Axial Rotor Protrusion Design for Centrifugal Force Management
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Solution Overview
Problem
The existing axial-type rotary electric machines face challenges in improving torque and efficiency while maintaining a reduced rotor size, as increasing the rotor's diameter to enhance gap area leads to increased centrifugal forces, causing magnet scattering and breakage, and thickening the protrusion to counteract this force results in decreased magnet size and efficiency.
Innovation Solution
The design incorporates a rotor with a permanent magnet, yoke, and support member, where a first region on the permanent magnet's outer diameter side does not overlap with the yoke's projection, allowing for reduced radial thickness of the protrusion while maintaining strength against centrifugal forces, thus minimizing rotor diameter increase and enhancing torque and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor diameter is increased to increase the gap area, then the torque and efficiency are improved, but the centrifugal force acting on the rotor increases causing magnet scattering and breakage
Solution Approach 1:
The invention introduces a protrusion structure that extends in the axial direction (perpendicular to the radial centrifugal force direction) to support the permanent magnet. This dimensional change allows the support function to operate in a different spatial dimension, effectively counteracting the radial centrifugal force without increasing rotor diameter
Solution Approach 2:
The rotor is segmented into functional regions: a magnet arrangement region and a protrusion support region. The protrusion acts as a separate structural element that divides the support function from the magnet volume, allowing independent optimization of both torque-generating magnet size and centrifugal-force-resisting support structure
2Strength
If the protrusion thickness is increased to improve strength against centrifugal force, then the magnet scattering is suppressed, but the outer diameter of the permanent magnet decreases resulting in decreased torque and efficiency
Solution Approach 1:
The support function is moved to the axial dimension through the protrusion structure, separating it from the radial dimension where the permanent magnet volume determines torque. This allows the protrusion to provide structural strength without encroaching on the magnet's radial space
Solution Approach 2:
The protrusion creates a structural support function that copies the load-bearing role without requiring the permanent magnet itself to bear the full centrifugal load, effectively transferring mechanical stress from the magnet to the dedicated support structure
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 allows for improved torque and efficiency by reducing the radial thickness of the protrusion, suppressing magnet scattering, and maintaining strength against centrifugal forces, while enabling a higher ratio of permanent magnet diameter to rotor diameter, resulting in better manufacturing performance and reduced housing diameter.
Implementation Method 1
a permanent magnet arranged so as to face the stator core in the axial direction of the rotation axis
Implementation Method 2
a yoke arranged so as to face the stator core across the permanent magnet
Implementation Method 3
a centrifugal force acting on the rotor increases. Particularly, since the axial-type rotary electric machine has a surface-magnet configuration in which a permanent magnet is arranged on a surface of the rotor
Data Source
AI summary
An axial-type rotary electric machine that improves a torque and an efficiency relative to a size of a rotor is provided. The axial-type rotary electric machine is provided with a stator having a stator core, and a rotor facing the stator along an axial direction of a rotation axis passing through the stator. The rotor includes a permanent magnet arranged so as to face the stator core in the axial direction of the rotation axis, a yoke arranged so as to face the stator core across the permanent magnet, and a support member supporting the yoke. The support member includes a protrusion protruding so as to face a side surface of the permanent magnet that is on the farther side to the rotation axis. In projection along the axial direction of the rotation axis, a first region where a projecting portion of the permanent magnet does not overlap a projecting portion of the yoke is formed in the permanent magnet, and the first region is formed on the outer-diameter side of the permanent magnet and the first region is formed on a side of the protrusion.