Milk Frothing Airflow Limiting for Steam Pressure Variations

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Solution Overview

Problem

Existing milk frothing systems face issues with inconsistent milk froth results due to deviations in steam pressure caused by heating hysteresis in steam boilers, leading to disproportionate air delivery from compressed air sources, which affects the quality and reproducibility of milk foam, especially in high-quality coffee machines.

Innovation Solution

A frothing device with an air volume limiting device that regulates air supply based on steam pressure, using mechanisms like variable-area diaphragms or spring-loaded cone valves to ensure optimal air delivery, thereby compensating for hysteresis effects and maintaining consistent milk foam quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a compressed air source is used with fixed back pressure matching, then the system is simple in structure, but the air delivery becomes disproportionate when steam pressure deviates due to heating hysteresis, leading to inconsistent milk froth quality

Engineering Contradiction:
Improvesystem structureVSAvoidmilk froth quality consistency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the air volume limiting device responds to steam pressure variations. The device automatically adjusts air delivery based on the actual steam pressure conditions, creating a closed-loop control system that compensates for heating hysteresis effects and maintains consistent milk froth quality without requiring complex external control systems.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The air volume limiting device is designed to self-regulate based on steam pressure conditions. It automatically adapts its air delivery without requiring external control signals or complex automation, allowing the system to self-correct for pressure deviations and maintain optimal frothing conditions through inherent pressure-dependent operation.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If the compressed air source is adjusted to a defined back pressure, then the system operates simply, but it delivers too much air when steam pressure is low and too little air when steam pressure is high, affecting froth results

Engineering Contradiction:
Improveoperation simplicityVSAvoidair delivery precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent changes the operating parameters of the air volume limiting device based on steam pressure conditions. The device automatically adjusts its air delivery characteristics in response to varying steam pressure, enabling precise air control that adapts to different operating conditions while maintaining simple operation without requiring manual adjustment or complex control systems.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If heating hysteresis is present in the steam boiler, then the system is simple to operate, but the actual steam pressure deviates from nominal pressure, causing disproportionate air delivery

Engineering Contradiction:
Improvesystem implementationVSAvoidsteam pressure accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The air volume limiting device acts as an intermediary between the steam pressure source and the air delivery system. It mediates the relationship by automatically adjusting air delivery based on actual steam pressure conditions, compensating for pressure deviations caused by heating hysteresis without requiring complex control systems or precise pressure measurement devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 provides cost-effective and reliable regulation of air volume, ensuring consistent and high-quality milk foam production by directly responding to steam pressure fluctuations, eliminating the need for complex control devices and improving reproducibility of milk froth results.

Implementation Method 1

the negative pressure on the suction side of the compressed air source, for example an air pump, varies when the vapor pressure on the pressure side of the compressed air source changes

Methodology Applied
Scientific EffectNegative pressure variation: Pressure Drop

Implementation Method 2

If the steam pressure in the steam supply line is comparatively high and above the nominal pressure, the air volume limiting device is actuated in such a way that, if it is designed as a variable-area diaphragm, it opens the diaphragm at least slightly

Methodology Applied
Scientific EffectPressure-dependent actuation: Pressure Drop

Data Source

PatentEP2526840B1Foaming device
Publication Date: 2015.01.21 WMF WURTTEMBERGISCHE METALLWARENFABRIK AG
  • EP2526840B1 patent drawingFigure 1~2
  • EP2526840B1 patent drawingFigure 3~4

AI summary

The milk frothing device (1) has steam feed line (2), air supply line (3), milk supply line (4) and mixing region (5). The air supply pipe connected with steam feed pipe is inserted into mixing region. A compressed air source (6) is provided in one region of ??air supply line for blowing the air. An airflow-limiting device (8) is provided in upstream of compressed air source to regulate the air blowing in the air supply line based on pressure prevailing in the steam feed pipe. The airflow-limiting device has diaphragm made of sintered metal or ceramic. USE : Milk frothing device of coffee machine (claimed). ADVANTAGE : The automatic and inexpensive control of supplied amount of air is achieved so that operation of milk frothing device is enhanced. High quality milk froth is produced so that high quality of coffee machine is ensured. DESCRIPTION OF DRAWINGS : The drawings show the sectional views of the milk frothing device and airflow-limiting device. 1 : Milk frothing device 2 : Steam feed line 3 : Air supply line 4 : Milk supply line 5 : Mixing region 6 : Compressed air source 8 : Airflow-limiting device.