Washing Machine Tub Fill-Level Sensing Without Pressure Lines
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Solution Overview
Problem
Existing methods for determining the fill level of liquid in washing machines are sensitive to pressure peaks and require complex components, making them inefficient and costly.
Innovation Solution
A fill level sensor is placed directly in the lower region of the washing machine tub, allowing for direct measurement of the pressure column formed by the liquid, reducing sensitivity to pressure peaks and eliminating the need for pressure transmission components, with an elastic membrane protecting the sensor and enhancing pressure transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure line is arranged in a drain hose with a fill level sensor above the tub to detect fill level via air column changes, then the fill level can be determined indirectly, but the device becomes more complex and more sensitive to pressure peaks from washing mechanics
Solution Approach 1:
The invention extracts the fill level sensor from its traditional position above the tub and places it directly in the lower region of the tub. This eliminates the need for complex pressure transmission components like pressure lines and air columns, while also reducing sensitivity to pressure peaks from washing mechanics. The sensor directly measures liquid pressure at the bottom of the tub, simplifying the overall device structure.
Solution Approach 2:
The invention introduces an elastic membrane as an intermediary between the liquid and the sensor element. This membrane protects the sensor from direct contact with liquid while still transmitting pressure changes accurately. It serves as a mediator that allows the sensor to function in a harsh environment without being damaged, while maintaining measurement precision.
2Reliability
If the fill level sensor is arranged above the tub to measure air column pressure, then the sensor is protected from liquid contact, but the device requires additional pressure transmission components and becomes more sensitive to pressure peaks
Solution Approach 1:
The elastic membrane serves as a protective intermediary that shields the sensor element from direct liquid contact while maintaining reliable pressure transmission. This resolves the contradiction by allowing the sensor to be positioned in the liquid environment without compromising its protection or reliability.
Solution Approach 2:
The sensor is pre-positioned in the lower region of the tub where it can directly measure liquid pressure from the beginning of the washing process. This eliminates the need for complex pressure transmission paths that are susceptible to pressure peaks, providing reliable measurements throughout the washing cycle without requiring additional protective mechanisms.
3Ease of manufacture
If pressure transmission components are used to connect the sensor to the liquid, then the sensor can be positioned away from the liquid, but the device becomes more complex and costly
Solution Approach 1:
The invention removes unnecessary pressure transmission components from the system by placing the sensor directly in the liquid environment. Only the essential elastic membrane remains to protect the sensor element, significantly simplifying the device structure and reducing manufacturing costs compared to traditional systems with multiple pressure transmission components.
Solution Approach 2:
The sensor housing and membrane support structure are merged into a single integrated component that can be directly installed in the tub. This consolidation eliminates the need for separate pressure lines, connectors, and mounting structures, reducing both device complexity and manufacturing costs while maintaining sensor protection and functionality.
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 approach results in a cost-effective and insensitive method for determining the fill level, less affected by washing mechanics and capable of precise measurement, using piezoresistive, capacitive, or inductive sensors to convert pressure signals into analog outputs.
Implementation Method 1
an elastic and pressure-transmitting membrane which is connected to the housing of the level sensor and is in direct contact with the liquid
Implementation Method 2
the detection part of the filling level sensor comprises a flat sensor element which is covered by an elastic and pressure-transmitting membrane
Implementation Method 3
the fill level is measured by direct measurement of the pressure column formed by the liquid in the tub
Implementation Method 4
using piezoresistive, capacitive, or inductive sensors to convert pressure signals into analog outputs
Implementation Method 5
using piezoresistive, capacitive, or inductive sensors to convert pressure signals into analog outputs
Implementation Method 6
using piezoresistive, capacitive, or inductive sensors to convert pressure signals into analog outputs
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a device for determining a fill level (16) of liquid (14) within a suds tub (10) of a washing machine (1), having a fill level sensor (18) by means of which a pressure value generated by the liquid (14) can be determined, the fill level sensor (18) having at least one detection part (20) disposed in a lower area (22) of the suds tub (10) that is covered by the liquid (14) during the washing process.