Two-Vessel Milk Frothing Layout for Stable Milk Flow

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Solution Overview

Problem

Existing milk frothing devices in coffee machines suffer from variable milk flow as the milk level decreases, leading to inconsistent proportions of milk, steam, and air in the mixing chamber, which affects proper frothing.

Innovation Solution

A milk frothing device design featuring a containment body with two separate and distinct vessels, where the milk supply conduit is connected to an open-top vessel separate from the air supply conduit, ensuring a constant milk level through real-time refilling, maintaining a consistent proportion of steam, air, and milk in the mixing chamber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single vessel is used for milk containment, then the device structure is simple, but the milk flow varies greatly as the milk level decreases

Engineering Contradiction:
Improvestructure simplicityVSAvoidmilk flow consistency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The containment body is divided into two separate vessels: a first open-top vessel for milk supply and a second closed vessel for real-time refilling. This segmentation allows the system to maintain constant milk level in the first vessel while simplifying the overall structure compared to complex single-vessel level control mechanisms.

Inventive Principle:
Principle #1Segmentation

2Quantity of substance

If the milk level in the containment body decreases, then the available milk volume increases, but the suction head required increases causing variable milk flow

Engineering Contradiction:
Improvemilk volumeVSAvoidmilk flow control
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The second vessel pre-fills the first vessel through connection opening (11) before and during the milk suction process. This preliminary action maintains the milk level in the first vessel at a constant height, ensuring consistent suction head and stable milk flow to the mixing chamber throughout the frothing operation.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If a single vessel design is used, then the device is easier to manufacture, but the proportion of milk in the mixture becomes variable

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmixture proportion consistency
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system separates milk containment (first vessel) from milk refilling (second vessel), allowing each component to be manufactured independently with simple geometries while achieving the complex function of constant proportion mixing through their coordinated operation.

Inventive Principle:
Principle #1Segmentation

4Productivity

If the milk containment body is emptied, then more milk can be processed, but the suction head increases reducing milk flow

Engineering Contradiction:
Improvemilk processing capacityVSAvoidmilk flow stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The second vessel continuously refills the first vessel through connection opening (11) during the entire frothing process. This continuous refilling action maintains constant milk level and stable milk flow throughout the processing of the entire milk quantity in the containment body, enabling sustained productivity without flow instability.

Inventive Principle:
Principle #20Continuity of useful 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

This design ensures a constant milk level in the frothing device, preventing fluctuations in milk flow and maintaining a consistent proportion of milk, steam, and air, resulting in proper frothing of milk.

Implementation Method 1

When the flow of steam is dispensed, thanks to the depression created in the mixing chamber, the milk supply conduit sucks the milk from the milk containment body below

Methodology Applied
Scientific EffectDepression created by steam flow: Pressure Gradient

Implementation Method 2

The mixing body in turn comprises a Venturi-shaped mixing chamber

Methodology Applied
Scientific EffectVenturi effect: Venturi Effect

Data Source

PatentEP3020312B1Device and method for frothing milk
Publication Date: 2019.01.02 DE LONGHI APPLIANCES SRL
  • EP3020312B1 patent drawingFigure 1
  • EP3020312B1 patent drawingFigure 2
  • EP3020312B1 patent drawingFigure 3

AI summary

The frothing device for milk (1) comprises a containment body (2) for the milk and a mixing body (3) in turn comprising a mixing chamber (4), a conduit (5) for supplying the milk to the mixing chamber (4), a conduit (6) for supplying steam to the mixing chamber (4), a conduit (7) for supplying air to the mixing chamber (4), and an outlet conduit (8) for the milk mixed with air and steam from the mixing chamber (4), the milk containment body (2) comprising a first open top vessel (9) in which one end of the milk supply conduit (5) is positioned and a second vessel (10) having a closing ceiling (10a) communicating with the first vessel (9) through a connection opening (11) positioned at a distance from the ceiling (10a).