Electric Machine Rotor Lamination N-Star Web Configuration

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Solution Overview

Problem

Existing sheet metal sections for electrical machine rotors are prone to material inefficiency and weight issues due to radially acting centrifugal forces, which can weaken the connection between the rotor shaft and laminated core, leading to mechanical and electromagnetic stress.

Innovation Solution

A sheet metal section design featuring a central connecting means with an inner area forming an n-star configuration, where webs connect magnetic poles and transmit centrifugal forces tangentially, reducing radial forces on the connecting means and optimizing material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conventional sheet metal section design with radial force transmission is used, then the connection to the rotor shaft is simple, but the centrifugal forces act radially on the connecting means which can weaken the shrink connection and lead to material inefficiency and excessive weight

Engineering Contradiction:
Improveconnection strengthVSAvoidrotor weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The inner area is segmented into multiple webs arranged in an n-star configuration, where each web connects two magnetic poles. This segmentation allows the centrifugal forces to be distributed and transmitted tangentially through multiple paths rather than radially through a single connecting means, reducing the radial load on the rotor shaft connection while maintaining structural strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The force transmission direction is changed from radial (one dimension) to tangential (another dimension). The webs in the n-star configuration transmit centrifugal forces tangentially along the circumferential direction, converting the radial force problem into a tangential force distribution system, which prevents radial widening of the connecting means and preserves the shrink connection integrity.

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

2Reliability

If more material is used to strengthen the connection and reduce radial forces, then the connection strength improves, but the rotor weight increases and material efficiency decreases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidrotor weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The n-star configuration provides localized structural support at critical positions where webs connect magnetic poles, rather than uniformly distributing material throughout the entire inner area. This localized reinforcement maintains connection reliability through strategic web placement while minimizing overall material usage and rotor weight.

Inventive Principle:
Principle #3Local quality

3Weight of moving object

If the sheet metal section uses minimal material to reduce weight, then material efficiency improves, but the mechanical and electromagnetic performance may be compromised

Engineering Contradiction:
Improverotor weightVSAvoidmechanical strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The inner area is divided into multiple webs forming an n-star pattern, where each web acts as an independent load-bearing element. This segmentation allows the structure to achieve high mechanical strength through distributed force paths while using minimal material, as each web is optimized for its specific load path rather than requiring a solid continuous structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sheet metal section combines magnetic poles with the n-star web configuration to create a composite structure that simultaneously provides electromagnetic functionality and mechanical strength. The integration of magnetic poles into the web structure allows dual functionality with minimal material.

Inventive Principle:
Principle #40Composite materials

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 design enhances mechanical and electromagnetic performance by minimizing material usage, achieving maximum speed stability and a robust connection between the sheet metal section and rotor shaft, while reducing the weight of the rotor.

Implementation Method 1

Strong magnetic and mechanical forces occur when an electrical machine is in operation. Due to the rotor rotating in the stator, strong centrifugal forces act on the individual magnetic poles.

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

the magnetic fields generated by the magnets of the rotor, in particular by the permanent magnets, and the magnetic fields coupled into the rotor by the stator field cause reluctance forces or electromagnetic forces

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 3

the magnetic fields generated by the magnets of the rotor, in particular by the permanent magnets, and the magnetic fields coupled into the rotor by the stator field

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP3410571B1Metal sheet for a rotor of an electric machine, rotor for an electric machine, and electrical machine comprising rotor
Publication Date: 2021.04.07 VOLKSWAGEN AG
  • EP3410571B1 patent drawingFigure 1
  • EP3410571B1 patent drawingFigure 2
  • EP3410571B1 patent drawingFigure 3a~3b

AI summary

To provide a lamination for an electric machine rotor that is electromagnetically and mechanically optimized and exhibits maximum performance with minimal material usage and weight while maintaining the necessary speed stability, and to provide a lamination for an electric machine rotor that features an improved connection between the lamination and a shaft, in particular a rotor shaft, a lamination (100) for an electric machine rotor is proposed, wherein the lamination (100) has a central connecting element (10) for connection with a shaft, wherein the lamination (100) has, with respect to a radial direction (12), an outer area (14) extending in a circumferential direction (15) and an inner area (13) arranged between the outer area (14) and the connecting element (10) extending in a circumferential direction (15), wherein the outer area (14) n, n ≥ 2,having magnetic poles (16) distributed along the circumferential direction (15), wherein the magnetic poles (16) are arranged corresponding to the vertices of a first n-gon (23), in particular a regular one, wherein the inner region (13) has webs (21), each web (21) connecting two magnetic poles (16, 16a, 16b) and/or extending between two magnetic poles (16, 16a, 16b), wherein the webs (21) substantially form an n-star (24), in particular a hexagram or an octagram or a decagram, wherein the n-star (24) has a second inner n-gon (25), wherein the connecting means (10) is arranged in the second n-gon (25) and is connected to web sections (22, 26) of the webs (21) enclosing the second n-gon (25) and/or wherein the The connecting means (10) is formed at least partially by the web sections (22, 26) enclosing the second n-gon (25).