Nonmagnetic Rotor Connecting Portion for Resonance Control
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Solution Overview
Problem
Conventional rotors with resin-filled spaces between inner and outer rotor cores have a narrow resonant frequency adjustment range, leading to difficulties in reducing torsional resonance and noise in motors used in fans and air conditioning apparatuses.
Innovation Solution
A rotor design featuring a nonmagnetic connecting portion between the shaft and rotor core, allowing adjustment of resonant frequency and reducing magnetic flux leakage, which includes an annular rotor core with embedded magnets and a thermoplastic resin connecting portion for electrical insulation and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the space between the inner rotor core and the outer rotor core is filled with resin, then the rotor structure is simplified and manufactured easily, but the resonant frequency adjustment range becomes narrow
Solution Approach 1:
The rotor core is divided into an inner rotor core and an outer rotor core with a space between them. This segmentation allows the connecting portion to be separately designed and optimized for resonant frequency adjustment while maintaining manufacturing simplicity through the resin filling approach.
Solution Approach 2:
A connecting portion formed of nonmagnetic material is introduced as an intermediary element between the shaft and the rotor core. This connecting portion serves as a mediator that enables resonant frequency adjustment by modifying the mechanical coupling characteristics, thereby widening the adjustment range while maintaining the simple resin-filled manufacturing approach.
2Device complexity
If the rotor core and shaft are directly connected, then the structure is simpler, but magnetic flux leakage occurs and motor performance deteriorates
Solution Approach 1:
The connecting portion formed of nonmagnetic material acts as an intermediary between the shaft and rotor core. This intermediary element blocks magnetic flux leakage paths while maintaining mechanical connection, thereby improving motor performance without significantly increasing structural complexity.
Solution Approach 2:
The connecting portion is formed of nonmagnetic material which may be a composite material or treated metal. This material choice provides both mechanical connection functionality and magnetic flux blocking capability, resolving the contradiction between structural simplicity and performance reliability.
3Adaptability or versatility
If a nonmagnetic connecting portion is introduced between the shaft and rotor core, then resonant frequency adjustment range widens and magnetic flux leakage is reduced, but the device complexity increases
Solution Approach 1:
The connecting portion combines multiple functions into a single element: mechanical connection between shaft and rotor core, resonant frequency adjustment through shape/size modification, and magnetic flux leakage prevention. This merging approach widens the adjustment range while minimizing the increase in device complexity.
Solution Approach 2:
The connecting portion is designed as a multi-functional element that simultaneously provides structural support, enables resonant frequency tuning, and blocks magnetic flux. This universality allows a single component to address multiple requirements, reducing the overall device complexity despite the added functionality.
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 widens the resonant frequency adjustment range, reduces noise, and improves motor performance by minimizing magnetic flux leakage and electrolytic corrosion, while also reducing material usage and manufacturing costs.
Implementation Method 1
since the rotor core and shaft are separated by the connecting portion, it is possible to reduce magnetic flux leakage from the rotor core to the shaft
Implementation Method 2
a thermoplastic resin connecting portion for electrical insulation and noise reduction
Implementation Method 3
it is possible to adjust a resonant frequency of the rotor by changing the shape and size of the connecting portion
Implementation Method 4
making it possible to reduce torsional resonance of the motor and impeller or resonance of a unit including the fan, and noise can occur
Data Source
AI summary
A rotor includes: a shaft; a rotor core having an annular shape and surrounding the shaft from outside in a radial direction about a center axis line of the shaft so as to leave a space therebetween; a magnet embedded in the rotor core; and a connecting portion disposed between the shaft and the rotor core and formed of a nonmagnetic material.