Electrically Insulated Bearing Ring Structure for Current Damage

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Solution Overview

Problem

In electric motors or machines, rolling bearings experience damage from electrical currents and vibrations due to potential differences between the shaft and housing, and replacing steel rolling elements with ceramic ones is expensive.

Innovation Solution

A bearing device with a first and second ring that rotates relative to each other, featuring an insulating sleeve with an overmolded electrically insulating lining between the rings, which reduces electrical conductivity and includes annular grooves and washers for enhanced axial load transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rolling elements are replaced with ceramic material to prevent electrical current damage, then bearing reliability is improved, but device cost increases

Engineering Contradiction:

Improvebearing reliabilityVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

An insulating lining is introduced as an intermediary component between the bearing rings and rolling elements. This lining prevents direct electrical contact and current flow through the ceramic rolling elements, thereby protecting the bearing while allowing the use of more cost-effective materials rather than requiring expensive all-ceramic construction

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bearing device employs a composite structure combining conductive metal components (bearing rings) with an electrically insulating lining material. This composite approach provides the necessary electrical insulation to prevent current damage while maintaining mechanical functionality, offering a cost-effective alternative to full ceramic bearings

Inventive Principle:

Principle #40Composite materials

2Reliability

If insulating lining is added to provide electrical insulation, then bearing reliability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvebearing reliabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The insulating lining is pre-formed and positioned within the bearing structure before final assembly. This preliminary preparation of the insulating component simplifies the overall manufacturing process by allowing the lining to be prepared separately and then integrated into the bearing assembly in a controlled manner

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The insulating lining is nested within the bearing structure, fitting inside the bearing rings and surrounding the rolling elements. This nested configuration allows the insulating component to be integrated into the existing bearing geometry without requiring complete redesign of the bearing structure

Inventive Principle:

Principle #7Nested doll (Nesting)

3Manufacturing precision

If annular grooves are formed in insulating lining to reduce particle adherence, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:

Improvemachining precisionVSAvoidstructural complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Annular grooves are introduced at specific locations on the insulating lining where particle adherence is most problematic during machining. This localized feature provides targeted particle release functionality without requiring complex modifications throughout the entire insulating component structure

Inventive Principle:

Principle #3Local quality

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 provides cost-effective, easy-to-manufacture bearings with integrated electrical insulation, reduced sensitivity to temperature changes, and improved axial load handling, minimizing the risk of particle adherence during machining.

Implementation Method 1

The insulating lining is made of electrically insulating material

Methodology Applied

Scientific EffectElectrical insulation: Electrical Resistance

Implementation Method 2

The insulating lining is overmolded on the second ring and on the socket

Methodology Applied

Scientific EffectOvermolding:

Data Source

PatentUS12196266B2Bearing device with integrated electrical insulation, in particular for an electric motor or machine, and method of forming same

Publication Date: 2025.01.14 AB SKF SKF PATENT DEPARTMENT

AI summary

A bearing device includes first and second rings each having end faces and being configured to rotate relative to one another, and the second ring has an annular groove. A socket having an electrically insulating sleeve is mounted on the second ring with the insulating lining radially interposed between the second ring and the socket. End faces of the electrically insulating lining each have an annular groove with a bottom that is offset axially inward relative to the respective first and second end faces of the second ring and to the respective first and second end faces of the socket. A method includes grinding end faces of the socket and/or second ring to reduce an axial depth of the grooves in the insulating layer.