Rotating electric machine, compressor, and refrigeration device
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Solution Overview
Problem
Rotors with ferrite magnets in rotating electric machines experience reduced magnetic flux density and increased size due to the deviation of magnetic centers, leading to decreased torque performance and vertical vibration of the drive shaft.
Innovation Solution
Incorporating a rotor core with a first core section opposed to the stator core, a second core section protruding upward, and a third core section protruding downward, along with magnetic resistance structures in the second and third core sections to maintain magnetic flux concentration and apply a downward pull force on the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the rotor core is extended axially to compensate for magnetic center deviation, then magnetic flux density is improved, but the motor size increases
Solution Approach 1:
The rotor core is divided into three distinct sections: a first core section at the N-pole, a second core section at the S-pole, and a third core section in the middle. Each section has different axial lengths, with the first and second core sections extending further axially than the third core section. This segmentation allows targeted extension of magnetic path length at pole regions to improve flux density without proportionally increasing overall motor size.
Solution Approach 2:
Different sections of the rotor core have different axial lengths tailored to their specific functional requirements. The first core section (N-pole) and second core section (S-pole) have greater axial lengths to enhance magnetic flux density at the magnetic poles where flux generation is critical, while the third core section (middle) has a shorter length to minimize overall size. This local differentiation optimizes magnetic performance without unnecessary size increase.
2Power
If the rotor core is extended axially to maintain magnetic flux concentration, then torque performance is improved, but vertical vibration of the drive shaft increases
Solution Approach 1:
The rotor core employs asymmetric axial lengths for different sections: the first core section (N-pole) and second core section (S-pole) extend further axially than the third core section (middle). This asymmetric design creates intentional magnetic center deviation that generates a downward pull force on the rotor, counteracting upward vibration of the drive shaft and reducing vertical oscillation while maintaining torque performance.
Solution Approach 2:
The asymmetric rotor core design proactively introduces a downward pull force through magnetic center deviation to counteract the harmful upward vibration of the drive shaft before it becomes a significant problem. This preliminary counter-action reduces vertical vibration and potential bearing damage while simultaneously improving torque output through enhanced flux concentration at the extended pole sections.
3Ease of manufacture
If ferrite magnets are used to reduce cost, then manufacturing cost is reduced, but magnetic flux density decreases
Solution Approach 1:
The invention changes the geometric parameters of the rotor core, specifically extending the axial lengths of the first and second core sections at the magnetic poles. This parameter change increases the magnetic path length and enhances magnetic flux concentration, compensating for the inherently lower magnetic strength of ferrite magnets and maintaining adequate flux density despite using cost-effective ferrite material instead of more expensive rare-earth magnets.
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 configuration enhances magnetic flux density, reduces vertical vibration of the drive shaft, and maintains compact motor size while improving torque performance.
Implementation Method 1
The second core section is at least partially ahead of an end of the stator core in the first direction, and has a magnetic resistance structure with a lower magnetic permeability than the first core section
Implementation Method 2
a plurality of permanent magnets in magnet holes provided in the rotor core
Implementation Method 3
a rotor including a rotor core configured to rotate about a rotation axis and a plurality of permanent magnets in magnet holes provided in the rotor core; and a stator including a stator core radially outside the rotor
Implementation Method 4
The effect of the magnetic pull force biases the rotor downward. This reduces the vertical vibration of the drive shaft below the motor
Data Source
AI summary
A rotating electric machine includes a rotor and a stator. The rotor includes a rotor core, and a plurality of permanent magnets. The stator includes a stator core radially outside the rotor. First and second directions represent axial directions of the rotation axis. The rotor core includes first and second core sections with same cross-sectional shapes perpendicular to the axial directions. The first core section is at least partially opposed to the stator core in radial directions. The second core section is adjacent to an end of the first core section in the first direction. The second core section is at least partially ahead of a first end of the stator core. The second core section has a magnetic resistance structure with lower magnetic permeability than the first core section. The magnetic resistance structure is formed in a magnetic pole section of the rotor radially outside the magnets.