Rotation Angle Detector With Soft Magnetic Yoke
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Solution Overview
Problem
Conventional rotation angle detectors are not suitable for measuring the rotation angle of steering shafts due to integration issues with the shaft, leading to unstable magnetic circuits and calibration challenges caused by differences in material, size, and fixing status.
Innovation Solution
A rotation angle detector with a ring-shaped magnet and a soft magnetic yoke integrated on the inner side, which stabilizes the magnetic circuit and prevents magnetic flux from reaching the shaft, ensuring accurate measurement regardless of the shaft's material, size, and fixing status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ring-shaped magnet is used to allow shaft insertion, then the detector can be fixed to the steering shaft, but the magnetic circuit becomes unstable due to shaft material and diameter variations
Solution Approach 1:
A yoke made of soft magnetic material is introduced as an intermediary component between the ring-shaped magnet and the steering shaft. This yoke serves as a magnetic circuit mediator that guides and stabilizes the magnetic flux, preventing it from being directly affected by the shaft's material properties, diameter variations, and assembly gaps. The soft magnetic material in the yoke provides a low-reluctance path for magnetic flux, ensuring stable magnetic circuit formation regardless of shaft characteristics.
2Measurement precision
If the magnet is integrated with the rotating shaft, then the rotation angle can be detected, but the detector cannot be flexibly fixed to different locations on the steering shaft
Solution Approach 1:
The detector is segmented into distinct functional components: the ring-shaped magnet, the yoke, and the sensor assembly. This segmentation allows the magnet and yoke to be fixed to the steering shaft at various locations, while the sensor assembly remains separate and can be positioned independently. The ring-shaped magnet with its through-hole design enables flexible mounting options on the steering shaft, decoupling the detection function from fixed integration requirements.
3Measurement precision
If hall elements are calibrated in advance, then detection accuracy can be improved, but the complexity of the assembly process increases
Solution Approach 1:
The yoke is pre-formed with a specific geometry and magnetic properties that inherently stabilize the magnetic circuit. This preliminary design of the yoke structure ensures that the magnetic flux distribution remains consistent regardless of assembly variations, eliminating the need for post-assembly calibration of the hall elements. The pre-configured magnetic circuit path in the yoke provides built-in compensation for assembly tolerances.
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
The solution provides stable and accurate rotation angle detection by forming a consistent magnetic circuit around the magnet, reducing output dispersion and eliminating the need for calibration, making it suitable for high-accuracy applications like steering devices.
Implementation Method 1
the yoke is provided on inner side of the ring shaped magnet, the inner side (shaft side) of the magnetic flux of the magnetic circuit is formed so as to pass through the inside of the yoke
Implementation Method 2
The yoke is made from soft magnetic material
Implementation Method 3
two magnetic sensors are provided. The two magnetic sensors consist of hall elements
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4
AI summary
A rotation angle detector (1) for detecting the rotation angle of a rotator to be measured which detects the flux density, generated depending on rotation of the rotator to be measured, of a ringlike magnet (10) fixed to the rotator by means of a magnetic detection element. Since a soft magnetic member (20) is interposed between the ringlike magnet (10) and the rotator, rotation angle of the rotator can be measured accurately without being affected by the material or diameter of the rotator or the fixing state of the rotation angle detector to the rotator. Consequently, a rotation angle detector for detecting the rotation angle of a rotator to be measured accurately without being affected by the material or diameter of the rotator or the fixing state of the rotation angle detector to the rotator is presented.