Rolling Bearing Angular Position Sensing With Eddy Current Patterns

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing rolling bearings with built-in position-determining devices face challenges in accurately and reliably determining the absolute angle of rotation, especially in harsh environmental conditions due to external magnetic fields and aging-related demagnetization.

Innovation Solution

A rolling bearing with integrated position-determining device using field patterns with discrete field heights on one bearing ring and eddy current sensors on the other, allowing for accurate and reliable determination of the absolute angular position, even in harsh conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic sensors and magnetic characteristics are used for position determination in a rolling bearing, then absolute angle of rotation can be determined, but measurement accuracy deteriorates under external magnetic fields and aging-related demagnetization

Engineering Contradiction:

Improveposition determination accuracyVSAvoidmeasurement reliability under external magnetic fields

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the magnetic field-based measurement system with an eddy current-based measurement system. Eddy current sensors detect changes in electrical impedance caused by conductive fields on the bearing ring, eliminating susceptibility to external magnetic fields and demagnetization effects while maintaining absolute position determination capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical parameter used for measurement from magnetic field characteristics to electrical impedance characteristics. By using eddy current sensors that respond to electrical conductivity variations rather than magnetic field variations, the system achieves immunity to magnetic interference while preserving measurement accuracy.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If incremental encoders are used for position determination, then position can be monitored, but absolute angle of rotation cannot be determined

Engineering Contradiction:

Improveposition monitoring capabilityVSAvoidabsolute position information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent replaces incremental encoder technology with eddy current sensor technology that inherently provides absolute position information. The eddy current measurement system directly measures the absolute angular position through electrical impedance changes, eliminating the need for pulse counting and reference position requirements of incremental encoders.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If magnetic characteristics with steeper than sinusoidal profiles are used, then measurement range increases, but measurement data becomes distorted under external magnetic fields

Engineering Contradiction:

Improvemeasurement rangeVSAvoiddistortion under external magnetic fields

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes magnetic field interaction with electrical eddy current interaction. The eddy current sensors measure electrical impedance changes caused by conductive fields, completely avoiding distortion from external magnetic fields while maintaining the ability to scan steep field profiles for extended measurement ranges.

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

The solution provides a reliable and accurate method for determining the absolute angular position of rolling bearings, resistant to external interference and aging effects, enabling continuous position determination during high rotation speeds.

Implementation Method 1

at least one eddy current sensor which is arranged on a second of the bearing rings in order to scan the field patterns

Methodology Applied

Scientific EffectEddy current: Eddy Currents

Data Source

PatentUS12332272B2Rolling bearing having position-determining device

Publication Date: 2025.06.17 ROTHE ERDE GMBH

AI summary

A rolling bearing may have at least two bearing rings arranged rotatably relative to each other, at least one row of rolling elements arranged such that they can roll between the bearing rings, and a position-determining device for determining an absolute angular position of the bearing rings relative to each other. The position-determining device includes field patterns that are arranged on a surface of a first of the bearing rings and distributed around a circumference thereof, with fields of the field patterns having field heights with discrete values. The position-determining device also includes at least one eddy current sensor that is provided on a second of the bearing rings to scan the field patterns. An evaluation device may be configured to assign an associated angular position signal, which describes the absolute angular position of the first and second bearing rings relative to each other, to a scan of each field pattern.