Rolling Bearing Angular Position Sensing With Eddy Current Patterns
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Solution Overview
Problem
Existing position determining devices for rolling bearings, such as incremental encoders and absolute value encoders, face challenges in achieving accurate and reliable angular position measurement, especially in harsh environmental conditions and under the influence of external magnetic fields or aging, which leads to distorted and unreliable position values.
Innovation Solution
A rolling bearing with integrated position determining device featuring field patterns with discrete-value field heights on one bearing ring and an eddy current sensor on the other ring, allowing for precise absolute angular position determination, immune to external interference and aging, and capable of continuous measurement during high twisting speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic characteristics are used for position determination in rolling bearings, then measurement accuracy can be improved, but the system becomes sensitive to external magnetic fields and aging demagnetization
Solution Approach 1:
The patent replaces magnetic field-based measurement with eddy current sensing. The encoder disk uses conductive material patterns that interact with eddy current sensors through electromagnetic induction, eliminating sensitivity to external magnetic fields while maintaining measurement precision. The eddy current sensors detect changes in electrical conductivity patterns on the encoder disk surface, providing reliable position data without magnetic interference.
Solution Approach 2:
The patent changes the measurement parameter from magnetic field characteristics to electrical conductivity patterns. The encoder disk features conductive patterns with varying conductivity values that are detected by eddy current sensors, transforming the measurement approach from magnetic to electrical properties, thereby avoiding magnetic field sensitivity while preserving measurement accuracy.
2Measurement precision
If optical scanning encoders are used for position determination, then measurement resolution can be achieved, but the system becomes vulnerable to grease and oil lubrication environments
Solution Approach 1:
The patent replaces optical scanning with eddy current sensing technology. The eddy current sensors detect electrical conductivity patterns on the encoder disk through electromagnetic induction without requiring optical paths. This eliminates sensitivity to grease and oil lubrication environments while maintaining measurement resolution, as the electrical field penetration is not blocked by lubricants.
3Measurement precision
If field patterns with discrete field heights are used, then measurement signals become clearer for angular position assignment, but manufacturing complexity increases
Solution Approach 1:
The patent implements field patterns with discrete field heights (different depths) on the encoder disk surface. These depth variations create distinct eddy current responses that provide clear measurement signals for angular position determination. The patterns can be manufactured using conventional techniques such as machining, milling, or additive manufacturing, balancing signal clarity with manufacturing feasibility.
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 reliable and precise determination of the absolute angle of rotation, resistant to external interference and aging, enabling continuous and accurate angular position monitoring even in harsh conditions and high-speed operations.
Implementation Method 1
at least one eddy current sensor arranged on a second of the bearing rings for scanning the field patterns
Implementation Method 2
The position-determining device comprises field patterns distributed over the circumference of a first of the bearing rings on its surface
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a rolling bearing (1) having at least two bearing rings (2, 3) arranged rotatably relative to each other, at least one row of rolling elements (4) arranged such that they can roll between the bearing rings (2, 3), and a position-determining device (5) for determining an absolute angular position of the bearing rings (2, 3) relative to each other. The position-determining device (5) comprises field patterns (6) which are arranged on a surface (19) of a first (2) of the bearing rings (2, 3) and distributed around the circumference thereof, the fields (10, 11) of which have field heights of discrete values. The position-determining device (5) also comprises at least one eddy current sensor (7, 8) which is provided on a second (3) of the bearing rings (2, 3) in order to scan the field patterns (6), and an evaluation device (9) configured to assign an associated angular position signal, which describes the absolute angular position of the first and second bearing rings (2, 3) relative to each other, to the scanning of each of the field patterns (6).