Laminated Rotor Core Fastening via Interference Fit
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Solution Overview
Problem
Existing methods for fastening components in electrical machines, such as wind turbine generators, are complex, costly, and prone to deterioration over time, requiring extensive materials like welding and gluing, which complicates the assembly process and reduces reliability.
Innovation Solution
A fastening system utilizing a male and female portion with protruding sheets that deform upon insertion, creating a secure pressure fit without additional materials like bolts or welding, allowing for easy assembly with minimal force and potentially elastic or plastic deformation for reliable attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional fastening methods (welding, gluing, bolting) are used to attach components in electrical machines, then the attachment strength is improved, but the assembly process becomes complex, costly, and time-consuming
Solution Approach 1:
The rotor core is segmented into multiple laminated sheets with different shapes. Some sheets have protrusions that interfere with the magnet insertion path, while others have gaps that guide the magnets. This segmentation allows the magnet to be mechanically interlocked with the rotor core through interference fit, eliminating the need for additional fastening materials and reducing assembly complexity.
Solution Approach 2:
The rotor core sheets are designed to automatically perform the fastening function through their geometric configuration. The protruding sheets bend during magnet insertion and create interference fit, while the gap sheets guide the magnets into position. This self-service mechanism eliminates the need for external fastening systems like welds, glue, or bolts, significantly simplifying the assembly process.
2Strength
If traditional fastening methods are used, then the attachment strength is improved, but the assembly time and labor intensity increase
Solution Approach 1:
The rotor core sheets are pre-configured with specific geometric features (protrusions and gaps) during manufacturing. These pre-formed features automatically guide the magnets into the correct positions and create the interference fit during a single insertion motion. This preliminary action eliminates the need for multiple sequential fastening operations, dramatically reducing assembly time and labor intensity.
3Strength
If glue is used for fastening, then the attachment is initially strong, but the reliability deteriorates over time
Solution Approach 1:
The invention replaces long-lived mechanical interference fit structures with a short-lived adhesive bonding approach. The glue is applied to the protruding sheets and cures to bond the magnet to the rotor core. While the adhesive itself has a limited service life compared to permanent mechanical fastening, the overall system achieves reliable attachment through the combination of mechanical interference and chemical bonding, with the advantage of simplified assembly.
4Strength
If complex fastening systems with multiple materials are used, then the attachment strength is improved, but the manufacturing cost increases
Solution Approach 1:
The invention merges the structural support function and the fastening function into a single integrated rotor core structure. The laminated sheets with protrusions and gaps simultaneously provide mechanical support for the magnets and create the interference fit for attachment. This merging eliminates the need for separate fastening components (bolts, welds, or additional clips), reducing the number of parts, materials, and manufacturing steps, thereby lowering overall manufacturing cost.
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
This method simplifies and cost-reduces the assembly process by eliminating the need for extra materials, providing a reliable and balanced fastening mechanism that maintains stability over time, while also reducing eddy currents through the use of non-magnetic and electrically insulating materials.
Implementation Method 1
The one or more protruding sheets have dimensions larger than the opening of the female portion such that, in use, the one or more protruding sheets are deformed during insertion of the male portion into the opening of the female portion
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
Electrical machine comprising a first item having a male portion and a second item having a female portion. The male and female portions have a shape adapted to each other such that the male portion can be fitted into the female portion. The male and/or female portion is formed as a stack of sheets comprising standard sheets and protruding sheets. The "male" standard sheets substantially fits into the female portion and the "male" protruding sheets are larger than the female portion such that, in use, said protruding sheets are deformed during insertion of the male portion into the female portion. The "female" standard sheets have an opening into which the male portion substantially fits, and the "female" protruding sheets have an opening smaller than the male portion such that, in use, said protruding sheets are deformed during insertion of the male portion into the opening of the female portion.