Dishwasher Duct Pressure Control for Mixed-Load Cleaning
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Solution Overview
Problem
Household dishwashers often fail to optimally match the cleaning action to the load, leading to either inadequate cleaning of heavily soiled items or excessive mechanical stress on delicate items.
Innovation Solution
The dishwasher features a duct system that adjusts pressure difference between spray elements based on the rotational speed of the circulating pump, allowing for a normal and intensive cleaning mode, ensuring gentle cleaning for sensitive items and intense cleaning for heavily contaminated ones without additional actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the circulating pump operates at high rotational speed for intensive cleaning, then cleaning effectiveness is improved, but mechanical stress on delicate items increases
Solution Approach 1:
The duct system is designed with different branch characteristics (first branch vs second branch) that create different pressure responses to pump speed changes. The first branch is configured to provide proportional pressure increase at high speeds, while the second branch provides over-proportional pressure increase, enabling zone-specific cleaning intensity adjustment without additional actuators
Solution Approach 2:
The system dynamically adapts cleaning intensity by varying the circulating pump's rotational speed. The control device adjusts pump speed based on detected load characteristics, enabling the duct system to transition between different pressure difference regimes (proportional vs over-proportional) to match cleaning requirements
2Object-affected harmful factors
If the circulating pump operates at low rotational speed for gentle cleaning, then mechanical stress on delicate items is reduced, but cleaning effectiveness on heavily soiled items becomes insufficient
Solution Approach 1:
Different regions of the rinsing chamber receive differently pressurized rinsing liquid through the branched duct system. The second spray element receives higher pressure (over-proportional increase) for intensive cleaning of heavily soiled items, while the first spray element receives lower pressure (proportional increase) for gentle cleaning of delicate items
Solution Approach 2:
The system changes the pressure difference parameter dynamically by adjusting pump rotational speed. The duct system's hydraulic characteristics cause the pressure difference to change differently than pump speed, creating two operational ranges that provide different cleaning intensities without additional control components
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 solution enables simultaneous intensive cleaning of heavily contaminated items and gentle cleaning of sensitive items, avoiding dirt residue and mechanical damage, while maintaining a simple and reliable design.
Implementation Method 1
a function describing a pressure difference, which is defined as a pressure of the rinsing liquid in the second spray element less a pressure of the rinsing liquid in the first spray element
Implementation Method 2
a circulating pump for circulating a rinsing liquid present in the rinsing chamber
Data Source
AI summary
A dishwasher, wherein a duct system has a function describing a pressure difference in dependence on the rotational speed of the circulating pump and having a lower rotational speed range in which the pressure difference changes at most in proportion to the rotational speed of the circulating pump and an upper rotational speed range in which the pressure difference changes more than in proportion to the rotational speed of the circulating pump; and wherein the control device has a first rinsing program in which the circulating pump is operated at a normal cleaning rotational speed for normal cleaning of the rinsing stock and a second rinsing program in which the circulating pump is operated at an intensive cleaning rotational speed higher than the normal cleaning rotational speed and lying in the upper rotational speed range for intensive cleaning of the rinsing stock.