Two-Part Outer Ring Bearing Assembly for Axial Displacement

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Solution Overview

Problem

Existing bearing assemblies in applications like electric motors and wind-turbine generators face issues with friction corrosion and reduced grease service life due to linear contact in cylindrical roller bearings, and high costs associated with ceramic rollers, which can lead to bearing failure and increased maintenance costs.

Innovation Solution

A bearing assembly featuring two locating bearings with a two-part outer ring design, where one locating bearing has an inward and outward outer ring with different diameters, allowing axial displacement to accommodate thermal expansion and manufacturing tolerances, and utilizing deep-groove ball bearings with ceramic rolling elements and optional spring elements for improved service life and reduced friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a non-locating bearing with a sliding seat is used to allow axial displacement, then the shaft can be displaced to compensate for manufacturing tolerances and thermal expansion, but friction corrosion arises between the outer ring and housing which can block displacement and cause bearing failure

Engineering Contradiction:

Improveaxial displacement capabilityVSAvoidbearing service life

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The outer ring is divided into two separable parts: an inner outer ring and an outer outer ring. This segmentation allows the inner outer ring to move axially relative to the outer outer ring, enabling displacement compensation without sliding against the housing, thus preventing friction corrosion while maintaining adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner outer ring is nested within the outer outer ring, with the inner outer ring having a smaller diameter than the outer outer ring. This nested configuration allows the inner ring to slide axially within the outer ring's internal diameter, providing displacement capability while the outer ring remains fixed to the housing, eliminating friction corrosion issues.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Adaptability or versatility

If cylindrical roller bearings are used to accommodate axial displacement, then displacement is possible, but linear contact between inner ring, outer ring, and rollers causes reduced grease service life and increased bearing friction

Engineering Contradiction:

Improveaxial displacement capabilityVSAvoidbearing friction

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The invention uses deep groove ball bearings instead of cylindrical roller bearings. The spherical contact between balls and rings replaces the linear contact of rollers, converting sliding friction into rolling friction, which significantly reduces energy loss and improves grease service life while maintaining displacement capability through the two-part outer ring design.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If ceramic rollers are used in cylindrical roller bearings, then wear is reduced and service life is extended, but the cost increases significantly

Engineering Contradiction:

Improvebearing service lifeVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using expensive ceramic rollers, the invention employs standard deep groove ball bearings with two-part outer rings. This approach achieves the desired service life and wear resistance through the innovative outer ring design and reduced friction mechanism, avoiding the high costs associated with ceramic materials while maintaining reliability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 two-part outer ring design enables effective compensation for axial deformations, extending the service life of the bearings, reducing wear, and lowering costs by enhancing grease service life and minimizing friction, while ceramic rolling elements provide low wear and increased durability.

Implementation Method 1

In order to allow the shaft to be displaced, a non-locating bearing is used as the second bearing. Such a displacement can be necessary in order to compensate for manufacturing tolerances of the bearings or for a deformation, such as a thermal expansion, of the elements, for example, of the bearing or of the shaft.

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

since in operation a friction corrosion (also called fretting) can arise in particular between an outer ring of the non-locating bearing and the housing of the non-locating bearing, the displacement can be blocked in extreme cases

Methodology Applied

Scientific EffectFriction corrosion (fretting): Tribocorrosion

Implementation Method 3

a linear contact of the inner ring, outer ring, and of the rollers occurs in the cylindrical roller bearing, and this causes disadvantages in the grease service life and the bearing friction

Methodology Applied

Scientific EffectRolling friction: Friction

Data Source

PatentUS11156250B2Bearing assembly

Publication Date: 2021.10.26 AB SKF SKF PATENT DEPARTMENT

AI summary

A bearing assembly includes a first locating bearing and a second locating bearing configured to be mounted on a shaft. The first locating bearing includes a two-part outer ring formed from a radially inward outer ring and a radially outward outer ring, and a diameter of the inward outer ring is smaller than a diameter of the outward outer ring.