Tapered Dishwasher Air Trap for Accurate Water Level Sensing
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Solution Overview
Problem
Conventional water level controllers in dishwashers are plagued by inaccuracies due to temperature-induced pressure changes in the air trap, leading to unnecessary water loading or draining, which affects energy consumption and machine efficiency.
Innovation Solution
The air trap is designed with a cross-section that decreases from the bottom upwards, reducing sensitivity to volume changes caused by temperature variations, thereby minimizing reading errors in water level detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional cylindrical air trap is used, then the structure is simple and manufacturing is easy, but the water level detection accuracy deteriorates due to temperature-induced pressure changes
Solution Approach 1:
The air trap is designed with a curved, non-cylindrical shape where the cross-sectional area varies along its length. Specifically, the air trap has a larger cross-section at the bottom and a smaller cross-section at the top, creating a tapered or bulbous geometry that compensates for thermal expansion effects on pressure measurement
Solution Approach 2:
The invention changes the geometric parameter of the air trap from a uniform cylindrical shape to a variable cross-section shape. This geometric parameter change allows the air trap to maintain accurate pressure readings despite temperature variations, as the varying cross-sectional areas compensate for the volume changes of trapped air
2Volume of moving object
If the overflow position is set close to the correct water level, then the useful loading space is maximized, but the measurement precision deteriorates due to temperature-induced level variations
Solution Approach 1:
The curved air trap geometry enables the system to achieve both compact dimensions and accurate measurement by distributing the measurement range over a non-linear geometric profile, allowing the overflow to be positioned closer to the operating level without sacrificing precision
3Reliability
If the air trap volume changes with temperature, then the pressure switch detects pressure changes, but the measurement precision deteriorates due to false level readings
Solution Approach 1:
The invention changes the geometric parameters of the air trap to create a temperature-compensating design. The variable cross-section is specifically designed so that pressure changes due to thermal expansion are minimized or compensated, maintaining reliable pressure detection while ensuring accurate water level measurement across temperature variations
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 design enhances precision, allowing for a more compact machine with increased useful loading space and reduced energy waste by accurately maintaining the optimal water level, while maintaining simplicity, inexpensiveness, and applicability to various machines.
Implementation Method 1
the air inside it remains trapped and undergoes a pressure change proportional to the water level
Implementation Method 2
the mass of air present in the air trap tends to expand when heated and to contract when it cools, causing corresponding pressure changes
Data Source
Figure 1~2
Figure 3
AI summary
A water level controller of a dishwasher comprises an air trap (1) connected to a pressure switch adapted to control the opening and closing of valves for the loading and draining of the water, the air trap (1) being shaped in such a way that its cross-section decreases from the bottom upwards, for example with a pyramidal shape.