Elevator Car Working Platform Retraction to Prevent Sudden Drop

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Solution Overview

Problem

Existing elevator cars require significant manual effort to move and secure a working platform between stowed and lowered positions, posing safety risks due to potential sudden drops and complex, expensive structures.

Innovation Solution

An elevator car with a retractable working platform mechanism using pull means, including belt reels and a self-locking mechanism, that compensates for the platform's weight and prevents rapid descent, and incorporates a self-blocking mechanism to control movement, eliminating the need for scissors mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a scissors mechanism is used to move and hold the working platform, then the platform can be supported and positioned, but the structure becomes complex and expensive

Engineering Contradiction:

Improveplatform support reliabilityVSAvoidsupport structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the complex scissors mechanism from the system and replaces it with a simple pull means (rope, cable, or belt) that runs through guide elements. This extraction eliminates the mechanical complexity of linkages and joints while maintaining the essential function of platform support and positioning through tension-based restraint.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs flexible pull means in the form of ropes, cables, or belts instead of rigid mechanical linkages. These flexible elements pass through guide elements (pulleys, rings, or brackets) to provide platform support, replacing the rigid scissors mechanism with a more compliant and simpler tension-based system.

Inventive Principle:

Principle #30Flexible shells and thin films

2Ease of operation

If manual force is applied to move the working platform, then the platform can be repositioned, but large amounts of force are required and safety risks arise from sudden drops

Engineering Contradiction:

Improveplatform repositioning easeVSAvoidmanual force required

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The patent implements a counterweight mechanism where a weight is suspended from the pull means to balance the weight of the working platform. This counterbalancing reduces the manual force required to move the platform, as the operator only needs to overcome friction and minor imbalances rather than the full weight of the platform.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent introduces guide elements (pulleys, rings, or brackets) as intermediaries between the pull means and the working platform. These intermediaries redirect and distribute the tension forces, providing mechanical advantage and reducing the effort required by the operator to control platform movement.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the working platform is lowered without a retracting mechanism, then the structure is simpler, but the platform may drop rapidly causing injury

Engineering Contradiction:

Improvemechanism complexityVSAvoidinjury risk from sudden drop

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies beforehand cushioning by implementing a retracting mechanism that provides controlled resistance during platform descent. This mechanism prevents sudden drops by gradually dissipating the platform's potential energy through friction or progressive engagement, ensuring a controlled and safe lowering process before the platform reaches its final position.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The retracting mechanism is designed to automatically engage and control the platform's descent without requiring active operator intervention. The mechanism self-regulates the lowering process through inherent friction characteristics or progressive engagement features, providing safety control that operates autonomously as the platform is lowered.

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 solution allows easy and safe operation of the working platform with reduced manual effort, minimizing the risk of injury and simplifying the structure while meeting safety requirements.

Implementation Method 1

The retracting mechanism can comprise a spring mechanism for generating the retracting force. That is, a spring return force of the spring mechanism can correspond to the retracting force.

Methodology Applied

Scientific EffectSpring mechanism: Spring

Data Source

PatentUS20250382156A1Elevator car and elevator assembly

Publication Date: 2025.12.18 OTIS ELEVATOR CO

AI summary

An elevator car (1) defining an interior space (4) for accommodating passengers and/or cargo. The elevator car (1) includes a working platform (8) moveable up and down within the interior space (4), and pull means (10) mounted to the elevator car (1) above the interior space (4) and connected to the working platform (8) for moving the working platform (8) between a stowed position and a lowered position and holding the working platform (8) at an operational position. The pull means (10) includes a retracting mechanism. A retracting force of the retracting mechanism is set to compensate for the weight of the working platform (8) or less.