Capacitive Level Sensor Distance Compensation

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Solution Overview

Problem

Existing devices with removable containers for liquids or granular materials face challenges in precise level measurement due to issues like jamming and cleanliness problems with floats, and inaccuracies with capacitive sensors caused by varying distances between the sensor and container.

Innovation Solution

A device equipped with a capacitive level sensor and an inductive distance sensor that determines the fill level by measuring capacitance and distance values, using a processing unit to calculate the precise fill level, and an inductive distance sensor with a conductive structure to influence the electromagnetic field for accurate distance measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a float is used to determine the fill level, then the fill level can be indicated by the float's position, but the float can get stuck leading to inaccurate readings and requires time-consuming cleaning

Engineering Contradiction:
Improvefill level measurement accuracyVSAvoidfloat operation reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical float system with a capacitive level sensor that uses electrical fields to detect liquid level. The sensor measures capacitance changes between a capacitive element and the liquid surface, eliminating moving mechanical parts that can jam or require cleaning, while maintaining accurate fill level detection

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

2Ease of operation

If a capacitive level sensor is used to measure fill level in a removable container, then level measurement is enabled, but varying distances between the sensor and container cause measurement inaccuracies

Engineering Contradiction:
Improveremovable container operationVSAvoidfill level measurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the measured capacitance value is used to calculate the distance between the sensor and container. This distance information is then fed back to compensate for its effect on the capacitance measurement, allowing the system to distinguish between capacitance changes due to liquid level versus those due to distance variations, thereby maintaining measurement accuracy

Inventive Principle:
Principle #23Feedback

3Ease of operation

If the container is made removable for filling or emptying, then convenience is improved, but precise level measurement becomes more difficult due to distance variations

Engineering Contradiction:
Improvecontainer removal and installationVSAvoidfill level measurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical level measurement mechanisms with an electrical field-based capacitive sensor system that can accurately measure level regardless of container position. Combined with distance compensation algorithms, this enables precise measurement while maintaining the convenience of removable containers

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

Solution Approach 2:

The patent changes the measurement approach from direct mechanical contact to electrical field measurement, and dynamically adjusts the interpretation of capacitance values based on measured distance parameters. This allows the system to adapt to varying container positions while maintaining measurement precision

Inventive Principle:
Principle #35Parameter changes

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 precise, cost-effective, and convenient measurement of the fill level in removable containers, reducing errors and maintenance costs while maintaining design flexibility.

Implementation Method 1

a capacitive level sensor (113) mounted on the housing (110), configured to determine a capacitance value, wherein the capacitance value depends on the fill level of (liquid or granular) material in the container (120)

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

The distance sensor comprises an inductive distance sensor. This inductive distance sensor can include a sensor unit mounted on the housing, configured to generate an electromagnetic field

Methodology Applied
Scientific EffectElectromagnetic field: Electromagnetic Induction

Data Source

PatentEP3405756B1Device adapted for determination of a fluid level of a removable reservoir
Publication Date: 2020.03.11 BOSCH SIEMENS HAUSGERATE GMBH
  • EP3405756B1 patent drawingFigure 1~2

AI summary

The invention relates to an appliance (100) comprising a housing (110) and a container (120) that can be decoupled from the housing (110). The appliance (100) also comprises a capacitive filling level sensor (113) arranged on the housing (110), which is designed to determine a capacity value that depends on a filling level of matter (121) in the container (120). The appliance (100) further comprises a distance sensor (112, 122) which is designed to determine a distance value that depends on a distance between the filling level sensor (113) and the container (120). Furthermore, the appliance (100) comprises a processing unit (111) which is designed to determine a value for the filling level on the basis of the capacity value and on the basis of the distance value.