Magnetic Rotation Sensor Using Giant Magnetoresistance

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Solution Overview

Problem

Existing methods for sensing the rotation of a shaft, such as using ferromagnetic toothed wheels, require complex algorithms, are sensitive to manufacturing accuracy and mounting precision, and occupy significant space, making them inefficient and costly.

Innovation Solution

A sensor device comprising a magnetic field sensitive element positioned in the magnetic field of a magnet on a shaft, which senses the orientation angle between 0° and 360°, using effects like Giant Magnetoresistance to generate pulse patterns emulating toothed wheel outputs, allowing for accurate and compact rotation sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a ferromagnetic toothed wheel is used to sense shaft rotation, then rotation detection is achieved, but the device occupies significant space and requires complex algorithms for accurate angle estimation

Engineering Contradiction:

Improverotation angle detection accuracyVSAvoidalgorithm complexity and manufacturing precision requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical toothed wheel system with a magnetic field-based sensing system. A magnet is mounted on the shaft and a magnetic field sensitive element detects its position, eliminating the need for complex mechanical toothed wheels and their associated alignment precision requirements. The magnetic field sensor detects changes in magnetic field strength as the magnet rotates, providing rotation information through electrical signals rather than mechanical tooth patterns.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a simplified magnetic field-based copy of the toothed wheel functionality. Instead of using actual mechanical teeth, the system uses magnetic field variations that replicate the toothed wheel's rotation detection capability. The magnetic sensor output mimics the pulse pattern that would be generated by a toothed wheel, providing the same functional information with reduced complexity.

Inventive Principle:

Principle #26Copying

2Reliability

If a ferromagnetic toothed wheel is used for rotation sensing, then rotation information is obtained, but the device size and cost increase significantly

Engineering Contradiction:

Improverotation sensing capabilityVSAvoidsensor device volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent replaces the bulky mechanical toothed wheel with a compact magnetic field sensing system. The magnet mounted on the shaft occupies minimal space, and the magnetic field sensitive element requires only a small sensing volume. This substitution dramatically reduces the overall device volume while maintaining reliable rotation sensing capability through magnetic field detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the sensor is placed radially offset from the ferromagnetic toothed wheel, then rotation detection is enabled, but mounting precision requirements increase

Engineering Contradiction:

Improverotation angle measurementVSAvoidsensor mounting precision

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent eliminates the radial offset mounting requirement by replacing the mechanical toothed wheel with a magnetic field system. The magnetic field sensitive element can be positioned more flexibly relative to the magnet on the shaft, as magnetic fields penetrate through non-magnetic materials and do not require precise radial alignment. This substitution significantly reduces manufacturing and assembly precision requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables efficient, accurate, and cost-effective sensing of shaft rotation with reduced complexity and space requirements, emulating conventional toothed wheel outputs while improving accuracy and reducing system complexity and costs.

Implementation Method 1

using effects like Giant Magnetoresistance to generate pulse patterns emulating toothed wheel outputs

Methodology Applied

Scientific EffectGiant Magnetoresistance: Magnetoresistance

Data Source

PatentUS11359936B2Rotation sensor

Publication Date: 2022.06.14 INFINEON TECHNOLOGIES AG

AI summary

A system is provided with a magnetic field sensor being positioned in a magnetic field of a magnet that is coupled to a rotatable driving shaft. The magnetic field sensor is configured to sense a rotation of the magnetic field in response to a rotation of the rotatable driving shaft, and generate an angle sensor signal based on an orientation angle of the magnetic field. The angle sensor signal includes angular values that represent an absolute orientation angle of the rotatable driving shaft. The system includes a memory storing a mapping of values of a patterned signal to the angular values, electronic circuitry configured to generate, based on the angular values and the stored mapping, the patterned signal, and a signal generator circuit configured to generate a signal representing the absolute orientation angle of the rotatable driving shaft based on the angle sensor signal.