Clothes Dryer Burner Delay Control to Reduce Overheating Damage
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Solution Overview
Problem
Conventional clothes dryers cause damage to clothes due to overheating, especially in the second half of the drying operation, as they cannot distinguish the type and amount of clothes, leading to excessive temperature maintenance after moisture reduction.
Innovation Solution
A clothes dryer with a heating control unit that introduces a delay time between stopping and restarting the heating unit based on exhaust temperature, gradually lowering the peak temperature inside the drum, using a non-adjustable burner and setting upper limits for delay time to prevent excessive cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the burner is re-ignited immediately when exhaust temperature reaches the re-ignition temperature, then the drying operation continues efficiently, but the interior temperature of the drum remains high causing damage to clothes
Solution Approach 1:
The burner is operated in periodic cycles rather than continuously. The control unit ignites the burner for a predetermined period, then stops it for a predetermined period, creating periodic heating action. This allows the drum temperature to rise during heating phases and decrease during cooling phases, preventing continuous high-temperature damage to clothes while maintaining drying progress through alternating thermal cycles.
Solution Approach 2:
The control unit pre-determines the ignition and stop periods of the burner before the drying operation begins. By establishing predetermined time intervals for burner operation and cessation, the system proactively manages temperature fluctuations to prevent overheating damage before it occurs, rather than reacting to temperature conditions in real-time.
2Object-affected harmful factors
If the burner is stopped to lower the interior temperature of the drum, then clothes damage is reduced, but the drying operation time increases
Solution Approach 1:
The burner operates in periodic cycles with predetermined ignition periods followed by predetermined stop periods. This periodic operation allows the system to balance temperature management with drying efficiency, where heating phases advance the drying process and cooling phases prevent clothes damage, optimizing both time and temperature control.
Solution Approach 2:
The control unit changes the operational parameters of the burner by switching between ignition and stop states at predetermined intervals. This parameter change approach allows dynamic adjustment of thermal input to the system, balancing the need for heat to drive evaporation with the need to limit maximum temperature to protect clothes fibers.
3Productivity
If the burner operates continuously at high temperature, then drying speed is maximized, but the clothes surface temperature rises excessively causing damage
Solution Approach 1:
The burner is operated periodically with predetermined ignition and stop periods rather than continuously. This creates alternating phases of high-temperature drying (advancing the drying speed) and cooling (reducing clothes surface temperature), thereby achieving both fast drying and temperature protection through time-based thermal cycling.
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 approach ensures uniform drying while reducing damage from overheating, maintaining desired drying performance without increasing costs or complexity, and reducing the number of burner ignitions and extinctions, thus enhancing machine durability.
Implementation Method 1
a heating unit for heating the drying air supplied to the drum
Implementation Method 2
an exhaust temperature detection unit for detecting a temperature of the drying air exhausted from the drum
Data Source
AI summary
Disclosed is a clothes dryer. The clothes dryer includes a drum; an air supply/exhaust unit for supplying/exhausting drying air to/from the drum; a burner for heating the drying air; a temperature sensor for detecting an exhaust temperature; and a heating control unit for performing a temperature adjustment process of stopping the burner when the exhaust temperature reaches an upper limit temperature and restarting the burner after a time point when the exhaust temperature decreases to a re-ignition temperature. The heating control unit has a delay time inserting portion, which inserts a delay time between the time when the exhaust temperature decreases to a lower limit temperature and the time when the burner is restarted. The delay time is increased every time the temperature adjustment process is repeated intermittently.