Segmented Sheave Assembly with Wave Springs

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Solution Overview

Problem

In elevator applications, traditional idler sheaves with a single large tube and multiple grooves face challenges in bearing installation and load distribution, leading to reduced bearing life and increased bending stress, especially as duty tables expand and sheaves become smaller.

Innovation Solution

A unitized segmented sheave assembly featuring sheaves arrayed in a side-to-side formation with bearings and spacers, a unifying sleeve for easy installation, and an elastic element like a wave spring to manage stress, allowing customization of groove numbers and improved load distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single large tube is machined into multiple grooves to create idler sheaves, then the sheave structure is simplified, but bearing installation becomes difficult and bearing life decreases

Engineering Contradiction:
Improvesheave structureVSAvoidbearing life
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the traditional single-tube sheave into multiple separate groove components that can be independently manufactured and assembled. Each groove is a separate element that can be pre-assembled with bearings in a controlled environment, then stacked and secured to the shaft. This segmentation allows bearings to be installed on individual grooves rather than forcing them into a large tube in the field, significantly improving bearing life and installation quality.

Inventive Principle:
Principle #1Segmentation

2Reliability

If individual grooves are created with separate bearings to increase bearing life, then the number of bearings increases, but load per bearing decreases and shaft bending stress increases

Engineering Contradiction:
Improvebearing lifeVSAvoidshaft bending stress
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent combines multiple groove components with their respective bearings into a unified stacked assembly that is secured to the shaft. The grooves are arranged in a specific pattern around the shaft and connected through the stacking mechanism, creating a integrated structure where the load is distributed across multiple contact points. This merging approach maintains the benefits of separate bearings for extended life while distributing shaft bending stress through the combined structural support of all grooves working together.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If multiple bearings and spacers are used between sheaves to support individual grooves, then bearing life increases, but installation complexity and time increase

Engineering Contradiction:
Improvebearing lifeVSAvoidinstallation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary assembly of bearings with each groove component in a controlled manufacturing environment before field installation. The grooves are pre-assembled with their bearings and positioned relative to each other, creating ready-to-install modules. In the field, these pre-assembled groove modules are simply stacked onto the shaft and secured, eliminating the need for complex bearing installation procedures and spacer positioning during field work. This preliminary action dramatically reduces installation time while maintaining the reliability benefits of separate bearings.

Inventive Principle:
Principle #10Preliminary action

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 solution enhances bearing life, simplifies installation, reduces installation time, and provides customizable configurations, while addressing bending stress and cost reduction through non-metallic components and improved tension equalization.

Implementation Method 1

each sheave includes at least one of an elastic element axially interposed between a set of bearings and a set of integral bearings. In accordance with additional embodiments, the elastic element includes a wave spring.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4056513B1Unitized segmented sheave assembly
Publication Date: 2024.07.24 OTIS ELEVATOR CO
  • EP4056513B1 patent drawingFigure 1
  • EP4056513B1 patent drawingFigure 2~3
  • EP4056513B1 patent drawingFigure 4~7

AI summary

A unitized segmented sheave assembly is provided. The unitized segmented sheave assembly comprises a plurality of sheaves arrayed in a side-to-side formation which is consistent with a configuration of the elevator system, each sheave comprising a wave spring axially interposed between a set bearings, an exterior running surface and radial flanges bracketing the exterior running surface; a plurality of spacers interleaved between neighboring ones of the plurality of sheaves to form gaps therein, respective inner races of the set of bearings of each one of the plurality of sheaves and respective interior portions of each one of the plurality of spacers cooperatively forming an interior annular surface; and a sleeve disposable in abutment with the interior annular surface.