Dishwasher with at least one heating element for heating the rinsing liquid
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dishwasher heating systems require complex control algorithms to determine faults, often relying on absolute temperature measurements without considering differential temperatures, leading to inefficiencies and potential overheating due to lack of medium flow detection.
Innovation Solution
A dishwasher design featuring a second temperature sensor coupled differently to the heating conductor, allowing for differential temperature measurement between sensors, which simplifies fault detection and automatic heating shutdown by indicating when the medium flow is insufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature sensor is used to monitor heating conductor temperature, then the device complexity is reduced, but the reliability of fault detection deteriorates due to inability to detect medium flow issues
Solution Approach 1:
The temperature monitoring function is segmented into two independent sensors: a first temperature sensor (T1) thermally coupled to the heating conductor for direct temperature measurement, and a second temperature sensor (T2) monitoring the medium temperature. This segmentation allows independent evaluation of each sensor's function and enables detection of medium flow problems through temperature difference analysis, resolving the contradiction between device simplicity and fault detection reliability.
2Measurement precision
If complex control algorithms with time derivatives and standard curve comparisons are used, then the measurement precision of fault detection is improved, but the device complexity increases
Solution Approach 1:
The complex computational approach (time derivatives, standard curve comparisons) is replaced by a simpler thermal physics-based approach. The system uses the natural thermal coupling between the heating conductor and medium, monitored by two temperature sensors, to detect faults. The evaluation compares actual temperature differences against expected thermal behavior during heating phases, eliminating the need for complex mathematical processing while maintaining reliable fault detection.
3Ease of operation
If absolute temperature limits are used for heating shutdown, then the ease of operation is improved, but the reliability of overheating prevention deteriorates due to inability to detect pump dry-running
Solution Approach 1:
The system implements feedback control by continuously monitoring the temperature difference between T1 (heating conductor temperature) and T2 (medium temperature). During normal operation with adequate medium flow, the temperature difference remains within expected ranges. When the pump runs dry or medium flow is insufficient, the temperature difference exceeds thresholds, triggering heating shutdown. This feedback mechanism maintains operational simplicity while significantly improving overheating prevention 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 solution enables reliable detection of pump dry-running conditions and prevents overheating by automatically switching off the heating when a predetermined temperature difference is exceeded, reducing hardware and software complexity and eliminating the need for pressure switches and amperage queries.
Implementation Method 1
a first temperature sensor (15), which is located in the vicinity of a heat conductor (17)
Implementation Method 2
a second temperature sensor (16), which is located at a distance from the first temperature sensor (15) and from the heat conductor (17), which is associated with the first temperature sensor (15)
Implementation Method 3
with at least one heating conductor (17) by which water and/or washing-up liquid can be heated
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The dishwasher has a washing tub that is filled with water and/or washing solution (S) for cleaning dish. A heater (13) comprising heating conductors (17) is arranged surrounding the washing tub for heating the washing solution and/or water. A temperature sensor (15) is provided in vicinity of the heating conductors and another temperature sensor (16) having different thermal coupling efficiency is provided opposite to the heating conductors, and temperature difference between measured values of the temperature sensors is determined.