Bidirectional Magnetic Position Sensor With Variable Magnetization
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Solution Overview
Problem
Existing bidirectional contactless magnetic position sensors face limitations such as limited stroke, measurement of rotations only, high cost due to strong remanence and thickness of magnets, significant size, and sensitivity to geometric tolerances and temperature, making them unsuitable for applications requiring independent position information in two directions.
Innovation Solution
A magnetic position sensor measuring relative displacement between a magnetized element and a magneto-sensitive probe using at least two components of the magnetic field at a single point, with a magnetization vector that varies along one or both dimensions, allowing for independent position signals in two directions without ferromagnetic parts, thus avoiding hysteresis and geometric sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If permanent magnets with ferromagnetic material are used to guide and concentrate magnetic flux, then bidirectional position sensing is achieved, but cost and sensor performance deteriorate
Solution Approach 1:
The patent removes ferromagnetic materials from the sensor structure, extracting the source of hysteresis and cost complexity. The solution uses only non-ferromagnetic materials (paramagnetic or diamagnetic) while maintaining bidirectional sensing capability through a different magnetic field generation approach using permanent magnets without ferromagnetic circuits.
Solution Approach 2:
The patent changes the magnetic material parameters by eliminating ferromagnetic materials with high permeability and replacing them with non-ferromagnetic materials. This parameter change removes hysteresis effects while maintaining the necessary magnetic field characteristics for bidirectional sensing through alternative magnet arrangements.
2Adaptability or versatility
If permanent magnets with ferromagnetic material are used to guide and concentrate magnetic flux, then bidirectional position sensing is achieved, but sensor performance deteriorates
Solution Approach 1:
The patent removes ferromagnetic materials that cause hysteresis, extracting the source of measurement errors. By using only non-ferromagnetic materials, the sensor eliminates hysteresis effects that degrade performance and require complex compensation algorithms.
Solution Approach 2:
The patent converts the limitation of non-ferromagnetic materials (lower magnetic flux concentration) into a benefit by eliminating hysteresis. The design accepts reduced flux concentration but gains measurement accuracy and stability, as the magnetic field characteristics become predictable and repeatable without ferromagnetic hysteresis.
3Measurement precision
If amplitude measurement is used to detect position, then position information is obtained, but sensitivity to geometric tolerances and temperature increases
Solution Approach 1:
The patent changes the measurement parameter from magnetic field amplitude to magnetic field direction (angle). This parameter change makes the measurement insensitive to temperature variations and geometric tolerances, as directional measurement depends on field orientation rather than field strength, which is affected by environmental factors.
4Device complexity
If a single unidirectional sensor is used, then simple structure is maintained, but bidirectional position information cannot be provided
Solution Approach 1:
The patent makes a single sensor probe multi-functional by enabling it to detect magnetic field components in multiple directions simultaneously. The probe measures both X and Y direction fields using the same sensing elements, providing bidirectional position information without requiring separate sensor assemblies.
Solution Approach 2:
The patent adds dimensional capability by enabling the single sensor to detect fields in multiple spatial dimensions (X and Y directions). This is achieved through measuring magnetic field components along different axes using the same probe, effectively transitioning from one-dimensional to two-dimensional sensing capability.
5Adaptability or versatility
If multiple independent unidirectional sensors are placed end-to-end, then bidirectional position sensing is achieved, but device bulk and production cost increase
Solution Approach 1:
The patent merges multiple sensing functions into a single integrated probe. The unified sensor measures magnetic field components in both X and Y directions simultaneously at the same location, eliminating the need for separate sensor assemblies and reducing overall device volume while maintaining bidirectional sensing capability.
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 independent, precise position information in two directions with minimal bulk and cost, overcoming variations in magnetic properties and geometric tolerances, and is robust against temperature and air gap variations.
Implementation Method 1
measuring at least two components of the magnetic field generated by said magnetized element (1)
Data Source
Figure 1~2b
Figure 2c~3
Figure 4~6
AI summary
The invention relates to a magnetic position sensor in at least two directions, said sensor comprising at least one magnetized element (1) and a probe (6) comprising at least two magneto-sensitive elements located substantially on the same point and each measuring one of the components of the magnetic field generated by said magnetized element (1), the magnetized element (1) being movable relative to said magneto-sensitive elements. Said probe (6) moreover comprises at least one processing circuit capable of carrying out angle and module calculations on the basis of algebraic combinations of the components of the magnetic field and providing at least two independent signals representing the position of the movable element along, respectively, one and the other of the two directions. According to the invention, the magnetization vector of the magnetized element (1) is variable in relation to the normal vector on the surface of the magnetized element that is placed opposite the probe (6) in at least one of the dimensions of said magnetized element so as to define a single position of said probe (6) in relation to said magnetized element (1).