Rotary Electric Machine Outer Rotor Magnetization and Gap Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rotary electric machines with radially magnetized rotors often experience demagnetization due to opposing magnetic flux, leading to reduced magnetic torque and output torque, while those with circumferentially magnetized rotors struggle to secure sufficient reluctance torque due to uniform magnetic path intervals.
Innovation Solution
A rotary electric machine design featuring an outer rotor with circumferentially magnetized magnets, a stator core with an annular yoke and radially protruding teeth, and a gap distance between magnets 1.5 times the tooth pitch, which reduces demagnetization and secures reluctance torque by altering magnetic flux paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If magnets are magnetized in the radial direction, then the magnetic field strength is improved, but demagnetization occurs due to opposing magnetic flux from stator teeth
Solution Approach 1:
The patent inverts the conventional radial magnetization direction and adopts circumferential magnetization instead. This fundamental directional reversal eliminates the opposing magnetic flux issue that causes demagnetization, while still maintaining effective magnetic interaction with the stator coils through the modified magnetic path configuration.
Solution Approach 2:
The patent changes the magnetization direction parameter from radial to circumferential, and simultaneously adjusts the gap distance parameter to be 1.5 times or more the tooth pitch. These parameter changes collectively resolve the demagnetization problem while preserving torque generation capability.
2Reliability
If magnets are magnetized in the circumferential direction, then demagnetization is suppressed, but reluctance torque becomes insufficient due to uniform magnetic path intervals
Solution Approach 1:
The patent changes the gap distance parameter between adjacent magnets to be 1.5 times or more the tooth pitch. This parameter modification creates non-uniform magnetic path intervals that enable sufficient reluctance torque generation while maintaining the benefits of circumferential magnetization and suppressing demagnetization.
3Force
If the gap between magnets is reduced to increase magnetic flux density, then magnetic torque is improved, but demagnetization risk increases
Solution Approach 1:
The patent adopts a gap distance that is 1.5 times or more the tooth pitch, which balances magnetic flux density and demagnetization risk. This parameter setting maintains sufficient magnetic torque while ensuring magnet stability by preventing excessive opposing flux concentration.
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
Effectively suppresses demagnetization, enhances reluctance torque, and improves output torque by optimizing magnetic flux paths and reducing leakage flux, thereby increasing the efficiency and performance of the rotary electric machine.
Implementation Method 1
a rotary electric machine including: a stator including a stator core and a stator coil wound around the stator core; and an annular outer rotor including an outer core disposed around an outer periphery of the stator and a plurality of outer magnets arranged at intervals in a circumferential direction
Implementation Method 2
the outer magnets are magnetized in the circumferential direction such that magnetization directions of the outer magnets adjacent to each other in the circumferential direction are opposite to each other in the circumferential direction
Implementation Method 3
a stator including a stator core and a stator coil wound around the stator core
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A rotary electric machine (10) includes: a stator (14) including a stator core (26) and a stator coil (28) wound around the stator core; and an annular outer rotor (18) including an outer core (38) disposed around an outer periphery of the stator and a plurality of outer magnets (40) arranged at intervals in a circumferential direction, in which the stator core has an annular yoke (29) and a plurality of outer teeth (32) protruding radially outward from an outer periphery of the yoke, the outer magnets are magnetized in the circumferential direction such that magnetization directions of the outer magnets adjacent to each other in the circumferential direction are opposite to each other in the circumferential direction, and a circumferential distance of a gap between the outer magnets adjacent to each other is 1.5 times or more a disposition pitch in the circumferential direction of the outer teeth.