Elevator Fault Classification from Safety Chain and Drive Timing

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Solution Overview

Problem

Existing elevator systems face challenges in accurately and quickly classifying faults due to the independent operation of safety chains, which can lead to misclassification of drive hardware issues as safety chain breaks, delaying diagnosis and repair.

Innovation Solution

An elevator system that utilizes both drive information and safety chain information to classify faults, considering the order and timing of information receipt, and includes a control device to issue safety chain break commands and analyze electrical safety chain signal properties for precise fault identification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the safety chain operates independently to control drive hardware, then safety function is ensured, but fault classification accuracy deteriorates due to misinterpretation of safety chain breaks as drive hardware faults

Engineering Contradiction:
Improvesafety functionVSAvoidfault classification accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary mechanism (control device with integrated monitoring) that mediates between the safety chain and drive control software. This intermediary receives and correlates information from both sources, preventing the drive control software from misinterpreting safety chain breaks as drive hardware faults, thus resolving the contradiction between maintaining safety function and improving fault classification accuracy

Inventive Principle:
Principle #24Intermediary (Mediator)

2Difficulty of detecting and measuring

If drive control software monitors power output independently, then drive system monitoring is achieved, but diagnosis time increases due to confusion between safety chain breaks and drive hardware faults

Engineering Contradiction:
Improvedrive system monitoringVSAvoiddiagnosis time
Core Design Contradiction:
Difficulty of detecting and measuringVSLoss of time

Solution Approach 1:

The patent merges the monitoring functions of the safety chain and drive control software into a single integrated control device. This combination allows simultaneous monitoring of both safety chain status and drive system parameters, enabling accurate differentiation between safety chain breaks and drive hardware faults, thereby reducing diagnosis time while maintaining comprehensive monitoring capability

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3915916B1Fault classification in elevator systems
Publication Date: 2025.11.12 OTIS ELEVATOR CO
  • EP3915916B1 patent drawingFigure 1
  • EP3915916B1 patent drawingFigure 2
  • EP3915916B1 patent drawingFigure 3

AI summary

An elevator system (2, 102) is provided which comprises a drive system (10) comprising one or more drive components (11, 13) and drive hardware (15) for controlling the supply of power to the one or more drive components (11,13), a safety chain (16) arranged to break and thus interrupt a supply of power to the one or more drive components (11, 13) unless all of one or more safety condition(s) is satisfied; and a control device (12). The control device (12) is arranged to receive drive information from the drive hardware (15) indicative of a drive system fault; to receive safety chain information from the safety chain (16) indicative of a safety chain break; and to detect and classify a fault in the elevator system (2, 102) using the drive information and the safety chain information.