Inductive Elevator Door Gap Monitoring Using Eddy Current Sensing

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Solution Overview

Problem

Existing elevator door gap clearance monitoring systems are inadequate, as they fail to effectively detect and prevent excessive gaps that pose safety risks and are costly or impractical for continuous monitoring, leading to potential safety hazards and inefficient maintenance.

Innovation Solution

An inductive sensor device is integrated into the elevator door's sill profile to monitor gap clearance by inducing eddy currents in conductive surfaces, providing real-time data on gap size and trends, and communicating with a remote monitoring entity for proactive maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical or magnetic sensors are used to monitor gap clearance, then measurement precision is improved, but device complexity and cost increase making them not cost effective for widespread use

Engineering Contradiction:
Improvegap clearance detection accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex optical or magnetic sensors with a simple inductive coil that generates a magnetic field. This inductive sensing mechanism uses basic electromagnetic induction principles to detect gap clearance through changes in inductance, eliminating the need for complex optical components while maintaining measurement capability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent monitors gap clearance by detecting changes in electrical parameters (inductance, impedance) of the inductive coil rather than using complex physical measurements. By converting mechanical gap distance into electrical parameter variations, the system achieves precise measurement with simple, low-cost components

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If door safety contacts are used to detect gap clearance, then ease of operation is improved, but measurement precision deteriorates as they cannot detect excessive gaps when closed

Engineering Contradiction:
Improvedetection system operationVSAvoidgap clearance detection accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The inductive sensor provides continuous monitoring of gap clearance throughout door operation, unlike discrete safety contacts that only trigger at specific positions. The inductive coil continuously detects gap changes by monitoring ongoing electrical parameter variations, enabling both operational simplicity and precise detection

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The inductive coil acts as an intermediary between the door mechanism and detection system. It converts physical gap distance into electrical signals through electromagnetic induction, providing a bridge that maintains both ease of integration with existing door systems and high measurement precision

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If additional contacts are installed for continuous monitoring, then reliability is improved, but device complexity and maintenance requirements increase

Engineering Contradiction:
Improvecontinuous monitoring capabilityVSAvoidmonitoring system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The inductive coil serves multiple functions: it generates the magnetic field for actuation, senses gap clearance through inductance changes, and provides continuous monitoring. This multi-functionality eliminates the need for separate sensing components, achieving reliable continuous monitoring while reducing overall system complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The inductive sensing system uses the door's own magnetic environment and electrical characteristics for sensing. The coil leverages natural electromagnetic induction and changes in the door assembly's electrical properties, requiring no external power sources or complex calibration systems for reliable operation

Inventive Principle:
Principle #25Self-service

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

The inductive sensor device enables continuous, cost-effective monitoring of elevator door gaps, ensuring compliance with safety limits and facilitating preventive maintenance, thereby reducing safety risks and maintenance inefficiencies.

Implementation Method 1

The inductive sensor device may comprise an inductive coil configured to generate an alternating magnetic field that induces eddy currents in a conductive surface of the elevator door to obtain the sensor data

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an inductive coil configured to generate an alternating magnetic field that induces eddy currents in a conductive surface of the elevator door

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Data Source

PatentEP4504637B1An inductive sensor device, a method, and a system for monitoring a gap clearance of an elevator door
Publication Date: 2026.03.25 KONE OYJ
  • EP4504637B1 patent drawingFigure 1~3A
  • EP4504637B1 patent drawingFigure 3B~3D
  • EP4504637B1 patent drawingFigure 4~6

AI summary

The invention relates to an inductive sensor device (100) for monitoring gap clearance (340) of an elevator door (210). The inductive sensor device (100) is arranged in association with the elevator door (210). The inductive sensor device (100) is configured to obtain sensor data representing the gap clearance (340) of the elevator door (210) being in a closed state. The inductive sensor device (100) is further configured to:monitor the gap clearance (340) of the elevator door (210) based on the obtained sensor data, and/or provide the obtained sensor data to a remote monitoring entity (220) for monitoring the gap clearance (340) of the elevator door (210). The invention relates also to a method and a monitoring system for monitoring gap clearance (340) of an elevator door (210).