Step-Shaped Coil Core for Compact Inductive Sensor

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Solution Overview

Problem

Inductive sensor devices for vehicle pedals face challenges in achieving a balance between compact size and high sensitivity, as reducing the coil core length compromises measurement resolution and sensitivity, while requiring a high level of reliability for safety-critical applications like brake pedals.

Innovation Solution

The coil core's immersion piece features a section with a stepwise increase or decrease in cross-section, allowing for a shorter overall length while maintaining a large measurement path and sensitivity, enabling multiple coils in series with redundancy for reliability, and easy production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the coil core length is reduced to reduce installation space, then the space requirement decreases, but the measuring path and sensitivity are reduced

Engineering Contradiction:
Improveinstallation spaceVSAvoidmeasuring path and sensitivity
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The coil core is segmented into multiple sections with alternating cross-sectional areas along its longitudinal axis, creating a stepped profile that interacts differently with the magnetic field at various positions, thereby maintaining high sensitivity over a compact length

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the coil core have different cross-sectional areas, creating local variations in magnetic permeability and field interaction that enhance the overall measurement capability within a reduced total length

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If a smooth cylindrical coil core is used, then the manufacturing is simple, but the overall length exceeds the measuring path considerably

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcoil core length
Core Design Contradiction:
Ease of manufactureVSLength of stationary object

Solution Approach 1:

The coil core is divided into multiple sections with alternating cross-sectional areas, creating a stepped profile that can be manufactured using standard machining processes while achieving compact overall length

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of varying the length of a uniform cylinder, the invention varies the cross-sectional area along the length, creating a stepped profile that achieves compactness in one dimension while maintaining functional effectiveness

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

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 achieves a compact inductive sensor device with high resolution and sensitivity, ensuring reliable operation even in safety-critical applications by utilizing a stepwise cross-sectional change in the coil core, allowing for digital signal generation and redundancy in coil arrangement.

Implementation Method 1

the immersion of soft-iron cores in the coil creates a lower resistance to the magnetic flux, as a result of which the inductance of the coil increases measurably

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 2

inductive sensor device with at least two electrical coils (4, 6) wound on a coil body (2), by introducing an immersion piece (8) of a coil core (10) into a central coil body opening (12) of the coil body (2) and thus into the field lines of a magnetic field generated by them

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2028451B1Inductive sensor assembly with a step-shaped coil core
Publication Date: 2014.12.10 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP2028451B1 patent drawingFigure 1~2
  • EP2028451B1 patent drawing

AI summary

The invention relates to an inductive sensor device (1) with at least two electrical coils (4, 6) arranged in series one behind the other, wherein a coil core (10) is provided which is adjustable according to a distance or angle to be measured and which dips into the coils (4, 6) with an immersion piece (8).The invention provides that a) the immersion piece (8) of the coil core (10) has a section (16) with a cross-section that is stepwise enlarged or stepwise reduced compared to the two adjacent sections (18, 20), wherein b) in a basic position of the coil core (10) the section (16) with the stepwise enlarged or stepwise reduced cross-section overlaps with one coil (4) and one of the two adjacent sections (18, 20) overlaps with the other coil (6) and c) in a position of the coil core (10) that deviates from the basic position the section (16) with the stepwise enlarged or stepwise reduced cross-section overlaps with a part of the other coil (6) and the other of the two adjacent sections (18, 20) overlaps with a part of one coil (4).