Friction Stirrer Surface Angle for High-Viscosity Mixing

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Solution Overview

Problem

Magnetic stirrers are limited in their ability to effectively stir high-viscosity liquids due to high resistance forces, which prevent the stirrer from initiating rotation and maintaining movement.

Innovation Solution

A magnetic stirrer with a base body featuring a friction stirring surface that forms a small angle with the direction of rotation, utilizing fluid friction to introduce stirring energy, allowing the stirrer to start rotating easily and increase energy input as speed increases, with a design that minimizes initial resistance and includes features like vertical passage openings and magnetic shielding for stability and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a traditional magnetic stirring bar is used, then it can stir low-viscosity liquids, but it cannot effectively stir high-viscosity liquids due to high resistance forces preventing rotation initiation

Engineering Contradiction:
Improveviscosity rangeVSAvoidrotation initiation
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The invention changes the geometric parameter of the stirring surface by using a friction stirring surface forming a small angle (less than 15°) with the direction of rotation. This parameter change reduces the initial resistance force, enabling rotation initiation in high-viscosity liquids while maintaining stirring capability across a wide viscosity range

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces the traditional mechanical thrust stirring mechanism with a friction-based stirring mechanism. Instead of relying on direct mechanical pushing against the liquid, the friction stirring surface utilizes fluid friction to transmit stirring energy, which reduces starting resistance and improves ease of operation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a magnetic stirring bar is designed to overcome high resistance in viscous liquids, then it can maintain rotation, but it cannot start moving from the stationary position

Engineering Contradiction:
Improvestirring performanceVSAvoidstarting behavior
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

By changing the geometric parameter of the stirring surface angle to less than 15°, the invention creates a design where the initial resistance force is minimized. This allows the magnetic stirrer to start rotating easily from the stationary position while the same geometric configuration ensures reliable stirring performance during operation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The friction stirring surface is designed in advance with a specific small angle configuration that pre-establishes favorable starting conditions. This preliminary design ensures that when the magnetic field begins rotating, the stirrer can immediately start moving without overcoming excessive initial resistance, while maintaining reliable stirring once in motion

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If a friction stirring surface with a small angle is used, then the initial resistance is reduced, but the stirring energy input must occur at higher rotational speeds

Engineering Contradiction:
Improvestarting resistanceVSAvoidrotational speed for energy input
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

The invention accepts the parameter trade-off where the friction stirring surface angle is set to less than 15°, which reduces initial resistance and improves ease of operation. The small angle design inherently requires higher rotational speeds to generate sufficient fluid friction for stirring energy input, but this is acceptable since the stirrer can now start rotating easily in the first place

Inventive Principle:
Principle #35Parameter changes

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 efficient stirring of high-viscosity liquids by reducing initial resistance and ensuring the stirrer can start and maintain rotation, with increased fluid friction at higher speeds, effectively overcoming the limitations of traditional magnetic stirrers.

Implementation Method 1

The magnetic bodies are designed for magnetic coupling to a magnetic drive of the magnetic stirring device

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

the base body has at least one friction stirring surface for the transmission of stirring energy to a liquid to be stirred by means of fluid friction

Methodology Applied
Scientific EffectFluid friction: Friction

Data Source

PatentEP3175912B1Magnetic stirrer for a magnetic stirrer device
Publication Date: 2020.08.05 2MAG
  • EP3175912B1 patent drawingFigure 1
  • EP3175912B1 patent drawingFigure 2
  • EP3175912B1 patent drawingFigure 3

AI summary

The present invention relates to a magnetic stirrer (10) for a magnetic stirring device (100), comprising a base body (20) with an axis of rotation (RA) and at least two magnetic bodies (30) for magnetic coupling with a magnetic drive (110) of the magnetic stirring device (100), wherein the base body (20) has at least one friction stirring surface (22) for the transfer of stirring energy to a liquid (210) to be stirred by means of fluid friction, wherein the at least one friction stirring surface (22) forms a stirring angle of less than 15° with a direction of rotation (RR) about the axis of rotation (RA).