Segmented Rotor Holder Assembly to Contain Magnet Fragments
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Solution Overview
Problem
It is challenging to effectively fit a non-magnetic pipe around a permanent magnet extending in an axial direction, which can lead to scattering of magnet fragments during high-speed rotation in inner rotor type motors.
Innovation Solution
A rotor design featuring a cylindrical magnet with a through hole, covered by first and second holders with annular bottom plate portions and cylindrical body portions, where the magnet is press-fitted and the holders are joined with flange portions to prevent scattering, allowing for easier coverage and press-fitting, and welding to ensure a secure and gap-free assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single non-magnetic pipe is used to cover the magnet, then magnet fragment scattering is suppressed, but the fitting process becomes difficult and complex
Solution Approach 1:
The holder is divided into two separate parts (first holder and second holder) that cover opposite ends of the magnet. This segmentation makes the assembly process easier by allowing incremental installation rather than attempting to fit a single complex pipe structure around the entire magnet.
Solution Approach 2:
The holder structure extends in the axial direction with body portions that cover the outer peripheral surface of the magnet, adding a dimensional approach to coverage that simplifies the fitting process compared to a single circumferential pipe.
2Reliability
If the holder inner diameter is made smaller than magnet outer diameter for secure fitting, then magnet coverage is improved, but press-fitting becomes difficult
Solution Approach 1:
The holder is segmented into two parts that can be installed separately on opposite ends of the magnet. This allows the magnet to be covered incrementally without requiring extreme press-fitting forces that would be needed if a single continuous holder tried to accommodate the entire magnet.
Solution Approach 2:
The first and second holders cover only portions of the magnet's outer peripheral surface rather than attempting to cover the entire circumference with a single structure. This partial coverage approach reduces the complexity and difficulty of the press-fitting process while still achieving the goal of suppressing magnet fragment scattering.
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
The design effectively suppresses magnet fragment scattering, facilitates easier magnet coverage and assembly, and maintains the rotor's balance and reliability, even when using sintered magnets.
Implementation Method 1
the magnet is press-fitted into the first body portion and the second body portion
Implementation Method 2
the inner diameter of the first end and an inner diameter of the second end are larger than an outer diameter of the magnet
Data Source
AI summary
In a rotor of a motor or the like, in order to suppress scattering of a part of a magnet provided around a rotating shaft, the rotor has a cylindrical magnet through which the rotating shaft passes, a first holder which covers the magnet from one side in an axial direction of the rotating shaft and a second holder which covers the magnet from the other side in the axial direction. The magnet is press-fitted into a first body portion of the first holder and a second body portion of the second holder, and a first end of the first body portion and a second end of the second body portion are joined by welding or the like. An inner diameter of the first end and the inner diameter of the second end are larger than an outer diameter of the magnet.