Stator Core Tightness Testing via Air Gap Nesting

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Solution Overview

Problem

Existing methods for testing the tightness of an electric machine stator core require rotor extraction, which is time-consuming, risky, and disrupts the strict time constraints of upgrades and rewinds, while also posing a risk of damage to the stator and rotor.

Innovation Solution

A device with a movable support and guide system that allows a test instrument to be introduced into the air gap between the stator core and rotor, enabling local testing of defined zones without rotor extraction, using sensors to induce and detect vibrations in the stator core packets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If rotor extraction is performed to test stator core tightness, then testing can be carried out with sufficient space, but the process becomes time-consuming and risks damaging the stator and rotor

Engineering Contradiction:
Improvetesting accessibilityVSAvoidtesting time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The test instrument is nested within the air gap between the stator core and rotor, allowing testing to be performed inside the existing structure without extraction. The movable support system enables the instrument to be inserted and retracted through the air gap, effectively nesting the testing operation within the assembled machine configuration.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

A movable support system acts as an intermediary mechanism that bridges the space constraints of the assembled machine with the testing requirements. This support system with extendable arms allows the test instrument to reach defined zones of the stator core through the air gap, mediating between the limited access space and the need for adequate testing space.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If rotor extraction is performed to test stator core tightness, then sufficient testing space is available, but the risk of stator and rotor damage increases

Engineering Contradiction:
Improvetesting accessibilityVSAvoidmachine integrity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

By nesting the test instrument within the air gap of the assembled machine, the testing operation can be performed without disassembling or extracting the rotor. This eliminates the mechanical risks associated with extraction and reassembly while maintaining testing capability through the compact nested configuration.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The movable support system serves as an intermediary that enables testing without direct contact or stress on the stator and rotor structures. The support system absorbs and isolates any testing forces, protecting the machine components from damage while still allowing effective tightness assessment.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If a compact test instrument is used in the air gap, then testing can be performed without rotor extraction, but the device complexity increases

Engineering Contradiction:
Improvetesting speedVSAvoidtest device structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The test device is segmented into modular components: a movable support system with separate positioning and testing functions, extendable arms for reaching different zones, and a compact test instrument. This segmentation allows each component to be optimized independently while maintaining overall compactness and reducing operational complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The movable support system incorporates dynamic elements such as extendable arms and adjustable positioning mechanisms that adapt to different testing zones within the air gap. This dynamic capability allows a single compact device to perform multiple testing positions and orientations, reducing the need for multiple specialized tools.

Inventive Principle:
Principle #15Dynamics

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

Enables fast and risk-free tightness testing of the stator core, allowing for precise identification of loose packets and reducing the likelihood of damage during the testing process, while accommodating various stator core configurations.

Implementation Method 1

an impactor (12) to strike a packet (4) of the stator core (2) to vibrate the packet

Methodology Applied
Scientific EffectImpact force: Impact Force

Implementation Method 2

a sensor (23, 24) to detect the vibrations of the packet (4)

Methodology Applied
Scientific EffectVibration detection: Vibration

Data Source

PatentEP2564179B1Method and device for testing the tightness of an electric machine stator core
Publication Date: 2017.11.22 GENERAL ELECTRIC TECH GMBH
  • EP2564179B1 patent drawingFigure 1~3
  • EP2564179B1 patent drawingFigure 4~6

AI summary

The method for testing the tightness of an electric machine stator core comprises: introducing a test instrument (12) that is connected to a movable support (10) into an air gap (11) between a stator core (2) and a rotor (3), locally placing the test instrument (12) and locally testing defined zones of the generator stator core (2). The invention also refers to a device for carrying out the method.