Rotation Angle Detection Device Using Biasing Magnet
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Solution Overview
Problem
Conventional rotation angle detection devices suffer from undulation in detection results due to variations in magnetic sensor characteristics, limiting the detection range to a narrow linear region, making accurate angle detection challenging beyond this range.
Innovation Solution
The device biases the magnetic field generated from the part to be detected towards the rotation surface, filtering out variations in magnetic flux components detected by magnetism sensing elements, ensuring linearity in a wider rotation angle range through differential detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If differential detection is performed using magnetic sensors disposed on axial lines, then the effect of disturbance magnetic field in the axial direction is suppressed, but detection result undulation occurs due to variation in sensor characteristics
Solution Approach 1:
A magnet is introduced as an intermediary component between the rotation member and the magnetic sensors. This magnet generates a magnetic field that biases the magnetic flux components detected by the sensors, allowing the differential detection to filter out sensor characteristic variations while maintaining sensitivity to rotation angle changes.
Solution Approach 2:
The magnetic field parameters are changed by introducing a biasing magnet that alters the magnetic flux distribution. This changes the operating point of the magnetic sensors, enabling them to operate in a region where differential detection effectively cancels out characteristic variations while maintaining linearity over a wider angle range.
2Measurement precision
If detection is performed in a narrow linear region to avoid undulation, then detection accuracy is maintained, but the rotation angle detection range is limited
Solution Approach 1:
The magnetic field parameters are modified by adding a biasing magnet, which changes the magnetic flux detection characteristics. This parameter change extends the linear detection range of the sensors, allowing accurate detection over a wider rotation angle range without the undulation problems of conventional differential detection.
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 approach enhances detection accuracy by eliminating undulation, allowing accurate rotation angle detection over a double the conventional range, thereby expanding the usable angle range for precise measurements.
Implementation Method 1
uses magnetism sensing elements disposed on detection axes for detecting a magnetic field generated from a part to be detected
Implementation Method 2
the difference in output voltage between the pair of detection elements is computed to detect the magnetic flux, thereby eliminating the effect of the disturbance magnetic field in the axial direction
Data Source
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Figure 3A
AI summary
Provided is a rotation angle detection device capable of obtaining a detection result in a wider angle range with high accuracy. A rotation angle detection device 1 is provided with a part to be detected 4 which is attached to a throttle shaft S by a rotor 3, and a Hall IC 5 which detects magnetic flux components of the part to be detected 4. The Hall IC 5 is provided with a magnetism collecting plate 51 which is disposed facing the part to be detected 4 and extends along the rotation surface of the part to be detected 4, and Hall elements 52 which detect the magnetic flux components of the part to be detected 4, and output a signal corresponding to the rotation position of the throttle shaft S on the basis of the results of the detection by the Hall elements 52. The Hall elements 52a, 52c each detect a magnetic flux component in an X-axis direction passing through the rotation axis of the throttle shaft S. The Hall elements 52b, 52d each detect a magnetic flux component in the Y-axis direction passing through the rotation axis of the throttle shaft S. The part to be detected 4 is configured by combining a semicircular yoke 41 with a semiannular magnet 42.