Magnetic Bearing Load Determination Using Wavelength Optimization
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Solution Overview
Problem
Current load measurement technologies for rolling element bearings, such as strain gauges and magnetic sensors, face challenges in accuracy and cost, particularly in distinguishing between cornering loads and thermal effects, and are inefficient in compact wheel bearing units where deformations overlap.
Innovation Solution
A load determining system using multiple magnetic sensors and a signal processing unit to calculate axial forces and cornering loads by analyzing the natural logarithm of magnetic sensor outputs, combined with deformation sensors to account for thermal drift and improve resolution, allowing for precise load measurement and wear assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard magnetic sensors with large wavelength (7 mm or more) are used for load detection, then signal-to-noise ratio is sufficient and wheel speed detection is accurate, but load measurement resolution is low due to shallow slope of characteristic function
Solution Approach 1:
The patent changes the wavelength parameter of the magnetic target ring from the standard 7 mm or more to a shorter wavelength range. This parameter change steepens the slope of the characteristic function describing the dependency of signal amplitude on distance, thereby improving load measurement resolution while maintaining sufficient signal-to-noise ratio for practical applications
2Measurement precision
If strain gauges are attached to bearing surfaces for load measurement, then load can be measured, but manufacturing becomes time-consuming, costly and difficult to automate
Solution Approach 1:
The patent replaces the mechanical strain gauge attachment method with a magnetic sensing system. Instead of physically attaching strain gauges to bearing surfaces, the invention uses magnetic sensors interacting with a magnetic target ring to detect bearing displacement and infer load, eliminating the need for manual strain gauge application and associated manufacturing complexities
Solution Approach 2:
The magnetic target ring serves multiple functions: it enables both wheel speed detection (through frequency analysis) and load measurement (through amplitude analysis). This multi-functionality eliminates the need for separate strain gauge systems while providing comprehensive bearing monitoring capabilities
3Measurement precision
If Eddy Current Sensors are used for load measurement, then load can be measured, but the solution becomes fairly expensive
Solution Approach 1:
The patent employs relatively inexpensive magnetic sensors and a simple magnetic target ring instead of costly Eddy Current Sensors. This substitution significantly reduces the overall system cost while maintaining the capability to measure bearing load through magnetic field interactions and signal amplitude analysis
4Adaptability or versatility
If magnetic sensors are used for both wheel speed and load detection, then existing sensor systems can be utilized, but the wavelength is not optimized for accurate load sensing
Solution Approach 1:
The patent optimizes the wavelength parameter of the magnetic target ring specifically for load detection applications. By reducing the wavelength from the standard 7 mm or more to a shorter value, the system achieves steepened characteristic function slope that improves load measurement accuracy while preserving the ability to perform wheel speed detection through frequency analysis of the same sensor signals
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 system provides accurate load determination with improved resolution and cost-effectiveness, capable of distinguishing between different load scenarios and thermal effects, enhancing the precision of load measurement in compact wheel bearing units.
Implementation Method 1
The amplitude of the magnetic field acting between a magnetic sensor and an angle target ring depends on the axial distance between these elements
Data Source
AI summary
A load determining system having a sensorized rolling element bearing in a hub unit for wheels. The bearing includes a first ring and a second ring as an inner and outer ring. The first and second ring may be the inner ring, the other ring being the outer ring. The system includes at least two magnetic sensors attached to the first ring interact with a target wheel attached to the second ring. The system includes a signal processing unit configured to receive the magnetic sensor output of the at least one magnetic sensor, to determine at least axial forces acting on the bearing based on the amplitude of the magnetic sensor output and to calculate averages value of the outputs of the at least two magnetic sensors and to calculate a logarithm of a ratio of the average values to determine a load acting on the bearing.