Outer Rotor Brushless Motor Magnet Holder Integration
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Solution Overview
Problem
Conventional brushless motor shaft retaining structures face poor workability and potential oil leakage due to complex magnet holder installation and gaps between components, leading to increased manufacturing costs and time.
Innovation Solution
A brushless motor design featuring a magnet holder molded integrally with the bearing holding part, using a thrust plate to prevent shaft contact with the attraction magnet and applying an oil-repellent agent to prevent leakage, while simplifying assembly through insert molding and positioning pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnet holder is press-fitted into a recessed shape or hole formed at the bottom portion of the bearing holding part, then the magnet holder can be fixed, but the workability in assembling the motor becomes poor due to the complex pressing process and small part insertion
Solution Approach 1:
The magnet holder and bearing holding part are merged into a single integrated component. The magnet holder is formed as an integral part of the bearing holding part through injection molding, eliminating the need for separate press-fitting operations. This integration directly resolves the technical contradiction by maintaining reliable magnet holder fixation while dramatically improving assembly workability.
Solution Approach 2:
The bearing holding part is designed to serve multiple functions: it holds the bearing, provides structural support, and integrates the magnet holder function. By making the magnet holder integral to the bearing holding part, the structure achieves multi-functionality, eliminating the need for separate components and assembly steps, thus improving ease of manufacture while maintaining fixation reliability.
2Ease of manufacture
If a hole is drilled at the bottom portion of the bearing holding part and the magnet holder is press-fitted into the hole, then the magnet holder can be installed, but there is a possibility that a slight gap occurs between the bottom portion of the bearing holding part and the magnet holder causing oil leakage
Solution Approach 1:
The magnet holder and bearing holding part are merged into a single integrated component formed by injection molding. This eliminates the interface between separate parts that would create gaps, thereby preventing oil leakage while maintaining ease of manufacture through the integrated formation process.
Solution Approach 2:
The invention uses an oil-repellent coating (thin film) on the magnet holder surface to prevent oil leakage. This coating acts as a barrier that repels oil, ensuring reliable sealing even in the event of minor gaps, thus resolving the contradiction between ease of manufacture and oil sealing reliability.
3Reliability
If the magnet holder is made of a magnetic material and installed with the attraction magnet, then the shaft can be attracted and retained, but the magnet may be stuck to a collar portion of the magnet holder by magnetic force making the process more complicated
Solution Approach 1:
The invention extracts the problematic magnetic interaction by positioning the attraction magnet on the outer peripheral surface of the magnet holder rather than inside it. This separation prevents the magnet from being stuck to the collar portion during installation, simplifying the installation process while maintaining reliable shaft retention through the attraction mechanism.
4Adaptability or versatility
If the magnet holder and bearing holding part are separate components requiring press-fitting assembly, then the structure can be modular, but the manufacturing precision and cost are adversely affected due to poor workability and potential gaps
Solution Approach 1:
The magnet holder and bearing holding part are merged into a single integrated component formed by injection molding. This eliminates assembly operations, ensures high manufacturing precision without gaps, and reduces costs while maintaining structural versatility through integrated design.
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 manufacturing precision and reduces costs by improving workability and accuracy during assembly, while preventing oil leakage through effective positioning and sealing of the magnet holder and bearing components.
Implementation Method 1
an attraction magnet disposed at a position facing one end of the shaft and configured to attract the shaft by a magnetic force
Implementation Method 2
JP-A-2007-037365 discloses a technique for applying oil-repellent agent to the magnet holder and thus repelling the oil
Data Source
AI summary
A brushless motor is provided with: a shaft; a rotor; a stator; a cylindrical oil-retaining bearing; a bearing holding part; an attraction magnet disposed at a position facing one end of the shaft and configured to attract the shaft by a magnetic force; and a thrust plate disposed between the attraction magnet and the one end of the shaft, wherein a magnet holder made of a magnetic material is formed integrally to the bearing holding part, the magnet holder being installed with the attraction magnet, and wherein a side of the magnet holder, on which the attraction magnet is installed, is covered by a material for forming the bearing holding part, except for an installation surface on which the attraction magnet is installed, or for a proximity of the installation surface.