Elevator Safety Control Using Multi-System Door Switches

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Solution Overview

Problem

Conventional elevator safety systems require additional equipment to detect movement of maintenance workers into the hoistway, increasing costs.

Innovation Solution

An elevator safety controlling apparatus that utilizes existing car gate switches and landing door switches to detect movement of maintenance workers by monitoring the open or closed state of car and landing doors, enabling automatic operation disabling when necessary, thereby reducing the need for extra equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional equipment is installed to detect movement of maintenance workers into the hoistway, then detection reliability is improved, but device complexity and cost increase

Engineering Contradiction:
Improvedetection reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes existing door switches serve dual purposes: their primary function of detecting door open/closed states for normal operation, and a secondary function of detecting maintenance worker entry into the hoistway. By monitoring the state sequence of car door switch and landing door switches, the system can identify when maintenance workers enter the hoistway without requiring additional detection equipment, thus resolving the contradiction between detection reliability and device complexity

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

Solution Approach 2:

The system uses its own existing sensing capabilities (door switches) to detect conditions that would normally require separate detection equipment. The door switches 'serve themselves' by providing information about both door status and maintenance worker presence, eliminating the need for external detection devices and reducing overall system complexity while maintaining reliability

Inventive Principle:
Principle #25Self-service

2Reliability

If additional equipment is installed to detect movement of maintenance workers into the hoistway, then detection reliability is improved, but cost increases

Engineering Contradiction:
Improvedetection reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent makes existing door switches serve dual purposes: their primary function of detecting door open/closed states for normal operation, and a secondary function of detecting maintenance worker entry into the hoistway. By monitoring the state sequence of car door switch and landing door switches, the system can identify when maintenance workers enter the hoistway without requiring additional detection equipment, thus resolving the contradiction between detection reliability and device complexity

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

Solution Approach 2:

The system uses its own existing sensing capabilities (door switches) to detect conditions that would normally require separate detection equipment. The door switches 'serve themselves' by providing information about both door status and maintenance worker presence, eliminating the need for external detection devices and reducing overall system complexity while maintaining reliability

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2671836B1Safety control device for elevator
Publication Date: 2021.03.24 MITSUBISHI ELECTRIC CORP
  • EP2671836B1 patent drawingFigure 1
  • EP2671836B1 patent drawingFigure 2
  • EP2671836B1 patent drawingFigure 3

AI summary

In an elevator safety controlling apparatus, a plurality of landing door switches are divided into a plurality of systems. A safety controlling portion can recognize opening of landing doors independently for each of the systems of the landing door switches. The safety controlling portion detects movement of maintenance workers into a hoistway if the landing door switches of any of the systems indicate an open door state when the car gate switch indicates a closed door state, and if the landing door switches in two or more of the systems indicate an open door state when the car gate switch indicates an open door state.