Elevator Traction System C-Sheave Layout for Hoistway Utilization

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Solution Overview

Problem

Existing elevator traction systems face challenges in maximizing hoistway utilization and accommodating double-door systems in small spaces, particularly with the 4:1 elevator traction system, where space efficiency and balanced force distribution are compromised.

Innovation Solution

The proposed elevator traction system features a unique sheave layout with a C-shaped structure and additional tension sheaves to increase wrap angles and prevent rope deflection, allowing for a more compact car side wheel train and enabling counter-weight placement in the middle of the hoistway, facilitating a double-door elevator system in narrow spaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a traditional 4:1 elevator traction system is used, then the elevator can operate with standard hoistway dimensions, but the hoistway utilization rate is low and space occupation is excessive

Engineering Contradiction:
Improvehoistway utilization rateVSAvoidspace occupation
Core Design Contradiction:
Area of stationary objectVSVolume of moving object

Solution Approach 1:

The patent applies dimensionality change by transitioning from a traditional linear arrangement of sheaves to a compact C-shaped layout where sheaves are positioned in a multi-dimensional configuration. The traction sheave, guide sheave, and car top sheave are arranged to form a C-shape that utilizes vertical and horizontal space more efficiently, reducing the overall footprint in the hoistway while maintaining functional requirements.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent implements nesting by positioning the car top sheave within the C-shaped structure formed by the traction sheave and guide sheave. The car top sheave is nested in the space between these two sheaves, allowing multiple functional elements to occupy overlapping or adjacent spatial zones, thereby maximizing hoistway utilization and minimizing total space occupation.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Area of stationary object

If sheaves are arranged in a compact C-shaped layout, then hoistway utilization is improved, but rope deflection may occur due to insufficient wrap angle

Engineering Contradiction:
Improvehoistway utilization rateVSAvoidrope deflection prevention
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent introduces tension sheaves as intermediary elements between the main sheaves and the rope. These tension sheaves serve as mediators that apply additional tension forces to the rope, ensuring proper wrap angles are maintained on the traction and guide sheaves. The tension sheaves act as intermediate force application points that prevent rope deflection and slippage while allowing the compact C-shaped arrangement to be maintained.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the counter-weight is placed in the middle of the hoistway, then a double-door elevator system can be enabled, but the force balance and tension distribution become more complex

Engineering Contradiction:
Improvedouble-door elevator capabilityVSAvoidtension distribution complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent employs asymmetry in the sheave layout and tension distribution to accommodate the counter-weight positioned in the middle of the hoistway. The C-shaped arrangement of sheaves creates an asymmetric force distribution pattern that naturally balances the loads on either side of the counter-weight. The tension sheaves are strategically positioned to create asymmetric tension forces that compensate for the unbalanced configuration, enabling double-door operation while managing the complexity of force distribution.

Inventive Principle:
Principle #4Asymmetry

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

This layout enhances hoistway utilization by reducing space occupation, improving force balance, and enabling the installation of double-door elevators in shallow hoistways by optimizing sheave placement and tension distribution.

Implementation Method 1

a rope, wherein the rope is successively wrapped around the first sheave, the second sheave, the third sheave, the first transition sheave, the second transition sheave, the fourth sheave, and the fifth sheave

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3476789B1Traction system for elevator and elevator
Publication Date: 2022.03.02 OTIS ELEVATOR CO
  • EP3476789B1 patent drawingFigure 1
  • EP3476789B1 patent drawingFigure 2
  • EP3476789B1 patent drawingFigure 3

AI summary

The present invention provides an elevator traction system and an elevator system. The elevator traction system includes: a car side wheel train; a transition wheel train; a counter-weight side wheel train; and a rope including a first end and a second end that are fixed to the top of a hoistway, the rope passing through the car side wheel train, the transition wheel train, and the counter-weight side wheel train sequentially, the car side wheel train including a first sheave and a third sheave that are fixed to the top of a car and a second sheave that is fixed to the top of the hoistway, wherein the first sheave and the third sheave are arranged to be parallel to each other and perpendicular to the second sheave. The elevator traction system and the elevator system according to embodiments of the present invention have a compact layout and a high hoistway utilization rate.