IPM Rotor Lamination Fixing for Resonance Suppression

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Solution Overview

Problem

Conventional IPM rotors with embedded magnets in a rotor core face issues with resonance and opening of the outer circumferential ends of laminations during rotation, due to vibration and magnetic forces.

Innovation Solution

The rotor design includes a shaft, a rotor core with stacked laminations, caulking portions to secure the laminations radially, and fixing portions to weld the outer peripheral edges of laminations, preventing resonance and vibration-induced opening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If laminations are stacked in the axial direction to form the rotor core, then the rotor structure is simplified and manufacturing is easier, but resonance occurs during rotation causing the outer circumferential ends of laminations to open

Engineering Contradiction:

Improverotor core assemblyVSAvoidlamination stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The rotor core is divided into multiple laminations stacked in the axial direction, with each lamination being a separate component. This segmentation allows for easier manufacturing of individual laminations while requiring a fixing mechanism to maintain their relative positions during rotation, thus resolving the contradiction between ease of manufacture and lamination stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A fixing portion is introduced as an intermediary element between the laminations to prevent their relative displacement. This fixing portion acts as a mediator that maintains the integrity of the laminated structure during rotation without complicating the manufacturing process of the individual laminations themselves.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If magnets are embedded in the rotor core, then motor performance is improved, but magnetic forces cause vibration and resonance of laminations during rotation

Engineering Contradiction:

Improvemotor outputVSAvoidvibration and resonance

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The fixing portion serves as an intermediary structure between the magnets and the laminations, providing mechanical support to the laminations against the vibrational forces generated by the embedded magnets during motor operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The rotor core employs a composite structure combining multiple laminations with a fixing portion, creating a hybrid construction that maintains the magnetic performance benefits of embedded magnets while suppressing vibration and resonance through the additional structural element.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If the rotor core uses a simple lamination structure, then manufacturing cost is reduced, but the outer circumferential ends of laminations open due to resonance during rotation

Engineering Contradiction:

Improverotor core fabricationVSAvoidlamination configuration

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The rotor core is segmented into multiple laminations that can be manufactured separately and then assembled, maintaining manufacturing simplicity while the addition of a fixing portion during assembly provides the necessary structural stability to prevent lamination separation during operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fixing portion is strategically positioned at specific locations within the rotor core structure, providing localized reinforcement only where needed to prevent lamination opening, rather than requiring a complete redesign of the entire rotor core structure.

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

This configuration enhances the natural frequency of laminations, suppresses resonance, and prevents the outer circumferential ends from opening, ensuring stable operation and controlled vibration patterns.

Implementation Method 1

The at least one fixing portion fixes at least portions of outer peripheral edges of the plurality of laminations to each other

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 2

The at least one caulking portion is disposed at a radial-directional inner side of the at least one magnet and caulks the plurality of laminations to each other

Methodology Applied

Scientific EffectCaulking: Mechanical Fastener

Data Source

PatentUS11289963B2Rotor, motor, and electric power steering device

Publication Date: 2022.03.29 NIDEC CORP(JP)

AI summary

A rotor includes a shaft, a rotor core, at least one magnet, and at least one fixing portion. The shaft extends in an axial direction. The rotor core includes laminations, and at least one caulking portion. The laminations are stacked in the axial direction. The at least one caulking portion is located at a radial-directional inner side of the at least one magnet to caulk the laminations to each other. The at least one magnet is embedded in the rotor core. The at least one fixing portion fixes at least portions of outer peripheral edges of the laminations to each other.