Alternating pump direction for fluid detection
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Solution Overview
Problem
Existing methods for detecting water presence in domestic appliance pumps, such as dishwashers, face challenges in accurately determining overfill situations and filter clogging due to variations in pump parameters like age, temperature, and type, requiring precise current or power level measurements.
Innovation Solution
A method involving operating a pump in two directions and comparing the responses based on measured parameters like motor current or power, allowing for water detection without needing absolute current levels or accounting for parameter variations, by identifying asymmetry in responses indicating water presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absolute current level detection is used to determine filter clogging, then water presence detection is achieved, but the system becomes sensitive to parameter variations such as age, temperature, and pump type
Solution Approach 1:
The patent applies asymmetry by comparing pump responses in opposite rotation directions. When water is present, the pump exhibits asymmetric current consumption patterns between forward and reverse rotation due to hydraulic resistance differences. This asymmetric comparison eliminates the need for absolute current threshold calibration and makes the detection independent of pump age, temperature, and type variations.
Solution Approach 2:
The patent changes the detection parameter from absolute current level to differential current response between opposite rotation directions. By measuring the difference in current consumption when the pump rotates in opposite directions, the system transforms a parameter-sensitive measurement into a relative measurement that cancels out environmental and aging effects.
2Measurement precision
If pressure sensors are used for overfill detection, then water presence detection is achieved, but the device complexity increases
Solution Approach 1:
The patent makes the pump serve a dual function: both fluid transport and water presence detection. By analyzing the pump's own operational parameters (current consumption) during normal operation, the system eliminates the need for separate pressure sensors or level sensors, thereby reducing device complexity while maintaining detection accuracy.
Solution Approach 2:
The patent implements multi-functionality by enabling the pump to perform both its primary function (fluid circulation) and a secondary detection function (water presence sensing). The same pump motor and control system are used for both pumping and detection, eliminating the need for dedicated sensing hardware.
3Difficulty of detecting and measuring
If circulation pump current monitoring is used to detect filter clogging, then detection capability is achieved, but the system requires precise current level thresholds that vary with operating conditions
Solution Approach 1:
The patent uses asymmetric response comparison between opposite pump rotation directions to detect filter clogging. Instead of monitoring absolute current levels against fixed thresholds, the system measures the asymmetry in current consumption patterns when the pump rotates forward versus reverse. This asymmetric measurement naturally compensates for filter resistance changes without requiring recalibration.
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 effectively determines water presence in domestic appliance pumps without requiring precise motor current or power level knowledge, simplifying the detection process and eliminating the need to consider parameter variations, thus improving the accuracy of overfill and filter clogging detection.
Implementation Method 1
comparing the first response and the second response, and determining the presence of water in the pump based on the comparison of the first and second response
Data Source
AI summary
A domestic appliance and a method at the domestic appliance for detecting presence of process water in a pump of the domestic appliance are provided. The method of detecting process water in a pump of a domestic appliance may include operating the pump to rotate in a first direction, recording a first response of the pump rotating in the first direction based on a measured pump operation parameter, operating the pump to rotate in a second direction, and recording a second response of the pump rotating in the second direction based on the measured pump operation parameter. The method may further include comparing the first response and the second response, and determining the presence of water in the pump based on the comparison of the first and second response.