Rotary Sensor Segmented Magnet Arrangement
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Solution Overview
Problem
Conventional rotary sensors face challenges in achieving compact size while maintaining high measuring accuracy and robustness against external magnetic fields and mechanical vibrations, with ring magnets requiring large sizes and complex magnetization processes.
Innovation Solution
A rotary sensor design utilizing distinct, spatially separate permanent magnets arranged circumferentially about a rotation axis, with each magnet having parallel magnetization and alternating polarities, allowing for a compact configuration that enhances magnetic flux density and robustness against misalignment and external fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional injection molding methods are used to produce ring magnets, then manufacturing simplicity is maintained, but the sensor size increases and magnetization becomes difficult below certain dimensions
Solution Approach 1:
The patent divides the magnet arrangement into at least four distinct and spatially separate permanent magnets arranged circumferentially about the rotation axis. Each magnet can be independently produced and magnetized, avoiding the limitations of conventional ring magnet injection molding. This segmentation enables compact sensor design while maintaining ease of manufacture, as each individual magnet can be produced using standard methods and assembled into the final configuration.
2Volume of moving object
If the ring magnet size is reduced to make the sensor more compact, then sensor compactness improves, but robustness against disturbing magnetic fields deteriorates
Solution Approach 1:
By using multiple separate permanent magnets arranged circumferentially, the patent maintains sufficient magnetic flux density for robustness against external fields while reducing the overall sensor volume. The segmented configuration allows optimal positioning of each magnet to maximize field strength at the sensor location without requiring a large single ring magnet.
Solution Approach 2:
The magnet arrangement uses multiple permanent magnets with specific magnetic properties arranged in a composite configuration. This composite structure creates a magnetic field that is more robust against external disturbances compared to a single magnet of equivalent volume, while enabling compact sensor design.
3Measurement precision
If grooves are added between sectors of the ring magnet to reduce angular position error, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent achieves improved angular position measurement accuracy by using multiple distinct permanent magnets with defined spatial arrangement and alternating polarity. This segmented approach provides inherent magnetic field gradients that reduce sensitivity to radial displacement, eliminating the need for additional grooves or structural modifications while maintaining measurement precision.
4Reliability
If multiple Hall-sensor pairs are used to account for external disturbing magnetic fields, then robustness against external fields improves, but device complexity increases
Solution Approach 1:
The patent uses multiple spatially separate permanent magnets arranged circumferentially to create a magnetic field configuration that is inherently more robust against external disturbing fields. This segmented magnet arrangement provides field reinforcement and stability without requiring additional sensor elements, reducing overall system complexity while maintaining reliability.
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 design achieves improved measurement accuracy and robustness against mechanical vibrations and external magnetic fields, reducing angular deviation due to sensor displacement by up to a factor of 4 compared to conventional ring magnets, while significantly reducing material usage.
Implementation Method 1
a magnet arrangement configured to generate a magnetic field. The magnet arrangement comprises at least four distinct and spatially separate permanent magnets
Implementation Method 2
Hall-sensors may for example be employed for contactless angular measurements... a magnetic field sensor configured and arranged to detect a rotation of the magnetic field
Data Source
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AI summary
A rotary sensor comprising a magnet arrangement (20) is provided. The magnet arrangement is configured to generate a magnetic field and comprises at least two distinct and spatially separate permanent magnets (21-24). The at least two permanent magnets (21-24) are arranged circumferentially about a rotation axis (15) extending in an axial direction, wherein the magnet arrangement (20) is configured to be non-rotatably mounted to a component (50) a rotation of which about the rotation axis is to be measured. The rotary sensor further comprises at least one magnetic field sensor (30) configured and arranged to detect a rotation of the magnetic field generated by the magnet arrangement (20) upon rotation of the magnet arrangement (20).