Grounding Brush Assembly With Centering Bearings for Bearing Protection

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Solution Overview

Problem

Electric currents accumulating on shafts in bearings of electric machines can cause damage to raceways and rolling elements, necessitating a conductive path to shunt current away from the bearings.

Innovation Solution

A grounding brush assembly with a conductive base member and radially extending conductive fibers that provide a path from the rotatable shaft to a grounded fixed shaft, using centering bearings to center and stabilize the shaft, reducing friction and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a grounding brush assembly is provided to shunt current away from bearings, then bearing damage is prevented, but friction and wear on the conductive fibers increase

Engineering Contradiction:

Improvebearing protectionVSAvoidfriction and wear

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces centering bearings as an intermediary component between the conductive fibers and the shaft. These centering bearings reduce friction and wear by providing a low-friction interface, while the conductive fibers maintain electrical contact to shunt current away from the bearing raceways and rolling elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameters of the conductive fibers by treating them with a lubricant or coating that reduces friction and wear. This allows the fibers to maintain their electrical conductivity while experiencing reduced mechanical wear during operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conductive fibers extend radially inwardly to contact the shaft, then current shunting is effective, but misalignment and instability occur

Engineering Contradiction:

Improvecurrent shuntingVSAvoidshaft alignment

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The centering bearings serve as intermediary components that maintain proper alignment between the conductive fibers and the shaft. These bearings ensure the shaft remains centered while allowing the conductive fibers to maintain stable radial contact for effective current shunting.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The centering bearings create a stable, centered position for the shaft, ensuring equipotential alignment with the conductive fibers. This eliminates misalignment issues and ensures consistent electrical contact while maintaining mechanical stability.

Inventive Principle:

Principle #12Equipotentiality

3Device complexity

If the shaft is left unsupported, then the structure is simple, but vibration and instability increase

Engineering Contradiction:

ImprovestructureVSAvoidshaft stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The centering bearings act as intermediary support elements that stabilize the shaft without adding significant structural complexity. These bearings provide the necessary support to reduce vibration and maintain shaft stability while keeping the overall assembly relatively simple.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Prevents damage to bearings by shunting electric currents away from the bearing raceways and rolling elements while stabilizing the shaft, reducing friction and wear on the conductive fibers.

Implementation Method 1

At least one centering bearing includes an inner ring disposed about the at least one end body portion of the cylindrical body of the base member and an outer ring engageable with the inner circumferential surface of the rotatable shaft so as to center the rotatable shaft about the fixed shaft

Methodology Applied

Scientific EffectBall bearing: Ball Bearing

Implementation Method 2

Each conductive fiber has an inner radial end coupled with the base member and an outer radial end engageable with the inner circumferential surface of the rotatable shaft such that at least one conductive path extends from the rotatable shaft, through the brush and the base member, and to the fixed shaft

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20260018977A1Internally shunting grounding brush assembly with axial brushes and centering bearings

Publication Date: 2026.01.15 AB SKF SKF PATENT DEPARTMENT

AI summary

A grounding brush assembly is for an electric machine include a rotatable shaft having a bore, an outer housing, bearing(s) rotatably coupling the shaft and housing and an electrically-grounded, fixed shaft extending through the rotatable shaft bore. A conductive base member receives the fixed shaft and has a main body portion and at least one end body portion with an outside diameter less than the main body portion outside diameter. A centering bearing is disposed about the end body portion. A conductive brush coupled with the main body portion includes conductive fibers extending radially outwardly from the main body portion and axially along a centerline. Each conductive fiber has an inner radial end coupled with the base member and an outer radial end engageable with the inner circumferential surface of the rotatable shaft such that at least one conductive path extends from the rotatable shaft to the fixed shaft.