, based on the precise height measurement achieved herein, it is safe under the circumstances to open the doors of the car.