Elevator Sheave Traction Monitoring via Targeted Section Detection
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Solution Overview
Problem
Existing elevator systems face difficulty in detecting minute slippage of the main rope relative to the sheave, especially during the initial stage of traction performance reduction, making it challenging to promptly identify declines in traction performance.
Innovation Solution
An elevator apparatus equipped with a traction machine, a control unit, a section specification unit, a sheave rotation detector, and a determination unit that identifies a determination target section based on load weight and acceleration conditions, allowing for the detection of sheave rotation and subsequent assessment of traction performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional method of computing ascent and descent travel distance values from encoder pulse signals is used, then the system can detect main rope slippage, but it cannot detect minute amounts of slippage in the initial stage of traction performance reduction
Solution Approach 1:
The system performs preliminary action by selecting specific determination target sections where the car accelerates upward or decelerates downward under heavy load conditions. These pre-selected sections create optimal conditions for detecting minute slippage before it becomes significant, enabling early detection of traction performance reduction.
Solution Approach 2:
The invention changes the detection parameters by focusing measurement on specific travel sections with controlled acceleration and load conditions rather than measuring continuously throughout all travel. This parameter change amplifies the detectability of minute slippage by creating conditions where slippage effects are maximized and most measurable.
2Reliability
If the system monitors slippage continuously throughout all travel sections, then it may detect slippage earlier, but it increases the complexity of the detection system and data processing
Solution Approach 1:
The detection system is segmented by dividing the car's travel path into specific determination target sections where detection is performed. Instead of continuous monitoring throughout all travel, the system focuses only on critical sections where the car accelerates upward or decelerates downward under heavy load, simplifying the overall system while maintaining reliability.
Solution Approach 2:
The system applies partial action by performing detection only in specific critical sections rather than throughout the entire travel range. This partial monitoring approach is sufficient to detect traction performance reduction while avoiding the complexity of comprehensive continuous monitoring.
Data Source
AI summary
An elevator apparatus includes: a traction machine including a sheave around which a middle portion of a main rope from which a car and counterweight are suspended is wound; a controller configured to control travel of the car; a section specification unit configured to specify a determination target section serving as a travel section, including at least a travel position of the car, satisfying a predetermined determination execution condition; a sheave rotation detector configured to detect a sheave rotation amount; and a determinator configured to determine traction performance of the sheave based on the sheave rotation amount detected during travel of the car in the determination target section. The determination execution condition is to have a load weight and an acceleration of the car that cause direction of an acceleration vector of one of a car side and a counterweight side heavier than the other to match an ascent direction.