Counter-Rotating Rollers for Viscous Fluid Droplet Control

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Solution Overview

Problem

Conventional spray deposition systems face difficulties in creating small, controlled volumes of droplets from highly viscous and non-Newtonian fluids due to their shear thinning or strong extensional thickening properties, which delay capillary instability and droplet formation.

Innovation Solution

A controlled-volume spray deposition system using bi-directional, counter-rotating rollers to stretch fluid filaments beyond their capillary break-up point, forming small, controlled droplets without the need for pressurized air, by rotating in one direction to dispense and retract in another, allowing precise control over droplet size and volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional spray deposition systems use highly pressurized air to generate droplets of highly viscous fluids, then droplet formation is assisted, but the systems have difficulties in creating small quantities and controlled dosing of droplets

Engineering Contradiction:

Improvedroplet generationVSAvoiddroplet volume control

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the pneumatic system (highly pressurized air) with a mechanical system (counter-rotating rollers) to generate droplets. The rollers mechanically stretch and break the fluid filament, providing direct mechanical control over droplet formation and volume, thereby achieving both ease of operation and precise volume control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent controls droplet volume by changing the operational parameters of the rollers, specifically the rotation speed and the gap between rollers. By adjusting these parameters, the system can precisely control the amount of fluid stretched and broken into droplets, achieving controlled dosing while maintaining ease of operation.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If diverging surface-type spray deposition systems are used to atomize highly viscous and non-Newtonian fluids, then large volumes of spray droplets are produced, but the systems produce large volumes rather than small controlled quantities

Engineering Contradiction:

Improvespray droplet productionVSAvoiddroplet volume control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent employs dynamically adjustable roller rotation speeds and gap distances to control droplet production. By varying these dynamic parameters, the system can produce either small or large volumes of droplets as needed, while maintaining precise control over droplet size and volume, thus resolving the contradiction between productivity and manufacturing precision.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If highly viscous and non-Newtonian fluids are subjected to shear thinning or strong extensional thickening properties, then capillary instability is delayed, but droplet formation becomes difficult

Engineering Contradiction:

Improvefluid rheologyVSAvoiddroplet formation

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary stretching action to the fluid between the counter-rotating rollers before droplet break-up occurs. This preliminary mechanical extension overcomes the fluid's resistance to capillary instability caused by shear thinning or extensional thickening properties, facilitating droplet formation while respecting the fluid's rheological characteristics.

Inventive Principle:

Principle #10Preliminary action

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 the formation of small, controlled droplets from highly viscous and non-Newtonian fluids, simplifying the atomization process and broadening applications by using purely mechanical means to control droplet size and volume, effectively addressing the challenges of conventional systems.

Implementation Method 1

the applied strain or continuous stretching to the fluid filaments causes them to stretch until beyond the point at which the fluid filament break up from capillary forces, meaning the fluid filaments exceed their capillary break-up point and break into droplets

Methodology Applied

Scientific EffectCapillary instability: Capillary Pressure

Data Source

PatentUS10562059B2Devices and methods for the controlled formation and dispension of small drops of highly viscous and/or non-newtonian liquids

Publication Date: 2020.02.18 XEROX CORP

AI summary

A controlled-volume spray deposition system has a fluid feed system including a pair of bi-directional, counter-rotating rollers to dispense fluid as a first surface, the rollers operable to rotate in a first direction to dispense the fluid, a second surface positioned to receive the fluid when the rollers rotate in the first direction, and the rollers operable to rotate in a second direction to retract the fluid to cause the fluid to stretch and form a filament until it breaks to form a spray. A method of generating a controlled-volume spray includes feeding fluid between two counter-rotating rollers as a first surface as they rotate in a first direction until the fluid contacts a second surface, reversing the counter-rotating rollers such that they pull the fluid to form a fluid filament, and causing the filament to break into a spray.