Motor, rotor, compressor, and refrigeration and air conditioning apparatus
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Solution Overview
Problem
Permanent magnets in embedded type motors are prone to demagnetization due to magnetic flux flowing through magnet holding portions made of the same magnetic material as the rotor core, leading to reduced motor performance and efficiency.
Innovation Solution
The motor design includes a rotor core with magnet insertion holes and magnet holding portions where the opening is positioned on the radially inner side of the first magnet holding portion, increasing magnetic resistance and reducing the flow of magnetic flux through the holding portion, thereby suppressing demagnetization. Additionally, the use of rare earth magnets without dysprosium and strategic placement of openings and holes to enhance cooling and reduce demagnetization risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnet holding portions are made of the same magnetic material as the rotor core, then the permanent magnets can be securely positioned, but magnetic flux flows through the magnet holding portions causing demagnetization of the permanent magnets
Solution Approach 1:
The magnet holding portion is designed with non-magnetic material in the region adjacent to the permanent magnet, while other portions may retain magnetic material for positioning function. This local differentiation prevents magnetic flux from flowing through the holding portion to the permanent magnet, thereby suppressing demagnetization while maintaining positioning capability.
Solution Approach 2:
A non-magnetic material is introduced as an intermediary between the magnetic rotor core and the permanent magnet. This intermediary blocks the magnetic flux path that would otherwise cause demagnetization, while still allowing the magnet holding portion to perform its positioning function through mechanical means.
2Reliability
If openings are positioned close to the magnet insertion hole, then magnetic resistance through the magnet holding portion increases suppressing demagnetization, but the structural integrity of the rotor core may be compromised
Solution Approach 1:
The position, size, and shape of the opening are optimized to achieve the right balance. By carefully controlling these parameters, the opening can be placed close enough to the magnet insertion hole to increase magnetic resistance and suppress demagnetization, while maintaining sufficient structural integrity of the rotor core.
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 increases the magnetic resistance through the magnet holding portions, effectively suppresses demagnetization, widens the usable current range, reduces the need for dysprosium, and enhances motor efficiency and stability, especially in high-temperature applications like refrigeration and air conditioning compressors.
Implementation Method 1
By disposing the opening as described above, magnetic resistance through the first magnet holding portion increases, and magnetic flux is less likely to flow through the first magnet holding portion
Implementation Method 2
magnetic flux from a stator tends to flow through the magnet holding portion when the motor is driven
Implementation Method 3
a motor in which permanent magnets are mounted on a rotor is known
Data Source
AI summary
A motor includes a stator and a rotor provided inside the stator. The rotor includes a rotor core having a magnet insertion hole and two permanent magnets disposed in the magnet insertion hole. The rotor core has a first magnet holding portion disposed between the two permanent magnets and holding the two permanent magnets, an opening disposed on an inner side of the first magnet holding portion in a radial direction of the rotor core, and a center hole disposed at a center of the rotor core in the radial direction. A distance from the opening to the magnet insertion hole is shorter than a distance from the opening to the center hole.