Electric Motor Pole Tube Rolling and Magnet Insertion

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Solution Overview

Problem

Existing electric motor manufacturing methods result in internal burrs during the deep-drawing process, requiring larger inner diameters and increasing material costs, complexity, and design limitations, particularly when mounting ring-shaped magnets.

Innovation Solution

A method involving rolling a stamped pole tube with a thin-walled ring magnet, where the magnet's outer circumference contacts the inner circumference, allowing for a uniform inner diameter and flexible design, with the burr occurring on the outside, enabling cost-effective production using less material and simpler tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If deep-drawing process is used to manufacture housing, then housing structure is formed, but internal burrs are generated requiring larger inner diameter and increasing material costs

Engineering Contradiction:
Improvehousing formationVSAvoidmaterial usage
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

The patent inverts the conventional deep-drawing approach by using a rolling process that forms the pole tube from a flat lateral surface. This inversion of the manufacturing method eliminates the internal burr generation problem inherent in deep-drawing, allowing the magnet to be mounted without requiring additional clearance diameter.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the manufacturing parameters by transitioning from deep-drawing to rolling formation. This parameter change in the manufacturing process fundamentally alters the surface quality characteristics, eliminating internal burrs and enabling precise control of the inner diameter without material waste.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If larger inner diameter is used to accommodate burrs, then magnet mounting is enabled, but material usage and device complexity increase

Engineering Contradiction:
Improvemagnet mountingVSAvoidhousing structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent converts the potential harm of burr generation into a benefit by using a rolling process that naturally produces burrs on the outer surface only. This transforms the manufacturing challenge into an advantage, where the same rolling process that forms the structure also ensures clean inner surfaces for precise magnet mounting.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Volume of moving object

If thin-walled ring magnet is used for compact design, then motor compactness is improved, but magnet damage risk increases due to internal burrs

Engineering Contradiction:
Improvemotor sizeVSAvoidmagnet integrity
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by ensuring the inner surface of the pole tube is free of burrs through the rolling manufacturing process before the magnet is mounted. This preliminary preparation of the mounting surface prevents damage to the thin-walled magnet during installation and operation.

Inventive Principle:
Principle #10Preliminary action

4Ease of manufacture

If deep-drawn housing with multiple diameters is used, then magnet mounting is possible, but production costs and manufacturing steps increase

Engineering Contradiction:
Improvemagnet insertionVSAvoidproduction efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies universality by designing the rolling process to simultaneously achieve multiple functions: forming the pole tube structure, controlling the inner diameter precision, and ensuring burr-free inner surfaces. This multi-functional approach eliminates the need for separate diameter variations and additional manufacturing steps.

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

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 approach reduces material usage, production steps, and costs, while enhancing design flexibility and preventing magnet damage or abrasion, allowing for lighter and more versatile electric motor construction.

Implementation Method 1

shaping the pole tube by rolling the lateral surface

Methodology Applied
Scientific EffectRolling:

Implementation Method 2

an outer circumference of the ring magnet rests against an inner circumference of the pole tube

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2449659B1Method for manufacturing an electric motor
Publication Date: 2014.01.22 ROBERT BOSCH GMBH
  • EP2449659B1 patent drawingFigure 1
  • EP2449659B1 patent drawingFigure 2

AI summary

The present invention relates to a method for manufacturing an electric motor, comprising the following steps: providing an outer surface of a pole tube (8) of the electric motor, forming the pole tube (8) by rolling the outer surface in, and inserting a thin-walled ring magnet (19) into the pole tube (8), so that an outer circumference of the ring magnet (19) rests on an inner circumference of the pole tube (8).