Electrically Isolated Non-Sealed Bearing Shunt Ring
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Solution Overview
Problem
Non-sealed bearings in applications like automatic transmission systems face premature failure due to electrical leakage currents, which cause arcing and material degradation, especially when lubricants like ATF are present, leading to increased noise and potential damage.
Innovation Solution
An electrically-conductive shunt ring assembly is integrated into the bearing, featuring conductive coatings on the inner and outer rings and a conductive shunt ring that safely diverts electrical current to ground while allowing lubricant flow, preventing arcing and material degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a non-sealed bearing is used to allow lubricant flow, then lubrication is improved, but electrical current passes through rolling elements causing arcing and material degradation
Solution Approach 1:
A conductive shunt ring assembly is introduced as an intermediary component between the inner and outer rings. This shunt ring provides a dedicated electrical conduction path that intercepts leakage current before it can pass through the rolling elements, thereby protecting the bearing materials from arcing and electrochemical degradation while maintaining the non-sealed structure for lubricant flow
Solution Approach 2:
The bearing is segmented into functionally distinct zones: conductive coatings are applied to specific surfaces (inner ring outer surface and outer ring inner surface) to create electrical conduction paths without covering the entire surfaces, allowing simultaneous lubricant flow and electrical current management in different areas
2Reliability
If conductive coatings are applied to bearing surfaces to divert electrical current, then electrical protection is improved, but lubricant flow may be restricted
Solution Approach 1:
Conductive coatings are applied locally to specific surfaces (the outer surface of the inner ring and the inner surface of the outer ring) rather than covering entire surfaces. This localized application creates electrical conduction paths for current diversion while leaving other areas open for unrestricted lubricant flow through the bearing
Solution Approach 2:
The shunt ring assembly acts as a mediator that collects electrical current from the conductive coatings and provides a separate conduction path to ground, preventing current from passing through rolling elements while not interfering with the lubricant flow path through the bearing clearance
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 effectively inhibits electrical current from passing through the rolling elements, reducing the risk of arcing and material degradation, thus extending the bearing's lifespan and preventing premature failure.
Implementation Method 1
a surface of the first pocket is provided with a first conductive coating... a surface of the second pocket is provided with a second conductive coating... An electrically-conductive shunt ring assembly couples the inner ring to the outer ring
Implementation Method 2
An electrically-conductive shunt ring assembly couples the inner ring to the outer ring and is configured to inhibit electrical current passing between the inner ring and outer ring from passing through the rolling elements
Data Source
AI summary
A bearing includes an inner ring having an outer surface defining a first pocket therein. The surface of the first pocket can be provided with a first conductive coating. The bearing includes an outer ring concentric with and radially outward from the inner ring. The outer ring has an inner surface defining a second pocket therein, and a surface of the second pocket can be provided with a second conductive coating. A plurality of rolling elements are disposed between the inner ring and the outer ring. An electrically-conductive shunt ring assembly couples the inner ring to the outer ring and is configured to inhibit electrical current passing between the inner ring and outer ring from passing through the rolling elements. The shunt ring assembly is sized and configured to enable lubricant to flow freely through the bearing. In some embodiments, the shunt ring is a conductive snap ring.