Induction-Heated Laundry Drum Dryness Detection With One Temperature Sensor
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Solution Overview
Problem
Conventional laundry treating apparatuses face challenges in accurately determining the drying ending timing without a circulating duct, as humidity sensors can be contaminated by detergents, washing water, or lint, and require multiple temperature sensors, making them unreliable and difficult to manufacture.
Innovation Solution
A laundry treating apparatus using a single temperature sensor to detect dryness by monitoring the washing-water temperature and preventing overheating of the induction heater, with a safety device to autonomously cut off power in abnormal conditions, and employing natural convection to condense moisture for accurate drying control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a humidity sensor is used to detect dryness, then drying end timing can be detected, but the sensor is contaminated by detergent, washing water or lint making it unreliable
Solution Approach 1:
The patent removes the humidity sensor from the system entirely and replaces it with a temperature-based detection method. The drying end timing is determined by monitoring temperature changes of the drum and air using temperature sensors, thereby extracting the detection function from the contaminated humidity sensor environment to a cleaner temperature measurement approach.
Solution Approach 2:
The patent substitutes the electrical/humidity sensing mechanism with a thermal measurement mechanism. Instead of using a humidity sensor that directly contacts contaminated air, the system uses temperature sensors to measure temperature differences, which indirectly indicate drying progress through the relationship between temperature and moisture content.
2Measurement precision
If temperature sensors are installed near inlet and outlet of condensing duct to detect dryness, then drying end can be determined, but three or more temperature sensors are required making manufacture difficult
Solution Approach 1:
The patent merges the functions of multiple temperature sensors into a single temperature sensor. By positioning one temperature sensor to monitor the drum temperature and another to monitor air temperature, the system combines dryness detection and overheating prevention functions into a unified temperature-based control approach, reducing the total number of sensors required.
Solution Approach 2:
The temperature sensors serve multiple functions simultaneously: they detect drying progress by monitoring temperature changes, prevent overheating of the induction heater, and provide data for determining both dryness and load amount. This multi-functionality eliminates the need for separate sensors for each measurement purpose.
3Measurement precision
If a circulation duct is used for air circulation and condensation, then dryness can be indirectly determined by temperature difference, but the apparatus becomes complex requiring separate condensing duct and drying duct
Solution Approach 1:
The patent extracts the air circulation and condensation functions from the system, eliminating the need for a complex circulation duct structure. Instead of using a separate condensing duct and drying duct system, the invention directly monitors temperature changes in the existing drum and air space to determine drying end timing, simplifying the overall apparatus structure.
4Productivity
If induction heater is used to heat drum directly, then drying efficiency is improved, but overheating may occur requiring active control and safety devices
Solution Approach 1:
The patent implements a feedback control system where temperature sensors continuously monitor the drum and air temperatures, and the controller adjusts the induction heater operation accordingly. When the temperature difference between drum and air exceeds a predetermined threshold, the controller reduces or stops heater operation, creating a closed-loop feedback mechanism that maintains safety while maximizing drying efficiency.
Solution Approach 2:
The patent incorporates safety devices including a thermal fuse and temperature sensor positioned beforehand to prevent overheating accidents. These safety components are installed in advance to detect abnormal temperature conditions and automatically cut off power to the induction heater before dangerous overheating can occur, providing a cushion against potential failures.
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 effective determination of drying ending timing and load amount using a single sensor, reducing sensor malfunction risks and ensuring safety by actively controlling the induction heater and using multiple safety devices to prevent accidents.
Implementation Method 1
an induction heater disposed on the tub and heating 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.