Rotor Magnet Positioning for Rotary Electric Machine Angle Sensing
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Solution Overview
Problem
Conventional rotary electric machines face challenges in accurately sensing the rotational angle of the rotor, which affects the control of the machine, due to misalignment between assembly and magnetization references.
Innovation Solution
A rotor design for rotary electric machines featuring a ring-shaped magnet with only one pair of point-symmetric magnet-side positioning portions that serve as both the magnetization and assembly reference, reducing misalignment and improving sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate assembly reference and magnetization reference are used, then the magnet can be assembled to the rotor core, but misalignment between the two references reduces rotational angle sensing accuracy
Solution Approach 1:
The patent combines the assembly reference and magnetization reference into a single integrated reference system. The magnet includes only one pair of positioning portions that serve dual functions: guiding assembly of the magnet to the rotor core and providing the magnetization reference. This merging eliminates misalignment between separate references, improving rotational angle sensing accuracy while reducing the number of positioning portions needed.
Solution Approach 2:
The positioning portions on the magnet are designed to perform multiple functions simultaneously. The same positioning portions that guide the assembly process also serve as the magnetization reference. This multi-functionality resolves the contradiction by eliminating the need for separate assembly and magnetization references, thereby improving sensing accuracy without increasing device complexity.
2Manufacturing precision
If multiple pairs of positioning portions are provided for assembly and magnetization references, then alignment accuracy improves, but the device complexity and number of parts increase
Solution Approach 1:
The patent merges the assembly reference and magnetization reference into a single integrated system using one pair of positioning portions. This positioning portion simultaneously ensures accurate assembly alignment and provides the magnetization reference, eliminating the need for multiple separate positioning features while maintaining high alignment accuracy.
Solution Approach 2:
The positioning portions are designed with universal functionality to perform both assembly guidance and magnetization referencing. This multi-functional design achieves high alignment accuracy without increasing the number of positioning portions, thereby resolving the contradiction between manufacturing precision and device complexity.
3Ease of manufacture
If only one pair of magnet-side positioning portions is used, then the device complexity is reduced and manufacturing is simplified, but adequate positioning accuracy must be maintained
Solution Approach 1:
The patent simplifies manufacturing by using only one pair of magnet-side positioning portions that simultaneously serve as both assembly reference and magnetization reference. This merging of functions reduces the number of positioning features needed while maintaining adequate positioning accuracy through the dual-role design of the positioning portions.
Solution Approach 2:
The positioning portions are designed with universal functionality to perform both assembly guidance and magnetization referencing with a single pair of features. This multi-functional approach simplifies manufacturing processes and reduces part count while maintaining the positioning accuracy required for rotational angle sensing.
Data Source
AI summary
A rotor of a rotary electric machine includes a magnet that is a ring member arranged coaxially with a rotor core and assembled to an axial end part of the rotor core. The magnet is used for sensing a rotational angle of the rotor. The rotor core includes only one pair of core-side positioning portions which are arranged to be point-symmetric about a rotational axis. The magnet includes only one pair of magnet-side positioning portions which are arranged to be point-symmetric about the rotational axis. The magnet-side positioning portions are engaged with the core-side positioning portions, respectively, to position the magnet relative to the rotor core in a first direction, a second direction and a circumferential direction, and the magnet-side positioning portions are used as both a magnetization reference and an assembly reference.