Electric Machine Rotor With Scarf-Jointed Multi-Material Bridges
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Solution Overview
Problem
Current motor/generator core manufacturing processes result in rotor or stator laminations with uniform properties, failing to meet conflicting property requirements for different regions, such as varying magnetic permeability and mechanical strength.
Innovation Solution
The electric machine rotor incorporates stamped sheets of different materials with specific properties, such as non-ferromagnetic metals or alloys, to create regions with tailored magnetic permeability and mechanical strength, including center bridges, top bridges, and vertex portions, to address specific operational stresses and performance challenges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rotor or stator laminations are punched from homogeneous electrical steel sheet, then manufacturing process is simple and cost-effective, but all regions have identical magnetic permeability and mechanical strength properties which cannot satisfy conflicting regional requirements
Solution Approach 1:
The lamination is divided into multiple regions with different materials: a first region made from electrical steel sheet and a second region made from a different material, allowing each region to have optimized properties for its specific function
Solution Approach 2:
Different regions of the lamination are assigned different material properties - the first region has specific magnetic permeability and mechanical strength while the second region has different properties, enabling each local area to be optimized for its operational requirements
2Reliability
If certain regions are designed with low magnetic permeability while other regions require high magnetic permeability, then regional performance optimization is achieved, but manufacturing complexity increases due to multi-material processing
Solution Approach 1:
The lamination is segmented into distinct material zones during the punching process, with the first region punched from electrical steel sheet and the second region from a different material, enabling independent optimization of magnetic properties for each zone
Solution Approach 2:
The lamination uses a composite structure combining electrical steel sheet with a second material having different magnetic properties, creating a multi-material component that achieves superior magnetic flux management compared to homogeneous materials
3Strength
If homogeneous electrical steel sheet is used throughout the rotor or stator lamination, then manufacturing precision is maintained with uniform material properties, but mechanical strength in high-stress areas is insufficient
Solution Approach 1:
The second region is specifically designed with enhanced mechanical strength properties to withstand high-stress conditions in that local area, while the first region maintains properties suitable for its lower-stress application
Solution Approach 2:
The lamination is segmented into a first region with standard electrical steel properties and a second region with reinforced material properties, allowing mechanical strength to be concentrated where needed without unnecessarily complicating the entire structure
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 approach enhances the rotor's performance by reducing flux leakage, increasing torque density, and improving mechanical strength in high-stress areas, while minimizing core losses and optimizing magnetic flux density.
Implementation Method 1
define a center bridge between the magnet pockets that has a magnetic permeability less than, and a mechanical strength greater than, the first stamped rotor lamination
Implementation Method 2
The first stamped sheet is coplanar with and scarf jointed to the first stamped rotor lamination
Data Source
AI summary
An electric machine rotor including a first stamped rotor lamination and a first stamped sheet of a material different than the first stamped rotor lamination is provided. The first stamped rotor lamination may define a pair of magnet pockets. The first stamped sheet may be coplanar with and scarf jointed to the first stamped rotor lamination to define a center bridge between the magnet pockets that has a magnetic permeability less than, and a mechanical strength greater than, the first stamped rotor lamination. The rotor may further include a second stamped sheet of a material different than the first stamped rotor lamination coplanar with and scarf jointed to the first stamped rotor lamination to define a top bridge adjacent to one of the magnet pockets at a perimeter of the rotor that has a magnetic permeability less than, and a mechanical strength greater than, the first stamped rotor lamination.