Rotor Magnet Protruded Surface Torque Enhancement
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Solution Overview
Problem
Conventional inner rotor type motors face challenges in increasing magnetic force and torque without enlarging the rotor diameter, as they typically utilize only the radially outer magnetic pole surfaces, limiting the effective use of magnetic material.
Innovation Solution
A rotor design featuring a cylindrical shape with a magnetic core and alternately arranged magnets, where one circumferential end surface is protruded and the other is flat, allowing for increased magnetic volume without expanding the rotor diameter, enabling enhanced magnetic force and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the rotor diameter is increased to increase magnetic force, then the magnetic force increases, but the motor size increases
Solution Approach 1:
The magnet shape is changed from a conventional rectangular parallelepiped to a shape with a protruded circumferential end surface, utilizing the circumferential dimension more effectively. This dimensional change allows the magnet to extend further in the circumferential direction, increasing the effective magnetic pole surface area without increasing the rotor's radial diameter, thus increasing magnetic force while maintaining compact size.
Solution Approach 2:
The magnet is designed with non-uniform geometry, featuring a protruded portion at one circumferential end surface while maintaining a standard rectangular shape at the other end. This local quality variation optimizes the magnetic pole surface area distribution, allowing concentrated magnetic field generation at critical positions without requiring a larger overall rotor diameter.
2Ease of manufacture
If conventional rectangular magnets are used in spoke type rotor, then manufacturing is simple, but magnetic force is limited by magnet volume
Solution Approach 1:
The magnet geometry parameters are modified by introducing a protruded dimension at one circumferential end surface. This parameter change increases the magnet's effective volume and magnetic pole surface area, thereby enhancing magnetic force generation while maintaining compatibility with conventional manufacturing processes for bonded 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 design effectively increases the magnetic force and torque of the motor without increasing the rotor diameter, improving motor performance while reducing manufacturing costs and preventing magnet displacement.
Implementation Method 1
The magnet has a pair of circumferential end surfaces which are magnetic pole surfaces. The magnetic pole surfaces having identical polarity of the plurality of magnets are configured to face one another in a circumferential direction
Data Source
AI summary
Provided is a rotor for use in an inner rotor-type motor, comprising a plurality of magnets arranged in a circumferential direction around the center axis, and a rotor core formed of a magnetic material. The rotor core has an inner core part and a plurality of outer core parts. The plurality of outer core parts and the plurality of magnets are alternately arranged in a circumferential direction at a radially outer side of the inner core part. The magnet has a pair of circumferential end surfaces which are magnetic pole surface, and at least one of them is a protruded surface. Also, the magnet has a portion of which circumferential width is wider than a circumferential width of an outer end surface. For this reason, the volume of the magnet can be increased and the magnetic force of the rotor can be increased, without the need to increase the diameter of the rotor. As a result, when such rotor is incorporated into a motor, the torque of the motor can be improved.