Drop Generator Layout for Fine Mist Without Large Droplet Stains

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional mist generators in household appliances produce a range of droplet sizes, leading to large drops that cause stains and inefficient cleaning due to their size distribution.

Innovation Solution

The solution involves extending the path to the liquid droplet outlet in a household appliance, allowing larger droplets to sink due to gravity while smaller droplets are held in the air by Stokes' friction, ensuring only specific-sized droplets reach the outlet, thus generating a finer mist. This is achieved by adjusting the distance between the flow container and the droplet outlet to match the transport time of droplets with their descent time, using a piezoelectric oscillator for droplet generation, and incorporating a mechanical filter and obstacle device to further select and redirect larger droplets back into the container.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional mist generators are used to generate liquid droplets, then a range of droplet sizes is produced, but large droplets are reflected in the operation on sight glasses and material, leaving liquid stains

Engineering Contradiction:
Improvedroplet size distributionVSAvoidliquid stains on sight glass and material
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The invention segments the droplet population by size through gravitational separation. The flow container is designed with a specific geometry where larger droplets settle to the bottom while smaller droplets remain suspended and are conveyed to the outlet, effectively segmenting the droplet size distribution to eliminate staining-causing large droplets

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces a vertical dimension for droplet separation within the flow container. By creating a vertical flow path and utilizing gravity in the vertical direction, droplets are separated by size before horizontal conveyance to the outlet, adding a dimensional aspect to the droplet size control mechanism

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the path length between flow container area and liquid droplet outlet is increased to allow larger droplets to sink, then droplet size is reduced and mist quality is improved, but transport time is increased

Engineering Contradiction:
Improvedroplet size uniformityVSAvoidtransport time of liquid droplets
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The invention optimizes the geometric parameters of the flow container, specifically the ratio of width to height, to achieve effective droplet separation within a minimized transport distance. By carefully selecting these parameters, the container enables gravitational settling of large droplets while maintaining a compact overall size and short transport path to the outlet

Inventive Principle:
Principle #35Parameter changes

3Productivity

If a flow generator is used to convey liquid droplets to the outlet, then droplet transport is enabled, but energy consumption increases

Engineering Contradiction:
Improvedroplet conveyance efficiencyVSAvoidenergy consumption of flow generator
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The flow container design enables self-service droplet separation through its geometric configuration. The container's width-to-height ratio creates natural gravitational settling zones where large droplets automatically separate without requiring external energy input, while the overall compact design minimizes the energy needed for any necessary active flow generation

Inventive Principle:
Principle #25Self-service

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

This approach results in a more homogeneous and efficient mist distribution, reducing liquid consumption and extending refill intervals, with improved visibility and moistening of treated materials, as only droplets within a specific size range (1-10 μm) are delivered, enhancing cleaning efficiency.

Implementation Method 1

a droplet generator (105) arranged on the flow container (103) for generating liquid droplets (107) from a liquid (109)

Methodology Applied
Scientific EffectPiezoelectric oscillation: Piezoelectric Effect

Implementation Method 2

larger liquid droplets do not reach the liquid droplet outlet (111) because they sink beforehand due to gravitation

Methodology Applied
Scientific EffectGravitation: Gravitation

Implementation Method 3

only droplets of a specific size or with a specific maximum radius reach the liquid droplet outlet (111), since these are also held longer in the air by the effect of Stokes' friction

Methodology Applied
Scientific EffectStokes' friction: Stokes Drift

Data Source

PatentEP3171750B1Domestic appliance having a drop generator
Publication Date: 2019.04.17 BSH HAUSGERATE GMBH
  • EP3171750B1 patent drawingFigure 1~2
  • EP3171750B1 patent drawingFigure 3a~3b

AI summary

The invention relates to a domestic appliance, comprising a flow container (103), a drop generator (105) arranged on the flow container (103) for generating liquid drops (107) from a liquid (109) in a flow container region (121) of the flow container (103), a liquid drop outlet (111), and a flow generator (113) arranged opposite the liquid drop outlet (111) for generating an air flow for conveying the liquid drops (107) to the liquid drop outlet (111), wherein a distance (201) between the flow container region (121) and the liquid drop outlet (111) is selected in such a way that a first time span of the conveyance of liquid drops (107) between the flow container region (121) and the liquid drop outlet (111) is equal to or greater than a second time span of the falling of a liquid drop (107) of a predetermined drop size along a predetermined falling route.