Steering Angle Detection Using Magnetic Field Difference
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Solution Overview
Problem
The existing steering angle detection methods in EPS systems face issues with slow response rates and inaccuracies due to the method of acquiring angular information through electrical excitation, which can cause common cause failures and slow responses.
Innovation Solution
A steering angle detection apparatus and torque sensing method utilizing a cylindrical rotor with alternately disposed permanent magnets, a cylindrical stator body, and stator rings with magnetic sensors to calculate torque based on the difference in magnetic fields sensed by the rotating rotor, allowing for accurate and rapid torque sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical excitation method is used to acquire angular information, then the steering angle can be detected, but the response is slow
Solution Approach 1:
The patent replaces the electrical excitation system with a magnetic field-based detection system. A rotor containing permanent magnets rotates with the steering shaft, generating magnetic fields that are detected by magnetic sensors on the stator. This substitution eliminates the excitation circuit and its associated reliability issues while maintaining angular detection capability.
Solution Approach 2:
The magnetic sensors detect periodic variations in magnetic field strength as the magnets on the rotor pass by. The frequency of these periodic variations corresponds to the rotational speed and angle, providing both accurate measurement and fast response without the delays inherent in electrical excitation systems.
2Device complexity
If a simple magnetic field sensing structure is used, then the device complexity is reduced, but the torque sensing accuracy may be affected
Solution Approach 1:
The patent divides the magnetic detection system into two separate stator rings, each with its own magnetic sensors. One stator ring detects the magnetic field at a position corresponding to the leading edge of the magnets, while the other detects at the trailing edge. This segmentation allows independent measurement of magnetic field differences, improving torque accuracy while keeping each individual sensor simple.
Solution Approach 2:
The patent measures torque not just by the magnitude of the magnetic field, but by the difference in magnetic field strength between two spatially separated stator rings. This dimensional approach (comparing fields at different positions) provides torque information without requiring complex sensor structures, achieving accurate torque sensing through spatial differentiation.
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 response rate and accuracy of torque sensing, improving the stability and performance of the steering system by calculating torque using the difference in magnetic fields sensed by the stator rings, thereby facilitating better control of the steering motor.
Implementation Method 1
a rotor formed in a cylindrical shape having a central region, in which a space for housing a rotary shaft is formed, and configured to have a plurality of permanent magnets of different polarities alternately disposed at regular intervals in a circumferential direction
Implementation Method 2
one pair of magnetic sensors installed at a certain distance from each other in a circumferential direction of the pair of stator rings on external sides of the pair of stator rings and configured to sense magnetic fields generated when the rotor rotates
Data Source
AI summary
Provided are an apparatus for detecting a steering angle, a steering system, and a torque sensing method of the steering system. The apparatus includes a rotor formed in a cylindrical shape having a central region, in which a space for housing a rotary shaft is formed, and configured to have a plurality of permanent magnets of different polarities alternately disposed at regular intervals in a circumferential direction, a stator body formed in a cylindrical shape having a space for housing the rotor, and two stator rings formed in ring shapes coupled to the stator body and disposed at a certain distance in a longitudinal direction of the rotary shaft. Accordingly, it is possible to calculate an accurate torque, and a response rate is increased so that stability and performance of the steering system can be improved.