Composite-Coated Rolling Bearing for Creep and Current Isolation
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Solution Overview
Problem
Rolling bearings used in EV motors face issues with creep due to clearance fits and potential electrolytic corrosion from leakage currents, which existing solutions either inadequately address or introduce new problems.
Innovation Solution
A rolling bearing design featuring a coating layer composite on the inner and outer rings, comprising an anti-creep film with lubricity as the surface layer and an insulating film with insulation properties in the underlying layers, which prevents creep and electrolytic corrosion by reducing friction and wear and breaking the leakage current circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a clearance fit is selected for the outer ring to facilitate easy mounting, then the assemblability is improved, but the outer ring may creep (rotate) relative to the housing under high loads or high-speed rotation
Solution Approach 1:
The patent applies a multi-layer coating with different properties to different regions of the outer ring surface. The surface layer provides lubricity to prevent creeping at the fitting surface, while the underlying insulating layer provides electrical isolation. This local differentiation of material properties allows the clearance fit to maintain both ease of assembly and creep resistance.
Solution Approach 2:
The patent uses a composite coating structure consisting of multiple layers with different functions. The surface layer contains solid lubricant powder for reducing friction and preventing creeping, while the underlying layer provides electrical insulation. This composite material approach allows simultaneous achievement of creep resistance and electrical isolation properties that single materials cannot provide.
2Reliability
If ceramic films are applied to prevent electrolytic corrosion, then the electrolytic corrosion resistance is improved, but the fitting surface lacks lubricity causing friction and wear that affect shaft supporting function
Solution Approach 1:
The patent creates a multi-layer coating where the surface layer provides lubricity to reduce friction and wear, while the underlying layer provides electrical insulation to prevent electrolytic corrosion. This local differentiation ensures that the fitting surface has the necessary lubricating properties while maintaining electrical isolation.
Solution Approach 2:
The patent employs a composite coating structure combining a lubricious surface layer with an insulating underlying layer. The surface layer contains solid lubricant powder to reduce friction and wear, while the underlying layer provides electrical insulation. This composite approach simultaneously addresses both friction reduction and electrolytic corrosion prevention.
3Ease of manufacture
If a single-layer coating is applied to the outer ring, then the manufacturing process is simplified, but it cannot simultaneously provide both lubricity for creep resistance and electrical insulation for corrosion prevention
Solution Approach 1:
The patent applies coatings with different properties to different layers of the outer ring surface. The surface layer is optimized for lubricity to prevent creeping, while the underlying layer is optimized for electrical insulation. This local differentiation of material properties allows simultaneous achievement of multiple functions that a single uniform coating cannot provide.
Solution Approach 2:
The patent uses a multi-layer composite coating structure where each layer serves a specific function. The surface layer provides lubricity for creep resistance, while the underlying layer provides electrical insulation for corrosion prevention. This composite material approach enables simultaneous delivery of multiple critical functions that would be impossible with a single-layer coating.
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 proposed solution effectively prevents creep and electrolytic corrosion in rolling bearings used in EV motors, ensuring reliable operation under high loads and high-speed rotation by reducing friction and wear and protecting against electrolytic damage.
Implementation Method 1
at least one of the plurality of layers of the coating layer composite excluding the surface layer is composed of an insulating film having insulation properties
Implementation Method 2
A surface layer of the plurality of layers of the coating layer composite is composed of an anti-creep film having lubricity
Data Source
AI summary
A bearing device includes an inner ring and an outer ring. At least one of the radially inner surface of the inner ring and the radially outer surface of the outer ring is covered with a coating layer. The coating layer is a coating layer composite composed of a plurality of layers. Of the plurality of layers, the surface layer is composed of an anti-creep film having lubricity, and at least one layer other than the surface layer is composed of an insulating film having insulating properties.