Shielded Magnetic Torque Sensor for Steering Shaft Precision
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Solution Overview
Problem
Magnetic torque sensor devices in motor vehicles are susceptible to measurement errors due to external disruptive magnetic fields, particularly from electrical currents and the Earth's magnetic field, which are exacerbated by vehicle electrification.
Innovation Solution
An improved shielding element, formed from a metal plate with high magnetic permeability, is arranged around the magnetic ring and stator ring of the torque sensor device, covering the torque sensor device and deflecting disruptive magnetic fields, thereby enhancing measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic shield is added to reduce external disruptive magnetic fields, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The magnetic shield is integrated within the existing housing structure of the torque sensor device. The shield forms a nested configuration where it is positioned between the housing and housing cover, utilizing the existing structural space to provide shielding functionality without adding external complexity.
Solution Approach 2:
The magnetic shield serves multiple functions: it provides magnetic field shielding to protect the sensor from external disruptive fields, acts as a structural component within the housing assembly, and facilitates the clamping mechanism that secures the shield in place. This multi-functionality reduces the need for separate components.
2Reliability
If the shield is clamped between the housing and housing cover, then shielding effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The magnetic shield is designed as a separate component that can be manufactured independently from the housing and housing cover. This segmentation allows each component to be optimized for its specific function while simplifying the assembly process. The shield is inserted and clamped between the housing and cover, requiring less precise matching than if it were an integrated part.
3Ease of operation
If the shield is designed to match the housing precisely, then clamping effect is improved, but shielding optimization is limited
Solution Approach 1:
The magnetic shield is designed with specific local properties including a magnetic permeability of μr > 200 to optimize its shielding effectiveness. The shield's geometry and material properties are tailored to provide optimal magnetic field blocking in the critical regions around the sensor, while still maintaining compatibility with the housing structure for effective clamping.
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 shielding element significantly reduces measurement errors, allowing for more precise detection of torque applied to the steering shaft by minimizing external magnetic interference.
Implementation Method 1
the shielding element, formed from a metal plate with high magnetic permeability, is arranged around the magnetic ring and stator ring of the torque sensor device
Data Source
AI summary
An electromechanical steering system comprises a steering shaft, with a magnetic torque sensor device for measuring a torque applied to the steering shaft and with a shielding element. The steering shaft comprises an input shaft which can be rotationally fixedly connected to a steering handle and penetrates through the shielding element, and an output shaft which is connected to the input shaft via a twistable torsion bar. The torque sensor device comprises a multipole magnetic ring rotationally fixedly connected to the input shaft, a stator ring element rotationally fixedly connected to the output shaft and surrounding the magnetic ring, a magnetic flux collector and a sensor for detecting a magnetic flux density. The shielding element is arranged following the magnetic ring, the shielding element covering the surface of the magnetic ring and the stator ring element with respect to the steering handle.