Axially Magnetized Sensor Magnet for Steering Torque Interference
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Solution Overview
Problem
Existing steering angle sensors suffer from measurement inaccuracies due to the spatially extensive magnetic fields of disc-shaped, diametrically magnetized permanent magnets, which cause interference between neighboring sensor systems, leading to undesired measurement errors.
Innovation Solution
A device with a torque sensor and a rotation angle sensor, where the rotation angle sensor uses a two-pole, axially magnetized permanent magnet with a defined magnetization and a shielding device to decouple magnetic fields, allowing for precise measurement of the magnetic field direction and orientation without interfering with the torque sensor, and a magnetic field detector to determine the angle of rotation accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If disc-shaped, diametrically magnetized permanent magnets are used in the rotation angle sensor, then the magnetic field is spatially extensive (4-5 times the diameter of the magnet), but this causes interference in neighboring sensor systems and leads to measurement inaccuracies
Solution Approach 1:
The patent changes the magnetization parameters from diametric to axial direction, and from multi-pole to two-pole configuration. This parameter change concentrates the magnetic field lines between the axial poles rather than allowing them to extend radially outward, thereby reducing spatial interference while maintaining sufficient field strength for sensor detection
Solution Approach 2:
The patent introduces an asymmetric magnetic field distribution by using axial magnetization with two poles, creating a concentrated field pattern between the poles. This asymmetric field configuration differs from the symmetric radial distribution of diametric magnetization, enabling better spatial containment of the magnetic field
2Area of stationary object
If two sensor systems (torque sensor and rotation angle sensor) are arranged adjacent to each other, then space utilization is improved, but magnetic field interference between the sensors causes measurement errors
Solution Approach 1:
By changing the magnetization parameters to axial two-pole configuration, the magnetic field is concentrated in a smaller spatial volume between the poles. This allows the rotation angle sensor to generate sufficient magnetic field signal for accurate measurement while minimizing field extension into the torque sensor's measurement area, enabling close arrangement of both sensors
Solution Approach 2:
The axial two-pole magnetization creates a localized concentration of magnetic field lines between the two poles, with rapidly decreasing field strength in radial directions. This local quality enhancement ensures strong field where needed (between poles for sensor detection) while minimizing field presence in neighboring regions (torque sensor area)
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 enhances measurement accuracy by concentrating magnetic field lines in a small spatial volume, reducing interference and increasing signal strength, thereby improving the precision of both torque and rotation angle measurements while allowing for a compact integration of sensor systems.
Implementation Method 1
a permanent magnet and a magnetic field detector, the magnetic field detector being designed to detect the direction of the magnetic field generated in particular by the permanent magnet
Implementation Method 2
there is a shielding device for magnetic fields between the torque sensor and the angle of rotation sensor
Data Source
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Figure 3~4
Figure 5
AI summary
The invention relates to a device, in particular for a motor vehicle, comprising a torque sensor (1) for determining a torque of a steering shaft and a rotation angle sensor (2) for determining a rotation angle of the steering shaft, wherein the torque sensor (1) operates with the aid of a magnetic field, and the rotation angle sensor (2) comprises a permanent magnet (4) and a magnetic field detector (3, 3a, 3b), wherein the magnetic field detector (3, 3a, 3b) is designed to detect the direction of a magnetic field, and the torque sensor (1) and the rotation angle sensor (2) are disposed adjacent to one another, and wherein a shielding device (12) for magnetic fields is disposed between the torque sensor (1) and the rotation angle sensor (2) and/or the permanent magnet (4) of the rotation angle sensor (2) is designed to be double-pole axially with a main axis (H).