Rotary Encoder Generator with Segmented Magnets for Clean Pulses
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Solution Overview
Problem
Conventional rotary encoders with autonomous power supply face issues of unwanted pre- and post-pulses at high rotational speeds, and require a small air gap to differentiate voltage pulses, which is insufficient in the presence of axial offsets.
Innovation Solution
A rotary encoder design featuring magnet segments with seamless transitions in polarity, a magnetically conductive spring element, and a coil, generating a time-varying magnetic field to induce voltage, allowing for a larger air gap and reducing undesired pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If block magnets are used to generate voltage pulses for autonomous power supply, then the rotary encoder can operate without external power, but unwanted pre- and post-pulses are generated at high rotational speeds
Solution Approach 1:
The magnet is divided into multiple segments along the circumferential direction, with each segment having a specific polarity arrangement. This segmentation creates distinct magnetic field zones that generate clean voltage pulses without the overlapping fields that cause pre- and post-pulses in conventional block magnet designs.
Solution Approach 2:
Different regions of the magnet structure are assigned different polarities (N and S poles alternating in specific patterns). This local differentiation of magnetic properties ensures that voltage pulses are generated only at intended transition points, eliminating unwanted pulses while maintaining autonomous power supply capability.
2Power
If a small air gap is selected to generate high-level voltage pulses, then the desired voltage pulse level is sufficient, but the device becomes sensitive to axial offsets between the drive shaft and generator
Solution Approach 1:
The segmented magnet structure creates multiple localized magnetic field interactions across the air gap. This segmentation allows for a larger overall air gap while maintaining sufficient voltage pulse levels through the cumulative effect of multiple segment interactions, thereby reducing sensitivity to axial misalignment.
Solution Approach 2:
The invention changes the magnetic field distribution parameters by using alternating polarities in segmented arrangements. This parameter change allows optimization of the air gap size to achieve both sufficient voltage pulse levels and increased tolerance to axial offsets, resolving the trade-off between power output and mechanical tolerance.
3Reliability
If adjacent magnet segments with different polarity have seamless transition, then only desired main pulses are generated, but the manufacturing complexity increases
Solution Approach 1:
The magnet is designed as separable segments that can be manufactured independently and then assembled. This segmentation enables precise control of polarity transitions at joints while simplifying manufacturing, as each segment can be magnetized separately to standard specifications before assembly, reducing overall manufacturing complexity despite the seamless transition requirement.
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 effectively generates only the desired voltage pulse, avoiding unwanted pre- and post-pulses, and accommodates larger air gaps, enhancing tolerance and efficiency.
Implementation Method 1
the spring element is designed to perform a sudden back-and-forth movement in response to a time-varying magnetic field and to induce a voltage in the coil in order to supply the rotary encoder with energy
Implementation Method 2
a plurality of magnet segments which are arranged adjacent to one another in the circumferential direction and are alternately polarized in order to apply the time-varying magnetic field to the spring element upon rotation of the rotatable shaft
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a rotary encoder (200) for acquiring position and/or motion information of a rotatable shaft (400). The rotary encoder comprises a generator (100) with a carrier body (120, 130), a coil (160) wound around a section of the carrier body, and a magnetically conductive spring element (115), wherein the spring element is configured to perform an abrupt reciprocating movement in response to a time-varying magnetic field and to induce a voltage in the coil in order to supply energy to the rotary encoder. The rotary encoder further comprises a plurality of magnetic segments (230a-d), wherein the plurality of magnetic segments are arranged adjacent to one another in the direction of rotation and are alternately polarized in order to subject the spring element to the time-varying magnetic field due to rotation of the rotatable shaft.