Magnetic Structure for Uniform Field Generation
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Solution Overview
Problem
Magnetic field direction sensors, such as anisotropic magnetoresistive (AMR) sensors, face errors and performance degradation due to non-uniform and stray magnetic fields, which are challenging to control and concentrate for precise angular displacement measurements.
Innovation Solution
A rotatable housing with magnetic redirecting materials and strategically positioned magnets with parallel and opposing polarity, along with inserts, is used to generate a uniform magnetic field within a specific region, minimizing stray fields and enhancing field parallelism and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If magnets are positioned close to the sensor to generate sufficient magnetic field strength, then the magnetic field strength is improved, but magnetic field uniformity deteriorates due to stray fields and non-parallel field lines
Solution Approach 1:
A non-magnetic insert is introduced between the magnets and the sensor to modify the magnetic field distribution. This intermediary component helps to straighten magnetic field lines and reduce stray fields, achieving both sufficient field strength and improved uniformity in the gap region where the sensor is positioned.
Solution Approach 2:
The magnetic structure is designed with different regions having different properties: the insert is positioned specifically in the gap region to create locally optimized field conditions. The insert's geometry and material properties are tailored to affect only the local field distribution in the sensor region, leaving other areas unaffected.
2Object-affected harmful factors
If a complex magnetic shielding structure is used to reduce stray fields, then stray field interference is reduced, but device complexity increases
Solution Approach 1:
Instead of using complex magnetic shielding materials or multiple shielding layers, a simple non-magnetic insert is used as an intermediary to control stray fields. This insert passively modifies the field distribution through its geometry and position, achieving stray field reduction without adding structural complexity.
Solution Approach 2:
The harmful stray fields are not blocked by additional shielding components but are instead redirected and contained by removing unnecessary magnetic path elements. The design extracts only the essential magnetic field-generating components (the two magnets) and uses the insert to manage field distribution, eliminating complex shielding structures.
3Area of stationary object
If the magnetic field region is expanded to cover a larger area, then the coverage area is improved, but magnetic field uniformity deteriorates
Solution Approach 1:
The insert is designed to create a localized region of improved field uniformity in the gap area where the sensor is positioned. By concentrating the field-uniforming effect in this specific local region, the design achieves both adequate coverage area and high uniformity where it matters most for sensor operation.
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 robust, scalable, and compact magnetic structure that maintains high accuracy and immunity to errors, suitable for various applications including automotive and industrial uses, with improved temperature stability and reduced angular errors.
Implementation Method 1
a first magnetic redirecting material... the second wall comprising the first magnetic redirecting material... the housing alters a magnetic field of the at least two magnets
Implementation Method 2
at least two magnets positioned within the rotatable housing between the first and second walls... the at least two magnets comprise a first pair of magnets magnetized parallel and opposite to one another
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Apparatus and methods for generating a uniform magnetic field are provided herein. In certain configurations, a magnetic structure (400) includes one or more pairs of magnets (410A, 410B) positioned within a housing (325). The magnets of each pair are arranged in parallel and include poles that are reversed in polarity relative to one another. For example, in certain implementations, a first pair of magnets includes a first magnet (410A) and a second magnet (410B) arranged side by side, with a north pole of the first magnet adjacent a south pole of the second magnet and with a south pole of the first magnet adjacent a north pole of the second magnet. The housing is implemented using a magnetic redirecting material, which can confine magnetic flux and reduce stray magnetic fields. The magnetic structure can be used to generate a magnetic field that is substantially uniform in a region of interest.