Variable Magnet Profile Sensor Eliminates Hysteresis
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Solution Overview
Problem
Magnetic position sensors face challenges due to magnetic hysteresis, temperature effects, and the need for expensive materials to reduce hysteresis, which complicates sensor design and performance.
Innovation Solution
A magnetic sensor design featuring a permanent magnet with a non-constant quasi-sinusoidal dimension variation and unidirectional magnetization, allowing for the measurement of two magnetic field components at the same point, which enables the calculation of linear or angular position using amplitude ratios and arctangent calculations, thereby overcoming temperature and time-related variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ferromagnetic materials are used to guide and concentrate magnetic flux, then magnetic field strength is improved, but magnetic hysteresis phenomenon increases and sensor cost increases
Solution Approach 1:
The patent removes ferromagnetic materials from the sensor design, extracting the source of hysteresis problems. The solution uses permanent magnets with specifically shaped profiles that generate the required magnetic field patterns without relying on ferromagnetic guiding structures, thereby eliminating magnetic hysteresis while maintaining measurement capability
Solution Approach 2:
The patent changes the geometric parameters of the permanent magnet by introducing non-constant profiles (sinusoidal or polynomial variations in thickness or width). This parameter modification allows the magnet to generate the necessary magnetic field distributions without ferromagnetic materials, resolving the hysteresis issue while maintaining field strength
2Strength
If ferromagnetic materials are used to guide and concentrate magnetic flux, then magnetic field concentration is improved, but sensor cost increases
Solution Approach 1:
The patent extracts and eliminates ferromagnetic materials from the sensor construction, removing the need for expensive specialized materials while maintaining magnetic field concentration through optimized permanent magnet geometries with non-constant profiles
Solution Approach 2:
The patent replaces expensive ferromagnetic materials with cost-effective permanent magnets having non-constant profiles. The solution uses standard permanent magnet materials combined with geometric optimization, significantly reducing material costs while achieving the required magnetic field performance
3Measurement precision
If electronic compensation is used to correct temperature effects, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces electronic compensation mechanisms with a geometric solution. By designing permanent magnets with non-constant profiles (sinusoidal or polynomial variations), the magnetic field inherently compensates for temperature effects and positional variations, eliminating the need for complex electronic correction circuits
Solution Approach 2:
The patent implements self-compensation through the magnet's geometric design. The non-constant profile of the permanent magnet automatically adjusts the magnetic field distribution to account for temperature variations and positional changes, making the sensor self-regulating without external electronic intervention
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 design enhances sensor accuracy and cost-effectiveness by minimizing the reliance on remanent induction and allowing for the use of standard probes, while also providing mechanical strength through ferromagnetic yokes and adaptable magnet shapes.
Implementation Method 1
a permanent magnet having at least one dimension varying according to a non-constant function, preferably continuous and in a quasi-sinusoidal manner
Implementation Method 2
these ferromagnetic materials induce a magnetic hysteresis phenomenon in the sensor
Implementation Method 3
at least two magneto-sensitive elements measuring two different components at the same point
Data Source
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Figure 3~4
Figure 5~6
AI summary
The invention relates to a magnetic angular or linear sensor including at least one permanent magnet (1) defined in a cylindrical (r, Q & z) or Cartesian (x, y & z) coordinate system and at least two magneto-sensitive elements (2 and 3), in which the magnet (1) can move in relation to said two magneto-sensitive elements (2 and 3). The invention is characterised in that at least one dimension of the magnet (1) varies as a non-constant function and in that the magnetisation of the magnets (1) is oriented in a single direction, i.e. x, y or z in the case of a magnet defined in a Cartesian coordinate system or r, Q or z in the case of a magnet defined in a cylindrical coordinate system.