Outer Rotor Motor Segmented Mounting Post Design
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Solution Overview
Problem
Traditional outer rotor brushless DC motors face challenges in increasing cogging torque without increasing the size and manufacturing cost, particularly due to the need for high-strength materials and precise bearing alignment, which complicates the structure and manufacturing process.
Innovation Solution
The design includes a stator with a stator core and winding, a rotor with a magnet holder, and a mounting seat comprising separate upper and lower brackets, a connecting member, and a cylindrical mounting post that extends through the stator core, allowing bearings to be positioned outside the stator core, reducing the motor's overall size and enabling the use of less expensive materials for the mounting post.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mounting post is made larger to accommodate bearings, then the bearing support capability is improved, but the radial size of the stator core increases and manufacturing complexity increases
Solution Approach 1:
The mounting post is divided into two functional sections: an upper section that supports the bearings and a lower section that fits through the stator core. This segmentation allows the bearing-supporting portion to be sufficiently large while the portion occupying stator core space remains small, resolving the contradiction between bearing support capability and stator core size.
2Reliability
If the mounting post is made larger to accommodate bearings, then the bearing support capability is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The mounting post is divided into an upper bearing-supporting section and a lower stator-core-fitting section with different diameters. This segmentation allows each section to be optimized independently: the upper section is sufficiently large for bearing support while the lower section remains small for easy integration with the stator core, reducing overall manufacturing complexity.
3Strength
If high-strength materials are used for the mounting post, then the load-bearing capability is improved, but the manufacturing cost increases
Solution Approach 1:
The mounting post employs different material properties in different sections: the upper section requiring high strength uses high-strength materials to support bearings and loads, while the lower section passing through the stator core uses lower-cost materials. This local quality differentiation maintains necessary load-bearing capability while reducing overall manufacturing cost.
4Manufacturing precision
If the mounting post is finished precisely to ensure bearing concentricity, then the bearing alignment is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The mounting post is segmented into an upper precision section for bearing mounting and a lower section for stator core integration. This segmentation allows precise finishing to be applied only to the upper section where bearings are mounted, ensuring bearing concentricity while reducing overall manufacturing complexity and cost by avoiding unnecessary precision work on the lower section.
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 design enhances cogging torque while reducing the motor's size and manufacturing costs by allowing the use of cheaper materials and simplifying the assembly process, maintaining the same overall size and increasing the stator core's coil capacity for greater power.
Implementation Method 1
The stator includes a stator core and a stator winding wound around the stator core
Implementation Method 2
The stator comprises a housing and permanent magnets mounted to the inner surface of the housing
Data Source
AI summary
An outer rotor motor includes a stator, a rotor rotatably disposed outside the stator, a mounting seat, a rotation shaft driven by the rotor, and two bearing mounted to the mounting seat to rotatably support the rotation shaft. The stator includes a stator core and a stator winding wound around the stator core. The mounting seat includes an upper bracket seated on one of opposite axial ends of the rotor, a lower bracket seated on the other axial end of the rotor, a connecting member connected between the upper bracket and the lower bracket, and a cylindrical mounting post fixed to the upper bracket. The cylindrical mounting post extends through and is fixed in the stator core. The rotation shaft is rotatably received in the mounting post. The two bearings are avoided overlapping the stator core in the axial direction.