Permanent magnet embedded motor, compressor, and refrigerating and air conditioning apparatus

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Solution Overview

Problem

Conventional permanent magnet embedded motors face issues with degraded magnetic properties, increased noise and vibration, and reduced motor efficiency due to insufficient rigidity and inner-diameter roundness of the stator core, as well as increased magnetic reluctance caused by gaps in the yoke portions when a cylindrical frame is fitted onto the stator core.

Innovation Solution

A permanent magnet embedded motor design that stacks first and second annular cores with specific swaging portions, where the first annular core pieces are in contact and the second annular core pieces are separated, allowing for improved contact and reduced compressive stress, enhancing motor efficiency and reducing vibration levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a cylindrical frame is fitted and fixed onto a stator core configured by combining a plurality of core pieces into an annular shape, then the rigidity of the stator core is increased and the inner-diameter roundness is improved, but the magnetic properties of the stator core degrade

Engineering Contradiction:

Improverigidity of stator coreVSAvoidmagnetic properties of stator core

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The stator core is divided into a first annular core and a second annular core that are stacked in the axial direction. Each annular core is further divided into multiple core pieces that are disposed in the circumferential direction. This segmentation allows the frame to be fitted onto the stacked configuration, distributing the mechanical stress and reducing compression on individual core pieces, thereby maintaining magnetic properties while achieving sufficient rigidity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a single-layer annular core configuration to a multi-layer stacked configuration in the axial direction. By stacking the first and second annular cores, the structure gains rigidity in the radial direction without increasing the circumferential compression on individual core pieces, thus preserving magnetic properties while achieving the required structural strength.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Shape

If the adjacent core pieces are in contact with each other to increase rigidity, then the inner-diameter roundness is improved, but compressive stress increases in the main magnetic-flux region

Engineering Contradiction:

Improveinner-diameter roundness of stator coreVSAvoidcompressive stress in main magnetic-flux region

Core Design Contradiction:

ShapeVSStress or pressure

Solution Approach 1:

The stator core is segmented into multiple core pieces disposed in the circumferential direction, with each core piece including contact portions that contact adjacent core pieces. This segmentation allows controlled contact points that provide sufficient roundness while limiting the area of compressive stress application, preventing excessive stress in the main magnetic-flux region.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the rigidity of the stator core is insufficient, then the manufacturing is easier, but the noise and vibration level increases

Engineering Contradiction:

Improveease of assembling core piecesVSAvoidnoise and vibration level

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The stator core is divided into multiple core pieces that can be independently manufactured and then assembled by stacking the first and second annular cores. This segmentation simplifies manufacturing of individual pieces while the stacked configuration with contact portions ensures sufficient overall rigidity to minimize noise and vibration during operation.

Inventive Principle:

Principle #1Segmentation

4Ease of manufacture

If there is a gap in the magnetic path in the yoke portion, then the assembly of divided yoke portions is simplified, but the magnetic reluctance increases

Engineering Contradiction:

Improveassembly of divided yoke portionsVSAvoidmagnetic reluctance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The yoke portion is divided into multiple core pieces disposed in the circumferential direction, with contact portions that contact adjacent core pieces. This segmentation simplifies assembly by allowing independent manufacturing of core pieces, while the contact portions ensure continuous magnetic paths without gaps, preventing increase in magnetic reluctance.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10804754B2Permanent magnet embedded motor, compressor, and refrigerating and air conditioning apparatus

Publication Date: 2020.10.13 MITSUBISHI ELECTRIC CORP

AI summary

A permanent magnet embedded motor includes a cylindrical stator core disposed on an inner side of a cylindrical frame and configured by stacking a first annular core and a second annular core disposed to be adjacent to the first annular core in an axial direction of the frame, and a rotor disposed on an inner side of the stator core. The second annular core is fixed to the first annular core by using swaging portions formed in the second annular core, and adjacent first yokes are in contact with each other, while adjacent second yokes are separated from each other.