Ferrite Core Alignment Structures for Inductive Device Precision

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Solution Overview

Problem

Inductive components with ferrite cores face challenges in precise positioning and alignment due to manufacturing tolerances, leading to unacceptable electrical property deviations and assembly issues, particularly with length tolerances in ferrite core production.

Innovation Solution

An inductive component design featuring a ferrite core with a yoke body having perpendicular dimensions, including a positioning structure and an elongate alignment structure on its side surface, spaced apart along the length dimension, allowing for precise alignment and positioning through rotational degrees of freedom, with cylindrical or conical pins serving as positioning and alignment elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If ferrite cores are produced by pressing and sintering, then manufacturing is simplified, but length tolerances of ±2.5% occur due to thermal expansion during sintering

Engineering Contradiction:
Improvemanufacturing processVSAvoidlength tolerance
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent converts the harmful effect of thermal expansion during sintering into a beneficial feature by designing compensation elements that actively compensate for the expected dimensional changes. The compensation elements are pre-calculated to offset the ±2.5% length tolerances, transforming the manufacturing challenge into a predictable and correctable parameter.

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

Solution Approach 2:

The patent applies parameter changes by modifying the dimensions of compensation elements based on the known thermal expansion characteristics of ferrite materials. The compensation elements are designed with specific dimensional parameters that counteract the thermal expansion effects, allowing the final assembled dimensions to meet tight tolerance requirements despite the ±2.5% variation during sintering.

Inventive Principle:
Principle #35Parameter changes

2Volume of moving object

If inductive components are miniaturized, then compactness is improved, but positioning and alignment precision becomes more difficult to achieve

Engineering Contradiction:
Improvecomponent sizeVSAvoidpositioning and alignment precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent divides the positioning and alignment function into multiple independent elements: positioning elements for location, alignment elements for orientation, and compensation elements for tolerance adjustment. This segmentation allows each element to be optimized independently for its specific function, achieving high precision in miniaturized components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent addresses positioning and alignment precision by adding dimensional flexibility through compensation elements that can adjust in multiple directions. These elements provide degrees of freedom in assembly, allowing compensation for misalignments in any dimension, which is critical for maintaining precision in miniaturized inductive components.

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

3Manufacturing precision

If positioning and alignment structures are added to ferrite cores, then positioning precision is improved, but device complexity increases

Engineering Contradiction:
Improvepositioning and alignment precisionVSAvoidstructure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the positioning, alignment, and compensation functions into an integrated system of elements that work together on the ferrite core. The positioning elements, alignment elements, and compensation elements are designed as a coordinated set, reducing the need for separate adjustment mechanisms and simplifying the overall assembly process despite the multiple functions required.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The compensation elements are designed to automatically compensate for manufacturing tolerances without requiring active control or adjustment during assembly. The elastic elements self-adjust to accommodate the ±2.5% length variations in ferrite cores, providing positioning precision without adding complex control systems or manual adjustment 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 design enables precise alignment and positioning of the ferrite core independently of manufacturing tolerances, reducing assembly problems and maintaining minimal magnetic flux disruption, thus enhancing the performance and reliability of inductive components.

Implementation Method 1

The magnetic core of an inductive component is often made of a ferromagnetic material such as iron powder or ferrite and is used to guide the magnetic field while increasing the magnetic coupling between the windings

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 2

Due to thermally induced changes in length (the behavior of a substance/material with regard to changes in its dimensions with temperature changes is described by the thermal expansion coefficient, which represents a substance-specific material constant), tolerances of ± 2.5% are to be expected during sintering

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3252785B1Inductive device and method for producing an inductive device
Publication Date: 2020.12.23 SUMIDA COMPONENTS & MODULES GMBH
  • EP3252785B1 patent drawingFigure 1a~1c
  • EP3252785B1 patent drawingFigure 2~3c

AI summary

In a first aspect, the invention provides a ferrite core with a yoke body (110) having a length dimension, a width dimension, and a height dimension, each oriented perpendicular to the others, wherein the length dimension is larger than the height dimension and/or the width dimension. A positioning structure (112) and an elongated alignment structure (114), distinct from the positioning structure (112), are provided on a side surface (116) of the yoke body (110). These elongated alignment structures are spaced apart from each other along the length dimension by between 5% and 75% of the length dimension. A maximum dimension of the elongated alignment structure (114) is oriented transversely to a direction perpendicular to a connection direction between the positioning structure (112) and the alignment structure (114).