Torque Sensor Stator Teeth Layout for Magnetic Interference Shielding
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Solution Overview
Problem
Torque sensors in electronic power steering systems are affected by external magnetic fields, leading to inaccurate measurements of torsion degree due to magnetic interference, which is a common issue in vehicles equipped with various electric devices.
Innovation Solution
A sensing device design where a pair of collectors are disposed between stator teeth, with overlapping first and second stator teeth and a magnet rotating between them, preventing external magnetic interference and enhancing flux collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a collector is disposed outside the stator tooth in a magnetic type torque sensor, then the torque sensor structure is simplified, but external magnetic fields interfere with the magnetic flux value of the Hall IC, causing inaccurate torque measurement
Solution Approach 1:
The stator tooth is divided into multiple segments (first stator tooth and second stator tooth) that are disposed at different radial positions. This segmentation allows the magnetic circuit to be divided into multiple paths, enabling the Hall IC to detect magnetic flux that is less susceptible to external magnetic field interference while maintaining structural simplicity.
Solution Approach 2:
The invention transitions from a single-plane collector arrangement to a multi-radial-position arrangement where collectors and stator teeth are distributed across different radial distances from the center. This dimensional change in spatial arrangement allows the magnetic circuit to utilize flux paths that are more resistant to external magnetic field interference.
2Device complexity
If a single stator tooth structure is used, then the device complexity is reduced, but the magnetic flux magnitude is insufficient for accurate sensing
Solution Approach 1:
Multiple stator teeth (first stator tooth and second stator tooth) are combined in the magnetic circuit, with their respective collectors working together to generate and guide magnetic flux. This merging of multiple magnetic flux paths increases the overall flux magnitude available for detection by the Hall IC, improving measurement reliability.
Solution Approach 2:
The second stator tooth is positioned inside the first stator tooth, creating a nested configuration where inner and outer magnetic flux paths cooperate. This nested arrangement allows the magnetic circuit to utilize both inner and outer flux paths simultaneously, increasing total flux magnitude while maintaining a compact structure.
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 minimizes magnetic interference, increases flux magnitude, facilitates easy coupling of stator teeth to the stator body, and prevents stator separation from the housing, ensuring accurate torque measurement and secure coaxial rotation.
Implementation Method 1
a rotor including a magnet... the first tooth overlaps the second tooth in a radial direction... a pair of collectors are disposed between stator teeth
Implementation Method 2
the collector serves as a passage of the magnetic field in the structure... affects a magnetic flux value of a Hall integrated circuit (IC)
Data Source
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AI summary
An embodiment may provide a sensing device including a stator including a stator tooth and a rotor including a magnet, wherein the stator tooth includes a first stator tooth and a second stator tooth disposed inside the first stator tooth, the first stator tooth includes a plurality of first teeth, the second stator tooth includes a plurality of second teeth, the first tooth overlaps the second tooth in a radial direction from a center of the stator, the stator includes a stator holder and a stator body which is coupled to the stator holder and on which the first stator tooth and the second stator tooth are disposed, the stator body includes a protrusion, and the protrusion is in contact with a lower end of the first stator tooth or a lower end of the second stator tooth.