Asymmetrical Rotor Geometry for Symmetrical Bidirectional Performance

Solution Overview

Problem

Conventional electric motors with symmetrical construction exhibit identical performance in both forward and reverse directions, but introducing asymmetry for improved performance results in loss of symmetrical motor performance.

Innovation Solution

A rotor design featuring arcuately arranged pole segments and magnets with axially varying widths and angular offsets, along with a hub and bridges, allows for symmetrical performance in both directions by maintaining a symmetrical flux distribution and inductance profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If asymmetrical rotor construction is introduced to improve performance under certain operating conditions, then performance under specific conditions is improved, but symmetrical motor performance is lost

Engineering Contradiction:

Improveperformance under certain operating conditionsVSAvoidsymmetrical motor performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The rotor employs asymmetrical pole segments with varying axial widths and non-uniform angular spacing. Specifically, adjacent pole segments have different axial widths, and the angular spacing between pole segments varies around the rotor circumference. This deliberate asymmetry improves performance under certain operating conditions while the overall design maintains functional balance through the alternating pattern of wider and narrower pole segments.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Different portions of the rotor are designed with locally optimized characteristics. The pole segments feature varying axial widths at different angular positions, with some segments being wider than others. This local variation in geometry allows each region to be optimized for specific operational requirements while contributing to the overall asymmetrical design that improves performance under certain conditions.

Inventive Principle:

Principle #3Local quality

2Reliability

If symmetrical construction is used to maintain identical performance in both forward and reverse directions, then symmetrical motor performance is maintained, but performance improvement under certain operating conditions is limited

Engineering Contradiction:

Improvesymmetrical motor performanceVSAvoidperformance under certain operating conditions

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The rotor employs asymmetrical pole segments with varying axial widths and non-uniform angular spacing. Specifically, adjacent pole segments have different axial widths, and the angular spacing between pole segments varies around the rotor circumference. This deliberate asymmetry improves performance under certain operating conditions while the overall design maintains functional balance through the alternating pattern of wider and narrower pole segments.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Different portions of the rotor are designed with locally optimized characteristics. The pole segments feature varying axial widths at different angular positions, with some segments being wider than others. This local variation in geometry allows each region to be optimized for specific operational requirements while contributing to the overall asymmetrical design that improves performance under certain conditions.

Inventive Principle:

Principle #3Local quality

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

The design achieves identical performance in both forward and reverse directions with improved flux concentration and reduced flux leakage, without requiring material upgrades or additional components, while maintaining structural strength and cost-effectiveness.

Implementation Method 1

a rotor for use in an electric motor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a plurality of arcuately arranged magnets configured and arranged to facilitate symmetrical motor performance

Methodology Applied

Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentUS20260081487A1Asymmetrical rotor with symmetrical performance

Publication Date: 2026.03.19 NIDEC MOTOR CORP

AI summary

A symmetrically performing motor includes an asymmetrical rotor. The rotor includes a core and a plurality of arcuately arranged magnets. The core includes a hub, a plurality of pole segments, and a plurality of bridges extending between and interconnecting respective ones of the pole segments to the hub. Each of the bridges has an axially varying width. The pole segments are swept in form such that the rotor core exhibits mirror asymmetry. Each of the pole segments includes a body, a head disposed radially adjacent the body, and a pair of arcuately spaced apart ears extending generally tangentially outwardly from the head. The head defines an arcuate outer head face extending along an outer rotor margin. Each of the ears defines a respective outer ear face disposed inward of the outer rotor margin. Each of the outer ear faces defines an ear angle relative to the outer rotor margin.