Rotor Core Dovetail Groove Bridge Insertion
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Solution Overview
Problem
Conventional rotor designs face challenges in reducing magnetic flux leakage and assembly accuracy, leading to increased costs and potential motor damage due to friction dust generation and deformation under centrifugal forces, which affect rotor-stator clearance and motor performance.
Innovation Solution
A method involving a rotor core with magnetic flux leakage prevention holes and dovetail grooves, where non-magnetic bridges with wide-width end portions are inserted while the core is elastically deformed to prevent friction dust and maintain constant clearance, reducing magnet material usage and motor costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-magnetic bridges are press-fitted into dovetail grooves to prevent magnetic flux leakage, then magnetic flux leakage is reduced, but fine friction dust is generated that can damage motor components
Solution Approach 1:
The patent applies preliminary action by pre-compressing the rotor core to create elastic deformation before inserting the non-magnetic bridges. This preliminary compression creates a state where the bridges can be inserted with clearance into the dovetail grooves without requiring forceful press-fitting, thereby preventing friction dust generation while still achieving magnetic flux leakage prevention when the core returns to its normal state
Solution Approach 2:
The patent changes the physical state parameter of the rotor core by applying external compression force that causes elastic deformation. This parameter change (from normal state to compressed state) allows the dovetail grooves to be closer together, enabling clearance-fit insertion of bridges without friction. When the compression is released, the core returns to its original state, maintaining the magnetic flux leakage prevention function
2Reliability
If rotor core is assembled from separate outer and inner circumferential pieces with non-magnetic bridges, then magnetic flux leakage is prevented, but assembly accuracy variations increase making it difficult to reduce stator-rotor clearance
Solution Approach 1:
The patent merges the outer and inner circumferential pieces into a single integrated rotor core structure. This eliminates the need for separate assembly of multiple pieces and non-magnetic bridges, thereby removing assembly accuracy variations while still preventing magnetic flux leakage through the integrated design of the rotor core itself
3Object-generated harmful factors
If non-magnetic bridges are inserted with clearance into dovetail grooves to avoid friction dust, then friction dust generation is reduced, but outer circumferential portion deformation occurs under centrifugal force
Solution Approach 1:
The patent applies preliminary compression to the rotor core, creating elastic deformation that pre-positions the rotor core walls in a compressed state. This preliminary action ensures that when bridges are inserted with clearance, the compressed state maintains bridge position stability. Upon release of compression, the elastic recovery maintains continuous contact between bridges and grooves, preventing deformation under centrifugal force
Solution Approach 2:
The patent utilizes parameter change through elastic deformation of the rotor core. By changing the density and dimensional parameters of the rotor core through compression, the structure gains the ability to maintain bridge positioning without friction-based press-fitting. The elastic properties allow the structure to adapt to centrifugal forces while maintaining stability
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 effectively reduces magnetic flux leakage, minimizes friction dust generation, and maintains consistent rotor-stator clearance, enhancing motor performance and reducing costs by using less magnet material.
Implementation Method 1
applying an external force to the rotor core to cause elastic deformation of the rotor core so that the outer-circumferential-side inner wall of the magnetic flux leakage prevention hole comes close to the inner-circumferential-side inner wall
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
In a method for producing a rotor (1) including a leak prevention hole (15) formed in a rotor core (2) to prevent leakage of magnetic flux from a permanent magnet (3-5); an outer-circumferential-side dovetail groove (20) formed in an outer-circumferential-side inner wall (15a) of the leak prevention hole (15), an inner-circumferential-side dovetail groove (21) formed, opposite the outer-circumferential-side dovetail groove (20), in an inner-circumferential-side inner wall (15b) of the leak prevention hole (15); and a non-magnetic bridge (6) having both end portions (61, 62) engageable with the dovetail grooves (20, 21), an external force is applied to bring the outer-circumferential-side inner wall close to the inner-circumferential-side inner wall, the non-magnetic bridge (6) is inserted in the dovetail grooves (20, 21) while keeping the rotor core (2) in an elastically deformed state, and, after inserting, the external force is released.