Ring Magnet Arrangement for Accurate Rotational Angle Detection
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Solution Overview
Problem
Existing rotational angle detection systems using tapered magnets suffer from inaccurate measurements due to impure sine waves generated by the magnetic field, leading to a high margin of error and mechanical issues such as demagnetization and mechanical failure.
Innovation Solution
A ring-shaped magnet arrangement formed from a single piece of material with intersecting thickness and magnetized in opposite directions, creating a wedge that produces a relatively pure sine wave magnetic field for accurate rotational angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tapered magnets are used in rotational angle detection systems, then the magnetic field can be generated, but the measurements become inaccurate due to impure sine waves
Solution Approach 1:
The magnet is divided into multiple segments with different magnetization directions (first magnet portion with first magnetization direction, second magnet portion with second magnetization direction). This segmentation allows each portion to contribute differently to the magnetic field, creating a pure sine wave pattern that eliminates measurement inaccuracies while maintaining reliable rotational angle detection.
2Strength
If traditional magnet arrangements are used, then the structure is simple, but mechanical failures and demagnetization occur
Solution Approach 1:
The magnet employs a composite structure with multiple magnet portions having different magnetization directions arranged in specific spatial relationships. This composite configuration enhances mechanical strength and distributes stress more evenly, while the alternating magnetization patterns provide resistance to demagnetization by creating a more robust magnetic structure that prevents mechanical failures.
3Volume of moving object
If the magnet arrangement is designed with intersecting thickness, then the overall size is maintained, but the manufacturing complexity increases
Solution Approach 1:
The magnet incorporates an intersecting thickness parameter that varies across different portions of the magnet structure. By carefully controlling this geometric parameter, the design maintains a compact overall size while the systematic variation in thickness follows manufacturable patterns that can be produced using standard machining or molding processes, balancing size constraints with manufacturing feasibility.
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 enables accurate rotational angle detection within 1 degree, improves mechanical strength, and reduces the risk of demagnetization, while maintaining the overall size and robustness of the magnet arrangement.
Implementation Method 1
a first ring portion magnetized in a first direction; and a second ring portion magnetized in a second direction that is opposite the first direction
Data Source
AI summary
A ring-shaped magnet arrangement for use in determining a rotational angle of a rotatable shaft. The ring-shaped magnet arrangement being connected to or formed as part of the rotatable shaft for co-rotation with the rotatable shaft around a rotational axis. The ring-shaped magnet arrangement includes a first ring portion including a first wedge surface and a second ring portion including a second wedge surface. The first wedge surface and the second wedge surface form a wedge in a sensor facing end of the ring-shaped magnet arrangement. The sensor facing end is axially opposite a radial end of the ring-shaped magnet arrangement.