Rotating Asymmetric Magnet for Magnetic Field Sensor Calibration
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Solution Overview
Problem
Conventional magnetic field sensors packaged in harsh environments, such as automobiles, suffer from reduced magnetic field strength due to air gaps, making them unsuitable for precise measurements.
Innovation Solution
A measurement system featuring a magnet with rotational asymmetry, allowing adjustment of flux density by rotating the magnet, which compensates for mechanical and technological tolerances, and positions magnetic field sensors to optimize magnetic field component measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packaged measuring elements are enclosed in an additional housing (overmold) for protection from moisture and dirt, then protection from harsh environments is improved, but the peak magnetic field strength decreases
Solution Approach 1:
The measuring element is separated into two functional parts: the sensor chip enclosed in a protective package, and the magnetic field-generating elements (permanent magnets) exposed outside. This segmentation allows the sensor to be protected while maintaining strong magnetic field interaction with the teeth of the measurement object.
Solution Approach 2:
The package structure acts as an intermediary that protects the sensitive measuring element from environmental factors while allowing magnetic field interaction. The package contains the sensor chip but positions it to receive magnetic field signals from external magnets without requiring the entire assembly to be overmolded.
2Strength
If the measuring element is positioned close to the magnet to maximize magnetic field strength, then peak magnetic field strength is improved, but mechanical tolerances and scattering of switching points increase
Solution Approach 1:
The system uses multiple permanent magnets arranged in a specific pattern that creates a dynamic magnetic field distribution. This allows the magnetic field to maintain sufficient strength even with variations in positioning, reducing the impact of mechanical tolerances on switching point scattering.
Solution Approach 2:
The invention changes the magnetic field generation approach by using multiple permanent magnets with specific magnetization directions rather than a single magnet. This parameter change in the magnetic field structure provides more stable field characteristics that are less sensitive to positioning variations.
3Reliability
If conventional packaged magnetic field sensors are used in harsh environments, then protection from environmental factors is improved, but measurement precision deteriorates due to reduced magnetic field strength
Solution Approach 1:
The system segments the sensor and magnet functions spatially, with the sensitive measuring element protected inside the package and the magnetic field-generating magnets positioned outside. This allows the sensor to operate in a protected environment while maintaining high measurement precision through strong external magnetic field interaction.
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 solution enhances the accuracy and adaptability of magnetic field measurements by adjusting the switching point and compensating for manufacturing tolerances, enabling effective use in various applications, including non-programmable sensors.
Implementation Method 1
a magnet whose magnetic flux penetrates the sensor
Implementation Method 2
Hall effect sensors are arranged relative to the field of the permanent magnet in such a manner that a Hall voltage is generated
Data Source
AI summary
A measurement system having a first magnetic field sensor and having a magnet for generating a magnetic field, in which the magnet has a first pole face and a second pole face, wherein an axis of rotation is defined perpendicular to the first pole face and perpendicular to the second pole face, wherein the magnet is supported for rotation about the axis of rotation, in which the first magnetic field sensor is positioned facing the first pole face and at a distance from the axis of rotation, in which the magnet has a rotational asymmetry of the flux density in the region of the first pole face, wherein the flux density of the magnet in the first magnetic field sensor can be adjusted between a maximum and a minimum by rotation of the magnet about the axis of rotation.