Tubular Magnet Layout for Tolerant Angular Position Sensing
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Solution Overview
Problem
Magnetic sensor systems used to determine relative angular positions in constrained spaces face accuracy issues due to ferromagnetic parts and external magnetic field disturbances, and existing solutions are either costly or lack robustness against mounting tolerances and dynamic clearance.
Innovation Solution
A sensor system with a tubular permanent magnet having a magnetization vector that varies orthogonally across its surface, allowing for accurate angular position determination by measuring magnetic induction components at specific points, and a method for manufacturing this magnet using a pattern of parallel electrical conductors to achieve a robust and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If axial magnetization with multiple pole pairs is used, then measurement accuracy is improved, but robustness to mounting tolerances and dynamic clearance deteriorates
Solution Approach 1:
The patent changes the magnetization parameter from axial to radial direction, creating a single magnetic pole on the measurement side. This parameter change fundamentally alters the magnetic field distribution, making the measurement less sensitive to axial mounting tolerances and dynamic clearance variations while maintaining high measurement accuracy through the specialized tubular magnet geometry with continuously variable magnetization orientation.
2Measurement precision
If Halbach magnetization with shielding is used, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex shielding structure from the Halbach magnetization system. By using radial magnetization with a single magnetic pole oriented toward the measurement side, the invention achieves accurate angular position measurement without requiring additional shielding components, thereby reducing device complexity and cost while maintaining measurement precision.
Solution Approach 2:
The patent replaces the expensive and complex Halbach magnetization system with a simpler radial magnetization approach using a tubular magnet. This substitution uses more economical materials and manufacturing methods (such as circumferential winding of coils or magnetization after assembly) while achieving comparable or superior measurement accuracy without the need for costly shielding structures.
3Reliability
If radial magnetization with single magnetic pole is used, then robustness to mounting tolerances is improved, but resistance to external magnetic fields deteriorates
Solution Approach 1:
The patent employs a composite approach by combining radial magnetization with a specifically oriented tubular magnet structure. The magnetization vectors are continuously oriented from the radial inward direction at one end to the radial outward direction at the other end, creating a sophisticated magnetic field distribution that provides both robustness to mounting tolerances and inherent resistance to external magnetic field interference through the structured field geometry.
4Measurement precision
If complex magnetization patterns are used, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies preliminary action by performing magnetization after the tubular magnet assembly is complete, rather than requiring complex pre-magnetization of individual components. The circumferential winding of coils around the assembled tubular structure allows for simplified manufacturing where the magnetization is applied in a single final step, reducing overall manufacturing cost while achieving the desired continuously variable magnetization pattern for high measurement accuracy.
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 system provides accurate and reliable angular position determination with robustness against external magnetic fields and mounting inaccuracies, while being compact and cost-effective for large-scale production.
Implementation Method 1
the magnetized body has a permanent magnetization such that, for any point of the magnetized body on a given circle about the main axis, the magnetization vector at a point of the given circle presents, in orthogonal projection on a plane perpendicular to the main axis, a projected vector whose relative orientation with respect to the particular radial segment at this point is a continuously variable function according to a law of variation
Implementation Method 2
a primary pair of measurement elements comprising a first primary measurement element making it possible to determine, at a first primary measurement point, a first primary component of the magnetic induction according to a primary measurement vector
Data Source
AI summary
A sensor system having a permanent magnet for a sensor for determining a relative angular position (Ω(t)), whose magnetization vector (M(P)) at a point (P) presents, in orthogonal projection on a plane perpendicular to its main axis (A′), a projected vector whose relative orientation (φrp(θ(P))) with respect to the particular radial segment (SRP) at this point (P) is a continuously variable function of the angular position (θ(P)) of the point (P), periodic function having an even integer (Np) greater than or equal to 2 of angular periods (T) over the 360° about the main axis (A′), with a positive variation of the relative orientation (φrp(θ(P))) as a function of a positive variation of the angular position (θ(P)) of the point (P); a method implementing such a sensor system; and a method for manufacturing a magnetized body.