Optical Reservoir Level Sensing for Removable Wash Aid Alignment

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Solution Overview

Problem

Washing machines lack an efficient and cost-effective method to sense the liquid level in removable reservoirs for washing aids, leading to potential misalignment and increased costs due to the need for complex sensor mechanisms and electrical connectors.

Innovation Solution

A liquid level sensing system using an optical sensor assembly aligned with the insertion axis of a removable reservoir, which includes a window for light reflection and a triangular prism for internal reflections, allowing for precise liquid level detection without complex float-type devices and electrical connectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If float-type sensor mechanisms are used in removable reservoirs, then liquid level detection is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improveliquid level detection accuracyVSAvoidsensor mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical float-type sensor system with an optical sensing system. The optical sensor assembly uses light transmission through the reservoir wall to detect liquid level, eliminating the need for mechanical floating components inside the removable reservoir. This substitution reduces mechanical complexity while maintaining detection accuracy.

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

Solution Approach 2:

The patent extracts the sensing electronics from the removable reservoir and places them in the fixed appliance body. Only a simple optical window remains in the removable reservoir, while the complex electronic components are separated into the appliance's fixed structure. This extraction simplifies the removable reservoir design for easier manufacturing and cleaning.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If electrical connectors are added to removable reservoirs for sensor operation, then sensing capability is enabled, but manufacturing cost and assembly complexity increase

Engineering Contradiction:
Improveliquid level sensing capabilityVSAvoidreservoir manufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent extracts all electrical components from the removable reservoir, leaving only passive optical elements (the window). The active sensing electronics are completely removed from the removable component and placed in the fixed appliance body, eliminating the need for electrical connectors in the reservoir.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces electrical connection methods with optical transmission through the reservoir wall. Instead of using electrical connectors to power sensors in the removable reservoir, the system uses light transmission through the transparent or translucent reservoir wall to enable sensing without electrical connections.

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

3Ease of manufacture

If optical sensor is separated from removable reservoir, then reservoir cost is reduced, but misalignment between sensor and reservoir may occur

Engineering Contradiction:
Improvereservoir manufacturing costVSAvoidoptical alignment accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces the appliance body as an intermediary structure that provides precise mounting for the optical sensor. The fixed appliance body serves as a stable reference frame with built-in alignment features (such as guide rails or positioning ribs) that ensure the optical sensor is correctly positioned relative to the removable reservoir's optical window, eliminating alignment issues that would arise from trying to precision-align two separate removable components.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Measurement precision

If complex sensor mechanisms are used in removable reservoirs, then liquid level detection is achieved, but ease of cleaning and loading is reduced

Engineering Contradiction:
Improveliquid level detectionVSAvoidcleaning and loading simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent extracts all complex sensing mechanisms from the removable reservoir, leaving only a simple optical window and basic structural elements. This extraction makes the removable reservoir much easier to clean (no internal sensor components to contaminate) and simpler to load with liquid detergent, while the fixed appliance body contains all the complex electronics that require power and data connections.

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution provides a low-cost, accurate, and sensitive liquid level sensing system that prevents misalignment errors and reduces the cost of removable reservoirs, enabling multilevel height detection and distinguishing between washing aid presence and reservoir absence.

Implementation Method 1

a window receiving light along the axis and reflecting light from an interior surface of the window adapted to contact liquid and an optical sensor assembly affixed with respect to the reservoir receptacle to transmit light along the axis into the window and to receive and measure light reflected along the axis from the window

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

The reflecting surface may be in the form of a triangular prism having first and second adjacent faces forming the reflecting surface and projecting into the volume and the incoming light and reflected light may pass perpendicularly through a third face of the triangular prism provided by an outer wall of the receptacle

Methodology Applied
Scientific EffectInternal reflection: Total Internal Reflection

Data Source

PatentEP4036534B1Optical level sensor for wash aid removable container
Publication Date: 2024.01.31 ILLINOIS TOOL WORKS INC
  • EP4036534B1 patent drawingFigure 1~2
  • EP4036534B1 patent drawingFigure 3~4
  • EP4036534B1 patent drawingFigure 5~6

AI summary

A liquid level sensing system provides a removable reservoir incorporating a reflective surface that can be interrogated by a stationary optical sensor in a receptacle receiving the removable reservoir. The optical sensor may detect the presence of the liquid within the reservoir without connection to the reservoir simplifying the process of making the reservoir removable while still allowing sensing of its contents. By aligning the optical axis with the insertion axis of the reservoir sensitive optical alignment problems are minimized.