Magnetic Position Sensor Flux Collector Harmonization
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Solution Overview
Problem
Existing analog magnetic sensors face limitations in measuring rotary and linear displacement due to sensitivity issues with large diameter magnets, precision problems, and incompatibility with certain magneto-sensitive elements, especially when dealing with varying magnetic field ratios and external disturbances.
Innovation Solution
The solution involves measuring two components of magnetic induction at the same point using flux collectors to harmonize their amplitudes, allowing for a ratio close to 1, which enables the use of a broader range of magneto-sensitive elements and reduces sensitivity to external disturbances, while also incorporating flux collectors that can be molded into the sensor housing or fixed to a printed circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diametrically magnetized ring magnet is used with large diameter, then the radial component of magnetic induction increases, but the tangential component decreases making the ratio incompatible with conventional magneto-sensitive elements
Solution Approach 1:
Ferromagnetic concentration elements are introduced as intermediaries between the diametrically magnetized ring magnet and the magneto-sensitive elements. These concentrators modify the magnetic field distribution, specifically enhancing the tangential component at the measurement point to achieve a suitable ratio for compatibility with conventional magneto-sensitive elements while maintaining accurate angular position measurement capability
2Measurement precision
If the ratio between radial and tangential components is large (1.5 to 4), then the sensor can measure position, but the sensor becomes sensitive to magnetic disturbances
Solution Approach 1:
The ferromagnetic concentration elements change the magnetic field parameters by selectively concentrating flux lines, modifying the ratio between radial and tangential components at the measurement point. This parameter adjustment reduces the sensor's sensitivity to external magnetic disturbances while preserving its ability to accurately measure angular position through the modified field distribution
3Measurement precision
If ferromagnetic parts are used to equalize magnetic field components, then the amplitudes of components are equalized, but the volume of ferromagnetic parts is very large making construction difficult
Solution Approach 1:
Instead of using large-volume ferromagnetic parts distributed throughout the sensor, the invention employs localized ferromagnetic concentration elements positioned specifically at strategic locations around the ring magnet. These localized concentrators achieve the desired equalization of magnetic field component amplitudes at the measurement point while minimizing overall device volume and construction complexity
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 enhances the accuracy and reliability of position detection, reduces manufacturing costs, and improves compatibility with various magneto-sensitive elements, enabling effective measurement of angular and linear positions over extended ranges with reduced error and sensitivity to magnetic disturbances.
Implementation Method 1
The solution involves measuring two components of magnetic induction at the same point using flux collectors to harmonize their amplitudes
Implementation Method 2
at least two magneto-sensitive elements which measure the direction of the magnetic field
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
The present invention relates to a magnetic position sensor with field direction measurement and flux collector. The invention proposes to measure two magnetic induction components at one and the same point, harmonizing the amplitude of the two magnetic induction components using flux collectors so as to have a ratio of the amplitudes of these two components close to one. For this purpose, the invention provides a contactless position sensor comprising at least one permanent magnet (1), emitting a magnetic field, at least one detection element (3) sensitive to the direction of the magnetic field, and at least one pair of flux collectors (2a, 2b), the permanent magnet (1) being capable of moving in a direction of displacement and having a direction of magnetization that can be continuously varied according to the direction of displacement. Each flux collector (2a, 2b) has at least one portion, provided with an end (8, 9), extending substantially along the direction of displacement of the magnet (1). The ends (8, 9) of a pair of flux collectors (2a, 2b) define a gap (7) oriented along the direction of displacement of the magnet (1). The detection element (3) is positioned outside said gap (7) and substantially equidistant from the ends (8) and (9).