Dishwasher Zeolite Drying Sensor Layout for Low-Cost Moisture Detection
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Solution Overview
Problem
Dishwashing machines with drying units face challenges in precise control of the drying process due to varying loads and temperature fluctuations, requiring expensive temperature sensors for accurate humidity detection near the heat source.
Innovation Solution
A temperature sensor is placed upstream of the drying unit and downstream of the washing compartment in the air circulation loop, allowing for the use of simpler, cost-effective components like NTC resistors to detect significant temperature changes, reducing the need for precise absolute temperature detection and enabling multiple functions such as control and fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature detection is performed downstream of the absorption column or in the water-absorbing material itself, then the moisture content detection precision is improved, but the device complexity and cost increase due to requiring specially designed expensive temperature sensors
Solution Approach 1:
The patent introduces an intermediary approach by detecting temperature at a location upstream of the absorption column where the temperature is lower. Instead of directly measuring temperature in the high-temperature zone requiring special sensors, the system measures temperature in a cooler zone and uses this information to infer moisture content, thereby avoiding the need for expensive high-temperature sensors while maintaining measurement capability
Solution Approach 2:
The patent creates a temperature measurement copy by measuring temperature at a different location (upstream of absorption column) rather than directly at the heat source. This copied measurement point has lower temperature requirements, allowing use of standard sensors while still providing information about the drying process through the temperature profile of circulating air
2Measurement precision
If temperature detection is performed downstream of the absorption column, then the actual drying conditions are accurately reflected, but the manufacturing cost increases due to requiring expensive temperature sensors
Solution Approach 1:
The patent employs inexpensive standard temperature sensors (such as NTC thermistors) instead of expensive specially-designed high-temperature sensors. By positioning the sensor where temperatures are lower and using standard off-the-shelf components, the manufacturing cost is significantly reduced while the sensor can be easily replaced if needed
Solution Approach 2:
The system uses an intermediary measurement location upstream of the absorption column where standard sensors can operate. This intermediary point provides sufficient information about drying conditions without requiring direct measurement in the high-temperature zone, thus enabling use of cheaper standard components
3Measurement precision
If absolute temperature detection near the heat source is performed, then precise humidity detection is achieved, but the device complexity and sensor requirements increase
Solution Approach 1:
Instead of measuring temperature directly at the heat source where conditions are harsh, the patent inverts the approach by measuring temperature upstream of the absorption column where conditions are milder. This reverse positioning makes measurement easier with standard sensors while still enabling humidity detection through analysis of the temperature profile in the air circulation loop
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 simplifies the control of the drying process, reduces manufacturing costs, and allows for more precise monitoring of drying conditions and fault detection, offering additional user options and reducing effort in device control.
Implementation Method 1
temperature detection of the circulating air
Implementation Method 2
the characteristic of the zeolite whereby heat is emitted upon the absorption of water as a consequence of the absorption reaction
Implementation Method 3
heat is emitted upon the absorption of water as a consequence of the absorption reaction
Data Source
AI summary
A dishwashing machine is provided having a washing compartment, a drying unit that includes an absorption column with a reversibly dehydratable drying agent, and having an air circulation loop through the washing compartment and the drying unit. A temperature sensor is arranged in front of the drying unit and to the rear of the washing compartment with respect to the direction of the flow of air circulating in the air circulation loop.