Negative Yarn Feeder Position Detector with Sinusoidal Magnet
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Solution Overview
Problem
Existing negative yarn feeders for textile machines have limited angular position resolution due to the number of magnets on the fly-wheel, high manufacturing costs, and require a zero-search procedure for position measurement, which affects speed control stability and increases positioning time.
Innovation Solution
A position detector with an annular permanent magnet diametrally magnetized and Hall sensors spaced 90° apart, generating sinusoidal voltage signals that allow for continuous position measurement and constant speed signal frequency band, eliminating the need for zero-search procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple magnets are positioned on the fly-wheel to improve angular position resolution, then position measurement precision is improved, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The invention changes the magnetic field distribution parameter from discrete localized magnets to a continuous sinusoidal distribution around the annular magnet. This allows the Hall sensor to detect continuous position information through the sinusoidal variation of magnetic field strength, achieving high resolution without requiring multiple discrete magnets.
Solution Approach 2:
The invention replaces the mechanical system of multiple discrete magnets with a magnetic field-based system using a single annular magnet with sinusoidal magnetization. The position detection is achieved through magnetic field interaction rather than mechanical positioning of multiple components, reducing manufacturing complexity.
2Measurement precision
If multiple magnets are positioned on the fly-wheel to improve angular position resolution, then position measurement precision is improved, but device complexity increases
Solution Approach 1:
The invention transforms the detector from a system requiring multiple discrete magnets and their precise positioning into a system with a single annular magnet and one Hall sensor. The sinusoidal magnetization pattern encodes all position information, simplifying the device structure while maintaining high measurement precision.
3Measurement precision
If zero-search procedure is used to univocally measure position, then position measurement accuracy is improved, but positioning time increases
Solution Approach 1:
The invention performs preliminary action by pre-magnetizing the annular magnet with a sinusoidal distribution pattern before operation. This pre-established magnetic field pattern allows the Hall sensor to immediately determine position from the sinusoidal signal variation, eliminating the need for runtime zero-search procedures and enabling direct absolute position measurement.
4Measurement precision
If time interval measurement between magnet pulses is used to calculate speed, then speed measurement is achieved, but frequency band is limited by rotation speed
Solution Approach 1:
The invention utilizes the periodic sinusoidal variation of the magnetic field as the annular magnet rotates. The Hall sensor detects this periodic signal, and the frequency of the sinusoidal signal directly corresponds to the rotation speed. This allows speed measurement through frequency analysis of the continuous sinusoidal signal rather than time interval measurement between discrete pulses, providing a wider and more stable frequency band for speed control.
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
Enables precise, continuous position control and constant speed feedback without zero-search procedures, improving stability and reducing manufacturing costs by allowing for more flexible and efficient yarn feeding.
Implementation Method 1
a pair of Hall sensors 24, 26 which are arranged near permanent magnet 22 in order to detect the diametral component of the magnetic field generated by the magnet
Data Source
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AI summary
A swivel arm (14), which is operated by a motor (15) driven by a control unit (UC), winds yarn loops forming a weft reserve (RT) on a stationary drum (12). A position detector (20) controls the angular position and the speed of the swivel arm, and comprises an annular permanent magnet (22) which is keyed to the shaft (15a) of the motor and is diametrally magnetized with a sinusoidal distribution of the magnetization. A pair of Hall sensors (24, 26), which are angularly spaced at 90° from each other about the axis of the magnet, are arranged near the magnet for detecting the diametral component of the magnetic field generated by the magnet, and are connected for sending signals to the control unit, which is programmed for calculating the absolute angular position (Ω) of the motor shaft on the basis of the signals from the Hall sensors.