Household Appliance Water Detection Using Dual Temperature Sensors
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Solution Overview
Problem
Existing methods for detecting water levels in household appliances, such as dishwashers, are not very accurate and reliable, leading to potential damage from running dry, as they rely on flow meters, pressure sensors, or temperature monitoring which increase costs and are not effective in preventing overheating.
Innovation Solution
A method using a first and second temperature sensor to monitor temperature changes in separate spaces within a household appliance, where the heating element heats the liquid, allowing for comparison of temperature behaviors to determine if a sufficient amount of liquid is present, thereby preventing the heating element from operating without sufficient water and diagnosing pump functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a flow meter or pressure sensor is used to detect water presence, then water level detection capability is provided, but the total cost increases and additional water flow is required for element operation
Solution Approach 1:
The patent replaces mechanical flow meters and pressure sensors with a thermal-based detection system using temperature sensors and heating elements. The system detects water presence by measuring temperature changes in the air space above water, substituting mechanical measurement components with a thermal field-based detection method that reduces device complexity and cost.
Solution Approach 2:
The patent introduces air as an intermediary medium between the water and the temperature sensor. Instead of directly measuring water properties or pressure, the system measures temperature changes in the air space above the water, which indirectly indicates water presence and level, simplifying the detection mechanism.
2Reliability
If temperature monitoring is used to detect water presence, then detection capability is provided, but accuracy and reliability are insufficient to prevent running dry
Solution Approach 1:
The patent divides the detection system into two separate temperature sensors positioned at different locations: one in the air space above water and another near the heating element. By comparing temperature changes from both sensors, the system achieves more reliable water level detection and prevents running dry conditions through cross-validation of temperature behaviors.
Solution Approach 2:
The system continuously monitors temperature changes from both sensors and uses this feedback to determine water presence and prevent heating operation when water is insufficient. The control logic adjusts heating operation based on real-time temperature comparison, creating a closed-loop feedback system that reliably prevents running dry conditions.
3Ease of manufacture
If conventional temperature monitoring methods are used, then simple implementation is achieved, but the system cannot reliably distinguish between temperature changes caused by water and other factors
Solution Approach 1:
The patent segments the temperature measurement function into two separate sensors positioned at different locations with different functions: one sensor monitors ambient air temperature changes above water, while the other monitors temperature near the heating element. This segmentation allows the system to distinguish between temperature changes caused by water presence versus other environmental factors through comparative analysis.
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 method provides a simple and reliable way to determine if a sufficient amount of liquid is present, preventing damage to the appliance and ensuring proper operation by comparing temperature changes between the two spaces, thus enhancing the control of household appliance operations.
Implementation Method 1
a first temperature sensor arranged within the first space... The first temperature sensor may be used for detecting and monitoring temperature changes in the first space. The temperature changes measured by the first temperature sensor may be caused by a liquid supplied to the first space.
Implementation Method 2
a heating element arranged to heat the liquid in the second space... the heating element is arranged to enable transfer of heat energy from the heating element to a liquid supplied to the second space
Implementation Method 3
a second temperature sensor arranged at the heating element... the second temperature sensor may register, i.e. measure temperature changes of the heating element during heating of the liquid in the second space. The second temperature sensor may also register temperature changes at the heating element caused by the liquid supplied to the second space.
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A method (100) for controlling operation of a household appliance (1) is provided. The method (100) comprises: supplying (101) a liquid to a first space (3), determining (103) a first behaviour (TB1) of temperature measured by a first temperature sensor (11) during supplying (101) of the liquid to the first space (3), supplying (105) the liquid to a second space (5) by activating a pump (7) in order to transport the liquid from the first space (3) to the second space (5), determining (107) a second behaviour (TB2) of temperature measured by a second temperature sensor (13) during supplying (105) of the liquid to the second space (5), and determining (109) if a sufficient amount of the liquid has been supplied to the second space (5) or not based on the second behaviour (TB2) evaluated with respect to the first behaviour (TB1). Further, a household appliance (3) is provided.