Movable Limit Switch for Elevator Overtravel Maintenance Access

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Solution Overview

Problem

Elevator systems face limitations in maintenance accessibility due to restricted overtravel distances, preventing mechanics from reaching components at higher elevations within the elevator shaft during normal operation, necessitating enhanced mechanisms for safe and efficient maintenance.

Innovation Solution

An elevator overrun system that includes a movable body with a limit switch, secured to a fixed body via a mounting bracket, allowing the elevator car to be moved beyond standard safety limits by adjusting the limit switch's position, enabling access to higher levels within the elevator shaft for maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the overtravel distance is fixed to prevent the elevator car from rising above a specific level, then safety is improved, but maintenance accessibility to higher components deteriorates

Engineering Contradiction:
ImprovesafetyVSAvoidmaintenance accessibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The limit switch is made movable rather than fixed, allowing it to be repositioned between a first position (providing normal overtravel protection) and a second position (allowing extended overtravel for maintenance). This dynamic adjustment resolves the contradiction by enabling the system to switch between safety-oriented and maintenance-oriented configurations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The overtravel distance parameter is made variable through the movable limit switch mechanism. By changing the position of the limit switch, the maximum overtravel distance can be adjusted between a restricted value (for safety) and an extended value (for maintenance access), thus resolving the contradiction between fixed safety limits and flexible maintenance needs.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If the limit switch position is fixed, then system simplicity is improved, but adaptability to different maintenance needs deteriorates

Engineering Contradiction:
Improvesystem simplicityVSAvoidadaptability to maintenance needs
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The limit switch is designed with movable mounting capabilities, allowing repositioning between a first position for normal operation and a second position for extended maintenance access. This dynamic feature provides adaptability without requiring complete system redesign, balancing complexity and versatility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The limit switch mechanism serves multiple functions: it provides normal overtravel protection during regular operation and enables extended overtravel during maintenance operations. This multi-functionality increases adaptability to different operational needs while maintaining a relatively simple overall system structure.

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

Data Source

PatentEP3401260B1Elevator overrun systems
Publication Date: 2023.08.09 OTIS ELEVATOR CO
  • EP3401260B1 patent drawingFigure 1
  • EP3401260B1 patent drawingFigure 2A~2C
  • EP3401260B1 patent drawingFigure 3A~3B

AI summary

Elevator overrun systems having a first body arranged to be fixedly mounted to a portion of an elevator system or elevator shaft, a second body positioned within the first body and moveable from a deployed state to a retracted state relative to the first body, and a limit switch located at a distal end of the second body, the limit switch configured to interact with a component of an elevator system to prevent movement of an elevator car.