Method for calibrating a weight sensor arranged on the tank of a beverage dispensing machine

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Solution Overview

Problem

Economical weight sensors in beverage dispensing machines exhibit significant measurement dispersions and require complex and expensive calibration operations, making precise liquid volume measurement challenging throughout the machine's life.

Innovation Solution

A method for calibrating weight sensors in beverage dispensing machines involves filling the reservoir, recording weight sensor values over time intervals, determining slope changes during liquid withdrawal, and identifying intersection points to associate measured values with liquid weights, allowing for simple and economical calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If economical weight sensors (strain gauges) are used in beverage dispensing machines, then cost is reduced, but measurement precision deteriorates due to significant measurement dispersions from one sensor to another and over time

Engineering Contradiction:
ImprovecostVSAvoidmeasurement precision
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by performing calibration operations before the sensor is put into service and cyclically during its duration of use. This pre-calibration and periodic recalibration compensates for the inherent measurement dispersions of economical strain gauge sensors, ensuring accurate liquid volume measurement throughout the machine's life without requiring expensive high-precision sensors.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If calibration operations are performed to obtain accurate weight measurements, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoidcalibration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements self-service by enabling the control system to automatically perform calibration operations using data from the weight sensor and known liquid volumes. The system autonomously determines calibration parameters and adjusts measurements without requiring external calibration equipment or complex manual procedures, thereby maintaining high measurement precision while minimizing calibration complexity and cost.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If calibration operations are performed frequently to maintain accuracy throughout the machine's life, then measurement precision is improved, but loss of time and productivity decrease

Engineering Contradiction:
Improvemeasurement precisionVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies periodic action by scheduling calibration operations to be performed cyclically during the duration of use of the beverage dispensing machine. Rather than continuous calibration, the system performs measurements at regular intervals or based on usage conditions, maintaining measurement precision over time while minimizing the time lost to calibration activities.

Inventive Principle:
Principle #19Periodic action

4Device complexity

If the tank has a uniform cross-section, then the calibration process is simpler, but the ability to clearly identify calibration points during liquid withdrawal deteriorates

Engineering Contradiction:
Improvecalibration process complexityVSAvoidcalibration point identification
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies segmentation by dividing the tank into two portions with different cross-sectional areas: a first portion with cross-section S1 and a second portion with cross-section S2. This segmentation creates distinct linear segments in the weight versus time curve during liquid withdrawal, with clearly identifiable intersection points that serve as precise calibration references, thereby improving calibration point identification while maintaining reasonable process complexity.

Inventive Principle:
Principle #1Segmentation

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 method enables precise and consistent measurement of liquid volume in the tank and distributed volume, reducing the need for frequent and costly recalibrations, ensuring accurate liquid dispensing according to user recipes.

Implementation Method 1

a weight sensor arranged between the reservoir and the frame to determine and transmit to the control device a value representative of the weight of the liquid present in the reservoir

Methodology Applied
Scientific EffectWeight sensing:

Data Source

PatentEP4151961B1Method for calibrating a weight sensor arranged on the tank of a beverage dispensing machine
Publication Date: 2024.07.03 SEB SA
  • EP4151961B1 patent drawingFigure 1
  • EP4151961B1 patent drawingFigure 2
  • EP4151961B1 patent drawingFigure 3

AI summary

The invention relates to a method for calibrating a weight sensor (30) arranged on a beverage dispensing machine (1) which includes a reservoir (10) mounted movably in a frame (2). According to the invention, the reservoir (10) has a first portion (12) and a second portion (13) and said method comprises the steps: - Determine a slope P1 of a first straight line Dr1 corresponding to the withdrawal of the first portion (12) and a slope P2 of a second straight line Dr2 corresponding to the withdrawal of the second portion (13), - Determine, from the point of intersection PI of the first and second lines, a value V1 measured by the weight sensor (30), - Calibrate the weight sensor (30) by associating the measured value V1 with the weight of the liquid contained in the first portion (12).