Contactless Torque Sensor Magnetic Shield Holes
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Solution Overview
Problem
Conventional contactless torque sensors for steering systems detect twist angles between input and output shafts through two processes of magnetic induction, leading to decreased and distorted magnetic flux, which hampers accurate detection.
Innovation Solution
A contactless torque sensor design featuring a magnetic force generating part with alternating N and S pole magnets on the input shaft and a magnetic shield part with strategically positioned holes in a hollow cylinder, allowing magnetic flux to pass through and be detected directly by a magnetic detection sensor, reducing the number of induction processes and maintaining flux strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional contactless torque sensor uses two processes of magnetic induction through a detection ring and a stationary detection ring, then the twist angle can be detected, but the magnetic flux is decreased and distorted leading to reduced detection accuracy
Solution Approach 1:
The patent removes the stationary detection ring from the magnetic flux path, extracting only the necessary rotating detection ring. This eliminates the second magnetic induction process that caused flux distortion, allowing direct detection of magnetic flux changes from the permanent magnet through the rotating detection ring, thereby maintaining magnetic flux strength while detecting twist angles accurately
Solution Approach 2:
The patent introduces a magnetic shield ring as an intermediary component with through-holes that allows magnetic flux to pass through while shielding external magnetic interference. The magnetic shield ring with strategically positioned through-holes enables the magnetic flux from the permanent magnet to reach the detection ring without being distorted by a stationary detection ring, thus preserving flux strength and improving detection accuracy
2Reliability
If a conventional torque sensor uses a rotating detection ring around the sensor, then the magnetic force can be detected, but there is much fluctuation in magnetic force and interference between the detection ring and magnet detection device
Solution Approach 1:
The magnetic shield ring acts as an intermediary between the permanent magnet and the detection ring, providing a stable magnetic flux path through its through-holes. This intermediary structure reduces magnetic force fluctuation and prevents interference between the rotating detection ring and the magnet detection device, thereby improving detection reliability
Solution Approach 2:
The magnetic shield ring has through-holes positioned at specific locations to allow magnetic flux to pass through only where needed. This local quality approach ensures that magnetic flux is channeled precisely to the detection ring while blocking unnecessary magnetic paths, reducing fluctuation and interference for more reliable detection
3Object-affected harmful factors
If a stationary detection ring is additionally installed to avoid interference, then interference is avoided, but the magnetic flux is decreased and distorted by going through magnetic induction two times
Solution Approach 1:
The patent extracts the stationary detection ring from the system, eliminating the second magnetic induction process. By using only the rotating detection ring in conjunction with the magnetic shield ring, the system avoids the dual induction process that caused flux distortion while still preventing interference through proper magnetic shielding
Solution Approach 2:
The magnetic shield ring serves as an intermediary that prevents interference between the rotating detection ring and the magnet detection device without requiring a stationary detection ring. The shield ring's through-holes guide magnetic flux directly to the detection ring, maintaining flux strength while avoiding the harmful effects of dual magnetic induction
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 enables accurate detection of twist angles between input and output shafts with reduced magnetic flux distortion, improving the sensor's accuracy and manufacturing efficiency by minimizing parts and processes.
Implementation Method 1
a magnetic flux is changed in the detection ring and the change of the magnetic flux is detected through the sensor
Implementation Method 2
the magnetic flux generated from the permanent magnet is magnetically induced firstly through the detection ring and then magnetically induced secondly through the stationary detection ring
Data Source
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AI summary
The present invention relates to a contactless torque sensor for a steering system which is installed between an input shaft connected to the steering wheel of the vehicle and an output shaft connected to the wheels of the vehicle and detects torsion generated by rotational manipulation of the steering wheel. The torque sensor comprises: a magnetism generation unit which is coupled with the input shaft wherein plural north pole and south pole magnets are arranged alternately along the outer circumference thereof to have the same distance from the center, a cylindrical magnetic shielding unit which is connected to the output shaft and comprises plural holes respectively placed in the plural north pole and south pole areas, a magnetic detection unit which is distanced from the outer circumference of the magnetic shielding unit and detects magnetism passing through the plural holes, and a magnetic detection sensor which is placed on the outer circumference of the magnetic detection unit and detects relative torsion variation of the magnetism generation unit and magnetic shielding unit. Therefore, without inducing the magnetism twice, the present invention can detect degree of torque of the output shaft with magnetism induced once.