Helical Magnetic Poles for Pitched Sensor Position Encoding
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Solution Overview
Problem
Existing rotary magnetic encoders with limited pole counts and magnet diameters are not practical for use with pitched magnetic sensors, limiting their effectiveness in detecting rotational motion and position.
Innovation Solution
A magnetic encoder system featuring a rotor with elongate north and south magnetic poles arranged helically around its exterior, allowing for a flexible pole count and magnet diameter, and utilizing pitched Hall sensors to detect the magnetic fields, enabling efficient detection of rotational and axial movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional rotary magnetic encoders with limited pole counts are used, then the encoder can detect rotational motion, but the resolution and flexibility in detecting rotational and axial movements are limited
Solution Approach 1:
The patent transitions from traditional two-dimensional magnetic pole arrangements (circumferential only) to a three-dimensional helical arrangement that extends axially. The magnetic poles are configured in a helix pattern around the rotor shaft, allowing the magnetic field to vary in both circumferential and axial directions. This dimensional extension enables simultaneous detection of rotational and axial movements with a single sensor, significantly improving measurement precision and flexibility without requiring multiple sensors or complex pole configurations.
Solution Approach 2:
The patent employs a dynamic helical magnetic pole configuration where the pole arrangement can be adjusted or optimized for different detection requirements. The helical pitch and pole distribution can be varied to achieve different detection resolutions and ranges for rotational and axial movements. This dynamic configurability allows the encoder to adapt to various application requirements, improving versatility while maintaining high measurement precision.
2Measurement precision
If multiple sensors are used to detect both rotational and axial movements, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal magnetic encoder system where a single pitched magnetic sensor performs multiple functions: detecting both rotational position and axial position simultaneously. The helical magnetic pole configuration ensures that the magnetic field varies in a predictable pattern for both rotational and axial movements, allowing one sensor to extract both types of information through signal processing. This eliminates the need for separate sensor arrays for rotational and axial detection, significantly reducing device complexity while maintaining enhanced detection capability.
Solution Approach 2:
The patent merges the detection of rotational and axial movements into a single integrated sensing system. By combining the helical magnetic pole structure with a single pitched magnetic sensor, the system consolidates what would traditionally require multiple sensors into one compact unit. The sensor detects the combined magnetic field variations caused by both rotational and axial movements, and signal processing separates these components to provide both position measurements simultaneously.
3Ease of operation
If traditional magnetic encoders are positioned on-axis, then detection is straightforward, but application range is limited
Solution Approach 1:
The patent utilizes an asymmetric helical magnetic pole configuration that is inherently suited for off-axis sensor positioning. Unlike traditional symmetric radial pole arrangements that require on-axis sensors for optimal performance, the helical pattern creates a magnetic field distribution that maintains detection capability at off-axis positions. The asymmetric geometry of the helical poles ensures that the magnetic field varies appropriately for both rotational and axial detection even when the sensor is positioned offset from the rotor center, expanding application range while maintaining operational simplicity.
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 enhanced resolution and flexibility in detecting rotational and axial movements, allowing for dual-purpose encoding with a single cycle sine and cosine output, and can be positioned off-axis, expanding its application range.
Implementation Method 1
Hall effect sensors (also referred to herein as Hall sensors or Hall devices) are magnetic sensors that work by detecting a change in voltage by magnetic deflection of electrons
Data Source
AI summary
A position encoder comprising a cylindrical rotor; first and second magnetic poles having opposite polarity helically disposed about the inner or outer diameter of the rotor; first and second Hall sensors disposed within a distance suitable for the Hall sensors to detect the magnet poles.