Segmented Stator Frame with Threaded Steel Bars

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Solution Overview

Problem

Existing motor stator carcasses face challenges in being resistant to distortion and cost-effective while maintaining a reduced bulk, as one-piece cast iron carcasses are heavy and costly, while steel carcasses with multiple parts are prone to distortions and hot spots due to internal stresses from welding.

Innovation Solution

A motor stator carcass composed of two cast iron plates connected by steel bars and threaded sleeves, where the bars are secured through threaded conduits and clamping heads, providing structural integrity and reduced mass without the need for extensive welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a one-piece cast iron carcass is used, then strength and rigidity are improved, but weight increases and cost increases

Engineering Contradiction:
Improvecarcass strengthVSAvoidcarcass weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The carcass is divided into multiple components: cast iron end plates and steel bars, connected through threaded sleeves and clamping heads. This segmentation allows each material to be used where most beneficial - cast iron for the plates providing rigidity and steel for the bars providing tensile strength, while reducing overall weight compared to a solid cast iron structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention combines cast iron and steel materials in a composite structure. The end plates are made of cast iron while the connecting bars are made of steel, creating a hybrid structure that optimizes the properties of both materials to achieve the desired strength-to-weight ratio.

Inventive Principle:
Principle #40Composite materials

2Weight of moving object

If a multi-part welded steel carcass is used, then weight is reduced, but manufacturing cost increases and distortion risk increases

Engineering Contradiction:
Improvecarcass weightVSAvoidmanufacturing cost
Core Design Contradiction:
Weight of moving objectVSEase of manufacture

Solution Approach 1:

The carcass is segmented into modular components (end plates and bars) that can be manufactured separately and assembled through threading rather than welding. This reduces manufacturing complexity and cost while maintaining structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Threaded sleeves act as intermediary components between the cast iron end plates and steel bars, providing a standardized connection interface that simplifies assembly and reduces manufacturing cost compared to custom welded joints.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Weight of moving object

If a multi-part welded steel carcass is used, then weight is reduced, but distortion and magnetic imbalance risk increase

Engineering Contradiction:
Improvecarcass weightVSAvoidcarcass stability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

By segmenting the structure and using threaded connections instead of welding, the invention eliminates the thermal stresses and distortions associated with welding while maintaining structural integrity and dimensional stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection method is changed from welding (thermal process) to threading (mechanical process), fundamentally changing the parameters of the joining process to eliminate thermal distortion and magnetic imbalance risks.

Inventive Principle:
Principle #35Parameter changes

4Strength

If a one-piece cast iron carcass is used, then strength is improved, but manufacturing cost increases

Engineering Contradiction:
Improvecarcass strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The carcass is segmented into separately manufacturable components that can be produced using standard casting and machining processes, then assembled through standardized threading operations, reducing overall manufacturing cost compared to producing a single complex cast iron piece.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The threaded sleeves serve multiple functions: they provide structural connection, enable disassembly and assembly, and allow for standardization of manufacturing processes across different carcass configurations, reducing overall manufacturing cost.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3273575B1Screwed stator frame for an electric motor and associated manufacturing process
Publication Date: 2020.04.29 ALSTOM TRANSPORT TECH SAS
  • EP3273575B1 patent drawingFigure 1~2
  • EP3273575B1 patent drawingFigure 3~4

AI summary

Motor stator frame (10) comprising: - two cast iron plates (12); and - at least one steel bar (14) connecting the two plates (12), each bar (14) having two threaded ends; characterized in that the frame (10) further comprises at least one threaded bushing (22) and in that each of the plates (12) comprises at least one orifice serving as a seat for each threaded bushing (22), the threaded ends of each bar (14) being engaged in the threaded bushings (22).