Rotary Electric Machine Stator with Variable Thickness Connection Portions

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Solution Overview

Problem

Existing rotary electric machines face challenges in reducing leakage magnetic flux while maintaining structural strength and preventing vibration, as previous solutions are insufficient in addressing these issues effectively.

Innovation Solution

The rotary electric machine employs connected tooth steel sheets with annular connection portions and non-connected tooth steel sheets, where the connected sheets have thinner connection portions to increase magnetic resistance and reduce leakage flux, and the non-connected sheets are stabilized by being alternately joined via swage portions to maintain structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the slot opening width is reduced to suppress vibration, then the irregularity of magnetic resistance is reduced, but the leakage magnetic flux increases and output is reduced

Engineering Contradiction:

ImprovevibrationVSAvoidoutput

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

The patent applies local quality by making the connection portions have different thickness (thinner) compared to other parts of the core sheet. This creates localized variation in magnetic resistance specifically at the connection portions, allowing the ends of teeth to be closer together (reducing vibration) while the thinner connection portions maintain higher magnetic resistance to reduce leakage flux, thus resolving the contradiction between vibration suppression and output maintenance.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If the connection portion is thinned to reduce leakage magnetic flux, then the effective magnetic flux is preserved, but the structural strength and press-forming pressure capability are compromised

Engineering Contradiction:

Improveleakage magnetic fluxVSAvoidstructural strength

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The connection portions are made thinner than other parts of the core sheet to locally increase magnetic resistance and reduce leakage flux. However, to compensate for the strength loss, multiple core sheets are stacked and joined together at the connection portions, distributing the mechanical load across multiple layers while maintaining the thin profile for magnetic flux control.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite construction by stacking multiple core sheets together. The combination of thinner connection portions in each sheet with the multi-layer stacking creates a composite structure that achieves both high magnetic resistance (for reducing leakage flux) and sufficient structural strength (through the stacked layers working together).

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If the ends of teeth are close to each other to reduce magnetic resistance irregularity, then vibration is suppressed, but leakage magnetic flux increases

Engineering Contradiction:

ImprovevibrationVSAvoidleakage magnetic flux

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent implements local quality by creating thinner connection portions at specific locations where the ends of teeth are close together. This localized thinning increases magnetic resistance precisely where needed (at the connection portions between adjacent teeth), allowing the teeth ends to be positioned closer for vibration suppression while the thinner connection portions counteract the increased leakage flux that would result from the reduced spacing.

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 effectively reduces leakage magnetic flux, enhancing the output of the motor while maintaining structural strength and minimizing vibration.

Implementation Method 1

the thickness of each connection portion is smaller than the thickness of the other part of each steel sheet... a part corresponding to the bridging portion has a greater magnetic resistance than the other parts

Methodology Applied

Scientific EffectMagnetic resistance: Magnetic Reluctance

Implementation Method 2

The connected tooth steel sheets and the non-connected tooth steel sheets are joined to each other in the axial direction via swage portions provided in the tooth portions

Methodology Applied

Scientific EffectMechanical joining: Mechanical Fastener

Data Source

PatentUS10658888B2Rotary electric machine including an inner core formed of steel sheets with connected and non-connected tooth portions and manufacturing method therefor

Publication Date: 2020.05.19 MITSUBISHI ELECTRIC CORP

AI summary

A stator is assembled by stacking, in the axial direction, a plurality of magnetic steel sheets having tooth portions. The steel sheets include connected tooth steel sheets in which the inner-circumferential-side end portions of the tooth portions are connected via connection portions in an annular shape along the circumferential direction, and non-connected tooth steel sheets which are separated from each other with the tooth portions not connected to each other. The connected tooth steel sheets and the non-connected tooth steel sheets are joined to each other in the axial direction via swage portions provided in the tooth portions. The thickness of each connection portion is smaller than the thickness of the other part of each steel sheet.