Milk Conveying Channel Sensing for Empty Detection in Beverage Machines

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Solution Overview

Problem

Existing beverage preparation devices, such as coffee machines, lack effective and inexpensive methods to detect when milk is running low or empty, leading to potential contamination and inefficient operation.

Innovation Solution

A device with a detection unit and sensor system integrated into the milk conveying channel that detects changes in flow status, allowing for automatic notification or reaction when milk is depleted, using non-contact methods such as piezoelectric, capacitive, or optical sensors to determine the presence of air or steam instead of milk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If weight-based monitoring is used to detect milk empty status, then detection reliability is improved, but device complexity and cost increase due to additional weighing mechanisms

Engineering Contradiction:
Improvemilk empty detection reliabilityVSAvoidmonitoring system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical weighing systems with optical sensing. A light source and light receiver are positioned on opposite sides of the milk container wall, detecting changes in light transmission as milk level decreases. This substitution eliminates complex mechanical weighing mechanisms while maintaining reliable empty detection through optical property changes of the milk-container system.

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

2Measurement precision

If ultrasound-based fill level measurement is used, then measurement precision is improved, but device cost increases significantly

Engineering Contradiction:
Improvefill level measurement precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs inexpensive optical components (LED light source and photodetector) instead of costly ultrasound sensors. These simple optical sensors provide sufficient measurement precision for milk level detection while dramatically reducing manufacturing costs. The system accepts that these components are consumable and may require periodic replacement, prioritizing low initial cost over long component lifespan.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If contact-based sensors are used to detect milk flow status, then detection accuracy is improved, but contamination risk increases

Engineering Contradiction:
Improveflow status detection accuracyVSAvoidoperator and machine contamination
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces the milk container wall as an intermediary medium. Optical sensors are positioned outside the container, detecting light transmission changes through the wall as milk level changes. This intermediary approach allows accurate flow and level detection without physical contact between sensors and milk, eliminating contamination risks while maintaining measurement precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Device complexity

If no milk storage monitoring is implemented, then device complexity is reduced, but harmful effects occur including milk spurtout and contamination

Engineering Contradiction:
Improvemonitoring system complexityVSAvoidmilk spurtout and contamination
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a self-monitoring system where the milk container itself participates in the detection process. Changes in the container's optical properties (light transmission, reflection) as milk is consumed provide automatic feedback about milk status. This self-service approach enables harmful factor prevention through simple optical detection without complex external monitoring systems.

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

Enables timely detection of milk depletion without contacting the milk, preventing contamination and ensuring continuous operation, while being cost-effective and easy to integrate into existing machines.

Implementation Method 1

the sensor (6) is designed as a piezoelectric sensor

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the sensor (7) is designed as a capacitive sensor

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Implementation Method 3

the sensor (10) is designed as an optical sensor

Methodology Applied
Scientific EffectOptical detection: Light

Implementation Method 4

a Venturi nozzle (20) is integrated into the conveying channel (2)

Methodology Applied
Scientific EffectVenturi effect: Venturi Effect

Data Source

PatentEP2628421B1Device for preparing a beverage containing milk with emptiness detection and method for same
Publication Date: 2014.12.10 WMF WURTTEMBERGISCHE METALLWARENFABRIK AG
  • EP2628421B1 patent drawingFigure 1
  • EP2628421B1 patent drawingFigure 2a
  • EP2628421B1 patent drawingFigure 2b

AI summary

The apparatus has milk conveying device (1) with conveying channel (2) whose one end is provided with outlet (3) for discharging the milk (M) into external collecting vessel (S). A sensing element (6,7,10) is provided with detection unit (4) that is provided to detect the change in filling and/or flow condition of the milk in the conveying channel, and detect transition from conveying milk towards conveyance of steam (D) and/or air (L) for predetermined time. An independent claim is included for method for preparing milk-containing beverage.