Asymmetric Yoke Design for Rotational Angle Sensing Accuracy
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Solution Overview
Problem
Existing rotational angle sensing devices face challenges in maintaining sensing accuracy due to reduced magnetic flux and increased manufacturing costs when minimizing magnet volumes, as the narrower parallel magnetic field range can be affected by manufacturing tolerances and Hall IC displacement.
Innovation Solution
A rotational angle sensing device with a tubular yoke and opposing magnets, where the yoke's larger inner diameter in one direction maintains a balanced magnetic flux, allowing for a wider parallel magnetic field and improved sensing accuracy, while reducing magnet volume to lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the volumes of the magnets are reduced to lower manufacturing costs, then manufacturing costs are reduced, but the magnetic flux between the magnets decreases and the range of the parallel magnetic field narrows, reducing sensing accuracy
Solution Approach 1:
The yoke is designed with an asymmetric cross-section where the inner diameter in the second direction (perpendicular to the first direction and central axis) is larger than the inner diameter in the first direction. This asymmetric geometry creates an elongated parallel magnetic field range in the second direction, compensating for the reduced magnetic flux from smaller magnets and maintaining sensing accuracy even when the Hall IC is displaced from the central axis
Solution Approach 2:
The invention changes the geometric parameters of the yoke, specifically making the inner diameter in the second direction larger than in the first direction. This parameter change elongates the magnetic field distribution in the second direction, allowing the parallel magnetic field to extend further and maintain adequate flux density even with reduced magnet volumes
2Ease of manufacture
If the volumes of the magnets are reduced to lower manufacturing costs, then manufacturing costs are reduced, but the magnetic flux flows between circumferential ends of the magnets and the inner wall of the yoke, reducing the range of the parallel magnetic field
Solution Approach 1:
The asymmetric yoke design with different inner diameters in different directions directs the magnetic flux distribution. The larger inner diameter in the second direction creates more space for magnetic flux to flow parallel to the magnets in that direction, effectively extending the parallel magnetic field range even when magnet volume is reduced
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 enhances sensing accuracy and reduces manufacturing costs by maintaining a stable magnetic field even with smaller magnets, ensuring precise voltage signal output and easier magnet production.
Implementation Method 1
A magnetic sensing means is for sensing a magnetic field, which is generated between the first magnet and the second magnet
Implementation Method 2
A Hall IC is placed at the central axis such that the two magnets are rotatable relative to the Hall IC. A voltage signal, which is outputted from the Hall IC, is sensed to sense a rotational angle of the accelerator pedal
Data Source
AI summary
First and second magnets are installed to an inner peripheral wall of a yoke, which is configured into a tubular form. The yoke is constructed from at least one plate material. At each contact portion, a corresponding circumferential end part of the at least one plate material and another corresponding circumferential end part of the at least one plate material contact with each other. A Hall IC is placed in a magnetic field, which is generated between the first and second magnets.