Plastic Spiral Magnet Sensor for Long Path Detection

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Solution Overview

Problem

Existing sensor devices with a single diagonally magnetized magnet are limited to detecting medium-length paths and face challenges in reproducible and cost-effective production of elongated magnets, particularly for series production.

Innovation Solution

A rotatably mounted and diametrically magnetized magnet system is used, where a plastic spiral induces rotary motion, converting linear movement of a measurement object into a detectable rotating movement, allowing for longer path detection and easier production through plastic injection molding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single elongated magnet is used to detect medium-length paths, then the measurement capability is improved, but the manufacturing difficulty and cost increase significantly

Engineering Contradiction:
Improvepath detection capabilityVSAvoidmagnet production
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces a single elongated magnet with multiple shorter magnets arranged in a specific configuration. Each magnet is of manageable length that can be easily manufactured using standard plastic-bonded magnet processes, while collectively they provide the necessary measurement capability for medium-length paths through their combined magnetic field interaction with the sensor element.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a one-dimensional elongated magnet arrangement to a multi-dimensional configuration where multiple magnets are positioned at different locations and orientations. This spatial arrangement allows the system to detect path movements through the combined effect of multiple magnetic fields, achieving the same measurement capability without requiring a single long magnet.

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

2Measurement precision

If a single elongated magnet is used to detect medium-length paths, then the measurement capability is improved, but the device complexity increases

Engineering Contradiction:
Improvepath detection capabilityVSAvoidmagnet arrangement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the magnetic field generation function across multiple shorter magnets rather than using one long magnet. This segmentation simplifies the overall device architecture by using standard-sized components that can be easily positioned and secured, reducing the complexity of magnet support structures and alignment mechanisms required for a single elongated magnet.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If plastic-bonded magnets or anisotropic magnetic material magnets are used, then the manufacturing flexibility is improved, but the production cost and difficulty increase for series production

Engineering Contradiction:
Improvemagnet material selectionVSAvoidseries production efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent uses multiple shorter magnets that can be manufactured using standard plastic-bonded magnet processes, which are well-suited for high-volume series production. Each magnet can be produced independently using automated molding and magnetization processes, significantly increasing production efficiency compared to manufacturing a single custom elongated magnet.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the dimensional parameters of the magnets from a single long configuration to multiple shorter configurations, making them compatible with standard manufacturing processes. This parameter change allows the use of conventional plastic-bonded magnet technology with automated production lines, improving both cost-effectiveness and productivity in series production.

Inventive Principle:
Principle #35Parameter changes

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

Enables the detection of arbitrarily long paths with improved production efficiency and cost-effectiveness by converting linear movement into rotary motion, which is evaluated by a sensor, and allows for precise distance measurement.

Implementation Method 1

a plastic spiral (6), which performs a linear motion and penetrates the magnet (2), so that the magnet (2) is set into a rotary motion

Methodology Applied
Scientific EffectMechanical conversion from linear to rotary motion:

Implementation Method 2

a sensor (3) for detecting the rotary movement of the magnet (2)

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP2596323B1Path measurement using a plastic spiral and a diametric magnet
Publication Date: 2014.11.19 HIRSCHMANN AUTOMOTIVE GMBH
  • EP2596323B1 patent drawingFigure 1~2

AI summary

The invention relates to a sensor device (1) that is designed to detect a linear movement of an object to be measured and that is provided with a sensor (3) and a magnet system co-operating therewith. The device is characterised in that the magnet system is designed as a rotatably mounted, diametrically magnetised magnet (2) and the rotational movement is generated by a plastic spiral (6) that penetrates the magnet (2).