Dishwasher Pump Pressure Sensing for Non-Electronic Fill Control
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Solution Overview
Problem
Existing techniques for detecting a water fill level in dishwashers are either costly or require complex electronic systems, and there is a need for non-electronic methods to accurately control the water fill level.
Innovation Solution
Monitoring the output pressure of the recirculation pump to determine when to deactivate the fill valve, using an electro-mechanical or electronic pressure sensor to ensure an appropriate water fill level is reached, and employing a pressure wave damper to stabilize pressure measurements and prevent false triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current gradients of the pump motor are used to detect cavitation, then water fill level detection is effective, but the pump motor rotor requires costly fine balancing to avoid detection errors
Solution Approach 1:
The patent replaces the mechanical approach of monitoring pump motor current gradients with a non-contact acoustic sensing system. A microphone or acoustic sensor detects cavitation sounds directly from the pump, eliminating the need for precise mechanical balancing of the rotor while maintaining cavitation detection accuracy.
Solution Approach 2:
The patent introduces an acoustic intermediary (sound waves) as the mediator between the cavitation event and the detection system. Instead of directly measuring electrical current changes that are sensitive to mechanical imbalances, the system uses acoustic signals that propagate through the fluid and can be detected without contact, serving as an intermediate carrier of cavitation information.
2Measurement precision
If electronic systems are used to detect water fill level, then detection accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent replaces complex electronic water level sensing systems with a simplified acoustic detection method. By listening for cavitation sounds that naturally occur when the pump operates without sufficient water, the system achieves accurate water fill level detection using relatively simple acoustic sensors rather than complex electronic level sensors or control systems.
Solution Approach 2:
The system uses the pump's own operational characteristics (cavitation sounds) as the detection signal. The pump essentially detects its own water level condition through the acoustic emissions it produces during cavitation, eliminating the need for separate electronic water level sensing systems.
3Loss of energy
If water conservation techniques are applied to reduce water consumption, then energy and water usage are optimized, but the risk of pump cavitation increases
Solution Approach 1:
The patent implements a feedback control system where acoustic sensors continuously monitor for cavitation sounds during pump operation. When cavitation is detected, the system provides feedback to the control mechanism to adjust water flow or pump operation, preventing damage while allowing water conservation techniques to be applied during normal operation.
Solution Approach 2:
The system provides protective cushioning against cavitation damage by detecting early signs of cavitation through acoustic monitoring. This allows preventive action to be taken before severe cavitation occurs, protecting the pump while enabling aggressive water conservation measures during normal 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 method allows for accurate and cost-effective detection of the water fill level, ensuring the dishwasher operates with the right amount of water without the need for expensive electronic adjustments, thereby optimizing energy and water usage.
Implementation Method 1
Monitoring the output pressure of the recirculation pump to determine when to deactivate the fill valve
Implementation Method 2
employing a pressure wave damper to stabilize pressure measurements and prevent false triggers
Data Source
AI summary
A method for operating a dishwasher system, including monitoring an output pressure of at least one recirculation pump in the dishwasher system, and deactivating at least one fill valve in the dishwasher system when the output pressure satisfies at least one predefined criteria.