Rotation Angle Detector Hall Element Positioning Backlash
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Solution Overview
Problem
Conventional rotation angle detectors face accuracy issues due to backlash in the axial or radial direction of the rotation axis, leading to variations in the relative positions between the magnet and Hall elements, resulting in incorrect angle detection, especially when attached to steering shafts in vehicles.
Innovation Solution
A rotation angle detector design featuring a disk-shaped magnet with strategically positioned Hall elements, where the magnet is polarized to ensure optimal alignment with the Hall elements, allowing for accurate detection even with a certain degree of backlash, by positioning the Hall elements along the intermediate region of the magnetic field path and using a packaging body to shield external magnetism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If backlash is allowed in axial direction between rotor and stator to improve assembly ease, then assembly ease is improved, but detection accuracy deteriorates due to variation in relative positions
Solution Approach 1:
The patent changes the spatial arrangement parameters of Hall elements, positioning them at the intermediate region of the magnetic field path rather than directly at the magnet circumference. This parameter change makes the detection system less sensitive to axial position variations caused by backlash, thereby maintaining detection accuracy while allowing easier assembly.
Solution Approach 2:
The patent introduces the concept of an intermediate region in the magnetic field path as a mediator between the magnet and Hall elements. This intermediate positioning acts as a buffer that reduces the direct impact of axial backlash on detection accuracy, allowing both assembly ease and detection precision to be maintained.
2Reliability
If Hall elements are arranged directly under magnet circumference to improve sensitivity, then sensitivity is improved, but detection accuracy deteriorates when backlash occurs
Solution Approach 1:
The patent optimizes the spatial parameter of Hall element positioning by placing them at the intermediate region of the magnetic field path rather than directly under the magnet circumference. This parameter optimization maintains sufficient magnetic field sensitivity while reducing sensitivity to axial position variations, thereby resolving the contradiction between sensitivity and accuracy under backlash conditions.
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 configuration maintains high accuracy in detecting rotation angles, even with allowed backlash, enhancing assembly ease and stability, and is applicable to steering shafts and other devices requiring precise angle measurement.
Implementation Method 1
magnetic sensors as two units therefor. Still further, such the magnetic sensors as two units are Hall elements
Data Source
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Figure 3(a)~3(b)
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AI summary
To provide a rotation angle detector, which is characterized in that the rotation angle detector is for detecting a rotation angle of a measurable rotation body, by which it becomes able to measure the rotation angle of the measurable rotation body with an accuracy as higher even in a case where there may be happened such as an axial backlash or the like on an axis of rotation in the measurable rotation body, and then such a rotation angle detector 1 comprises: a magnetic detecting element 40, for detecting a magnetic flux density of a magnet 10 that is designed to be attached onto the measurable rotation body and then to be rotated as integral with the measurable rotation body, wherein the magnetic detecting element 40 is arranged at a position as approximately intermediate in a path from a north pole to a south pole according to a line of magnetic force due to the magnet 10, and then thereby it becomes able to measure the rotation angle of the measurable rotation body with the accuracy as higher even in the case where there may be happened such as the axial backlash or the like on the axis of rotation in the measurable rotation body.