Torque Sensor Collector Layout for Magnetic Interference Shielding
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Solution Overview
Problem
Existing torque sensors in electronic power steering systems are susceptible to magnetic field interference from external sources, leading to inaccurate torque measurements and collector deformation due to eccentricity and fusion issues, which affect sensitivity and performance.
Innovation Solution
The design includes a stator with overlapping first and second stator teeth, a rotor with a magnet, and collectors disposed between these teeth, along with a housing that incorporates protrusions and grooves to maintain a consistent gap and prevent deformation, minimizing magnetic interference.
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 Hall IC causing inaccurate measurements
Solution Approach 1:
The stator tooth is divided into multiple segments (first stator tooth and second stator tooth) with collectors positioned between them. This segmentation creates separate magnetic flux paths that prevent external magnetic fields from interfering with the Hall IC, while maintaining the simplified magnetic type structure.
Solution Approach 2:
A magnetic shield is introduced as an intermediary element between the collector and the Hall IC. This shield acts as a mediator that blocks external magnetic fields from reaching the Hall IC, thereby protecting the measurement system while allowing the collector to remain in its simplified external position.
2Ease of operation
If the housing moves or becomes eccentric, then the radial gap between the collector and stator tooth changes, but this increases magnetic flux sensitivity and measurement errors
Solution Approach 1:
A magnetic shield is pre-installed between the collector and the Hall IC to compensate for potential housing movement or eccentricity. This shield cushions against variations in the radial gap, maintaining consistent magnetic flux levels even when the housing moves, thereby preventing measurement errors.
Solution Approach 2:
The magnetic shield's position and orientation are designed to automatically adjust in response to housing movement or eccentricity. By changing the shield's parameters (position, angle), the system maintains optimal magnetic flux conditions despite housing variations, preserving measurement accuracy.
3Stability of the object's composition
If collectors are fused to the housing with protrusion structures, then the collectors are fixed in position, but deformation during fusion widens the gap and changes collector positions
Solution Approach 1:
A magnetic shield is introduced as an intermediary element that compensates for gaps created during the fusion process. Even if the protrusion structures cause collector deformation or gap widening, the shield maintains the magnetic flux path, ensuring measurement accuracy is not affected by manufacturing variations.
Solution Approach 2:
The magnetic shield is designed to compensate for potential deformation and gap changes that may occur during fusion. By pre-positioning the shield to account for expected manufacturing variations, the system cushions against position changes and maintains consistent measurement conditions.
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 configuration effectively prevents external magnetic field interference and maintains sensor performance by ensuring a stable collector gap, thus enhancing the accuracy and reliability of torque measurements.
Implementation Method 1
a rotor including a magnet
Implementation Method 2
a problem affecting a magnetic flux value of a Hall integrated circuit (IC)
Data Source
AI summary
An embodiment may provide a motor comprising: a stator including stator teeth; and a rotor including a magnet, wherein the stator teeth include a first stator tooth and a second stator tooth disposed within the first stator tooth, wherein the first stator tooth includes a plurality of first teeth, the second stator tooth includes a plurality of second teeth, wherein the first teeth radially overlap the second teeth at the center of the stator in a radial direction, the motor further comprising: a sensor and a collector disposed between the first stator tooth and the second stator tooth in the radial direction, and the motor further comprising: a circuit board on which the sensor is disposed; and a housing accommodating the circuit board, wherein the collector includes a first collector and a second collector disposed within the first collector, the sensor is disposed, in the radial direction, between the first collector and the second collector, and the housing includes a first protrusion, wherein the first protrusion comprises: a body disposed, in the radial direction, between the first collector and the second collector; a head disposed at an upper end of the body; and a first groove, wherein the head includes a first surface and a second surface disposed so as to face each other, wherein the first surface is in contact with an upper end of the first collector and an upper end of the second collector, the first groove is disposed so as to be concave on the second surface, and a portion of the first groove is disposed to overlap the first and second collectors in the radial direction.