Rotational Angle Sensor with Magnetic Yoke Flux Detection
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Solution Overview
Problem
Conventional rotational angle detecting devices face challenges in achieving high detection precision and low manufacturing costs due to the need for a rotation transmitting mechanism, complex holding structures, and difficulties in miniaturization and sealing, especially when using permanent magnets.
Innovation Solution
A rotational angle detecting device with a flat face part on the detected object, a permanent magnet, a pair of first yokes arranged in line symmetry, and a second yoke, where the rotational angle is calculated based on magnetic flux densities in parallel and perpendicular directions detected by magnetic sensitive elements, eliminating the need for a rotation transmitting mechanism and allowing for a one-piece angle sensor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotation transmitting mechanism is used to rotate the permanent magnet in association with the detected object, then the detection precision can be improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical rotation transmitting mechanism with a magnetic field-based detection system. The permanent magnet is fixed to the detected object, and its rotational position is detected through changes in magnetic flux density at fixed detection points, eliminating the need for complex mechanical transmission components.
Solution Approach 2:
The patent introduces magnetic flux density as an intermediary parameter to transmit rotational information. Instead of directly mechanically transmitting rotation, the system uses the magnetic field generated by the permanent magnet as a mediator to convey positional information to the detection elements.
2Reliability
If the angle sensor unit is formed as a one-piece product with air-tight accommodation, then the reliability is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the sensor components and accommodation structure into a integrated one-piece unit. The case, permanent magnet, and detection elements are combined into a single manufactured component, simplifying the overall structure while maintaining air-tight properties and reducing the need for separate holding mechanisms.
3Device complexity
If the permanent magnet is attached to the detected object by eliminating the rotational member, then the device complexity is reduced, but magnetic contamination occurs during manufacturing
Solution Approach 1:
The patent segments the sensor system into distinct functional components: the permanent magnet attached to the detected object and the detection elements positioned separately. This segmentation allows the magnet to be mounted without complex rotational members while enabling controlled positioning that minimizes magnetic contamination risks during assembly.
4Measurement precision
If precision work is performed to combine the rotational member and detected object as one-piece, then the detection precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs self-aligning magnetic field interactions to establish precise positional relationships without requiring high-precision mechanical assembly. The magnetic flux distribution naturally guides the detection elements to their correct positions relative to the permanent magnet, reducing the need for expensive precision machining and alignment procedures.
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 enables high detection precision, reduces manufacturing costs, and allows for miniaturization and easy handling of the angle sensor unit, while eliminating mechanical errors and the complexity of air-tight accommodation, thereby enhancing the degree of freedom in application and installation.
Implementation Method 1
permanent magnets are arranged to alternate an N pole region thereof with an S pole region thereof
Implementation Method 2
magnetic detection elements arranged in a predetermined position to the rotational member, wherein a rotational angle of the rotational member is calculated based upon the detection result of magnetic field components
Implementation Method 3
a pair of first yokes that are arranged in line symmetry with respect to a reference line passing a rotational axis of the detected object and along the magnetization direction and project in parallel with the rotational axis of the detected object from the permanent magnet
Data Source
AI summary
A rotational angle detecting device may include a flat face part formed on a detected object, and a permanent magnet having a magnetic pole face facing the flat face part. The device may also include a pair of first yokes arranged in line symmetry along a magnetization direction and project in parallel with a rotational axis of the detected object from the permanent magnet, and a second yoke spaced from projecting ends of the first yokes to face a face of the permanent magnet, the first yokes projecting from the face. The device may further include a magnetic detection element having a magnetic sensitive part positioned in a detection point corresponding to each of the first yokes, and may be configured to detect magnetic flux densities in directions parallel with the rotational axis and a magnetic flux density in a direction perpendicular to the rotational axis and the reference line.