Electromagnetic Stirring Apparatus with Air Core Coils
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Solution Overview
Problem
Existing magnetic stirring devices for liquids in vials are unreliable due to short motor life and inconsistent magnetic field distribution, which affects stirring efficiency and vial capacity in autosamplers.
Innovation Solution
An electronic magnetic stirring apparatus that generates rotating magnetic fields using air core coils and pole standoffs to provide a consistent magnetic field strength to each vial, allowing for independent stirring of multiple vials with improved reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motors with magnets are used to stir vials, then stirring function is achieved, but motor life is short (about 2000 hours)
Solution Approach 1:
The patent replaces the mechanical motor-magnet system with an electromagnetic system consisting of coils and pole shoes. The coils generate magnetic fields that interact with permanent magnets in the stir bars, eliminating mechanical moving parts and extending operational life beyond 8000 hours of continuous use.
Solution Approach 2:
The electromagnetic stirring system allows the coils to generate magnetic fields on-demand without mechanical wear. The system serves itself by using electrical energy to create the necessary magnetic fields, with no mechanical components to degrade over time.
2Quantity of substance
If pole shoes are placed on top of coils to direct shared magnetic field under multiple vials, then vial capacity increases, but magnetic field strength becomes inconsistent across vials
Solution Approach 1:
The patent divides the magnetic field generation into separate, independently controlled coil assemblies for each vial position. Each coil-pole shoe-stir bar combination forms an independent magnetic circuit, ensuring consistent field strength across multiple vials while maximizing vial density on the plate.
Solution Approach 2:
The design provides localized magnetic field generation at each vial position through individual coil assemblies. Each location has its own optimized magnetic circuit with pole shoes positioned to create uniform field distribution specifically for that vial, ensuring consistent stirring performance across all positions.
3Reliability
If magnets are placed between target vials, then stirring is achieved, but the number of vials that can be placed in a given area decreases
Solution Approach 1:
The patent transitions from placing magnets between vials (horizontal arrangement) to placing pole shoes above coils beneath each vial (vertical arrangement). This dimensional change allows magnets to be positioned directly under each vial without occupying horizontal space between vials, thereby maximizing vial placement density while maintaining reliable stirring function.
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 ensures reliable and consistent stirring of samples in multiple vials, extending motor life and increasing vial capacity, making it suitable for high-use autosamplers with reduced power consumption and improved stirring action.
Implementation Method 1
The stirring apparatus is an electronic design that generates rotating magnetic fields to drive magnetic stir bars within vials placed above the cover of the stirring apparatus
Implementation Method 2
The cover contains an array of pole standoffs that matches the coil pattern. The hollow center of each air core coil contains at least a portion of one pole standoff. The heads of the pole standoffs extend through the cover and are flush with the top surface of the cover.
Data Source
AI summary
The stirring apparatus is an electronic design that generates rotating magnetic fields to drive magnetic stir bars within vials placed above the cover of the stirring apparatus. Below the cover is a magnetics board containing multiple vial groups of four air core coils arranged in rectangular patterns. Each vial group has with two pairs of diagonal coils. The coils in each pair are wired in series and have opposite winding directions. Each pair is driven by a different phase of a stepper motor driver. The vial groups are spaced appropriately for placing one vial above each group. The adjacent coils of adjacent vial groups are driven by the same phase and have the same magnetic direction. The cover contains an array of pole standoffs that matches the coil pattern. The hollow center of each air core coil contains at least a portion of one pole standoff.