Dishwasher Pump Speed Sequencing to Prevent Re-Soiling
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Solution Overview
Problem
Existing methods for draining water from household appliances like dishwashers result in re-soiling due to reverse flow, which causes filter cake detachment and re-contamination, leading to increased energy consumption.
Innovation Solution
The method involves reducing the speed of the circulating pump from maximum to minimum speed before starting the drain pump, ensuring no pressure surges occur, and then stopping the circulating pump to prevent re-soiling, allowing the drain pump to operate alone to remove liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both the circulation pump and drain pump are operated simultaneously to prevent reverse flow, then re-soiling of items is prevented, but energy consumption increases
Solution Approach 1:
The circulation pump speed is dynamically adjusted from maximum to minimum in steps before the drain pump starts, and then to zero when the drain pump operates. This dynamic speed control prevents reverse flow and re-soiling while avoiding the energy waste of running both pumps at full power simultaneously.
Solution Approach 2:
The operating parameters of the circulation pump are changed by reducing its speed in controlled steps. The pump transitions from maximum speed to minimum speed, then to zero speed, matching the operational phases of the drain pump. This parameter adjustment prevents harmful reverse flow while optimizing energy consumption.
2Use of energy by moving object
If the circulation pump is stopped abruptly to save energy, then energy consumption decreases, but pressure surges occur causing filter cake detachment and re-soiling
Solution Approach 1:
The circulation pump speed is reduced in preliminary steps from maximum to minimum before the drain pump starts operation. This preliminary speed reduction prevents pressure surges and filter cake detachment that would occur with abrupt stopping, while still preparing the system for energy-efficient drain pump operation.
Solution Approach 2:
Instead of abrupt stopping, the circulation pump undergoes a dynamic speed reduction process in multiple steps. The speed transitions smoothly from maximum to minimum to zero, preventing pressure surges and filter cake detachment while optimizing energy consumption during the draining phase.
3Productivity
If the circulation pump runs at maximum speed during draining, then liquid is removed quickly, but pressure surges cause flow reversal and re-soiling
Solution Approach 1:
The circulation pump operates at maximum speed initially for quick liquid removal, then dynamically reduces speed in steps as the drain pump operates. This dynamic adjustment maintains high productivity during the initial phase while preventing pressure surges and re-soiling during the draining phase.
Solution Approach 2:
The circulation pump operates in different speed phases: maximum speed at the beginning for quick liquid removal, then minimum speed during drain pump operation to prevent re-soiling, and finally zero speed when draining is complete. This periodic action optimizes both productivity and reliability.
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 the liquid flow, reducing energy consumption, and minimizing the duration of the pumping process while maintaining efficient operation and noise reduction.
Implementation Method 1
the speed of the circulating pump is reduced from a maximum speed at least down to a minimum speed before the drain pump is started up, essentially without pressure surges
Implementation Method 2
a drain pump is provided, which can be connected to a domestic waste water disposal system
Data Source
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AI summary
The invention relates to a method for pumping a fluid out of an aquiferous household device (GS), in particular a household dishwashing machine, wherein water is conveyed out of said aquiferous household device at least temporarily by the operation of a drain pump (LP) and water is circulated at least temporarily by the operation of a circulation pump (UP). According to the invention, the speed of said circulation pump (UP) is lowered from a maximum speed (nMax) at least to a minimum speed (nMin) before startup of said drain pump (LP) substantially without pressure surges.