Continuous Skew Rotor for Rotary Electric Machine

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Solution Overview

Problem

Existing rotary electric machine rotors with stepped skew structures struggle to significantly reduce cogging torque and torque ripple due to limited suppression of rapid magnetic flux changes in the circumferential direction.

Innovation Solution

A rotor core with a stacked structure of magnetic sheets shifted by a constant angle in the circumferential direction and through holes forming continuous magnet insertion holes, allowing permanent magnets to be twisted and inserted, creating a continuous skew structure that reduces cogging torque and torque ripple.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a stepped skew structure is used to reduce cogging torque and torque ripple, then the structure complexity increases, but the suppression effect on rapid magnetic flux changes remains limited

Engineering Contradiction:

Improvecogging torque and torque rippleVSAvoidstacked structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The rotor core is segmented into multiple magnetic sheets stacked in the axial direction, with each sheet containing through holes for permanent magnets. This segmentation enables the formation of a continuous skew structure that extends along the axial direction, effectively suppressing rapid magnetic flux changes and reducing cogging torque and torque ripple while maintaining manageable structural complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a two-dimensional stepped skew structure to a three-dimensional continuous skew structure by extending the skew along the axial direction through multiple stacked magnetic sheets. This dimensional change creates a more effective skew structure that better suppresses magnetic flux variations without excessively increasing complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If multiple magnetic sheets are stacked with constant angle shift to form continuous skew structure, then cogging torque and torque ripple are reduced, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvecogging torque and torque rippleVSAvoidpositioning precision of through holes

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The through holes are pre-formed in each magnetic sheet before stacking, with their positions and angles precisely determined in advance. This preliminary action ensures that when the magnetic sheets are stacked, the through holes align to form continuous magnet insertion holes, reducing the need for high-precision post-assembly adjustments and lowering overall manufacturing precision requirements

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Each magnetic sheet is designed with specific local characteristics, including through holes at predetermined positions and angles. This local quality approach allows each sheet to be manufactured independently with controlled precision, and the cumulative effect of multiple sheets creates the overall continuous skew structure, distributing the precision requirements across multiple components rather than requiring one highly precise assembly

Inventive Principle:

Principle #3Local quality

3Device complexity

If permanent magnets are twisted and inserted into magnet insertion holes to form continuous skew structure, then the number of components is reduced, but the ease of manufacture decreases

Engineering Contradiction:

Improvenumber of componentsVSAvoidmagnet insertion process

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The permanent magnets are divided into multiple segments, with each segment inserted into corresponding through holes in different magnetic sheets. This segmentation allows the magnets to be installed piece by piece through pre-formed holes, simplifying the insertion process compared to installing one large twisted magnet, while still achieving the continuous skew structure effect

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The magnet insertion holes are pre-formed in the magnetic sheets before the magnet insertion process. This preliminary action prepares the insertion paths in advance, making it easier to insert the permanent magnet segments without requiring complex real-time alignment or twisting operations during assembly, thereby improving ease of manufacture

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11264878B2Rotor for rotary electric machine and method of manufacturing rotary electric machine

Publication Date: 2022.03.01 AISIN SEIKI KK

AI summary

A rotor for a rotary electric machine, wherein: magnet insertion holes are formed, each defined by the plurality of through holes communicating with each other in the axial direction across the plurality of magnetic sheets; and each of the permanent magnets is twisted about the center axis so as to be placed into a corresponding one of the magnet insertion holes, each having opposite ends in the axial direction that are shifted from each other by an angle corresponding to the constant angle, from outside in the axial direction.