Dishwasher Intensive Spray Detection Using Pump Current Differential
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Solution Overview
Problem
Existing dishwashers face challenges in determining the activation state of intensive spray devices without additional sensors, leading to potential errors due to changes in pump flow caused by aging components, contamination, or fluctuating power grids, which can affect cleaning performance.
Innovation Solution
A control device in the dishwasher detects pump currents while applying rinsing liquor to different spray devices, forms a current difference value, and determines the switching state of the intensive spray device using stored previous difference values and a class difference value, allowing for adaptive washing program adjustments without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor is installed in the wash cabinet to detect the switching position of the intensive spray device, then the detection accuracy is improved, but the device complexity and cost increase, and the sensor is prone to failure due to harsh conditions
Solution Approach 1:
The patent uses pump current as an intermediary parameter to indirectly detect the switching state of the intensive spray device. Instead of directly sensing the valve position or spray device state with a sensor in the harsh wash cabinet environment, the system measures the electrical current consumed by the pump motor, which changes characteristically when the intensive spray device is activated. This intermediary measurement approach avoids the need for fragile sensors in the wash cabinet while still achieving reliable detection.
Solution Approach 2:
The patent replaces a mechanical/electrical sensing system (sensor in wash cabinet) with an electrical measurement system (current measurement at the pump motor). By measuring the electrical current characteristics of the pump motor under different spray device configurations, the system substitutes a complex sensor-based detection mechanism with a simpler electrical measurement approach that is more reliable and easier to implement.
2Device complexity
If fixed threshold values are used to determine the switching state, then the detection process is simplified, but false detections occur due to gradual changes in pump flow from aging components and contamination
Solution Approach 1:
The patent performs preliminary characterization of the pump system by storing reference current values and differential values obtained during a calibration phase when the intensive spray device is known to be in a specific state. These reference values are stored in memory and serve as a baseline for future comparisons. By establishing this preliminary reference data, the system adapts to the specific pump characteristics of each dishwasher, accounting for variations due to manufacturing tolerances, aging, and contamination.
Solution Approach 2:
The patent changes the detection parameter from fixed absolute current thresholds to dynamic differential values that represent the difference in current between different spray device configurations. Instead of using a single fixed threshold that may become obsolete due to aging, the system uses relative measurements (differential values) that remain valid over time. The calibration process establishes these differential values specific to each pump system, making the detection robust against gradual parameter drift.
3Measurement precision
If the pump current is measured at high resolution to detect small changes, then the detection precision is improved, but the energy consumption and measurement complexity increase
Solution Approach 1:
The patent applies partial measurement by only measuring pump current during specific phases of the washing cycle when the spray devices are actively operating. Instead of continuous high-resolution monitoring, the system takes measurements only when needed (during spray operations), reducing overall energy consumption and measurement complexity. The measurement is performed at a resolution sufficient to detect the characteristic current differences between spray device states without excessive precision requirements.
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 enables accurate detection of the intensive spray device's state, reducing false detections and improving washing performance by accounting for slow changes and power fluctuations, ensuring consistent cleaning results without the need for additional sensors.
Implementation Method 1
The control device (150) is configured to detect a first pump current (I0) during the application of rinsing liquor to the first spray device (112) and to detect a second pump current (I1, I2) during the application of rinsing liquor to the second spray device (122)
Data Source
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AI summary
The invention relates to a dishwasher (1), in particular a domestic dishwasher, comprising a controller (150) for running a wash program for washing washware arranged in a wash chamber (4) of the dishwasher (1), a first spray unit (112) and a second spray unit (122) which can selectively be supplied with a wash liquor (F) via a pump device (140) in order to form a respective wash zone, and an intensive spray device (132) which is paired with the first (112) or the second spray device (122) and can be brought into an activated state or a deactivated state by means of a switch valve (133). The controller (150) is designed to detect a first pump flow (I0) while the first spray device (112) is being supplied with wash liquor (F) and to detect a second pump flow (I1, I2) while the second spray device (122) is being supplied with wash liquor (F) in order to form a current differential value (ΔI0) on the basis of the detected first (I0) and second pump flow (I1, I2) and in order to ascertain a current switch state of the intensive spray device (132) on the basis of the current differential value (ΔI0), a number of stored earlier differential values (ΔI1 – ΔI8), and a specified class differential value (K), wherein the controller (150) is designed to adapt the wash program on the basis of the ascertained current switch state.