Magnetizing Magnetizable Objects for Sensor Accuracy
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Solution Overview
Problem
Magnetic sensors face sensitivity issues due to non-well-defined magnetic properties at the border regions between magnetized and non-magnetized portions of shafts, leading to signal inhomogeneities and parasitic effects, which affect the accuracy of torque and position measurements.
Innovation Solution
A method involving a sequence of electrical signals is applied to magnetizable objects to achieve precise magnetization, including a first degaussing signal to remove existing magnetization, a magnetizing signal to induce desired magnetization, and a second degaussing signal to refine the magnetization, using degaussing elements like coils to adjust the magnetization profile and eliminate parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shaft is magnetized in longitudinal direction to create a magnetized region, then the magnetic encoded region generates a characteristic signal for torque and position measurement, but the border area between magnetized and non-magnetized portions develops intermediate magnetization values that deteriorate sensor sensitivity
Solution Approach 1:
The patent applies a preliminary degaussing treatment to the border regions before final magnetization to prevent intermediate magnetization values from forming. By pre-treating the border areas to ensure they remain non-magnetized, the subsequent magnetization process creates a sharp transition between magnetized and non-magnetized regions, eliminating the intermediate states that would otherwise degrade sensor signal quality
Solution Approach 2:
The patent applies different magnetization treatments to different regions of the shaft. The central region receives full longitudinal magnetization to generate the encoding signal, while the border regions are specifically treated to maintain non-magnetized or reduced magnetization states. This local differentiation ensures that only the intended regions contribute to the magnetic signal, eliminating parasitic effects from border areas
2Measurement precision
If a shaft is magnetized to enable magnetic sensing, then torque and position can be measured non-contacting, but disturbing effects and inhomogeneities occur that cause signal variation along the circumferential trajectory
Solution Approach 1:
The patent extracts or removes the harmful magnetic inhomogeneities from the shaft by applying targeted degaussing treatments to specific regions. By selectively demagnetizing the border areas and surface regions that generate parasitic fields, the patent eliminates the source of signal variations and artefacts, leaving only the desired magnetization pattern in the central encoding region
Solution Approach 2:
The patent employs periodic alternating current signals with decreasing amplitude to progressively eliminate residual magnetization in border and surface regions. This periodic degaussing action, repeated with diminishing intensity, effectively removes magnetic inhomogeneities without affecting the main magnetized region, thereby eliminating circumferential signal variations
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 approach ensures a well-defined, step-like magnetization profile, enhancing the sensitivity and accuracy of magnetic sensors by eliminating border region ambiguities and surface magnetization contributions, thereby improving the reliability of torque and position measurements.
Implementation Method 1
applying a first degaussing signal to the magnetizable object to degauss the magnetizable object, wherein the first degaussing signal is an alternating electrical signal
Implementation Method 2
applying a first degaussing signal to the magnetizable object to degauss the magnetizable object
Implementation Method 3
applying a magnetizing signal to the degaussed magnetizable object to magnetize the magnetizable object
Implementation Method 4
applying a magnetizing signal to the degaussed magnetizable object to magnetize the magnetizable object
Implementation Method 5
applying a second degaussing signal to the magnetized magnetizable object to partially degauss the magnetized magnetizable object, wherein the second degaussing signal is an alternating electrical signal having a second frequency and a second amplitude
Implementation Method 6
applying a second degaussing signal to the magnetized magnetizable object to partially degauss the magnetized magnetizable object
Data Source
AI summary
Described is a method and array for magnetizing a magnetizable object. The method includes the steps of (a) applying a first degaussing signal to the magnetizable object to degauss the magnetizable object and the first degaussing signal is an alternating electrical signal having a first frequency and a first amplitude; (b) applying a magnetizing signal to the degaussed magnetizable object to magnetize the magnetizable object; and (c) applying a second degaussing signal to the magnetized magnetizable object to partially degauss the magnetized magnetizable object and the second degaussing signal is an alternating electrical signal having a second frequency and a second amplitude.