Dishwasher Pump Sequencing to Prevent Reverse Flow Re-Soiling
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Solution Overview
Problem
Existing methods for draining fluid from aquiferous household devices, such as dishwashing machines, often result in re-soiling due to reverse flow causing filter cake loosening, leading to increased energy consumption as both circulation and drain pumps operate simultaneously.
Innovation Solution
The method involves reducing the speed of the circulation pump from maximum to minimum speed before starting the drain pump to prevent pressure surges, allowing fluid to be pumped out without re-soiling, and optimizing pump operations to minimize energy consumption and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both circulation pump and drain pump are operated simultaneously to prevent reverse flow and filter cake loosening, then reliability of filter separation is improved, but energy consumption increases
Solution Approach 1:
The circulation pump speed is reduced from maximum to minimum before the drain pump starts operation. This preliminary speed reduction prevents pressure surges that would cause reverse flow and filter cake loosening, eliminating the need for simultaneous pump operation and reducing energy consumption
2Productivity
If circulation pump operates at maximum speed during draining to maintain fluid circulation, then cleaning effectiveness is maintained, but pressure surges occur causing reverse flow and filter cake loosening
Solution Approach 1:
The circulation pump speed is dynamically adjusted based on the operational phase. During draining, the speed is reduced from maximum to minimum before the drain pump starts, and then further reduced to zero when the drain pump is operating. This dynamic speed adjustment prevents pressure surges and reverse flow while maintaining system productivity
3Stress or pressure
If circulation pump speed is rapidly reduced from maximum to minimum before drain pump start-up, then pressure surge prevention is improved, but fluid level reduction may be insufficient to prevent reverse flow
Solution Approach 1:
The circulation pump speed is reduced in advance before the drain pump starts operation. This preliminary action allows the fluid level to gradually reduce without causing pressure surges, preventing both reverse flow and filter cake loosening while maintaining adequate fluid levels for continuous operation
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 prevents re-soiling by controlling pump speeds to manage fluid levels and flow, reducing energy usage and noise emissions while ensuring efficient fluid removal.
Implementation Method 1
The speed of the circulation pump is lowered from a maximum speed at least to a minimum speed before start-up of the drain pump substantially without pressure surges
Data Source
AI summary
In a method for pumping a fluid out of an aquiferous household device such as a dishwashing machine, a drain pump and a circulation pump are operated at least partially simultaneously to ensure that, in the event of an abrupt stop of the circulation pump, reverse flow that may cause filter cake formed by separating soiling and particles to loosen resulting in their re-soiling of the items to be cleaned. The speed of the circulation pump is lowered from a maximum speed to at least a minimum speed substantially without pressure surges before startup of the drain pump.