Motor Rotor Holder Magnet Halbach Array Design
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Solution Overview
Problem
The processing of permanent magnets for outer rotor type motors is challenging due to their complex shape, leading to increased costs and difficulty in manufacturing.
Innovation Solution
A motor design featuring a magnet unit with first and second magnets arranged in a Halbach array on the radially inside surface of a cylindrical rotor holder, allowing for simpler magnet shapes and easier manufacturing, with intervals between the magnets and the rotor holder for adhesive application, enhancing magnetic field distribution and reducing processing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If permanent magnets are processed into a shape along the inner circumferential surface of the cylindrical member, then the motor structure is achieved, but processing difficulty increases and manufacturing cost increases
Solution Approach 1:
The magnet unit is divided into multiple independent permanent magnets (first magnets and second magnets) with simple rectangular shapes. Each magnet is manufactured separately as a standard shape, avoiding the need to process a single complex shaped magnet. The magnets are then assembled in a specific pattern (Halbach array) on the rotor holder, achieving the required magnetic field distribution through arrangement rather than through complex individual magnet shapes.
2Ease of manufacture
If permanent magnets are processed into a shape along the inner circumferential surface of the cylindrical member, then the motor structure is achieved, but manufacturing cost increases
Solution Approach 1:
The magnet unit is divided into multiple independent permanent magnets (first magnets and second magnets) with simple rectangular shapes. Each magnet is manufactured separately as a standard shape, avoiding the need to process a single complex shaped magnet. The magnets are then assembled in a specific pattern (Halbach array) on the rotor holder, achieving the required magnetic field distribution through arrangement rather than through complex individual magnet shapes.
3Reliability
If magnets are placed directly against the rotor holder, then structural support is achieved, but magnetic saturation occurs in the rotor holder
Solution Approach 1:
The invention introduces air gaps between the magnets and the rotor holder, creating a non-uniform magnetic circuit. The gaps are strategically positioned to control magnetic flux distribution, preventing magnetic saturation in the rotor holder while maintaining effective magnetic coupling. The Halbach array arrangement of first and second magnets creates specific magnetic field patterns that work in conjunction with the gaps to optimize magnetic performance.
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 facilitates the manufacture of magnets, suppresses magnetic saturation in the rotor holder, and increases the back electromotive force constant, leading to more efficient motor performance with improved output generation.
Implementation Method 1
a magnet unit includes a plurality of first magnets 241 each of which has N and S poles magnetized in a radial direction, and a plurality of second magnets 242 each of which has N and S poles magnetized in a circumferential direction
Implementation Method 2
Magnetic poles of radially inner end portions of the first magnets adjacent to each other in the circumferential direction via the second magnet are different from each other
Data Source
AI summary
A motor includes a stationary unit including a stator and a rotation unit including a magnet unit disposed radially outward of the stator and a cylindrical rotor holder. The magnet unit is held on a radially inside surface of the rotor holder. The magnet unit includes first magnets each of which has N and S poles magnetized in a radial direction, and second magnets each of which has N and S poles magnetized in a circumferential direction. Magnetic poles of radially inner end portions of the first magnets adjacent to each other in the circumferential direction via the second magnet are different from each other. Magnetic poles of circumferential end portions of the second magnets adjacent to each other in the circumferential direction via the first magnet are different from each other. An interval is provided between a radially outside surface of each first magnet and the radially inside surface of the rotor holder, and between a radially outside surface of each second magnet and the radially inside surface of the rotor holder.