Eccentric Hall Sensor Angular Position Measurement
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Solution Overview
Problem
Existing angular position measurement devices face challenges with poor sensitivity, making them unsuitable for small oscillations or high precision applications, and are often costly and difficult to implement, especially when free axial access is necessary.
Innovation Solution
A device using a diametrally polarized ring-shaped permanent magnet with a linear Hall effect sensor positioned eccentrically relative to the axis of rotation, where the magnet's angle of extension is carefully aligned with the angle of oscillation to ensure continuous and high-sensitivity signal output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a magnetic sensor is mounted axially aligned with the axis of rotation and magnetically coupled to an eccentric permanent magnet, then the device can measure angular position, but the device has considerable dimensions and is not usable when free axial access is necessary
Solution Approach 1:
The patent inverts the conventional mounting arrangement by positioning the Hall effect sensor on the rotating body and the permanent magnet on the fixed body, opposite to the traditional configuration. This inversion enables free axial access while maintaining measurement functionality, directly resolving the contradiction between axial access availability and device dimensions.
2Measurement precision
If prior art measuring systems are used, then angular position can be measured, but they show poor sensitivity making them unusable for small oscillations or high precision applications
Solution Approach 1:
The patent changes the geometric parameters of the permanent magnet, specifically using a circular arc shape with a carefully selected angle of extension (α) that is less than the angle of oscillation (θ). This parameter change, combined with diametral polarization at a specific angle, optimizes the magnetic field distribution to achieve high sensitivity for small oscillations while maintaining reliability across the entire measuring range.
Solution Approach 2:
The patent employs asymmetric diametral polarization where the polarization direction forms a specific angle with respect to the chord subtended by the circular arc, rather than using symmetric radial or standard diametral polarization. This asymmetric configuration optimizes the magnetic field gradient for high sensitivity measurements.
3Measurement precision
If diametrically polarized permanent magnets with circular arc shape are used, then angular position measurement is achieved, but only two alternative directions of polarization are used (parallel or perpendicular to the chord), limiting measurement performance
Solution Approach 1:
The patent extends the polarization direction options beyond the two conventional alternatives by introducing a specific angle parameter for diametral polarization relative to the chord. This parameter change enables optimization of the magnetic field distribution for high sensitivity measurements while maintaining the simplicity of diametral polarization.
4Reliability
If magnetic flux conveyors are used to guarantee sufficient measuring reliability, then measurement reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the magnetic flux conveyor component from the measuring system. By optimizing the permanent magnet geometry (circular arc with specific angle of extension) and polarization, the system achieves sufficient measuring reliability without the additional complexity and cost of magnetic flux conveyors.
Solution Approach 2:
The optimized permanent magnet configuration serves its own function of guiding and concentrating the magnetic field lines effectively, making the magnet self-sufficient in providing reliable measurements without requiring separate magnetic flux conveyor components.
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 a continuous measuring signal with high sensitivity across the entire measuring range, is cost-effective, and easy to produce, while maintaining operational efficiency within the specified angular range.
Implementation Method 1
contactless magnetic measurements that use the interactions between a permanent magnet and a magnetic sensor (usually a Hall effect sensor)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A device for measuring an angular position, comprising a rotating body (3) that oscillates relative to a supporting body (2) between two limit positions which are rotated one relative to the other by an angle of oscillation θ with amplitude that is less than or equal to 150°, a permanent magnet (5) that extends along an arc of extension that corresponds to an arc of a circle centred on the main axis of rotation (4), the arc of extension subtending an angle of extension α, and a magnetic sensor (6) positioned eccentrically relative to the main axis of rotation (4); the permanent magnet (5) and the magnetic sensor (6) being fixed one to the rotating body (3) and the other to the supporting body (2), and always being magnetically coupled; the following relation applying between the angle of extension α of the permanent magnet (5) and the angle of oscillation θ: α>θ−30°; and the permanent magnet (5) being diametrally polarized and having a direction of polarization (12) that forms an angle that is less than or equal to 10° relative to a straight line perpendicular to the main axis of rotation (4) and passing both through the main axis of rotation (4), and through a first end of the arc of extension.