Segmented Linear Motor Secondary Part with Overlapping Yoke Plates

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Solution Overview

Problem

Existing linear motors with segmented secondary parts face challenges in manufacturing complexity and stray field leakage due to high demands on manufacturing accuracy and alignment, particularly in producing long lengths where small inaccuracies lead to gaps and edges that allow uncontrolled escape of magnetic flux.

Innovation Solution

A segmented secondary part design with overlapping yoke plates of alternating polarity magnets, aligned via screws and pins rather than positive fit, featuring a tongue and groove structure to concentrate magnetic flux and minimize air gaps, reducing leakage flux through chamfered edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If secondary parts are segmented to enable manufacturing in arbitrary lengths, then manufacturing flexibility is improved, but manufacturing precision deteriorates due to alignment requirements at joints

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidalignment precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The secondary part is divided into multiple segments that can be manufactured separately and joined together. Each segment contains magnets with alternating polarities mounted on a yoke plate, allowing the secondary part to be produced in arbitrary lengths by assembling multiple standardized segments.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The segments are designed with overlapping areas where yoke plates of adjacent segments lie one above the other in the magnetization direction. This nested arrangement ensures that the magnetic flux is concentrated inside the segments and transmitted through a small air gap, while the overlapping structure provides inherent alignment guidance.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Manufacturing precision

If positive locking joints are used to ensure segment alignment, then alignment precision is improved, but device complexity increases

Engineering Contradiction:
Improvealignment precisionVSAvoidjoint structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The overlapping yoke plate structure provides self-alignment through magnetic flux concentration. The magnetic field naturally guides the alignment of adjacent segments, eliminating the need for complex mechanical positive locking joints while maintaining high alignment precision.

Inventive Principle:
Principle #25Self-service

3Object-generated harmful factors

If small air gaps are maintained at segment joints, then stray field leakage is reduced, but manufacturing tolerance requirements increase

Engineering Contradiction:
Improvestray field leakageVSAvoidgap control precision
Core Design Contradiction:
Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The overlapping yoke plate configuration creates a nested structure where segments are positioned one above the other in the magnetization direction. This geometry naturally concentrates magnetic flux within the overlapping region and transmits it through a controlled small air gap, reducing leakage flux while providing manufacturing tolerance.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The air gap distance varies locally across the segment joint: it is small in the overlapping area to concentrate flux and reduce leakage, while being larger in outer areas where leakage is already minimal. This local variation in gap size optimizes both magnetic field containment and manufacturing feasibility.

Inventive Principle:
Principle #3Local quality

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 reduces manufacturing complexity and accuracy demands, effectively shielding stray fields by concentrating magnetic flux and minimizing leakage, allowing for efficient production of linear motors of varying lengths with improved magnetic field containment.

Implementation Method 1

The special design of the overlapping area of the secondary part segments ensures that the magnetic flux is concentrated inside the segments and transmitted through a small air gap with low magnetic resistance

Methodology Applied
Scientific EffectMagnetic flux concentration: Magnetic Field

Implementation Method 2

transmitted through a small air gap with low magnetic resistance, while in outer areas of the segments the air gap is larger, the flux, and therefore the leakage flux, is smaller

Methodology Applied
Scientific EffectMagnetic resistance: Magnetic Reluctance

Implementation Method 3

Linear motors with an active, coil-equipped primary part and a passive, magnet-equipped secondary part are ubiquitous as drives for the precise positioning of machine elements

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP3627673B1Segmented secondary part for a linear motor
Publication Date: 2023.07.26 ETEL SA
  • EP3627673B1 patent drawingFigure 1~2
  • EP3627673B1 patent drawingFigure 3~4

AI summary

A segmented secondary part of a linear motor is disclosed, comprising at least two segments (S1, S2) each with a plurality of magnets (M) of alternating polarity mounted on a yoke plate (J), the magnetization direction (Y) of which is perpendicular to the yoke plate (J). The yoke plates (J) have an overlap region (B) in which the yoke plates (J) of adjacent segments (S1, S2) lie one above the other in the magnetization direction (Y), but do not touch each other in the overlap region (B).