CoFe Core Keyway Mounting for Electrical Machines
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Solution Overview
Problem
Electrical machines using Cobalt Iron (CoFe) cores experience reduced magnetic properties due to compressive stresses from interference fits with stator housings, affecting their performance.
Innovation Solution
The use of radially projecting keys on the core that fit into complementary keyways within the housing, allowing for non-interference mounting and retention, either with retaining elements or an interference fit between the key and keyway, minimizing compressive stresses on the core.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an interference fit is used between the core and stator housing to ensure good mechanical connection, then the mechanical connection strength is improved, but the magnetic properties of the core material are adversely affected due to compressive stresses
Solution Approach 1:
The core is divided into multiple core segments that are assembled together in a ring. This segmentation allows the core to be retained by retaining elements without requiring a full interference fit between the entire core and housing, thereby reducing compressive stresses on the core material while maintaining mechanical connection strength through the segmented structure.
Solution Approach 2:
Retaining elements are introduced as intermediary components between the core and stator housing. These retaining elements provide the mechanical connection and retention function without transferring compressive stresses directly to the core material, thus preserving the magnetic properties while ensuring good mechanical connection.
2Reliability
If an interference fit is used to retain the core in the housing, then the mechanical retention is improved, but the magnetic properties of the core are reduced due to introduced compressive stresses
Solution Approach 1:
The core is segmented into multiple sections that can be retained independently by retaining elements. This segmentation allows mechanical retention without requiring the entire core to be interference fitted into the housing, thereby maintaining reliability of retention while minimizing harmful compressive stresses on the core material.
Solution Approach 2:
The retaining elements act as intermediary components that provide mechanical retention between the core and housing without directly compressing the core material. This intermediary mechanism ensures reliable retention while preserving the magnetic properties of the core.
3Ease of manufacture
If core segments are used to assemble the core in a ring, then the ease of assembly and repair is improved, but the device complexity increases due to multiple components
Solution Approach 1:
The core is divided into multiple segments that can be assembled together in a ring configuration. This segmentation improves ease of manufacture and assembly, as segments can be prepared separately and then assembled without requiring complex interference fitting procedures. The modular nature also facilitates repair by allowing individual segment replacement.
Solution Approach 2:
Retaining elements serve as intermediaries that simplify the assembly process by providing a straightforward retention mechanism for the core segments. Instead of requiring complex interference fits for the entire core, the retaining elements allow for simpler assembly and disassembly operations.
Data Source
AI summary
An electrical machine comprises a stator and a housing. The housing has an internal bore. The stator comprises an annular core mounted within the bore of the housing. The core comprises at least one key projecting radially outwardly from a radially outer surface thereof. The housing comprises at least one keyway in the bore. The at least one key of the core being received within the at least one keyway of the housing.