Method of determining whether process water is present in a circulation pump of an appliance for washing and rinsing goods, and appliance and computer program therewith
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Solution Overview
Problem
Existing washing appliances, such as dishwashers, require additional sensors like flow sensors, pressure sensors, and float switches to detect process water in circulation pumps, increasing complexity and cost.
Innovation Solution
A method and appliance that determine the presence of process water in a circulation pump by measuring the operating current at different speeds, calculating the difference or quotient between minimum and maximum load values, and comparing it to predetermined thresholds, eliminating the need for traditional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensors (flow sensors, pressure sensors, float switches) are used to detect process water in circulation pumps, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The circulation pump serves dual functions: it both circulates process water and acts as its own detection device. By measuring the pump's own power consumption at different speeds, the system determines process water presence without requiring external sensors. The pump's motor controller measures power draw, and when process water is detected, the controller adjusts pump speed accordingly, making the pump self-diagnosing and self-regulating.
Solution Approach 2:
The patent replaces mechanical detection systems (float switches, pressure sensors) with an electrical measurement approach. Instead of using physical sensors to detect process water, the system measures electrical power consumption of the pump motor at different operating speeds. This substitution of mechanical detection with electrical measurement simplifies the system while maintaining detection capability.
2Reliability
If traditional sensors are installed to monitor circulation pump conditions, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The pump motor controller performs multiple functions: it controls pump speed, measures power consumption, detects process water presence, and adjusts operation accordingly. By making the controller multi-functional, the system eliminates the need for separate detection sensors, reducing component count and manufacturing cost while maintaining reliable process water detection capability.
3Measurement precision
If multiple sensors are used to detect process water, then measurement precision is improved, but ease of operation and maintenance deteriorates
Solution Approach 1:
The patent extracts the detection function from separate physical sensors and integrates it into the pump's power measurement system. By taking out the detection capability from dedicated sensors and embedding it in the motor controller's existing power measurement infrastructure, the system achieves accurate process water detection while simplifying operation and maintenance, as there are fewer separate components to operate and service.
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
Effectively determines the presence of process water in circulation pumps without using traditional sensors, reducing complexity and cost while maintaining accuracy.
Implementation Method 1
measuring a minimum load of the circulation pump at a predetermined first speed, measuring a maximum load of the circulation pump at a predetermined second speed
Data Source
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AI summary
The invention relates to a method of determining whether process water is present in a circulation pump of an appliance for washing and rinsing goods, an appliance performing the method, and a computer program for performing the method steps. The method of determining whether process water is present in a circulation pump (21) of an appliance (1) for washing and rinsing goods comprises measuring a minimum value of a property representing load of the circulation pump (21) at a predetermined first speed, measuring a maximum value of a property representing load of the circulation pump (21) at a predetermined second speed, the second speed being higher than the first speed, determining a relation between said minimum value and said maximum value, and determining, from said relation, whether process water is present in the circulation pump (21).