Rotor Through-Hole Layout for High-Torque Compact Electric Machines
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Solution Overview
Problem
Existing rotary electric machines face challenges in reducing size and weight while maintaining high torque output, especially at low rotational speeds, which is crucial for applications like flying objects.
Innovation Solution
The rotary electric machine design incorporates a stator with a yoke portion and teeth portions, and a rotor with a stacked body of electromagnetic steel sheets and permanent magnets, optimizing the ratio of rotor inner to outer diameter and increasing the number of poles to 16 to 32, thereby achieving high torque without increasing machine size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the size of the motor is increased to obtain high torque at low rotational speed, then the torque output is improved, but the weight of the motor is increased
Solution Approach 1:
The rotor core is divided into multiple electromagnetic steel sheets stacked together, with through holes formed in each sheet. This segmentation allows for a compact design while maintaining structural integrity and magnetic flux density, achieving high torque without increasing overall motor size and weight
Solution Approach 2:
The invention optimizes the ratio of rotor inner diameter to outer diameter to be within 1:1.5 to 1:3.5, and increases the number of permanent magnet poles to 16-32. These parameter changes enable high torque density in a compact rotor structure, improving torque output without proportionally increasing motor weight
2Force
If the inner diameter of the rotor is increased to accommodate a large bearing for high torque, then the torque capacity is improved, but the outer diameter of the rotor has to be increased making the rotary electric machine large
Solution Approach 1:
By optimizing the rotor inner diameter to outer diameter ratio within 1:1.5 to 1:3.5 and increasing the number of poles to 16-32, the invention achieves high torque capacity in a compact rotor. This allows for a smaller overall machine size while maintaining the required torque output through increased magnetic pole density rather than simply scaling up dimensions
Solution Approach 2:
The rotor core uses stacked electromagnetic steel sheets with integrated through holes and coupling portions, creating a composite structure that provides both mechanical strength for bearing support and optimized magnetic flux paths. This composite approach enables high torque capacity without requiring a large rotor volume
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 design allows for the achievement of high torque while significantly reducing the size and weight of the rotary electric machine, making it suitable for applications requiring compact and lightweight motors.
Implementation Method 1
the electromagnetic coils are energized. With the energization, the electromagnetic coils are magnetized to form an alternating magnetic field. The alternating magnetic field and the magnetic field generated by the permanent magnets repel each other. Alternatively, the two magnetic fields attract each other. The above repulsion and attraction cause the rotor to rotate.
Implementation Method 2
the rotor has permanent magnets... the magnetic field generated by the permanent magnets repel each other. Alternatively, the two magnetic fields attract each other.
Data Source
AI summary
A rotor of a rotary electric machine includes a rotor core. The rotor core is a stacked body in which a plurality of electromagnetic steel sheets are stacked. The electromagnetic steel sheet includes an inner annular portion and an outer annular portion. A first insertion hole into which a rotating shaft is inserted is formed in the inner annular portion. A rotor inner diameter is defined as twice a distance from a center of the first insertion hole to an inner circumferential edge of the inner annular portion. A rotor outer diameter is defined as twice a distance from the center of the first insertion hole to an outer circumferential edge of the outer annular portion. A ratio of the rotor inner diameter to the rotor outer diameter is within a range of 1:1.5 to 1:3.5.