Ferrite Magnet Protective Cover Step Gap Design
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Solution Overview
Problem
In rotating electric machines, the dimensional tolerance of magnets and metal tubes can lead to contact issues, affecting airtightness and magnetic force, especially when using ferrite magnets with neodymium magnets, resulting in potential mechanical stress and reduced performance.
Innovation Solution
A structure featuring a cylindrical stator core, a rotor with a shaft and yoke, at least one ferrite magnet on the yoke's outer surface, and a protective cover with a step portion to create a gap between the magnet and cover, reducing contact and stress, and optimizing magnetic force utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal tube is bent at a sharp angle to attain an airtight structure of the magnet, then the airtight closing of the magnet is improved, but the dimensional tolerance causes contact between the magnet end surface and the end of the metal tube
Solution Approach 1:
The patent applies beforehand cushioning by providing a gap between the magnet end surface and the metal tube end through a step structure. This gap acts as a cushion that absorbs dimensional tolerance variations, preventing direct contact between the magnet and metal tube while maintaining airtight closing. The step structure creates a controlled clearance that compensates for manufacturing tolerances before contact can occur.
Solution Approach 2:
The patent applies segmentation by dividing the metal tube structure into two distinct levels: a first end that contacts the magnet and a second end that is bent at a sharp angle. The step structure creates a clear separation between these segments, allowing the first end to provide airtight closing while the second end maintains the bent configuration without causing contact issues.
2Force
If the length of the ferrite magnet is prolonged to ensure magnetic force, then the magnetic force is improved, but the probability of contact between the magnet end surface and the end of the metal tube increases
Solution Approach 1:
The step structure providing a gap between the magnet and metal tube end acts as beforehand cushioning. This allows the ferrite magnet to be prolonged in length to ensure sufficient magnetic force while the gap prevents contact between the extended magnet end surface and the metal tube, maintaining reliability even with increased magnet length.
3Ease of manufacture
If the axial length of the magnet is manufactured without any process, then the manufacturing complexity is reduced, but the dimensional tolerance increases to about ±2%
Solution Approach 1:
The step structure providing a gap between the magnet and metal tube end serves as beforehand cushioning that absorbs dimensional tolerance variations. This allows the magnet to be manufactured without additional processing steps, maintaining ease of manufacture while the gap compensates for the ±2% dimensional tolerance.
Solution Approach 2:
The gap created by the step structure acts as an intermediary element between the magnet and the metal tube. This intermediary space accommodates dimensional tolerance variations without requiring complex manufacturing processes, allowing direct manufacturing of the magnet while preventing contact issues.
Data Source
AI summary
A small and low-price rotating electric machine has a structure where a magnet end surface and a metal tube end are not in contact with each other. The rotating electric machine has a cylindrical stator core, a rotor having a shaft provided on the inner circumferential side of the stator core, a yoke fixed to the shaft, at least one ferrite magnet provided on the outer circumferential surface of the yoke, and a protective cover provided on the outer circumference of the ferrite magnet. The ferrite magnet end surface is projected with respect to an end surface of the yoke, and has a step portion to form a gap between the end surface of the ferrite magnet and a bottom surface of the protective cover.