Electric Motor Stator Tooth Vibration Reduction

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Solution Overview

Problem

Electric motors and generators generate undesirable noise due to relative movement between the teeth of the rotor and stator caused by fluctuating magnetic flux fields, leading to vibration.

Innovation Solution

Mechanical connection of the free ends of the teeth and stiffening the core via welds or retaining members to inhibit relative movement and reduce vibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the teeth are left mechanically independent, then the manufacturing process is simpler, but the relative movement between teeth causes vibration and noise

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidnoise and vibration

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent merges the teeth into a single mechanically integrated structure by providing a core body that substantially integrates the teeth, eliminating relative movement between them while they remain magnetically independent. This integration prevents the harmful relative motion that causes noise and vibration.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The core is segmented into multiple teeth that are mechanically integrated but magnetically independent, allowing each tooth to function independently in the magnetic circuit while being structurally unified to prevent relative movement.

Inventive Principle:

Principle #1Segmentation

2Strength

If retaining members are added to connect tooth ends, then the structural stiffness increases, but the device complexity increases

Engineering Contradiction:

Improvestructural stiffnessVSAvoidcomponent count

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The retaining members are integrated into the core body structure, merging the function of structural reinforcement with the core itself. This approach increases stiffness while minimizing additional complexity by making the retaining members an integral part of the core rather than separate attachable components.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If welds are used to stiffen the core, then the structural integrity improves, but the manufacturing complexity increases

Engineering Contradiction:

Improvestructural integrityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the manufacturing parameter from mechanical assembly to welding, creating a permanently integrated core structure. This parameter change improves structural integrity and reliability by eliminating relative movement, though it increases manufacturing complexity through the welding process.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8567043B2Method of assembling low noise rotor or stator of an electric motor or generator

Publication Date: 2013.10.29 NIDEC MOTOR CORP

AI summary

A stator or rotor of an electric motor or generator comprises a core formed of ferromagnetic material having a plurality of teeth arranged circumferentially about an axis. In one aspect of the invention, at least one retaining member connects the end portions of at least two of the teeth to each other in a manner inhibiting relative movement between said tooth end portions. By inhibiting relative movement between said tooth end portions, vibration is reduced. Vibration can also be reduced by welding interior surfaces of a core to each other. Reducing the vibration reduces the noise emissions of the rotor or stator during operation.