Combined Insulator Conductor Assembly for Bearing Current Protection

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Solution Overview

Problem

Bearings in electrical machinery are susceptible to damage from electric current or charge passing through them, which existing grounding devices and insulative coatings fail to adequately prevent.

Innovation Solution

A combined electrical insulator and conductor assembly is used between the shaft and housing, featuring an annular insulator and a conductive disk with a brush subassembly of conductive fibers to prevent current flow through the bearing while providing an alternative conductive path for current to flow safely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If grounding brushes with conductive fibers are used to provide an alternative current path, then current protection is improved, but the device complexity increases due to the need for multiple components (insulator, conductor, brush subassembly)

Engineering Contradiction:

Improvecurrent protectionVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the insulator and conductor into a single integrated assembly where the conductor is fixedly coupled to the insulator. This merging reduces the number of separate components that need to be installed and managed, thereby reducing device complexity while maintaining the dual functionality of electrical insulation and current conduction protection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The combined assembly serves multiple functions simultaneously: the insulator portion prevents current flow through the bearing, while the conductor portion provides an alternative current path. This multi-functionality eliminates the need for separate grounding devices, simplifying the overall system while improving reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If insulative coatings are applied to prevent current flow through the bearing, then current protection is improved, but the manufacturing precision requirements increase for proper coating application and thickness control

Engineering Contradiction:

Improvecurrent protectionVSAvoidcoating thickness control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Instead of applying a coating directly to the bearing (which requires precise thickness control), the patent introduces a separate insulator component that mechanically interfaces with the bearing. This intermediary component provides the insulation function without requiring precision coating processes, as the insulator is a discrete part with defined dimensional tolerances that is easier to manufacture and install.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a solid ring of conductive fibers is used to ground the bearing, then current conduction is improved, but the device complexity and material quantity increase

Engineering Contradiction:

Improvecurrent conductionVSAvoidconductive fiber quantity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

Rather than using a continuous solid ring of conductive fibers, the patent segments the conductor into a brush subassembly with multiple discrete conductive fibers spaced circumferentially. This segmentation achieves effective current conduction through multiple parallel paths while reducing the total quantity of conductive material required compared to a solid ring structure.

Inventive Principle:

Principle #1Segmentation

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

Effectively protects the bearing from electric current by preventing direct flow through it and directing current through the assembly, thereby preventing damage and ensuring safe operation of electrical machinery.

Implementation Method 1

an annular insulator disposable about the outer ring and configured to prevent electric current flow between the outer ring and the housing

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

a plurality of electrically conductive fibers, the conductive fibers being spaced circumferentially about the centerline and extending radially inwardly from the inner end of the conductive disk. Each conductive fiber has an inner end contactable with the shaft outer surface so as to provide a conductive path between the shaft and the disk

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11486445B2Combined insulator and conductor assembly for bearings with fixed conductor

Publication Date: 2022.11.01 AB SKF SKF PATENT DEPARTMENT

AI summary

A combined electrical insulator and conductor assembly for a bearing disposable between a shaft and a housing includes an annular insulator disposable about the bearing outer ring and configured to prevent electric current flow between the outer ring and the housing and including projections extending axially along and spaced circumferentially about a centerline. A conductor preferably includes a conductive disk with an outer radial end engageable with the housing inner surface, an inner radial end defining a central opening for receiving the shaft and openings each receiving a separate one of the plurality of projections of the insulator such that the disk is axially fixed relative to the insulator. An annular conductive brush subassembly is coupled with the conductive disk and includes a plurality of electrically conductive fibers contactable with the shaft outer surface so as to provide a conductive path between the shaft and the disk.