Stator Laminated Core Axial Bars for Rigidity

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Solution Overview

Problem

Stator laminated cores in electrical machines, particularly in POD drives for ships, face challenges in achieving high rigidity and compact structure while maintaining hydrodynamic efficiency, which is compromised due to lower stiffness and material constraints.

Innovation Solution

The stator laminated core incorporates ring-shaped or disk-shaped pressure plates connected by axial bars, with bolts providing clamping forces and increased rigidity, and optional baking lacquer treatment, along with a slim design that integrates bolts into the yoke for enhanced heat dissipation and reduced material costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the stator laminated core is designed with a slim structure for hydrodynamic efficiency, then the outer diameter is reduced and flow behavior is improved, but the rigidity and stiffness of the structure deteriorate

Engineering Contradiction:
Improveouter diameterVSAvoidrigidity
Core Design Contradiction:
ShapeVSStrength

Solution Approach 1:

The stator laminated core is divided into multiple individual laminations stacked together, with each lamination containing grooves for windings. This segmentation allows the core to maintain a slim outer diameter while the stacked structure with inter-lamination bonding provides the necessary rigidity and stiffness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stator laminated core uses composite construction combining multiple electrical steel laminations with insulating coatings, bonded together through brazing or welding of ribs. This composite structure achieves high rigidity in a slim package, resolving the contradiction between reduced outer diameter and maintained structural strength.

Inventive Principle:
Principle #40Composite materials

2Strength

If the stator laminated core uses a large yoke height to increase rigidity, then the structural stiffness is improved, but the outer diameter increases and hydrodynamic behavior deteriorates

Engineering Contradiction:
ImproverigidityVSAvoidouter diameter
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

Instead of increasing rigidity by increasing yoke height in the radial dimension, the patent uses axial dimension strategies: stacking multiple thin laminations and adding rib structures that extend axially. This provides the necessary rigidity without increasing the radial outer diameter, maintaining hydrodynamic efficiency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If conventional clamping methods are used without additional rigidity devices, then the manufacturing process is simple, but the rigidity of the laminated core is insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidrigidity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The rib structures serve dual functions: they provide the necessary rigidity and structural support, and simultaneously act as clamping elements to hold the laminations together during assembly. This merging of functions eliminates the need for separate clamping devices, maintaining manufacturing simplicity while achieving high rigidity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The rib structures are designed to automatically provide both clamping force and rigidity enhancement. During assembly, the ribs self-align and self-clamp the laminations while providing the structural reinforcement needed, without requiring additional active control or complex mechanisms.

Inventive Principle:
Principle #25Self-service

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 enhances the rigidity and heat dissipation of the stator laminated core, enabling a slim design that improves hydrodynamic behavior and reduces material and operational costs, while maintaining structural stability and efficiency.

Implementation Method 1

The bolts allow axial clamping forces to be exerted on the laminated core

Methodology Applied
Scientific EffectClamping force: Compression

Implementation Method 2

its rigidity is additionally increased by baking lacquer, that is to say by baking lacquer treatment of the laminated core

Methodology Applied
Scientific EffectBaking lacquer treatment: Heat Treatment

Implementation Method 3

The bars are, for example, flat bars, flat strips or round bars. The bars in particular run essentially axially parallel.

Methodology Applied
Scientific EffectWelding: Welding

Implementation Method 4

The use of the bolts can mean a slightly higher amount of material, but this can be compensated for by the optimized manufacturing process.

Methodology Applied
Scientific EffectHeat dissipation: Conduction (thermal)

Data Source

PatentEP3326265B1Laminated stator sheet package and manufacturing method
Publication Date: 2020.02.12 SIEMENS AG
  • EP3326265B1 patent drawingFigure 1
  • EP3326265B1 patent drawingFigure 2
  • EP3326265B1 patent drawingFigure 3

AI summary

A stator core (1) comprises pressure plates (2, 4) and a plurality of bars (3) which interconnect the at least two pressure plates (2, 4), the pressure plates (2, 4) being in particular terminal pressure plates (2, 4). The bars (3) are at least partly located in the gaps (48) between core plates. The bars (3) and the pressure plates (2, 4) are welded together. The stator core is suitable especially for a pod drive.