Washing Machine Additive Dispensing Using Conductivity Feedback
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Solution Overview
Problem
Conventional washing machine detergent dispensers struggle to accurately dispense detergent volumes due to varying viscosities of different detergents, leading to inconsistent results.
Innovation Solution
A smart dispense system that uses a conductivity sensor to measure the electrical conductivity of the wash fluid and adjusts the dispensing amount based on historical averages, ensuring accurate detergent dosing by detecting changes in detergent type or concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed time-based smart dispense procedure is used to dispense detergent through a venturi, then the dispensing process is simple and fast, but the detergent volume accuracy deteriorates due to varying detergent viscosities
Solution Approach 1:
The system measures the actual detergent volume dispensed and compares it to the target volume, then adjusts the dispense time accordingly. This feedback loop compensates for viscosity variations by learning the actual dispense rate for each detergent batch, ensuring accurate dosing while maintaining fast operation.
Solution Approach 2:
The system changes the dispense time parameter dynamically based on the measured detergent volume. By adjusting this key parameter according to actual dispense performance, the system adapts to different detergent viscosities and maintains volume accuracy without changing the physical dispensing mechanism.
2Manufacturing precision
If the dispense time is extended to compensate for high viscosity detergent, then the detergent volume accuracy improves, but the dispensing time increases and productivity decreases
Solution Approach 1:
The system measures the actual detergent volume dispensed and uses this feedback to adjust future dispense times. This eliminates the need for conservative extended dispense times by providing real-time data on actual dispense rates, optimizing both accuracy and speed.
Solution Approach 2:
The system transitions from static fixed-time dispensing to dynamic adaptive dispensing. The dispense time becomes a variable parameter that adjusts based on measured performance, allowing the system to optimize for each detergent batch rather than using a fixed conservative time.
3Measurement precision
If a conductivity sensor is added to measure wash fluid conductivity for detecting detergent changes, then the detergent type detection accuracy improves, but the device complexity increases
Solution Approach 1:
The system replaces complex mechanical or visual inspection methods with an electrical conductivity measurement approach. The conductivity sensor provides a simple electrical measurement that effectively detects detergent type and concentration changes, substituting potential mechanical complexity with straightforward electrical sensing.
Solution Approach 2:
The conductivity sensor acts as an intermediary that translates detergent properties into measurable electrical signals. This intermediary device simplifies the detection process by providing a direct electrical measurement of detergent characteristics without requiring complex analysis of the detergent itself.
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
The system ensures precise detergent dispensing, compensating for different detergent viscosities and characteristics, thereby maintaining consistent wash quality across various cycles.
Implementation Method 1
a conductivity sensor for measuring an electrical conductivity of the wash fluid collected in the wash tub
Implementation Method 2
The detergent dispenser commonly dispenses the detergent using a venturi effect
Data Source
AI summary
A washing machine appliance includes a water supply configured to selectively dispense wash fluid into a wash tub, a bulk dispenser for selectively adding a wash additive to the wash fluid, and a conductivity sensor for measuring an electrical conductivity of the wash fluid collected in the wash tub. A controller is configured to determine that a requested cycle has a target set of cycle parameters, determine that the bulk dispenser has been refilled, obtain a historical average conductivity of cycles performed using the target set of cycle parameters, obtain a conductivity of the wash fluid during performance of the requested cycle using the conductivity sensor, determine that the conductivity is different than the historical average conductivity, and implement a responsive action in response to determining that the conductivity is different than the historical average conductivity.