Elevator Speed Sensor Preventive Maintenance
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Solution Overview
Problem
Elevator systems face challenges in ensuring accurate absolute positioning and continuous operation of speed sensor systems, leading to potential service interruptions due to sensor failures, which can compromise safety and passenger comfort.
Innovation Solution
A method for preventive maintenance of elevator speed sensor systems using at least two independent sensors to monitor and calculate a sensor system performance indicator, allowing for timely calibration or repair before failure, and a system architecture that includes a remote connection to a maintenance server for scheduling maintenance based on performance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single speed sensor system is used for absolute positioning, then the device complexity is reduced, but the reliability decreases due to potential sensor failures causing service interruptions
Solution Approach 1:
The patent applies local quality by making the two sensor systems independent of each other, allowing each sensor to function autonomously. This independence ensures that if one sensor fails, the other can continue to provide absolute positioning information, thereby improving reliability without requiring a complex redundant system where sensors are interconnected and interdependent.
Solution Approach 2:
The patent implements preliminary action by continuously monitoring the operational status and accuracy of the speed sensor system before actual failure occurs. The control unit detects deviations in sensor performance and can trigger maintenance actions or switch to backup sensors proactively, preventing service interruptions rather than reacting after failure.
2Measurement precision
If high accuracy absolute positioning is implemented, then the measurement precision is improved, but the device complexity increases due to additional sensors and monitoring systems
Solution Approach 1:
The patent applies universality by designing the speed sensor system to serve multiple functions: it provides both speed measurement for drive control and absolute positioning information for safety functions. The same sensor infrastructure is used for both purposes, eliminating the need for separate dedicated positioning sensors and thereby improving measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The patent implements feedback by continuously monitoring the operational status and accuracy of the speed sensor system. The control unit receives feedback signals from the sensors, compares them against expected values, and can detect deviations indicating potential failures. This feedback mechanism enables proactive maintenance and ensures high measurement precision through continuous validation.
3Reliability
If continuous monitoring of sensor performance is implemented, then the reliability is improved, but the use of energy increases due to continuous data processing
Solution Approach 1:
The patent applies self-service by enabling the speed sensor system to monitor its own operational status and accuracy without requiring external intervention. The control unit automatically detects sensor deviations, identifies potential failures, and can trigger maintenance actions autonomously. This self-monitoring capability improves reliability while minimizing energy consumption by avoiding continuous active processing and only engaging when deviations are detected.
Data Source
AI summary
A method for preventive maintenance of an elevator speed sensor system includes at least a first and a second sensor, which are independent of each other. The method includes: determining a reference distance for an elevator car travel between a first door zone and a second door zone, during the elevator car travel, defining continuously a first elevator car speed information from the first sensor and a second elevator car speed information from the second sensor, calculating a cumulative sensor system error by integrating the difference between the first elevator car speed information and the second elevator car speed information, and dividing the cumulative sensor system error with the reference distance to obtain a sensor system performance indicator.