Rotation Number Detector Using Barkhausen Magnetic Wire
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Solution Overview
Problem
Conventional rotation number detectors experience reduced power generation and reliability when power generation elements are positioned off-center relative to the magnet, leading to decreased detection accuracy and increased thickness due to the need for stacked coils and varying distances from the magnet.
Innovation Solution
A rotation number detector design featuring multiple power generation elements with magnetic wires exhibiting a large Barkhausen effect and pickup coils wound around them, where the magnetic wire is longer than the pickup coil, positioned away from the magnet's center to enhance power generation stability and thinness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the power generation element is positioned near the outer periphery of the magnet to avoid the center, then the detector can be made thinner, but the power generation amount decreases to about 40 percent of the center position
Solution Approach 1:
The patent places multiple power generation elements at different radial positions around the magnet, with inner elements closer to the center and outer elements near the periphery. These elements are nested concentrically, allowing the detector to maintain thinness while capturing power generation from multiple positions simultaneously, thus resolving the contradiction between reduced thickness and sufficient power generation.
2Device complexity
If the power generation element is positioned off-center, then the detector structure is simplified, but the detection reliability decreases due to large power variation with eccentric rotation
Solution Approach 1:
The patent assigns different functional roles to power generation elements at different radial positions. Inner elements experience smaller power variations and provide stable baseline signals, while outer elements generate larger signals but with higher variation. By combining these locally optimized elements, the system achieves both structural simplicity and high detection reliability.
3Adaptability or versatility
If two power generation elements are stacked one on top of the other to achieve 90-degree phase difference, then rotation direction can be determined, but the detector thickness increases by 10 millimeters
Solution Approach 1:
Instead of stacking power generation elements vertically (one dimension), the patent arranges them radially in the horizontal plane around the magnet. This dimensional transition from vertical stacking to radial arrangement enables 90-degree phase difference between elements while maintaining thin detector profile, thus achieving rotation direction detection without increasing thickness.
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 high reliability and flexibility by maintaining stable power generation pulses and reducing detector thickness, allowing for accurate rotation counting and direction determination.
Implementation Method 1
a magnetic wire, in which magnetization reversal occurs due to a large Barkhausen effect
Implementation Method 2
a pickup coil that is wound around the magnetic wire
Data Source
AI summary
A rotation number detector according to an embodiment is a rotation number detector that detects the number of rotations of a magnet attached to a rotating body by using a power generation unit. The power generation unit includes N (N is a natural number equal to or larger than 1) power generation elements, each including a magnetic wire in which magnetization reversal occurs due to a large Barkhausen effect and a pickup coil that is wound around the magnetic wire. The magnetic wire is longer than a wound portion of the pickup coil in an extension direction of the magnetic wire of the power generation elements. The magnetic wire is set above a rotation center of the magnet.