Magnetic Rotary Encoder Central Field Space Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotary encoders with single two-pole permanent magnets suffer from weak, non-homogeneous, and non-linear leakage fields, leading to increased noise and susceptibility to interference, which limits their ability to provide strong and homogeneous magnetic fields for fine position value measurement.
Innovation Solution
The arrangement of two permanent magnets with aligned magnetization vectors, either perpendicular or parallel to the axis of rotation, creates a central field space with enhanced field strength and homogeneity, allowing for improved fine resolution and revolution counting capabilities, and the use of a ferromagnetic deflection body or shaft to maintain sinusoidal field dependency without hysteresis effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single two-pole permanent magnet is used, then the structure is simple, but the magnetic field strength is weak and non-homogeneous
Solution Approach 1:
The single permanent magnet is divided into two separate permanent magnets with opposite polarity arrangements. Each magnet generates its own magnetic field, and their combination in the central field space creates a stronger, more homogeneous magnetic field suitable for fine position measurement while maintaining reasonable structural complexity
Solution Approach 2:
The magnetic fields from two permanent magnets are combined in the central field space between them. The opposite polarity arrangement causes the fields to reinforce each other in the central region, creating a homogeneous magnetic field with increased strength that overcomes the limitations of a single magnet
2Device complexity
If a single two-pole permanent magnet is used, then the device is simple, but the magnetic field homogeneity is poor
Solution Approach 1:
Dividing the magnetic field generation into two separate permanent magnets allows each to contribute to a more uniform field distribution in the central space, creating a homogeneous magnetic field environment necessary for precise angle measurement
Solution Approach 2:
The opposite polarity arrangement of the two permanent magnets creates a symmetric magnetic field pattern in the central field space, which produces the desired homogeneity for accurate sensor operation
3Device complexity
If a single two-pole permanent magnet is used, then the structure is simple, but the magnetic field linearity is poor
Solution Approach 1:
The segmentation into two permanent magnets with opposite polarities creates a magnetic field distribution in the central field space that exhibits improved linearity with respect to rotational angle, enabling more accurate fine position measurements
Solution Approach 2:
By changing the polarity arrangement parameter from a single magnet configuration to an opposite polarity two-magnet configuration, the magnetic field characteristics are optimized to provide better linearity for angle measurement applications
4Device complexity
If weak leakage fields are used, then the permanent magnet structure is simple, but noise increases due to high electrical amplification
Solution Approach 1:
Combining the magnetic fields from two permanent magnets creates a stronger magnetic field in the central field space, which reduces the need for high electrical amplification and thereby decreases the noise generated by the amplification process
5Device complexity
If weak magnetic fields are used, then the permanent magnet structure is simple, but susceptibility to interference fields increases
Solution Approach 1:
The merging of magnetic fields from two permanent magnets produces a stronger magnetic field that is more resistant to external interference fields, reducing the susceptibility to disturbances while maintaining a relatively simple permanent magnet structure
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
This configuration provides a stronger, more homogeneous magnetic field for improved fine resolution and revolution counting, reducing noise and interference susceptibility, while allowing for a smaller encoder diameter and efficient energy harvesting from kinetic energy for multiturn applications.
Implementation Method 1
two permanent magnets (7, 7) whose magnetization vectors (21, 21) extending through their respective center of gravity extend in the same direction in relation to common field lines form a central field space (9) in which there is a magnetic field (10)
Implementation Method 2
four-quadrant Hall probe whose Hall elements are connected in crossed relationship
Implementation Method 3
a ferromagnetic deflection body which rotates with the exciter unit and which draws substantial parts of the field out of the central field space and in so doing deforms same that the field lines in question pass through the active surface or surfaces of the fine resolution sensor unit with a perpendicular component
Data Source
AI summary
A magnetic rotary encoder for the fine resolution of the rotational angle of a shaft (1) includes an exciter unit which images the rotation to be monitored and rotates about an axis of rotation (20), a stationary fine resolution sensor unit (2) for fine resolution of each revolution, and an electronic processing means. It is characterized in that the exciter unit includes two first permanent magnets (7, 7) which are disposed symmetrically with respect to the axis of rotation at a mutual spacing such that their magnetization vectors (21, 21) which extend through their respective center of gravity extend in the same direction in relation to the common field lines and form a central field space (9) which directly connects the permanent magnets, and at least the fine resolution sensor unit is so arranged that it can use the field (10) of the central field space for measurement.