Magnetic Rotation Angle Sensor Radial Shift Design
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Solution Overview
Problem
Conventional magnetic rotation angle sensors have limited detection ranges and increased manufacturing costs due to complex magnetic circuit constructions, where the magnetic detection device is installed on the inner circumferential side of the magnet, leading to reduced output levels and enlarged sensor sizes.
Innovation Solution
A magnetic rotation angle sensor design where the magnet is radially shifted from the rotation center, and the magnetic flux density detection device is positioned on the outer circumferential side, allowing for a wider detection range without increasing the number of components, with the magnet being magnetized in the tangential or normal direction of the turning circle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetic detection device is installed on the inner circumferential side of the magnet, then the magnetic flux can be concentrated, but the output level decreases and the detection range is limited to less than 180 degrees
Solution Approach 1:
The patent inverts the conventional arrangement by placing the magnetic detection device on the outer circumferential side of the magnet instead of the inner circumferential side. This inversion allows the detection device to detect magnetic flux from a wider angular range, extending the linear detection range to approximately 300 degrees while maintaining adequate output level through optimized radial positioning.
Solution Approach 2:
The patent utilizes radial positioning in addition to angular positioning to optimize detection performance. By adjusting the radial distance between the magnet and detection device, the system achieves both wide angular detection range and sufficient magnetic flux intensity, adding a dimensional degree of freedom to the design.
2Power
If the magnet is formed in a large size to increase magnetic flux quantity, then the output level increases, but the entire sensor size increases
Solution Approach 1:
The patent changes the geometric parameters of the magnet, specifically using a smaller magnet with optimized dimensions (outer diameter 1.6-2.4 times the thickness, length 3-6 times the thickness) to achieve sufficient magnetic flux output without increasing overall sensor size. The detection device's radial positioning compensates for the reduced magnet size.
3Adaptability or versatility
If two Hall effect devices are used to calculate magnetic flux angle, then the detection range can be extended, but the number of parts increases and manufacturing cost increases
Solution Approach 1:
The patent makes a single Hall effect device perform multiple functions by positioning it to detect magnetic flux variations over a wide angular range (approximately 300 degrees). The detection device simultaneously captures flux information across different angles, replacing the need for multiple devices used in conventional arrangements.
4Adaptability or versatility
If the magnetic detection device is positioned on the rotation path of the magnet, then the detection range is maximized, but the device hinders the movement of the magnet
Solution Approach 1:
The patent employs asymmetric positioning where the magnetic detection device is located on the outer circumferential side at a specific radial distance from the rotation center, rather than symmetrically on the rotation path. This asymmetric arrangement maximizes detection range while avoiding mechanical interference with magnet rotation.
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 enhances the linearity of the output over a wider rotation angle range, reduces the size of the sensor, and maintains a high detection accuracy by optimizing the magnetic flux distribution, enabling detection of rotation angles up to approximately 300 degrees with a single Hall IC.
Implementation Method 1
a magnetic flux density detection device that detects a magnetic flux density of the magnetic flux
Data Source
AI summary
In a magnetic rotation angle sensor for detecting a rotation angle of a detection target, a yoke covers outer circumferences of a magnet and a Hall device. One of the magnet and the magnetic flux density detection device rotates together with the detection target. The Hall IC is radially shifted from a rotation center of the detection target. The magnetic flux density detection device has a detection surface that is in parallel to one of a tangential direction and a normal direction of a turning circle. The magnet is magnetized in the one of the tangential direction and the normal direction of the turning circle.