Dishwasher Clean Indicator Control Using Door Position Feedback
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Solution Overview
Problem
Existing dishwasher indicators can be deactivated prematurely, leading to dirty dishes being added to clean ones, as they do not accurately monitor the completion of the washing cycle.
Innovation Solution
A dishwasher appliance with a sensor to monitor door openings and time in the unlatched position, using threshold values to determine if the appliance is fully emptied, and adjust the indicator accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the indicator is deactivated immediately after the washing cycle ends, then the appliance can quickly indicate readiness for new loading, but the indicator may turn off prematurely before the door is fully closed, leading to dirty dishes being added to clean ones
Solution Approach 1:
The system continuously monitors door position sensor feedback after the washing cycle ends. The indicator remains active until the sensor confirms the door has been fully closed a specific number of times, providing real-time feedback about the actual loading status. This prevents premature deactivation and ensures the indicator accurately reflects when the appliance is ready for new loading.
Solution Approach 2:
The system pre-sets threshold values for door closure counts and monitoring time periods before the washing cycle ends. These preliminary parameters define the conditions under which the indicator will deactivate, ensuring that the appliance waits for proper door closure patterns before indicating readiness, thus preventing contamination of clean dishes.
2Reliability
If the indicator remains activated for an extended period after the washing cycle, then dirty dishes can be safely added, but the indicator may stay on too long even after the appliance is ready for new loading
Solution Approach 1:
The door position sensor provides continuous feedback during and after the washing cycle. The system counts door closures and monitors the time the door remains closed. When the threshold values are met (specific number of closures within a time period), the indicator deactivates, signaling the appliance is ready for new loading. This feedback mechanism prevents both premature and delayed deactivation.
Solution Approach 2:
The system uses adjustable threshold parameters (door closure count, time period) that can be modified based on different operating conditions. By changing these parameters dynamically, the system optimizes the indicator deactivation timing to balance between ensuring cleanliness and minimizing idle time.
3Measurement precision
If the system monitors door position continuously with multiple threshold checks, then the indicator deactivation timing is accurate, but the system complexity increases
Solution Approach 1:
A simple door position sensor provides feedback to the controller, which counts door closures and monitors time. The controller compares these counts against pre-set thresholds and deactivates the indicator when conditions are met. This feedback loop achieves accurate monitoring without requiring complex sensors or multiple interconnected components.
Solution Approach 2:
The system uses the existing door mechanism and a simple sensor to automatically monitor and determine when the appliance is ready for new loading. The door itself serves as the monitoring element - its closure pattern provides the information needed to control the indicator, eliminating the need for separate complex monitoring systems.
Data Source
AI summary
A dishwasher appliance includes a tub; a door, a sensor, and an indicator. The dishwasher performs an operation including determining a completion of a washing cycle, turning on the indicator, accumulating a first value relating to a first characteristic and a second value relating to a second characteristic, comparing the first accumulated value against a first threshold value and the second accumulated value against a second threshold value, determining that at least one of the first or second accumulated value is greater than its respective threshold value, and implementing a responsive action after determining that the at least one of the first or second accumulated value is greater than its respective threshold value.