Induction-Heated Drum Dryer With Single-Sensor Dryness Detection
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Solution Overview
Problem
Conventional laundry treating apparatuses face challenges in accurately determining the drying ending timing without a circulating duct, particularly when sensors are contaminated by detergents, washing water, or lint, and require multiple temperature sensors for effective dryness detection, which complicates manufacturing and increases the risk of sensor malfunction.
Innovation Solution
A laundry treating apparatus using a single temperature sensor to detect dryness by monitoring the temperature difference between the drum and washing water, with a safety system that includes multiple safety devices to prevent overheating and ensure safe operation, even in abnormal conditions, and a control method that utilizes natural convection to determine the drying target load and ending timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple temperature sensors are installed to detect dryness accurately, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The single temperature sensor performs multiple functions: detecting washing water temperature during washing cycle and detecting condensed water temperature during drying cycle. The processor distinguishes between these functions based on the operational cycle, eliminating the need for separate sensors for different measurement purposes.
Solution Approach 2:
The system changes the interpretation parameter of the temperature sensor based on the operational cycle. During washing, the sensor measures washing water temperature; during drying, it measures condensed water temperature. This parameter switching allows one sensor to provide accurate dryness detection without requiring multiple sensors.
2Measurement precision
If humidity sensor is used to detect dryness, then measurement precision is improved, but reliability deteriorates due to contamination from detergent, washing water, and lint
Solution Approach 1:
Instead of placing a humidity sensor directly in the contaminated environment inside the drum, the system uses temperature sensors positioned in the tub to detect condensed water temperature. This intermediary approach indirectly measures dryness without exposing sensors to direct contamination from detergent, washing water, and lint.
Solution Approach 2:
The system replaces the direct humidity sensing mechanism with a thermal-based indirect measurement system. By measuring the temperature difference between condensed water and ambient air, the processor calculates dryness levels without requiring physical contact between sensors and contaminated laundry materials.
3Measurement precision
If circulation duct is installed for dryness detection, then measurement precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention extracts the essential measurement function from the complex circulation duct system. By removing the circulation duct requirement and using simple temperature sensors positioned in the tub, the system achieves accurate dryness detection through condensed water temperature monitoring, significantly simplifying the manufacturing process.
Solution Approach 2:
The system utilizes the natural condensation process that occurs during drying to provide the measurement medium. The condensed water formed during normal drying operation serves as the measurement target, eliminating the need for separate circulation ducts and active air sampling systems.
4Productivity
If induction heater is used for heating, then productivity is improved, but reliability deteriorates due to overheating risks and safety concerns
Solution Approach 1:
The processor continuously monitors the temperature detected by the temperature sensor during induction heater operation and adjusts the heater power accordingly. When the condensed water temperature reaches the target temperature or rises abnormally, the processor reduces or stops heater operation, providing real-time feedback control that prevents overheating while maintaining high drying efficiency.
Solution Approach 2:
The system establishes predetermined safety temperature thresholds and control algorithms before operation begins. The processor is programmed with target temperatures and maximum safe operating limits, creating a pre-established safety buffer that prevents the induction heater from causing overheating or safety incidents 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 solution allows for accurate determination of drying ending timing and load using a single sensor, reduces the risk of sensor malfunction, and enhances safety by actively controlling the induction heater and using redundant safety devices, thereby improving the reliability and efficiency of the drying process.
Implementation Method 1
an induction heater disposed on the tub and configured to heat an outer circumferential face of the drum contacting the heater
Implementation Method 2
humid steam evaporated in heat exchange between the heated drum and the object is condensed into the condensed water inside the tub
Data Source
AI summary
A laundry treating apparatus includes a tub, a drum for receiving an object therein, an induction heater for heating an outer circumferential face of the drum, a motor for rotating the drum, and a power supply for supplying power from an external power source to the laundry treating apparatus, a relay for interrupting current to be applied from the power supply to the induction heater via an electrical wire, a processor connected to the relay via a control wire and configured to control an operation of the relay and to control an operation of the induction heater and an operation of the motor, and a first safety device disposed at the control wire to interrupt a control signal to be applied from the processor to the relay. The first safety device operates in response to a temperature change thereof.