Insulated Bearing Assembly With Keyed Insert Locking
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Solution Overview
Problem
Existing rolling bearings in electric motors and electrical machines face issues such as electrical current damage to components and potential separation of insulating inserts due to relative movement, which are costly and inefficient.
Innovation Solution
A bearing device with integrated electrical insulation featuring a bushing and insulating insert overmolded onto a ring, secured by grooves and keys to prevent relative movement, ensuring electrical isolation and ease of assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic rolling elements are used to replace steel rolling elements for electrical insulation, then electrical insulation is improved, but manufacturing cost increases
Solution Approach 1:
The bearing is divided into conductive parts (steel inner ring, outer ring, and rolling elements) and an insulating part (insulating sleeve with insulating insert). This segmentation allows the use of inexpensive steel components while adding electrical insulation functionality through the sleeve assembly, avoiding the need for expensive ceramic rolling elements.
Solution Approach 2:
An insulating sleeve with an insulating insert is introduced as an intermediary component between the conductive inner ring and outer ring. This mediator provides the required electrical insulation while allowing the use of standard steel bearing components, thus resolving the contradiction between insulation performance and manufacturing cost.
2Reliability
If an insulating insert with bushing is added to provide electrical insulation, then electrical insulation is improved, but device complexity increases
Solution Approach 1:
The insulating insert and bushing are merged into a single integrated component where the insulating insert is overmolded directly onto the bushing. This merging eliminates the need for separate assembly steps and additional fastening elements, reducing device complexity while maintaining electrical insulation functionality.
Solution Approach 2:
The insulating insert is overmolded onto the bushing during the manufacturing process, creating a pre-assembled unit with integrated electrical insulation. This preliminary action ensures proper positioning and fixation without requiring additional assembly steps or complex fastening mechanisms in the final bearing assembly.
3Ease of operation
If the insulating insert is overmolded to fix it to the outer ring and bushing, then ease of assembly is improved, but relative separation can still occur in operation
Solution Approach 1:
Grooves are created at specific local positions on the bushing and insulating insert to provide mechanical interlocking. This local modification enhances the fixation reliability at critical interfaces without affecting the overall overmolded structure or complicating the assembly process.
Solution Approach 2:
The insulating insert is made of a material that can be overmolded onto the bushing, creating a composite structure with enhanced mechanical bonding. This composite construction, combined with the grooves, prevents relative separation while maintaining ease of assembly through the overmolding process.
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 economical, reliable electrical insulation with reduced risk of separation, enhancing the durability and efficiency of the bearing device.
Implementation Method 1
The insulating insert is overmolded onto the second ring of the bearing and at least onto the exterior and/or interior surface(s) of the bushing
Implementation Method 2
at least one first key housed at least in part in the first grooves of the bushing and the insulating insert. The provision of the first key enables the bushing and the insulating insert to be locked together in the circumferential direction
Implementation Method 3
The insulating insert is made of electrically insulative material... an electrical potential difference can appear between the latter and the casing... which generates an electrical current... The insulating insert... ensures electrical isolation
Data Source
AI summary
A bearing device includes a bearing having first and second rings configured for relative rotation, a bushing and an electrically insulating insert overmolded between the second ring and the bushing. The bushing includes a radial groove at least partially aligned with a radial groove in the insulating insert, and the bearing device includes a key having a first portion mounted in the radial groove of the bushing and a second portion mounted in the radial groove of the insulating insert. Also a method of forming the bearing device.